eaogorg.files.wordpress.com€¦ · Web viewGEOCHEMISTRY ARTICLES – May 2020. Analytical...

GEOCHEMISTRY ARTICLES – May 2020

Analytical Chemistry

Adams, F., Adriaens, M., 2020. The metamorphosis of analytical chemistry. Analytical and Bioanalytical Chemistry 412, 3525-3537.

Beyssac, O., 2020. New Trends in Raman Spectroscopy: From High-Resolution Geochemistry to Planetary Exploration. Elements 16, 117-122.

Cha, J.W., Park, S., 2020. Extraction of individual spectra from mixture data based on high-resolution 13C–13C NMR correlation spectrum and decode procedure. Analytical Chemistry 92, 7037-7044.

Fumoto, E., Sato, S., Takanohashi, T., 2020. Determination of carbonyl functional groups in heavy oil using infrared spectroscopy. Energy & Fuels 34, 5231-5235.

Gilboa, T., Garden, P.M., Cohen, L., 2020. Single-molecule analysis of nucleic acid biomarkers – A review. Analytica Chimica Acta 1115, 61-85.

Liu, Y., Xu, J., Tao, Y., Fang, T., Du, W., Ye, A., 2020. Rapid and accurate identification of marine microbes with single-cell Raman spectroscopy. Analyst 145, 3297-3305.

Nasdala, L., Schmidt, C., 2020. Applications of Raman spectroscopy in mineralogy and geochemistry. Elements 16, 99-104.

Pasteris, J.D., Beyssac, O., 2020. Welcome to Raman spectroscopy: Successes, challenges, and pitfalls. Elements 16, 87-92.

Steele, A., Fries, M.D., Pasteris, J.D., 2020. Geoscience meets biology: Raman spectroscopy in geobiology and biomineralization. Elements 16, 111-116.

Villabona-Estupiñan, S., Rojas-Ruiz, F.A., Pinto-Camargo, J.L., Manrique, E.J., Orrego-Ruiz, J.A., 2020. Characterization of petroleum compounds adsorbed on solids by infrared spectroscopy and mass spectrometry. Energy & Fuels 34, 5317-5330.

Vítek, P., Ascaso, C., Artieda, O., Casero, M.C., Wierzchos, J., 2020. Raman imaging of microbial colonization in rock—some analytical aspects. Analytical and Bioanalytical Chemistry 412, 3717-3726.

Wang, D., Wang, K., Zheng, X., Butterbach-Bahl, K., Díaz-Pinés, E., Chen, H., 2020. Applicability of a gas analyzer with dual quantum cascade lasers for simultaneous measurements of N2O, CH4 and CO2 fluxes from cropland using the eddy covariance technique. Science of The Total Environment 729, 138784.

Zeng, Q., Chen, J., Zhan, C., Lin, Y., Chen, Z., 2020. Fully exploiting the power of 2D NMR J-resolved spectroscopy. Analytical Chemistry 92, 6893-6899.

EXTRACTION METHODS/SAMPLE PREPARATION

Alawani, N.A., Panda, S.K., Lajami, A.R., Al-Qunaysi, T.A., Muller, H., 2020. Characterization of crude oils through alkyl chain-based separation by gel permeation chromatography and mass spectrometry. Energy & Fuels 34, 5414-5425.

Fontanals, N., Borrull, F., Marcé, R.M., 2020. Overview of mixed-mode ion-exchange materials in the extraction of organic compounds. Analytica Chimica Acta 1117, 89-107.

Jin, X., Kaw, H.Y., Li, H., Zhao, W., Zhao, J., Piao, X., Li, D., Jin, D., He, M., 2020. A traceless clean-up method coupled with gas chromatography and mass spectrometry for analyzing polycyclic aromatic hydrocarbons in complex plant leaf matrices. Analyst 145, 3266-3273.

Marrubini, G., Dugheri, S., Cappelli, G., Arcangeli, G., Mucci, N., Appelblad, P., Melzi, C., Speltini, A., 2020. Experimental designs for solid-phase microextraction method development in bioanalysis: A review. Analytica Chimica Acta 1119, 77-100.

Silva, S.R.C., Moncioso, N.A.P., Sad, C.M.S., Tosta, C.L., de Souza, L.M., Cipriano, D.F., Romão, W., Freitas, J.C.C., Kuster, R.M., de Castro, E.V.R., Filgueiras, P.R., 2020. Preparation of a nitrogen oil compound fraction by modified gel silica column chromatography. Energy & Fuels 34, 5652-5664.

Sitterley, K.A., Linden, K.G., Ferrer, I., Thurman, E.M., 2020. Desalting and concentration of common hydraulic fracturing fluid additives and their metabolites with solid-phase extraction. Journal of Chromatography A 1622, 461094.

GAS CHROMATOGRAPHY/GC×GC/GC-MS

Bale, N.J., Koenen, M., Yadav, S., Hopmans, E.C., Villanueva, L., Sinninghe Damsté, J.S., Schouten, S., 2020. Diagnostic amide products of amino lipids detected in the microaerophilic bacteria Lutibacter during routine fatty acid analysis using gas chromatography. Organic Geochemistry 144, 104027.

Berrier, K.L., Reaser, B.C., Pinkerton, D.K., Synovec, R.E., 2019. Examination of the two-dimensional mass channel cluster plot method for gas chromatography – mass spectrometry in the context of the statistical model of overlap. Journal of Chromatography A 1601, 319-326.

Chen, J., Xie, J., Zhang, Z., Wang, F., Hu, J., Li, H., 2020. Rapid and accurate determination of carboxyl groups in carbon materials by headspace gas chromatography. Journal of Chromatography A 1621, 461062.

Delmonte, P., Belaunzaran, X., Ridge, C., Aldai, N., Kramer, J.K.G., 2020. Separation and characterization of products from acidic methanolysis of plasmalogenic lipids by two-dimensional gas chromatography with online reduction. Journal of Chromatography A 1619, 460955.

Domínguez, I., Arrebola, F.J., Vidal, J.L.M., Frenich, A.G., 2020. Assessment of wastewater pollution by gas chromatography and high resolution Orbitrap mass spectrometry. Journal of Chromatography A 1619, 460964.

Duan, L., Ma, A., Meng, X., Shen, G.-a., Qi, X., 2020. QPMASS: A parallel peak alignment and quantification software for the analysis of large-scale gas chromatography-mass spectrometry (GC-MS)-based metabolomics datasets. Journal of Chromatography A 1620, 460999.

Eckhard, T., Wütscher, A., Muhler, M., 2020. Simultaneous analysis of light gases and heavy pyrolyzates evolved from lignite and hard coal by pyrolysis-GC/MS-GC/TCD. Journal of Analytical and Applied Pyrolysis 149, 104833.

Guan, X., Luong, J., Yu, Z., Jiang, H., 2020. Quasi-stop-flow modulation strategy for comprehensive two-dimensional gas chromatography. Analytical Chemistry 92, 6251-6256.

Jaramillo, R., Dorman, F.L., 2020. Thermodynamic modeling of comprehensive two dimensional gas chromatography isovolatility curves for second dimension retention indices based analyte identification. Journal of Chromatography A 1622, 461111.


Li, H.-X., Xie, T.-P., Xie, S.-M., Wang, B.-J., Zhang, J.-H., Yuan, L.-M., 2020. Enantiomeric separation on a homochiral porous organic cage-based chiral stationary phase by gas chromatography. Chromatographia 83, 703-713.

Matyushin, D.D., Sholokhova, A.Y., Karnaeva, A.E., Buryak, A.K., 2020. Various aspects of retention index usage for GC-MS library search: A statistical investigation using a diverse data set. Chemometrics and Intelligent Laboratory Systems 202, 104042.

Read, D.H., Sillerud, C.H., Whiting, J.J., Achyuthan, K.E., 2020. Metal-organic framework stationary phases for one- and two-dimensional micro-gas chromatographic separations of light alkanes and polar toxic industrial chemicals. Journal of Chromatographic Science 58, 389-400.

Trinklein, T.J., Prebihalo, S.E., Warren, C.G., Ochoa, G.S., Synovec, R.E., 2020. Discovery-based analysis and quantification for comprehensive three-dimensional gas chromatography flame ionization detection data. Journal of Chromatography A 1623, 461190.

IMAGING: AFM

Eibinger, M., Ganner, T., Plank, H., Nidetzky, B., 2020. A biological nanomachine at work: Watching the cellulosome degrade crystalline cellulose. ACS Central Science 6, 739-746.

Rao, A., Kumar, S., Annink, C., Le-Anh, D., Ayirala, S.C., Alotaibi, M.B., Siretanu, I., Duits, M.H.G., Yousef, A.A., Mugele, F., 2020. Mineral interfaces and oil recovery: A microscopic view on surface reconstruction, organic modification, and wettability alteration of carbonates. Energy & Fuels 34, 5611-5622.

IMAGING: SEM, TEM, HIM

Azenkeng, A., Mibeck, B.A.F., Kurz, B.A., Gorecki, C.D., Myshakin, E.M., Goodman, A.L., Azzolina, N.A., Eylands, K.E., Butler, S.K., Sanguinito, S., 2020. An image-based equation for estimating the prospective CO2 storage resource of organic-rich shale formations. International Journal of Greenhouse Gas Control 98, 103038.

Bai, G., Zeng, X., Li, X., Zhou, X., Cheng, Y., Linghu, J., 2020. Influence of carbon dioxide on the adsorption of methane by coal using low-field nuclear magnetic resonance. Energy & Fuels 34, 6113-6123.

de la Torre Noetzel, R., Ortega García, M.V., Miller, A.Z., Bassy, O., Granja, C., Cubero, B., Jordão, L., Martínez Frías, J., Rabbow, E., Backhaus, T., Ott, S., García Sancho, L., de Vera, J.-P.P., 2020. Lichen vitality after a space flight on board the EXPOSE-R2 facility outside the International Space Station: Results of the biology and Mars experiment. Astrobiology 20, 583-600.

Deng, Y., Chen, S., Pu, X., Yan, J., 2020. Characteristics and controlling factors of shale oil reservoir spaces in the Bohai Bay Basin. Acta Geologica Sinica - English Edition 94, 253-268.

Elkhatib, O., Chaisoontornyotin, W., Gesho, M., Goual, L., 2020. Nanoscale investigation of asphaltene deposition under capillary flow conditions. Energy & Fuels 34, 5148-5158.

Feng, Z., Hao, F., Zhou, S., Tian, J., Wu, W., Xie, C., Cai, Y., 2020. Pore systems of the different lithofacies of the Longmaxi Formation at depths exceeding 3500 m in the Zigong area, Sichuan Basin. Energy & Fuels 34, 5733-5752.

Gao, Z., Fan, Y., Hu, Q., Jiang, Z., Cheng, Y., 2020. The effects of pore structure on wettability and methane adsorption capability of Longmaxi Formation shale from the southern Sichuan Basin in China. American Association of Petroleum Geologists Bulletin 104, 1375-1399.

Gibson, T.M., Kunzmann, M., Poirier, A., Schumann, D., Tosca, N.J., Halverson, G.P., 2020. Geochemical signatures of transgressive shale intervals from the 811 Ma Fifteenmile Group in Yukon, Canada: Disentangling sedimentary redox cycling from weathering alteration. Geochimica et Cosmochimica Acta 280, 161-184.

Gu, Y., Li, X., Yang, S., Wan, Q., 2020. Microstructure evolution of organic matter and clay minerals in shales with increasing thermal maturity. Acta Geologica Sinica - English Edition 94, 280-289.

Hassan, M.B., Rodelli, D., Benites, M., Abreu, F., Murton, B., Jovane, L., 2020. Presence of biogenic magnetite in ferromanganese nodules. Environmental Microbiology Reports 12, 288-295.

He, Q., Dong, T., He, S., Zhai, G., Guo, X., Hou, Y., Yang, R., Han, Y., 2020. Sedimentological and geochemical characterization of the Upper Permian transitional facies of the Longtan Formation, northern Guizhou Province, southwest China: Insights into paleo-environmental conditions and organic matter accumulation mechanisms. Marine and Petroleum Geology 118, 104446.

Heiss, A.G., Azorín, M.B., Antolín, F., Kubiak-Martens, L., Marinova, E., Arendt, E.K., Biliaderis, C.G., Kretschmer, H., Lazaridou, A., Stika, H.-P., Zarnkow, M., Baba, M., Bleicher, N., Ciałowicz, K.M., Chłodnicki, M., Matuschik, I., Schlichtherle, H., Valamoti, S.M., 2020. Mashes to Mashes, Crust to Crust. Presenting a novel microstructural marker for malting in the archaeological record. PLoS ONE 15, e0231696.

Jauvion, C., Bernard, S., Gueriau, P., Mocuta, C., Pont, S., Benzerara, K., Charbonnier, S., 2020. Exceptional preservation requires fast biodegradation: thylacocephalan specimens from La Voulte-sur-Rhône (Callovian, Jurassic, France). Palaeontology 63, 395-413.

Li, H., Zhou, L., Lu, Y., Yan, F., Zhou, J., Tang, J., 2020. Changes in pore structure of dry-hot rock with supercritical CO2 treatment. Energy & Fuels 34, 6059-6068.

Liu, H., Feng, S., Zhang, S., Jia, C., Xuan, H., Wang, Q., 2020. Analysis of the pore structure of Longkou oil shale semicoke during fluidized bed combustion. Oil Shale 37, 89-103.

Liu, L., Pan, H., Lin, Z., Zhang, S., Qin, Z., Li, J., Huang, G., Wang, L., Li, D., 2020. Reservoir characteristics and logging evaluation of gas−bearing mudstone in the south of North China Plain. Scientific Reports 10, 8791.

Liu, X., Wang, F., Liu, B., Tian, J., Shang, T., Ma, J., Zhang, Z., Zhang, X., 2020. Factors controlling hydrocarbon accumulation in Jurassic reservoirs in the southwest Ordos Basin, NW China. Acta Geologica Sinica - English Edition 94, 467-484.

Roslin, A., Pokrajac, D., Wu, K., Zhou, Y., 2020. 3D pore system reconstruction using nano-scale 2D SEM images and pore size distribution analysis for intermediate rank coal matrix. Fuel 275, 117934.

Shi, G., Kou, G., Du, S., Wei, Y., Zhou, W., Zhou, B., Li, Q., Wang, B., Guo, H., Lou, Q., Li, T., 2020. What role would the pores related to brittle minerals play in the process of oil migration and oil & water two-phase imbibition? Energy Reports 6, 1213-1223.

Sun, W., Zuo, Y., Wu, Z., Liu, H., Zheng, L., Wang, H., Shui, Y., Lou, Y., Xi, S., Li, T., Luo, X., 2020. Pore characteristics and evolution mechanism of shale in a complex tectonic area: Case study of the Lower Cambrian Niutitang Formation in Northern Guizhou, Southwest China. Journal of Petroleum Science and Engineering 193, 107373.

Thompson, M.S., Morris, R.V., Clemett, S.J., Loeffler, M.J., Trang, D., Keller, L.P., Christoffersen, R., Agresti, D.G., 2020. The effect of progressive space weathering on the organic and inorganic components of a carbonaceous chondrite. Icarus 346, 113775.

Wang, T.-T., Ying, G.-G., Shi, W.-J., Zhao, J.-L., Liu, Y.-S., Chen, J., Ma, D.-D., Xiong, Q., 2020. Uptake and translocation of perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) by wetland plants: Tissue- and cell-level distribution visualization with desorption electrospray ionization mass spectrometry (DESI-MS) and transmission electron microscopy equipped with energy-dispersive spectroscopy (TEM-EDS). Environmental Science & Technology 54, 6009-6020.

Wang, Z., Chen, L., Chen, D., Lai, J., Deng, G., Liu, Z., Wang, C., 2020. Characterization and evaluation of shale lithofacies within the lowermost Longmaxi-Wufeng Formation in the Southeast Sichuan Basin. Journal of Petroleum Science and Engineering 193, 107353.

Wilson, R.D., Chitale, J., Huffman, K., Montgomery, P., Prochnow, S.J., 2020. Evaluating the depositional environment, lithofacies variation, and diagenetic processes of the Wolfcamp B and lower Spraberry intervals in the Midland Basin: Implications for reservoir quality and distribution. American Association of Petroleum Geologists Bulletin 104, 1287-1321.

Wu, Y., Lin, C., Yan, W., Liu, Q., Zhao, P., Ren, L., 2020. Pore-scale simulations of electrical and elastic properties of shale samples based on multicomponent and multiscale digital rocks. Marine and Petroleum Geology 117, 104369.

Xia, C., Wilkinson, M., Haszeldine, S., 2020. Petroleum emplacement inhibits quartz cementation and feldspar dissolution in a deeply buried sandstone. Marine and Petroleum Geology 118, 104449.

Yan, Q., Lei, H., Xian, B., Wang, J., Luo, Z., Yang, Z., He, J., Niu, J., Pu, Q., Tian, R., 2020. Influence of source rock properties on the development of authigenic chlorite in conglomerate reservoirs and its significance for oil and gas reservoirs: A case study from the Lower Urhe Formation in the Mahu depression, Junggar Basin. Acta Sedimentologica Sinica 38, 367-378.

Yang, B., Qu, H., Pu, R., Tian, X., Yang, H., Dong, W., Chen, Y., 2020. Controlling effects of tight reservoir micropore structures on seepage ability: A case study of the Upper Paleozoic of the eastern Ordos Basin, China. Acta Geologica Sinica - English Edition 94, 322-336.

Ye, Q., Tong, J., Pang, K., Tian, L., Hu, J., An, Z., 2020. Fossils or sedimentary structures? Carbonaceous spheroids from the shale of the Cryogenian Nantuo Formation in Shengnongjia area, South China. Precambrian Research 345, 105759.

Zakrzewski, M., Schertel, A., Brus, G., Wagner, M., Sciazko, A., Komatsu, Y., Kimijima, S., Kaneko, S., Szmyd, J.S., 2020. A three-dimensional reconstruction of coal microstructure using the Cryo-FIB-SEM technique. Fuel 275, 117919.

Zeng, X., Sun, J., Yan, W., Cui, R., Yuan, W., Yan, W., Dong, X., 2020. New insight into the petrophysical characterization of shales with different fluid saturation states based on nuclear magnetic resonance experiments. Energy & Fuels 34, 5599-5610.

Zhang, X., Liu, C., Li, B., Wu, L., Gui, H., Wang, Z., Zhang, Z., Liang, D., 2020. Characterization of a lacustrine shale reservoir and the evolution of its nanopores: A case study of the Upper Cretaceous Qingshankou Formation in the Songliao Basin, northeastern China. Acta Geologica Sinica - English Edition 94, 337-351.

IMAGING: XRAY CT

Berg, J.S., Duverger, A., Cordier, L., Laberty-Robert, C., Guyot, F., Miot, J., 2020. Rapid pyritization in the presence of a sulfur/sulfate-reducing bacterial consortium. Scientific Reports 10, 8264.

Liang, Z., Wang, C., Zhou, Y., 2020. Analysis of seepage characteristics of complex pore structure rock by digital core method. Chemistry and Technology of Fuels and Oils 55, 756-764.

Maldanis, L., Hickman-Lewis, K., Verezhak, M., Gueriau, P., Guizar-Sicairos, M., Jaqueto, P., Trindade, R.I.F., Rossi, A.L., Berenguer, F., Westall, F., Bertrand, L., Galante, D., 2020. Nanoscale 3D quantitative imaging of 1.88 Ga Gunflint microfossils reveals novel insights into taphonomic and biogenic characters. Scientific Reports 10, 8163.

Wu, P., Li, Y., Liu, W., Liu, Y., Wang, D., Song, Y., 2020. Microstructure evolution of hydrate-bearing sands during thermal dissociation and ensued impacts on the mechanical and seepage characteristics. Journal of Geophysical Research: Solid Earth 125, e2019JB019103.


LIQUID CHROMATOGRAPHY/LC-MS/SFC

Bouwmeester, R., Martens, L., Degroeve, S., 2020. Generalized calibration across liquid chromatography setups for generic prediction of small-molecule retention times. Analytical Chemistry 92, 6571-6578.

Chen, L.C., 2020. A plug-and-play high-pressure ESI source with an emitter at ground potential and its application to high-temperature capillary LC-MS. Journal of the American Society for Mass Spectrometry 31, 1015-1018.

Dascalu, A.-E., Ghinet, A., Chankvetadze, B., Lipka, E., 2020. Comparison of dimethylated and methylchlorinated amylose stationary phases, coated and covalently immobilized on silica, for the separation of some chiral compounds in supercritical fluid chromatography. Journal of Chromatography A 1621, 461053.

Glenne, E., Samuelsson, J., Leek, H., Forssén, P., Klarqvist, M., Fornstedt, T., 2020. Systematic investigations of peak distortions due to additives in supercritical fluid chromatography. Journal of Chromatography A 1621, 461048.

Kadjo, A.F., Dasgupta, P.K., Shelor, C.P., 2020. Optimum cell pathlength or volume for absorbance detection in liquid chromatography: Transforming longer cell results to virtual shorter cells. Analytical Chemistry 92, 6391-6400.

Khvalbota, L., Roy, D., Wahab, M.F., Firooz, S.K., Machyňáková, A., Špánik, I., Armstrong, D.W., 2020. Enhancing supercritical fluid chromatographic efficiency: Predicting effects of small aqueous additives. Analytica Chimica Acta 1120, 75-84.

Lin, J., Tsang, C., Lieu, R., Zhang, K., 2020. Fast chiral and achiral profiling of compounds with multiple chiral centers by a versatile two-dimensional multicolumn liquid chromatography (LC–mLC) approach. Journal of Chromatography A 1620, 460987.

Losacco, G.L., Ismail, O., Pezzatti, J., González-Ruiz, V., Boccard, J., Rudaz, S., Veuthey, J.-L., Guillarme, D., 2020. Applicability of Supercritical fluid chromatography–Mass

spectrometry to metabolomics. II–Assessment of a comprehensive library of metabolites and evaluation of biological matrices. Journal of Chromatography A 1620, 461021.

Ndiripo, A., Albrecht, A., Pasch, H., 2020. Advanced liquid chromatography of polyolefins using simultaneous solvent and temperature gradients. Analytical Chemistry 92, 7325-7333.

Novák, J., Škríba, A., Havlíček, V., 2020. CycloBranch 2: Molecular formula annotations applied to imzML data sets in bimodal fusion and LC-MS data files. Analytical Chemistry 92, 6844-6849.

Reymond, C., Le Masle, A., Colas, C., Charon, N., 2020. Input of an off-line, comprehensive, three-dimensional method (CPC×SFC/HRMS) to quantify polycyclic aromatic hydrocarbons in vacuum gas oils. Analytical Chemistry 92, 6684-6692.

Wang, H., Lhotka, H.R., Bennett, R., Potapenko, M., Pickens, C.J., Mann, B.F., Haidar Ahmad, I.A., Regalado, E.L., 2020. Introducing online multicolumn two-dimensional liquid chromatography screening for facile selection of stationary and mobile phase conditions in both dimensions. Journal of Chromatography A 1622, 460895.

Zhang, H.J., Lv, Y., Chua, C.K., Guo, T., Sun, Z., Zhan, Z., 2020. Mass spectral reconstruction of LC/MS data with entropy minimization. International Journal of Mass Spectrometry 454, 116359.

Zhang, W., Shang, B., Ouyang, Z., Xia, Y., 2020. Enhanced phospholipid isomer analysis by online photochemical derivatization and RPLC-MS. Analytical Chemistry 92, 6719-6726.

MASS SPECTROSCOPY/FT-ICR /ORBITRAP

Cai, D., Wang, X., Chen, J., Li, X., 2020. Molecular characterization of organosulfates in highly polluted atmosphere using ultra-high-resolution mass spectrometry. Journal of Geophysical Research: Atmospheres 125, e2019JD032253.

Challis, J.K., Parajas, A., Anderson, J.C., Asiedu, E., Martin, J.W., Wong, C.S., Ross, M.S., 2020. Photodegradation of bitumen-derived organics in oil sands process-affected water. Environmental Science: Processes & Impacts 22, 1243-1255.

Chen, W., Zhuo, X., He, C., Shi, Q., Li, Q., 2020. Molecular investigation into the transformation of dissolved organic matter in mature landfill leachate during treatment in a combined membrane bioreactor-reverse osmosis process. Journal of Hazardous Materials 397, 122759.

Ding, Y., Shi, Z., Ye, Q., Liang, Y., Liu, M., Dang, Z., Wang, Y., Liu, C., 2020. Chemodiversity of soil dissolved organic matter. Environmental Science & Technology 54, 6174-6184.


Du, Y., Deng, Y., Ma, T., Xu, Y., Tao, Y., Huang, Y., Liu, R., Wang, Y., 2020. Enrichment of geogenic ammonium in quaternary alluvial–lacustrine aquifer systems: Evidence from carbon isotopes and DOM characteristics. Environmental Science & Technology 54, 6104-6114.

Li, H., Zhang, Y., Xu, C., Zhao, S., Chung, K.H., Shi, Q., 2020. Quantitative molecular composition of heavy petroleum fractions: A case study of fluid catalytic cracking decant oil. Energy & Fuels 34, 5307-5316.

Li, J., Wang, Y., Zhou, W., Chen, W., Deng, M., Zhou, S., 2020. Characterization of a new biosurfactant produced by an effective pyrene-degrading Achromobacter species strain AC15. International Biodeterioration & Biodegradation 152, 104959.

Liu, Y., Huang, H., Liu, Q., Xu, X., Cheng, H., 2020. The acid and neutral nitrogen compounds characterized by negative ESI Orbitrap MS in a heavy oil before and after oxidation. Fuel 277, 118085.

Liu, Y., Wan, Y.Y., Zhu, Y., Fei, C., Shen, Z., Ying, Y., 2020. Impact of biodegradation on polar compounds in crude oil: Comparative simulation of biodegradation from two aerobic bacteria using ultrahigh-resolution mass spectrometry. Energy & Fuels 34, 5553-5565.

Merder, J., Freund, J.A., Feudel, U., Hansen, C.T., Hawkes, J.A., Jacob, B., Klaproth, K., Niggemann, J., Noriega-Ortega, B.E., Osterholz, H., Rossel, P.E., Seidel, M., Singer, G., Stubbins, A., Waska, H., Dittmar, T., 2020. ICBM-OCEAN: Processing ultrahigh-resolution mass spectrometry data of complex molecular mixtures. Analytical Chemistry 92, 6832-6838.

Orrego-Ruiz, J.A., Marquez, R.E., Rojas-Ruiz, F.A., 2020. New insights on organic geochemistry characterization of the Putumayo Basin using negative ion electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry. Energy & Fuels 34, 5281-5292.

Pinzon-Espinosa, A., Kanda, R., 2020. Naphthenic acids are key contributors to toxicity of heavy oil refining effluents. Science of The Total Environment 729, 138119.

Qiu, Y., Xu, W., Jia, L., He, Y., Fu, P., Zhang, Q., Xie, Q., Hou, S., Xie, C., Xu, Y., Wang, Z., Worsnop, D.R., Sun, Y., 2020. Molecular composition and sources of water-soluble organic aerosol in summer in Beijing. Chemosphere 255, 126850.


Samarah, L.Z., Khattar, R., Tran, T.H., Stopka, S.A., Brantner, C.A., Parlanti, P., Veličković, D., Shaw, J.B., Agtuca, B.J., Stacey, G., Paša-Tolić, L., Tolić, N., Anderton, C.R., Vertes, A., 2020. Single-cell metabolic profiling: Metabolite formulas from isotopic fine structures in heterogeneous plant cell populations. Analytical Chemistry 92, 7289-7298.

Scholl, P.F., Gray, P.J., Harp, B.P., Delmonte, P., 2020. High resolution mass spectral data from the analysis of copper chlorophylls and copper chlorophyll degradation products in bright green table olives. Data in Brief 30, 105548.



Xie, Q., Li, Y., Yue, S., Su, S., Cao, D., Xu, Y., Chen, J., Tong, H., Su, H., Cheng, Y., Zhao, W., Hu, W., Wang, Z., Yang, T., Pan, X., Sun, Y., Wang, Z., Liu, C.-Q., Kawamura, K., Jiang, G., Shiraiwa, M., Fu, P., 2020. Increase of high molecular weight organosulfate with intensifying urban air pollution in the Megacity Beijing. Journal of Geophysical Research: Atmospheres 125, e2019JD032200.

Zeng, Y., Shen, Z., Takahama, S., Zhang, L., Zhang, T., Lei, Y., Zhang, Q., Xu, H., Ning, Y., Huang, Y., Cao, J., Rudolf, H., 2020. Molecular absorption and evolution mechanisms of PM2.5 brown carbon revealed by electrospray ionization Fourier transform–ion cyclotron resonance mass spectrometry during a severe winter pollution episode in Xi'an, China. Geophysical Research Letters 47, e2020GL087977.

MASS SPECTROSCOPY/OTHER

Bednařík, A., Preisler, J., Bezdeková, D., Machálková, M., Hendrych, M., Navrátilová, J., Knopfová, L., Moskovets, E., Soltwisch, J., Dreisewerd, K., 2020. Ozonization of tissue sections for MALDI MS imaging of carbon–carbon double bond positional isomers of phospholipids. Analytical Chemistry 92, 6245-6250.

Dong, M., Wei, L., González, J.J., Oropeza, D., Chirinos, J., Mao, X., Lu, J., Russo, R.E., 2020. Coal discrimination analysis using tandem laser-induced breakdown spectroscopy and laser ablation inductively coupled plasma time-of-flight mass spectrometry. Analytical Chemistry 92, 7003-7010.

Erba, E., Signor, L., Petosa, C., 2020. Exploring the structure and dynamics of macromolecular complexes by native mass spectrometry. Journal of Proteomics 222, 103799.

Huang, P., Huang, C.-Y., Lin, T.-C., Lin, L.-E., Yang, E., Lee, C., Hsu, C.-C., Chou, P.-T., 2020. Toward the rational design of universal dual polarity matrix for MALDI mass spectrometry. Analytical Chemistry 92, 7139-7145.

Jones, M.A., Cho, S.H., Patterson, N.H., Van de Plas, R., Spraggins, J.M., Boothby, M.R., Caprioli, R.M., 2020. Discovering new lipidomic features using cell type specific fluorophore expression to provide spatial and biological specificity in a multimodal workflow with MALDI imaging mass spectrometry. Analytical Chemistry 92, 7079-7086.

Katz, L., Woolman, M., Talbot, F., Amara-Belgadi, S., Wu, M., Tortorella, S., Das, S., Ginsberg, H.J., Zarrine-Afsar, A., 2020. Dual laser and desorption electrospray ionization

mass spectrometry imaging using the same interface. Analytical Chemistry 92, 6349-6357.

Nakano, Y., Imasaka, T., Imasaka, T., 2020. Generation of a nearly monocycle optical pulse in the near-infrared region and its use as an ionization source in mass spectrometry. Analytical Chemistry 92, 7130-7138.



Xiao, Y., Deng, J., Yao, Y., Fang, L., Yang, Y., Luan, T., 2020. Recent advances of ambient mass spectrometry imaging for biological tissues: A review. Analytica Chimica Acta 1117, 74-88.

Xu, S.-l., Wu, B.-f., Orešič, M., Xie, Y., Yao, P., Wu, Z.-y., Lv, X., Chen, H., Wei, F., 2020. Double derivatization strategy for high-sensitivity and high-coverage localization of double bonds in free fatty acids by mass spectrometry. Analytical Chemistry 92, 6446-6455.

METABOLOMICS/LIPIDOMICS

Álvarez-Muñoz, D., Farré, M. (eds.), 2020. Environmental Metabolomics. Applications in Field and Laboratory Studies to Understand from Exposome to Metabolome. Elsevier, p. 368.


Furse, S., Fernandez-Twinn, D.S., Jenkins, B., Meek, C.L., Williams, H.E.L., Smith, G.C.S., Charnock-Jones, D.S., Ozanne, S.E., Koulman, A., 2020. A high-throughput platform for detailed lipidomic analysis of a range of mouse and human tissues. Analytical and Bioanalytical Chemistry 412, 2851-2862.

González-Fernández, C., Le Grand, F., Bideau, A., Huvet, A., Paul-Pont, I., Soudant, P., 2020. Nanoplastics exposure modulate lipid and pigment compositions in diatoms. Environmental Pollution 262, 114274.

Hayashi, S., Satoh, Y., Ogasawara, Y., Dairi, T., 2020. Recent advances in functional analysis of polyunsaturated fatty acid synthases. Current Opinion in Chemical Biology 59, 30-36.

Heinsvig, P.J., Nielsen, L.S., Lindholst, C., 2020. Development of a method using gas chromatography–mass spectrometry for profiling of oil-based androgenic anabolic steroid products. Journal of Chromatography A 1620, 460989.


Law, K.P., Li, X., Zhang, C., 2020. Lipidomics in archaeal membrane adaptation to environmental stresses and growth conditions: A review of culture-based physiological studies. Science China Earth Sciences 63, 790-807.

Losacco, G.L., Ismail, O., Pezzatti, J., González-Ruiz, V., Boccard, J., Rudaz, S., Veuthey, J.-L., Guillarme, D., 2020. Applicability of Supercritical fluid chromatography–Mass spectrometry to metabolomics. II–Assessment of a comprehensive library of metabolites and evaluation of biological matrices. Journal of Chromatography A 1620, 461021.

Milojevic, T., Weckwerth, W., 2020. Molecular mechanisms of microbial survivability in outer space: A systems biology approach. Frontiers in Microbiology 11, 923. doi: 910.3389/fmicb.2020.00923.


Probst, A.J., Elling, F.J., Castelle, C.J., Zhu, Q., Elvert, M., Birarda, G., Holman, H.-Y.N., Lane, K.R., Ladd, B., Ryan, M.C., Woyke, T., Hinrichs, K.-U., Banfield, J.F., 2020. Lipid analysis of CO2-rich subsurface aquifers suggests an autotrophy-based deep biosphere with lysolipids enriched in CPR bacteria. The ISME Journal 14, 1547-1560.

Quehenberger, J., Pittenauer, E., Allmaier, G., Spadiut, O., 2020. The influence of the specific growth rate on the lipid composition of Sulfolobus acidocaldarius. Extremophiles 24, 413-420.




Archaeological/Art Organic Chemistry

Fulcher, K., Stacey, R., Spencer, N., 2020. Bitumen from the Dead Sea in Early Iron Age Nubia. Scientific Reports 10, 8309.

Grillo, K.M., Dunne, J., Marshall, F., Prendergast, M.E., Casanova, E., Gidna, A.O., Janzen, A., Karega, M., Keute, J., Mabulla, A.Z.P., Robertshaw, P., Gillard, T., Walton-Doyle, C., Whelton, H.L., Ryan, K., Evershed, R.P., 2020. Molecular and isotopic evidence for milk, meat, and plants in prehistoric eastern African herder food systems. Proceedings of the National Academy of Sciences 117, 9793-9799.

Haklay, G., Gopher, A., 2020. Geometry and architectural planning at Göbekli Tepe, Turkey. Cambridge Archaeological Journal 30, 343-357.

Heiss, A.G., Azorín, M.B., Antolín, F., Kubiak-Martens, L., Marinova, E., Arendt, E.K., Biliaderis, C.G., Kretschmer, H., Lazaridou, A., Stika, H.-P., Zarnkow, M., Baba, M., Bleicher, N., Ciałowicz, K.M., Chłodnicki, M., Matuschik, I., Schlichtherle, H., Valamoti, S.M., 2020. Mashes to Mashes, Crust to Crust. Presenting a novel microstructural marker for malting in the archaeological record. PLoS ONE 15, e0231696.

Mattiangeli, V., Cooke, N.P., Ó Maoldúin, R., Sikora, M., Mulhall, I., Bradley, D.G., Teasdale, M.D., 2020. Genomic analysis of Irish bog butter. Journal of Archaeological Science: Reports 31, 102368.

Paris, V., Pizzigoni, A., Adriaenssens, S., 2020. Statics of self-balancing masonry domes constructed with a cross-herringbone spiraling pattern. Engineering Structures 215, 110440.

Stojanovski, D., Roffet-Salque, M., Casanova, E., Knowles, T., Oosterbeek, L., Evershed, R.P., Cruz, A., Thissen, L., Arzarello, M., 2020. Anta 1 de Val da Laje – the first direct view of diet, dairying practice and socio-economic aspects of pottery use in the final Neolithic of central Portugal. Quaternary International 542, 1-8.

Biochemistry


Chevrette, M.G., Gutiérrez-García, K., Selem-Mojica, N., Aguilar-Martínez, C., Yañez-Olvera, A., Ramos-Aboites, H.E., Hoskisson, P.A., Barona-Gómez, F., 2020. Evolutionary dynamics of natural product biosynthesis in bacteria. Natural Product Reports 37, 566-599.

Ciemniecki, J.A., Newman, D.K., 2020. The potential for redox-active metabolites to enhance or unlock anaerobic survival metabolisms in aerobes. Journal of Bacteriology 202, e00797-00719.

Farag, I.F., Biddle, J.F., Zhao, R., Martino, A.J., House, C.H., León-Zayas, R.I., 2020. Metabolic potentials of archaeal lineages resolved from metagenomes of deep Costa Rica sediments. The ISME Journal 14, 1345-1358.

Hassan, N., Anesio, A.M., Rafiq, M., Holtvoeth, J., Bull, I., Haleem, A., Shah, A.A., Hasan, F., 2020. Temperature driven membrane lipid adaptation in glacial psychrophilic bacteria. Frontiers in Microbiology 11, 824. doi: 810.3389/fmicb.2020.00824.

Hill, N.C., Tay, J.W., Altus, S., Bortz, D.M., Cameron, J.C., 2020. Life cycle of a cyanobacterial carboxysome. Science Advances 6, eaba1269.


Moore, E.R., Davie-Martin, C.L., Giovannoni, S.J., Halsey, K.H., 2020. Pelagibacter metabolism of diatom-derived volatile organic compounds imposes an energetic tax on photosynthetic carbon fixation. Environmental Microbiology 22, 1720-1733.


Subramanian, M., Marudhamuthu, M., 2020. Hitherto unknown terpene synthase organization in taxol-producing endophytic bacteria isolated from marine macroalgae. Current Microbiology 77, 918-923.

Wiechmann, A., Ciurus, S., Oswald, F., Seiler, V.N., Müller, V., 2020. It does not always take two to tango: “Syntrophy” via hydrogen cycling in one bacterial cell. The ISME Journal 14, 1561-1570.

Biodegradation

Brown, D.M., Camenzuli, L., Redman, A.D., Hughes, C., Wang, N., Vaiopoulou, E., Saunders, D., Villalobos, A., Linington, S., 2020. Is the Arrhenius-correction of biodegradation rates, as recommended through REACH guidance, fit for environmentally relevant conditions? An example from petroleum biodegradation in environmental systems. Science of The Total Environment 732, 139293.

Goss, M., Li, Z., McLachlan, M.S., 2020. A simple field-based biodegradation test shows pH to be an inadequately controlled parameter in laboratory biodegradation testing. Environmental Science: Processes & Impacts 22, 1006-1013.


Liu, Y., Fang, J., Jia, Z., Chen, S., Zhang, L., Gao, W., 2020. DNA stable-isotope probing reveals potential key players for microbial decomposition and degradation of diatom-derived marine particulate matter. MicrobiologyOpen 9, e1013.

Liu, Y., Wan, Y.Y., Wang, C., Ma, Z., Liu, X., Li, S., 2020. Biodegradation of n-alkanes in crude oil by three identified bacterial strains. Fuel 275, 117897.


Liu, Y., White, H.K., Simister, R.L., Waite, D., Lyons, S.L., Kujawinski, E.B., 2020. Probing the chemical transformation of seawater-soluble crude oil components during microbial oxidation. ACS Earth and Space Chemistry 4, 690-701.

Mei, J., Shen, X., Gang, L., Xu, H., Wu, F., Sheng, L., 2020. A novel lignin degradation bacteria-Bacillus amyloliquefaciens SL-7 used to degrade straw lignin efficiently. Bioresource Technology 310, 123445.

Omoni, V.T., Lag-Brotons, A.J., Semple, K.T., 2020. Impact of organic amendments on the development of 14C-phenanthrene catabolism in soil. International Biodeterioration & Biodegradation 151, 104991.

Salvachúa, D., Werner, A.Z., Pardo, I., Michalska, M., Black, B.A., Donohoe, B.S., Haugen, S.J., Katahira, R., Notonier, S., Ramirez, K.J., Amore, A., Purvine, S.O., Zink, E.M., Abraham, P.E., Giannone, R.J., Poudel, S., Laible, P.D., Hettich, R.L., Beckham, G.T., 2020. Outer membrane vesicles catabolize lignin-derived aromatic compounds in Pseudomonas putida KT2440. Proceedings of the National Academy of Sciences 117, 9302-9310.

BIODEGRADATION PATHWAYS/GENOMICS

Garrido-Sanz, D., Redondo-Nieto, M., Martín, M., Rivilla, R., 2020. Comparative genomics of the Rhodococcus genus shows wide distribution of biodegradation traits. Microorganisms 8, 774.

Maeda, A.H., Nishi, S., Hatada, Y., Ohta, Y., Misaka, K., Kunihiro, M., Mori, J.F., Kanaly, R.A., 2020. Chemical and genomic analyses of polycyclic aromatic hydrocarbon biodegradation in Sphingobium barthaii KK22 reveals divergent pathways in soil sphingomonads. International Biodeterioration & Biodegradation 151, 104993.

Sangkharak, K., Choonut, A., Rakkan, T., Prasertsan, P., 2020. The degradation of phenanthrene, pyrene, and fluoranthene and its conversion into medium-chain-length polyhydroxyalkanoate by novel polycyclic aromatic hydrocarbon-degrading bacteria. Current Microbiology 77, 897-909.

Biofuels/Biomass/Bioengineering

Arapova, O.V., Chistyakov, A.V., Tsodikov, M.V., Moiseev, I.I., 2020. Lignin as a renewable resource of hydrocarbon products and energy carriers (a review). Petroleum Chemistry 60, 227-243.

Aravind, S., Kumar, P.S., Kumar, N.S., Siddarth, N., 2020. Conversion of green algal biomass into bioenergy by pyrolysis. A review. Environmental Chemistry Letters 18, 829-849.

Cui, Z., Cheng, F., Jarvis, J.M., Brewer, C.E., Jena, U., 2020. Roles of co-solvents in hydrothermal liquefaction of low-lipid, high-protein algae. Bioresource Technology 310, 123454.

Davis, K., Moon, T.S., 2020. Tailoring microbes to upgrade lignin. Current Opinion in Chemical Biology 59, 23-29.


Figueirêdo, M.B., Venderbosch, R.H., Heeres, H.J., Deuss, P.J., 2020. In-depth structural characterization of the lignin fraction of a pine-derived pyrolysis oil. Journal of Analytical and Applied Pyrolysis 149, 104837.

Hernandez, C.A., Osma, J.F., 2020. Microbial electrochemical systems: Deriving future trends from historical perspectives and characterization strategies. Frontiers in Environmental Science 8, 44. doi: 10.3389/fenvs.2020.00044.

Jun, J., Frith, M.G., Connatser, R.M., Keiser, J.R., Brady, M.P., Lewis, S., 2020. Corrosion susceptibility of Cr–Mo steels and ferritic stainless steels in biomass-derived pyrolysis oil constituents. Energy & Fuels 34, 6220-6228.

Li, Z.-H., Magrini-Bair, K., Wang, H., Maltsev, O.V., Geeza, T.J., Mora, C.I., Lee, J.E., 2020. Tracking renewable carbon in bio-oil/crude co-processing with VGO through 13C/12C ratio analysis. Fuel 275, 117770.


Priharto, N., Ronsse, F., Prins, W., Carleer, R., Heeres, H.J., 2020. Experimental studies on a two-step fast pyrolysis-catalytic hydrotreatment process for hydrocarbons from microalgae (Nannochloropsis gaditana and Scenedesmus almeriensis). Fuel Processing Technology 206, 106466.


Sun, L., Alper, H.S., 2020. Non-conventional hosts for the production of fuels and chemicals. Current Opinion in Chemical Biology 59, 15-22.

Zhao, C., Qiao, X., Shao, Q., Hassan, M., Ma, Z., 2020. Evolution of the lignin chemical structure during the bioethanol production process and its inhibition to enzymatic hydrolysis. Energy & Fuels 34, 5938-5947.

Zhu, J., Yang, H., Hu, H., Zhou, Y., Li, J., Jin, L., 2020. Novel insight into pyrolysis behaviors of lignin using in-situ pyrolysis-double ionization time-of-flight mass spectrometry combined with electron paramagnetic resonance spectroscopy. Bioresource Technology 312, 123555.

Biogeochemistry

Argentino, C., Johnson, J.E., Conti, S., Fioroni, C., Fontana, D., 2020. Preservation of 34S-enriched sulfides in fossil sulfate-methane transition zones: new evidence from Miocene outcrops of the northern Apennines (Italy). Geo-Marine Letters 40, 379-390.

Arosio, T., Ziehmer, M.M., Nicolussi, K., Schlüchter, C., Leuenberger, M., 2020. Alpine Holocene Tree-Ring Dataset: Age-related trends in the stable isotopes of cellulose show species-specific patterns. Biogeosciences Discussions 2020, 1-21.

Bertran, E., Waldeck, A., Wing, B.A., Halevy, I., Leavitt, W.D., Bradley, A.S., Johnston, D.T., 2020. Oxygen isotope effects during microbial sulfate reduction: applications to sediment cell abundances. The ISME Journal 14, 1508-1519.

Bishop, M.E., Dong, H., Glasser, P., Briggs, B.R., Pentrak, M., Stucki, J.W., 2020. Microbially mediated iron redox cycling of subsurface sediments from Hanford Site, Washington State, USA. Chemical Geology 546, 119643.

Dick, J.M., Yu, M., Tan, J., 2020. Uncovering chemical signatures of salinity gradients through compositional analysis of protein sequences. Biogeosciences Discussions 2020, 1-29.

Findlay, A.J., Pellerin, A., Laufer, K., Jørgensen, B.B., 2020. Quantification of sulphide oxidation rates in marine sediment. Geochimica et Cosmochimica Acta 280, 441-452.

Guo, W., Cecchetti, A.R., Wen, Y., Zhou, Q., Sedlak, D.L., 2020. Sulfur cycle in a wetland microcosm: Extended 34S-stable isotope analysis and mass balance. Environmental Science & Technology 54, 5498-5508.

Haalboom, S., Price, D.M., Mienis, F., van Bleijswijk, J.D.L., de Stigter, H.C., Witte, H.J., Reichart, G.-J., Duineveld, G.C.A., 2020. Patterns of (trace) metals and microorganisms in the Rainbow hydrothermal vent plume at the Mid-Atlantic Ridge. Biogeosciences 17, 2499-2519.

Haffert, L., Haeckel, M., de Stigter, H., Janssen, F., 2020. Assessing the temporal scale of deep-sea mining impacts on sediment biogeochemistry. Biogeosciences 17, 2767-2789.

Hong, W.-L., Latour, P., Sauer, S., Sen, A., Gilhooly, W.P., Lepland, A., Fouskas, F., 2020. Iron cycling in Arctic methane seeps. Geo-Marine Letters 40, 391-401.

Huang, W., Ertekin, E., Wang, T., Cruz, L., Dailey, M., DiRuggiero, J., Kisailus, D., 2020. Mechanism of water extraction from gypsum rock by desert colonizing microorganisms. Proceedings of the National Academy of Sciences 117, 10681-10687.

Jørgensen, B.B., Andrén, T., Marshall, I.P.G., 2020. Sub-seafloor biogeochemical processes and microbial life in the Baltic Sea. Environmental Microbiology 22, 1688-1706.

Kraemer, G., Camps-Valls, G., Reichstein, M., Mahecha, M.D., 2020. Summarizing the state of the terrestrial biosphere in few dimensions. Biogeosciences 17, 2397-2424.

Lahme, S., Callbeck, C.M., Eland, L.E., Wipat, A., Enning, D., Head, I.M., Hubert, C.R.J., 2020. Comparison of sulfide-oxidizing Sulfurimonas strains reveals a new mode of thiosulfate formation in subsurface environments. Environmental Microbiology 22, 1784-1800.

Li, Y., Tang, S., Zhang, S., Xi, Z., 2020. In situ analysis of methanogenic pathways and biogeochemical features of CBM co-produced water from the Shizhuangnan Block in the southern Qinshui Basin, China. Energy & Fuels 34, 5466-5475.

Rathour, R., Gupta, J., Mishra, A., Rajeev, A.C., Dupont, C.L., Thakur, I.S., 2020. A comparative metagenomic study reveals microbial diversity and their role in the biogeochemical cycling of Pangong lake. Science of The Total Environment 731, 139074.

Shi, L.-D., Lv, P.-L., Wang, M., Lai, C.-Y., Zhao, H.-P., 2020. A mixed consortium of methanotrophic archaea and bacteria boosts methane-dependent selenate reduction. Science of The Total Environment 732, 139310.


Sun, X., Kong, T., Häggblom, M.M., Kolton, M., Li, F., Dong, Y., Huang, Y., Li, B., Sun, W., 2020. Chemolithoautotropic diazotrophy dominates the nitrogen fixation process in mine tailings. Environmental Science & Technology 54, 6082-6093.

Vonnahme, T.R., Molari, M., Janssen, F., Wenzhöfer, F., Haeckel, M., Titschack, J., Boetius, A., 2020. Effects of a deep-sea mining experiment on seafloor microbial communities and functions after 26 years. Science Advances 6, eaaz5922.

Watanabe, K., Yoshida, G., Hori, M., Umezawa, Y., Moki, H., Kuwae, T., 2020. Macroalgal metabolism and lateral carbon flows can create significant carbon sinks. Biogeosciences 17, 2425-2440.

Zhao, X., Zhao, C., Stahr, K., Kuzyakov, Y., Wei, X., 2020. The effect of microorganisms on soil carbonate recrystallization and abiotic CO2 uptake of soil. CATENA 192, 104592.

Zhou, X., Kang, F., Qu, X., Fu, H., Alvarez, P.J.J., Tao, S., Zhu, D., 2020. Role of extracellular polymeric substances in microbial reduction of arsenate to arsenite by Escherichia coli and Bacillus subtilis. Environmental Science & Technology 54, 6185-6193.

Zhu, L., Shi, W., Van Dam, B., Kong, L., Yu, J., Qin, B., 2020. Algal accumulation decreases sediment nitrogen removal by uncoupling nitrification-denitrification in shallow eutrophic lakes. Environmental Science & Technology 54, 6194-6201.

BIOFILM S/MICROBIAL INDUCED CORROSION


Muhammad, M.H., Idris, A.L., Fan, X., Guo, Y., Yu, Y., Jin, X., Qiu, J., Guan, X., Huang, T., 2020. Beyond risk: Bacterial biofilms and their regulating approaches. Frontiers in Microbiology 11, 928. doi: 910.3389/fmicb.2020.00928.

MICROBIAL MEDIATION OF MINERAL FORMATION/DEGRADATION

Avdonin, V.V., Zhegallo, E.A., Sergeeva, N.E., 2020. The microstructure of oxide ferromanganese ores in the world ocean as proof of their bacterial origin. Moscow University Geology Bulletin 75, 1-6.


Enyedi, N.T., Makk, J., Kótai, L., Berényi, B., Klébert, S., Sebestyén, Z., Molnár, Z., Borsodi, A.K., Leél-Őssy, S., Demény, A., Németh, P., 2020. Cave bacteria-induced amorphous calcium carbonate formation. Scientific Reports 10, 8696.


Nitschke, M.R., Fidalgo, C., Simões, J., Brandão, C., Alves, A., Serôdio, J., Frommlet, J.C., 2020. Symbiolite formation: a powerful in vitro model to untangle the role of bacterial communities in the photosynthesis-induced formation of microbialites. The ISME Journal 14, 1533-1546.

Ponomarchuk, V.A., Dobretsov, N.L., Lazareva, E.V., Zhmodik, S.M., Karmanov, N.S., Tolstov, A.V., Pyryaev, A.N., 2020. Evidence of microbial-induced mineralization in rocks of the Tomtor Carbonatite Complex (Arctic Siberia). Doklady Earth Sciences 490, 76-80.

Popall, R.M., Bolhuis, H., Muyzer, G., Sánchez-Román, M., 2020. Stromatolites as biosignatures of atmospheric oxygenation: Carbonate biomineralization and UV-C resilience in a Geitlerinema sp. - dominated culture. Frontiers in Microbiology 11, 948. doi: 910.3389/fmicb.2020.00948.

Xia, J., Liu, H., Nie, Z., Fan, X., Zhang, D., Zheng, X., Liu, L., Pan, X., Zhou, Y., 2020. Taking insights into phenomics of microbe-mineral interaction in bioleaching and acid mine drainage: Concepts and methodology. Science of The Total Environment 729, 139005.

Carbon Cycle

Buesseler, K.O., Boyd, P.W., Black, E.E., Siegel, D.A., 2020. Metrics that matter for assessing the ocean biological carbon pump. Proceedings of the National Academy of Sciences 117, 9679-9687.

Gray, A., Krolikowski, M., Fretwell, P., Convey, P., Peck, L.S., Mendelova, M., Smith, A.G., Davey, M.P., 2020. Remote sensing reveals Antarctic green snow algae as important terrestrial carbon sink. Nature Communications 11, 2527.

Li, D., Zhao, J., Yao, P., Liu, C., Sun, C., Chen, J., Pan, J., Han, Z., Hu, J., 2020. Spatial heterogeneity of organic carbon cycling in sediments of the northern Yap Trench: Implications for organic carbon burial. Marine Chemistry 223, 103813.

Li, K., Li, L., Aubaud, C., Muehlenbachs, K., 2020. Efficient carbon recycling at the central-northern Lesser Antilles arc: Implications to deep carbon recycling in global subduction zones. Geophysical Research Letters 47, e2020GL086950.

Tao, R., Zhang, L., Zhang, L., 2020. Redox evolution of western Tianshan subduction zone and its effect on deep carbon cycle. Geoscience Frontiers 11, 915-924.

Toming, K., Kotta, J., Uuemaa, E., Sobek, S., Kutser, T., Tranvik, L.J., 2020. Predicting lake dissolved organic carbon at a global scale. Scientific Reports 10, 8471.


Zolkos, S., Tank, S.E., 2020. Experimental evidence that permafrost thaw history and mineral composition shape abiotic carbon cycling in thermokarst-affected stream networks. Frontiers in Earth Science 8, 152. doi: 110.3389/feart.2020.00152.

Climate Change

Thirumalai, K., Clemens, S.C., Partin, J.W., 2020. Methane, monsoons, and modulation of millennial-scale climate. Geophysical Research Letters 47, e2020GL087613.

Wang, T., Yang, D., Yang, Y., Piao, S., Li, X., Cheng, G., Fu, B., 2020. Permafrost thawing puts the frozen carbon at risk over the Tibetan Plateau. Science Advances 6, eaaz3513.

Zhang, S., Zhang, F., Shi, Z., Qin, A., Wang, H., Sun, Z., Yang, Z., Zhu, Y., Pang, S., Wang, P., 2020. Sources of seasonal wetland methane emissions in permafrost regions of the Qinghai-Tibet Plateau. Scientific Reports 10, 7520.


Carbon Sequestration

Alhosani, A., Scanziani, A., Lin, Q., Raeini, A.Q., Bijeljic, B., Blunt, M.J., 2020. Pore-scale mechanisms of CO2 storage in oilfields. Scientific Reports 10, 8534.


Fauziah, C.A., Al-Yaseri, A.Z., Jha, N.K., Lagat, C., Roshan, H., Barifcani, A., Iglauer, S., 2020. Carbon dioxide wettability of South West Hub sandstone, Western Australia: Implications for carbon geo-storage. International Journal of Greenhouse Gas Control 98, 103064.

Ju, Y., Lee, S.-S., Kaown, D., Lee, K.-K., Gilfillan, S.M.V., Hahm, D., Park, K., 2020. Noble gas as a proxy to understand the evolutionary path of migrated CO2 in a shallow aquifer system. Applied Geochemistry 118, 104609.


Menefee, A.H., Ellis, B.R., 2020. Regional-scale greenhouse gas utilization strategies for enhanced shale oil recovery and carbon management. Energy & Fuels 34, 6136-6147.

Myers, M., White, C., Pejcic, B., Feitz, A., Roberts, J., Oh, Y.-Y., Xu, L., Ricard, L., Michael, K., Avijegon, A., Rachakonda, P.K., Woltering, M., Larcher, A., Stalker, L., Hortle, A., 2020. CSIRO In-Situ Lab: A multi-pronged approach to surface gas and groundwater monitoring at geological CO2 storage sites. Chemical Geology 545, 119642.

Paluszny, A., Graham, C.C., Daniels, K.A., Tsaparli, V., Xenias, D., Salimzadeh, S., Whitmarsh, L., Harrington, J.F., Zimmerman, R.W., 2020. Caprock integrity and public perception studies of carbon storage in depleted hydrocarbon reservoirs. International Journal of Greenhouse Gas Control 98, 103057.

Psarras, P., He, J., Pilorgé, H., McQueen, N., Jensen-Fellows, A., Kian, K., Wilcox, J., 2020. Cost analysis of carbon capture and sequestration from U.S. natural gas-fired power plants. Environmental Science & Technology 54, 6272-6280.

Song, Y., Sung, W., Jang, Y., Jung, W., 2020. Application of an artificial neural network in predicting the effectiveness of trapping mechanisms on CO2 sequestration in saline aquifers. International Journal of Greenhouse Gas Control 98, 103042.

Wheatley, D., Hollingworth, S., Steele, P., Chan, M., 2020. Sedimentology, diagenesis, and reservoir characterization of the Permian White Rim Sandstone, southern Utah: Implications for carbon capture and sequestration potential. American Association of Petroleum Geologists Bulletin 104, 1357-1373.

Coal/Lignite/Peat Geochemistry

Cheng, Q., Zhang, M., Huang, G., 2020. Even-carbon predominance of monomethyl branched alkanes in Humic coal from Junggar Basin, NW China. Acta Geochimica 39, 434-444.



Gordadze, G.N., Giruts, M.V., Poshibaeva, A.R., Alferova, A.A., Yusupova, A.A., 2020. Change in maturity of coals of the same genotype occurring at different depths, as determined by saturated hydrocarbon biomarkers. Petroleum Chemistry 60, 264-269.

Hopple, A.M., Wilson, R.M., Kolton, M., Zalman, C.A., Chanton, J.P., Kostka, J., Hanson, P.J., Keller, J.K., Bridgham, S.D., 2020. Massive peatland carbon banks vulnerable to rising temperatures. Nature Communications 11, 2373.

Liu, B., Zhao, C., Fiebig, J., Bechtel, A., Sun, Y., Püttmann, W., 2020. Stable isotopic and elemental characteristics of pale and dark layers in a late Pliocene lignite deposit basin in Yunnan Province, southwestern China: Implications for paleoenvironmental changes. International Journal of Coal Geology 226, 103498.

Liu, G.-H., Zong, Z.-M., Liu, F.-J., Ma, Z.-H., Wei, X.-Y., Kang, Y.-H., Fan, X., Ma, F.-Y., Liu, J.-M., Mo, W.-L., 2020. Two-step catalytic degradations of Dahuangshan lignite and directional upgrading of the resulting petroleum ether-extractable portions. Energy & Fuels 34, 5457-5465.

Mathews, R.P., Singh, B.D., Singh, V.P., Singh, A., Singh, H., Shivanna, M., Dutta, S., Mendhe, V.A., Chetia, R., 2020. Organo-petrographic and geochemical characteristics of Gurha lignite deposits, Rajasthan, India: Insights into the palaeovegetation, palaeoenvironment and hydrocarbon source rock potential. Geoscience Frontiers 11, 965-988.


Ütnü, Y.E., Okutan, H., Aydın, A.A., 2020. Polycyclic aromatic hydrocarbon (PAH) content of Malkara lignite and its ex-situ underground coal gasification (UCG) char residues. Fuel 275, 117949.

Wang, Q., Zhao, Y., Zhang, Y., Zhang, T., He, S., Wei, Y., 2020. Isotope labeling to study the hydrogen transfer route during lignite modification in a subcritical D2O–CO System. Energy & Fuels 34, 5485-5496.

Wang, Y., Qin, Y., Yang, L., Liu, S., Elsworth, D., Zhang, R., 2020. Organic geochemical and petrographic characteristics of the coal measure source rocks of Pinghu Formation in the Xihu sag of the East China Sea Shelf Basin: Implications for coal measure gas potential. Acta Geologica Sinica - English Edition 94, 364-375.


Zhang, Z., Zhao, L., Yang, J., Zhou, M., 2020. Seepage channel model and gas–water differentiation of near-vertical coal reservoirs in the Kuba coalfield, China: implication for coalbed methane development. Arabian Journal of Geosciences 13, 361.

Cosmochemistry/Planetary Geochemistry

Elardo, S.M., Laneuville, M., McCubbin, F.M., Shearer, C.K., 2020. Early crust building enhanced on the Moon’s nearside by mantle melting-point depression. Nature Geoscience 13, 339-343.

Faulk, S.P., Lora, J.M., Mitchell, J.L., Milly, P.C.D., 2020. Titan’s climate patterns and surface methane distribution due to the coupling of land hydrology and atmosphere. Nature Astronomy 4, 390-398.

Gáspár, A., Rieke, G.H., 2020. New HST data and modeling reveal a massive planetesimal collision around Fomalhaut. Proceedings of the National Academy of Sciences 117, 9712-9722.

Grewal, D.S., Dasgupta, R., Farnell, A., 2020. The speciation of carbon, nitrogen, and water in magma oceans and its effect on volatile partitioning between major reservoirs of the Solar System rocky bodies. Geochimica et Cosmochimica Acta 280, 281-301.

Hanna, R.D., Hamilton, V.E., Haberle, C.W., King, A.J., Abreu, N.M., Friedrich, J.M., 2020. Distinguishing relative aqueous alteration and heating among CM chondrites with IR spectroscopy. Icarus 346, 113760.

Kebukawa, Y., Nakashima, S., Mita, H., Muramatsu, Y., Kobayashi, K., 2020. Molecular evolution during hydrothermal reactions from formaldehyde and ammonia simulating aqueous alteration in meteorite parent bodies. Icarus 347, 113827.

Materese, C.K., Nuevo, M., Sandford, S.A., Bera, P.P., Lee, T.J., 2020. The production and potential detection of hexamethylenetetramine-methanol in space. Astrobiology 20, 601-616.

Morota, T., Sugita, S., Cho, Y., Kanamaru, M., Tatsumi, E., Sakatani, N., Honda, R., Hirata, N., Kikuchi, H., Yamada, M., Yokota, Y., Kameda, S., Matsuoka, M., Sawada, H., Honda, C., Kouyama, T., Ogawa, K., Suzuki, H., Yoshioka, K., Hayakawa, M., Hirata, N., Hirabayashi, M., Miyamoto, H., Michikami, T., Hiroi, T., Hemmi, R., Barnouin, O.S., Ernst, C.M., Kitazato, K., Nakamura, T., Riu, L., Senshu, H., Kobayashi, H., Sasaki, S., Komatsu, G., Tanabe, N., Fujii, Y., Irie, T., Suemitsu, M., Takaki, N., Sugimoto, C., Yumoto, K., Ishida, M., Kato, H., Moroi, K., Domingue, D., Michel, P., Pilorget, C., Iwata, T., Abe, M., Ohtake, M., Nakauchi, Y., Tsumura, K., Yabuta, H., Ishihara, Y., Noguchi, R., Matsumoto, K., Miura, A., Namiki, N., Tachibana, S., Arakawa, M., Ikeda, H., Wada, K., Mizuno, T., Hirose, C., Hosoda, S., Mori, O., Shimada, T., Soldini, S., Tsukizaki, R., Yano, H., Ozaki, M., Takeuchi, H., Yamamoto, Y., Okada, T., Shimaki, Y., Shirai, K., Iijima, Y., Noda, H., Kikuchi, S., Yamaguchi, T., Ogawa, N., Ono, G., Mimasu, Y., Yoshikawa, K., Takahashi, T., Takei, Y., Fujii, A., Nakazawa, S., Terui, F., Tanaka, S., Yoshikawa, M., Saiki, T., Watanabe, S., Tsuda, Y., 2020. Sample collection from asteroid (162173) Ryugu by Hayabusa2: Implications for surface evolution. Science 368, 654-659.

Nakano, H., Hirakawa, N., Matsubara, Y., Yamashita, S., Okuchi, T., Asahina, K., Tanaka, R., Suzuki, N., Naraoka, H., Takano, Y., Tachibana, S., Hama, T., Oba, Y., Kimura, Y., Watanabe, N., Kouchi, A., 2020. Precometary organic matter: A hidden reservoir of water inside the snow line. Scientific Reports 10, 7755.

Rampe, E.B., Blake, D.F., Bristow, T.F., Ming, D.W., Vaniman, D.T., Morris, R.V., Achilles, C.N., Chipera, S.J., Morrison, S.M., Tu, V.M., Yen, A.S., Castle, N., Downs, G.W., Downs, R.T., Grotzinger, J.P., Hazen, R.M., Treiman, A.H., Peretyazhko, T.S., Des Marais, D.J., Walroth, R.C., Craig, P.I., Crisp, J.A., Lafuente, B., Morookian, J.M., Sarrazin, P.C., Thorpe, M.T., Bridges, J.C., Edgar, L.A., Fedo, C.M., Freissinet, C., Gellert, R., Mahaffy, P.R., Newsom, H.E., Johnson, J.R., Kah, L.C., Siebach, K.L., Schieber, J., Sun, V.Z., Vasavada, A.R., Wellington, D., Wiens, R.C., 2020. Mineralogy and geochemistry of sedimentary rocks

and eolian sediments in Gale crater, Mars: A review after six Earth years of exploration with Curiosity. Geochemistry 80, 125605.

Redd, N.T., 2020. News feature: Diamonds in the rubble. Proceedings of the National Academy of Sciences 117, 11187-11190.

Ritson, D.J., Mojzsis, S.J., Sutherland, J.D., 2020. Supply of phosphate to early Earth by photogeochemistry after meteoritic weathering. Nature Geoscience 13, 344-348.

Rizzo, V., 2020. Why should geological criteria used on Earth not be valid also for Mars? Evidence of possible microbialites and algae in extinct Martian lakes. International Journal of Astrobiology 19, 283-294.

Reinhold, T., Shapiro, A.I., Solanki, S.K., Montet, B.T., Krivova, N.A., Cameron, R.H., Amazo-Gómez, E.M., 2020. The Sun is less active than other solar-like stars. Science 368, 518-521.

Salese, F., McMahon, W.J., Balme, M.R., Ansan, V., Davis, J.M., Kleinhans, M.G., 2020. Sustained fluvial deposition recorded in Mars’ Noachian stratigraphic record. Nature Communications 11, 2067.

Salta, Z., Tasinato, N., Lupi, J., Boussessi, R., Balbi, A., Puzzarini, C., Barone, V., 2020. Exploring the maze of C2N2H5 radicals and their fragments in the interstellar medium with the help of quantum-chemical computations. ACS Earth and Space Chemistry 4, 774-782.

Schmidt, J.S., Hinrichs, R., 2020. Evaluation of terrestrial carbonaceous matter aromatization by Raman spectroscopy and its application to C chondrites. Meteoritics & Planetary Science 55, 800-817.


White, L.F., Tait, K.T., Langelier, B., Lymer, E.A., Černok, A., Kizovski, T.V., Ma, C., Tschauner, O., Nicklin, R.I., 2020. Evidence for sodium-rich alkaline water in the Tagish Lake parent body and implications for amino acid synthesis and racemization. Proceedings of the National Academy of Sciences 117, 11217-11219.

Woods, P., 2020. The discovery of cosmic fullerenes. Nature Astronomy 4, 299-305.

Yokota, S., Terada, K., Saito, Y., Kato, D., Asamura, K., Nishino, M.N., Shimizu, H., Takahashi, F., Shibuya, H., Matsushima, M., Tsunakawa, H., 2020. KAGUYA observation of global emissions of indigenous carbon ions from the Moon. Science Advances 6, eaba1050.

ASTROBIOLOGY

Araujo, G.G.d., Rodrigues, F., Galante, D., 2020. Probing the response of Deinococcus radiodurans exposed to simulated space conditions. International Journal of Astrobiology 19, 203-209.

Capper, D., 2020. The search for microbial Martian life and American Buddhist ethics. International Journal of Astrobiology 19, 244-252.

Cockell, C.S., 2020. Persistence of habitable, but uninhabited, aqueous solutions and the application to extraterrestrial environments. Astrobiology 20, 617-627.

Costello, L.J., Filiberto, J., Crandall, J.R., Potter-McIntyre, S.L., Schwenzer, S.P., Miller, M.A., Hummer, D.R., Olsson-Francis, K., Perl, S., 2020. Habitability of hydrothermal systems at Jezero and Gusev Craters as constrained by hydrothermal alteration of a terrestrial mafic dike. Geochemistry 80, 125613.


Gale, J., Wandel, A., Hill, H., 2020. Will recent advances in AI result in a paradigm shift in Astrobiology and SETI? International Journal of Astrobiology 19, 295-298.

Haqq-Misra, J., Kopparapu, R.K., Schwieterman, E., 2020. Observational constraints on the Great Filter. Astrobiology 20, 572-579.

Lineweaver, C.H., Sleep, N., 2020. Are we alone? An interview with Dr. Norman Sleep. Astrobiology 20, 563-571.

Lingam, M., Loeb, A., 2020. Photosynthesis on exoplanets and exomoons from reflected light. International Journal of Astrobiology 19, 210-219.


Onofri, S., Balucani, N., Barone, V., Benedetti, P., Billi, D., Balbi, A., Brucato, J.R., Cobucci-Ponzano, B., Costanzo, G., Rocca, N.L., Moracci, M., Saladino, R., Vladilo, G., Albertini, N., Battistuzzi, M., Bloino, J., Botta, L., Casavecchia, P., Cassaro, A., Claudi, R., Cocola, L., Coduti, A., Di Donato, P., Di Mauro, E., Dore, L., Falcinelli, S., Fulle, M., Lombardi, A., Mancini, G., Maris, M., Maurelli, L., Murante, G., Negri, R., Pacelli, C., Pagano, I., Piccinino, D., Poletto, L., Prantera, G., Puzzarini, C., Rampino, S., Ripa, C., Rosi, M., Sanna, M., Selbmann, L., Silva, L., Skouteris, D., Strazzulli, A., Tasinato, N., Timperio, A.M., Tozzi, A., Tozzi, G.P., Trainotti, L., Ugliengo, P., Vaccaro, L., Zucconi, L., 2020. The Italian National Project of Astrobiology—Life in Space—Origin, presence, persistence of life in space, from molecules to extremophiles. Astrobiology 20, 580-582.

Osmanov, Z., 2020. On the interstellar Von Neumann micro self-reproducing probes. International Journal of Astrobiology 19, 220-223.

Puzzarini, C., 2020. Grand challenges in astrochemistry. Frontiers in Astronomy and Space Sciences 7, 19. doi: 10.3389/fspas.2020.00019.

Ramirez, R.M., 2020. A complex life habitable zone based on lipid solubility theory. Scientific Reports 10, 7432.

Sheikh, S.Z., 2020. Nine axes of merit for technosignature searches. International Journal of Astrobiology 19, 237-243.

Siraj, A., Loeb, A., 2020. Exporting terrestrial life out of the Solar System with gravitational slingshots of Earthgrazing bodies. International Journal of Astrobiology 19, 260-263.

Tasker, E.J., Ishimaru, K., Guttenberg, N., Foriel, J., 2020. Earth-Like: an education & outreach tool for exploring the diversity of planets like our own. International Journal of Astrobiology 19, 264-275.

Teece, B.L., George, S.C., Agbaje, O.B.A., Jacquet, S.M., Brock, G.A., 2020. Mars rover techniques and Lower/Middle Cambrian microbialites from South Australia: Construction, biofacies, and biogeochemistry. Astrobiology 20, 637-657.

Way, M.J., Del Genio, A.D., 2020. Venusian habitable climate scenarios: Modeling venus through time and applications to slowly rotating Venus-like exoplanets. Journal of Geophysical Research: Planets 125, e2019JE006276.

Environmental Geochemistry

Álvarez-Muñoz, D., Farré, M., 2020. Environmental Metabolomics. Applications in Field and Laboratory Studies to Understand from Exposome to Metabolome. Elsevier, p. 368.

Borji, H., Ayoub, G.M., Al-Hindi, M., Malaeb, L., Hamdan, H.Z., 2020. Nanotechnology to remove polychlorinated biphenyls and polycyclic aromatic hydrocarbons from water: a review. Environmental Chemistry Letters 18, 729-746.

Chen, J., Liao, J., Wei, C., 2020. Coking wastewater treatment plant as a sources of polycyclic aromatic hydrocarbons (PAHs) in sediments and ecological risk assessment. Scientific Reports 10, 7833.

Hirst, B., Randell, D., Jones, M., Chu, J., Kannath, A., Macleod, N., Dean, M., Weidmann, D., 2020. Methane emissions: Remote mapping and source quantification using an open-path laser dispersion spectrometer. Geophysical Research Letters 47, e2019GL086725.

Ingraffea, A.R., Wawrzynek, P.A., Santoro, R., Wells, M., 2020. Reported methane emissions from active oil and gas wells in Pennsylvania, 2014–2018. Environmental Science & Technology 54, 5783-5789.

Jia, H., Liu, J., Zhu, K., Gao, P., Lichtfouse, E., 2020. High contribution of hydrocarbon transformation during the removal of polycyclic aromatic hydrocarbons from soils, humin and clay by thermal treatment at 100–200 °C. Environmental Chemistry Letters 18, 923-930.

Nascimento, M.K.S., Loureiro, S., Souza, M.R.d.R., Alexandre, M.d.R., Nilin, J., 2020. Toxicity of a mixture of monoaromatic hydrocarbons (BTX) to a tropical marine microcrustacean. Marine Pollution Bulletin 156, 111272.

Pang, S.Y., Tay, J.H., Suratman, S., Simoneit, B.R.T., Mohd Tahir, N., 2020. Input of organic matter in Brunei Bay, East Malaysia, as indicated by sedimentary steroids and multivariate statistics. Marine Pollution Bulletin 156, 111269.


Su, P., Zhang, W., Hao, Y., Tomy, G.T., Yin, F., Chen, L., Ding, Y., Li, Y., Feng, D., 2020. Polycyclic aromatic hydrocarbon contaminations along shipping lanes and implications of seafarer exposure: Based on PAHs in ship surface films and a film-air-water fugacity model. Science of The Total Environment 731, 138943.

Van De Ven, C.J.C., Mumford, K.G., 2020. Intermediate-scale laboratory investigation of stray gas migration impacts: Methane source architecture and dissolution. Environmental Science & Technology 54, 6299-6307.

Ward, C.P., Cory, R.M., 2020. Assessing the prevalence, products, and pathways of dissolved organic matter partial photo-oxidation in arctic surface waters. Environmental Science: Processes & Impacts 22, 1214-1223.

Williams, T., Walsh, C., Murray, K., Subir, M., 2020. Interactions of emerging contaminants with model colloidal microplastics, C60 fullerene, and natural organic matter – effect of surface functional group and adsorbate properties. Environmental Science: Processes & Impacts 22, 1190-1200.

Yin, Y., Mastalerz, M., Lennon, J.T., Drobniak, A., Schimmelmann, A., 2020. Characterization and microbial mitigation of fugitive methane emissions from oil and gas wells: Example from Indiana, USA. Applied Geochemistry 118, 104619.

BIOREMEDIATION

Ekperusi, A.O., Nwachukwu, E.O., Sikoki, F.D., 2020. Assessing and modelling the efficacy of Lemna paucicostata for the phytoremediation of petroleum hydrocarbons in crude oil-contaminated wetlands. Scientific Reports 10, 8489.

Jaiswal, S., Shukla, P., 2020. Alternative strategies for microbial remediation of pollutants via synthetic biology. Frontiers in Microbiology 11, 808. doi: 810.3389/fmicb.2020.00808.

Li, F., Guo, S., Wang, S., Zhao, M., 2020. Changes of microbial community and activity under different electric fields during electro-bioremediation of PAH-contaminated soil. Chemosphere 254, 126880.

Sachaniya, B.K., Gosai, H.B., Panseriya, H.Z., Dave, B.P., 2020. Bioengineering for multiple PAHs degradation for contaminated sediments: Response surface methodology (RSM) and artificial neural network (ANN). Chemometrics and Intelligent Laboratory Systems 202, 104033.

DEEPWATER HORIZON/MACONDO/OTHER OIL SPILLS

Afshar-Mohajer, N., Lam, A., Dora, L., Katz, J., Rule, A.M., Koehler, K., 2020. Impact of dispersant on crude oil content of airborne fine particulate matter emitted from seawater after an oil spill. Chemosphere 256, 127063.

Bryant, W.L., Camilli, R., Fisher, G.B., Overton, E.B., Reddy, C.M., Reible, D., Swarthout, R.F., Valentine, D.L., 2020. Harnessing a decade of data to inform future decisions:

Insights into the ongoing hydrocarbon release at Taylor Energy's Mississippi Canyon Block 20 (MC20) site. Marine Pollution Bulletin 155, 111056.

Bytingsvik, J., Parkerton, T.F., Guyomarch, J., Tassara, L., LeFloch, S., Arnold, W.R., Brander, S.M., Volety, A., Camus, L., 2020. The sensitivity of the deepsea species northern shrimp (Pandalus borealis) and the cold-water coral (Lophelia pertusa) to oil-associated aromatic compounds, dispersant, and Alaskan North Slope crude oil. Marine Pollution Bulletin 156, 111202.

Eronat, A.H., 2020. Time series evaluation of oil spill in marine environment: a case study in marine area of Cyprus. Arabian Journal of Geosciences 13, 365.

Gilchrist, R.M., Hall, R.A., Bacon, J.C., Rees, J.M., Graham, J.A., 2020. Increased dispersion of oil from a deep water seabed release by energetic mesoscale eddies. Marine Pollution Bulletin 156, 111258.

Gregson, B.H., Metodieva, G., Metodiev, M.V., Golyshin, P.N., McKew, B.A., 2020. Protein expression in the obligate hydrocarbon-degrading psychrophile Oleispira antarctica RB-8 during alkane degradation and cold tolerance. Environmental Microbiology 22, 1870-1883.


Lourenço, R.A., Combi, T., Alexandre, M.d.R., Sasaki, S.T., Zanardi-Lamardo, E., Yogui, G.T., 2020. Mysterious oil spill along Brazil's northeast and southeast seaboard (2019–2020): Trying to find answers and filling data gaps. Marine Pollution Bulletin 156, 111219.

Schutte, C.A., Marton, J.M., Bernhard, A.E., Giblin, A.E., Roberts, B.J., 2020. No evidence for long-term impacts of oil spill contamination on salt marsh soil nitrogen cycling processes. Estuaries and Coasts 43, 865-879.

Shen, S., Wu, W., Grimes, D.J., Saillant, E.A., Griffitt, R.J., 2020. Community composition and antibiotic resistance of bacteria in bottlenose dolphins Tursiops truncatus – Potential impact of 2010 BP Oil Spill. Science of The Total Environment 732, 139125.

Thompson, J., Pietsch, L., Phillips, M., Lennard, C., Fuller, S., Spikmans, V., 2020. Assessment of evaporative and photochemical effects on asphaltene profiling of a heavy fuel oil. Environmental Forensics 21, 212-222.

Wang, D., Guo, W., Kong, S., Xu, T., 2020. Estimating offshore exposure to oil spill impacts based on a statistical forecast model. Marine Pollution Bulletin 156, 111213.

Ward, C.P., Overton, E.B., 2020. How the 2010 Deepwater Horizon spill reshaped our understanding of crude oil photochemical weathering at sea: a past, present, and future perspective. Environmental Science: Processes & Impacts 22, 1125-1138.

White, A.R., Jalali, M., Sheng, J., 2020. Hydrodynamics of a rising oil droplet with bacterial extracellular polymeric substance (EPS) streamers using a microfluidic microcosm. Frontiers in Marine Science 7, 294. doi: 210.3389/fmars.2020.00294.

MICROPLASTICS


Padervand, M., Lichtfouse, E., Robert, D., Wang, C., 2020. Removal of microplastics from the environment. A review. Environmental Chemistry Letters 18, 807-828.


OIL SAND PROCESS WATERS/TAILING PONDS


Fang, Z., Huang, R., How, Z.T., Jiang, B., Chelme-Ayala, P., Shi, Q., Xu, C., El-Din, M.G., 2020. Molecular transformation of dissolved organic matter in process water from oil and gas operation during UV/H2O2, UV/chlorine, and UV/persulfate processes. Science of The Total Environment 730, 139072.

Saidi-Mehrabad, A., Kits, D.K., Kim, J.-J., Tamas, I., Schumann, P., Khadka, R., Strilets, T., Smirnova, A.V., Rijpstra, W.I.C., Sinninghe Damsté, J.S., Dunfield, P.F., 2020. Methylicorpusculum oleiharenae gen. nov., sp. nov., an aerobic methanotroph isolated from an oil sands tailings pond. International Journal of Systematic and Evolutionary Microbiology 70, 2499-2508.

UNCONVENTIONALSHALE GAS-CBM RESOURCES

Hu, S.-y., Xiao, C.-L., Liang, X.-J., Cao, Y.-q., 2020. Influence of water-rock interaction on the pH and heavy metals content of groundwater during in-situ oil shale exploitation. Oil Shale 37, 104-118.

Tasker, T.L., Warner, N.R., Burgos, W.D., 2020. Geochemical and isotope analysis of produced water from the Utica/Point Pleasant Shale, Appalachian Basin. Environmental Science: Processes & Impacts 22, 1224-1232.

Zhong, C., Nesbø, C.L., Goss, G.G., Lanoil, B.D., Alessi, D.S., 2020. Response of aquatic microbial communities and bioindicator modelling of hydraulic fracturing flowback and produced water. FEMS Microbiology Ecology 96, fiaa068.

Evolution/Paleontology/Palynology

Bailleul, A.M., Zheng, W., Horner, J.R., Hall, B.K., Holliday, C.M., Schweitzer, M.H., 2020. Evidence of proteins, chromosomes and chemical markers of DNA in exceptionally preserved dinosaur cartilage. National Science Review 7, 815-822.

Becker-Kerber, B., Paim, P.S.G., Chemale Junior, F., Girelli, T.J., da Rosa, A.L.Z., Albani, A.E., Osés, G.L., Prado, G.M.E.M., Figueiredo, M., Simões, L.S.A., Pacheco, M.L.A.F., 2020. The oldest record of Ediacaran macrofossils in Gondwana (~563 Ma, Itajaí Basin, Brazil). Gondwana Research 84, 211-228.

Frederickson, J.A., Engel, M.H., Cifelli, R.L., 2020. Ontogenetic dietary shifts in Deinonychus antirrhopus (Theropoda; Dromaeosauridae): Insights into the ecology and social behavior of raptorial dinosaurs through stable isotope analysis. Palaeogeography, Palaeoclimatology, Palaeoecology 552, 109780.

Ibrahim, N., Maganuco, S., Dal Sasso, C., Fabbri, M., Auditore, M., Bindellini, G., Martill, D.M., Zouhri, S., Mattarelli, D.A., Unwin, D.M., Wiemann, J., Bonadonna, D., Amane, A., Jakubczak, J., Joger, U., Lauder, G.V., Pierce, S.E., 2020. Tail-propelled aquatic locomotion in a theropod dinosaur. Nature 581, 67-70.


Khalturin, K., 2020. The origin of metazoan larvae. Nature Ecology & Evolution 4, 674-675.

Long, J., Zhang, S., Luo, K., 2020. Distribution of selenium and arsenic in differentiated multicellular eukaryotic fossils and their significance. Geoscience Frontiers 11, 821-833.

Naimark, E.B., Boeva, N.M., 2020. The role of iron in the formation of fossils of soft-bodied organisms: Results of long-term experiments. Doklady Earth Sciences 490, 72-75.

Nazarova, V.M., Gatovsky, Y.A., 2020. “Conodont pearls” from the Devonian deposits of European Russia. Moscow University Geology Bulletin 75, 31-39.

Ou, Q., Vannier, J., Yang, X., Chen, A., Mai, H., Shu, D., Han, J., Fu, D., Wang, R., Mayer, G., 2020. Evolutionary trade-off in reproduction of Cambrian arthropods. Science Advances 6, eaaz3376.

Pillai, A.S., Chandler, S.A., Liu, Y., Signore, A.V., Cortez-Romero, C.R., Benesch, J.L.P., Laganowsky, A., Storz, J.F., Hochberg, G.K.A., Thornton, J.W., 2020. Origin of complexity in haemoglobin evolution. Nature 581, 480-485.

Schoch, R.R., Werneburg, R., Voigt, S., 2020. A Triassic stem-salamander from Kyrgyzstan and the origin of salamanders. Proceedings of the National Academy of Sciences 117, 11584-11588.

Shukla, Y., Sharma, M., 2020. Ediacaran discs from the Bhima Group, Karnataka, South India. Journal of the Geological Society of India 95, 483-490.

Theodoridis, S., Fordham, D.A., Brown, S.C., Li, S., Rahbek, C., Nogues-Bravo, D., 2020. Evolutionary history and past climate change shape the distribution of genetic diversity in terrestrial mammals. Nature Communications 11, 2557.

Wang, J., Zhang, L., Lian, S., Qin, Z., Zhu, X., Dai, X., Huang, Z., Ke, C., Zhou, Z., Wei, J., Liu, P., Hu, N., Zeng, Q., Dong, B., Dong, Y., Kong, D., Zhang, Z., Liu, S., Xia, Y., Li, Y., Zhao, L., Xing, Q., Huang, X., Hu, X., Bao, Z., Wang, S., 2020. Evolutionary transcriptomics of metazoan biphasic life cycle supports a single intercalation origin of metazoan larvae. Nature Ecology & Evolution 4, 725-736.

Wang, Q., Zheng, J., Sun, B., Ma, F., Wang, Z., Wang, W., 2020. Carbon isotope and paleoclimatic implications of three plants from the Oligocene Ningming Formation, Guangxi Acta Sedimentologica Sinica 38, 358-366

Zhang, X.-Y., Zheng, Q.-F., Li, Y., Yang, H.-Q., Zhang, H., Wang, W.-Q., Shen, S.-Z., 2020. Polybessurus-like fossils as key contributors to Permian–Triassic boundary microbialites in South China. Palaeogeography, Palaeoclimatology, Palaeoecology 552, 109770.

ORIGINS OF LIFE/MICROBIAL GENOMICS

Baú, J.P.T., Villafañe-Barajas, S.A., Negrón-Mendoza, A., Colín-García, M., Zaia, D.A.M., 2020. Effect of γ-radiation on adenine dissolved in distilled water, saline solutions and artificial seawater resembling that of 4.0 billion years ago. International Journal of Astrobiology 19, 224-236.

Chen, S.-C., Sun, G.-X., Yan, Y., Konstantinidis, K.T., Zhang, S.-Y., Deng, Y., Li, X.-M., Cui, H.-L., Musat, F., Popp, D., Rosen, B.P., Zhu, Y.-G., 2020. The Great Oxidation Event expanded the genetic repertoire of arsenic metabolism and cycling. Proceedings of the National Academy of Sciences 117, 10414-10421.


Fox, S., Gspandl, A., Wenng, F.M., 2020. Acceleration of amino acid racemization by isovaline: possible implications for homochirality and biosignature search. International Journal of Astrobiology 19, 276-282.

Fu, X., Liao, Y., Glein, C.R., Jamison, M., Hayes, K., Zaporski, J., Yang, Z., 2020. Direct synthesis of amides from amines and carboxylic acids under hydrothermal conditions. ACS Earth and Space Chemistry 4, 722-729.

Globus, N., Blandford, R.D., 2020. The chiral puzzle of life. The Astrophysical Journal 895, L11.


Neubeck, A., Freund, F., 2020. Sulfur chemistry may have paved the way for evolution of antioxidants. Astrobiology 20, 670-675.

Ramírez-Vázquez, L., Negrón-Mendoza, A., 2020. Stability of α-ketoglutaric acid simulating an impact-generated hydrothermal system: implications for prebiotic chemistry studies. International Journal of Astrobiology 19, 253-259.



HOMINID EVOLUTION

Gibbons, A., 2020. Oldest Homo sapiens bones found in Europe. Science 368, 697.

Hublin, J.-J., Sirakov, N., Aldeias, V., Bailey, S., Bard, E., Delvigne, V., Endarova, E., Fagault, Y., Fewlass, H., Hajdinjak, M., Kromer, B., Krumov, I., Marreiros, J., Martisius, N.L., Paskulin, L., Sinet-Mathiot, V., Meyer, M., Pääbo, S., Popov, V., Rezek, Z., Sirakova, S., Skinner, M.M., Smith, G.M., Spasov, R., Talamo, S., Tuna, T., Wacker, L., Welker, F., Wilcke, A., Zahariev, N., McPherron, S.P., Tsanova, T., 2020. Initial Upper Palaeolithic Homo sapiens from Bacho Kiro Cave, Bulgaria. Nature 581, 299-302.

Fluid Inclusions

Bodnar, R.J., Frezzotti, M.L., 2020. Microscale chemistry: Raman analysis of fluid and melt inclusions. Elements 16, 93-98.

Fu, S., Liu, Z., Zhang, Y.-m., Jiang, S.-q., Wang, X., Wang, H.-l., Tian, N., Yang, H.-l., 2020. Erosion thickness estimate and hydrocarbon accumulation period of relic basins: A case study of the Wulan-Hua Sag in southern Erlian Basin, NE China. Geological Journal 55, 3430-3450.

Hu, A., Niu, C., Wang, D., Li, H., Ye, T., Xu, P., 2020. The characteristics and formation mechanism of condensate oil and gas in Bozhong19-6 structure, Bozhong sag, Bohai Bay Basin Acta Petrolei Sinica 41, 403-411

Nie, H., He, Z., Wang, R., Zhang, G., Chen, Q., Li, D., Lu, Z., Sun, C., 2020. Temperature and origin of fluid inclusions in shale veins of Wufeng–Longmaxi Formations, Sichuan Basin, south China: Implications for shale gas preservation and enrichment. Journal of Petroleum Science and Engineering 193, 107329.


Su, A., Chen, H., Zhao, J.-x., Feng, Y.-x., 2020. Integrated fluid inclusion analysis and petrography constraints on the petroleum system evolution of the central and southern Biyang Sag, Nanxiang Basin, Eastern China. Marine and Petroleum Geology 118, 104437.

Su, A., Chen, H., Zhao, J.-x., Zhang, T.-w., Feng, Y.-x., Wang, C., 2020. Natural gas washing induces condensate formation from coal measures in the Pinghu Slope Belt of the Xihu Depression, East China Sea Basin: Insights from fluid inclusion, geochemistry, and rock gold-tube pyrolysis. Marine and Petroleum Geology 118, 104450.

Teixeira, C.A.S., Bello, R.M.S., Almeida, N.S., Pestilho, A., Brochsztain, S., de Queiroz, T.B., Andrade, L.S., Júnior, D.F.G., Sawakuchi, A.O., 2020. Hydrocarbon generation in the Permian Irati organic-rich shales under the influence of the Early Cretaceous Paraná Large Igneous Province. Marine and Petroleum Geology 117, 104410.

Wang, Y., Chang, X., Sun, Y., Shi, B., Qin, S., 2020. Timeframe of hydrocarbon migration in the Paleogene Shahejie Formation in the Dongying depression, Bohai Bay Basin (northeastern China) based on fluid inclusions and oil geochemistry. Journal of Petroleum Science and Engineering 193, 107428.


General Interest

Halbwachs, M., Sabroux, J.-C., Kayser, G., 2020. Final step of the 32-year Lake Nyos degassing adventure: Natural CO2 recharge is to be balanced by discharge through the degassing pipes. Journal of African Earth Sciences 167, 103575.

Liu, Z., Huang, E., Orozco, I., Liao, W., Palomino, R.M., Rui, N., Duchoň, T., Nemšák, S., Grinter, D.C., Mahapatra, M., Liu, P., Rodriguez, J.A., Senanayake, S.D., 2020. Water-promoted interfacial pathways in methane oxidation to methanol on a CeO2-Cu2O catalyst. Science 368, 513-517.

Miller, T.E., Beneyton, T., Schwander, T., Diehl, C., Girault, M., McLean, R., Chotel, T., Claus, P., Cortina, N.S., Baret, J.-C., Erb, T.J., 2020. Light-powered CO2 fixation in a chloroplast mimic with natural and synthetic parts. Science 368, 649-654.

Service, R.F., 2020. Without fossil fuels, reactors churn out chemicals. Science 368, 566-567.

Takata, T., Jiang, J., Sakata, Y., Nakabayashi, M., Shibata, N., Nandal, V., Seki, K., Hisatomi, T., Domen, K., 2020. Photocatalytic water splitting with a quantum efficiency of almost unity. Nature 581, 411-414.

Geology

Bozhko, N.A., 2020. Tectonic inheritance and predetermination in supercontinental cyclicity. Moscow University Geology Bulletin 75, 7-12.

Cawood, P.A., 2020. Metamorphic rocks and plate tectonics. Science Bulletin 65, 968-969.

Kopylova, M.G., Tso, E., Ma, F., Liu, J., Pearson, D.G., 2019. The metasomatized mantle beneath the North Atlantic Craton: Insights from peridotite xenoliths of the Chidliak kimberlite province (NE Canada). Journal of Petrology 60, 1991-2024.



Liu, J., Hunfeld, L.B., Niemeijer, A.R., Spiers, C.J., 2020. Frictional properties of simulated shale-coal fault gouges: Implications for induced seismicity in source rocks below Europe's largest gas field. International Journal of Coal Geology 226, 103499.

Liu, Q., Sun, Y., Li, J., 2020. Experimental study on seepage characteristics of Jurassic weakly cemented sandstone under water-rock interaction. Geofluids 2020, 8543687.

Miao, Q., Xu, C., Hao, F., Yin, J., Wang, Q., Xie, M., Cao, Y., Zou, H., 2020. Roles of fault structures on the distribution of mantle-derived CO2 in the Bohai Bay basin, NE China. Journal of Asian Earth Sciences 197, 104398.

Planavsky, N., Hood, A., Tarhan, L., Shen, S., Johnson, K., 2020. Store and share ancient rocks. Nature 581, 137-139.

Sanei, H., Ardakani, O.H., Akai, T., Akihisa, K., Jiang, C., Wood, J.M., 2020. Core versus cuttings samples for geochemical and petrophysical analysis of unconventional reservoir rocks. Scientific Reports 10, 7920.

Wang, J., Liu, J., Zhang, H., Zhang, H., Li, Y., 2020. Metamorphism, geochemistry, and carbon source on sedimentary-metamorphic graphite deposits in eastern Shandong, China. Geological Journal 55, 3748-3769.

Wicking, C., Tessarolo, N., Savvoulidi, M., Crouch, J., Collins, I., Couves, J., Kot, E., Banks, N., Hodges, M., Zeng, H., 2020. Sequential extraction and characterization of the organic layer on sandstone reservoir rock surface. Fuel 276, 118062.


Zhang, X., Li, L.-F., Du, Z.-F., Hao, X.-L., Cao, L., Luan, Z.-D., Wang, B., Xi, S.-C., Lian, C., Yan, J., Sun, W.-D., 2020. Discovery of supercritical carbon dioxide in a hydrothermal system. Science Bulletin 65, 958-964.

BOLIDE IMPACTS/CRATER GEOCHEMISTRY

Collins, G.S., Patel, N., Davison, T.M., Rae, A.S.P., Morgan, J.V., Gulick, S.P.S., Christeson, G.L., Chenot, E., Claeys, P., Cockell, C.S., Coolen, M.J.L., Ferrière, L., Gebhardt, C., Goto, K., Jones, H., Kring, D.A., Lofi, J., Lowery, C.M., Ocampo-Torres, R., Perez-Cruz, L., Pickersgill, A.E., Poelchau, M.H., Rasmussen, C., Rebolledo-Vieyra, M., Riller, U., Sato, H., Smit, J., Tikoo, S.M., Tomioka, N., Urrutia-Fucugauchi, J.,

Whalen, M.T., Wittmann, A., Xiao, L., Yamaguchi, K.E., Artemieva, N., Bralower, T.J., Party, I.-I.E.S., Third-Party, S., 2020. A steeply-inclined trajectory for the Chicxulub impact. Nature Communications 11, 1480.

Gladysheva, O., 2020. The Tunguska event. Icarus 348, 113837.

Kenkmann, T., Wulf, G., Agarwal, A., 2020. Ramgarh, Rajasthan, India: A 10 km diameter complex impact structure. Meteoritics & Planetary Science 55, 936-961.

Khrennikov, D.E., Titov, A.K., Ershov, A.E., Pariev, V.I., Karpov, S.V., 2020. On the possibility of through passage of asteroid bodies across the Earth’s atmosphere. Monthly Notices of the Royal Astronomical Society 493, 1344-1351.

Navarro, K.F., Urrutia-Fucugauchi, J., Villagran-Muniz, M., Sánchez-Aké, C., Pi-Puig, T., Pérez-Cruz, L., Navarro-González, R., 2020. Emission spectra of a simulated Chicxulub impact-vapor plume at the Cretaceous–Paleogene boundary. Icarus 346, 113813.

Smith, V., Warny, S., Grice, K., Schaefer, B., Whalen, M.T., Vellekoop, J., Chenot, E., Gulick, S.P.S., Arenillas, I., Arz, J.A., Bauersachs, T., Bralower, T., Demory, F., Gattacceca, J., Jones, H., Lofi, J., Lowery, C.M., Morgan, J., Nuñez Otaño, N.B.N., O'Keefe, J.M.K., O'Malley, K., Rodríguez-Tovar, F.J., Schwark, L., the Expedition 364 Scientists, 2020. Life and death in the Chicxulub impact crater: A record of the Paleocene-Eocene Thermal Maximum. Climate of the Past Discussions 2020, 1-17.

GEOCHIMICA ET COSMOCHIMICA 278, THE CONTINENTS: ORIGIN, EVOLUTION AND INTERACTIONS WITH OTHER RESERVOIRS

Teng, F.-Z., Lee, C.-T., Aulbach, S., Liu, X.-M., 2020. The continents: Origin, evolution, and interactions with other reservoirs. Geochimica et Cosmochimica Acta 278, 1-5.

Tang, M., Lee, C.-T.A., Rudnick, R.L., Condie, K.C., 2020. Rapid mantle convection drove massive crustal thickening in the late Archean. Geochimica et Cosmochimica Acta 278, 6-15.

Chen, K., Rudnick, R.L., Wang, Z., Tang, M., Gaschnig, R.M., Zou, Z., He, T., Hu, Z., Liu, Y., 2020. How mafic was the Archean upper continental crust? Insights from Cu and Ag in ancient glacial diamictites. Geochimica et Cosmochimica Acta 278, 16-29.

Li, S., Junkin, W.D., Gaschnig, R.M., Ash, R.D., Piccoli, P.M., Candela, P.A., Rudnick, R.L., 2020. Molybdenum contents of sulfides in ancient glacial diamictites: Implications for molybdenum delivery to the oceans prior to the Great Oxidation Event. Geochimica et Cosmochimica Acta 278, 30-50.

Mei, Q.-F., Yang, J.-H., Wang, Y.-F., Wang, H., Peng, P., 2020. Tungsten isotopic constraints on homogenization of the Archean silicate Earth: Implications for the transition of tectonic regimes. Geochimica et Cosmochimica Acta 278, 51-64.

Roman, A., Arndt, N., 2020. Differentiated Archean oceanic crust: Its thermal structure, mechanical stability and a test of the sagduction hypothesis. Geochimica et Cosmochimica Acta 278, 65-77.

Aulbach, S., Symes, C., Chacko, T., 2020. Elemental and radiogenic isotope perspective on formation and transformation of cratonic lower crust: Central Slave craton (Canada). Geochimica et Cosmochimica Acta 278, 78-93.

Ma, Q., Xu, Y.-G., Huang, X.-L., Zheng, J.-P., Ping, X., Xia, X.-P., 2020. Eoarchean to Paleoproterozoic crustal evolution in the North China Craton: Evidence from U-Pb and Hf-O isotopes of zircons from deep-crustal xenoliths. Geochimica et Cosmochimica Acta 278, 94-109.

Huang, T.-Y., Teng, F.-Z., Rudnick, R.L., Chen, X.-Y., Hu, Y., Liu, Y.-S., Wu, F.-Y., 2020. Heterogeneous potassium isotopic composition of the upper continental crust. Geochimica et Cosmochimica Acta 278, 122-136.

Ji, W.-Q., Wu, F.-Y., Liu, X.-C., Liu, Z.-C., Zhang, C., Liu, T., Wang, J.-G., Paterson, S.R., 2020. Pervasive Miocene melting of thickened crust from the Lhasa terrane to Himalaya, southern Tibet and its constraint on generation of Himalayan leucogranite. Geochimica et Cosmochimica Acta 278, 137-156.

Wang, C., Lo Cascio, M., Liang, Y., Xu, W., 2020. An experimental study of peridotite dissolution in eclogite-derived melts: Implications for styles of melt-rock interaction in lithospheric mantle beneath the North China Craton. Geochimica et Cosmochimica Acta 278, 157-176.

Liu, J., Pearson, D.G., Shu, Q., Sigurdsson, H., Thomassot, E., Alard, O., 2020. Dating post-Archean lithospheric mantle: Insights from Re-Os and Lu-Hf isotopic systematics of the Cameroon Volcanic Line peridotites. Geochimica et Cosmochimica Acta 278, 177-198.

Chin, E.J., Soustelle, V., Liu, Y., 2020. An SPO-induced CPO in composite mantle xenoliths correlated with increasing melt-rock interaction. Geochimica et Cosmochimica Acta 278, 199-218.

Hu, Y., Teng, F.-Z., Ionov, D.A., 2020. Magnesium isotopic composition of metasomatized upper sub-arc mantle and its implications to Mg cycling in subduction zones. Geochimica et Cosmochimica Acta 278, 219-234.

Goto, K.T., Sekine, Y., Shimoda, G., Hein, J.R., Aoki, S., Ishikawa, A., Suzuki, K., Gordon, G.W., Anbar, A.D., 2020. A framework for understanding Mo isotope records of Archean and Paleoproterozoic Fe- and Mn-rich sedimentary rocks: Insights from modern marine hydrothermal Fe-Mn oxides. Geochimica et Cosmochimica Acta 280, 221-236.

Li, W.-Y., Yu, H.-M., Xu, J., Halama, R., Bell, K., Nan, X.-Y., Huang, F., 2020. Barium isotopic composition of the mantle: Constraints from carbonatites. Geochimica et Cosmochimica Acta 278, 235-243.

Cuozzo, N., Sletten, R.S., Hu, Y., Liu, L., Teng, F.-Z., Hagedorn, B., 2020. Silicate weathering in Antarctic ice-rich permafrost: Insights using magnesium isotopes. Geochimica et Cosmochimica Acta 278, 244-260.

Chen, C., Ciazela, J., Li, W., Dai, W., Wang, Z., Foley, S.F., Li, M., Hu, Z., Liu, Y., 2020. Calcium isotopic compositions of oceanic crust at various spreading rates. Geochimica et Cosmochimica Acta 278, 272-288.

Shen, J., Xia, J., Qin, L., Carlson, R.W., Huang, S., Helz, R.T., Mock, T.D., 2020. Stable chromium isotope fractionation during magmatic differentiation: Insights from Hawaiian basalts and implications for planetary redox conditions. Geochimica et Cosmochimica Acta 278, 289-304.

Wang, Z.-Z., Liu, S.-A., Liu, Z.-C., Zheng, Y.-C., Wu, F.-Y., 2020. Extreme Mg and Zn isotope fractionation recorded in the Himalayan leucogranites. Geochimica et Cosmochimica Acta 278, 305-321.

Hanna, H.D., Liu, X.-M., Park, Y.-R., Kay, S.M., Rudnick, R.L., 2020. Lithium isotopes may trace subducting slab signatures in Aleutian arc lavas and intrusions. Geochimica et Cosmochimica Acta 278, 322-339.

Zhang, Y., Yuan, C., Sun, M., Li, J., Long, X., Jiang, Y., Huang, Z., 2020. Molybdenum and boron isotopic evidence for carbon-recycling via carbonate dissolution in subduction zones. Geochimica et Cosmochimica Acta 278, 340-352.

Sun, Y., Teng, F.-Z., Hu, Y., Chen, X.-Y., Pang, K.-N., 2020. Tracing subducted oceanic slabs in the mantle by using potassium isotopes. Geochimica et Cosmochimica Acta 278, 353-360.

Tian, H.-C., Zhang, C., Teng, F.-Z., Long, Y.-J., Li, S.-G., He, Y., Ke, S., Chen, X.-Y., Yang, W., 2020. Diffusion-driven extreme Mg and Fe isotope fractionation in Panzhihua ilmenite: Implications for the origin of mafic intrusion. Geochimica et Cosmochimica Acta 278, 361-375.

Huang, J., Guo, S., Jin, Q.-Z., Huang, F., 2020. Iron and magnesium isotopic compositions of subduction-zone fluids and implications for arc volcanism. Geochimica et Cosmochimica Acta 278, 376-391.

Lu, W.-N., He, Y., Wang, Y., Ke, S., 2020. Behavior of calcium isotopes during continental subduction recorded in meta-basaltic rocks. Geochimica et Cosmochimica Acta 278, 392-404.

Hydrates

Guo, Z.Y., Wang, H.N., Jiang, M.J., 2020. Elastoplastic analytical investigation of wellbore stability for drilling in methane hydrate-bearing sediments. Journal of Natural Gas Science and Engineering 79, 103344.

Liu, X., Xing, L., Qin, Z., Liu, H., 2020. The sensitive properties of hydrate reservoirs based on seismic stereoscopic detection technology. Acta Geologica Sinica - English Edition 94, 530-544.

Nagashima, H.D., Miyagi, T., Yasuda, K., Ohmura, R., 2020. Clathrate hydrates at temperatures below the freezing point of water: A review. Fluid Phase Equilibria 517, 112610.

Truong-Lam, H.S., Seo, S., Kim, S., Seo, Y., Lee, J.D., 2020. In situ Raman study of the formation and dissociation kinetics of methane and methane/propane hydrates. Energy & Fuels 34, 6288-6297.

Waage, M., Serov, P., Andreassen, K., Waghorn, K.A., Bünz, S., 2020. Geological controls of giant crater development on the Arctic seafloor. Scientific Reports 10, 8450.


Wang, Y.-F., Wang, L.-B., Li, Y., Gu, J.-X., Sun, C.-Y., Chen, G.-J., Wang, X.-H., Yuan, Q., Li, N., 2020. Effect of temperature on gas production from hydrate-bearing sediments by using a large 196-L reactor. Fuel 275, 117963.


Yasue, M., Masuda, Y., Liang, Y., 2020. Estimation of methane recovery efficiency from methane hydrate by the N2–CO2 gas mixture injection method. Energy & Fuels 34, 5236-5250.


Zhang, L., Xia, X., Liu, S., Zhang, S., Li, S., Wang, J., Wang, G., Gao, H., Zhang, Z., Wang, Q., Wen, W., Liu, R., Yang, Z., Stanley, E.H., Raymond, P.A., 2020. Significant methane ebullition from alpine permafrost rivers on the East Qinghai–Tibet Plateau. Nature Geoscience 13, 349-354.


Isotope Geochemistry





Gussone, N., Ahm, A.-S.C., Lau, K.V., Bradbury, H.J., 2020. Calcium isotopes in deep time: Potential and limitations. Chemical Geology 544, 119601.

He, D., Nemiah Ladd, S., Saunders, C.J., Mead, R.N., Jaffé, R., 2020. Distribution of n-alkanes and their δ2H and δ13C values in typical plants along a terrestrial-coastal-oceanic gradient. Geochimica et Cosmochimica Acta 281, 31-52.


Pang, K.-N., Teng, F.-Z., Sun, Y., Chung, S.-L., Zarrinkoub, M.H., 2020. Magnesium isotopic systematics of the Makran arc magmas, Iran: Implications for crust-mantle Mg isotopic balance. Geochimica et Cosmochimica Acta 278, 110-121.

Reynard, L.M., Ryan, S.E., Guirguis, M., Contreras-Martínez, M., Pompianu, E., Ramis, D., van Dommelen, P., Tuross, N., 2020. Mediterranean precipitation isoscape preserved in bone collagen δ2H. Scientific Reports 10, 8579.

Tang, T., Cheng, Z., Xu, B., Zhang, B., Zhu, S., Cheng, H., Li, J., Chen, Y., Zhang, G., 2020. Triple isotopes (δ13C, δ2H, and Δ14C) compositions and source apportionment of atmospheric naphthalene: A key surrogate of intermediate-volatility organic compounds (IVOCs). Environmental Science & Technology 54, 5409-5418.

Teng, F.-Z., Hu, Y., Ma, J.-L., Wei, G.-J., Rudnick, R.L., 2020. Potassium isotope fractionation during continental weathering and implications for global K isotopic balance. Geochimica et Cosmochimica Acta 278, 261-271.

Tian, Q., Bai, Y., Fang, X., Chen, C., Liu, X., 2020. Responses of sedimentary δ2Halk values to environmental changes as revealed by different plant responses to altitude and altitude-related temperatures. Science of The Total Environment 733, 138087.

Vasil’chuk, Y.K., Vasil’chuk, J.Y., Budantseva, N.A., Vasil’chuk, A.C., 2020. New AMS dates of organic microinclusions in ice wedges from the lower part of Batagay Yedoma, Yakutia. Doklady Earth Sciences 490, 100-103.



Zhang, Z., Volkman, J.K., 2020. Isotopically enriched n-alkan-2-ones with even chain predominance in a torbanite from the Sydney Basin, Australia. Organic Geochemistry 144, 104018.

CLUMPED ISOTOPES

Fosu, B.R., Subba, R., Peethambaran, R., Bhattacharya, S.K., Ghosh, P., 2020. Technical note: Developments and applications in triple oxygen isotope analysis of carbonates. ACS Earth and Space Chemistry 4, 702-710.

Methner, K., Campani, M., Fiebig, J., Löffler, N., Kempf, O., Mulch, A., 2020. Middle Miocene long-term continental temperature change in and out of pace with marine climate records. Scientific Reports 10, 7989.

Price, G.D., Bajnai, D., Fiebig, J., 2020. Carbonate clumped isotope evidence for latitudinal seawater temperature gradients and the oxygen isotope composition of Early Cretaceous seas. Palaeogeography, Palaeoclimatology, Palaeoecology 552, 109777.

METHODS/INSTRUMENTATION

Riekenberg, P.M., van der Meer, M., Schouten, S., 2020. Practical considerations for improved reliability and precision during determination of δ15N values in amino acids using a single combined oxidation–reduction reactor. Rapid Communications in Mass Spectrometry 34, e8797.

Mathematical Geochemistry/Phase Behavior

Khamehchi, E., Mahdiani, M.R., Amooie, M.A., Hemmati-Sarapardeh, A., 2020. Modeling viscosity of light and intermediate dead oil systems using advanced computational frameworks and artificial neural networks. Journal of Petroleum Science and Engineering 193, 107388.

Romero Yanes, J.F., Ferreira, A.F.B., Gomes de Medeiros, P.Y., Bassani, G.S., Fleming, F.P., Feitosa, F.X., de Sant’Ana, H.B., 2020. Phase behavior for crude oil and methane mixtures: Crude oil property comparison. Energy & Fuels 34, 5188-5195.

Microbiology/Extremophiles



He, X.-L., Zhou, D., Gao, H., Huang, F.-q., Li, H., Lv, J., 2020. Dyadobacter bucti sp. nov., isolated from subsurface sediment. International Journal of Systematic and Evolutionary Microbiology 70, 2281-2287.

Hogendoorn, C., Pol, A., Picone, N., Cremers, G., van Alen, T.A., Gagliano, A.L., Jetten, M.S.M., D’Alessandro, W., Quatrini, P., Op den Camp, H.J.M., 2020. Hydrogen and carbon monoxide-utilizing Kyrpidia spormannii species from Pantelleria Island, Italy. Frontiers in Microbiology 11, 951. doi: 910.3389/fmicb.2020.00951.

Kim, J., Chhetri, G., Kim, I., Lee, B., Jang, W., Kim, M.K., Seo, T., 2020. Methylobacterium terricola sp. nov., a gamma radiation-resistant bacterium isolated from gamma ray-irradiated soil. International Journal of Systematic and Evolutionary Microbiology 70, 2449-2456.

Kim, Y.B., Kim, J.Y., Song, H.S., Lee, S.H., Shin, N.-R., Bae, J.-W., Myoung, J., Lee, K.-E., Cha, I.-T., Rhee, J.-K., Roh, S.W., 2020. Haloplanus rubicundus sp. nov., an extremely halophilic archaeon isolated from solar salt. Systematic and Applied Microbiology 43, 126085.


Sass, K., Perner, M., 2020. Characterization of two hydrogen-oxidizing Hydrogenovibrio strains from Kermadec volcanic island arc hydrothermal vents. Frontiers in Marine Science 7, 295. doi: 210.3389/fmars.2020.00295.

MICROBIAL ECOSYSTEMS

Bottos, E.M., Laughlin, D.C., Herbold, C.W., Lee, C.K., McDonald, I.R., Cary, S.C., 2020. Abiotic factors influence patterns of bacterial diversity and community composition in the Dry Valleys of Antarctica. FEMS Microbiology Ecology 96, fiaa042.

Giongo, A., Haag, T., Medina-Silva, R., Heemann, R., Pereira, L.M., Zamberlan, P.M., Valdez, F.P., Oliveira, R.R., Eizirik, E., Viana, A.R., Ketzer, J.M.M., 2020. Distinct deep subsurface microbial communities in two sandstone units separated by a mudstone layer. Geosciences Journal 24, 267-274.


Hand, K.P., Bartlett, D.H., Fryer, P., Peoples, L., Williford, K., Hofmann, A.E., Cameron, J., 2020. Discovery of novel structures at 10.7 km depth in the Mariana Trench may reveal chemolithoautotrophic microbial communities. Deep Sea Research Part I: Oceanographic Research Papers 160, 103238.


Kalwasińska, A., Krawiec, A., Deja-Sikora, E., Gołębiewski, M., Kosobucki, P., Swiontek Brzezinska, M., Walczak, M., 2020. Microbial diversity in deep-subsurface hot brines of

northwest Poland: From community structure to isolate characteristics. Applied and Environmental Microbiology 86, e00252-00220.

Lincy, J., Manohar, C.S., 2020. A comparison of bacterial communities from OMZ sediments in the Arabian Sea and the Bay of Bengal reveals major differences in nitrogen turnover and carbon recycling potential. Biogeosciences Discussions 2020, 1-28.

Liu, J., Zhu, S., Liu, X., Yao, P., Ge, T., Zhang, X.-H., 2020. Spatiotemporal dynamics of the archaeal community in coastal sediments: assembly process and co-occurrence relationship. The ISME Journal 14, 1463-1478.

Mahmoudi, N., Enke, T.N., Beaupré, S.R., Teske, A.P., Cordero, O.X., Pearson, A., 2020. Illuminating microbial species-specific effects on organic matter remineralization in marine sediments. Environmental Microbiology 22, 1734-1747.

Motamedi, S., Orcutt, B.N., Früh-Green, G.L., Twing, K.I., Pendleton, H.L., Brazelton, W.J., 2020. Microbial residents of the Atlantis Massif’s shallow serpentinite subsurface. Applied and Environmental Microbiology 86, e00356-00320.




Xue, Y., Jonassen, I., Øvreås, L., Taş, N., 2020. Metagenome-assembled genome distribution and key functionality highlight importance of aerobic metabolism in Svalbard permafrost. FEMS Microbiology Ecology 96, fiaa057.

Zhang, H., Hou, F., Xie, W., Wang, K., Zhou, X., Zhang, D., Zhu, X., 2020. Interaction and assembly processes of abundant and rare microbial communities during a diatom bloom process. Environmental Microbiology 22, 1707-1719.


PETROLEUM DEGRADERS






Nisenbaum, M., Corti-Monzón, G., Villegas-Plazas, M., Junca, H., Mangani, A., Patat, M.L., González, J.F., Murialdo, S.E., 2020. Enrichment and key features of a robust and consistent indigenous marine-cognate microbial consortium growing on oily bilge wastewaters. Biodegradation 31, 91-108.

Pannekens, M., Voskuhl, L., Meier, A., Müller, H., Haque, S., Frösler, J., Brauer, V.S., Meckenstock, R.U., 2020. Densely populated water droplets in heavy-oil seeps. Applied and Environmental Microbiology 86, e00164-00120.

Ruan, Z.-p., Cao, W.-m., Zhang, X., Liu, J.-t.-y., Zhu, J.-c., Hu, B., Jiang, J.-d., 2020. Rhizobium terrae sp. nov., isolated from an oil-contaminated soil in China. Current Microbiology 77, 1117-1124.


Santos, J.C.d., Lopes, D.R.G., Da Silva, J.D., De Oliveira, M.D., Dias, R.S., Lima, H.S., De Sousa, M.P., De Paula, S.O., Silva, C.C.d., 2020. Diversity of sulfate-reducing prokaryotes in petroleum production water and oil samples. International Biodeterioration & Biodegradation 151, 104966.

Yang, R., Zhang, B., Wang, J., Tai, X., Sun, H., Zhang, G., Zhang, W., Chen, T., Liu, G., 2020. Planococcus lenghuensis sp. nov., an oil-degrading bacterium isolated from petroleum-contaminated soil. Antonie van Leeuwenhoek 113, 839-850.

Zhang, Y.-X., Li, X., Li, F.-L., Ma, S.-C., Zheng, G.-D., Chen, W.-F., Li, W.-J., Wang, L., 2020. Paracoccus alkanivorans sp. nov., isolated from a deep well with oil reservoir water. International Journal of Systematic and Evolutionary Microbiology 70, 2312-2317.

Zhou, L., Lu, Y.-W., Wang, D.-W., Zhang, S.-L., Tang, E.-G., Qi, Z.-Z., Xie, S.-N., Wu, J., Liang, B., Liu, J.-F., Yang, S.-Z., Zhang, J., Gu, J.-D., Mu, B.-Z., 2020. Microbial community composition and diversity in production water of a high-temperature offshore

oil reservoir assessed by DNA- and RNA-based analyses. International Biodeterioration & Biodegradation 151, 104970.

Paleoclimatology/Paleoceanography


Brandon, M., Landais, A., Duchamp-Alphonse, S., Favre, V., Schmitz, L., Abrial, H., Prié, F., Extier, T., Blunier, T., 2020. Exceptionally high biosphere productivity at the beginning of Marine Isotopic Stage 11. Nature Communications 11, 2112.

Bulgin, C.E., Merchant, C.J., Ferreira, D., 2020. Tendencies, variability and persistence of sea surface temperature anomalies. Scientific Reports 10, 7986.

Camillo, E., Quadros, J.P., Santarosa, A.C.A., Costa, K.B., Toledo, F.A.L., 2020. An abrupt cooling event recorded around 73 kyr in western South Atlantic. Quaternary International 542, 80-87.

Cao, J., Rao, Z., Shi, F., Jia, G., 2020. Ice formation on lake surfaces in winter causes warm-season bias of lacustrine brGDGT temperature estimates. Biogeosciences 17, 2521-2536.

Dauner, A.L.L., Mollenhauer, G., Bícego, M.C., Martins, C.C., 2020. Cluster analysis for time series based on organic geochemical proxies. Organic Geochemistry 145, 104038.

de Nooijer, W., Zhang, Q., Li, Q., Zhang, Q., Li, X., Zhang, Z., Guo, C., Nisancioglu, K.H., Haywood, A.M., Tindall, J.C., Hunter, S.J., Dowsett, H.J., Stepanek, C., Lohmann, G., Otto-Bliesner, B.L., Feng, R., Sohl, L.E., Tan, N., Contoux, C., Ramstein, G., Baatsen, M.L.J., von der Heydt, A.S., Chandan, D., Peltier, W.R., Abe-Ouchi, A., Chan, W.-L., Kamae, Y., Brierley, C.M., 2020. Evaluation of Arctic warming in mid-Pliocene climate simulations. Climate of the Past Discussions 2020, 1-30.

Fontorbe, G., Frings, P.J., De La Rocha, C.L., Hendry, K.R., Conley, D.J., 2020. Constraints on Earth system functioning at the Paleocene-Eocene Thermal Maximum from the marine silicon cycle. Paleoceanography and Paleoclimatology 35, e2020PA003873.

Hutchinson, D.K., Coxall, H.K., Lunt, D.J., Steinthorsdottir, M., de Boer, A.M., Baatsen, M., von der Heydt, A., Huber, M., Kennedy-Asser, A.T., Kunzmann, L., Ladant, J.-B., Lear, C.H., Moraweck, K., Pearson, P.N., Piga, E., Pound, M.J., Salzmann, U., Scher, H.D., Sijp, W.P., Śliwińska, K.K., Wilson, P.A., Zhang, Z., 2020. The Eocene-Oligocene transition: a review of marine and terrestrial proxy data, models and model-data comparisons. Climate of the Past Discussions 2020, 1-71.

Kessler, A., Bouttes, N., Roche, D.M., Ninnemann, U.S., Galaasen, E.V., Tjiputra, J., 2020. Atlantic Meridional Overturning Circulation and δ13C variability during the last interglacial. Paleoceanography and Paleoclimatology 35, e2019PA003818.

Li, X., Wang, J., Rasbury, T., Zhou, M., Zhang, C., 2020. Early Jurassic climate and atmospheric CO2 concentration in the Sichuan paleobasin, Southwest China. Climate of the Past Discussions 2020, 1-35.

Marcantonio, F., Hostak, R., Hertzberg, J.E., Schmidt, M.W., 2020. Deep equatorial Pacific Ocean oxygenation and atmospheric CO2 over the last ice age. Scientific Reports 10, 6606.


Miller, K.G., Browning, J.V., Schmelz, W.J., Kopp, R.E., Mountain, G.S., Wright, J.D., 2020. Cenozoic sea-level and cryospheric evolution from deep-sea geochemical and continental margin records. Science Advances 6, eaaz1346.

Naafs, B.D.A., Voelker, A.H.L., Karas, C., Andersen, N., Sierro, F.J., 2020. Repeated near-collapse of the Pliocene sea surface temperature gradient in the North Atlantic. Paleoceanography and Paleoclimatology 35, e2020PA003905.

Pletnev, S.P., Wu, Y., Romanova, A.V., Annin, V.K., Utkin, I.V., Vereshchagina, O.F., 2020. Negative δ13C excursions in foraminiferal records: The Holocene history of methane events in the central Sea of Okhotsk. Russian Geology and Geophysics 61, DOI: 10.15372/RGG2019107.



Richey, J.D., Montañez, I.P., Goddéris, Y., Looy, C.V., Griffis, N.P., DiMichele, W.A., 2020. Influence of temporally varying weatherability on CO2–climate coupling and ecosystem change in the late Paleozoic. Climate of the Past Discussions 2020, 1-37.

Rizzi, M., Thibault, N., Ullmann, C.V., Ruhl, M., Olsen, T.K., Moreau, J., Clémence, M.-E., Mette, W., Korte, C., 2020. Sedimentology and carbon isotope stratigraphy of the Rhaetian Hochalm section (Late Triassic, Austria). Global and Planetary Change 191, 103210.


Sun, W., Zhang, E., Chang, J., Shulmeister, J., Bird, M.I., Zhao, C., Jiang, Q., Shen, J., 2020. Archaeal lipid-inferred paleohydrology and paleotemperature of Lake Chenghai during the Pleistocene–Holocene transition. Climate of the Past 16, 833-845.

Super, J.R., Thomas, E., Pagani, M., Huber, M., O'Brien, C.L., Hull, P.M., 2020. Miocene evolution of North Atlantic Sea surface temperature. Paleoceanography and Paleoclimatology 35, e2019PA003748.

Vorrath, M.-E., Müller, J., Rebolledo, L., Cárdenas, P., Shi, X., Esper, O., Opel, T., Geibert, W., Muñoz, P., Haas, C., Lange, C.B., Lohmann, G., Mollenhauer, G., 2020. Sea ice dynamics at

the Western Antarctic Peninsula during the industrial era: a multi-proxy intercomparison study. Climate of the Past Discussions 2020, 1-43.


Weber, J., Bauersachs, T., Schwark, L., 2020. A multiphasic Younger Dryas cold period recorded in sediments of Lake Steisslingen, SW-Germany: A biomarker perspective. Quaternary International 542, 121-136.

Wu, R., Liu, J., Calner, M., Gong, F., Lehnert, O., Luan, X., Li, L., Zhan, R., 2020. High-resolution carbon isotope stratigraphy of the Lower and Middle Ordovician succession of the Yangtze Platform, China: implications for global correlation. Journal of the Geological Society 177, 537.

Yang, Y., Ruan, X., Gao, C., Lü, X., Yang, H., Li, X., Yao, Y., Pearson, A., Xie, S., 2020. Assessing the applicability of the long-chain diol (LDI) temperature proxy in the high-temperature South China Sea. Organic Geochemistry 144, 104017.

Zhang, Y.G., Henderiks, J., Liu, X., 2020. Refining the alkenone-pCO2 method II: Towards resolving the physiological parameter ‘b’. Geochimica et Cosmochimica Acta 281, 118-134.


Zhao, Y., Tzedakis, P.C., Li, Q., Qin, F., Cui, Q., Liang, C., Birks, H.J.B., Liu, Y., Zhang, Z., Ge, J., Zhao, H., Felde, V.A., Deng, C., Cai, M., Li, H., Ren, W., Wei, H., Yang, H., Zhang, J., Yu, Z., Guo, Z., 2020. Evolution of vegetation and climate variability on the Tibetan Plateau over the past 1.74 million years. Science Advances 6, eaay6193.

EXTINCTION EVENTS

Bond, D.P.G., Wignall, P.B., Grasby, S.E., 2020. The Capitanian (Guadalupian, Middle Permian) mass extinction in NW Pangea (Borup Fiord, Arctic Canada): A global crisis driven by volcanism and anoxia. GSA Bulletin 132, 931-942.

Fujisaki, W., Fukami, Y., Matsui, Y., Sato, T., Sawaki, Y., Suzuki, K., 2020. Redox conditions and nitrogen cycling during the Triassic-Jurassic transition: A new perspective from the mid-Panthalassa. Earth-Science Reviews 204, 103173.

Hu, D., Li, M., Zhang, X., Turchyn, A.V., Gong, Y., Shen, Y., 2020. Large mass-independent sulphur isotope anomalies link stratospheric volcanism to the Late Ordovician mass extinction. Nature Communications 11, 2297.

Marshall, J.E.A., Lakin, J., Troth, I., Wallace-Johnson, S.M., 2020. UV-B radiation was the Devonian-Carboniferous boundary terrestrial extinction kill mechanism. Science Advances 6, eaba0768.


Voosen, P., 2020. UV radiation blamed in ancient mass extinction. Science 368, 926.

Wignall, P.B., Bond, D.P.G., Grasby, S.E., Pruss, S.B., Peakall, J., 2020. Controls on the formation of microbially induced sedimentary structures and biotic recovery in the Lower Triassic of Arctic Canada. GSA Bulletin 132, 918-930.

Wu, Y., Tong, J., Algeo, T.J., Chu, D., Cui, Y., Song, H., Shu, W., Du, Y., 2020. Organic carbon isotopes in terrestrial Permian-Triassic boundary sections of North China: Implications for global carbon cycle perturbations. GSA Bulletin 132, 1106-1118.

Yao, L., Aretz, M., Chen, J., Qi, Y., 2020. Earliest Carboniferous stromatolites from the Qianheishan Formation, Dashuigou section, northwestern China: Implications for microbial proliferation after the end-Devonian mass extinction. Geological Journal 55, 3361-3376.


Zheng, D., Chang, S.-C., Algeo, T., Zhang, H., Wang, B., Wang, H., Wang, J., Feng, C., Xu, H., 2020. Age constraint for an earliest Famennian forest and its implications for Frasnian-Famennian boundary in West Junggar, Northwest China. Palaeogeography, Palaeoclimatology, Palaeoecology 552, 109749.

Petroleum Systems

EXPLORATION

Adegoke, A.K., Hakimi, M.H., Abdullah, W.H., Ibrahim, E.-K., Sarki Yandoka, B.M., Al Faifi, H., Lashin, A., 2020. Geochemistry and oil-gas generation modeling of the Late Cretaceous shales from the Chad (Bornu) Basin, Northeast Nigeria. Journal of Natural Gas Science and Engineering 79, 103341.

Bai, Z., Cheng, M., Chen, C., Huo, J., Zhang, J., Zhou, X., Gao, Y., Zhao, B., Qiu, H., Han, M., Yang, Y., Sun, Z., Miao, M., Zhang, J., Li, Q., 2020. Distribution features of the Nanhua-Sinian rifts and their significance to hydrocarbon accumulation in the Tarim Basin. Acta Geologica Sinica - English Edition 94, 501-515.

Bian, C., Li, Y., Bai, B., Zhou, X., Liu, J., 2020. The hydrocarbon accumulation potential of Upper Cretaceous to Paleogene in the northern Kaikang trough, Muglad Basin. Arabian Journal of Geosciences 13, 352.

Broadley, L., Schofield, N., Jolley, D., Howell, J., Underhill, J.R., 2020. UK Rockall prospectivity: re-awakening exploration in a frontier basin. Petroleum Geoscience 26, 247.


Fyfe, L.-J.C., Schofield, N., Holford, S.P., Heafford, A., Raine, R., 2020. Geology and petroleum prospectivity of the Larne and Portpatrick basins, North Channel, offshore SW Scotland and Northern Ireland. Petroleum Geoscience 26, 272.

Guellala, R., Abdelmoumen, K., Sarsar Naouali, B., Mahroug, A., 2020. Contribution of well logging and seismic reflection to the Jurassic petroleum system characterization in the Chotts zone (Southern Tunisia). Journal of Petroleum Exploration and Production Technology 10, 1763-1773.

Hakimi, M.H., Ahmed, A., Mogren, S., Ali Shah, S.B., Kinawy, M.M., Lashin, A.A., 2020. Thermogenic gas generation from organic-rich shales in the southeastern Say'un-Masila Basin, Yemen as demonstrated by geochemistry, organic petrology, and basin modeling. Journal of Petroleum Science and Engineering 192, 107322.

Liu, D., Li, J., Liu, J.-q., Zhang, L., 2020. Modeling hydrocarbon accumulation based on gas origin and source rock distribution in Paleozoic strata of the Ordos Basin, China. International Journal of Coal Geology 225, 103486.




Yang, C., Sun, J., Yang, Y., Yang, C., Wang, J., Xiao, G., Wang, J., 2020. Key factors controlling Mesozoic hydrocarbon accumulation in the Southern East China Sea Basin. Marine and Petroleum Geology 118, 104436.

GENERATION & EXPULSION

Kayukova, G.P., Mikhailov, A.N., Kosachev, I.P., Morozov, V.P., Vakhin, A.V., 2020. Hydrothermal transformations of organic matter of carbon-rich Domanik rock in carbon dioxide environment at different temperatures. Petroleum Chemistry 60, 278-290.

Smirnov, M.B., Borisov, R.S., Vanyukova, N.A., 2020. A new reaction involved in forming the composition of oils: Methylation of aromatic cycles. Geochemistry International 58, 520-530.

Smirnov, M.B., Brodskii, E.S., Vanyukova, N.A., 2020. A new type of aromatic petroleum hydrocarbons: Phenyl-substituted tri- and tetracycloaromatics. Petroleum Chemistry 60, 270-277.

Stockhausen, M., Galimberti, R., Elias, R., Di Paolo, L., Schwark, L., 2020. The Expulsinator versus conventional pyrolysis: The differences of oil/gas generation and expulsion simulation under near-natural conditions. Marine and Petroleum Geology 117, 104412.

Xie, X., Li, M., Xu, J., Snowdon, L.R., Volkman, J.K., 2020. Geochemical characterization and artificial thermal maturation of kerogen density fractions from the Eocene Huadian oil shale, NE China. Organic Geochemistry 144, 103947.

Xie, X., Snowdon, L.R., Volkman, J.K., Li, M., Xu, J., Qin, J., 2020. Inter-maceral effects on hydrocarbon generation as determined using artificial mixtures of purified macerals. Organic Geochemistry 144, 104036.

OIL & GAS


Chen, Z., Wang, Z., Zhang, S., Gao, Y., Han, C., Li, K., 2020. Biomarker characteristics of source rocks and oil source correlation in Baolegentaohai sag, Erlian Basin. Acta Sedimentologica Sinica 38, 451-462

Enrico, M., Mere, A., Zhou, H., Carrier, H., Tessier, E., Bouyssiere, B., 2020. Experimental tests of natural gas samplers prior to mercury concentration analysis. Energy & Fuels 34, 5205-5212.

Esegbue, O., Jones, M., van Bergen, P.F., Kolonic, S., 2020. Quantitative diamondoid analysis indicates oil cosourcing from a deep petroleum system onshore Niger Delta Basin. American Association of Petroleum Geologists Bulletin 104, 1231-1259.

Han, Q., Li, M., Liu, X., Jiang, W., Shi, S., Tang, Y., He, D., 2020. Fractionation of alkylated carbazoles in petroleum during subsurface migration: Evidence from molecular simulation and application in sandstone reservoirs. Journal of Petroleum Science and Engineering 191, 107308.

Hu, A., Niu, C., Wang, D., Li, H., Ye, T., Xu, P., 2020. The characteristics and formation mechanism of condensate oil and gas in Bozhong19-6 structure, Bozhong sag, Bohai Bay Basin Acta Petrolei Sinica 41, 403-411

Kotarba, M.J., Bilkiewicz, E., Więcław, D., Radkovets, N.Y., Koltun, Y.V., Kowalski, A., Kmiecik, N., Romanowski, T., 2020. Origin and migration of oil and natural gas in the central part of the Ukrainian outer Carpathians: Geochemical and geological approach. American Association of Petroleum Geologists Bulletin 104, 1323-1356.

Lin, M., Wang, Y., Cao, Y., Wang, Y., Wang, X., Xi, K., 2020. Experimental study of the influence of oil-wet calcite cements on oil migration and implications for clastic reservoirs. Marine and Petroleum Geology 118, 104427.



Miranda, M.A., Subramani, H.J., Mohammad, S.A., Aichele, C.P., 2020. Kinetics of gas evolution from supersaturated oils at elevated pressures and temperatures. Energy & Fuels 34, 5537-5544.


Plummer, P.S., 2020. GC profiles of oils reflect organic maturity rather than depositional environment of parent source rock: examples from Central Australia. Australian Journal of Earth Sciences 67, 739-747.

Ran, Y., Zhou, X., 2020. Geochemical characteristics and genesis of tight gas in Shahezi Formation, Xujiaweizi Fault Depression, North Songliao Basin, China. Journal of Natural Gas Geoscience 5, 69-79.



Tao, K., Cao, J., Wang, Y., Mi, J., Ma, W., Shi, C., 2020. Chemometric classification of crude oils in complex petroleum systems using t-distributed stochastic neighbor embedding machine learning algorithm. Energy & Fuels 34, 5884-5899.

Wang, T., Zhang, D.-L., Yang, X.-Y., Xu, J.-Q., Matthew, C., Tang, Y.-J., 2020. Light hydrocarbon geochemistry: insight into oils/condensates families and inferred source rocks of the Woodford–Mississippian tight oil play in North-Central Oklahoma, USA. Petroleum Science 17, 582-597.

SOURCE ROCKS

Bai, Y., Ma, Y., 2020. Geology of the Chang 7 Member oil shale of the Yanchang Formation of the Ordos Basin in central north China. Petroleum Geoscience 26, 355.


Bojesen-Koefoed, J.A., Alsen, P., Bjerager, M., Hovikoski, J., Ineson, J., Nytoft, H.P., Nøhr-Hansen, H., Petersen, H.I., Pilgaard, A., Vosgerau, H., 2020. A mid-Cretaceous petroleum source-rock in the North Atlantic region? Implications of the Nanok-1 fully cored borehole, Hold with Hope, northeast Greenland. Marine and Petroleum Geology 117, 104414.

Caro Gonzalez, L.D., Mastalerz, M., Filho, J.G.M., 2020. Application of organic facies and biomarkers in characterization of paleoenvironmental conditions and maturity of sediments from the Codó Formation in the west-central part of the São Luís Basin, Brazil. International Journal of Coal Geology 225, 103482.

Chen, G., Gang, W., Chang, X., Wang, N., Zhang, P., Cao, Q., Xu, J., 2020. Paleoproductivity of the Chang 7 unit in the Ordos Basin (North China) and its controlling factors. Palaeogeography, Palaeoclimatology, Palaeoecology 551, 109741.

Chen, Y., Lin, S., Bai, B., Zhang, T., Pang, Z., Tao, S., Hu, S., 2020. Effects of petroleum retention and migration within the Triassic Chang 7 Member of the Ordos Basin, China. International Journal of Coal Geology 225, 103502.

Chen, Z., Chen, J., Zhong, N., Fei, W., Dong, Q., Chen, J., Wang, Y., 2020. The geneses of sedimentary organic matter with anomalous 13C-enriched isotopic composition in saline and freshwater lakes: A case study of lacustrine source rocks from Dongpu and Qikou sags, Bohai Bay Basin, eastern China. Marine and Petroleum Geology 118, 104434.

Chenrai, P., Fuengfu, S., 2020. Organic geochemistry of the Lower Permian Tak Fa Formation in Phetchabun Province, Thailand: implications for its paleoenvironment and hydrocarbon generation potential. Acta Geochimica 39, 291-306.

Fan, X., Mao, X., Liu, Z., Geng, T., Wang, H., 2020. Organic geochemical characteristics and hydrocarbon generation potential of Jurassic shales and mudstones in Qixiang Co area southern Qiangtang Basin, Tibet. Journal of Petroleum Science and Engineering 193, 107377.

French, K.L., Birdwell, J.E., Lewan, M.D., 2020. Trends in thermal maturity indicators for the organic sulfur-rich Eagle Ford Shale. Marine and Petroleum Geology 118, 104459.

Ganeeva, Y.M., Barskaya, E.E., Yusupova, T.N., Okhotnikova, E.S., Sotnikov, O.S., Remeev, M.M., Khisamov, R.S., 2020. Comparative analysis of organic matter of reservoir rocks and Domanik deposits of the Bavly oil field. Petroleum Chemistry 60, 255-263.

Gao, G., Cao, J., Luo, B., Xiao, D., Zhang, Y., Chen, C., 2020. Evidence of the Middle Permian marine mixed type source rocks in the northwestern Sichuan Basin and its contribution to large gas reservoirs in Shuangyushi area Acta Petrolei Sinica 41, 433-445.



Jin, S., Wang, H., Cao, H., Gan, H., Chen, S., 2020. Lake-type controls on sedimentary infill and petroleum source rocks in the Palaeogene Fushan Depression, Beibuwan Basin, South China. Geological Journal 55, 3936-3956.

Kibria, M.G., Das, S., Hu, Q.-H., Basu, A.R., Hu, W.-X., Mandal, S., 2020. Thermal maturity evaluation using Raman spectroscopy for oil shale samples of USA: comparisons with vitrinite reflectance and pyrolysis methods. Petroleum Science 17, 567-581.

Liu, M., Sun, P., Them, T.R., Li, Y., Sun, S., Gao, X., Huang, X., Tang, Y., 2020. Organic geochemistry of a lacustrine shale across the Toarcian Oceanic Anoxic Event (Early Jurassic) from NE China. Global and Planetary Change 191, 103214.

Pisarzowska, A., Becker, R.T., Aboussalam, Z.S., Szczerba, M., Sobień, K., Kremer, B., Owocki, K., Racki, G., 2020. Middlesex/punctata Event in the Rhenish Basin (Padberg section, Sauerland, Germany) – Geochemical clues to the early-middle Frasnian perturbation of global carbon cycle. Global and Planetary Change 191, 103211.

Rui, J., Zhang, H., Ren, Q., Yan, L., Guo, Q., Zhang, D., 2020. TOC content prediction based on a combined Gaussian process regression model. Marine and Petroleum Geology 118, 104429.

Setta, F., Bergamaschi, S., Rodrigues, R., Jones, C., Chaves, H., Brito, M., Pereira, E., 2020. The volumetric potential assessment of the oil shales of Tremembé Formation, Taubaté Basin, Brazil. Journal of Petroleum Exploration and Production Technology 10, 1835-1848.

Sun, T., Luo, X., Qing, H., Kou, X., Sheng, Z., Xu, G., Zuo, Y., 2020. Characteristics and natural gas origin of Middle–Late Triassic marine source rocks of the western Sichuan depression, SW China. Acta Geologica Sinica - English Edition 94, 376-398.


Tiwari, B., Ojha, A., Ghosh, S., Varma, A.K., Mendhe, V.A., Mondal, A., 2020. A composite microstructural and geochemical approach to quench the quest for hydrocarbon from Barren Measures shales of Jharia Basin, India. Journal of Natural Gas Science and Engineering 78, 103310.

Walters, A.P., Meyers, S.R., Carroll, A.R., Hill, T.R., Vanden Berg, M.D., 2020. Lacustrine cyclicity in the early Eocene Green River Formation, Uinta Basin, Utah: Evidence from X-ray fluorescence core scanning. Journal of Sedimentary Research 90, 429-447.



Xu, H., Hou, D., Löhr, S.C., Liu, Q., George, S.C., 2020. Early diagenetic pyrite cementation influences molecular composition of sedimentary organic matter in the Dongying Depression, China. Organic Geochemistry 144, 104019.


Yang, S., Horsfield, B., 2020. Critical review of the uncertainty of Tmax in revealing the thermal maturity of organic matter in sedimentary rocks. International Journal of Coal Geology 225, 103500.

Yu, K., Ju, Y., Zhang, B., 2020. Modeling of tectono-thermal evolution of Permo-Carboniferous source rocks in the southern Qinshui Basin, China: Consequences for hydrocarbon generation. Journal of Petroleum Science and Engineering 193, 107343.

Zakrzewski, A., Kosakowski, P., Waliczek, M., Kowalski, A., 2020. Polycyclic aromatic hydrocarbons in Middle Jurassic sediments of the Polish Basin provide evidence for high-temperature palaeo-wildfires. Organic Geochemistry 145, 104037.

Zhang, Y., Sun, Y., Chen, J., 2020. Stable carbon isotope evidence for the origin of C28 steranes in lacustrine source rocks from the Qikou Sag, Bohai Bay Basin, Eastern China. Organic Geochemistry 145, 104028.

Precambrian Geochemistry



Han, T., Fan, H., Wen, H., Mo, B., Murowchick, J.B., Lu, Z., Algeo, T.J., 2020. Petrography and sulfur isotopic compositions of SEDEX ores in the early Cambrian Nanhua Basin, South China. Precambrian Research 345, 105757.

Hao, J., Knoll, A.H., Huang, F., Schieber, J., Hazen, R.M., Daniel, I., 2020. Cycling phosphorus on the Archean Earth: Part II. Phosphorus limitation on primary production in Archean ecosystems. Geochimica et Cosmochimica Acta 280, 360-377.

Planavsky, N.J., Reinhard, C.T., Isson, T.T., Ozaki, K., Crockford, P.W., 2020. Large mass-independent oxygen isotope fractionations in Mid-Proterozoic sediments: Evidence for a low-oxygen atmosphere? Astrobiology 20, 628-636.

Shahkarami, S., Buatois, L.A., Mángano, M.G., Hagadorn, J.W., Almond, J., 2020. The Ediacaran–Cambrian boundary: Evaluating stratigraphic completeness and the Great Unconformity. Precambrian Research 345, 105721.

Ugelow, M.S., Berry, J.L., Browne, E.C., Tolbert, M.A., 2020. The impact of molecular oxygen on anion composition in a hazy Archean Earth atmosphere. Astrobiology 20, 658-669.

ORGANICS/MICROFOSSILS/MICROBIAL EVOLUTION

Canfield, D.E., Knoll, A.H., Poulton, S.W., Narbonne, G.M., Dunning, G.R., 2020. Carbon isotopes in clastic rocks and the Neoproterozoic carbon cycle. American Journal of Science 320, 97-124.

Jiang, S., Wang, G., Li, S., Wang, G., Li, X., Zhang, H., Zhang, W., Cao, W., Dai, L., Suo, Y., Somerville, I., 2020. Potential deep-buried petroleum systems in Meso-Neoproterozoic rifts of the southwestern North China Craton revealed by gravity anomalies. Precambrian Research 346, 105764.

Khullar, S., Pandita, S.K., Meinhold, G., Bhat, G.M., Raina, B.K., Thusu, B., Jones, M.J., 2020. Discovery of organic matter and palynomorphs from the Neoproterozoic Zor diamictite of the Ramsu Formation in the Ramban District, Jammu and Kashmir, India. Journal of the Geological Society of India 95, 447-454.

Knoll, A.H., Germs, G.J.B., Tankard, A., Welsink, H., 2020. Tonian microfossils from subsurface shales in Botswana. Precambrian Research 345, 105779.



O'Neil, G.R., Tackett, L.S., Meyer, M., 2020. Petrographic evidence for Ediacaran microbial mat-targeted behaviors from the Great Basin, United States. Precambrian Research 345, 105768.


PALEOCLIMATOLOGY/PALEOCEANOGRAPHY

Flowers, R.M., Macdonald, F.A., Siddoway, C.S., Havranek, R., 2020. Diachronous development of Great Unconformities before Neoproterozoic Snowball Earth. Proceedings of the National Academy of Sciences 117, 10172-10180.


Li, J., Hao, C., Wang, Z., Dong, L., Wang, Y., Huang, K.-J., Lang, X., Huang, T., Yuan, H., Zhou, C., Shen, B., 2020. Continental weathering intensity during the termination of the Marinoan Snowball Earth: Mg isotope evidence from the basal Doushantuo cap carbonate in South China. Palaeogeography, Palaeoclimatology, Palaeoecology 552, 109774.


Li, Z., Cao, M., Loyd, S.J., Algeo, T.J., Zhao, H., Wang, X., Zhao, L., Chen, Z.-Q., 2020. Transient and stepwise ocean oxygenation during the late Ediacaran Shuram Excursion: Insights from carbonate δ238U of northwestern Mexico. Precambrian Research 344, 105741.

Park, Y., Swanson-Hysell, N.L., MacLennan, S.A., Maloof, A.C., Gebreslassie, M., Tremblay, M.M., Schoene, B., Alene, M., Anttila, E.S.C., Tesema, T., Haileab, B., 2020. The lead-up to the Sturtian Snowball Earth: Neoproterozoic chemostratigraphy time-calibrated by the Tambien Group of Ethiopia. GSA Bulletin 132, 1119-1149.


Viehmann, S., Reitner, J., Tepe, N., Hohl, S.V., Van Kranendonk, M., Hofmann, T., Koeberl, C., Meister, P., 2020. Carbonates and cherts as archives of seawater chemistry and habitability on a carbonate platform 3.35 Ga ago: Insights from Sm/Nd dating and trace element analysis from the Strelley Pool Formation, Western Australia. Precambrian Research 344, 105742.

Warke, M.R., Strauss, H., Schröder, S., 2020. Positive cerium anomalies imply pre-GOE redox stratification and manganese oxidation in Paleoproterozoic shallow marine environments. Precambrian Research 344, 105767.

Xiong, J., Yang, J., 2020. Examining the role of varying surface pressure in the climate of early Earth. Climate of the Past Discussions 2020, 1-20.

Yu, W., Algeo, T.J., Zhou, Q., Du, Y., Wang, P., 2020. Cryogenian cap carbonate models: a review and critical assessment. Palaeogeography, Palaeoclimatology, Palaeoecology 552, 109727.

CRUSTAL EVOLUTION



Guo, M., Korenaga, J., 2020. Argon constraints on the early growth of felsic continental crust. Science Advances 6, eaaz6234.





Production/Engineering Geochemistry

Fong, S.Y., Montoya Sánchez, N., de Klerk, A., 2020. Olefin saturation using asphaltenes as a hydrogen source. Energy & Fuels 34, 4534-4543.


He, Q., Huang, Y., Ding, L., Guo, Q., Gong, Y., Yu, G., 2020. Effect of partial rapid pyrolysis on bituminous properties: From structure to reactivity. Energy & Fuels 34, 5476-5484.

Jia, T., Pan, L., Gong, S., Xie, J., Wang, X., Fang, Y., Zou, J.-J., Zhang, X., 2020. Mechanistic insights into the thermal deposition of highly thermal-stable jet fuel. Fuel 276, 118100.

Kang, S.S., Kang, J.W., 2020. Extraction of naphthenic acid from low-grade crude oil using diol compounds. Fuel 275, 117828.



Maagi, M.T., Lupyana, S.D., Jun, G., 2020. Nanotechnology in the petroleum industry: Focus on the use of nanosilica in oil-well cementing applications - A review. Journal of Petroleum Science and Engineering 193, 107397.

Ocubalidet, S., Carvajal-Ortiz, H., Gentzis, T., 2020. Post-well stimulation allocation of commingled production using geochemical fingerprinting techniques in unconventional reservoirs: A review of methods, and a case study of the Montney Formation, Western Canadian Sedimentary Basin. International Journal of Coal Geology 224, 103476.


Zhao, S., Pu, W., Varfolomeev, M.A., Liu, Y., Liu, Z., 2020. Oxidation characteristics of heavy oil and its SARA fractions during combustion using TG-FTIR. Journal of Petroleum Science and Engineering 192, 107331.

ASPHALTENES

Amiri, R., Khamehchi, E., Ghaffarzadeh, M., Kardani, N., 2020. Laboratory evaluation of a novel multifunctional chemical solution for asphaltene precipitation and aggregation problem: Comparison with an industrial chemical solution. Journal of Petroleum Science and Engineering 193, 107340.


Hernández, M.S., Silva, P.J., 2020. Electron paramagnetic resonance study of the fractions and trapped compounds in asphaltenes of Merey heavy crude oils and its vacuum residue. Energy & Fuels 34, 5641-5651.

Madeira, N.C.L., Rainha, K.P., Mendonça, J., Lacerda, V., Chinelatto, L.S., de Menezes, S.M.C., Porto, C.F.d.C., Pinto, F.E., Filgueiras, P.R., Romão, W., Neto, Á.C., 2020. Study of the influence of resins on the asphaltene aggregates by 1H DOSY NMR. Energy & Fuels 34, 5679-5688.

Medina, O.E., Gallego, J., Olmos, C.M., Chen, X., Cortés, F.B., Franco, C.A., 2020. Effect of multifunctional nanocatalysts on n-C7 asphaltene adsorption and subsequent oxidation under high-pressure conditions. Energy & Fuels 34, 6261-6278.

Mizuhara, J., Liang, Y., Masuda, Y., Kobayashi, K., Iwama, H., Yonebayashi, H., 2020. Evaluation of asphaltene adsorption free energy at the oil–water interface: Role of heteroatoms. Energy & Fuels 34, 5267-5280.

Mousavi, S.M.R., Jafari, S., Schaffie, M., Norouzi-Apourvari, S., 2020. Experimental study and modeling permeability damage in porous media due to asphaltene deposition. Journal of Petroleum Science and Engineering 193, 107396.

Oñate-Gutiérrez, J.A., Ramírez-Pradilla, J.S., Pinzón, J.R., Combariza, M.Y., Blanco-Tirado, C., 2020. Asphaltene structure modifiers as a novel approach for viscosity reduction in heavy crude oils. Energy & Fuels 34, 5251-5257.

Ramos-Pallares, F., Yarranton, H.W., 2020. Extending the modified regular solution model to predict component partitioning to the asphaltene-rich phase. Energy & Fuels 34, 5213-5230.

Rytting, B.M., Harper, M.R., Edmond, K.V., Merchant, S., Zhang, Y., Kilpatrick, P.K., 2020. Interfacial phenomena of purified petroporphyrins and their impact on asphaltene interfacial film formation. Energy & Fuels 34, 5444-5456.

Simon, S., Gao, B., Tofte, S., Sjöblom, J., Passade-Boupat, N., Palermo, T., Rondon-Gonzalez, M., 2020. Influence of asphaltenes on gelation of tetrameric acid with calcium ion at the oil/water interface under flow-model condition. Energy & Fuels 34, 5846-5855.

Taheri-Shakib, J., Zojaji, I., Saadati, N., Kazemzadeh, E., Esfandiarian, A., Rajabi-Kochi, M., 2020. Investigating molecular interaction between wax and asphaltene: Accounting for wax appearance temperature and crystallization. Journal of Petroleum Science and Engineering 191, 107278.


Yan, Y., de Klerk, A., Prado, G.H.C., 2020. Visbreaking of vacuum residue deasphalted oil: New asphaltenes formation. Energy & Fuels 34, 5135-5147.






Zeng, Y., Shen, Z., Takahama, S., Zhang, L., Zhang, T., Lei, Y., Zhang, Q., Xu, H., Ning, Y., Huang, Y., Cao, J., Rudolf, H., 2020. Molecular absorption and evolution mechanisms of PM2.5 brown carbon revealed by electrospray ionization Fourier transform–ion cyclotron

resonance mass spectrometry during a severe winter pollution episode in Xi'an, China. Geophysical Research Letters 47, e2020GL087977.

INTERFACES/EOR

Acosta, M., Reyes, L., Cruz, J.C., Pradilla, D., 2020. Demulsification of Colombian heavy crude oil (W/O) emulsions: insights into the instability mechanisms, chemical structure, and performance of different commercial demulsifiers. Energy & Fuels 34, 5665-5678.

Ansah, E.O., Vo Thanh, H., Sugai, Y., Nguele, R., Sasaki, K., 2020. Microbe-induced fluid viscosity variation: field-scale simulation, sensitivity and geological uncertainty. Journal of Petroleum Exploration and Production Technology 10, 1983-2003.

Dong, X., Shen, L.W., Liu, X., Zhang, P., Sun, Y., Yan, W., Jiang, L., Wang, F., Sun, J., 2020. NMR characterization of a tight sand's pore structures and fluid mobility: An experimental investigation for CO2 EOR potential. Marine and Petroleum Geology 118, 104460.

Hawthorne, S.B., Miller, D.J., Grabanski, C.B., Jin, L., 2020. Experimental determinations of minimum miscibility pressures using hydrocarbon gases and CO2 for crude oils from the Bakken and cut bank oil reservoirs. Energy & Fuels 34, 6148-6157.

Huang, X., Xue, J., Li, X., 2020. Adsorption behavior of CH4 and C2H6 on shale under the influence of CO2 and flue gas. Energy & Fuels 34, 5689-5695.

Jagadisan, A., Heidari, Z., 2020. Impact of geochemical properties on wettability of kerogen and organic-rich mudrocks. SPE-199356-PA 23, 758-771.

Li, S., Jackson, M.D., Agenet, N., 2020. Role of the calcite-water interface in wettability alteration during low salinity waterflooding. Fuel 276, 118097.



Morishita, R., Matsuyama, R., Ishiwata, T., Tsuchiya, Y., Giang, P.T., Takahashi, S., 2020. Oil and water interactions during low-salinity enhanced oil recovery in water-wet porous media. Energy & Fuels 34, 5258-5266.

Niu, J., Liu, Q., Lv, J., Peng, B., 2020. Review on microbial enhanced oil recovery: Mechanisms, modeling and field trials. Journal of Petroleum Science and Engineering 192, 107350.

Pal, N., Mandal, A., 2020. Oil recovery mechanisms of Pickering nanoemulsions stabilized by surfactant-polymer-nanoparticle assemblies: A versatile surface energies’ approach. Fuel 276, 118138.

Pan, B., Li, Y., Zhang, M., Wang, X., Iglauer, S., 2020. Effect of total organic carbon (TOC) content on shale wettability at high pressure and high temperature conditions. Journal of Petroleum Science and Engineering 193, 107374.

Rao, A., Kumar, S., Annink, C., Le-Anh, D., Ayirala, S.C., Alotaibi, M.B., Siretanu, I., Duits, M.H.G., Yousef, A.A., Mugele, F., 2020. Mineral interfaces and oil recovery: A microscopic view on surface reconstruction, organic modification, and wettability alteration of carbonates. Energy & Fuels 34, 5611-5622.



Song, Z., Song, Y., Li, Y., Bai, B., Song, K., Hou, J., 2020. A critical review of CO2 enhanced oil recovery in tight oil reservoirs of North America and China. Fuel 276, 118006.

Wang, J., Jaeger, P., Samara, H., Ryan, D., 2020. Simultaneous evaluation of time-dependent phase and wetting properties of hydrocarbon liquids for CO2-enhanced recovery of oil and gas from tight reservoirs. Energy & Fuels 34, 5128-5134.

Yang, Y., Cheng, T., Wu, H., You, Z., Shang, D., Hou, J., 2020. Enhanced oil recovery using oleic acid-modified titania nanofluids: Underlying mechanisms and oil-displacement performance. Energy & Fuels 34, 5813-5822.

Zhang, Y., Zhao, P., Cai, M., Lu, F., Wu, X., Guo, Z., 2020. Occurrence state and forming mechanism of microscopic remaining oil controlled by dynamic and static factors. Journal of Petroleum Science and Engineering 193, 107330.

HEAVY OIL PRODUCTION

Ado, M.R., 2020. Effect of reservoir pay thickness on the performance of the THAI heavy oil and bitumen upgrading and production process. Journal of Petroleum Exploration and Production Technology 10, 2005-2018.

Liu, H., Wang, Y., Xiong, H., Wu, K., 2020. Semianalytical analysis of chamber growth and energy efficiency of solvent-assisted steam-gravity drainage considering the effect of reservoir heterogeneity along the horizontal well. Energy & Fuels 34, 5777-5787.

Martinez, J.F., Schoeggl, F.F., Maini, B.B., Yarranton, H.W., 2020. Investigation of mechanisms for gravity drainage of heavy oil and solvent mixtures in a Hele-Shaw cell. Energy & Fuels 34, 5823-5837.

Santa, M.L.S., Sabet, N., Hassanzadeh, H., 2020. Propane-aided leaching of bitumen from oilsands. Energy & Fuels 34, 5798-5803.

Zhang, J., Han, F., Yang, Z., Zhang, L., Wang, X., Zhang, X., Jiang, Y., Chen, K., Pan, H., Lin, R., 2020. Significance of aquathermolysis reaction on heavy oil recovery during the steam-assisted gravity drainage process. Energy & Fuels 34, 5426-5435.

NOVEL MATERIALS

Guo, J., Li, X., Xu, H., Zhu, H., Li, B., Westwood, A., 2020. Molecular structure control in mesophase pitch via co-carbonization of coal tar pitch and petroleum pitch for production of carbon fibers with both high mechanical properties and thermal conductivity. Energy & Fuels 34, 6474-6482.

Soltani Hosseini, M., Chartrand, P., 2020. Thermodynamics and phase relationship of carbonaceous mesophase appearing during coal tar pitch carbonization. Fuel 275, 117899.

Recent Sediments

Blattmann, T.M., Ishikawa, N.F., 2020. Theoretical amino acid-specific radiocarbon content in the environment: Hypotheses to be tested and opportunities to be taken. Frontiers in Marine Science 7, 302. doi: 310.3389/fmars.2020.00302.

Ciglenečki, I., Čanković, M., Kuzmić, M., Pagano, M., 2020. Accumulation of organic matter in a mesotidal Mediterranean lagoon (Boughrara, Tunisia). Estuarine, Coastal and Shelf Science 240, 106780.

Grin’ko, A.A., Goncharov, I.V., Shakhova, N.E., Gustafsson, Ö., Oblasov, N.V., Romankevich, E.A., Zarubin, A.G., Kashapov, R.S., Gershelis, E.V., Dudarev, O.V., Mazurov, A.K., Semiletov, I.P., Chernykh, D.V., 2020. Organic matter of sediments in areas of intense methane release in the Laptev Sea: Molecular-composition specifics. Russian Geology and Geophysics 61, DOI: 10.15372/RGG2019150.

Kaiser, J., Wasmund, N., Kahru, M., Wittenborn, A.K., Hansen, R., Häusler, K., Moros, M., Schulz-Bull, D., Arz, H.W., 2020. Reconstructing N2-fixing cyanobacterial blooms in the Baltic Sea beyond observations using 6- and 7-methylheptadecane in sediments as specific biomarkers. Biogeosciences 17, 2579-2591.

Kitahashi, T., Sugime, S., Inomata, K., Nishijima, M., Kato, S., Yamamoto, H., 2020. Meiofaunal diversity at a seamount in the Pacific Ocean: A comprehensive study using environmental DNA and RNA. Deep Sea Research Part I: Oceanographic Research Papers 160, 103253.



Nakakuni, M., Takehara, K., Swart, P.K., Yamamoto, S., 2020. The contribution of prokaryotes and terrestrial plants to Maldives inter-atoll sapropels: Evidence from organic biomarkers. Organic Geochemistry 145, 104039.

Nemirovskaya, I.A., Kochenkova, A.I., Khramtsova, A.V., 2020. Hydrocarbons at the geochemical barrier the northern Dvina–the White Sea. Water Resources 47, 438-447.


Petrova, V.I., Batova, G.I., Kursheva, A.V., Litvinenko, I.V., Morgunova, I.P., 2020. Hydrocarbon molecular markers as indicators of the Late Cenozoic sedimentation on the Amerasian continental margin (Arctic Ocean). Russian Geology and Geophysics 61, DOI: 10.15372/RGG2019084.

Pu, Y., Werne, J.P., Meyers, P.A., Zhang, H., 2020. Organic matter geochemical signatures of sediments of Lake Ngoring (Qinghai-Tibetan Plateau): A record of environmental and climatic changes in the source area of the Yellow River for the last 1500 years. Palaeogeography, Palaeoclimatology, Palaeoecology 551, 109729.

Vaughn, D.R., Bianchi, T.S., Shields, M.R., Kenney, W.F., Osborne, T.Z., 2020. Increased organic carbon burial in northern Florida mangrove-salt marsh transition zones. Global Biogeochemical Cycles 34, e2019GB006334.

Zhu, Z.-Y., Oakes, J., Eyre, B., Hao, Y., Sia, E.S.A., Jiang, S., Müller, M., Zhang, J., 2020. The nonconservative distribution pattern of organic matter in the Rajang, a tropical river with peatland in its estuary. Biogeosciences 17, 2473-2485.

ATMOSPHERIC GEOCHEMISTRY


Harrison, A.W., Waterson, A.M., De Bruyn, W.J., 2020. Spectroscopic and photochemical properties of secondary brown carbon from aqueous reactions of methylglyoxal. ACS Earth and Space Chemistry 4, 762-773.

Link, M.F., Nguyen, T.B., Bates, K.H., Müller, J.-F., Farmer, D.K., 2020. Can isoprene oxidation explain high concentrations of atmospheric formic and acetic acid over forests? ACS Earth and Space Chemistry 4, 730-740.




Xu, R., Alam, M.S., Stark, C., Harrison, R.M., 2020. Composition and emission factors of traffic- emitted intermediate volatility and semi-volatile hydrocarbons (C10–C36) at a street canyon and urban background sites in central London, UK. Atmospheric Environment 231, 117448.

Xu, X., Lu, X., Li, X., Liu, Y., Wang, X., Chen, H., Chen, J., Yang, X., Fu, T.-M., Zhao, Q., Fu, Q., 2020. ROS-generation potential of humic-like substances (HULIS) in ambient PM2.5 in urban Shanghai: Association with HULIS concentration and light absorbance. Chemosphere 256, 127050.

HYDROSPHERE GEOCHEMISTRY

Brailsford, F.L., Glanville, H.C., Wang, D., Golyshin, P.N., Johnes, P.J., Yates, C.A., Jones, D.L., 2020. Rapid depletion of dissolved organic sulphur (DOS) in freshwaters. Biogeochemistry 149, 105-113.


Clark, J.B., Long, W., Hood, R.R., 2020. A comprehensive estuarine dissolved organic carbon budget using an enhanced biogeochemical model. Journal of Geophysical Research: Biogeosciences 125, e2019JG005442.

Costalago, D., Forster, I., Nemcek, N., Neville, C., Perry, R.I., Young, K., Hunt, B.P.V., 2020. Seasonal and spatial dynamics of the planktonic trophic biomarkers in the Strait of Georgia (northeast Pacific) and implications for fish. Scientific Reports 10, 8517.


Juhls, B., Stedmon, C.A., Morgenstern, A., Meyer, H., Hölemann, J., Heim, B., Povazhnyi, V., Overduin, P.P., 2020. Identifying drivers of seasonality in Lena River biogeochemistry and dissolved organic matter fluxes. Frontiers in Environmental Science 8, 53. doi: 10.3389/fenvs.2020.00053.

Kellerman, A.M., Hawkings, J.R., Wadham, J.L., Kohler, T.J., Stibal, M., Grater, E., Marshall, M., Hatton, J.E., Beaton, A., Spencer, R.G.M., 2020. Glacier outflow dissolved organic matter as a window into seasonally changing carbon sources: Leverett Glacier, Greenland. Journal of Geophysical Research: Biogeosciences 125, e2019JG005161.

Landsman-Gerjoi, M., Perdrial, J.N., Lancellotti, B., Seybold, E., Schroth, A.W., Adair, C., Wymore, A., 2020. Measuring the influence of environmental conditions on dissolved organic matter biodegradability and optical properties: a combined field and laboratory study. Biogeochemistry 149, 37-52.

Liénart, C., Savoye, N., Conan, P., David, V., Barbier, P., Bichon, S., Charlier, K., Costes, L., Derriennic, H., Ferreira, S., Gueux, A., Hubas, C., Maria, E., Meziane, T., 2020. Relationship between bacterial compartment and particulate organic matter (POM) in coastal systems: An assessment using fatty acids and stable isotopes. Estuarine, Coastal and Shelf Science 239, 106720.

Lodeiro, P., Rey-Castro, C., David, C., Achterberg, E.P., Puy, J., Gledhill, M., 2020. Acid-base properties of dissolved organic matter extracted from the marine environment. Science of The Total Environment 729, 138437.


Morana, M., Bouillon, S., Nolla-Ardèvol, V., Roland, F.A.E., Okello, W., Descy, J.-P., Nankabirwa, A., Nabafu, E., Springael, D., Borges, A.V., 2020. Methane paradox in tropical lakes? Sedimentary fluxes rather than water column production in oxic waters sustain methanotrophy and emissions to the atmosphere. Biogeosciences Discussions 2020, 1-20.


Saito, M.A., McIlvin, M.R., Moran, D.M., Santoro, A.E., Dupont, C.L., Rafter, P.A., Saunders, J.K., Kaul, D., Lamborg, C.H., Westley, M., Valois, F., Waterbury, J.B., 2020. Abundant nitrite-oxidizing metalloenzymes in the mesopelagic zone of the tropical Pacific Ocean. Nature Geoscience 13, 355-362.





Wohl, C., Brown, I., Kitidis, V., Jones, A.E., Sturges, W.T., Nightingale, P.D., Yang, M., 2020. Underway seawater and atmospheric measurements of volatile organic compounds in the Southern Ocean. Biogeosciences 17, 2593-2619.


Zhang, Q., Luo, S., Zhao, L., Zhang, P., Wang, S., Sun, C., Zhang, L., 2020. Effect of Darcy flux on the release of dissolved organic matter and nitrogen from coal gangue in a coal mine underground reservoir: Column experiments. Chemical Geology 545, 119652.

Zhang, Y., Yang, T., Hohl, S.V., Zhu, B., He, T., Pan, W., Chen, Y., Yao, X., Jiang, S., 2020. Seawater carbon and strontium isotope variations through the late Ediacaran to late Cambrian in the Tarim Basin. Precambrian Research 345, 105769.

SOIL GEOCHEMISTRY

Chen, C., Hall, S.J., Coward, E., Thompson, A., 2020. Iron-mediated organic matter decomposition in humid soils can counteract protection. Nature Communications 11, 2255.


Le Mer, G., Barthod, J., Dignac, M.-F., Barré, P., Baudin, F., Rumpel, C., 2020. Inferring the impact of earthworms on the stability of organo-mineral associations, by Rock-Eval thermal analysis and 13C NMR spectroscopy. Organic Geochemistry 144, 104016.

Leifeld, J., Klein, K., Wüst-Galley, C., 2020. Soil organic matter stoichiometry as indicator for peatland degradation. Scientific Reports 10, 7634.

Pallud, C., Rhoades, C.C., Schneider, L., Dwivedi, P., Borch, T., 2020. Temperature-induced iron (III) reduction results in decreased dissolved organic carbon export in subalpine wetland soils, Colorado, USA. Geochimica et Cosmochimica Acta 280, 148-160.

Servais, S., Kominoski, J.S., Coronado-Molina, C., Bauman, L., Davis, S.E., Gaiser, E.E., Kelly, S., Madden, C., Mazzei, V., Rudnik, D., Santamaria, F., Sklar, F.H., Stachelek, J., Troxler, T.G., Wilson, B.J., 2020. Effects of saltwater pulses on soil microbial enzymes and organic matter breakdown in freshwater and brackish coastal wetlands. Estuaries and Coasts 43, 814-830.

Zhang, D., Wu, J., Yang, F., Chen, Q., Feng, J., Li, Q., Zhang, Q., Wang, W., Cheng, X., 2020. Linkages between soil organic carbon fractions and carbon-hydrolyzing enzyme activities across riparian zones in the Three Gorges of China. Scientific Reports 10, 8433.


Remote Sensing-Hydrocarbon Seepage

Asadzadeh, S., de Souza Filho, C.R., 2020. Characterization of microseepage-induced diagenetic changes in the Upper-Red Formation, Qom region, Iran. Part I: Outcrop, geochemical, and remote sensing studies. Marine and Petroleum Geology 117, 104149.

Asadzadeh, S., Souza Filho, C.R., 2020. Characterization of microseepage-induced diagenetic changes in the Upper-Red Formation, Qom region, Iran. Part II: A new insight using reflectance spectroscopic analysis. Marine and Petroleum Geology 117, 104387.

Åström, E.K.L., Sen, A., Carroll, M.L., Carroll, J., 2020. Cold seeps in a warming Arctic: Insights for benthic ecology. Frontiers in Marine Science 7, 244. doi: 210.3389/fmars.2020.00244.

Chakraborty, A., Ruff, S.E., Dong, X., Ellefson, E.D., Li, C., Brooks, J.M., McBee, J., Bernard, B.B., Hubert, C.R.J., 2020. Hydrocarbon seepage in the deep seabed links subsurface and seafloor biospheres. Proceedings of the National Academy of Sciences 117, 11029-11037.

Ciotoli, G., Procesi, M., Etiope, G., Fracassi, U., Ventura, G., 2020. Influence of tectonics on global scale distribution of geological methane emissions. Nature Communications 11, 2305.





Palladino, G., Rizzo, R.E., Zvirtes, G., Grippa, A., Philipp, R.P., Healy, D., Alsop, G.I., 2020. Multiple episodes of sand injection leading to accumulation and leakage of hydrocarbons along the San Andreas/San Gregorio fault system, California. Marine and Petroleum Geology 118, 104431.


Wang, Y., Cao, J., Jin, J., Zhang, J., Hu, G., Zhou, N., Shi, T., 2020. Diverse oil and gas seeps in the southern Junggar Basin, NW China (piedmont Northern Tian Shan): Origins and links to tectono-sedimentary evolution. Geological Journal 55, 3497-3521.


Unconventional Resources

Cao, Y., Han, H., Guo, C., Pang, P., Ding, Z.-g., Gao, Y., 2020. Influence of extractable organic matters on pore structure and its evolution of Chang 7 member shales in the Ordos Basin, China: Implications from extractions using various solvents. Journal of Natural Gas Science and Engineering 79, 103370.

Chen, J., Pang, X., Wang, X., Wang, Y., 2020. A new method for assessing tight oil, with application to the Lucaogou Formation in the Jimusaer depression, Junggar Basin, China. American Association of Petroleum Geologists Bulletin 104, 1199-1229.



Gao, Y., Wen, Z., Xu, Y., Song, H., Li, W., Yu, Y., Ke, C., 2020. Geochemical characteristics of the Chang7 organic-rich fine-grained sedimentary rocks and its relationship with the tight oil in Longdong area, Northwest China. Journal of Petroleum Exploration and Production Technology 10, 1803-1816.


He, Z., Nie, H., Hu, D., Jiang, T., Wang, R., Zhang, Y., Zhang, G., Lu, Z., 2020. Geological problems in the effective development of deep shale gas: a case study of Upper Ordovician Wufeng-Lower Silurian Longmaxi formations in Sichuan Basin and its periphery. Acta Petrolei Sinica 41, 379-391.

He, Z., Nie, H., Li, S., Luo, J., Wang, H., Zhang, G., 2020. Differential enrichment of shale gas in upper Ordovician and lower Silurian controlled by the plate tectonics of the Middle-Upper Yangtze, south China. Marine and Petroleum Geology 118, 104357.



Liu, Z., Guo, S., Lv, R., 2020. Shale-gas play risk of the lower Cambrian on the Yangtze platform, South China. American Association of Petroleum Geologists Bulletin 104, 989-1009.

Memon, A., Li, A., Jacqueline, N., Kashif, M., Ma, M., 2020. Study of gas sorption, stress effects and analysis of effective porosity and permeability for shale gas reservoirs. Journal of Petroleum Science and Engineering 193, 107370.


Pang, Z., Tao, S., Zhang, Q., Zhang, B., Zhang, T., Yang, X., Wu, Y., Fan, J., Yuan, M., 2020. Evaluation methods of profitable tight oil reservoir of lacustrine coquina: A case study of Da'anzhai Member of Jurassic in the Sichuan Basin. Acta Geologica Sinica - English Edition 94, 418-429.

Qiao, J., Littke, R., Zieger, L., Jiang, Z., Fink, R., 2020. Controls on gas storage characteristics of Upper Paleozoic shales from the southeastern Ordos Basin. Marine and Petroleum Geology 117, 104377.

Sowiżdżał, K., Słoczyński, T., Kaczmarczyk, W., 2020. Estimation of the oil-in-place resources in the liquid-rich shale formations exploiting geochemical and petrophysical data in a 3D high-resolution geological model domain: Baltic basin case study. Geofluids 2020, 5385932.

Tian, H., Wang, M., Liu, S., Zhang, S., Zou, C., 2020. Influence of pore water on the gas storage of organic-rich shale. Energy & Fuels 34, 5293-5306.

Wan, X., Rasouli, V., Damjanac, B., Yu, W., Xie, H., Li, N., Rabiei, M., Miao, J., Liu, M., 2020. Coupling of fracture model with reservoir simulation to simulate shale gas production with complex fractures and nanopores. Journal of Petroleum Science and Engineering 193, 107422.

Xu, J., Huang, Q., 2020. Geological characteristics of shale in the Silurian (Sichuan) basin and chemical reaction of its reservoir under the action of fracturing fluid. Journal of Petroleum Exploration and Production Technology 10, 1775-1782.

Yang, R., Jia, A., He, S., Hu, Q., Dong, T., Hou, Y., Yan, J., 2020. Water adsorption characteristics of organic-rich Wufeng and Longmaxi Shales, Sichuan Basin (China). Journal of Petroleum Science and Engineering 193, 107387.

Zeng, T., Kim, K.T., Werth, C.J., Katz, L.E., Mohanty, K.K., 2020. Surfactant adsorption on shale samples: Experiments and an additive model. Energy & Fuels 34, 5436-5443.


Zhao, D., Guo, Y., Wang, G., Li, G., Zeng, C., Jiao, W., 2020. Sequence stratigraphic framework and its influence on the development characteristics of shale reservoirs: Taking the Longmaxi Formation shale in the Sichuan Basin as an example. Acta Sedimentologica Sinica 38, 379-397.

Zhou, Y., Ni, H., Shen, Z., Wang, M., 2020. Study on proppant transport in fractures of supercritical carbon dioxide fracturing. Energy & Fuels 34, 6186-6196.

COAL-BED METHANE


Duan, L., Qu, L., Xia, Z., Liu, L., Wang, J., 2020. Stochastic modeling for estimating coalbed methane resources. Energy & Fuels 34, 5196-5204.

Enriquez, D.A., Zhang, T., Sun, X., Meng, D., Zhang, Y., 2020. Methane resaturation in Barnett Formation core plugs and new approach for determination of post-coring gas loss. Marine and Petroleum Geology 118, 104430.

Guo, C., Qin, Y., Ma, D., Xia, Y., Bao, Y., Chen, Y., Lu, L., 2020. Pore structure and permeability characterization of high-rank coal reservoirs: A case of the Bide-Santang Basin, western Guizhou, South China. Acta Geologica Sinica - English Edition 94, 243-252.


Qu, Y., Shan, X., Du, T., Du, X., Zhao, R., 2020. Molecular organic geochemical characteristics and coal gas potential evaluation of Mesozoic coal seams in the western Great Khingan Mountains. Acta Geologica Sinica - English Edition 94, 409-417.

Tao, C., Wang, Y., Li, Y., Ni, X., Gao, X., 2020. Adsorption mechanism and kinetic characterization of bituminous coal under high temperatures and pressures in the Linxing-Shenfu area. Acta Geologica Sinica - English Edition 94, 399-408.

Wang, G., Qin, Y., Xie, Y., Wang, Z., Wang, B., Wang, Q., Zhang, X., 2020. Cyclic characteristics of the physical properties of key strata in CBM systems controlled by sequence stratigraphy—an example from the Gujiao Block. Acta Geologica Sinica - English Edition 94, 444-455.

Yuan, Y., Shan, Y., Tang, Y., Cao, D., 2020. Coalbed methane enrichment regularity and major control factors in the Xishanyao Formation in the western part of the southern Junggar Basin. Acta Geologica Sinica - English Edition 94, 485-500.


FLUID TRANSPORT/RECOVERY

Arunachalam, K., Fan, X., 2020. Impact of heat of sorption on thermal enhanced recovery of sorbed gas from gas shale reservoirs – An experimental and simulation study. Journal of Natural Gas Science and Engineering 79, 103318.

Burrows, L.C., Haeri, F., Cvetic, P., Sanguinito, S., Shi, F., Tapriyal, D., Goodman, A., Enick, R.M., 2020. A literature review of CO2, natural gas, and water-based fluids for enhanced oil recovery in unconventional reservoirs. Energy & Fuels 34, 5331-5380.


Fan, K., Sun, R., Elsworth, D., Dong, M., Li, Y., Yin, C., Li, Y., Chen, Z., Wang, C., 2020. Radial permeability measurements for shale using variable pressure gradients. Acta Geologica Sinica - English Edition 94, 269-279.


Hou, L., Elsworth, D., Geng, X., 2020. Swelling and embedment induced by sub- and super-critical-CO2 on the permeability of propped fractures in shale. International Journal of Coal Geology 225, 103496.

Li, Q., Jew, A.D., Brown, G.E., Bargar, J.R., Maher, K., 2020. Reactive transport modeling of shale–fluid interactions after imbibition of fracturing fluids. Energy & Fuels 34, 5511-5523.

Ning, C., Ma, Z., Jiang, Z., Su, S., Li, T., Zheng, L., Wang, G., Li, F., 2020. Effect of shale reservoir characteristics on shale oil movability in the Lower Third Member of the Shahejie Formation, Zhanhua sag. Acta Geologica Sinica - English Edition 94, 352-363.

POROSITY

Blach, T., Radlinski, A.P., Edwards, D.S., Boreham, C.J., Gilbert, E.P., 2020. Pore anisotropy in unconventional hydrocarbon source rocks: A small-angle neutron scattering (SANS) study on the Arthur Creek Formation, Georgina Basin, Australia. International Journal of Coal Geology 225, 103495.


Kireeva, T.A., Bychkov, A.Y., Zubkov, M.Y., 2020. The specific features of the microcomponent composition of pore solutions in the rocks of the Bazhenov Formation, Western Siberia. Moscow University Geology Bulletin 75, 47-57.


Liu, H., Liu, S., Luo, X., Sun, Y., Tian, J., Liang, L., Liu, X., 2020. Study of fractal characteristics of the cementation index in shale gas. Acta Geologica Sinica - English Edition 94, 456-466.

Sobecki, N., Wang, S., Ding, D.Y., Nieto-Draghi, C., Wu, Y.-S., 2020. A multi-scale modeling of confined fluid: From nanopore to unconventional reservoir simulation. Journal of Petroleum Science and Engineering 193, 107364.


Tian, H., Zou, C., Liu, S., Hong, F., Fan, J., Gui, L., Hao, J., 2020. Reservoir porosity measurement uncertainty and its influence on shale gas resource assessment. Acta Geologica Sinica - English Edition 94, 233-242.




Abstracts

Acosta, M., Reyes, L., Cruz, J.C., Pradilla, D., 2020. Demulsification of Colombian heavy crude oil (W/O) emulsions: insights into the instability mechanisms, chemical structure, and performance of different commercial demulsifiers. Energy & Fuels 34, 5665-5678.

https://doi.org/10.1021/acs.energyfuels.0c00313

Chemical products such as PEO/PPO block copolymers or alkoxylated resins tend to work well in chemical demulsification of light hydrocarbons (°API > 20) but fail to do so in the presence of heavy and extra heavy crude emulsions. Moreover, a large knowledge gap between the relationship of instability mechanisms at the liquid-liquid interface and the tendency of demulsifier systems to promote phase separation, has limited the ability of practitioners in field operations to properly select a system for a particular application. To address this issue, here, an enhanced quantitative protocol is put forward to assess the chemical demulsification of heavy crude oil (HCO) emulsions by coupling transmission/backscattering measurements to traditional bottle tests. The applicability of the method was evaluated by adding a wide variety of commercially available demulsifiers to HCO emulsions from a Colombian oilfield. The collected data on interfacial tension and average droplet size showed that for the complex case of HCO emulsions, interfacial activity and fast kinetics are not sufficient criteria for phase separation. The best performing chemicals (separated water ~85%) exhibited a low reduction of the interfacial tension at equilibrium (IFT ~ 20 mN/m). This evidence strongly suggests that separation might be likely triggered after the intermingling of the demulsifier

with the oil phase such that the density difference between phases is considerably increased (~5% change on average). Furthermore, HPLC-MS results showed that spatial and chemical configuration, as well as steric effects, drive the performance of demulsifiers and must be carefully considered for new developments.

Adams, F., Adriaens, M., 2020. The metamorphosis of analytical chemistry. Analytical and Bioanalytical Chemistry 412, 3525-3537.

https://doi.org/10.1007/s00216-019-02313-z

Defining analytical chemistry as the measurement of isolated compositional features in a selected study object ignores the unique perspective that analytical chemists bring to twenty-first century science and society. In this feature article, we will discuss some of the existing preconceptions and misinterpretations of analytical chemistry that occur at present and will tackle them from the more up-to-date perspective of science in the Big Data Era. This will place their influence in context while simultaneously enlarging the scope of the discipline analytical chemistry to its well-deserved prevalent position in present-day science and technology.

Adegoke, A.K., Hakimi, M.H., Abdullah, W.H., Ibrahim, E.-K., Sarki Yandoka, B.M., Al Faifi, H., Lashin, A., 2020. Geochemistry and oil-gas generation modeling of the Late Cretaceous shales from the Chad (Bornu) Basin, Northeast Nigeria. Journal of Natural Gas Science and Engineering 79, 103341.

http://www.sciencedirect.com/science/article/pii/S1875510020301955

Late Cretaceous Fika Formation shale was collected and analyzed from six wells in northeastern Nigeria's Chad (Bornu) Basin. The characteristics and the oil and gas-generating potential of the source are discussed based on combined geochemistry investigations and basin models. The abundance of marine phytoplanktonic-bacteria and land-plant suggested by biological markers indicate that the kerogen in the Fika shale Formation is a mixture of Types II and III, which is not compatible with the current low Rock-Eval HI findings of less than 200 mg HC/g TOC. The chemical and optical maturity parameters suggest that the Fika shales throughout the studied wells are in the early maturity stage of the oil window near the gas window point. Therefore, thermal maturation is the critical factor that significantly reduces the original HI values and modifies Types II and III to produce oil and gas.

Based on the kinetic database models for Types II and III kerogen mixtures, the initial conversion of kerogen to oil has been occurring since the Late Cretaceous in the Kanadi-1 and Tuma-1 wells and since the Eocene in the Kinasar-1, Kuchalli-1, and Faltu-1 wells with transformation ratios (TR) between 10–31% and 10–50%, respectively. Furthermore, the oil was expelled from the Fika shale source rock in the Kanadi-1 and Tuma-1 wells at the end of Late Cretaceous, with TRs of 65–70%. From that period up to the present, the retained oil was cracked into wet gas in the gas window of 1.10–1.30 Easy %Ro with peak TR ratios greater than 65%.

The distributions of thermal maturation, conversion ratio, and thickness suggest that the Fika source rock could generate substantial amounts of oil and gas in the southwest part of the basin. Therefore, the southwest part of the Chad (Bornu) Basin is considered a frontier exploration target.

Ado, M.R., 2020. Effect of reservoir pay thickness on the performance of the THAI heavy oil and bitumen upgrading and production process. Journal of Petroleum Exploration and Production Technology 10, 2005-2018.

https://doi.org/10.1007/s13202-020-00840-5

The increasing energy demand has to be met while we transitioned to a decarbonized energy future. Heavy oil and bitumen reserves are urgently needed to be developed to ensure that a smooth transition is provided. In this work, field-scale kinetics parameters are used to study the effect of reservoir pay thickness on the performance of toe-to-heel air injection (THAI) process. Air was injected at constant rate into three different models with the thicknesses of 24 m, 16 m, and 8 m, respectively. The oil produced is slightly affected by the reservoir thickness. It is found that the lower the reservoir thickness, the larger the cumulative air-to-oil ratio (cAOR), indicating that heat loss increases with the decrease in the reservoir thickness. This trend is similar to steam-based processes. At constant air injection flux, it is found that both the cumulative oil produced and the cAOR decrease with the decrease in the reservoir thicknesses. This decrease is attributed to the decrease in the rate of heat generation in the thinner reservoirs, which in turn results in lower combustion zone temperature and thus lower temperature gradients between the reservoir and the overburden and the reservoir and the underburden. Consequently, a more general conclusion is that decreasing the air injection rate by the same factor the reservoir thickness is decreased (i.e. keeping the air injection flux constant) results in a more economical THAI process operation compared to when the air injection rate is kept constant (i.e. allowing increase in air injection flux).

Afshar-Mohajer, N., Lam, A., Dora, L., Katz, J., Rule, A.M., Koehler, K., 2020. Impact of dispersant on crude oil content of airborne fine particulate matter emitted from seawater after an oil spill. Chemosphere 256, 127063.

http://www.sciencedirect.com/science/article/pii/S004565352031256X

Inhalation of PM2.5, particles with an aerodynamic diameter <2.5 μm, from sea spray after crude oil spills could present serious health concerns. The addition of dispersants to effectively spread the crude oil throughout the water column has been practiced in recent years. Here, we investigated the possibility of an increase in the toxic content of fine PM after adding dispersant. A laboratory setup consisted of a vertical tank filled with seawater, 31.5 L airspace for aerosol sampling, and a bubble generating nozzle that aerosolized the oily droplets. Four different cases were studied: no slick, 0.5-mm-thick slick of pure crude oil (MC252 surrogate), dispersant (Corexit 9500A) mixed with crude oil at dispersant to oil ratio (DOR) 1:25, and DOR 1:100. The resulting airborne droplets were sampled for gravimetric and chemical analyses through development of a gas chromatography and mass spectrometry technique. Also, PM2.5 particles were size-fractioned into 13 size bins covering <60 nm to 12.1 μm using a low-pressure cascade impactor.

The highest PM2.5 concentration (20.83 ± 5.21 μg/m3) was released from a slick of DOR 1:25, 8.83× greater than the case with pure crude oil. The average ratio of crude oil content from the slick of DOR 1:25 to the case with pure crude oil was 2.37 (1.83 vs 0.77 μg/m3) that decreased to 1.17 (0.90 vs 0.77 μg/m3) at DOR 1:100. For particles <220 nm, the resultant crude oil concentrations were 0.64 and 0.29 μg/m3 at DOR 1:25 and 1:100, both higher than 0.11 μg/m3 from the slick of pure crude oil.


https://doi.org/10.1021/acs.energyfuels.9b03990

The complexity of petroleum crude oils necessitates a combination of analytical techniques to gain the in-depth compositional knowledge needed to enhance oil production or develop optimal refining strategies. This study focuses on the fractionation of four Arabian crude oils through gel permeation chromatography (GPC) to obtain chemically well-defined fractions, which are then characterized in detail using atmospheric pressure photoionization Fourier transform-ion cyclotron resonance mass spectrometry, and field desorption time-of-flight mass spectrometry. GPC is found to be a valuable tool because the described methodology produces petroleum fractions with nonpolar components reproducibly separated by total alkyl chain length. While the early-eluting fractions contained large saturated compounds and small aromatic systems with extensive alkyl chains, as well as potential asphaltene material, the later-eluting GPC fractions contained molecules with a wide range of aromatic rings but very limited alkyl chains. The molecular size contribution of aromatic rings did not change the elution time of the studied petroleum components as it appears counterbalanced by non-size effects. Preliminary tandem mass spectrometry experiments revealed the presence of noncondensed aromatic rings alongside species with up to nine fused aromatic rings in the late-eluting GPC fractions, as demonstrated for S2 class species. Finally, the GPC separation was also tested on a South American crude oil sample and found to fractionate it by the same molecular criterion, i.e., total alkyl chain length, independent of the crude oil API gravity, total sulfur and nitrogen contents, or geographical origin.

Alhosani, A., Scanziani, A., Lin, Q., Raeini, A.Q., Bijeljic, B., Blunt, M.J., 2020. Pore-scale mechanisms of CO2 storage in oilfields. Scientific Reports 10, 8534.

https://doi.org/10.1038/s41598-020-65416-z

Rapid implementation of global scale carbon capture and storage is required to limit temperature rises to 1.5 °C this century. Depleted oilfields provide an immediate option for storage, since injection infrastructure is in place and there is an economic benefit from enhanced oil recovery. To design secure storage, we need to understand how the fluids are configured in the microscopic pore spaces of the reservoir rock. We use high-resolution X-ray imaging to study the flow of oil, water and CO2 in an oil-wet rock at subsurface conditions of high temperature and pressure. We show that contrary to conventional understanding, CO2 does not reside in the largest pores, which would facilitate its escape, but instead occupies smaller pores or is present in layers in the corners of the pore space. The CO2 flow is restricted by a factor of ten, compared to if it occupied the larger pores. This shows that CO2 injection in oilfields provides secure storage with limited recycling of gas; the injection of large amounts of water to capillary trap the CO2 is unnecessary.

Álvarez-Muñoz, D., Farré, M. (eds.), 2020. Environmental Metabolomics. Applications in Field and Laboratory Studies to Understand from Exposome to Metabolome. Elsevier, p. 368.

https://doi.org/10.1016/C2018-0-03345-9

Environmental Metabolomics Applications in Field and Laboratory Studies: From the Exposome to the Metabolome presents an overview of the current state of aquatic environments and problems caused by human pressure and daily life. The presence of contaminants in nature and their effects are evaluated, along with recommendations for preservation. This book not only shows readers how to implement techniques, it also guides them through the process. As metabolomics becomes a more routine technique for environmental studies and future perspectives, a guide for validation and globalization of current approaches is needed.

Key Features

Presents relevant and reliable information on the use of different analytical techniques for establishing the environmental metabolomics of polluted systems

Includes a critical review of each central topic in every chapter, together with a bibliography and future trends

Provides, for the first time, a global opinion and guide for achieving standardized results

Chapter 1 - Fundamentals of environmental metabolomics, Vera Kovacevic and Myrna J. Simpson, Pages 1-33

Chapter 2 - Analytical techniques in metabolomics, Arthur David and Pawel Rostkowski, Pages 35-64

Chapter 3 - Metabolic profiling of biofluids in fish for identifying biomarkers of exposure and effects for assessing aquatic pollution, Pedro Carriquiriborde, Pages 65-89

Chapter 4 - Environmental metallomics and metabolomics in free-living and model organisms: an approach for unraveling metal exposure mechanisms, Julián Blasco, Gema Rodríguez-Moro, Belén Callejón-Leblic, Sara Ramírez-Acosta, Francisca Arellano-Beltrán, Ana Arias-Borrego, Tamara García-Barrera, José Luis Gómez-Ariza, Pages 91-119

Chapter 5 - The metabolic responses of aquatic animal exposed to POPs, Hailong Zhou, Chien-Min Chen and Xiaoping Diao, Pages 121-161

Chapter 6 - Metabolomics in plant protection product research and development: discovering the mode(s)-of-action and mechanisms of toxicity, Konstantinos A. Aliferis, Pages 163-194

Chapter 7 - Metabolomics strategies and analytical techniques for the investigation of contaminants of industrial origin, Òscar Aznar-Alemany and Marta Llorca, Pages 195-233

Chapter 8 - Mass spectrometry to explore exposome and metabolome of organisms exposed to pharmaceuticals and personal care products, Frédérique Courant, Hélène Fenet, Bénilde Bonnefille, Thibaut Dumas, Elena Gomez, Pages 235-257

Chapter 9 - Metabolomics effects of nanomaterials: an ecotoxicological perspective, Marinella Farré and Awadhesh N. Jha, Pages 259-281

Chapter 10 - Environmental metabolomics and xenometabolomics for the assessment of exposure to contaminant mixtures, Sara Rodríguez-Mozaz, Albert Serra-Compte, Ruben Gil-Solsona, Diana Álvarez-Muñoz, Pages 283-310

Chapter 11 - A snapshot of biomarkers of exposure for environmental monitoring, Diana Álvarez-Muñoz and Marinella Farré, Pages 311-338

Chapter 12 - Future trends in environmental metabolomics analysis, Diana Álvarez-Muñoz and Marinella Farré, Pages 339-341

Index Pages 343-351

Amiri, R., Khamehchi, E., Ghaffarzadeh, M., Kardani, N., 2020. Laboratory evaluation of a novel multifunctional chemical solution for asphaltene precipitation and aggregation problem: Comparison with an industrial chemical solution. Journal of Petroleum Science and Engineering 193, 107340.


Asphaltene deposition in the near-wellbore area and within the pipelines reduces productivity and is costly. There are usually 2 methods to remedy this hardship that are using dispersants or inhibitors to preventing asphaltene deposition or using solvents when asphaltene deposits on inner surface of pipes or in the porous media. In this study, additive called AUT Force 110 has been developed and its properties have been inspected. This solvent has multifunctional efficiencies (MS) such that can be used as asphaltene inhibition and dispersion and dissolve asphaltene deposits. Furthermore, its performance is compared to an industrial solvent called PL5001 (CS). Analyzing the fourier-transform infrared spectroscopy (FTIR) of the two additives were found to have polar functional groups of hydroxyl, thiol, carbonyl and carboxylic acid in their molecule. The existence of various functional groups gives the MS molecule the ability to interact with adjacent molecules through hydrogen bonding. In addition, aliphatic compounds were observed in the MS molecule with a low carbon number, which leads to its compatibility with crude oil. In contrast, the CS consists mainly of aromatic rings. Two carbonyl and ether functional groups were also observed in its molecular structure, which are very low in concentration compared to polar compounds of MS. Then, the confocal microscopy imaging was used to observe asphaltene aggregates with precipitant. The crude oil and n-heptane were combined in a ratio of 1–30 volumes. The addition of 100 ppm MS reduced about 87% of the mean diameter of asphaltene aggregates; while this reduction was less than 70% by adding CS. Also, adding MS narrowed the dispersion range of the asphaltene particles diameter to 2–16 μm. The carboxylic acid and thiol functional groups play important roles in asphaltene dispersion in MS system. Both MS and CS delayed the onset of asphaltene precipitation, however MS has greater asphaltene inhibition power as well as improving the rheological properties of crude oil and n-heptane solution due to the reduction in the size of asphaltene aggregates, the interaction of MS with asphaltene, and the reduction of the interaction between the asphaltene-asphaltene molecule besides the polar nature of MS. Turbiscan test was also used to measure the solvation power of two additives. The solubility number of MS was lower than that of CS and was reported to be a good solvent, indicating that it has better solvation power than CS. Because MS has the ability to hydrogen bond with asphaltene molecules as both donor and acceptor. Secondly, its aliphatic chains cause steric hindrance, which contributes to the stability of asphaltenes within MS.

Ansah, E.O., Vo Thanh, H., Sugai, Y., Nguele, R., Sasaki, K., 2020. Microbe-induced fluid viscosity variation: field-scale simulation, sensitivity and geological uncertainty. Journal of Petroleum Exploration and Production Technology 10, 1983-2003.

https://doi.org/10.1007/s13202-020-00852-1

This study is intended to expand the scope of microbial enhanced oil recovery (MEOR) simulation studies from 1D to field scale focussing on fluid viscosity variation and heterogeneity that lacks in most MEOR studies. Hence, we developed a model that incorporates: (1) reservoir simulation of microbe-induced oil viscosity reduction and (2) field-scale simulation and robust geological uncertainty workflow considering the influence of well placement. Sequential Gaussian simulation, co-kriging and artificial neural network were used for the petrophysical modelling prior to field-scale modelling. As per this study, the water viscosity increased from 0.5 to 1.72 cP after the microbe growth and increased biomass/biofilm. Also, we investigated the effect of the various component compositions and reaction frequencies on the oil viscosity and possibly oil recovery. For instance, the fraction of the initial CO2 in the oil phase (originally in the reservoir) was varied from 0.000148 to 0.005 to promote the reactions, and more light components were produced. It can be observed that the viscosity of oil reduced considerably after 90 days of MEOR operation from an initial 7.1–7.07 cP and 6.40 cP, respectively. Also, assessing the pre- and post-MEOR oil production rate, we witnessed two main typical MEOR field responses: sweeping effect and radial colonization occurring at the start and tail end of the MEOR process, respectively. MEOR oil recovery factors varied from 28.2 to 44.9% OOIP for the various 200 realizations. Since the well placement was the same for all realizations, the difference in the permeability distribution amongst the realizations affected the microbes’ transport and subsequent interaction with nutrient during injection and transport.

Arapova, O.V., Chistyakov, A.V., Tsodikov, M.V., Moiseev, I.I., 2020. Lignin as a renewable resource of hydrocarbon products and energy carriers (a review). Petroleum Chemistry 60, 227-243.

https://doi.org/10.1134/S0965544120030044

A review of modern industrial and developed experimental approaches to the separation and conversion of lignin—a renewable and accumulated raw material of plant origin—into important organic products is presented. Based on an analysis of the literature data, the prospects of the use of catalytic systems for increasing the selectivity and depth of lignin conversion were demonstrated. The basic principles of the application of microwave stimulation to the destruction of the stable structure of lignin, including a new approach to the rapid plasma-catalytic conversion of lignin into synthesis gas, were considered.


https://doi.org/10.1017/S1473550419000211

The extremotolerant bacterium Deinococcus radiodurans is used as a model to explore the limits of life on Earth and beyond. In experiments performed in an ultra-high vacuum chamber with a vacuum ultraviolet (VUV) synchrotron beamline, this microorganism was exposed to conditions present on an extraterrestrial environment unprotected by an atmosphere, such as outside a spacecraft or on an asteroid, relevant in the context of planetary protection and panspermia hypothesis. Different methods were used to obtain the biologically relevant information from this investigation. Counting of colony forming units, the traditional approach for viability assessment, is limited to measuring the survival of the cells. For a more in-depth study of damage mechanisms at

subcellular levels, specific molecular probes (propidium iodide and dihydrorhodamine 123) were applied and whole populations could be analysed, cell by cell, by flow cytometry. VUV radiation caused a substantial loss of viability, though only a fraction of the cells presented membrane damages even at the largest tested fluences. Additionally, intracellular oxidative stress was also detected upon exposure. These results point to significant VUV inactivating effects extending beyond the cells' outermost structures, in contrast to a more superficial role that could be expected due to the highly interacting nature of this radiation range. Nevertheless, it was observed that microscopic-level shading sufficed to allow the persistence of a small surviving subpopulation for the longer expositions. This study contributes to unveiling the response of biological systems under space conditions, assessing not just cell viability but also the mechanisms that lead to inactivation.

Aravind, S., Kumar, P.S., Kumar, N.S., Siddarth, N., 2020. Conversion of green algal biomass into bioenergy by pyrolysis. A review. Environmental Chemistry Letters 18, 829-849.

https://doi.org/10.1007/s10311-020-00990-2

Climate change issues are calling for the design of renewable sources of energy. In particular, biomass energy from algae is encouraging because production of algae at the commercial scale can be done successfully with various techniques. Here, we review the conversion of algal biomass into energy by fast, slow, microwave and catalytic pyrolysis. The article details algae classification; cultivation of macroalgae and microalgae; pyrolysis parameters; production of biochar, bio-oil and biogas; and types of pyrolysis.


https://doi.org/10.1007/s00367-020-00644-w

We provide new evidence of the preservation of 34S-enriched signals in methane seep-impacted sediments from two onshore Miocene outcrops located in the northern Apennines (Italy). Selected outcrops include methane-derived authigenic carbonates (MDAC) with δ13C composition between − 42.3 and − 18.2‰. MDACs contain chemosynthetic clams and abundant pyrite indicative of formation close to or within a shallow sulfate-methane transition zone (SMTZ). This study aims to evaluate the relative contributions of background organic matter mineralization and anaerobic oxidation of methane (AOM) to sulfate consumption and to gain insight into the transport process (i.e., diffusion, advection) controlling the depth of the SMTZ. Host sediments were investigated by CHN elemental analysis coupled with total sulfur (TS) and sulfur isotopic measurements on bulk samples. Total organic carbon (TOC) measurements reveal a consistent and low amount of organic carbon (TOC< 0.5%), with no notable difference between the underlying turbidites and the stratigraphic intervals hosting the MDACs. The TS/TOC ratio of most samples is well above the baseline value of deposition under normal marine conditions, suggesting the excess TS here is due to enhanced sulfate reduction. The samples show bulk δ34S values commonly enriched (> 0‰ and up to + 17.1‰), which is characteristic of sulfides precipitated in association with AOM. We propose that advection of methane-rich fluids was responsible for maintaining the shallow depth of the studied paleo-SMTZs. AOM at paleo-SMTZ positions in the investigated seep-impacted sediments

resulted in excess bicarbonate and sulfide production, favoring solid-phase MDAC and iron sulfide precipitation.


https://www.biogeosciences-discuss.net/bg-2020-166/

Stable isotopes in tree-ring cellulose are important tools for climatic reconstructions even though their interpretation could be challenging due to non-climate signals, primarily those related to tree ageing. Previous studies on the presence of tree-age related trends during juvenile as well as adult growth phases in δD, δ18O and δ13C time series yielded variable results that are not coherent among different plant species. We analysed possible trends in the extracted cellulose of tree-rings of 85 larch trees and 119 cembran pine trees, i.e. in samples of one deciduous and one evergreen conifer species collected at the treeline in the Alps covering nearly the whole Holocene. The age trend analyses of all tree-ring variables were conducted on the basis of mean curves established by averaging the cambial-age aligned tree series. For cambial ages over 100 years, our results prove the absence of any age-related effect in the δD, δ18O and δ13C time series for both the evergreen as well the deciduous conifer species, with the only exception of larch δD. However, for lower cambial ages, we found trends that differ for each isotope and species. I.e., mean δ13C values in larch do not vary with ageing and can be used without detrending, whereas those in cembran pine show a juvenile effect and the data should be detrended. Mean δ18O values present two distinct ageing phases for both species complicating detrending. Similarly, mean δD values in larch change in the first 50 yr whereas cembran pine between 50–100 yr. Values for these two periods of cambial age for δD and δ18O should be used with caution for climatic reconstructions, ideally complemented by additional information regarding mechanisms for these trends.

Arunachalam, K., Fan, X., 2020. Impact of heat of sorption on thermal enhanced recovery of sorbed gas from gas shale reservoirs – An experimental and simulation study. Journal of Natural Gas Science and Engineering 79, 103318.


The importance of heat of sorption in the thermal enhanced recovery of gas shale reservoirs is not well understood in the reservoir engineering community. Our results indicate that not accounting for the heat of sorption significantly over-estimated the potential for thermal enhanced gas recovery under heated conditions by about 13%. However, including the heat of sorption parameter under normal operating (isothermal) conditions did not have any effect on production estimates. This suggests that heat of sorption is a significant parameter, and cannot be ignored whilst assessing the potential for thermal enhanced recovery in gas shales. The multi-physical reservoir simulation was carried out using a modified equation for heat transfer that accounts for heat of sorption. The Langmuir equation was modified to account for the temperature dependence of sorption. Input parameters for the numerical study - sorption, heat of sorption, porosity, and permeability were experimentally measured in the laboratory using a high-pressure rig. The maximum sorption capacity on shale samples used in this study decreased significantly by 25% when the temperature was increased from 60 to 80 °C. Using sensitivity analysis, shales with high adsorption capacity and

low heat of sorption were found to be good candidates for thermal stimulation to enhance sorbed gas recovery.

Asadzadeh, S., de Souza Filho, C.R., 2020. Characterization of microseepage-induced diagenetic changes in the Upper-Red Formation, Qom region, Iran. Part I: Outcrop, geochemical, and remote sensing studies. Marine and Petroleum Geology 117, 104149.


This article explores the footprints of hydrocarbon microseepage in the Upper-Red Formation covering the Alborz petroleum reservoir in the Saveh-Qom basin, Iran. The adopted multidisciplinary approach combines field observation and sampling, detailed petrographical and geochemical analysis, and remote sensing mapping using Sentinel-2 and ASTER satellite data. The study revealed significant changes in the microseepage-affected zones when contrasted to unaffected lithofacies and led to the establishment of a new array of mineralogical and geochemical indicators for the phenomenon. These comprise partial bleaching of the red-beds, secondary goethite coatings, diagenetic clay minerals (e.g. illite-smectite, chlorite), and pervasive calcite, silica, and gypsum cementations. In terms of geochemistry, the major oxides, particularly the ratio of CaO + K2O/Na2O + MgO + CaO + K2O proved to be a reliable index for distinguishing microseepage-prone areas. Based on isotopic studies, a combination of three sources of carbon, comprising oxidized hydrocarbons, was recognized in the carbonate cements; yet the strata were shown to be moderately flushed by percolating fluids. Satellite remote sensing was successful in mapping reservoir-scale footprints of the microseepage systems. It indicated that the extent of the induced alterations, and thereby the outline of the underlying reservoir, is much larger than previously known. Overall, the secondary changes were shown to be a function of the geochemistry of the host-rock, the local environmental variables (i.e. climate and hydrogeology), and the 3D architecture of the trap. The substantiated indicators carry direct implications for onshore microseepage targeting and hold high potential to help reduce the exploration and development risks in frontier and mature basins.

Asadzadeh, S., Souza Filho, C.R., 2020. Characterization of microseepage-induced diagenetic changes in the Upper-Red Formation, Qom region, Iran. Part II: A new insight using reflectance spectroscopic analysis. Marine and Petroleum Geology 117, 104387.


The classic microseepage model supports the notion that hydrocarbon pools leak to the surface over time and trigger an array of diagenetic physicochemical and mineralogical changes in the overlying sediments. Mapping the induced alteration mineralogy for microseepage targeting has been an appealing yet ambiguous practice, mostly because of our incomplete understanding of the diversity of changes occurring in the environment. To close this gap, an integrated spectroscopic approach is adopted here to investigate the variability, quantity, and physicochemistry of diagenetic minerals induced by active microseepage systems over the Alborz oil reservoir in the Qom region, Iran. The area includes an effectively sealed carbonate reservoir overlain by thick Oligocene sediments of the Upper Red Formation. A large suite of samples collected from microseepage-affected zones was spectrally characterized in the 350–2500 nm wavelength region and then statistically contrasted

against unaffected samples gathered from a nearby control area. The analysis reveals a novel array of mineralogic indicators for microseepage systems. It indicates that smectites (montmorillonite, nontronite), Al-rich mixed-layer illite/smectite, Fe-rich chlorite and traces of palygorskite constitute the clay alterations. This array is associated with the enrichment of K2O and loss of Na2O and MgO from the system, as indicated by X-ray fluorescence measurements. In the arid climate of the region, the iron-rich red-beds (Fe2O3 > 6%) are only moderately bleached and, thus, the subsequent chemical weathering of the relict irons has triggered goethite (Al-poor), and likely ferrihydrite and maghemite precipitation. Consequently, besides the typical ferric iron bleaching, the modification in the mineralogy of iron oxides/oxyhydroxides (marked by a shift in the absorption minimum at ~900 nm) is suggested as an additional indicator of microseepage systems. Fe-chlorites constitute the dominant ferrous mineral present in the environment. The affected strata are also associated with prevalent calcite and gypsum cements, and occasionally jarosite occurrences. Based on the silica contents of the host-rock, the microseepage-induced alterations are classified into two categories, namely ‘felsic’ and ‘mafic’, wherein the latter is typified by the assemblages described here. This study provides new insights into microseepage-induced alterations and highlights the significance of reflectance spectroscopic techniques in facies determination and the alteration footprints mapping of onshore microseepage systems.

Åström, E.K.L., Sen, A., Carroll, M.L., Carroll, J., 2020. Cold seeps in a warming Arctic: Insights for benthic ecology. Frontiers in Marine Science 7, 244. doi: 10.3389/fmars.2020.00244.

https://www.frontiersin.org/article/10.3389/fmars.2020.00244

Cold-seep benthic communities in the Arctic exist at the nexus of two extreme environments; one reflecting the harsh physical extremes of the Arctic environment and another reflecting the chemical extremes and strong environmental gradients associated with seafloor seepage of methane and toxic sulfide-enriched sediments. Recent ecological investigations of cold seeps at numerous locations on the margins of the Arctic Ocean basin reveal that seabed seepage of reduced gas and fluids strongly influence benthic communities and associated marine ecosystems. These Arctic seep communities are mostly different from both conventional Arctic benthic communities as well as cold-seep systems elsewhere in the world. They are characterized by a lack of large specialized chemo-obligate polychetes and mollusks often seen at non-Arctic seeps, but, nonetheless, have substantially higher benthic abundance and biomass compared to adjacent Arctic areas lacking seeps. Arctic seep communities are dominated by expansive tufts or meadows of siboglinid polychetes, which can reach densities up to >3 × 105 ind.m–2. The enhanced autochthonous chemosynthetic production, combined with reef-like structures from methane-derived authigenic carbonates, provides a rich and complex local habitat that results in aggregations of non-seep specialized fauna from multiple trophic levels, including several commercial species. Cold seeps are far more widespread in the Arctic than thought even a few years ago. They exhibit in situ benthic chemosynthetic production cycles that operate on different spatial and temporal cycles than the sunlight-driven counterpart of photosynthetic production in the ocean’s surface. These systems can act as a spatio-temporal bridge for benthic communities and associated ecosystems that may otherwise suffer from a lack of consistency in food quality from the surface ocean during seasons of low production. As climate change impacts accelerate in Arctic marginal seas, photosynthetic primary production cycles are being modified, including in terms of changes in the timing, magnitude, and quality of photosynthetic carbon, whose delivery to the seabed fuels benthic communities. Furthermore, an increased northward expansion of species is expected as a

consequence of warming seas. This may have implications for dispersal and evolution of both chemosymbiotic species as well as for background taxa in the entire realm of the Arctic Ocean basin and fringing seas.



Kimberlite-borne granulite xenoliths provide rare insights into the age, chemical composition and tectonothermal evolution of the otherwise largely inaccessible deep cratonic crust. The formation and transformation of the lower continental crust (LCC) beneath the central Slave craton (Canada) is here illuminated using whole-rock trace-element and Sr-Nd isotope compositions of nine metabasaltic (MBG), one gabbroic (MGG) and two metasedimentary/hybrid (MSG) granulite xenoliths. On the one hand, published sulphide Re-Os and a few zircon U-Pb data indicate that at least a portion of the LCC beneath the central Slave craton has a Palaeoarchaean origin (∼3.3 Ga), which apparently coincides with a period of juvenile crust and deep lithospheric mantle formation during plume impingement beneath the pre-existing cratonic nucleus. On the other hand, enrichment in Li, Sr, LREE, Pb and Th, but relative depletion in Ti, Hf and HREE, suggest formation of (picro)basaltic protoliths by partial melting of a subduction-modified garnet-bearing source, Crystallisation in the crust after fractionation of plagioclase is inidicated by their Sr and Eu negative anomalies, which are complementary to the positive anomalies in the MGG. Samarium-Nd isotopes in MBG and MGG show large scatter, but fall on Neo- or Mesoarchaean age arrays. These elemental systematics are suggested to fingerprint deserpentinisation fluids plus small amounts of sedimentary melt as the main contaminants of the mantle source, supporting the operation of at least regional and transient subduction at 3.3 Ga. Evidence for quasi-coeval plume impingement and subduction beneath the central Slave craton in the Mesoarchaean is reconcilable in a dynamic regime where vertical tectonics, though waning, was still active and plate interactions became increasingly important. Unradiogenic 87Sr/86Sr (down to 0.7017) is consistent with significant loss of Rb and probably other heat-producing elements (K, Th, U) plus H2O during Neoarchaean metamorphism, which helped to enhance LCC viscosity and stabilise the cratonic lithosphere.

Avdonin, V.V., Zhegallo, E.A., Sergeeva, N.E., 2020. The microstructure of oxide ferromanganese ores in the world ocean as proof of their bacterial origin. Moscow University Geology Bulletin 75, 1-6.

https://doi.org/10.3103/S0145875220010020

Study of the submicroscopic structure of oxide ores revealed their similarity to the present-day bacterial communities. It was shown that the structure of cobalt-bearing crusts and ferromanganese nodules is based on bacterial mats, which permits identifying them as stromatolites and oncolites. Data that support intense interaction between biofilms and the environment were found. Signs of formation of the mineral phase as a result of biochemical absorption and assimilation of iron and manganese by bacteria were observed.



An image-based volumetric equation for estimating the prospective CO2 mass storage resource potential for organic-rich shale formations has been developed using data obtained from advanced image analysis of Bakken Formation shale samples. The equation is a modification of the U.S. Department of Energy (DOE) National Energy Technology Laboratory’s (NETL’s) volumetric equation methodology for estimating the prospective CO2 mass storage resource for shale formations. The current equation enhances DOE’s version by systematically deriving expressions for calculating efficiency factors based on analysis of high-resolution field-emission scanning electron microscopy (FESEM) shale images. FESEM images are used to obtain improved nanoscale porosity estimates for the shale matrix and OM. The calculation of the efficiency factors associated with free-phase storage and CO2 adsorption onto solid surfaces are based on a ratio of connected-to-nonconnected porosity and the newly developed shared border analysis (SBA) method, respectively. The image-based equation described herein is structured so that it can be adapted and applied to other formation types by considering the specific mineralogy or matrix characteristics. Preliminary data used to illustrate the newly developed equation show that the Upper Bakken Shale (UBS) may have a lower prospective CO2 storage resource potential than the Lower Bakken Shale (LBS) by about 65 %. Although these results are neither optimized for each lithofacies nor represent the Bakken formation regional scale, they are encouraging for unfractured shale samples and serve as a useful starting point for future evaluations at the regional scale.



The adsorption capacity of coal with respect to carbon dioxide (CO2) is greater than that of methane (CH4). Studying the CO2 replacement of CH4 in coal is essential to understanding the mechanism behind CO2-enhanced coalbed methane. In this paper, scanning electron microscopy was used to qualitatively study the influence of CO2 injection pressure on the fracture characteristics of coal. The time effect of the CH4/CO2 adsorption and the effect of the CO2 injection on the CH4 adsorption were quantitatively studied using low-field nuclear magnetic resonance. The results suggest three different CH4 states in the coal samples: CH4 adsorbed on the pore surface, free CH4 in the pore center, and free CH4 between the coal particles. Indeed, the greater the CO2 injection pressure, the more developed the fracturing and network, which, in turn, increases connectivity. As the adsorption time of CH4/CO2 increases, the adsorption rate of CO2/CH4 gradually decreases. In essence, CO2 preferentially replaces the CH4 of the minipores. As the CO2 injection pressure increases, the difference between the CO2 equilibrium pressure and the initial injection pressure increases. Moreover, the CH4 production rate increases, the transverse relaxation time (T2) spectrum of the adsorption-state area decreases, the T2 spectrum of the free-state area increases, and the number of adsorption holes gradually decreases, whereas the number of seepage holes increases.

Bai, Y., Ma, Y., 2020. Geology of the Chang 7 Member oil shale of the Yanchang Formation of the Ordos Basin in central north China. Petroleum Geoscience 26, 355.

http://pg.lyellcollection.org/content/26/2/355.abstract

We present a review of the Chang 7 Member oil shale, which occurs in the middle–late Triassic Yanchang Formation of the Ordos Basin in central north China. The oil shale has a thickness of 28 m (average), an area of around 30 000 km2 and a Ladinian age. It is mainly brown-black to black in colour with a laminar structure. It is characterized by average values of 18 wt% TOC (total organic carbon), 8 wt% oil yield, a 8.35 MJ kg−1 calorific value, 400 kg t−1 hydrocarbon productivity and kerogen of type I–II1, showing a medium quality. On average, it comprises 49% clay minerals, 29% quartz, 16% feldspar and some iron oxides, which is close to the average mineral composition of global shale. The total SiO2 and Al2O3 comprise 63.69 wt% of the whole rock, indicating a medium ash type. The Sr/Ba is 0.33, the V/Ni is 7.8, the U/Th is 4.8 and the FeO/Fe2O3 is 0.5, indicating formation in a strongly reducing, freshwater or low-salinity sedimentary environment. Multilayered intermediate-acid tuff is developed in the basin, which may have promoted the formation of the oil shale. The Ordos Basin was formed during the northwards subduction of the Qinling oceanic plate during the Ladinian–Norian in a back-arc basin context. The oil shale of the Ordos Basin has a large potential for hydrocarbon generation. Supplementary material: Tables of oil-shale geochemical composition, proximate and organic matter analyses from the Chang 7 Member oil shale, the Ordos Basin, Central north China are available at https://doi.org/10.6084/m9.figshare.c.4411703

Bai, Z., Cheng, M., Chen, C., Huo, J., Zhang, J., Zhou, X., Gao, Y., Zhao, B., Qiu, H., Han, M., Yang, Y., Sun, Z., Miao, M., Zhang, J., Li, Q., 2020. Distribution features of the Nanhua-Sinian rifts and their significance to hydrocarbon accumulation in the Tarim Basin. Acta Geologica Sinica - English Edition 94, 501-515.

https://doi.org/10.1111/1755-6724.14340

On the basis of reprocessing 34 new two dimensional spliced long sections (20,191 km) in the Tarim ‐Basin, the deep structure features of the Tarim Basin were analyzed through interpreting 30,451 km of two dimensional seismic data and compiling basic maps. Seismic interpretation and geological ‐analysis conclude that the Nanhua Sinian strata are a set of rift depression depositional systems ‐ ‐according to their tectonic and depositional features. The rift valley formed in the Nanhua Period, and the transformation became weaker during the late Sinian Period, which eventually turned into depression. From bottom to top, the deposited strata include mafic igneous, tillite, mudstone, and dolomite. Three major depocenters developed inside this basin during the rift stage and are distributed in the eastern Tarim Basin, the Awati area, and the southwestern Tarim Basin. Among them, the rift in the eastern Tarim Basin strikes in the near east west direction on the plane and ‐coincides with the aeromagnetic anomaly belt. This represents a strong magnetic zone formed by upwelling basic volcanic rock along high, steep normal faults of the Nanhua Period. Controlled by the tectonic background, two types of sedimentary systems were developed in the rift stage and depression stage, showing two types of sequence features in the Sinian depositional stage. The Nanhua System appears as a wedge shaped formation, with its bottom in unconformable contact ‐with the base. The rifting event has a strong influence on the current tectonic units in the Tarim Basin, and affects the distribution of source rock in the Yuertus Formation and reservoir beds in the Xiaoerbulake Formation in Lower Cambrian, as well as the gypseous cap rock in Middle Cambrian. The distribution features of the rifts have important and realistic significance for determining the

direction of oil and gas exploration in the deep strata of the Tarim Basin. Comprehensive analysis suggests that the Tazhong region is the most favorable zone, and the Kalpin Bachu region is the ‐optimal potential zone for exploring sub salt oil and gas in deep Cambrian strata.‐

Bailleul, A.M., Zheng, W., Horner, J.R., Hall, B.K., Holliday, C.M., Schweitzer, M.H., 2020. Evidence of proteins, chromosomes and chemical markers of DNA in exceptionally preserved dinosaur cartilage. National Science Review 7, 815-822.

https://doi.org/10.1093/nsr/nwz206

A histological ground-section from a duck-billed dinosaur nestling (Hypacrosaurus stebingeri) revealed microstructures morphologically consistent with nuclei and chromosomes in cells within calcified cartilage. We hypothesized that this exceptional cellular preservation extended to the molecular level and had molecular features in common with extant avian cartilage. Histochemical and immunological evidence supports in situ preservation of extracellular matrix components found in extant cartilage, including glycosaminoglycans and collagen type II. Furthermore, isolated Hypacrosaurus chondrocytes react positively with two DNA intercalating stains. Specific DNA staining is only observed inside the isolated cells, suggesting endogenous nuclear material survived fossilization. Our data support the hypothesis that calcified cartilage is preserved at the molecular level in this Mesozoic material, and suggest that remnants of once-living chondrocytes, including their DNA, may preserve for millions of years.



Analysis of fatty acids in the form of fatty acid methyl esters (FAMEs) using gas chromatography (GC) is routine within microbiology but still some compounds remain unidentified. During characterization of the FAMEs of two strains of the microaerophilic bacterium Lutibacter sp., recently isolated from the Black Sea, a series of compounds, eluting after the regular FAMEs, were detected. We identified these compounds using GC–mass spectrometry (GC–MS) and an authentic standard, to be amino acids glycine-linked via an amide bond to β-hydroxy fatty acids (i.e. glycine β-hydroxy fatty acid amides). Analysis of the intact polar lipids of the Lutibacter species by ultra-high performance liquid chromatography–high resolution mass spectrometry (UHPLC–HRMS) showed that the glycine β-hydroxy fatty acid amides are derived from glycine lipids (also known as cytolipins), which are amino acid lipids. Amino acid lipids represent an under-studied, but potentially significant, group of microbial membrane lipids and our results provide a rapid way to detect the presence of glycine lipids during routine fatty acid analysis by GC. Furthermore, glycine β-hydroxy fatty acid amides represent easily detectable biomarker lipids for glycine lipid-producing microorganisms in natural environments.

Baú, J.P.T., Villafañe-Barajas, S.A., Negrón-Mendoza, A., Colín-García, M., Zaia, D.A.M., 2020. Effect of γ-radiation on adenine dissolved in distilled water, saline solutions and artificial seawater resembling that of 4.0 billion years ago. International Journal of Astrobiology 19, 224-236.

https://doi.org/10.1017/S1473550419000272

In this work, the effect of γ-radiation on the decomposition of adenine dissolved in distilled water, saline solutions and artificial seawater was studied. As the composition of the major cations and anions of artificial seawater probably better resembles the composition of seawater on the Earth 4.0 billion years ago, this seawater was named artificial seawater 4.0 Ga. The main finding in this work is that artificial seawater 4.0 Ga demonstrated a better protective effect of adenine against γ-radiation. In addition, artificial seawater 4.0 Ga showed that adenine had no changes in pH after radiation exposure and the minor radiation-chemical yield G. The radiolysis of adenine promoted modifications in Fourier-transform infrared spectra. The deconvolution of some bands demonstrated the formation of a new frequency at 1713 cm−1. High performance liquid chromatography-mass detected a product of decomposition with 151 atomic units. Using the geometry optimization and simulated vibrational spectra it was possible to show that the main species formed are hydroxyl and oxide modified adenine. The data point to the formation of hydroxyl-adenine and adenine Nx-oxide. These products have biological relevance and could be available for chemical evolution.

Becker-Kerber, B., Paim, P.S.G., Chemale Junior, F., Girelli, T.J., da Rosa, A.L.Z., Albani, A.E., Osés, G.L., Prado, G.M.E.M., Figueiredo, M., Simões, L.S.A., Pacheco, M.L.A.F., 2020. The oldest record of Ediacaran macrofossils in Gondwana (~563 Ma, Itajaí Basin, Brazil). Gondwana Research 84, 211-228.

http://www.sciencedirect.com/science/article/pii/S1342937X20301210

The Avalon biota (Ediacaran Period, 570–559 Ma) marks the first appearance of macroscopic and complex benthic communities in the fossil record. This assemblage is known from a few localities worldwide, mainly in Canada and England. Here, we report for the first time the presence of Ediacaran macrofossils in deposits of similar age from Gondwana (Itajaí Basin, southern Brazil). Our new radiometric date (~563 Ma) indicates that the Itajaí Basin can be chronocorrelated with the classic Avalonian deposits and thus represents one of the oldest records of the Ediacaran biota in Gondwana. We describe the presence of the Ediacaran genus Palaeopascichnus, as well as discs (Aspidella and Nimbia), and other problematic forms. Contrary to the deep-marine macroorganisms of the Avalon Assemblage, the Itajaí fossils are associated with abundant and exceptionally preserved three-dimensional microbial mats and microbially induced sedimentary structures (MISS) in relatively shallow settings (upper slope and distal delta front deposits). In this sense, the Itajaí biota could represent early adaptations of benthic macrobiota to the shallower and more photic environments that characterize the later White Sea Assemblage.

Bednařík, A., Preisler, J., Bezdeková, D., Machálková, M., Hendrych, M., Navrátilová, J., Knopfová, L., Moskovets, E., Soltwisch, J., Dreisewerd, K., 2020. Ozonization of tissue sections for MALDI MS imaging of carbon–carbon double bond positional isomers of phospholipids. Analytical Chemistry 92, 6245-6250.

https://doi.org/10.1021/acs.analchem.0c00641

Visualizing the differential distribution of carbon–carbon double bond (C═C db) positional isomers of unsaturated phospholipids (PL) in tissue sections by use of refined matrix-assisted laser desorption

ionization mass spectrometry imaging (MALDI MSI) technologies offers a high promise to deeper understand PL metabolism and isomer-specific functions in health and disease. Here we introduce an on-tissue ozonization protocol that enables a particular straightforward derivatization of unsaturated lipids in tissue sections. Collision-induced dissociation (CID) of MALDI-generated ozonide ions (with yields in the several ten percent range) produced the Criegee fragment ion pairs, which are indicative of C═C db position(s). We used our technique for visualizing the differential distribution of Δ9 and Δ11 isomers of phosphatidylcholines in mouse brain and in human colon samples with the desorption laser spot size 15 μm, emphasizing the potential of the technique to expose local isomer-specific metabolism of PLs.


https://doi.org/10.1038/s41598-020-64990-6

Precambrian cellular remains frequently have simple morphologies, micrometric dimensions and are poorly preserved, imposing severe analytical and interpretational challenges, especially for irrefutable attestations of biogenicity. The 1.88 Ga Gunflint biota is a Precambrian microfossil assemblage with different types and qualities of preservation across its numerous geological localities and provides important insights into the Proterozoic biosphere and taphonomic processes. Here we use synchrotron-based ptychographic X-ray computed tomography to investigate well-preserved carbonaceous microfossils from the Schreiber Beach locality as well as poorly-preserved, iron-replaced fossil filaments from the Mink Mountain locality, Gunflint Formation. 3D nanoscale imaging with contrast based on electron density allowed us to assess the morphology and carbonaceous composition of different specimens and identify the minerals associated with their preservation based on retrieved mass densities. In the Mink Mountain filaments, the identification of mature kerogen and maghemite rather than the ubiquitously described hematite indicates an influence from biogenic organics on the local maturation of iron oxides through diagenesis. This non-destructive 3D approach to microfossil composition at the nanoscale within their geological context represents a powerful approach to assess the taphonomy and biogenicity of challenging or poorly preserved traces of early microbial life, and may be applied effectively to extraterrestrial samples returned from upcoming space missions.

Berrier, K.L., Reaser, B.C., Pinkerton, D.K., Synovec, R.E., 2019. Examination of the two-dimensional mass channel cluster plot method for gas chromatography – mass spectrometry in the context of the statistical model of overlap. Journal of Chromatography A 1601, 319-326.


Evaluation of a recently developed data reduction method for gas chromatography time-of-flight mass spectrometry (GC-TOFMS) is presented in the context of the statistical model of overlap (SMO) using simulated chromatographic data. The two-dimensional mass cluster plot method (2D m/z cluster plot method) significantly improves separation visualization by measuring the retention time, tR, and peak width-at-base, wb, of each analyte peak on a per mass channel, m/z, basis and plotting wb versus tR as a single point for each peak. Additional selectivity is provided by the peak width dimension, allowing for the differentiation of “pure” or selective m/z and shared or overlapped m/z. Analyte clusters in the 2D mass cluster plot are defined based on clustering of individual points,

representing the selective m/z for those analytes, and encompassed by a box of user-specified size. The method is applied to simulated chromatographic data with a random, independent distribution of analyte peaks and constant peak wb. Two levels of chromatographic saturation factor, α, and two sets of analyte mass spectra with varying spectral similarity are studied to assess method performance. The percentage of analyte clusters found relative to the number of analytes simulated in the chromatogram increases as the box size (analogous to chromatographic resolution, Rs) is decreased, resulting in an Rs limit of 0.05 for the method. Additionally, the percentage of analyte clusters discovered also increases with lower α and greater dissimilarity between analyte mass spectra, demonstrating the immense benefit of improving the chromatographic separation and chemical selectivity in analyte discovery, identification, and quantification.


https://doi.org/10.1038/s41396-020-0618-2

The majority of anaerobic biogeochemical cycling occurs within marine sediments. To understand these processes, quantifying the distribution of active cells and gross metabolic activity is essential. We present an isotope model rooted in thermodynamics to draw quantitative links between cell-specific sulfate reduction rates and active sedimentary cell abundances. This model is calibrated using data from a series of continuous culture experiments with two strains of sulfate reducing bacteria (freshwater bacterium Desulfovibrio vulgaris strain Hildenborough, and marine bacterium Desulfovibrio alaskensis strain G-20) grown on lactate across a range of metabolic rates and ambient sulfate concentrations. We use a combination of experimental sulfate oxygen isotope data and nonlinear regression fitting tools to solve for unknown kinetic, step-specific oxygen isotope effects. This approach enables identification of key isotopic reactions within the metabolic pathway, and defines a new, calibrated framework for understanding oxygen isotope variability in sulfate. This approach is then combined with porewater sulfate/sulfide concentration data and diagenetic modeling to reproduce measured 18O/16O in porewater sulfate. From here, we infer cell-specific sulfate reduction rates and predict abundance of active cells of sulfate reducing bacteria, the result of which is consistent with direct biological measurements.

Beyssac, O., 2020. New Trends in Raman Spectroscopy: From High-Resolution Geochemistry to Planetary Exploration. Elements 16, 117-122.

https://doi.org/10.2138/gselements.16.2.117

This article reviews nonconventional Raman spectroscopy techniques and discusses present and future applications of these techniques in the Earth and planetary sciences. Time-resolved spectroscopy opens new ways to limit or exploit luminescence effects, whereas techniques based on coherent anti-Stokes Raman scattering (CARS) or surface-enhanced Raman spectroscopy (SERS) allow the Raman signal to be considerably enhanced even down to very high spatial resolutions. In addition, compact portable Raman spectrometers are now routinely used out of the laboratory and are even integrated to two rovers going to Mars in the near future.


https://doi.org/10.1007/s12517-020-05335-5

This paper investigates the characteristics of sedimentary faces, source rocks, and hydrocarbon accumulation in detail within the Paleogene and Upper Cretaceous in the northern Kaikang trough, Muglad Basin. Analysis shows that the fluvial floodplain, delta, and shore-shallow lake facies are well developed in the main formations and several reservoir-cap assemblages are formed. Research on geochemical indicators, hydrocarbon generation, and expulsion potential of source rocks indicated that the thickness of good source rocks in Paleogene ranges from 50 to 200 m and TOC value can reach 0.5–1.3%, but it is immature and has no hydrocarbon generation potential. Nevertheless, the Upper Cretaceous source rocks are mostly matured, but its hydrocarbon generation is limited because of lower TOC (only 0.5–0.8%) and thinner thickness (only 10 m). The main effective source rock is the AG Group in the Lower Cretaceous, which is distributed throughout the area. The evolutionary history shows that most of structures in the central troughs lack hydrocarbon potential, because they were formed since the Paleogene, which are later than the main accumulation period of the AG source rock. The fault terrace zones on both sides of the Kaikang trough have obtained petroleum discovery, but the distribution of oil layers is much complicated. Hydrocarbon accumulation is controlled by formation dips, fault activity intensity, and fault lateral docking characteristics. The weaker active fault block in late period and more effective trap are the key factors to hydrocarbon enrichment at the fault terrace zones. There are two typical reservoir-forming modes; one is the small fault distance reservoir-forming mode of the lower primary reservoir, and the other is the secondary reservoir-forming mode of the upper and middle combination.

Bishop, M.E., Dong, H., Glasser, P., Briggs, B.R., Pentrak, M., Stucki, J.W., 2020. Microbially mediated iron redox cycling of subsurface sediments from Hanford Site, Washington State, USA. Chemical Geology 546, 119643.


Iron-bearing clay minerals are predominant in soils and sediments, and they undergo oxidation-reduction cycles as a result of natural processes such as wetting/drying cycles and plant root respiration. However, the kinetics and mechanisms of multiple redox cycles of iron in clay-rich sediments and consequences of such cycling on sediment properties are poorly understood. The objective of this study was to understand how multiple redox cycles of Fe in clay-rich sediment affect the rate and extent of Fe bioreduction and the physicochemical properties of the sediment. A natural sediment sample containing Fe-bearing montmorillonite from Hanford, Washington, USA was size-fractionated [2.0 to 0.5 μm (Hanford-C) and 0.5 to 0.02 μm (Hanford-F)] and redox-cycled for four times. Bioreduction was achieved utilizing Geobacter sulfurreducens and re-oxidization was performed with sparged air. Time-course change of total Fe (II) was monitored to measure the rate and extent of Fe (III) bioreduction. Redox-cycled sediments were characterized to determine the physicochemical changes. Both the initial rate and extent of bioreduction fluctuated across the four redox cycles, but they ultimately decreased from 5.3 μmol g−1 h−1 and 22.9% to nearly zero by the fourth cycle. These fluctuation patterns were likely due to a combined effect of reductive dissolution of small/poorly crystalline clay particles (by 3–5%) and clay mineral structural changes, as evidenced

by redox induced changes of aqueous chemistry, surface area, cation exchange capacity, mineralogy, and Mössbauer parameters. Once these small/poorly crystalline clay particles were dissolved, structural Fe in residual larger and more crystalline clay particles was largely reversible across additional redox cycles, as revealed by Mössbauer spectroscopy through the first three cycles.

Blach, T., Radlinski, A.P., Edwards, D.S., Boreham, C.J., Gilbert, E.P., 2020. Pore anisotropy in unconventional hydrocarbon source rocks: A small-angle neutron scattering (SANS) study on the Arthur Creek Formation, Georgina Basin, Australia. International Journal of Coal Geology 225, 103495.


Small-angle neutron scattering (SANS) measurements were performed on 32 rock samples from the southern Georgina Basin, central Australia to assess nanopore anisotropy. Anisotropy can only be determined from oriented core material, hence the samples were cut perpendicular to bedding in cores selected from three wells that intersect the base of the hydrocarbon-bearing, organic-rich middle Cambrian Arthur Creek Formation; the latter is the source rock for both unconventional and conventional plays in the basin. The evolution of anisotropy of two-dimensional SANS intensity profiles with depth (for pore diameters ranging from 10 nm to 100 nm) was quantified and correlated with SANS intensity and total organic carbon (TOC) content. Our results confirm hydrocarbon generation at the base of the Arthur Creek Formation in the wells analysed. The nanopore anisotropy in the basal Arthur Creek Formation at the well locations CKAD0001 (oil generation window) and MacIntyre 1 (late oil generation window) varies roughly according to normal compaction. When the Arthur Creek Formation is in the gas window, as sampled at Baldwin 1, there is a strong (negative) correlation between the average vertical-to-horizontal pore shape anisotropy and SANS intensity. The results indicate that unconventional gas production from organic-rich regions of overmature shale may be adversely affected by abnormal pore compaction.

Blattmann, T.M., Ishikawa, N.F., 2020. Theoretical amino acid-specific radiocarbon content in the environment: Hypotheses to be tested and opportunities to be taken. Frontiers in Marine Science 7, 302. doi: 10.3389/fmars.2020.00302.


Tracing of biogeochemical pathways using molecular approaches has advanced our basic understanding of the carbon cycle and life’s legacy in the sedimentary record. To this end, compound-specific radiocarbon analysis has been instrumental in shedding light on the turnover, age, and sources of a range of biomarkers embedded within complex environmental matrices. However, despite their foundational importance for life and their omnipresence throughout geologic space and time, the biogeochemical cycling of amino acids remains largely unexplored. Here, we discuss the potential of using amino acid-specific radiocarbon to deepen our knowledge of the biogeochemistry of food webs and sedimentary organic carbon.

Bodnar, R.J., Frezzotti, M.L., 2020. Microscale chemistry: Raman analysis of fluid and melt inclusions. Elements 16, 93-98.


Raman spectroscopy is a commonly applied nondestructive analytical technique for characterizing fluid and melt inclusions. The exceptional spatial resolution (~1 µm) and excellent spectral resolution (≤1 cm−1) permits the characterization of micrometer-scale phases and allows quantitative analyses based on Raman spectral features. Data provided by Raman analysis of fluid and melt inclusions has significantly advanced our understanding of complex geologic processes, including preeruptive volatile contents of magmas, the nature of fluids in the deep crust and upper mantle, the generation and evolution of methane-bearing fluids in unconventional hydrocarbon reservoirs. Anticipated future advances include the development of Raman mass spectroscopy and the use of Raman to monitor reaction progress in synthetic and natural fluid inclusion microreactors.

Bojesen-Koefoed, J.A., Alsen, P., Bjerager, M., Hovikoski, J., Ineson, J., Nytoft, H.P., Nøhr-Hansen, H., Petersen, H.I., Pilgaard, A., Vosgerau, H., 2020. A mid-Cretaceous petroleum source-rock in the North Atlantic region? Implications of the Nanok-1 fully cored borehole, Hold with Hope, northeast Greenland. Marine and Petroleum Geology 117, 104414.


The Cenomanian–Turonian transition includes the youngest of the two so-called Cretaceous Oceanic Anoxic Events, sometimes also referred to as the “Bonarelli Event”. This is an interval of global deposition of organic-rich oceanic deposits, including some of the most prolific petroleum source rocks of the World. However, in the greater North Atlantic realm, little direct evidence of notable volumes of rich Cenomanian–Turonian petroleum source rocks exists. As part of a major study of the Cretaceous succession in northeast Greenland between 2009 and 2012, a fully cored borehole (Nanok-1) on eastern Hold with Hope was drilled to penetrate a poorly or non-exposed stratigraphic succession including the Cenomanian–Turonian transition. The Nanok-1 penetrated 160.5 m of Cenomanian to Campanian clastic deposits and terminated at a TD of 168.35 m in an igneous intrusion. Although none of the deposits penetrated qualify as a petroleum source rock, a downwards increasing trend in petroleum source potential starting at c. 100m hint at the existence of such rocks at levels deeper than the TD of the well. The downwards increasing trend in petroleum generation potential is curtailed by maturation from c. 140m, but assuming the trend would have prevailed, were it not for the intrusion, the presence of at least a marginal source rock would be expected at the level of the sill and deeper. The presumed existence of petroleum source rocks below the TD of the borehole is supported by the presence of marked oil staining in sandstones (i.e. migrated petroleum) at shallower levels of the drilled succession. The hopane and sterane distributions and stable carbon isotopic compositions and age-specific nordiacholestane ratios of the oil stains are compatible with an origin from the Cretaceous succession, while the Jurassic can be ruled out. The oil stains recorded were probably generated from a marine shale source rock of Cretaceous age, containing a significant proportion of terrigenous organic matter. The possible presence of at least one marginal petroleum source rock in the mid-Cretaceous succession at the Nanok-1 location has implications for the exploration potential of the conjugate margin. Hence, comparison of sediment accumulation histories of the Møre and Vøring basins and northeast Greenland suggests that the presumed source rock was deposited before the accommodation space at the Nanok-1 location was exhausted. Thus, coeval sediment starvation and deposition of more condensed and richer petroleum source rocks may have prevailed in the offshore basins to the east during the mid-late Cenomanian. This potential source rock will thus be slightly older than Cenomanian–Turonian source rocks that are important worldwide.

Bond, D.P.G., Wignall, P.B., Grasby, S.E., 2020. The Capitanian (Guadalupian, Middle Permian) mass extinction in NW Pangea (Borup Fiord, Arctic Canada): A global crisis driven by volcanism and anoxia. GSA Bulletin 132, 931-942.

https://doi.org/10.1130/B35281.1

Until recently, the biotic crisis that occurred within the Capitanian Stage (Middle Permian, ca. 262 Ma) was known only from equatorial (Tethyan) latitudes, and its global extent was poorly resolved. The discovery of a Boreal Capitanian crisis in Spitsbergen, with losses of similar magnitude to those in low latitudes, indicated that the event was geographically widespread, but further non-Tethyan records are needed to confirm this as a true mass extinction. The cause of this crisis is similarly controversial: While the temporal coincidence of the extinction and the onset of volcanism in the Emeishan large igneous province in China provides a clear link between those phenomena, the proximal kill mechanism is unclear. Here, we present an integrated fossil, pyrite framboid, and geochemical study of the Middle to Late Permian section of the Sverdrup Basin at Borup Fiord, Ellesmere Island, Arctic Canada. As in Spitsbergen, the Capitanian extinction is recorded by brachiopods in a chert/limestone succession 30–40 m below the Permian-Triassic boundary. The extinction level shows elevated concentrations of redox-sensitive trace metals (Mo, V, U, Mn), and contemporary pyrite framboid populations are dominated by small individuals, suggestive of a causal role for anoxia in the wider Boreal crisis. Mercury concentrations—a proxy for volcanism—are generally low throughout the succession but are elevated at the extinction level, and this spike withstands normalization to total organic carbon, total sulfur, and aluminum. We suggest this is the smoking gun of eruptions in the distant Emeishan large igneous province, which drove high-latitude anoxia via global warming. Although the global Capitanian extinction might have had different regional mechanisms, like the more famous extinction at the end of the Permian, each had its roots in large igneous province volcanism.

Borji, H., Ayoub, G.M., Al-Hindi, M., Malaeb, L., Hamdan, H.Z., 2020. Nanotechnology to remove polychlorinated biphenyls and polycyclic aromatic hydrocarbons from water: a review. Environmental Chemistry Letters 18, 729-746.

https://doi.org/10.1007/s10311-020-00979-x

Persistent pollutants cause adverse effects to human and environmental health. Most polychlorinated biphenyls (PCB) and polycyclic aromatic hydrocarbons (PAH) are toxic and stable in the environment, yet their removal is rarely targeted by conventional remediation methods. Alternatively, nanotechnology appears promising for contaminant removal. Indeed, nanomaterials have unique size-dependent properties due to their high specific surface area. Nanomaterials also possess fast dissolution properties, strong sorption, supermagnetic characteristics and quantum confinement. This manuscript reviews the application of nanotechnologies for the removal of PCB and PAH from contaminated water sources.

Bottos, E.M., Laughlin, D.C., Herbold, C.W., Lee, C.K., McDonald, I.R., Cary, S.C., 2020. Abiotic factors influence patterns of bacterial diversity and community composition in the Dry Valleys of Antarctica. FEMS Microbiology Ecology 96, fiaa042.

https://doi.org/10.1093/femsec/fiaa042

The Dry Valleys of Antarctica are a unique ecosystem of simple trophic structure, where the abiotic factors that influence soil bacterial communities can be resolved in the absence of extensive biotic interactions. This study evaluated the degree to which aspects of topographic, physicochemical and spatial variation explain patterns of bacterial richness and community composition in 471 soil samples collected across a 220 square kilometer landscape in Southern Victoria Land. Richness was most strongly influenced by physicochemical soil properties, particularly soil conductivity, though significant trends with several topographic and spatial variables were also observed. Structural equation modeling (SEM) supported a final model in which variation in community composition was best explained by physicochemical variables, particularly soil water content, and where the effects of topographic variation were largely mediated through their influence on physicochemical variables. Community dissimilarity increased with distance between samples, and though most of this variation was explained by topographic and physicochemical variation, a small but significant relationship remained after controlling for this environmental variation. As the largest survey of terrestrial bacterial communities of Antarctica completed to date, this work provides fundamental knowledge of the Dry Valleys ecosystem, and has implications globally for understanding environmental factors that influence bacterial distributions.

Bouwmeester, R., Martens, L., Degroeve, S., 2020. Generalized calibration across liquid chromatography setups for generic prediction of small-molecule retention times. Analytical Chemistry 92, 6571-6578.


Accurate prediction of liquid chromatographic retention times from small-molecule structures is useful for reducing experimental measurements and for improved identification in targeted and untargeted MS. However, different experimental setups (e.g., differences in columns, gradients, solvents, or stationary phase) have given rise to a multitude of prediction models that only predict accurate retention times for a specific experimental setup. In practice this typically results in the fitting of a new predictive model for each specific type of setup, which is not only inefficient but also requires substantial prior data to be accumulated on each such setup. Here we introduce the concept of generalized calibration, which is capable of the straightforward mapping of retention time models between different experimental setups. This concept builds on the database-controlled calibration approach implemented in PredRet and fits calibration curves on predicted retention times instead of only on observed retention times. We show that this approach results in substantially higher accuracy of elution-peak prediction than is achieved by setup-specific models.

Bozhko, N.A., 2020. Tectonic inheritance and predetermination in supercontinental cyclicity. Moscow University Geology Bulletin 75, 7-12.

https://doi.org/10.3103/S0145875220010032

The issues of tectonic inheritance in supercontinental cyclicity are considered on the basis of the contemporary domestic and foreign studies, as well as those of the author. Examples of repeated manifestations of Wilson cycles within the specific zones, as well as the paleomagnetic data on the similarity of reconstructions for supercontinents of different ages are provided. It is shown that the

deep causes that predetermine this inheritance are related to weakened zones of the lithospheric mantle that control the assembly and breakup of supercontinents.

Brailsford, F.L., Glanville, H.C., Wang, D., Golyshin, P.N., Johnes, P.J., Yates, C.A., Jones, D.L., 2020. Rapid depletion of dissolved organic sulphur (DOS) in freshwaters. Biogeochemistry 149, 105-113.

https://doi.org/10.1007/s10533-020-00669-4

Sulphur (S) is a key macronutrient for all organisms, with similar cellular requirements to that of phosphorus (P). Studies of S cycling have often focused on the inorganic fraction, however, there is strong evidence to suggest that freshwater microorganisms may also access dissolved organic S (DOS) compounds (e.g. S-containing amino acids). The aim of this study was to compare the relative concentration and depletion rates of organic 35S-labelled amino acids (cysteine, methionine) with inorganic S (Na2

35SO4) in oligotrophic versus mesotrophic river waters draining from low nutrient input and moderate nutrient input land uses respectively. Our results showed that inorganic SO4

2− was present in the water column at much higher concentrations than free amino acids. In contrast to SO4

2−, however, cysteine and methionine were both rapidly depleted from the mesotrophic and oligotrophic waters with a halving time < 1 h. Only a small proportion of the DOS removed from solution was mineralized and excreted as SO4

2− (< 16% of the total taken up) suggesting that the DOS could be satisfying a demand for carbon (C) and S. In conclusion, even though inorganic S was abundant in freshwater, it appears that the aquatic communities retained the capacity to take up and assimilate DOS.

Brandon, M., Landais, A., Duchamp-Alphonse, S., Favre, V., Schmitz, L., Abrial, H., Prié, F., Extier, T., Blunier, T., 2020. Exceptionally high biosphere productivity at the beginning of Marine Isotopic Stage 11. Nature Communications 11, 2112.

https://doi.org/10.1038/s41467-020-15739-2

Significant changes in atmospheric CO2 over glacial-interglacial cycles have mainly been attributed to the Southern Ocean through physical and biological processes. However, little is known about the contribution of global biosphere productivity, associated with important CO2 fluxes. Here we present the first high resolution record of Δ17O of O2 in the Antarctic EPICA Dome C ice core over Termination V and Marine Isotopic Stage (MIS) 11 and reconstruct the global oxygen biosphere productivity over the last 445 ka. Our data show that compared to the younger terminations, biosphere productivity at the end of Termination V is 10 to 30 % higher. Comparisons with local palaeo observations suggest that strong terrestrial productivity in a context of low eccentricity might explain this pattern. We propose that higher biosphere productivity could have maintained low atmospheric CO2 at the beginning of MIS 11, thus highlighting its control on the global climate during Termination V.

Broadley, L., Schofield, N., Jolley, D., Howell, J., Underhill, J.R., 2020. UK Rockall prospectivity: re-awakening exploration in a frontier basin. Petroleum Geoscience 26, 247.


The UK Rockall, located to the west of Scotland and the Hebrides, is a frontier petroleum-bearing basin. Exploratory drilling in the basin took place over a quarter of a century (1980–2006), during which time a total of 12 wells were drilled, leading to the discovery of a single, subcommercial gas accumulation. We argue that the basin, which has seen no drilling activity for more than a decade, has not been sufficiently tested by the existing well stock. We examine the reasons for the absence of key Jurassic source rocks in the UK Rockall wells, which are widely distributed elsewhere on the UK Continental Shelf (UKCS), and argue that their absence in the wells does not preclude their existence in the basin at large. An evaluation of the Permian–Early Eocene successions, based upon the seismic interpretation of new 2D seismic data, has been integrated with legacy data and regional evidence to establish the potential for source, reservoir and sealing elements within each interval. Finally, we look at the future for exploration in the UK Rockall and suggest a way forward in the drilling of a new joint governmental–industry test well that may help to unlock the exploration potential of this under-explored, yet prospective, basin.Thematic collection: This article is part of the Under-explored plays and frontier basins of the UK continental shelf collection available at: https://www.lyellcollection.org/cc/under-explored-plays-and-frontier-basins-of-the-uk-continental-shelf

Brown, D.M., Camenzuli, L., Redman, A.D., Hughes, C., Wang, N., Vaiopoulou, E., Saunders, D., Villalobos, A., Linington, S., 2020. Is the Arrhenius-correction of biodegradation rates, as recommended through REACH guidance, fit for environmentally relevant conditions? An example from petroleum biodegradation in environmental systems. Science of The Total Environment 732, 139293.


Biodegradation is a major determinant of chemical persistence in the environment and an important consideration for PBT and environmental risk assessments. It is influenced by several environmental factors including temperature and microbial community structure. According to REACH guidance, a temperature correction based on the Arrhenius equation is recommended for chemical persistence data not performed at the recommended EU mean surface water temperature. Such corrections, however, can lead to overly conservative P/vP assessments. In this paper, the relevance of this temperature correction is assessed for petroleum hydrocarbons, using measured surface water (marine and freshwater) degradation half-time (DT50) and degradation half-life (HL) data compiled from relevant literature. Stringent screening criteria were used to specifically select data from biodegradation tests containing indigenous microbes and conducted at temperatures close to their ambient sampling temperature. As a result, ten independent studies were identified, with 993 data points covering 326 hydrocarbon constituents. These data were derived from tests conducted with natural seawater, or freshwater, at temperatures ranging from 5 to 21 °C. Regressions were performed on the full hydrocarbon dataset and on several individual hydrocarbons. The results were compared to the trnd as predicted by the Arrhenius equation and using the activation energy (Ea) as recommend in the REACH Guidance. The comparison shows that the correction recommended in REACH Guidance over predicts the effect of temperature on hydrocarbon biodegradation. These results contrast with temperature manipulated inocula where the test temperature is different from the ambient sampling temperature. In these manipulated systems, the effect of temperature follows the Arrhenius equation more closely. In addition, a more striking effect of temperature on the lag phase was observed with longer lag phases more apparent at lower temperatures. This indicates that the effect of temperature may indeed be even lower when considering hydrocarbon biodegradation without the initial lag phase.

Bryant, W.L., Camilli, R., Fisher, G.B., Overton, E.B., Reddy, C.M., Reible, D., Swarthout, R.F., Valentine, D.L., 2020. Harnessing a decade of data to inform future decisions: Insights into the ongoing hydrocarbon release at Taylor Energy's Mississippi Canyon Block 20 (MC20) site. Marine Pollution Bulletin 155, 111056.


The release of oil and gas at Mississippi Canyon Block 20 into the Gulf of Mexico has vexed response officials since 2004 when a regional seafloor failure toppled the Taylor Energy Company platform. Despite the completion of nine intervention wells, releases continue from the seafloor, mostly captured by a recently installed containment system. Toward informing resolution, this work applies chemical forensic and statistical analyses to surface sheens, sediments, and reservoir oil samples. Our results indicate sheens are chemically heterogeneous, contain remnant synthetic hydrocarbons likely discharged from well interventions prior to 2012, and require mixing of multiple chemically-distinct oil groups to explain observed variability in diagnostic ratios. Given the respite and opportunity afforded by containment we suggest leveraging ongoing collection activities to assess release dynamics, as well as engaging the National Academies of Science, Engineering, and Medicine, to evaluate potential solutions, associated risks, and to consider policy ramifications.

Buesseler, K.O., Boyd, P.W., Black, E.E., Siegel, D.A., 2020. Metrics that matter for assessing the ocean biological carbon pump. Proceedings of the National Academy of Sciences 117, 9679-9687.

http://www.pnas.org/content/117/18/9679.abstract

The biological carbon pump (BCP) comprises wide-ranging processes that set carbon supply, consumption, and storage in the oceans’ interior. It is becoming increasingly evident that small changes in the efficiency of the BCP can significantly alter ocean carbon sequestration and, thus, atmospheric CO2 and climate, as well as the functioning of midwater ecosystems. Earth system models, including those used by the United Nation’s Intergovernmental Panel on Climate Change, most often assess POC (particulate organic carbon) flux into the ocean interior at a fixed reference depth. The extrapolation of these fluxes to other depths, which defines the BCP efficiencies, is often executed using an idealized and empirically based flux-vs.-depth relationship, often referred to as the “Martin curve.” We use a new compilation of POC fluxes in the upper ocean to reveal very different patterns in BCP efficiencies depending upon whether the fluxes are assessed at a fixed reference depth or relative to the depth of the sunlit euphotic zone (Ez). We find that the fixed-depth approach underestimates BCP efficiencies when the Ez is shallow, and vice versa. This adjustment alters regional assessments of BCP efficiencies as well as global carbon budgets and the interpretation of prior BCP studies. With several international studies recently underway to study the ocean BCP, there are new and unique opportunities to improve our understanding of the mechanistic controls on BCP efficiencies. However, we will only be able to compare results between studies if we use a common set of Ez-based metrics.

Bulgin, C.E., Merchant, C.J., Ferreira, D., 2020. Tendencies, variability and persistence of sea surface temperature anomalies. Scientific Reports 10, 7986.

https://doi.org/10.1038/s41598-020-64785-9

Quantifying global trends and variability in sea surface temperature (SST) is of fundamental importance to understanding changes in the Earth’s climate. One approach to observing SST is via remote sensing. Here we use a 37-year gap-filled, daily-mean analysis of satellite SSTs to quantify SST trends, variability and persistence between 1981–2018. The global mean warming trend is 0.09 K per decade globally, with 95% of local trends being between −0.1 K and + 0.35 K. Excluding perennial sea-ice regions, the mean warming trend is 0.11 K per decade. After removing the long-term trend we calculate the SST power spectra over different time periods. The maximum variance in the SST power spectra in the equatorial Pacific is 1.9 K2 on 1–5 year timescales, dominated by ENSO processes. In western boundary currents characterised by an intense mesoscale activity, SST power on sub-annual timescales dominates, with a maximum variance of 4.9 K2. Persistence timescales tend to be shorter in the summer hemisphere due to the shallower mixed layer. The median short-term persistence length is 11–14 days, found over 71–79% of the global ocean area, with seasonal variations. The mean global correlation between monthly SST anomalies with a three-month time-lag is 0.35, with statistically significant correlations over 54.0% of the global oceans, and notably in the northern and equatorial Pacific, and the sub-polar gyre south of Greenland. At six months, the mean global SST anomaly correlation falls to 0.18. The satellite data record enables the detailed characterisation of temporal changes in SST over almost four decades.

Burrows, L.C., Haeri, F., Cvetic, P., Sanguinito, S., Shi, F., Tapriyal, D., Goodman, A., Enick, R.M., 2020. A literature review of CO2, natural gas, and water-based fluids for enhanced oil recovery in unconventional reservoirs. Energy & Fuels 34, 5331-5380.


Primary oil recovery from fractured unconventional formations, such as shale or tight sands, is typically less than 10%. The development of an economically viable enhanced oil recovery (EOR) technique applicable to unconventional liquid reservoirs (ULRs) would lead to tremendous increases in domestic oil production. Although injection techniques such as waterflooding and CO2 EOR have proven profitable in conventional formations for decades, EOR in ULRs presents a far more difficult challenge. The extremely low permeability and mixed wettability of unconventional formations are the foremost obstacles to success. Because of the challenges associated with water-based EOR techniques (a.k.a., chemical EOR) in shale, several nonaqueous injection fluids have been considered, including CO2, natural gas, and (to a lesser degree) nitrogen. All these fluids have significantly lower viscosities than water, allowing them to more easily penetrate shale nanopores. Unlike water, they also each possess some degree of miscibility with oil, which enables the gas to extract oil through a combination of mechanisms. Based on laboratory-scale experimentation, CO2 and rich natural gas (methane-rich natural gas containing high concentrations of ethane, propane, and butane) are the most promising EOR fluids. The interpretation of results from field tests in the Bakken and Eagle Ford formations have been complicated by interference of frac-hits or well-bashing caused by hydraulic fracturing at nearby wells. In this review we cover mechanisms, laboratory experiments, numerical simulations, and field tests involving high-pressure CO2, natural gas, ethane, nitrogen, and water.

Bytingsvik, J., Parkerton, T.F., Guyomarch, J., Tassara, L., LeFloch, S., Arnold, W.R., Brander, S.M., Volety, A., Camus, L., 2020. The sensitivity of the deepsea species northern shrimp (Pandalus borealis) and the cold-water coral (Lophelia pertusa) to oil-associated aromatic compounds, dispersant, and Alaskan North Slope crude oil. Marine Pollution Bulletin 156, 111202.


This study investigated the sensitivity of two deepsea species using mortality of northern shrimp (Pandalus borealis) and polyp activity of stony coral (Lophelia pertusa) to dispersant, Corexit 9500 and aromatic hydrocarbons (toluene, 2-methylnaphthalene, phenanthrene) in 96-h tests. Resulting hydrocarbon toxicity data were fit to the Target Lipid Model to generate predictive models and determine species sensitivity. Toxicity of chemically enhanced water accommodated fractions of Alaskan North Slope crude oil (ANS-oil) was also investigated with shrimp using nominal loading, total petroleum hydrocarbons and biomimetic extraction (BE) as oil exposure metrics. Coral were more sensitive to dispersant than shrimp while similar sensitivity was observed for hydrocarbons. Study and literature findings indicate deepsea species exhibit acute sensitivities to dispersant, hydrocarbons and oil that are comparable to pelagic species. Results support use of passive sampling methods to quantify dissolved oil for interpreting oil toxicity tests and suggest models for predicting time-dependence of toxicity warrant re-evaluation.


https://doi.org/10.1029/2019JD032253

Organosulfates (OSs) have recently been observed to be a potentially important constituent of secondary organic aerosol (SOA); however, their molecular characterization in highly polluted atmospheres has not been probed in detail. This study thoroughly presents the characterization of OSs in polluted air and demonstrates their seasonal and diurnal variations, formation mechanisms, and contributions to organic aerosol. Atmospheric PM2.5 samples were collected from an urban Shanghai site across the winter and summer of 2017. OSs were characterized by ultra high‐ ‐performance liquid chromatography (UHPLC) coupled with Orbitrap mass spectrometry (MS). Based on exact mass formulae in conjunction with previous chamber studies, hundreds of sulfur‐containing compounds were tentatively identified as OSs. The number and abundance of OSs increased significantly during pollution episodes. The OSs in the clean aerosol samples were dominant in biogenic products, whereas the OSs in the polluted winter samples had distinctive anthropogenic characteristics. Aromatics and long chain alkanes from anthropogenic emissions ‐might be their precursors. By using synthesized standards, the total concentrations of 14 quantified OSs ranged 21.6–161 ng m−3 in summer and 5.85–84.3 ng m−3 in winter, respectively. Among these OSs, glycolic acid sulfate was the most abundant species (1.13–122 ng m−3). Further analysis of their seasonal and diurnal variations suggests possible contributions from multiple formation mechanisms, including acid catalyzed and NO‐ 3 initiated oxidation reactions. Our results highlight ‐that increased anthropogenic pollutant emissions (e.g., NOx and SO2) can significantly enhance the SOA burden in biogenically influenced urban areas.

Camillo, E., Quadros, J.P., Santarosa, A.C.A., Costa, K.B., Toledo, F.A.L., 2020. An abrupt cooling event recorded around 73 kyr in western South Atlantic. Quaternary International 542, 80-87.


This paper presents the record of sea surface temperature and planktonic foraminifera cold species for the last 130 kyr of a deep sea marine piston core (GL-854) from western South Atlantic. Our data shows a prominent and consistent feature around 73 kyr when an abrupt drop in sea surface temperature, both artificial neural network and oxygen isotope-based, was recorded. Additionally, our oxygen isotope curve presents a positive excursion and two cold-water planktonic foraminifera (Globoconella inflata and Neogloboquadrina incompta) remarkably increased their abundances. The benthic oxygen isotope record did not indicate any change while planktonic indicators were intensely disturbed. This cooling episode should be explained by a strong and abrupt mechanism able to promptly affect the surface ocean but not the deep ocean. It seems to be one of the coldest intervals during the last 130 kyr. Here, we discuss some hypothesis for this abrupt cooling recorded in the South Atlantic, including the speculative climatic impact of Toba super-eruption.

Canfield, D.E., Knoll, A.H., Poulton, S.W., Narbonne, G.M., Dunning, G.R., 2020. Carbon isotopes in clastic rocks and the Neoproterozoic carbon cycle. American Journal of Science 320, 97-124.

http://www.ajsonline.org/content/320/2/97.abstract

It has been proposed that isotopically light inorganic carbon precipitated diagenetically in clastic sediments can explain the large carbon isotopic excursions recorded in Neoproterozoic carbonates. To date, however, the data needed to test this hypothesis have been limited. Here we report the analysis of ca. 540 clastic sedimentary rocks, including shales, siltstones, sandstones and tillites, that span the second half of the Neoproterozoic Era. A diagenetic carbon isotopic overprint does indeed occur in many of the samples; however, when we include our analyses in a carbon isotope mass balance model, they produce only a small effect on mass balance model results. Thus, clastic sedimentary rocks were not a major sink for 13C-depleted carbonate during the Neoproterozoic Era. These results do, however, produce a more accurate carbon mass balance, pointing to a high proportion of total organic carbon burial, compared to total carbon burial, during the late Tonian, Cryogenian, and late Ediacaran Periods. This result suggests a vigorous release of oxygen to the atmosphere. The clastic carbonate record also offers a chemostratigraphic tool. For example, we observe an isotope trend in clastic-hosted carbonates of the Isaac Formation, Windermere Supergroup, that strongly resembles the Shuram-Wonoka isotope anomaly, allowing us to place this previously undated section in a temporal context. We also find isotope trends in the fossiliferous and radiometrically well-dated sedimentary rocks of the Avalon Peninsula, Newfoundland, that may also reflect the Shuram-Wonoka anomaly. If correct, this constrains the timing of the Shuram event, suggesting that it began after 571 Ma and ended before 562 Ma, with the most extreme isotopic values lying well within those bounds.

Cao, J., Rao, Z., Shi, F., Jia, G., 2020. Ice formation on lake surfaces in winter causes warm-season bias of lacustrine brGDGT temperature estimates. Biogeosciences 17, 2521-2536.

https://www.biogeosciences.net/17/2521/2020/

It has been frequently found that lacustrine branched glycerol dialkyl glycerol tetraethers (brGDGT)-derived temperatures are warm-season-biased relative to measured mean annual air temperature (AT) in the middle to high latitudes, the mechanism of which, however, is not very clear. Here, we investigated the brGDGTs from catchment soils, suspended particulate matter (SPM) and surface sediments in different water depths in Gonghai Lake in northern China to explore this question. Our

results showed that the brGDGT distribution in sediments resembled that in the SPM but differed from the surrounding soils, suggesting a substantial aquatic origin of the brGDGTs in the lake. Moreover, the increase in brGDGT content and decrease in methylation index with water depth in sediments suggested more contribution of aquatic brGDGTs produced from deep or bottom waters. Therefore, established lake-specific calibrations were applied to estimate local mean annual AT. As usual, the estimates were significantly higher than the measured mean annual AT. However, they were similar to (and thus actually reflected) the mean annual lake water temperature (LWT). Interestingly, the mean annual LWT is close to the measured mean warm-season AT, thus suggesting that the apparent warm-season bias of lacustrine brGDGT-derived temperatures could be caused by the discrepancy between AT and LWT. In our study region, ice forms at the lake surface during winter, leading to isolation of the underlying lake water from air and hence higher LWT than AT, while LWT basically follows AT during warm seasons when ice disappears. Therefore, we think that lacustrine brGDGTs actually reflected the mean annual LWT, which is higher than the mean annual AT in our study location. Since the decoupling between LWT and AT in winter due to ice formation is a universal physical phenomenon in the middle to high latitudes, we propose this phenomenon could be also the reason for the widely observed warm-season bias of brGDGT-derived temperatures in other seasonally surface ice-forming lakes, especially in shallow lakes.

Cao, Y., Han, H., Guo, C., Pang, P., Ding, Z.-g., Gao, Y., 2020. Influence of extractable organic matters on pore structure and its evolution of Chang 7 member shales in the Ordos Basin, China: Implications from extractions using various solvents. Journal of Natural Gas Science and Engineering 79, 103370.


To explore the effect of extractable organic matters on pore structure and its evolution of shales, a suite of lacustrine Chang 7 shales with various maturities from the Ordos Basin, China were extracted using acetone, tetrahydrofuran (THF), carbon disulfide (CS2), and benzene, respectively. Fractionations of extracted organic matters were employed to examine group components. Low-pressure nitrogen and carbon dioxide adsorptions were used to characterize the pore structure before and after extraction.

The results showed that the asphaltene comes to be significantly extractable in the presence of THF, which may be attributed to that THF has remarkable ability of decreasing the interaction between asphaltene and shale matrix. The micropores with a diameter ranging from 0.3 nm to 0.86 nm in the samples with high TOC content (>15.6%) clearly increased after extractions, thus soluble organic matters of shales may be mainly stored in the micropores with the diameter range above. On the contrary, mesopores have not obvious changes after extractions. Comparably, CS2 has greater access to release micropores and mesopores than other solvents, which may be related to that CS2 is easier to enter the most inner spots due to its smallest dynamic diameter and strip molecular structure. THF has greater access to release micropores due to its ability of reducing molecular size of asphaltene fraction and dissolving abundant asphaltene with small molecular diameter. TOC exerts a stronger control on mesopores and micropores than minerals, mesopores and micropores mainly exist in organic matters of the studied samples. Effect of soluble organic matters on pore structure was much less than maturity, suggesting the generation and cracking of liquid hydrocarbons aren't the major influence factor of evolution of porosity in studied samples.

Capper, D., 2020. The search for microbial Martian life and American Buddhist ethics. International Journal of Astrobiology 19, 244-252.

https://doi.org/10.1017/S1473550419000296

Multiple searches hunt for extraterrestrial life, yet the ethics of such searches in terms of fossil and possible extant life on Mars have not been sufficiently delineated. In response, in this essay, I propose a tripartite ethic for searches for microbial Martian life that consists of default non-harm towards potential living beings, default non-harm to the habitats of potential living beings, but also responsible, restrained scientific harvesting of some microbes in limited transgression of these default non-harm modes. Although this multifaceted ethic remains secular and hence adaptable to space research settings, it arises from both a qualitative analysis of authoritative Buddhist scriptural ethics as well as the quantified ethnographic survey voices of contemporary American Buddhists. The resulting tripartite ethic, while developed for Mars, contains ramifications for the study of microbes on Earth and further retains application to other research locations in our Solar system.

Caro Gonzalez, L.D., Mastalerz, M., Filho, J.G.M., 2020. Application of organic facies and biomarkers in characterization of paleoenvironmental conditions and maturity of sediments from the Codó Formation in the west-central part of the São Luís Basin, Brazil. International Journal of Coal Geology 225, 103482.


Paleoenvironmental conditions of the sediments of the Cretaceous Codó Formation in Brazil are still being debated. The main point of controversy is whether they were deposited in a strictly marine environment or under lacustrine conditions of varying salinity. In this study, organic facies and biomarker analyses were performed on samples from the Codó Formation in the São Luís Basin, northwest Brazil, to reconstruct the paleoenvironmental conditions, the origin, and the thermal maturity of the organic matter. Four types of palynofacies associations (PI – amorphous organic matter, PII – amorphous organic matter+sporomorphs, PIII – phytoclasts, and IV – marine palynomorphs) were identified. The total organic carbon (TOC) content exhibits a strong correlation (ρ = 0.75, p < .05) with amorphous organic matter (AOM) content suggesting that AOM is the main factor controlling TOC in the stratigraphic section, and that increases in the AOM contribution were associated with an increase in the water column and expansion of reducing conditions that favored organic matter preservation. The TOC and total sulfur (TS) plots suggest that there were salinity variations in the depositional environment. The identification of marine palynomorphs (Subtilisphaera genus) are indicative of several local marine incursions. The n-alkane distribution (unimodal and bimodal) confirmed the presence of strong input of higher plant components (phytoclast-dominated Palynofacies III) and the bacterially-reworked organic material (Palynofacies I/II). The aquatic terrestrial (ATR), terrigenous/aquatic (TAR), and proxy for aquatic macrophytes (Paq) ratios suggest autochthonous (Palynofacies I and II) and allochthonous (Palynofacies III) organic matter, and eutrophic and submerged-floating plants. Based on palynofacies associations and biomarkers we conclude that the depositional environment ranged from an anoxic/reducing to dysoxic/oxic within a closed-lacustrine system having a stratified water column. High evaporation rates favored a decrease in the water column and an increase in salinity, allowing the precipitation of salt by evaporation (CaCO3 > 80%). The thermal maturity indicators including vitrinite reflectance (%Ro), spore color index (SCI), Ts/(Ts + Tm) ratios, and C29 20S/(20S + 20R) and C29 ββ/(αα + ββ) indicate that the organic matter is immature to marginally mature.

Cawood, P.A., 2020. Metamorphic rocks and plate tectonics. Science Bulletin 65, 968-969.


Our planet is a dynamic system whose evolution has been controlled by complex feedbacks between its solid and surficial components (e.g., mantle, crust, oceans, atmosphere and biosphere), across a range of temporal and spatial scales. On the modern Earth, these interactions are controlled by plate tectonics, which involves the horizontal motion of surface plates (i.e., continental drift and sea-floor spreading) across a series of continuous linked boundaries [1]. Continental drift is effected by moving of rigid lithosphere (crust and the uppermost mantle) over ductile asthenosphere. While lithosphere is generated along divergent plate boundaries such as mid-ocean ridges, it is recycled back into the asthenosphere along convergent plate boundaries such as subduction zones. This generation and recycling of lithosphere via plate tectonics is referred to as top down tectonics (Fig. 1). Plate tectonics is essentially a mechanism for dissipating heat from the planet’s interior to space. However, the early Earth (ca. greater than 2.5 billion years ago) is known to have been considerably hotter with mantle temperatures estimated to have been over 200 °C higher than today (Fig. 1) [2], [3]. This has led to much discussion as to the viability of plate tectonics under such conditions and thus, to how long it has been the modus operandi of Earth behaviour. Some suggest it may have operated since the Hadean eon, which covers the first 500 million years following the Earth’s accretion from the solar nebula some 4.55 billion years ago, whereas others argue that it only commenced in the Neoproterozoic, the period from 1000 to 540 million years ago [4], [5]. Proposed pre-plate tectonic regimes involve a fixed or episodically mobile lithosphere, often referred to as a stagnant-lid, in which the convecting mantle egresses heat through a combination of conduction, mantle plume-focused igneous activity, and periodic catastrophic overturn of the lithosphere [6], [7]. Mantle plumes which derive from deep within the Earth are sometimes referred to as bottom up tectonics and with a potential inverse relationship between top down and bottom up tectonics through Earth history (Fig. 1). Given the fundamental importance of plate tectonics in controlling the Earth system, the level of uncertainty as to when it commenced, which ranges over some 80% of the planet’s existence, is remarkable. Reasons for this uncertainty include the incompleteness of the rock archive in deep time, differences in the criteria used to infer the existence of both plate tectonic and pre-plate tectonic regimes on the early Earth, and disagreements in the significance and interpretation of available data [1].

Zheng and Zhao [8] propose a resolution to the uncertainty in the start date of plate tectonics by arguing that it has been operating for significant component of Earth history, but that its character has changed over time and that some features characteristic of plate tectonics today were different in the past. They propose that plate tectonics as recognized today, involving rigid plate boundaries and cold subduction, has only been active since the Neoproterozoic, but that prior to this time and extending since sometime in the Eoarchean (4–3.6 Ga) the higher internal heat flux of Earth resulted in a form of plate tectonics involving ductile plate boundaries and warm subduction. Thus, they argue that changing mantle temperatures led to differences in the character of plate margins due to changing rock rheology. They base their arguments on the distribution of metamorphic facies series through time [9]. Mineral assemblages preserved within metamorphic rocks provide a record of the temperature and pressure conditions that they have experienced during their burial. These conditions show a spatial linkage to plate tectonic setting [10] as well as a temporal relationship related to evolving thermal gradients [8], [9]. The pressure and temperature conditions that a metamorphic rock experiences, as recorded in preserved mineral assemblages can be expressed as

their thermobaric ratio, which represents a proxy for the transient geotherm recorded by the rock at the peak of metamorphism. Three thermobaric regimes are recognized: high T/P, intermediate T/P, and low T/P [9]. They are basically responsible for three types of metamorphic facies series [8]. High and intermediate T/P conditions first occur in the rock record in the Eoarchean (4.0–3.6 Ga), whereas low T/P metamorphic assemblages do not become widespread until the Neoproterozoic and Phanerozoic (<1.0 Ga). The low and intermediate thermal gradients are attributed to subduction and collisional settings associated with active compression for convergent plate interaction, whereas the high thermal gradients are ascribed to active extension in the hinterland of the overriding plate (e.g., back-arc rifts) as well as in continental rifts [8]. Zheng and Zhao [8] propose that the paired metamorphic high and intermediate T/P assemblages require a form of plate tectonics in which the higher mantle heat flux resulted in ductile plate boundaries. By the Neoproterozoic the mantle temperature had cooled sufficiently, probably to less than 100 °C hotter than today (Fig. 1), enabling the formation of low T/P metamorphic assemblages with relatively narrow plate margins. Zheng and Zhao [8] provide an important framework for understanding the role of plate tectonics in creating the current Earth system, and this has resulted in the environment in which we live and the resources on which we depend.

Metamorphic assemblages and plate tectonic inferences drawn from them, such as those proposed by Zheng and Zhao [8], have to date largely been based on their temporal distribution. Although the present-day spatial distribution of data for the metamorphic assemblages is known, their spatial relationships at the time of formation is often difficult to establish due to subsequent tectonic disruption, which can result in the dispersal of once contiguous and temporally contemporaneous rock associations. Thus, we know that there are temporally paired metamorphic belts [8], [9] but equally important is the need to show that belts were (or were not) spatially paired. In this regard, thermomechanical models under inferred hotter Archean conditions provide a way of studying the temporal evolution and spatial distribution of pressure-temperature regimes under both plate tectonic and non-plate tectonic scenarios [11]. Furthermore, the contributions of vertical density driven motions, such as delamination of lithosphere and upwelling of asthenosphere during the evolving phases of plate tectonics, warrant ongoing evaluation.

References1. PA. Cawood, C.J. Hawkesworth, S.A. Pisarevsky, et al. Geological archive of the onset of plate

tectonics. Philos Trans R Soc A, 376 (2018), p. 201704052. C. Herzberg, K. Condie, J. Korenaga, Thermal history of the Earth and its petrological expression.

Earth Planet Sci Lett, 292 (2010), pp. 79-883. J. Ganne, X. Feng, Primary magmas and mantle temperatures through time. Geochem Geophys

Geosyst, 18 (2017), pp. 872-8884. M.D. Hopkins, T.M. Harrison, C.E. Manning, Constraints on Hadean geodynamics from mineral

inclusions in >4 Ga zircons.Earth Planet Sci Lett, 298 (2010), pp. 367-3765. R.J. Stern, Evidence from ophiolites, blueschists, and ultrahigh-pressure metamorphic terranes

that the modern episode of subduction tectonics began in Neoproterozoic time. Geology, 33 (2005), pp. 557-560

6. T. Gerya, Precambrian geodynamics: concepts and models. Gondwana Res, 25 (2014), pp. 442-463

7. H. Bédard, Stagnant lids and mantle overturns: implications for Archaean tectonics, magmagenesis, crustal growth, mantle evolution, and the start of plate tectonics.

Geosci Front, 9 (2018), pp. 19-49

8. Y.-F. Zheng, G. Zhao, Two styles of plate tectonics in Earth’s history. Sci Bull, 65 (2020), pp. 329-334

9. M. Brown, T. Johnson, Secular change in metamorphism and the onset of global plate tectonics. Am Mineral, 103 (2018), pp. 181-196

10. A. Miyashiro, Metamorphism and related magmatism in plate tectonics. Am J Sci, 272 (1972), pp. 629-656

11. F.A. Capitanio, O. Nebel, P.A. Cawood, et al., Reconciling thermal regimes and tectonics of the early Earth. Geology, 47 (2019), pp. 923-927

Cha, J.W., Park, S., 2020. Extraction of individual spectra from mixture data based on high-resolution 13C–13C NMR correlation spectrum and decode procedure. Analytical Chemistry 92, 7037-7044.


In NMR analysis of complex organic molecules, low natural abundance of 13C and the low resolution of two-dimensional (2D) experiments are significant difficulties. Also challenging is the analysis of a mixture spectrum without separation, which has been limited to simple molecules. Through nonuniform sampling using modified heteronuclear multiple bond correlation combined with indirect covariance, a high-resolution 13C–13C correlation spectrum was obtained with 1H sensitivity. Built on the thus-obtained 13C–13C connectivities, deconvolution of the mixture spectra was achieved through a new signal-processing procedure, termed DECODE, tailored to the indirect covariance eigendecomposition. When applied to a complex natural product mixture of rotenone and brucine with many quaternary carbons, the method resolved very close carbon peaks and extracted clean individual spectra. Essentially providing molecule-wide 13C connectivities for complex molecules from 1H-detected 2D spectra, our approach should prove useful in many areas of NMR analysis.

Chakraborty, A., Ruff, S.E., Dong, X., Ellefson, E.D., Li, C., Brooks, J.M., McBee, J., Bernard, B.B., Hubert, C.R.J., 2020. Hydrocarbon seepage in the deep seabed links subsurface and seafloor biospheres. Proceedings of the National Academy of Sciences 117, 11029-11037.

https://doi.org/10.1073/pnas.2002289117

Significance: The marine subsurface is one of the largest habitats on Earth composed exclusively of microorganisms and harboring on the order of 1029 microbial cells. It is unclear if deep subsurface life impacts overlying seafloor diversity and biogeochemical cycling in the deep ocean. We analyzed the microbial communities of 172 seafloor surface sediment samples, including gas and oil seeps as well as sediments not subject to upward fluid flow. A strong correlation between typical subsurface clades and active geofluid seepage suggests that subsurface life is injected into the deep ocean floor at hydrocarbon seeps, a globally widespread hydrogeological phenomenon. This supply of subsurface-derived microbial populations, biomass, and metabolic potential thus increases biodiversity and impacts carbon cycling in the deep ocean.

Abstract: Marine cold seeps transmit fluids between the subseafloor and seafloor biospheres through upward migration of hydrocarbons that originate in deep sediment layers. It remains unclear how geofluids influence the composition of the seabed microbiome and if they transport deep subsurface life up to the surface. Here we analyzed 172 marine surficial sediments from the deep-water Eastern Gulf of Mexico to assess whether hydrocarbon fluid migration is a mechanism

for upward microbial dispersal. While 132 of these sediments contained migrated liquid hydrocarbons, evidence of continuous advective transport of thermogenic alkane gases was observed in 11 sediments. Gas seeps harbored distinct microbial communities featuring bacteria and archaea that are well-known inhabitants of deep biosphere sediments. Specifically, 25 distinct sequence variants within the uncultivated bacterial phyla Atribacteria and Aminicenantes and the archaeal order Thermoprofundales occurred in significantly greater relative sequence abundance along with well-known seep-colonizing members of the bacterial genus Sulfurovum, in the gas-positive sediments. Metabolic predictions guided by metagenome-assembled genomes suggested these organisms are anaerobic heterotrophs capable of nonrespiratory breakdown of organic matter, likely enabling them to inhabit energy-limited deep subseafloor ecosystems. These results point to petroleum geofluids as a vector for the advection-assisted upward dispersal of deep biosphere microbes from subsurface to surface environments, shaping the microbiome of cold seep sediments and providing a general mechanism for the maintenance of microbial diversity in the deep sea.


http://dx.doi.org/10.1039/D0EM00005A

The chemical composition of water-soluble organics in oil sands process-affected water (OSPW) is primarily composed of natural constituents of bitumen that are solubilized and concentrated during aqueous extraction of oil sands. OSPW organics are persistent and acutely toxic, and a leading remediation strategy is long-term ageing in end-pit lakes, despite limited data available on its photochemical fate. Here, direct photolysis of whole OSPW, or of its constituent fractions, was examined at environmentally relevant wavelengths (>290 nm) in bench-top studies. Changes in the chemical profiles of whole OSPW, acid- (AEO), and base-extractable organics (BEO) were characterized by liquid chromatography with ultra-high resolution mass spectrometry in negative (−) and positive (+) ionization modes. Following 18 d of irradiation, photolysis reduced the total ion intensity in all samples in both modes. The most photo-labile species included the O2

−, O3−, O4

−, O2S−, and O4S− chemical classes, which were depleted in whole OSPW by 93–100% after only 5 d. In positive mode, detected species were more recalcitrant than those detected in negative mode, with an average reduction across all heteroatomic classes of 75 ± 11.0% after 18 d. Estimated environmental half-lives for heteroatomic classes ranged from 57 d (O4S−) to 545 d (O3N+), with a greater recalcitrance for classes detected in positive mode compared to negative mode. Under field conditions in end-pit lakes, natural photolysis may be an important mechanism for effective OSPW remediation, and we suggest that future end-pit lakes be shallow to maximize light penetration and natural photolysis in ageing OSPW.

Chen, C., Ciazela, J., Li, W., Dai, W., Wang, Z., Foley, S.F., Li, M., Hu, Z., Liu, Y., 2020. Calcium isotopic compositions of oceanic crust at various spreading rates. Geochimica et Cosmochimica Acta 278, 272-288.


The oceanic crust consists mainly of a lower layer of cumulate gabbroic rocks and an upper layer of differentiated basalts. The thicknesses and proportions of the gabbroic and basaltic layers in different oceans are largely controlled by spreading rate, magma supply, and magmatic differentiation processes. Evaluating the effects of complex magmatic differentiation as a function of spreading rate on Ca isotope composition is critical to understanding whether the Ca isotope compositions of oceanic crust from different oceans are homogeneous and thus whether the observed considerable variation of δ44/40Ca in basalts (up to 0.4‰) results from magmatic differentiation or mantle source heterogeneity. To address the question, we present δ44/40Ca measurements of a series of gabbroic rocks (n = 38) and mineral separates from the 810-m-long U1473A hole drilled into the gabbroic lower crust at the ultraslow-spreading Southwest Indian Ridge (SWIR), along with 12 mid-ocean ridge basalts (MORBs) from the slow-spreading South Mid-Atlantic Ridge (SMAR) and the fast-spreading East Pacific Rise (EPR). Although the gabbroic rocks of the SWIR reflect several events of magma supply and strong magmatic differentiation (bulk rock Mg# of 64–79 for each event), their δ44/40Ca values (0.85 ± 0.09‰, 2sd, n = 37) are uniform. The results are consistent with limited inter-mineral Ca isotope fractionation between plagioclase (Pl) and co-existing clinopyroxene (Cpx) in the accumulated gabbros (average Δ44/40CaPl-Cpx = −0.10‰, n = 5). This indicates that no measurable Ca isotope fractionation occurs during formation of ultraslow-spreading oceanic crust. The MORBs from the SMAR and EPR show consistent δ44/40Ca values (0.82 ± 0.08‰ (2sd, n = 4) and 0.86 ± 0.09‰ (2sd, n = 8), respectively), regardless of the degree of fractional crystallization. On the whole, the ultraslow-, slow- and fast-spreading gabbroic cumulates and MORBs display indistinguishable δ44/40Ca within analytical uncertainty, suggesting a homogenous Ca isotope composition for the global igneous oceanic crust (δ44/40Ca = 0.85 ± 0.09‰, 2sd, n = 49) even if they experience complex magmatic differentiation. Comparison with values for fertile mantle rocks (δ44/40Ca = 0.94 ± 0.10‰) reveals that partial melting triggers only slight Ca isotope fractionation (0.09 ± 0.02‰, 2se). In this light, the considerable variation of previously reported δ44/40Ca values for basalts may result from their different mantle sources, and is probably attributable to the recycling of crustal materials.

Chen, C., Hall, S.J., Coward, E., Thompson, A., 2020. Iron-mediated organic matter decomposition in humid soils can counteract protection. Nature Communications 11, 2255.

https://doi.org/10.1038/s41467-020-16071-5

Soil organic matter (SOM) is correlated with reactive iron (Fe) in humid soils, but Fe also promotes SOM decomposition when oxygen (O2) becomes limited. Here we quantify Fe-mediated OM protection vs. decomposition by adding 13C dissolved organic matter (DOM) and 57FeII to soil slurries incubated under static or fluctuating O2. We find Fe uniformly protects OM only under static oxic conditions, and only when Fe and DOM are added together: de novo reactive Fe III phases suppress DOM and SOM mineralization by 35 and 47%, respectively. Conversely, adding 57FeII alone increases SOM mineralization by 8% following oxidation to 57FeIII. Under O2 limitation, de novo reactive 57FeIII phases are preferentially reduced, increasing anaerobic mineralization of DOM and SOM by 74% and 32‒41%, respectively. Periodic O2 limitation is common in humid soils, so Fe does not intrinsically protect OM; rather reactive Fe phases require their own physiochemical protection to contribute to OM persistence.

Chen, G., Gang, W., Chang, X., Wang, N., Zhang, P., Cao, Q., Xu, J., 2020. Paleoproductivity of the Chang 7 unit in the Ordos Basin (North China) and its controlling factors. Palaeogeography, Palaeoclimatology, Palaeoecology 551, 109741.


Primary paleoproductivity provides basic organic matter for the formation of high-quality hydrocarbon source rock. A progressive method to quantitatively calculate paleoproductivity on the basis of total organic carbon (TOC) has been proposed to evaluate the contribution of primary paleoproductivity to a hydrocarbon source rock with high organic matter abundance. In this study, pyrite contents, organic maceral compositions and high-resolution sedimentation rates (SRs) were used to recover the amount of organic matter oxidation and to exclude the effect of terrestrial clastic input during the deposition of the Chang 7 sediment. Multiple calculation methods were used to quantitatively reconstruct paleoproductivity, and the results suggest that the Ordos Basin was a eutrophic lacustrine basin (approximately 2 × 104 mg C cm−2 kyr−1 to 10 × 104 mg C cm−2 kyr−1) during the Chang 7 stage compared with modern lake productivity. The paleoclimatic analysis indicates that a warm humid paleoclimate was beneficial for increasing the weathering intensity, which could have provided more nutrient inputs to the depositional environment with incoming terrestrial debris. In addition, the plate collision between the North China Block and Yangtze Block generated moderate volcanic ash that spread to the study area and provided large amounts of essential nutrients for algae blooms. Moreover, a brackish water condition promoted upward mixing of deep water, which inhibited water mass stratification and then facilitated primary paleoproductivity. In general, the Chang 7 high-quality hydrocarbon source rock is a result of increased paleoproductivity resulting from suitable paleoclimate conditions, brackish water masses and abundant essential nutrient inputs.

Chen, J., Liao, J., Wei, C., 2020. Coking wastewater treatment plant as a sources of polycyclic aromatic hydrocarbons (PAHs) in sediments and ecological risk assessment. Scientific Reports 10, 7833.

https://doi.org/10.1038/s41598-020-64835-2

The spatial and temporal distribution of polycyclic aromatic hydrocarbons (PAHs) was investigated in sediments of Maba River, a major tributary of Beijiang River (South China). A total of 13 samples from Maba River and its tributary, Meihua River, were analyzed for 16 PAHs. The total concentration of 16 PAHs (ΣPAH) in high and low water period ranged between 47.61 to 25480.98 ng g−1, with a mean concentration of 4382.98 ng g−1, and 60.30 to 15956.62 ng g−1 with a mean concentration of 3664.32 ng g−1, respectively. Three-ring and four-ring PAHs were the dominant species. It was concluded that a pattern of pyrolytic input as a major source of PAHs in sediments through the molecular ratio method for the source identification, such as HMW/LMW PAHs, Flu/(Flu+Pyr), IcdP/(IcdP+BghiP) and BaA/(BaA+Chr). It is suggested that the pollution emission from the iron and steel plant might be the most important sources of PAHs into Maba River water system. The threat of PAHs contamination to biota of the river was assessed using effect range low (ERL) and effect range median (ERM) values, which suggested that PAHs in Maba River and its tributary had already caused ecological risks.

Chen, J., Pang, X., Wang, X., Wang, Y., 2020. A new method for assessing tight oil, with application to the Lucaogou Formation in the Jimusaer depression, Junggar Basin, China. American Association of Petroleum Geologists Bulletin 104, 1199-1229.

http://archives.datapages.com/data/bulletns/2020/06jun/BLTN17401/bltn17401.html

This study proposes a new method for estimating tight oil resources in a closed petroleum system using an alternative mass balance model. The proposed approach primarily derives resource estimates based on a large volume of Rock-Eval pyrolysis data. In addition to leveraging the cost-effective, straightforward, and rapid process, the proposed method has the flexibility to assess the potential of different types of resources, including organic-rich tight (shale) oil and organic-lean tight oil. The method is validated by assessing the oil resource potential of the middle Permian Lucaogou Formation (P2l) in the Jimusaer depression, Junggar Basin, China. Results indicate that the P2l contains 1.62 × 109 t (11.91 × 109 bbl) of organic-rich and 2.88 × 109 t (21.17 × 109 bbl) of organic-lean tight oil. Of the organic-rich tight oil, 21% comprises free oil resources, amounting to 0.343 × 109 t (2.521 × 109 bbl). The proposed approach deals sufficiently with the different resources in a petroleum system well and provides a useful tool for estimating the resource potential of an unconventional play.

Chen, J., Xie, J., Zhang, Z., Wang, F., Hu, J., Li, H., 2020. Rapid and accurate determination of carboxyl groups in carbon materials by headspace gas chromatography. Journal of Chromatography A 1621, 461062.


This paper reports a novel and rapid method for determining carboxyl groups in carbon materials by headspace gas chromatography (HS-GC). Taking carboxylated carbon nanotubes (CNTs) as an example, the experiment based on GC measurement of carbon dioxide (CO2) generated by complete reaction between carboxyl groups and sodium bicarbonate in a sealed vial, which showed that carboxyl groups in CNTs could be completely transformed into CO2 under the equilibrium temperature at 60 °C for 10 min. The relative standard deviation (RSD) of this method in the repeatability test was less than 1.52%, and the limit of quantitation (LOQ) for carboxyl content was 0.014 mmol/g in CNTs. More significantly, appropriate ultrasound of the sample before headspace injection could greatly improve the detection efficiency by reducing the equilibrium time. All in all, the HS-GC method provides an automated and accurate analysis for testing carboxyl groups in carbon materials, and it is of profound significance to develop a new way for quantitative research of carbon materials.



The concentrations of Cu and Ag, both insoluble chalcophile elements, can be used to place tight constraints on the proportion of basalts in the upper continental crust (UCC) through time via analyses of fine-grained terrigenous sedimentary rocks. Copper and Ag concentrations in magmas are largely controlled by sulfide dissolution during melting and sulfide fractionation during

differentiation. We show that Cu is high in basalts but low in komatiites and felsic rocks, making Cu useful for constraining the proportion of basalts in the UCC. Furthermore, Cu/Ag ratios are high in basalts and komatiites but decrease with differentiation. The fine-grained matrix of ancient glacial diamictites shows dramatic declines in both Cu concentrations and Cu/Ag ratios at 3.0–2.4 Ga, after which diamictite Cu concentrations and Cu/Ag ratios remain roughly constant. Mass-balance calculations using average Cu concentrations of Archean komatiites, basalts and felsic rocks require that a high proportion basalt (65–75%) was present in the UCC at ∼3.0 Ga, and this crust transitioned to a felsic-rock-dominated crust at ∼2.4 Ga ago and has remained basically unchanged since then. This conclusion is supported by the consistency between the Cu/Ag ratios in the diamictites and the weighted average Cu/Ag ratios based on the lithological proportions obtained using Cu mass-balance calculations. Our observations document the emergence of felsic continental crust in the late Archean, which, in turn, indicates a fundamental change in Earth’s dynamic regime at that time.

Chen, L.C., 2020. A plug-and-play high-pressure ESI source with an emitter at ground potential and its application to high-temperature capillary LC-MS. Journal of the American Society for Mass Spectrometry 31, 1015-1018.

https://doi.org/10.1021/jasms.0c00052

A new high-pressure ESI source that can be readily used for commercial API mass spectrometers in a plug-and-play manner without any modification on the ion sampling interface is introduced. The emitter can be operated at ground potential, and the positive mode electrospray is generated by applying a negative high potential to the counter electrode. A shielding electrode effectively shields the opposing electric field and improves the ion transmission. This feature facilitates the direct connection of the ESI emitter to the electrically grounded components. The application of the present ion source to the high-temperature (>100 °C) capillary liquid chromatography for high-speed separation of peptide and proteins is demonstrated using a monolithic polymeric column.



Significance: The oxygenation of the atmosphere about 2.4 billion years ago remodeled global cycles of toxic, redox-sensitive metal(loids), including that of arsenic, which must have represented a cataclysm in the history of life. Our understanding of biological adaptations surrounding this key transition remains unexplored. By estimating the timing of genetic systems for arsenic detoxification, we reveal an expansion of enzymes and pathways that accompanied adaptations to the biotoxicity of oxidized arsenic species produced by Great Oxidation Event. These include enzymes originated via convergent evolution and pathways that use oxygen for enzymatic catalysis. Our results illustrate how life thrived under the stress of metal(loid) toxicity and provide insights into environmental biogeochemical cycling and microbial evolution.

Abstract: The rise of oxygen on the early Earth about 2.4 billion years ago reorganized the redox cycle of harmful metal(loids), including that of arsenic, which doubtlessly imposed substantial barriers to the physiology and diversification of life. Evaluating the adaptive biological responses to these environmental challenges is inherently difficult because of the paucity of fossil records. Here we applied molecular clock analyses to 13 gene families participating in principal pathways of arsenic resistance and cycling, to explore the nature of early arsenic biogeocycles and decipher feedbacks associated with planetary oxygenation. Our results reveal the advent of nascent arsenic resistance systems under the anoxic environment predating the Great Oxidation Event (GOE), with the primary function of detoxifying reduced arsenic compounds that were abundant in Archean environments. To cope with the increased toxicity of oxidized arsenic species that occurred as oxygen built up in Earth’s atmosphere, we found that parts of preexisting detoxification systems for trivalent arsenicals were merged with newly emerged pathways that originated via convergent evolution. Further expansion of arsenic resistance systems was made feasible by incorporation of oxygen-dependent enzymatic pathways into the detoxification network. These genetic innovations, together with adaptive responses to other redox-sensitive metals, provided organisms with novel mechanisms for adaption to changes in global biogeocycles that emerged as a consequence of the GOE.



This study investigated the effectiveness of a combined membrane bioreactor (MBR) and reverse osmosis (RO) process for treating leachate produced by a large-scale anaerobic landfill. The MBR process had limited treatment efficiency for removing organic pollutants, but when combined with RO, the integrated system completely removed macromolecular compounds (i.e., humic- and fulvic-like substances) and produced effluent that satisfied the applicable discharge standard. The landfill leachate contained many types of DOM that had high molecular weight and were highly unsaturated. Although the MBR process removed some DOM that had a relatively low saturated degree (mainly aliphatic compounds (2.0 ≥ H/C ≥ 1.5) with relatively high bioavailability), many bio-refractory compounds were not removed. The RO system greatly reduced the content of residual DOM in MBR effluent and was effective for removing heteroatom DOM, especially polycyclic aromatics (AI > 0.66) and polyphenols (0.66 ≥ AI > 0.50). The effluent from the combined process of MBR and RO treatment mainly contained a small number of aliphatic compounds and phenolic compounds (AI ≤ 0.50 and H/C < 1.5) that had higher bioavailability than DOM in the raw leachate and posed little environmental risk.



The effects of petroleum retention within and expulsion from five intervals within the Triassic Chang 7 Member in the Ordos Basin in China have been demonstrated by deciphering a large suite of petrologic, organic petrographic, and organic geochemical analyses on 106 core samples.

Organic properties and lithological heterogeneities control the amount and chemical composition of retained petroleum. Enrichment of aliphatic hydrocarbons in the silty, organic-lean intervals versus enrichment of aromatic fluids in the clayey, organic-rich units are probably caused by compositional fractionation occurred during primary and short-distance secondary migration. Migration of excess petroleum from organic-rich units to those organic-lean counterparts was further corroborated by the negative expulsion efficiencies calculated using a mass-balance model in the organic-lean intervals. Capillary pressure difference induced by the contrast in pore throat size of the clayey, organic-rich versus the silty, organic-lean intervals is postulated to be the major driver for the migration.

A significant implication of this study is that the hydrocarbons in the first and fourth intervals constitute potential petroleum exploitation targets, given (i) improved oil quality caused by enriched aliphatic compounds versus viscous aromatic and polar compounds, (ii) lower organic matter sorption affinities, (iii) relatively high contents of brittle minerals in these two intervals. Despite its high content of retained hydrocarbons, the organic-rich fifth interval is not the best target, which is mainly due to the high sorption affinity of the organic matter structure, thereby causing low oil mobility and producibility.

Chen, Z., Chen, J., Zhong, N., Fei, W., Dong, Q., Chen, J., Wang, Y., 2020. The geneses of sedimentary organic matter with anomalous 13C-enriched isotopic composition in saline and freshwater lakes: A case study of lacustrine source rocks from Dongpu and Qikou sags, Bohai Bay Basin, eastern China. Marine and Petroleum Geology 118, 104434.


The carbon isotopic composition of sedimentary organic matter (δ13COM) is notably important for the genetic identification of source rock and its products. The sapropelic organic matter (mostly plankton with high hydrogen index) is generally depleted in 13C as compared to humic organic matter (mainly higher plants with lower hydrogen index). However, some lacustrine sediments contain sapropelic source rocks with anomalous 13C-enriched isotopic ratios, especially reported in freshwater lakes. The purpose of this study is to discuss the geneses of lacustrine sedimentary organic matter characterized by anomalous 13C-enriched ratios in saline and freshwater sediments. To this end, we integrate the detailed organic geochemical data (including Rock-Eval analysis data, total organic carbon contents, total organic carbon isotopic compositions, biomarkers, and trace element concentrations) of 64 saline lake sediments and 39 freshwater lake sediments obtained from the Paleogne Shahejie Formation of Dongpu sag and Qikou sag, separately, in Bohai Bay Basin of eastern China. Both sags exist samples with high hydrogen index values (HI > 400 mg/g) and high total organic carbon contents (TOC > 2%), but anomalous 13C-enriched isotopic ratios (up to −21.1‰). In Qikou sag, the δ13COM values of sapropelic kerogen correlate positively with TOC contents. The anomalous enrichment of 13C in organic matter is associated with extremely high productivity of algae, such as algae bloom. In Dongpu sag, the enrichment of 13C in organic matter is attributed to the significant increase of drought and salinity. High salinity and aridity climate may lead to the abundance of C4 plants and Chlorobium as well as the enrichment of 13C in plankton.

Chen, Z., Wang, Z., Zhang, S., Gao, Y., Han, C., Li, K., 2020. Biomarker characteristics of source rocks and oil source correlation in Baolegentaohai sag, Erlian Basin. Acta Sedimentologica Sinica 38, 451-462 http://www.cjxb.ac.cn/EN/abstract/abstract4106.shtml

Although good exploration achievements have been made in Baolegentaohai Sag of Erlian Basin,the basic research on hydrocarbon accumulation is still very weak. In this study,source rocks are classified according to geochemical characteristics,and then oil group division and oil source correlation are carried out according to the characteristics of the biomarker compounds. The results show effective source rocks in the study area can be divided into three types:The first type,in the upper part of K1bt1,is characterized by high organic matter abundance,low maturity,high C27-sterane relative content,high gammacerane content,and low Pr/Ph. The second type,in the lower part of K1bt1,is characterized by high organic matter abundance,medium maturity,and medium gammacerane and C27-sterane relative content. The third type,in K1ba,is characterized by relative high organic matter abundance,high maturity,low C27-sterane content,low gammacerane content,and high Pr/Ph. Crude oil can be divided into four groups:Oil group 1 is K1bt1 immature oil,with hydrocarbons from the first type of source rock. Oil group 2 is K1bt1 mature oil,with hydrocarbons from the second type of source rock. Oil group 3 is a mixture of K1bt1 immature and K1bt1 mature oil,with hydrocarbons from the first and second types of source rocks. Oil group 4 is a mixture of K1bt1 mature and K1ba mature oil,with hydrocarbons from the second and third types of source rocks. In terms of the favorable exploration area prediction by oil and gas sources,the favorable area predicted by K1bt1 source rock is 26.85 km2, and the favorable area predicted by K1ba source rock is 79.30 km2.

Cheng, Q., Zhang, M., Huang, G., 2020. Even-carbon predominance of monomethyl branched alkanes in Humic coal from Junggar Basin, NW China. Acta Geochimica 39, 434-444.

https://doi.org/10.1007/s11631-019-00372-8

A series of Monomethyl branched alkanes compounds were detected between nC14–nC36, in immature and low maturity Jurassic humic coal, Junggar basin. 2-methyl alkanes and 3-methyl alkanes accounted for the vast majority of the compounds. It is worth noting that the 2-methyl alkanes in the humic coal samples show an obvious distribution of even carbon predominances rarely reported in the literature. The results show that with the increase of Pr/Ph (pristane/phytane), the even carbon dominance of 2-methyl alkanes is more obvious, while the odd carbon number distribution of 3-methyl alkanes is weakened. As Pr/Ph increases in the humic coal, the relative content of the hopanes increased, while the relative content of 2-methyl alkanes and 3-methyl alkanes increases first and then decreases.

Chenrai, P., Fuengfu, S., 2020. Organic geochemistry of the Lower Permian Tak Fa Formation in Phetchabun Province, Thailand: implications for its paleoenvironment and hydrocarbon generation potential. Acta Geochimica 39, 291-306.

https://doi.org/10.1007/s11631-019-00370-w

The outcrop samples of the Tak Fa Formation (Lower Permian) in Phetchabun Province have been studied to determine their organic geochemical characteristic, depositional paleoenvironment, and

hydrocarbon generation potential. The total organic carbon (TOC) values ranging from 1.42 to 4.58 wt% and extractable organic matter values ranging from 76.84 to 197.65 ppm of the Tak Fa Formation were generally low and associated with low S2 values (0.00–0.50 mg HC/g rock) and hydrogen index values in range of 0–32 mg/g TOC, although this could reflect highly thermal maturity and complex tectonic history. Thus, kerogen classification can be based on a non-biomarker study for these outcrop samples instead. The non-biomarker plot, Pr/n-C17 and Ph/n-C18 from this study indicates that organic matter originally comes from type II/III kerogen. The samples were also investigated and indicated that the organic matter inputs were derived from mixed marine and terrigenous sources and deposited under suboxic to oxic conditions. The depositional environment of the Tak Fa Formation in this study is interpreted to be an estuarine environment or restricted lagoonal carbonate platforms. This has been achieved from normal alkane and isoprenoids distributions, terpane, and sterane biomarkers. Thus, the Tak Fa Formation is considered to be a hydrocarbon source rock during the time of the deposition. Although the geochemical data in this study indicate that the Tak Fa Formation has experienced high maturation, one or more locations could meet a condition that places this formation to be an active source rock. The approach and concepts presented in this study can be applied to similar evaporite-carbonate deposits in Thailand to find more petroleum plays.


http://dx.doi.org/10.1039/C9NP00048H

Covering: 2008 up to 2019 The forces of biochemical adaptive evolution operate at the level of genes, manifesting in complex phenotypes and the global biodiversity of proteins and metabolites. While evolutionary histories have been deciphered for some other complex traits, the origins of natural product biosynthesis largely remain a mystery. This fundamental knowledge gap is surprising given the many decades of research probing the genetic, chemical, and biophysical mechanisms of bacterial natural product biosynthesis. Recently, evolutionary thinking has begun to permeate this otherwise mechanistically dominated field. Natural products are now sometimes referred to as ‘specialized’ rather than ‘secondary’ metabolites, reinforcing the importance of their biological and ecological functions. Here, we review known evolutionary mechanisms underlying the overwhelming chemical diversity of bacterial secondary metabolism, focusing on enzyme promiscuity and the evolution of enzymatic domains that enable metabolic traits. We discuss the mechanisms that drive the assembly of natural product biosynthetic gene clusters and propose formal definitions for ‘specialized’ and ‘secondary’ metabolism. We further explore how biosynthetic gene clusters evolve to synthesize related molecular species, and in turn how the biological and ecological roles that emerge from metabolic diversity are acted on by selection. Finally, we reconcile chemical, functional, and genetic data into an evolutionary model, the dynamic chemical matrix evolutionary hypothesis, in which the relationships between chemical distance, biomolecular activity, and relative fitness shape adaptive landscapes.

Chin, E.J., Soustelle, V., Liu, Y., 2020. An SPO-induced CPO in composite mantle xenoliths correlated with increasing melt-rock interaction. Geochimica et Cosmochimica Acta 278, 199-218.


Melt-rock interaction, a general term describing various processes including cryptic and modal metasomatism and melt-rock reaction, is the main process responsible for modifying chemical composition of previously melt-depleted mantle peridotite. However, the underlying mechanisms of melt-rock interaction and its effect on mantle rheology, particularly in natural peridotites, is poorly constrained. Composite xenoliths are natural examples of melt-rock interaction as they contain pyroxenitic veins interpreted as evidence of passage of melt through peridotite at high pressures. Here, we present new mineral chemistry (major, trace element, and water contents of olivine and pyroxenes) and microstructural data on a suite of composite xenoliths from the Neogene Hannuoba basalt, North China Craton. We show that despite having experienced high melt/rock ratios, olivines and pyroxenes contain very low water contents (<10 ppm and <100 ppm, respectively). In contrast, melts calculated to be in equilibrium with clinopyroxene show enriched trace element signatures suggesting the infiltrating melt had a crustal origin. Microstructural data corroborate a key role for melt infiltration in causing a systematic shift in olivine crystallographic preferred orientation (CPO) from initially A-type to AG-type with increasing melt/rock ratio. By describing the olivine grain shape with respect to the crystal reference frame, we show that as pyroxene mode (and hence melt/rock ratio) increases, olivine grains appear to rotate with their flattest (0 1 0) faces aligning with the melt flow plane, resulting in an olivine CPO controlled by its shape-preferred orientation (SPO). Previously, such an SPO-induced CPO was only demonstrated in shallow magmatic environments such as mafic intrusions, in mafic lavas, and in high-pressure/high-temperature experiments. Such a finding in the deep lithosphere is important as it suggests that dislocation creep may not always play a major role in CPO development, particularly when melt is involved.

Ciemniecki, J.A., Newman, D.K., 2020. The potential for redox-active metabolites to enhance or unlock anaerobic survival metabolisms in aerobes. Journal of Bacteriology 202, e00797-19.

http://jb.asm.org/content/202/11/e00797-19.abstract

Classifying microorganisms as “obligate” aerobes has colloquially implied death without air, leading to the erroneous assumption that, without oxygen, they are unable to survive. However, over the past few decades, more than a few obligate aerobes have been found to possess anaerobic energy conservation strategies that sustain metabolic activity in the absence of growth or at very low growth rates. Similarly, studies emphasizing the aerobic prowess of certain facultative aerobes have sometimes led to underrecognition of their anaerobic capabilities. Yet an inescapable consequence of the affinity both obligate and facultative aerobes have for oxygen is that the metabolism of these organisms may drive this substrate to scarcity, making anoxic survival an essential skill. To illustrate this, we highlight the importance of anaerobic survival strategies for Pseudomonas aeruginosa and Streptomyces coelicolor, representative facultative and obligate aerobes, respectively. Included among these strategies, we describe a role for redox-active secondary metabolites (RAMs), such as phenazines made by P. aeruginosa, in enhancing substrate-level phosphorylation. Importantly, RAMs are made by diverse bacteria, often during stationary phase in the absence of oxygen, and can sustain anoxic survival. We present a hypothesis for how RAMs may enhance or even unlock energy conservation pathways that facilitate the anaerobic survival of both RAM producers and nonproducers.

Ciglenečki, I., Čanković, M., Kuzmić, M., Pagano, M., 2020. Accumulation of organic matter in a mesotidal Mediterranean lagoon (Boughrara, Tunisia). Estuarine, Coastal and Shelf Science 240, 106780.


In the frame of the COZOMED project, concentrations of organic matter (TOC, DOC, POC) were monitored during two seasonal field campaigns (autumn, October 2016 and spring, April 2017) in the Boughrara Lagon, Tunisia. Results indicate strong influence of the seawater exchange and circulation, on the organic matter accumulation inside the lagoon, visible through a significant correlation between TOC and salinity in both seasons. Two times higher concentration of TOC (up to 5.5 mg/l) was recorded in autumn, when high salinity water (46 psμ) was present in the lagoon. POC made a relatively small percentage of TOC in autumn samples when high accumulation of TOC, especially its DOC fraction can be related to remineralization processes and zooplankton-mediated release of DOC. Indeed, PCA analysis identified DOC as the most significant factor influencing the observed variability in autumn samples, and correlated to NH4

+ (p < 0.05) in surface waters, while POC was significantly (p < 0.05) correlated to chlorophyll a. During spring, organic matter in the lagoon was depth-dependent and under the high influence of salinity and temperature, and in the surface correlated to NO3

-. Satellite data on lagoon water optical properties appear to support changes in measured organic matter concentrations indicating different optical properties of the water inside the lagoon during spring and autumn seasons. The ocean color remote sensing, with properly validated and tested robust algorithms, accommodating optically shallow waters, can provide valuable tools for monitoring and timely detection of possibly detrimental changes inside the lagoon.

Ciotoli, G., Procesi, M., Etiope, G., Fracassi, U., Ventura, G., 2020. Influence of tectonics on global scale distribution of geological methane emissions. Nature Communications 11, 2305.

https://doi.org/10.1038/s41467-020-16229-1

Earth’s hydrocarbon degassing through gas-oil seeps, mud volcanoes and diffuse microseepage is a major natural source of methane (CH4) to the atmosphere. While carbon dioxide degassing is typically associated with extensional tectonics, volcanoes, and geothermal areas, CH4 seepage mostly occurs in petroleum-bearing sedimentary basins, but the role of tectonics in degassing is known only for some case studies at local scale. Here, we perform a global scale geospatial analysis to assess how the presence of hydrocarbon fields, basin geodynamics and the type of faults control CH4 seepage. Combining georeferenced data of global inventories of onshore seeps, faults, sedimentary basins, petroleum fields and heat flow, we find that hydrocarbon seeps prevail in petroleum fields within convergent basins with heat flow ≤ 98 mW m−2, and along any type of brittle tectonic structure, mostly in reverse fault settings. Areas potentially hosting additional seeps and microseepage are identified through a global seepage favourability model.

Clark, J.B., Long, W., Hood, R.R., 2020. A comprehensive estuarine dissolved organic carbon budget using an enhanced biogeochemical model. Journal of Geophysical Research: Biogeosciences 125, e2019JG005442.

https://doi.org/10.1029/2019JG005442

Abstract: Complicated biogeochemical cycling and differential organic matter reactivity make quantifying the relative contribution of a given source of organic carbon to the standing stock within an estuary difficult. Here, a new model of tidal marsh estuary organic carbon cycling is presented for‐

the Rhode River, MD, a well studied tributary of the Chesapeake Bay, USA. A dissolved organic ‐carbon (DOC) budget was estimated by summing the source and sink terms and the advection of water within the tributary. 13.1% and 15.3% of the total DOC input to the Rhode River entered from the marsh and the watershed, respectively, and 52.6% was derived from phytoplankton production. Extrapolating to the entire year, 35.5 Mg of DOC is exported to the main stem of Chesapeake Bay annually, which accounts for 12.3% of the total allochthonous and autochthonous inputs to the estuary. Removing the modeled marsh at the head of the Rhode River decreased export of DOC to the main stem by 39.2%, and up to 56% of the estuarine DOC standing stock can be attributed to the marsh. The model described here can be used across temperate estuarine systems and provides a new methodology for quantifying the amount of DOC that can be attributed to or lost by specific source and sink pathways.

Plain Language Summary: Tidal wetlands are potentially significant in global carbon cycling, taking large quantities of carbon dioxide out of the atmosphere and fixing it as plant and root biomass. Some of this fixed carbon is buried on long time scales, but a large portion is also transported out of wetlands into estuaries. Understanding where the carbon goes and how long it takes to get there is important for carbon cycling and potentially feedbacks related to climate change. The role tidal wetlands play in estuary carbon cycling and biogeochemistry is complex, and this paper uses a computer model to give insight into how these two important systems are linked. We found that a tidal wetland in a tributary of Chesapeake Bay contributes a large portion (39%) to the total organic carbon export from the tributary. This implies that relative to their inputs, tidal wetlands potentially contribute a greater portion to the total export from estuaries. Wetlands are thus potentially more important in carbon budgets than their inputs to estuaries would suggest.

Cockell, C.S., 2020. Persistence of habitable, but uninhabited, aqueous solutions and the application to extraterrestrial environments. Astrobiology 20, 617-627.

https://doi.org/10.1089/ast.2019.2179

In most environments on Earth, habitable environments contain life. Experiments were conducted to investigate the decoupling of the presence of habitable conditions and life. A set of microcosms habitable for known groups of organisms, but uninhabited (i.e., uninhabited habitats), was exposed to external environmental conditions to test the hypothesis that extreme habitable environments can remain uninhabited for sustained time periods. These microcosms were made of tubes containing liquid water and inorganic N, P, and S. Organics (used as electron donors and as a C source) were provided as L and D amino acids. One set of uninhabited habitats contained no additional salts, one set contained saturated NaCl, and one set contained saturated MgSO4. A ddH2O control and a complex medium for Halobacterium were used as controls. The presence of organisms was tested by enumeration of colonists and sequencing of extracted DNA. At each time point, inoculation into fresh medium was used to test for growth of organisms. After 1 week, the “no salt” and saturated MgSO4 solutions were colonized. After 6 months, both the NaCl-saturated and Halobacterium solutions remained uninhabited, but all other samples were colonized. These experiments demonstrate that certain types of habitable liquid water environments exposed to microbial atmospheric inoculation, even on Earth, can remain devoid of reproducing life for many months. On other planetary bodies, such as Mars, these data imply the possibility of preserved transient water bodies that would record habitable conditions, but no evidence of life, even if life existed elsewhere on the planet.

Collins, G.S., Patel, N., Davison, T.M., Rae, A.S.P., Morgan, J.V., Gulick, S.P.S., Christeson, G.L., Chenot, E., Claeys, P., Cockell, C.S., Coolen, M.J.L., Ferrière, L., Gebhardt, C., Goto, K., Jones, H., Kring, D.A., Lofi, J., Lowery, C.M., Ocampo-Torres, R., Perez-Cruz, L., Pickersgill, A.E., Poelchau, M.H., Rasmussen, C., Rebolledo-Vieyra, M., Riller, U., Sato, H., Smit, J., Tikoo, S.M., Tomioka, N., Urrutia-Fucugauchi, J., Whalen, M.T., Wittmann, A., Xiao, L., Yamaguchi, K.E., Artemieva, N., Bralower, T.J., Party, I.-I.E.S., Third-Party, S., 2020. A steeply-inclined trajectory for the Chicxulub impact. Nature Communications 11, 1480.

https://doi.org/10.1038/s41467-020-15269-x

The environmental severity of large impacts on Earth is influenced by their impact trajectory. Impact direction and angle to the target plane affect the volume and depth of origin of vaporized target, as well as the trajectories of ejected material. The asteroid impact that formed the 66 Ma Chicxulub crater had a profound and catastrophic effect on Earth’s environment, but the impact trajectory is debated. Here we show that impact angle and direction can be diagnosed by asymmetries in the subsurface structure of the Chicxulub crater. Comparison of 3D numerical simulations of Chicxulub-scale impacts with geophysical observations suggests that the Chicxulub crater was formed by a steeply-inclined (45–60° to horizontal) impact from the northeast; several lines of evidence rule out a low angle (<30°) impact. A steeply-inclined impact produces a nearly symmetric distribution of ejected rock and releases more climate-changing gases per impactor mass than either a very shallow or near-vertical impact.

Costalago, D., Forster, I., Nemcek, N., Neville, C., Perry, R.I., Young, K., Hunt, B.P.V., 2020. Seasonal and spatial dynamics of the planktonic trophic biomarkers in the Strait of Georgia (northeast Pacific) and implications for fish. Scientific Reports 10, 8517.

https://doi.org/10.1038/s41598-020-65557-1

Fish growth and survival are largely determined by the nutritional quality of their food, and the fish that grow quickly during early life stages are more likely to reproduce. To adequately estimate the quality of the prey for fish, it is necessary to understand the trophic links at the base of the food-web. Trophic biomarkers (e.g., stable isotopes and fatty acids) are particularly useful to discriminate and quantify food-web relationships. We explored the connections between plankton food-web components, and the seasonal and spatial dynamics of the trophic biomarkers and how this determines the availability of high-quality prey for juvenile Pacific salmon and Pacific herring in the Strait of Georgia, Canada. We demonstrate that the plankton food-web in the region is largely supported by diatom and flagellate production. We also show that spatial differences in terms of energy transfer efficiency exist in the region. Further, we found that the fatty acid composition of the zooplankton varied seasonally, matching a shift from diatom dominated production in the spring to flagellate dominated production in the summer. This seasonal shift conferred a higher nutritional value to zooplankton in the summer, indicating better quality prey for juvenile salmon and herring during this period.

Costello, L.J., Filiberto, J., Crandall, J.R., Potter-McIntyre, S.L., Schwenzer, S.P., Miller, M.A., Hummer, D.R., Olsson-Francis, K., Perl, S., 2020. Habitability of hydrothermal systems at Jezero and Gusev Craters as constrained by hydrothermal alteration of a terrestrial mafic dike. Geochemistry 80, 125613.


NASA’s search for habitable environments has focused on alteration mineralogy of the Martian crust and the formation of hydrous minerals, because they reveal information about the fluid and environmental conditions from which they precipitated. Extensive work has focused on the formation of alteration minerals at low temperatures, with limited work investigating metamorphic or high-temperature alteration. We have investigated such a site as an analog for Mars: a mafic dike on the Colorado Plateau that was hydrothermally altered from contact with groundwater as it was emplaced in the porous and permeable Jurassic Entrada sandstone. Our results show evidence for fluid mobility removing Si and K but adding S, Fe, Ca, and possibly Mg to the system as alteration progresses. Mineralogically, all samples contain calcite, hematite, and kaolinite; with most samples containing minor anatase, barite, halite, and dolomite. The number of alteration minerals increase with alteration. The hydrothermal system that formed during interaction of the magma (heat source) and groundwater would have been a habitable environment once the system cooled below ∼120 °C. The mineral assemblage is similar to alteration minerals seen within the Martian crust from orbit, including those at Gusev and Jezero Craters. Therefore, based on our findings, and extrapolating them to the Martian crust, these sites may represent habitable environments which would call for further exploration and sample return of such hydrothermally altered igneous materials.

Cui, Z., Cheng, F., Jarvis, J.M., Brewer, C.E., Jena, U., 2020. Roles of co-solvents in hydrothermal liquefaction of low-lipid, high-protein algae. Bioresource Technology 310, 123454.


Valorization of algal biomass is often limited by its low lipid content. Here, different alcohols: ethanol, isopropanol, and glycerol, were studied as co-solvents to improve the conversion efficiency of a lipid-poor microalgae, Galdieria sulphuraria, by hydrothermal liquefaction. Bio-crude oil yield increases, from 13 to 73 wt.% (on dry algae basis), were attributed to the alcohols facilitating the transfer of algal protein-derived fragments from the aqueous phase into the oil phase. A series of characterization results showed that bio-crude oil formation was mainly the result of alcohols reacting with algal fragments via Maillard reactions, alkylation, and esterification, respectively. Insights into the synergistic effect of low-lipid feed and alcohol provide mechanistic support for choosing an alcohol-rich waste, crude glycerol, to improve bio-crude oil production from HTL of wastewater-grown G. sulphuraria. Promising improvements in yield and energy recovery indicates competitive economics for a low-lipid biomass waste-to-biofuel conversion technique.

Cuozzo, N., Sletten, R.S., Hu, Y., Liu, L., Teng, F.-Z., Hagedorn, B., 2020. Silicate weathering in Antarctic ice-rich permafrost: Insights using magnesium isotopes. Geochimica et Cosmochimica Acta 278, 244-260.


This study reports that substantial chemical weathering occurs at subzero temperatures in ice-and-salt-rich permafrost in the McMurdo Dry Valleys, Antarctica. Chemical weathering is documented in a 30.0-m core collected in Beacon Valley by measuring the ionic composition, pH, and Mg isotopes of water extracted from thawed ice-rich sediment. Evidence of rock weathering is revealed by

coinciding increases in the Mg isotopic composition and pH values. The primary factor that controls weathering is the salt content that leads to unfrozen brine; this is most apparent in the upper 7.0 m where salt content is high, temperatures rise above −21 °C and modeled unfrozen water reaches up to 4.0% of ice-content. In the upper 7.0 m, up to 60% of soluble Mg in the thawed permafrost ice is sourced from Ferrar Dolerite (δ26Mg = −0.22 ± 0.07‰) weathering, resulting in δ26Mg values ranging from of −0.82 ± 0.05‰ to −0.64 ± 0.05‰. Below 7.0 m, temperatures remain below −21 °C, unfrozen water is less than 2.0% of ice-content, and on average, 5% of soluble Mg is sourced from dolerite weathering with δ26Mg values ranging from −1.05 ± 0.05‰ to −0.76 ± 0.05‰. Regions of the core that are modeled to have no unfrozen water show little or no evidence of chemical weathering and relatively constant δ26Mg values close to Taylor Glacier and Beacon Valley snowfall values (–0.93 ± 0.06‰). This study demonstrates that significant chemical weathering occurs at subzero temperatures in permafrost where liquid brines form.

Dascalu, A.-E., Ghinet, A., Chankvetadze, B., Lipka, E., 2020. Comparison of dimethylated and methylchlorinated amylose stationary phases, coated and covalently immobilized on silica, for the separation of some chiral compounds in supercritical fluid chromatography. Journal of Chromatography A 1621, 461053.


The chromatographic properties of a new coated amylose tris(3-chloro-5-methylphenylcarbamate) were evaluated in supercritical fluid chromatography for the separation of enantiomers of chiral 1-aryl-5-aryl-pyrrolidin-2-one derivatives, potential anticancer agents, and some commercial drugs. The mobile phase consisted of CO2-modifier mixtures with 30% of either methanol or ethanol, the flow rate was 3 mL/min. The column oven temperature was 40 °C and the outlet pressure was 15 MPa, in order to limit the compressibility of the CO2, thus limiting density variation along the column. The obtained results were then compared to those observed toward 3 other stationary phases: the coated amylose tris(3,5-dimethylphenylcarbamate), the immobilized amylose tris(3,5-dimethylphenylcarbamate) and the coated amylose tris(5-chloro-2-methylphenylcarbamate). It was shown that the new coated amylose tris(3-chloro-5-methylphenylcarbamate) was the most retentive column whatever the studied compounds, particularly for thalidomide and omeprazole with retention factors up to 73.3 and 29.5for the second enantiomer, respectively. Concerning the enantioselectivity, even most of the compounds are separated on all the four columns, the coated amylose tris(3-chloro-5-methylphenylcarbamate) allows the best resolution for most of the ten studied analytes (except omeprazole for which the resolution values are equal to 7.8 and 9.7 on the coated amylose tris(3-chloro-5-methylphenylcarbamate) and amylose tris(3,5-dimethylphenylcarbamate), respectively). Acting in complementary ways, the two chlorinated stationary phases permitted the complete separation of enantiomers of nine compounds out of the ten.

Dauner, A.L.L., Mollenhauer, G., Bícego, M.C., Martins, C.C., 2020. Cluster analysis for time series based on organic geochemical proxies. Organic Geochemistry 145, 104038.


Depositional and paleoenvironmental studies using organic geochemical proxies often present the temporal evolution of several compounds. Despite the importance of using several proxies to

understand how the surrounding environment changed through time, this large amount of data usually hampers interpretations. In this scenario, the use of statistical tools for time series analysis can help simplify and interpret large data sets, even if they were not initially developed for molecular marker data. In this study, we show the benefits of using two different cluster analyses in order to: (i) group compounds with similar sources; and (ii) identify temporal zones. Cluster analysis using SAX (Symbolic Aggregate approXimation) representation groups together different proxies with similar sources (whether anthropogenic or natural, autochthonous or allochthonous), based on their temporal evolution. Temporal zones, on the other hand, can be identified by using a constrained cluster analysis, in which samples (sediment layers) are grouped according to the temporal variability of the organic compounds. These two approaches were successfully applied to organic proxy datasets from two sediment cores, retrieved from distinct environments and with distinct temporal recoveries. Based on these analyses, we were able to identify the probable source of compounds with multiple sources, and to show how the terrestrial and marine organic matter presented distinct patterns over time. These techniques do not replace the study of the temporal evolution of compounds individually but synthesize a large amount of information and may indicate which compounds of an assemblage yield the most robust information in environmental studies.

Davis, K., Moon, T.S., 2020. Tailoring microbes to upgrade lignin. Current Opinion in Chemical Biology 59, 23-29.


Lignin depolymerization generates a mixture of numerous compounds that are difficult to separate cost-effectively. To address this heterogeneity issue, microbes have been employed to ‘biologically funnel’ a broad range of compounds present in depolymerized lignin into common central metabolites that can be converted into a single desirable product. Because the composition of depolymerized lignin varies significantly with the type of biomass and the depolymerization method, microbes should be selected and engineered by considering this compositional variation. An ideal microbe must efficiently metabolize all relevant lignin-derived compounds regardless of the compositional variation of feedstocks, but discovering or developing such a perfect microbe is very challenging. Instead, developing multiple tailored microbes to tolerate a given mixture of lignin-derived compounds and to convert most of these into a target product is more practical. This review summarizes recent progress toward the development of such microbes for lignin valorization and offers future directions.


https://doi.org/10.1089/ast.2018.1959

As part of the Biology and Mars Experiment (BIOMEX; ILSRA 2009-0834), samples of the lichen Circinaria gyrosa were placed on the exposure platform EXPOSE-R2, on the International Space Station (ISS) and exposed to space and to a Mars-simulated environment for 18 months (2014–2016) to study: (1) resistance to space and Mars-like conditions and (2) biomarkers for use in future space missions (Exo-Mars). When the experiment returned (June 2016), initial analysis showed rapid

recovery of photosystem II activity in the samples exposed exclusively to space vacuum and a Mars-like atmosphere. Significantly reduced recovery levels were observed in Sun-exposed samples, and electron and fluorescence microscopy (transmission electron microscope and field emission scanning electron microscope) data indicated that this was attributable to the combined effects of space radiation and space vacuum, as unirradiated samples exhibited less marked morphological changes compared with Sun-exposed samples. Polymerase chain reaction analyses confirmed that there was DNA damage in lichen exposed to harsh space and Mars-like environmental conditions, with ultraviolet radiation combined with space vacuum causing the most damage. These findings contribute to the characterization of space- and Mars-resistant organisms that are relevant to Mars habitability.

de Nooijer, W., Zhang, Q., Li, Q., Zhang, Q., Li, X., Zhang, Z., Guo, C., Nisancioglu, K.H., Haywood, A.M., Tindall, J.C., Hunter, S.J., Dowsett, H.J., Stepanek, C., Lohmann, G., Otto-Bliesner, B.L., Feng, R., Sohl, L.E., Tan, N., Contoux, C., Ramstein, G., Baatsen, M.L.J., von der Heydt, A.S., Chandan, D., Peltier, W.R., Abe-Ouchi, A., Chan, W.-L., Kamae, Y., Brierley, C.M., 2020. Evaluation of Arctic warming in mid-Pliocene climate simulations. Climate of the Past Discussions 2020, 1-30.

https://www.clim-past-discuss.net/cp-2020-64/

Palaeoclimate simulations improve our understanding of the climate, inform us about the performance of climate models in a different climate scenario, and help to identify robust features of the climate system. Here, we analyse Arctic warming in an ensemble of 16 simulations of the mid-Pliocene Warm Period (mPWP), derived from the Pliocene Model Intercomparison Project Phase 2 (PlioMIP2).

The PlioMIP2 ensemble simulates Arctic (60–90° N) annual mean surface air temperature (SAT) increases of 3.7 to 11.6 °C compared to the pre-industrial, with a multi-model mean (MMM) increase of 7.2 °C. The Arctic warming amplification ratio relative to global SAT anomalies in the ensemble ranges from 1.8 to 3.1 (MMM is 2.3). Sea ice extent anomalies range from −3.0 to −10.4 × 06 km2 with a MMM anomaly of −5.6 × 106 km2, which constitutes a decrease of 53 % compared to the pre-industrial. The majority (11 out of 16) models simulate summer sea ice-free conditions (≤ 1 × 06 km2) in their mPWP simulation. The ensemble tends to underestimate SAT in the Arctic when compared to available reconstructions. The simulations with the highest Arctic SAT anomalies tend to match the proxy dataset in its current form better. The ensemble shows some agreement with reconstructions of sea ice, particularly with regards to seasonal sea ice. Large uncertainties limit the confidence that can be placed in the findings and the compatibility of the different proxy datasets. We show that, while reducing uncertainties in the reconstructions could decrease the SAT data-model discord substantially, further improvements are likely to be found in enhanced boundary conditions or model physics. Lastly, we compare the Arctic warming in the mPWP to projections of future Arctic warming and find that the PlioMIP2 ensemble simulates greater Arctic amplification, an increase instead of a decrease in AMOC strength compared to pre-industrial, and a lesser strengthening of northern modes of variability than CMIP5 future climate simulations. The results highlight the importance of slow feedbacks in equilibrium climate simulations, and that caution must be taken when using simulations of the mPWP as an analogue for future climate change.

Delmonte, P., Belaunzaran, X., Ridge, C., Aldai, N., Kramer, J.K.G., 2020. Separation and characterization of products from acidic methanolysis of plasmalogenic lipids by two-dimensional gas chromatography with online reduction. Journal of Chromatography A 1619, 460955.


The complexity of determining the composition of animal tissue lipids is greatly increased by the presence of plasmalogens in which the alkyl chain is linked to glycerol by a vinyl ether bond instead of being esterified. Acidic methanolysis of animal tissue lipids provides the simultaneous scission of acyl and alkenyl ether moieties, but the complexity of the products of reaction poses a great challenge in their gas chromatographic analysis. Two-dimensional gas chromatography with online reduction (GC-OR × GC) provided the resolution of all components contained in acid methanolyzed animal lipids, taking advantage of the selective hydrogenation of alkenyl ether methanolysis products prior to the second-dimension separation (2D). In this study, we also studied the chemical transformations occurring during the acidic methanolysis of animal lipids and the subsequent gas chromatographic analysis. In particular, we observed that using methanolysis reagents contaminated with water resulted in the undesired formation of fatty aldehydes, and we made recommendations on how to avoid these side reactions using proper methanolysis conditions. Products of acidic methanolysis were studied by GC-OR × GC, GC-MS, NMR spectroscopy, and GC with flame ionization detection (GC-FID). We defined the GC-FID elution order of animal lipid acidic methanolysis products using 100 m x 0. 25 mm 100% bis(cyanopropyl)siloxane columns and two different set of elution conditions: isothermal elution at 180°C, and a temperature program optimized for dairy fats. A simple procedure for isolating dimethyl acetals (DMA) prior to GC analysis is also described.


https://doi.org/10.1111/1755-6724.14286

The Cenozoic continental strata of the Bohai Bay Basin are rich in shale oil resources, and they contain various types of reservoir spaces that are controlled by complex factors. Using field emission scanning electron microscopy (FESEM), automatic mineral identification and characterization system (AMICS), CO2 and N2 gas adsorption, and focused ion beam scanning electron microscopy (FIB SEM), ‐the types of shale reservoir spaces in the Bohai Bay Basin are summarized, the spatial distribution and connectivity of the various types of pores are described in detail, the microscopic pore structures are characterized, and the key geological mechanisms affecting the formation and evolution of the reservoir spaces are determined. Three conclusions can be drawn in the present study. First, the shale reservoir spaces in the Bohai Bay Basin can be divided into three broad categories, including mineral matrix pores, organic matter pores, and micro fractures. Those spaces can be subdivided into seven categories and fourteen sub categories based on the distribution and ‐formation mechanisms of the pores. Second, the complex pore throat structures of the shale ‐reservoir can be divided into two types based on the shape of the adsorption hysteresis loop. The pore structures mainly include wedge shaped, flat slit shaped, and ink bottle shaped pores. The ‐ ‐ ‐mesopores and micropores are the main contributors to pore volume and specific surface area, respectively. The macropores provide a portion of the pore volume, but they do not significantly contribute to the specific surface area. Third, the factors controlling the development of microscopic pores in the shale are complex. The sedimentary environment determines the composition and

structure of the shale and provides the material basis for pore development. Diagenesis controls the types and characteristics of the pores. In addition, the thermal evolution of the organic matter is closely related to inorganic diagenesis and drives the formation and evolution of the pores.

Dick, J.M., Yu, M., Tan, J., 2020. Uncovering chemical signatures of salinity gradients through compositional analysis of protein sequences. Biogeosciences Discussions 2020, 1-29.


Thermodynamic influences on the chemical compositions of proteins in nature have remained enigmatic despite much work that demonstrates the impact of environmental conditions on amino acid frequencies. Here, we present evidence that the dehydrating effect of salinity is detectable as chemical differences in protein sequences inferred from (1) metagenomes and metatranscriptomes in regional salinity gradients and (2) differential gene and protein expression in microbial cells under hyperosmotic stress. The stoichiometric hydration state (nH2O), derived from the number of water molecules in theoretical reactions to form proteins from a particular set of basis species (glutamine, glutamic acid, cysteine, O2, H2O), decreases along salinity gradients including the Baltic Sea and Amazon River and ocean plume and in particle-associated compared to free-living fractions. However, the proposed metric does not behave as expected for hypersaline environments. Analysis of data compiled for hyperosmotic stress experiments under controlled laboratory conditions shows that differentially expressed proteins, as well as proteins coded by differentially expressed transcripts, are on average shifted toward lower nH2O. Notably, the dehydration effect is stronger for most organic solutes compared to NaCl. This new method of compositional analysis can be used to identify possible thermodynamic effects in the distribution of proteins along chemical gradients at a range of scales from biofilms to oceans.


https://doi.org/10.1021/acs.est.0c01136

Dissolved organic matter (DOM) plays a key role in many biogeochemical processes, but the drivers controlling the diversity of chemical composition and properties of DOM molecules (chemodiversity) in soils are poorly understood. It has also been debated whether environmental conditions or intrinsic molecular properties control the accumulation and persistence of DOM due to the complexity of both molecular composition of DOM and interactions between DOM and surrounding environments. In this study, soil DOM samples were extracted from 33 soils collected from different regions of China, and we investigated the effects of climate and soil properties on the chemodiversity of DOM across different regions of China, employing a combination of Fourier transform ion cyclotron resonance mass spectrometry, optical spectroscopy, and statistical analyses. Our results indicated that, despite the heterogeneity of soil samples and complex influencing factors, aridity and clay can account for the majority of the variations of DOM chemical composition. The finding implied that DOM chemodiversity is an ecosystem property closely related to the environment, and can be used in developing large-scale soil biogeochemistry models for predicting C cycling in soils.



As a novelty, the combination of headspace solid phase microextraction and gas chromatography coupled to an Orbitrap mass analyzer in full scan mode (HS-SPME-GC-Orbitrap-MS) was evaluated for the monitoring of organic pollutants in wastewaters. The developed methodology showed good linearity (R2> 0.999), sensitivity as well as suitable relative recoveries (89-115%) and precision values (RSD= 1-16 %) for 15 polycyclic aromatic hydrocarbons (PAHs) selected as target compounds. Naphthalene, acenapthene and phenanthrene were found in the analyzed samples (influent and effluent wastewaters). Naphthalene was present in 62 % of them, ranging from 1.33 to 24.32 ng L−1. Acenapthene was observed in 1 single sample (4.17 ng L−1) while phenanthrene was found in 7 samples (1.51-8.67 ng L−1).

In addition, in order to identify other pollutants in the samples, retrospective analyses were addressed through target and non-target screenings. An in-house database containing close to 1,000 pollutants including, among others, polychlorinated biphenyls (PCBs), diphenyl ethers (BDEs) and pesticides was applied in the post-target analysis. For the non-target screening, after a deconvolution process, high resolution filtering (HRF) and Kovats retention index (KI) were used for tentative analyte identification. Thus, 51 additional pollutants were tentatively identified in the wastewaters, most of them used as flavoring agents and household product ingredients, highlighting the presence of linear alkyl benzenes (LABs).



The contribution and impact of combined laser ablation inductively coupled plasma time-of-flight mass spectrometry (LA-ICP-TOF-MS) and laser-induced breakdown spectroscopy (LIBS) were evaluated for the discrimination analysis of different coal samples. This tandem approach allows simultaneous determination of major and minor elements (C, H, Si, Ca, Al, Mg, etc.) and trace elements (V, Ba, Pb, U, etc.) in the coal. The research focused on coal-classification strategies based on principle component analysis (PCA) combined with K-means clustering, partial least-squares discrimination analysis (PLS-DA), and support vector machine (SVM) for analytical performance. Correlation analyses performed from TOF mass and LIBS emission spectra from the coal samples showed that most major, minor, and trace element emissions had negative correlation with the volatile content. Suitable variables for the classification models were determined from these data. The individual TOF data, LIBS data, and combined data of TOF and LIBS as the inputs for different models were analyzed and compared. In all cases, the results obtained with the combined TOF and LIBS data were found to be superior to those obtained with the individual TOF or LIBS data. The nonlinear SVM model combined with TOF and LIBS data provided the best coal-classification performance, with a classification accuracy of up to 98%.



Successful designs of the enhanced oil recovery operation and production forecasts require careful characterization of the reservoir rocks’ pore structures and fluids within. In contrary to the commonly adopted assumptions, strengths of the bonding forces resisting fluid displacement in tight sands do not necessarily correlate with the pore sizes. Free fluid (FF) exists across pores of a broad spectrum of sizes and vice versa; fluids bonded firmly to the pore surface by capillary force (i.e., capillary bound fluid, CAF) and electrochemical forces (i.e., clay bound fluid, CBF) may exist in larger pores too; this brings the need of laboratory experiments, particularly at an environment similar to that in-situ. Here, we investigate the pore size distribution and fluid movement in tight sand samples. Fluids in the fully saturated samples are removed sequentially via centrifugation and thermal treatment. NMR responses measured during this process allows the establishment of the characteristic T2 curves of TFF, TCAF, and TCBF. We compare these curves with the T2 curves measured during cycles of a laboratory-scale CO2 HnP (huff-n-puff) experiments to assess the recovery rate against fluid types and pore sizes. Low field NMR experiments allow us to investigate the fluid displacements across pores of different sizes, represented by the T2 relaxation times, at pressurized environments. Through these experiments, we found most FF, including those stored in medium/small-sized pores, are recovered within the first two cycles along with significant CAF from small to medium pores; no displacement of CBF is observed.



Geogenic ammonium in groundwater owing to mineralization of natural organic matter (NOM) has been reported in different geologic settings, but detailed mechanisms responsible for high ammonium concentration levels are poorly understood. To this end, we chose Quaternary high ammonium aquifer systems in central Yangtze River basins and used carbon isotopes in both dissolved organic carbon and inorganic carbon together with characterization of dissolved organic matter (DOM) and groundwater chemistry to reveal mechanisms related to the genesis of ammonium. The results indicate that high levels of geogenic ammonium (up to 33.50 mg/L as N) occur due to long-term water–rock interactions in a relatively sluggish hydrogeological environment with abundant organic matter that is rich in both C and N. The stable carbon isotope data suggest that ammonium in the groundwater is released from intensive degradation of organic matter with higher contents of ammonium associated with methanogenesis. The optical signatures of DOM indicate ammonium in the groundwater is mostly associated with terrestrial humic-like components rather than protein-like components. Molecular characterization of DOM by Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) shows that, compared to low ammonium groundwater, high ammonium groundwater has larger mass weights, greater abundance of CHO+N compounds, higher percentages of lignin- and condensed-hydrocarbon-like components, lower H/C ratios, higher nominal oxidation state of carbon (NOSC) values and more double bonds, rings, and aromatic structures. Strong degradation of NOM and preferential utilization of energetically more

favorable, terrestrial humic-like components (lignin-like as the main class) with high NOSC values facilitates the formation of high ammonium groundwater. To the best of our knowledge, this is the first effort to use carbon isotopes and DOM characteristics to identify enrichment mechanisms for geogenic ammonium in alluvial–lacustrine aquifer systems.



Gas chromatography-mass spectrometry (GC-MS) is a robust analytical platform for analysis of small molecules. Recently, it is widely used for large-scale metabolomics studies, in which hundreds or even thousands of samples are analyzed simultaneously, producing a very large and complex GC-MS datasets. A number of software are currently available for processing GC-MS data, but it is too compute-intensive for them to efficiently and accurately align chromatographic peaks from thousands of samples. Here, we report a newly developed software, QPMASS, for analysis of large-scale GC-MS data. The parallel computing with an advanced dynamic programming approach is implemented in QPMASS to align peaks from multiple samples based on retention time and mass spectra, enabling fast processing large-scale datasets. Furthermore, the missing value filtering and backfilling are introduced into the program, greatly reducing false positive and false negative errors to be less than 5%. We demonstrated that it took only 8 h to align and quantify a GC-TOF-MS dataset from 300 rice leaves samples, and 17 h to process a GC-qMS dataset from 1000 rice seed samples by using a personal computer (3.70 GHz CPU, 16 GB of memory and > 100 GB hard disk). QPMASS is written in C++ programming language, and is able to run under Windows operation system with a user-friendly interface.

Duan, L., Qu, L., Xia, Z., Liu, L., Wang, J., 2020. Stochastic modeling for estimating coalbed methane resources. Energy & Fuels 34, 5196-5204.


In this paper, an integrated workflow was developed to estimate coalbed methane (CBM) probabilistic resources. This workflow captures all of the uncertainty parameters in CBM modeling, including the structural surface and coal thickness in the structural modeling and the coal facies, logging density, etc. in the property modeling. These uncertainties were statistically analyzed and quantified. Sensitivity analysis was carried out to rank the impact of these parameters on the resources, and six sensitive parameters were chosen. Then, multiple stochastic models were generated using the aforementioned six parameters to determine the resource distribution, from which the P90, P50, and P10 resources were chosen. Finally, the low, middle, and high probabilistic models corresponding to these three probabilistic resources were attained. This workflow was applied to a CBM field in Australia, and the simulated results show that for the low, middle, and high probabilistic resource models the resources are always high in the central and western part of the study area.



The pyrolysis of solid fossil fuels and biomass is of great relevance, because it influences the combustion kinetics of these fuels, and the pyrolysis products are potential raw materials for further chemical processing. The aim of this work was to develop a pyrolysis system able to separate the whole variety of pyrolysis products during one pyrolysis experiment without the need to replace GC columns for improved resolution. A conventional pyrolysis system equipped with a coupled gas chromatography (GC)/mass spectrometry (MS) detector was extended by a second GC with a fused-silica capillary column and a thermal conductivity detector (TCD). The coupled pyrolysis-GC/MS-GC/TCD system was used to investigate the evolved pyrolysis products of two lignites and a hard coal enabling the qualitative detection of pyrolyzates (GC/MS) while simultaneously quantifying the light gases (TCD). Benzofuran, catechol, and a preference for even-numbered hydrocarbon pyrolyzates in addition to a higher pristene/heptadecane ratio were found to be characteristic for the two studied German lignites in comparison to the Columbian hard coal as well as a higher release of especially oxygen-containing light gases.


https://doi.org/10.1021/acscentsci.0c00050

The cellulosome is a supramolecular multienzymatic protein complex that functions as a biological nanomachine of cellulosic biomass degradation. How the megadalton-size cellulosome adapts to a solid substrate is central to its mechanism of action and is also key for its efficient use in bioconversion applications. We report time-lapse visualization of crystalline cellulose degradation by individual cellulosomes from Clostridium thermocellum by atomic force microscopy. Upon binding to cellulose, the cellulosomes switch to elongated, even filamentous shapes and morph these dynamically at below 1 min time scale according to requirements of the substrate surface under attack. Compared with noncomplexed cellulases that peel off material while sliding along crystalline cellulose surfaces, the cellulosomes remain bound locally for minutes and remove the material lying underneath. The consequent roughening up of the surface leads to an efficient deconstruction of cellulose nanocrystals both from the ends and through fissions within. Distinct modes of cellulose nanocrystal deconstruction by nature’s major cellulase systems are thus revealed.


https://doi.org/10.1038/s41598-020-65389-z

The potentials of the invasive duckweed species, Lemna paucicostata to remove pollutants from aquatic environment was tested in a constructed wetlands as an ecological based system for the phytoremediation of petroleum hydrocarbons in crude oil-contaminated waters within 120 days. Total petroleum hydrocarbons in wetlands and tissues of duckweed were analyzed using gas

chromatography with flame ionization detector following established methods while the experimental data were subjected to the first-order kinetic rate model to understand the remediation rate of duckweed in wetlands. L. paucicostata effected a significant (F = 253.405, P < 0.05) removal of hydrocarbons from wetlands reaching 97.91% after 120 days. Assessment on the transport and fate of hydrocarbons in duckweed indicated that L. paucicostata bioaccumulated less than 1% and significantly biodegraded 97.74% of hydrocarbons in wetlands at the end of the study. The experimental data reasonably fitted (r2 = 0.938) into the first-order kinetic rate model. From the result of the study, it is reasonable to infer that L. paucicostata is an effective aquatic macrophyte for the removal of petroleum hydrocarbons in moderately polluted waters.

Elardo, S.M., Laneuville, M., McCubbin, F.M., Shearer, C.K., 2020. Early crust building enhanced on the Moon’s nearside by mantle melting-point depression. Nature Geoscience 13, 339-343.

https://doi.org/10.1038/s41561-020-0559-4

The Moon’s Earth-facing hemisphere hosts a geochemically anomalous region, the Procellarum KREEP Terrane, which is widely thought to have provided radiogenic heat for mantle melting from ~3.9 to ~1 billion years ago. However, there is no agreement on such a link between this region and the earliest pulse of post-differentiation crust-building magmatism on the Moon at ~4.37 billion years ago; whether this early magmatism was global or regional has been debated. Here we present results of high-temperature experiments that show the nearside geochemical anomaly may have caused asymmetric early crust building via mantle melting-point depression. Our results demonstrate that the anomalous enrichment in incompatible elements of this nearside reservoir dramatically lowers the melting temperature of the source rock for these magmas and may have resulted in 4 to 13 times more magma production under the nearside crust, even without any contribution from radioactivity. From thermal numerical modelling, we show that radiogenic heating compounds this effect and may have resulted in an asymmetric concentration of post-magma-ocean crust building on the lunar nearside. Our findings suggest that the nearside geochemical anomaly has influenced the thermal and magmatic evolution of the Moon over its entire post-differentiation history.



This study proposes a novel approach to investigate the diffusion-limited deposition of asphaltenes in flow lines to better understand their nanoscale behavior at interfaces and aid in the development of more accurate remediation methods and modeling tools. Experiments were first designed by flowing asphaltene-in-toluene solutions through capillary polyetheretherketone tubes and imaging their cross-sectional areas using high-resolution scanning electron microscopy. A two-step digital image analysis using machine-learning concepts was applied and consisted of a (1) denoising process by analyzing the local and global bias and variance and (2) binarization process to improve the quality of image segmentation. As a result of polydispersity, particles on the tube surface were categorized into nanoaggregates (1.5–4 nm), small clusters (SCs, 4–10 nm), medium clusters (MCs, 10–20 nm), large clusters (LCs, 20–100 nm), and extra-large clusters (XLCs, >100 nm). A Langmuir adsorption isotherm was measured in toluene with an adsorption free energy of −29 kJ/mol, in

agreement with previous work. Nanoaggregates and SCs were the main constituents of the adsorption layer as a result of their high mass diffusivity. A competing behavior between aggregation and adsorption was observed as the asphaltene concentration increased in toluene. Enhanced self-assembly in the bulk phase led to a continuous decrease in the number of adsorbed particles. Adding n-heptane to toluene at different volume ratios prompted the deposition of MCs with a peak in the particle size, number, and mass density observed in the vicinity of the onset of precipitation. These clusters are potential precursors to fouling because they constitute the building blocks of larger particles that grow over time on the surface. Limiting their deposition could be achieved by either increasing the flow rate or introducing chemical inhibitors that promote the formation of larger aggregates in the bulk phase under given flow conditions. The novel insights gained from this study reveal that MC-rich petroleum fluids are more prone to flow assurance challenges and that effective flow enhancers are those that promote the aggregation of MCs into particles that are too large to deposit.

Enrico, M., Mere, A., Zhou, H., Carrier, H., Tessier, E., Bouyssiere, B., 2020. Experimental tests of natural gas samplers prior to mercury concentration analysis. Energy & Fuels 34, 5205-5212.


Mercury (Hg) is a natural, trace component of natural gas. Corrosion of aluminum heat exchangers by liquid metallic Hg can lead to dramatic issues. The quantification of the gaseous Hg concentration in natural gas streams is therefore crucial prior to the implementation of Hg removal units for preventing the formation of liquid Hg. Different methodologies exist for the determination of the Hg concentration in natural gas, one of which relies on the sampling of natural gas at high pressure using stainless-steel cylinders prior to off-site Hg measurement. An inert internal coating is supposed to hamper Hg adsorption, presumably making the Hg analysis reliable. Here, we challenge this statement by showing that even silicon-coated cylinders are inefficient for preventing Hg adsorption on internal walls. Different cylinders were tested for gaseous Hg concentration stability over time in a clean argon matrix. We find that the gaseous Hg concentration sharply declines in almost all tested cylinders (uncoated, polytetrafluoroethylene-coated, and silicon-coated) to reach undetectable levels within a day or two as a result of adsorption, with the notable exception of a brand new silicon-coated cylinder. Heating cylinders up to 190 °C allowed for the recovery of most adsorbed Hg and revealed the occurrence of two distinct Hg species with distinct release temperatures. Our results suggest that Hg0 is first physically adsorbed and further oxidized, presumably in relation to sulfur compounds covering the internal walls of the cylinders. The newly purchased silicon-coated cylinder kept a constant gaseous Hg concentration over 6 months because it never interacted with any real natural gas sample containing substantial sulfur concentrations relative to Hg.

Enriquez, D.A., Zhang, T., Sun, X., Meng, D., Zhang, Y., 2020. Methane resaturation in Barnett Formation core plugs and new approach for determination of post-coring gas loss. Marine and Petroleum Geology 118, 104430.


Understanding the physiochemical mechanisms that control the loss of gas during coring processes is critical to accurately determining gas-in-place (GIP) resource assessments of unconventional shale-gas plays. Our study uses an experimental approach, utilizing methane (CH4) adsorption

isotherms and degassing curves of methane-resaturated Barnett Formation core plugs, to determine the amount of lost-gas based on mass-balance analysis at different CH4 re-saturation pressures and varied exposure times. Several readily available empirical methods for estimating lost-gas were evaluated, quantified, and compared with the mass balance–derived lost-gas values in our experiments.

A CH4 isotherm measurement on 3/8-inch Barnett Formation core plugs was performed at 35.4 °C; the amount of gas adsorbed in excess was then quantified and fitted to the modified Langmuir equation to determine the Langmuir maximum, Langmuir constant, and adsorbed gas-phase density. Two sets of CH4 gas-resaturation and degassing measurements, one varying saturation pressures and the other varying exposure times, were performed on 3/8-inch Barnett Formation core-plugs at an isothermal temperature of 35.4 °C. Degassing curves, the plot of the released gas yield versus the square root of degassing time, display three stages that correspond to different gas-releasing mechanisms. The rapid increase of released gas yield at the beginning of degassing represents that nonlinear gas expansion is dominant and that degassing evolves into a linear desorption-dominated phase over time. Experimentally derived values for lost gas were determined by subtracting the sum of the desorbed and retained gas at the peak of the degassing curve from the amount of gas initially charged into the samples at equilibrated resaturation pressure. Lost gas varies linearly with increasing gas-resaturation pressure and nonlinearly by a greater magnitude with increasing exposure time, indicating that lost gas is more sensitive to exposure time.

The uncertainty evaluation of lost gas determined by three empirical methods was conducted by direct comparison with mass-balance-derived lost-gas values from our experiment. Nonlinear least-squares extrapolation overestimates, and both linear extrapolation and polynomial equation fitting underestimate, mass-balance lost-gas control points. Among the three empirical methods, the polynomial-fitted lost-gas values most closely agree with mass-balance lost gas, revealing that polynomial fitting to degassing curves is a viable way to accurately estimate lost gas and, more importantly, to estimate GIP values with up to 85% accuracy. As free gas is the dominant storage mechanism in the Barnett Formation, the trends of experimentally measured cumulative desorbed gas content versus the square root of elapsed time match neither the calculated curves derived from USBM Direct Method nor Amoco Method.

Enyedi, N.T., Makk, J., Kótai, L., Berényi, B., Klébert, S., Sebestyén, Z., Molnár, Z., Borsodi, A.K., Leél-Őssy, S., Demény, A., Németh, P., 2020. Cave bacteria-induced amorphous calcium carbonate formation. Scientific Reports 10, 8696.

https://doi.org/10.1038/s41598-020-65667-w

Amorphous calcium carbonate (ACC) is a precursor of crystalline calcium carbonates that plays a key role in biomineralization and polymorph evolution. Here, we show that several bacterial strains isolated from a Hungarian cave produce ACC and their extracellular polymeric substance (EPS) shields ACC from crystallization. The findings demonstrate that bacteria-produced ACC forms in water-rich environment at room temperature and is stable for at least half year, which is in contrast to laboratory-produced ACC that needs to be stored in a desiccator and kept below 10 °C for avoiding crystallization. The ACC-shielding EPS consists of lipids, proteins, carbohydrates and nucleic acids. In particular, we identified large amount of long-chain fatty acid components. We suggest that ACC could be enclosed in a micella-like formula within the EPS that inhibits water infiltration. As the bacterial cells lyse, the covering protective layer disintegrates, water penetrates and the

unprotected ACC grains crystallize to calcite. Our study indicates that bacteria are capable of producing ACC, and we estimate its quantity in comparison to calcite presumably varies up to 20% depending on the age of the colony. Since diverse bacterial communities colonize the surface of cave sediments in temperate zone, we presume that ACC is common in these caves and its occurrence is directly linked to bacterial activity and influences the geochemical signals recorded in speleothems.

Erba, E., Signor, L., Petosa, C., 2020. Exploring the structure and dynamics of macromolecular complexes by native mass spectrometry. Journal of Proteomics 222, 103799.


Mass spectrometry (MS) is an effective approach for determining the mass of biomolecules with high accuracy, sensitivity and speed. Over the past 25 years, MS performed under non-denaturing conditions (“native MS”) has been successfully exploited to investigate non-covalently associated biomolecules. Here we illustrate native MS applications aimed at studying protein-ligand interactions and structures of biomolecular assemblies, including both soluble and membrane protein complexes. Moreover, we review how the partial dissociation of holo-complexes can be used to determine the stoichiometry of subunits and their topology. We also describe “native top-down MS”, an approach based on Fourier Transform MS (FT MS), whereby non-covalent interactions are preserved while covalent bonds are selectively fragmented. Overall, native MS plays an increasingly important role in integrative structural biology, helping researchers to elucidate the three dimensional architecture of intricate macromolecular complexes.

Eronat, A.H., 2020. Time series evaluation of oil spill in marine environment: a case study in marine area of Cyprus. Arabian Journal of Geosciences 13, 365.

https://doi.org/10.1007/s12517-020-05388-6

The eastern Levantine Sea is known as one of the illegal discharge regions of the world. Nevertheless, the coastal waters of Cyprus are famous for its crystal clear oligotrophic waters in spite of the fact that its exposure to high pollution pressure is due mainly to the intensive touristic and maritime activities. This study aimed to evaluate and understand the oil spill dynamics in the marine area surrounding Cyprus over a period of 18 months between January 2017 and June 2018. A practical method utilizing multiple products of satellite remote-sensing was used to detect and evaluate oil spill events in the study area. A total of 122 images were available for the study period. Results showed that average coverage per sampling days was 0.10%. A small portion of the study area, which is 0.05%, showed relatively intense oil spill detection. However, none of the region showed constant reoccurrence of oil spill detection. The analysis showed that the marine area has a low oil spill intensity. Additionally, intensity and reoccurrence of oil spill events are relatively higher in the main ports of Cyprus and the main routes of maritime traffic. It is concluded that continuous monitoring of oil spill detection in the marine areas will provide an important contribution to implement effective management plans by increasing understanding of impacts on marine ecosystem. It is also provide a baseline for detection and implementation of precautionary or recovery actions of any possible oil spill accident in high- or low-risk zones.

Esegbue, O., Jones, M., van Bergen, P.F., Kolonic, S., 2020. Quantitative diamondoid analysis indicates oil cosourcing from a deep petroleum system onshore Niger Delta Basin. American Association of Petroleum Geologists Bulletin 104, 1231-1259.


The Niger Delta Basin is one of the most prolific hydrocarbon provinces in the world, yet the origin of the vast amounts of oil and gas found in the numerous subbasins across the delta remains contested. A total of 180 oil samples from more than 40 oil fields in the Niger Delta were analyzed by gas chromatography (GC) and GC–mass spectrometry, and selected samples were analyzed by GC–tandem mass spectrometry.

The interpreted thermal maturity and source depositional environments of these hydrocarbons show significant variation depending on the components analyzed and allow no clear correlation to a single source rock but rather imply extensive mixed contributions. Diamondoid hydrocarbon parameters were used for the first time on these Paleogene–Neogene reservoired oils to investigate source, thermal maturity, and mixing effects and perform cross correlations of these oils. The diamondoid abundances and distributions support the hypothesis of cosourcing of oil from a thermally cracked, subdelta, type II marine source, which was then mixed with oils of relatively lower maturities in the Paleogene–Neogene reservoirs.

Future geochemical interpretations should treat the Niger Delta oils as potential mixtures of oils of variable maturities from different sources, commonly with the most important source biomarkers depleted because of the extent of thermal cracking.

Fan, K., Sun, R., Elsworth, D., Dong, M., Li, Y., Yin, C., Li, Y., Chen, Z., Wang, C., 2020. Radial permeability measurements for shale using variable pressure gradients. Acta Geologica Sinica - English Edition 94, 269-279.

https://doi.org/10.1111/1755-6724.14304

Shale gas is becoming an important component of the global energy supply, with permeability a critical controlling factor for long term gas production. Obvious deviation may exist between helium ‐permeability determined using small pressure gradient (SPG) methods and methane permeability obtained under actual field production with variable pressure gradients (VPG). In order to more accurately evaluate the matrix permeability of shale, a VPG method using real gas (rather than He) is established to render permeability measurements that are more representative of reservoir conditions and hence response. Dynamic methane production experiments were performed to measure permeability using the annular space in the shale cores. For each production stage, boundary pressure is maintained at a constant and the gas production with time is measured on the basis of volume change history in the measuring pump. A mathematical model explicitly accommodating gas desorption uses pseudo pressure and pseudo time to accommodate the effects‐ ‐ of variations in pressure dependent PVT parameters. Analytical and semi analytical solutions to the ‐ ‐model are obtained and discussed. These provide a convenient approach to estimate radial permeability in the core by nonlinear fitting to match the semi analytical solution with the recorded ‐gas production data. Results indicate that the radial permeability of the shale determined using methane is in the range of 1×10−6 – 1×10−5 mD and decreases with a decrease in average pore pressure. This is contrary to the observed change in permeability estimated using helium. Bedding

geometry has a significant influence on shale permeability with permeability in parallel bedding orientation larger than that in perpendicular bedding orientation. The superiority of the VPG method is confirmed by comparing permeability test results obtained from both VPG and SPG methods. Although several assumptions are used, the results obtained from the VPG method with reservoir gas are much closer to reality and may be directly used for actual gas production evaluation and prediction, through accommodating realistic pressure dependent impacts.

Fan, X., Mao, X., Liu, Z., Geng, T., Wang, H., 2020. Organic geochemical characteristics and hydrocarbon generation potential of Jurassic shales and mudstones in Qixiang Co area southern Qiangtang Basin, Tibet. Journal of Petroleum Science and Engineering 193, 107377.


The Qixiang Co area is located in the South Qiangtang Depression Zone. Jurassic shales and mudstones with large thicknesses are widely developed in this area. The Jurassic was a potential exploration horizon in the Qiangtang Basin; however, few detailed analyses have been conducted on the geochemical characteristics of mudstones and shales in this area. In this paper, the hydrocarbon generation potential and sedimentary environment of shales and mudstones are analyzed using organic geochemical data. The results show that the abundance of organic matter is low, as indicated by the low TOC value (averaging 0.70%) and hydrocarbon potential (S1+S2) (0.13 mg/g). The main macerals of kerogen are exinites with an average value of 82%, and they are mainly type II2

kerogen. A summary of the results is presented: the thermal maturity of organic matter is high; the average Ro value is more than 1.2%; n-alkanes are dominated by a high carbon number and have no obvious odd-even advantage; the average value of Pr/Ph is 0.74; the distribution of C23 triterpenoids satisfies C20< C21< C23; the content of the gammacerane index is moderate (0.21) the variation range is small; and the C27 content in regular steranes is dominant. It can be concluded that the organic matter precursors in this area were a mix of higher plants and marine phytoplankton. Organic matter was deposited under a reductive environment with stable water and slightly high salinity. The hydrocarbon generation potential of the Jurassic shale and mudstone in this area is poor, which is unfavorable to oil and gas exploration.

Fang, Z., Huang, R., How, Z.T., Jiang, B., Chelme-Ayala, P., Shi, Q., Xu, C., El-Din, M.G., 2020. Molecular transformation of dissolved organic matter in process water from oil and gas operation during UV/H2O2, UV/chlorine, and UV/persulfate processes. Science of The Total Environment 730, 139072.


This paper reported the impact of UV/H2O2, UV/chlorine, and UV/persulfate advanced oxidation processes on the molecular transformations of dissolved organic matter (DOM), removal of naphthenic acids (NAs) and acute toxicity in oil sands process water (OSPW). The UV/persulfate process exhibited the highest removal (81.2% with 2 mM dose) towards classical NAs and highest reduction in acute toxicity to Vibrio fischeri among the three processes. The fraction of DOM such as CHOS class species decreased along with the increase of the oxidant doses in all processes. The increase in O/C ratio and lack of change in the H/C and double bond equivalence indicated that H-abstraction followed by the OH-addition was main reaction pathway for all processes. This observation aligned with previous studies using model compounds and proved that OSPW DOM reacted similarly to model compounds. Sulfur containing organic matters were the most liable

compounds in OSPW NOM, while UV/chlorine was the most effective process to oxidize nitrogen containing organic matters. Overall results revealed that the UV/persulfate process could be used as a promising technique for the removal of OSPW NA and reduction of acute toxicity towards Vibrio fischeri. In addition, this DOM characterization approach could be utilized to investigate the transformation of complicated OSPW DOM and to identify the byproducts generated during different water treatment processes.


https://doi.org/10.1038/s41396-020-0615-5

Numerous archaeal lineages are known to inhabit marine subsurface sediments, although their distributions, metabolic capacities, and interspecies interactions are still not well understood. Abundant and diverse archaea were recently reported in Costa Rica (CR) margin subseafloor sediments recovered during IODP Expedition 334. Here, we recover metagenome-assembled genomes (MAGs) of archaea from the CR margin and compare them to their relatives from shallower settings. We describe 31 MAGs of six different archaeal lineages (Lokiarchaeota, Thorarchaeota, Heimdallarchaeota, Bathyarcheota, Thermoplasmatales, and Hadesarchaea) and thoroughly analyze representative MAGs from the phyla Lokiarchaeota and Bathyarchaeota. Our analysis suggests the potential capability of Lokiarchaeota members to anaerobically degrade aliphatic and aromatic hydrocarbons. We show it is genetically possible and energetically feasible for Lokiarchaeota to degrade benzoate if they associate with organisms using nitrate, nitrite, and sulfite as electron acceptors, which suggests a possibility of syntrophic relationships between Lokiarchaeota and nitrite and sulfite reducing bacteria. The novel Bathyarchaeota lineage possesses an incomplete methanogenesis pathway lacking the methyl coenzyme M reductase complex and encodes a noncanonical acetogenic pathway potentially coupling methylotrophy to acetogenesis via the methyl branch of Wood–Ljungdahl pathway. These metabolic characteristics suggest the potential of this Bathyarchaeota lineage to be a transition between methanogenic and acetogenic Bathyarchaeota lineages. This work expands our knowledge about the metabolic functional repertoire of marine benthic archaea.

Faulk, S.P., Lora, J.M., Mitchell, J.L., Milly, P.C.D., 2020. Titan’s climate patterns and surface methane distribution due to the coupling of land hydrology and atmosphere. Nature Astronomy 4, 390-398.

https://doi.org/10.1038/s41550-019-0963-0

Planetary surfaces beyond Earth’s are impacted by surface hydrology, and exhibit fluvial and lacustrine features. Titan in particular harbours a rich hydroclimate replete with valley networks, lakes, seas and putative wetlands, all of which are pronounced in the lower-elevation polar regions. However, understanding of Titan’s global climate has heretofore neglected the hydraulic influence of Titan’s large-scale topography. Here we add a surface hydrology model to an existing Titan atmospheric model, and find that infiltration, groundmethane evaporation, and surface and subsurface flow are fundamental to simultaneously reproducing Titan’s observed surface liquid distribution and other aspects of its climate system. We propose that Titan’s climate features infiltration into unsaturated low- and mid-latitude highlands and surface or subsurface flow into

high-latitude basins, producing the observed polar moist climes and equatorial deserts. This result implies that a potentially massive unobserved methane reservoir participates in Titan’s methane cycle. It also illustrates the importance of surface hydrology in Titan climate models, and by extension suggests the influence of surface hydrology in idealized models of other planetary climates, including the climates and palaeoclimates of Earth, Mars and exoplanets.

Fauziah, C.A., Al-Yaseri, A.Z., Jha, N.K., Lagat, C., Roshan, H., Barifcani, A., Iglauer, S., 2020. Carbon dioxide wettability of South West Hub sandstone, Western Australia: Implications for carbon geo-storage. International Journal of Greenhouse Gas Control 98, 103064.


CO2-rock wettability is a key factor which determines the fluid dynamics and CO2 geo-storage capacity. However, the full understanding of real reservoir CO2-wettability is yet to be gained. We thus systematically analysed the wettability of CO2/brine/South West Hub sandstones at various pressures (0.1 MPa, 5 MPa, 10 MPa, 15 MPa, and 20 MPa) at 334 K. A new procedure based on organic carbon isotope tracking (δ13Corg) was proposed to eliminate the effect of artificial organic matter introduced by drilling mud penetration. The results indicate that the advancing (θa) and receding (θr) water contact angles for the CO2/brine/South West Hub sandstone system increase with increase in pressure (ranging from 71° to 118° and 66° to 111°). It can thus be suggested that the system is weakly water-wet to intermediate-wet. When the samples were treated with dichloromethane, a slight decline in organic content was observed leading to slight decrease in water contact angles (i.e. TOC decreased from 0.019% to 0.003% for core C, and the corresponding θa and θr decreased from 118° and 111° to 110° and 104°, respectively, at 20 MPa and 334 K). This wettability analysis demonstrates that (a) of the contact angle is very sensitive to the amount of organic matter and therefore care should be taken to remove artificial organic matter from the sample, and that (b) this condition prevails in a real proposed CO2-storage site. This analysis thus has important implications for assessing the feasibility of long-term CO2 storage and enabling large-scale industrial carbon geological storage projects.



The deep Longmaxi Formation shale in the Zigong area is widely distributed and has a huge resource potential, which has enabled it to become one of the most important replacement areas for shale gas exploration in China. This article investigates the key shale gas evaluation well, Well Z1, in the Zigong area using field emission-scanning electron microscopy, mercury intrusion capillary pressure, low-pressure N2/CO2 adsorption, and fractal theory to determine the pore systems of the different lithofacies of the deep O3w–S1l shale. The mineral composition and total organic carbon (TOC) content (1.79%– 8.16%/3.48%) are highly heterogeneous, and five types of shale lithofacies including mixed shale, mixed siliceous, clay-rich siliceous, argillaceous/siliceous shale, and mixed carbonate shale were identified. The deep shale mainly develops interpores and microcracks associated with the organic matter (OM)–mineral (carbonate, pyrite, and clay minerals) aggregates and a small number of mud pores. The surface areas and total pore volume vary from 16.29 to 41.76

m2/g and from 1.19 to 3.49 cm3/100 g, with averages of 25.03 m2/g and 1.99 cm3/100 g, respectively. The pore distribution exhibits significant multimodal and fractal characteristics. The distribution morphology, peak values, and fractal dimensions vary with lithofacies. The mesopores provide the main pore volume (average of 53.99%), and the micropores provide the main surface area (average of 73.95%). The TOC content and biogenic quartz are beneficial to the development of micro- and mesopores. In the Zigong area, mineral aggregates composed of OM and brittle minerals (quartz, feldspar, and carbonate) are more favorable for pore development than the clay mineral–brittle mineral aggregates.

Figueirêdo, M.B., Venderbosch, R.H., Heeres, H.J., Deuss, P.J., 2020. In-depth structural characterization of the lignin fraction of a pine-derived pyrolysis oil. Journal of Analytical and Applied Pyrolysis 149, 104837.


Pyrolytic lignin (PL) is the collective name of the water-insoluble fraction of pyrolysis oils produced from the fast pyrolysis of lignocellulosic biomass. As the name suggests, PL is composed by fragments derived from lignin, which is the largest natural source of aromatic carbon. Its valorization is of major importance for the realization of economically competitive biorefineries. Nonetheless, the valorization of PL is hindered by its complex structure, which makes the development of tailored strategies for its deconstruction into valuable compounds challenging. In this work, we provide an in-depth analysis of the structural composition of PL obtained from a commercially available pine-derived pyrolysis oil obtained at 500 °C (Empyro B.V., the Netherlands). Molecular weight distribution and thermal stability were accessed by GPC and TGA, respectively, and the monomers present in the PL (≈ 15 wt%) were identified and quantified by chromatographic analyses (GCxGC-FID, GCxGC/TOF-MS, GC-MS and HPLC). Together with FTIR, Py-GC-MS, TAN, elemental analysis and various advanced NMR techniques (13C-NMR, 31P-NMR, 19F-NMR, NMR HSQC, NMR HMBC), structural features of the PL oligomers were elucidated, revealing a guaiacyl backbone linked by alkyl, ether, ester and carbonyl groups, with none of the typical native lignin linkages (i.e. β-O-4, β-β, β-5) present. Furthermore, 72.3 % of the oxygen content in PL could be assigned to specific motifs by the quantitative analyses performed, and oligomeric models were proposed based on the obtained information. We expect that this characterization work can support future research on the development of valorization pathways for PL, allowing the feasible conversion of this promising feedstock into valuable biobased products with a wide range of possible applications, e.g. fuels, materials and specialty chemicals.

Findlay, A.J., Pellerin, A., Laufer, K., Jørgensen, B.B., 2020. Quantification of sulphide oxidation rates in marine sediment. Geochimica et Cosmochimica Acta 280, 441-452.


The marine sulphur cycle is driven by the reduction of sulphate to sulphide coupled to microbial decomposition of organic matter. The sulphide produced by sulphate reduction may either react with Fe or organic matter to be buried as pyrite or organic sulphur, respectively; or may be oxidised through different pathways and intermediates. The amount of sulphide that is oxidised in marine sediments is not well constrained, yet oxidative sulphur cycling has critical implications for hypoxic coastal waters and oxygen minimum zones, carbon mineralisation, microbial metabolism and the

interpretation of ancient and modern stable isotope signatures. Here, we present an experimental method to directly determine sulphide oxidation rates in undiluted marine sediment incubations. We find that sulphide oxidation rates in the top two centimetres of organic-rich coastal sediments were greater than rates of sulphide production through sulphate reduction and calculate that in the top 6 centimetres, up to 92 % of sulphide produced during sulphate reduction was reoxidised. The rates decreased steeply with depth, however, and sulphide oxidation to sulphate could no longer be quantified 10 cm below the seafloor. Fe oxides were the primary oxidant for sulphide and the sulphide oxidation rate was related to the amount and reactivity of the Fe minerals. These results provide important insights into the magnitude and processes of the sulphur cycle in marine sediments.

Flowers, R.M., Macdonald, F.A., Siddoway, C.S., Havranek, R., 2020. Diachronous development of Great Unconformities before Neoproterozoic Snowball Earth. Proceedings of the National Academy of Sciences 117, 10172-10180.


Significance: Erosion below the Great Unconformity has been interpreted as a global phenomenon associated with Snowball Earth. Geological relationships and thermochronologic data provide evidence that the bulk of erosion below the Great Unconformity in Colorado occurred prior to Cryogenian glaciation. We suggest that there are multiple, regionally diachronous Great Unconformities that are tectonic in origin.

Abstract: The Great Unconformity marks a major gap in the continental geological record, separating Precambrian basement from Phanerozoic sedimentary rocks. However, the timing, magnitude, spatial heterogeneity, and causes of the erosional event(s) and/or depositional hiatus that lead to its development are unknown. We present field relationships from the 1.07-Ga Pikes Peak batholith in Colorado that constrain the position of Cryogenian and Cambrian paleosurfaces below the Great Unconformity. Tavakaiv sandstone injectites with an age of ≥676 ± 26 Ma cut Pikes Peak granite. Injection of quartzose sediment in bulbous bodies indicates near-surface conditions during emplacement. Fractured, weathered wall rock around Tavakaiv bodies and intensely altered basement fragments within unweathered injectites imply still earlier regolith development. These observations provide evidence that the granite was exhumed and resided at the surface prior to sand injection, likely before the 717-Ma Sturtian glaciation for the climate appropriate for regolith formation over an extensive region of the paleolandscape. The 510-Ma Sawatch sandstone directly overlies Tavakaiv-injected Pikes granite and drapes over core stones in Pikes regolith, consistent with limited erosion between 717 and 510 Ma. Zircon (U-Th)/He dates for basement below the Great Unconformity are 975 to 46 Ma and are consistent with exhumation by 717 Ma. Our results provide evidence that most erosion below the Great Unconformity in Colorado occurred before the first Neoproterozoic Snowball Earth and therefore cannot be a product of glacial erosion. We propose that multiple Great Unconformities developed diachronously and represent regional tectonic features rather than a synchronous global phenomenon.

Fong, S.Y., Montoya Sánchez, N., de Klerk, A., 2020. Olefin saturation using asphaltenes as a hydrogen source. Energy & Fuels 34, 4534-4543.


To facilitate the pipeline transport of oilsands bitumen, bitumen viscosity must be decreased. Decreasing bitumen viscosity by whatever means adds to the production cost of bitumen. One of the low cost methods to decrease bitumen viscosity is mild thermal cracking by visbreaking. Thermally cracked products are potentially fouling in nature and the maximum olefin content of upgraded bitumen is limited by pipeline specifications to reduce risk of fouling. Hydrotreating is conventionally applied to treat cracked products. A process alternative to hydrotreating that does not require an external source of H2 was evaluated for application in partial bitumen upgrading processes that employ thermal conversion in conjunction with solvent deasphalting. The proposed olefin saturation process employs thermally induced hydrogen transfer from asphaltenes as a hydrogen source to saturate olefins in cracked naphtha. The process chemistry was demonstrated first using model olefin and hydrogen donor mixtures, then using model olefin and asphaltenes mixtures, and finally using industrially cracked naphtha and asphaltenes-rich material. The operating temperature range investigated was 250–350 °C. It was found that the main reactions of the olefins were (i) saturation, (ii) alkylation, (iii) dimerization, and (iv) double bond isomerization. The conversion of model naphtha and cracked naphtha with asphaltenes was comparable, indicating that the increased complexity of the cracked product did not measurably affect the olefin saturation. It was shown how the proposed process could be integrated in a solvent deasphalting process by replacing the asphaltenes stripper. It was possible to obtain 60 wt % 1-decene equivalent olefin conversion in a thermally cracked naphtha by reacting the cracked naphtha with asphaltenes in a 1:4 ratio at 350 °C for 3 h. The study aim was to show technical feasibility, and although a range of conditions was investigated, the study did not optimize the process.

Fontanals, N., Borrull, F., Marcé, R.M., 2020. Overview of mixed-mode ion-exchange materials in the extraction of organic compounds. Analytica Chimica Acta 1117, 89-107.


Mixed-mode ion-exchange materials, including silica-based, polymer-based and other supports, have been applied in sample treatment with different techniques, mainly solid-phase extraction, but also other microextraction techniques such as solid-phase microextraction, stir bar sorptive extraction and microextraction by packed sorbent. These materials are widespread because they conveniently combine capacity (through the reversed-phase interactions in the material backbone) and selectivity (through the specific ion-exchange interactions).

This review provides an overview of the advances and applications of mixed-mode ion-exchange materials for the extraction of organic compounds from complex matrices in environmental, food and biological samples. We summarise the different approaches used to prepare these materials and discuss the extraction protocols applied and the types of compounds and samples analysed based on different selected examples.

Fontorbe, G., Frings, P.J., De La Rocha, C.L., Hendry, K.R., Conley, D.J., 2020. Constraints on Earth system functioning at the Paleocene-Eocene Thermal Maximum from the marine silicon cycle. Paleoceanography and Paleoclimatology 35, e2020PA003873.

https://doi.org/10.1029/2020PA003873

The Paleocene Eocene Thermal Maximum (PETM, ca. 56 Ma) is marked by a negative carbon isotope‐ excursion (CIE) and increased global temperatures. The CIE is thought to result from the release of 13C depleted carbon, although the source(s) of carbon and triggers for its release, its rate of release, ‐and the mechanisms by which the Earth system recovered are all debated. Many of the proposed mechanisms for the onset and recovery phases of the PETM make testable predictions about the marine silica cycle, making silicon isotope records a promising tool to address open questions about the PETM. We analyzed silicon isotope ratios (δ30Si) in radiolarian tests and sponge spicules from the Western North Atlantic (ODP Site 1051) across the PETM. Radiolarian δ30Si decreases by 0.6‰ from a background of 1‰ coeval with the CIE, while sponge δ30Si remains consistent at 0.2‰. Using a box model to test the Si cycle response to various scenarios, we find the data are best explained by a weak silicate weathering feedback, implying the recovery was mostly driven by nondiatom organic carbon burial, the other major long term carbon sink. We find no resolvable evidence for a volcanic ‐trigger for carbon release, or for a change in regional oceanography. Better understanding of radiolarian Si isotope fractionation and more Si isotope records spanning the PETM are needed to confirm the global validity of these conclusions, but they highlight how the coupling between the silica and carbon cycles can be exploited to yield insight into the functioning of the Earth system.

Fosu, B.R., Subba, R., Peethambaran, R., Bhattacharya, S.K., Ghosh, P., 2020. Technical note: Developments and applications in triple oxygen isotope analysis of carbonates. ACS Earth and Space Chemistry 4, 702-710.

https://doi.org/10.1021/acsearthspacechem.9b00330

Triple oxygen isotope systematics has evolved as a powerful tool in understanding various earth system processes. It has proven reliable in assessing paleoenvironmental conditions from natural archives (e.g., waters, ice cores, biota, sediments, etc.) owing to recent advances in high-precision mass spectrometric analysis. Toward the standardization of triple oxygen isotope analyses in carbonates, we describe a procedure of high-precision Δ′17O analysis of carbonates by a two-step protocol: acid digestion of carbonates to evolve CO2 followed by the catalytic CO2–O2 exchange method. The Δ′17O values of a suite of carbonate reference materials and several carbonates of different origins have been determined with good precision (∼0.007‰). The accuracy of sample Δ′17O values is dependent on the accuracy of Δ′17O composition of the reference CO2 used in determining the effective fractionation (θs) in the experimental setup. The obtained Δ′17O values (λ = 0.528, versus VSMOW) for NBS18-CO2 (−0.119‰) and NBS19-CO2 (−0.169‰) show a difference of 0.050‰, similar to that obtained elsewhere via complete fluorination. The analyzed carbonates mostly conform to equilibrium mass-dependent fractionation laws, but we encountered a suite of samples from cold seeps, caves, and metasomatic environments that have Δ′17O values indicative of disequilibrium fractionation. We show that a combination of clumped isotope composition (Δ47) that provides estimates of formation temperature and triple oxygen isotope ratios in carbonates can help in reconstructing past environments, where paired carbonate data (δ13C−δ18O−Δ47–Δ′17O) and parent water data (δ17O−δ18O−Δ′17O) are particularly useful.

Fox, S., Gspandl, A., Wenng, F.M., 2020. Acceleration of amino acid racemization by isovaline: possible implications for homochirality and biosignature search. International Journal of Astrobiology 19, 276-282.

https://doi.org/10.1017/S1473550420000014

In nature, abiotically formed amino acids are usually racemic. However, this is not true for the α,α-dialkyl amino acid isovaline (Iva), which has an L-enantiomeric excess in some specimens of carbonaceous meteorites. On the early Earth and Mars, such meteorites were sources of amino acids, including Iva. Therefore, a connection may exist between the possible chiral influence of non-racemic Iva and the origin of biological homochirality. On the surface of a young terrestrial planet, amino acids can be chemically altered in many ways. For example, high temperatures from geothermal heating can lead to racemization. Four billion years ago, active volcanism and volcanic islands provided suitable conditions for such reactions and perhaps even for early microbial life on Earth. In the current study, we investigated the influence of D- and L-Iva on the thermal racemization of L-alanine (L-Ala) and L-2-aminobutyric acid (L-Abu) in a simulated hot volcanic environment. The amino acids were intercalated in the clay mineral calcium montmorillonite (SAz-1). While Iva was resistant to racemization, partial racemization was observed for Ala and Abu after 8 weeks at 150°C. The experimental results – for example, accelerated racemization in the presence of Iva and different influences of the Iva enantiomers – suggest that the amino acid molecules interacted with each other, possibly in hydrogen-bonded dimers. Accelerated racemization of amino acids could have been an obstacle to the development of homochirality. Besides, it is also detrimental to the use of homochirality as a biosignature, for example, in the search for microbial life on Mars.

Frederickson, J.A., Engel, M.H., Cifelli, R.L., 2020. Ontogenetic dietary shifts in Deinonychus antirrhopus (Theropoda; Dromaeosauridae): Insights into the ecology and social behavior of raptorial dinosaurs through stable isotope analysis. Palaeogeography, Palaeoclimatology, Palaeoecology 552, 109780.


The image of the highly intelligent, pack-hunting raptor has become engrained in scientific literature and popular works alike. First proposed to explain the relatively common co-occurrence of the large-bodied iguanodontian Tenontosaurus tilletti and the wolf-sized Deinonychus antirrhopus from the Lower Cretaceous of North America, a canid-like social hunting structure has become the standard depiction of dromaeosaurs in popular works over the last three decades. This reconstruction is, however, problematic largely due to the fact that highly coordinated hunting strategies are rarely observed in modern archosaurs. This has led to the alternative hypothesis that D. antirrhopus was more analogous to agonistic reptilian carnivores, like the Komodo dragon (Varanus komodoensis). Among the many differences between these two analogs is how social and asocial organisms rear their young, producing a diagnostic pattern based on the presence or absence of ontogenetic dietary changes. In order to test for dietary changes through growth, stable carbon and oxygen isotope (δ13C, δ18O) analysis was performed on tooth carbonate from small (<4.5 mm crown height) and large (>9 mm crown height) D. antirrhopus specimens from two microsites from the Lower Cretaceous Cloverly (Montana) and Antlers (Oklahoma) formations. Teeth from goniopholidid crocodylians and Tenontosaurus tilletti from the Cloverly Formation were also tested for comparison. The results show that the Cloverly goniopholidids, like their modern counterparts, went through a distinct transition in diet as they grew. The smallest teeth were the relatively most enriched in 13C (mean = −9.32‰; n = 5), the medium-sized teeth were the most-depleted in 13C (mean = −10.56‰; n = 5), and the largest teeth were intermediate (mean = −10.12‰; n = 6). These factors are characteristic of the dietary shifts seen in modern asocial reptiles. D. antirrhopus showed this same pattern in tooth samples collected from both rock units, with small teeth being the more enriched in 13C (mean = −8.99‰; n = 10) and the large teeth being more depleted in 13C (mean =

−10.38‰; n = 10). These differences suggest that juvenile and adult D. antirrhopus from both formations likely consumed different prey. Hypothetical food sources, such as T. tilletti, are close to the 13C isotopic signal of adult D. antirrhopus, consistent with the hypothesized trophic relationship (predator-prey) between these two species. Juvenile D. antirrhopus had a diet more enriched in 13C, likely composed of smaller-bodied, but trophically-higher species. Taken together, these data add to the growing evidence that D. antirrhopus was not a complex social hunter by modern mammalian standards.

French, K.L., Birdwell, J.E., Lewan, M.D., 2020. Trends in thermal maturity indicators for the organic sulfur-rich Eagle Ford Shale. Marine and Petroleum Geology 118, 104459.


Thermal maturity is critical to evaluate petroleum systems and to interpret biomarker results for paleoenvironmental and geobiology studies. Many thermal maturity indices were developed for marine source rocks containing type II kerogen, but their behavior in organic sulfur-rich source rocks requires more investigation. Here, we present geochemical analyses of whole and extracted rock, isolated kerogen, and extractable organic matter across a natural thermal maturity sequence of the Upper Cretaceous Eagle Ford Shale to evaluate the behavior of maturity parameters in organic sulfur-rich source rocks. The samples have similar mineralogy and trace element composition, minimizing potential facies effects on thermal maturity parameters. Atomic H/C ratios of isolated kerogen, extractable organic matter yield, and programmed pyrolysis results show that the samples range from the pre-oil through dry gas generation windows. Programmed pyrolysis data and kerogen elemental ratios show that the immature samples host both type IIS (atomic Sorg/C > 0.04) and sulfur-rich type II kerogen (kerogen Sorg/C: 0.03–0.04) while samples with lower kerogen Sorg/C ratios (kerogen Sorg/C < 0.02) are more mature. The vitrinite reflectance values corresponding to the onset of oil generation in the Eagle Ford are comparable to other type II petroleum systems. Likewise, the organic sulfur-rich Eagle Ford follows a similar hydrogen index (HI) and kerogen H/C trend as other marine type II source rocks. Hopane and sterane stereoisomer maturity ratios are anomalously elevated at low thermal maturities, so they should not be applied in organic sulfur-rich petroleum systems to infer thermal maturity. However, some biomarker ratios, including those that are more commonly used as source parameters, strongly track thermal maturity in this case study with limited facies variability.


https://doi.org/10.1002/gj.3596

We conducted a study in the Wulan Hua Sag, a Mesozoic relic sag in the Erlian Basin to analyse and ‐determine the period of its hydrocarbon accumulation. Estimation of erosional thickness is carried out from sonic well logs and seismic velocity data, followed by defining burial history of the Wulan‐Hua Sag together with thermal history through basin modelling. Fluid inclusions and pore fluid microthermometric data of 37 samples from clastic reservoir in the Wulan Hua Sag are available for ‐detailed correlation and analysis. The reconstructed erosion thickness indicates that first of all, differential uplift that is characterized by seesaw uplift erosion initiated at the north sub sag. ‐ ‐

Secondly, largest erosion degree appears in Tumu'er and Saiwusu tectonic belts. Thirdly, the thickness of sedimentary rocks removed by erosion in the south sub sag progressively increases ‐from its subsiding centre outwardly. Burial history of the Wulan Hua Sag belongs to type of late‐ ‐period intensive uplift erosion. Two types of fluid inclusion are recognized in the Wulan Hua Sag ‐ ‐indicating two hydrocarbon accumulation periods for reservoirs in LK1bt1 (lower interval in first member of Tengge'er Formation), which is middle depositing period of K1bt1 (first member of Tengge'er Formation) to early depositing period of K1bt2 (second member of Tengge'er Formation) and early K1bt2 to middle K1bs (Saihantala Formation) depositing period, respectively. Reservoir in the K1ba and upper interval of K1bt1 appears to have experienced one hydrocarbon accumulation period, which is early K1bt1 to early K1bt2 depositing period. And reservoir in the UK1bt1 (upper interval in first member of Tengge'er Formation) also has one hydrocarbon accumulation period, which is late K1bt2 depositing period to the Late Cretaceous (K2). Hydrocarbon accumulation model of the Wulan Hua Sag consists of two oil reservoir types including “upward charging” and “self‐ ‐ ‐ ‐sourced.” Reservoir in lower interval of K1bt1 and reservoir in the upper interval of K1bt1 are considered to have more hydrocarbon exploration potential.

Fu, X., Liao, Y., Glein, C.R., Jamison, M., Hayes, K., Zaporski, J., Yang, Z., 2020. Direct synthesis of amides from amines and carboxylic acids under hydrothermal conditions. ACS Earth and Space Chemistry 4, 722-729.

https://doi.org/10.1021/acsearthspacechem.0c00009

Hydrothermal systems provide a unique habitat for the subsurface biosphere, and possibly, for the origin of life. Amides are fundamental to hydrothermal organic geochemistry and deep subsurface biology research, in large part because of their involvement in metabolism, such as in the forms of peptides and proteins, and also because of their participation in the deep nitrogen cycle and their potential role in the origin of life. Hydrothermal chemistry of amides is also of great interest to astrobiology research because it may reveal potential formation pathways of peptides and biomolecules in the space outside Earth. Here, we describe a nonmineral-catalyzed synthetic pathway for amide synthesis under hydrothermal conditions (250 °C and 40 bar, Psat). We find that a suite of amides (12 examples) are readily synthesized through a direct condensation between amines and carboxylic acids, with an amide yield of up to 90% over a timescale of hours. Time-series hydrothermal experiments were performed to obtain apparent rate constants for amide synthesis. The observed hydrothermal rate constants were significantly larger for certain amines (e.g., 0.2 h–1 for benzylamine) than for others (e.g., 0.05 h–1 for cyclohexylamine), which suggests a strong substitution effect on amide formation. An amine acylation mechanism is proposed, and also consistent with previous studies. Furthermore, amide formation is found to be strongly inhibited in high or low pH solutions (e.g., pH <2 or >12), which further supports that the condensation reaction should occur between the neutral amine and acid. Our finding of a feasible and selective hydrothermal pathway for amide bond formation may provide new insights into understanding peptides and biomolecule synthesis in relevant hydrothermal environments.

Fujisaki, W., Fukami, Y., Matsui, Y., Sato, T., Sawaki, Y., Suzuki, K., 2020. Redox conditions and nitrogen cycling during the Triassic-Jurassic transition: A new perspective from the mid-Panthalassa. Earth-Science Reviews 204, 103173.


We determined redox-sensitive element concentrations along with δ15NTN values from the Triassic-Jurassic shales interbedded within deep-sea cherts at the Katsuyama section, SW Japan, to clarify the redox and related nitrogen cycle conditions in mid-Panthalassa during the TJB biotic crisis, focusing particularly on the linkages with CAMP volcanism. Slight enrichments of Mn and Mo across the TJB suggest a vertically expanded mid-Panthalassic OMZ above a well-oxygenated deep ocean. Moreover, high-resolution δ15NTN records during the Triassic-Jurassic transition exhibit a negative nitrogen isotope excursion (NNIE) just above the TJB. Relative to the previously reported negative carbon isotope excursion (NCIE) across the TJB, the NNIE can be divided into two intervals: negative interval 1 (NI-1) during the NCIE and NI-2 after the NCIE. The NNIE can be explained as an interval of nitrate-rich conditions, reflecting an oxic Panthalassic Ocean during the Triassic-Jurassic transition. Our geochemical dataset provides new insights into environmental perturbations in mid-Panthalassia during the TJB biotic crisis: (1) a vertically expanded OMZ and decreased primary productivity owing to global warming caused by CAMP volcanism across the TJB resulted in an increased nitrate concentration during the NI-1, and (2) eutrophic, nitrate-rich conditions developed in mid-Panthalassa during the NI-2 due to the enhanced continental weathering and deep-water upwelling. Significantly, our results are the first to demonstrate that the OMZs were expanded not only in the shallow-marine regions, but also in pelagic sites across the TJB, suggesting that the globally expanded OMZs can be regarded as a crucial driver for the TJB biotic crisis.

Fulcher, K., Stacey, R., Spencer, N., 2020. Bitumen from the Dead Sea in Early Iron Age Nubia. Scientific Reports 10, 8309.

https://doi.org/10.1038/s41598-020-64209-8

Bitumen has been identified for the first time in Egyptian occupied Nubia, from within the town of Amara West, occupied from around 1300 to 1050 BC. The bitumen can be sourced to the Dead Sea using biomarkers, evidencing a trade in this material from the eastern Mediterranean to Nubia in the New Kingdom or its immediate aftermath. Two different end uses for bitumen were determined at the site. Ground bitumen was identified in several paint palettes, and in one case can be shown to have been mixed with plant gum, which indicates the use of bitumen as a ground pigment. Bitumen was also identified as a component of a friable black solid excavated from a tomb, and a black substance applied to the surface of a painted and plastered coffin fragment. Both contained plant resin, indicating that this substance was probably applied as a ritual funerary liquid, a practice identified from this time period in Egypt. The use of this ritual, at a far remove from the royal Egyptian burial sites at Thebes, indicates the importance of this ritual as a component of the funeral, and the value attributed to the material components of the black liquid.



In this study, we examined carbonyl functional groups in Canadian oil sand bitumen using Fourier transform infrared spectroscopy (FTIR). FTIR spectra of a bromoform solution of the bitumen fraction showed carbonyl absorption at 1702 cm–1, which shifted to 1718 cm–1 following the addition of 1,6-dicyanohexane (DCH) to the bromoform solution. Bromoform solution analyses of model aliphatic and aromatic carboxylic acids and ketones showed carbonyl absorption values of 1704–

1702 and 1691–1680 cm–1, respectively, for the aliphatic and aromatic compounds. When DCH was added to the bromoform solution, aliphatic and aromatic carboxylic acid carbonyl absorption shifted to higher wavenumbers, whereas no equivalent shift was observed in ketones. Therefore, we conclude that the bitumen fraction contained aliphatic carboxylic acids. The FTIR area ratio of carbonyl to C–H of bromoform, at 3020 cm–1 in the model carboxylic acids and ketones, increased in proportion to their mole ratios. The amount of carbonyl in the bitumen fraction was estimated at 0.026 mol/kg based on the relationship between the area ratio and mole ratio.

Furse, S., Fernandez-Twinn, D.S., Jenkins, B., Meek, C.L., Williams, H.E.L., Smith, G.C.S., Charnock-Jones, D.S., Ozanne, S.E., Koulman, A., 2020. A high-throughput platform for detailed lipidomic analysis of a range of mouse and human tissues. Analytical and Bioanalytical Chemistry 412, 2851-2862.

https://doi.org/10.1007/s00216-020-02511-0

Lipidomics is of increasing interest in studies of biological systems. However, high-throughput data collection and processing remains non-trivial, making assessment of phenotypes difficult. We describe a platform for surveying the lipid fraction for a range of tissues. These techniques are demonstrated on a set of seven different tissues (serum, brain, heart, kidney, adipose, liver, and vastus lateralis muscle) from post-weaning mouse dams that were either obese (> 12 g fat mass) or lean (<5 g fat mass). This showed that the lipid metabolism in some tissues is affected more by obesity than others. Analysis of human serum (healthy non-pregnant women and pregnant women at 28 weeks’ gestation) showed that the abundance of several phospholipids differed between groups. Human placenta from mothers with high and low BMI showed that lean placentae contain less polyunsaturated lipid. This platform offers a way to map lipid metabolism with immediate application in metabolic research and elsewhere.

Fyfe, L.-J.C., Schofield, N., Holford, S.P., Heafford, A., Raine, R., 2020. Geology and petroleum prospectivity of the Larne and Portpatrick basins, North Channel, offshore SW Scotland and Northern Ireland. Petroleum Geoscience 26, 272.


The Larne and Portpatrick basins, located in the North Channel between SW Scotland and Northern Ireland, have been the target of a small programme of petroleum exploration activities since 1971. A total of five hydrocarbon exploration wells have been drilled within the two basins, although as of yet no commercial discoveries have been made. The presence of hydrocarbon shows alongside the discovery of two good-quality reservoir–seal couplets within Triassic and underlying Permian strata has encouraged exploration within the region. The focus of this study is to evaluate the geology and hydrocarbon prospectivity of the Portpatrick Basin and the offshore section of the Larne Basin. This is achieved through the use of seismic reflection data, and gravity and aeromagnetic data, alongside sedimentological, petrophysical and additional available datasets from both onshore and offshore wells, boreholes and previously published studies. The primary reservoir interval, the Lower–Middle Triassic Sherwood Sandstone Group (c. 600–900 m gross thickness), is distributed across both basins and shows good to excellent porosity (10–25%) and permeability (10–1000 mD) within the Larne Basin. The Middle–Late Triassic Mercia Mudstone Group should provide an excellent top seal where present due to the presence of thick regionally extensive halite deposits, although differential erosion has removed this seal from the margins of the Larne and Portpatrick basins. The

Carboniferous, which has been postulated to contain organic-rich source-rock horizons, as inferred from their presence in adjacent basins, has not yet been penetrated within the depocentre of either basin. There is, therefore, some degree of uncertainty regarding the quality and distribution of a potential source rock. The interpretation of seismic reflection profiles presented here, alongside the occurrence of hydrocarbon shows, indicates the presence of organic-rich pre-Permian sedimentary rocks within both basins. 1D petroleum system modelling of the Larne-2 borehole shows that the timing of hydrocarbon generation and migration within the basins is a significant risk, with many traps post-dating the primary hydrocarbon charge. Well-failure analysis has revealed that trap breach associated with kilometre-scale uplift events, and the drilling of wells off-structure due to a lack of good-quality subsurface data, have contributed to the lack of discoveries. While the Larne and Portpatrick basins have many elements required for a working petroleum system, along with supporting hydrocarbon shows, the high risks coupled with the small scale of potential discoveries makes the Portpatrick Basin and offshore section of the Larne Basin poorly prospective for oil and gas discovery.Thematic collection: This article is part of the Under-explored plays and frontier basins of the UK continental shelf collection available at: http://www.lyellcollection.org/cc/under-explored-plays-and-frontier-basins-of-the-uk-continental-shelf

Gale, J., Wandel, A., Hill, H., 2020. Will recent advances in AI result in a paradigm shift in Astrobiology and SETI? International Journal of Astrobiology 19, 295-298.

https://doi.org/10.1017/S1473550419000260

The steady advances in computer performance and in programming raise the concern that the ability of computers would overtake that of the human brain, an occurrence termed ‘the Singularity’. While comparing the size of the human brain and the advance in computer capacity, the Singularity has been estimated to occur within a few decades although the capacity of conventional computers may reach its limits in the near future. However, in the last few years, there have been rapid advances in artificial intelligence. There are already programs that carry out pattern recognition and self-learning which, at least in limited fields such as chess and other games, are superior to the best human players. Furthermore, the quantum computing revolution, which is expected to vastly increase computer capacities, is already on our doorstep. It now seems inevitable that the Singularity will arrive within the foreseeable future. Biological life, on Earth and on extraterrestrial planets and their satellites, may continue as before, but humanity could be ‘replaced’ by computers. Older and more advanced intelligent life forms, possibly evolved elsewhere in the Universe, may have passed their Singularity a long time ago. Post Singularity life would probably be based not on biochemical reactions but on electronics. Their communication may use effects such as quantum entanglement and be undetectable to us. This may explain the Fermi paradox or at least the ‘Big Silence’ problem in SETI.

Ganeeva, Y.M., Barskaya, E.E., Yusupova, T.N., Okhotnikova, E.S., Sotnikov, O.S., Remeev, M.M., Khisamov, R.S., 2020. Comparative analysis of organic matter of reservoir rocks and Domanik deposits of the Bavly oil field. Petroleum Chemistry 60, 255-263.

https://doi.org/10.1134/S0965544120030068

Core material taken over a section of the Bavly multipay field of Tatarstan (Russia), and extracts from it have been studied by thermal analysis, IR and EPR spectroscopy, and gas-liquid

chromatography. The trends of changes in the amount and fractional and hydrocarbon-group compositions of residual oil and oil components irreversibly adsorbed on the rock depending on the age of deposition have been revealed. In rocks from the Trans-Volgian and Dankovian–Lebedyanian horizons attributed to domanik deposits, the organic matter content has been determined with an estimate of the proportion of bitumoid and kerogen in it, and the peculiarities of their fractional and hydrocarbon-group compositions have been revealed.

Gao, G., Cao, J., Luo, B., Xiao, D., Zhang, Y., Chen, C., 2020. Evidence of the Middle Permian marine mixed type source rocks in the northwestern Sichuan Basin and its contribution to large gas reservoirs in Shuangyushi area Acta Petrolei Sinica 41, 433-445.

http://www.syxb-cps.com.cn/EN/abstract/abstract5880.shtml

Gas exploration has made a major breakthrough in Permian Qixia Formation of the Shuangyushi structural belt in the northwest of Sichuan basin, revealing a new exploration field. However, the geochemical characteristics of gas are not in line with the typical characteristics of oil cracking gas from the Cambrian Qiongzhusi Formation as expected. To explain this contradiction, the paper conducts a study through the geological survey of field sections and analysis of downhole core samples in combination with the geological background. The research results show that the marine mixed marls in Middle Permian Qixia Formation and Maokou Formation may be regional effective source rocks. These two sets of source rocks are widely distributed in the northwestern Sichuan Basin, with thicknesses of 0-30 m and 30-150 m, respectively. The source rocks were formed in a marine reducing environment with low salinity. The organic carbon content is 0.86%-7.15%, and the type II organic matter type is dominant. At present, the thermal evolution is mainly in the over mature stage. The equivalent vitrinite reflectance of laser Raman spectroscopy is 1.94%-3.39%. Generally, they are medium-high quality source rocks with good hydrocarbon generation potential, and as the major source rocks, have made substantial contributions to the development of large gas reservoirs in Qixia Formation of the Shuangyushi structural belt. The connectivity between faults and underlying hydrocarbon sources is the key factor determining the differences between Cambrian and Permian hydrocarbon sources. The stable maintenance of traps and good preservation conditions of oil and gas are the key to natural gas accumulation on a large scale.

Gao, Y., Wen, Z., Xu, Y., Song, H., Li, W., Yu, Y., Ke, C., 2020. Geochemical characteristics of the Chang7 organic-rich fine-grained sedimentary rocks and its relationship with the tight oil in Longdong area, Northwest China. Journal of Petroleum Exploration and Production Technology 10, 1803-1816.

https://doi.org/10.1007/s13202-020-00891-8

In order to study the geochemical characteristics of fine-grained sedimentary rocks and clarify its relationship with the tight oil reservoir, the Chang7 Member of Triassic Yanchang Formation in Longdong area was taken as an example to be studied by rock pyrolysis, isotopic determination, maceral analysis, gas chromatography and gas chromatography–mass spectrometry. Lacustrine organic-rich fine-grained sedimentary rocks can be divided into organic-rich shale and organic-rich mudstone according to their lithology and texture. The results show that the organic-rich shale was deposited in a quiet and anoxic deep lacustrine environment, the organic matter was of high abundance and mainly sourced from plankton and benthic algae (type I–II1). Organic-rich mudstone mainly deposited in the semi-deep lacustrine environment, where the water was relatively shallow

and the salinity was low, the organic matter was of low abundance and came from the mixed source of plankton and terrestrial clastic (type II1–II2). The Chang7 tight oil is widely distributed in the turbidite sand bodies, and it was mainly sourced from the Chang7 organic-rich shale.



The lower Silurian Longmaxi Formation shale in the Sichuan Basin is one of the most promising shale gas plays in China. Pore structure has a significant impact on hydrocarbon migration within shales. This study conducts systematic experiments to analyze the pore structure, wettability, and methane adsorption capacity of the Longmaxi Formation shale samples from the southern Sichuan Basin. The pore-size distributions obtained from N2 adsorption, high-pressure mercury intrusion porosimetry, and statistical analysis of representative field emission–scanning electron microscopy photographs of organic matter (OM) are compared to evaluate the contribution of OM pores to total pore spaces. Shale wettability was determined by contact angle measurements and spontaneous imbibition experiments. The results reveal that these samples could be divided into three wettability categories: more water-wet samples Z1, more oil-wet samples Z4, and intermediate-wet samples Z2 and Z3. Although samples Z1 and Z4 have similar total organic carbon (TOC) contents, OM pores within sample Z4 have a larger average pore size and occupy a greater proportion of the total pore spaces compared with sample Z1, whereas inorganic pores contribute more to the total pore spaces of sample Z1. Sample Z4 has a larger methane adsorption capacity than sample Z1 with a higher Brunauer–Emmett–Teller (BET) surface area, which may be caused by the difference in their OM pore types. Samples Z2 and Z3 with less TOC content have lower porosities and BET surface areas as well as lower methane adsorption capacities. Consequently, the pore structure significantly affects the wettability and methane adsorption capacity of the Longmaxi shale.


https://doi.org/10.3390/microorganisms8050774

The genus Rhodococcus exhibits great potential for bioremediation applications due to its huge metabolic diversity, including biotransformation of aromatic and aliphatic compounds. Comparative genomic studies of this genus are limited to a small number of genomes, while the high number of sequenced strains to date could provide more information about the Rhodococcus diversity. Phylogenomic analysis of 327 Rhodococcus genomes and clustering of intergenomic distances identified 42 phylogenomic groups and 83 species-level clusters. Rarefaction models show that these numbers are likely to increase as new Rhodococcus strains are sequenced. The Rhodococcus genus possesses a small “hard” core genome consisting of 381 orthologous groups (OGs), while a “soft” core genome of 1253 OGs is reached with 99.16% of the genomes. Models of sequentially randomly added genomes show that a small number of genomes are enough to explain most of the shared diversity of the Rhodococcus strains, while the “open” pangenome and strain-specific genome evidence that the diversity of the genus will increase, as new genomes still add more OGs to the whole genomic set. Most rhodococci possess genes involved in the degradation of aliphatic

and aromatic compounds, while short-chain alkane degradation is restricted to a certain number of groups, among which a specific particulate methane monooxygenase (pMMO) is only found in Rhodococcus sp. WAY2. The analysis of Rieske 2Fe-2S dioxygenases among rhodococci genomes revealed that most of these enzymes remain uncharacterized.

Gáspár, A., Rieke, G.H., 2020. New HST data and modeling reveal a massive planetesimal collision around Fomalhaut. Proceedings of the National Academy of Sciences 117, 9712-9722.


Significance: Although originally thought to be a massive exoplanet, the faintness of Fomalhaut b in the infrared and its failure to perturb Fomalhaut’s debris ring indicate a low mass. We use all available data to reveal that it has faded in brightness and grown in extent, with motion consistent with an escaping orbit. This behavior confirms suggestions that the source is a dispersing cloud of dust, produced by a massive collision between two planetesimals. The visible signature appears to be very fine dust escaping under the influence of radiation pressure. Such events should be rare in quiescent planetary systems at the age of Fomalhaut, suggesting increased dynamical activity within the system possibly due to orbital migration of hypothetical planets.

Abstract: The apparent detection of an exoplanet orbiting Fomalhaut was announced in 2008. However, subsequent observations of Fomalhaut b raised questions about its status: Unlike other exoplanets, it is bright in the optical and nondetected in the infrared, and its orbit appears to cross the debris ring around the star without the expected gravitational perturbations. We revisit previously published data and analyze additional Hubble Space Telescope (HST) data, finding that the source is likely on a radial trajectory and has faded and become extended. Dynamical and collisional modeling of a recently produced dust cloud yields results consistent with the observations. Fomalhaut b appears to be a directly imaged catastrophic collision between two large planetesimals in an extrasolar planetary system. Similar events should be very rare in quiescent planetary systems of the age of Fomalhaut, suggesting that we are possibly witnessing the effects of gravitational stirring due to the orbital evolution of hypothetical planet(s) around the star.

Gibbons, A., 2020. Oldest Homo sapiens bones found in Europe. Science 368, 697.

http://science.sciencemag.org/content/368/6492/697.abstract

During a warm spell about 47,000 years ago, a small band of people took shelter in a cave on the northern slope of the Balkan Mountains in what is now Bulgaria. There, they butchered bison, wild horses, and cave bears, leaving the cave floor littered with bones and a wealth of artifacts—ivory beads, pendants made with cave bear teeth, and stone blades stained with red ochre.

This region had long been home to Neanderthals, who left stone tools in the same cave more than 50,000 years ago. But these cave dwellers were new to Europe, as an international team reports in Nature this week. Researchers re-excavated the cave and used a cutting-edge toolkit of their own to identify a molar and a handful of bone fragments as belonging to Homo sapiens, our own species. Precise new dates show these cave dwellers lived as early as 47,000 years ago, which makes them the earliest known members of our species in Europe.

The last Neanderthals didn't vanish from Western Europe until about 40,000 years ago, so the two kinds of humans must have overlapped on the continent for at least 5000 years; previous DNA studies have shown that they mated. The new work is reigniting a long-standing debate about how Neanderthals and moderns may have influenced each other's cultures, because it links moderns to a package of artifacts that resemble those made later by Neanderthals. “It's a wonderful example of pulling all these lines of evidence together to make a solid argument that H. sapiens were the authors” of some of those artifacts, says paleoanthropologist Katerina Harvati of the University of Tübingen.

Bones of early H. sapiens in Europe are scarce, so researchers try to identify them from tools and artifacts thought to be unique to modern humans. Those include sophisticated artifacts known as the Aurignacian, including bladelets, carved figurines, and musical instruments dating from 43,000 to 33,000 years ago. The reign of the Neanderthals, from about 400,000 to 40,000 years ago, is marked by less refined Mousterian tools. But researchers have puzzled over who crafted “transitional” artifacts—a grab bag of bone tools, beads, and jewelry immediately preceding the Aurignacian. One of these toolkits, called the Initial Upper Paleolithic (IUP), shows up in the Middle East about 47,000 years ago and later appears across Eurasia.

Partial fossils found with artifacts at one site in the United Kingdom and one in Italy suggested H. sapiens made some transitional assemblages, but questions persist about those dates at those sites. The Bulgarian cave, called Bacho Kiro, yielded human fossils in the 1970s, but those were lost.

Paleoanthropologist Jean-Jacques Hublin and colleagues at the Max Planck Institute for Evolutionary Anthropology joined forces with Bulgarian researchers to re-excavate Bacho Kiro in 2015. They uncovered thousands of bones, stone and bone tools, beads and pendants, and a human molar.

The shape of the molar marked it as a member of H. sapiens, but many of the bones were too fragmentary to tell whether they were animal or human. So, the Max Planck team scrutinized proteins in the bone. They extracted collagen from 1271 fragments and applied a new method called ZooMs to analyze them. Four fragments from the older layers were human. Researchers then extracted DNA from these bones and the tooth and found that the mitochondrial sequences—the most abundant DNA in many fossils—were those of H. sapiens. The team is now analyzing the fossils' nuclear DNA.

Meanwhile, Max Planck radiocarbon dating specialist Helen Fewlass and her colleagues directly dated collagen from 95 bones. They report in Nature Ecology & Evolution that the human bones and artifacts date from 43,650 to 45,820 years ago. The ages of animal bones modified by people suggest they were in the cave “probably beginning from 46,940” years ago, Fewlass says. At about this time, the climate of Europe had begun to warm, which may have enticed H. sapiens with IUP toolkits to venture north from the Middle East, into the Balkans and beyond, Hublin says. (The DNA of these early arrivals shows, however, that they left no descendants in Europe today.)

Hublin notes that pendants made from the teeth of cave bears at Bacho Kiro are similar to pendants thought to be the handiwork of later Neanderthals and crafted about 42,000 to 44,000 years ago—the so-called Châtelperronian industry, first found at the Grotte du Renne site in France. He argues that this supports his long-held contention that Neanderthals picked up this type of pendant from moderns.

Others say that extrapolation goes too far. “Transitional” technologies such as the IUP are so diverse and widespread that it's not clear that only one kind of human invented them, says archaeologist Nick Conard, also at the University of Tübingen. And archaeologist Francesco d'Errico of the University of Bordeaux, who has long debated Hublin over Neanderthals' abilities, points to earlier notched bone scrapers and beadlike objects as evidence that Neanderthals could create sophisticated art and technology well before they met modern humans.

Debate is sure to continue, but archaeologists welcome the “very significant” dates at Bacho Kiro, says Tom Higham, a radiocarbon specialist at the University of Oxford. “For the first time, we're able to pin the IUP as being made by anatomically modern humans in Europe.”



Despite iron and trace element proxies informing much of our insight into Earth’s oxygenation history, the processes that controlled their accumulation and distribution in ancient sedimentary environments are not fully understood. Furthermore, deciphering between primary, depositional signals and oxidative weathering alteration poses a substantial challenge to reconstructing Earth’s redox history using its sedimentary record. Here, we present a multi-proxy geochemical investigation of three transgressive shale intervals from the ca. 811 Ma Reefal assemblage (upper Fifteenmile Group) in Yukon, Canada to help resolve these issues. Systematic stratigraphic trends from low to high FeHR/FeT and FeT/Al compositions across shale intervals represent shoaling of a discrete redoxcline that separated oxygenated surface waters from anoxic, ferruginous deep waters during marine transgression. In some cases, these trends are followed by a symmetric fall, which represents a full “transgressive-regressive cycle” of the redoxcline. The high proportion of glauconite to total illite indicate short-term oscillating redox conditions as the redoxcline migrated across the sediment-water interface during relative sea-level rise. These conditions invigorated dissimilatory iron reduction (DIR) within anoxic sediment pore waters, which released Fe(II) into the overlying water column where it was oxidized to iron oxy(hydr)oxide and shuttled downslope. High rates of DIR within sediment replete with highly reactive iron oxy(hydr)oxide and organic matter removed isotopically light, bio-available iron, rendering the residual sediment depleted in FeT/Al relative to the detrital baseline and enriched in 56Fe. The low iron content of the detrital flux to the basin (Fe/Al ∼ 0.3) rendered the sediment susceptible to changes in its bulk δ56Fe composition by modification of its authigenic components alone and enabled fractionation from DIR to drive bulk-rock δ56Fe values up to 0.8‰. Anomalously high concentrations of redox-sensitive elements in three samples (up to 5792 ppm Cr, 586 ppm Mn, 726 ppm Mo, and 3509 ppm Ni) and their relative distribution patterns show similarities to co-enrichment due to particulate shuttling within a weakly restricted basin. However, SEM-EDS element maps and large-area BSE image mosaics show the remains of framboidal pyrite “ghosts” with secondary enrichment of redox-sensitive elements. Thus, these geochemical trends in redox-sensitive trace metals most likely reflect mobilization and re-accumulation following pyrite dissolution during outcrop weathering. The low primary pyrite content and local transformation of pyrite iron to iron oxy(hdr)oxide suggest that δ56Fe and FeHR/FeT data were unaltered despite indications of pyrite weathering. Ultimately, this dataset elucidates key aspects of sedimentary redox cycling directly preceding evolutionary milestones and a major

perturbation to the global carbon cycle and also provides a template for evaluating the effects of outcrop weathering on commonly used sedimentary redox proxies.

Gilboa, T., Garden, P.M., Cohen, L., 2020. Single-molecule analysis of nucleic acid biomarkers – A review. Analytica Chimica Acta 1115, 61-85.


Nucleic acids are important biomarkers for disease detection, monitoring, and treatment. Advances in technologies for nucleic acid analysis have enabled discovery and clinical implementation of nucleic acid biomarkers. However, challenges remain with technologies for nucleic acid analysis, thereby limiting the use of nucleic acid biomarkers in certain contexts. Here, we review single-molecule technologies for nucleic acid analysis that can be used to overcome these challenges. We first discuss the various types of nucleic acid biomarkers important for clinical applications and conventional technologies for nucleic acid analysis. We then discuss technologies for single-molecule in vitro and in situ analysis of nucleic acid biomarkers. Finally, we discuss other ultra-sensitive techniques for nucleic acid biomarker detection.

Gilchrist, R.M., Hall, R.A., Bacon, J.C., Rees, J.M., Graham, J.A., 2020. Increased dispersion of oil from a deep water seabed release by energetic mesoscale eddies. Marine Pollution Bulletin 156, 111258.


Hydrodynamics play a critical role in determining the trajectory of an oil spill. Currents, stratification and mesoscale processes all contribute to how a spill behaves. Using an industry-leading oil spill model, we compare forecasts of oil dispersion when forced with two different hydrodynamic models of the North-West European Shelf (7 km and 1.5 km horizontal resolution). This demonstrates how the trajectory of a deep water (>1000 m) release in the central Faroe-Shetland Channel is influenced by explicitly resolving mesoscale processes. The finer resolution hydrodynamic model dramatically enhances the horizontal dispersion of oil and transports pollutant further afield. This is a consequence of higher mesoscale variability. Stratification influences the depth of subsurface plume trapping and subsequently the far-field transport of oil. These results demonstrate that the choice of hydrodynamic model resolution is crucial when designing particle tracking or tracer release experiments.

Giongo, A., Haag, T., Medina-Silva, R., Heemann, R., Pereira, L.M., Zamberlan, P.M., Valdez, F.P., Oliveira, R.R., Eizirik, E., Viana, A.R., Ketzer, J.M.M., 2020. Distinct deep subsurface microbial communities in two sandstone units separated by a mudstone layer. Geosciences Journal 24, 267-274.

https://doi.org/10.1007/s12303-019-0028-5

Deep subsurface microbial communities are more abundant in coarse-grained sedimentary rocks such as sandstones than in fine-grained mudstones. The low porosity and low permeability of mudstones are believed to restrict microbial life. Then, it is expected that distinct, isolated microbial communities may form in sandstones separated by mudstones. In this context, the connectivity between microbial communities in different sandstone units can be investigated to infer evolutionary patterns of diversification in space-time, which may potentially contribute with

relevant data for analyses of hydraulic connectivity and stratigraphic correlation. In this work, we used high throughput DNA sequencing of a ribosomal 16S gene fragment to characterize the prokaryotic communities found in Permian sandstone samples of the same core that are separated by one mudstone interval, in the Charqueadas coal field, Parana Basin (Southern Brazil). Our samples were collected at ∼300 m deep, in porous sandstones separated by a thick mudstone package. Differences in the bacterial community structure between samples were observed for the classified OTUs, from phylum to genus. Molecular biology might be further applied as a possible tool to help to understand the spatial and temporal distribution of depositional facies, and the efficiency of low permeability rocks to compartmentalize reservoirs. Ongoing studies aim to extend the present investigation into further analyses regarding lateral changes in microbial communities present in the same sandstone units.

Gladysheva, O., 2020. The Tunguska event. Icarus 348, 113837.


The question about the nature of the object called the Tunguska meteorite, which exploded over the Siberian taiga on June 30, 1908, is the cornerstone in understanding the process of interaction of cosmic bodies with the Earth's atmosphere. If we consider it to have been an asteroid, then we have to assume that an object with a mass >108 kg can completely evaporate in the atmosphere. If this object was a comet, then the rule obtained from experiments is valid: an asteroid with a mass >104–105 kg is crushed by the atmosphere and its fragments fall to the ground. The calculations indicate that a comet with an initial mass of 8·109 kg can reach an altitude of 10 km above the Earth's surface and explode with an energy release of 10 megatons of TNT. Remains of the Tunguska body fragments were found on the ground.

Glenne, E., Samuelsson, J., Leek, H., Forssén, P., Klarqvist, M., Fornstedt, T., 2020. Systematic investigations of peak distortions due to additives in supercritical fluid chromatography. Journal of Chromatography A 1621, 461048.


The impact of eluent components added to improve separation performance in supercritical fluid chromatography was systematically, and fundamentally, investigated. The model system comprised basic pharmaceuticals as solutes and eluents containing an amine (i.e., triethylamine, diethylamine, or isopropylamine) as additive with MeOH as the co-solvent. First, an analytical-scale study was performed, systematically investigating the impact of the additives/co-solvent on solute peak shapes and retentions, using a design of experiments approach; here, the total additive concentration in the eluent ranged between 0.021 and 0.105 % (v/v) and the MeOH fraction in the eluent between 16 and 26 % (v/v). The co-solvent fraction was found to be the most efficient tool for adjusting retentions, whereas the additive fraction was the prime tool for improving column efficiency and peak analytical performance. Next, the impacts of the amine additives on the shapes of the so-called overloaded solute elution profiles were investigated. Two principal types of preparative peak deformations appeared and were investigated in depth, analyzed using computer simulation with mechanistic modeling. The first type of deformation was due to the solute eluting too close to the additive perturbation peak, resulting in severe peak deformation caused by co-elution. The second type of deformation was also due to additive–solute interactions, but here the amine additives

acted as kosmotropic agents, promoting the multilayer adsorption to the stationary phase of solutes with bulkier aryl groups.

Globus, N., Blandford, R.D., 2020. The chiral puzzle of life. The Astrophysical Journal 895, L11.

http://dx.doi.org/10.3847/2041-8213/ab8dc6

Biological molecules chose one of two structurally chiral systems which are related by reflection in a mirror. It is proposed that this choice was made, causally, by cosmic rays, which are known to play a major role in mutagenesis. It is shown that magnetically polarized cosmic rays that dominate at ground level today can impose a small, but persistent, chiral bias in the rate at which they induce structural changes in simple, chiral monomers that are the building blocks of biopolymers. A much larger effect should be present with helical biopolymers, in particular, those that may have been the progenitors of ribonucleic acid and deoxyribonucleic acid. It is shown that the interaction can be both electrostatic, just involving the molecular electric field, and electromagnetic, also involving a magnetic field. It is argued that this bias can lead to the emergence of a single, chiral life form over an evolutionary timescale. If this mechanism dominates, then the handedness of living systems should be universal. Experiments are proposed to assess the efficacy of this process.



The impact of nanoplastics (NP) using model polystyrene nanoparticles amine functionalized (PS–NH2) has been investigated on pigment and lipid compositions of the marine diatom Chaetoceros neogracile, at two growth phases using a low (0.05 μg mL−1) and a high (5 μg mL−1) concentrations for 96 h. Results evidenced an impact on pigment composition associated to the light-harvesting function and photoprotection mainly at exponential phase. NP also impacted lipid composition of diatoms with a re-adjustment of lipid classes and fatty acids noteworthy. Main changes upon NP exposure were observed in galactolipids and triacylglycerol’s at both growth phases affecting the thylakoids membrane structure and cellular energy reserve of diatoms. Particularly, exponential cultures exposed to high NP concentration showed an impairment of long chain fatty acids synthesis. Changes in pigment and lipid content of diatom’ cells revealed that algae physiology is determinant in the way cells adjust their thylakoid membrane composition to cope with NP contamination stress. Compositions of reserve and membrane lipids are proposed as sensitive markers to assess the impact of NP exposure, including at potential predicted environmental doses, on marine organisms.

Gordadze, G.N., Giruts, M.V., Poshibaeva, A.R., Alferova, A.A., Yusupova, A.A., 2020. Change in maturity of coals of the same genotype occurring at different depths, as determined by saturated hydrocarbon biomarkers. Petroleum Chemistry 60, 264-269.

https://doi.org/10.1134/S096554412003007X

Saturated hydrocarbon biomarkers have been determined in chloroform extracts of coals occurring at different depths (190, 205, and 322 m) of the Vinogradovskii open-pit mine (Belovo, Kuzbass), using gas–liquid chromatography and gas chromatography–mass spectrometry. The relative distribution of hydrocarbon (HC) biomarkers—n-alkanes, isoprenanes, steranes, and terpanes—shows that the coals are genetically uniform. In terms of hydrocarbon composition, they are weakly mature, although they relate to long-flame D-type coals by the degree of metamorphism. With an increase in the coal occurrence depth, the HC biomarker ratios that reflect the degree of maturity of organic matter slightly increase. As coal occurrence depth increases, the carbon preference index of n-alkanes decreases, the maturity coefficients K1mat and K2mat by C29 steranes and the dia/reg ratios of C27 steranes increase; the terpane Ts/Tm ratio and S/R epimer ratio of C31 and C32 homohopanes increase, and the moretane/hopane ratio decrease.

Goss, M., Li, Z., McLachlan, M.S., 2020. A simple field-based biodegradation test shows pH to be an inadequately controlled parameter in laboratory biodegradation testing. Environmental Science: Processes & Impacts 22, 1006-1013.

https://doi.org/10.1039/C9EM00491B

Abstract: Biodegradation tests are essential for characterizing the behavior of organic micropollutants in the environment, but they are carried out almost exclusively in the laboratory. Test parameters such as temperature and test chemical concentration are often applied in ways that affect observed biodegradation, and laboratory testing requires sophisticated temperature-controlled facilities. We developed a field-based test based on OECD 309 which minimizes the need for laboratory resources such as temperature-controlled facilities by using bottles incubated in the natural water body. The test also utilized contaminant residues present in unspiked natural water to increase the relevance of the results to the local system. A test in a local river and a matching lab-based test were conducted in parallel. We quantified 26 of 40 targeted micropollutants and observed dissipation for 13. Significant differences in half-life (up to a factor of 3.5) between lab and field bottles were observed for 7 compounds, with 6 of 7 degrading more slowly in field bottles. For 4 of these, dissipation was positively correlated to the neutral fraction of the chemical. Differences in the neutral fraction arose due to a higher pH in the lab bottles induced by outgassing of CO2 from the oversaturated river water. We conclude that pH is an important parameter to control in biodegradation testing and that field-based tests may be more environmentally relevant.

Environmental significance statement: Organic micropollutants such as pharmaceuticals are widely released into the environment via wastewater treatment plants. Standard laboratory tests estimate biodegradation rates for these contaminants but biodegradation is rarely measured in the field. This manuscript compares a standard laboratory test with a novel field-based method, which attempts to measure biodegradation rates more directly relevant to a local environment. We observed that rising sample pH under typical laboratory conditions, due to outgassing of CO2 from oversaturated river water, was correlated with faster biodegradation of some compounds than was observed under constant pH in field incubations. This suggests standard laboratory tests may improperly estimate micropollutant half-lives in the environment when pH is not appropriately considered.

Goto, K.T., Sekine, Y., Shimoda, G., Hein, J.R., Aoki, S., Ishikawa, A., Suzuki, K., Gordon, G.W., Anbar, A.D., 2020. A framework for understanding Mo isotope records of Archean and Paleoproterozoic Fe- and

Mn-rich sedimentary rocks: Insights from modern marine hydrothermal Fe-Mn oxides. Geochimica et Cosmochimica Acta 280, 221-236.


Molybdenum isotopic compositions (δ98/95Mo) of Archean and Paleoproterozoic Fe- and Mn-rich sedimentary rocks have been used to investigate local accumulations of O2 in an O2-lean ocean. Previous studies interpret that these δ98/95Mo values would be a representation of the global minimum for δ98/95Mo of contemporaneous seawater and would, therefore, link to global paleoredox conditions. Here, we present new δ98/95Mo data on modern marine hydrothermal Fe-Mn oxides, for a wide range of Fe/Mn ratios, from five hydrothermal systems. Samples composed mainly of Fe oxides (Fe/Mn > 10) show positive values (δ98/95Mo ∼ +0.7‰), whereas those containing substantial amounts of Mn oxides (Fe/Mn < 10−1) generally exhibit negative values (δ98/95Mo ∼ −0.8 ‰). These δ98/95Mo values are consistent with isotopic fractionations due to the adsorption of seawater Mo onto Fe and Mn oxides, respectively. The aforementioned positive and negative values are connected by a positive correlation between δ98/95Mo values and the Fe/Mn ratios of samples with Fe/Mn ∼ 10−1–101. The positive correlation can be explained by the mixing of δ98/95Mo in Fe and Mn oxides. Based on these data, we propose that the measured δ98/95Mo trends for the modern hydrothermal Fe-Mn oxides can be reproduced using a simple mass-balance calculation with both modern seawater δ98/95Mo and Mo isotopic fractionations due to the adsorption of Mo onto Fe and Mn oxides. By applying this mass-balance calculation to published Fe/Mn and δ98/95Mo data on ancient Fe- and Mn-rich sedimentary rocks, we estimate Archean and Paleoproterozoic seawater δ98/95Mo and their deviations (Δ98/95Mo) from modern seawater δ98/95Mo. The long-term evolution of seawater δ98/95Mo inferred as a result suggests extensive deposition of Fe and Mn oxides at ∼2.3–2.2 Ga and an expansion of euxinic conditions at ∼1.9 Ga, which are broadly consistent with the proposed redox evolution of the ocean–atmosphere system during the Archean and Paleoproterozoic.

Gray, A., Krolikowski, M., Fretwell, P., Convey, P., Peck, L.S., Mendelova, M., Smith, A.G., Davey, M.P., 2020. Remote sensing reveals Antarctic green snow algae as important terrestrial carbon sink. Nature Communications 11, 2527.

https://doi.org/10.1038/s41467-020-16018-w

We present the first estimate of green snow algae community biomass and distribution along the Antarctic Peninsula. Sentinel 2 imagery supported by two field campaigns revealed 1679 snow algae blooms, seasonally covering 1.95 × 106 m2 and equating to 1.3 × 103 tonnes total dry biomass. Ecosystem range is limited to areas with average positive summer temperatures, and distribution strongly influenced by marine nutrient inputs, with 60% of blooms less than 5 km from a penguin colony. A warming Antarctica may lose a majority of the 62% of blooms occupying small, low-lying islands with no high ground for range expansion. However, bloom area and elevation were observed to increase at lower latitudes, suggesting that parallel expansion of bloom area on larger landmasses, close to bird or seal colonies, is likely. This increase is predicted to outweigh biomass lost from small islands, resulting in a net increase in snow algae extent and biomass as the Peninsula warms.


https://doi.org/10.1111/1462-2920.14956

In cold marine environments, the obligate hydrocarbon degrading psychrophile ‐ Oleispira antarctica RB 8, which utilizes aliphatic alkanes almost exclusively as substrates, dominates microbial ‐communities following oil spills. In this study, LC–MS/MS shotgun proteomics was used to identify changes in the proteome induced during growth on n alkanes and in cold temperatures. ‐Specifically, proteins with significantly higher relative abundance during growth on tetradecane (n ‐C14) at 16°C and 4°C have been quantified. During growth on n C‐ 14, O . antarctica expressed a complete pathway for the terminal oxidation of n alkanes including two alkane monooxygenases, ‐two alcohol dehydrogenases, two aldehyde dehydrogenases, a fatty acid CoA ligase, a fatty acid ‐ ‐desaturase and associated oxidoreductases. Increased biosynthesis of these proteins ranged from 3‐ to 21 fold compared with growth on a non hydrocarbon control. This study also highlights ‐ ‐mechanisms O . antarctica may utilize to provide it with ecological competitiveness at low temperatures. This was evidenced by an increase in spectral counts for proteins involved in flagella structure/output to overcome higher viscosity, flagella rotation to accumulate cells and proline metabolism to counteract oxidative stress, during growth at 4°C compared with 16°C. Such species‐specific understanding of the physiology during hydrocarbon degradation can be important for parameterizing models that predict the fate of marine oil spills.

Grewal, D.S., Dasgupta, R., Farnell, A., 2020. The speciation of carbon, nitrogen, and water in magma oceans and its effect on volatile partitioning between major reservoirs of the Solar System rocky bodies. Geochimica et Cosmochimica Acta 280, 281-301.


The composition of atmospheres and the resulting potential for planetary habitability in the rocky bodies of our Solar System and beyond is strongly controlled by the volatile exchange between their silicate reservoirs and exospheres. The initial budget and speciation of major volatiles, like carbon (C), nitrogen (N) and water (H2O), in the silicate reservoirs and atmospheres was set during the formation stages of rocky bodies. However, the speciation of these major volatiles in reduced silicate melts prevalent during the differentiation stages of rocky bodies and its effect on the partitioning of volatiles between major rocky body reservoirs is poorly known. Here we present SIMS and vibrational spectroscopy (FTIR and Raman) data, determining C solubility, H content, and speciation of mixed C-O-N-H volatiles in graphite saturated silicate glasses from high P (1–7 GPa)-T (1500–2200 °C) experiments reported in Grewal et al., 2019a, Grewal et al., 2019b. The experiments recorded oxygen fugacity (log fO2) between IW–4.3 and IW–0.8. C-O-N-H speciation varied systematically as function of fO2 at any given P-T. We find out that C-N−, CO32-, N2, and OH− are the dominant species in the oxidized range (>IW–1.5), along with some contributions from C-H, N-H, and C-O bearing species. Between IW–3.0 and IW–1.5, C is bonded as C-O either in the form of isolated C-O molecules or Fe-carbonyl complexes, or as C-H in hydrocarbons, or as combination of both in esters, while almost all of the H is bonded with the dominant N species, i.e., NH2− or NH2-. At the most reduced conditions (<IW–3.0), C is present mostly in the form of C-H bearing species, while anhydrous N3− followed by N-H bearing molecules are the dominant N bearing species. Magma oceans (MOs) in highly reduced bodies like Mercury would contain most of their C as graphite if MO

is carbon saturated and the dissolved C and N would be chemically bonded with the silicate network either in the form of anhydrous C4− and N3−, or hydrogenated C-H and N-H bearing species depending on H content of the silicate melts. MOs relevant for Mars, the Moon, Vesta, and angrite parent body would contain C and N mostly in the form of C-O and N-H bearing species, respectively. If the composition of Earth’s accreting material evolved from reduced to oxidized, then initially a significant amount of the C and N budget would be locked in the silicate reservoirs, which would subsequently be released to the proto-atmosphere(s) at later stages. The retention of proto-atmosphere(s) formed by MO degassing on Earth could have provided important precursors for prebiotic chemistry which possibly led to the eventual habitability of our planet. Additionally, based on the dominant speciation of N versus C in silicate melt as a function of fO2, we also predict that DNalloy/silicate is unaffected by fH2 under highly reduced conditions (<IW–3), while DCalloy/silicate is affected. Therefore, caution must be taken during the application of experimentally determined DNalloy/silicate and DCalloy/silicate to nominally anhydrous MOs.

Grillo, K.M., Dunne, J., Marshall, F., Prendergast, M.E., Casanova, E., Gidna, A.O., Janzen, A., Karega, M., Keute, J., Mabulla, A.Z.P., Robertshaw, P., Gillard, T., Walton-Doyle, C., Whelton, H.L., Ryan, K., Evershed, R.P., 2020. Molecular and isotopic evidence for milk, meat, and plants in prehistoric eastern African herder food systems. Proceedings of the National Academy of Sciences 117, 9793-9799.


Significance: Lipid residue analysis of archaeological ceramics provides the earliest direct chemical evidence for milk, meat, and plant consumption by pastoralist societies in eastern Africa. Data for milk in specialized pastoral systems (c. 5000 to 1200 BP) reveal changing selective pressures for lactase persistence and provide support for models of gene–culture coevolution among pastoral populations.

Abstract: The development of pastoralism transformed human diets and societies in grasslands worldwide. The long-term success of cattle herding in Africa has been sustained by dynamic food systems, consumption of a broad range of primary and secondary livestock products, and the evolution of lactase persistence (LP), which allows digestion of lactose into adulthood and enables the milk-based, high-protein, low-calorie diets characteristic of contemporary pastoralists. Despite the presence of multiple alleles associated with LP in ancient and present-day eastern African populations, the contexts for selection for LP and the long-term development of pastoralist foodways in this region remain unclear. Pastoral Neolithic (c. 5000 to 1200 BP) faunas indicate that herders relied on cattle, sheep, and goats and some hunting, but direct information on milk consumption, plant use, and broader culinary patterns is rare. Combined chemical and isotopic analysis of ceramic sherds (n = 125) from Pastoral Neolithic archaeological contexts in Kenya and Tanzania, using compound-specific δ13C and Δ13C values of the major fatty acids, provides chemical evidence for milk, meat, and plant processing by ancient herding societies in eastern Africa. These data provide the earliest direct evidence for milk product consumption and reveal a history of reliance on animal products and other nutrients, likely extracted through soups or stews, and plant foods. They document a 5,000-y temporal framework for eastern Africa pastoralist cuisines and cultural contexts for selection for alleles distinctive of LP in eastern Africa.

Grin’ko, A.A., Goncharov, I.V., Shakhova, N.E., Gustafsson, Ö., Oblasov, N.V., Romankevich, E.A., Zarubin, A.G., Kashapov, R.S., Gershelis, E.V., Dudarev, O.V., Mazurov, A.K., Semiletov, I.P., Chernykh, D.V., 2020. Organic matter of sediments in areas of intense methane release in the Laptev Sea: Molecular-composition specifics. Russian Geology and Geophysics 61, DOI: 10.15372/RGG2019150.

http://dx.doi.org/10.15372/RGG2019150

We present results of study of the molecular composition of organic matter (OM) in the bottom sediments of the Laptev Sea by gas chromatography-mass spectrometry, isotope gas chromatography-mass spectrometry, and Rock-Eval pyrolytic analysis. The OM of all collected sediment samples shows a significant terrigenous contribution. Compounds that are biomarkers of methanotrophic microorganisms are also found. A positive correlation between the contents of the studied biomarkers and the contents of pelite and total organic carbon is observed at the sites with documented intense methane bubbling. For example, the average content of C30 hopenes at the “methane” stations is twice higher than that at the “background” ones. The average content of C32 αβ-hopanes in sediment samples from the methane seepage area is 1.5 times higher than that at the background stations. We suggest that the increased C30 αβ-hopane content (~1.5 times higher within the methane seepage area) and the decreased moretane index relative to the C31 hopane index are due to the inflow of OM of petroleum origin. The presence of biphenyl in sediments indicates its petroleum origin, which supports our assumption of the migratory nature of petroleum hydrocarbons in the methane seepage area. Triterpenoids found in the sediment OM indicate diagenetic bacterial transformation of OM in the methane seepage areas, which shows that methane has been released for a long time. We assume the intense activity of the consortium of methanotrophs and sulfate reducers in the methane seepage areas.


https://doi.org/10.1111/1755-6724.14285

As the two important components of shale, organic matter (OM) and clay minerals are usually thought to strongly influence the hydrocarbon generation, enrichment and exploitation. The evolution process of OM and clay minerals as well as their interrelationship over a wide range of thermal maturities are not completely clear. Taking Yanchang (T3y), Longmaxi (S1l) and Niutitang (Є1n) shales as examples, we have studied the microstructure characteristics of OM and clay minerals in shales with different thermal maturities. The effects of clay minerals and OM on pores were reinforced through sedimentation experiments. Using a combination of field emission scanning electron microscopy (FE SEM) and low pressure N‐ ‐ 2 adsorption, we investigated the microstructure differences among the three shales. The results showed that both OM and clay minerals have strong effects on pores, and small mesopore (2–20 nm) is the dominant pore component for all three samples. However, the differences between the three samples are embodied in the distribution of pore size and the location. For the T3y shale, clay minerals are loosely arranged and develop large amounts of pores, and fine OM grains often fill in intergranular minerals or fractures. Widespread OM pores distribute irregularly in S1l shale, and most of the pores are elliptical and nondirectional. The Є1n shale is characterized by the preferred orientational OM clay aggregates, and lots of pores ‐in the composites are in the mesopore range, suggesting that over maturity lead to the collapse and compaction of pores under huge pressure of strata. The results of the current research imply that with increasing thermal maturity, OM pores are absent at low maturity (T3y), are maximized at high

maturity (S1l) and are destroyed or compacted at over mature stage (Є‐ 1n). Meanwhile, clay minerals have gone through mineral transformation and orientational evolution. The interaction of the two processes makes a significant difference to the microstructure evolution of OM and clay minerals in shale, and the findings provide scientific foundation in better understanding diagenetic evolution and hydrocarbon generation of shale.

Guan, X., Luong, J., Yu, Z., Jiang, H., 2020. Quasi-stop-flow modulation strategy for comprehensive two-dimensional gas chromatography. Analytical Chemistry 92, 6251-6256.


An easy-to-implement strategy of differential flow modulation for comprehensive two-dimensional gas chromatography was innovated. With this approach, an independent auxiliary pneumatic control device for flow modulation was not a prerequisite. The strategy involved splitting the carrier gas stream into two separate streams before reaching the inlet embodiment. One stream was employed as a mobile phase for chromatographic separation. The other stream, for flow modulation, was routed to one of the ports of a three-way solenoid valve. The modulation stream flowed onward to a fluidic path and a T-junction that joined the primary and secondary dimension columns. With this arrangement and depending on the configuration of the three-port valve, the analytical platform can be operated in three different modes: bypass stop-flow, vent stop-flow, and quasi-stop flow. Quasi-stop-flow mode was demonstrated to have a significantly better chromatographic performance, as demonstrated in various types of real-life petroleum samples such as gasoline and light cycle oil. In the light cycle oil sample, a respectable separation between compound classes was achieved with peak width at half height of 34 ms or less for alkanes on a second dimension with polyethylene glycol stationary phase. Excellent repeatability was shown with normal alkanes standards of nC8-nC25. Relative standard deviations for retention times are almost zero in 1D, less than 0.2% in 2D, and less than 3.5% for peak areas (n = 9).

Guellala, R., Abdelmoumen, K., Sarsar Naouali, B., Mahroug, A., 2020. Contribution of well logging and seismic reflection to the Jurassic petroleum system characterization in the Chotts zone (Southern Tunisia). Journal of Petroleum Exploration and Production Technology 10, 1763-1773.

https://doi.org/10.1007/s13202-020-00871-y

In the Chotts zone central part (southern Tunisia), the Jurassic series are interesting for hydrocarbon exploration. However, these series’ composition and geometry are little studied to propose prospection programs. Using boreholes and seismic reflection data, the present study aims a better characterization of the Jurassic series in the Chotts zone central part, in view of petroleum prospects identification. The analysis of the lithological columns and their corresponding well logs highlights an interesting petroleum system: The Tithonian, Kimmeridgian and Oxfordian carbonated deposits are the main reservoirs formations, whereas the Kimmeridgian and Callovian clays constitute the source rocks. The seal rocks are composed of the Jurassic clayey intercalations. Forty-four seismic reflection profiles calibrated using the time–depth relation in petroleum wells are interpreted in this study. The reflectors corresponding to the Malm, Dogger and Lias tops are identified and picked on the different seismic profiles. The isochrone, isobath and isopach maps subsequently deduced disclose important tectonic features that affect the Jurassic series in the Chotts zone and control their geometry. They highlight two sunken zones separated by a raised structure. This structure

corresponds to an anticline, overturned toward the south, limited by E–W major faults and truncated by other oriented NW–SE. It constitutes an excellent trap structure where five interesting prospects are precisely delimited. Furthermore, the determined tectonic accidents may facilitate the migration of oil from Jurassic source rocks. The findings of this study can help for better understanding of the Jurassic petroleum system in the Chotts area and guide enormously its exploration.

Guo, C., Qin, Y., Ma, D., Xia, Y., Bao, Y., Chen, Y., Lu, L., 2020. Pore structure and permeability characterization of high-rank coal reservoirs: A case of the Bide-Santang Basin, western Guizhou, South China. Acta Geologica Sinica - English Edition 94, 243-252.

https://doi.org/10.1111/1755-6724.14295

Abstract The methods of nuclear magnetic resonance (NMR) spectroscopy, mercury injection porosimetry (MIP), and gas-water relative permeability (GWRP) were used to reveal the pore structure and permeability characteristics of high-rank coal reservoirs in the Bide-Santang basin, western Guizhou, South China, to provide guidance for coalbed methane (CBM) exploration and exploitation and obtain direct insights for the development of CBM wells. The results indicate that the coal reservoirs in the study area are characterized by well-developed adsorption pores and poorly developed seepage pores. The bimodal NMR transverse relaxation time (T2) spectra and the mutation in the fractal characteristic of the MIP pore volume indicate poor connectivity between the adsorption pores and the seepage pores. As a result, the effective porosity is relatively low, with an average of 1.70%. The irreducible water saturation of the coal reservoir is relatively high, with an average of 66%, leading to a low gas relative permeability under irreducible water saturation. This is the main reason for the low recovery of high-rank CBM reservoirs, and effective enhanced CBM recovery technology urgently is needed. As a nondestructive and less time-consuming technique, the NMR is a promising method to quantitatively characterize the pores and fractures of coals.

Guo, J., Li, X., Xu, H., Zhu, H., Li, B., Westwood, A., 2020. Molecular structure control in mesophase pitch via co-carbonization of coal tar pitch and petroleum pitch for production of carbon fibers with both high mechanical properties and thermal conductivity. Energy & Fuels 34, 6474-6482.


Spinnable mesophase pitches C-MP, P-MP, and C/P-MP were synthesized from coal tar pitch, petroleum pitch, and their cocarbonized pitches, respectively. The molecular structures of these mesophase pitches and their effect on the microcrystalline sizes of the mesophase and the properties of carbon fibers derived from them were comparatively investigated. The molecular structures and orientation of the prepared mesophase pitches have significant influence on the performance of resultant carbon fibers. In comparison with P-MP and C/P-MP, C-MP possessing the highest aromaticity, a rigid molecular structure, and a very small amount of methyl groups makes C-MP-CFs with smaller crystal size and lower decomposition during the preparation process and thus results in the best mechanical properties of their carbon fibers, consequently. The prepared P-MP, however, containing abundant methyl groups and possessing a semirigid molecular structure, yields products with higher d002-spacing and larger mesomorphic phase size. The largest crystallite dimension of P-MP combined with its higher molecular orientation makes P-MP-CFs possessing the highest crystal size and axial thermal conductivity. On the other hand, C/P-MP shows the molecular

structure character of both coal tar pitch and petroleum pitch and a tunable mesophase domain orientation. The carbon fiber prepared from cocarbonized C/P-MP shows both good mechanical properties, like C-MP-based fiber, and, in particular, ultrahigh thermal conductivity, like P-MP-based fiber.

Guo, M., Korenaga, J., 2020. Argon constraints on the early growth of felsic continental crust. Science Advances 6, eaaz6234.

http://advances.sciencemag.org/content/6/21/eaaz6234.abstract

The continental crust is a major geochemical reservoir, the evolution of which has shaped the surface environment of Earth. In this study, we present a new model of coupled crust-mantle-atmosphere evolution to constrain the growth of continental crust with atmospheric 40Ar/36Ar. Our model is the first to combine argon degassing with the thermal evolution of Earth in a self-consistent manner and to incorporate the effect of crustal recycling and reworking using the distributions of crustal formation and surface ages. Our results suggest that the history of argon degassing favors rapid crustal growth during the early Earth. The mass of continental crust, highly enriched in potassium, is estimated to have already reached >80% of the present-day level during the early Archean. The presence of such potassium-rich, likely felsic, crust has important implications for tectonics, surface environment, and the regime of mantle convection in the early Earth.

Guo, W., Cecchetti, A.R., Wen, Y., Zhou, Q., Sedlak, D.L., 2020. Sulfur cycle in a wetland microcosm: Extended 34S-stable isotope analysis and mass balance. Environmental Science & Technology 54, 5498-5508.

https://doi.org/10.1021/acs.est.9b05740

The sulfur cycle is an important part of constructed wetland biogeochemistry because it is intimately intertwined with the carbon, nitrogen, and iron cycles. However, to date, no quantitative investigation has been conducted on the sulfur cycle in constructed wetlands because of the complexity of wetland systems and the deficiencies in experimental methodology. In this study, 34S-stable isotope analysis was extended in terms of the calculation for the enrichment factor and the kinetic analysis for bacterial sulfate reduction. With this extended method, we attempted for the first time to assess the true rate of bacterial sulfate reduction when sulfide oxidation co-occurs. The joint application of the extended 34S-stable isotope and mass balance analyses made it possible to quantitatively investigate the primary sulfur transformation in a wetland microcosm. Accordingly, a sulfur cycle model for constructed wetlands was quantified and validated. Approximately 75% of the input sulfur was discharged. The remainder was mainly removed through deposition as acid volatile sulfide, pyrite, and elemental sulfur. Plant uptake was negligible. These findings improve our understanding of the physical, chemical, and biological transformations of sulfur among plants, sediments, and microorganisms, and their interactions with carbon, nitrogen, and iron cycles, in constructed wetlands and similar systems.

Guo, Z.Y., Wang, H.N., Jiang, M.J., 2020. Elastoplastic analytical investigation of wellbore stability for drilling in methane hydrate-bearing sediments. Journal of Natural Gas Science and Engineering 79, 103344.


Methane hydrates (MHs) are popular clean energy resources. The dissociation of MHs near the wellbore wall during drilling in marine methane hydrate-bearing sediments (MHBS) significantly reduces the bearing capacity of the wellbore and increases the risk of wellbore instability. In this study, a new elastoplastic analytical solution for wellbore stability during drilling in MHBS is provided, taking into account the reduction in the stiffness and strength of the formation after the hydrates dissociate, the conduction/diffusion and convection of heat/ion transfer, and the partial coupling among the seepage, temperature, salt concentration and mechanical fields.

An axisymmetric plane strain problem is simplified by diving the infinite region into several annular regions with different physical properties. The distribution of pore pressure at a specific time for this multi-region problem is first obtained by introducing an influence radius estimated by the common unsteady flow solution. Accordingly, the conduction/diffusion and convection effects on the temperature and salt concentration fields are provided for balanced, underbalanced and overbalanced drilling conditions, and the dissociated region is finally addressed through the hydrate phase equilibrium equation fitted by numerous experimental data. Then, the mechanical responses of the wellbore in an elastic-brittle-plastic formation are analytically analysed by employing unified strength theory, considering two principal stress orders and three plastic zone locations.

The analytical solution agrees very well with the numerical results determined under the same assumptions, and the solutions of the influence radii of the pressure and temperature and distribution of the pressure and effective stress around the wellbore are consistent with the results from complex numerical simulations. A detailed parametric study is carried out to investigate the specific influence of the drilling fluid properties, the size of the dissociated region and the reduction in Young's modulus/cohesion due to hydrate dissociation on wellbore stability during drilling in MHBS.

Gussone, N., Ahm, A.-S.C., Lau, K.V., Bradbury, H.J., 2020. Calcium isotopes in deep time: Potential and limitations. Chemical Geology 544, 119601.


Calcium is an essential element in the biogeochemical cycles that regulate the long-term climate state of Earth. The removal of CO2 from the ocean-atmosphere system is controlled by the burial of carbonate sediments (CaCO3), ultimately linking the global calcium and carbon cycles. This fundamental link has driven the development of the stable calcium isotope proxy with application to both ancient skeletal and non-skeletal bulk carbonate sediments. Calcium isotope ratios (δ44/40Ca) have been used to track long-term changes in seawater chemistry (e.g., aragonite vs. calcite seas) and to elucidate short-term climatic perturbations associated with mass extinction events. However, developments in the calcium isotope proxy have shown that δ44/40Ca values in carbonate minerals also are sensitive to changes in precipitation rates, mineralogy and diagenesis, thereby complicating the application of the proxy to the reconstruction of global cycles. First, inorganic carbonate precipitation experiments have demonstrated that carbonate δ44/40Ca values are sensitive to precipitation rates with higher rates generally leading to larger fractionation. Second, δ44/40Ca values are sensitive to carbonate mineralogy with inorganic aragonite and calcite being on average ~ 1.5‰ and ~ 0.9‰ depleted relative to contemporaneous seawater, respectively. The effects of both changes in carbonate mineralogy and precipitation rates affect primary and secondary minerals, but

are particularly pronounced during carbonate diagenesis where relatively slow rates of recrystallization and neomorphism can lead to significant changes in bulk sediment δ44/40Ca values. Third, changes in faunal composition expressed in skeletal fossil archives can lead to large changes in carbonate δ44/40Ca values that are decoupled from changes in global cycles. Nevertheless, when these factors are appropriately considered the application of calcium isotopes in ancient carbonate sediments becomes a powerful tool for understanding biogeochemical processes that operate over many scales; from diagenetic changes within the sediment pore-space, to regional changes across ancient carbonate platforms, and to global changes in seawater chemistry through time. Importantly, the processes that contribute to variability in carbonate δ44/40Ca values are likely to impact other carbonate-bound proxies, highlighting the potential for calcium isotopes as a tool to better understand the variability of other isotope systems.



Hydrothermal vent fields found at mid-ocean ridges emit hydrothermal fluids that disperse as neutrally buoyant plumes. From these fluids seafloor massive sulfides (SMS) deposits are formed, which are being explored as possible new mining sites for (trace) metals and rare earth elements (REEs). It has been suggested that during mining activities large amounts of suspended matter will appear in the water column due to excavation processes and discharge of mining waste from the surface vessel. Understanding how hydrothermal plumes can be characterised by means of geochemistry and microbiology as they spread away from their source and how they affect their surrounding environment may help in characterising the behaviour of the dilute distal part of chemically enriched mining plumes.

This study on the extensive Rainbow hydrothermal plume, observed up to 25 km downstream from the vent site, enabled us to investigate how microbial communities and (trace) metal composition change in a natural plume with distance. The (trace) metal and REE content of suspended particulate matter (SPM) was determined using sector field inductively coupled plasma mass spectrometry (SF-ICP-MS) with high resolution (HR), and the microbial communities of the neutrally buoyant plume, above-plume, below-plume, and near-bottom water and sediment were characterised by using 16S rRNA amplicon sequencing methods. Both vertically in the water column and horizontally along the neutrally buoyant plume, geochemical and biological changes were evident, as the neutrally buoyant plume stood out by its enrichments in (trace) metals and REEs, as, for example, Fe, Cu, V, Mn and REEs were enriched by factors of up to ∼80, ∼90, ∼52, ∼2.5 and ∼40, respectively, compared to above-plume water samples taken at 1000 m water depth. The concentrations of these elements changed as the plume aged, shown by the decrease in element ∕ Fe molar ratios of chalcophile elements (Cu, Co, Zn), indicative of rapid removal from the hydrothermal plume or removal from the solid phase. Conversely, increasing REE ∕ Fe molar ratios imply uptake of REEs from the ambient seawater onto Fe-oxyhydroxides. This was also reflected in the background pelagic system, as Epsilonproteobacteria started to dominate and univariate microbial biodiversity declined with distance away from the Rainbow hydrothermal vent field. The Rainbow hydrothermal plume provides a geochemically enriched natural environment, which is a heterogeneous, dynamic habitat that is conducive to ecological changes in a short time span. This study of a hydrothermal plume

provides a baseline study to characterise the natural plume before the interference of deep-sea mining.

Haffert, L., Haeckel, M., de Stigter, H., Janssen, F., 2020. Assessing the temporal scale of deep-sea mining impacts on sediment biogeochemistry. Biogeosciences 17, 2767-2789.


Deep-sea mining for polymetallic nodules is expected to have severe environmental impacts because not only nodules but also benthic fauna and the upper reactive sediment layer are removed through the mining operation and blanketed by resettling material from the suspended sediment plume. This study aims to provide a holistic assessment of the biogeochemical recovery after a disturbance event by applying prognostic simulations based on an updated diagenetic background model and validated against novel data on microbiological processes. It was found that the recovery strongly depends on the impact type; complete removal of the reactive surface sediment reduces benthic release of nutrients over centuries, while geochemical processes after resuspension and mixing of the surface sediment are near the pre-impact state 1 year after the disturbance. Furthermore, the geochemical impact in the DISturbance and reCOLonization (DISCOL) experiment area would be mitigated to some degree by a clay-bound Fe(II)-reaction layer, impeding the downward diffusion of oxygen, thus stabilizing the redox zonation of the sediment during transient post-impact recovery. The interdisciplinary (geochemical, numerical and biological) approach highlights the closely linked nature of benthic ecosystem functions, e.g. through bioturbation, microbial biomass and nutrient fluxes, which is also of great importance for the system recovery. It is, however, important to note that the nodule ecosystem may never recover to the pre-impact state without the essential hard substrate and will instead be dominated by different faunal communities, functions and services.

Hakimi, M.H., Ahmed, A., Mogren, S., Ali Shah, S.B., Kinawy, M.M., Lashin, A.A., 2020. Thermogenic gas generation from organic-rich shales in the southeastern Say'un-Masila Basin, Yemen as demonstrated by geochemistry, organic petrology, and basin modeling. Journal of Petroleum Science and Engineering 192, 107322.


The current study aimed to explore the gas-generating potential and oil-to-gas conversion in the Madbi oil-source rock system based on data from deep well within the Say'un-Masila Basin using both geochemical and petrological methods as well as basin models. Biomarker results for the bitumen from analyzed shale samples indicate mixed organic matter, with mainly phytoplankton, bacteria, and some terrigenous land plants, deposited under relatively anoxic marine environmental conditions. The terrigenous organic matter, and rich in lipids from phytoplankton and bacteria, suggests Types II and II/III as the original organic matter during deposition. Such findings are not consistent with the significant amounts of vitrinite and inertinite that found under microscope and the low current hydrogen index (HI) values of 43–282 (Types III/IV and III/II kerogen) of the analyzed shale samples. The chemical and optical maturity indicators show that the Madbi shales throughout the studied well section are at different thermal maturity stages, consistent with late-mature stage of the oil window to gas-generation window. Therefore, this high thermal maturation is the critical factor that significantly modifies the original organic matter.

Based on the basin models of the single well studied (Ghayl Bin Yumain-01), the initial conversion of kerogen to oil, occurring between the Late Cretaceous and Late Eocene (75–38 Ma), corresponding to peak-oil window (0.70–1.00 Easy %Ro). Furthermore, the oil was expelled during the Late Eocene to Early Oligocene; hence, the late-mature stage of the oil window (1.00–1.30 Easy %Ro) commenced during this time, with transformation ratios (TR) of 50–70%. Subsequently, the cracking of the retained oil into gas has occurred from the Early Oligocene through the present and is attributed to the high thermal maturation of the gas window (>1.30 Easy %Ro), with maximum TRs of 70–97%.

Haklay, G., Gopher, A., 2020. Geometry and architectural planning at Göbekli Tepe, Turkey. Cambridge Archaeological Journal 30, 343-357.

https://doi.org/10.1017/S0959774319000660

The site of Göbekli Tepe in southeastern Turkey keeps fascinating archaeologists as it is being exposed. The excavation since 1995 has been accompanied by a lively discussion about the meaning and implications of its remarkable early Neolithic megalithic architecture, unprecedented in its monumentality, complexity and symbolic content. The building history and the chronological relations between the different structures (enclosures), however, remain in many ways a challenge and open to further analysis. The study presented here is an attempt to contribute in this direction by applying a preliminary architectural formal analysis in order to reconstruct aspects of the architectural design processes involved in the construction of the monumental enclosures. This is done under the premise that such investigation would shed light on the chaîne opératoire of the enclosures' construction and their history, thus enabling a fresh look as well as an evaluation of past suggestions regarding these structures and the people who built them. Indeed, the results of the analysis brought to light an underlying geometric pattern which offers a new understanding of the assemblage of architectural remains indicating that three of the stone-built large enclosures were planned and initially built as a single project.

Halbwachs, M., Sabroux, J.-C., Kayser, G., 2020. Final step of the 32-year Lake Nyos degassing adventure: Natural CO2 recharge is to be balanced by discharge through the degassing pipes. Journal of African Earth Sciences 167, 103575.


In wake of the lakes Monoun and Nyos disasters, the aim of the Nyos Organ Pipes Program was clearly to mitigate the hazard of a limnic eruption at both lakes in the coming decades. Due to the carbon dioxide natural recharge of the Nyos lake water, the self-siphon degassing pipes had been progressively scaled up since 1992 in order to liberate most of the CO2 content of the lake in a reasonable time. One of the pipes was also fine-tuned to exactly counterbalance for the CO2 recharge on the long term. In less than thirty years, both objectives have been met by a team of French scientists, engineers and technicians. Here we show that the continuous operation of no more than a single degassing pipe, as already installed in Lake Nyos since 2001 and refurbished in 2011, could match the natural CO2 recharge rate. The safeguarding, without any human intervention, of a visible water jet, equally feasible at Lake Monoun, will sustain the awareness of scientists and institutions in charge, and will perpetuate their commitment to decrease the risk of a new disaster among the Nyos and Monoun lakeside residents.

Han, Q., Li, M., Liu, X., Jiang, W., Shi, S., Tang, Y., He, D., 2020. Fractionation of alkylated carbazoles in petroleum during subsurface migration: Evidence from molecular simulation and application in sandstone reservoirs. Journal of Petroleum Science and Engineering 191, 107308.


Carbazole (CA) and alkylated carbazoles are common nitrogen-containing heterocyclic aromatic compounds widely found in crude oils and sedimentary rocks extracts. Their geochemical significances in petroleum exploration have been widely investigated in previous studies. Using density functional theory (DFT) and molecular dynamics (MD) simulation, we calculated the polarity of alkylated carbazole isomers/homologues and their adsorption energy with water and α-quartz, respectively. The calculated results show that there are significant differences in migration fractionation effects for alkylated carbazole isomers/homologues. This study confirmed the validity of previously proposed carbazole migration indicators, i.e. 4-/1-MCA (the relative abundance of 4-methylcarbazole to 1-methylcarbazole), 2,5-/1,8-DMCA (2,5-dimethylcarbazole to 1,8-dimethylcarbazole) and 2,4-/1,8-DMCA (2,4-dimethylcarbazole to 1,8-dimethylcarbazole) on the basis of quantum chemistry and molecular simulation. All these three parameters have been successfully applied in a lacustrine sandstone reservoir in the Fushan Depression, Beibuwan Basin (South China Sea). The calculations of Gibbs free energy show that the differences in thermal stability between the isomers of alkylcarbazoles can be negligible. The source input and depositional environment have no significant effect on these indicators for oils from a same oil family. Hence, the values of these parameters are mainly controlled by subsurface petroleum migration processes. Therefore, the molecular parameters relative to alkylated carbazoles can be used as practically effective geochemical markers to trace the oil filling orientation and pathways for subsurface oil migration.

Han, T., Fan, H., Wen, H., Mo, B., Murowchick, J.B., Lu, Z., Algeo, T.J., 2020. Petrography and sulfur isotopic compositions of SEDEX ores in the early Cambrian Nanhua Basin, South China. Precambrian Research 345, 105757.


Widespread Ni-Mo sulfide mineralization in South China during the early Cambrian may have affected the seawater chemistry and biodiversity of this region, but its underlying causes are not well-understood. To better understand the formation of sulfide ores in early Cambrian marine systems, this study evaluated the paragenesis and sulfur isotopic composition (δ34S) of sediment-hosted Ni-Mo sulfide ores in the lower Cambrian Niutitang Formation of the Nanhua Basin of South China. Petrographic analysis revealed three types of sulfide aggregates: (1) ubiquitous framboidal and euhedral pyrite (Py-1), (2) a MoSC phase (i.e., Mo mineralization) that was cogenetic with larger pyrite cubes or nodules (Py-2), and (3) intergrown millerite (NiS), sphalerite (ZnS) and veined pyrite (Py-3) (i.e., Ni-Zn mineralization) characterized by laminated and veined textures. Alternating precipitation of Mo and Ni-Zn sulfides was caused by intermittent emission of Mo-Fe or Ni-Zn-rich hydrothermal fluids into euxinic mid-depth waters of the Nanhua Basin, representing a sedimentary exhalative (SEDEX) process. The different sedimentary ore textures are each associated with a characteristic δ34S distribution. At all study sites, the syngenetic Py-1 phase yields δ34S of −15.7 to + 1.9‰, consistent with a seawater sulfate source that was variably fractionated through microbial sulfate reduction (MSR). In the Nayong and Zunyi areas, δ34S values of −11.8 to +4.4‰ are associated with the MoSC phase, and −20.6 to −6.8‰ with the Py-2 phase. In the Zhangjiajie area,

Py-2 yields similar values (−25.1 to −10.8‰) but MoSC higher and less variable values (+8.6 to +18.7‰). These phases are thought to contain a mixture of sulfur sourced from seawater sulfate (via MSR) and hydrothermal fluids in varying proportions. A mode of Ni-Zn sulfides δ34S values between −9.1 and +8.0‰ is likely to represent the isotopic composition of hydrothermal sulfur inputs to the Ni-Zn mineralization. As a consequence, both hydrothermal emissions and biogenic production of H2S had a significant influence on seawater chemistry, with consequences for contemporaneous evolution of early marine animal life (e.g., the small shelly fauna and Chengjiang Biota) in the early Cambrian Nanhua Basin.



During an expedition in 2012 we recovered sediment, water, and biological samples from the inner slope of the Mariana Trench using a lander equipped with cameras, three twenty-liter Niskin bottles, a baited net trap, and a pressure calibrated depth sensor. Images and samples collected from the 10,677 m drop site reveal filamentous structures covering both talus and outcrop, which we cautiously identify as a microbial mat community. Analyses of retrieved sediments and images of the outcrop indicate that serpentinization of exposed ultramafic rock may be the source of the chemical energy needed to sustain this ecosystem. If true, this is the deepest known such community to be identified in Earth's ocean.

Hanna, H.D., Liu, X.-M., Park, Y.-R., Kay, S.M., Rudnick, R.L., 2020. Lithium isotopes may trace subducting slab signatures in Aleutian arc lavas and intrusions. Geochimica et Cosmochimica Acta 278, 322-339.


We report [Li] and δ7Li values for a well-characterized suite of 52 geographically (165–184°W), compositionally (SiO2 = 46–70 wt.%), and temporally (0–38 Ma) diverse lavas and intrusive samples. The δ7Li in these rocks range from −0.7‰ to +14.2‰, with 32 of the 35 lavas and 12 of the 17 intrusive samples falling within the depleted mantle range (δ7Li +1.6 to +5.6‰), as sampled by mid-ocean ridge basalts (MORB). The δ7Li values of Aleutian lavas do not exhibit the spatial trends observed in other slab component tracers, nor do δ7Li values correlate with any slab component indicators, such as radiogenic isotopes, oxygen isotopes, or trace element ratios such as Cs/La and Th/La. The δ7Li values in Aleutian intrusions also do not exhibit temporal trends, however, an overall positive relationship exists between δ7Li and Th/Nd. Mixing models for δ7Li and 143Nd/144Nd values suggest that Aleutian samples within or above the MORB δ7Li range can be explained by addition of <1–2% sediment-derived aqueous fluid and ≤3% sediment melt to depleted mantle; both are required to explain the range in δ7Li that is observed. Sediment-derived fluid exerts a stronger control on Aleutian samples having higher δ7Li values than the MORB range, while sediment melt skews the Li isotopic compositions of MORB-range samples to slightly lower values than if sediment fluid was the only slab influence. Our study demonstrates that a slab signature may be deciphered via modeling even in arcs where spatial trends in δ7Li values and correlations with slab component indicators are lacking.

Hanna, R.D., Hamilton, V.E., Haberle, C.W., King, A.J., Abreu, N.M., Friedrich, J.M., 2020. Distinguishing relative aqueous alteration and heating among CM chondrites with IR spectroscopy. Icarus 346, 113760.


Using infrared (IR) spectroscopy of thin sections, we characterize the relative degree of aqueous alteration and subsequent heating of a suite of CM chondrites to document spectral indicators of these processes that can contextualize observations of carbonaceous asteroids. We find that the progressive aqueous alteration of CMs manifests in two spectral regions. The low-wavenumber region (1200–400 cm−1; 8–25 μm) records the increasing proportion of Mg-Fe phyllosilicates relative to anhydrous silicates as aqueous alteration proceeds, with a highly correlated shift of the Christiansen feature (CF) to lower wavenumber and the Si-O bending band minimum to higher wavenumber, and an increase in depth of the Mg-OH band (~625 cm−1). The strongest correlation (R2

= 0.90) with petrologic subtype is the distance between the CF and Si-O stretching band minimum, which predicts the petrologic subtype of the sample to within 0.1. The high-wavenumber region (4000–2500 cm−1, ≤3.33 μm) probes the variation in abundance and composition of Mg-Fe serpentine and tochilinite among the altered CMs. All moderately to highly altered CMs (≤2.3) have an OH/H2O (‘3 μm’) band emission maximum of 3690 cm−1 (2.71 μm) indicative of Mg-bearing serpentine, and mildly aqueously altered CMs (≥ 2.5) have a wider band with a complex shape that results from contributions of Fe-bearing serpentine and tochilinite. Among weakly heated CMs (Stage II; 300–500 °C), the low-wavenumber region exhibits spectral features resulting from the dehydration and dehydroxylation of phyllosilicates that include broadening of the Si-O stretching band and a shift of its minimum to lower wavenumber, and the disappearance of the Mg-OH band. The location of the Si-O bending band minimum appears to be unaffected by mild heating. Extensively heated CMs (Stage III+; > 500 °C) have a low-wavenumber region dominated by the spectral features of secondary, Fe-bearing olivine and low-Ca pyroxene and thus are readily distinguished from unheated and mildly heated CMs. The OH/H2O band of all heated CMs is broad and rounded with an emission peak at lower wavenumbers (≤3636 cm−1; ≥2.75 μm) than in unheated CMs. However, spectral and petrographic evidence suggests that our heated CMs have been compromised by terrestrial rehydration. Our study confirms that thermal metamorphism effects are concentrated within the matrix and suggests that the matrix of the CM WIS 91600 had a CI-like mineralogy prior to heating.

Hao, J., Knoll, A.H., Huang, F., Schieber, J., Hazen, R.M., Daniel, I., 2020. Cycling phosphorus on the Archean Earth: Part II. Phosphorus limitation on primary production in Archean ecosystems. Geochimica et Cosmochimica Acta 280, 360-377.


Several lines of evidence point to low rates of net primary production (NPP) in Archean oceans. However, whether Archean NPP was limited by electron donors or nutrients, particularly phosphorus (P), and how these factors might have changed over a billion years of recorded Archean history, remains contentious. One major challenge is to understand quantitatively the biogeochemical cycling of P on the early Earth. In Part I of this series (Hao et al., 2020), we estimated the weathering flux of P to the oceans as a function of temporally increasing continental emergence and elevation through Archean time. In Part II, we conduct thermodynamic and kinetic simulations to understand key processes of P cycling within the Archean ocean, including seafloor weathering,

recycling of organic P, the solubility and precipitation of secondary phosphate minerals, and the burial diagenesis of P precipitates. Our calculations suggest low solubilities of apatite minerals in Archean seawater, primarily due to nearly neutral pH and high levels of Ca. This low solubility, in turn, implies a negligible contribution of apatite dissolution to P bioavailability in Archean seawater.

We also simulate the solubility limits of common secondary P-bearing minerals, showing that vivianite would have been the least soluble P mineral in ferruginous Archean seawater (0.1–0.3 µM), even at moderate supersaturation states (Ω = 100 or 1000). If vivianite precipitation was kinetically favorable by microbial activities and mineral adsorption, the sinking flux of P as vivianite in Archean seawater could have reached the modern sinking flux, implying that vivianite precipitation was a potentially major sink for P in Archean oceans. During burial diagenesis, however, vivianite in porewater would have become less stable than Ca-phosphates of lower solubility. At elevated temperatures (>100 °C) associated with burial diagenesis and low-grade metamorphism, vivianite is predicted to react irreversibly with calcite to form apatite.

Optimistic assumptions about the recycling efficiency of P on the Archean Earth lead us to estimate that by the end of the eon the total flux of P (continental weathering + recycling) could have supported NPP at levels up to 7% of the modern. The total flux of P would have been much lower on the early and middle Archean Earth, whereas fluxes of electron donors could have been higher, suggesting very low productivity and P-limitation of marine ecosystems during much of the eon. Comparing our estimates of NPP as limited by P supply with the estimate by Ward et al. (2019), in which NPP was limited by electron donors and metabolic efficiency, there could have been a transition between P-limited productivity in the early to middle Archean to electron donor-limitation closer to the eon’s end (assuming no oxygenic photosynthesis). Once oxygenic photosynthesis reached ecological significance, probably near the end of the Archean, our estimated flux of P would allow rapid oxidation of atmosphere.

Haqq-Misra, J., Kopparapu, R.K., Schwieterman, E., 2020. Observational constraints on the Great Filter. Astrobiology 20, 572-579.

https://doi.org/10.1089/ast.2019.2154

The search for spectroscopic biosignatures with the next generation of space telescopes could provide observational constraints on the abundance of exoplanets with signs of life. An extension of this spectroscopic characterization of exoplanets is the search for observational evidence of technology, known as technosignatures. Current mission concepts that would observe biosignatures from ultraviolet to near-infrared wavelengths could place upper limits on the fraction of planets in the Galaxy that host life, although such missions tend to have relatively limited capabilities of constraining the prevalence of technosignatures at mid-infrared wavelengths. Yet searching for technosignatures alongside biosignatures would provide important knowledge about the future of our civilization. If planets with technosignatures are abundant, then we can increase our confidence that the hardest step in planetary evolution—the Great Filter—is probably in our past. But if we find that life is commonplace while technosignatures are absent, then this would increase the likelihood that the Great Filter awaits to challenge us in the future.

Harrison, A.W., Waterson, A.M., De Bruyn, W.J., 2020. Spectroscopic and photochemical properties of secondary brown carbon from aqueous reactions of methylglyoxal. ACS Earth and Space Chemistry 4, 762-773.


Chromophoric organic compounds in the atmosphere termed brown carbon (BrC) play an important role in tropospheric photochemistry and radiative forcing due to their absorption in the near-UV region of the solar spectrum (300–400 nm). BrC chromophores can form in secondary reactions of carbonyls with ammonium and amine precursors commonly found in aqueous aerosols and cloud water, although there is still uncertainty regarding the contribution of these reactions to atmospheric BrC. Herein, experimental results are presented characterizing the spectroscopic properties of BrC generated from aqueous aerosol/cloud water mimics containing methylglyoxal and ammonium sulfate (MG + AS) or methylamine chloride (MG + MA). Spectroscopic results include mass absorption coefficients, fluorescence quantum yields, and excitation–emission matrix (EEM) spectra, including parallel factor (PARAFAC) analysis. This work also provides a detailed comparison to previous laboratory and field measurements on the classification of aerosols and environmental water with EEM spectroscopy. In addition to spectroscopic characterization, the chemical composition of these samples is investigated using electrospray ionization mass spectrometry and shows the formation of oligomers of methylglyoxal- and nitrogen-containing heterocycles as contributors to absorption in the near-UV consistent with the previous work. The BrC samples were also irradiated using a solar simulator to study the changes in the optical properties and estimate the atmospheric photolytic lifetimes, which have not been previously reported for MG + MA BrC. These results reveal that BrC derived from MG + MA is more stable under solar irradiation than MG + AS BrC with measured atmospheric photolytic half-lives of 39 ± 8 and 12 ± 3 min, respectively.


https://doi.org/10.1111/1758-2229.12831

Transmission electron microscopy (TEM) and rock magnetic study of ferromanganese nodule sample JC120 104B collected from Clarion Clipperton zone (CCZ) in the eastern Pacific Ocean indicate the ‐ ‐presence of biogenic magnetite (magnetofossils). First order reversal curves (FORCs) and ‐decomposition of isothermal remanent magnetization (IRM) curves were used as the main tool for the characterization of magnetic properties of the bulk magnetic minerals present in the sample. TEM was performed for the direct identification of biogenic magnetic minerals (magnetofossils). The nodule sample has distinctive alternating Mn and Fe rich layers per micro X ray fluorescence data. ‐ ‐ ‐While diagenetic precipitation of Mn is known for the less oxygenated environment, the presence of biogenic magnetite is also common in the environments where the supply of oxygen is limited. Moreover, the increase in magnetic properties is consistent with the increase in Mn content, which ‐is related to favourable conditions for Mn precipitation as well as magnetite biomineralization in oxic suboxic transition zone. Investigations on magnetofossil fingerprints lead to a better ‐understanding of paleoenvironmental conditions involved in the formation and growth of deep sea ‐ferromanganese nodules.

Hassan, N., Anesio, A.M., Rafiq, M., Holtvoeth, J., Bull, I., Haleem, A., Shah, A.A., Hasan, F., 2020. Temperature driven membrane lipid adaptation in glacial psychrophilic bacteria. Frontiers in Microbiology 11, 824. doi: 10.3389/fmicb.2020.00824.

https://www.frontiersin.org/article/10.3389/fmicb.2020.00824

Bacteria inhabiting non-polar glaciers are exposed to large variations in temperature, which significantly affects the fluidity of bacterial cell membranes. In order to maintain normal functions of the cell membranes, psychrophilic bacteria adapt by changing the composition of cell membrane fatty acids. However, information on the exact pattern of cell membrane adaptability in non-polar low-temperature habitats is scarce. In the present study, 42 bacterial strains were isolated from the Ghulmet, Ghulkin, and Hopar glaciers of the Hunza Valley in the Karakoram Mountain Range, Pakistan and their cell membrane fatty acid distributions studied, using gas chromatography/mass spectrometry (GC-MS) for the analysis of fatty acid methyl esters (FAMEs) liberated by acid-catalyzed methanolysis. Furthermore, Gram-negative and Gram-positive groups were grown under different temperature settings (5, 15, 25, and 35°C) in order to determine the effect of temperature on cell membrane (CM) fatty acid distribution. The analyses identified the major groups of cell membrane fatty acids (FA) as straight-chain monounsaturated fatty acids (n-MUFAs) and branched fatty acids (br-FAs), accounting for more than 70% of the fatty acids analyzed. The distribution of br-FAs and n-FAs in bacterial cell membranes was significantly affected by temperature, with the level of br-FAs decreasing relative to n-FAs with increasing temperature. Notably, the production of polyunsaturated fatty acids (PUFAs) was only seen at lower temperatures. This study contributes to understanding, for the first time, the role of br-FAs in the maintenance of cell membrane fluidity of bacteria inhabiting non-polar habitats.



Minimum miscibility pressures (MMPs) were measured at reservoir temperatures using a capillary-rise vanishing interfacial tension (VIT) technique for four crude oils collected from different formations in the deep/hot Bakken Petroleum System and the shallow/cool Cut Bank field. Potential injection fluids tested were pure CO2, methane, ethane, propane, and hydrocarbon gas mixtures typical of the rich gas produced from tight shale formations like the Bakken Petroleum System (ca. 7/2/1 mol ratios of methane/ethane/propane). Depending on the oil and test temperature, MMPs were achieved with the fluids in the gas, liquid, or supercritical states. Regardless of the physical state of the test fluids at MMP, propane achieved MMP at the lowest pressure with all four crude oils, followed by ethane, then CO2 and produced gas, and finally methane requiring the highest pressures. For the Bakken (110 °C) and Three Forks crudes (127 °C), MMPs dropped from 29 to 31 MPa with methane from 16.2 to 18.7 MPa with CO2 or produced gas, and further lowered from 9.2 to 10 MPa with ethane, and from 3.8 to 4.3 MPa with propane. Changes in the MMPs with the different fluids were even more dramatic for the Madison and Cut Bank crude oils (both at 28 °C) with methane MMPs about 28–29 MPa, produced gas at 10–10.6 MPa, CO2 at 8.3–8.7 MPa, ethane at 4.2–4.5 MPa, and propane only requiring 1.3–1.4 MPa to achieve MMP. Enriching produced gas by adding either ethane or propane showed approximately linear decreases in the MMPs with the Bakken crude oil. For example, increasing propane in produced gas from 6.7 to 25 mol % reduced

the Bakken crude oil’s MMP from 18 to 12.7 MPa, while increasing ethane from 13.5 to 68 mol % reduced the MMP from 18.6 to 11.4 MPa. The results of this experimental study show that injecting produced rich gas may be as effective as injecting CO2 for enhancing oil recovery and that enriching produced gas with ethane or propane may be superior to CO2 for EOR in both shallow/cool and deep/hot reservoirs.

Hayashi, S., Satoh, Y., Ogasawara, Y., Dairi, T., 2020. Recent advances in functional analysis of polyunsaturated fatty acid synthases. Current Opinion in Chemical Biology 59, 30-36.


Summary Polyunsaturated fatty acids (PUFAs) such as docosahexaenoic acid, eicosapentaenoic acid, and arachidonic acid are essential fatty acids for humans. PUFAs are biosynthesized by either desaturases/elongases from oleic acid or PUFA synthases from acetyl units. PUFA synthases are composed of three or four subunits, and each creates a specific PUFA even though the multiple catalytic domains in each subunit are very similar. We recently dissected these PUFA synthases by in vivo and in vitro experiments and elucidated how the enzymes control PUFA profiles. Moreover, for the first time, we converted a practical microalgal docosahexaenoic acid synthase into an eicosapentaenoic acid synthase based on the results.

He, D., Nemiah Ladd, S., Saunders, C.J., Mead, R.N., Jaffé, R., 2020. Distribution of n-alkanes and their δ2H and δ13C values in typical plants along a terrestrial-coastal-oceanic gradient. Geochimica et Cosmochimica Acta 281, 31-52.


Reconstructing past responses of coastal wetlands to climate change contextualizes ongoing and future developments in these globally important ecosystems. The molecular distributions and stable isotope ratios (δ2H and δ13C) of sedimentary plant wax n-alkanes are frequently used to infer past vegetation and hydroclimate changes in wetland systems. However, there is limited modern information available about these compounds in subtropical wetlands. Here we analyzed mature leaves from 30 typical plant species and roots from 6 plant species collected in the Florida Everglades, including tree island plants, freshwater wetland plants, mangroves, and seagrass. The n-alkane abundance (2 to 884 µg/g dry weight), percent of aquatic plants ratio (Paq, 0 to 1), average chain length (ACL23-33, 24.0–30.7), concentration weighted average (CWA) δ2H (−231 to −78‰) and δ13C values (−38.9 to −14.4‰) spanned wide ranges with plant growth habit. Significant differences in n-alkane abundances, Paq, ACL23-33, CWA δ2H and δ13C values were found to exist between the leaves and roots of some emergent aquatic plants. Simple mass balance calculations of wetland aquatic plants suggest that long chain n-alkanes (e.g., C29 n-alkanes) are predominantly derived from leaves rather than roots in wetland surface sediments/soils. However, the contribution from mid-chain n-alkanes (e.g., C23 n-alkane) from roots may be equal to or greater than those from leaves. This implies that the differences in the isotopic compositions between root and leaf derived material need to be taken into account when interpreting down core changes in mid-chain n-alkane δ2H and δ13C values, which may be derived from variable contributions from leaves and roots rather than a change in hydroclimate or vegetation. Considering the large variation in both n-alkane distribution proxies and isotopic composition, no single molecular index or stable isotope ratio can capture multivariate changes of wetland ecosystems in the past. Nevertheless, principal component analysis

shows promising potential to resolve different plant functional types. Paleo-reconstruction of subtropical aquatic ecosystems using n-alkanes will be most useful if the full molecular and isotopic distribution information of plant waxes are used.



Characterized by high TOC content and large cumulative thickness, the Upper Permian marine-continental transitional facies of shales are widely distributed in southwest China, and are currently becoming a prospective area for shale gas exploration and production. Compared to marine shales, the organic matter (OM) accumulation model and paleo-environmental conditions remain unclear in transitional settings. In this study, core descriptions, thin section and scanning electron microscopy (SEM) observations, X-ray diffraction (XRD) mineralogical analysis, and a major, trace, and rare earth element analysis were integrated to document the varying lithofacies, paleo-environmental conditions, and OM accumulation mechanisms for the Upper Permian transitional facies of the Longtan Formation in northern Guizhou Province, southwest China.

Six major lithofacies, including carbonaceous mudstones, siliceous-clay mixed mudstones, argillaceous mudstones, silty shales, muddy siltstones, and calcareous-clay mixed shales, were identified. The XRD analysis and SEM images suggest that clay (average = 51.2 wt%) and siderite (average = 17.3 wt%) are the dominant minerals in the Longtan Formation, which is different from the mineralogical composition of typical marine shales, which are generally dominated by quartz (e.g. Horn River Shale in the Western Canada Sedimentary Basin, and the Barnett Shale in the Fort Worth Basin). Furthermore, the sedimentological and geochemical analyses suggest that the paleo-environmental conditions and OM accumulation mechanisms of the transitional facies of the Longtan Formation are different from those of marine shales, and can be summarized as follows: (1) terrestrial plant fragments mainly contribute to the TOC contents of the Longtan Formation; (2) paleoproductivity is generally the major influencing factor of OM accumulation in marine shales, but is relatively low during the deposition of the Longtan Formation; (3) terrestrial OM input, redox conditions and sedimentation rate are the major factors controlling OM accumulation; and (4) most of the silica content has detrital origin instead of biogenic origin in the Longtan Formation.

He, Q., Huang, Y., Ding, L., Guo, Q., Gong, Y., Yu, G., 2020. Effect of partial rapid pyrolysis on bituminous properties: From structure to reactivity. Energy & Fuels 34, 5476-5484.


In this paper, typical Chinese bituminous coal was pyrolyzed rapidly and repeatedly in a high-frequency furnace at 1000 °C to investigate the changes of coal physicochemical structures, reactivities, and their relationship. The physicochemical structure was mainly characterized by Fourier transform infrared spectroscopy, Raman spectroscopy, pore analysis, and so forth. The results showed that after the rapid pyrolysis, the specific surface area reduced significantly, the average particle size and the content of amorphous carbon structure increased first and then

decreased, the content of the oxygen-containing group exposed to the surface decreased, and the aromaticity increased gradually. The reactivities were analyzed by thermogravimetric analysis, including slow pyrolysis (from 105 to 1000 °C) and in situ gasification (at 850, 900, 950, and 1000 °C). For slow pyrolysis, the primary decomposition peak of pretreated samples was inhibited, whereas the secondary peak was enhanced. For in situ gasification, the reactivity was promoted after rapid pyrolysis according to the reactivity index. The Coats–Redfern method and model-free method were adopted for kinetic analysis. These reactivity changes were discussed with the evolution of the physicochemical structure in detail. For example, the variation of the decomposition peak in slow pyrolysis was implied by the content of the aliphatic and aromatic in the samples. Besides, the first rapid pyrolysis was found to be more crucial than the second rapid pyrolysis for the changes of the coal structure and reactivity.

He, X.-L., Zhou, D., Gao, H., Huang, F.-q., Li, H., Lv, J., 2020. Dyadobacter bucti sp. nov., isolated from subsurface sediment. International Journal of Systematic and Evolutionary Microbiology 70, 2281-2287.

https://doi.org/10.1099/ijsem.0.004030

A Gram-reaction-negative, yellow-pigmented, rod-shaped, aerobic, non-motile, non-spore-forming bacterium, designated strain QTA69T, was isolated from a subsurface sediment sample collected at the Qiangtang basin, Qinghai–Tibetan Plateau, PR China. Cells were catalase-positive and oxidase-negative. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain QTA69T was a member of the genus Dyadobacter and was closely related to Dyadobacter sediminis , Dyadobacter ginsengisoli and Dyadobacter psychrophilus with sequence similarities from 97.90 % to 96.85 %. Strain QTA69T grew at 4–35 °C, and the optimum temperature was 25–28 °C. It grew at the pH range of 6.0–9.0 (optimum, pH 7.0–8.0) and its NaCl tolerance was 0–2.0 % (optimum, 0–1.0 %). The major cellular fatty acids were summed feature 3 (iso-C15 : 0 2-OH and C 16:1ω6c/C16 : 1ω7c), iso-C15 : 0

and C16 : 1ω5c. The major respiratory quinone was MK-7 and the major polar lipid was phosphatidylethanolamine. Genome sequencing revealed a genome size of 8.41 Mbp and a G+C content of 46.87 mol%. Based on whole genome average nucleotide identity values, phenotypic data, phylogenetic data and genotypic data, strain QTA69T represents a novel species of genus Dyadobacter , for which the name Dyadobacter bucti sp. nov is proposed. The type strain is QTA69T (=CGMCC 1.13688T=KCTC 72024T).

He, Z., Nie, H., Hu, D., Jiang, T., Wang, R., Zhang, Y., Zhang, G., Lu, Z., 2020. Geological problems in the effective development of deep shale gas: a case study of Upper Ordovician Wufeng-Lower Silurian Longmaxi formations in Sichuan Basin and its periphery. Acta Petrolei Sinica 41, 379-391.

http://www.syxb-cps.com.cn/EN/abstract/abstract5875.shtml

Deep shale gas is the main alternative field for shale gas exploration and development in China. The deep shale gas in Wufeng Formation and Longmaxi Formation in Sichuan Basin and its periphery has a geological environment of high temperature, high pressure and high crustal stress. With the increase of deep overburden pressure, the reservoir porosity is reduced by 15%-20%, the permeability by 90%-95%, and the contribution of fractures in shale to permeability is decreased significantly. The deep gas content varies in different regions in Wufeng Formation and Longmaxi Formation, but generally varies little in the middle-shallow shale that has been exploited. The gas

content is mainly controlled by the original sedimentary conditions and later preservation conditions. Deep shale underwent less structural uplift and erosion, and had good oil and gas preservation conditions. Deep shale formations are characterized by high temperature, large crustal stress, and high stress difference, which can easily lead to the enhanced shale plasticity, difficulties in fracture initiation and propagation, and high closure pressure in shale. For this reason, the proppant was cracked, thus influencing the propping degree of fracturing fractures; fracture conductivity decreases rapidly, and it is difficult to maintain the long-term conductivity. The biogenic siliceous shale in the WF2-LM4 graptolite zone is characterized by high quartz content and strong resistance to compaction, which are conducive to the formation and preservation of effective reservoirs. However, due to the large brittleness and rapid development of natural fractures, the lower limit of "sweet window" of the shale may exceed 5 km, which is the optimal interval for deep shale gas development. The enrichment degree of deep shale gas is mainly related to the superior congenital sedimentary and diagenetic conditions, burial and hydrocarbon generation and expulsion history, amplitude of later uplift, and differences in structural deformation. Shale gas can be fully exploited to successfully achieve the large-scale effective development of deep shale gas by optimizing the distribution areas of deep shale with high brittleness, high porosity and permeability, high pressure coefficient and high gas conten, establishing a suitable method of volume fracturing treatment in deep shale, and a reasonable production system through continuous optimization.

He, Z., Nie, H., Li, S., Luo, J., Wang, H., Zhang, G., 2020. Differential enrichment of shale gas in upper Ordovician and lower Silurian controlled by the plate tectonics of the Middle-Upper Yangtze, south China. Marine and Petroleum Geology 118, 104357.


The Upper Ordovician Wufeng Formation and Lower Silurian Longmaxi Formation marine shale are the major shale gas exploration and development target in the Middle-Upper Yangtze region. Although three national shale gas demonstration areas have been built and several high-yield shale gas wells have been discovered in the Wufeng Formation and Longmaxi Formation, shale gas in these areas has not been fully commercialized because the enrichment degree of shale gas varies greatly in different tectonic settings. By analyzing the formation processes and distribution characteristics of the organic-rich shale, reconstructing the burial history and hydrocarbon generation history, and comparing the shale gas enrichment and preservation conditions in different tectonic settings in South China, this paper points out that (1) The craton depression and foreland basin on the cratonic margin are favorable zones for the development of organic-rich shale. Because the Yangtze plate is small, the foreland basin is greatly affected by the input of terrigenous clastic and the thickness and area of organic-rich shale in the craton basin is larger than that in the foreland basin. The organic-rich shale is mainly distributed in south Sichuan deep-water shelf and west Hubei-east Chongqing deep-water shelf, and the enrichment interval is the Dillcellograptus complexus-Cystograptus Vesicolus graptolite zone from the Wufeng Formation to the bottom of Longmaxi Formation are favorable intervals for shale gas enrichment. (2) Since the Late Jurassic, significant differential intracontinental tectonic deformation, uplift and denudation occurred in the Middle-Upper Yangtze region. Moderate compression and uplift were beneficial to the development of micro-fractures and bedding fractures in shale, resulting in good preservation conditions of shale gas reservoirs with a high-pressure coefficient. In contrast, strongly deformed areas, where faults and high-angle large fractures were developed, are not conducive to the preservation of shale gas reservoirs. (3) The craton depression of the Middle-Upper Yangtze region, where organic-rich shale

was deposited, is favorable to shale gas enrichment because it provides a good material basis, and also a relatively stable and compression-resistant tectonic environment for later tectonic deformation and uplift-derived destruction. Based on the analysis and evaluation of tectonic construction–transformation conditions under the macro-control of plate tectonics, it can well explain the existing commercial shale gas discoveries and failure cases and can guide the optimization of future exploration targets.

Heinsvig, P.J., Nielsen, L.S., Lindholst, C., 2020. Development of a method using gas chromatography–mass spectrometry for profiling of oil-based androgenic anabolic steroid products. Journal of Chromatography A 1620, 460989.


A GC–MS based analytical method was developed for the profiling of oil-based AAS products using 15 organic constituents as target compounds. A total of 219 compounds were identified in 109 seized AAS products, among them 15 target compounds were selected. The selection was based on each compound's occurrence, reproducibility, and variance between products. The 15 target compounds did not include the active steroid itself, but only compounds found in the carrier oil. The subsequent method validation included assessment of specificity, linearity, precision, robustness and sample stability. The method was finally applied for the classification of a set of 27 seizures of AAS products supplied by the police. The classification was based on the Pearson correlation coefficient using pre-treated peak area data from the 15 target compounds. A successful classification was obtained, with only a small overlap between linked and unlinked samples. A 1% false-positive rate could be obtained at a threshold of 0.625 in terms of the Pearson distance. The present study thus demonstrates that it is possible to profile and classify AAS products with regard to a common origin. As the profiling method is not specific with regards to the steroid content, it may potentially be used to profile and compare other kinds of oil-based liquids.

Heiss, A.G., Azorín, M.B., Antolín, F., Kubiak-Martens, L., Marinova, E., Arendt, E.K., Biliaderis, C.G., Kretschmer, H., Lazaridou, A., Stika, H.-P., Zarnkow, M., Baba, M., Bleicher, N., Ciałowicz, K.M., Chłodnicki, M., Matuschik, I., Schlichtherle, H., Valamoti, S.M., 2020. Mashes to Mashes, Crust to Crust. Presenting a novel microstructural marker for malting in the archaeological record. PLOS ONE 15, e0231696.

https://doi.org/10.1371/journal.pone.0231696

The detection of direct archaeological remains of alcoholic beverages and their production is still a challenge to archaeological science, as most of the markers known up to now are either not durable or diagnostic enough to be used as secure proof. The current study addresses this question by experimental work reproducing the malting processes and subsequent charring of the resulting products under laboratory conditions in order to simulate their preservation (by charring) in archaeological contexts and to explore the preservation of microstructural alterations of the cereal grains. The experimentally germinated and charred grains showed clearly degraded (thinned) aleurone cell walls. The histological alterations of the cereal grains were observed and quantified using reflected light and scanning electron microscopy and supported using morphometric and statistical analyses. In order to verify the experimental observations of histological alterations, amorphous charred objects (ACO) containing cereal remains originating from five archaeological

sites dating to the 4th millennium BCE were considered: two sites were archaeologically recognisable brewing installations from Predynastic Egypt, while the three broadly contemporary central European lakeshore settlements lack specific contexts for their cereal-based food remains. The aleurone cell wall thinning known from food technological research and observed in our own experimental material was indeed also recorded in the archaeological finds. The Egyptian materials derive from beer production with certainty, supported by ample contextual and artefactual data. The Neolithic lakeshore settlement finds currently represent the oldest traces of malting in central Europe, while a bowl-shaped bread-like object from Hornstaad–Hörnle possibly even points towards early beer production in central Europe. One major further implication of our study is that the cell wall breakdown in the grain’s aleurone layer can be used as a general marker for malting processes with relevance to a wide range of charred archaeological finds of cereal products.

Hernandez, C.A., Osma, J.F., 2020. Microbial electrochemical systems: Deriving future trends from historical perspectives and characterization strategies. Frontiers in Environmental Science 8, 44. doi: 10.3389/fenvs.2020.00044.

https://www.frontiersin.org/article/10.3389/fenvs.2020.00044

Microbial electrochemical systems (MES) can be described as a combination of technologies with the unique ability to use microorganisms to conduct the transformation between chemical and electric energy. This property holds the promise to offer an alternative to the use of fossil fuels in the generation of electricity and hazardous compounds in the production of chemical products. In this review, the fundamental aspects to describe the mechanisms involved in the MES microbe–electrode interaction are presented. Furthermore, a detailed discussion on the current classification strategies is performed including the techniques used at distinctive characterization levels. Also, the implementation of a dual-iterative bibliographic analysis was conducted. The first iteration of the bibliographic analysis was considered from a historical perspective, allowing one to identify, in a systematic manner, the main research areas related to MES. In the second iteration, the previously identified areas were surveyed in order to obtain a representative sample for the analysis and identification of trends and main research objectives of MES technologies. The MES areas that displayed the highest growth rate value are those related to “wastewater,” “wastewater treatment,” and “extracellular electron transfer,” while “system (configuration/application)” and “microbial fuel cell” reported the highest number of related documents.



The electron paramagnetic resonance (EPR) technique was used to study the behavior of the asphaltenes from the Merey crude oil (ASCM), its vacuum residue (ARVM), its fractions, and trapped compounds (A1-ASCM, A2-ASCM, TC-ASCM, A1-ARVM, A2-ARVM, and TC-ARVM). Asphaltenes were precipitated from Merey heavy crude oil and its vacuum residue. The fractionation of our petroleum asphaltenes was carried out using the para-nitrophenol (PNP) method. Two fractions named A1 and A2 and trapped compounds were obtained. The temperature dependence of the EPR spectra was used to obtain a set of temperatures related to free radical (FR) generation and recombination.

From the analysis of the EPR spectrum of the most intense signal of the vanadium, we obtain the temperature ranges of the anisotropic-to-isotropic domains, we found a nonlinear behavior of the B parameter in the temperature range studied, and we propose a functional relationship for this parameter as a function of the temperature. On the other hand, we found the temperatures for the slow-to-fast motion regime in these samples and correlated it with the mobility of the fractions.

Hill, N.C., Tay, J.W., Altus, S., Bortz, D.M., Cameron, J.C., 2020. Life cycle of a cyanobacterial carboxysome. Science Advances 6, eaba1269.

http://advances.sciencemag.org/content/6/19/eaba1269.abstract

Carboxysomes, prototypical bacterial microcompartments (BMCs) found in cyanobacteria, are large (~1 GDa) and essential protein complexes that enhance CO2 fixation. While carboxysome biogenesis has been elucidated, the activity dynamics, lifetime, and degradation of these structures have not been investigated, owing to the inability of tracking individual BMCs over time in vivo. We have developed a fluorescence-imaging platform to simultaneously measure carboxysome number, position, and activity over time in a growing cyanobacterial population, allowing individual carboxysomes to be clustered on the basis of activity and spatial dynamics. We have demonstrated both BMC degradation, characterized by abrupt activity loss followed by polar recruitment of the deactivated complex, and a subclass of ultraproductive carboxysomes. Together, our results reveal the BMC life cycle after biogenesis and describe the first method for measuring activity of single BMCs in vivo.


https://doi.org/10.1029/2019GL086725

Abstract: Reducing man made greenhouse gas emissions depends on the effective detection and ‐location of sources. We present a new method that remotely detects, locates, and quantifies gas emission rates by sequentially steering an optical beam between multiple retro reflectors. The novel‐ open path laser gas sensor uses Laser Dispersion Spectroscopy (LDS), with seven beams up to 98 ‐meters long deployed across open, flat terrain. LDS offers high precision (10–20 ppb), high dynamic range and linearity, enhanced immunity to atmospheric perturbations, with fast response to probe an area in 3 s. Simultaneous wind and concentration data were collected for four calibrated methane gas release schemes with emission rates of ~1.3 kg/hr. The resulting data were processed using a Bayesian, Markov chain Monte Carlo inverse solver to locate the sources and quantify their ‐mass emission rates and uncertainty bounds. All the sources were located to within a few meters and mass emission rates established within the associated confidence bounds.

Plain Language Summary: The Earth's atmosphere contains 600 times as much CO2 as methane (by mass), but the warming effect due to the small amount of methane is 58% of that due to all the CO2. Furthermore, methane's atmospheric lifetime is ~10 yr whereas CO2's is ~100 yr. So, reducing methane emissions not only provides much greater impact per unit mass but that reduction in atmospheric warming is realized in years not centuries. Many industrial activities produce methane emissions, but difficulties in remotely attributing and quantifying emission rates have severely

impeded effective remedial action. We present a novel method to continuously detect, locate, and quantify methane emission sources distributed across extensive areas. We demonstrate its performance in simple controlled tests using a novel optical beam gas sensor to measure path‐averaged gas concentrations. The data are analyzed using advanced statistical methods to locate and quantify the emission rates of the sources.

Hogendoorn, C., Pol, A., Picone, N., Cremers, G., van Alen, T.A., Gagliano, A.L., Jetten, M.S.M., D’Alessandro, W., Quatrini, P., Op den Camp, H.J.M., 2020. Hydrogen and carbon monoxide-utilizing Kyrpidia spormannii species from Pantelleria Island, Italy. Frontiers in Microbiology 11, 951. doi: 10.3389/fmicb.2020.00951.


Volcanic and geothermal areas are hot and often acidic environments that emit geothermal gasses, including H2, CO and CO2. Geothermal gasses mix with air, creating conditions where thermoacidophilic aerobic H2- and CO-oxidizing microorganisms could thrive. Here, we describe the isolation of two Kyrpidia spormannii strains, which can grow autotrophically by oxidizing H2 and CO with oxygen. These strains, FAVT5 and COOX1, were isolated from the geothermal soils of the Favara Grande on Pantelleria Island, Italy. Extended physiology studies were performed with K. spormannii FAVT5, and showed that this strain grows optimally at 55°C and pH 5.0. The highest growth rate is obtained using H2 as energy source (μmax 0.19 ± 0.02 h–1, doubling time 3.6 h). K. spormannii FAVT5 can additionally grow on a variety of organic substrates, including some alcohols, volatile fatty acids and amino acids. The genome of each strain encodes for two O2-tolerant hydrogenases belonging to [NiFe] group 2a hydrogenases and transcriptome studies using K. spormannii FAVT5 showed that both hydrogenases are expressed under H2 limiting conditions. So far no Firmicutes except K. spormannii FAVT5 have been reported to exhibit a high affinity for H2, with a Ks of 327 ± 24 nM. The genomes of each strain encode for one putative CO dehydrogenase, belonging to Form II aerobic CO dehydrogenases. The genomic potential and physiological properties of these Kyrpidia strains seem to be quite well adapted to thrive in the harsh environmental volcanic conditions.

Hong, W.-L., Latour, P., Sauer, S., Sen, A., Gilhooly, W.P., Lepland, A., Fouskas, F., 2020. Iron cycling in Arctic methane seeps. Geo-Marine Letters 40, 391-401.

https://doi.org/10.1007/s00367-020-00649-5

Anoxic marine sediments contribute a significant amount of dissolved iron (Fe2+) to the ocean which is crucial for the global carbon cycle. Here, we investigate iron cycling in four Arctic cold seeps where sediments are anoxic and sulfidic due to the high rates of methane-fueled sulfate reduction. We estimated Fe2+ diffusive fluxes towards the oxic sediment layer to be in the range of 0.8 to 138.7 μmole/m2/day and Fe2+ fluxes across the sediment-water interface to be in the range of 0.3 to 102.2 μmole/m2/day. Such variable fluxes cannot be explained by Fe2+ production from organic matter–coupled dissimilatory reduction alone. We propose that the reduction of dissolved and complexed Fe3+ as well as the rapid formation of iron sulfide minerals are the most important reactions regulating the fluxes of Fe2+ in these cold seeps. By comparing seafloor visual observations with subsurface pore fluid composition, we demonstrate how the joint cycling of iron and sulfur determines the distribution of chemosynthesis-based biota.

Hopple, A.M., Wilson, R.M., Kolton, M., Zalman, C.A., Chanton, J.P., Kostka, J., Hanson, P.J., Keller, J.K., Bridgham, S.D., 2020. Massive peatland carbon banks vulnerable to rising temperatures. Nature Communications 11, 2373.

https://doi.org/10.1038/s41467-020-16311-8

Peatlands contain one-third of the world’s soil carbon (C). If destabilized, decomposition of this vast C bank could accelerate climate warming; however, the likelihood of this outcome remains unknown. Here, we examine peatland C stability through five years of whole-ecosystem warming and two years of elevated atmospheric carbon dioxide concentrations (eCO2). Warming exponentially increased methane (CH4) emissions and enhanced CH4 production rates throughout the entire soil profile; although surface CH4 production rates remain much greater than those at depth. Additionally, older deeper C sources played a larger role in decomposition following prolonged warming. Most troubling, decreases in CO2:CH4 ratios in gas production, porewater concentrations, and emissions, indicate that the peatland is becoming more methanogenic with warming. We observed limited evidence of eCO2 effects. Our results suggest that ecosystem responses are largely driven by surface peat, but that the vast C bank at depth in peatlands is responsive to prolonged warming.

Hou, L., Elsworth, D., Geng, X., 2020. Swelling and embedment induced by sub- and super-critical-CO2 on the permeability of propped fractures in shale. International Journal of Coal Geology 225, 103496.


Swelling and embedment exert significant influence on the evolution of permeability in propped fractures, potentially consuming significant proportions of the original gain in permeability. We measure the evolution of permeability in propped fractures of shale to both adsorbing CO2 and non-adsorbing He – accommodating the impacts of aperture change due to proppant pack compaction and both reversible and irreversible modes of embedment. A linear relation between pressure and log-permeability is obtained for He, representing the impact of effective stresses in proppant pack compaction, alone. Permeability change with pressure is always concave upwards and U-shaped for gaseous subcritical CO2 and W-shaped for supercritical CO2. One exception is for liquid CO2 at high injection pressure where effective stress effects and swelling contribute equally to the change in permeability and result in a linear curve with the lowest permeability. Approximately ~50–70% of the permeability recovers from the recovery of swelling after the desorption of CO2. The magnitude of swelling is recovered from measurements of permeability change and ranges from 0.005 to 0.06 mm, which contributes ~9–56% of the total swelling and induced embedment as evaluated from the adsorbed mass. Swelling also increases embedment by a factor of ~1.84–1.93 before and after the injection of CO2. A new calibration equation representing swelling and induced embedment is generated accommodating Langmuir isothermal sorption and verified against experiments on rocks both admitting and excluding swelling and embedment and for various sorbing and non-sorbing gases. Stability and accuracy of the predictions demonstrate the universality of the approach that may be applied to both enhanced gas recovery and CO2 sequestration.

Hu, A., Niu, C., Wang, D., Li, H., Ye, T., Xu, P., 2020. The characteristics and formation mechanism of condensate oil and gas in Bozhong19-6 structure, Bozhong sag, Bohai Bay Basin Acta Petrolei Sinica 41, 403-411 http://www.syxb-cps.com.cn/EN/abstract/abstract5877.shtml

Based on the analysis results of condensate oil and gas components, biomarkers, stable carbon isotopes and fluid inclusions, compressively using mulitple research methods of petroleum geochemistry, this paper determines the characteristics and genisis of condensate oil and gas and explores the oil-gas formation mechanism in Bozhong19-6 structure, southwestern Bozhong sag, Bohai Bay Basin. The results show that the condensate oil has physical properties of low density, low viscosity, low colloid and asphaltene, high wax and high freezing point. In the condensate oil, n-alkanes are mainly composed of medium and high carbon components, and light hydrocarbon components are dominated by the n-octane, n-heptane and methylcyclohexane with the same contents. The condensate oil is the product of mature source rocks in Member 3 of Shahejie Formation. The natural gas is mainly composed of hydrocarbon gas with low content of non-hydrocarbon gas and derived from the cracking of humic-type source rocks in Member 3 of Shahejie Formation. The Bozhong19-6 structure has experienced multi-stage continuous charging of heavy oil, light oil, condensate oil or gas, and natural gas since 12Ma. The phase-controlled miscibility is the main formation mechanism of condensate gas in Bozhong19-6 structure. In the natural gas fluid containing crude oil, the early crude oil dissolves in the later charging natural gas with the increase of underground temperature and pressure, thus forming the present condensate gas reservoir.

Hu, D., Li, M., Zhang, X., Turchyn, A.V., Gong, Y., Shen, Y., 2020. Large mass-independent sulphur isotope anomalies link stratospheric volcanism to the Late Ordovician mass extinction. Nature Communications 11, 2297.

https://doi.org/10.1038/s41467-020-16228-2

Volcanic eruptions are thought to be a key driver of rapid climate perturbations over geological time, such as global cooling, global warming, and changes in ocean chemistry. However, identification of stratospheric volcanic eruptions in the geological record and their causal link to the mass extinction events during the past 540 million years remains challenging. Here we report unexpected, large mass-independent sulphur isotopic compositions of pyrite with Δ33S of up to 0.91‰ in Late Ordovician sedimentary rocks from South China. The magnitude of the Δ33S is similar to that discovered in ice core sulphate originating from stratospheric volcanism. The coincidence between the large Δ33S and the first pulse of the Late Ordovician mass extinction about 445 million years ago suggests that stratospheric volcanic eruptions may have contributed to synergetic environmental deteriorations such as prolonged climatic perturbations and oceanic anoxia, related to the mass extinction.

Hu, S.-y., Xiao, C.-L., Liang, X.-J., Cao, Y.-q., 2020. Influence of water-rock interaction on the pH and heavy metals content of groundwater during in-situ oil shale exploitation. Oil Shale 37, 104-118.

http://www.kirj.ee/33424/?tpl=1061&c_tpl=1064

In this paper, step-by-step groundwater-rock interaction experiments were performed to investigate the migration of heavy metals (Pb, Cr, Zn) into the water and the pH change of oil shale and oil shale ash aqueous solutions (hereinafter OS solution and OSA solution, respectively) during the in-situ

production of oil shale. For geochemical calculations the PHREEQC software was used to simulate pH variation in the aqueous solutions at different temperatures and CO2 partial pressures (PCO2). The pH of most solutions was between 6.95 and 7.49 and changed significantly with increasing reaction time. The simulated data were closest to the experimental results at PCO2 = 10–2. A clear effect of reaction temperature and pH on the Pb content in the aqueous solutions was observed. The Pb content in the OSA solution was 0.36–0.47 µg/L, being higher than that in the OS solution (0.13–0.26 µg/L). The Cr content in OS and OSA solutions was from 0.55 to 0.70 µg/L. The Zn content in the OS solution was 1.17–3.61 µg/L, being significantly influenced by reaction temperature.

Hu, Y., Teng, F.-Z., Ionov, D.A., 2020. Magnesium isotopic composition of metasomatized upper sub-arc mantle and its implications to Mg cycling in subduction zones. Geochimica et Cosmochimica Acta 278, 219-234.


Dehydration of subducting oceanic crust and underlying serpentinized mantle is potentially the most important source of fluids for element cycling between surface-processed materials and the interior of the Earth. Magnesium (Mg) isotopes -have been proposed as a promising tracer of dehydration of serpentinites because of their high Mg contents and distinctive Mg isotopic signatures relative to the mantle, which is difficult to identify using other isotopes. To constrain the primary controls on Mg isotope cycling in subduction zones, here we analyze a suite of well-characterized sub-arc mantle xenoliths from the Avacha volcano in southern Kamchatka arc, Russia. They are comparable in modal and/or chemical composition to serpentinized fore-arc harzburgites and sub-arc harzburgite xenoliths from the western Pacific. Despite evidence for ubiquitous slab-related fluid metasomatism, the 23 spinel harzburgite xenoliths and four pyroxenite metasomatic veins display mantle-like δ26Mg values from −0.30 to −0.21‰. Mineral separates have similar δ26Mg values, with an average of −0.26 ± 0.04‰ (2SD, n = 17) for olivine, −0.23 ± 0.04‰ (2SD, n = 17) for orthopyroxene, and −0.24 ± 0.10‰ (2SD, n = 5) for late-stage interstitial clinopyroxene. The lack of a clear slab-derived δ26Mg signature in the Avacha sub-arc peridotites is probably due to their high MgO contents and low fluid/rock mass ratios during flux melting and metasomatism. We also compare published δ26Mg data for four volcanic arcs distributed worldwide. This inter-arc comparison reveals that the thermal structure of a subduction zone appears to exert a strong control on the efficiency of Mg isotope cycling from the downgoing slab to the mantle wedge and subsequently to the arc magmas; those arcs that permit large-scale dehydration of Mg-rich serpentinized slab mantle, coupled with available channelized fluid pathways, are more likely to produce isotopically diverse arc magmas.

Huang, J., Guo, S., Jin, Q.-Z., Huang, F., 2020. Iron and magnesium isotopic compositions of subduction-zone fluids and implications for arc volcanism. Geochimica et Cosmochimica Acta 278, 376-391.


High-pressure (HP) metamorphic veins in eclogites provide insights into the composition and evolution of fluids in subduction zones. We here present the first Fe-Mg isotope data for three types of HP veins, eclogites and their mineral separates from the Dabie Orogen to constrain the Fe-Mg isotopic compositions of subduction-zone fluids and the Fe-Mg isotope behaviors during fluid-rock interaction and fluid evolution. The HP veins include omphacite-epidote (Omp-Ep), epidote-quartz (Ep-Qtz), and kyanite-epidote-quartz (Ky-Ep-Qtz) veins. The Omp-Ep veins first crystallized from

eclogite-derived, solute-rich vein-forming fluids with the Ep-Qtz and Ky-Ep-Qtz veins successively crystallizing from the residual fluids after the formation of the Omp-Ep veins. The early Omp-Ep veins have much heavier Fe-Mg isotopic compositions compared to the host eclogites, indicating Fe-Mg isotope fractionation during fluid-rock interaction due to preferential dissolution of isotopically heavy Omp and Ep from the eclogites into the vein-forming fluids. The δ56Fe and δ26Mg values of the Omp-Ep, Ep-Qtz, and Ky-Ep-Qtz veins gradually decrease and positively correlate with the Eu/Eu* values of whole rock and epidote. This indicates that Fe-Mg isotope fractionation during fluid evolution results from continuous crystallization of isotopically heavy Omp and Ep from the vein-forming fluids. Our results thus demonstrate that Fe-Mg isotopes can significantly fractionate during the dissolution-precipitation processes of minerals in subduction zones.

The high δ56Fe (0.04–0.21‰) and δ26Mg (−0.08 to 0.15‰) values of fluid-related HP veins within mafic eclogites indicate that fluids derived from subducted altered oceanic crust (AOC) probably have Fe-Mg isotopic compositions similar to or higher than those of mid-ocean ridge basalts (MORBs). Thus, contribution from AOC-derived fluids is unlikely to explain the light Fe and heavy Mg isotopic compositions of arc lavas. We propose that the light Fe and heavy Mg isotopic compositions of arc lavas may result from a combination of prior melt depletion and addition of serpentinite-derived 54Fe-26Mg-rich fluids into the overlying mantle wedge.

Huang, P., Huang, C.-Y., Lin, T.-C., Lin, L.-E., Yang, E., Lee, C., Hsu, C.-C., Chou, P.-T., 2020. Toward the rational design of universal dual polarity matrix for MALDI mass spectrometry. Analytical Chemistry 92, 7139-7145.


A series of novel anthranilic acid derivatives I–IV, of which COOH-NH2 (I) and COOH-NHMe (IV) are endowed with acid and base bifunctionality, were designed and synthesized for matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry applications in dual polarity molecular imaging of biological samples, particularly for lipids. The heat of protonation, deprotonation, and proton transfer reaction as well as the capability of analyzing biomolecules in both positive and negative ion modes for I–IV were systematically investigated under standard 355 nm laser excitation. The results indicate correlation between dual polarity and acid–base property. Further, COOH-NHMe (IV) showed a unique performance and was successfully applied as the matrix for MALDI-TOF mass spectrometry imaging (MSI) for studying the mouse brain. Our results demonstrate the superiority of COOH-NHMe (IV) in detecting more lipid and protein species compared to commercially available matrices. Moreover, MALDI-TOF MSI results were obtained for lipid distributions, making COOH-NHMe (IV) a potential next generation universal matrix.

Huang, T.-Y., Teng, F.-Z., Rudnick, R.L., Chen, X.-Y., Hu, Y., Liu, Y.-S., Wu, F.-Y., 2020. Heterogeneous potassium isotopic composition of the upper continental crust. Geochimica et Cosmochimica Acta 278, 122-136.


Assessing the K isotopic composition of the upper continental crust is important for understanding the processes by which the crust is generated and modified, and constraining the K isotopic budget of the silicate Earth. High-precision K isotopic data are reported for 70 well-characterized individual

and composite samples from the upper continental crust, including diorite, granodiorite, granite, loess, shale, graywacke, pelite, and tillite, to constrain its K isotopic composition. δ41K varies significantly in eight I-type and two S-type granites from Australia (−0.57 to −0.40‰), nine A-type granites (−0.53 to −0.38‰), and three granitoid composites including diorite, granodiorite, and granite (−0.50 to −0.37‰) from China, mainly reflecting source heterogeneity. The 22 post-Archean Australian shales (PAAS) (δ41K = −0.68 to −0.12‰) and the 12 sedimentary composites including graywacke, pelite, and tillite from China (δ41K = −0.57 to −0.23‰) have heterogeneous K isotopic compositions while the 12 loess samples from around the world display more limited K isotopic variation (δ41K = −0.47 to −0.35‰). δ41K values display a smaller dispersion in loess compared to shales, which have comparatively more intense weathering and higher chemical index of alteration (CIA). δ41K correlates with Fe2O3/Al2O3 and Fe2O3/K2O in shales and Al2O3/SiO2, K2O/Al2O3, and δ7Li in loess, suggesting that K isotopes are fractionated during chemical weathering. Overall, the upper continental crust has a heterogeneous K isotopic composition, ranging from −0.68 to −0.12‰ with an average δ41K of −0.44 ± 0.05‰ (2SD, n = 88), which is indistinguishable from the mantle.

Huang, W., Ertekin, E., Wang, T., Cruz, L., Dailey, M., DiRuggiero, J., Kisailus, D., 2020. Mechanism of water extraction from gypsum rock by desert colonizing microorganisms. Proceedings of the National Academy of Sciences 117, 10681-10687.


Significance: This research provides an in-depth analysis of how microorganisms are able to survive in the world’s driest non-polar place, the Atacama Desert, Chile. We show that these organisms extract water from gypsum rocks in this desert, enabling these colonizing microorganisms to sustain life in this extreme environment. We believe the results in this work could not only shed light on how microorganisms can obtain water under severe xeric conditions, but also provide insights into potential life in even more extreme environments, such as Mars, as well as offer strategies for advanced water storage methods.

Abstract: Microorganisms, in the most hyperarid deserts around the world, inhabit the inside of rocks as a survival strategy. Water is essential for life, and the ability of a rock substrate to retain water is essential for its habitability. Here we report the mechanism by which gypsum rocks from the Atacama Desert, Chile, provide water for its colonizing microorganisms. We show that the microorganisms can extract water of crystallization (i.e., structurally ordered) from the rock, inducing a phase transformation from gypsum (CaSO4·2H2O) to anhydrite (CaSO4). To investigate and validate the water extraction and phase transformation mechanisms found in the natural geological environment, we cultivated a cyanobacterium isolate on gypsum rock samples under controlled conditions. We found that the cyanobacteria attached onto high surface energy crystal planes ({011}) of gypsum samples generate a thin biofilm that induced mineral dissolution accompanied by water extraction. This process led to a phase transformation to an anhydrous calcium sulfate, anhydrite, which was formed via reprecipitation and subsequent attachment and alignment of nanocrystals. Results in this work not only shed light on how microorganisms can obtain water under severe xeric conditions but also provide insights into potential life in even more extreme environments, such as Mars, as well as offering strategies for advanced water storage methods.



CO2 injection has been accepted as a suitable method for enhancing shale hydrocarbon recovery as well as achieving CO2 storage in shale reservoirs. In this study, flue gas is proposed as a better injection gas for shale resource recovery. The objective of this work is conducted to investigate how introduced CO2 and flue gas affect the adsorption behavior of CH4 and C2H6, which are two main components in shale gas, on shale, which is critical for understanding the fundamental mechanism of shale gas recovery. In this work, the adsorption isotherms are first measured to evaluate the relative adsorption capacity of CO2, flue gas, CH4, and C2H6 on typical shale samples. The low-field nuclear magnetic resonance technique is consequently applied to study the influence of injected CO2

and flue gas on the adsorption behavior of CH4 and C2H6 at the reservoir pressure and temperature conditions. Test results show that flue gas presents the highest adsorption capacity on shale, which is followed by C2H6, CO2, and CH4, respectively. On the basis of the measured T2 signals, CH4 and C2H6 exist in shale within the two patterns, i.e., the adsorbed pattern in pores and the free-state pattern at the pore center. After injection of CO2 and flue gas, the amount of adsorbed CH4 is reduced, accompanying with the increase of the quantity of free gas state that appeared at the pore center. In comparison to CO2, flue gas can further replace adsorbed CH4 and C2H6 from the shale surface, suggesting more feasibility of flue gas for enhancing CH4 and C2H6 recovery. This study may inspire new strategies that can be applied for shale reservoir development; more importantly, it may provide a new way for the usage of flue gas for energy supply while reducing the possibility for environmental pollution.

Hublin, J.-J., Sirakov, N., Aldeias, V., Bailey, S., Bard, E., Delvigne, V., Endarova, E., Fagault, Y., Fewlass, H., Hajdinjak, M., Kromer, B., Krumov, I., Marreiros, J., Martisius, N.L., Paskulin, L., Sinet-Mathiot, V., Meyer, M., Pääbo, S., Popov, V., Rezek, Z., Sirakova, S., Skinner, M.M., Smith, G.M., Spasov, R., Talamo, S., Tuna, T., Wacker, L., Welker, F., Wilcke, A., Zahariev, N., McPherron, S.P., Tsanova, T., 2020. Initial Upper Palaeolithic Homo sapiens from Bacho Kiro Cave, Bulgaria. Nature 581, 299-302.

https://doi.org/10.1038/s41586-020-2259-z

The Middle to Upper Palaeolithic transition in Europe witnessed the replacement and partial absorption of local Neanderthal populations by Homo sapiens populations of African origin. However, this process probably varied across regions and its details remain largely unknown. In particular, the duration of chronological overlap between the two groups is much debated, as are the implications of this overlap for the nature of the biological and cultural interactions between Neanderthals and H. sapiens. Here we report the discovery and direct dating of human remains found in association with Initial Upper Palaeolithic artefacts, from excavations at Bacho Kiro Cave (Bulgaria). Morphological analysis of a tooth and mitochondrial DNA from several hominin bone fragments, identified through proteomic screening, assign these finds to H. sapiens and link the expansion of Initial Upper Palaeolithic technologies with the spread of H. sapiens into the mid-latitudes of Eurasia before 45 thousand years ago. The excavations yielded a wealth of bone artefacts, including pendants manufactured from cave bear teeth that are reminiscent of those later produced by the last Neanderthals of western Europe. These finds are consistent with models based on the arrival of multiple waves of H. sapiens into Europe coming into contact with declining Neanderthal populations.

Hutchinson, D.K., Coxall, H.K., Lunt, D.J., Steinthorsdottir, M., de Boer, A.M., Baatsen, M., von der Heydt, A., Huber, M., Kennedy-Asser, A.T., Kunzmann, L., Ladant, J.-B., Lear, C.H., Moraweck, K., Pearson, P.N., Piga, E., Pound, M.J., Salzmann, U., Scher, H.D., Sijp, W.P., Śliwińska, K.K., Wilson, P.A., Zhang, Z., 2020. The Eocene-Oligocene transition: a review of marine and terrestrial proxy data, models and model-data comparisons. Climate of the Past Discussions 2020, 1-71.


The Eocene-Oligocene transition (EOT) from a largely ice-free greenhouse world to an icehouse climate with the first major glaciation of Antarctica was a phase of major climate and environmental change occurring ~34 million years ago (Ma) and lasting ~500 kyr. The change is marked by a global shift in deep sea δ18O representing a combination of deep-ocean cooling and global ice sheet growth. At the same time, multiple independent proxies for sea surface temperature indicate a surface ocean cooling, and major changes in global fauna and flora record a shift toward more cold-climate adapted species. The major explanations of this transition that have been suggested are a decline in atmospheric CO2, and changes to ocean gateways, while orbital forcing likely influenced the precise timing of the glaciation. This work reviews and synthesises proxy evidence of paleogeography, temperature, ice sheets, ocean circulation, and CO2 change from the marine and terrestrial realms. Furthermore, we quantitatively compare proxy records of change to an ensemble of model simulations of temperature change across the EOT. The model simulations compare three forcing mechanisms across the EOT: CO2 decrease, paleogeographic changes, and ice sheet growth. We find that CO2 forcing provides by far the best explanation of the combined proxy evidence, and based on our model ensemble, we estimate that a CO2 decrease of about 1.6× across the EOT (e.g. from 910 to 560 ppmv) achieves the best fit to the temperature change recorded in the proxies. This model-derived CO2 decrease is consistent with proxy estimates of CO2 decline at the EOT.

Ibrahim, N., Maganuco, S., Dal Sasso, C., Fabbri, M., Auditore, M., Bindellini, G., Martill, D.M., Zouhri, S., Mattarelli, D.A., Unwin, D.M., Wiemann, J., Bonadonna, D., Amane, A., Jakubczak, J., Joger, U., Lauder, G.V., Pierce, S.E., 2020. Tail-propelled aquatic locomotion in a theropod dinosaur. Nature 581, 67-70.

https://doi.org/10.1038/s41586-020-2190-3

In recent decades, intensive research on non-avian dinosaurs has strongly suggested that these animals were restricted to terrestrial environments. Historical proposals that some groups, such as sauropods and hadrosaurs, lived in aquatic environments were abandoned decades ago. It has recently been argued that at least some of the spinosaurids—an unusual group of large-bodied theropods of the Cretaceous era—were semi-aquatic, but this idea has been challenged on anatomical, biomechanical and taphonomic grounds, and remains controversial. Here we present unambiguous evidence for an aquatic propulsive structure in a dinosaur, the giant theropod Spinosaurus aegyptiacus. This dinosaur has a tail with an unexpected and unique shape that consists of extremely tall neural spines and elongate chevrons, which forms a large, flexible fin-like organ capable of extensive lateral excursion. Using a robotic flapping apparatus to measure undulatory forces in physical models of different tail shapes, we show that the tail shape of Spinosaurus produces greater thrust and efficiency in water than the tail shapes of terrestrial dinosaurs and that these measures of performance are more comparable to those of extant aquatic vertebrates that use vertically expanded tails to generate forward propulsion while swimming. These results are consistent with the suite of adaptations for an aquatic lifestyle and piscivorous diet that have

previously been documented for Spinosaurus. Although developed to a lesser degree, aquatic adaptations are also found in other members of the spinosaurid clade, which had a near-global distribution and a stratigraphic range of more than 50 million years, pointing to a substantial invasion of aquatic environments by dinosaurs.

Ingraffea, A.R., Wawrzynek, P.A., Santoro, R., Wells, M., 2020. Reported methane emissions from active oil and gas wells in Pennsylvania, 2014–2018. Environmental Science & Technology 54, 5783-5789.


Oil/gas well integrity failures are a common but poorly constrained source of methane emissions to the atmosphere. As of 2014, Pennsylvania requires gas and oil well operators to report gas losses, both fugitive and process, from all active and unplugged abandoned gas and oil wells. We analyze 589,175 operator reports and find that lower-bound reported annual methane emissions averaged 22.1 Gg (−16.9, +19.5) between 2014 and 2018 from 62,483 wells, an average of only 47% of the statewide well inventory for those years. Extrapolating to the 2019 oil and gas well inventory yields well average emissions of 55.6 Gg CH4. These emissions are not currently included in the state’s oil and gas emission inventory. We also assess compliance in reporting among operators and note anomalies in reporting and apparent workarounds to reduce reported emissions. Suggestions for improving the accuracy and reliability in reporting and reducing emissions are offered.

Jagadisan, A., Heidari, Z., 2020. Impact of geochemical properties on wettability of kerogen and organic-rich mudrocks. SPE Reservoir Evaluation & Engineering 23, 758-771.

https://doi.org/10.2118/199356-PA

The wettability of organic-rich mudrocks has a significant effect on multiphase-fluid flow and hydrocarbon recovery. This important rock property has still not been well-quantified in organic-rich mudrocks. Kerogen constitutes a significant fraction of mudrocks and can considerably affect their wettability. Recent publications suggested that kerogen wettability is affected by the thermal maturity of rocks and can influence the wettability of mudrocks. In this paper, we experimentally quantify the influence of geochemistry and thermal maturity of kerogen on the wettability of organic-rich mudrocks, and the influence of thermal maturity and chemical bonding on the wettability of kerogen. The wettability of organic-rich-mudrock samples at different experimental thermal-maturity levels was measured using the sessile-drop method, and also qualitatively estimated using a Flotation test and spontaneous-imbibition experiments on crushed-organic-rich-mudrock samples. The concentration of minerals in the mudrock samples was quantified using X-ray diffraction (XRD) at different experimental maturity levels. We then isolated kerogen samples from an organic-rich-mudrock formation and experimentally matured them. The variation in the chemical-bonding state of carbon present in kerogen at different levels of natural and experimental thermal maturity was determined using X-ray-photoelectron-spectroscopy (XPS) measurements. Finally, the wettability of pure-kerogen samples at different thermal-maturity levels was quantified using the sessile-drop method and the effect of aromatic carbon content on the wettability of the kerogen samples was determined.

The sessile-drop test performed on the organic-rich-mudrock-rock samples showed a 5° increase in contact angle with a 96% decrease in the hydrogen index (HI). The Flotation test showed that the oil-

wet fraction of the mudrock samples increases by 81% as the heat-treatment temperature increases from nonheated to 650°C. The water-imbibition measurements in crushed-mudrock samples suggest that the volume of water imbibed was higher by 22 cm3 at lower thermal maturity [i.e., HI of 328 mg hydrocarbon/g organic carbon (mg HC/g OC)] compared with mudrock samples at higher thermal maturity (i.e., HI of 10 mg HC/g OC). Results indicate that the thermal maturity of kerogen could potentially affect the wettability of mudrocks and that the mudrock has higher water wettability at lower thermal maturity of kerogen. The experimental results also demonstrated that the wettability of kerogen changes from waterwet to hydrocarbon-wet with an increase in the aromatic carbon content. The contact angle of the water droplet on the kerogen samples from Formation A increased by 78° when the aromatic carbon concentration increased by 19%. The results contribute to a better understanding of the effects of kerogen wettability and thermal maturity on the wettability of organic-rich mudrocks. The outcomes can also have potential future contributions in understanding flow mechanisms in organic-rich mudrocks as well as in developing reliable rockphysics models for the interpretation of borehole geophysical measurements [e.g., electromagnetic and nuclear-magnetic-resonance (NMR) measurements] in organic-rich mudrocks.

Jaiswal, S., Shukla, P., 2020. Alternative strategies for microbial remediation of pollutants via synthetic biology. Frontiers in Microbiology 11, 808. doi: 10.3389/fmicb.2020.00808.


Continuous contamination of the environment with xenobiotics and related recalcitrant compounds has emerged as a serious pollution threat. Bioremediation is the key to eliminating persistent contaminants from the environment. Traditional bioremediation processes show limitations, therefore it is necessary to discover new bioremediation technologies for better results. In this review we provide an outlook of alternative strategies for bioremediation via synthetic biology, including exploring the prerequisites for analysis of research data for developing synthetic biological models of microbial bioremediation. Moreover, cell coordination in synthetic microbial community, cell signaling, and quorum sensing as engineered for enhanced bioremediation strategies are described, along with promising gene editing tools for obtaining the host with target gene sequences responsible for the degradation of recalcitrant compounds. The synthetic genetic circuit and two-component regulatory system (TCRS)-based microbial biosensors for detection and bioremediation are also briefly explained. These developments are expected to increase the efficiency of bioremediation strategies for best results.

Jaramillo, R., Dorman, F.L., 2020. Thermodynamic modeling of comprehensive two dimensional gas chromatography isovolatility curves for second dimension retention indices based analyte identification. Journal of Chromatography A 1622, 461111.


A method to thermodynamically model the alkane isovolatility curves of a comprehensive two dimensional gas chromatography (GC × GC) separation is presented. This method omits all instrument modifications, additional chromatogram collection, or method alterations which typical isovolatility curve generation requires. Provided that the thermodynamic indices of reference alkanes are available, chromatographers only need to specify the GC × GC method parameters of their separation to output the isovolatility curves. The curves can then be used alongside reference

retention indices to generate two dimensional retention times for each analyte. Agreement between the modeled and experimental retention times provides a secondary mechanism for compound identification, supporting the results of a mass spectral search. The technique was used to model the retention times of a GC × GC separation of aromatic hydrocarbons, achieving an average first dimension retention time modeling error of 11 s and an average second dimension retention time modeling error of 0.09 s. Retention indices modeled retention times provide a simpler analyte identification procedure compared to conventional two dimensional retention indices matching.


https://doi.org/10.1111/pala.12456

Konservat Lagerstätten are seen as snapshots of past biodiversity for a given location and time. ‐However, processes leading to the exceptional morphological preservation of fossils in these deposits remain incompletely understood. This results in a deficient assessment of taphonomic biases and limits the robustness/relevance of palaeobiological reconstructions. Here, we report the mineralogical characterization of crustacean fossils preserved within carbonate rich concretions ‐from the Jurassic Konservat Lagerstätte of La Voulte sur Rhône (Ardèche, France). The combination ‐ ‐ ‐of SEM EDS , TEM , synchrotron based XRF , XRD and XANES allows the mineralogical phases ‐ ‐composing these fossils (i.e. fluorapatite, Fe sulfides (pyrite, pyrrhotite) and Mg calcite) and the ‐ ‐surrounding matrix (i.e. Mg calcite, clays and detrital silicates) to be identified. Fluorapatite and ‐pyrite (and pyrrhotite) precipitated during decay under anoxic conditions, replacing delicate organic structures and preserving anatomical details. These mineral structures were subsequently consolidated by a Mg calcite cement. Of note, histologically similar tissues were replaced by the ‐same mineral phases, confirming that fossilization (in La Voulte) occurred rapidly enough to be influenced by tissue composition. Altogether, the present study shows that exceptional preservation requires fast biodegradation, thereby confirming recent experimental evidence.

Ji, W.-Q., Wu, F.-Y., Liu, X.-C., Liu, Z.-C., Zhang, C., Liu, T., Wang, J.-G., Paterson, S.R., 2020. Pervasive Miocene melting of thickened crust from the Lhasa terrane to Himalaya, southern Tibet and its constraint on generation of Himalayan leucogranite. Geochimica et Cosmochimica Acta 278, 137-156.


The Oligocene to Miocene period is one of the most important stages during the formation and evolution of the Tibetan Plateau which generated the tectonic framework similar to the present. The rise of southern Tibet at this time was accompanied by widespread and intense tectonomagmatic activities. The Himalayan region was dominated by leucogranites considered as pure metasediments derived S-type granites, while the Lhasa terrane developed coeval thickened crust derived high Sr/Y calcalkaline rocks and metasomatized mantle derived ultrapotassic rocks. It is puzzling why the adjacent amalgamated regions show contrasting magmatic and dynamic process.

This contribution presents a systematic study of newly found various dikes, including minette, aplite, granodiorite porphyry and granite porphyry, which are widespread from the southern Lhasa terrane, across the Yarlung Tsangpo suture zone (YTSZ) and into the Tethyan Himalaya. These dikes yield 16–11 Ma U-Th-Pb ages from zircon, titanite and monazite. The aplite and granodiorite porphyry dikes (high Sr/Y calcalkaline) and minette dikes (ultrapotassic) previal from the Lhasa terrane to the YTSZ. They are identical to the coeval high Sr/Y and/or ultrapotassic rocks from the Lhasa terrane, indicating a similar melting process of thickened lower crust and metasomatized lithospheric mantle. To the south of YTSZ, the middle Miocene granite porphyry in the Tethyan Himalaya exhibit high Sr/Y ratios (50–138), relatively low initial 87Sr/86Sr ratio (0.7064–0.7098), high εNd(t) value (−8.31 to −1.91) and positive εHf(t) value (+1.55 to +4.33), in contrast to the high 87Sr/86Sr and low εNd(t) Himalayan leucogranites. They were likely generated by partial melting of thickened lower crust dominated by amphibolite with significant contributions from juvenile magma. The two-mica granite of Bendui pluton from the Tethyan Himalaya is similar to the granite porphyry in element composition, while the highly evolved muscovite granite there resembles the Himalayan leucogranite. Together, the granite porphyry, Bendui two-mica granite and leucogranite from the Tethyan Himalaya show a transition trend in elemental and Sr-Nd isotopic compositions, implying that the high Sr/Y granite porphyry dikes may represent the more primitive magma of Himalayan leucogranites. In this case, the Himalayan leucogranites, at least in part, represent highly evolved I-type granites with extensive assimilation of ancient crustal materials instead of pure metasediment-derived partial melts. Therefore, we suggest that the thickened lower crust in southern Tibet underwent pervasive partial melting during Oligocene to Miocene as a result of the removal of subducting Indian plate.

Jia, H., Liu, J., Zhu, K., Gao, P., Lichtfouse, E., 2020. High contribution of hydrocarbon transformation during the removal of polycyclic aromatic hydrocarbons from soils, humin and clay by thermal treatment at 100–200 °C. Environmental Chemistry Letters 18, 923-930.

https://doi.org/10.1007/s10311-020-00972-4

Polycyclic aromatic hydrocarbons (PAHs) are major pollutants in air, soils and sediments. PAH-polluted soils can be cleaned rapidly by thermal treatment. PAH volatilization is considered as the main process explaining PAH removal at low temperature, yet other processes may occur. Particularly, we hypothesize that thermal transformation can also explain PAH removal, where transformation refers to both degradation and formation of bound PAHs. We thus studied the removal of spiked benzo[a]pyrene at 0.5 mg/g in bauxite soil, fluvo-aquic soil, chernozem soil, montmorillonite, humin, and quartz sand as control, from 100 to 200 °C. We measured concentrations of benzo[a]pyrene in the volatilized fraction and solid residues by high-performance liquid chromatography. We identified transformation products by gas chromatography–mass spectrometry. Results show that the contribution of thermal transformation to the removal of benzo[a]pyrene increased from 24.7 to 58.4 wt% for bauxite soil, from 4.4 to 38.2 wt% for fluvo-aquic soil, and from 11.5 to 35.9 wt% for chernozem soil, with temperature increasing from 100 to 200 °C. Transformation such as oxidation occurred in all samples except in benzo[a]pyrene-spiked quartz sands. Transformation of benzo[a]pyrene was thus partly explained by the presence of clay minerals, as evidenced for the montmorillonite assay where transformation contributed 74.6 wt% to the total removal of benzo[a]pyrene at 200 °C. Overall, our findings demonstrate a major overlooked contribution of transformation to PAH removal at low temperature.

Jia, T., Pan, L., Gong, S., Xie, J., Wang, X., Fang, Y., Zou, J.-J., Zhang, X., 2020. Mechanistic insights into the thermal deposition of highly thermal-stable jet fuel. Fuel 276, 118100.


Highly thermal-stable jet fuel plays an important role in the advanced supersonic aircrafts, but its oxidation to the insoluble deposits is a serious problem when serving as a coolant. However, there are few reports as to the deep insights of insoluble deposits formation. Here we apply the PetroOxy device to investigate the thermal oxidation and deposition behaviors of highly thermal-stable jet fuel, using decalin as the model jet fuel, in order to explore the formation mechanism of insoluble deposits. All oxidation products (gas, liquid and solid) of fuel at different oxidation stages were separated and carefully characterized. The initial oxidation of fuel produces hydroperoxides, which then decompose rapidly to produce gas products (H2, CO or CO2) as well as large amounts of polar species (soluble oxidized products, e.g., alcohols, ketones, and molecular growth products). Meanwhile, these polar monomer species condense to produce soluble macromolecular oxidatively reactive species (SMORS) and insoluble deposits. The SMORS amount increases during the overall oxidation process, but the amount of insoluble deposits increases only in the presence of oxygen. The characterizations of liquid chromatography/electrospray ionization mass spectrometry and solution-state 2D heteronuclear single quantum coherence NMR confirm that the concentration of highly polar macromolecular species in insoluble deposits is much higher than that in SMORS, which causes the precipitation of the insoluble deposits from the bulk fuel. We further propose the detailed formation process and chemical structures of the insoluble deposits during the autoxidation of highly thermal-stable jet fuel, which would be helpful for a better understanding of the deposition mechanism of jet fuel and the improvement of its thermal stability.

Jiang, S., Wang, G., Li, S., Wang, G., Li, X., Zhang, H., Zhang, W., Cao, W., Dai, L., Suo, Y., Somerville, I., 2020. Potential deep-buried petroleum systems in Meso-Neoproterozoic rifts of the southwestern North China Craton revealed by gravity anomalies. Precambrian Research 346, 105764.


In order to evaluate the potential petroleum system within the Meso-Neoproterozoic strata of the southwest North China Craton (NCC), we explored the deep-buried basal tectonics on the Precambrian basement and the residual sedimentary thickness of the Meso-Neoproterozoic in the Ordos Basin. A combination of geophysical processing methodologies has been conducted. Based on regional seismic exploration, the shallow gravity effects caused by the undulation of the Cenozoic, Jurassic, Carboniferous and Cambrian sedimentary formations were calculated through forward modeling, and eliminated the free-air gravity anomaly by a gravity stripping technique. Subsequently, by using the wavelet multi-scale decomposition method, the deeper gravity effect sourcing from underneath the Meso-Neoproterozoic base was calculated and then eliminated, including the undulation of Paleoproterozoic-Archaean crystalline basement and the lateral density discontinuity of the lower crust. As a result, the residual gravity anomalies caused by the Meso-Neoproterozoic sedimentary formations and the Moho discontinuity of the Ordos Block were both obtained, which was then used for inversion. The inversion results show that the residual Meso-Neoproterozoic strata are mainly distributed in the southwest and northern part of the Ordos Block, and the Moho depth of the Ordos Block averages about 42 km. It ranges from 38 to 42 km in the eastern part and deepens to over 44 km in the west. In addition, there are some detailed deep-structure reflections on the Moho discontinuity. For instance, the parallel-arranged NE-trending

anomalous belts in southwest Ordos Block indicate strong crustal extension and mantle uplift. The regional geology indicates that the NE-trending crustal extension is not related to the Cenozoic strike-slip pull-apart process around the Ordos Block, nor the Indosinian Movement in Early Mesozoic, or the cratonic depression in the Paleozoic. However, it highly resembles the NE-oriented paleo-rifts that developed in the Meso-Neoproterozic aulacogens. The residual crustal gravity anomaly eliminates both the shallow disturbance from the sediments and the deep shadow from the mantle. It shows very good consistency with the undulation of the Meso-Neoproterozoic sedimentary basement along a classical interpreted seismic survey line, which validates the correlation between the NE-trending anomalous belts with the basal aulacogen tectonics. According to seismic interpretation, the paleo-rifts within the Precambrian aulacogens occurred during the Mesoproterozoic and continued into the early Neoproterozoic. Huge volumes of sediment filled the rift troughs during the Meso-Neoproterozoic, causing a significant gravity loss on the gravity field, and formed considerable oil–gas exploration potential. Given suitable paleoclimatic conditions, the grabens would have provided a favorable environment for organic-rich shales and source rocks to develop. While the faults controlling the grabens and horsts would have played an important role in the migration and accumulation of hydrocarbons in the potential petroleum system. Combined with paleoclimate and lithofacies paleogeography analysis, five favorable areas are speculated for Meso-Neoproterozoic potential petroleum systems, which are the northwest Yimeng Uplift, the northern Tianhuan Depression, the southern Tianhuan Depression, the southwestern to central Yishaan Slope and the western Weibei Uplift, respectively. Based on lithofacies paleogeography, source rock maturity and organic carbon abundance, it suggests that the favorable petroleum systems within the Proterozoic strata of the Ordos Block were obviously controlled or influenced by the deep paleo-rifts and block faults, which resulted in forming three types of play, called the Weathering Model, the Tilting Model and the Transition Model. In particular, the central to western parts of the Yimeng Uplift and the southern Tianhuan Depression, where the Weathering Model developed, as the Upper Paleozoic coal-bearing source rocks have large hydrocarb n generation potential and good preservation conditions, these two areas should be regarded as important favorable prospecting regions in the Ordos Basin.

Jin, S., Wang, H., Cao, H., Gan, H., Chen, S., 2020. Lake-type controls on sedimentary infill and petroleum source rocks in the Palaeogene Fushan Depression, Beibuwan Basin, South China. Geological Journal 55, 3936-3956.


The lacustrine Beibuwan Basin contained large petroleum reserves in the northern continental shelf of the South China Sea. Due to the great sedimentologic complexity of the lacustrine basins, a significant financial risk associated with exploration needed to be reduced by specific techniques or significantly increasing knowledge of the lake system. Sedimentary infill, sequence stratigraphy, and organic geochemistry of the Fushan Depression in the Beibuwan Basin were studied, and enhanced our comprehension of the genetic relations between the sediment + water supply rates (climate change) and potential accommodation (tectonic subsidence and inherited topography) change. Here, we report two different lake-type evolution cycles developed in two separated sags in the Fushan Depression, which are characterized by: (a) overfilled, (b) balanced-fill, (c) overfilled, (d) balanced-fill, and (e) overfilled in the Huangtong Sag, and (a) overfilled, (b) balanced-fill, and (c) overfilled in the Bailian Sag and the centre Huachang Transfer Zone. Climate change is the dominant factor in the first three phases of the lake-type evolution in both two sags, and transtensional

tectonic setting is the controlling factor in the fourth and fifth phases of the lake-type evolution in the Huangtong Sag. The same lake-type with similar source rock and reservoir properties and observations indicate that these associations of source rock and reservoir play elements occur in a wide variety of tectonic settings. Moreover, the discovery of the cyclical process of the lake-type evolution in the Fushan Depression can be a reference in the study of other similar lacustrine basins under an analogous tectonic and climate background.


http://dx.doi.org/10.1039/D0AN00128G

This study developed a traceless clean-up method by combining solid phase extraction (SPE) with gas purge–microsyringe extraction (GP–MSE) to purify sample extracts for the determination of polycyclic aromatic hydrocarbons (PAHs) in plant leaves. SPE exhibited good purification performance for the removal of polar lipids, while the GP–MSE technique effectively eliminated less-volatile lipids hence realizing zero damage to the instrument, and significantly improved the peak tailings. After ultrasonic extraction, the combined two-step clean-up procedure successfully removed over 99% of lipids from nineteen types of tree leaves, and PAHs in tree leaves were determined by GC–MS. The relative standard deviations (RSDs) for intra-day (n = 3) and inter-day (n = 3) analyses of PAHs in spiked willow samples were in the range of 0.8%–12.1% and 4.7%–15.3%, respectively. The recoveries of PAHs from spiked willow extracts ranged from 74 to 90%, with an average of 86%. The method detection limit (MDL) of PAHs in tree leaves ranged from 0.1 to 4.9 ng g−1 dry weight. In conclusion, the clean-up method in this study realized the analysis of PAHs in plant leaves with high accuracy, sensitivity and reproducibility. Most importantly, the two-step purification method significantly minimizes damage to the GC–MS system particularly to the column and ion source, which is beneficial to ensure continuous analysis of a large number of samples with good performance.



Identifying the spatial distributions of biomolecules in tissue is crucial for understanding integrated function. Imaging mass spectrometry (IMS) allows simultaneous mapping of thousands of biosynthetic products such as lipids but has needed a means of identifying specific cell-types or functional states to correlate with molecular localization. We report, here, advances starting from identity marking with a genetically encoded fluorophore. The fluorescence emission data were integrated with IMS data through multimodal image processing with advanced registration techniques and data-driven image fusion. In an unbiased analysis of spleens, this integrated technology enabled identification of ether lipid species preferentially enriched in germinal centers. We propose that this use of genetic marking for microanatomical regions of interest can be paired with molecular information from IMS for any tissue, cell-type, or activity state for which

fluorescence is driven by a gene-tracking allele and ultimately with outputs of other means of spatial mapping.


https://doi.org/10.1111/1462-2920.14920

The post glacial Baltic Sea has experienced extreme changes that are archived today in the deep ‐sediments. IODP Expedition 347 retrieved cores down to 100 m depth and studied the climate history and the deep biosphere. We here review the biogeochemical and microbiological highlights and integrate these with other studies from the Baltic seabed. Cell numbers, endospore abundance and organic matter mineralization rates are extremely high. A 100 fold drop in cell numbers with ‐depth results from a small difference between growth and mortality in the ageing sediment. Evidence for growth derives from a D:L amino acid racemization model, while evidence for mortality derives from the abundance and potential activity of lytic viruses. The deep communities assemble at the bottom of the bioturbated zone from the founding surface community by selection of organisms suited for life under deep sediment conditions. The mean catabolic per cell rate of ‐microorganisms drops steeply with depth to a life in slow motion, typical for the deep biosphere. ‐The subsurface life under extreme energy limitation is facilitated by exploitation of recalcitrant substrates, by biochemical protection of nucleic acids and proteins and by repair mechanisms for random mismatches in DNA or damaged amino acids in proteins.

Ju, Y., Lee, S.-S., Kaown, D., Lee, K.-K., Gilfillan, S.M.V., Hahm, D., Park, K., 2020. Noble gas as a proxy to understand the evolutionary path of migrated CO2 in a shallow aquifer system. Applied Geochemistry 118, 104609.


To provide confidence in the safety of a carbon capture and storage (CCS) project, researchers have focused on developing monitoring techniques to trace the unlikely, but potentially possible, migration of CO2 from a deep reservoir. Among the various techniques, noble gas tracing is a beneficial approach, owing to the unique noble gas fingerprints present in injection fluids, the deep reservoir, and the shallow aquifer above the storage area. However, the value of this approach has been limited to demonstrations in a natural analogue CO2-rich reservoir and an artificial injection test site. Therefore, further efforts are required to link those valuable observations to an actual CCS site. In this study, we outline how to use these tracers for actual monitoring work in a shallow aquifer system. First, two artificial injection tests were performed using He, Ar, Kr, and SF6 to understand the behavior of the leaked plume in the shallow aquifer system. In both tests, the noble gas ratio remarkably changed with the solubility-controlled process and the mixing process. To extend and link the valuable findings from the artificial injection tests to an actual CO2 leakage event, we performed a leakage simulation using data from a real CO2 injection site, i.e., the Weyburn–Midale site. This simulation suggested that combinations of 4He with other heavier noble gases can be used to monitor CO2 leakage, as they allow us to separate and explain the major interactions governing the migration of the leaked plume in the shallow aquifer system. Additionally, although the high CO2 density of a dissolved plume is known to add uncertainty in quantitative approaches, the influence of those effects was negligible when compared to the errors

arising from the wide variation in the noble gas fingerprints in the leaked CO2. This study, therefore, provides insight into the evolutionary path of the migrated CO2 plume in the shallow aquifer system and to the results can be used to inform the tracing of a leakage source within a shallow aquifer despite various mechanisms complicating the plume distribution.

Juhls, B., Stedmon, C.A., Morgenstern, A., Meyer, H., Hölemann, J., Heim, B., Povazhnyi, V., Overduin, P.P., 2020. Identifying drivers of seasonality in Lena River biogeochemistry and dissolved organic matter fluxes. Frontiers in Environmental Science 8, 53. doi: 10.3389/fenvs.2020.00053.

https://www.frontiersin.org/article/10.3389/fenvs.2020.00053

Warming air temperatures, shifting hydrological regimes and accelerating permafrost thaw in the catchments of the Arctic rivers is affecting their biogeochemistry. Arctic river monitoring is necessary to observe changes in the mobilization of dissolved organic matter (DOM) from permafrost. The Lena River is the second largest Arctic river and 71% of its catchment is continuous permafrost. Biogeochemical parameters, including temperature, electrical conductivity (EC), stable water isotopes, dissolved organic carbon (DOC) and absorption by colored dissolved organic matter (aCDOM) have been measured as part of a new high-frequency sampling program in the central Lena River Delta. The results show strong seasonal variations of all biogeochemical parameters that generally follow seasonal patterns of the hydrograph. Optical indices of DOM indicate a trend of decreasing aromaticity and molecular weight from spring to winter. High-frequency sampling improved our estimated annual fluvial flux of annual dissolved organic carbon flux (6.79 Tg C). EC and stable isotope data were used to distinguish three different source water types which explain most of the seasonal variation in the biogeochemistry of the Lena River. These water types match signatures of (1) melt water, (2) rain water, and (3) subsurface water. Melt water and rain water accounted for 84% of the discharge flux and 86% of the DOC flux. The optical properties of melt water DOM were characteristic of fresh organic matter. In contrast, the optical properties of DOM in subsurface water revealed lower aromaticity and lower molecular weights, which indicate a shift toward an older organic matter source mobilized from deeper soil horizons or permafrost deposits. The first year of this new sampling program sets a new baseline for flux calculations of dissolved matter and has enabled the identification and characterization of water types that drive the seasonality of the Lena River water properties.



To better understand and evaluate the corrosion performance of candidate structural steels and ferritic stainless steels for production, transport, and storage of biomass pyrolysis oils, corrosion studies were conducted in selected organic constituents of bio-oils, including catechol, formic acid, and their mixtures as well as lactobionic acid, using electrochemical impedance spectroscopy. R2, the resistance against corrosion reaction, was obtained by fitting measured impedance spectra into an equivalent circuit. The values of R2 were then used to assess corrosion resistance of the steels in each organic constituent and mixture. Type 410 and 430 stainless steels were resistant to corrosion in all tested organic constituents, while 2.25Cr-1Mo steel was not. 9Cr-1Mo steel was corrosion

resistant in catechol but not in the other mixtures that contained organic acids. On the basis of the results of this work, it is suggested that the corrosion resistance against organic acids is attributed to formation of a Cr-rich passive film that requires stainless steels with critical Cr levels in excess of approximately 11 wt %. In catechol-only solution, lower levels of Cr intermediate between that of 2.25Cr-1Mo steel and 9Cr-1Mo steel appeared sufficient.

Kadjo, A.F., Dasgupta, P.K., Shelor, C.P., 2020. Optimum cell pathlength or volume for absorbance detection in liquid chromatography: Transforming longer cell results to virtual shorter cells. Analytical Chemistry 92, 6391-6400.

https://doi.org/10.1021/acs.analchem.9b05464

The cell volume permissible for a specified degree of loss of efficiency can be computed from response volume considerations. For an open tubular column, the permissible illuminated length can be computed for the unretained peak. Similar estimations can be made for the maximum permissible cell volume with a packed column for a given column efficiency and flow rate. The packed column case does require an assumption on the degree to which the cell behaves as a mixer. An altogether different question is if the data from a long cell, with its considerable advantage in S/N, can be used and the associated dispersion mathematically removed. Experimental data for a variable path length (0–60 mm) HPLC detection cell indicate that an exponential model fits the observed dispersion. Once fit parameters are determined, the same can be applied to a peak, not part of the original training set, obtained in a longer path cell and the effects of dispersion mathematically reversed without major loss of S/N. Results with shorter path cell dispersion characteristics are then obtained with much higher S/N. A comparison is made with Fourier transform–inverse Fourier transform based deconvolution that can be used to achieve the same ends.

Kaiser, J., Wasmund, N., Kahru, M., Wittenborn, A.K., Hansen, R., Häusler, K., Moros, M., Schulz-Bull, D., Arz, H.W., 2020. Reconstructing N2-fixing cyanobacterial blooms in the Baltic Sea beyond observations using 6- and 7-methylheptadecane in sediments as specific biomarkers. Biogeosciences 17, 2579-2591.


Summer cyanobacterial blooms represent a threat to the Baltic Sea ecosystem, causing deoxygenation of the bottom water and the spread of the so-called dead zones. The history of the Baltic Sea cyanobacterial blooms is known from in situ and satellite observations since the early 1980s but is still not well understood. By comparing both weekly resolved sediment trap material and a well-dated sediment core from the eastern Gotland Basin with monitoring and satellite cyanobacterial data of the last ca. 35 years, it is shown here that 6- and 7-methylheptadecane lipids (expressed as 6+7Me-C17 : 0) may be potentially considered semiquantitative biomarkers for diazotrophic cyanobacteria, and more specifically for Nodularia spumigena. Using this organic proxy, it was thus possible to reconstruct the history of cyanobacterial blooms beyond the observational period with a resolution of 2–4 years since 1860. Cyanobacteria were constantly present but in relatively low abundance until 1920, when they started to alternate between periods with high and low abundance. Interestingly, there seems to be no significant increase in cyanobacterial abundance in the 1950s, when eutrophication and deoxygenation of the Baltic Sea increased considerably.

While the early increase in cyanobacteria may be related to a small increase in phosphorus loading, decadal to multi-decadal fluctuations are likely related to variability in the Baltic Sea surface temperature and, ultimately, to the Atlantic Multi-decadal Oscillation. A 7000-year 6+7Me-C17 : 0 record from the Bothnian Sea also suggests a relationship with the mean summer temperature in the Baltic Sea region but at a multi-centennial to multi-millennial timescale. The intensity of the cyanobacterial blooms in the Baltic Sea is thus likely mainly related to natural processes such as temperature variability, at least at a multi-decadal to multi-millennial timescale.

Kalwasińska, A., Krawiec, A., Deja-Sikora, E., Gołębiewski, M., Kosobucki, P., Swiontek Brzezinska, M., Walczak, M., 2020. Microbial diversity in deep-subsurface hot brines of northwest Poland: From community structure to isolate characteristics. Applied and Environmental Microbiology 86, e00252-20.

http://aem.asm.org/content/86/10/e00252-20.abstract

Abstract: Deep-subsurface hot brines in northwest Poland, extracted through boreholes reaching 1.6 and 2.6 km below the ground surface, were microbiologically investigated using culture-independent and culture-dependent methods. The high-throughput sequencing of 16S rRNA gene amplicons showed a very low diversity of bacterial communities, which were dominated by phyla Proteobacteria and Firmicutes. Bacterial genera potentially involved in sulfur oxidation and nitrate reduction (Halothiobacillus and Methylobacterium) prevailed in both waters over the sulfate reducers (“Candidatus Desulforudis” and Desulfotomaculum). Only one archaeal taxon, affiliated with the order Thermoplasmatales, was detected in analyzed samples. Bacterial isolates obtained from these deep hot brines were closely related to Bacillus paralicheniformis based on the 16S rRNA sequence similarity. However, genomic and physiological analyses made for one of the isolates, Bacillus paralicheniformis strain TS6, revealed the existence of more diverse metabolic pathways than those of its moderate-temperature counterpart. These specific traits may be associated with the ecological adaptations to the extreme habitat, which suggest that some lineages of B. paralicheniformis are halothermophilic.

Importance: Deep-subsurface aquifers, buried thousands of meters down the Earth’s crust, belong to the most underexplored microbial habitats. Although a few studies revealed the existence of microbial life at the depths, the knowledge about the microbial life in the deep hydrosphere is still scarce due to the limited access to such environments. Studying the subsurface microbiome provides unique information on microbial diversity, community structure, and geomicrobiological processes occurring under extreme conditions of the deep subsurface. Our study shows that low-diversity microbial assemblages in subsurface hot brines were dominated by the bacteria involved in biogeochemical cycles of sulfur and nitrogen. Based on genomic and physiological analyses, we found that the Bacillus paralicheniformis isolate obtained from the brine under study differed from the mesophilic species in the presence of specific adaptations to harsh environmental conditions. We indicate that some lineages of B. paralicheniformis are halothermophilic, which was not previously reported.

Kang, S.S., Kang, J.W., 2020. Extraction of naphthenic acid from low-grade crude oil using diol compounds. Fuel 275, 117828.


The extraction of naphthenic acid from low-grade crudes offers economic and environmental advantages over chemical conversion or other separation processes. The properties of the solvent play critical roles for the successful implementation of the extraction process. Solvent screening techniques based on thermodynamic prediction can facilitate the selection of candidate solvents. This study first performed solvent screening based on thermodynamic property estimation using the COSMO-RS method and subsequently verified the solvent performances experimentally. The formation of liquid–liquid equilibrium (LLE), mutual solubility, and ternary LLE were predicted for n-octanol + n-octanoic acid + solvent mixtures. The predicted results were analyzed for the selection of the best candidates to remove acidic components from crude oil. From the theoretical calculations, 1,6-hexanediol was selected as the best candidate solvent. This result was experimentally verified by extracting reagent-grade naphthenic acid from diesel oil using the candidate solvents. The measured results were consistent with the trend observed in the theoretical calculations. Among the candidate solvents, 1,6-hexanediol reduced the acidic component composition corresponding to 5 mg KOH/g down to 1 mg KOH/g with a solvent fraction of 0.6.

Katz, L., Woolman, M., Talbot, F., Amara-Belgadi, S., Wu, M., Tortorella, S., Das, S., Ginsberg, H.J., Zarrine-Afsar, A., 2020. Dual laser and desorption electrospray ionization mass spectrometry imaging using the same interface. Analytical Chemistry 92, 6349-6357.


For a more comprehensive characterization of molecular heterogeneities of matter, multimodal mass spectrometry imaging must be developed to take advantage of the complementarity of information available through different ionization mechanisms. We report the design, implementation, and performance validation of a laser desorption imaging interface composed of add-on components that adapt a commercial Desorption Electrospray Ionization Mass Spectrometry (DESI–MS) imaging interface for dual imaging of Picosecond Infrared Laser Mass Spectrometry (PIRL–MS) with DESI–MS. The interface utilizes hardware elements and data analysis pipelines already established for DESI–MS imaging, and was further validated in cancer margin assessments using human medulloblastoma cancers. The PIRL–MS images were robust and reproducible across multiple experimental runs on independently prepared xenograft tumors, and could be segmented into cancer and healthy regions in concordance with pathology using a variety of supervised and unsupervised clustering methods. The spectral quality and complexity obtained with this interface were examined with infiltrating and noninfiltrating tumors, and were comparable to other mass spectrometry analysis interfaces. The average PIRL–MS spectra from spatially resolved images could be used for robust cancer m/z model building to classify medulloblastoma cancer from healthy tissue without any misclassifications, an observation that held true over close to 70 sampling data points. While the unsupervised spectral analysis methods suggested a slight suppression of signal in the phospholipid range compared to the hand-held configuration, these changes were insufficient to hamper utility in cancer margin assessment with spatially resolved data obtained with our interface. Dual PIRL–MS and DESI–MS imaging of consecutive sections, as suggested by multivariate loading plots, revealed highly complementary molecular information with m/z values identifiable with one desorption method sufficient to reveal cancer regions being absent in another, further emphasizing the need for effective hardware and software interfaces for dual mass spectrometry imaging.

Kayukova, G.P., Mikhailov, A.N., Kosachev, I.P., Morozov, V.P., Vakhin, A.V., 2020. Hydrothermal transformations of organic matter of carbon-rich Domanik rock in carbon dioxide environment at different temperatures. Petroleum Chemistry 60, 278-290.

https://doi.org/10.1134/S0965544120030093

The influence of temperature on the nature of transformation of organic matter (OM) of carbon-rich rocks from Upper Devonian Semilukian–Mendymian (domanik) deposits of the Berezovskaya area of the Romashkino oilfield in hydrothermal processes has been studied. The experiments have been carried out at temperatures of 200, 250, 300, and 350°C in a CO2 medium in the presence of water in an amount of 30% of rock mass in the reaction system. The yield and changes in the component, structural-group, and hydrocarbon-group composition of extracts obtained from rocks before and after hydrothermal experiments have been evaluated. It has been established that at temperatures of 300 and 350°C, high-molecular-weight components and insoluble kerogen undergo degradation processes, leading to a noticeable increase in the concentration of free hydrocarbons in the rock and their more complete extraction from the rocks. By the nature of molecular-mass distribution of normal and isoprenoid alkanes, the extracts from the rocks are similar to oils of the A1 and A2 types (according to the chemical classification by A.A. Petrov) from productive formations of the Devonian and Carboniferous deposits of the Romashkino field. The treatment of the domanik rock at lower temperatures of 200 and 250°C facilitates more intensive recovery of free hydrocarbons from the rock, without significantly affecting the structure of kerogen by destructive processes. The influence of temperature on the phase transformations of asphaltenes and their paramagnetic properties, as well as on the composition of biomarker hydrocarbons associated with the genotype of original OM and lithology and maturity of possible oil producing strata, has been revealed. It has been shown that carbonate–siliceous source rocks of domanik deposits of the Romashkino field can become an additional source of petroleum hydrocarbons in the case of development using hydrothermal technologies.



Simple molecules such as formaldehyde and ammonia were expected to be incorporated into small bodies with water ice in the early accretion history. These molecules would have reacted to produce various organic compounds during aqueous alteration which most of the primitive carbonaceous chondrite parent bodies have experienced. Our previous hydrothermal experiments involving formaldehyde and ammonia have already shown formations of amino acids and organic solids that resemble to macromolecular organic matter in primitive meteorites. Here we focus on the characterization in liquid phases with various analytical methods including high-resolution mass spectrometry (HRMS), X-ray absorption near edge structure (XANES), and Fourier-transform infrared spectroscopy (FTIR), in addition to kinetic analyses of the reactions using in-situ FTIR spectroscopy with a heatable liquid cell.

The HRMS results showed that soluble fractions contain various carbohydrates (CHO molecules) and these with nitrogen (CHON molecules). The mass defect plots of the reaction products suggested the reactions involving CH2O addition, CH2 addition, dehydration and decarboxylation. C-C and C-N

bonds increased with temperature by condensation reactions. Behaviors of oxygen-bearing functional groups showed high complexity. In general, carboxyl/ester/aldehyde compounds formed at the early stage of the reactions, then some of these decomposed by decarboxylation. N-XANES indicated the presence of amide-bearing compounds that could be precursors of amino acids.

The in-situ FTIR spectra showed that formaldehyde and ammonia reacted and formed hexamethylenetetramine (HMT) before starting the heating experiments at room temperature. Kinetic analyses showed that the apparent activation energy of decreases in HMT is ~130–140 kJ mol−1. The decrease in HMT is faster than the other reactions, indicating that the reactions involving HMT occurred at the early stage of the aqueous alteration. The kinetics of the ammonia–aldehyde system suggested that the reactions involving formaldehyde, ammonia and HMT are efficient for aqueous alteration in parent bodies of CI, CM, and CR chondrites.

Kellerman, A.M., Hawkings, J.R., Wadham, J.L., Kohler, T.J., Stibal, M., Grater, E., Marshall, M., Hatton, J.E., Beaton, A., Spencer, R.G.M., 2020. Glacier outflow dissolved organic matter as a window into seasonally changing carbon sources: Leverett Glacier, Greenland. Journal of Geophysical Research: Biogeosciences 125, e2019JG005161.

https://doi.org/10.1029/2019JG005161

The Greenland Ice Sheet is losing mass at a remarkable rate as a result of climatic warming. This mass loss coincides with the export of dissolved organic matter (DOM) in glacial meltwaters. However, little is known about how the source and composition of exported DOM changes over the melt season, which is key for understanding its fate in downstream ecosystems. Over the 2015 ablation season, we sampled the outflow of Leverett Glacier, a large land terminating glacier of the ‐Greenland Ice Sheet. Dissolved organic carbon (DOC) concentrations and DOM fluorescence were analyzed to assess the evolution of DOM sources over the course of the melt season. DOC concentrations and red shifted fluorescence were highly associated (‐ R2 > 0.95) and suggest terrestrial inputs from overridden soils dominated DOM early season inputs before progressive dilution with increasing discharge. During the outburst period, supraglacial drainage events disrupted the subglacial drainage system and introduced dominant protein like fluorescence ‐signatures not observed in basal flow. These results suggest that subglacial hydrology and changing water sources influence exported DOC concentration and DOM composition, and these sources were differentiated using fluorescence characteristics. Red shifted fluorescence components were ‐robust proxies for DOC concentration. Finally, the majority of DOM flux, which occurs during the outburst and postoutburst periods, was characterized by protein like fluorescence from supraglacial‐ and potentially subglacial microbial sources. As protein like fluorescence is linked to the ‐bioavailability of DOM, the observed changes likely reflect seasonal variations in the impact of glacial inputs on secondary production in downstream ecosystems due to shifting hydrologic regimes.

Kenkmann, T., Wulf, G., Agarwal, A., 2020. Ramgarh, Rajasthan, India: A 10 km diameter complex impact structure. Meteoritics & Planetary Science 55, 936-961.

https://doi.org/10.1111/maps.13454

The Ramgarh structure is a morphological landmark in southeastern Rajasthan, India. Its 200 m high and 3.5?4 km wide annular collar has provoked many hypotheses regarding its origin, including impact. Here, we document planar deformation features, planar fractures, and feather features in quartz grains of the central part of the Ramgarh structure, which confirm its impact origin. The annular collar does not mark the crater rim but represents the outer part of a central uplift of an approximately 10 km diameter complex impact structure. The apparent crater rim is exposed as a low-angle normal fault and can be traced as lineaments in remote sensing imagery. The central uplift shows a stratigraphic uplift of ~1000 m and is rectangular in shape. It is dissected by numerous faults that are co-genetic with the formation of the central uplift. The central uplift has a bilateral symmetry along an SW-NE axis, where a large strike-slip fault documents a strong horizontal shear component. This direction corresponds to the assumed impact trajectory from the SW toward the NE. The uprange sector is characterized by concentric reverse faults, whereas radial faults dominate downrange. Sandstones of the central uplift are infiltrated by Fe-oxides and suggest an impact-induced hydrothermal mineralization overprint. The impact may have occurred into a shallow water environment as indicated by soft-sediment deformation features, observed near the apparent crater rim, and the deposition of a diamictite layer above them. Gastropods embedded in the diamictite have Middle Jurassic age and may indicate the time of the impact.

Kessler, A., Bouttes, N., Roche, D.M., Ninnemann, U.S., Galaasen, E.V., Tjiputra, J., 2020. Atlantic Meridional Overturning Circulation and δ13C variability during the last interglacial. Paleoceanography and Paleoclimatology 35, e2019PA003818.

https://doi.org/10.1029/2019PA003818

The Atlantic Meridional Overturning Circulation (AMOC) is thought to be relatively vigorous and stable during Interglacial periods on multimillennial (equilibrium) timescales. However, recent proxy (δ13C benthic) reconstructions suggest that higher frequency variability in deep water circulation may have been common during some interglacial periods, including the Last Interglacial (LIG, 130–115 ka). The origin of these isotope variations and their implications for past AMOC remain poorly understood. Using iLOVECLIM, an Earth system model of intermediate complexity (EMIC) allowing the computation of δ13CDIC and direct comparison to proxy reconstructions, we perform a transient experiment of the LIG (125–115 ka) forced only by boundary conditions of greenhouse gases and orbital forcings. The model simulates large centennial scale variations in the interior δ‐ 13CDIC of the North Atlantic similar in timescale and amplitude to changes resolved by high resolution ‐reconstructions from the LIG. In the model, these variations are caused by changes in the relative influence of North Atlantic Deep Water (NADW) and southern source water (SSW) and are closely linked to large (∼50%) changes in AMOC strength provoked by saline input and associated deep convection areas south of Greenland. We identify regions within the subpolar North Atlantic with different sensitivity and response to changes in preformed of NADW and to changes in NADW versus SSW influence, which is useful for proxy record interpretation. This could explain the relatively large δ13C gradient (∼0.4%0) observed at ∼3 km water depth in the subpolar North Atlantic at the inception of the last glacial.

Khalturin, K., 2020. The origin of metazoan larvae. Nature Ecology & Evolution 4, 674-675.

https://doi.org/10.1038/s41559-020-1192-8

A comparative analysis of developmental transcriptomes across Metazoa provides a quantitative approach to test scenarios of life-cycle evolution and supports an ancestral adult form with later intercalation of larval stages.



The dead oil viscosity is a key parameter to numerous reservoir engineering problems such as modeling of (viscously-unstable) flow and transport in hydrocarbon reservoirs, sweep efficiency of enhanced oil recovery scenarios as well as the breakthrough times of the injected fluid. Prediction of this thermos-physical parameter, however, is of challenge due to nonlinear dependence on reservoir conditions as well as the crude oil characteristics. Previous studies have attempted to develop predictive empirical correlations or other intelligent models for dead oil viscosity; however, they often suffer from the lack of generality and required accuracy. In this work, based on a comprehensive databank from diverse geological sources, we develop three intelligent models –upon various schemes including simulated annealing programming, artificial neural network, and decision tree– for estimating dead oil viscosity. The latter may be used further for prediction of saturated and under-saturated oil viscosity as well. Our models function in wide range of temperatures and oil API gravity; hence, they can be employed as unified, general-in-purpose frameworks for universal prediction of dead oil viscosity. We compare the resulting novel frameworks with the pre-existing models available in the literature, and demonstrate the superiority of the decision tree-based model over others in terms of statistical (and graphical) error estimates as well as the (physical) validity of the model. The findings of this study can help for better understanding and more accurate management, simulation and prediction in different oil fields.


https://doi.org/10.1093/mnras/staa329

We have studied the conditions of through passage of asteroids with diameters 200, 100, and 50 m, consisting of three types of materials – iron, stone, and water ice, across the Earth’s atmosphere with a minimum trajectory altitude in the range 10–15 km. The conditions of this passage with a subsequent exit into outer space with the preservation of a substantial fraction of the initial mass have been found. The results obtained support our idea explaining one of the long-standing problems of astronomy – the Tunguska phenomenon, which has not received reasonable and comprehensive interpretations to date. We argue that the Tunguska event was caused by an iron asteroid body, which passed through the Earth’s atmosphere and continued to the near-solar orbit.

Khullar, S., Pandita, S.K., Meinhold, G., Bhat, G.M., Raina, B.K., Thusu, B., Jones, M.J., 2020. Discovery of organic matter and palynomorphs from the Neoproterozoic Zor diamictite of the Ramsu Formation

in the Ramban District, Jammu and Kashmir, India. Journal of the Geological Society of India 95, 447-454.

https://doi.org/10.1007/s12594-020-1461-9

The presence of medium-grade organic matter confirmed by Raman spectroscopy is reported for the first time from the Zor diamictite of the Ramsu Formation, Tethyan Himalaya. The organic matter has undergone overmature thermal evolution. The sediment shows low total organic carbon (TOC) and low total sulfur (TS) values of <0.25% and <0.01%, respectively. Low TS/TOC < 0.08 suggests oxic bottom waters during the deposition of the Zor diamictite. The recovered palynomorph assemblage includes Leiosphaeridia spp., Kildinosphaera verrucata, Trachyhystrichosphaera sp., the filamentous cyanophyte Taeniatum sp., the clusters of simple, spheroidal forms Myxococcoides sp., and the colonial cyanobacteria Synsphaeridium sp. This palynomorph assemblage suggests a Neoproterozoic age for the Zor diamictite of the Ramsu Formation.



The dead oil viscosity is a key parameter to numerous reservoir engineering problems such as modeling of (viscously-unstable) flow and transport in hydrocarbon reservoirs, sweep efficiency of enhanced oil recovery scenarios as well as the breakthrough times of the injected fluid. Prediction of this thermos-physical parameter, however, is of challenge due to nonlinear dependence on reservoir conditions as well as the crude oil characteristics. Previous studies have attempted to develop predictive empirical correlations or other intelligent models for dead oil viscosity; however, they often suffer from the lack of generality and required accuracy. In this work, based on a comprehensive databank from diverse geological sources, we develop three intelligent models –upon various schemes including simulated annealing programming, artificial neural network, and decision tree– for estimating dead oil viscosity. The latter may be used further for prediction of saturated and under-saturated oil viscosity as well. Our models function in wide range of temperatures and oil API gravity; hence, they can be employed as unified, general-in-purpose frameworks for universal prediction of dead oil viscosity. We compare the resulting novel frameworks with the pre-existing models available in the literature, and demonstrate the superiority of the decision tree-based model over others in terms of statistical (and graphical) error estimates as well as the (physical) validity of the model. The findings of this study can help for better understanding and more accurate management, simulation and prediction in different oil fields.


https://doi.org/10.1093/mnras/staa329

We have studied the conditions of through passage of asteroids with diameters 200, 100, and 50 m, consisting of three types of materials – iron, stone, and water ice, across the Earth’s atmosphere

with a minimum trajectory altitude in the range 10–15 km. The conditions of this passage with a subsequent exit into outer space with the preservation of a substantial fraction of the initial mass have been found. The results obtained support our idea explaining one of the long-standing problems of astronomy – the Tunguska phenomenon, which has not received reasonable and comprehensive interpretations to date. We argue that the Tunguska event was caused by an iron asteroid body, which passed through the Earth’s atmosphere and continued to the near-solar orbit.

Khullar, S., Pandita, S.K., Meinhold, G., Bhat, G.M., Raina, B.K., Thusu, B., Jones, M.J., 2020. Discovery of organic matter and palynomorphs from the Neoproterozoic Zor diamictite of the Ramsu Formation in the Ramban District, Jammu and Kashmir, India. Journal of the Geological Society of India 95, 447-454.

https://doi.org/10.1007/s12594-020-1461-9

The presence of medium-grade organic matter confirmed by Raman spectroscopy is reported for the first time from the Zor diamictite of the Ramsu Formation, Tethyan Himalaya. The organic matter has undergone overmature thermal evolution. The sediment shows low total organic carbon (TOC) and low total sulfur (TS) values of <0.25% and <0.01%, respectively. Low TS/TOC < 0.08 suggests oxic bottom waters during the deposition of the Zor diamictite. The recovered palynomorph assemblage includes Leiosphaeridia spp., Kildinosphaera verrucata, Trachyhystrichosphaera sp., the filamentous cyanophyte Taeniatum sp., the clusters of simple, spheroidal forms Myxococcoides sp., and the colonial cyanobacteria Synsphaeridium sp. This palynomorph assemblage suggests a Neoproterozoic age for the Zor diamictite of the Ramsu Formation.

Khvalbota, L., Roy, D., Wahab, M.F., Firooz, S.K., Machyňáková, A., Špánik, I., Armstrong, D.W., 2020. Enhancing supercritical fluid chromatographic efficiency: Predicting effects of small aqueous additives. Analytica Chimica Acta 1120, 75-84.


Supercritical fluid chromatography is becoming more prevalent, particularly in industry. This is due to the inexpensive, and more importantly, environmentally benign carbon dioxide that is used as the major component of the mobile phase. Water is minimally miscible with carbon dioxide at temperatures and pressures commonly used in SFC. However, the introduction of a polar alcohol modifier component increases the solubility of water in carbon dioxide. Previously, the addition of small amounts of water in the mobile phase was shown to provide significant gains in efficiency in chiral supercritical fluid chromatography, especially with polar stationary phases. In this work, we report the effect of the addition of small amounts of water on efficiency and retention factor with four different SFC stationary phases used for achiral analysis namely FructoShell-N (native cyclofructan-6), SilicaShell (bare silica), PoroShell 120 EC C18 (octadecyl silica) and Xselect C18 SB. This is the first reported use of FructoShell-N, a cyclofructan derivatized phase for SFC applications. We devised a predictive test to determine which analytes show an increase in efficiency using their known chemical constants (logKow, pKa, PSA and Hsum). We also use discriminant analysis to elucidate the most important analyte parameters that contribute to “water enhanced” efficiency gains.

Kibria, M.G., Das, S., Hu, Q.-H., Basu, A.R., Hu, W.-X., Mandal, S., 2020. Thermal maturity evaluation using Raman spectroscopy for oil shale samples of USA: comparisons with vitrinite reflectance and pyrolysis methods. Petroleum Science 17, 567-581.

https://doi.org/10.1007/s12182-020-00443-z

Thermal maturity is commonly assessed by various geochemical screening methods (e.g., pyrolysis and organic petrology). In this contribution, we attempt to establish an alternative approach to estimating thermal maturity with Raman spectroscopy, using 24 North American oil shale samples with thermal maturity data generated by vitrinite reflectance (VRo%) and pyrolysis (Tmax)-based maturity calculation (VRe%). The representative shale samples are from the Haynesville (East Texas), Woodford (West Texas), Eagle Ford and Pearsall (South Texas) Formations, as well as Gothic, Mancos, and Niobrara Formation shales (all from Colorado). The Raman spectra of disordered carbonaceous matter (D1 and G bands separation) of these samples were directly obtained from the rock chips without prior sample preparation. Using the Gaussian and Lorentzian distribution approach, thermal maturities from VR were correlated with carbon G and D1. We found that the Raman band separation (RBS) displayed a better correlation for equivalent VRe% than vitrinite reflectance VRo%. The RBS (D1–G) distance versus total organic carbon, free hydrocarbons from thermal extraction (S1), and the remaining hydrocarbon generating potential (S2) indicate that the RBS (D1–G) distance is also related to kerogen type. Data presented here from three methods of maturity determination of shale demonstrate that Raman spectroscopy is a quick and valid approach to thermal maturity assessment.

Kim, J., Chhetri, G., Kim, I., Lee, B., Jang, W., Kim, M.K., Seo, T., 2020. Methylobacterium terricola sp. nov., a gamma radiation-resistant bacterium isolated from gamma ray-irradiated soil. International Journal of Systematic and Evolutionary Microbiology 70, 2449-2456.

https://www.microbiologyresearch.org/content/journal/ijsem/10.1099/ijsem.0.004054

A gamma radiation-resistant and pink-pigmented bacterial strain, designated as 17Sr1-39T, was isolated from a gamma ray-irradiated soil sample collected in the Republic of Korea. Cells were Gram-stain-negative, strictly aerobic, flagellated, asporogenous, rod-shaped and methylotrophic. Results of 16S rRNA gene sequence analysis showed that strain 17Sr1-39T was phylogenetically related to Methylobacterium currus PR1016AT (97.3 %), Methylobacterium aquaticum DSM 16371T (97.2 %), Methylobacterium platani PMB02T (97.0 %), Methylobacterium frigidaeris IER25-16T (96.6 %), Methylobacterium terrae 17Sr1-28T (96.6 %) and Methylobacterium organophilum JCM 2833T (93.4 %). The G+C content calculated based on the genome sequence was 70.4 mol%. The average nucleotide identity and in silico DNA–DNA hybridization values between strain 17Sr1-39T and M. currus , M. aquaticum , M. platani , M. frigidaeris , M. terrae and M. organophilum were 77.3–89.9 and 22–38.2 %, respectively. The predominant fatty acids were summed feature 8 (C18 : 1ω7c and/or C18 : 1ω6c) and summed feature 3 (C16 : 1ω7c and/or C16 : 1ω6c). The predominant quinone was ubiquinone 10 and the major polar lipids were diphosphatidylglycerol, phosphatidylglycerol and phosphatidylethanolamine. Based on the data from phenotypic tests and genotypic differences between strain 17Sr1-39T and its close phylogenetic relatives, strain 17Sr1-39T represented a new species belonging to the genus Methylobacterium , for which the name Methylobacterium terricola sp. nov. (=KACC 52905T=NBRC 112874T) is proposed.

Kim, Y.B., Kim, J.Y., Song, H.S., Lee, S.H., Shin, N.-R., Bae, J.-W., Myoung, J., Lee, K.-E., Cha, I.-T., Rhee, J.-K., Roh, S.W., 2020. Haloplanus rubicundus sp. nov., an extremely halophilic archaeon isolated from solar salt. Systematic and Applied Microbiology 43, 126085.


Two extremely halophilic archaea strains, CBA1112T and CBA1113, were isolated from solar salt in Korea. The genome sizes and G + C content of CBA1112T and CBA1113 were 3.77 and 3.53 Mb, and 66.0 and 66.5 mol%, respectively. Phylogenetic analysis based on closely related taxa and environmental Haloplanus sequences indicated that both CBA1112T and CBA1113 strains are grouped within the genus Haloplanus. OrthoANI and in silico DNA–DNA hybridization values were below the species delineation threshold. Pan-genomic analysis showed that the two novel strains and four reference strains had 6203 pan-orthologous groups in total. Six Haloplanus strains shared 1728 core pan-genome orthologous groups, which were mainly associated with amino acid transport and metabolism and translation, ribosomal structure and biogenesis categories, and amino acid metabolism and carbohydrate metabolism related categories. The novel strain-specific pan-genome orthologous groups were mainly involved with replication, recombination and repair category and replication and repair pathway or amino acid metabolism pathway. Cells of both strains were Gram-negative and pleomorphic, and colonies were red-pigmented. The major polar lipids of both strains were phosphatidylglycerol, phosphatidylglycerol phosphate methyl ester, phosphatidylglycerol sulfate, and one glycolipid, sulfated mannosyl glucosyl diether. Based on genomic, phylogenetic, phenotypic, and chemotaxonomic features, strains CBA1112T and CBA1113 are described as novel species of the genus Haloplanus. Thus, we propose the name Haloplanus rubicundus sp. nov. The type strain is CBA1112T (=KCCM 43224T = JCM 30475T).

Kireeva, T.A., Bychkov, A.Y., Zubkov, M.Y., 2020. The specific features of the microcomponent composition of pore solutions in the rocks of the Bazhenov Formation, Western Siberia. Moscow University Geology Bulletin 75, 47-57.

https://doi.org/10.3103/S0145875220010068

The results of experimental studies of the macrocomponent and microcomponent compositions of pore solutions in the bituminous siliceous shales of the Bazhenov Formation (BF) in Western Siberia with total organic carbon (TOC) contents up to 12.63% (“normal rocks”) and the silty sandstones of the “anomalous” section of the BF with TOC contents no higher than 0.63% (“anomalous” rocks) are presented. The studies of water extracts from core samples were performed. It was found that the pore solutions in the rocks of the “normal” BF rocks are sodium sulfate–bicarbonate, whereas the solutions in the “anomalous” rocks are sodium bicarbonate–chloride. The following tendencies were noted in the pore solutions of both “normal” and “anomalous” rocks compared with the oceanic water: (a) increase in Mn, Co, Ni, Cu, Zn, Mo, Sb, Cd, Ba, V, and Cr concentrations to varying degrees; (b) elevated Cs, Pb, and Ti concentrations in pore solutions of “anomalous” rocks only; (c) reduced Li, B, Rb, and Sr concentrations. A direct correlation between Li, B, Ba, Sr, U, Mo, Cd, Sb, and Ni concentrations in the pore water and total organic carbon (TOC) contents in the rocks was established. The concentrations of V, Cs, Sb, Rb, Ti, and Mn in pore waters display a close to inverse correlation with TOC content in rocks. The content of Ba in the pore solutions of the “normal” BF rocks equals or exceeds the Sr content, which is abnormal compared with formation water in most oil fields and with ocean water and is attributable to the specific features of organic-rich mudstone

accumulation, considering that the Sr content in the “anomalous” rocks of the BF is two times higher than the Ba content, which is closer to their usual ratios in most natural waters.

Kitahashi, T., Sugime, S., Inomata, K., Nishijima, M., Kato, S., Yamamoto, H., 2020. Meiofaunal diversity at a seamount in the Pacific Ocean: A comprehensive study using environmental DNA and RNA. Deep Sea Research Part I: Oceanographic Research Papers 160, 103253.


In deep-sea environments, which have low densities of large benthic animals, meiofauna are a useful indicator of biodiversity. However, in low-latitudes and in low-productivity areas, meiofaunal density is low, but is higher than that of megafaunal or macrofaunal density. Therefore, it is difficult to collect a sufficient number of specimens for statistical analysis. In addition, because faunal classification has been based on conventional microscopic observations, the use of meiofauna to estimate biodiversity in deep-sea environments is time-consuming. However, metabarcoding analyses focused on environmental DNA (eDNA) or RNA (eRNA) have recently been used to examine deep-sea eukaryotic diversity and communities. Here, we examined meiofaunal assemblages using microscopic, eDNA-, and eRNA-based methods at Xufu Guyot (JA06 Seamount), off the southeastern coast of Minami-Torishima Island in the North Pacific Ocean. Microscopic analysis failed to detect a significant difference in diversity or community structure between the seamount terrace and base. This was likely because of the low abundance of meiofauna, which was caused by the low surface productivity at the study area. However, eDNA/eRNA-based metabarcoding analyses revealed spatial variations in diversity and community structures within a single seamount. Therefore, metabarcoding analysis might be useful to elucidate meiofaunal assemblages in areas with low productivity and low faunal density.

Knoll, A.H., Germs, G.J.B., Tankard, A., Welsink, H., 2020. Tonian microfossils from subsurface shales in Botswana. Precambrian Research 345, 105779.


Shale samples recovered from the Masetlheng Pan-1 well, drilled in western Botswana, contain abundant, moderately well preserved, and modestly diverse microfossils. The fossils are assigned to eleven taxa, several reported for the first time from Africa. Distinctive acritarch taxa suggest a late Tonian age for the thick siliciclastic succession that lies unconformably beneath sandstones of the upper Ediacaran-lower Cambrian Nama Group. Masetlheng Pan-1 rocks, therefore, record the major events of Damara sedimentation and tectonics, hidden beneath surficial sands of western Botswana.

Kopylova, M.G., Tso, E., Ma, F., Liu, J., Pearson, D.G., 2019. The metasomatized mantle beneath the North Atlantic Craton: Insights from peridotite xenoliths of the Chidliak kimberlite province (NE Canada). Journal of Petrology 60, 1991-2024.

https://doi.org/10.1093/petrology/egz061

We studied the petrography, mineralogy, thermobarometry and whole-rock chemistry of 120 peridotite and pyroxenite xenoliths collected from the 156 - 138 Ma Chidliak kimberlite province (Southern Baffin Island). Xenoliths from pipes CH-1, -6, -7 and -44 are divided into two garnet-

bearing series, dunites-harzburgites-lherzolites and wehrlites – olivine pyroxenites. Both series show widely varying textures, from coarse to sheared, and textures of late formation of garnet and clinopyroxene. Some samples from the lherzolite series may contain spinel, while wehrlites may contain ilmenite. In CH-6, rare coarse samples of the lherzolite and wehrlite series were derived from P = 2.8-5.6 GPa, while predominant sheared and coarse samples of the lherzolite series coexist at P = 5.6-7.5 GPa. Kimberlites CH-1, -7, -44 sample mainly the deeper mantle, at P = 5.0-7.5 GPa, represented by coarse and sheared lherzolite and wehrlite series. The bulk of the pressure-temperature arrays defines a thermal state compatible with 35-39 mW/m2 surface heat flow, but a significant thermal disequilibrium was evident in the large isobaric thermal scatter, especially at depth, and in the low thermal gradients uncharacteristic of conduction. The whole rock Si and Mg contents of the Chidliak xenoliths and their mineral chemistry reflects initial high levels of melt depletion typical of cratonic mantle and subsequent refertilization in Ca and Al. Unlike the more orthopyroxene-rich mantle of many other cratons, the Chidliak mantle is rich (∼83 vol.%) in forsteritic olivine. We assign this to silicate-carbonate metasomatism, which triggered wehrlitization of the mantle. The Chidliak mantle resembles the Greenlandic part of the North Atlantic Craton suggesting the former contiguous nature of their lithosphere before subsequent rifting into separate continental fragments. Another, more recent type of mantle metasomatism, which affected the Chidliak mantle, is characterized by elevated Ti in pyroxenes and garnet typical of all rock types from CH-1, -7 and -44. These metasomatic samples are largely absent from the CH-6 xenolith suite. The Ti imprint is most intense in xenoliths derived from depths equivalent to 5.5 to 6.5 GPa where it is associated with higher strain, the presence of sheared samples of the lherzolite series and higher temperatures varying isobarically by up to 200 °C. The horizontal scale of the thermal-metasomatic imprint is more ambiguous and could be as regional as 10 s of kilometers or as local as < 1 km. The time-scale of this metasomatism relates to a conductive length-scale and could be as short as < 1 Myr, shortly predating kimberlite formation. A complex protracted metasomatic history of the North Atlantic Craton reconstructed from Chidliak xenoliths matches emplacement patterns of deep CO2-rich and Ti-rich magmatism around the Labrador Sea prior to the craton rifting. The metasomatism may have played a pivotal role in thinning the North Atlantic Craton lithosphere adjacent to the Labrador Sea from ∼240 km in the Jurassic to ∼65 km in the Paleogene.

Kotarba, M.J., Bilkiewicz, E., Więcław, D., Radkovets, N.Y., Koltun, Y.V., Kowalski, A., Kmiecik, N., Romanowski, T., 2020. Origin and migration of oil and natural gas in the central part of the Ukrainian outer Carpathians: Geochemical and geological approach. American Association of Petroleum Geologists Bulletin 104, 1323-1356.


The generation and migration processes, as well as the influence of secondary processes, on oil and natural gas accumulated in Lower Cretaceous–lower Miocene strata of the central part of the Ukrainian outer Carpathians are discussed. Type II and II/III kerogens from the Oligocene–lower Menilite beds of the Boryslav-Pokuttya nappe generated oil and natural gas mainly during the middle stage of the oil window. These hydrocarbons accumulated in the fields of the Boryslav-Pokuttya and Skiba nappes. Water washing is the dominant secondary process occurring in many accumulations, regardless of reservoir rock, whereas biodegradation is insignificant and is clearly evident only in natural gas from one seep in the abandoned Starunia ozocerite mine. All hydrocarbon gases are thermogenic and were generated from mixed organic matter containing various proportions of type II and III kerogens. Only one natural gas accumulation in the Pivnichna

Dolyna field contains some microbial hydrocarbon contribution. Carbon dioxide mainly originated from thermogenic kerogen decarboxylation and sporadically from microbial processes. Molecular nitrogen was mainly generated during low-temperature thermal transformation of organic matter and could also partly originate from NH4-rich illites of the clayey facies of the Oligocene–lower Miocene Menilite beds. The integration of the geochemical data with geological setting and maturation history of source rocks enabled us to reconstruct hydrocarbon migration paths, revealing the complicated trap-filling process.

Kraemer, G., Camps-Valls, G., Reichstein, M., Mahecha, M.D., 2020. Summarizing the state of the terrestrial biosphere in few dimensions. Biogeosciences 17, 2397-2424.


In times of global change, we must closely monitor the state of the planet in order to understand the full complexity of these changes. In fact, each of the Earth's subsystems – i.e., the biosphere, atmosphere, hydrosphere, and cryosphere – can be analyzed from a multitude of data streams. However, since it is very hard to jointly interpret multiple monitoring data streams in parallel, one often aims for some summarizing indicator. Climate indices, for example, summarize the state of atmospheric circulation in a region. Although such approaches are also used in other fields of science, they are rarely used to describe land surface dynamics. Here, we propose a robust method to create global indicators for the terrestrial biosphere using principal component analysis based on a high-dimensional set of relevant global data streams. The concept was tested using 12 explanatory variables representing the biophysical state of ecosystems and land–atmosphere fluxes of water, energy, and carbon fluxes. We find that three indicators account for 82 % of the variance of the selected biosphere variables in space and time across the globe. While the first indicator summarizes productivity patterns, the second indicator summarizes variables representing water and energy availability. The third indicator represents mostly changes in surface albedo. Anomalies in the indicators clearly identify extreme events, such as the Amazon droughts (2005 and 2010) and the Russian heat wave (2010). The anomalies also allow us to interpret the impacts of these events. The indicators can also be used to detect and quantify changes in seasonal dynamics. Here we report, for instance, increasing seasonal amplitudes of productivity in agricultural areas and arctic regions. We assume that this generic approach has great potential for the analysis of land surface dynamics from observational or model data.

Lahme, S., Callbeck, C.M., Eland, L.E., Wipat, A., Enning, D., Head, I.M., Hubert, C.R.J., 2020. Comparison of sulfide-oxidizing Sulfurimonas strains reveals a new mode of thiosulfate formation in subsurface environments. Environmental Microbiology 22, 1784-1800.

https://doi.org/10.1111/1462-2920.14894

Sulfur oxidizing ‐ Sulfurimonas spp. are widespread in sediments, hydrothermal vent fields, aquifers and subsurface environments such as oil reservoirs where they play an important role in the sulfur cycle. We determined the genome sequence of the oil field isolate Sulfurimonas sp. strain CVO and compared its gene expression during nitrate dependent sulfide oxidation to the coastal sediment ‐isolate Sulfurimonas denitrificans . Formation of elemental sulfur (S0) and high expression of sulfide quinone oxidoreductase (SQR) genes indicates that sulfide oxidation in both strains is mediated by SQR. Subsequent oxidation of S0 was achieved by the sulfur oxidation enzyme complex (SOX). In the

coastal S. denitrificans , the genes are arranged and expressed as two clusters: soxXY 1 Z 1 AB and soxCDY 2 Z 2 H , and sulfate was the sole metabolic end product. By contrast, the oil field strain CVO has only the soxCDY 2 Z 2 H cluster and not soxXY 1 Z 1 AB . Despite the absence of the soxXY 1 Z 1 AB cluster, strain CVO oxidized S0 to thiosulfate and sulfate, demonstrating that soxCDY 2 Z 2 H genes alone are sufficient for S0 oxidation in Sulfurimonas spp. and that thiosulfate is an additional metabolic end product. Screening of publicly available metagenomes revealed that Sulfurimonas spp. with only the soxCDY 2 Z 2 H cluster are widespread suggesting this mechanism of thiosulfate formation is environmentally significant.

Landsman-Gerjoi, M., Perdrial, J.N., Lancellotti, B., Seybold, E., Schroth, A.W., Adair, C., Wymore, A., 2020. Measuring the influence of environmental conditions on dissolved organic matter biodegradability and optical properties: a combined field and laboratory study. Biogeochemistry 149, 37-52.

https://doi.org/10.1007/s10533-020-00664-9

Fluorescence spectroscopy is a common tool to assess optical dissolved organic matter (DOM) and a number of characteristics, including DOM biodegradability, have been inferred from these analyses. However, recent findings on soil and DOM dynamics emphasize the importance of ecosystem-scale factors, such as physical separation of substrate from soil microbial communities and soil physiochemical cycles driving DOM stability. We apply this principle to soil derived DOM and hypothesize that optical properties can only supply information on biodegradability when evaluated in the larger ecosystem because substrate composition and the activity/abundance of the microbial community ultimately drive DOM degradation. To evaluate biodegradability in this context, we assessed aqueous soil extracts for water extractable organic carbon (WEOC) content, biodegradability, microbial biomass and DOM characteristics using fluorescence spectroscopy across a range of environmental conditions (covariant with season and land use) in northern Vermont, USA. Our results indicate that changes in environmental conditions affect composition, quantity, and biodegradability of DOM. WEOC concentrations were highest in the fall and lowest in the summer, while no significant differences were found between land covers; however, DOM biodegradability was significantly higher in the agricultural site across seasons. Despite a shift in utilized substrate from less aromatic DOM in summer to more aromatic DOM in winter, biodegradability was similar for all seasons. The only exception was cold temperature incubations where microbial activity was depressed, and processing was slowed. These results provide examples on how fluorescence based metrics can be combined with context relevant environmental parameters to evaluate bioavailability in the context of the larger ecosystem.


https://doi.org/10.1007/s11430-019-9571-2

Membrane lipids are thought to be a crucial part of the homeoviscous adaptation of archaea to extreme conditions. This article reviews the recent lipidomic studies of physiological membrane adaptations of archaea, assesses the biomolecular basis of an organic paleothermometer, TEX86, and contemplates the future directions of archaeal lipidomics. The studies of extremophilic archaea have

revealed that at least three different molecular mechanisms are involved in membrane adaptation of archaea: (1) regulation of the number of cyclopentane rings of caldarchaeol, (2) alteration of the diether-to-tetraether lipid ratio, and (3) variation of the proportion of saturated and unsaturated lipids. However, most of the studies have focused on a limited number of archaeal ether-linked lipids, such as glycerol dialkyl glycerol tetraethers (GDGTs), which only represent a fraction of the entire lipidome. Environmental factors such as growth temperature and pH have been most frequently reported, but biotic factors, including growth phases, nutrition, and enzymatic activities affecting the membrane lipid composition are often overlooked. Membrane lipids of mesophilic ammonia-oxidizing marine Thaumarchaeota have been applied in the reconstruction of past sea surface temperatures. However, recent culture-based physiological studies have demonstrated that non-thermal biotic factors, including dissolved oxygen, ammonia oxidation rate and the growth rate, are the main drivers of GDGT cyclization in Nitrosopumilus maritimus. Moreover, other related strains or ecotypes exhibit a markedly different set of stress adaptations. A trend is now developing to examine the whole lipid profile (lipidome) for studies of archaeal physiology and biochemistry related to lipid biosynthesis (lipidomics) to gain a better understanding of the biological mechanisms underpinning the applications of membrane lipid-based proxies in biogeochemical or ecological research.

Le Mer, G., Barthod, J., Dignac, M.-F., Barré, P., Baudin, F., Rumpel, C., 2020. Inferring the impact of earthworms on the stability of organo-mineral associations, by Rock-Eval thermal analysis and 13C NMR spectroscopy. Organic Geochemistry 144, 104016.


Stabilization of organic matter (OM) against decomposition and its de-stabilization leading to mineralization, are important processes in the control of greenhouse gas emissions and carbon sequestration in soils. Soil organisms, particularly earthworms, may influence these processes greatly through their potential impacts on the interaction of OM with clay minerals, which is a mechanism which may protect OM for medium (years) to long (decades, centuries) time scales. The aim of this study was to use earthworms and pure minerals in order to investigate enhancement of carbon sequestration through the formation of aggregates containing particulate OM and organo-mineral associations, during a composting experiment. To this end we compared OM transformations in composting treatments with and without (i) clay minerals (montmorillonite) and (ii) epigeic earthworms (Eisenia andrei and Eisenia foetida). We used density fractionation of the end-products to quantify the amount of aggregates, including organo-mineral associations, formed during 196 days. Chemical composition and stability were examined by elemental analyses, Rock-Eval 6 thermal analysis and solid-state 13C nuclear magnetic resonance (NMR) spectroscopy.

The results indicated that the addition of minerals led to the formation of heavy fractions, most probably containing aggregates and organo-mineral associations, in treatments with and without earthworms. While OM showed higher oxidative transformation in all treatments, addition of earthworms changed organic carbon (OC) and nitrogen (N) concentrations in specific density fractions and increased the thermal stability of OM in heavy density fractions. These fractions contained higher proportions of aromatic and proteinaceous materials. We conclude that, earthworms under composting conditions, earthworms may be able to effectively to stabilize OM through the formation of aggregates and/or organo-mineral associations containing greater proportions of microbially-derived material.

Leifeld, J., Klein, K., Wüst-Galley, C., 2020. Soil organic matter stoichiometry as indicator for peatland degradation. Scientific Reports 10, 7634.

https://doi.org/10.1038/s41598-020-64275-y

Peatlands accumulate organic matter (OM) under anaerobic conditions. After drainage for forestry or agriculture, microbial respiration and peat oxidation induce OM losses and change the stoichiometry of the remaining organic material. Here, we (i) evaluate whether land use (cropland CL, grassland GL, forest FL, natural peatland NL) is associated with different peat stoichiometry, (ii) study how peat stoichiometry changes with OM content and (iii) infer the fate of nitrogen upon soil degradation. Organic C and soil N were measured for 1310 samples from 48 sites in Switzerland, and H and O for 1165. The soil OM content and C/N ratio were most sensitive to land use and are hence best suited as indicators for peatland degradation. OM contents (CL < GL < FL < NL), H/C, O/C, C/N ratios, and OM oxidation states were significantly different between land use types in top- and subsoils. With decreasing bulk OM content, C was relatively depleted while H and particularly N were higher. The data suggest very high N mobilization rates from strongly decomposed peat in agricultural topsoil. A comparison to peat C and N from mostly intact peatlands of the Northern hemisphere reveals that agriculture and, to a lesser extent, forestry induce a progressed state of soil degradation.



The hadal trenches (>6000 m) are considered to be ultimate sinks of organic carbon (OC) from biosphere. However, highly spatial heterogeneity of geographic background and organic matter in different zones make significant influences on the OC cycling, and further the carbon burial. In this study, three sediment cores were drilled across the northern Yap Trench axis (9.8–9.9°N, 138.3–138.7°E). The elemental compositions, stable carbon isotopes of organic matter, mineral-specific surface area, and grain size composition were analyzed to investigate the spatial variations of organic sources, distribution, and its degradation in the northern Yap Trench. The surface sedimentary OC (SOC) contents in the northern Yap Trench increase from 0.25% at abyssal depth (4435 m) to 0.50% at hadal depth (~6674 m). Higher OC content (0.27% ± 0.08%) and sedimentation rate (5.8 cm kyr−1) occur in the station on the gradual oceanward slope (~4.2°) compared to those on the steep landward slope (~10°) (0.17% ± 0.13%, 0.52–1.8 cm kyr−1), suggesting enhanced accumulation of OC on the gradual slope. The allochthonous OC (i.e. marine phytoplankton-derived (55% ± 7%) and terrestrial (16% ± 8%)) dominates the SOC pool on the oceanward slope, whereas autochthonous microbe reworked OC contributes more than 50% in the steep landward slope, based on the evaluation of a three-end-member mixing model using δ13C composition and OC/N ratios as source markers. Correspondingly, radiocarbon age of SOC in the gradual slope is ~700 years younger than that in the steep slope with similar depth, indicating that the relatively fresh allochthonous OC is selectively deposited on the gradual slope. A multi-G degradation model demonstrates that OC degradation rates in the northern Yap Trench range from 0.00015 yr−1 to 0.00068 yr−1, which can be comparable with abyssal plain (3000–6000 m) and are lower than those of neritic environments (<1000 m). Mass accumulation model calculation shows that accumulation rate of surface OC in the northern Yap trench is ~2.7 × 10−2 g C m−2 yr−1, much lower than those from

other deep ocean seafloors. This study suggests an inefficient SOC preservation within the northern Yap Trench, which might be induced by high labile marine phytoplankton-derived OC inputs and active heterotrophic microbial activity, and the results have important implications for better understanding the effects of sediment dynamics on OC cycling in hadal zones.

Li, F., Guo, S., Wang, S., Zhao, M., 2020. Changes of microbial community and activity under different electric fields during electro-bioremediation of PAH-contaminated soil. Chemosphere 254, 126880.


Electro-bioremediation is a promising technology for remediation of soil contaminated with persistent organic compounds such as polycyclic aromatic hydrocarbons (PAHs). During electro-bioremediation, electrical fields have been shown to increase pollutant degradation. However, it remains unclear whether there is an optimal strength for the electrical field applied that is conductive to the maximum role played by microbes. This study aimed to determine the optimal strength of electric field through the analysis of the effects of different voltages on the microbial community and activity. Four bench-scale experiments with voltages of 0, 1, 2 and 3 V cm−1 were conducted for 90 days in an aged PAH-contaminated soil. The spatiotemporal changes of the soil pH, moisture content and temperature, microbial biomass and community structure, and the degradation extent of PAHs were researched over 90 days. The results indicated that the total microbial biomass and degradation activity were highest at voltages of 2 V cm−1. The concentration of total phospholipid fatty acids, used to quantify soil microbial biomass, reached 65.7 nmol g−1 soil, and the mean degradation extent of PAHs was 44.0%. Similarly, the maximum biomass of actinomycetes, bacteria and fungus also occurred at the voltage of 2 V cm−1. The Gram-positive/Gram-negative and (cy17:0+cy 19:0)/(16:1ω7+18:1ω7) ratios also showed that the intensity of electric field and electrode reactions strongly influenced the microbial community structure. Therefore, to optimize the electro-bioremediation of PAH-contaminated soil, the strength of electric field needs to be selected carefully. This work provides reference for the development of novel electrokinetically enhanced bioremediation processes.

Li, H.-X., Xie, T.-P., Xie, S.-M., Wang, B.-J., Zhang, J.-H., Yuan, L.-M., 2020. Enantiomeric separation on a homochiral porous organic cage-based chiral stationary phase by gas chromatography. Chromatographia 83, 703-713.

https://doi.org/10.1007/s10337-020-03895-y

Porous organic cages (POCs) are an emerging class of porous molecular materials which self-assembled by discrete, shape-persistent, cage-like molecules and have recently received intensive interest in diverse fields. In this work, a hydroxyl-functionalized homochiral POC was synthesized by [4 + 6] condensation of 2-hydroxy-1,3,5-triformylbenzene with (1R, 2R)-diaminocyclohexane and coated on a capillary column for gas chromatography (GC) separations. Forty-one pairs of enantiomers belonging to various classes have been resolved on the column, including alcohols, diols, esters, lactones, halohydrocarbons, ethers, epoxides, ketones and sulfoxides. Compared with β-cyclodextrin derivative-based commercial β-DEX 120 column, previously reported chiral POCs- (CC9 and CC10) based columns, there are 12, 27 and 19 pairs of studied enantiomers cannot be resolved on β-DEX 120 column, CC9 column and CC10 column, respectively. Besides, both separation factors and resolution values of some racemates are higher on this column than those on β-DEX 120

column, CC9 column and CC10 column. The results demonstrate that the column exhibits good chiral recognition complementarity or superior chiral resolution capability to those columns which used for comparison, and the introduction of hydroxyl group enhances hydrogen-bonding interaction to some racemates, leading to better enantioselectivity. The column also shows excellent separation performance toward positional isomers of dichlorobenzene, dibromobenzene, nitrotoluene, chlorotoluene, nitrobromobenzene and nitrochlorobenzene. The retention time and selectivity of analytes have no significant changes after more than 500 injections and 260 °C conditioned for 6 h, showing the good repeatability and thermal stability of the column. This work indicates the promising prospect of POCs for GC separation, especially for the separation of enantiomers and also demonstrates the significance of design and synthesis of more functionalized chiral POCs for GC enantioseparation that broaden the enantiomer separation scope and applicability of POCs-based columns through their chiral recognition complementarities.



High-resolution mass spectrometry enables molecular characterization of heavy petroleum fractions for petroleomics research. However, results from mass spectrometry are usually not quantitative. This paper provides strategies and solutions for obtaining quantitative analysis of a heavy petroleum fraction. The fluid catalytic cracking (FCC) slurry decant oil and its fractions were characterized by high-resolution Orbitrap mass spectrometry with various ionization techniques, such as positive- and negative-ion electrospray ionization, positive-ion atmospheric pressure photoionization, and chemical derivatizations. Molecular compositions obtained from various methods were combined and normalized using elemental composition of the FCC decant oil and its fractions. More than 7000 molecules of 20 class species were assigned and quantified. Aromatic hydrocarbon was the most abundant, accounting for 49.6 wt % of FCC decant oil. The non-basic N1O3 class species had a minimum content of 0.03 wt %. The concentration-assigned molecules ranged from 2.0 × 10–3 to 2.1 × 104 wppm for C22H15N2 to C18H12, respectively.



Using supercritical CO2 as a fracturing or heat exchange medium can not only improve the thermal recovery efficiency of geothermal energy but can also store CO2 and reduce CO2 emissions. The pore structure characteristics are important factors affecting the permeability of the dry-hot rock (granite in this study), as well as the key parameters to predict any induced earthquakes. However, the influence of supercritical CO2 on the pore structure of granite is not clear. In this study, nuclear magnetic resonance, X-ray diffraction, and scanning electron microscopy were performed to study the effects of supercritical CO2 saturation on the granite over time. The results showed that many new dissolution pores are found on the surface of calcite after supercritical CO2 saturation, and the formation of secondary minerals can also be observed. The crystallinity of granite mineral particles decreased after supercritical CO2 saturation. In addition, the proportion of micropores increased,

while the proportion of mesopores and macropores decreased compared to the unexposed granite. Supercritical CO2 saturation improved the connectivity among micropores, mesopores, and macropores, and longer saturation times in supercritical CO2 led to stronger microscopic heterogeneity in the granite. Furthermore, ultrasonic wave velocity results showed that the granite was damaged by the supercritical CO2 saturation. In the early stage of supercritical CO2 saturation, the damage coefficient of granite developed rapidly. With the increase of the saturation time, the damage coefficient of granite remained stable.

Li, J., Hao, C., Wang, Z., Dong, L., Wang, Y., Huang, K.-J., Lang, X., Huang, T., Yuan, H., Zhou, C., Shen, B., 2020. Continental weathering intensity during the termination of the Marinoan Snowball Earth: Mg isotope evidence from the basal Doushantuo cap carbonate in South China. Palaeogeography, Palaeoclimatology, Palaeoecology 552, 109774.


The Neoproterozoic global glaciations (720–635 Ma) represent the most severe icehouse climatic conditions in Earth's history, collectively known as the ‘Snowball Earth events’. The ‘Snowball Earth’ hypothesis (Hoffman et al. 1998) proposed that the termination of the global glaciation was driven by the extremely high atmospheric pCO2 level (300 times of present atmospheric level, PAL) that was accumulated during the global glaciation by volcanic degassing for tens of million years. Because of extremely high temperature, the deglaciation might associate with intense continental weathering that brought abundant bicarbonate and alkaline earth metals (Mg, Ca) to the ocean, resulting in the rapid precipitation of cap carbonate all over the world. Thus, cap carbonate precipitation marks the termination of global glaciation. The deglacial intense continental weathering has been recently supported by Mg isotopes. However, the Mg isotope data also indicate that the deglaciation might have significantly predated the cap carbonate precipitation, and limited data suggest that the weathering intensity was already low during the cap carbonate precipitation. In order to further test whether the cap carbonate precipitation was associated with low weathering intensity, here we analyzed Mg isotopic composition of siliciclastic component (δ26Mgsil) of the Doushantuo cap carbonate in the Yangtze Block, South China. Four cap carbonate sections (the Tongle (TL) drill core, the Fanyang (FY) section, the Wuluo (WL) drill core, and the Jiulongwan (JLW) section), spanning from shelf to basin environments, were analyzed. δ26Mgsil ranges from −0.43‰ to +0.39‰ (n = 10), from −0.31‰ to +0.48‰ (n = 9), from −0.06‰ to +0.10‰ (n = 7), and from −1.42‰ to −0.03‰ (n = 8) for the JLW, FY, WL, and TL samples, respectively. There are negative correlations between Mg/Al and δ26Mgsil in JLW, WL, and TL. The geochemical data indicate that the variation of δ26Mgsil might be attributed to authigenic clay formation during the cap carbonate precipitation. The binary mixing model indicates that the isotopic compositions of terrestrial clays range from 0‰ to +0.3‰, comparable to the values of modern soil clays but significantly lower than the values of the upper Nantuo Formation (up to ~ + 0.90‰), suggesting the moderate to low weathering intensity during the cap carbonate deposition. Our study suggests low atmospheric pCO2 level during cap carbonate precipitation probably due to the consumption by intense continental weathering.



An Achromobacter species strain AC15 was isolated from mangrove soil and identified as a potent producer of biosurfactant. It could utilize high concentrations of pyrene as the sole source of carbon and energy. Results showed that AC15 degraded about 40% of the pyrene, which was provided at an initial concentration of 300 mg L−1, and reduced surface tension of the culture medium from 67.2 to 33.2 mN m−1 after 14 d of incubation using its good emulsification property on the culture medium. The main chemical component of partially purified biosurfactant, namely BS15, was analyzed by gas chromatography-mass spectrometry, amino acid analysis, and LTQ Orbitrap Elite mass spectrometry. Results showed that BS15 was a novel linear lipopeptide with a long-chain C16 fatty acid and peptide comprised of four amino acid residues. The molecular structure was determined as CH3-(CH2)14–CO–O-Leu-Asp-Lys-Ser. The solubility of pyrene in water improved 1.5–1.9 times in the presence of 40–60 mg L−1 of BS15. This work demonstrated that strain AC15 and its biosurfactant BS15 could be potential candidates in further applications of bioremediation of high-molecular weight polycyclic aromatic hydrocarbons.

Li, K., Li, L., Aubaud, C., Muehlenbachs, K., 2020. Efficient carbon recycling at the central-northern Lesser Antilles arc: Implications to deep carbon recycling in global subduction zones. Geophysical Research Letters 47, e2020GL086950.

https://doi.org/10.1029/2020GL086950

Abstract: Carbon recycling efficiency of arc (CREA) is an important parameter to assess the recycling of slab carbon into Earth's deep interior. Although previous studies observed variable degrees of recycled slab carbon at global arcs, the CREA value of any individual subduction zone has not been obtained due to the loose constraints on carbon budget in altered oceanic crust (AOC). Here, through estimates of carbon input by both sediments and AOC at DSDP Site 543 and recycled carbon output from major volcanoes in the Central Northern Lesser Antilles, we show an extremely efficient‐ carbon recycling case, with the CREA value reaching 100±27%. Nearly complete slab carbon release at sub arc depth implies little carbon has been lost in the forearc region or subducted into the deep ‐mantle in this subduction zone. Our results highlight strongly variable CREA on a global scale, which must be considered in the modeling of global deep carbon cycle.

Plain Language Summary: Subduction zones are the major channel to deliver crustal carbon into the mantle. However, the fate of crustal carbon at a variety of depth (e.g., forearc, sub arc, beyond arc) ‐in the subduction channel is poorly quantified, which is an obstacle to our understanding of the deep carbon cycle. Here, we assessed the carbon recycling efficiency in the Central Northern Lesser ‐Antilles arc by comparing the carbon input flux (estimated from data of the subducting slab recovered by DSDP drillings) with carbon output flux (estimated based on volcanic emission data). We found that the subducted crustal carbon was nearly completely recycled by arc volcanism in the Central Northern Lesser Antilles. This implies little carbon loss within the forearc region and little ‐carbon subducted into the deep mantle in the Central Northern Lesser Antilles, which differs from ‐some other subduction zones (e.g., the Izu Bonin Mariana and Central America) that show low ‐ ‐carbon recycling efficiencies. Our discovery highlights that the carbon recycling in subduction zone is highly variable on a global scale.

Li, Q., Jew, A.D., Brown, G.E., Bargar, J.R., Maher, K., 2020. Reactive transport modeling of shale–fluid interactions after imbibition of fracturing fluids. Energy & Fuels 34, 5511-5523.


Injection of hydraulic fracturing fluid (HFF) into shale formations for unconventional oil/gas production results in chemical reactions in the shale matrix. Our recent experimental study determined the depths to which different types of reactions between the shale matrix and the HFF extended. In the present study, we built continuum-scale reactive transport models to understand the coupling of chemical reactions and the transport of aqueous species in these shale–HFF systems. Calibration of the model with our previous experimental results reveals that it takes hours to months for the shale matrix to completely neutralize the imbibed acids, depending primarily upon the carbonate content of the shale. Both the HFF pH and pore pH affect the location of barite precipitation, resulting in unique barite precipitation profiles extending millimeters into calcite-rich Eagle Ford shale but only tens of micrometers into low-carbonate Marcellus shale. In addition, dissolved oxygen and extracted bitumen are key to reproducing the experimental observation of Fe(III) (oxyhydr)oxide formation in the shale matrix as a result of pyrite dissolution in the shales. A comparison between the modeling results of porosity in the present study to experimentally measured permeabilities in our previous study suggests that chemical reactions occurring at a greater depth than the observable reaction zone might have impacted permeability. Our model serves as a benchmark for efficiently modeling water–rock interactions in similar systems where bulk rock samples react with a solution in batch reactors. Important reactive transport processes were ascertained via modeling, which allows for quantitative prediction of shale–HFF interactions in shale matrices given the shale and HFF compositions.

Li, S., Jackson, M.D., Agenet, N., 2020. Role of the calcite-water interface in wettability alteration during low salinity waterflooding. Fuel 276, 118097.


Wettability alteration has been widely accepted as the key process for enhanced oil recovery during controlled salinity waterflooding. However, the decisive mechanism causing wettability alteration, particularly for crude-oil-brine-carbonate-rock systems, is not fully understood. Zeta potential is a key electrochemical parameter for the mineral-brine interface and is sensitive to physicochemical changes at the interface. In this study, we conducted core-flooding tests integrated with zeta potential measurements to characterize changes in wettability, oil recovery and zeta potential on two carbonate rock samples, Carbonate-I and Carbonate-II, comprised of close to pure calcite. Following the same coreflooding protocol with the same crude oil and flooding brine compositions, the two samples showed different behaviour. Incremental oil recovery during controlled (low) salinity waterflooding was observed in the oil-brine-Carbonate-II system (8% incremental oil recovery) but there was no response for the Carbonate-I system. The zeta potential of the Carbonate-I and Carbonate-II samples also showed different behaviour in high salinity formation brine, with Carbonate-I returning a positive zeta potential, consistent with previous published measurements, but Carbonate-II returning an anomalously negative value. We suggest that the different zeta potential and EOR behaviour is most likely caused by the different proportions of crystal faces and edges in each sample that are exposed to brine. The low permeability Carbonate-II sample contains nanoscale pores and the edges of the calcite crystals are the dominant surface in contact with brine. Our results suggest that textural variations in natural carbonates control calcite-brine interfacial properties and the behaviour during controlled salinity waterflooding.



In order to determine whether sulfides are major reservoirs for Mo in the upper continental crust (UCC), we determined the composition and mode of occurrence of sulfides and evaluated their contribution to the molybdenum budget in twelve glacial diamictites with ages ranging from 2900 to 300 Ma. The diamictites provide a snapshot of UCC mineralogy and composition at the time of their deposition and show systematic depletion in bulk rock Mo concentrations after the Great Oxidation Event (GOE), reflecting the effects of oxidative weathering in their provenance (Gaschnig et al., 2014; Li et al., 2016). Sulfides are generally confined to Archean and Paleoproterozoic diamictites, although they also have been found in one Phanerozoic sample with an ancient provenance. We classify the sulfides based on their compositions and morphologies. Detrital sulfides are generally rounded, may be a single mineral, or an assemblage of minerals, and show a very wide range in mineralogy, including a single molybdenite grain. Sedimentary sulfides are pyrites, generally with framboidal-like textures. Pyrites also include non-framboidal textured authigenic pyrites. Epigenetic sulfides consist of irregular pyrrhotite aggregates (sometimes pyrrhotite intergrown with chalcopyrite and cobaltite), late-stage euhedral pyrites and pyrite aggregates in veins. High Mo concentrations (up to ∼230 ppm) are found in some sedimentary framboidal-like pyrites from the Mesoarchean Coronation and Paleoproterozoic Makganyene Formations, epigenetic pyrrhotite aggregates and chalcopyrite in the Ramsay Lake diamictite, and in detrital sulfides in Timeball Hill diamictites that may have originated from hydrothermal fluids in the sedimentary basins. Other detrital sulfides have widely variable Mo concentrations (0.5–36 ppm). Mass balance calculations show that sulfides can account for only <8% of the whole rock Mo contents in all glacial diamictites except for the Makganyene Formation, and thus sulfides (including molybdenite) are unlikely to be a significant host of Mo within the UCC before the GOE. In the Makganyene diamictites, ∼37% of whole rock Mo is contained within sulfides, which are predominantly framboidal-like pyrites interpreted to have grown in the matrix at the time of deposition. In these, the Mo contents correlate with the size of the microcrystals: smaller-sized crystals contain significantly higher concentrations than larger-sized crystals, suggesting that rapid nucleation and growth of framboidal pyrites leads to incorporation of large amounts of Mo available in the pore water or Mo expulsion during recrystallization. The presence of Mo in sedimentary pyrites from a pre-GOE deposit – the 2900 Ma Coronation Formation – points to the availability of Mo and S in pre-GOE seawater (and associated pore fluids), and is consistent with previously reported evidence for isolated pulses of atmospheric oxygen and oxidative continental weathering prior to the GOE. However, the lack of significant whole rock Mo depletion in pre-GOE diamictites limits the amount of Mo released from the continents prior to the GOE.

Li, W.-Y., Yu, H.-M., Xu, J., Halama, R., Bell, K., Nan, X.-Y., Huang, F., 2020. Barium isotopic composition of the mantle: Constraints from carbonatites. Geochimica et Cosmochimica Acta 278, 235-243.


To investigate the behaviour of Ba isotopes during carbonatite petrogenesis and to explore the possibility of using carbonatites to constrain the Ba isotopic composition of the mantle, we report

high-precision Ba isotopic analyses of: (1) carbonatites and associated silicate rocks from the only active carbonatite volcano, Oldoinyo Lengai, Tanzania, and (2) Archean to Cenozoic carbonatites from Canada, East Africa, Germany and Greenland. Carbonatites and associated phonolites and nephelinites from Oldoinyo Lengai have similar δ137/134Ba values that range from +0.01 to +0.03‰, indicating that Ba isotope fractionation during carbonatite petrogenesis is negligible. The limited variation in δ137/134Ba values from −0.03 to +0.09‰ for most carbonatite samples suggests that their mantle sources have a relatively homogeneous Ba isotopic composition. Based on the carbonatites investigated in this work, the average δ137/134Ba value of their mantle sources is estimated to be +0.04 ± 0.06‰ (2SD, n = 16), which is similar to the average value of +0.05 ± 0.06‰ for mid-ocean ridge basalts. The lower δ137/134Ba value of −0.08‰ in a Canadian sample and higher δ137/134Ba values of +0.14‰ and + 0.23‰ in two Greenland samples suggest local mantle isotopic heterogeneity that may reflect the incorporation of recycled crustal materials in their sources.

Li, X., Wang, J., Rasbury, T., Zhou, M., Zhang, C., 2020. Early Jurassic climate and atmospheric CO2 concentration in the Sichuan paleobasin, Southwest China. Climate of the Past Discussions 2020, 1-35.


Unlike marine archives, terrestrial sediments show more complicated and dynamic environment and climate. This work presents new results of climate-sensitive sediment observation and carbon-oxygen isotope analyses of lacustrine and pedogenic carbonates for the Early Jurassic Ziliujing Formation from the grand Sichuan paleobasin (GSB), Southwest China. Lithofacies analysis indicates calcisols were widespread in riverine and flood plain facies. Climate–sensitive sediments and carbon-oxygen isotopes with palynofloral assemblages manifest that an overall (semi-) arid climate dominated the GSB; and that it became drier through time, accompanied by occasional evaporites in the Toarcian. This climate pattern is similar with the arid climate in Colorado Plateau, westwen America, but distinct from the relatively warm-humid climate in North China and northern Gondwanaland in Southern Hemisphere. The estimated Early Jurassic atmospheric CO2 concentration (pCO2) from carbon isotopes of pedogenic carbonates shows a range of 980–2610 ppmV (~ 3.5–10 times the pre-industrial value) with a mean 1660 ppmV. Three phases of pCO2 (the Sinemurian 1500–2000 ppmV, the Pliensbachian 1000–1500 ppmV, and the early Toarcian 1094–2610 ppmV) and two events of rapid falling pCO2 by ~ 1000–1300 ppmV are observed, illustrating the pCO2 perturbation in the Early Jurasic. The pattern and associated rapid falling events of pCO2 are compatible with the excursions of stable isotopes and seawater temperature from the coeval marine sediments, consistent with a positive feedback of climate to pCO2 through the Early Jurassic.



Coal bed methane generated thermogenically or biogenically is a significant unconventional natural gas resource. However, assessments of biogenic methane in high-rank coal deposits have been rarely reported. On the basis of geochemical and microbiological investigations of coal reservoir water, this is the first study of the Shizhuangnan block in southern Qinshui Basin, China that

provides an understanding of methanogenic pathways and indigenous microbes. Carbon and hydrogen isotopes indicated that CO2 reduction and acetate fermentation methanogenesis coexisted in the Shizhuangnan block. The 16S rRNA results revealed that native archaea were dominated by Methanobacterium and Methanosarcina that were significantly affected by geochemical factors in the indigenous environment. As microbial consortia, the presence of various fermentative bacteria played a crucial role in coal biodegradation. In particular, sulfate-reducing bacteria competed with methanogens for substrates under relatively high sulfate concentrations. Finally, 16S rRNA sequencing indicated that acetate fermentation methanogenesis was more prevalent than CO2 reduction methanogenesis near the eastern outcrop in the study area.



Biomass-derived pyrolosis oil (aka. Bio-oil) contains high oxygen and other heteroatoms that prevent it from being directly used as a conventional fuel due to its thermal instability, non-volatility and corrosivity. Co-processing the bio-oil with vacuum gas oil (VGO, a petroleum refining feedstock) leverages the existing petroleum refining infrastructure which significantly reduces Capex for the bio-oil pathway. Increasing renewable carbon incorporation into conventional fuels is a critical step in biofuels development and adoption. To take advantage of this approach, a fast, economic and accurate method with a potenial online monitoring capability is needed for tracking the renewable carbon through processing and then using the information to guide optimization of the co-processing parameters to maximize renewable carbon incorporation in fuel products. Here, we have developed a high-precision analytical protocol that enables accurate 13C/12C ratio analysis for bio-oil/crude samples. Our study demonstrates that high-precision 13C/12C ratio analysis can be a viable way to track renewable carbon incorporation in bio-oil co-processing products including the feedstock derived from C3 plants and guide the optimization of the co-processing parameters. Comparison of δ13C with radiocarbon (14C) results obtained by an accelerator mass spectrometer (AMS) reveals a significant correlation (R2 = 0.998) and confirms δ13C applicability for tracking renewable carbon in co-processing systems. Because C4 plant-derived bio-oils (−13‰) possesess more distinct δ13C values than C3 plant-derived bio-oils (-26‰) relative to VGO (~−30‰), the use of C4 plant-derived feedstock will greatly increase the renewable C traceability through 13C/12C ratio analysis in bio-oil co-processing.

Li, Z., Cao, M., Loyd, S.J., Algeo, T.J., Zhao, H., Wang, X., Zhao, L., Chen, Z.-Q., 2020. Transient and stepwise ocean oxygenation during the late Ediacaran Shuram Excursion: Insights from carbonate δ238U of northwestern Mexico. Precambrian Research 344, 105741.


The Ediacaran Shuram Excursion (SE) was a key episode in the history of atmospheric and oceanic oxygenation that has also been linked to contemporaneous bioevolutionary events. However, key aspects of the redox state of Ediacaran oceans during the SE remain in doubt. Here, the uranium isotope compositions (δ238U) of marine carbonates from Sonora, northwestern Mexico were measured to investigate ocean oxygenation during the SE. We found that the SE in Sonora is

characterized by a shift toward higher δ238U values (from −0.7‰ to −0.3‰), consistent with a major oxygenation event that has now been documented in widely separated coeval upper Ediacaran sections including the Doushantuo Formation in South China, the Bol'shoy Patom Formation in Siberia, and the Johnnie Formation in California. In the Sonora Succession, this δ238U shift exhibits a ~0.8-Myr lag relative to the δ13Ccarb excursion that defines the SE. To account for these observations, we propose a two-step oceanic oxygenation model for the SE: (1) initial oxidation of an aqueous reductant (e.g., dissolved organic carbon) that resulted only in a shift of δ13Ccarb (from +5‰ to −3‰); and (2) subsequent oxidation of methane or particulate organic matter that caused a continuation of the negative shift in δ13Ccarb (from −3‰ to −12‰) as well as a positive excursion of δ238U due to progressive oceanic oxygenation. This transient period of enhanced oceanic oxygenation of the late Ediacaran ocean, which may have promoted the evolution of early metazoans, terminated after ~5.0 to 6.5 Myr.


https://doi.org/10.1007/s10553-020-01091-0

Application of traditional rock physics experimental methods in investigating the macroscopic pertrophysical properties of low porosity, low permeability, and high complexity pore structure reservoirs is limited by the high cost, long cycle, large error, and specific difficulties of such reservoirs. It is also difficult to evaluate quantitatively the influence of microscopic reservoir structure on rock physical properties. Application of micro-CT scanning and advanced imaging processing technology enables one to establish an accurate representative pore space model equivalent to the true core structure. Numerical simulation with Avizo-XLab solver method was used to calculate the pore fluid flow based on the Navier-Stokes equation and the Darcy seepage law. The visualization method helped to display the pore-space fluid flow in a three-dimensional streamline, and the pore pressure distribution field is displayed, making the simulation results clear and intuitive. Research shows that numerical simulation based on the digital platform provides an instrument for the measurement of the fluid micro flow and the rock seepage parameters. This paper provides a new method for digital research on rock physical properties which helps to overcome the deficiency of traditional rock physics experimental research.

Liénart, C., Savoye, N., Conan, P., David, V., Barbier, P., Bichon, S., Charlier, K., Costes, L., Derriennic, H., Ferreira, S., Gueux, A., Hubas, C., Maria, E., Meziane, T., 2020. Relationship between bacterial compartment and particulate organic matter (POM) in coastal systems: An assessment using fatty acids and stable isotopes. Estuarine, Coastal and Shelf Science 239, 106720.


Particulate organic matter (POM) in coastal systems is a mixture of different organic matter (OM) sources originating from land and sea. Among sources, bacterial biomass plays a large role in OM processing and carbon recycling in the ocean and is often neglected as a source in common approaches. The present study proposes to use elemental and isotopic ratio of carbon and nitrogen (C:N, δ13C, δ15N) and fatty acids to investigate the relationship between bacteria and surface water POM composition of three systems with different characteristics (two marine and one estuarine) over an annual cycle. Overall, our results highlight a positive relationship between bacterial

contribution and continental degraded or undergoing degradation POM for all the studied systems and an inverse relationship with pelagic primary producers. At multisystem scale, high bacterial contribution is linked to high proportion of refractory terrestrial material characterizing estuarine stations whereas in marine systems, the occurrence of bacteria is mainly linked to river POM. Over the annual cycle, bacterial markers are more abundant during the winter period characterized by larger river and/or benthic POM contribution. This seasonal pattern is mainly driven by changes in river flows and resuspension. This study highlights the importance of bacterial compartment as a component of coastal and estuarine POM. Even though these results remains semi-quantitative, similar studies in other types of systems can help to understand microbial role in OM dynamic and to better estimate bacterial source in carbon budgets and food web studies.

Lin, J., Tsang, C., Lieu, R., Zhang, K., 2020. Fast chiral and achiral profiling of compounds with multiple chiral centers by a versatile two-dimensional multicolumn liquid chromatography (LC–mLC) approach. Journal of Chromatography A 1620, 460987.


It is critical to determine the chiral impurity profile of pharmaceutical compounds. The rising trend of drug candidates bearing multiple chiral centers has aggravated the analytical challenges. The traditional chiral HPLC methods can take gruelingly long time to develop yet may not offer sufficient resolution for all stereoisomers. A fast analytical strategy with a high success rate is in urgent demand for compounds with multiple chiral centers. In this study, we have developed an effective and fast multiple heart-cutting (MHC) multicolumn two-dimensional liquid chromatography (LC–mLC) platform approach. The m in the name of LC-mLC highlights the employment of multiple chiral columns with different chiral selectors and mobile phases in the second dimension (2D) within the same run. A short achiral HPLC method in the first dimension (1D) allows the separation of diastereomers and other achiral impurities, followed by 2D analysis enabling different chiral columns and different mobile phases on each coeluted 1D peak for maximum resolution. This LC–mLC strategy breaks down the complex multiple-chiral-center separation problems into simple individual one-chiral-center separation, which dramatically reduces chiral method development time and sample analysis turnaround. Its versatile nature and fast turnaround approach have made it a highly efficient strategy to enable quick stereoselective synthetic route development. This platform LC–mLC strategy has been successfully demonstrated in separating eight stereoisomers for a pharmaceutical compound with 3 chiral centers, within total method development time of less than 2 hours and a final analysis time of less than 24 min, including column equilibration time. It was also proved highly efficient in separating multiple chiral and achiral components in an in-process sample containing structurally similar starting materials, intermediates, side products and multiple stereoisomers of the product with 3 chiral centers, with minimal method development time.



The influence of oil-wet calcite cements on oil migration in clastic reservoirs is of significant interest in the field of petroleum exploration. However, the microscopic migration of oil in microscopic pore

spaces with oil-wet calcite cements has not been directly observed. Microscopic observations of oil migration were conducted in a glass micromodel at normal temperature and pressure to investigate the influence mechanism of oil-wet calcite cements on oil migration in pore spaces. The calcites were precipitated as cements prior to the oil migration. A two-dimensional glass micromodel with two interconnected spaces with the same pore throat structures was used in the experimental study. A new method to create firmly adhering calcites was used to precipitate equal amounts of calcites in the two interconnected spaces. The oil migration was recorded in real-time under a microscope throughout the experiment. The experimental results show that oil migration occurs faster in spaces with than without oil-wet calcites. During the oil migration in the pore-throat spaces, the oil migrates towards the surfaces of the oil-wet calcites when the oil is in contact with the calcites. The presence of oil-wet calcites significantly reduces the oil breakthrough pressure. The electrostatic attraction between the carboxylic groups and calcites and the intermolecular forces between the carboxylic groups and organic molecules in the oil cause the oil migration towards the surfaces of the oil-wet calcites. The experimental results indicate that oil preferentially migrates into clastic reservoirs that possess appropriate amounts of oil-wet calcite cements precipitated prior to oil emplacement.

Lincy, J., Manohar, C.S., 2020. A comparison of bacterial communities from OMZ sediments in the Arabian Sea and the Bay of Bengal reveals major differences in nitrogen turnover and carbon recycling potential. Biogeosciences Discussions 2020, 1-28.


The Northern Indian Ocean hosts two Oxygen Minimum Zones (OMZ), one in the Arabian Sea and the other in the Bay of Bengal. High-throughput sequencing was used to understand the total bacterial diversity in, the surface sediment off Goa within the OMZ of the Arabian Sea, and from off Paradip within the OMZ of the Bay of Bengal. The dominant phyla identified included Firmicutes (33.08 %) and Proteobacteria (32.59 %) from the Arabian Sea, and Proteobacteria (52.65 %) and Planctomycetes (9.36 %) from the Bay of Bengal. Only 30 % of OTUs were shared between the sites which make up three-fourth of the Bay of Bengal OMZ bacterial community, but only one-fourth of the Arabian Sea OMZ sediment bacterial community. Statistical analysis indicated the bacterial diversity from sediments of the Bay of Bengal OMZ is ~ 48 % higher than the Arabian Sea OMZ. The community analysis combined with a predictive functional profiling of 16S rRNA amplicons pinpointed the occurrence of specific enzymes that are crucial in the cycling of nitrogen and sulfur compounds, with major differences regarding nitrogen fixation and carbon recycling.

Lineweaver, C.H., Sleep, N., 2020. Are we alone? An interview with Dr. Norman Sleep. Astrobiology 20, 563-571.

https://doi.org/10.1089/ast.2020.0224

No abstract

Lingam, M., Loeb, A., 2020. Photosynthesis on exoplanets and exomoons from reflected light. International Journal of Astrobiology 19, 210-219.

https://doi.org/10.1017/S1473550419000247

Photosynthesis offers a convenient means of sustaining biospheres. We quantify the constraints for photosynthesis to be functional on the permanent nightside of tidally locked rocky exoplanets via reflected light from their exomoons. We show that the exomoons must be at least half the size of Earth's moon in order for conventional oxygenic photosynthesis to operate. This scenario of photosynthesis is unlikely for exoplanets around late-type M-dwarfs due to the low likelihood of large exomoons and their orbital instability over long timescales. Subsequently, we investigate the prospects for photosynthesis on habitable exomoons via reflected light from the giant planets that they orbit. Our analysis indicates that such photosynthetic biospheres are potentially sustainable on these moons except those around late-type M-dwarfs. We conclude our analysis by delineating certain physiological and biochemical features of photosynthesis and other carbon fixation pathways, and the likelihood of their evolution on habitable planets and moons.

Link, M.F., Nguyen, T.B., Bates, K.H., Müller, J.-F., Farmer, D.K., 2020. Can isoprene oxidation explain high concentrations of atmospheric formic and acetic acid over forests? ACS Earth and Space Chemistry 4, 730-740.


Formic and acetic acid concentrations are particularly high over forested areas of the world. However, the gas-phase mechanisms for producing these acids are poorly understood even for isoprene, the globally dominant biogenic hydrocarbon. We quantified formic and acetic acid production from reactions of hydroxyl radical (OH)—between high and low ranges of nitric oxide (NO) levels—with isoprene, methacrolein (MACR), isoprene epoxydiol (IEPOX), isoprene hydroxy hydroperoxide (ISOPOOH), and α-pinene from the Focused Isoprene eXperiments at California Institute of Technology (FIXCIT) laboratory chamber study. We find that (i) OH oxidation of MACR, IEPOX, and ISOPOOH are sources of formic acid, (ii) isoprene peroxy radical isomerization and associated photolysis oxidation products are potentially important sources of organic acids, and (iii) high levels of NO generally suppress organic acid formation from OH oxidation of isoprene. We modified existing chemical mechanisms for isoprene oxidation to account for organic acid production pathways observed in the FIXCIT study. We simulated organic acid production during the Southeastern Oxidant and Aerosol Study using the updated chemical mechanisms and represent acetic acid within a factor of two, but still underpredict formic acid by a factor of six. While we cannot explain ambient formic acid with explicit chemical mechanisms, the FIXCIT results suggest that the oxidation of isoprene could account for as much as 70% of the global annual production of formic acid from gas-phase reactions.

Liu, B., Zhao, C., Fiebig, J., Bechtel, A., Sun, Y., Püttmann, W., 2020. Stable isotopic and elemental characteristics of pale and dark layers in a late Pliocene lignite deposit basin in Yunnan Province, southwestern China: Implications for paleoenvironmental changes. International Journal of Coal Geology 226, 103498.


The carbon and nitrogen stable isotopic compositions and elemental characteristics of Pliocene pale and dark lignites in the Jinsuo Basin, Yunnan Province, southwestern China, were investigated. These data were used to develop paleoenvironmental models and to discuss possible geological driving forces for the formation of pale and dark layers.

The δ13C values of fossil wood (av. −24.79‰) and fusain samples (av. −24.19‰) are generally higher than the values obtained from bulk pale (av. −27.01‰) and dark (av. −26.38‰) lignite samples. In contrast, the δ15N values of fossil wood (av. −0.63‰) and fusain samples (av. 1.29‰) are lower than the average values of bulk pale lignites (av. 2.17‰) and dark lignites (av. 1.79‰). The difference in the carbon isotopic values between pale and dark lignites can be explained by the very high amount of liptinite and strong degradation of woody material by bacterial activity in pale lignites, which resulted in depletion of 13C in pale lignites, and the wet/humid depositional conditions contributed to the relatively heavy stable carbon isotope compositions of dark layers. The higher δ13C values in the fossil wood and fusain samples can be explained by the general enrichment of 13C in woody material compared to leaves. The weakly negative correlation between the δ15N and δ13C values indicates that, besides bacterial degradation, the liptinite content could also influence the carbon and nitrogen compositions of lignites. The influence of the original plant community (gymnosperms/angiosperms) on the carbon and nitrogen isotopic compositions of bulk lignites is insignificant in the Jinsuo Basin.

The paleoenvironmental model suggests deposition of pale layers under relatively dry, cold conditions supporting the expansion of gymnosperms such as Pinus yunnanensis. The slight stepwise uplift of the Tibetan Plateau and the approximate co-occurrence of the more intense Asian monsoon might have supported short periods of a locally dry, cold climate resulting in the lowering of water table which was favorable for the formation of pale layers. The low δ13C values in pale layers further support this. The relatively high SiO2/Al2O3 ratios, higher values of the average detrital/authigenic index, and high levels of TiO2 and Zr in pale layers suggest an increased detrital input relative to dark layers. The dark layers, however, formed in a tropical/subtropical warm, humid climate that favored angiosperm dominance of the vegetation. The long-term geologically stable conditions together with the regionally warm, humid climate resulted in a rise in the water table in the basin, which led to the formation of dark layers until the subsequent slight uplift of the Tibetan Plateau. This conclusion is also supported by the high δ13C values in dark layers and the thickness differences between pale (thin) and dark (thick) layers and the changes in major elements and minerals changes between the two types of layer.

Liu, D., Li, J., Liu, J.-q., Zhang, L., 2020. Modeling hydrocarbon accumulation based on gas origin and source rock distribution in Paleozoic strata of the Ordos Basin, China. International Journal of Coal Geology 225, 103486.


Paleozoic gases in the Ordos Basin, China, are produced from upper Paleozoic tight sandstones, Ordovician weathered-crust, and ‘pre-salt’ (beneath gypsum deposits) dolomite reservoirs. Their origins have been debated, particularly as to whether Carboniferous–Permian (C-P) or Ordovician source rocks contributed more gas to the lower Paleozoic gas reservoirs. The expanded exploration of lower Paleozoic gas to the eastern, western, northern, and southern regions of the basin has re-initiated the debates. In this study, geochemical characteristics of gas samples from newly drilled wells in different regions of Ordos Basin in combination with the source rock evaluation were used to determine the gas origin. The carbon and hydrogen isotope of alkane indicate that gas mixing occurred in both upper Paleozoic and Ordovician weathered-crust gases, and that TSR occurred in pre-salt gases. A modified δ13C–1/Cn plot was suggested to be useful to determine the carbon isotopic patterns of gases generated from the different source rocks. The light hydrocarbon characteristic shows that oil-type gas mainly distributes in the eastern basin. A study of source-rock

distributions also indicates that the most favorable Ordovician source rock is located in the eastern basin. Based on the distribution of C-P coal measures, limestones and lower Paleozoic carbonate source rock, a gas accumulation history was established. The results of this study provide applicable method for identifying gas origin in Ordos Basin. Moreover, the accumulation history proposed in this study is useful for further exploration of the lower Paleozoic gas in Ordos Basin.

Liu, G.-H., Zong, Z.-M., Liu, F.-J., Ma, Z.-H., Wei, X.-Y., Kang, Y.-H., Fan, X., Ma, F.-Y., Liu, J.-M., Mo, W.-L., 2020. Two-step catalytic degradations of Dahuangshan lignite and directional upgrading of the resulting petroleum ether-extractable portions. Energy & Fuels 34, 5457-5465.


A biochar (BC)-supported non-noble metal catalyst CoMoSxOy@BC was prepared by in situ co-pyrolysis and ex situ sulfurization, and a two-step conversion (TSC) strategy, including H2-controlled catalytic hydroconversion (CHC) and catalytic ethanolysis without H2 participation, was proposed and used for catalyzing degradation of Dahuangshan lignite (DL) into soluble species (SSs) in high yields. CoMoSxOy@BC with uniformly dispersed nanoparticles of metals, metal sulfides, and metal oxides plays a crucial role in the TSC. The effective activation of H2 and ethanol over CoMoSxOy@BC facilitates cleaving bridged linkages in organic matter of DL to increase the SS yields. As a result, the total yield of SSs increased from 42.7% via non-catalytic degradation (NCD) to 70.0% via catalytic degradation (CD), while that of the petroleum ether-extractable portion (PEEP) increases from 17.5% via NCD to 27.0% via CD. In addition, according to the analysis with a gas chromatograph/mass spectrometer, alkanes, arenes, and arenols are dominant in PEEPs from step 1 (PEEPs1), while alkanol, arenols, and esters in PEEPs from step 2 (PEEPs2) are predominant. The difference in composition among the PEEPs and hydrogenated PEEPs obtained by the CHC further confirms that PEEPs1 are more suitable as a precursor for the fuel-platform unit, while PEEPs2 are better candidates for obtaining value-added chemicals. In other words, multiple PEEPs in high yields with different properties can be obtained by this TSC strategy, which provides a potential and promising alternative to the clean and efficient utilization of lignites.


http://www.kirj.ee/33414/?tpl=1061&c_tpl=1064

The combustion experiment of Longkou oil shale semicoke was conducted in a batch fluidized bed reactor. A specific surface area (SSA) analyzer and a scanning electron microscope (SEM) were used to respectively measure the specific surface area of samples and examine their surface pore structure in different experimental operating conditions, and the fractal dimension (FD) was used to describe the complexity of pore morphology. The results showed that Longkou oil shale semicoke had a developed pore structure, and in the combustion process, its SSA and pore volume first increased and then decreased, remaining finally unchanging. Most pores were micropores and mesopores of about 2 nm in size. The pore structure was fully developed at a temperature of 600 °C, at which the specific surface area and pore volume also reached maximum values. There were great differences in the pore size distribution of semicoke with different particle sizes. As calculated by the box-counting method (BCM) and the Frenkel-Halsey-Hill (FHH) equation, the pore size showed similar trends of variation, increasing first and then decreasing slowly.

Liu, H., Liu, S., Luo, X., Sun, Y., Tian, J., Liang, L., Liu, X., 2020. Study of fractal characteristics of the cementation index in shale gas. Acta Geologica Sinica - English Edition 94, 456-466.

https://doi.org/10.1111/1755-6724.14302

The description of pores and fracture structures is a consistently important issue and certainly a difficult problem, especially for shale or tight rocks. However, the exploitation of so called ‐unconventional energy, such as shale methane and tight oil, has become more and more dependent‐ on an understanding of the inner structure of these unconventional reservoirs. The inner structure of porous rocks is very difficult to describe quantitatively using normal mathematics, but fractal geometry, which is a powerful mathematical tool for describing irregularly shaped objects, can be ‐applied to these rocks. To some degree, the cementation index and tortuosity can be used to describe the complexity of these structures. The cementation index can be acquired through electro lithology experiments, but, until now, tortuosity could not be quantitatively depicted. This ‐research used the well logging curves of a gas shale formation to reflect the characteristics of the ‐rock formations, and the changes in the curves to indicate the changes of the rock matrix, the pores, the connections among the pores, the permeability, and the fluid type. The curves that are affected most by the rock lithology, such as gamma ray, acoustic logging, and deep resistivity curves, can provide significant information about the micro or nanostructure of the rocks. If the rock structures‐ have fractal characteristics, the logging curves will also have fractal properties. Based on the definition of a fractal dimension and the Hausdorff dimension, this paper presents a new methodology for calculating the fractal dimensions of logging curves. This paper also reveals the deep meaning of the rock cementation index, m, through the Hausdorff dimension, and provides a new equation to calculate this parameter through the resistivity and porosity of the formation. Although it represents a very important relationship between the saturation of hydrocarbons with pores and resistivity, the Archie formula was not available for shale and tight rock. The major reason for this was an incorrect understanding of the cementation index, and the calculation of saturation used a single m value from the bottom to the top of the well. Unfortunately, this processing method is clearly inappropriate for the intensely heterogeneous material that is shale and tight rock. This paper proposes a method of calculating m through well logging curves based on a fractal geometry ‐that can change with different lithologies, so that it would have more agreement with in situ scenarios than traditional methods.

Liu, H., Wang, Y., Xiong, H., Wu, K., 2020. Semianalytical analysis of chamber growth and energy efficiency of solvent-assisted steam-gravity drainage considering the effect of reservoir heterogeneity along the horizontal well. Energy & Fuels 34, 5777-5787.


Solvent-assisted steam-gravity drainage (SA-SAGD) has lately been viewed as one of the most efficient alternatives to develop heavy oil reservoirs. However, there is strong evidence that reservoir heterogeneity along the horizontal well can significantly affect chamber evolution and energy efficiency which has been rarely investigated for SA-SAGD. In this study, a mathematical method is proposed for the chamber growth in the heterogeneous reservoir by considering the wellbore flow effect coupled with the effect of phase change. Subsequently, the recovery rate and the energy efficiency, defined as the steam–oil ratio (SOR) of SA-SAGD, under different permeability

distributions along the horizontal well are estimated using the method. The results reveal that heterogeneous reservoirs with high-to-low permeability distribution can achieve the highest oil production from SA-SAGD, but they are still lower than those in the homogeneous reservoirs. In addition, the highest energy efficiency in the SA-SAGD project can be achieved by injecting hot fluid from the lower permeability to the higher permeability region in the heterogeneous reservoir. The findings of this paper shed light on understanding the effects of reservoir heterogeneity along the horizontal well on the SA-SAGD project evaluation and the optimal designing for the decision of the injection direction in the SA-SAGD project, which can be applied to more reliably investigate greenhouse gas emission and economic benefits in a future bitumen exploitation project.

Liu, J., Hunfeld, L.B., Niemeijer, A.R., Spiers, C.J., 2020. Frictional properties of simulated shale-coal fault gouges: Implications for induced seismicity in source rocks below Europe's largest gas field. International Journal of Coal Geology 226, 103499.


We report 21 frictional sliding experiments performed on simulated fault gouges prepared from shale-coal mixtures. Our aim was to investigate the effects of local coal seam smearing on the frictional properties and induced seismogenic potential of faults cutting the Upper Carboniferous source rocks underlying the Groningen gas reservoir (Netherlands). We used shale/siltstone core recovered from beneath the Groningen reservoir plus Polish bituminous coal of similar age and origin to coals locally present in the Groningen source rocks. We performed friction experiments in velocity stepping, constant velocity, slide-hold-slide (SHS) and slide-unload-slide (SUS) modes, under near in-situ conditions of 100 °C and 40 MPa effective normal stress, employing sliding velocities of 0.1–100 μm/s and a variety of pore fluids. Samples with 0–50 vol% coal showed friction coefficients ~0.45, with minor slip weakening. Samples with ≥50 vol% coal showed marked slip-weakening from peak friction values of ~0.47 to ~0.3, regardless of experimental conditions, presumably reflecting strain localization in weak coal-rich shear bands, possibly accompanied by changes in coal molecular structure. However, re-sliding experiments (SUS) showed that slip-weakening is limited to small initial displacements (2–3 mm), and does not occur during slip reactivation. At (near) steady state, almost all experiments performed at in-situ stress, pore water pressure (15 MPa) and temperature conditions exhibited stable, velocity strengthening behaviour, regardless of coal content. By contrast, under dry and gas-saturated (CH4, Argon) conditions, or using water at 1 atm, 50:50 (vol%) shale-coal mixtures showed velocity-weakening and even stick-slip. Our results imply that faults in the Groningen Carboniferous shale-siltstone sequence are not prone to induced earthquake nucleation at in-situ conditions, even when coal-bearing or coal-enriched by smearing. However, the mechanisms controlling coal friction remain unclear at the sliding velocities studied, and the evolution of coal friction at seismic slip velocities remains unknown.

Liu, J., Pearson, D.G., Shu, Q., Sigurdsson, H., Thomassot, E., Alard, O., 2020. Dating post-Archean lithospheric mantle: Insights from Re-Os and Lu-Hf isotopic systematics of the Cameroon Volcanic Line peridotites. Geochimica et Cosmochimica Acta 278, 177-198.


Highly depleted Archean peridotites have proven very amenable to Re-Os model age dating. In contrast, due to the increasing heterogeneity of mantle Os isotope compositions with time, the Re-

Os system has not been as effective in dating post-Archean peridotites. The timing of depletion and accretion of post-Archean lithospheric mantle around cratons is important to understand within the context of the evolution of the continents. In an attempt to precisely date post-Archean peridotite xenoliths, we present a study of the petrology, mineralogy and geochemistry, including whole-rock Re-Os isotopes, highly siderophile elements and clinopyroxene-orthopyroxene Sr-Nd-Hf isotopes of peridotite xenoliths from Lake Nyos in the Cameroon Volcanic Line (CVL). Eight Nyos peridotite xenoliths, all fresh spinel lherzolites, are characterized by low to moderate olivine Fo contents (88.9–91.2) and low spinel Cr# (8.4–19.3), together with moderate to high whole-rock Al2O3 contents (2.0–3.7%). These chemical characteristics indicate that they are mantle residues of a few percent to <20% partial melting. However, trace element patterns of both clinopyroxene and orthopyroxene are not a pristine reflection of melt depletion but instead show various extents of evidence of metasomatic enrichment. Some of the samples contain orthopyroxene with 143Nd/144Nd lower than its coexisting clinopyroxene, which is best explained by recent short-timescale alteration, most likely by infiltration of the host basalt. Because of these metasomatic effects, the Sr-Nd isotope systematics in pyroxenes cannot sufficiently reflect melt depletion signatures. Unlike Sr-Nd isotopes, the Lu-Hf isotope system is less sensitive to recent metasomatic overprinting. Given that orthopyroxene hosts up to 33% of the Lu and 14% of the Hf in the whole rock budget of these rocks and has 176Hf/177Hf similar to, or higher than, coexisting clinopyroxene, it is necessary to reconstruct a whole-rock Lu-Hf isochron in order to constrain the melt depletion age of peridotites. The reconstructed Nyos Lu-Hf isochron from ortho- and clinopyroxenes gives an age of 2.01 ± 0.18 Ga (1σ), and when olivine and spinel are considered, is 1.82 ± 0.14 Ga (1σ). Both ages are identical within error, and they are within error of the alumina-187Os/188Os pseudo-isochron ages (1.2–2.4 Ga) produced on the peridotites from Lake Nyos, consistent with their oldest rhenium depletion Os model ages (2.0 Ga). We conclude that the Nyos peridotites, and the lithospheric mantle that they represent, were formed at ∼2.0 Ga, indicating that the reconstructed whole-rock Lu-Hf isotope system can be a powerful radiometric dating tool that is complementary to and in some instances, more precise than the Re-Os isotope system in dating well-preserved post-Archean peridotites. The recognition of ∼2.0 Ga subcontinental lithospheric mantle (SCLM) in the Nyos area suggests that the Nyos region was assembled as a Paleoproterozoic block, or that it represents fragments of the SCLM from the nearby Paleoproterozoic domain juxtaposed through collisional emplacement during the Pan African Orogeny. With regards to the origin of the CVL, our data reveal that the Hf isotopic compositions of the Nyos peridotites are too radiogenic to be the main source of the CVL basalts.

Liu, J., Zhu, S., Liu, X., Yao, P., Ge, T., Zhang, X.-H., 2020. Spatiotemporal dynamics of the archaeal community in coastal sediments: assembly process and co-occurrence relationship. The ISME Journal 14, 1463-1478.

https://doi.org/10.1038/s41396-020-0621-7

Studies of marine benthic archaeal communities are updating our view of their taxonomic composition and metabolic versatility. However, large knowledge gaps remain with regard to community assembly processes and inter taxa associations. Here, using 16S rRNA gene amplicon sequencing and qPCR, we investigated the spatiotemporal dynamics, assembly processes, and co-occurrence relationships of the archaeal community in 58 surface sediment samples collected in both summer and winter from across ~1500 km of the eastern Chinese marginal seas. Clear patterns in spatiotemporal dynamics in the archaeal community structure were observed, with a more pronounced spatial rather than seasonal variation. Accompanying the geographic variation was a

significant distance-decay pattern with varying contributions from different archaeal clades, determined by their relative abundance. In both seasons, dispersal limitation was the most important process, explaining ~40% of the community variation, followed by homogeneous selection and ecological drift, that made an approximately equal contribution (~30%). This meant that stochasticity rather than determinism had a greater impact on the archaeal community assembly. Furthermore, we observed seasonality in archaeal co-occurrence patterns: closer inter-taxa connections in winter than in summer, and unmatched geographic patterns between community composition and co-occurrence relationship. These results demonstrate that the benthic archaeal community was assembled under a seasonal-consistent mechanism but the co-occurrence relationships changed over the seasons, indicating complex archaeal dynamic patterns in coastal sediments of the eastern Chinese marginal seas.


https://doi.org/10.1038/s41598-020-65325-1

Mudstone is very similar to shale except it lacks sheet bedding. Shale gas is widely concerned and successfully exploited commercially in the world, while gas-bearing mudstone is rarely paid attention. To evaluate the reservoir characteristics and exploitation potential of gas-bearing mudstone, a total of 127 mudstone samples from the Shanxi formation were tested by X-ray diffraction (XRD), scanning electron microscope (SEM), gas content, etc., and the qualitative identification and quantitative evaluation of gas-bearing mudstone reservoirs were performed on four wells using the logging curve overlay method and reservoir parameter calculation equations. The results showed that: (1) the average total gas content of core measurement is 1.81 m3/t, and the total content of brittle minerals is 44.2%, which confirms that mudstones can also have good gas content and fracturing performance; (2) logging evaluation the average thickness of gas-bearing mudstone is 55.7 m, the average total gas content is 1.6 m3/t, and the average brittleness index is 38.1%, which indicates that the mudstone of Shanxi formation in the study area is generally gas-bearing and widely distributed. All the results reveal that gas-bearing mudstone with block bedding has the same exploitation potential as shale with sheet bedding,which deserves more attention.

Liu, M., Sun, P., Them, T.R., Li, Y., Sun, S., Gao, X., Huang, X., Tang, Y., 2020. Organic geochemistry of a lacustrine shale across the Toarcian Oceanic Anoxic Event (Early Jurassic) from NE China. Global and Planetary Change 191, 103214.


Thirty-nine shale samples of the Lower Jurassic Beipiao Formation from drill core ZK01 in the Jinyang Basin, NE China were investigated by comprehensive organic geochemical methods in this study. A prominent negative excursion in δ13Corg values (~ 2‰) was observed in the Beipiao Formation, which is most likely associated with Toarcian Oceanic Anoxic Event (T-OAE) negative carbon isotope excursion (CIE) that is recorded globally in marine and terrestrial sediments constrained by previous studies. Elemental and Rock-Eval analyses of Beipiao shales demonstrate that the total organic carbon (TOC) ranges from 0.56 to 4.33 wt% (average of 1.40 wt%) and S2 values range from 0.12 to 6.91 mg/g (average of 1.3 mg/g) and implicate fair to good source rock potential. A majority of the

Tmax values of the Beipiao shales range from 456 to 465 °C, indicating that the organic matter is within the mature oil window apart from few overmature samples with extreme high Tmax values that might have been affected by local magmatic intrusions. Elemental analysis suggests that the kerogens are mainly Type II-III. Unlike many marine organic-rich sediments deposited during OAEs, redox proxies indicate no significant upper water column oxygen-depletion during the formation of Beipiao lacustrine shale. The decreasing upward trend of organic source indicators such as tricyclic terpanes/C30 hopane values, relative distributions of regular C27 steranes to C29 steranes, and steranes/hopanes in the Beipiao Formation consistently suggest a shift to a lower abundance of eukaryotic organisms relative to bacterial community abundance during the onset of the T-OAE. Meanwhile, gradually decreasing values of gammacerane/C30 hopane in the Beipiao Formation during the negative CIE suggest decreasing salinity and increased mixing of the Jinyang paleo-lake system, potentially corresponding with the shift toward an accelerated hydrological cycle with enhanced fresh water input to this lacustrine system. Moreover, increasing C30 moretane/C30 hopane values contemporaneous with the negative CIE also suggest enhanced land erosion during putative Toarcian climatic warming, which could have increased delivery of riverine nutrients and elevated regional primary productivity, eventually resulting in massive organic matter accumulation in the Beipiao shales.


https://doi.org/10.1155/2020/8543687

As unconventional water-bearing rocks, the hydraulic conductivity of weakly cemented sandstones can increase by several orders of magnitude during drainages or pumping tests, posing great challenges to water prevention and control of coal mines in northwestern China. In this study, seepage experiments on Jurassic weakly cemented sandstones were performed and the hydraulic conductivity during the seepage process was analyzed. Combined with laboratory test and theoretical analysis methods, the relation between the permeability and micropore structures was studied, and the permeability evolution mechanism of the weakly cemented sandstones was eventually clarified. According to the experimental results, the seepage process can be divided into the saturated seepage stage, the stable seepage stage, and the seepage mutation stage. The hydraulic conductivity increases as the porosity and the mercury extrusion rate increase, but there is no obvious correlation between them that can be identified. In contrast, there is a linear positive correlation between the hydraulic conductivity and the average pore-throat radius. The variation trend of the pore-throat ratio can be used as the main reference indicator for judging whether the seepage mutation occurs in weakly cemented sandstone. Based on the correlation analysis of micropore structures and the hydraulic conductivity, a seepage model of straight capillary was constructed and the theoretical permeability equations of stable seepage stage and seepage mutation stage were proposed. It is concluded that the specific permeability of weakly cemented sandstones is directly proportional to porosity and the square of the average pore-throat radius. A theoretical equation to calculate the specific permeability during the latter two stages was also presented in this paper. Theoretical calculation results are roughly consistent with actual values obtained in the experiments.


https://doi.org/10.1111/1755-6724.14332

The sedimentary, paleogeomorphological and reservoir characteristics of the Jurassic Yan'an Formation in the southwestern Ordos Basin, northwestern China, were studied by means of casting thin sections, scanning electron microscopy, inclusion analysis and identification of low amplitude ‐structures. A model for reservoir formation is established, and the controlling effects of sedimentary facies, paleotopography, low amplitude structures and formation water on oil reservoirs are ‐revealed. There are significant differences in the sedimentary characteristics, structural morphology and paleowater characteristics between the reservoirs above the Yan 10 Member and those in the Yan 9 to Yan 7 Members. The Yan 10 Member contains fluvial sediments, whereas the Yan 9 to Yan 7 members contain delta plain anastomosing river deposits. The distribution of high permeability ‐ ‐ ‐reservoir is controlled by pre Jurassic paleogeomorphology and sedimentary facies. Some of these ‐facies exhibit high porosity and high permeability in a low permeability background. The main ‐hydrocarbon accumulation period was the late Early Cretaceous, filling was continuous, and the charging strength altered from weak to strong and then from strong to weak. The Yan 10 reservoir is mainly controlled by the paleogeomorphology: hydrocarbons migrated upward at a high speed through the unconformity surface, and accumulated in the favorable traps formed by paleogeomorphic structural units, such as gentle slopes or channel island. Furthermore, groundwater alternation in these areas was relatively stagnant, providing good reservoir preservation conditions. The reservoirs in the Yan 9 and higher members are controlled by the sedimentary facies, low amplitude structure and paleowater characteristics. Hydrocarbons migrated‐ through the three dimensional delivery system, influenced by favorable sedimentary facies and ‐high salinity groundwater, then accumulated in the favorable low amplitude structural traps that ‐ ‐formed during the hydrocarbon production period.

Liu, X., Xing, L., Qin, Z., Liu, H., 2020. The sensitive properties of hydrate reservoirs based on seismic stereoscopic detection technology. Acta Geologica Sinica - English Edition 94, 530-544.

https://doi.org/10.1111/1755-6724.14305

Higher precision determinations of hydrate reservoirs, hydrate saturation levels and storage ‐estimations are important for guaranteeing the ability to continuously research, develop and utilize natural gas hydrate resources in China. With seismic stereoscopic detection technology, which fully combines the advantages of different seismic detection models, hydrate formation layers can be observed with multiangle, wide azimuth, wide band data with a high precision. This technique ‐ ‐provides more reliable data for analyzing the distribution characteristics of gas hydrate reservoirs, establishing velocity models, and studying the hydrate sensitive properties of petrophysical ‐parameters; these data are of great significance for the exploration and development of natural gas hydrate resources. Based on a velocity model obtained from the analysis of horizontal streamer velocity data in the hydrate bearing area of the Shenhu Sea, this paper uses three VCs (longitudinal ‐spacing of 25 m) and four OBSs (transverse spacing of 200 m) to jointly detect seismic datasets consisting of wave points based on an inversion of traveltime imaging sections. Accordingly, by comparing the differences between the seismic phases in the original data and the forward‐modeled seismic phases, multiangle coverage constraint corrections are applied to the initial

velocity model, and the initial model is further optimized, thereby improving the imaging quality of the streamer data. Petrophysical elastic parameters are the physical parameters that are most directly and closely related to rock formations and reservoir physical properties. Based on the optimized velocity model, the rock elastic hydrate sensitive parameters of the hydrate reservoirs in ‐the study area are inverted, and the sensitivities of the petrophysical parameters to natural gas hydrates are investigated. According to an analysis of the inversion results obtained from these sensitive parameters, λρ, Vp and λμ are simultaneously controlled by the bulk modulus and shear modulus, while Vs and μρ are controlled only by the shear modulus, and the latter two parameters are less sensitive to hydrate bearing layers. The bulk modulus is speculated to be more sensitive ‐than the shear modulus to hydrates. In other words, estimating the specific gravity of the shear modulus among the combined parameters can affect the results from the combined elastic parameters regarding hydrate reservoirs.

Liu, Y., Fang, J., Jia, Z., Chen, S., Zhang, L., Gao, W., 2020. DNA stable-isotope probing reveals potential key players for microbial decomposition and degradation of diatom-derived marine particulate matter. MicrobiologyOpen 9, e1013.

https://doi.org/10.1002/mbo3.1013

Microbially mediated decomposition of particulate organic carbon (POC) is a central component of the oceanic carbon cycle, controlling the flux of organic carbon from the surface ocean to the deep ocean. Yet, the specific microbial taxa responsible for POC decomposition and degradation in the deep ocean are still unknown. To target the active microbial lineages involved in these processes, 13C labeled particulate organic matter (POM) was used as a substrate to incubate particle attached ‐ ‐(PAM) and free living microbial (FLM) assemblages from the epi and bathypelagic zones of the New‐ ‐ Britain Trench (NBT). By combining DNA stable isotope probing and Illumina Miseq high throughput ‐ ‐sequencing of bacterial 16S rRNA gene, we identified 14 active bacterial taxonomic groups that implicated in the decomposition of 13C labeled POM at low and high pressures under the ‐temperature of 15°C. Our results show that both PAM and FLM were able to decompose POC and assimilate the released DOC. However, similar bacterial taxa in both the PAM and FLM assemblages were involved in POC decomposition and DOC degradation, suggesting the decoupling between microbial lifestyles and ecological functions. Microbial decomposition of POC and degradation of DOC were accomplished primarily by particle attached bacteria at atmospheric pressure and by ‐free living bacteria at high pressures. Overall, the POC degradation rates were higher at atmospheric‐ pressure (0.1 MPa) than at high pressures (20 and 40 MPa) under 15°C. Our results provide direct evidence linking the specific particle attached and free living bacterial lineages to decomposition ‐ ‐and degradation of diatomic detritus at low and high pressures and identified the potential mediators of POC fluxes in the epi and bathypelagic zones.‐



One heavy crude oil from Liaohe Basin, NE China and its oxidized counterparts at 200 and 400 °C have been characterized geochemically by negative-ion electrospray ionization Orbitrap mass

spectrometry to investigate the variation of acid and neutral nitrogen compounds during in-situ combustion. The heteroatom compounds of acid and neutral nitrogen detected in the samples are mainly N1, N1O1, N1O2, O1, O2, O3 and O4 classes, dominated by N1, O1 and O2. The N1 class predominated by carbazole and benzocarbazole with double bond equivalents (DBE) 9 and 12, is relatively stable and resistant to oxidation, while the N1O1 and N1O2 classes vary without a clear trend during oxidation. The O1 class is generally low in raw sample and the 200 °C oxidized oil but increases sharply in the 400 °C oxidized oil. The O2 class is peaked in the 200 °C oxidized oil but its relative concentration declines drastically in the 400 °C oxidized oil. The O1 and O2 class compounds show a similar DBE and carbon number (CN) distribution trend with increasing temperatures. Lower DBE and CN compounds are enriched in the 400 °C oxidized oil after alkyl side chain cleavage, where small proportion of high DBE compounds derived from aromatization and condensation has also been observed. The relative abundance of O1 and O2 species with specific DBE values and carbon number ranges are sensitive to in-situ thermal upgrading and ratios of DBE1/DBE4-O1 and DBE1/DBE3-O2 endure the potential as geochemical proxies to monitor the degree of oil upgrading.

Liu, Y., Wan, Y.Y., Wang, C., Ma, Z., Liu, X., Li, S., 2020. Biodegradation of n-alkanes in crude oil by three identified bacterial strains. Fuel 275, 117897.


In this study, aerobic biodegradation of crude oil was simulated using Pseudomonas aeruginosa XJ16, Bacillus cereus XJ20, and Acinetobacter lwoffii XJ19 bacteria for 90 days, for semi-quantitative calculation of concentration, demonstrating that n-alkanes (C14–C35) were biodegraded by the three strains at different ratios and rates. P. aeruginosa XJ16 showed the highest biodegradative potential for n-alkanes, with total biodegradation ratio of 98.2% in 10 days. In comparison, the total biodegradation ratio by B. cereus XJ20 increased gradually and achieved 98.8% after 90 days; whereas that by A. lwoffii XJ19 was much lower even after 90 days (29.3%). In addition, P. aeruginosa XJ16 and B. cereus XJ20 exhibited stronger biodegradation efficiencies for C18–C32 n-alkanes (95.4%–99.7%) than A. lwoffii XJ19 (9.05%–73.0%). However, all three bacterial strains exhibited comparably good biodegradation efficiencies for C33–C35 n-alkanes (60.2%–86.4%). Moreover, the biodegradation rate constants and biodegradation rates were of the decreasing order: P. aeruginosa XJ16 > B. cereus XJ20 > A. lwoffii XJ19. P. aeruginosa XJ16 and B. cereus XJ20 biodegrade n-alkanes with relatively low carbon numbers more easily than those with high carbon numbers. However, A. lwoffii XJ19 is more likely to biodegrade n-alkanes with relatively high carbon numbers. On day 10, surface tension (mN·m−1) declined from 70.6 to 35.9 by treatment with P. aeruginosa XJ16, to 31.3 with B. cereus XJ20, and to 34.1 with A. lwoffii XJ19. As biosurfactant-producing and hydrocarbon-degrading bacteria, these three strains have the potential to be used for bioremediation of hydrocarbon pollutants.



Biodegradation preference of single, identified bacterium is the basis of bioremediation and microbial enhanced oil recovery (MEOR). However, the impacts of different bacterial species on the

biodegradation of polar compounds are unclear. Accordingly, in this study, we performed a 90-day biodegradation simulation of crude oil using Pseudomonas aeruginosa XJ16 and Acinetobacter lwoffii XJ19. Biodegraded oils were characterized by negative-ion electrospray source ionization ESI (−), Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS), and gas chromatography–mass spectrometry (GC-MS). We aimed to study the differential biodegradation and mechanism of nitrogen- and oxygen-containing polar compounds using two strains that showed different abilities to produce and utilize polar compounds. P. aeruginosa XJ16 could easily biodegrade n-alkanes and n-alkyl cyclohexanes, whereas A. lwoffii XJ19 was able to utilize complex compounds, such as steranes and hopanes. Compared with P. aeruginosa XJ16, A. lwoffii XJ19 biodegraded more N1 class and produced more intermediate products (N1O1 and N1O2 classes). The efficiency of biodegradation of O1 varied with the type of microorganism. Intermediate products, such as alkylphenols, alkylnaphthols naphthols, and phenyl phenols, were produced by P. aeruginosa XJ16, whereas A. lwoffii XJ19 biodegraded these products. After biodegradation, the saturated fatty acids in Pa-90 and Al-90 decreased through the monoterminal, diterminal, and subterminal oxidation of n-alkane. However, naphthenic acids with 1–6 rings produced from terminal oxidation of naphthenes or dearomatization of aromatic hydrocarbons increased. Overall, these findings provided key insights into the biodegradation of polar compounds by different bacterial species.


https://doi.org/10.1021/acsearthspacechem.9b00316

Studies assessing the environmental impacts of oil spills focus primarily on the nonwater-soluble components, leaving the fate of the water-soluble fraction (WSF) largely unexplored. We employed untargeted chemical analysis along with biological information to probe the transformation of crude oil WSF in seawater in the absence of light in a laboratory experiment. Over a 14-day incubation, microbes transformed WSF into various metabolic intermediates without significantly altering the dissolved organic carbon concentrations. Microbial transformation processes increased the chemical diversity and overall oxygen content of WSF compounds, concomitant with an increase in dioxygenase gene abundances. While the majority of metabolites formed from the transformation of WSF could not be structurally identified with existing databases, elemental formulas suggest that many of these compounds could be oxidation products of water-soluble nonpolar compounds such as PAHs. In particular, metabolites with three oxygen atoms may represent a key transition point for WSF degradation. One such compound, salicylic acid, likely provides a route for complete WSF remineralization, as it is labile to marine bacteria. The environmental persistence and toxicity of WSF metabolic products are still unknown, but results from this study provide a framework for further exploration of the fate of WSF in marine ecosystems.

Liu, Y., Xu, J., Tao, Y., Fang, T., Du, W., Ye, A., 2020. Rapid and accurate identification of marine microbes with single-cell Raman spectroscopy. Analyst 145, 3297-3305.

http://dx.doi.org/10.1039/C9AN02069A

Rapid and accurate identification of individual microorganisms, such as pathogenic or unculturable microbes, is significant in microbiology. In this work, rapid identification of marine microorganisms by single-cell Raman spectroscopy (scRS) using one-dimensional convolutional neural networks (1DCNN) was explored. Here, single-cell Raman spectra of ten species of marine actinomycetes, two species of non-marine actinomycetes and E. coli (as a reference) were individually collected. Several common classification algorithms in chemometrics, including linear discriminant analysis with principal component analysis and a support vector machine, were applied to evaluate the 1DCNN performance based on the raw and pre-processed Raman spectra. 1DCNN showed superior performance on the raw data in terms of its accuracy and recall rate compared with other classification algorithms. Our investigation demonstrated that the scRS-integrating advanced 1DCNN classification algorithm provided a rapid and accurate approach for identifying individual microorganisms without time-consuming cell culture and sophisticated or specific techniques, which could be a useful methodology for discriminating the microbes that cannot be cultured under normal conditions, especially for ‘biological risk’-related emergencies.

Liu, Z., Guo, S., Lv, R., 2020. Shale-gas play risk of the lower Cambrian on the Yangtze platform, South China. American Association of Petroleum Geologists Bulletin 104, 989-1009.

http://archives.datapages.com/data/bulletns/2020/05may/BLTN18148/bltn18148.html

This paper describes the establishment of shale-gas play risk workflow and discusses the major geologic risks for the lower Cambrian shale-gas play on the Yangtze platform. The shale-gas play risk is assessed by considering the probability of occurrence (Po) of hydrocarbon charge, reservoir, and retention (HCRR) of a shale-gas play. The Po of each of these three factors is determined according to geological understanding and data availability. The risk of these factors is categorized into high risk (Po ≤ 0.3), relatively high risk (0.3 < Po < 0.5), relatively low risk (0.5 < Po < 0.7), and low risk (Po ≥ 0.7). Multiplication of these probabilities generates the chance of geologic success (COGS). The COGS values determine the shale-gas play risk. This workflow provides a method for transferring geological understanding and data availability to quantitatively assess the probability of HCRR. The ranking process allows a focus on the assessment unit of the lowest risk, which is most likely to deliver high-quality prospects.

The shale-gas play risk assessment was used to evaluate the major geologic risks of the lower Cambrian shales in each assessment unit and the range of uncertainties resulting from the available database. Essentially, extremely high thermal maturities (vitrinite reflectance equivalent > 3.5%) and poor hydrocarbon retention are the key geologic risks of the lower Cambrian shale-gas play. Uncertainty is inherent in the play risk assessment owing to sparse well data coverage. Understanding the play risks and uncertainties warrants further study of the impact of extremely high thermal maturities and burial history and how it facilitates decision-making for exploration investment.

Liu, Z., Huang, E., Orozco, I., Liao, W., Palomino, R.M., Rui, N., Duchoň, T., Nemšák, S., Grinter, D.C., Mahapatra, M., Liu, P., Rodriguez, J.A., Senanayake, S.D., 2020. Water-promoted interfacial pathways in methane oxidation to methanol on a CeO2-Cu2O catalyst. Science 368, 513-517.


Abstract: Highly selective oxidation of methane to methanol has long been challenging in catalysis. Here, we reveal key steps for the promotion of this reaction by water when tuning the selectivity of a well-defined CeO2/Cu2O/Cu(111) catalyst from carbon monoxide and carbon dioxide to methanol under a reaction environment with methane, oxygen, and water. Ambient-pressure x-ray photoelectron spectroscopy showed that water added to methane and oxygen led to surface methoxy groups and accelerated methanol production. These results were consistent with density functional theory calculations and kinetic Monte Carlo simulations, which showed that water preferentially dissociates over the active cerium ions at the CeO2–Cu2O/Cu(111) interface. The adsorbed hydroxyl species blocked O-O bond cleavage that would dehydrogenate methoxy groups to carbon monoxide and carbon dioxide, and it directly converted this species to methanol, while oxygen reoxidized the reduced surface. Water adsorption also displaced the produced methanol into the gas phase.

Editorial summary: A water boost for methanol synthesis. Model catalysts based on metals and metal oxides can dissociate methane (CH4) at room temperature, converting it directly to methanol (CH3OH). Liu et al. show that for one of these catalysts, an “inverted” CeOx-Cu2O oxide on Cu(111), water tunes the selectivity from forming CO and CO2 to forming surface CH3O groups, as revealed by ambient-pressure x-ray photoelectron spectroscopy. Theoretical modeling showed that adsorbed water blocks O2 dissociation and O2 instead oxidizes the reduced catalyst. Hydroxyl groups from water generate the CH3O species from dissociated CH4, and water then goes on to form and displace CH3OH to the gas phase.

Lodeiro, P., Rey-Castro, C., David, C., Achterberg, E.P., Puy, J., Gledhill, M., 2020. Acid-base properties of dissolved organic matter extracted from the marine environment. Science of The Total Environment 729, 138437.


Marine dissolved organic matter (DOM) plays a key role in the current and future global carbon cycle, which supports life on Earth. Trace metals such as iron, an essential micronutrient, compete with protons and major ions for the binding to DOM. These competitive effects and the DOM binding capacity are related to the DOM acid-base properties, which also influence DOM transport and reactivity in marine waters. Here we present the results of a complete set of acid-base titration experiments of a pre-concentrated marine DOM sample in the range 0.01 ≤ I ≤ 0.7 M and 3 ≤ pH ≤ 10. We characterize the obtained proton binding curves using a combination of the non-ideal competitive adsorption (NICA) isotherm and Donnan electrostatic model. Within the main chemical groups of marine DOM, the carboxylic distribution was accurately characterized from the obtained data (QmaxH, 1=2.52 mol·kg−1, logk¯H,1 = 3.26, m1 = 0.69 and b = 0.70). This carboxylic mode was found to be less acidic and more homogeneous than a generic fulvic acid, but the differences are consistent with the reported variability of fulvic acids of freshwater and terrestrial origin. We find that changes in temperature (down to 5.5 °C), and the presence of calcium or magnesium (at 0.01 M) resulted in no significant modification of the proton ion binding curves obtained at 25 °C and 0.7 or 0.1 M ionic strength, respectively. We demonstrate the relevance of proton binding parameters for the modelling of the system iron/marine DOM throughout a wide range of salinity and acidity conditions in the context of different future ocean scenarios.



We present variation patterns of trace elements within different sequences of the Ediacaran Doushantuo Formation (DST, 635–551 million years ago), and inside the cells of the earliest differentiated multicellular eukaryotic fossils of the Weng’an biota in the Weng’an County of Guizhou Province. The results showed that selenium is the most enriched and significantly varied trace element among the 22 trace elements throughout the DST, followed by arsenic. The highest selenium and arsenic content sequences are consistent with the first appeared sequence of the earliest differentiated multicellular eukaryotic fossils Megasphaera at the middle to upper parts of the DST. Nanoman secondary ion mass spectrometry analyses show that selenium and arsenic have an inhomogeneous and punctate distribution in the nucleus and cytoplasm. The nucleus has anomalously enriched levels of selenium and arsenic among the organelles. The selenium and arsenic concentrations exhibit a positive correlation with the diversity of fossilized Megasphaera. These new findings give us a clue that the anomalous enrichment of selenium and arsenic might contributes to the cell differentiation in Ediacaran Doushantuo period.

Losacco, G.L., Ismail, O., Pezzatti, J., González-Ruiz, V., Boccard, J., Rudaz, S., Veuthey, J.-L., Guillarme, D., 2020. Applicability of Supercritical fluid chromatography–Mass spectrometry to metabolomics. II–Assessment of a comprehensive library of metabolites and evaluation of biological matrices. Journal of Chromatography A 1620, 461021.


In this work, the impact of biological matrices, such as plasma and urine, was evaluated under SFC-HRMS in the field of metabolomics. For this purpose, a representative set of 49 metabolites were selected. The assessment of the matrix effects (ME), the impact of biological fluids on the quality of MS/MS spectra and the robustness of the SFC-HRMS method were each taken into consideration. The results have highlighted a limited presence of ME in both plasma and urine, with 30% of the metabolites suffering from ME in plasma and 25% in urine, demonstrating a limited sensitivity loss in the presence of matrices. Subsequently, the MS/MS spectra evaluation was performed for further peak annotation. Their analyses have highlighted three different scenarios: 63% of the tested metabolites did not suffer from any interference regardless of the matrix; 21% were negatively impacted in only one matrix and the remaining 16% showed the presence of matrix-belonging compounds interfering in both urine and plasma. Finally, the assessment of retention times stability in the biological samples, has brought into evidence a remarkable robustness of the SFC-HRMS method. Average RSD (%) values of retention times for spiked metabolites were equal or below 0.5%, in the two biological fluids over a period of three weeks.

In the second part of the work, the evaluation of the Sigma Mass Spectrometry Metabolite Library of Standards containing 597 metabolites, under SFC-HRMS conditions was performed. A total detectability of the commercial library up to 66% was reached. Among the families of detected metabolites, large percentages were met for some of them. Highly polar metabolites such as amino acids (87%), nucleosides (85%) and carbohydrates (71%) have demonstrated important success rates, equally for hydrophobic analytes such as steroids (78%) and lipids (71%). On the negative side,

very poor performance was found for phosphorylated metabolites, namely phosphate-containing compounds (14%) and nucleotides (31%).

Lourenço, R.A., Combi, T., Alexandre, M.d.R., Sasaki, S.T., Zanardi-Lamardo, E., Yogui, G.T., 2020. Mysterious oil spill along Brazil's northeast and southeast seaboard (2019–2020): Trying to find answers and filling data gaps. Marine Pollution Bulletin 156, 111219.


Large amounts of crude oil were found along Brazil's northeast and southeast seaboard from August 2019 to January 2020. Petroleum companies and oil tankers reported no accidents previously or during this period. The stranded oil on Brazilian beaches looks like tar; it has solid aspect and is denser than seawater. Chemical characterization of this oil showed that light hydrocarbons were still present, increasing the probability of negative effects to coastal organisms and ecosystems upon release in the water column. Diagnostic ratios, chromatogram pattern, and percentage-weathering plots proved that the oil samples share the same oil source. This work provides data for future comparison with oil samples that will likely be found stranded along the Brazilian shoreline in the years to come, helping to understand long term issues associated with the mysterious oil spill that made landfall in late 2019.

Lu, W.-N., He, Y., Wang, Y., Ke, S., 2020. Behavior of calcium isotopes during continental subduction recorded in meta-basaltic rocks. Geochimica et Cosmochimica Acta 278, 392-404.


In order to investigate the behavior of Ca isotopes during subduction, we report high precision Ca isotopic data of a suit of well-characterized meta-basaltic rocks from the Dabie-Sulu orogen, including six greenschists, six amphibolites and seven eclogites. Except two samples that may have been affected by carbonation alteration, greenschists, amphibolites and eclogites yield comparable δ44/42Ca values ranging from 0.36 to 0.41‰, 0.32 to 0.39‰ and 0.32 to 0.42‰, respectively. Overall, Dabie-Sulu meta-basaltic rocks have an average δ44/42Ca of 0.37 ± 0.06‰ (2SD, N = 17/19), comparable to terrestrial basalts previously reported (0.36 ± 0.05‰, 2SD; N = 34). Combined with no correlation of δ44/42Ca with H2O and Rb/TiO2, this study suggests that prograde metamorphism dehydration cannot significantly fractionate Ca isotopic compositions of meta-basaltic rocks. Given the comparable CaO contents in meta-basaltic rocks with increasing metamorphism grade, isotope fractionation may be limited by insignificant Ca loss during dehydration. Two heavy greenschists with δ44/42Ca of 0.46‰ and 0.49‰ also have high CO2 concentrations, indicating carbonation alteration that is evidenced by 0.04M HCl leaching experiments. The limited δ44/42Ca variation observed in the other metamorphic samples is most likely inherited from their igneous protoliths. Considering that terrestrial basalts have δ44/42Ca systematically lower than the upper mantle, subduction of mafic lithologies (e.g., oceanic slabs) thus could reflux light Ca isotopes back into the mantle and may create mantle heterogeneity.



Granulite-facies xenoliths entrained within igneous rocks shed a light on poorly understood yet critical questions about age, origin and history of the lower continental crust. Here, we present the first coupled in-situ U-Pb, Lu-Hf and O isotope data for the Precambrian zircons from fourteen deep-crustal xenoliths from the North China craton. The geochronological data demonstrates that the oldest lower crustal remnants formed at ∼3.82 Ga and related magmatism continued until ∼3.55 Ga. The Eo-Paleoarchean zircons, with exception of one analysis, have subchondritic initial Hf isotopes with negative εHf(t) and are characterized by normal mantle to elevated δ18O values (5.37–6.90‰), indicating a development of a low Lu/Hf reservoir and hydrosphere-crust interactions in the early Earth. Magmatic zircons from lower crustal xenoliths of North China define a strongly episodic distribution of ages at 3.82–3.55 Ga, ∼2.7 Ga, ∼2.5 Ga and 1.95–1.85 Ga and a non-linear Hf isotope-age array for nearly 2 Gyr, indicating episodic crustal generation and reworking through time. The lower crustal xenoliths record a change in zircon O isotope compositions from a restricted range at 3.8–2.6 Ga to more variable after ∼2.5 Ga. Both heavier (δ18O up to 10.25‰) and lighter (δ18O low to 2.16‰) O isotope compositions than the normal mantle are observed in ∼2.5 Ga magmatic zircons. The secular change in zircon O isotopes documents an increase in recycling rate of surface-derived materials (including high-δ18O sediments, weathered and altered rocks and low-δ18O altered oceanic crust) into magma sources at the end of Archean, which, in turn, is possibly linked to modern style subduction processes and maturation of the crust at that time.

Maagi, M.T., Lupyana, S.D., Jun, G., 2020. Nanotechnology in the petroleum industry: Focus on the use of nanosilica in oil-well cementing applications - A review. Journal of Petroleum Science and Engineering 193, 107397.


The usage of nanotechnology has gained widespread attention in the petroleum industry in recent years. Existing studies indicate that incorporation of nanoparticles into the cement matrix improves cement properties such as strength, microstructure and durability. This improvement is attributed to the nanoscale size and high specific surface area of nanoparticles. To fulfill the purpose of this paper, previous studies associated with the role of nanotechnology in the petroleum industry, with specific attention to the use of nanosilica in oil-well cementing applications are reviewed. The effect of silica nanoparticles on both fresh and hardened cement properties are investigated and presented. The study has revealed that the addition of nanosilica improves the performance of cement, ensuring adequate zonal isolation and extended well life. These findings highlight the potential use of nanotechnology in the petroleum industry. In terms of future study, more investigation and experimentation into the use of nanosilica in oil-well cementing is strongly recommended.

Madeira, N.C.L., Rainha, K.P., Mendonça, J., Lacerda, V., Chinelatto, L.S., de Menezes, S.M.C., Porto, C.F.d.C., Pinto, F.E., Filgueiras, P.R., Romão, W., Neto, Á.C., 2020. Study of the influence of resins on the asphaltene aggregates by 1H DOSY NMR. Energy & Fuels 34, 5679-5688.


Aggregation and precipitation of asphaltenes are relevant concerns during the extraction and processing of petroleum because of the severe damage they cause to the equipment for crude oil transportation. Studies show that the presence of resins can contribute to smaller aggregate formation and thereby reduce the asphaltene precipitation. Herein, we showed the investigation of the influence of resins on the size of asphaltene aggregates by diffusion-ordered spectroscopy (DOSY). The asphaltenes were extracted from crude oil by precipitation with n-heptane. The resins were extracted from the maltene fraction, and their samples were analyzed by 1H and 13C nuclear magnetic resonance spectroscopy. Aromatic and aliphatic hydrogen and carbon contents were estimated, including their subdivisions. From these results, we estimated the aromaticity factor (fa), the number of naphthenic rings (RN), the number of total rings (RT), the average length of alkyl chains (Nalk), the aromatic condensation index (Φ), and the aromatic condensation degree (ξ), which were used to determine the asphaltene architecture. The asphaltene chemical structures were suggested for each sample (asphaltene 1 was predominantly continental, while asphaltenes 2 and 3 were archipelago), and the relative diffusion of asphaltene aggregates and resins in toluene-d8 was determined by DOSY. Asphaltenes, resins, and their mixtures were prepared in toluene-d8 at concentrations ranging from 5 to 7 wt %. The aspthaltenes/resins mixture proportions were 7:1; 7:2; 7:3; 1:1; and 2:1 wt %. Generally, the relative diffusion values of the solutions increased because of the addition of resins (asphaltenes/resins 7:3 > 7:2 > 7:1 wt %), indicating that their presence favors the formation of smaller aggregates.

Maeda, A.H., Nishi, S., Hatada, Y., Ohta, Y., Misaka, K., Kunihiro, M., Mori, J.F., Kanaly, R.A., 2020. Chemical and genomic analyses of polycyclic aromatic hydrocarbon biodegradation in Sphingobium barthaii KK22 reveals divergent pathways in soil sphingomonads. International Biodeterioration & Biodegradation 151, 104993.


Polycyclic aromatic hydrocarbons (PAHs) are hazardous pollutants that are biodegraded by soil bacteria and the soil sphingomonads are thought to be major contributors to PAH biodegradation. To predict PAH environmental fates it is necessary to understand the chemistry and genetics of PAH biodegradation by sphingomonads. When the soil sphingomonad Sphingobium barthaii KK22 was exposed to low molecular weight (LMW) PAHs and biotransformation products were investigated by comprehensive chemical analyses, at least twenty products were identified by different techniques and both intradiol- and extradiol-aromatic ring cleavage pathways were found to be active in this organism. Sphingomonads, a large and diverse group, have been studied in regard to PAH biodegradation, however intradiol-ring cleavage of LMW PAHs has never been reported. Whole genome sequencing and prediction of S. barthaii KK22 functional genes revealed sets of aromatic ring-hydroxylating oxygenases and PAH biotransformation genes. Combined with chemical analyses results, novel, near complete PAH biotransformation pathways for soil sphingomonads were constructed. In conjunction with quantitative assays, a comprehensive view of PAH biodegradation was obtained that revealed divergent downstream pathways that advanced our understanding of the PAH biotransformation capabilities of these versatile soil bacteria and shall aid in predictions of PAH environmental fate during soil bioremediation.


https://doi.org/10.1111/1462-2920.14871

Marine microorganisms play a fundamental role in the global carbon cycle by mediating the sequestration of organic matter in ocean waters and sediments. A better understanding of how biological factors, such as microbial community composition, influence the lability and fate of organic matter is needed. Here, we explored the extent to which organic matter remineralization is influenced by species specific metabolic capabilities. We carried out aerobic time series incubations ‐ ‐of Guaymas Basin sediments to quantify the dynamics of carbon utilization by two different heterotrophic marine isolates (Vibrio splendidus 1A01; Pseudoalteromonas sp. 3D05). Continuous measurement of respiratory CO2 production and its carbon isotopic compositions (13C and 14C) shows species specific differences in the rate, quantity and type of organic matter remineralized. Each ‐species was incubated with hydrothermally influenced versus unimpacted sediments, resulting in a ‐~2 fold difference in respiratory CO‐ 2 yield across the experiments. Genomic analysis indicated that the observed carbon utilization patterns may be attributed in part to the number of gene copies encoding for extracellular hydrolytic enzymes. Our results demonstrate that the lability and remineralization of organic matter in marine environments is not only a function of chemical composition and/or environmental conditions, but also a function of the microorganisms that are present and active.


https://doi.org/10.1038/s41598-020-65176-w

Precambrian cellular remains frequently have simple morphologies, micrometric dimensions and are poorly preserved, imposing severe analytical and interpretational challenges, especially for irrefutable attestations of biogenicity. The 1.88 Ga Gunflint biota is a Precambrian microfossil assemblage with different types and qualities of preservation across its numerous geological localities and provides important insights into the Proterozoic biosphere and taphonomic processes. Here we use synchrotron-based ptychographic X-ray computed tomography to investigate well-preserved carbonaceous microfossils from the Schreiber Beach locality as well as poorly-preserved, iron-replaced fossil filaments from the Mink Mountain locality, Gunflint Formation. 3D nanoscale imaging with contrast based on electron density allowed us to assess the morphology and carbonaceous composition of different specimens and identify the minerals associated with their preservation based on retrieved mass densities. In the Mink Mountain filaments, the identification of mature kerogen and maghemite rather than the ubiquitously described hematite indicates an influence from biogenic organics on the local maturation of iron oxides through diagenesis. This non-destructive 3D approach to microfossil composition at the nanoscale within their geological context represents a powerful approach to assess the taphonomy and biogenicity of challenging or poorly preserved traces of early microbial life, and may be applied effectively to extraterrestrial samples returned from upcoming space missions.

Marcantonio, F., Hostak, R., Hertzberg, J.E., Schmidt, M.W., 2020. Deep equatorial Pacific Ocean oxygenation and atmospheric CO2 over the last ice age. Scientific Reports 10, 6606.

https://doi.org/10.1038/s41598-020-63628-x

Ventilation of carbon stored in the deep ocean is thought to play an important role in atmospheric CO2 increases associated with Pleistocene deglaciations. The presence of this respired carbon has been recorded by an array of paleoceanographic proxies from various locations across the global ocean. Here we present a new sediment core from the Eastern Equatorial Pacific (EEP) Ocean spanning the last 180,000 years and reconstruct high-resolution 230Th-derived fluxes of 232Th and excess barium, along with redox-sensitive uranium concentrations to examine past variations in dust delivery, export productivity, and bottom-water oxygenation, respectively. Our bottom-water oxygenation record is compared to other similar high-resolution records from across the Pacific and in the Southern Ocean. We suggest that the deep Pacific is a site of respired carbon storage associated with periods of decreased global atmospheric CO2 concentration during the LGM, confirming the conclusions from a wealth of previous studies. However, our study is the first to show a similar relationship beyond the last glacial, extending to at least 70,000 years.

Marrubini, G., Dugheri, S., Cappelli, G., Arcangeli, G., Mucci, N., Appelblad, P., Melzi, C., Speltini, A., 2020. Experimental designs for solid-phase microextraction method development in bioanalysis: A review. Analytica Chimica Acta 1119, 77-100.


This review is an update of a previous review in 2009 and covers publications from 2009 to 2019. The review focuses on experimental design, referred to as the design of experiments (DoE), used in developing bioanalytical solid-phase microextraction (SPME) methods. Characteristics of different SPME approaches are illustrated and critically discussed. The literature selection evidences that two-level full factorial designs, with a limited number of factors (<5), are most frequently used for preliminary factors screening. When applying the response surface methodology for the quantitative assessment of factorial effects, few quadratic models were used. The most popular were the rotatable central composite and Box-Benkhen designs. Models including more than four factors, such as fractional factorial designs (including the Plackett-Burman and Taguchi designs), were rarely used. Definitive screening and D-Optimal designs were not reported anywhere in the literature selection.

When examining the diagnostic criteria used to evaluate different model’s quality and validity, it was apparent the researchers relied heavily on commercial software for experimental design, analysis, and reporting of the results.

Marshall, J.E.A., Lakin, J., Troth, I., Wallace-Johnson, S.M., 2020. UV-B radiation was the Devonian-Carboniferous boundary terrestrial extinction kill mechanism. Science Advances 6, eaba0768.


There is an unexplained terrestrial mass extinction at the Devonian-Carboniferous boundary (359 million years ago). The discovery in east Greenland of malformed land plant spores demonstrates that the extinction was coincident with elevated UV-B radiation demonstrating ozone layer reduction. Mercury data through the extinction level prove that, unlike other mass extinctions, there were no planetary scale volcanic eruptions. Importantly, the Devonian-Carboniferous boundary terrestrial mass extinction was coincident with a major climatic warming that ended the intense final

glacial cycle of the latest Devonian ice age. A mechanism for ozone layer reduction during rapid warming is increased convective transport of ClO. Hence, ozone loss during rapid warming is an inherent Earth system process with the unavoidable conclusion that we should be alert for such an eventuality in the future warming world.

Martinez, J.F., Schoeggl, F.F., Maini, B.B., Yarranton, H.W., 2020. Investigation of mechanisms for gravity drainage of heavy oil and solvent mixtures in a Hele-Shaw cell. Energy & Fuels 34, 5823-5837.


One reason it is challenging to predict oil recovery rates from solvent-based heavy oil recovery methods is that the interplay of the mass transfer and convective flow mechanisms is not well understood. An apparatus was designed and commissioned to investigate these mechanisms in a controllable flow geometry. The apparatus consisted of a Hele-Shaw cell (parallel glass plates) that was partially filled with bitumen and rotated to set a target initial slope of the bitumen layer. Toluene was fed at the top of the bitumen at a constant volumetric flow rate. The flow rate, composition, and properties of the drained liquid were measured over time, and photographs of the bitumen profile were taken periodically. The measurements were performed at ambient conditions at injection flow rates from 0.1 to 2 cm3/min, gap widths of 0.5 and 1 mm, and initial angles of inclination between 30 and 45°. The data were modeled with a two-dimensional numerical model in which the fluid was divided into columns, each with a solvent (drainage) layer and a bitumen layer. The following recovery mechanisms were identified: (1) diffusion of bitumen into the drainage layer represented with Fick’s Law, (2) open duct flow of the drainage layer represented as a falling film, and (3) flow of the bitumen phase settling under its own weight. The model with a single fixed tuning parameter matched all of the bitumen production rates with an average deviation of 7.4%.

Materese, C.K., Nuevo, M., Sandford, S.A., Bera, P.P., Lee, T.J., 2020. The production and potential detection of hexamethylenetetramine-methanol in space. Astrobiology 20, 601-616.

https://doi.org/10.1089/ast.2019.2147

Numerous laboratory studies of astrophysical ice analogues have shown that their exposure to ionizing radiation leads to the production of large numbers of new, more complex compounds, many of which are of astrobiological interest. We show here that the irradiation of astrophysical ice analogues containing H2O, CH3OH, CO, and NH3 yields quantities of hexamethylenetetramine-methanol (hereafter HMT-methanol; C7N4H14O) that are easily detectible in the resulting organic residues. This molecule differs from simple HMT, which is known to be abundant in similar ice photolysis residues, by the replacement of a peripheral H atom with a CH2OH group. As with HMT, HMT-methanol is likely to be an amino acid precursor. HMT has tetrahedral (Td) symmetry, whereas HMT-methanol has C1 symmetry. We report the computed expected infrared spectra for HMT and HMT-methanol obtained using ab initio quantum chemistry methods and show that there is a good match between the observed and computed spectra for regular HMT. Since HMT-methanol lacks the high symmetry of HMT, it produces rotational transitions that could be observed at longer wavelengths, although establishing the exact positions of these transitions may be challenging. It is likely that HMT-methanol represents an abundant member of a larger family of functionalized HMT molecules that may be present in cold astrophysical environments.

Mathews, R.P., Singh, B.D., Singh, V.P., Singh, A., Singh, H., Shivanna, M., Dutta, S., Mendhe, V.A., Chetia, R., 2020. Organo-petrographic and geochemical characteristics of Gurha lignite deposits, Rajasthan, India: Insights into the palaeovegetation, palaeoenvironment and hydrocarbon source rock potential. Geoscience Frontiers 11, 965-988.


The sedimentary sequence containing lignite deposits in Gurha quarry of the Bikaner-Nagaur Basin (Rajasthan) has been investigated. The samples from lignite and allied shale horizons were evaluated for petrographical, palynological, palynofacies and organic geochemical inferences, to depict the source flora and to reconstruct the palaeodepositional conditions prevailed during the sedimentation. An assessment for the hydrocarbon generation potential of these deposits has also been made. The results revealed the dominance of huminite macerals and phytoclasts organic matter (OM) indicating the existence of forested vegetation in the vicinity of the depositional site. A relatively high terrigenous/aquatic ratio (TAR) and the carbon preference index (CPI) are also suggesting the contribution of higher plants in the peat formation. However, the n-alkane distributions, maximizing at n-C17 and n-C29, showed inputs from the algal communities along with the higher plant derived organic matters. Recovered palynomorphs of the families Onagraceae, Meliaceae, Arecaceae, Rhizophoraceae, Rubiaceae, Ctenolophonaceae, etc. together with oleanene and ursane types of triterpenoids suggest the contribution from angiosperms source vegetation. Interestingly, the presence of Araucareaceae and Podocarpaceae pollen grains shows the existence of gymnosperms vegetation. Further, the presence of tetracyclic diterpanes; demethylated ent-beyerane, sandaracopimarane, pimarane, and Kaurane type of compounds confirms the contribution of conifers. The variation in the values of the coefficient of non-equality (H: 0.68%–7.56%), the standard deviation (δ: 0.04%–0.16%) and the coefficient of variability (V: 16.10%–46.47%), also shows the heterogeneity in the source organic matter.

The various petrographical indices, palynological entities, and geochemical parameters indicate that the peat-forming vegetation was accumulated under a mixed environment and fluctuating hydrological settings. The interpretation of palynofacies data on APP (Amorphous organic matter-Phytoclast-Palynomorphs) diagram suggests that the accumulation of organic matter occurred in a dysoxic-suboxic condition in a proximal (to land) setting with the shift to an anoxic condition in distal setting towards the termination of sedimentation. The huminite (ulminite) reflectance (R r) values (av. 0.28%) showed a good relationship with average Tmax value (414 °C), suggesting the immaturity. The TOC content ranges of 13–59 wt.%, and HI values vary between 101 and 546 mg HC/g TOC in the studied samples. Collectively, the studied lignite and shale samples have the admixed kerogens (Type III–II) and exhibit the ability to generate the gaseous to oil hydrocarbons upon maturation.

Mattiangeli, V., Cooke, N.P., Ó Maoldúin, R., Sikora, M., Mulhall, I., Bradley, D.G., Teasdale, M.D., 2020. Genomic analysis of Irish bog butter. Journal of Archaeological Science: Reports 31, 102368.


The deposition of butter in bogs is well documented in the archaeological record, from prehistoric to post-medieval times. To our knowledge this pilot study presents the first genetic analysis of bog butter, using technological advances that demonstrate the ability to reveal new information from substrates previously untested for genetic data. In this analysis, DNA was successfully isolated from three Irish bog butter samples using a novel approach. Furthermore, high throughput shotgun DNA

sequencing was successful and bovine DNA sequences were recovered from all three samples of bog butter. Investigation of the environmental DNA (metagenomic analysis) recovered from the bog butter samples clearly identified similarities between samples taken from the same bog butter. This pilot analysis suggests that bog butter could be used as a substrate for DNA extraction, thereby furthering our understanding of diet and animal use in the past.

Matyushin, D.D., Sholokhova, A.Y., Karnaeva, A.E., Buryak, A.K., 2020. Various aspects of retention index usage for GC-MS library search: A statistical investigation using a diverse data set. Chemometrics and Intelligent Laboratory Systems 202, 104042.


This work is devoted to the large-scale statistical evaluation of various aspects of using the retention index for GC-MS library search with a diverse data set. A search in a large library often does not give a correct compound even if a library contains it. One of the methods to improve a spectral library search procedure is to use the retention index information. The aim of this study is to explore some statistical peculiarities which can be helpful for development of automated software which uses a library search of diverse completely unknown compounds in a large database. A data set that was used in this work as a source of queries contains ~11 thousand spectra of compounds which belong to diverse chemical classes. Six equations for matching reference and experimental “retention index – spectrum” pairs were compared. It was found that good results can be obtained when a linear equation for similarity of pairs is used. Similarity of pairs is found as a sum of spectral similarity and of a product of a negative adjustable weight parameter and the absolute difference between reference and query retention indices. This equation performs equal or better than much more complex equations which contain two instead of one adjustable parameters. Widely used threshold-based approach, when candidates with high retention index deviation are rejected, performs worse than other equations. The use of predicted with neural networks retention indices as reference was also considered. Modern universal retention prediction models which are applicable to a wide variety of compounds are still quite inaccurate comparing with values from databases, but these predicted values allow to improve a library search as well. When predicted retention indices are used as reference, the linear equation for matching “retention index – spectrum” pairs also performs equal or better than other equations. The distribution of differences between query indices and reference indices (both calculated and experimental) was found close to exponential distribution near zero. The dependence of a fraction of correct identifications on the reference retention indices accuracy was studied. The addition of random noise with double exponential distribution to exact values was used to create “reference” retention indices with the predefined accuracy. The use of the molecular mass and molecular formula as additional constraints during a library search was also considered.

Medina, O.E., Gallego, J., Olmos, C.M., Chen, X., Cortés, F.B., Franco, C.A., 2020. Effect of multifunctional nanocatalysts on n-C7 asphaltene adsorption and subsequent oxidation under high-pressure conditions. Energy & Fuels 34, 6261-6278.


This study was carried out to evaluate the effect of high pressure on the oxidation kinetics of n-heptane asphaltenes in the presence and absence of AuPd/Ce0.62Zr0.38O2 catalysts. Bimetallic Au–Pd

catalysts with Au/Pd molar ratios from 3.5 to 9.6 were synthesized by deposition–precipitation of Au and followed by incipient wetness impregnation of Pd (3:1AuPd and 10:1AuPd). Adsorption isotherms between hydrocarbons and nanocatalysts were constructed varying the initial asphaltene concentration from 100 to 1500 mg·L–1. Subsequent oxidation was evaluated using thermogravimetric analysis under an air atmosphere, at different pressures from 0.084 to 6.0 MPa in a wide temperature range between 100 and 800 °C. Kinetic parameters were calculated using a first-order kinetic model, considering the system pressure. Adsorption affinity increases in the order support < 3:1AuPd < 10:1AuPd. The catalytic activity of the nanocatalyst was highly dependent on the employed temperature and pressure. Their presence reduces the n-C7 asphaltene decomposition temperature from 450 °C to temperatures below 200 °C for all catalysts used at 6.0 MPa. The main decomposition peaks are presented at 150, 170, and 210 °C for 10:1AuPd, 3:1AuPd, and support, at 6.0 MPa, respectively. Besides, the oxygen chemisorption (OC) region is favored as the material has a greater catalytic activity, increasing from 9.0 to 14.0% (on the load asphaltene basis calculation) for the support and 10:1AuPd catalyst. This was corroborated by the activation energy, which is reduced by more than 30% for all pressures evaluated with the best system. Besides, 89.0 and 80.0% of the mass are lost in the decomposition of the chemisorbed oxygen (DCO) thermal event for the 10:1AuPd and 3:1AuPd nanocatalysts, respectively. Finally, first and second combustions were carried out at temperatures below 240 °C at 6.0 MPa for the 10:1AuPd system, which is a very promising result to determine the reaction pathway for the heavy and extraheavy crude oils during EOR application.



Using tobacco straw (Ts) and lignin as the sole carbon source, a strain was isolated from Ts and identified as Bacillus amyloliquefaciens SL-7 by 16S rDNA gene-sequencing technology.7-day incubation of Bacillus amyloliquefaciens SL-7 can reduce the chemical oxygen demand (COD) by 69.35% in lignin mineral salt medium. The activity of Manganese peroxidase (MnP) reached maximum level 258.57 U L−1, and Lignin peroxidase (Lip) was 422.68 U L−1 at 4th day. The highest Laccase (Lac) activity (55.95 U L−1) was observed at 3th day. After straw-liquid fermentation degradation of 15 days, the bacterial could degrade 28.55% lignin of the straw which was close to that of fungi. Compared with the control group and effective microorganisms (EM) group, the lignin degradation rate in Bacillus amyloliquefaciens SL-7 group increased by 22.26% and 11.70% at 41-day compost fermentation of tobacco straw. These show the strain has strong lignin degradation performance.



The short-lived 182Hf-182W system has been used to constrain the early Earth’s accretion and differentiation. This paper reports high precision W isotopic compositions and trace element

concentrations for Archean (4.0–3.0 Ga) intermediate to felsic rocks from the Slave, North China, and Kaapvaal cratons to discuss early Earth differentiation and mantle mixing processes. The 4.0–3.8 Ga diorite and trondhjemite samples from the Acasta Gneiss Complex (AGC) in the Slave Craton and Anshan Complex in the North China Craton have positive μ182W values ranging from 8.3 ± 3.6 to 14.5 ± 4.0, whereas the 3.36–2.95 Ga TTG rocks from the North China Craton have a uniform modern mantle-like μ182W value of 0.7 ± 3.9 (2 SD, n = 11); with one exception, the 3.32 Ga old sample F28-2, which has a positive μ182W anomaly (7.3 ± 3.9 and 13.0 ± 3.2 for two individual analyses). The Earth’s oldest potassic granites, occurring as conglomerates in the Moodies Group, an intrusive trondhjemite, and an amphibolite with ages of ~3.55 Ga in the Kaapvaal Craton exhibit W isotopic compositions indistinguishable from what is proposed for the modern mantle. The positive 182W anomalies in the 4.0–3.8 Ga rocks could possibly be the result of either early mantle differentiation that occurred within the lifetime of 182Hf or a partial lack of late accreted material. The signature of 182W excess in the 3.32 Ga sample (F28-2) is inherited from earlier crust, presumably similar to the 3.8 Ga TTGs, either by melting or crustal contamination. The transition in μ182W values from positive to near-zero would indicates that a significant event occurred at ∼3.6 Ga which caused efficient mixing of early differentiated mantle and late accreted material, possibly indicating the transition of tectonic regimes from plume to plate tectonics on the Earth.

Memon, A., Li, A., Jacqueline, N., Kashif, M., Ma, M., 2020. Study of gas sorption, stress effects and analysis of effective porosity and permeability for shale gas reservoirs. Journal of Petroleum Science and Engineering 193, 107370.


The gas sorption capacity, effective porosity, and effective permeability are important to shale gas reservoir characterization, gas-in-place estimation, and production behavior prediction. Previous studies have ignored the absorption gas in gas sorption measurements; however, the absorption gas is dissolved into kerogen and cannot be underestimated. In this study, experiments are performed on shale samples to quantify the gas sorption capacity with new sights and to analyze the effective porosity and permeability in adsorbed and absorbed gas considering gas sorption and stress impacts. Then, data are also obtained for quantitative analysis. This study revealed that the proposed gas sorption model (sum of adsorption and absorption of gases) is as accurate as the Langmuir model. Based on this model, converted excessive to absolute gas sorption and the contribution of the absorption gas to the total gas sorption are estimated. The porosity and permeability in adsorbed/absorbed and sorption gas increases with increasing pore pressure, whereas the effective porosity and permeability decreases with increasing pore pressure. The effective porosity is affected more at low pressure, whereas it is almost the same or changes slightly at higher pressure; however, the effective permeability is dependent on the adsorbed porosity. The amount of absorbed gas increases linearly with increasing pore pressure, and that it followed Henry's law, whereas the effective absorbed porosity decreases linearly with increasing pore pressure. The effective absorbed permeability increases at a lower rate at low pressure, while at a high pressure, the rate of increase is higher. It is also observed that the adsorbed/absorbed porosity, such as gas sorption, is a function of the total organic carbon and specific surface area. However, both parameters vary with kerogen quality. The combined impact of gas sorption and stress may change the controlling factors of shale gas properties and enable the accurate measurement of the effective porosity and permeability.



Recent advances in shale oil development have largely outpaced efforts to manage associated greenhouse gas (GHG) emissions that pose significant environmental risks. In this work, we explore opportunities to leverage synergies between oil recovery and emission reduction targets through a regional case study in the Eagle Ford shale, where natural gas co-produced with oil (i.e. casinghead gas) is still frequently flared at the wellhead rather than sold due to a lack of pipeline infrastructure. We demonstrate that reinjecting casinghead gas for enhanced oil recovery (EOR) would be a profitable and environmentally favorable alternative to flaring, particularly considering the extent of oil that remains trapped in shales following primary recovery. Based on our projections of oil and casinghead gas production through 2025, this approach could prevent a cumulative 370 Bcf of flared gas (or abated emissions of 22 Mt CO2 eq) while recovering an additional 42.5 MMbbl of oil. Supplementing casinghead gas with anthropogenic CO2 emissions from natural gas processing facilities in the Haynesville shale could produce another 46.1 MMbbl of oil while sequestering 19.8 Mt CO2. We discuss the operational costs of this strategy, which could be competitive with traditional CO2–EOR (particularly in a carbon-constrained economy), but motivating industry adoption over cheaper conventional EOR approaches will require policy intervention and market assurances to mitigate long-term risks.



Untargeted molecular analyses of complex mixtures are relevant for many fields of research, including geochemistry, pharmacology, and medicine. Ultrahigh-resolution mass spectrometry is one of the most powerful tools in this context. The availability of open scripts and online tools for specific data processing steps such as noise removal or molecular formula assignment is growing, but an integrative tool where all crucial steps are reproducibly evaluated and documented is lacking. We developed a novel, server-based tool (ICBM-OCEAN, Institute for Chemistry and Biology of the Marine Environment, Oldenburg–complex molecular mixtures, evaluation & analysis) that integrates published and novel approaches for standardized processing of ultrahigh-resolution mass spectrometry data of complex molecular mixtures. Different from published approaches, we offer diagnostic and validation tools for all relevant steps. Among other features, we included objective and reproducible reduction of noise and systematic errors, spectra recalibration and alignment, and identification of likeliest molecular formulas. With 15 chemical elements, the tool offers high flexibility in formula attribution. Alignment of mass spectra among different samples prior to molecular formula assignment improves mass error and facilitates molecular formula confirmation with the help of isotopologues. The online tool and the detailed instruction manual are freely accessible at www.icbm.de/icbm-ocean.


https://doi.org/10.1038/s41598-020-64743-5

Reconstructing long-term continental temperature change provides the required counterpart to age equivalent marine records and can reveal how terrestrial and marine temperatures were related during times of extreme climate change such as the Miocene Climatic Optimum (MCO) and the following Middle Miocene Climatic Transition (MMCT). Carbonate clumped isotope temperatures (T(Δ47)) from 17.5 to 14.0 Ma Central European paleosols (Molasse Basin, Switzerland) display a temperature pattern during the MCO that is similar to coeval marine temperature records. Maximum temperatures in the long-term soil T(Δ47) record (at 16.5 and 14.9 Ma) lag maximum ocean bottom water temperatures, lead global ice volume, and mark the initiation of minimum global ice volume phases. The suggested onset of the MMCT, deduced by a marked and rapid decline in Molasse Basin soil temperatures is coeval with cooling reported in high-latitudinal marine records. This is best explained by a change in the seasonal timing of soil carbonate formation that was likely driven by a modification of rainfall seasonality and thus by a major reorganization of mid-latitude atmospheric circulation across Central Europe. In particular, our data suggest a strong climate coupling between the North Atlantic and Central Europe already in the middle Miocene.

Miao, Q., Xu, C., Hao, F., Yin, J., Wang, Q., Xie, M., Cao, Y., Zou, H., 2020. Roles of fault structures on the distribution of mantle-derived CO2 in the Bohai Bay basin, NE China. Journal of Asian Earth Sciences 197, 104398.


Based on studies on the contents, origin and filling history of CO2, and the seismic interpretation of the Bohai Sea, the sea area of the Bohai Bay basin, the distribution of mantle-derived CO2 and roles of fault structures have been examined in this study. Mantle-derived CO2 is mainly distributed in the structures within the Bozhong area, the center of the Bohai Sea. Laser Raman spectrum shows that CO2 inclusions are symbiotic with hydrocarbon inclusions with a charging time no earlier than 5.1 Ma. Late-stage (5.1–0 Ma) active basement faults are the major pathways for the migration of mantle-derived CO2. The intensity of the activity influences the CO2 content. Abundant CO2 occurs in the structures with basement faults that have relatively high fault activity rate (FAR) values. Along the basement fault, high CO2 content appears near the segments with high FAR values. Fault combination patterns affect the accumulation layers of mantle-derived CO2. Structures with fault combination patterns that resemble a “flower” or “Y” commonly accumulate CO2 in Cenozoic shallow layers as well. The branch faults that intersect with basement faults facilitate the adjustment of CO2 from deep to shallow layers. The uplifted mantle is the deep tectonic context, and the upwelling mantle magma is the source of the development of mantle-derived CO2. Below the middle crust, mantle-derived CO2 may be vertically transported along the lithosphere-scale strike–slip faults. Within the middle and upper crust, the late-stage active basement faults are the major conduits for mantle-derived CO2.

Miller, K.G., Browning, J.V., Schmelz, W.J., Kopp, R.E., Mountain, G.S., Wright, J.D., 2020. Cenozoic sea-level and cryospheric evolution from deep-sea geochemical and continental margin records. Science Advances 6, eaaz1346.


Using Pacific benthic foraminiferal δ18O and Mg/Ca records, we derive a Cenozoic (66 Ma) global mean sea level (GMSL) estimate that records evolution from an ice-free Early Eocene to Quaternary bipolar ice sheets. These GMSL estimates are statistically similar to “backstripped” estimates from continental margins accounting for compaction, loading, and thermal subsidence. Peak warmth, elevated GMSL, high CO2, and ice-free “Hothouse” conditions (56 to 48 Ma) were followed by “Cool Greenhouse” (48 to 34 Ma) ice sheets (10 to 30 m changes). Continental-scale ice sheets (“Icehouse”) began ~34 Ma (>50 m changes), permanent East Antarctic ice sheets at 12.8 Ma, and bipolar glaciation at 2.5 Ma. The largest GMSL fall (27 to 20 ka; ~130 m) was followed by a >40 mm/yr rise (19 to 10 ka), a slowing (10 to 2 ka), and a stillstand until ~1900 CE, when rates began to rise. High long-term CO2 caused warm climates and high sea levels, with sea-level variability dominated by periodic Milankovitch cycles.

Miller, T.E., Beneyton, T., Schwander, T., Diehl, C., Girault, M., McLean, R., Chotel, T., Claus, P., Cortina, N.S., Baret, J.-C., Erb, T.J., 2020. Light-powered CO2 fixation in a chloroplast mimic with natural and synthetic parts. Science 368, 649-654.


Abstract: Nature integrates complex biosynthetic and energy-converting tasks within compartments such as chloroplasts and mitochondria. Chloroplasts convert light into chemical energy, driving carbon dioxide fixation. We used microfluidics to develop a chloroplast mimic by encapsulating and operating photosynthetic membranes in cell-sized droplets. These droplets can be energized by light to power enzymes or enzyme cascades and analyzed for their catalytic properties in multiplex and real time. We demonstrate how these microdroplets can be programmed and controlled by adjusting internal compositions and by using light as an external trigger. We showcase the capability of our platform by integrating the crotonyl–coenzyme A (CoA)/ethylmalonyl-CoA/hydroxybutyryl-CoA (CETCH) cycle, a synthetic network for carbon dioxide conversion, to create an artificial photosynthetic system that interfaces the natural and the synthetic biological worlds.

Editor's summary: Hybrid approach catches light. Plant chloroplasts enclose two major photosynthetic processes: light reactions, which generate the energy carriers adenosine triphosphate and reduced nicotinamide dinucleotide phosphate (NADPH), and dark reactions, which use these molecules to fix carbon dioxide and build biomass. Miller et al. appropriated natural components, thylakoid membranes from spinach, for the light reactions and showed that these could be coupled to a synthetic enzymatic cycle that fixes carbon dioxide within water-in-oil droplets. The composition of the droplets could be tuned and optimized and the metabolic activity monitored in real time by NADPH fluorescence (see the Perspective by Gaut and Adamala). These chloroplast-mimicking droplets bring together natural and synthetic components in a small space and are amenable to further functionalization to perform complex biosynthetic tasks.



Since the dawn of space exploration, the survivability of terrestrial life in outer space conditions has attracted enormous attention. Space technology has enabled the development of advanced space exposure facilities to investigate in situ responses of microbial life to the stress conditions of space during interplanetary transfer. Significant progress has been made toward the understanding of the effects of space environmental factors, e.g., microgravity, vacuum and radiation, on microorganisms exposed to real and simulated space conditions. Of extreme importance is not only knowledge of survival potential of space-exposed microorganisms, but also the determination of mechanisms of survival and adaptation of predominant species to the extreme space environment, i.e., revealing the molecular machinery, which elicit microbial survivability and adaptation. Advanced technologies in –omics research have permitted genome-scale studies of molecular alterations of space-exposed microorganisms. A variety of reports show that microorganisms grown in the space environment exhibited global alterations in metabolic functions and gene expression at the transcriptional and translational levels. Proteomic, metabolomic and especially metabolic modeling approaches as essential instruments of space microbiology, synthetic biology and metabolic engineering are rather underrepresented. Here we summarized the molecular space-induced alterations of exposed microorganisms in terms of understanding the molecular mechanisms of microbial survival and adaptation to drastic outer space environment.

Miranda, M.A., Subramani, H.J., Mohammad, S.A., Aichele, C.P., 2020. Kinetics of gas evolution from supersaturated oils at elevated pressures and temperatures. Energy & Fuels 34, 5537-5544.


The design of gas–liquid separators is commonly based on the American Petroleum Institute (API) 12J guidelines. Although these guidelines have been useful, they may fail to provide sufficient time required for complete gas–liquid separation and may lead to problems, such as gas carry-under (GCU), in some cases. Therefore, an accurate understanding of gas evolution rates (volumetric mass transfer coefficient) from supersaturated solutions is critical. The objective of this work was to elucidate the influence of pressure and temperature on the rate of gas evolution from a supersaturated model oil (Exxsol D-110) and three crude oils (crude A, crude B, and crude C) of varying viscosities. The initial pressure was varied up to 10.45 MPa, keeping the temperature constant at 298.15 K. The increase in the initial saturation pressure showed that the volumetric mass transfer coefficient (gas evolution) of Exxsol D-110 and crude B (having the same viscosity) exhibited different trends. In contrast, crude A and crude C with different viscosities exhibited similar volumetric mass transfer coefficients. The effect of temperature was determined by varying the liquid temperature from 288.15 to 348.15 K at a constant initial saturation pressure of 3.45 MPa. The volumetric mass transfer coefficient increased with an increase in temperature. At similar viscosities, crude oils exhibited different volumetric mass transfer coefficients. On the basis of our experimental data, it was observed that the viscosity of the oils was not the only factor that affected gas evolution. For all cases considered in this work, the time required to evolve 50% of the gas was higher than the time estimated by the API 12J guidelines.



In this study, we investigated the stability of asphaltene adsorption structures at the oil–water interface, focusing on the role of heteroatoms, by molecular dynamics simulations. We employed an oil (1:1 mixture of heptane and toluene, by volume)–water system and used 13 types of asphaltene molecules. Two sets of asphaltene models with the alkyl side chain at different locations were considered. For each set, six models were employed, which have essentially the same structures but with different heteroatoms (such as nitrogen, oxygen, and sulfur) on the aromatic ring (i.e., heteroaromatic ring). Besides 12 models, an additional asphaltene molecule with a carboxyl group at the end of the alkyl side chain was included. We evaluated the asphaltene adsorption Gibbs free energy at the oil–water interface using potential of mean force calculations. It is found that the basic pyridine-type nitrogen-containing asphaltene presents the highest adsorption Gibbs free energy among six asphaltene molecules for both sets. The heteroatom of the asphaltene molecule forms a hydrogen bond with the water molecules so that it can stabilize asphaltene adsorption at the oil–water interface. The strength of the hydrogen bond depends on the negative charge of the heteroatom, with the basic pyridine-type nitrogen being the highest, and the highest adsorption Gibbs free energy. Furthermore, it is found that the acidic pyrrole-type nitrogen-containing asphaltene has the most significant weak hydrogen bonding between the heteroaromatic ring and water molecules due to the charge of the carbon atom in that ring being higher than others. The thiophene-type sulfur-containing asphaltene has the most significant van der Waals interaction; the adsorption Gibbs free energy shows a significant value for both sets. The carboxyl asphaltene molecule has the highest affinity to the oil–water interface among 13 models because it has two heteroatoms. The detailed understanding of the asphaltene adsorption behavior presented in this study would be useful to solve the stability issue of oil–water emulsions in crude oil production.

Moore, E.R., Davie-Martin, C.L., Giovannoni, S.J., Halsey, K.H., 2020. Pelagibacter metabolism of diatom-derived volatile organic compounds imposes an energetic tax on photosynthetic carbon fixation. Environmental Microbiology 22, 1720-1733.

https://doi.org/10.1111/1462-2920.14861

Volatile organic compounds (VOCs) produced by phytoplankton are molecules with high vapor pressures that can diffuse across cell membranes into the environment, where they become public goods. VOCs likely comprise a significant component of the marine dissolved organic carbon (DOC) pool utilized by microorganisms, but they are often overlooked as growth substrates because their diffusivity imposes analytical challenges. The roles of VOCs in the growth of the photoautotrophic diatom Thalassiosira pseudonana and heterotrophic bacterium Pelagibacter sp. HTCC1062 (SAR11) were examined using co cultures and proton transfer reaction time of flight mass spectrometry. ‐ ‐ ‐ ‐VOCs at 82 m /z values were produced in the cultures, and the concentrations of 9 of these m /z values changed in co culture relative to the diatom monoculture. Several of the ‐ m /z values were putatively identified, and their metabolism by HTCC1062 was confirmed by measuring ATP production. Diatom carbon fixation rates in co culture with HTCC1062 were 20.3% higher than the ‐diatom monoculture. Removal of VOCs from the T. pseudonana monoculture using a hydrocarbon trap caused a similar increase in carbon fixation (18.1%). These results show that a wide range of

VOCs are cycled in the environment, and the flux of VOCs from phytoplankton to bacterioplankton imposes a large and unexpected tax on phytoplankton photosynthesis.

Morana, M., Bouillon, S., Nolla-Ardèvol, V., Roland, F.A.E., Okello, W., Descy, J.-P., Nankabirwa, A., Nabafu, E., Springael, D., Borges, A.V., 2020. Methane paradox in tropical lakes? Sedimentary fluxes rather than water column production in oxic waters sustain methanotrophy and emissions to the atmosphere. Biogeosciences Discussions 2020, 1-20.


Despite growing evidence that methane (CH4) formation could also occur in well-oxygenated surface freshwaters, its significance at the ecosystem scale is uncertain. Empirical models based on data gathered at high latitude predict that the contribution of oxic CH4 increases with lake size and should represent the majority of CH4 emissions in large lakes. However, such predictive models could not directly apply to tropical lakes which differ from their temperate counterparts in some fundamental characteristics, such as year-round elevated water temperature. We conducted stable isotope tracer experiments which revealed that oxic CH4 production is closely related to phytoplankton metabolism, and is a common feature in five contrasting African lakes. Nevertheless, methanotrophic activity in surface waters and CH4 emissions to the atmosphere were predominantly fuelled by CH4 generated in sediments and physically transported to the surface. Indeed, measured CH4 bubble dissolution flux and diffusive benthic CH4 flux were several orders of magnitude higher than CH4 production in surface waters. Microbial CH4 consumption dramatically decreased with increasing sunlight intensity, suggesting that the freshwater CH4 paradox might be also partly explained by photo-inhibition of CH4 oxidizers in the illuminated zone. Sunlight appeared as an overlooked but important factor determining the CH4 dynamics in surface waters, directly affecting its production by photoautotrophs and consumption by methanotrophs.

Morishita, R., Matsuyama, R., Ishiwata, T., Tsuchiya, Y., Giang, P.T., Takahashi, S., 2020. Oil and water interactions during low-salinity enhanced oil recovery in water-wet porous media. Energy & Fuels 34, 5258-5266.


The role of emulsions should be an important factor in additional oil recovery during low-salinity water flooding (LSWF); however, it has been rarely discussed in previous studies. In this study, the contributing behavior of the oil/water interaction to the oil recovery process was investigated through core- and microscale experiments involving high-polar-component oil. Two tertiary coreflood experiments with high- and low-salinity water were conducted using cores from the same reservoir formation, where the behavior of oil recovery and that of differential pressure differed significantly. The results of core and water analyses indicate that the emulsions predominantly caused this difference. Thus, microfluidic experiments were conducted to visualize the emulsion-based oil recovery mechanisms; two phenomena of emulsions contributed to oil recovery: pore blockage and microwater dispersion. In addition, we studied the stability of emulsions in terms of the surface electric charge through the use of ζ potential measurements; emulsions were more stable in the lower salinity and higher pH conditions. These experimental results demonstrate that emulsions are important during LSWF for additional oil recovery in water-wet porous media.

Morota, T., Sugita, S., Cho, Y., Kanamaru, M., Tatsumi, E., Sakatani, N., Honda, R., Hirata, N., Kikuchi, H., Yamada, M., Yokota, Y., Kameda, S., Matsuoka, M., Sawada, H., Honda, C., Kouyama, T., Ogawa, K., Suzuki, H., Yoshioka, K., Hayakawa, M., Hirata, N., Hirabayashi, M., Miyamoto, H., Michikami, T., Hiroi, T., Hemmi, R., Barnouin, O.S., Ernst, C.M., Kitazato, K., Nakamura, T., Riu, L., Senshu, H., Kobayashi, H., Sasaki, S., Komatsu, G., Tanabe, N., Fujii, Y., Irie, T., Suemitsu, M., Takaki, N., Sugimoto, C., Yumoto, K., Ishida, M., Kato, H., Moroi, K., Domingue, D., Michel, P., Pilorget, C., Iwata, T., Abe, M., Ohtake, M., Nakauchi, Y., Tsumura, K., Yabuta, H., Ishihara, Y., Noguchi, R., Matsumoto, K., Miura, A., Namiki, N., Tachibana, S., Arakawa, M., Ikeda, H., Wada, K., Mizuno, T., Hirose, C., Hosoda, S., Mori, O., Shimada, T., Soldini, S., Tsukizaki, R., Yano, H., Ozaki, M., Takeuchi, H., Yamamoto, Y., Okada, T., Shimaki, Y., Shirai, K., Iijima, Y., Noda, H., Kikuchi, S., Yamaguchi, T., Ogawa, N., Ono, G., Mimasu, Y., Yoshikawa, K., Takahashi, T., Takei, Y., Fujii, A., Nakazawa, S., Terui, F., Tanaka, S., Yoshikawa, M., Saiki, T., Watanabe, S., Tsuda, Y., 2020. Sample collection from asteroid (162173) Ryugu by Hayabusa2: Implications for surface evolution. Science 368, 654-659.


Abstract: The near-Earth asteroid (162173) Ryugu is thought to be a primitive carbonaceous object that contains hydrated minerals and organic molecules. We report sample collection from Ryugu’s surface by the Hayabusa2 spacecraft on 21 February 2019. Touchdown images and global observations of surface colors are used to investigate the stratigraphy of the surface around the sample location and across Ryugu. Latitudinal color variations suggest the reddening of exposed surface material by solar heating and/or space weathering. Immediately after touchdown, Hayabusa2’s thrusters disturbed dark, fine grains that originate from the redder materials. The stratigraphic relationship between identified craters and the redder material indicates that surface reddening occurred over a short period of time. We suggest that Ryugu previously experienced an orbital excursion near the Sun.

Editor's Summary: Collecting a sample of asteroid Ryugu. The Hayabusa2 spacecraft recently traveled to the nearby carbonaceous asteroid Ryugu to collect samples and return them to Earth for laboratory analysis. Morota et al. describe Hayabusa2's first sample collection, taken during a brief touchdown on Ryugu's surface. Close-up images and video taken during the sampling process allowed the authors to investigate the surface colors and morphology on a small scale. Relating these to the surface craters and stratigraphy constrains the evolution of Ryugu. The authors conclude that the asteroid experienced a prior period of strong solar heating caused by changes in its orbit. The sample is expected to arrive on Earth in December 2020.

Motamedi, S., Orcutt, B.N., Früh-Green, G.L., Twing, K.I., Pendleton, H.L., Brazelton, W.J., 2020. Microbial residents of the Atlantis Massif’s shallow serpentinite subsurface. Applied and Environmental Microbiology 86, e00356-20.


Abstract: The Atlantis Massif rises 4,000 m above the seafloor near the Mid-Atlantic Ridge and consists of rocks uplifted from Earth’s lower crust and upper mantle. Exposure of the mantle rocks to seawater leads to their alteration into serpentinites. These aqueous geochemical reactions, collectively known as the process of serpentinization, are exothermic and are associated with the release of hydrogen gas (H2), methane (CH4), and small organic molecules. The biological consequences of this flux of energy and organic compounds from the Atlantis Massif were explored

by International Ocean Discovery Program (IODP) Expedition 357, which used seabed drills to collect continuous sequences of shallow (<16 m below seafloor) marine serpentinites and mafic assemblages. Here, we report the census of microbial diversity in samples of the drill cores, as measured by environmental 16S rRNA gene amplicon sequencing. The problem of contamination of subsurface samples was a primary concern during all stages of this project, starting from the initial study design, continuing to the collection of samples from the seafloor, handling the samples shipboard and in the lab, preparing the samples for DNA extraction, and analyzing the DNA sequence data. To distinguish endemic microbial taxa of serpentinite subsurface rocks from seawater residents and other potential contaminants, the distributions of individual 16S rRNA gene sequences among all samples were evaluated, taking into consideration both presence/absence and relative abundances. Our results highlight a few candidate residents of the shallow serpentinite subsurface, including uncultured representatives of the Thermoplasmata, Acidobacteria, Acidimicrobia, and Chloroflexi.

Importance: The International Ocean Discovery Program Expedition 357—“Serpentinization and Life”—utilized seabed drills to collect rocks from the oceanic crust. The recovered rock cores represent the shallow serpentinite subsurface of the Atlantis Massif, where reactions between uplifted mantle rocks and water, collectively known as serpentinization, produce environmental conditions that can stimulate biological activity and are thought to be analogous to environments that were prevalent on the early Earth and perhaps other planets. The methodology and results of this project have implications for life detection experiments, including sample return missions, and provide a window into the diversity of microbial communities inhabiting subseafloor serpentinites.

Mousavi, S.M.R., Jafari, S., Schaffie, M., Norouzi-Apourvari, S., 2020. Experimental study and modeling permeability damage in porous media due to asphaltene deposition. Journal of Petroleum Science and Engineering 193, 107396.


Asphaltene deposition in porous media has a destructive effect on well productivity during primary and secondary oil recovery. Previous research studies have presented models for permeability reduction due to particle deposition in porous media. In this study, a semi-experimental model was modified and a new model was introduced to predict permeability changes due to asphaltene retention in early times of precipitation. The modified model unlike common models considers the size of asphaltene particles, porous media grain size, fluid flow properties and precipitation in pore throat. A set of experiments are done to obtain the parameters needed for modeling and check the validity of model. Crude oil is used as fluid sample and a sand pack filled with glass beads is used as an artificial porous media in flood tests. To identify the size of asphaltene particles, microscopic technique is used. The results of experiments are used to investigate asphaltene deposition in porous media and evaluate model prediction. A new procedure based on the modified model is applied to obtain model parameters and simplify the calculations. The new model can eliminate the deficiencies in previous models for prediction of asphaltene deposition in early stages of particle retention. The model also is validated by experimental results that were reported in the literature before. The results show rational accommodation with experimental data.

Muhammad, M.H., Idris, A.L., Fan, X., Guo, Y., Yu, Y., Jin, X., Qiu, J., Guan, X., Huang, T., 2020. Beyond risk: Bacterial biofilms and their regulating approaches. Frontiers in Microbiology 11, 928. doi: 10.3389/fmicb.2020.00928.


Bacterial biofilms are complex surface attached communities of bacteria held together by self-produced polymer matrixs mainly composed of polysaccharides, secreted proteins, and extracellular DNAs. Bacterial biofilm formation is a complex process and can be described in five main phases: (i) reversible attachment phase, where bacteria non-specifically attach to surfaces; (ii) irreversible attachment phase, which involves interaction between bacterial cells and a surface using bacterial adhesins such as fimbriae and lipopolysaccharide (LPS); (iii) production of extracellular polymeric substances (EPS) by the resident bacterial cells; (iv) biofilm maturation phase, in which bacterial cells synthesize and release signaling molecules to sense the presence of each other, conducing to the formation of microcolony and maturation of biofilms; and (v) dispersal/detachment phase, where the bacterial cells depart biofilms and comeback to independent planktonic lifestyle. Biofilm formation is detrimental in healthcare, drinking water distribution systems, food, and marine industries, etc. As a result, current studies have been focused toward control and prevention of biofilms. In an effort to get rid of harmful biofilms, various techniques and approaches have been employed that interfere with bacterial attachment, bacterial communication systems (quorum sensing, QS), and biofilm matrixs. Biofilms, however, also offer beneficial roles in a variety of fields including applications in plant protection, bioremediation, wastewater treatment, and corrosion inhibition amongst others. Development of beneficial biofilms can be promoted through manipulation of adhesion surfaces, QS and environmental conditions. This review describes the events involved in bacterial biofilm formation, lists the negative and positive aspects associated with bacterial biofilms, elaborates the main strategies currently used to regulate establishment of harmful bacterial biofilms as well as certain strategies employed to encourage formation of beneficial bacterial biofilms, and highlights the future perspectives of bacterial biofilms.



In February 2019, at the CSIRO In-Situ Laboratory CCS project, a test was conducted where 38 t of gaseous CO2 were injected over 5 days into a fault zone at a depth of approximately 340 m. As a release test, this project enabled the testing and validation of surface and shallow well monitoring strategies at intermediate depths (i.e. depths much deeper than previous release projects and shallower than reservoirs used for CO2 storage). One of the aims of this project is to understand how CO2 would behave at intermediate depths if it did migrate from deeper depths (i.e. from a storage reservoir); the CO2 was not intended to migrate to the shallow subsurface or to surface/atmosphere. To verify that the injected CO2 remained in the subsurface, and to comply with environmental performance requirements on site, a comprehensive surface gas and groundwater monitoring program was conducted. The monitoring strategy was designed such that any leakage(s) to the surface of injected CO2 would be detected, mapped and, ultimately, quantified. The surface air monitoring program was comprised of three different but complementary approaches allowing data

to be efficiently collected over different spatial and temporal scales. These approaches included continuous soil-gas chamber measurements at fixed locations, periodic soil-gas chamber measurements on gridded locations and near-surface atmospheric measurements on a mobile platform. The surface air monitoring approaches gave self-consistent results and reduced the risk of “false negative” test results. The only anomalous CO2 detected at the surface flowed from the observation well and could be directly attributed to a breach in the well casing at the injection depth providing a conduit for CO2/water to rise to the surface. Groundwater monitoring program revealed no impact on the groundwater resources attributable to the carbon injection project. Based on this work, we demonstrate that this multi-pronged monitoring strategy can be utilized to minimize the overall resources devoted to monitoring by increasing the number of monitoring approaches and diminishing the resources devoted to each technique. By maximizing the effectiveness of each element of the monitoring program, a cost-efficient and robust monitoring strategy capable of early leak detection and attribution of any leaking CO2 can be achieved.

Naafs, B.D.A., Voelker, A.H.L., Karas, C., Andersen, N., Sierro, F.J., 2020. Repeated near-collapse of the Pliocene sea surface temperature gradient in the North Atlantic. Paleoceanography and Paleoclimatology 35, e2020PA003905.

https://doi.org/10.1029/2020PA003905

Sea surface temperature (SST) is used to infer past changes in the state of the climate system. Here we use a combination of newly generated and published organic paleothermometer records, together with novel high resolution benthic foraminiferal δ‐ 18O stratigraphy, from four sites in the midlatitude North Atlantic (41–58°N) to reconstruct the long term evolution of the latitudinal SST ‐gradient during the Pliocene and early Pleistocene (4.0 to 2.4 Myr), the last time atmospheric CO2 reached concentrations above 400 ppmv. We demonstrate that the latitudinal SST gradient in the North Atlantic nearly collapsed twice during this period. We conclude that the latitudinal SST gradient in the midlatitude North Atlantic has two end members: a maximum as existing at present ‐and a minimum that existed during certain periods of the (late) Pliocene. Our results suggest that the 400 ppmv Pliocene world was more dynamic than currently thought.‐

Nagashima, H.D., Miyagi, T., Yasuda, K., Ohmura, R., 2020. Clathrate hydrates at temperatures below the freezing point of water: A review. Fluid Phase Equilibria 517, 112610.


This paper provides the review focusing on the clathrate hydrates at the temperatures below the freezing point of water. The three main topics of the review are the chemical thermodynamics, naturally-occurring hydrates and novel industrial applications utilizing hydrates. Fundamental phase equilibria in the hydrate forming systems at the temperatures below the freezing point of water are first reviewed. The effects of water-soluble compound on the hydrate phase equilibria are extensively discussed based on the experimental data reported in the literature and the newly obtained experimental data on the solid ice + sodium chloride aqueous solution + carbon dioxide hydrate + carbon dioxide gas four-phase equilibria that were measured in the present study. Natural occurrence of hydrates is discussed by comparing the thermodynamic conditions in the planets and satellites with the relevant hydrate phase equilibrium data. The naturally-occurring hydrates would exist in the following planets and satellites; Mars and Titan. The storage of natural gas in the form of

the hydrate has been well investigated in the past two decades. CO2 hydrate can be used as the fire-fighting agent and the solid carbonated foods. The refrigeration and engine utilizing hydrates as the working media may be the challenging technologies having the prospects in terms of the efficiency, environment friendliness and the safety.

Naimark, E.B., Boeva, N.M., 2020. The role of iron in the formation of fossils of soft-bodied organisms: Results of long-term experiments. Doklady Earth Sciences 490, 72-75.

https://doi.org/10.1134/S1028334X20020105

For the first time, a series of long-term taphonomic experiments (1–5 years) has shown iron deposition during the formation of fossils of soft-bodied animals. Based on the set of measurements, it is concluded that the deposition of iron is not a factor of preservation of soft-bodied animal remains, and pyritization itself is a consequence of chemical processes in iron-containing sediments. These reactions are triggered by the decomposition of organic matter and are accompanied by the destruction of minerals and saturation of the liquid medium with dissolved iron. The nonexclusive, common nature of these reactions in the sediments explains the cosmopolitan distribution of pyritized fossils of soft-bodied organisms. Such an explanation is an alternative to the prevailing opinion on pyritization: iron serves as the main preservation agent and pyritization takes place with the participation of sulfate reducers accelerating the deposition of iron on the organic matrix.

Nakakuni, M., Takehara, K., Swart, P.K., Yamamoto, S., 2020. The contribution of prokaryotes and terrestrial plants to Maldives inter-atoll sapropels: Evidence from organic biomarkers. Organic Geochemistry 145, 104039.


The composition of organic matter in early Miocene sediment cores obtained from International Ocean Discovery Program Expedition 359 (IODP Exp. 359) was analysed using tetramethylammonium hydroxide (TMAH) thermochemolysis, a method used to determine concentrations of lignin phenols, fatty acids, sterols and hopanoids. These early Miocene sediment cores contain thick sequences (∼100 m) of interbedded light (organic-poor) and dark (organic-rich) sedimentary layers. A total of 49 samples from cores between 704.4 mbsf to 803.95 mbsf (∼20–23 Ma) at Site U1466 (518 m water depth) was selected with particular emphasis placed on the dark layers, although the light layers were also sampled. While organic compounds were below detection limits in the lighter (white) coloured sedimentary layers, the dark layers, with concentrations of organic carbon up to 20%, contained varying concentrations of all analysed compounds. Although sterols were present, hopanoids were more abundant in the dark layers. The contribution of prokaryotic organisms, estimated from the ratio ([hopanols and hopanoic acids]/[sterols + hopanols and hopanoic acids]), indicates that it was prokaryotic organisms rather than eukaryotic organisms that contributed the majority (∼90%) of the organic matter in the dark layers. In conjunction with this record, more negative δ15N values in the darker layers suggest that the prokaryotic organisms were nitrogen-fixing microorganisms (presumably cyanobacteria). The long-to-short fatty acid ratios, together with sterol distributions and the concentration of lignin phenols, suggest the input of terrestrial plant material occurred during a high total organic carbon (TOC) interval (∼770–810 mbsf), which coincides with more negative carbon isotope ratios. Additionally, the long-to-short

fatty acid ratio in this interval was significantly higher in the dark layers than the light layers, suggesting that terrestrial environments suitable for vegetation growth expanded during the interval represented by the dark layers. Furthermore, the ratio of cinnamyl lignin phenols to vanillyl lignin phenols (C/V) is relatively high during these intervals. From these biomarker tracers, we speculate that the terrestrial vegetation was dominated by herbaceous plants adapted to frequent sea-level changes.

Nakano, H., Hirakawa, N., Matsubara, Y., Yamashita, S., Okuchi, T., Asahina, K., Tanaka, R., Suzuki, N., Naraoka, H., Takano, Y., Tachibana, S., Hama, T., Oba, Y., Kimura, Y., Watanabe, N., Kouchi, A., 2020. Precometary organic matter: A hidden reservoir of water inside the snow line. Scientific Reports 10, 7755.

https://doi.org/10.1038/s41598-020-64815-6

The origin and evolution of solar system bodies, including water on the Earth, have been discussed based on the assumption that the relevant ingredients were simply silicates and ices. However, large amounts of organic matter have been found in cometary and interplanetary dust, which are recognized as remnants of interstellar/precometary grains. Precometary organic matter may therefore be a potential source of water; however, to date, there have been no experimental investigations into this possibility. Here, we experimentally demonstrate that abundant water and oil are formed via the heating of a precometary-organic-matter analog under conditions appropriate for the parent bodies of meteorites inside the snow line. This implies that H2O ice is not required as the sole source of water on planetary bodies inside the snow line. Further, we can explain the change in the oxidation state of the Earth from an initially reduced state to a final oxidized state. Our study also suggests that petroleum was present in the asteroids and is present in icy satellites and dwarf planets.

Nakano, Y., Imasaka, T., Imasaka, T., 2020. Generation of a nearly monocycle optical pulse in the near-infrared region and its use as an ionization source in mass spectrometry. Analytical Chemistry 92, 7130-7138.


We report on the generation of an octave-spanning (600–1400 nm) nearly monocycle (1.1 cycle) ultrashort optical pulse (3.2 fs) in the near-infrared region by the Fourier synthesis of two pulses at 800 and 1200 nm, both of which were spectrally broadened by self-phase modulation and were compressed by chirp mirrors. The 3.2 fs pulse was converted into the ultraviolet by third harmonic generation, the pulse width being evaluated to 1.9 fs. The near-infrared pulse (3.2 fs) was employed as an ionization source in mass spectrometry, and the signal intensity was significantly increased for pentachlorobenzene, an environmental pollutant listed in the Stockholm Convention. The present data and the spectral properties obtained by quantum chemical calculations suggest that the method offers a potential advantage for the detection of Novichok, a chemical warfare agent that is thought to have been used in a terrorist attack.

Nascimento, M.K.S., Loureiro, S., Souza, M.R.d.R., Alexandre, M.d.R., Nilin, J., 2020. Toxicity of a mixture of monoaromatic hydrocarbons (BTX) to a tropical marine microcrustacean. Marine Pollution Bulletin 156, 111272.


This study evaluated the toxicity of benzene, toluene, and xylenes (BTX), isolated and in binary mixtures to Mysidopsis juniae. The organisms were exposed to BTX, and combined effect patterns were predicted by applying the theoretical models of Concentration Addition and Independent Action. According to the LC50 of the isolated compounds, xylene (16.1 ± 2.4 mg L−1) was considered the most toxic, followed by toluene (38.0 ± 5.3 mg L−1) and, lastly, benzene (78.0 ± 2.9 mg L−1). The binary combinations showed deviations from additivity, with exposure to the xylene–benzene mixture presenting as antagonistic, while the xylene–toluene and toluene–benzene mixtures were better explained by a dose ratio deviation, with toluene being responsible for the antagonistic pattern. This study provides new insights into toxicity prediction of a BTX mixture, which adds value to the risk assessment procedure over evaluation of chemical hazards on a case-by-case basis.

Nasdala, L., Schmidt, C., 2020. Applications of Raman spectroscopy in mineralogy and geochemistry. Elements 16, 99-104.


The application of Raman spectroscopy for the identification and characterization of minerals and related materials has increased appreciably during recent years. Raman spectroscopy has proven to be a most valuable and versatile analytical tool. Successful applications cover virtually all the mineralogical sub-disciplines, and have become more numerous in geochemistry. We present a general summary of present applications, illustrated by selected examples. In addition, we briefly point out several aspects of spectral acquisition, data reduction, and interpretation of Raman results that are important for the application of Raman spectroscopy as a reliable analytical tool.



A plume of vaporized sediments and basement rocks was ejected to the top of atmosphere when a 10–15 km asteroid impacted on Yucatan in the Southern Gulf of Mexico about 66 million years ago. The Chicxulub impact-vapor plume emitted a flash of light that had clues on the chemistry and degree of vaporization of the target surface material. Here we simulate the asteroid impact by vaporizing marine carbonate sediments cored in the Yaxcopoil-1 borehole in the Chicxulub crater using an intense infrared laser pulse. We investigate two sedimentary layers that represent the most dominant mineral phases of the target sequence: carbonates and sulfates. Their main constituents are 86% calcite and 74% anhydrite, respectively. The laser-induced vapor plumes were produced from each layer in a background simulated late Cretaceus atmosphere (0.16% CO2, 30% O2, and 69.84% N2). Time-resolved spectroscopic analyses from the laser-induced plumes were carried out using experimental and synthetic spectra. The vapor plumes had similar temperatures (≥7800 K) at 1 μs and their spectra showed similar emissions. The spectra contained the following lines in nm: Ca+

(mostly at 393.4 and 396.9 with less prominence at 370.6 and 373.7), Ca (422.7, 430.3, 443.6, 445.5, 527.0, 560.3, 616.4, and 657.3), N (746.8 and 821.6), O (777.7), and C (794.5). Molecular bands were not conspicuous which indicated complete vaporization of the target material by the laser pulse. The contribution of the granitic basement was examined using synthetic spectra. The expected emissions according to their intensities are: Na (589.6), Ca+ (393.4), Al (396.2, 309.3), Ca+ (396.9), Ca (422.7), Na (819.5) and K (766.5, 769.9). The results suggest that the emission corresponded to Ca+ and Ca originated mostly from the volatilization of the marine sediments, and Na, Al, and K from the basement rocks. The physico-chemical evolution of the Chicxulub impact-vapor plume could be deduced by deciphering the temperature and electron density from the emission lines of Ca and Ca+. These physical parameters can be used in gas dynamic models to predict the fluxes and nature of gases, vapors and mineral phases that were introduced into the atmosphere and better assess their impact to the environment and the biosphere.

Nazarova, V.M., Gatovsky, Y.A., 2020. “Conodont pearls” from the Devonian deposits of European Russia. Moscow University Geology Bulletin 75, 31-39.

https://doi.org/10.3103/S014587522001010X

The study history and hypotheses of origin of unique phosphate microfossils, that is, “conodont pearls,” are considered in the present paper. The material comes from the Middle and Upper Devonian deposits of the European Russia. The analysis of the chemical composition of these unique objects has shown their great similarity with other phosphate microfossils that belong to conodonts and types of fish that inhabit the same paleobasins. Based on their morphological features and chemical composition one can suggest that “conodont pearls” are the otoliths of conodonts

Ndiripo, A., Albrecht, A., Pasch, H., 2020. Advanced liquid chromatography of polyolefins using simultaneous solvent and temperature gradients. Analytical Chemistry 92, 7325-7333.


Olefin copolymers are complex polymer materials that exhibit multiple distributions in molecular properties such as molar mass, chemical composition, and branching. To address the multivariate molecular compositions, chromatographic protocols have been developed that synergistically combine solvent and temperature gradients. As representative examples, blends of olefin copolymers have been fractionated on porous graphitic carbon stationary phases. This is the first study that makes complementary use of solvent and temperature gradient interaction chromatography (SGIC and TGIC, respectively) to capitalize on the advantages of both techniques. In a first experimental setup, solvent and temperature gradients were used simultaneously and complex blends of low molar mass polyethylene and ethylene-co-1-octene copolymers were separated with high efficiency. The separation of oligomers was observed to be significantly better in SGIC as compared to TGIC, while comonomer blends could be separated in either TGIC or SGIC mode. In another innovation, a two-column setup was employed where the columns were placed in different temperature zones. It was demonstrated that the separation of both low and high comonomer content blends was improved significantly when the temperatures of the two zones were manipulated reasonably.

Nemirovskaya, I.A., Kochenkova, A.I., Khramtsova, A.V., 2020. Hydrocarbons at the geochemical barrier the northern Dvina–the White Sea. Water Resources 47, 438-447.

https://doi.org/10.1134/S0097807820030148

Aliphatic and polycyclic aromatic hydrocarbons have been studied in suspended matter and bottom sediments at the geochemical barrier the Northern Dvina–Dvina Bay during spring flood and low-water season. The increase in the concentrations during spring flood (for aliphatic hydrocarbons, on the average, 154 µg/L) compared with those during low-water season (on the average, 52 µg/L) has been shown to be short-time. The losses of hydrocarbons at this geochemical barrier are governed by variations of water salinity, river flow, and lunar phases and can reach 96% (August 2017). The composition of alkanes and polycyclic aromatic hydrocarbons in river water mostly showed the predominance of petroleum components. In the course of sedimentation and as salinity increases, petroleum hydrocarbons decompose, making their effect beyond the gravitational part of the marginal filter of the Northern Dvina minor. The effect of redox processes in the sediment stratum on hydrocarbon distributions is stronger than that on Corg.

Neubeck, A., Freund, F., 2020. Sulfur chemistry may have paved the way for evolution of antioxidants. Astrobiology 20, 670-675.

https://doi.org/10.1089/ast.2019.2156

The first organisms on the young Earth, just 1–1.5 billion years old, were likely chemolithoautotrophic anaerobes, thriving in an anoxic world rich in water, CO2, and N2. It is generally assumed that, until the accumulation of O2 in the atmosphere, life was exempted from the oxidative stress that reactive oxygen species (ROS) impose on hydrocarbon-based life. Therefore, it is perplexing to note that life on the early Earth already carried antioxidants such as superoxide dismutase enzymes, catalase, and peroxiredoxins, the function of which is to counteract all forms of ROS, including H2O2. Phylogenetic investigations suggest that the presence of these enzymes in the last universal common ancestor, far predating the great oxygenation event (GOE) sometime between 2.3 and 2.7 billion years ago, is thought to be due to the appearance of oxygen-producing microorganisms and the subsequent need to respond to the appearance of ROS. Since the metabolic enzymes that counteract ROS have been found in all domains of life, they are considered of primitive origin. Two questions arise: (1) Could there be a nonbiological source of ROS that predates the oxygenic microbial activity? (2) Could sulfur, the homologue of oxygen, have played that role? Reactive sulfur species (RSS) may have triggered the evolution of antioxidants such that the ROS antioxidants started out as “antisulfur” enzymes developed to cope with, and take advantage of, various forms of RSS that were abundantly present on the early Earth.



In the southeastern Sichuan Basin, the Wufeng–Longmaxi Formations are major strata used for shale gas exploration and development. Although the Fuling shale gas field—the largest Lower

Paleozoic shale gas field in the world—has already been developed, shale gas wells in other parts of this area apart from the Jiaoshiba anticline vary greatly in production capacity. Microstructures and inclusion homogenization temperatures were analyzed for venous fluid inclusions in samples taken from the main shale gas wells in the Wufeng–Longmaxi Formations and were combined with simulated burial–thermal histories, hydrocarbon generation and expulsion histories, and fracture formation–closure times and stages to determine how fracture and fluid activities influenced shale gas preservation/destruction conditions. Veins were composed of quartz, calcite, and quartz–calcite and contained gas–liquid two-phase brine and high-density methane inclusions. Combined with simulated burial–thermal histories, the results showed that fracture-fluid activity time could be inferred from inclusion homogenization temperatures and was consistent with gas content and output of shale gas wells. The deeper and earlier the vein formation, the more favorable the preservation conditions of the shale gas reservoir. Furthermore, the more the fracture formation–closure stages and the lower the inclusion homogenization temperature, the more severe damage to the shale gas reservoir has happened. Clearly, in areas from Jiaoshiba to Pingqiao, Nanchuan, and Dingshan in the southwest, increasing the number of paleo-fluid activity and vein formation stages, as well as later paleo-fluid activity time, worsened shale gas preservation conditions. The results can act as a reference for studying fracture-fluid activity, enrichment, and preservation of shale gas in the southeastern Sichuan Basin and other parts of the world.

Ning, C., Ma, Z., Jiang, Z., Su, S., Li, T., Zheng, L., Wang, G., Li, F., 2020. Effect of shale reservoir characteristics on shale oil movability in the Lower Third Member of the Shahejie Formation, Zhanhua sag. Acta Geologica Sinica - English Edition 94, 352-363.

https://doi.org/10.1111/1755-6724.14284

To reveal the effect of shale reservoir characteristics on the movability of shale oil and its action mechanism in the lower third member of the Shahejie Formation (Es3

l), samples with different features were selected and analyzed using N2 adsorption, high pressure mercury injection capillary ‐pressure (MICP), nuclear magnetic resonance (NMR), high speed centrifugation, and displacement ‐image techniques. The results show that shale pore structure characteristics control shale oil movability directly. Movable oil saturation has a positive relationship with pore volume for radius > 2 μm, as larger pores often have higher movable oil saturation, indicating that movable oil is present in relatively larger pores. The main reasons for this are as follows. The relatively smaller pores often have oil wetting properties because of organic matter, which has an unfavorable effect on the flow ‐of oil, while the relatively larger pores are often wetted by water, which is helpful to shale oil movability. The rich surface provided by the relatively smaller pores is beneficial to the adsorption of immovable oil. Meanwhile, the relatively larger pores create significant pore volume for movable oil. Moreover, the larger pores often have good pore connectivity. Pores and fractures are interconnected to form a complex fracture network, which provides a good permeability channel for shale oil flow. The smaller pores are mostly distributed separately; thus, they are not conducive to the flow of shale oil. The mineral composition and fabric macroscopically affect the movability of shale oil. Calcite plays an active role in shale oil movability by increasing the brittleness of shale and is more likely to form micro cracks under the same stress background. Clay does not utilize shale oil ‐flow because of its large specific surface area and its block effect. The bedding structure increases the large scale storage space and improves the connectivity of pores at different scales, which is ‐conducive to the movability of shale oil.

Nisenbaum, M., Corti-Monzón, G., Villegas-Plazas, M., Junca, H., Mangani, A., Patat, M.L., González, J.F., Murialdo, S.E., 2020. Enrichment and key features of a robust and consistent indigenous marine-cognate microbial consortium growing on oily bilge wastewaters. Biodegradation 31, 91-108.

https://doi.org/10.1007/s10532-020-09896-w

Oily bilge wastewater (OBW) is a hazardous hydrocarbon-waste generated by ships worldwide. In this research, we enriched, characterized and study the hydrocarbon biodegradation potential of a microbial consortium from the bilges of maritime ships. The consortium cZ presented a biodegradation efficiency of 66.65% for total petroleum hydrocarbons, 72.33% for aromatics and 97.76% removal of n-alkanes. This consortium showed the ability to grow in OBWs of diverse origin and concentration. A 67-fold increase in biomass was achieved using a Sequential Batch Reactor with OBW as the only carbon and energy source. The bacterial community composition of the enriched OBW bacterial consortium at the final stable stage was characterized by 16S amplicon Illumina sequencing showing that 25 out of 915 of the emerged predominant bacterial types detected summed up for 84% of total composition. Out of the 140 taxa detected, 13 alone accumulated 94.9% of the reads and were classified as Marinobacter, Alcanivorax, Parvibaculum, Flavobacteriaceae, Gammaproteobacteria PYR10d3, Novispirillum and Xanthomonadaceae among the most predominant, followed by Thalassospira, Shewanella, Rhodospirillaceae, Gammaprotobacteria, Rhodobacteriaceae and Achromobacter. The microbial community from OBW bioreactor enrichments is intrinsically diverse with clear selection of predominant types and remarkably exhibiting consistent and efficient biodegradation achieved without any nutrient or surfactant addition. Due to there is very little information available in the OBW biodegradation field, this work contributes to the body of knowledge surrounding the treatment improvement of this toxic waste and its potential application in wastewater management.

Nitschke, M.R., Fidalgo, C., Simões, J., Brandão, C., Alves, A., Serôdio, J., Frommlet, J.C., 2020. Symbiolite formation: a powerful in vitro model to untangle the role of bacterial communities in the photosynthesis-induced formation of microbialites. The ISME Journal 14, 1533-1546.

https://doi.org/10.1038/s41396-020-0629-z

Microbially induced calcification is an ancient, community-driven mineralisation process that produces different types of microbialites. Symbiolites are photosynthesis-induced microbialites, formed by calcifying co-cultures of dinoflagellates from the family Symbiodiniaceae and bacteria. Symbiolites encase the calcifying community as endolithic cells, pointing at an autoendolithic niche of symbiotic dinoflagellates, and provide a rare opportunity to study the role of bacteria in bacterial–algal calcification, as symbiodiniacean cultures display either distinct symbiolite-producing (SP) or non-symbiolite-producing (NP) phenotypes. Using Illumina sequencing, we found that the bacterial communities of SP and NP cultures differed significantly in the relative abundance of 23 genera, 14 families, and 2 phyla. SP cultures were rich in biofilm digesters from the phylum Planctomycetes and their predicted metagenomes were enriched in orthologs related to biofilm formation. In contrast, NP cultures were dominated by biofilm digesters from the Bacteroidetes, and were inferred as enriched in proteases and nucleases. Functional assays confirmed the potential of co-cultures and bacterial isolates to produce biofilms and point at acidic polysaccharides as key stimulators for mineral precipitation. Hence, bacteria appear to influence symbiolite formation primarily through their biofilm-producing and modifying activity and we anticipate that symbiolite

formation, as a low-complexity in vitro model, will significantly advance our understanding of photosynthesis-induced microbial calcification processes.

Niu, J., Liu, Q., Lv, J., Peng, B., 2020. Review on microbial enhanced oil recovery: Mechanisms, modeling and field trials. Journal of Petroleum Science and Engineering 192, 107350.


After conventional oil recovery operations, abundant residual oil is still trapped in pore space of complex capillary network in the reservoir. As a promising method of tertiary oil recovery, microbial enhanced oil recovery (MEOR) involves the use of indigenous or specially screened microorganisms to produce specific metabolites by injecting formation or ground fermentation to enhance crude oil recovery. This paper discussed the mechanism of mobilizing trapped crude oil by microorganisms and their metabolites in detail, including interfacial tension reduction, wettability alteration, selective plugging, and degradation. Furthermore, numerical simulation for MEOR and novel technologies, such as genetically engineered MEOR (GEMEOR) and enzyme enhanced oil recovery (EEOR) were also introduced. Finally, screening criteria of reservoirs and 19 field trials cases in 9 countries were summarised. Currently, the field application of MEOR is still restricted due to the inconsistent and unstable effects and the possible negative impact of nutrient and exogenous microbial injection. However, considering the economic feasibility and environmental benefit of MEOR, it has promising application prospects in the further development of the oil fields.



Natural product chemistry, microbiology, and food, human, and plant metabolomics represent a few sources of complex metabolomics data generated by mass spectrometry. Among the medley of software tools used to handle these data sets, no universal tool can qualitatively, quantitatively, or statistically address major biological questions or tasks. CycloBranch 2, an open and platform-free software, at least now provides the de novo generation of molecular formulas of unknown compounds in both liquid chromatography/mass spectrometry and mass spectrometry imaging datafiles. For imaging files, this database-free approach was documented in the bimodal image fusion and characterization of three small molecules, including metallophores. The fine isotope ratio data filtering step distinguished 34S/13C2 and 41K/13C2 features. The standalone software package is implemented in C++ and can be downloaded from https://ms.biomed.cas.cz/cyclobranch/ and used under GNU General Public License.

O'Neil, G.R., Tackett, L.S., Meyer, M., 2020. Petrographic evidence for Ediacaran microbial mat-targeted behaviors from the Great Basin, United States. Precambrian Research 345, 105768.


The lower Member of the Wood Canyon Formation contains a variety of simple late Precambrian–early Cambrian dwelling and grazing traces, typical of early bioturbators. The traces, dominated by Planolites and Palaeophycus, are heavily abundant throughout sections comprised of higher energy

siliciclastics. Two of which, Chicago Pass and Boundary Canyon (California, USA), also contain evidence for targeted microbial mat penetration by undermat mining organisms below and into the PC–C boundary. The co-occurence of penetrative burrows within microbial microlaminae, surficial trails, and dwelling structures is characteristic of the complex Ediacaran trace fossil, Lamonte trevallis, as described by Meyer et al., (2014) from the Dengying Formation of South China. The specimens from the Wood Canyon Formation present similar structures resulting from altering behaviors of epibenthic locomotion, undermat mining, and dwelling (Meyer et al., 2014). Principally, grain size analyses confirmed the presence of microbial mat-targeted mining, seemingly resistant to overprinting by co-occurring horizontal traces. Therefore, we have classified the traces present in the California sections as Lamonte trevallis, broadening the geographic extent of this particular mining behavior in the Precambrian and the instances of complex bioturbating behaviors preceding the Cambrian substrate revolution.

Ocubalidet, S., Carvajal-Ortiz, H., Gentzis, T., 2020. Post-well stimulation allocation of commingled production using geochemical fingerprinting techniques in unconventional reservoirs: A review of methods, and a case study of the Montney Formation, Western Canadian Sedimentary Basin. International Journal of Coal Geology 224, 103476.


The methods used in allocating commingled production in conventional reservoirs are similar to those that are effective in performing the same task on unconventional reservoirs. However, the protocols to follow can vary a great deal. The presence of distinct endmembers in the former allows the use of the method of production allocation using peak height ratios and mixing curves and using linear regression of peak heights. Due to the possible contribution from multiple intervals in the same formation or even from different formations as in the case of fracture stimulated unconventional reservoirs, the combined application of methods that compare the quantities and carbon stable isotopes of selected compounds (such as saturate and aromatic hydrocarbons) and other parameters (such as API gravity) was employed. This was done based on a series of samples presumed to represent the endmembers via their HRGC and GCMS oil fingerprint, followed by the determination of the contribution from each sample by using an algebraic solution of simultaneous linear equations. A review of the two methods is provided.

The aforementioned method for unconventional resources is demonstrated in a case study of production allocation that was performed on three produced oils sampled at different times from three separate wells, “A” “C”, and “D”, located in the Western Canadian Sedimentary Basin. A total of 25 core extract samples representing two producing zones (end members) of the Montney Formation (i.e., the Middle and the Lower Montney) from well “A” and “B” were used. Results of GC and GCMS analyses of the samples were evaluated; rigorous filters, cluster analysis (dendrograms), and Principal Component Analysis (PCA) were applied to identify any clustering or variation between the samples representing possible contributor layers and the commingled oil. Then, using proprietary software and statistical techniques, the fingerprint of selected compounds was qualitatively compared and their quantity in each of the rock extracts and the produced oils was determined in order to allocate the contribution from the two end members that each extract belongs to.

Results from the method for unconventional resources were compared to other data (such as GC trace patterns) for consistency. The case study demonstrates that a combined approach that

accounts for the entire fingerprint (i.e., GC and molecular markers (including biomarker and non-biomarker parameters)), produces the best results and minimizes uncertainty.

Omoni, V.T., Lag-Brotons, A.J., Semple, K.T., 2020. Impact of organic amendments on the development of 14C-phenanthrene catabolism in soil. International Biodeterioration & Biodegradation 151, 104991.


This study investigated the impact of spent brewery grains and spent mushroom compost on the development of phenanthrene biodegradation in soil. Two aspects were considered: (i) the influence of increasing waste-to-soil ratios (1:10, 1:5, 1:2, 1:1 & 2:1) and (ii) the impact of soil-PAH contact time (1–100 d). Biodegradation was quantified by measuring changes in the lag phase, the fastest rates and extents of mineralization of 14C-phenanthrene, as well as changes in the number of total heterotrophic and phenanthrene degrading bacteria and fungi. The amendment of smaller amounts of the wastes (1:10 & 1:5) resulted in greatest levels of biodegradation. Microbial numbers increased in all of the amended soils but phenanthrene-degrading numbers in most amended soils did not correlate with the rates and extents of 14C-phenanthrene mineralization. This investigation highlighted the value of waste organic materials as nutrient sources to stimulate microbial degradation of contaminants in soil.

Oñate-Gutiérrez, J.A., Ramírez-Pradilla, J.S., Pinzón, J.R., Combariza, M.Y., Blanco-Tirado, C., 2020. Asphaltene structure modifiers as a novel approach for viscosity reduction in heavy crude oils. Energy & Fuels 34, 5251-5257.


Heavy crude oils constitute the largest reserves; however, their extraction faces several challenges as a result of their high asphaltene content. Reducing the viscosity by physicochemical treatments or chemical transformation on heavy asphaltenes is still a challenge because of matrix complexity. On the other hand, the 1,3-dipolar cycloaddition (1,3-DC) reaction has been used to increase the solubility and rheological properties of graphene and fullerenes, suggesting that 1,3-DC on heavy crude oils can modify directly the chemical structure of titled compounds affecting their aggregation. Starting from Colombian heavy oils and purified asphaltenes, we used a set of chemical modifiers based on long-chain aliphatic and aromatic aldehydes and N-hexylglycine, followed by in situ reactions at several concentrations. Rheological measurements showed a significant reduction on crude oil viscosities up to 98% depending upon the alkyl chain and concentration; furthermore, 1,3-DC reactions between purified asphaltenes and chemical modifiers were followed by nuclear magnetic resonance experiments, which give credence to the viscosity reduction of heavy crude oils based on chemical reactivity.

Onofri, S., Balucani, N., Barone, V., Benedetti, P., Billi, D., Balbi, A., Brucato, J.R., Cobucci-Ponzano, B., Costanzo, G., Rocca, N.L., Moracci, M., Saladino, R., Vladilo, G., Albertini, N., Battistuzzi, M., Bloino, J., Botta, L., Casavecchia, P., Cassaro, A., Claudi, R., Cocola, L., Coduti, A., Di Donato, P., Di Mauro, E., Dore, L., Falcinelli, S., Fulle, M., Lombardi, A., Mancini, G., Maris, M., Maurelli, L., Murante, G., Negri, R., Pacelli, C., Pagano, I., Piccinino, D., Poletto, L., Prantera, G., Puzzarini, C., Rampino, S., Ripa, C.,

Rosi, M., Sanna, M., Selbmann, L., Silva, L., Skouteris, D., Strazzulli, A., Tasinato, N., Timperio, A.M., Tozzi, A., Tozzi, G.P., Trainotti, L., Ugliengo, P., Vaccaro, L., Zucconi, L., 2020. The Italian National Project of Astrobiology—Life in Space—Origin, presence, persistence of life in space, from molecules to extremophiles. Astrobiology 20, 580-582.

https://doi.org/10.1089/ast.2020.2247

The “Life in Space” project was funded in the wake of the Italian Space Agency's proposal for the development of a network of institutions and laboratories conceived to implement Italian participation in space astrobiology experiments. Of primary concern for this project is the study of the origin of life in the Universe, a focus that will promote investigation into prebiotic chemistry in various possible scenarios, whether in polar or nonpolar solvents (e.g., Titan's environment). Such results will link with study of the effects of simulated space conditions on possible chemical biosignatures. The limits of life as we know it will be investigated in ground-based experiments with microorganisms that have already demonstrated their resistance to extreme environments on Earth and to real or simulated space conditions. The potential survival of microorganisms will also be examined with up-to-date molecular methods. The ability of some microorganisms to produce atmospheric and surface biosignatures when exposed to simulated conditions will be tested and compared with the possible existence of biosignatures on potentially habitable exoplanets. Furthermore, the search for potentially habitable exoplanets, with space-based observational methods, will be optimized by way of dedicated climate models with the capacity to predict the detectability of atmospheric biosignatures for a broad range of planetary conditions.

The project embraces the four most important topics in astrobiological research, as listed below, along with relevant contributions from the participating Italian institutions.

Origins and evolution of organic compounds of biological significance in space (comets, asteroids, rocky planets, and moons);

Prebiotic syntheses, origin of life, and early life;

The limits of life and biological habitability: origin, evolution and adaptation of life in extreme environments on Earth and in space;

Biomarkers for life detection in the Solar System and on exoplanets.



Biomarkers are fossil organic molecules that contain information about either the precursor organisms or the environmental conditions that generated petroleum. They become useful tools to establish stratigraphic correlations, assess the depositional environment, and even check the history of organic matter. Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) is considered nearly indispensable when nitrogen-, oxygen-, or sulfur-containing (NSO) biomarker compounds need to be explored. In this contribution, we present an integrated study performed over 33 crude oils from the Putumayo Basin, Colombia. On the basis of gas chromatography–mass

spectrometry traditional analysis, we provide an interpretation outline built on classic hydrocarbon biomarkers. These outcomes allowed for establishing no biodegradation in most of the samples. Samples were grouped on the basis of whether the ratio Pr/Ph was higher or lower than 1 and further correlated with the abundance of oxygen compounds (classes O1 and O2) detected by negative ion electrospray ionization [(−) ESI] FT-ICR MS. In addition, saturate biomarkers allowed for validation of NSO parameters to sort crude oils according to their respective reservoirs, something crucial for production tests in new wells. The obtained results allowed for the correlation of the polar compound geochemistry to the influences of the source facies, depositional environment, and reservoir lithology of the Putumayo Basin.

Osmanov, Z., 2020. On the interstellar Von Neumann micro self-reproducing probes. International Journal of Astrobiology 19, 220-223.

https://doi.org/10.1017/S1473550419000259

In this paper we consider efficiency of self-reproducing extraterrestrial Von-Neumann micro scale robots and analyse the observational characteristics. By examining the natural scenario of moving in the HII clouds, it has been found that the timescale of replication might be several years and even less – making the process of observation quite promising. We have shown that by encountering the interstellar protons the probes might be visible at least in the infrared energy band and the corresponding luminosities might reach enormous values.

Ou, Q., Vannier, J., Yang, X., Chen, A., Mai, H., Shu, D., Han, J., Fu, D., Wang, R., Mayer, G., 2020. Evolutionary trade-off in reproduction of Cambrian arthropods. Science Advances 6, eaaz3376.


Trade-offs play a crucial role in the evolution of life-history strategies of extant organisms by shaping traits such as growth pattern, reproductive investment, and lifespan. One important trade-off is between offspring number and energy (nutrition, parental care, etc.) allocated to individual offspring. Exceptional Cambrian fossils allowed us to trace the earliest evidence of trade-offs in arthropod reproduction. †Chuandianella ovata, from the early Cambrian Chengjiang biota of China, brooded numerous (≤100 per clutch), small (Ø, ~0.5 mm) eggs under carapace flaps. The closely related †Waptia fieldensis, from the middle Cambrian Burgess Shale of Canada, also brooded young, but carried fewer (≤ 26 per clutch), larger (Ø, ~2.0 mm) eggs. The notable differences in clutch/egg sizes between these two species suggest an evolutionary trade-off between quantity and quality of offspring. The shift toward fewer, larger eggs might be an adaptive response to marine ecosystem changes through the early-middle Cambrian. We hypothesize that reproductive trade-offs might have facilitated the evolutionary success of early arthropods.

Padervand, M., Lichtfouse, E., Robert, D., Wang, C., 2020. Removal of microplastics from the environment. A review. Environmental Chemistry Letters 18, 807-828.

https://doi.org/10.1007/s10311-020-00983-1

The production of fossil fuel-derived, synthetic plastics is continually increasing, while poor plastic waste management has recently induced severe pollution issues. Microplastics are plastic particles

smaller than 5 mm. Microplastics are ubiquitous and slowly-degrading contaminants in waters and soils. Microplastics have long residence time, high stability, high potential of being fragmented and can adsorb other contaminants. Many aquatic species contain microplastics, which are in particular easily accumulated by planktonic and invertebrate organisms. Then, microplastics are transferred along food chains, leading to physical damages, decrease in nutritional diet value and exposure of the living organism to pathogens. Raw plastics contain chemical additives such as phthalates, bisphenol A and polybrominated diphenyl ethers that may induce toxic effects after ingestion by living organisms. Furthermore, the adsorption capability of microplastics makes them prone to carry several contaminants. Methods to remove microplastics from water and other media are actually needed. Here, we review microplastics occurrence, transport, raw polymers and additives, toxicity and methods of removal. Removal methods include physical sorption and filtration, biological removal and ingestion, and chemical treatments. Mechanisms, efficiency, advantages, and drawbacks of various removal methods are discussed.

Pal, N., Mandal, A., 2020. Oil recovery mechanisms of Pickering nanoemulsions stabilized by surfactant-polymer-nanoparticle assemblies: A versatile surface energies’ approach. Fuel 276, 118138.


In this article, we present a holistic approach to predict the interfacial activity of surfactant/polymer/nanoparticle stabilized Pickering nanoemulsions. Dynamic interfacial tension was measured and their profiles were generated in real time using pendant drop technique. The free detachment energies (Edet) at liquid-liquid interface decreased with time owing to gradual slipping of emulsifier(s) toward oleic phase, which translates to favorable oil displacement. Crude oil miscibility experiments confirmed synergistic influences of gemini surfactant, partially hydrolyzed polymer and silica nanoparticles. However, it was recognized that these investigations do not consider effects of rock mineralogy and solid-liquid dynamics, and hence, must be replaced with an evolved surface wetting approach. A “modified” Arrhenius model is tailor-made for nanoemulsions (as oil displacing fluids) to determine the surface activation energies and mechanistically discuss the altered wettability state of reservoir rock(s). Surfactant-polymer-nanoparticle (SPN) nanoemulsion exhibited enhanced oil displacement as compared to surfactant-stabilized and surfactant-polymer stabilized nanoemulsions. In summary, the surface energy approach was corroborated from theoretical as well as experimental investigations. Qualitative investigation of SPN nanoemulsion-based oil displacement was performed via microscopic imaging, infrared spectroscopy and wettability alteration technique by mimicking different flooding stages in oil-saturated reservoir models for application in enhanced oil recovery (EOR).

Palladino, G., Rizzo, R.E., Zvirtes, G., Grippa, A., Philipp, R.P., Healy, D., Alsop, G.I., 2020. Multiple episodes of sand injection leading to accumulation and leakage of hydrocarbons along the San Andreas/San Gregorio fault system, California. Marine and Petroleum Geology 118, 104431.


The presence of sand injections has been shown to enhance the likelihood of hydrocarbon traps within siliciclastic successions. Through the development of large interconnected networks of sills and dykes, sand injection complexes provide a volume of porous and permeable rocks within the low permeability host units. Overall, the formation of sand injection complexes requires extensive

fracturing and hydrofracturing, which can be particularly pronounced when sand injections are coupled with brittle tectonic deformation. In some circumstances, this process may threaten the integrity of the reservoir top seal thereby preventing further hydrocarbon accumulation. Studying exceptional exposures along the coastal area of Santa Cruz in California, we report evidence for top seal failure associated with injection episodes. Two distinct sand injection episodes are proposed. The first event, datable to the Late Miocene, resulted in large volumes of sand being emplaced within the top-seal units, and was followed by accumulation of hydrocarbons within the newly injected sandstones. Later, a series of brittle tectonic events, associated with the San Andreas/San Gregorio Fault System, caused remobilization and accumulation of sand along newly formed fault planes. Our case study documents this combination of pervasive brittle deformation and sandstone injection along fault structures, which can ultimately disrupt the integrity of a host unit leading top seal failure and leakage of hydrocarbons.

Pallud, C., Rhoades, C.C., Schneider, L., Dwivedi, P., Borch, T., 2020. Temperature-induced iron (III) reduction results in decreased dissolved organic carbon export in subalpine wetland soils, Colorado, USA. Geochimica et Cosmochimica Acta 280, 148-160.


Concentrations of dissolved organic carbon (DOC) in surface waters have rapidly increased across Europe and North America over the past few decades. The causes for such trends have yet to be fully understood, although several factors including elevated temperatures and decreased atmospheric deposition of acid, nitrogen and sulfur, are considered responsible for the release of carbon from soils into streams. In order to determine how seasonal temperature patterns and soil physical and chemical characteristics influence iron (Fe)(III) reduction and DOC release to pore-water in subalpine wetland soils, we measured potential Fe(II) and DOC export rates at low (6 °C) and high (18 °C) temperatures using flow-through reactors containing undisturbed wetland soils sampled in the Fraser Experimental Forest (Colorado, USA) in two wetland types and at two depths.

Higher temperature, soil organic matter, nitrogen, and extractable Fe concentrations, but lower soil C:N ratios and extractable manganese concentrations promoted Fe(II) export from soil to water. Additionally, Fe(III) reduction was 1.5–5 times more responsive to temperature in shallow, organic matter-rich soils, compared to organic-poor deeper soils. Conversely, DOC export declined at higher temperature in all soils, consistent with a temperature-related increase in carbon respiration by Fe(III)-reducers. While higher temperature is expected to reduce carbon storage in wetland soils, our findings suggest that temperature-related increase in Fe(III) reduction will not generate additional release of DOC from soils to rivers.

Paluszny, A., Graham, C.C., Daniels, K.A., Tsaparli, V., Xenias, D., Salimzadeh, S., Whitmarsh, L., Harrington, J.F., Zimmerman, R.W., 2020. Caprock integrity and public perception studies of carbon storage in depleted hydrocarbon reservoirs. International Journal of Greenhouse Gas Control 98, 103057.


Capture and subsurface storage of CO2 is widely viewed as being a necessary component of any strategy to minimise and control the continued increase in average global temperatures. Existing oil

and gas reservoirs can be re-used for carbon storage, providing a substantial fraction of the vast amounts of subsurface storage space that will be required for the implementation of carbon storage at an industrial scale. Carbon capture and storage (CCS) in depleted reservoirs aims to ensure subsurface containment, both to satisfy safety considerations, and to provide confidence that the containment will continue over the necessary timescales. Other technical issues that need to be addressed include the risk of unintended subsurface events, such as induced seismicity. Minimisation of these risks is key to building confidence in CCS technology, both in relation to financing/liability, and the development and maintenance of public acceptance. These factors may be of particular importance with regard to CCS projects involving depleted hydrocarbon reservoirs, where the mechanical effects of production activities must also be considered. Given the importance of caprock behaviour in this context, several previously published geomechanical caprock studies of depleted hydrocarbon reservoirs are identified and reviewed, comprising experimental and numerical studies of fourteen CCS pilot sites in depleted hydrocarbon reservoirs, in seven countries (Algeria, Australia, Finland, France, Germany, Netherlands, Norway, UK). Particular emphasis is placed on the amount and types of data collected, the mathematical methods and codes used to conduct geomechanical analysis, and the relationship between geomechanical aspects and public perception. Sound geomechanical assessment, acting to help minimise operational and financial/liability risks, and the careful recognition of the impact of public perception are two key factors that can contribute to the development of a successful CCS project in a depleted hydrocarbon reservoir.

Pan, B., Li, Y., Zhang, M., Wang, X., Iglauer, S., 2020. Effect of total organic carbon (TOC) content on shale wettability at high pressure and high temperature conditions. Journal of Petroleum Science and Engineering 193, 107374.


Rock wettability is a key parameter determining fluids distributions and migrations in hydrocarbon reservoirs. In shale rocks, the widespread existence of organic matter and the significant variation of total organic carbon (TOC) content lead to huge uncertainty on shale wettability. Therefore, this work systematically examines the dependence of shale wettability on TOC content (ranging from 1.2 wt% to 20.05 wt%). Multiple relations were probed experimentally, namely: 1) the effect of TOC content on n-dodecane (n-C12) contact angles for shale-methane (CH4)-n-C12 systems at 5 MPa and 50 °C; 2) the effect of TOC content on n-C12 contact angles for shale-carbon dioxide (CO2)-n-C12 systems at 5 MPa and 50 °C; 3) the effect of TOC content on brine contact angles for shale-brine-n-C12 systems at 0.1 MPa and 50 °C; 4) the effect of pressure (0.1 MPa–25 MPa), temperature (25 °C and 50 °C) and TOC content on brine contact angles for shale-CH4-brine systems. The results demonstrate that for shale-CH4-n-C12, shale-CO2-n-C12 and shale-brine-n-C12 systems, the affinity of n-C12 to shale increases with increasing TOC content. However, for shale-CH4-brine systems, the affinity of CH4 to shale increases firstly, then flatten out and afterwards increases again; while shale wettability shifted from water-wet to CH4-wet with TOC content increase. In addition, a larger pressure renders shale less hydrophilic while a higher temperature causes shale more hydrophilic. The temperature influence is reduced with TOC content increase. The results can aid in better understanding of shale wettability at reservoir conditions.

Pang, K.-N., Teng, F.-Z., Sun, Y., Chung, S.-L., Zarrinkoub, M.H., 2020. Magnesium isotopic systematics of the Makran arc magmas, Iran: Implications for crust-mantle Mg isotopic balance. Geochimica et Cosmochimica Acta 278, 110-121.


Continental crust loses Mg by lower crustal foundering and chemical weathering to become its intermediate-silicic composition. Both processes should preferentially retain heavy Mg isotopes in the crust, yet the estimated Mg isotopic ratio for the bulk continental crust is indistinguishable from that for unmodified mantle. This can be elucidated by two notions that are not mutually exclusive: (i) the basaltic parent to the crust has Mg isotopes lighter than the mantle and has since become mantle-like as a result of Mg loss by igneous and weathering fractionation, and (ii) heavy Mg isotopes in the continental crust are constantly balanced by a hidden input of light Mg isotopes. Arc magmas are arguably building blocks of the continental crust and their Mg isotopic signature could be used to place limits on the above views. Here, we conducted a Mg isotopic study of the Makran arc, a rare continental arc in Iran within the Alpine-Himalayan orogenic belt. The measured Mg isotopic ratios for most mafic and intermediate samples are mantle-like with δ26Mg values ranging from −0.32‰ to −0.20‰. After excluding dubious samples affected by alteration, the silicic samples span a broad range of isotopic ratios with δ26Mg values ranging from −0.32‰ to +0.32‰, beyond that of unmodified mantle (δ26Mg = −0.25 ± 0.04‰). The isotopic data form a trend from mantle-like δ26Mg at relatively high MgO towards elevated δ26Mg at low MgO, requiring the isotopic variability be related to differentiation in an open system involving assimilation of high-δ26Mg crustal rocks. Our results are generally consistent with Mg isotopic data compiled for global arcs where magmas have Mg isotopic ratios ranging from mantle-like to ∼0.7 per mil above the mantle range, and compositions substantially below that range are rare. Thus, heavy Mg isotopes in the continents predicted by igneous and weathering fractionation might have been compensated by a hidden input of light Mg isotopes, which is presumably in the form of carbonates, leading to a bulk crustal Mg isotopic composition that is mantle-like.



Brunei Bay is one of the most important marine environments of East Malaysia (South China Sea), covering many productive ecosystems with activities including fisheries, tourism, and main shipping lanes for petroleum transfers. Evaluation of the sources and distributions of steroids in the surface sedimentary organic matter was carried out by gas chromatography–mass spectrometry (GC–MS). The concentrations of the total identified sterols (TIS) ranged between 0.81 and 12.69 μg g−1 dry weight, and the total sterones were between 0.11 and 5.66 μg g−1 dry weight. The coprostanol level was comparatively low (<0.10 μg g−1), and the multi-biomarker proxies indicated that the region did not exhibit significant contamination from sewage effluents. Principal component analysis (PCA) revealed the coastal environment of the study area was dominated by allochthonous (mainly terrestrial) organic matter input.

Pang, Z., Tao, S., Zhang, Q., Zhang, B., Zhang, T., Yang, X., Wu, Y., Fan, J., Yuan, M., 2020. Evaluation methods of profitable tight oil reservoir of lacustrine coquina: A case study of Da'anzhai Member of Jurassic in the Sichuan Basin. Acta Geologica Sinica - English Edition 94, 418-429.

https://doi.org/10.1111/1755-6724.14369

Based on core observation, cast and fluorescent thin sections, FESEM and ESEM, coquina in Da'anzhai Member of Jurassic in Sichuan Basin were examined systematically. Together with production data and logging evaluation, a method for lacustrine coquina evaluation based on geological theory was established up. In the article, two aspects of the study were elaborated, characteristics of favorable reservoirs, and a “five step” evaluation method for favorable coquina ‐reservoir. According to the correlation between porosity and production data, porosity is not effective in finding high quality coquina reservoir of this area. Whereas micro research of reservoir samples from a high productivity well revealed that sparry coquina is the best lithofacies, with the most developed micro storage space of various kinds. After the favorable reservoir was sorted out, a five step method evaluating the coquina reservoir was worked out. Correlation of GR value and rock‐ types suggests that GR<30 API is an effective evaluation parameter in identifying profitable reservoir lithofacies. Meanwhile, the combination of profitable reservoir rock thickness and production data revealed that the reservoirs with the highest potentiality are those with thickness of 3–18 m. Fractures are more developed in faults, folds and structural noses in the study area. Organic acid is discharged massively before the peak of hydrocarbon generation, leading to the formation of dissolution pores in the reservoir. The evaluation of organic acid was made by using the source rock indexes. After evaluating the four factors, and compiling their distribution maps, the maps were overlapped to predict favorable reservoir zones, and 7 first class and 9 second class favorable zones of coquina were picked out.

Pannekens, M., Voskuhl, L., Meier, A., Müller, H., Haque, S., Frösler, J., Brauer, V.S., Meckenstock, R.U., 2020. Densely populated water droplets in heavy-oil seeps. Applied and Environmental Microbiology 86, e00164-20.


Abstract: Most of the microbial degradation in oil reservoirs is believed to take place at the oil-water transition zone (OWTZ). However, a recent study indicates that there is microbial life enclosed in microliter-sized water droplets dispersed in heavy oil of Pitch Lake in Trinidad and Tobago. This life in oil suggests that microbial degradation of oil also takes place in water pockets in the oil-bearing rock of an oil leg independent of the OWTZ. However, it is unknown whether microbial life in water droplets dispersed in oil is a generic property of oil reservoirs rather than an exotic exception. Hence, we took samples from three heavy-oil seeps, Pitch Lake (Trinidad and Tobago), the La Brea Tar Pits (California, USA), and an oil seep on the McKittrick oil field (California, USA). All three tested oil seeps contained dispersed water droplets. Larger droplets between 1 and 10 μl revealed high cell densities of up to 109 cells ml−1. Testing for ATP content and LIVE/DEAD staining showed that these populations consist of active and viable microbial cells with an average of 60% membrane-intact cells and ATP concentrations comparable to those of other subsurface ecosystems. Microbial community analyses based on 16S rRNA gene amplicon sequencing revealed the presence of known anaerobic oil-degrading microorganisms. Surprisingly, the community analyses showed similarities between all three oil seeps, revealing common OTUs, although the sampling sites were thousands of

kilometers apart. Our results indicate that small water inclusions are densely populated microhabitats in heavy oil and possibly a generic trait of degraded-oil reservoirs.

Importance: Our results confirmed that small water droplets in oil are densely populated microhabitats containing active microbial communities. Since these microhabitats occurred in three tested oil seeps which are located thousands of kilometers away from each other, such populated water droplets might be a generic trait of biodegraded oil reservoirs and might be involved in the overall oil degradation process. Microbial degradation might thus also take place in water pockets in the oil-bearing oil legs of the reservoir rock rather than only at the oil-water transition zone.

Paris, V., Pizzigoni, A., Adriaenssens, S., 2020. Statics of self-balancing masonry domes constructed with a cross-herringbone spiraling pattern. Engineering Structures 215, 110440.


The Brunelleschi herringbone pattern was certainly known by the Sangallo in the 16th century, who developed their own self-balanced construction technology for masonry domes based on the cross-herringbone spiraling pattern. Such technology was used for over one century in Italy to build masonry domes without shoring and formwork. However today it is not well known how this cross-herringbone spiraling pattern enables equilibrium states of self-balancing masonry domes. Therefore, in this study we demonstrate how this pattern permits equilibrium states of an octagonal masonry dome using two analysis approaches (i.e. Discrete Element Model and Limit State Analysis). The Discrete Element Model analysis has been performed to show the existence of the plate-bande resistance within the pattern. Even in the construction stages, these plate-bande resistance systems are capable of preventing sliding and overturning of the masonry dome. With the global self-balanced static equilibrium state proven, a Limit State Analysis is then adopted to estimate a possible thrust configuration needed to achieve equilibrium of the plate-bandes and the whole dome at each construction stage. It is shown that the value of the mortar friction has little influence on the static behavior of the dome. The study of the cross-herringbone spiraling pattern does not merely serve historical or conservation purposes. It has practical applications for the development of dry self-balanced robotic masonry construction technologies, particularly suited for unmanned aerial vehicles.

Park, Y., Swanson-Hysell, N.L., MacLennan, S.A., Maloof, A.C., Gebreslassie, M., Tremblay, M.M., Schoene, B., Alene, M., Anttila, E.S.C., Tesema, T., Haileab, B., 2020. The lead-up to the Sturtian Snowball Earth: Neoproterozoic chemostratigraphy time-calibrated by the Tambien Group of Ethiopia. GSA Bulletin 132, 1119-1149.

https://doi.org/10.1130/B35178.1

The Tonian-Cryogenian Tambien Group of northern Ethiopia is a mixed carbonate-siliciclastic sequence that culminates in glacial deposits associated with the first of the Cryogenian glaciations—the Sturtian “Snowball Earth.” Tambien Group deposition occurred atop arc volcanics and volcaniclastics of the Tsaliet Group. New U-Pb isotope dilution–thermal ionization mass spectrometry (ID-TIMS) dates demonstrate that the transition between the Tsaliet and Tambien Groups occurred at ca. 820 Ma in western exposures and ca. 795 Ma in eastern exposures, which is consistent with west to east arc migration and deposition in an evolving back-arc basin. The

presence of intercalated tuffs suitable for high-precision geochronology within the Tambien Group enable temporal constraints on stratigraphic data sets of the interval preceding, and leading into, the Sturtian glaciation. Recently discovered exposures of Sturtian glacial deposits and underlying Tambien Group strata in the Samre Fold-Thrust Belt present the opportunity to further utilize this unique association of tuffs and carbonate lithofacies. U-Pb ID-TIMS ages from zircons indicate that Tambien Group carbonates were deposited from ca. 820 Ma until 0–2 m.y. before the onset of the Sturtian glaciation, making the group host to a relatively complete carbonate stratigraphy leading into this glaciation. New δ13C and 87Sr/86Sr data and U-Pb ID-TIMS ages from the Tambien Group are used in conjunction with previously published isotopic and geochronologic data to construct newly time-calibrated composite Tonian carbon and strontium isotope curves. Tambien Group δ13C data and U-Pb ID-TIMS ages reveal that a pre-Sturtian sharp negative δ13C excursion (referred to as the Islay anomaly in the literature) precedes the Sturtian glaciation by ∼18 m.y., is synchronous in at least two separate basins, and is followed by a prolonged interval of positive δ13C values. The composite Tonian 87Sr/86Sr curve shows that, following an extended interval of low and relatively invariant values, inferred seawater 87Sr/86Sr rose ca. 880–770 Ma, then subsequently decreased leading up to the ca. 717 Ma initiation of the Sturtian glaciation. These data, when combined with a simple global weathering model and analyses of the timing and paleolatitude of large igneous province eruptions and arc accretion events, suggest that the 87Sr/86Sr increase was influenced by increased subaerial weathering of radiogenic lithologies as Rodinia rifted apart at low latitudes. The following 87Sr/86Sr decrease is consistent with enhanced subaerial weathering of arc lithologies accreting in the tropics over tens of millions of years, lowering pCO2 and contributing to the initiation of the Sturtian glaciation.



Geoscientists quickly recognized the broad applicability of Raman micro-probe spectroscopy to the Earth and planetary sciences, especially after commercially built microprobe instruments became available in the early 1980s. Raman spectra are sensitive to even minor (chemical or structural) perturbations within chemical bonds in (even amorphous) solids, liquids, and gases and can, thus, help identify, characterize, and differentiate between individual minerals, fluid inclusions, glasses, carbonaceous materials, solid solution phases, strain in minerals, and dissolved species in multi-component solutions. The articles in this issue explore how Raman spectroscopy has deepened and broadened our understanding of geological and extraterrestrial materials and processes.

Petrova, V.I., Batova, G.I., Kursheva, A.V., Litvinenko, I.V., Morgunova, I.P., 2020. Hydrocarbon molecular markers as indicators of the Late Cenozoic sedimentation on the Amerasian continental margin (Arctic Ocean). Russian Geology and Geophysics 61, DOI: 10.15372/RGG2019084.


The main factors controlling the bulk sedimentation in the region of the Mendeleev Rise and the adjacent part of the Arctic Ocean during the late Cenozoic were studied using a complex of geomorphological, lithological, and organic geochemical data. Samples for the study were collected during the cruises of the R/V Akademik Fedorov in 2000, 2005, and 2007 and the icebreaker Kapitan

Dranitsyn in 2012. Analysis of the group and molecular compositions of the dispersed organic matter (DOM) in bottom sediments has shown that the input of terrigenous sediments enriched with abrasion products of lithified rocks from the eastern source province determines the Holocene-Pleistocene sedimentation on the continental slope of the East Siberian Sea and the Podvodnikov Basin. The individual characteristics of DOM of the late Cenozoic deposits from the underwater mountains of the Mendeleev Rise reflect the wide diversity of sedimentary sources and depositional conditions. Subaqueous erosion and redeposition of denudation products of source rocks and pre-Holocene sediments play an important part in sedimentation together with a terrigenous flow and ice transport.

Pillai, A.S., Chandler, S.A., Liu, Y., Signore, A.V., Cortez-Romero, C.R., Benesch, J.L.P., Laganowsky, A., Storz, J.F., Hochberg, G.K.A., Thornton, J.W., 2020. Origin of complexity in haemoglobin evolution. Nature 581, 480-485.

https://doi.org/10.1038/s41586-020-2292-y

Most proteins associate into multimeric complexes with specific architectures, which often have functional properties such as cooperative ligand binding or allosteric regulation. No detailed knowledge is available about how any multimer and its functions arose during evolution. Here we use ancestral protein reconstruction and biophysical assays to elucidate the origins of vertebrate haemoglobin, a heterotetramer of paralogous α- and β-subunits that mediates respiratory oxygen transport and exchange by cooperatively binding oxygen with moderate affinity. We show that modern haemoglobin evolved from an ancient monomer and characterize the historical ‘missing link’ through which the modern tetramer evolved—a noncooperative homodimer with high oxygen affinity that existed before the gene duplication that generated distinct α- and β-subunits. Reintroducing just two post-duplication historical substitutions into the ancestral protein is sufficient to cause strong tetramerization by creating favourable contacts with more ancient residues on the opposing subunit. These surface substitutions markedly reduce oxygen affinity and even confer cooperativity, because an ancient linkage between the oxygen binding site and the multimerization interface was already an intrinsic feature of the protein’s structure. Our findings establish that evolution can produce new complex molecular structures and functions via simple genetic mechanisms that recruit existing biophysical features into higher-level architectures.



Oil refining produces vast quantities of wastewater with harmful contaminants that can be released back into the environment with a possible risk of toxicity to aquatic wildlife and human populations. Hence the importance of adequate wastewater treatment to achieve safe effluents that protect both ecological and human health. However, some refining effluents are linked to serious pollution problems even after treatment, partly because little progress has been made in determining the causative agents of the observed biological effects, resulting in non-targeted treatment. Here, we followed an effect-directed analysis (EDA) approach using Aliivibrio fischeri as biosensor to show that naphthenic acids (NAs) are important components of refining wastewater resulting from the processing of heavy crude oil. Furthermore, we demonstrate that besides mixture effects, NAs have

a significant contribution to the toxicity exerted by these effluents. Profiling of the NA mixture was conducted using high resolution liquid chromatography-Orbitrap, which evidenced that O2 NAs corresponded to 90% of the NAs detected. Our findings contrast with previous reports where classic NAs have been found between 15% and 72% and could explain the significant biological effects observed in A. fischeri. This study broadens the body of evidence pointing at mixture effects and low-concentration pollutants as the cause of toxicity from RWW, in addition to NAs resulting from the processing of heavy crude oil. Our results can serve as a starting point for setting better effluent discharge standards relevant to oil refining wastewater resulting from heavy crude oil and help improve wastewater treatment plants to reduce effluent toxicity.

Pisarzowska, A., Becker, R.T., Aboussalam, Z.S., Szczerba, M., Sobień, K., Kremer, B., Owocki, K., Racki, G., 2020. Middlesex/punctata Event in the Rhenish Basin (Padberg section, Sauerland, Germany) – Geochemical clues to the early-middle Frasnian perturbation of global carbon cycle. Global and Planetary Change 191, 103211.


A positive carbon stable isotope excursion of about 3‰ is documented in the topmost lower Frasnian at Padberg, eastern Rhenish Massif, as a muted record of the worldwide early−middle Frasnian isotopic perturbation (punctata Event; up to 6–8‰ shift in both δ13Ccarb and δ13Corg elsewhere), comparable with the Appalachian δ13C curve. This German isotopic signature occurs in a 12 m thick calciturbidite succession and correlates well with the three-step chemostratigraphic pattern known from the Holy Cross Mountains, Poland. It is especially clear in the δ13Corg shifts, whilst δ13Ccarb (and elemental geochemical) proxies are partly biased by post-sedimentary alterations. The New York State, Polish, Nevada and Padberg conodont successions place the onset of the major positive δ13C excursion slightly beneath the early–middle Frasnian boundary, with Ancyrodella nodosa (previously Ad. gigas form 1) as the main conodont guide species, and coincident with the Middlesex transgression and spread of cold, nutrient-rich, poorly oxygenated water masses. In the light of geochemical proxies, enhanced primary production and oxygen deficiency occurred evidently in the Rhenish Basin during the punctata Event. Moderate Hg enrichments in the early Middlesex/punctata Event interval suggest a volcanic signature. However, conclusive data from other regions are required to differentiate between effects of the regionally well-known synsedimenary magmatism and of a possible global volcanic trigger for the biogeochemical perturbation.

Planavsky, N., Hood, A., Tarhan, L., Shen, S., Johnson, K., 2020. Store and share ancient rocks. Nature 581, 137-139.

https://www.nature.com/articles/d41586-020-01366-w

Comment: Geological samples must be archived for all if we are to solve the riddles of Earth’s complex history

Geologists think they know the basics of Earth’s history. Liquid water has flowed on the planet for 4 billion years1. Tiny amounts of oxygen first gathered in the atmosphere about 2.3 billion years ago2. And the planet went through many periods of climatic upheaval, from freezing completely 700

million years ago3 to warming so rapidly about 250 million years ago that more than 80% of marine species were lost4,5. It has had many more ups and downs.

This story can be reconstructed using data wrestled from ancient rocks. But as geologists learn more, our planet’s tale is getting muddier rather than clearer. Controversies have erupted in the past two decades over many aspects of the chemical record of the early Earth, including the evolution of life, environments and past long-term climate (see ‘Contentious timeline’).

For example, variations in carbon-isotope ratios in carbonate rocks have conventionally been interpreted as recording drastic global environmental changes, including huge episodes of volcanism or bursts of oxygen6. By contrast, some researchers suggest that these same records have been changed over time by local environmental processes, and that they do not provide information about Earth’s ancient history7. This debate can be resolved only by applying a variety of geological and chemical tools8,9 to the same samples used to generate the carbon-isotope results.

Attempts over the past decade to answer questions using better tools and larger databases have only amplified disputes. To make matters worse, too often, rock samples are not archived or shared. It is common for samples to be held by researchers in private collections instead of in accessible, curated institutional archives or museums. That’s a problem, because different geoscience teams cannot check each other’s work to test whether published results are robust and can be replicated.

We call on researchers, museums, funders, scientific societies and journals to ensure that all samples of sediment and sedimentary rock from which geochemical data have been produced and published are curated, archived and made available to members of the research community.

Reproducibility crisis

Geological records are complicated and hard to interpret. It is easy to reach contradictory conclusions, most commonly for the following four reasons.

Proxies and archives. Several geochemical methods can be used to infer past conditions such as temperature. The same method applied to different sedimentary rock types can lead to inconsistencies. For example, the ratio of heavy to light oxygen isotopes in chemical precipitates (such as chert, carbonate or apatite) tracks the seawater temperatures under which these minerals formed. But even in the same piece of rock, the reconstructed temperatures can be different depending on whether they are measured in a fossil or in a bulk aggregate of the entire rock sample. This is because rocks are inherently combinations of different minerals, which might have formed during different stages of a rock’s long geological history. The consequences for understanding past climates can be dramatic. For example, it is still not clear whether an interval of extreme heat killed marine organisms during the ‘Great Dying’ 250 million years ago. Sulfide toxicity, ocean acidification and carbon dioxide poisoning have also been proposed as possible mechanisms for killing off organisms at this time4.

Similarly, the question of whether oxygen levels were low enough to have delayed the emergence of animals for around 4 billion years — or most of Earth’s history, thus addressing Charles Darwin’s dilemma of why complex life appeared so late in the fossil record — depends on which rocks are studied and what analytical methods are used8. For example, an analysis of gas bubbles in sedimentary rocks9 has suggested that atmospheric oxygen levels on Earth’s surface would have been high enough to support animals as early as 2.6 billion years ago. However, this clashes with a compelling body of evidence indicating that atmospheric oxygen concentrations were vanishingly

low at this time10,11. Refining such proxies is extremely challenging when different teams cannot work on the same samples.

Geographical and temporal variation. Rock samples that are used to tackle the same research question are often collected from different places, where the rocks were deposited at various times and in vastly different environments. This can result in completely distinct answers. For example, mercury enrichments in sediments are used as a tracer of large episodes of volcanic activity and their links to mass extinction events12. However, mercury enrichments can also result from wildfires or from local depositional conditions that lead to heavy-metal uptake by sedimentary organic matter12. Furthermore, diverse geographical settings can record mercury enrichments differently, depending on aspects such as water depth, dissolved oxygen concentrations, the rate of sediment deposition and the type and location of the volcanoes themselves12,13. All of this can lead to spurious correlations between volcanism and extinction events. It is difficult to disentangle signals of global changes in the Earth system through time from local environmental variability using only reported geochemical data sets.

Analytical reproducibility. Experiments can be hard to repeat even if rocks are pristinely preserved. Measurements are routinely checked against those of geochemical standard materials, the compositions of which are internationally validated. Yet there is always the possibility of errors during analysis. These can arise from differences in sample preparation (such as in rock-crushing techniques or in the type of acid used to prepare a sample) and instrumentation (machine type, tuning) to variations in laboratory conditions. For instance, boron-isotope measurements on marine carbonates are one of the key tools used to reconstruct atmospheric CO2 levels14. Various approaches to making such measurements can lead to CO2 estimates that differ by more than 400 parts per million14,15 — roughly equivalent to the total concentration of CO2 found in the atmosphere today.

Contamination and alteration. As sediments become rocks, they undergo many processes that can alter the geochemical signals of where and how they formed. Sediments laid down on sea floors or lake bottoms can experience changes in water level or salinity, for example if they are flushed with meltwater. Hydrothermal processes and heat at depth might leach chemicals from the rock and alter the mineral composition.

Rocks collected near the surface can be altered by groundwater or other contaminants, such as oil used to drill cores. For example, organic remains in rocks once thought to be evidence for oxygen production by pioneering photosynthetic microorganisms 2.7 billion years ago are now acknowledged to be probable contamination from the modern petroleum products used to drill the rocks from the ground16. Similarly, debate is raging over whether the chemical composition of ancient rocks records microbial oxygen production extending as far back as 3 billion years ago, or whether those rocks have been compromised by contact with recent groundwater17.

Precious prizes

Without the ability to access and remeasure samples, it can be challenging to work out whether disparities in results and views stem from complexity in Earth’s history, from sampling of rocks with different levels of alteration or from analytical issues. Yet sample archiving is not part of the standard protocol for inorganic or organic geochemical work, nor for some palaeoclimate work (other than, for example, ocean drill-core or ice-core samples, which are stored).

Why has this situation arisen? Many scientists are reluctant to share samples they have struggled hard to collect. After all, there are high costs associated with fieldwork on outcrops and drilling programmes. Research groups might want to perform multiple geochemical studies on a single set of samples, and this takes time. Large geochemical studies that use unconventional isotope systems can take several years to extract a data set18.

Other obstacles to archiving samples include how to fund archiving, where to store samples and how they are to be managed. Clearly, no single museum can hold all geological and geochemical samples. Museums would need to increase staff, space and funds for such collections.

Initiatives for archiving materials in other fields could serve as models. These include the Global Genome Initiative, a shared data protocol for frozen tissue repositories (see go.nature.com/3f4erur), and the Integrated Digitized Biocollections project for biological digital data. Global databases of these sample archives and their accessory information, building on initiatives such as the International Geo Sample Number (IGSN), will also be needed to assign unique identifiers and maintain inter-collection records.

Some Earth-science fields already deposit samples in publicly accessible museums. For instance, palaeontologists have been required to do so for samples formally described in scientific publications for more than 150 years. Likewise, museums hold type specimens of fossils, meteorites and biological samples. Well-funded drilling projects also have strict archiving policies and well-curated core libraries, such as that for the International Ocean Discovery Program (see go.nature.com/2xoumhh).

The FAIR data initiative offers strict guidelines on data archiving and has been adopted by many journals that publish Earth- and environmental-science research, including Science and Nature (see go.nature.com/2wv2jxd). Although the recommended best practices of this initiative already include sample archiving, this is not yet strictly implemented as a formal requirement for publication.

Forging consensus

Together, researchers, natural history museums, journal editors, scientific societies and funding agencies must develop and implement standardized archival policies. We recommend that the following steps are taken.

Geochemical researchers should routinely send their samples to museums. To encourage buy-in, we suggest an embargo period for delaying new studies by other research groups on each set of samples from which geochemical data have been published. Geochemists must also work with museums to broaden the conventional definition of collections to include a range of different materials, from fist-sized specimens to rock fragments, powders and mineral grains. Geochemists should work with custodians of protected lands to encourage the inclusion of archival policies and procedures for geochemical samples collected under research permits.

Natural history museums should broaden their mission to archive and curate geological samples. They should assign unique identifiers that can be logged in digital databases. Curators must decide how much of a sample can be withdrawn, because geochemical tests are destructive. Where resources are tight, museums will need to evaluate the spatial, financial and scientific capacity of collections, and determine which samples are most essential to curate.

Scientific societies must tackle the question of what constitutes an acceptable repository. For instance, the Meteoritical Society’s Committee on Meteorite Nomenclature does this. Scientific societies such as the Geochemical Society in Washington DC and the European Association of Geochemistry in Aubière, France, should begin to recommend suitable institutions.

Recent decades have demonstrated that rapid changes in data archiving are possible when clear guidelines — and editorial mandates — are in place. So we would like to see journals go further in supporting the FAIR data initiative, by making requests to archive samples and assignment of database unique identifiers mandatory for publication.

Many scientific journals regulate data archiving using a checklist. We recommend that this practice be implemented for sample archiving, and that repository-issued sample identifiers (as well as unique identifiers assigned by inter-institutional database efforts such as the IGSN) be included in each paper. All major changes to a field take time to develop, and changes at the editorial level can help to nudge them along. Journals could implement these policies on a relatively short timescale, as long as exceptions are initially made to the archiving mandate when requests for sample deposition are declined.

Funding agencies should require that researchers’ grant proposals include sample archival procedures and that budgets include curation fees. Critics might argue that archiving will decrease the money available for other scientific endeavours. In our view, a sample stewardship plan should be viewed as equivalent to budget-line items for data archiving, publishing fees or institutional overhead costs that support other essential components of the research workflow.

We strongly recommend against setting universal fees. Samples will vary widely in nature and size, from kilogram-scale samples to micrograms of separated minerals. So the cost to museums will likewise depend on institutional resources and expertise. However, we have confidence that museums, working with funding agencies and researchers, will ensure that fees are self-regulating.

Collections of palaeontological samples provide an analogue for the practices needed. They also show that large-scale archiving is possible. The Invertebrate Paleontology Division of the Yale Peabody Museum of Natural History in New Haven, Connecticut, for instance, holds about 4.5 million specimens and takes in more than 2,000 samples a year, on average. As well as its curatorial researchers, the division is supported by two full-time staff members, one of whom handles the new acquisitions.

We estimate that roughly 200,000 new sedimentary geochemical samples are analysed each year. We therefore reiterate that curation fees — even modest ones — should be incorporated into the budgets of research-grant proposals. Regardless of the current availability of space and curatorial support in individual museums, extra funds will be needed to meet the demand for archiving sedimentary geochemical samples.

The guidelines we offer will need to be discussed and revised by the community and institutions. Nonetheless, all best practices must rest on a shared commitment — to ensure that scientific data are not divorced from scientific samples.

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Planavsky, N.J., Reinhard, C.T., Isson, T.T., Ozaki, K., Crockford, P.W., 2020. Large mass-independent oxygen isotope fractionations in Mid-Proterozoic sediments: Evidence for a low-oxygen atmosphere? Astrobiology 20, 628-636.

https://doi.org/10.1089/ast.2019.2060

Earth's ocean-atmosphere system has undergone a dramatic but protracted increase in oxygen (O2) abundance. This environmental transition ultimately paved the way for the rise of multicellular life and provides a blueprint for how a biosphere can transform a planetary surface. However, estimates of atmospheric oxygen levels for large intervals of Earth's history still vary by orders of magnitude—foremost for Earth's middle history. Historically, estimates of mid-Proterozoic (1.9–0.8 Ga) atmospheric oxygen levels are inferred based on the kinetics of reactions occurring in soils or in the oceans, rather than being directly tracked by atmospheric signatures. Rare oxygen isotope systematics—based on quantifying the rare oxygen isotope 17O in addition to the conventionally determined 16O and 18O—provide a means to track atmospheric isotopic signatures and thus potentially provide more direct estimates of atmospheric oxygen levels through time. Oxygen isotope signatures that deviate strongly from the expected mass-dependent relationship between 16O, 17O, and 18O develop during ozone formation, and these “mass-independent” signals can be transferred to the rock record during oxidation reactions in surface environments that involve atmospheric O2. The magnitude of these signals is dependent upon pO2, pCO2, and the overall extent of biospheric productivity. Here, we use a stochastic approach to invert the mid-Proterozoic Δ17O record for a new estimate of atmospheric pO2, leveraging explicit coupling of pO2 and biospheric productivity in a biogeochemical Earth system model to refine the range of atmospheric pO2 values that is consistent with a given observed Δ17O. Using this approach, we find new evidence that atmospheric oxygen levels were less than ∼1% of the present atmospheric level (PAL) for at least some intervals of the Proterozoic Eon.

Pletnev, S.P., Wu, Y., Romanova, A.V., Annin, V.K., Utkin, I.V., Vereshchagina, O.F., 2020. Negative δ13C excursions in foraminiferal records: The Holocene history of methane events in the central Sea of Okhotsk. Russian Geology and Geophysics 61, DOI: 10.15372/RGG2019107.


Several negative δ13C excursions in benthic foraminifera from gas-bearing core LV50-05 sampled offshore on the eastern slope of Sakhalin Island, Sea of Okhotsk, in an area of active methane seepage record the local history of methane events (ME). The core chronostratigraphy has been contsrained from AMS 14C ages and biostratigraphic data. Benthic foraminifera ( Nonionellina labradorica and Uvigerina parvocostata ) from some core intervals show normal marine δ13C values (about -1‰), but some intervals are marked by extremely depleted compositions as low as -34.5‰ δ13C (relative to VPDB). The negative δ13C excursions are interpreted as a record of seabed methane emanation during primary and secondary biomineralization of carbonate foraminifera. The results reveal four Holocene methane events (ME) in the area: two brief (ME-1 at 700-900 yr BP and ME-2 at 1200-1400 yr BP) and two long (ME-3 at 2500-4700 yr BP and ME-4 at 7400-10000 yr BP) events.

Plummer, P.S., 2020. GC profiles of oils reflect organic maturity rather than depositional environment of parent source rock: examples from Central Australia. Australian Journal of Earth Sciences 67, 739-747.

https://doi.org/10.1080/08120099.2020.1710861

Review and analysis of 1332 gas chromatography (GC) n-alkane traces of oils from the Cooper and Eromanga basins indicate the shape of any GC trace profile is primarily controlled by the degree of organic maturity (early, peak or late) at which the oils were expelled from the parent source rock, rather than indicating the depositional environment, and hence organic composition, of that source rock. The depositional environment of a source rock may still be inferred, however, from the position of the n-alkane maximum on the GC traces of early expulsion oils in association with the pour point of the oil. Departures of GC trace profiles from the standard early, peak or late expulsion profiles can indicate mixing of oils of different maturities, while variations in the GC trace profiles of oils within adjacent reservoir units may indicate phase separation of the parent liquid, or possible seal breach by an accumulation that exceeds the capacity of its overlying seal.

Ponomarchuk, V.A., Dobretsov, N.L., Lazareva, E.V., Zhmodik, S.M., Karmanov, N.S., Tolstov, A.V., Pyryaev, A.N., 2020. Evidence of microbial-induced mineralization in rocks of the Tomtor Carbonatite Complex (Arctic Siberia). Doklady Earth Sciences 490, 76-80.

https://doi.org/10.1134/S1028334X20020117

Carbonates of the Tomtor complex of ultramafic alkaline rocks and carbonatites (the northern part of the Republic of Sakha Yakutia) are distinguished by a wide range of carbon isotopic composition δ13C from +2 to –59.9‰. The geological position, localization patterns, mineral and chemical compositions and the relationship with REE mineralization of samples with values of δ13C carbonates from –25 to –59‰ are characterized. The formation of abnormally low δ13C in carbonates is determined by the biogenic oxidation of methane from δ13Cmet to –70‰.

Popall, R.M., Bolhuis, H., Muyzer, G., Sánchez-Román, M., 2020. Stromatolites as biosignatures of atmospheric oxygenation: Carbonate biomineralization and UV-C resilience in a Geitlerinema sp. - dominated culture. Frontiers in Microbiology 11, 948. doi: 10.3389/fmicb.2020.00948.


Modern stromatolites are key to the record of past microbial activity preserved in fossil carbonate deposits. Mono-phototrophic cultures dominated by the cyanobacterium Geitlerinema sp. were obtained from a laboratory-maintained, low magnesium-calcite stromatolite originating from Lagoa Vermelha, Brazil. This lagoonal system has been described as a Precambrian analog, illustrating a period of photosynthetically induced atmospheric oxygenation, which created a global sanctuary from shortwave solar radiation and enabled the evolution of modern life on Earth. The enrichment cultures precipitate carbonates in minimal media, suggesting that cyanobacterial photosynthesis and extracellular polymeric substance production may be crucial in the mineralization of the studied stromatolite. We further show that Geitlerinema sp. can build and maintain filamentous mats under long-term UV-C exposure. Our results suggest that present day stromatolites dominated by cyanobacteria may be interpreted as biosignatures of atmospheric oxygenation and have implications for the search for putative biological traces on Mars.



In this study, we investigated Early Cretaceous (Valanginian, ca. 135 million years ago) climate from subtropical to boreal palaeolatitudes. Combined carbonate clumped isotope and oxygen isotope data derived from sub-arctic, boreal, and sub-tropical fossil belemnite rostra (Mollusca: Cephalopoda) provide new palaeotemperature estimates as well as a constraint on the oxygen isotope composition of seawater. Our belemnite data reveal balmy high-latitude marine temperatures (ca. 22 °C) and warm sub-tropical temperatures (ca. 31 °C). Supplementing our clumped isotope-based temperature estimates with published TEX86 data results in a conservative reconstruction of a latitudinal temperature gradient that is reduced compared to modern conditions. We find that modelling efforts are close to reproducing tropical temperatures when high pCO2 levels are considered. Warm polar temperatures imply, however, that data-model discrepancies remain. Early Cretaceous seawater oxygen isotope values show a modern profile and are much more positive (up to 1.5‰ SMOW) than typically assumed. Based on our findings, if the positive Cretaceous seawater δ18O values are not considered, carbonate δ18O thermometry would underestimate temperatures, most acute at middle and tropical latitudes.

Priharto, N., Ronsse, F., Prins, W., Carleer, R., Heeres, H.J., 2020. Experimental studies on a two-step fast pyrolysis-catalytic hydrotreatment process for hydrocarbons from microalgae (Nannochloropsis gaditana and Scenedesmus almeriensis). Fuel Processing Technology 206, 106466.


Two microalgae species (marine Nannochloropsis gaditana, and freshwater Scenedesmus almeriensis) were subjected to pyrolysis followed by a catalytic hydrotreatment of the liquid

products with the objective to obtain liquid products enriched in hydrocarbons. Pre-dried microalgae were pyrolyzed in a mechanically stirred fluidized bed reactor (380 and 480 °C) with fractional condensation. The heavy phase pyrolysis oils were hydrotreated (350 °C and 15 MPa of H2 pressure for 4 h) using a NiMo on alumina catalyst. The pyrolysis liquids after pyrolysis and those after catalytic hydrotreatment were analyzed in detail using GC–MS, GC × GC–MS, and 2D HSQC NMR. The liquid products are enriched in aromatics and aliphatic hydrocarbons and, as such have a considerably lower oxygen content (1.6–4.2% w/w) compared to the microalgae feeds (25–30% w/w). The overall carbon yield for the liquid products was between 15.6 and 19.1% w/w based on the initial carbon content of the algae feedstock.


https://doi.org/10.1038/s41396-020-0624-4

Sediment-hosted CO2-rich aquifers deep below the Colorado Plateau (USA) contain a remarkable diversity of uncultivated microorganisms, including Candidate Phyla Radiation (CPR) bacteria that are putative symbionts unable to synthesize membrane lipids. The origin of organic carbon in these ecosystems is unknown and the source of CPR membrane lipids remains elusive. We collected cells from deep groundwater brought to the surface by eruptions of Crystal Geyser, sequenced the community, and analyzed the whole community lipidome over time. Characteristic stable carbon isotopic compositions of microbial lipids suggest that bacterial and archaeal CO2 fixation ongoing in the deep subsurface provides organic carbon for the complex communities that reside there. Coupled lipidomic-metagenomic analysis indicates that CPR bacteria lack complete lipid biosynthesis pathways but still possess regular lipid membranes. These lipids may therefore originate from other community members, which also adapt to high in situ pressure by increasing fatty acid unsaturation. An unusually high abundance of lysolipids attributed to CPR bacteria may represent an adaptation to membrane curvature stress induced by their small cell sizes. Our findings provide new insights into the carbon cycle in the deep subsurface and suggest the redistribution of lipids into putative symbionts within this community.

Psarras, P., He, J., Pilorgé, H., McQueen, N., Jensen-Fellows, A., Kian, K., Wilcox, J., 2020. Cost analysis of carbon capture and sequestration from U.S. natural gas-fired power plants. Environmental Science & Technology 54, 6272-6280.


Despite increasing efforts to decarbonize the power sector, the utilization of natural gas-fired power plants is anticipated to continue. This study models existing solvent-based carbon capture technologies on natural gas-fired power plants, using site-specific emissions and regionally defined cost parameters to calculate the cost of CO2 avoided for two scenarios: delivery to and injection within reliable sequestration sites, and delivery and injection for the purpose of CO2-enhanced oil recovery (EOR). Despite the application of credits from the existing federal tax code 45Q, a minimum incentive gap of roughly $38/tCO2 remains for the geologic sequestration of CO2 and $56/tCO2 for CO2-EOR (before consideration of revenue generated from delivered CO2 contracts). At full

escalation of 45Q, delivered CO2 costs from this sector for geologic sequestration could reach as low as $22/tCO2. However, given the capital investment required in the near-term, it would be beneficial if the credit provided the greatest economic benefit early on and decreasing over time as deployment continues to ramp up. Additionally, due to the high qualifying limit of 45Q for the power sector, e.g., 500 ktCO2/yr, the tax credit incentivizes the capture of roughly 397 MtCO2/yr at a 90% capture efficiency or 75% of the emissions in this sector, with missed opportunities equating to roughly 118 MtCO2. Advancing the scale of carbon capture and sequestration (CCS) will require both technological advances in the capture technology, cost reductions through the leveraging of existing infrastructure, and increased policy incentives in terms of cost along with the reduction of qualifying limits.

Pu, Y., Werne, J.P., Meyers, P.A., Zhang, H., 2020. Organic matter geochemical signatures of sediments of Lake Ngoring (Qinghai-Tibetan Plateau): A record of environmental and climatic changes in the source area of the Yellow River for the last 1500 years. Palaeogeography, Palaeoclimatology, Palaeoecology 551, 109729.


The climate history of the source area of the Yellow River (SAYR) is important to understanding the pacing and processes of climate evolution on the northeastern Qinghai-Tibetan Plateau (QTP). To date, results of research in this alpine region are limited. Herein, we provide a first lacustrine record from the largest freshwater lake on the QTP that archives climatic and environmental variations in the SAYR for the last 1500 yr. The bulk organic carbon and nitrogen isotopic compositions (δ13Corg and δ15Ntot) are combined with atomic carbon/nitrogen (C/N) ratios to indicate that the sedimentary organic matter in Lake Ngoring originates from autochthonous algae and that the terrestrial input is minor. Comparison of the record of organic carbon isotope values with published records of ice accumulation rate (IAR) of Dunde and Guliya glaciers from the northern QTP, the total solar irradiance (TSI), δ18O variations in the Greenland ice core and biologically sensitive indicators (C37:4 alkenone, crenarchaeol and bGDGT concentrations) from Lake Qinghai indicate that variations in the δ13Corg values in Lake Ngoring sediments reflect lake level fluctuations that are associated with variations in the amount of precipitation and glacier meltwater on the SAYR. High lake level phases indicated by positive shifts of δ13Corg values correspond to higher values of the North Atlantic Oscillation Index (NAOI) and lower values of the Southern Oscillation Index (SOIpr). This relation suggests that the hydrologic history in the SAYR is linked to changes in the Indian monsoon and the Westerlies and that both air masses delivered more moisture to the SAYR during high TSI stages. In contrast, variations in the δ15Ntot values resemble the multiple paleoclimate proxy records obtained from ice cores, peat sequences, lake sediments, and integrated paleo-records from other QTP sites, suggesting that the δ15Ntot values archived in Lake Ngoring sediments provide a history of past lake-water temperature variations that is consistent with the variation history of the temperature-dependent parameters from regional paleo-climatic studies. Global climatic events including the Dark Ages Cold Period, the Medieval Climate Anomaly, the Little Ice Age and Modern Warming in 20th century could be clearly observed in the δ15Ntot variations. In general, the δ13Corg and δ15Ntot values in Lake Ngoring sediments appear to be useful indicators for paleo-environment and paleo-climate reconstructions in alpine oligotrophic freshwater lakes such as this one.

Puzzarini, C., 2020. Grand challenges in astrochemistry. Frontiers in Astronomy and Space Sciences 7, 19. doi: 10.3389/fspas.2020.00019.

https://www.frontiersin.org/article/10.3389/fspas.2020.00019

Astrochemistry and molecular astrophysics are often used as synonyms to define an interdisciplinary field that involves chemistry and astronomy, (astro)physics, as well as a “flavor” of biology and geology. Even if it is difficult to define an unique goal, it can be surely affirmed that the main aim is to understand the chemical evolution occurring in space: from diatomics to molecules of a certain degree of complexity and beyond. In other words, this research area studies how molecules are formed and destroyed in different astronomical environments as well as how they interact with radiation. To summarize (and, at the same time, simplify), the focus of astrochemistry is the investigation of chemical processes taking place in space, including molecular evolution and complexity. Molecules have been (and still are being) found everywhere in space: in the interstellar medium, in circumstellar shells, in pregalactic gas, in protostellar disks, and in the atmospheres of planets and stars. Molecules are thus ubiquitous and they can be considered unique probes of molecular excitation mechanisms, radiative transfer, and kinematics.

As is well-known, most of the matter-energy content of the Universe is composed of dark energy and dark matter. Indeed, atoms and molecules contribute <5% of the total. Focusing on atomic elements, the contribution of hydrogen and helium amounts to about 98%; therefore, that of heavier elements (such as carbon, nitrogen, and oxygen) is only about 2%. Nevertheless, this small fraction of heavy elements makes possible a great variety of chemical compounds. In the disk of our Galaxy (the Milky Way), about 90% of the atomic/molecular mass is in stars, and the remaining is in the interstellar matter, mainly in the form of clouds. These consist of gas and tiny dust particles and are the components out of which new stars and planets are born.

When do we place the birth of astrochemistry? At the time of the discovery of interstellar gas (Hartmann, 1904) and dust (Trumpler, 1930), it has thought that the extreme conditions (temperatures ranging between 10 and 106 K and densities from 10−4 to 108 particles/cm3) of the interstellar medium (ISM) would only allow the presence of atoms. In the early forties, however, McKellar identified spectral lines attributable to diatomic molecules (McKellar, 1940), undermining the belief in the absence of molecular reactivity in the ISM. It was only in the late sixties, after the birth of radioastronomy, that the first polyatomic molecules were identified. The first molecules discovered were: ammonia (NH3) in 1968 (Cheung et al., 1968); water (H2O) (Cheung et al., 1969) and formaldehyde (H2CO), the first organic molecule (Snyder et al., 1969), in 1969; hydrocyanic acid (HCN) (Snyder and Buhl, 1971), carbon monoxide (CO) (Wilson et al., 1970) and methanol (CH3OH) in 1970 (Wilson et al., 1970); formic acid (HCOOH) (Snyder and Buhl, 1971) and formamide (H2NCHO) (Snyder and Buhl, 1971) in 1971. Since then, more than 200 molecules have been detected in the ISM and circumstellar shells and the rate of discovery continues at rapid pace. Interestingly, the molecules detected by radioastronomy, which range in size from diatomics up to 13 atoms, are overwhelmingly organic in nature. Particularly fascinating are the so-called “complex organic molecules” (COMs) (Herbst and van Dishoeck, 2009), which are defined as molecules containing more than 5 atoms and including at least one carbon atom.

By the late 1960s and the early 1970s, it had become clear that the ISM is host to a rich chemistry, leading to the emergence of a new branch of science: Astrochemistry. Over the years, the discovery of new molecules has led to questions about how these molecules could be formed in such hostile environments and how far chemical complexity can go. In parallel, further questions arose: How are molecules incorporated into stars and planets? Is the chemistry occurring in the ISM related to the origin of life on Earth? All these questions and the related need to deepen our knowledge represent the current frontiers in astrochemistry.

The considerations above lead to the definition of two grand challenges. (1) The census of the interstellar molecules and beyond, where “beyond” means the search for molecules in (exo)planets and other astronomical objects (e.g., comets). (2) The mechanisms of formation of molecules and the chemical evolution of astronomical objects. Together with these two grand challenges, we can envisage a third one: (3) the origin of life. Indeed, understanding the chemical evolution can help to gain insight into the emergence of life on Earth. The list above is not exhaustive but, rather, a selection of major themes that intrinsically contain (or are related to) further challenges. In this respect, a comprehensive overview is presented in van Dishoeck (2017).

Astrochemistry and molecular astrophysics are often used as synonyms to define an interdisciplinary field that involves chemistry and astronomy, (astro)physics, as well as a “flavor” of biology and geology. Even if it is difficult to define an unique goal, it can be surely affirmed that the main aim is to understand the chemical evolution occurring in space: from diatomics to molecules of a certain degree of complexity and beyond. In other words, this research area studies how molecules are formed and destroyed in different astronomical environments as well as how they interact with radiation. To summarize (and, at the same time, simplify), the focus of astrochemistry is the investigation of chemical processes taking place in space, including molecular evolution and complexity. Molecules have been (and still are being) found everywhere in space: in the interstellar medium, in circumstellar shells, in pregalactic gas, in protostellar disks, and in the atmospheres of planets and stars. Molecules are thus ubiquitous and they can be considered unique probes of molecular excitation mechanisms, radiative transfer, and kinematics.

As is well-known, most of the matter-energy content of the Universe is composed of dark energy and dark matter. Indeed, atoms and molecules contribute <5% of the total. Focusing on atomic elements, the contribution of hydrogen and helium amounts to about 98%; therefore, that of heavier elements (such as carbon, nitrogen, and oxygen) is only about 2%. Nevertheless, this small fraction of heavy elements makes possible a great variety of chemical compounds. In the disk of our Galaxy (the Milky Way), about 90% of the atomic/molecular mass is in stars, and the remaining is in the interstellar matter, mainly in the form of clouds. These consist of gas and tiny dust particles and are the components out of which new stars and planets are born.

When do we place the birth of astrochemistry? At the time of the discovery of interstellar gas (Hartmann, 1904) and dust (Trumpler, 1930), it has thought that the extreme conditions (temperatures ranging between 10 and 106 K and densities from 10−4 to 108 particles/cm3) of the interstellar medium (ISM) would only allow the presence of atoms. In the early forties, however, McKellar identified spectral lines attributable to diatomic molecules (McKellar, 1940), undermining the belief in the absence of molecular reactivity in the ISM. It was only in the late sixties, after the birth of radioastronomy, that the first polyatomic molecules were identified. The first molecules discovered were: ammonia (NH3) in 1968 (Cheung et al., 1968); water (H2O) (Cheung et al., 1969) and formaldehyde (H2CO), the first organic molecule (Snyder et al., 1969), in 1969; hydrocyanic acid (HCN) (Snyder and Buhl, 1971), carbon monoxide (CO) (Wilson et al., 1970) and methanol (CH3OH) in 1970 (Wilson et al., 1970); formic acid (HCOOH) (Snyder and Buhl, 1971) and formamide (H2NCHO) (Snyder and Buhl, 1971) in 1971. Since then, more than 200 molecules have been detected in the ISM and circumstellar shells and the rate of discovery continues at rapid pace. Interestingly, the molecules detected by radioastronomy, which range in size from diatomics up to 13 atoms, are overwhelmingly organic in nature. Particularly fascinating are the so-called “complex organic molecules” (COMs) (Herbst and van Dishoeck, 2009), which are defined as molecules containing more than 5 atoms and including at least one carbon atom.

By the late 1960s and the early 1970s, it had become clear that the ISM is host to a rich chemistry, leading to the emergence of a new branch of science: Astrochemistry. Over the years, the discovery of new molecules has led to questions about how these molecules could be formed in such hostile environments and how far chemical complexity can go. In parallel, further questions arose: How are molecules incorporated into stars and planets? Is the chemistry occurring in the ISM related to the origin of life on Earth? All these questions and the related need to deepen our knowledge represent the current frontiers in astrochemistry.

The considerations above lead to the definition of two grand challenges. (1) The census of the interstellar molecules and beyond, where “beyond” means the search for molecules in (exo)planets and other astronomical objects (e.g., comets). (2) The mechanisms of formation of molecules and the chemical evolution of astronomical objects. Together with these two grand challenges, we can envisage a third one: (3) the origin of life. Indeed, understanding the chemical evolution can help to gain insight into the emergence of life on Earth. The list above is not exhaustive but, rather, a selection of major themes that intrinsically contain (or are related to) further challenges. In this respect, a comprehensive overview is presented in van Dishoeck (2017).

Despite the more than 200 molecules that have been discovered in the ISM and circumstellar shells, a significant number of features in radioastronomical spectra are still unidentified. This means that we are far from a complete census of the interstellar molecules. How many molecules have escaped our knowledge? And what about chemical complexity? Among the molecules discovered in space, those of prebiotic character are of particular relevance. In the last two decades, a great effort has been put in order to demonstrate the presence of biological building-block molecules in the ISM, because they can provide important information on the Galactic chemical evolution. To give an example, glycine (NH2CH2COOH), the simplest amino acid, has been intensively searched for in the ISM (see Kuan et al., 2003 and references therein). While it has been found (together with many other amino acids and nucleic bases) in some meteorites fallen on Earth (e.g., Murchison meteorite; Kvenvolden et al., 1970) and in the coma of comets (e.g., the 67P/Churyumov-Gerasimenko comet; Hadraoui et al., 2019), efforts to detect it in the ISM have so far failed. However, this has largely been interpreted as meaning that glycine is indeed present in the ISM, but its rotational transitions are just too weak for identification in the confusion limit of astronomical surveys. Can we find indirect ways to confirm its presence? To answer this question, a deep knowledge of chemical reactivity in space might help.

A class of compounds that deserve a special mention is that of polycyclic aromatic hydrocarbons (PAHs), a broad class of aromatic hydrocarbons made up of fused benzene rings. They have been discovered in the most disparate astronomical environments, including, e.g., interstellar dust grains, icy moons, comets and carbonaceous meteorites. Within the so-called “PAH world hypothesis,” PAHs have also been assumed to be involved in the abiogenic synthesis of biological molecules. Although this hypothesis has been largely criticized, PAHs clearly play a role in the chemical evolution of the universe (d'Ischia et al., 2019). However, we are far from a complete understanding, which presents a multifaceted challenge for the astrochemical community.

2. Grand Challenge 2: Chemical Reactivity

As already mentioned, understanding the chemical processes in space is one of the main aims of astrochemistry. Molecular complexity and the formation of a star proceed hand in hand. Concerning the latter, the evolution can be summarized as follows: the primordial cloud leads to a protostellar

envelope, which evolves into a protoplanetary disk and then a planetary system. This star-formation process is paralleled by an increasing complexity in the chemical composition of the gas.

In the early 1970s, gas-phase ion-molecule reactions were employed to (successfully) explain the molecular abundances observed in interstellar clouds. Later on, it was recognized the importance, even in low-temperature regimes, of gas-phase neutral-neutral reactions. However, the advance of observational capabilities has led to the detection of molecules in regions where gas-phase reactions could not contribute significantly to chemical reactivity. This marked the beginning of grain-surface chemistry, i.e., the modeling of chemical reactions occurring on dust grains. However, there is still much to be understood about the formation of molecules and, often, the proposed reaction mechanisms are controversial and inconclusive (Garrod et al., 2008; Herbst and van Dishoeck, 2009; Codella et al., 2017). Both theoretical (e.g., Fernández-Ramos et al., 2006; Puzzarini and Barone, 2020) and experimental (e.g., Abeysekera et al., 2015; Parker and Kaiser, 2017) efforts, and possibly their synergic interplay (Balucani et al., 2010), are thus required.

The formation routes of each individual molecular species can be thoroughly investigated. However, it is necessary to treat a large number of chemical reactions simultaneously in order to model the chemical evolution of a given astronomical environment. For setting up the complex network of elementary reactions taking place, e.g., in interstellar clouds or planetary atmospheres, a large number of physico-chemical parameters is also required. Then, kinetic models including thousands of reactions that involve hundreds of species are needed to simulate the chemical evolution over time. This has led to the growth of different astrochemical databases [such as KIDA (Wakelam et al., 2015)] to collect the kinetic parameters required for the relevant reactions. However, the data gathered in these catalogs are incomplete, and sometimes the assumptions included in the models are questionable. We are in the presence of a gigantic puzzle with a huge number of pieces that are still missing.

3. Grand Challenge 3: The Origin of Life

Shedding light on the chemistry occurring in space, i.e., understanding how molecules are formed and evolve, might help to set the stage for understanding the emergence of life on Earth and elsewhere. This aspect of Astrochemistry has attracted a lot of interest in all scientific community, but knowledge is still at a rather primitive stage. Two theories have been suggested so far on the emergence of life on our planet (Chyba and Sagan, 1992), exogenous delivery and endogenous synthesis, and we are far from stating with confidence if one or both of them are correct. Regardless of whether they were delivered to Earth from space or synthetized from simpler molecules, prebiotic species then evolved toward biological complexity, with astrochemistry then moving toward astrobiology. Then, it becomes impossible to place a dividing line between astrochemistry and astrobiology, with astrochemical and astrobiology challenges merging together.

References

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Qiao, J., Littke, R., Zieger, L., Jiang, Z., Fink, R., 2020. Controls on gas storage characteristics of Upper Paleozoic shales from the southeastern Ordos Basin. Marine and Petroleum Geology 117, 104377.


Potential shale gas resources in China are not only of marine but also of marine-terrigenous transitional and continental origins. To analyze the controls on gas storage capacity of shales from the Carboniferous Benxi and Permian Shanxi formations, high-pressure/temperature methane sorption isotherms (up to 25 MPa and 120 °C) and porosity have been measured on 12 samples from the Yishan slope. Total organic carbon (TOC) content of Shanxi and Benxi shales are low to moderate from 0.1% to < 2.3%. All samples have reached the over-mature stage as indicated by vitrinite reflectance values between 2.35% and 2.97% and show lithologic variation where clays are the major minerals (0%–80%) followed by quartz (0%–43%) in most samples. The largest fraction of gas (>80%) is stored on clay minerals (illite/smectite mixed layer and kaolinite) controlling both sorption capacity and porosity. TOC content, due to its low values, is of minor importance. Benxi and Shanxi shales possess comparatively low gas storage capacities compared to producing marine shale gas systems. Combined with the large amount of clay minerals that make hydraulic fracturing more difficult they are regarded unfavourable for shale gas exploitation. Although a substantial amount of gas can be stored sorbed in excess of the free gas in gas shales, methane sorption has a negligible effect on gas production at pressures above 10 MPa. This has major implications for deep reservoirs where pore pressures in the matrix may not be reduced sufficiently before production ceases.



Water-soluble organic aerosol (WSOA) constitutes a large fraction of OA and plays an important role in formation of secondary OA (SOA). Here we characterized the sources and molecular composition of WSOA in summer in Beijing using high-resolution aerosol mass spectrometer and orbitrap mass spectrometer equipped with electrospray ionization. Our results showed that WSOA was the major fraction of OA on average accounting for 69% in summer, which is much higher than that (47%) in winter. However, the oxidation degree of WSOA was comparable between summer and winter (O/C = 0.62 vs. 0.63). Positive matrix factorization analysis showed that SOA contributed dominantly to WSOA (72%) indicating that WSOA was mainly from secondary formation. The two water-soluble SOA factors that are associated with regional processing (OOA-1) and photochemical production (OOA-2), respectively, showed very different behaviors throughout the study. OOA-2 showed much

enhanced contribution during polluted periods with low relative humidity (RH), while OOA-1 played a more important role during high RH periods. Molecular composition analysis of WSOA revealed a high diversity of CHO and CHOS in WSOA in summer. Particularly, the relative intensity fraction of CHOS- compounds was increased by 42% from clean to polluted days which was associated with large increases (20%) in organosulfates (OSs) with lower O*/C (0.1–0.4), and OOA-1. These results suggest the formation of more unsaturated OSs in OOA-1 during polluted days in summer. Comparatively, the biogenic-derived OSs remained relatively stable (24–31%) for the entire study highlighting the ubiquitous importance of biogenic SOA in summer.

Qu, Y., Shan, X., Du, T., Du, X., Zhao, R., 2020. Molecular organic geochemical characteristics and coal gas potential evaluation of Mesozoic coal seams in the western Great Khingan Mountains. Acta Geologica Sinica - English Edition 94, 409-417.

https://doi.org/10.1111/1755-6724.14297

Coal bearing strata are widespread in the western Great Khingan Mountains. Abundant coal ‐resources have been found in the Jurassic Alatanheli Groups, the Cretaceous Bayanhua Groups, the Damoguaihe Formation and the Yimin Formation. The organic geochemical characteristics were analyzed in combination with hydrocarbon source rock evaluation and molecular organic geochemistry experiments, and the coal gas potential of coal seams was evaluated. The source rock evaluation results indicated that the Mesozoic coal samples have the characteristics of high organic matter abundance (TOC>30%), low maturity (Ro values of approximately 0.6%), and type III composition. The hydrocarbon generation potentials of the Alatanheli Groups and Bayanhua Groups are high, while the generation potentials of the Damoguaihe Formation and the Yimin Formation are low. The results of geochemistry show that the depositional environment of the coal seam was a lacustrine, oxidizing environment with a low salinity, and the source of the organic matter was mainly higher plants. Affected by weak degradation, the coal seams mainly formed low maturity gas‐ of thermal catalytic origin. The Cretaceous coal seams contain a large amount of phytoplankton groups deposited in a low stability environment affected by a transgression event, and the potential‐ range varied widely. For the Jurassic coal seams, the depositional environment was more stable, and the coal seams feature a higher coal forming gas potential.‐


https://doi.org/10.1007/s00792-020-01165-1

Archaeal lipids are constituted of two isoprenoid chains connected via ether bonds to glycerol in the sn-2, 3 position. Due to these unique properties archaeal lipids are significantly more stable against high temperature, low pH, oxidation and enzymatic degradation than conventional lipids. Additionally, in members of the phylum Crenarchaeota condensation of two (monopolar) archaeal diether lipids to a single (bipolar) tetraether lipid as well as formation of cyclopentane rings in the isoprenoid core strongly reduce permeability of the crenarchaeal membranes. In this work we show that the Crenarchaeum Sulfolobus acidocaldarius changes its lipid composition as reaction to a shift in growth rate caused by nutrient limitation. We thereby identified a novel influencing factor for the lipid composition of S. acidocaldarius and were able to determine the effect of this factor on the lipid composition by using MALDI-MS for the semi-quantification of an archaeal lipidome: a shift in

the specific growth rate during a controlled continuous cultivation of S. acidocaldarius from 0.011 to 0.035 h−1 led to a change in the ratio of diether to tetraether lipids from 1:3 to 1:5 and a decrease of the average number of cyclopentane rings from 5.1 to 4.6.

Ramírez-Vázquez, L., Negrón-Mendoza, A., 2020. Stability of α-ketoglutaric acid simulating an impact-generated hydrothermal system: implications for prebiotic chemistry studies. International Journal of Astrobiology 19, 253-259.

https://doi.org/10.1017/S1473550419000302

Life originated on Earth possibly as a physicochemical process; thus, geological environments and their hypothetical characteristics on early Earth are essential for chemical evolution studies. Also, it is necessary to consider the energy sources that were available in the past and the components that could have contributed to promote chemical reactions. It has been proposed that the components could have been mineral surfaces. The aim of this work is to determine the possible role of mineral surfaces on chemical evolution, and to study of the stability of relevant molecules for metabolism, such as α-ketoglutaric acid (α-keto acid, Krebs cycle participant), using ionizing radiation and thermal energy as energy sources and mineral surfaces to promote chemical reactions. Preliminary results show α-ketoglutaric acid can be relatively stable at the simulated conditions of an impact-generated hydrothermal system; thus, those systems might have been plausible environments for chemical evolution on Earth.

Ramirez, R.M., 2020. A complex life habitable zone based on lipid solubility theory. Scientific Reports 10, 7432.

https://doi.org/10.1038/s41598-020-64436-z

To find potentially habitable exoplanets, space missions employ the habitable zone (HZ), which is the region around a star (or multiple stars) where standing bodies of water could exist on the surface of a rocky planet. Follow-up atmospheric characterization could yield biosignatures signifying life. Although most iterations of the HZ are agnostic regarding the nature of such life, a recent study argues that a complex life HZ would be considerably smaller than that used in classical definitions. Here, I use an advanced energy balance model to show that such an HZ would be considerably wider than originally predicted given revised CO2 limits and (for the first time) N2 respiration limits for complex life. The width of this complex life HZ (CLHZ) increases by ~35% from ~0.95–1.2 AU to 0.95–1.31 AU in our solar system. Similar extensions are shown for stars with stellar effective temperatures between 2,600–9,000 K. I define this CLHZ using lipid solubility theory, diving data, and results from animal laboratory experiments. I also discuss implications for biosignatures and technosignatures. Finally, I discuss the applicability of the CLHZ and other HZ variants to the search for both simple and complex life.

Ramos-Pallares, F., Yarranton, H.W., 2020. Extending the modified regular solution model to predict component partitioning to the asphaltene-rich phase. Energy & Fuels 34, 5213-5230.


The modified regular solution (MRS) model is an activity coefficient approach previously developed to predict the onset and amount of asphaltene precipitation from n-paraffin-diluted crude oils. The activity coefficients in this model are determined from an enthalpic contribution based on the regular solution theory and a Flory–Huggins (configurational) entropic contribution. The inputs are the molar volume and solubility parameter of the crude oil pseudo-components, which are defined on the basis of the saturate, aromatic, resin, and asphaltene (SARA) fractions; however, only asphaltenes and resins are free to partition between the two phases. Hence, the model cannot predict the amount and composition of the heavy asphaltene-rich phase. In this study, the MRS model was updated to account for the partitioning of all components based on phase equilibrium data from a Western Canada bitumen mixed with n-pentane and n-heptane at ambient conditions. To match the measured phase compositions, the entropic contribution in the solvent-rich phase was set to the Flory–Huggins term and the contribution from the asphaltene-rich phase was set to zero. An approach to predict the solubility parameters and density of the pseudo-components at other temperatures and pressures was also proposed. The model was tested on a data set containing phase mass and phase compositions of a Western Canada bitumen mixed with n-heptane, n-pentane, n-butane, and propane at temperatures from 20 to 250 °C and pressures up to 13 MPa. The average absolute deviations in the phase mass and compositions were 7 and 12 wt %, respectively. The maximum deviations were found for the asphaltene-rich phase compositions. The model was also tested on a data set of asphaltene yields from oils from different disparate geographical locations at temperatures from 0 to 50 °C at 0.1 MPa. The average absolute deviation was 1 wt %.

Rampe, E.B., Blake, D.F., Bristow, T.F., Ming, D.W., Vaniman, D.T., Morris, R.V., Achilles, C.N., Chipera, S.J., Morrison, S.M., Tu, V.M., Yen, A.S., Castle, N., Downs, G.W., Downs, R.T., Grotzinger, J.P., Hazen, R.M., Treiman, A.H., Peretyazhko, T.S., Des Marais, D.J., Walroth, R.C., Craig, P.I., Crisp, J.A., Lafuente, B., Morookian, J.M., Sarrazin, P.C., Thorpe, M.T., Bridges, J.C., Edgar, L.A., Fedo, C.M., Freissinet, C., Gellert, R., Mahaffy, P.R., Newsom, H.E., Johnson, J.R., Kah, L.C., Siebach, K.L., Schieber, J., Sun, V.Z., Vasavada, A.R., Wellington, D., Wiens, R.C., 2020. Mineralogy and geochemistry of sedimentary rocks and eolian sediments in Gale crater, Mars: A review after six Earth years of exploration with Curiosity. Geochemistry 80, 125605.


The Mars Science Laboratory Curiosity rover arrived at Mars in August 2012 with a primary goal of characterizing the habitability of ancient and modern environments. Curiosity was sent to Gale crater to study a sequence of ∼3.5 Ga old sedimentary rocks that, based on orbital visible and near- to short-wave infrared reflectance spectra, contain secondary minerals that suggest deposition and/or alteration in liquid water. The sedimentary sequence in the lower slopes of Mount Sharp in Gale crater preserves a dramatic shift on early Mars from a relatively warm and wet climate to a cold and dry climate, based on a transition from smectite-bearing strata to sulfate-bearing strata. The rover is equipped with instruments to examine the sedimentology and identify compositional changes in the stratigraphy. The Chemistry and Mineralogy (CheMin) instrument is one of two internal laboratories on Curiosity and includes a transmission X-ray diffractometer (XRD) and X-ray fluorescence (XRF) spectrometer. CheMin measures loose sediment samples scooped from the surface and drilled rock powders, and the XRD provides quantitative mineralogy to a detection limit of ∼1 wt.% for crystalline phases. Curiosity has traversed >20 km since landing and has primarily been exploring an ancient lake environment fed by streams and groundwater. Of the 19 drilled rock

samples analyzed by CheMin as of sol 2300 (January 2019), 15 are from fluvio-lacustrine deposits that comprise the Bradbury and Murray formations. Most of these samples were drilled from units that did not have a clear mineralogical signature from orbit. Results from CheMin demonstrate an astounding diversity in the mineralogy of these rocks that signifies geochemical variations in source rocks, transportation mechanisms, and depositional and diagenetic fluids. Most detrital igneous minerals are basaltic, but the discovery in a few samples of abundant silicate minerals that usually crystallize from evolved magmas on Earth remains enigmatic. Trioctahedral smectite and magnetite at the base of the section may have formed from low-salinity pore waters with a circumneutral pH in lake sediments. A transition to dioctahedral smectite, hematite, and Ca-sulfate going up section suggests a change to more saline and oxidative aqueous conditions in the lake waters themselves and/or in diagenetic fluids. Perhaps one of the biggest mysteries revealed by CheMin is the high abundance of X-ray amorphous materials (15–73 wt.%) in all samples drilled or scooped to date. CheMin has analyzed three modern eolian sands, which have helped constrain sediment transport and mineral segregation across the active Bagnold Dune Field. Ancient eolian sandstones drilled from the Stimson formation differ from modern eolian sands in that they contain abundant magnetite but no olivine, suggesting that diagenetic processes led to the alteration of olivine to release Fe(II) and precipitate magnetite. Fracture-associated halos in the Stimson and the Murray formations are evidence for complex aqueous processes long after the streams and lakes vanished from Gale crater. The sedimentology and composition of the rocks analyzed by Curiosity demonstrate that habitable environments persisted intermittently on the surface or in the subsurface of Gale crater for perhaps more than a billion years.

Ran, Y., Zhou, X., 2020. Geochemical characteristics and genesis of tight gas in Shahezi Formation, Xujiaweizi Fault Depression, North Songliao Basin, China. Journal of Natural Gas Geoscience 5, 69-79.


Along with exploration of unconventional natural gas in North Songliao Basin, the tight gas in Shahezi Formation has become a new hotspot, followed by continual breakthroughs in terms of gas exploration. In order to understand the generation and distribution of tight gas in deep-layer of North Songliao Basin, this study focuses on the geochemical characteristics and accumulation period of tight gas, based on analysis of geochemical data such as gas compositions, carbon isotopes and homogenization temperature. According to the result of these analysis, gas in Shahezi Formation is dominated by methane with a light portion of heavy hydrocarbons and generally non-hydrocarbon, such as carbon dioxide and nitrogen. There is a widely distribution of δ13C1 which is ranges from −33.2‰ to −27.8‰, while δ13C2 is higher and have a relatively intensive distribution from −29.2‰ to −22.4‰. Carbon isotopic distribution of tight gas is characterised by a normal pattern, some partial reversal of carbon are observed. The identification of tight gas shows that the main type of tight gas in Shaheizi Formation are coal-formed gas and there are two accumulation periods including Nengjiang period and Qingshankou period. The mix of high maturity coal-formed gas in Nengjiang period and relatively low maturity coal-formed gas in Qingshankou Period is the major cause of carbon isotope reversal. In addition, it is notable that carbon dioxide in study area are inorganic origins, resulted from magma activity in Yingcheng Period.

Rao, A., Kumar, S., Annink, C., Le-Anh, D., Ayirala, S.C., Alotaibi, M.B., Siretanu, I., Duits, M.H.G., Yousef, A.A., Mugele, F., 2020. Mineral interfaces and oil recovery: A microscopic view on surface

reconstruction, organic modification, and wettability alteration of carbonates. Energy & Fuels 34, 5611-5622.


While it is generally known that aging protocols have an important impact on the interaction between crude oil (CRO), brines, and mineral surfaces, the microscopic consequences of the various steps of aging have hardly been described. In this study, we characterize the properties of fluids and carbonate mineral surfaces throughout a series of equilibration steps at 95 °C and correlate these microscopic observations with macroscopic contact angle measurements. Chemical equilibration of CRO (eqCRO) and FW (eqFW) leads to transfer of organic molecules from the former to the latter, causing also a pH change in the eqFW. Confocal Raman microscopy, atomic force microscopy, and infrared spectroscopy are used to reveal how consecutive aging of calcite in eqFW and eqCRO induces: first, in eqFW, considerable surface reconstruction and precipitation of mineral particles with colocalized organic species, and second, upon exposure to eqCRO, the formation of a second adlayer primarily composed of polyaromatic hydrocarbon-rich particles. Our results show how these interconnected microscopic chemical and topographical surface modifications give rise to more “oil wetting” contact angles after the two-step aging procedure.



The environment of a high altitude brackish water lake presents an unprecedented reservoir for the microbial community with adaptability towards surviving stressful conditions. Pangong lake is a high altitude brackish water lake of the Himalayas situated in the eastern part of Ladakh (Indian Tibet), at the height of 4250 m above the sea level. Shotgun metagenomics sequencing of Pangong Lake sediments was performed to examine the taxonomic diversity and functional adaptations of the resident psychrophilic and psychrotolerant microbial communities of the lake (September; a temperature of ±10 °C). Proteobacteria was the most prominent phylum, and Methylophaga, Halomonas, and Marinobacter were mainly abundant at the genus level. Enzyme pathways responsible for methane metabolism, nitrogen metabolism, sulfur reduction, benzoate, and xylene degradation appeared to be complete in the metagenomic dataset. Stress response genes responsible for adaption to pH, cold, salt tolerance, osmotic stress, and oxidative stress were also found in abundance in the metagenome. We compared the Pangong lake metagenome sample to sediments and water samples from three different aquatic habitats, namely saline lake, freshwater lakes and marine ecosystem using MG-RAST server against RefSeq and Subsystem databases. The Pangong lake microbial community contains six unique genera. Regression analysis using metagenome samples suggested that Pangong lake was most closely related to the Trophic South Pacific Ocean (R2 = 0.971) and Socompa lake ecosystem (R2 = 0.991) at phylum and functional level II, respectively. Our study signifies that the functional metabolic potentiality of Pangong lake is strongly influenced by the taxonomic structure and environmental conditions. We are reporting the metagenome of the sediment sample of the Pangong lake, which unveils the microbial diversity and their functional potential.

Read, D.H., Sillerud, C.H., Whiting, J.J., Achyuthan, K.E., 2020. Metal-organic framework stationary phases for one- and two-dimensional micro-gas chromatographic separations of light alkanes and polar toxic industrial chemicals. Journal of Chromatographic Science 58, 389-400.

https://doi.org/10.1093/chromsci/bmaa005

Despite promising advances with metal-organic frameworks (MOFs) as stationary phases for chromatography, the application of MOFs for one- and two-dimensional micro-gas chromatography (μGC and μGC × μGC) applications has yet to be shown. We demonstrate for the first time, μGC columns coated with two different MOFs, HKUST-1 and ZIF-8, for the rapid separation of high volatility light alkane hydrocarbons (natural gas) and determined the partition coefficients for toxic industrial chemicals, using μGC and μGC × μGC systems. Complete separation of natural gas components, methane through pentane, was completed within 1 min, with sufficient resolution to discriminate n-butane from i-butane. Layer-by-layer controlled deposition cycles of the MOFs were accomplished to establish the optimal film thickness, which was validated using GC (sorption thermodynamics), quartz-crystal microbalance gravimetric analysis and scanning electron microscopy. Complete surface coverage was not observed until after ~17 deposition cycles. Propane retention factors with HKUST-1-coated μGC and a state-of-the-art polar, porous-layer open-tubular (PLOT) stationary phase were approximately the same at ~7.5. However, with polar methanol, retention factors with these two stationary phases were 748 and 59, respectively, yielding methanol-to-propane selectivity factors of ~100 and ~8, respectively, a 13-fold increase in polarity with HKUST-1. These studies advance the applications of MOFs as μGC stationary phase.

Redd, N.T., 2020. News feature: Diamonds in the rubble. Proceedings of the National Academy of Sciences 117, 11187-11190.

http://www.pnas.org/content/early/2020/05/05/2005076117.abstract

Two ancient asteroids with distinctive diamond-like shapes are revealing clues not only about their own formation, but that of the solar system as well.For the past three years, two spacecraft have been studying a pair of the most primitive solar system objects ever explored. The asteroids, Ryugu and Bennu, born of violent collisions in the asteroid belt, are some of the smallest objects ever visited by spacecraft. Ryugu is just over a kilometer across, and Bennu is about half as wide.

But these small bodies are promising a huge bounty of data to astronomers over the next few years. Although the findings could revolutionize our understanding of the history, formation, and composition of asteroids, they may also tell us a little about the solar system during its infancy.

That’s because these carbon-rich (1) asteroids, with their coal-dark surfaces, are also among the darkest bodies known in the solar system. Although that can make it difficult to observe them from Earth, studying them could tell us about the building blocks of life that such asteroids may have delivered to Earth early in the history of the solar system.

Long Strange Trips

Before researchers could hope to study these asteroids, they first had to reach them. This, by itself, was an enormous challenge. Only a handful of spacecraft have visited asteroids, and fewer still have managed to orbit one of these tiny, irregularly shaped objects.

Two ancient asteroids with distinctive diamond-like shapes are revealing clues not only about their own formation, but that of the solar system as well.

For the past three years, two spacecraft have been studying a pair of the most primitive solar system objects ever explored. The asteroids, Ryugu and Bennu, born of violent collisions in the asteroid belt, are some of the smallest objects ever visited by spacecraft. Ryugu is just over a kilometer across, and Bennu is about half as wide.

Solar System Historians

About 4.5 billion years ago, a giant disk of rocks, gas, and dust coalesced to form Earth and other planets. Asteroids are some of the leftover pieces from this process and can provide insights into how our solar system came to be. Most asteroids are found in the asteroid belt between Mars and Jupiter, a vast field that looks nothing like Hollywood’s portrayal of it. The asteroids are usually widely separated, and collisions are few and far between. Asteroids have changed far less than most other solar system bodies like Earth and the Moon, making these small rocky bodies a valuable window into the early solar system.

Despite this potential window into the past, researchers know little about asteroids. The first one wasn't discovered until 1801. It wasn’t until 1959 that researchers realized that many meteorites came from asteroids. More than 22,000 meteorites have been identified on Earth, including some originating from Mars and the Moon. But researchers only began classifying asteroids by type in the 1970s and 80s, and definitively identifying a specific parent body has been a challenge. Then, in 1991, a spacecraft made the first flyby of an asteroid; since then, missions have buzzed more than a dozen of them. And so far, only the first Hayabusa mission has ever grabbed a piece of an asteroid (25143 Itokawa in 2005) and brought it back to Earth.

Like Ryugu and Bennu, Itokawa is a so-called rubble pile asteroid (2), the remains of a larger object that shattered in a collision. But whereas Ryugu and Bennu are rich in carbon, Itokawa is a stony asteroid, the source of the most common types of meteorites. The potato-shaped Itokawa has few craters or boulders on its surface. This finding led many to suspect that Hayabusa2 and OSIRIS-REx would encounter similar surfaces and have little trouble selecting samples from their targets. That turned out not to be the case. Both Ryugu (3) and Bennu (4) were covered with boulders that make collecting samples a challenge. And their boulder-strewn surfaces weren’t the only surprises.

Diamond Delights

Radar and Hubble Space Telescope observations of Bennu had revealed its distinctive diamond shape well before OSIRIS-REx arrived. But Ryugu is farther away and its shape had remained indistinct. Studies from Earth suggested a roughly spherical object, or one with a dumpling-like appearance. Only when Hayabusa2 drew close to the asteroid did it become clear that Ryugu too is diamond shaped (5). “Until we got there, to the proximity of the asteroid, I don’t think we could really finally answer,” says Seiji Sugita, a professor at the University of Tokyo, Japan, and member of the Haybausa2 team.

Both Ryugu and Bennu are small parts of larger asteroids, born when a massive object smashed into their parent bodies and blew off a cloud of debris. Rubble piles like Ryugu and Bennu (6) are made up of a variety of loosely bound rocks from both the surface and interior of the larger source asteroid. “We’re getting a glimpse at the previous body that was catastrophically disrupted and then reaccumulated into this grab bag of rocks from that parent body,” says Erica Jawin, a researcher at

the Smithsonian Museum of Natural History, in Washington, DC, and part of the OSIRIS-REx team. Gravity pulled debris together, and like an ice skater pulling his arms in, the asteroid began to spin faster and faster, and the rocks preferentially accumulated near the equator of the asteroid, creating a bulge that gives the asteroids their diamond top shape.

The ridges running around the equators of both asteroids revealed a further surprise. Ryugu’s ridge is prominent, whereas Bennu’s is muted. Several large impact craters scar the ridges on both asteroids, features which Kevin Walsh, a planetary modeler at the Southwest Research Institute in Boulder, CO, and an OSIRIS-REx team leader, calls “shocking”: The craters are evidence that the equators on these asteroids are older than expected.

The finding casts doubt on our understanding of how and when these asteroids formed. Planetary researchers thought that the asteroids probably didn’t achieve their diamond shape until after they had migrated, about a billion years after their birth, to the quieter, less violent neighborhood nearer to Earth. If so, impact craters on the equatorial ridges should be small and less plentiful than if the craters had formed back in the asteroid belt.

The thinking now is that the impacts that created the massive craters most likely came early in the life of Ryugu and Bennu, when they were still in the asteroid belt, but after the ridges were formed. “These asteroids might have gotten their shape when they were born, or at least a very long time ago,” he says. That’s something researchers didn’t expect.

A Field of Boulders

Both Ryugu and Bennu had another surprise in store for mission researchers. Instead of surfaces that were relatively smooth like Itokawa, both asteroids featured fields of boulders. According to Hayabusa2 team member Sho Sasaki, Ryugu boasts more than 4,400 boulders larger than 5 meters in diameter. Bennu has more than 3,100 boulders that are at least a meter across, Jawin says, with large boulders spread across the surface in similar proportions to Ryugu.

Extremely large boulders are rare; Bennu has two giants, and Ryugu has only one. Bennu's biggest boulders are 58 meters and 95 meters across. The smaller of the two is bright, composed of relatively fine-grained material. Observations revealed a meter-size chunk of embedded rock, or clast, but overall the rock seems to have very little surface variation. The boulder protrudes about three meters above the surface, Jawin says.

Bennu’s larger rock is a dark, partially buried object with several clasts embedded in its surface. The texture appears hummocky, a geological term that describes lines in the rock similar to small knolls. When the sun shines directly overhead, the stone giant becomes the hottest part of the asteroid, about 20 degrees warmer than the rest of the surface, Jawin says, and spectral studies of the rock suggest that it may be made up of magnetite.

Ryugu has its own distinctive 160-meter rock, which Hayabusa2 researchers named Otohime, for a princess from a Japanese folktale. Otohime is a dark rock located near the asteroid’s south pole, with sharp edges and smooth surfaces. Its vertical face is the brightest surface on Ryugu.

“We have two very distinct boulders on Bennu,” says Jawin, and first casual impressions suggest that “one of those looks very similar to the large boulder on Ryugu.”

The trio of large boulders on the two asteroids could provide insights about the bodies that birthed Ryugu and Bennu. All three are too large to have formed through collisions or impacts. Bennu’s two largest rocks may appear different because they are made up of different material, or their differences may arise from weathering processes, with the largest boulder having been exposed to the surface longer. The massive boulders and their smaller siblings could provide a glimpse into the conditions present at the start of the solar system.

Peering Inside

The largest boulders may catch the eye, but the midsized rocks can also provide valuable information. One class of objects, described as having “a crumbly, cauliflower-type appearance,” was visible in the nighttime hops made by Mobile Asteroid Surface Scout (MASCOT), a lander dropped on Ryugu's surface which sent images back to its mother ship for a few short hours. A second type of rock, with smooth, angular features and linear fractures, was only visible during the descent. Together, the two types dominate the surface of Ryugu. Fine rocky material, expected to be found in abundance on the asteroid, was surprisingly absent.

The low-flying spacecraft revealed that roughly 5% of the 500 boulders larger than 12 meters on Ryugu are cracked. Fractured boulders are also “common across the surface of Bennu,” Walsh says. Researchers are still trying to determine what cracked the rocks. Impacts and landslides can cause rocks to split, but the leading theory is that repeated heating and cooling caused by exposure to the sun caused the cracks.

The new observations may be the first direct evidence of such a process on a solar system object other than Earth. “We expect the stresses induced at the very center of the materials are going to want to propagate, creating linear fracturing in boulders,” says researcher and OSIRIS-REx team member Jamie Molaro of the Planetary Science Institute headquartered in Tucson, AZ.

Cracked boulders on Bennu reveal a little more about what’s going on inside. Molaro says that Bennu’s cauliflower-like boulders appear brittle. “They really just look like they are crumbling and falling apart,” she says. Some of the rough surfaces have bright spots that could be the result of material landing on the boulders. Others appear to have inclusions, small bits of material encased by the larger rocks which may help to advance the fragmentation process.

Ryugu’s rocks also hold hidden treasures. MASCOT carried not only a camera but four colored LED lights, allowing it to capture images in the dark. By shining different colors of light on the rocks, the LEDs revealed inclusions of a variety of colors too dim to see in daylight, some of them shining as much as four times brighter than the surrounding material. “We are not sure what these inclusions are,” Hayabusa2 team member Stefanus Schroder said last year at the Lunar and Planetary Sciences Conference in The Woodlands, TX.

Back on Earth, researchers compared the Ryugu rocks to various meteorites, and found that, under similar conditions, those rocks are similar to the Murchison meteorite, which fell to Earth near Murchison, Australia, in 1969. The red and blue inclusions in the meteorite both contain olivine (7) that had been altered by water at some time in the past, Schroder says. Olivine is present in a class of meteorites known as carbonaceous chondrites, and the similar inclusions could suggest a link between those meteorites and asteroids like Ryugu. However, because MASCOT couldn’t make spectral observations that shed light on the asteroid’s mineral composition, the identification of olivine remains tentative.

When Hayabusa2 fired a copper ball at the surface of Ryugu, it uncovered even more information about the asteroid. The layers of material revealed in the subsequent crater strengthened the case for a rubble pile asteroid of different material. Intriguingly, the resulting crater was larger than anticipated, calling into question the scaling laws used to date the asteroid duo (8).

“Perhaps the ridge did form relatively recently, erasing all previous craters and showing only the last 10 million years of cratering on the surface,” says Walsh, who called the new research “a big result, and surprising.”

“We Only Need One”

Although the bounty of boulders may provide significant scientific insights, they have also caused a few problems for the two sample return missions. Hayabusa2 was slated to begin the first of three sample collections in October 2018. However, the boulders caused a delay as researchers rushed to find a safe way to collect fine material that was unexpectedly rare on the surface. Hayabusa2 didn’t gather its first sample until February 2019, nearly 18 months after its arrival. Like its predecessor, the spacecraft fired a small projectile at the asteroid and scooped up material blown out from the surface. Its collection complete, it left Ryugu for Earth in December 2019 with a planned arrival date in December 2020.

Bennu faced similar challenges. OSIRIS-Rex mission planners had expected to find the equivalent of half a football field worth of space to navigate among the boulders. Instead, they found open spaces to be rare, with only a handful of regions between 5 and 20 meters across that were devoid of large, potentially hazardous boulders.

In December 2019, OSIRIS-REx finally announced its landing site, a region named Nightingale near Bennu’s north pole. Nightingale sits in a crater within a crater. “We made our final decision based on which site has the greatest amount of fine-grained material and how easily the spacecraft can access that material while keeping the spacecraft safe,” OSIRIS-REx principle investigator Dante Lauretta, a planetary researcher at the University of Arizona in Tucson, announced at the American Geophysical Union conference in San Diego, CA, in December. The spacecraft began reconnaissance flights over Nightingale and a backup site and has begun rehearsals for its touch-and-go sample collection attempt, which is scheduled for August 2020. Unlike Hayabusa2, OSIRIS-Rex’s sampling arm will reach down to the asteroid’s surface, blow nitrogen gas at it, and collect the dislodged material. Then it will leave Bennu for Earth sometime around March 2021.

Despite the intricacies of the maneuver, OSIRIS-REx researchers remain confident that they will be able to safely collect material from the asteroid for one of the sites they have identified. Jawin knows it will be a major feat, perhaps more challenging than originally thought, but remains hopeful that they’ll retrieve just enough. “We only need one,” she says.

References1. R. Jaumann et al. Images from the surface of asteroid Ryugu show rocks similar to carbonaceous

chondrite meteorites. Science 365, 817–820 (2019).2. K. J. Walsh, Rubble pile asteroids. Annu. Rev. Astron. Astrophys. 56, 593–624 (2018).3. K. Kitazato et al., The surface composition of asteroid 162173 Ryugu from Hayabusa2 near-

infrared spectroscopy. Science 364, 272–275 (2019).4. D. S. Lauretta et al., OSIRIS-REx Team, The unexpected surface of asteroid (101955) Bennu.

Nature 568, 55–60 (2019).

5. S. Watanabe et a., Hayabusa2 arrives at the carbonaceous asteroid 162173 Ryugu-A spinning top-shaped rubble pile. Science 364, 268–272 (2019).

6. D. N. DellaGiustina et al., Properties of rubble-pile asteroid (101955) Bennu from OSIRIS-REx imaging and thermal analysis. Nat. Astron. 3, 341–351 (2019).

7. V. E. Hamilton et al., OSIRIS-REx Team, Evidence for widespread hydrated minerals on asteroid (101955) Bennu. Nat. Astron. 3, 332–340 (2019).

8. M. Arakawa et al., An artificial impact on the asteroid (162173) Ryugu formed a crater in the gravity-dominated regime. Science, 368, 67–71 (2020).

Reinhold, T., Shapiro, A.I., Solanki, S.K., Montet, B.T., Krivova, N.A., Cameron, R.H., Amazo-Gómez, E.M., 2020. The Sun is less active than other solar-like stars. Science 368, 518-521.


Abstract: The magnetic activity of the Sun and other stars causes their brightness to vary. We investigated how typical the Sun’s variability is compared with other solar-like stars, i.e., those with near-solar effective temperatures and rotation periods. By combining 4 years of photometric observations from the Kepler space telescope with astrometric data from the Gaia spacecraft, we were able to measure photometric variabilities of 369 solar-like stars. Most of those with well-determined rotation periods showed higher variability than the Sun and are therefore considerably more active. These stars appear nearly identical to the Sun except for their higher variability. Therefore, we speculate that the Sun could potentially also go through epochs of such high variability.

Editorial summary: Activity levels of Sun-like stars. Magnetic activity on the Sun leads to solar flares, coronal mass ejections, and other space weather that affects Earth. Similar activity on other stars may determine the habitability of any orbiting exoplanets. Reinhold et al. analyzed brightness variations of stars observed with the Kepler and Gaia space telescopes to infer their activity levels (see the Perspective by Santos and Mathur). They found that the Sun was less active than most of the 369 solar-type stars in their sample (those with the most similar physical properties). It remains unclear whether the Sun is permanently less active than other stars of its type or if its activity levels vary over many thousands or millions of years.



Heavy polycyclic aromatic hydrocarbons (HPAHs) are known to cause undesirable effects in petroleum hydrocracking processes by deactivating the catalysts and accumulating in the downstream of reactors. Polycyclic aromatic hydrocarbons with less than seven rings (PAHs) naturally contained in vacuum gas oils (VGOs) act as precursors in the HPAHs formation. However, getting a detailed quantitative characterization of such polycyclic hydrocarbons has never been done until now, because of the high chemical complexity of VGOs. Thus, an off-line, comprehensive, three-dimensional methodology was required to achieve a quantitative analysis: centrifugal partition chromatography (CPC) as the first dimension of separation, supercritical fluid

chromatography (SFC) as the second dimension hyphenated to Fourier transform ion cyclotron resonance mass spectrometry as the third dimension. In this study, we demonstrated that the developed CPC method fractionated samples according to the hydrocarbons’ alkylation degree, whereas our SFC method provided an elution order according to their double bond equivalent. Finally, high-resolution mass spectrometry (HRMS) brought crucial information on the identity of analytes and proved to be essential in the event of unresolved peaks from CPC and SFC chromatograms. To assess the ability of the three-dimensional method for quantification purposes, matrix effects were evaluated by spiking VGO samples with deuterated pyrene. A strong ion suppression phenomenon was highlighted when using only SFC/HRMS, whereas no significant matrix effect was observed with the CPC×SFC/HRMS approach. These experiments revealed the great potential of this innovative methodology to quantify both PAH and HPAH in VGOs for the first time.


https://doi.org/10.1038/s41598-020-65407-0

The prehistory of the Mediterranean region has long been a subject of considerable interest, particularly the links between human groups and regions of origin. We utilize the spatial variation in the δ2H and δ18O values of precipitation (isoscapes) to develop proxies for geographic locations of fauna and humans. Bone collagen hydrogen isotope ratios (δ2H) in cattle (and to a lesser extent, ovicaprids) across the Mediterranean reflect the isotopic differences observed in rainfall (but δ18O values do not). We conclude that δ2H in herbivore bone collagen can be used as a geolocation tracer and for palaeoenvironmental studies such as tracing past isotopic variations in the global hydrological cycle. In contrast, human bone δ2H values are relatively tightly grouped and highly distinct from precipitation δ2H values, likely due to human-specific food practices and environmental modifications. Given the inter-species variability in δ2H, care should be taken in the species selected for study.

Richey, J.D., Montañez, I.P., Goddéris, Y., Looy, C.V., Griffis, N.P., DiMichele, W.A., 2020. Influence of temporally varying weatherability on CO2–climate coupling and ecosystem change in the late Paleozoic. Climate of the Past Discussions 2020, 1-37.


Earth's penultimate icehouse, the Late Paleozoic Ice Age (LPIA), was a time of dynamic glaciation and repeated ecosystem perturbation, under conditions of substantial variability in atmospheric pCO2 and O2. Improved constraints on the evolution of atmospheric pCO2 and O2 : CO2 during the LPIA and its subsequent demise to permanent greenhouse conditions is crucial for better understanding the nature of linkages between atmospheric composition, climate, and ecosystem perturbation during this time. We present a new and age-recalibrated pCO2 reconstruction for a 40-Myr interval (~313 to 273 Ma) of the late Paleozoic that (1) confirms a previously hypothesized strong CO2-glaciation linkage, (2) documents synchroneity between major pCO2 and O2 : CO2 changes and compositional turnovers in terrestrial and marine ecosystems, (3) lends support for a modeled progressive decrease in the CO2 threshold for initiation of continental ice sheets during the LPIA, and (4)

indicates a likely role of CO2 and O2 : CO2 thresholds in floral ecologic turnovers. Modeling of the relative role of CO2 sinks and sources, active during the LPIA and its demise, on steady-state pCO2 using an intermediate complexity climate-C cycle model (GEOCLIM) and comparison to the new multi-proxy CO2 record provides new insight into the relative influences of the uplift of the Central Pangaean Mountains, intensifying aridification, and increasing mafic rock to-granite rock ratio of outcropping rocks on the global efficiency of CO2 consumption and secular change in steady-state pCO2 through the late Paleozoic.

Riekenberg, P.M., van der Meer, M., Schouten, S., 2020. Practical considerations for improved reliability and precision during determination of δ15N values in amino acids using a single combined oxidation–reduction reactor. Rapid Communications in Mass Spectrometry 34, e8797.

https://doi.org/10.1002/rcm.8797

Rationale: There has been increased interest in the measurement of δ15N values in amino acids (AAs) to gain simultaneous insight into both trophic relationships and the composition of biogeochemical sources used by producers at the base of the food web. A new combustion reactor design in gas chromatography/combustion isotope ratio mass spectrometry (GC/C irMS) equipment has brought ‐to light variable outcomes in performance, highlighting the need for better information about best practices for new systems.

Methods: Precision for δ15N values in amino acids using the single combined oxidation–reduction reactor is improved across a sequence of analyses if the reactor is oxidized for a substantial period (2 h) and subsequently maintained throughout the sequence with 12–17 s seed oxidation before each run during GC/C irMS. A five point calibration curve using amino acids with a range of δ‐ ‐ 15N values from −2.4‰ to +61.5‰ was used in combination with a 13–15 amino acid mixture to consistently normalize measurements to internationally calibrated reference materials.

Results: Combining this oxidation method with normalization techniques using both internal and external standards provided a reliable throughput of ~25 samples per week. It allowed for a reproducible level of precision of <±0.5‰, n = 10 within a derivatized standard mixture across each sequence and an average sample precision of ±0.27‰ n = 3, which is lower than the analytical precision typically associated with δ15N values for amino acid analysis (<±1‰).

Conclusions: A few practical considerations regarding oxidation and conditioning of the combustion reactor allow for increased sequence capacity with the single combined oxidation–reduction reactor. These considerations combined with normalization techniques result in a higher throughput and reduced analytical error during the measurement of δ15N values in amino acids.


https://doi.org/10.1038/s41561-020-0556-7

During terrestrial differentiation, the relatively small amount of phosphorus that migrated to the lithosphere was incorporated into igneous rock, predominantly in the form of basic calcium orthophosphate (Ca10(PO4)6(OH,F,Cl)2, apatite). Yet the highly insoluble nature of calcium apatite

presents a significant problem to those contemplating the origin of life given the foundational role of phosphate (PO4

3−) in extant biology and the apparent requirement for PO43− as a catalyst, buffer

and reagent in prebiotic chemistry. Reduced meteorites such as enstatite chondrites are highly enriched in phosphide minerals, and upon reaction with water these minerals can release phosphorus species of various oxidation states. Here, we demonstrate how reduced phosphorus species can be fully oxidized to PO4

3− simply by the action of ultraviolet light on H2S/HS−. We used low-pressure Hg lamps to simulate ultraviolet output from the young Sun and 31P nuclear magnetic resonance spectroscopy to monitor the progress of reactions. Our experimental findings provide a cosmochemically and geochemically plausible means for supply of PO4

3− that was widely available to prebiotic chemistry and nascent life on early Earth and potentially on other planets.

Rizzi, M., Thibault, N., Ullmann, C.V., Ruhl, M., Olsen, T.K., Moreau, J., Clémence, M.-E., Mette, W., Korte, C., 2020. Sedimentology and carbon isotope stratigraphy of the Rhaetian Hochalm section (Late Triassic, Austria). Global and Planetary Change 191, 103210.


The Rhaetian (~201–209 Ma, the latest stage of the Triassic) is an important time-interval for the study of environmental changes preceding the End-Triassic Mass extinction. A detailed sedimentological and chemostratigraphic study was conducted in the lower Kössen Formation at Hochalm (Austria), the type-section of the Hochalm Member (Mb). This section exposes mid-Rhaetian sediments deposited in an intraplatform shallow marine basin on the north-western margin of the Tethys. The study highlights eight apparent shallowing-upward sequences from the middle of Unit 2 to Unit 4 of the Hochalm Mb stacked within the long-term transgression that characterizes the Kössen Formation. Both the bulk carbonate and the bulk organic matter δ13C records indicate the presence of a distinct increase in carbon isotope values in the lower part of the lower Hochalm Mb. This excursion might represent a new chemostratigraphic marker that could be used for refining the Rhaetian stratigraphy and represents another important Late Triassic carbon-cycle perturbation prior to the major disturbance associated with the End Triassic biotic crisis.

Rizzo, V., 2020. Why should geological criteria used on Earth not be valid also for Mars? Evidence of possible microbialites and algae in extinct Martian lakes. International Journal of Astrobiology 19, 283-294.

https://doi.org/10.1017/S1473550420000026

During the Noachian period, 4.1-3.7 Gys ago, the Martian environment was moderately similar to the one on present Earth. Liquid water was widespread in a neutral environment, volcanic activity and heat flow more vigorous, and atmospheric pressure and temperature were higher than today. These conditions may have favoured the spread of life on the surface of Mars. The recognition that different planets and moons share rocky material cast in space by meteoroid impact entails that life creation is not necessary for each single planetary body, but could travel through the Solar system on board of rock fragments. Studies conducted on the past forms of Martian life have already highlighted possible positive matches with microbialite-like structures, referable to the geo-environmental conditions in the Noachian and Hesperian. However, by necessity, these studies are on predominantly micro and meso-scopic scale structures and doubts arise as to their attribution to the biogenic world. We suggest that in the identification of Martian life, we are currently in a

position similar to the one of Kalkowsky who in 1908, based solely on morphological and sedimentological arguments, hypothesized the (now accepted) view of the biotic origin of stromatolites. Our analysis of thousands of images from Spirit, Opportunity and Curiosity has provided a selection of images of ring-shaped, domal and coniform macrostructures that resemble terrestrial microbialites such as the ring-shaped stromatolites of Lake Thetis, and stacked cones reminiscent of the group of terrestrial Conophyton. Notably, the latter were detected by Curiosity in the mudstone known as ‘Sheepbed’, the same outcrop where past organic molecules have been detected and where the occurrence of microbial-induced sedimentary structures (MISS) and of many more microbialitic micro, meso and macrostructures has already been hypothesized. Some of the structures discussed in this work are so complex that alternative biological hypotheses can be formulated as possible algae. Alternate, non-abiotic explanations are examined but we find difficult to explain some of such structures in the context of normal sedimentary processes, both syngenetic or epigenetic.



Many recent studies conclude that plate tectonics started about 3 billion years ago in the mid Archean. The transition from a pre-subduction regime to modern plate tectonics is reported to be marked by changes in trace element ratios or isotopic compositions that monitor the rate of growth of the continental crust, the appearance of eclogitic inclusions in diamonds, or an apparent change in the composition of the upper crust. Behind most of these arguments is the hypothesis that, early in Earth history when the mantle was hotter, subduction was intermittent or impossible. If so, a mechanism other than subduction must have created the granitoids that dominate Archean continental crust. One alternative, commonly referred to as sagduction, proposes that the base of thick oceanic crust founders and partially melts to generate granitic magma. Here we evaluate the sagduction process, starting by discussing two crucial concepts: (1) thick oceanic crust is internally differentiated, with hydrated basalt being restricted to the uppermost layers, (2) the generation of granitic magma requires that water and basalt is present in the lower part of the crust or is taken deep into the mantle. We present the results of numerical modelling that demonstrates that when intrusion is taken into account, the lower portion of the crust is well above dehydration temperatures and therefore essentially dry. We show that any deformation within thick, differentiated crust is restricted to the lowermost layers of dry, infertile mafic-ultramafic cumulates that lack the ingredients essential for the generation of granitic magma. Given the implausibility of the sagduction process, we suggest that subduction was the main mechanism that generated granitoid magmas, in the Archean as today.

Romero Yanes, J.F., Ferreira, A.F.B., Gomes de Medeiros, P.Y., Bassani, G.S., Fleming, F.P., Feitosa, F.X., de Sant’Ana, H.B., 2020. Phase behavior for crude oil and methane mixtures: Crude oil property comparison. Energy & Fuels 34, 5188-5195.


A wide variation in composition and thermodynamic properties is expected for different reservoir fluids, from the simplest one containing only methane and light compounds to those with high

compositional complexity. In this work, phase behavior of six different reservoir fluids recombined with methane was compared and contrasted. From our past work (Romero Yanes, J. F.; Feitosa, F. X.; Fleming, F. P.; de Sant’Ana, H. B. Experimental Study of the Phase Behavior of Methane and Crude Oil Mixtures. Fuel 2019, 255, 115850, DOI: 10.1016/j.fuel.2019.115850), a low asphaltene crude oil [28.0° American Petroleum Institute (API) gravity, 0.68 wt % n-C7 asphaltenes], referred to here as BRO, has presented a complex phase behavior when mixed with methane, especially when the methane content is around 75.0 mol %. On the basis of these results, the phase behavior of six different crude oils mixed with 75.0 mol % methane was studied in this work. The main characteristics of samples can be summarized as follows: a light condensate fluid (P1, 44.0° API gravity, and no detected n-C7 asphaltenes), three medium crude oils [(P2, 30.8° API gravity, and 0.09 wt % n-C7 asphaltenes), (P3, 26.0° API gravity, and 0.54 wt % n-C7 asphaltenes), and (P4, 25.1° API gravity, and 0.12 wt % n-C7 asphaltenes)], and two heavier crude oils [(P5, 19.5° API gravity, and 2.69 wt % n-C7 asphaltenes) and (P6, 18.7° API gravity, and 2.09 wt % n-C7 asphaltenes)]. From these fluids, mixtures with methane were prepared and their phase behavior was evaluated using a constant composition expansion test, coupled with a near-infrared solid detection system and high-pressure microscopy. For P1 and P4 systems, a unique phase transition at the bubble point was detected. On the other hand, for P2 and P3 systems, non-typical multiphase equilibria were observed associated with asphaltene precipitation, similar to that described for the BRO mixture. Phase segregation with no fractal geometry was observed from the phase transition onset pressure to the bubble pressure for P2, BRO, and P3 crude oils. Additionally, BRO and P3 show minor aggregation at pressures above the bubble pressure, with rapid redissolution when gas evolves at saturation pressures. P5 and P6 systems have phase transitions at a higher pressure because of their high asphaltene content. Phase transitions and related characteristics were associated with crude oil solvency for heavy compounds and their stability.



This paper comprises the analysis of scanning electron microscopy (SEM) images, nuclear magnetic resonance (NMR) and mercury injection capillary pressure (MICP) data to quantify the pore distribution in coal matrix. We first generate the 3D pore system in the coal matrix based on the statistics of pore distribution obtained from 2D SEM images, and then extract the pore network using the maximal ball method. The influence of the reconstructed cube size and the 2D image resolution on the accuracy of the reconstructed 3D coal sample was analysed when generate the 3D digital coal smaple. It was observed that the highest resolution which was achieved for the studied samples (6 nm) resulted in the underestimation of porosity of the studied sample, and it is recommended for future to create several models with different resolution to find the most representative model, instead of apriori using the highest possible resolution. The extracted pore network was then used to analyse pore size distribution and perform capillary pressure simulation using pore network modeling. A comparison of the pore network analysis with NMR and measured MICP data demonstrated that the pore network extraction method simplified the results of distribution and underestimated the size of elongated pores and microfractures. The simulated and laboratory measured MICP shows significant difference partically bucease the network extraction method was not suitable for the studied samples and this could be overcomed by our future study of model MICP using direct simulation method in the reconstructed 3D model.

Ruan, Z.-p., Cao, W.-m., Zhang, X., Liu, J.-t.-y., Zhu, J.-c., Hu, B., Jiang, J.-d., 2020. Rhizobium terrae sp. nov., isolated from an oil-contaminated soil in China. Current Microbiology 77, 1117-1124.

https://doi.org/10.1007/s00284-020-01889-5

A Gram-stain-negative, facultative aerobic, non-spore-forming, non-motile, non-flagellated, rod-shaped bacterium, designated strain NAU-18T was isolated from an oil-contaminated soil in China. Strain NAU-18T could grow at 10–42 °C (optimum, 30 °C), at pH 5.0–8.0 (optimum, 7.0) and in the presence of 0–2.0% (w/v) NaCl (optimum, 0.5% NaCl in R2A). The predominant fatty acids were C18:1ω7c (71.2%) and Summed feature 2 (5.1%), representing 76.3% of the total fatty acids. The major respiratory quinones were Q9 and Q10. The DNA G + C content of strain NAU-18T was 61.4 mol% based on its draft genome sequence. Genome annotation of strain NAU-18T predicted the presence of 6668 genes, of which 6588 are coding proteins and 80 are RNA genes. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain NAU-18T was a member of the genus Rhizobium and showed 96.93% (with 93.2% coverage) and 96.81% (with 100% coverage) identities with those of Neorhizobium alkalisoli CCBAU 01393T and Rhizobium oryzicola ZYY136T, respectively. In the phylogenetic analysis, strain NAU-18T and R. oryzicola ZYY136T are consistently placed in the same branch. Strain NAU-18T represents a novel species within the genus Rhizobium, for which the name Rhizobium terrae sp. nov. is proposed, with the type strain NAU-18T (=KCTC 62418T = CCTCC AB 2018075T).

Rui, J., Zhang, H., Ren, Q., Yan, L., Guo, Q., Zhang, D., 2020. TOC content prediction based on a combined Gaussian process regression model. Marine and Petroleum Geology 118, 104429.


Continuous total organic carbon (TOC) content estimation plays a crucial role in source rock reservoir evaluation. However, conventional prediction methods (e.g., empirical formulas or the δlogR method) have low prediction accuracy. Although machine learning algorithms possess a better prediction accuracy, they have also reached a bottleneck in this regard. Recently, ensemble learning and combined model prediction have achieved excellent results in many fields. In this study, a combined model was used for building a more accurate prediction model. Based on the theory that different formations correspond to different logging responses, we hypothesized that a Gaussian mixture model (GMM) classification of the logging data would be able to represent different geological conditions. Hence, we constructed independent Gaussian process regression (GPR) model based on the classified data; in particular, the posterior probability given by the GMM was used as a weight coefficient to combine the prediction results of all the independent GPR models. In addition, a confidence interval was obtained through the GPR to quantify the uncertainty of the prediction results. Finally, an error analysis showed that the combined-GPR model performed better than the δlogR method and other machine learning algorithms. In conclusion, the combined prediction model proposed in this study is reliable and effective, and it provides a new solution for quantitative prediction problems in corresponding fields.



Vanadyl petroporphyrins purified from a North American petroleum vacuum residue are used in experiments probing the interfacial phenomena of the petroporphyrins as well as asphaltene–petroporphyrin mixtures. Water–oil emulsion stability as a proxy for film strength is measured using the centrifugal method. Interfacial tension and elasticity of asphaltene and petroporphyrin films are recorded over tens of hours using an interfacial dilational rheometer. Film thicknesses of asphaltene films with and without petroporphyrins are estimated by fitting multiple models to small-angle neutron scattering curves. UV–visible spectroscopy is used to compare petroporphyrin content in the interfacial and bulk material of emulsions. Petroporphyrins are shown to be surface active and have significant effects on asphaltene film development. Surface-active petroporphyrins form monolayers at the interface with very low tension and high dilatational elasticity. However, this high elasticity does not translate to film strength. Being more surface active than asphaltenes, petroporphyrins may displace the first layer of asphaltenes that adsorb at the interface. However, thick asphaltene films that kinetically stabilize the emulsified water droplets still form. Monodisperse populations of petroporphyrins are prone to precipitation and therefore do not stabilize the interface or form an elastic film.

Sachaniya, B.K., Gosai, H.B., Panseriya, H.Z., Dave, B.P., 2020. Bioengineering for multiple PAHs degradation for contaminated sediments: Response surface methodology (RSM) and artificial neural network (ANN). Chemometrics and Intelligent Laboratory Systems 202, 104033.


Scientific community around the globe have major focus on designing bioremediation strategies for persistent, recalcitrant, highly toxic and carcinogen/mutagen polycyclic aromatic hydrocarbons (PAHs) present in marine environment. For the bioremediation strategy, components of growth medium are a key factor, which enhance degradation of the PAHs through simulating the microbial growth. Thus, present study involves bioengineering of growth medium (ONR7a) using response surface methodology (RSM) and artificial neural network (ANN) for enhanced multiple PAHs biodegradation. Microbes were isolated from contaminated sediments of Alang Sosiya Ship Breaking Yard (ASSBRY), Gulf of Khambhat, Gujarat, India. RSM - a process centric approach has resulted in an increase in PAHs degradation from 69% (Unoptimized) to 90.03% with 1.29 folds increase on 5th day with R2 value of 0.98. Moreover, use of Artificial Neural Network (ANN) – a data centric approach resulted in better prediction of PAHs degradation of 93.36% compared to the CCD-RSM predicted PAHs degradation of 90.03% with R2 value of 0.98. Based on various error functions such as mean absolute deviation (MAD), mean squared error (MSE), root mean squared error (RMSE) and mean absolute percentage error (MAPE), the predictive ability of the constructed ANN models was found to be higher compared to RSM. As this is the first ever report on PAHs degradation by bacterial mixed culture using data centric approach, this study bridges the gap between fundamental research and its application for policymakers and stakeholders which would be helpful in designing appropriate bioremediation technologies.



An aerobic methane oxidizing bacterium, designated XLMV4T, was isolated from the oxic surface layer of an oil sands tailings pond in Alberta, Canada. Strain XLMV4T is capable of growth on methane and methanol as energy sources. NH4Cl and sodium nitrate are nitrogen sources. Cells are Gram-negative, beige to yellow-pigmented, motile (via a single polar flagellum), short rods 2.0–3.3 µm in length and 1.0–1.6 µm in width. A thick capsule is produced. Surface glycoprotein or cup shape proteins typical of the genera Methylococcus, Methylothermus and Methylomicrobium were not observed. Major isoprenoid quinones are Q-8 and Q-7 at an approximate molar ratio of 71 : 22. Major polar lipids are phosphoglycerol and ornithine lipids. Major fatty acids are C16 : 1 ω8+C16 : 1 ω7 (34 %), C16 : 1 ω5 (16 %), and C18 : 1 ω7 (11 %). Optimum growth is observed at pH 8.0 and 25 °C. The DNA G+C content based on a draft genome sequence is 46.7 mol%. Phylogenetic analysis of 16S rRNA genes and a larger set of conserved genes place strain XLMV4T within the class Gammaproteobacteria and family Methylococcaceae , most closely related to members of the genera Methylomicrobium and Methylobacter (95.0–97.1 % 16S rRNA gene sequence identity). In silico genomic predictions of DNA–DNA hybridization values of strain XLMV4T to the nearest phylogenetic neighbours were all below 26 %. On the basis of the data presented, strain XLMV4T is considered to represent a new genus and species for which the name Methylicorpusculum oleiharenae is proposed. Strain XLMV4T (=DSMZ DSM 27269=ATCC TSD-186) is the type strain.

Saito, M.A., McIlvin, M.R., Moran, D.M., Santoro, A.E., Dupont, C.L., Rafter, P.A., Saunders, J.K., Kaul, D., Lamborg, C.H., Westley, M., Valois, F., Waterbury, J.B., 2020. Abundant nitrite-oxidizing metalloenzymes in the mesopelagic zone of the tropical Pacific Ocean. Nature Geoscience 13, 355-362.

https://doi.org/10.1038/s41561-020-0565-6

Numerous biogeochemical reactions occur within the oceans’ major oxygen minimum zones, but less attention has been paid to the open ocean extremities of these zones. Here we report measurements on oxygen minimum zone waters from the Eastern to the Central Tropical North Pacific, which we analysed using metaproteomic techniques to discern the microbial functions present and their influence on biogeochemical cycling. We found nitrite oxidoreductase—an iron-rich enzyme from Nitrospina bacteria—to be one of the most abundant microbial proteins present in the mesopelagic zone, with over 60 billion molecules per litre. Estimated reaction rates imply that this enzyme is undersaturated and that its high abundance provides a latent mesopelagic catalytic capacity to rapidly oxidize nitrite derived from episodic fluxes of degrading sinking organic matter. In addition, given the enzyme’s intensive iron demand, its high abundance represents a previously unrecognized microbial reservoir within suboxic mesopelagic zones. Nitrite oxidoreductase may also contribute to other reactions involving nitrogen and redox-sensitive metals. We suggest that the abundance and extent of nitrite oxidoreductase may increase with continued deoxygenation in the oceans, and result in increased mesopelagic demand for iron and other potential changes to marine biogeochemical cycles.

Salese, F., McMahon, W.J., Balme, M.R., Ansan, V., Davis, J.M., Kleinhans, M.G., 2020. Sustained fluvial deposition recorded in Mars’ Noachian stratigraphic record. Nature Communications 11, 2067.

https://doi.org/10.1038/s41467-020-15622-0

Orbital observation has revealed a rich record of fluvial landforms on Mars, with much of this record dating 3.6–3.0 Ga. Despite widespread geomorphic evidence, few analyses of Mars’ alluvial sedimentary-stratigraphic record exist, with detailed studies of alluvium largely limited to smaller sand-bodies amenable to study in-situ by rovers. These typically metre-scale outcrop dimensions have prevented interpretation of larger scale channel-morphology and long-term basin evolution, vital for understanding the past Martian climate. Here we give an interpretation of a large sedimentary succession at Izola mensa within the NW Hellas Basin rim. The succession comprises channel and barform packages which together demonstrate that river deposition was already well established >3.7 Ga. The deposits mirror terrestrial analogues subject to low-peak discharge variation, implying that river deposition at Izola was subject to sustained, potentially perennial, fluvial flow. Such conditions would require an environment capable of maintaining large volumes of water for extensive time-periods, necessitating a precipitation-driven hydrological cycle.

Salta, Z., Tasinato, N., Lupi, J., Boussessi, R., Balbi, A., Puzzarini, C., Barone, V., 2020. Exploring the maze of C2N2H5 radicals and their fragments in the interstellar medium with the help of quantum-chemical computations. ACS Earth and Space Chemistry 4, 774-782.


Among the species discovered in the interstellar medium and planetary atmospheres, a crucial role is played by the so-called “interstellar” complex organic molecules (iCOMs) because they are the signature of the increasing molecular complexity in space. Indeed, they may represent the connection between simple molecules and biochemical species like amino acids and nucleobases. In particular, HCN and the related CN radical are the starting points of rich nitrile chemistry. In this framework, we have undertaken a computational investigation of the gas-phase reaction mechanisms involving different C2N2H5 radicals and their fragments, stemming from the addition of the cyano radical to the nitrogen atom of methylamine. Aiming at exploiting an accurate yet cost-effective protocol, a combination of CCSD(T)-based composite schemes and density functional theory has been employed. The exploration of the plausible chemical reaction channels has led to the identification of 12 different products, as well as 28 transition states connecting reactants, intermediates, and products. Aminoacetonitrile (H2NCH2CN), proposed as an intermediate in the formation of the smallest amino acid glycine, and the CH2NH2 radical appear as products energetically accessible under astrophysical conditions.



Significance: The valorization of the plant polymer lignin is critical to enable the bioeconomy, but the heterogeneity of lignin presents a barrier to its use. Natural microbial conversion processes funnel aromatic compound mixtures to single products and thus, have emerged as a means to overcome lignin heterogeneity. Accordingly, understanding the mechanisms that bacteria use to convert lignin degradation products is of importance for their eventual industrial application. Here, we demonstrate that a promising bacterial chassis for lignin-relevant synthetic biology, Pseudomonas putida, secretes outer membrane vesicles that turn over aromatic compounds extracellularly. From this work, we propose a mechanism for extracellular nutrient acquisition from aromatic compounds by soil bacteria, which holds promise for improving the efficiency of microbial lignin conversion.

Abstract: Lignin is an abundant and recalcitrant component of plant cell walls. While lignin degradation in nature is typically attributed to fungi, growing evidence suggests that bacteria also catabolize this complex biopolymer. However, the spatiotemporal mechanisms for lignin catabolism remain unclear. Improved understanding of this biological process would aid in our collective knowledge of both carbon cycling and microbial strategies to valorize lignin to value-added compounds. Here, we examine lignin modifications and the exoproteome of three aromatic–catabolic bacteria: Pseudomonas putida KT2440, Rhodoccocus jostii RHA1, and Amycolatopsis sp. ATCC 39116. P. putida cultivation in lignin-rich media is characterized by an abundant exoproteome that is dynamically and selectively packaged into outer membrane vesicles (OMVs). Interestingly, many enzymes known to exhibit activity toward lignin-derived aromatic compounds are enriched in OMVs from early to late stationary phase, corresponding to the shift from bioavailable carbon to oligomeric lignin as a carbon source. In vivo and in vitro experiments demonstrate that enzymes contained in the OMVs are active and catabolize aromatic compounds. Taken together, this work supports OMV-mediated catabolism of lignin-derived aromatic compounds as an extracellular strategy for nutrient acquisition by soil bacteria and suggests that OMVs could potentially be useful tools for synthetic biology and biotechnological applications.



Characterization of the metabolic heterogeneity in cell populations requires the analysis of single cells. Most current methods in single-cell analysis rely on cell manipulation, potentially altering the abundance of metabolites in individual cells. A small sample volume and the chemical diversity of metabolites are additional challenges in single-cell metabolomics. Here, we describe the combination of fiber-based laser ablation electrospray ionization (f-LAESI) with 21 T Fourier transform ion cyclotron resonance mass spectrometry (21TFTICR-MS) for in situ single-cell metabolic profiling in plant tissue. Single plant cells infected by bacteria were selected and sampled directly from the tissue without cell manipulation through mid-infrared ablation with a fine optical fiber tip for ionization by f-LAESI. Ultrahigh performance 21T-FTICR-MS enabled the simultaneous capture of isotopic fine structures (IFSs) for 47 known and 11 unknown compounds, thus elucidating their elemental compositions from single cells and providing information on metabolic heterogeneity in the cell population.

Sanei, H., Ardakani, O.H., Akai, T., Akihisa, K., Jiang, C., Wood, J.M., 2020. Core versus cuttings samples for geochemical and petrophysical analysis of unconventional reservoir rocks. Scientific Reports 10, 7920.

https://doi.org/10.1038/s41598-020-64936-y

Core samples from petroleum wells are costly to obtain, hence drill cuttings are commonly used as an alternative source of rock measurements for reservoir, basin modelling, and sedimentology studies. However, serious issues such as contamination from drilling mud, geological representativeness, and physical alteration can cast uncertainty on the results of studies based on cuttings samples. This paper provides a unique comparative study of core and cuttings samples obtained from both vertical and horizontal sections of a petroleum well drilled in the Canadian Montney tight gas siltstone reservoir to investigate the suitability of cuttings for a wide range of geochemical and petrophysical analyses. The results show that, on average, the bulk quantity of kerogen or solid bitumen measured in cuttings is comparable to that of the core samples. However, total organic carbon (TOC) measurements are influenced by oil-based drilling mud (OBM) contamination. Solvent-cleaning of cuttings has been shown to effectively remove OBM contamination in light, medium, and heavy range hydrocarbons and to produce similar kerogen/solid bitumen measurements to that of core samples. Similarly, pyrolysis methods provide an alternative to the solvent-cleaning procedure for analysis of kerogen/solid bitumen in as-received cuttings. Microscopic study substantiates the presence of significant contamination by OBM and caved organic and inorganic matter in the cuttings, which potentially influence the bulk geochemistry of the samples. Furthermore, minerals in the cuttings display induced micro-fractures due to physical impacts of the drilling process. These drilling-induced micro-fractures affect petrophysical properties by artificially enhancing the measured porosity and permeability.


https://doi.org/10.1007/s00284-020-01883-x

Screening of high-efficient polycyclic aromatic hydrocarbon (PAH)-degrading bacteria is important due to environmental contamination by PAHs. In this study, sediment contaminated with phenanthrene (Phe), pyrene (Pyr), and fluoranthene (Fluo) was used as a source of bacteria. The ability of these isolated bacteria to convert PAHs into valuable products was determined. Based on a primary screening, 20 bacterial isolates were obtained; however, only three strains showed a good PAH-degrading ability, and were identified as Pseudomonas aeruginosa, Pseudomonas sp., and Ralstonia sp. PAH-degrading genes were detected in all isolates. Notably, all selected strains could degrade PAHs using the ortho or meta cleavage pathways due to the presence of catechol dioxygenase genes. The ability of isolated strains to convert PAHs into polyhydroxyalkanoate (PHA) was also evaluated in both single and mixed cultures. Single cultures of P. aeruginosa PAH-P02 showed 100% degradation of PAHs, with the highest biomass (1.27 ± 0.02 g l−1) and PHA content (38.20 ± 1.92% dry cell weight). However, degradative ability and PHA production were decreased when mixtures of PAHs were used. This study showed that P. aeruginosa, Pseudomonas sp., and Ralstonia sp. were able to degrade PAHs and convert them into medium-chain-length (mcl)-PHA. A high content of 3-hydroxydecanoate (3HD, C10) was observed in this study. The formation of mcl-

PHA with high 3HD content from Pyr and Fluo, and the assessment of mixed cultures converting PAHs to mcl-PHA, were novel contributions.

Santa, M.L.S., Sabet, N., Hassanzadeh, H., 2020. Propane-aided leaching of bitumen from oilsands. Energy & Fuels 34, 5798-5803.


We report highly fine-grid numerical simulations of solvent-aided bitumen leaching using propane as a solvent. These simulations allowed us to observe the detailed physics of the drainage process, which is otherwise impossible in coarse-grid simulations. Our results revealed significant fingering of the solvent into bitumen as a result of viscosity and density contrasts, which is in line with the previous experimental observation of bitumen leaching by toluene. Based on our simulation results, the drainage process undergoes two distinct infinite-acting and finite-acting periods, with more than two-thirds of the drainage taking place during the former. Interestingly, the rate of drainage of bitumen is constant during the infinite-acting period, and it is independent of formation thickness. Using the results of our simulations, we found out that the rate of drainage of bitumen is scaled linearly with formation permeability. The results of this work shed light on the fine-scale physics of the bitumen leaching process by solvents and pave the way for the development of new recovery processes.

Santos, J.C.d., Lopes, D.R.G., Da Silva, J.D., De Oliveira, M.D., Dias, R.S., Lima, H.S., De Sousa, M.P., De Paula, S.O., Silva, C.C.d., 2020. Diversity of sulfate-reducing prokaryotes in petroleum production water and oil samples. International Biodeterioration & Biodegradation 151, 104966.


Microorganisms from oil reservoirs are associated with negative impacts on the oilfield, such as oil biodeterioration and biocorrosion of steel structures used for exploration, transportation and storage. The objectives of this study were to analyze the taxonomic and functional diversity in the production water and oil of two oil reservoirs, with emphasis on H2S producing bacteria. Total DNA from the microbial community was extracted, and the taxonomic and functional diversity was evaluated. The phyla Proteobacteria, Firmicutes and Euryarchaeota were the most abundant among the samples and contain the main sulfate-reducing species, such as Desulfovibrio alaskensis and Archeoglobus fulgidus. The production water and the oil were found to have taxonomic and functionally different microbial communities in the three communities, however correlation networks showed basically the same types of interconnected metabolism between the sulfidogenic microorganisms. This indicates the importance of understanding the microbial diversity and metabolic capacity of communities in these environments and trying to control harmful processes that may result in huge economic damage to the oil industry.

Sass, K., Perner, M., 2020. Characterization of two hydrogen-oxidizing Hydrogenovibrio strains from Kermadec volcanic island arc hydrothermal vents. Frontiers in Marine Science 7, 295. doi: 10.3389/fmars.2020.00295.


The genus Hydrogenovibrio consists of chemolithotrophic sulfur- and hydrogen-oxidizing bacteria that are found in diverse marine environments including hydrothermal vents where they can reach high cell numbers. Although several vent Hydrogenovibrio genomes encode for [NiFe]-hydrogenases (enzymes catalyzing the reversible reaction of hydrogen into protons and electrons), different attempts to grow these strains on hydrogen failed for a long time. Not long ago it was shown that some Hydrogenovibrio strains from hydrothermal vents are indeed able to oxidize hydrogen, which broadens their physiological spectrum in a competitive environment for energy sources. We here identify two active hydrogen consuming bacteria of the Hydrogenovibrio genus with different hydrogenase genes from vents in the South Pacific Ocean. Based on our results, hydrogen consuming Hydrogenovibrio species seem to be much more widespread in the oceans than expected.

Schmidt, J.S., Hinrichs, R., 2020. Evaluation of terrestrial carbonaceous matter aromatization by Raman spectroscopy and its application to C chondrites. Meteoritics & Planetary Science 55, 800-817.

https://doi.org/10.1111/maps.13467

A Raman method to estimate the aromatization degree of carbonaceous matter (CM) was established, and calibrated by literature data respecting differences in acquisition procedures. The generated equations allowed a comparison of the G-band width to vitrinite reflectance, and to additional structural organization parameter extracted from X-ray powder diffraction. The relations between aromatization degree and peak temperatures from literature were then propagated to G-band width parameter. The applicability of these geothermometers is demonstrated by the consistency of data obtained for carbonaceous chondrites with previous estimations. Since the CM aromatization is controlled by peak temperature and time span, it is possible to estimate the duration of chondrite?s heating events. The G-band width relation to elemental ratio trends of organic matter in chondrites, interplanetary dust particles, glucose, and saccharose-based semi-coke favors synthesis by formose route. These findings provide new approaches for the future development of chemical kinetic models for organic matter of chondrites. A reliable chemical model may allow the external calibration of numerical models for accurately evaluating the peak temperatures and cooling durations of chondrites.

Schoch, R.R., Werneburg, R., Voigt, S., 2020. A Triassic stem-salamander from Kyrgyzstan and the origin of salamanders. Proceedings of the National Academy of Sciences 117, 11584-11588.


Significance: The origin of modern amphibians remains controversial, and especially the fossil record of salamanders remains poor. Their tiny, feeble skeletons are rarely preserved in rocks of the early Mesozoic era, the time frame in which they are believed to have originated. Here we report 230 million-year-old fossils from Kyrgyzstan, Inner Asia, providing the most ancient evidence of salamanders. They enable us to reconstruct crucial steps in the evolution of the salamander body plan, sharing numerous features with ancient amphibians, the temnospondyls. These finds push back the rock record of salamanders by 60 to 74 Ma and at the same time bridge the wide anatomic gap among salamanders, frogs, and temnospondyls.

Abstract: The origin of extant amphibians remains largely obscure, with only a few early Mesozoic stem taxa known, as opposed to a much better fossil record from the mid-Jurassic on. In recent time, anurans have been traced back to Early Triassic forms and caecilians have been traced back to the Late Jurassic Eocaecilia, both of which exemplify the stepwise acquisition of apomorphies. Yet the most ancient stem-salamanders, known from mid-Jurassic rocks, shed little light on the origin of the clade. The gap between salamanders and other lissamphibians, as well as Paleozoic tetrapods, remains considerable. Here we report a new specimen of Triassurus sixtelae, a hitherto enigmatic tetrapod from the Middle/Late Triassic of Kyrgyzstan, which we identify as the geologically oldest stem-group salamander. This sheds light not only on the early evolution of the salamander body plan, but also on the origin of the group as a whole. The new, second specimen is derived from the same beds as the holotype, the Madygen Formation of southwestern Kyrgyzstan. It reveals a range of salamander characters in this taxon, pushing back the rock record of urodeles by at least 60 to 74 Ma (Carnian–Bathonian). In addition, this stem-salamander shares plesiomorphic characters with temnospondyls, especially branchiosaurids and amphibamiforms.



This publication reports high resolution mass spectral data for copper chlorophyll and copper chlorophyll degradation products extracted from bright green table olives. These data support analyte identifications made in “Quantitation of copper chlorophylls in green table olives by ultra-high-performance liquid chromatography with inductively coupled plasma isotope dilution mass spectrometry” in the Journal of Chromatography A (Petigara Harp et al., 2020 [1]). Table olive pigments, divided into lipophilic and hydrophilic fractions by liquid-liquid repartition, were separated by ultra-high-performance liquid chromatography and detected by visible wavelength absorbance and high resolution mass spectrometry, using an Orbitrap HF with positive electrospray ionization. Full-scan mass spectra were acquired to assign pigment chemical formulae. Fragment-rich higher-energy collisional dissociation tandem mass spectra were acquired to facilitate structural assignments. Extracted ion chromatograms, full-scan, and tandem mass spectra obtained from representative lipophilic and hydrophilic green table olive extracts are presented in Figures 1-6. Annotated mass spectra comparing experimental and calculated isotope distributions, .raw mass spectral data files, and experimental details linking .raw data files to annotated spectra are provided as Supplementary Material. Spectra extracted from these native data files can be added to mass spectral libraries for use in other studies. Access to native data files uniquely enables rigorous data examination (e.g., molecular ion isotopic distribution, effective mass resolution, presence of overlapping ion series) and use in ways that are not possible when spectra are otherwise reported in simple tables listing mono-isotopic peaks and mass errors. Mass spectra reported here can be used to design multiple-reaction monitoring methods to detect these bright green pigments in agricultural food commodities and finished products.

Schutte, C.A., Marton, J.M., Bernhard, A.E., Giblin, A.E., Roberts, B.J., 2020. No evidence for long-term impacts of oil spill contamination on salt marsh soil nitrogen cycling processes. Estuaries and Coasts 43, 865-879.

https://doi.org/10.1007/s12237-020-00699-z

Salt marshes are important sites of nitrogen cycling and removal that straddle the land/ocean interface, allowing them to intercept human-derived nitrogen before it reaches coastal waters where it causes problems like hypoxia and harmful algal blooms. In 2010, the Deepwater Horizon oil spill released an estimated five million barrels of crude oil into the Gulf of Mexico, significantly contaminating coastal wetlands over approximately 800 km of shoreline. We investigated microbial nitrogen cycling processes in soil from four salt marshes in Terrebonne Bay, Louisiana, USA that were either exposed or not exposed to Deepwater Horizon oil over the course of 1 year (2013–2014), 2.5–3.5 years post-spill. Specifically, we measured nitrification and denitrification potentials, nitrogen cycling functional gene abundances (nirS, bacterial and archaeal amoA), and soil physical and chemical properties. We show that variation in nitrification and denitrification potentials was independent of site oil exposure. Large year-to-year differences in springtime nitrification potentials were inversely related to plant live belowground biomass, indicating that competition for nitrogen is likely an important control on nitrification. There were positive correlations between nitrification potentials and both soil extractable nitrate concentrations and denitrification potentials, supporting the idea that denitrification is coupled with nitrification. We found no evidence that there was a long-term impact of oil exposure on salt marsh soil microbial nitrogen cycling processes and the nitrogen removal ecosystem service they provide. It is important to note, however, that these impacts could have been masked by high background variability in process rates or loss of oil exposed soil to coastal erosion.

Servais, S., Kominoski, J.S., Coronado-Molina, C., Bauman, L., Davis, S.E., Gaiser, E.E., Kelly, S., Madden, C., Mazzei, V., Rudnik, D., Santamaria, F., Sklar, F.H., Stachelek, J., Troxler, T.G., Wilson, B.J., 2020. Effects of saltwater pulses on soil microbial enzymes and organic matter breakdown in freshwater and brackish coastal wetlands. Estuaries and Coasts 43, 814-830.

https://doi.org/10.1007/s12237-020-00708-1

Coastal freshwater and brackish wetlands are exposed to pulses of saltwater during times of reduced freshwater flows (i.e., dry seasons, droughts), periodic storm surges, and increased tidal extent associated with rising seas. The effects of saltwater pulses on belowground processing rates of detrital organic matter as mediated by microbial activities are uncertain. Our objectives were to quantify whether and how pulses of saltwater (i) change soil porewater physicochemistry, (ii) change soil microbial extracellular enzyme activities, and (iii) change root litter breakdown over time in freshwater and brackish marshes. From 2014 to 2016, we simulated saltwater intrusion as monthly in situ pulsed additions of artificial seawater in experimental dosing chambers (1.4 m diameter) within freshwater and brackish marshes of Everglades National Park. At monthly intervals, we collected soil porewater chemistry, and measured microbial extracellular enzymes, elemental stoichiometric ratios, and breakdown rates (k) of incubated (0–30 cm depth) root litter and compared these responses over time. Saltwater pulses increased sulfate and nitrogen concentrations in porewater at the freshwater site. However, saltwater pulses generally decreased porewater constituents (e.g., dissolved organic carbon, dissolved nitrogen and phosphorus species) at the brackish site. One saltwater pulse increased root litter k by 1.25-fold in the brackish marsh. However, long-term (740 days) k in brackish wetlands, and both short- and long-term k in freshwater wetlands, were not affected by 24 monthly pulses of saltwater. Enzyme activities fluctuated with time and did not respond to multiple saltwater pulses. Our results suggest that

detrital organic matter stocks and associated soil microbial activities are relatively resistant to single and multiple (n = 24) pulses of saltwater.

Service, R.F., 2020. Without fossil fuels, reactors churn out chemicals. Science 368, 566-567.

http://science.sciencemag.org/content/368/6491/566.2.abstract

As windmills and solar panels multiply, the supply of renewable electricity sometimes exceeds demand. Chemists would like to put the excess to work making commodity chemicals, such as the raw materials for fertilizer and plastics, which are now produced with heat, pressure, and copious fossil fuels. The electrochemical cells that can harness renewable electricity to make these compounds have been too slow to be practical. Now, two groups report redesigning the cells to achieve a dramatic speedup—perhaps enough to put green industrial chemistry within reach.

“In the future, electrons to molecules will be a major part of how we do chemical synthesis,” says Etosha Cave, chief scientific officer of Opus 12, a startup aiming to turn renewable energy into chemicals. “These two papers help push that vision forward.”

One research group uses carbon dioxide (CO2) as its starting material to make ethanol, a fuel, and ethylene, a starting point for plastics; the other turns nitrogen (N2) into ammonia (NH3), a key component in fertilizer. Both owe their progress to advances in the catalyst-coated electrodes that drive chemical reactions between gases and liquids.

In theory, turning CO2 into hydrocarbons such as ethanol and ethylene is simple: Just add energy to the CO2 so it can steal hydrogen atoms from water. But the reactions are tricky. They take place in electrolyzers, which consist of two electrodes separated by a liquid electrolyte. At one electrode, the anode, water splits into oxygen, electrons, and hydrogen ions, or protons. The protons then migrate through the electrolyte to the cathode, where they react with CO2, which is fed in separately, to make the hydrocarbons.

In current electrolyzers, the cathode typically consists of a 3D carbon mesh dotted with tiny copper catalyst particles. Their “gas diffusion” design allows CO2 gas that infiltrates the mesh to interact with all the catalyst particles simultaneously. One side of the mesh is also in contact with the liquid electrolyte, which helps ferry protons over from the anode. But water in the electrolyte can also infiltrate the pores, blocking CO2 gas from reaching the catalyst particles.

Coating the electrode with a water-repellent, fluorine-rich polymer can help. That and other improvements have resulted in electrolyzers that efficiently convert a modest input of electricity into hydrocarbons. But only about 40% of the product compounds have two carbon atoms, as ethylene and ethanol do. Much of the rest is methane, which has one carbon and is less valuable.

Now, researchers led by Ye Wang, a chemist at Xiamen University, report that adding fluorine to the standard copper catalyst on their gas diffusion electrode changes the pathway of the reactions, so that up to 85% of the resulting products are valuable two-carbon compounds.

The setup can also handle 1600 milliamps of current per square centimeter of catalyst, twice the throughput of the previous record holder, the researchers reported on 20 April in Nature Catalysis. “[It's] definitely in the range where someone will be interested in commercializing the technology,” says Karthish Manthiram, a chemical engineer at the Massachusetts Institute of Technology.

Manthiram reported parallel improvements in an electrochemical process for making NH3 using N2 from air and hydrogen (H2). The H2, made by splitting water in a separate cell, is fed into a second electrolyzer, where it splits into protons and electrons at the anode. The protons pass through a liquid electrolyte made of an organic solvent that the team spikes with lithium to speed transfer of hydrogen to nitrogen. At the cathode, a three-step chemical process takes place: Piped-in N2 splits into individual nitrogen atoms, which react with the lithium to make lithium nitride. The lithium nitride then reacts with protons and electrons coming from the anode to make NH3, regenerating the lithium.

Manthiram's team couldn't use a porous carbon cathode because the liquid electrolyte would flood the electrode, blocking N2 gas from the catalyst particles. So the researchers replaced the carbon cathode with a stainless steel mesh, which repels the organic electrolyte and allows N2 in.

The setup churned out ammonia nearly five times as fast as the previous record, the group reported this week in Nature Catalysis. Its efficiency for transferring electrons from water to NH3 is 40%, the highest ever achieved with an electrolyzer.

That still doesn't rival the performance of fossil fuel–based plants, which can make ammonia with up to 80% energy efficiency—an even more stringent measure than transferring electrons—but “it's absolutely great,” says Matteo Cargnello, a chemical engineer at Stanford University. Lauren Greenlee, a chemical engineer at the University of Arkansas, Fayetteville, agrees: “I think people will really jump on this” in search of further improvements.

With oil prices crashing because of price wars and the coronavirus pandemic, companies will likely continue to rely on fossil fuels to produce ammonia, ethanol, and other commodity chemicals in the near future. But as researchers continue to improve electricity-based production methods, even cheap fossil fuels may ultimately prove no match for surplus green energy.

Setta, F., Bergamaschi, S., Rodrigues, R., Jones, C., Chaves, H., Brito, M., Pereira, E., 2020. The volumetric potential assessment of the oil shales of Tremembé Formation, Taubaté Basin, Brazil. Journal of Petroleum Exploration and Production Technology 10, 1835-1848.

https://doi.org/10.1007/s13202-020-00846-z

This assessment of the volumetric potential of the oil shales of Tremembé Formation (Oligocene, Taubaté Basin, Brazil) was based on the sedimentological study of 2457 total organic carbon and 1007 Rock–Eval pyrolysis analyses of core samples from nine survey wells drilled in the central portion of Taubaté Basin. Along a 240-m-thick package in the upper part of Tremembé Formation, thirteen chemostratigraphic units with thicknesses varying from 10 to 35 m were identified. The upper interval (unit L), 30 m thick, exhibited the highest organic content and original generation potential and was thus studied in detail. In unit L, oil yield maps were constructed, seeking to identify the most attractive areas for industrially exploiting the oil shales, and volumetric calculations employing a probabilistic Monte Carlo method were conducted to quantify the potentially recoverable oil volume. Three exploratory scenarios based on yield values (S1 + S2) were considered for calculating the oil volumes, seeking to offer different exploratory scenarios for decision making. For the scenario that considered only average yields above 100 mg HC/g rock, the recoverable oil volume is 525 million bbl (P90) to 884 million bbl (P10); for the scenario that considered only average yields above 80 mg HC/g rock, the recoverable oil volume is 1.4 billion bbl

(P90) to 2.6 billion bbl (P10); and for the scenario that considered only average yields above 60 mg HC/g rock, the recoverable oil volume is 3.6 billion bbl (P90) to 5.4 billion bbl (P10).

Shahkarami, S., Buatois, L.A., Mángano, M.G., Hagadorn, J.W., Almond, J., 2020. The Ediacaran–Cambrian boundary: Evaluating stratigraphic completeness and the Great Unconformity. Precambrian Research 345, 105721.


The Ediacaran–Cambrian transition was a time of marked biological and sedimentary changes, representing a significant evolutionary breakthrough in Earth’s history. Numerous explanations have been posited for these dramatic changes. One view emphasizes an extensive period of widespread continental denudation during the Neoproterozoic followed by extensive reworking of the basement during the early Cambrian, resulting in the formation of what is known as the “Great Unconformity”. Geologic events leading to the formation of this unconformity have been hypothesized as an environmental trigger for the Cambrian explosion. Here we review seventeen key Ediacaran-Cambrian successions around the globe with a focus on their sedimentary facies and sequence-stratigraphic architecture. Based on this information, we explore the relationship of the Ediacaran–Cambrian boundary to this unconformity, underscoring a more nuanced scenario. We consider each section in a chemostratigraphic and chronostratigraphic framework, and consider the hypothesized origin of this unconformity at each locale—for example, whether it was eustatic in origin and therefore of global stratigraphic significance or whether it resulted from local tectonics, implying marked inter-basin diachronism. Our systematic review shows that significant diachronism was involved in the generation of the Great Unconformity, suggesting that the sea-level fall reflects overprint of local tectonics on pure eustasy. In most places, the Great Unconformity is actually a composite sequence boundary resulting from successive eustatic episodes of sea-level rise and fall overprinted by multiple tectonic events of subsidence and uplift. Thus this surface should not be used for inter-basin correlations. Although the general proximity and common co-occurrence of the Ediacaran–Cambrian boundary with a sequence boundary (SB) in places resulting in fluvial valley incision, has proved challenging for biostratigraphic sampling, by mapping this unconformity and its associated facies, there are new opportunities. In particular, paleontological work in terminal Ediacaran deposits located in interfluve positions may be promising because these areas may have preserved thick shallow-marine strata below the SB. Such strata could hold additional clues to help fill in gaps in our understanding of the Ediacaran roots of the Cambrian explosion.

Sheikh, S.Z., 2020. Nine axes of merit for technosignature searches. International Journal of Astrobiology 19, 237-243.

https://doi.org/10.1017/S1473550419000284

It can be difficult to develop an effective and balanced search strategy in SETI, especially from a funding perspective, given the diverse methodologies and myriad orthogonal proposals for the best technosignatures. Here I propose a framework to compare the relative advantages and disadvantages of various proposed technosignatures based on nine ‘axes of merit’. This framework was first developed at the NASA Technosignatures Workshop in Houston in 2018 and published in that report. I give the definition and rationale behind the nine axes as well as the history of each axis in the SETI and technosignature literature. These axes are then applied to three classes of

technosignature searches as an illustration of their use. An open-source software tool is available to allow technosignature researchers to make their own version of the figure.

Shen, J., Xia, J., Qin, L., Carlson, R.W., Huang, S., Helz, R.T., Mock, T.D., 2020. Stable chromium isotope fractionation during magmatic differentiation: Insights from Hawaiian basalts and implications for planetary redox conditions. Geochimica et Cosmochimica Acta 278, 289-304.


The stable isotope compositions of chromium (Cr) are fractionated during magmatic differentiation of lunar mare basalts, which might be attributed to redox-related mineral crystallization. It has yet to be demonstrated whether magmatic differentiation fractionates Cr isotope composition of terrestrial samples. Here, we present high-precision stable Cr isotope measurements, reported as δ53Cr relative to NIST SRM 979, of well-characterized Hawaiian tholeiitic basalts from Koolau, Mauna Kea and Kilauea. The studied Makapuu-stage Koolau lavas have MgO ranging from 6.58 to 21.54 wt.%, and they have homogeneous δ53Cr ranging from −0.21‰ to −0.17‰. Similarly, studied Mauna Kea lavas have MgO ranging from 9.11 to 17.90 wt.%, and they also have homogeneous δ53Cr ranging from −0.17‰ to −0.13‰. Some Makapuu-stage Koolau and Mauna Kea lavas experienced subaerial or submarine alteration. The homogenous δ53Cr within each sample suites implies that the post-magmatic alterations have not significantly changed the Cr isotope compositions of these samples. Conversely, nine Kilauea Iki basalts have MgO ranging from 7.77 to 26.87 wt.% reflecting varying degrees of magmatic differentiation, and they show resolvable Cr isotope variations with δ53Cr ranging from −0.18‰ to 0.00‰. The δ53Cr values of the Kilauea Iki samples are positively correlated with indicators of magmatic differentiation such as Cr and MgO contents, and Mg# values. The most evolved samples have the lightest isotope compositions, whereas the olivine-spinel cumulates display complementary heavy isotope compositions. This fractionation is most likely generated by the crystallization and accumulation of spinel, which is dominated by Cr3+ and, hence, enriched in heavier Cr isotopes relative to the residual melt. At a given MgO content, Kilauea and Mauna Kea lavas, both Kea-trend volcanoes, have higher δ53Cr than Makapuu-stage Koolau lavas, a Loa-trend volcano. This difference might reflect recycling of altered oceanic crusts or redox differences of their magmatic sources, with the mantle source of Makapuu-stage lavas being more reducing.

To understand the different Cr isotope fractionation behaviors of terrestrial and extraterrestrial basalts, we present a quantitative model that relates the Cr isotope compositions of basalts from the Earth, the Moon and Vesta, to the crystallization assemblage, the degree of fractional crystallization, and the Cr2+/ΣCr ratios of minerals and melts, which are related to the oxygen fugacity during differentiation. The primitive Hawaiian basaltic magma for Kilauea Iki and Mauna Kea lavas is estimated to have δ53Cr of −0.15‰, which is close to the average value of the BSE (−0.14‰ to −0.12‰). We further speculate that the initial lunar mantle is relatively homogeneous with BSE-like isotope composition (−0.16‰ to −0.09‰). The observed low δ53Cr in lunar mafic rocks is the result of redox-dominated fractional crystallization and accumulation processes of lunar mafic magmas. These magmas might be derived from variable degrees of partial melting of the primitive lunar mantle.

Combined with previous results on the variations in Cr valences and contents in silicate melts and minerals related to oxygen fugacity, Cr concentration and isotope composition can serve as a useful

oxybarometer for understanding the redox conditions of planetary differentiation and magmatic evolution.

Shen, S., Wu, W., Grimes, D.J., Saillant, E.A., Griffitt, R.J., 2020. Community composition and antibiotic resistance of bacteria in bottlenose dolphins Tursiops truncatus – Potential impact of 2010 BP Oil Spill. Science of The Total Environment 732, 139125.


Aquatic contamination, oil spills in particular, could lead to the accumulation of antibiotic resistance by promoting selection for and/or transfer of resistance genes. However, there have been few studies on antibiotic resistance in marine mammals in relation to environmental disturbances, specifically oil contaminations. Here we initiated a study on antibiotic resistance bacteria in bottlenose dolphins Tursiops truncatus in relation to oil contamination following the 2010 BP Oil Spill in the northern Gulf of Mexico. Bacterial communities and antibiotic resistance prevalence one year after the 2010 BP Oil Spill were compared between Barataria Bay (BB) and Sarasota Bay (SB) by applying the rarefaction curve method, and (generalized) linear mixed models. The results showed that the most common bacteria included Vibrio, Shewanella, Bacillus and Pseudomonas. The prevalence of antibiotic resistance was high in the bacterial isolates at both bays. Though bacterial diversity did not differ significantly among water or dolphin samples, and antibiotic resistance did not differ significantly among water samples between the two bays, antibiotic resistance and multi-drug resistance in dolphin samples was significantly higher in the BB than in the SB, mainly attributed to the resistance to E, CF, FEP and SXT. We also found sulfamethoxazole-trimethoprim-resistant Stenotrophomonas maltophilia the first time in the natural aquatic environment. The higher antibiotic resistance in the dolphins in BB is likely attributed to 2010 BP Oil Spill as we expected SB, a more urbanized bay area, would have had higher antibiotic resistance based on the previous studies. The antibiotic resistance data gathered in this research will fill in the important data gaps and contributes to the broader spatial-scale emerging studies on antibiotic resistance in aquatic environments.



This study aimed to investigate the geometry distinction of the pores formed by brittle minerals in shale oil reservoir and dig out its significance in hydrocarbon migration and exploitation.

14050 pores related to brittle minerals in typical shale oil reservoir samples are selected as the research objects, high-resolution field emission scanning electron microscopy (FE-SEM), imbibition test, Nuclear Magnetic Resonance(NMR), high-resolution image technique, construction of new parameters, statistics and analysis of large numbers and other means are used to discover this issue.

Results firstly show that the development of pores in the two directions (Angle between two directions is 90 degrees or approximately 90 degrees) are complementary and promote each other. Reversely, the data points begin to be scattered, which means that the development of the pore in the above two directions begins to “lose stability”, rather than promote each other all the time. This

could prove that the rectangle (width, height), Legendre ellipse (major axis and major axis) and maximum and minimum Feret diameter of pores can all be used as the effective criteria for the development of pore shape related to brittle minerals. Sufficient evidences could prove that the pores related to brittle minerals contribute to oil and gas migration and oil & water imbibition.

The conclusion of this study will provide an important theoretical basis for clarifying the oil occurrence mechanism of shale oil reservoir and looking for the geological and engineering dessert from the microscopic viewpoint.

Shi, L.-D., Lv, P.-L., Wang, M., Lai, C.-Y., Zhao, H.-P., 2020. A mixed consortium of methanotrophic archaea and bacteria boosts methane-dependent selenate reduction. Science of The Total Environment 732, 139310.


Though methane-based selenate reduction has been reported, neither the selenate load nor the removal rate could satisfy practical applications, thus limiting this technique to bio-remediate selenate pollution. In the present study, using a membrane biofilm batch reactor (MBBR), we successfully enriched a consortium performing methane-dependent selenate reduction, with enhanced reduction rates from 16.1 to 28.9 μM-day−1 under a comparable Se concentration to industrial wastewaters (i.e., ~500 μM). During active reduction, 16S rRNA gene copies of Archaea and Bacteria were both increased more than one order of magnitude. Clone library construction and high-throughput sequencing indicated that Methanosarcina and Methylocystis were the only methane-oxidizing microorganisms. The presence of 20 mM bromoethanesulphonate or 0.15 mM acetylene both significantly, but not completely, inhibited methane-dependent selenate reduction, indicating the concurrent contributions of methanotrophic archaea and bacteria. Fluorescence in situ hybridization (FISH) revealed that archaea directly adhered to the surface of the membrane while bacteria were in the outer layer, together forming the mature biofilm. This study highlights the crucial role of both methanotrophic archaea and bacteria in methane-dependent selenate reduction, and lays foundations in applying methane to bio-remediate practical selenate pollution.

Shukla, Y., Sharma, M., 2020. Ediacaran discs from the Bhima Group, Karnataka, South India. Journal of the Geological Society of India 95, 483-490.

https://doi.org/10.1007/s12594-020-1465-5

Discs/discoidal body fossils, an important constituent of Ediacaran biota, are reported from the sandstone unit of the Hotpet Formation of the Bhima Group, South India. Nine specimens preserved as circular to ovate structures are described and attributed to Ediacaran discs and are akin to Fermeuse-style preservation of Ediacaran fossils. These discs, occur as impressions on the bedding planes, are referred as Charniodiscus-like fossils. This is the first report of Ediacaran discs from the Bhima Group, south India.



The concentration of nitrogen compounds in crude oils is relatively low, less than 2 wt %, but these compounds are detrimental to refining processes and the environment. In particular, they can form deposits, spoil fuels, and contribute to air pollution. They are potentially carcinogenic as well. Nitrogen compounds identified in refining processes come from the oil matrix, and it is desirable to know which nitrogen species are present in crude oil. However, the complexity of the crude oil makes it necessary to separate these compounds, and the conventional fractionation method is commonly used, albeit less efficiently in the separation of minority classes. Methods used to separate minority classes of nitrogen are time- and labor-intensive. We herein report a column chromatography separation method capable of separating minority classes, such as neutral and basic nitrogen compounds, using a silica gel modification with small quantities of crude oil (∼50 mg). The method showed good reproducibility in triplicate tests, using seven selected oils with API gravity ranging from 14.8 to 34.4. By modifying the silica gel with boric acid, aromatic nitrogen compounds were isolated and analyzed by a comprehensive two-dimensional gas chromatography (GC×GC-qMS) and Fourier transform ion cyclotronic resonance mass spectrometry (FT-ICR MS). More saturated fractions were retained in the unmodified silica gel, while modified silica gel retained more aromatic and polar fractions. Carbazole and pyridine homologous series were fully separated and identified, obtaining high-quality mass spectra for the compounds under study.



The first step in calcium naphthenate deposition is supposed to be the formation of an interfacial gel by cross-linking between ARN tetrameric acid and Ca2+. Several aspects of the inhibition of the interfacial gel formation by asphaltenes are studied by sessile drop tensiometry fitted with a special device allowing a continuous exchange of the droplet subphase to simulate the dynamic conditions due to the flow of oil in crude oil-processing facilities. First experiments were performed by exchanging simultaneously ARN and asphaltenes. Interfacial tensions and interfacial dilational moduli have shown that asphaltenes prevent the formation of interfacial ARN gel. The interface is composed mostly of asphaltenes with a small proportion of non-cross-linked ARN. The influence of different parameters (pH, asphaltene concentration, exchange time, asphaltene solvency) was tested, and they are not found to significantly alter the conclusions. The inhibition of interfacial gel formation is most likely due to bulk interactions between ARN and asphaltenes and not to interfacial competition since ARN is more surface active than asphaltenes. The interfacial concentration of ARN is critical for the cross-linking with Ca2+. Furthermore, asphaltenes were exchanged in droplet bulk subphase after the formation of ARN/Ca2+ interfacial gel. A significant part of the interfacial gel seems to be desorbed or dispersed by asphaltenes, especially during the initial moments of the exchange. In conclusion, this study shows how important asphaltenes are in the calcium naphthenate deposition mechanism.

Siraj, A., Loeb, A., 2020. Exporting terrestrial life out of the Solar System with gravitational slingshots of Earthgrazing bodies. International Journal of Astrobiology 19, 260-263.

https://doi.org/10.1017/S1473550419000314

Exporting terrestrial life out of the Solar System requires a process that both embeds microbes in boulders and ejects those boulders out of the Solar System. We explore the possibility that Earthgrazing long-period comets (LPCs) and interstellar objects (ISOs) could export life from Earth by collecting microbes from the atmosphere and receiving a gravitational slingshot effect from the Earth. We estimate the total number of exportation events over the lifetime of the Earth to be ~1–10 for LPCs and ~1–50 for ISOs. If life existed above an altitude of 100 km, then the number is dramatically increased up to ~105 exportation events over Earth's lifetime.

Sitterley, K.A., Linden, K.G., Ferrer, I., Thurman, E.M., 2020. Desalting and concentration of common hydraulic fracturing fluid additives and their metabolites with solid-phase extraction. Journal of Chromatography A 1622, 461094.


This work describes the development of a solid-phase extraction method capable of detecting common fracturing fluid additives in flowback and produced water with mass spectrometry. Dissolved organic carbon (DOC) was used as a bulk measurement to investigate the retentive capacity of seven sorbents and to determine a loading volume. Conductivity was used to determine rinse volume. Based on this, four sorbents (HLB, PPL, Carbon, and C-18) were selected for further investigation of their ability to recover common fluid additives. Enrichment factors were calculated for poly(ethylene) glycols (PEGs), PEG-amines, and their metabolites PEG-carboxylates and PEG-carboxylate-amines, poly(propylene) glycols (PPGs), and linear alkyl ethoxylates (LAEs). The sorbent HLB gave the greatest enrichment for all of these compounds, with an average of 8.0× for PEGs, 11.9× for PEG-amines, 4.9× for PEG-carboxylates, and 21.6× for LAEs, though enrichment was highly dependent on sample composition. The effect was more pronounced for higher molecular weight compounds and enabled detection of some compounds in saltier samples. Then, HLB was used to recover these additives from 1:200 and 1:1000 dilutions in groundwater, illustrating the ability of solid-phase extraction to detect these compounds at low levels (<100 ppb) and highlighting the utility of desalting. This method was used to identify ethoxylated amines in flowback and produced waters from across the country.

Smirnov, M.B., Borisov, R.S., Vanyukova, N.A., 2020. A new reaction involved in forming the composition of oils: Methylation of aromatic cycles. Geochemistry International 58, 520-530.

https://doi.org/10.1134/S0016702920050092

One of the processes that can locally be involved in forming the composition of aromatic hydrocarbons in oils is the reaction of electrophilic methylation of aromatic cycles. Up to 40% of the original oil compounds can be transformed into methylation products. Methylation is demonstrated to most likely proceed during catagenesis, after the generation of the fluid that had produced a given oil accumulation. The methylation of aromatic cycles is a definite indicator that the source rocks are either clays or silicites containing relatively much clay material. The methylation reaction is proved not to be widespread even within a given basin, and hence, analysis for the presence of electrophilic methylation products can be efficiently applied in geochemical reconstructions. One of the consequences of methylation may be changes in the concentrations of isomers of aromatic

compounds that are used in calculating maturity coefficients, and this may lead to misinterpretations of the results.

Smirnov, M.B., Brodskii, E.S., Vanyukova, N.A., 2020. A new type of aromatic petroleum hydrocarbons: Phenyl-substituted tri- and tetracycloaromatics. Petroleum Chemistry 60, 270-277.

https://doi.org/10.1134/S0965544120030202

Analysis of the composition of crude oils from four oil and gas basins by gas chromatography–mass spectrometry has shown that aromatic compounds bearing a phenyl substituent are as typical of oils as the well-known phenanthrenes and chrysenes. Thus, biphenyls are the first member of the series of compounds of this structural type. Unsubstituted and alkyl substituted phenylnaphthalenes, terphenyls, phenylphenanthrenes, and naphthylnaphthalenes have been identified; the smallest set of components of this type (only phenylnaphthalenes) is in Volga–Urals oils. Unlike the case of dispersed organic matter (OM), the main components in oils are alkyl substituted compounds, which can have as long substituents as C10 alkyls in some cases. The proportion of unsubstituted compounds is small. In all the oils, thermodynamically more stable isomers predominate. The phenylnaphthalene content is close to the content of chrysenes, the proportion of which is about an order of magnitude lower than that of phenanthrenes. In one of the samples, phenylnaphthalenes are about in the same amount as phenanthrenes. The total concentration of terphenyls, phenylphenanthrenes, and naphthylnaphthalenes is usually much lower than the concentration of phenylnaphthalenes. To date, the use of phenyl substituted aromatic compounds in geochemistry has been limited to oil–oil and oil–OM correlations. Studying compounds of this type is important both for more detailed characterization of the composition of aromatic compounds of crude oil and for understanding the processes of oil generation in different environments.



Thermal stress on the biosphere during the extreme warmth of the Paleocene-Eocene Thermal Maximum (PETM) was most severe at low latitudes, with sea surface temperatures at some localities exceeding the 35 °C at which marine organisms experience heat stress. Relatively few equivalent terrestrial sections have been identified, and the response of land plants to this extreme heat is still poorly understood. Here, we present a new PETM record from the peak ring of the Chicxulub impact crater that has been identified based on nannofossil biostratigraphy, an acme of the dinoflagellate genus Apectodinium, and a negative carbon isotope excursion. Geochemical and microfossil proxies show that the PETM is marked by elevated TEX86H-based sea surface temperatures (SSTs) averaging ~37.8 °C, an increase in terrestrial input, surface productivity, salinity stratification, and bottom water anoxia, with biomarkers for green and purple sulfur bacteria indicative of photic zone euxinia in the early part of the event. Pollen and plants spores in this core provide the first PETM floral assemblage described from México, Central America, and the northern Caribbean. The source area was a diverse coastal shrubby tropical forest, with a remarkably high

abundance of fungal spores indicating humid conditions. Thus, while seafloor anoxia devastated the benthic marine biota, and dinoflagellate assemblages were heat-stressed, the terrestrial plant ecosystem thrived.

Sobecki, N., Wang, S., Ding, D.Y., Nieto-Draghi, C., Wu, Y.-S., 2020. A multi-scale modeling of confined fluid: From nanopore to unconventional reservoir simulation. Journal of Petroleum Science and Engineering 193, 107364.


Tight oil and shale gas reservoirs have a significant part of their pore volume occupied by micro (below 2 nm) and mesopores (between 2 and 50 nm). This kind of environment creates strong interaction forces in the confined fluid with pore walls and then changes dramatically the fluid phase behavior. An important work has therefore to be done on thermodynamic modeling of the confined fluid and on developing upscaling methodology of the pore size distribution for large scale reservoir simulations. Firstly, the comparison between molecular simulation results and commonly used modified equation of state (EOS) in the literature highlighted the model of flash with capillary pressure and critical temperature and pressure shift as the best one to model confined fluid behavior. Then, fine grid matrix/fracture simulations have been built and performed for different pore size distributions. The study has shown that the pore size distribution has an important impact on reservoir production and this impact is highly dependent on the volume fraction of nanopores inside the matrix. Afterwards, coarse grid upscaling models have then been performed on the same synthetic case and compared to the reference fine grid results. The commonly used upscaling methodology of dual porosity model with average pore radius for the pore size distribution is unable to match the fine grid results. A new triple porosity model considering fracture, small pores and large pores with their own capillary pressure and EOS, together with MINC (Multiple Interacting Continua) approach, has shown very good agreement with the reference fine grid results. Finally a large scale stimulated reservoir volume with different pore size distribution inside the matrix has been built using the upscaling method developed here.

Soltani Hosseini, M., Chartrand, P., 2020. Thermodynamics and phase relationship of carbonaceous mesophase appearing during coal tar pitch carbonization. Fuel 275, 117899.


Carbonaceous mesophase appears as an intermediate product in production of electrical and mechanical carbon materials, needle coke for graphite electrodes used in electric-arc furnaces, pitch-based fibers and aluminum-smelting prebaked electrodes through carbonization process. A thermodynamic approach for phase behavior estimation of carbonaceous mesophase is presented to provide more insights and to lead to semi-quantitative modeling of this process. Phase behavior of binary, ternary and multi-component systems are described by minimization of the Gibbs free energy function proposed by Hu and Hurt for mesophase pitches which exhibits orientational energy contribution of molecules in mesophase. The model enables estimating the reversible phase transition of mesophase upon temperature cycling as suggested by Lewis. The capability of the model to estimate the molecular weight distribution of species in the phases in equilibrium and variation of mesophase content with thermal soaking time has been discussed. Estimated ternary isothermal sections showing isotropic-mesophase and iso-iso immiscibility are presented for the first

time. The phase behavior of ternary systems with average molecular weight in the range of average molecular weight of coal tar pitches are described. The application of the model to phase diagram prediction of the specific systems which exhibit the miscibility gap has been studied.

Song, Y., Sung, W., Jang, Y., Jung, W., 2020. Application of an artificial neural network in predicting the effectiveness of trapping mechanisms on CO2 sequestration in saline aquifers. International Journal of Greenhouse Gas Control 98, 103042.


Predicting the effectiveness of geological CO2 storage and evaluating the field application of successful CO2 sequestration require a large number of case studies. These case studies that incorporate geologic, petrophysical, and reservoir characteristics can be achieved with an artificial neural network. We created an artificial neural network model for geological CO2 sequestration in saline aquifers (ANN-GCS). To train and test the ANN-GCS model, data of residual and solubility trapping indices were generated from a synthetic aquifer. Training and testing were conducted using Python with Keras, where the best iteration and regression were considered based on the calculated coefficient of determination (R2) and root mean square error (RMSE) values. The architecture of the model consists of eight hidden layers with each layer of 64 nodes showing an R2 of 0.9847 and an RMSE of 0.0082. For practical application, model validation was performed using a field model of saline aquifers located in Pohang Basin, Korea. The model predicted the values, resulting in an R2 of 0.9933 and an RMSE of 0.0197 for RTI and an R2 of 0.9442 and an RMSE of 0.0113 for STI. The model was applied successfully to solve a large number of case studies, predict trapping mechanisms, and optimize relationships between physical parameters of formation characteristics and storage efficiency. We propose that the ANN-GCS model is a useful tool to predict the storage effectiveness and to evaluate the successful CO2 sequestration. Our model may be a solution to works, where conventional simulations may not provide successful solutions.

Song, Z., Song, Y., Li, Y., Bai, B., Song, K., Hou, J., 2020. A critical review of CO2 enhanced oil recovery in tight oil reservoirs of North America and China. Fuel 276, 118006.


Primary oil recovery remains less than 10% in tight oil reservoirs, even after expensive multistage horizontal well hydraulic fracturing stimulation. Substantial experiments and simulation works have been performed to investigate CO2 enhanced oil recovery (CO2-EOR) potential in tight reservoirs; however, some results conflict with each other. The objectives of this paper are to fully understand the CO2-EOR mechanisms and to figure out the difference between tight oil exploitation in North America and China through a comprehensive literature review. It is shown that compared with Bakken and Eagle Ford formation, China’s tight oil reservoirs feature higher mud content and oil viscosity while they have a lower brittleness index of rock and formation pressure coefficient, leading to confined stimulated reservoir volume and further limited CO2-oil contact. The effect of CO2 molecular diffusion is relatively exaggerated in experimental results, which can be attributed to the dual restrictions of exposure time and oil-CO2 area in field scale. Numerical simulation works show that the shifted phase properties in nanopores lead to an oil recovery increment. The development of nano-scale chips withholding high pressure/temperature may advance the experimental study on the nanopore confinement effect. CO2-fluid-rock minerals interaction might

be more complex due to the large specific surface area of nanopores in tight formations. The geomechanics coupling effect cannot be ignored when examining the CO2-EOR performance in tight reservoirs. And a comprehensive simulation study coupling with technical and economic feasibility is highly recommended before running a field test of CO2-EOR.

Sowiżdżał, K., Słoczyński, T., Kaczmarczyk, W., 2020. Estimation of the oil-in-place resources in the liquid-rich shale formations exploiting geochemical and petrophysical data in a 3D high-resolution geological model domain: Baltic basin case study. Geofluids 2020, 5385932.

https://doi.org/10.1155/2020/5385932

The paper discusses the issue of oil-in-place estimation for liquid-saturated shales in Lower Paleozoic (Silurian and Ordovician) organic-rich formations of the Baltic Basin in North Poland. The authors adopted a geochemical method based on Rock Eval results which directly measure hydrocarbon content present in rock samples. Its application on a real data set required the implementation of correction procedures to consider also those oil compounds which were lost before Rock Eval measurements were taken or are not recorded in parameter. It was accomplished through the introduction of two correction coefficients: —for evaporation loss and —for heavier compounds underestimation. The first one was approximated on the basis of published results and known properties of crude oil, while the second one was addressed with laboratory experimental procedure which combines Rock Eval pyrolysis and rock sample extraction with organic solvents. The calculation formulas were implemented in the 3D geological model of shale formations reproducing their geometry as well as the spatial variability of the petrophysical and geochemical properties. Consequently, the results of oil-in-place estimation were also available as 3D models, ready for visualization and interpretation in terms of delineation of most favorable zones or well placement. The adopted geochemical method and the results of oil-in-place estimation it produced were confronted with standard volumetric method. Although both of them are volumetric methods, the results depend on different sets of rock properties, which is an advantage for result comparison reasons. The study revealed that the geochemical method of oil-in-place estimation in liquid-rich shales after appropriate adjustment, considering shale formation and reservoir fluid dependent conditions, could provide reliable results and be implemented on the early stage of shale exploration process in a condition of production data inaccessibility.



Geobiologists attempt to answer such questions as: when and under what conditions did life begin, how can we verify biogenicity in the geologic record, and what governs the relation between the living world and the mineral world? Raman spectroscopy can characterize and identify both organic and inorganic phases, typically nondestructively, at the (sub-)micrometer scale and, thereby, can provide key information to tackle these questions. This article illustrates contributions that Raman spectroscopy has made to understanding mineralization processes in mollusks, corals, and bones. Raman spectroscopy can also be used in the search for earliest terrestrial life and life on other planets. Some challenges for the three Raman instruments to be deployed on Mars are discussed.

Stockhausen, M., Galimberti, R., Elias, R., Di Paolo, L., Schwark, L., 2020. The Expulsinator versus conventional pyrolysis: The differences of oil/gas generation and expulsion simulation under near-natural conditions. Marine and Petroleum Geology 117, 104412.


The Expulsinator provides a new technique to simulate generation and expulsion of hydrocarbons under near-natural conditions. This is realized by application of lithostatic pressure onto an intact source rock disc with undisturbed mineral matrix and kerogen network and by hydrous pyrolysis, conducted in open flow-through mode. Conventional pyrolysis methodologies serve well in generation kinetics assessment but are only of limited use for investigation of primary migration and expulsion due to destructive sample preparation, inappropriate pressure regimes and pyrolysis in closed mode and/or in the absence of water. However, comparison of results generated with conventional pyrolysis with Expulsinator experiments is important to assess the performance of the generation and expulsion simulation carried out with the Expulsinator. Thus, the generation and expulsion behaviour of this new methodology has been compared with established pyrolysis methodologies, like HyPy and closed small vessel pyrolysis (CSVP) and has been assessed by Rock Eval pyrolysis. Expulsinator experiments released higher amounts of bitumen than CSVP. This has been attributed to increased cross-linking reactions of bitumen in case of the classic pyrolysis, favouring formation of pyrobitumen. Differences in yields and composition of n-alkanes were controlled not by generation (kinetics) exclusively but also by expulsion effects, in particular delayed expulsion caused by geochromatography. Expulsinator conversion rates of TOC exceeded 81%, whereas those of hydrous CSVP remained at 65%. Higher Expulsinator TOC conversion was accompanied by lower gas generation compared to CSVP. This is attributed to the open setup of the expulsion experiment, which by rapid removal of products generated prevents their secondary alteration, particularly polymerization to pyrobitumen and oil to gas cracking at higher temperatures. HyPy of Expulsinator pyrolysis residues verified a low generation potential remaining after the expulsion experiment. The Expulsinator-device delivers oil and gas generation data, which can be applied in numerical modelling exercises.

Stojanovski, D., Roffet-Salque, M., Casanova, E., Knowles, T., Oosterbeek, L., Evershed, R.P., Cruz, A., Thissen, L., Arzarello, M., 2020. Anta 1 de Val da Laje – the first direct view of diet, dairying practice and socio-economic aspects of pottery use in the final Neolithic of central Portugal. Quaternary International 542, 1-8.


This article presents the results of the first dedicated study of organic residues in Portugal, extracted from pottery excavated from Anta 1 de Val da Laje passage grave. We fully exploit the organic residue extract, to obtain information regarding the diet of the people and their relationship with the environment, the socio-economic aspects of an otherwise elusive society, and we also used a new methodology to obtain direct absolute dates for the pottery, the residue extract being the only datable organic material from the site. Our results suggest a community with diet based on terrestrial resources, that was fully benefitting from a range of domestic animals including their secondary products. We present the first direct evidence of not only meat consumption, but also milk and dairy production in Iberia. The compound-specific radiocarbon dating methodology, opens a door to possibilities for investigating otherwise poorly dated archaeological phenomena in the Iberian Peninsula.



We combine integrated fluid inclusion analysis, petrography, and burial-thermal-hydrocarbon generation history modeling, to delineate multiple generation-expulsion-charge episodes within the central and southern Biyang Sag, Nanxiang Basin, Eastern China. Basin models suggest the main phase of oil generation occurred between the late Eocene and early Miocene. This period generally corresponds to the three oil expulsion episodes (ca. 37.5 Ma, 33.1 Ma, and 23.0 Ma) recorded in petroleum inclusions that are hosted in fibrous calcite veins in organic-rich shales. Based on fluorescence spectrum parameters and the API gravities of a set of crude oils used as a calibration, the oils expelled during the three expulsion episodes were determined to have been heavy, black and light oils. Fluorescence correlations indicate that the three types of oil inclusions found in the source rocks correspond well with those detected in the reservoirs.

The first episode of heavy oil emplacement occurred prior to quartz overgrowth whereas the second episode of black oil emplacement was synchronous with quartz overgrowth. Ferrodolomite and ankerite cements were deposited, this being accompanied by a second phase of quartz grain overgrowth dissolution. The last episode of light oil emplacement was coincident with the precipitation of ankerite. By integrating fluid inclusion Th, burial-thermal models, and constraints from oil expulsion timing, the timings of the three episodes of oil charge were estimated to be 35.3 Ma, 31.9 Ma, and 20.8 Ma. Tectonic deformation related to horizontal compression facilitated trap formation; this is thought to be the reason behind the observation that only light oil related to the third charging episode accumulated in the reservoirs.



A systematic study into the origin and potential formation processes of condensates in the Pinghu Slope Belt of the Xihu Depression, East China Sea Basin, was conducted using fluid inclusion analysis, petroleum geochemistry, and rock gold-tube pyrolysis. Grains containing Oil Inclusions (GOI™) technique, well logging, and formation testing together indicate that the present-day gas condensate layer has evolved from a paleo-oil layer. Biomarkers from oil inclusions indicate that these paleo-oils were generated from coal measures at a moderate maturity level. Based on organic macerals, elemental ratios of kerogens, Rock-Eval pyrolysis, and results from gold-tube pyrolysis experiments, the coal measures are evaluated as source rocks prone to gas generation and capable of oil formation at moderate levels of maturity. This maturity level coincides with present-day condensate maturities determined from a series of molecular maturity ratios (vitrinite reflectance ~ 0.7–1.0% Ro). Biomarkers related to specific sources suggest that the condensates are also coal-derived. These observations suggest that the condensates are derived from secondary alteration

following paleo-oil accumulation, rather than being related to the thermal degradation of resin-rich organic matter at a low maturity level, or the thermal cracking of kerogen at a high maturity level.

Some condensates are characterized by a significant loss of n-alkanes with low carbon numbers and relatively high toluene/n-heptane (Tol/nC7) ratios. This indicates that the paleo-oil reservoirs have been subjected to varying degrees of gas washing, which resulted in condensate formation, as opposed to the process of oil cracking under high temperatures. Subsequent interactions between gas and paleo-oils resulted in oil inclusions showing fluorescence varying from near-yellow to blue. Variable vapor volume fractions measured in the same oil assemblage are the result of two-phase trapping of oil and gas. The widely observed presence of bitumen (asphaltene) in the reservoir pores and bitumen-bearing oil inclusions is considered to be due to gas deasphalting.

Homogenization temperatures (Th) of associated aqueous inclusions and burial-thermal curves suggest that the initial paleo-oil reservoirs formed in the late Miocene. Excess gas, composed of local mature gas and heterochthonous high-to over-mature gas, migrated into the paleo-oil reservoirs later, in the Quaternary. This process not only resulted in the formation of condensates, but also led to vertical differentiation of density and wax content in the reservoirs.

Su, P., Zhang, W., Hao, Y., Tomy, G.T., Yin, F., Chen, L., Ding, Y., Li, Y., Feng, D., 2020. Polycyclic aromatic hydrocarbon contaminations along shipping lanes and implications of seafarer exposure: Based on PAHs in ship surface films and a film-air-water fugacity model. Science of The Total Environment 731, 138943.


Polycyclic aromatic hydrocarbons (PAHs) are one of the most toxic compounds in ship tailpipe exhausts. The long-term contamination of PAHs along shipping lanes and ports is difficult to assess using conventional methods such as AIS-EFs-data based (AIS, Automatic identification system; EFs, emission factors) or field sampling methods. To address this, we collected the organic films on ship surfaces and used a modified film-air-water fugacity model to convert the film-bound concentrations to the airborne (gaseous plus particulate) concentrations. Not surprisingly, concentrations of PAHs on organic films on ship surfaces were greater than those measured on films on residential buildings. The airborne total PAH concentrations along shipping lanes in Yangtze River Delta area ranged from 63.3–325 ng m−3, which were in the same order of magnitude to those in Beijing during haze days. The incremental lifetime cancer risks by exposure to PAHs in ship indoor air were higher than the US EPA lower guideline, indicating considerable carcinogenic risks to seafarers. Our study proposes an alternative method to estimate the long-term contaminations of PAHs along shipping lanes and highlights a notable health risk to seafarers.

Subramanian, M., Marudhamuthu, M., 2020. Hitherto unknown terpene synthase organization in taxol-producing endophytic bacteria isolated from marine macroalgae. Current Microbiology 77, 918-923.

https://doi.org/10.1007/s00284-020-01878-8

Taxol is a successful anti-cancer drug, which extensively studied in Taxus spp. However, microbial endophytes also reported as taxol producers, and especially fungal endophytes extensively studied for the taxol biosynthesis pathway. Although it was well considered, the taxol biosynthesis pathway remains undisclosed since its discovery in bacteria. To decipher this gap, we isolated and identified

the endophytic bacteria such as Bacillus flexus strain DMTMMB08, Bacillus licheniformis strain DMTMMB10, and Oceanobacillus picturae strain DMTMMB24, which are unprecedented for taxol production. Subsequently, the genome annotation of these bacteria exhibited the isoprene biosynthesis pathway and terpene synthase profile. Feasibly, this is the very first report on taxol-producing endophytic bacteria from the non-Taxus host and solitary investigation on its genome analysis. The genomic insight into the bacterial system for taxol biosynthesis leads to understanding the terpene synthesis and evolution. This piece of work could expand our perception of the diversity of terpenes and their related natural products.

Sun, L., Alper, H.S., 2020. Non-conventional hosts for the production of fuels and chemicals. Current Opinion in Chemical Biology 59, 15-22.


Biotechnology offers a green alternative for the production of fuels and chemicals using microbes. Although traditional model hosts such as Escherichia coli and Saccharomyces cerevisiae have been widely studied and used, they may not be the best hosts for industrial application. In this review, we explore recent advances in the use of nonconventional hosts for the production of a variety of fuel, cosmetics, perfumes, food, and pharmaceuticals. Specifically, we highlight twenty-seven popular molecules with a special focus on recent progress and metabolic engineering strategies to enable improved production of fuels and chemicals. These examples demonstrate the promise of nonconventional host engineering.

Sun, T., Luo, X., Qing, H., Kou, X., Sheng, Z., Xu, G., Zuo, Y., 2020. Characteristics and natural gas origin of Middle–Late Triassic marine source rocks of the western Sichuan depression, SW China. Acta Geologica Sinica - English Edition 94, 376-398.

https://doi.org/10.1111/1755-6724.14341

A scientific exploration well (CK1) was drilled to expand the oil/gas production in the western Sichuan depression, SW, China. Seventy three core samples and four natural gas samples from the ‐Middle–Late Triassic strata were analyzed to determine the paleo depositional setting and the ‐abundance of organic matter (OM) and to evaluate the hydrocarbon generation process and ‐potential. This information was then used to identify the origin of the natural gas. The OM is characterized by medium n alkanes (nC‐ 15–nC19), low pristane/phytane and terrigenous aquatic ratios (TAR), a carbon preference index (CPI) of ∼1, regular steranes with C29 > C27 > C28, gammacerane/C30hopane ratios of 0.15–0.32, and δDorg of −132‰ to −58‰, suggesting a marine algal/phytoplankton source with terrestrial input deposited in a reducing–transitional saline/marine sedimentary environment. Based on the TOC, HI index, and chloroform bitumen “A,” the algal rich ‐dolomites of the Leikoupo Formation are fair–good source rocks; the grey limestones of the Maantang Formation are fair source rocks; and the shales of the Xiaotangzi Formation are moderately good source rocks. In addition, maceral and carbon isotopes indicate that the kerogen of the Leikoupo and Maantang formations is type II and that of the Xiaotangzi Formation is type II–III. The maturity parameters and the hopane and sterane isomerization suggest that the OM was advanced mature and produced wet–dry gases. One dimensional modeling of the thermal burial ‐ ‐history suggests that hydrocarbon generation occurred at 220–60 Ma. The gas components and C–‐H–He–Ar–Ne isotopes indicate that the oil associated gases were generated in the Leikoupo and ‐

Maantang formations, and then, they mixed with gases from the Xiaotangzi Formation, which were probably contributed by the underlying Permian marine source rocks. Therefore, the deeply buried ‐Middle–Late Triassic marine source rocks in the western Sichuan depression and in similar basins have a great significant hydrocarbon potential.

Sun, W., Zhang, E., Chang, J., Shulmeister, J., Bird, M.I., Zhao, C., Jiang, Q., Shen, J., 2020. Archaeal lipid-inferred paleohydrology and paleotemperature of Lake Chenghai during the Pleistocene–Holocene transition. Climate of the Past 16, 833-845.

https://www.clim-past.net/16/833/2020/

Over the past decades, paleoenvironmental studies in the Indian summer monsoon region have mainly focused on precipitation change, with few published terrestrial temperature records from the region. We analysed the distribution of isoprenoid glycerol dialkyl glycerol tetraethers (isoGDGTs) in the sediments of Lake Chenghai in southwest China across the Pleistocene–Holocene transition, to extract both regional hydrological and temperature signals for this important transition period. The lake level was reconstructed from the relative abundance of crenarchaeol in isoGDGTs (%cren) and the crenarchaeol /crenarchaeol ratio. The %cren-inferred lake level identified a single ′lowstand (15.4–14.4 ka cal BP), while the crenarchaeol /crenarchaeol ratio suggests a relatively ′lower lake level between 15.4–14.4 and 12.5–11.7 ka cal BP, corresponding to periods of weakened ISM during the Heinrich 1 and Younger Dryas cold event. A filtered TetraEther indeX consisting of 86 carbon atoms (TEX86 index) revealed that lake surface temperature was similar to present-day values during the last deglacial period and suggests a substantial warming of ∼4 ∘C from the early Holocene to the mid-Holocene. Our paleotemperature record is generally consistent with other records in southwest China, suggesting that the distribution of isoGDGTs in Lake Chenghai sediments has potential for quantitative paleotemperature reconstruction.



The Lower Cambrian Niutitang Formation is one of the most important shale reservoirs in the Northern Guizhou. To study the characteristics of pore structures and the relationships between shale's physical properties and pore structures in the complex tectonic area, from the perspective of hydrocarbon generation and evolution, the mineral composition, pore structure characteristics of shale samples in northern Guizhou were analyzed using X-ray diffraction (XRD), optical microscopic composition analysis, focused ion beam-scanning electron microscopy (FIB-SEM), vitrinite reflectivity and nitrogen adsorption experiments. Results indicate that the pore structures can be categorized into conical, ink bottle, spherical, elliptical, beaded, irregular, and plate-like intersecting microfractures. Shale samples are organic-rich with an average total organic carbon content of 4.39%. Organic matter is consumed within the shale matrix during the hydrocarbon generation and evolution, which increases the organic pore size and the proportion of organic pores. The high TOC content is conducive to developing organic pores. In addition, the average content of brittle minerals is greater than 70%. High content of brittle minerals during diagenesis is conducive to

developing the residual pores at the edges of mineral particles and dissolved pores within mineral particles. Thus, the high content of brittle minerals and TOC content is favorable for the development of meso-macropores. The content of clay minerals within the shale samples ranges from 6.3% to 42.2%, with an average of 20.02%. Micropores and mesopores mainly occur in the clay minerals. Pores in clay minerals are easily compacted under tectonic stress. Meanwhile, high thermal evolution degree and the vitrinite reflectance Ro greater than 3.5 is not conducive to developing pores. Hence, high TOC content, high brittle minerals content, and thermal evolution degree ranging from 0.6% to 3% make the Lower Cambrian Niutitang Formation shale reservoirs favorable for shale gas exploration.

Sun, X., Kong, T., Häggblom, M.M., Kolton, M., Li, F., Dong, Y., Huang, Y., Li, B., Sun, W., 2020. Chemolithoautotropic diazotrophy dominates the nitrogen fixation process in mine tailings. Environmental Science & Technology 54, 6082-6093.


Nutrient deficiency, especially bio-available nitrogen deficiency, often impedes the bioremediation efforts of mining generated tailings. Biological nitrogen fixation is a critical process necessary for the initial nitrogen buildup in tailings. Current knowledge regarding the diazotrophs that inhabit tailings is still in its infancy. Therefore, in this study, a comprehensive investigation combining geochemical characterization, sequence analyses, molecular techniques, and activity measurements was conducted to characterize the diazotrophic community residing in tailing environments. Significant differences between tailings and their adjacent soils in prokaryotic and diazotrophic communities were detected. Meanwhile, strong and significant correlations between the absolute abundance of the nitrogen fixation (nifH), carbon fixation (cbbL), sulfur oxidation (soxB), and arsenite oxidation (aioA) genes were observed in the tailings but not in the soils. The reconstructed nif-containing metagenome-assembled genomes (MAGs) suggest that the carbon fixation and sulfur oxidation pathways were important for potential diazotrophs inhabiting the tailings. Activity measurements further confirmed that diazotrophs inhabiting tailings preferentially use inorganic electron donors (e.g., elemental sulfur) compared to organic electron donors (e.g., sucrose), while diazotrophs inhabiting soils preferred organic carbon sources. Collectively, these findings suggest that chemolithoautotrophic diazotrophs may play essential roles in acquiring nutrients and facilitating ecological succession in tailings.

Sun, Y., Teng, F.-Z., Hu, Y., Chen, X.-Y., Pang, K.-N., 2020. Tracing subducted oceanic slabs in the mantle by using potassium isotopes. Geochimica et Cosmochimica Acta 278, 353-360.


Substantial quantities of oceanic slabs are known to be recycled into the mantle through subduction. However, tracing their fate in the mantle through studies of mantle-derived samples is not always straightforward. As K represents an omnipresent element in subducting crustal materials, its two stable isotopes (39K and 41K) display outstanding potential in tracing recycled crustal materials in the mantle. Here we report the first set of K isotopic data for a suite of well-characterized continental basaltic lavas from Northeast China. The δ41K of these lavas exhibit large variation from −0.81‰ to −0.15‰, compared with the narrow range of unaltered oceanic basalts (−0.43 ± 0.03‰). The isotopic variations, together with geochemical data obtained in earlier studies, cannot be

ascribed to chemical weathering, crystal fractionation, crustal contamination, or partial melting, but are consistent with the presence of diverse crustal materials in magma sources. Recycled oceanic crust and sediments both have contributed to the contrasting K isotopic signature observed in these lavas. Our study here highlights the potential of using K isotopes to trace different types of recycled crustal materials in the mantle and places new constraints on the generation of enriched mantle reservoirs.

Super, J.R., Thomas, E., Pagani, M., Huber, M., O'Brien, C.L., Hull, P.M., 2020. Miocene evolution of North Atlantic Sea surface temperature. Paleoceanography and Paleoclimatology 35, e2019PA003748.

https://doi.org/10.1029/2019PA003748

We reconstruct sea surface temperatures (SSTs) at Deep Sea Drilling Project Site 608 (42.836°N, 23.087°), north of the Azores Front, and Ocean Drilling Program Site 982 (57.516°N, 15.866°), under the North Atlantic Current, in order to track Miocene (23.1–5.3 Ma) development of North Atlantic surface waters. Mean annual SSTs from TEX86 and UK 37′ proxy estimates at both sites were 10–15 °C higher than modern through the Miocene Climatic Optimum (17–14.5 Ma). During the global cooling of the Middle Miocene Climate Transition (~14.5–12.5 Ma), SSTs at midlatitude Site 608 cooled by ~6 °C, whereas high latitude Site 982 cooled by only ~2 °C, resulting in an ~4 Myr collapse of the SST ‐gradient between the two sites. This regional pattern is inconsistent with an increased latitudinal surface temperature gradient, as generally associated with global cooling episodes linked to decreasing p CO2 levels. Instead, the pattern is best explained by enhanced ocean heat transport into the high latitude North Atlantic superimposed on the global cooling trend, probably due to ‐enhanced Atlantic meridional overturning circulation and/or a stronger North Atlantic Current. During global late Miocene cooling (~8–7 Ma), surface waters cooled by ~6 °C at Site 982 while minimal change occurred at Site 608, reestablishing the North Atlantic SST gradient. The collapse and reemergence of the SST gradient between the middle and high latitude North Atlantic suggests‐ ‐ that interaction between changes in regional ocean circulation and the global response to changes in greenhouse gas concentration was important in Miocene climate evolution.



Three modes will improve the interaction of the wax-asphaltene molecules that eventually increase wax appearance temperature (WAT) within crude oil. The first mode takes place when the wax is composed of long-chain alkanes, and its aromatic compounds are low, and adjacent hydrogens in its constituent aromatic rings are substituted with long-chain paraffin. The second condition is when the wax is formed from low carbon number alkanes. In this case, the lower the asphaltene aromaticity and the carbon number of side alkyl chain, the higher its interaction with wax would be. The third approach occurs if naphthenic or aromatic structures exist in wax, and asphaltene aromatic rings are arranged as peri-condenses. Higher interaction of wax and asphaltene reduces wax crystals’ size. The presence of polar compounds in the molecular structure of the wax and

asphaltene does not affect WAT, but the size and morphology of crystals alter in microscopic images.

Takata, T., Jiang, J., Sakata, Y., Nakabayashi, M., Shibata, N., Nandal, V., Seki, K., Hisatomi, T., Domen, K., 2020. Photocatalytic water splitting with a quantum efficiency of almost unity. Nature 581, 411-414.

https://doi.org/10.1038/s41586-020-2278-9

Overall water splitting, evolving hydrogen and oxygen in a 2:1 stoichiometric ratio, using particulate photocatalysts is a potential means of achieving scalable and economically viable solar hydrogen production. To obtain high solar energy conversion efficiency, the quantum efficiency of the photocatalytic reaction must be increased over a wide range of wavelengths and semiconductors with narrow bandgaps need to be designed. However, the quantum efficiency associated with overall water splitting using existing photocatalysts is typically lower than ten per cent. Thus, whether a particulate photocatalyst can enable a quantum efficiency of 100 per cent for the greatly endergonic water-splitting reaction remains an open question. Here we demonstrate overall water splitting at an external quantum efficiency of up to 96 per cent at wavelengths between 350 and 360 nanometres, which is equivalent to an internal quantum efficiency of almost unity, using a modified aluminium-doped strontium titanate (SrTiO3:Al) photocatalyst. By selectively photodepositing the cocatalysts Rh/Cr2O3 and CoOOH for the hydrogen and oxygen evolution reactions, respectively, on different crystal facets of the semiconductor particles using anisotropic charge transport, the hydrogen and oxygen evolution reactions could be promoted separately. This enabled multiple consecutive forward charge transfers without backward charge transfer, reaching the upper limit of quantum efficiency for overall water splitting. Our work demonstrates the feasibility of overall water splitting free from charge recombination losses and introduces an ideal cocatalyst/photocatalyst structure for efficient water splitting.



The lithospheric mantle beneath Archean cratons is conspicuously refractory and thick compared to younger continental lithosphere (Jordan, 1988, Boyd, 1989; Lee and Chin, 2014), but how such thick lithospheres formed is unclear. Using a large global geochemical database of Archean igneous crustal rocks overlying these thick cratonic roots, we show from Gd/Yb– and MnO/FeOT–SiO2 trends that crustal differentiation required continuous garnet fractionation. Today, these signatures are only found where crust is anomalously thick (60–70 km), as in the Northern and Central Andes and Southern Tibet. The widespread garnet signature in Archean igneous suites suggests that thickening occurred not only in the lithospheric mantle but also in the crust during continent formation in the late Archean. Building thick crust requires tectonic thickening or magmatic inflation rates that can compete against gravitational collapse through lower crustal flow, which would have been enhanced in the Archean when geotherms were hotter and crustal rocks weaker. We propose that Archean crust and mantle lithosphere formed by thickening over mantle downwelling sites with minimum strain rates on the order of 10−13–10−12 s−1, requiring mantle flow rates associated with late Archean crust formation to be 10–100 times faster than today.



Naphthalene (NAP), as a surrogate of intermediate-volatility organic compounds (IVOCs), has been proposed to be an important precursor of secondary organic aerosol (SOA). However, the relative contribution of its emission sources is still not explicit. This study firstly conducted the source apportionment of atmospheric NAP using a triple-isotope (δ13C, δ2H, and Δ14C) technique combined with a Bayesian model in the Beijing–Tianjin–Hebei (BTH) region of China. At the urban sites, stable carbon (−27.7 ± 0.7‰, δ13C) and radiocarbon (−944.0 ± 20.4‰, Δ14C) isotope compositions of NAP did not exhibit significant seasonal variation, but the deuterium system showed a relatively more 2H depleted signature in winter (−86.7 ± 8.9‰, δ2H) in comparison to that in summer (−56.4 ± 3.9‰, δ2H). Radiocarbon signatures indicated that 95.1 ± 1.8% of NAP was emitted from fossil sources in these cities. The Bayesian model results indicated that the emission source compositions in the BTH urban sites had a similar pattern. The contribution of liquid fossil combustion was highest (46.7 ± 2.6%), followed by coal high-temperature combustion (26.8 ± 7.1%), coal low-temperature combustion (18.9 ± 6.4%), and biomass burning (7.6 ± 3.1%). At the suburban site, the contribution of coal low-temperature combustion could reach 70.1 ± 6.4%. The triple-isotope based approach provides a top-down constraint on the sources of atmospheric NAP and could be further applied to other IVOCs in the ambient atmosphere.

Tao, C., Wang, Y., Li, Y., Ni, X., Gao, X., 2020. Adsorption mechanism and kinetic characterization of bituminous coal under high temperatures and pressures in the Linxing-Shenfu area. Acta Geologica Sinica - English Edition 94, 399-408.

https://doi.org/10.1111/1755-6724.14344

The majority of coalbed methane (CBM) in coal reservoirs is in adsorption states in coal matrix pores. To reveal the adsorption behavior of bituminous coal under high temperature and high‐ ‐pressure conditions and to discuss the microscopic control mechanism affecting the adsorption characteristics, isothermal adsorption experiments under high temperature and high pressure ‐ ‐conditions, low temperature liquid nitrogen adsorption desorption experiments and CO‐ ‐ 2 adsorption experiments were performed on coal samples. Results show that the adsorption capacity of coal is comprehensively controlled by the maximum vitrinite reflectance (Ro, max), as well as temperature and pressure conditions. As the vitrinite reflectance increases, the adsorption capacity of coal increases. At low pressures, the pressure has a significant effect on the positive effect of adsorption, but the effect of temperature is relatively weak. As the pressure increases, the effect of temperature on the negative effect of adsorption gradually becomes apparent, and the influence of pressure gradually decreases. Considering pore volumes of pores with diameters of 1.7–100 nm, the peak volume of pores with diameters 10–100 nm is higher than that from pores with diameters 1.7–10 nm, especially for pores with diameters of 40–60 nm, indicating that pores with diameters of 10–100 nm are the main contributors to the pore volume. The pore specific surface area shows multiple peaks, and the peak value appears for pore diameters of 2–3 nm, indicating that this pore diameter is the main contributor to the specific surface area. For pore diameters of 0.489–1.083 nm, the pore size distribution is bimodal, with peak values at 0.56–0.62 nm and 0.82–0.88 nm. The adsorption

capability of the coal reservoir depends on the development degree of the supermicroporous specific surface area, because the supermicroporous pores are the main contributors to the specific pore area. Additionally, the adsorption space increases as the adsorption equilibrium pressure increases. Under the same pressure, as the maximum vitrinite reflectance increases, the adsorption space increases. In addition, the cumulative reduction in the surface free energy increases as the maximum vitrinite reflectance increases. Furthermore, as the pressure increases, the surface free energy of each pressure point gradually decreases, indicating that as the pressure increases, it is increasingly difficult to adsorb methane molecules.

Tao, K., Cao, J., Wang, Y., Mi, J., Ma, W., Shi, C., 2020. Chemometric classification of crude oils in complex petroleum systems using t-distributed stochastic neighbor embedding machine learning algorithm. Energy & Fuels 34, 5884-5899.


The origin of crude oils is fundamental in the study of petroleum systems, but it encounters difficulties in complex systems because traditional geochemistry proxies are influenced by multiple factors (e.g., oil mixing, secondary alteration) and the interpretation of the data is challenging. To develop new potential approaches, a pilot study using the t-distributed stochastic neighbor embedding (t-SNE) machine learning algorithm was performed, based on a case study of the saline and alkaline lake petroleum systems in the lower Permian Mahu Sag, northwestern Junggar Basin, China. The algorithm revealed three main types of alkaline lacustrine related source rocks in the studied Fengcheng Formation: (i) argillaceous rocks deposited in brackish water and a weakly reducing environment; (ii) dolomitic mudstones deposited in saline water and a reducing environment; (iii) argillaceous dolomites deposited in hypersaline water and a strongly reducing environment. These organic facies are not time equivalent and vary temporally and spatially in the context of the alkaline lake evolution. Analysis of 43 crude oil samples showed that 5, 48, and 42% of the total number of samples were derived from argillaceous, dolomitic mudstone, and argillaceous dolomite source rocks, respectively, while the remaining 5% oil samples had a mixed origin from the former two end members. This suggests that hydrocarbon generation in the Fengcheng petroleum systems results mainly in large-scale oil generation from dolomitic source rocks. The biological precursors in the dolomitic rocks are dominated by haloduric algae, and the oil generation window is prolonged through organic–inorganic interactions during the hydrocarbon generation. This might be favorable for the preservation of an oil phase during deep burial and at high maturity. This represents a shale oil accumulation system in general as the source rocks and oils are the within the Fengcheng sequence. Our data suggest that the machine learning algorithm can find further application in this field with promising prospects.

Tao, R., Zhang, L., Zhang, L., 2020. Redox evolution of western Tianshan subduction zone and its effect on deep carbon cycle. Geoscience Frontiers 11, 915-924.


Knowing the phase relations of carbon-bearing phases at high-pressure (HP) and high-temperature (HT) condition is essential for understanding the deep carbon cycle in the subduction zones. In particular, the phase relation of carbon-bearing phases is also strongly influenced by redox condition of subduction zones, which is poorly explored. Here we summarized the phase relations of carbon-

bearing phases (calcite, aragonite, dolomite, magnesite, graphite, hydrocarbon) in HP metamorphic rocks (marble, metapelite, eclogite) from the Western Tianshan subduction zone and high-pressure experiments. During prograde progress of subduction, carbonates in altered oceanic crust change from Ca-carbonate (calcite) to Ca,Mg-carbonate (dolomite), then finally to Mg-carbonate (magnesite) via Mg–Ca cation exchange reaction between silicate and carbonate, while calcite in sedimentary calcareous ooze on oceanic crust directly transfers to high-pressure aragonite in marble or amorphous CaCO3 in subduction zones. Redox evolution also plays a significant effect on the carbon speciation in the Western Tianshan subduction zone. The prograde oxygen fugacity of the Western Tianshan subduction zone was constrained by mineral assemblage of garnet-omphacite from FMQ − 1.9 to FMQ − 2.5 at its metamorphic peak (maximum P-T) conditions. In comparison with redox conditions of other subduction zones, Western Tianshan has the lowest oxygen fugacity. Graphite and light hydrocarbon inclusions were ubiqutously identified in Western Tianshan HP metamorphic rocks and speculated to be formed from reduction of Fe-carbonate at low redox condition, which is also confirmed by high-pressure experimental simulation. Based on petrological observation and high-pressure simulation, a polarized redox model of reducing slab but oxidizing mantle wedge in subduction zone is proposed, and its effect on deep carbon cycle in subduction zones is further discussed.

Tasker, E.J., Ishimaru, K., Guttenberg, N., Foriel, J., 2020. Earth-Like: an education & outreach tool for exploring the diversity of planets like our own. International Journal of Astrobiology 19, 264-275.

https://doi.org/10.1017/S1473550419000326

Earth-Like is an interactive website and twitter bot that allows users to explore changes in the average global surface temperature of an Earth-like planet due to variations in the surface oceans and emerged land coverage, rate of volcanism (degassing) and the level of the received solar radiation. The temperature is calculated using a simple carbon–silicate cycle model to change the level of CO2 in the atmosphere based on the chosen parameters. The model can achieve a temperature range exceeding −100°C to 100°C by varying all three parameters, including freeze-thaw cycles for a planet with our present-day volcanism rate and emerged land fraction situated at the outer edge of the habitable zone. To increase engagement, the planet is visualized by using a neural network to render an animated globe, based on the calculated average surface temperature and chosen values for land fraction and volcanism. The website and bot can be found at earthlike.world and on twitter as @earthlikeworld. Initial feedback via a user survey suggested that Earth-Like is effective at demonstrating that minor changes in planetary properties can strongly impact the surface environment. The goal of the project is to increase understanding of the challenges we face in finding another habitable planet due to the likely diversity of conditions on rocky worlds within our Galaxy.

Tasker, T.L., Warner, N.R., Burgos, W.D., 2020. Geochemical and isotope analysis of produced water from the Utica/Point Pleasant Shale, Appalachian Basin. Environmental Science: Processes & Impacts 22, 1224-1232.

http://dx.doi.org/10.1039/D0EM00066C

While development of the Utica/Point Pleasant Shale (UPP) is extensive in Ohio (U.S.) and increasing in Pennsylvania and West Virginia, few studies report the chemistry of produced waters from UPP

wells. These data have important implications for developing best management practices for handling and waste disposal, or identifying the fluid in the event of accidental spill events. Here, we evaluated the elemental and isotope chemistry of UPP produced waters from 26 wells throughout Ohio, Pennsylvania, and West Virginia to determine any unique fluid chemistries that could be used for forensic studies. Compared to the Marcellus, UPP produced waters contain higher activities of total radium (226Ra + 228Ra) and higher 228Ra/226Ra ratios. As with the Marcellus Shale, elemental ratios (Sr/Ca) and isotope ratios (87Sr/86Sr) can distinguish UPP produced waters from many conventional oil and gas formations. Sr/Ca and 87Sr/86Sr ratios can fingerprint small fractions (∼0.1%) of UPP produced water in freshwater. However, because Marcellus and UPP produced waters display similar major elemental chemistry (i.e., Na, Ca, and Cl) and overlapping ratios of Sr/Ca and 87Sr/86Sr, 228Ra/226Ra ratios may be the best tracer to distinguish these waters.

Teece, B.L., George, S.C., Agbaje, O.B.A., Jacquet, S.M., Brock, G.A., 2020. Mars rover techniques and Lower/Middle Cambrian microbialites from South Australia: Construction, biofacies, and biogeochemistry. Astrobiology 20, 637-657.

https://doi.org/10.1089/ast.2019.2110

The Perseverance rover (Mars 2020) is equipped with an instrumental and analytical payload capable of identifying a broad range of organic molecules in geological samples. To determine the efficacy of these analytical techniques in recognizing important ecological and environmental signals in the rock record, this study utilized analogous equipment, including gas chromatography/mass spectrometry, Raman spectroscopy, X-ray fluorescence (XRF), Fourier transform infrared spectroscopy, along with macroscopic and petrographic observations, to examine early-middle Cambrian microbialites from the Arrowie Basin, South Australia. Morphological and petrographic observations of these carbonate successions reveal evidence of hypersaline-restricted environments. Microbialites have undergone moderate diagenesis, as supported by XRF data that show mineral assemblages, including celestine and the illitization of smectite. Raman spectral data, carbon preference indices of ∼1, and the methylphenanthrene index place the samples in the prehnite/pumpellyite metamorphic facies. Pristane and phytane are the only biomarkers that were detected in the least thermally mature samples. This research demonstrates a multitechnique approach that can yield significant geological, depositional, paleobiological, and diagenetic information that has important implications for planning future astrobiological exploration.



The increasing global demand for natural gas and petroleum byproducts is turning organic-rich shales into an important target for hydrocarbon exploration and production. Current understanding about hydrocarbon generation in unconventional plays, such as oil shales and gas shales, is still evolving, especially in sedimentary basins where hydrocarbon generation is influenced by magmatism. This is the case for the Permian oil shales of the Irati Formation in the Paraná Basin, southern South America. The Irati shales are considered an atypical petroleum system due to

thermal effects of the Paraná Large Igneous Province (LIP) emplaced during the Early Cretaceous. In this context, the focus of this study was to characterize the thermal conditions of hydrocarbon generation in the Irati Formation as well as the composition of related aqueous diagenetic fluids.

The kerogen from the Irati organic-rich shales has an aromaticity around 30% (ƒar ≈ 30%), as determined by carbon nuclear magnetic resonance (13C-NMR), and vitrinite reflectance (Ro) of around 0.6%. Fluid inclusions in calcite and quartz veins present aqueous fluids with salinity of 0–5 wt% of NaCl equivalent and homogenization temperatures greater than 250 °C. Hydrocarbon fluid inclusions were classified as black oil through their vapor fraction volumes (Fv = 1.6–9.1%) and homogenization temperatures (Th) in the 60–80 °C range. Methane (CH4) or carbon dioxide (CO2) fluid inclusions were absent within the analyzed calcite and quartz veins. The PVT model for trapped fluid inclusions suggests a shallow hydrocarbon petroleum system (≈2.5 km depth) active during the Early Cretaceous, synchronous with the Paraná LIP.

Teng, F.-Z., Hu, Y., Ma, J.-L., Wei, G.-J., Rudnick, R.L., 2020. Potassium isotope fractionation during continental weathering and implications for global K isotopic balance. Geochimica et Cosmochimica Acta 278, 261-271.


Potassium isotopic compositions of profiles through saprolites developed on a diabase in South Carolina, U.S.A., and on a granite in Guangdong, China, allow characterization of the behavior of K isotopes during continental weathering. Saprolites from the diabase profile are heavily weathered with chemical index of alteration (CIA) values up to 95; however, their K isotopic variation is limited, with δ41K ranging from −0.475 ± 0.028‰ in the unweathered diabase to −0.407 ± 0.021‰ for the saprolites. The lack of significant K isotope fractionation mainly reflects the conservative behavior of K in the diabase weathering profile, with >50% of the original K remaining in the saprolites. By contrast, K isotopes are fractionated during granite weathering and correlate with sample depth, CIA, and kaolinite abundance, with δ41K decreasing from −0.493 ± 0.030‰ in the unweathered granites at the bottom to −0.628 ± 0.021‰ in the most weathered saprolite close to the surface. These observations suggest the preference of light K isotopes in saprolites relative to fluids, which is further supported by the overall isotopically heavy nearby stream water samples (δ41K = −0.709 ± 0.017 to −0.339 ± 0.018‰). These results demonstrate that continental weathering plays an important role in the global K isotopic budget through the formation of isotopically heterogeneous rivers and weathered regolith. Recycling of K-rich crustal materials with distinct K isotopic signatures may produce distinct mantle K isotopic end members.

Teng, F.-Z., Lee, C.-T., Aulbach, S., Liu, X.-M., 2020. The continents: Origin, evolution, and interactions with other reservoirs. Geochimica et Cosmochimica Acta 278, 1-5.


Roberta L. Rudnick is a preeminent geochemist and world expert in studies of the continental crust, lithospheric mantle and non-traditional stable isotopes. For more than thirty years, she has made tremendous contributions to understanding the origin and evolution of the continents and their interactions with the atmosphere, hydrosphere, and the mantle through time using various cutting-edge techniques in petrology, mineralogy, and geochemistry. The impact of her research is reflected

in her highly-cited (∼30,000 times) scientific publications. The broader impact Roberta has on the geoscience community goes beyond her publications as she has been actively engaged in promoting international collaboration, mentoring next-generation geoscientists, and countless services to the community. Roberta has led and participated in over 60 national and international committees such as serving on the N.S.F. Advisory Committee for Geosciences, as the president of the Geochemical Society, and as the chair of the Arthur L. Day Prize and Lectureship Committee, N.A.S. She has also served as editor, editorial board member and associate editor for many journals, such as a 10-year position as an editor-in-chief of Chemical Geology, editor of “The Crust” volume for the “Treatise on Geochemistry” for both the 1st and 2nd edition, and as an associate editor of Annual Reviews of Earth and Planetary Sciences. Her accomplishments and contributions have been widely recognized by the community. Among her many honors and awards, Roberta is an elected member of the National Academy of Sciences, the American Academy of Arts and Sciences, and an elected foreign member of the Chinese Academy of Sciences. She is also an elected fellow of the American Association for the Advancement of Science, American Geophysical Union, European Association of Geochemistry, Geochemical Society, Geological Society of America, and Mineralogical Society of America. In addition, she has received the N. L. Bowen Award and Harry H. Hess Medal from the American Geophysical Union, and Dana Medal from the Mineralogical Society of America.

In recognition of her great achievements and to commemorate her sixtieth birthday, a special session titled “The continents: Origin, evolution, and interactions with other reservoirs” was held at the 28th Annual V. M. Goldschmidt Conference in Boston in 2018, organized by her former students and postdocs, Fang-Zhen Teng, Cin-Ty Lee, Sonja Aulbach and Xiao-Ming Liu. Over 80 abstracts were submitted to the session, representing colleagues, friends, and former students and postdocs from six continents. The 26 papers in this issue result from select presentations in the session. While this special issue is a tribute to Roberta’s accomplishments in crustal composition and evolution, mantle geochemistry, and non-traditional stable isotopes, her enormous contributions extend far beyond topics covered in this issue. For example, she, together with William F. McDonough and Ingo Horn, pioneered trace element analysis and U-Pb dating methods by laser ablation inductively-coupled plasma mass spectrometry (LA-ICPMS). Their classic paper “Precise elemental and isotope ratio determination by simultaneous solution nebulization and laser ablation-ICP-MS: application to U–Pb geochronology” has been cited nearly 600 times. Roberta also initiated the project of using ancient diamictite samples to trace the evolution of the continental crust, and more recently of the atmosphere, and has enthusiastically shared these samples with the community. Below, we highlight just some of Roberta’s achievements in her various fields of interest, and how the papers in this issue carry on from her early and enduring contributions.

1. The continental crust

To say that Roberta has a strong passion for understanding the composition and evolution of the continental crust, since her Ph.D. work on the composition of the deep crust, is more than a mild understatement. For example, her 2003 paper (with Shan Gao) “Composition of the continental crust” has been cited over 6000 times. Another publication (1995, with David Fountain) “Nature and composition of the continental crust: a lower crustal perspective” has been cited 3000 times. Her single-authored paper “Making continental crust”, also published in 1995, has been cited over 1000 times. The first group of papers in this collection focuses on this topic.

Studies on the temporal evolution of the chemical composition of the continental crust are the common theme of the first five papers. Tang et al. (2020) examine the Archean continental igneous database, documenting pervasive garnet fractionation throughout magmatic differentiation, which

indicates widespread synmagmatic orogenesis. To support magmatic orogens with thick crust in the Archean, mantle convection needed to be 1–2 orders of magnitude faster than today. Chen et al. (2020a) document secular variations of Cu concentrations and Cu/Ag ratios in ancient glacial diamictites, which suggests that the composition of the upper continental crust evolved from mafic at ∼3.0 Ga ago to felsic at ∼2.4 Ga ago, probably reflecting that global-scale plate tectonics initiated ∼3.0 Ga ago. By studying the same suite of samples, Li et al. (2020a) investigate the composition and mode of occurrence of sulfides and evaluate their contribution to the Mo budget in the upper continental crust. Their results indicate that sulfides are an insignificant host of Mo within the upper crust before the Great Oxidation Event (GOE), and that the release of Mo after the GOE is, thus, unlikely to reflect oxidative sulfide weathering. Mei et al. (2020) report W isotopic compositions for Archean intermediate to felsic rocks from the Slave, North China, and Kaapvaal cratons and find that the 4.0–3.8 Ga rocks have positive 182W anomalies, whereas the 3.55–2.95 Ga rocks have a uniform modern mantle-like W isotopic composition. The shift in μ182W values most likely reflects the transition of the tectonic regime from plume to plate tectonics at ∼3.6 Ga, which resulted in efficient mixing of early differentiated mantle and late accreted material. The last paper in this group applies numerical modelling to show that the thermal structure and mechanical stability of thick Archean oceanic crust do not permit the formation of deep hydrous melt required for the formation of the Archean granitoid crust. This suggests that the continental crust was produced by the process of subduction rather than by sagduction (Roman and Arndt, 2020).

The evolution of the deep continental crust is unraveled by studies of lower crustal granulite xenoliths in the next two papers. Using trace-element and radiogenic isotopic compositions of kimberlite-borne granulite xenoliths, Aulbach et al. (2020) propose that both plume and subduction processes are important in the origin of the dominantly mafic lower crust in the Mesoarchean, and that the early loss of significant amounts of heat-producing elements and H2O assisted in the stabilization and preservation of the cratonic lithosphere. Ma et al. (2020) report zircon U-Pb dates, Lu-Hf and O isotopic compositions for Eoarchean to Paleoproterozoic lower crustal xenoliths from the North China craton, including the oldest known (∼3.82 Ga) granulite xenoliths on Earth. The data provide insights into early crustal differentiation, interaction between early crust and hydrosphere, and efficient recycling of supracrustal rocks into the mantle at ∼2.5 Ga.

The last three papers in this group examine processes that modify the chemical and isotopic compositions of the crust. Pang et al. (2020) explore the Mg isotopic budget of the continental crust and the mantle in a case study of igneous rocks from the Makran arc, Iran. They find that relatively primitive arc basalts therein have Mg isotopic compositions similar to the unmodified mantle whereas evolved arc rocks have heavy Mg isotopic signatures presumably linked to assimilation-fractional crystallization processes. This is suggested to indicate that heavy Mg isotopes in the continents produced by igneous and weathering processes might have been compensated by a hidden input of light Mg isotopes, probably in the form of carbonates. Huang et al. (2020a) use well-characterized loess, shale, A-, S-, and I-type granite samples worldwide to constrain the K isotopic composition of the upper continental crust. They find large K isotopic variation, which mainly results from isotope fractionation during low-temperature water-rock interactions. Their study indicates that chemical weathering plays an important role in controlling the K isotopic composition of the crust. The final paper in this collection investigates the geochemical and isotopic compositions of Miocene high Sr/Y felsic dikes from southern Tibet (Ji et al., 2020). The results suggest that the generation of Himalayan leucogranite was likely driven by widespread melting of thickened continental crust in southern Tibet (Ji et al., 2020).

2. The Mantle

Roberta has also pioneered research in mantle geochemistry, with a particular focus on the Tanzania and North China cratons, which have been her playground for decades. Many of her papers on these topics have been highly cited, such as “Recycling lower continental crust in the North China craton” (with Shan Gao and others, cited over 1500 times), “Re–Os evidence for replacement of ancient mantle lithosphere beneath the North China craton” (with Shan Gao and others, cited nearly 1000 times) and “Carbonatite metasomatism in the northern Tanzanian mantle: petrographic and geochemical characteristics” (with William F. McDonough and Bruce Chappell, cited over 700 times). This topic is reflected in the second group of papers.

The first paper investigates melt-peridotite reactions via experimental studies. Wang et al. (2020a) identify two types of interaction between eclogite-derived melt and peridotite, including congruent dissolution of subsolidus peridotite and reactive dissolution of partially molten peridotite. These two types of reaction are responsible for generating a range of lithologies in cratonic lithospheric mantle and compositional variations of intracontinental high-Mg igneous rocks.

The next two papers investigate lithospheric mantle evolution using peridotite xenoliths. Liu et al. (2020) examine Nyos peridotites from the Cameroon volcanic line and demonstrate that the reconstructed whole-rock Lu-Hf isotope system can be used as a radiometric tool complementary to the Re-Os isotope system in well-preserved post-Archean peridotites to obtain the most robust estimate for age of melt depletion, and thus formation of the post-Archean lithospheric mantle. Chin et al. (2020) analyze water content in nominally anhydrous minerals and mineral fabric in composite mantle xenoliths from the North China craton. They find low water content in these minerals despite evidence for metasomatic enrichment and conclude that melt infiltration plays a key role in reorganizing olivine fabric, which has implications for the chemical and seismic properties of rejuvenated cratons.

The last two papers in this group focus on sub-arc mantle peridotites and mantle-derived carbonatites. Hu et al. (2020) report Mg isotopic data for a suite of rare and fresh sub-arc mantle xenoliths from the Kamchatka arc, Russia. By comparing their results with published arc lava data, they suggest that the thermal structure of a subduction zone strongly influences the Mg isotopic composition of its lavas via controlling the dehydration of Mg-rich serpentinized slab mantle and its subsequent release of isotopically distinct Mg. Li et al. (2020b) use worldwide carbonatites to constrain the Ba isotopic composition of the mantle. They find that, in contrast to the crust, which has high Ba concentrations and highly variable Ba isotopic compositions, the mantle has a homogenous Ba isotopic composition, thereby implying that Ba isotopes are potentially a novel tracer of crustal recycling.

3. Non-traditional stable isotopes

During her tenure at the University of Maryland, College Park, Roberta started her studies of non-traditional stable isotopes, particularly Li isotope geochemistry, with over 30 papers published by herself, students and postdocs, and a total citation of over 2200. The topics range from studies of Li isotopic distribution in major reservoirs such as the continental crust, lithospheric mantle, arc lavas, lunar samples and meteorites, to investigation of major processes that fractionate Li isotopes such as chemical weathering, magmatic differentiation, prograde metamorphism and chemical diffusion. This is reflected in the final group of papers in this collection, which focuses on recent developments

and novel applications of non-traditional stable isotopes (Li, B, Mg, K, Ca, Cr, Fe, Zn, and Mo) in some of those topics pioneered by Roberta.

The first two papers constrain behaviors of Mg and K isotopes during chemical weathering. Cuozzo et al. (2020) utilize Mg isotopes to reveal that substantial dolerite weathering occurs at sub-zero temperatures in an ice-rich permafrost core from Antarctica. The weathering intensity correlates with modelled unfrozen water content, which supports the concept of a “eutectic active zone layer” defined by the temperature where water freezes rather than the zero-degree isotherm. The next paper documents significant K isotope fractionation during chemical weathering in a tropical climate (Teng et al., 2020). The results suggest that continental weathering plays an important role in the global K isotopic budget by the formation of isotopically heterogeneous rivers and weathered regoliths. Recycling of K-rich crustal materials with distinct K isotopic signatures may produce distinct mantle K isotopic end members.

The following seven papers apply non-traditional stable isotope systematics to study magmatism in different tectonic settings. Chen et al. (2020b) find indistinguishable Ca isotopic compositions among ultraslow-, slow- and fast-spreading gabbroic cumulates and MORBs, suggesting a homogenous Ca isotopic composition of the global oceanic crust. This study lays a solid foundation for understanding the origin of anomalous Ca isotopic compositions in mantle-derived basalts. Shen et al. (2020) examine stable Cr isotopic compositions of Hawaiian basalts and reveal large isotope fractionation during redox-dominated magmatic differentiation, mainly associated with spinel crystallization. The difference in Cr isotopic compositions for basalts from Earth, Moon and Vesta might reflect their different redox conditions. Wang et al. (2020b) document large Mg and Zn isotopic variations in the Himalayan leucogranites, which is mainly induced by the extreme differentiation of high-silica granitic magmas. Their study highlights the potential application of Mg and Zn isotopes in tracing origins of highly fractionated granites. Hanna et al. (2020) explore Li isotopic compositions of geographically, compositionally and temporally diverse Aleutian arc lavas and intrusive samples and demonstrate that Li isotopes, in conjunction with radiogenic isotopes, may be used to decipher slab signatures in arc magmas. Zhang et al. (2020) show variable B and Mo isotopic compositions for arc andesites from the Chinese North Tianshan, which is best explained by the transfer of B and Mo from subducted carbonates to the overriding plate by carbonate dissolution. This study indicates that most carbonates are likely removed from the subducted slab to the mantle wedge during subduction. Sun et al. (2020) report, for the first time, large K isotopic variation in a suite of continental basalts from Northeast China, which reflects K inputs from both subducted oceanic crust and marine sediments into the mantle. This study highlights the potential of using K isotopes to trace subducted oceanic crust and/or sediments in the mantle and places new constraints on the generation of enriched mantle reservoirs. Tian et al. (2020) reveal extremely large diffusion-driven Mg and Fe isotopic variations in ilmenites from the Panzhihua Fe-Ti-oxide-bearing layered mafic intrusion, indicating that interstitial liquid immiscibility plays a crucial role in the formation of Fe-Ti-rich ore deposits.

The last two papers in this issue focus on subduction zone processes. Huang et al. (2020b) find heavy Mg and Fe isotopic compositions for high-pressure poly-mineral veins from the Dabie orogen, which indicates that fluids derived from subducted oceanic crust are heavier in both Mg and Fe isotopic compositions relative to the mantle. This study thus suggests that the light Fe and heavy Mg isotopic signatures of arc lavas are inherited from serpentinite-derived fluids rather than subducted oceanic crust. Lu et al. (2020) report similar Ca isotopic composition for a suite of well-characterized metabasaltic rocks from the Dabie-Sulu orogen including greenschists, amphibolites and eclogites.

Their results suggest limited Ca isotope fractionation during metamorphic dehydration, and hence heterogeneous Ca isotopic signatures in the subducting slab can be transferred into the mantle, producing mantle Ca isotopic heterogeneity.

4. A great scientist and mentor

Roberta received her BS from Portland State University in Oregon. She then moved to Sul Ross State University, a small university in the remote (one traffic light) town of Alpine in west Texas, where she published her first paper on Precambrian metaigneous rocks. After an internship at the NASA Johnson Space Center, where she worked on fluid inclusions in lunar rocks and meteorites (revealing they were laboratory artifacts), she moved to the Australian National University for her Ph.D. Her Ph.D. supervisor was Stuart Ross Taylor, a giant in geochemistry, who was the sole graduate student of Brian Mason. Brian himself was a student of Victor M. Goldschmidt, the founder of modern geochemistry. It was at ANU where she began to develop her global view of constraining the composition of the continental crust. Roberta identified and pioneered the importance of looking directly at lower crustal xenoliths to investigate the lower continental crust. She quickly realized that the present-day lower crust beneath continents was not mafic enough to balance the felsic composition of the bulk crust with that of a mafic parent, and her findings set off several decades of research in the community. After ANU, Roberta moved to the Max Planck Institute for Chemistry where she held a two-year Alexander von Humboldt postdoctoral fellowship in the group of Albrecht Hoffman, another world leader in geochemistry. Roberta returned to ANU as a research fellow in 1989, but first stopping off for her first time in East Africa to extend her studies on the lithosphere to deeper levels. In 1994, Roberta joined Harvard University as an assistant professor, and was promoted to associate professor in 1997, and full professor in 2000. This was no minor achievement, as she was the first woman to be tenured in Earth Sciences at Harvard University since the department was established some 200 years earlier. She joined the University of Maryland, College Park, in 2000 and served as the department chair from 2012 to 2015, prior to moving to the University of California, Santa Barbara. Finally, in 2010 while on sabbatical as a Fulbright Fellow, she co-taught, with Shukrani Manya, a geochemistry class at the University of Dar es Salaam in East Africa under the most challenging and rewarding circumstances.

During her decorated academic career, Roberta enjoyed collaboration with numerous researchers, especially William F. McDonough and Shan Gao. Her PhD students include Cin-Ty Lee and Matthias Barth (Harvard), Fang-Zhen Teng, Lin Qiu, Jingao Liu, Xiao-Ming Liu, Yu Huang, Kang Chen, Su Li, and Ming Tang (University of Maryland) and Allison Greaney, Francisco Apen, Mary Ringwood, and Pengyuan Han (University of California, Santa Barbara). Among those who worked with her as postdocs are Deborah Hassler (Harvard), Thomas Zack, Sonja Aulbach, Ralf Halama, Madalyn Blondes, Richard Gaschnig and Tolulope Olugboji (University of Maryland).

As former students and postdocs, we are fortunate that our academic and personal lives have been enriched by the outstanding intellectual environment that she creates. We have benefited immensely from her scientific integrity, creativity and thoroughness, all of which reflect her great human nature. We are also eternally grateful for her patience and unwavering support, even when we showed up knowing almost nothing, stumbled in our orals, and cooked the worst dinner in the field. Thank you Roberta for taking all of us under your wing.

References

S. Aulbach, C. Symes, T. Chacko, Elemental and radiogenic isotope perspective on formation and transformation of cratonic lower crust: Central Slave craton (Canada). Geochim. Cosmochim. Acta, 278 (2020), pp. 78-93

K. Chen, R.L. Rudnick, Z. Wang, M. Tang, R.M. Gaschnig, Z. Zou, T. He, Z. Hu, Y. Liu, How mafic was the Archean upper continental crust? Insights from Cu and Ag in ancient glacial diamictites, Geochim. Cosmochim. Acta, 278 (2020), pp. 16-29

C. Chen, J. Ciazela, W. Li, W. Dai, Z. Wang, S.F. Foley, M. Li, Z. Hu, Y. Liu, Calcium isotopic compositions of oceanic crust at various spreading rates, Geochim. Cosmochim. Acta, 278 (2020), pp. 272-288

E.J. Chin, V. Soustelle, Y. Liu, An SPO-induced CPO in composite mantle xenoliths correlated with increasing melt-rock interaction, Geochim. Cosmochim. Acta, 278 (2020), pp. 199-218

N. Cuozzo, R.S. Sletten, Y. Hu, L. Liu, F.-Z. Teng, B. Hagedorn, Silicate weathering in antarctic ice-rich permafrost: Insights using magnesium isotopes, Geochim. Cosmochim. Acta, 278 (2020), pp. 244-260

H.D. Hanna, X.-M. Liu, Y.-R. Park, S.M. Kay, R.L. Rudnick, Lithium isotopes may trace subducting slab signatures in Aleutian arc lavas and intrusions, Geochim. Cosmochim. Acta, 278 (2020), pp. 322-339

Y. Hu, F.-Z. Teng, D.A. Ionov, Magnesium isotopic composition of metasomatized upper sub-arc mantle and its implications to Mg cycling in subduction zones, Geochim. Cosmochim. Acta, 278 (2020), pp. 219-234

T.-Y. Huang, F.-Z. Teng, R.L. Rudnick, X.-Y. Chen, Y. Hu, Y.-S. Liu, F.-Y. Wu, Heterogenous potassium isotopic composition of the upper continental crust, Geochim. Cosmochim. Acta, 278 (2020), pp. 122-136

J. Huang, S. Guo, Q.-Z. Jin, F. Huang, Iron and magnesium isotopic compositions of subduction-zone fluids and implications for arc volcanism, Geochim. Cosmochim. Acta, 278 (2020), pp. 376-391

W.-Q. Ji, F.-Y. Wu, X.-C. Liu, Z.-C. Liu, C. Zhang, T. Liu, J.-G. Wang, S.R. Paterson, Pervasive Miocene melting of thickened crust from the Lhasa terrane to Himalaya, southern Tibet and its constraint on generation of Himalayan leucogranite, Geochim. Cosmochim. Acta, 278 (2020), pp. 137-156

S. Li, W.D. Junkin, R.M. Gaschnig, R.D. Ash, P.M. Piccoli, P.A. Candela, R.L. Rudnick, Molybdenum contents of sulfides in ancient glacial diamictites: Implications for molybdenum delivery to the oceans prior to the Great Oxidation Event, Geochim. Cosmochim. Acta, 278 (2020), pp. 30-50

W.-Y. Li, H.-M. Yu, J. Xu, R. Halama, K. Bell, X.-Y. Nan, F. Huang, Barium isotopic composition of the mantle: Constraints from carbonatites, Geochim. Cosmochim. Acta, 278 (2020), pp. 235-243

J. Liu, D.G. Pearson, Q. Shu, H. Sigurdsson, E. Thomassot, O. Alard, Dating post-Archean lithospheric mantle: Insights from Re-Os and Lu-Hf isotopic systematics of the Cameroon Volcanic Line peridotites, Geochim. Cosmochim. Acta, 278 (2020), pp. 177-198

W.-N. Lu, Y. He, Y. Wang, S. Ke, Behavior of calcium isotopes during continental subduction recorded in meta-basaltic rocks, Geochim. Cosmochim. Acta, 278 (2020), pp. 392-404

Q. Ma, Y.-G. Xu, X.-L. Huang, J.-P. Zheng, X. Ping, X.-P. Xia, Eoarchean to Paleoproterozoic crustal evolution in the North China Craton: Evidence from U-Pb and Hf-O isotopes of zircons from deep-crustal xenoliths, Geochim. Cosmochim. Acta, 278 (2020), pp. 94-109

Q.-F. Mei, J.-H. Yang, Y.-F. Wang, H. Wang, P. Peng, Tungsten isotopic constraints on homogenization of the Archean silicate Earth: Implications for the transition of tectonic regimes, Geochim. Cosmochim. Acta, 278 (2020), pp. 51-64

K.-N. Pang, F.-Z. Teng, Y. Sun, S.-L. Chung, M.H. Zarrinkoub, Magnesium isotopic systematics of the Makran arc, Iran: Implications for crust-mantle Mg isotopic balance, Geochim. Cosmochim. Acta, 278 (2020), pp. 110-121

A. Roman, N.T. Arndt, Differentiated Archean oceanic crust: Its thermal structure, mechanical stability and a test of the sagduction hypothesis, Geochim. Cosmochim. Acta, 278 (2020), pp. 65-77

J. Shen, J. Xia, L. Qin, R.W. Carlson, S. Huang, R.T. Helz, T.D. Mock, Stable chromium isotope fractionation during magmatic differentiation: Insights from Hawaiian basalts and implications for planetary redox conditions, Geochim. Cosmochim. Acta, 278 (2020), pp. 289-304

Y. Sun, F.-Z. Teng, Y. Hu, X.-Y. Chen, K.-N. Pang, Tracing subducted oceanic slabs in the mantle by using potassium isotopes, Geochim. Cosmochim. Acta, 278 (2020), pp. 353-360

M. Tang, C.T.A. Lee, R.L. Rudnick, K.C. Condie, Rapid mantle convection drove massive crustal thickening in the late Archean, Geochim. Cosmochim. Acta, 278 (2020), pp. 6-15

F.-Z. Teng, Y. Hu, J.-L. Ma, G.-J. Wei, R.L. Rudnick, Potassium isotope fractionation during continental weathering and implications for global K isotopic balance, Geochim. Cosmochim. Acta, 278 (2020), pp. 261-271

H.-C. Tian, C. Zhang, F.-Z. Teng, Y.-J. Long, S.-G. Li, Y. He, S. Ke, X.-Y. Chen, W. Yang, Diffusion-driven extreme Mg and Fe isotope fractionation in Panzhihua ilmenite: Implications for the origin of mafic intrusion, Geochim. Cosmochim. Acta, 278 (2020), pp. 361-375

C. Wang, M.L. Cascio, Y. Liang, W. Xu, An experimental study of peridotite dissolution in eclogite-derived melts: Implications for styles of melt-rock interaction in lithospheric mantle beneath the North China Craton, Geochim. Cosmochim. Acta, 278 (2020), pp. 157-176

Z.-Z. Wang, S.-A. Liu, Z.-C. Liu, Y.-C. Zheng, F.-Y. Wu, Extreme Mg and Zn isotope fractionation recorded in the Himalayan leucogranites, Geochim. Cosmochim. Acta, 278 (2020), pp. 305-321

Y. Zhang, C. Yuan, M. Sun, J. Li, X. Long, Y. Jiang, Z. Huang, Molybdenum and boron isotopic evidence for carbon-recycling via carbonate dissolution in subduction zones, Geochim. Cosmochim. Acta, 278 (2020), pp. 340-352

Theodoridis, S., Fordham, D.A., Brown, S.C., Li, S., Rahbek, C., Nogues-Bravo, D., 2020. Evolutionary history and past climate change shape the distribution of genetic diversity in terrestrial mammals. Nature Communications 11, 2557.

https://doi.org/10.1038/s41467-020-16449-5

Knowledge of global patterns of biodiversity, ranging from intraspecific genetic diversity (GD) to taxonomic and phylogenetic diversity, is essential for identifying and conserving the processes that shape the distribution of life. Yet, global patterns of GD and its drivers remain elusive. Here we assess existing biodiversity theories to explain and predict the global distribution of GD in terrestrial mammal assemblages. We find a strong positive covariation between GD and interspecific diversity, with evolutionary time, reflected in phylogenetic diversity, being the best predictor of GD. Moreover, we reveal the negative effect of past rapid climate change and the positive effect of inter-annual precipitation variability in shaping GD. Our models, explaining almost half of the variation in GD globally, uncover the importance of deep evolutionary history and past climate stability in accumulating and maintaining intraspecific diversity, and constitute a crucial step towards reducing the Wallacean shortfall for an important dimension of biodiversity.

Thirumalai, K., Clemens, S.C., Partin, J.W., 2020. Methane, monsoons, and modulation of millennial-scale climate. Geophysical Research Letters 47, e2020GL087613.

https://doi.org/10.1029/2020GL087613

Earth's orbital geometry exerts a profound influence on climate by regulating changes in incoming solar radiation. Superimposed on orbitally paced climate change, Pleistocene records reveal substantial millennial scale variability characterized by abrupt changes and ‐rapid swings. However, the extent to which orbital forcing modulates the amplitude and timing of these millennial variations is unclear. Here we isolate the magnitude of millennial‐scale variability (MMV) in two well dated records, both linked to precession cycles (19,000 ‐ ‐and 23,000 year periodicity): composite Chinese speleothem ‐ δ18O, commonly interpreted as a proxy for Asian monsoon intensity, and atmospheric methane. At the millennial timescale (1,000–10,000 years), we find a fundamental decoupling wherein precession directly modulates the MMV of methane but not that of speleothem δ18O, which is shown to be strikingly similar to the MMV of Antarctic ice core δ2H. One explanation is that the MMV of methane responds to changes in midlatitude to high latitude insolation, whereas ‐speleothem δ18O is modulated by internal climate feedbacks.


https://doi.org/10.1080/15275922.2020.1728437

Oil fingerprinting is concerned with determining the chemical profile of a spilled oil to determine its origin, whether that be a vessel, well or other source. Asphaltenes are typically discarded in this process even though they are considered refractory in comparison to the volatile fraction and have the ability to provide valuable information in oil fingerprinting. A heavy fuel oil was exposed to evaporative and photochemical conditions to determine if the asphaltene fraction and asphaltene profiling were influenced by weathering. It was found that although evaporative weathering had a strong effect on the volatile fraction of the oil, it had no influence on the asphaltene fraction, and profiling of the asphaltene fraction using previously published methods was still possible. When the oil was exposed to photo-oxidative conditions using natural sunlight, the mass of the asphaltene

fraction increased significantly. Attenuated Total Reflectance - Fourier Transform Infrared (ATR-FTIR) analysis demonstrated that the oxygen level in the asphaltene fraction also increased with photochemical weathering compared to evaporative weathering alone. Even though the asphaltene fraction changed under photo-oxidative conditions, it could still be used for source determination using previously published ATR-FTIR and pyrolysis GC-MS methods for profiling of the asphaltene fraction.



We performed pulsed laser irradiation to simulate the progressive space weathering of three individual chips of the CM2 Murchison meteorite. After irradiation, we performed two-step laser desorption mass spectrometry to analyze alterations in the concentration, distribution, and functional group chemistry of organics in the samples. These results indicate an increase in the concentration of aromatic organic species in the irradiated regions of the samples compared to the unirradiated areas. We utilized optical reflectance spectroscopy, Fourier-transform infrared spectroscopy, and Mössbauer spectroscopy to investigate changes in the spectral characteristics of the samples as a result of simulated progressive space weathering. We observed an overall decrease in reflectance spectra of the irradiated samples. The spectra also exhibit a bluing trend after irradiation, the degree of which weakens with progressive laser exposure. Finally, we used scanning electron microscopy and transmission electron microscopy to examine changes in microstructure and chemistry of the irradiated samples. We observed vesicles and nanoparticles in the melt layers produced by laser irradiation. Our results indicate that the nanoparticle compositions evolve with increasing laser irradiation, progressing from a mineralogically diverse group towards a population dominated by Fe-Ni-sulfides. Radiative transfer models were used to examine the influence of various nanoparticle compositions on sample spectral properties, the results of which indicate nanoparticle size and mineralogy may result in competing spectral effects. We discuss the implications these experiments have for the space weathering of primitive, organic-rich asteroids.

Tian, H.-C., Zhang, C., Teng, F.-Z., Long, Y.-J., Li, S.-G., He, Y., Ke, S., Chen, X.-Y., Yang, W., 2020. Diffusion-driven extreme Mg and Fe isotope fractionation in Panzhihua ilmenite: Implications for the origin of mafic intrusion. Geochimica et Cosmochimica Acta 278, 361-375.


To investigate the petrogenesis of Fe-Ti oxide ore deposits, we report Mg and Fe isotopic compositions for coexisting olivine, clinopyroxene and ilmenite in Fe-Ti oxide ores, magnetite-bearing gabbros and gabbros from the Panzhihua Fe-Ti-oxide-bearing layered mafic intrusion, Southwest China. Olivine and clinopyroxene have δ26Mg values ranging from −0.47 to −0.32‰ and −0.40 to −0.18‰, and δ57Fe values from −0.21 to +0.23‰ and −0.16 to +0.20‰, respectively. Most of these mineral pairs display disequilibrium inter-mineral fractionation as they fall off the theoretically predicted equilibrium fractionation lines. Ilmenites from oxide ores and magnetite-bearing gabbros (Group 1) have mantle-like or lower δ26Mg values of −0.80 to −0.13‰ and δ57Fe values of −0.33 to −0.23‰, and those from gabbros (Group 2) display slightly to extremely higher

δ26Mg values of +0.48 to +23.10‰ and much lower δ57Fe values of −0.59 to −0.33‰. The δ26Mg negatively correlates with δ57Fe in all ilmenites, which cannot be explained by simple extensive fractional crystallization or Soret diffusion. Instead, the negative correlations between δ26Mg and δ57Fe and between MgO and FeO in ilmenites result from Mg-Fe inter-diffusion among ilmenite, silicate minerals and high-Ti basaltic melts. The extremely large isotopic variations were produced by the large Mg activity gradient between different types of ilmenites and melts, which was enhanced by interstitial liquid immiscibility process. Our study therefore demonstrates that combined Mg-Fe isotopes can be used to trace the genesis of Fe-Ti-oxide-bearing ore.

Tian, H., Wang, M., Liu, S., Zhang, S., Zou, C., 2020. Influence of pore water on the gas storage of organic-rich shale. Energy & Fuels 34, 5293-5306.


Previous studies that use dry samples have been conducted on the nanoporosity of organic matter in shale. However, underground shales contain pore water that may greatly influence their pore structures and adsorbed gas content. To address this, a typical organic-rich, marine, gas-bearing shale in China was analyzed in this study. The water content and isothermal adsorption under different saturation conditions were determined, and the adsorbed and free gas contents were quantified. Across scales, water occurs within clays, between grains, and in fissures. In micro- and mesopores, gas is mainly adsorbed onto the surface of kerogen, because clay surfaces are water-saturated. In macropores and fractures, gas mainly exists in a free state. Adsorbed and free gas contents decrease with increasing water saturation in shale reservoirs. In high-production reservoirs, a limited amount of adsorbed gas is stored within micropores, while a relatively large amount of free gas is stored in larger pores and natural fractures. Because shale gas occurs in low concentrations, high total organic carbon may not be the only necessary factor; high porosity and many natural fractures may be more favorable for high reservoir productivity. The results provide valuable insights for understanding gas storage and finding zones of high productivity in shale reservoirs and have potential applications in engineering conditions.

Tian, H., Zou, C., Liu, S., Hong, F., Fan, J., Gui, L., Hao, J., 2020. Reservoir porosity measurement uncertainty and its influence on shale gas resource assessment. Acta Geologica Sinica - English Edition 94, 233-242.

https://doi.org/10.1111/1755-6724.14287

Reservoir porosity is a critical parameter for the process of unconventional oil and gas resources assessment. It is difficult to determine the porosity of a gas shale reservoir, and any large deviation will directly reduce the credibility of any shale gas resources evaluation. However, there is no quantitative explanation for the accuracy of porosity measurement. In this paper, measurement uncertainty, an internationally recognized index, was used to evaluate the results of porosity measurement of gas shale plugs, and its impact on the credibility of shale gas resources assessment was determined. The following conclusions are drawn: (1) the measurement uncertainty of porosity of a shale plug is 1.76%–3.12% using current measurement methods, the upper end of which is too large to be acceptable. It is suggested that the measurement uncertainty should be factored into the standard helium gas injection porosity determination experiment, and the uncertainty should be less than 2.00% when using a high precision pressure gauge; (2) in order to reduce the risk for ‐

exploration and decision making, attention should be paid to the large uncertainty (30% at least) of ‐shale gas resource assessment results, sometimes with corrections being made based on the practical considerations;(3) a pressure gauge with an accuracy of 0.25% of the full scal cannot meet the requirements of porosity measurement, and a high precision plug cutting method or high‐ ‐precision bulk volume measurement method such as one using 3D scanning, is recommended to effectively reduce porosity uncertainty; (4) the method and process for evaluating the measurement uncertainty of gas shale porosity could also be referred for assessment of experimental quality by other laboratories.

Tian, Q., Bai, Y., Fang, X., Chen, C., Liu, X., 2020. Responses of sedimentary δ2Halk values to environmental changes as revealed by different plant responses to altitude and altitude-related temperatures. Science of The Total Environment 733, 138087.


Single species-based altitudinal transects may provide a new understanding of the variabilities in sedimentary wax-derived n-alkane hydrogen isotope (δ2Halk) values caused by altitude and complex climatic change linked with the growth of mountains. We investigated Kobresia pygmaea (Kobresia), Quercus aquifolioides (Quercus) and Berberis thunbergii DC (Berberis) along three altitudinal transects on the Tibetan Plateau (TP), i.e., the southern TP, the Longmen Mountains (LM; eastern TP) and the Qilian Mountains (QL; northeastern TP). Here we present 47 plant δ2Halk values: these include 14 Kobresia, 27 Berberis and 6 Quercus samples, which are accompanied by comparisons with nine new soil δ2Halk values from the QL, and 105 previously-published δ2Halk values for surface soils along the first two transects. Our data show that altitude is the dominant factor in determining three plant δ2Halk values. However, we observed substantial differences in the δ2Halk values and their εwax-p ratios for Kobresia, Quercus and Berberis for different climatic regimes and along these three transects. Significantly, for Kobresia along the LM and QL transects, ∆δ2Halk = −84.3‰/km (r2 = 0.94; p < 0.05; n = 4) and − 65.5‰/km (r2 = 0.74; p < 0.01; n = 10), and ∆εwax-p = −80.4‰/km (r2 = 0.93; p < 0.05) and −56.7‰/km (r2 = 0.66; p < 0.01), respectively, were three or four times as large as for the soil δ2Halk values observed along these altitudinal gradients. Overall, the altitudinal lapse rate (ALR) of δ2Halk values and their εwax-p ratios varies between species, with Kobresia being the most negative and Berberis the least negative, potentially resulting from the strong response of monocotyledoneae Kobresia δ2Halk values to cooling with increasing altitude, and the relative influence of cryosphere meltwater at higher altitudes. Thus, impact of climate change on the sedimentary δ2Halk values should therefore be fully taken into account during reconstructions of paleoaltitudes.

Tiwari, B., Ojha, A., Ghosh, S., Varma, A.K., Mendhe, V.A., Mondal, A., 2020. A composite microstructural and geochemical approach to quench the quest for hydrocarbon from Barren Measures shales of Jharia Basin, India. Journal of Natural Gas Science and Engineering 78, 103310.


The present study portraits the organic petrological, geochemical and microstructural characters of twenty borehole shale samples for assessing the hydrocarbon generation proficiency of the shales from the Barren Measures Formation (a stratigraphic unit of the Gondwana that is devoid of any workable coal seam) of the Jharia Basin, India, which was underinvestigated until now. The samples consist of vitrinite grains ranging from 5.41 to 20.57 vol%, the dominance of which compared to the

inertinite and liptinites may reflect the lignocellulosic organic matter (type-III kerogen) input from the terrestrial plants. The range of the mean random vitrinite reflectance values (0.93–1.27%) may suggest the gas generation potential of the shale samples. The peak palaeotemperature values, may, in addition, suggest wet gas generation from these shales in complementary to some shale samples having efficiency to generate dry gas. The total organic carbon in these samples ranging between 3.87 and 15.99 wt% may imply good to excellent hydrocarbon generation capability. Rock Eval pyrolysis suggests the input of type-III kerogen within the mire and the correlations of the pyrolysis parameters exhibit that the shale samples possess significant potential to generate gaseous hydrocarbons (shale gas). The factor of kerogen conversion (f) of many shales suggests almost 20–30% transformation of kerogen to hydrocarbons. On attaining sufficient thermal maturity, the remaining large amount of labile chemical moieties may convert to hydrocarbons. The positive relation of the present-day hydrogen index (HIpd) with the A-factor would suggest the depletion of hydrogen containing functional groups for generating the gaseous hydrocarbons (shale gas). The Raman spectra of the samples reveal poorly organized microstructure, possibly, due to the presence of labile aliphatic compounds that would yet to generate hydrocarbons on attaining relevant thermal maturity as well as because of partially condensed aromatic system containing heteroatoms. The correlations of the Raman data with the mean random vitrinite reflectance data reveal generation of wet and dry gas from these shale samples based on the maturity level. The scientific content of this present study lies in suggesting a set of new equations from the relations obtained between of the Raman spectral parameters and the Rock Eval data in order to suggest the applicability of the Raman spectroscopy in elucidating the shale gas potential. These may be considered as the addendum to the applications of the existing techniques to elucidate the hydrocarbon potential of the organic-rich source rocks, which also add the novelty of this investigation. The new equations and the relations may be tested in the samples of different thermal maturity from other basins for substantiating their world-wide applications.


https://doi.org/10.1038/s41598-020-65010-3

The pool of dissolved organic carbon (DOC), is one of the main regulators of the ecology and biogeochemistry of inland water ecosystems, and an important loss term in the carbon budgets of land ecosystems. We used a novel machine learning technique and global databases to test if and how different environmental factors contribute to the variability of in situ DOC concentrations in lakes. In order to estimate DOC in lakes globally we predicted DOC in each lake with a surface area larger than 0.1 km2. Catchment properties and meteorological and hydrological features explained most of the variability of the lake DOC concentration, whereas lake morphometry played only a marginal role. The predicted average of the global DOC concentration in lake water was 3.88 mg L−1. The global predicted pool of DOC in lake water was 729 Tg from which 421 Tg was the share of the Caspian Sea. The results provide global-scale evidence for ecological, climate and carbon cycle models of lake ecosystems and related future prognoses.

Trinklein, T.J., Prebihalo, S.E., Warren, C.G., Ochoa, G.S., Synovec, R.E., 2020. Discovery-based analysis and quantification for comprehensive three-dimensional gas chromatography flame ionization detection data. Journal of Chromatography A 1623, 461190.


Basic principles are introduced for implementing discovery-based analysis with automated quantification of data obtained using comprehensive three-dimensional gas chromatography with flame ionization detection (GC3-FID). The GC3-FID instrument employs dynamic pressure gradient modulation, providing full modulation (100% duty cycle) with a fast modulation period (PM) of 100 ms. Specifically, tile-based Fisher-ratio analysis, previously developed for comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometry (GC×GC-TOFMS), is adapted and applied for GC3-FID where the third chromatographic dimension (3D) is treated as the “spectral” dimension. To evaluate the instrumental platform and software implementation, ten “non-native” compounds were spiked into a ninety-component base mixture to create two classes with a concentration ratio of two for the spiked analyte compounds. The Fisher ratio software identified 95 locations of potential interest (i.e., hits), with all ten spiked analytes discovered within the top fourteen hits. All 95 hits were quantified by a novel signal ratio (S-ratio) algorithm portion of the F-ratio software, which determines the time-dependent S-ratio of the 3D chromatograms from one class to another, thus providing relative quantification. The average S-ratio for spiked analytes was 1.94 ± 0.14 mean absolute error (close to the nominal concentration ratio of two), and 1.06 ± 0.16 mean absolute error for unspiked (i.e., matrix) components. The appearance of the S-ratio as a function of 3D retention time in the GC3 dataset, referred to as an S-ratiogram, provides indication of peak purity for each hit. The unique shape of the S-ratiogram for hit 1, α-pinene, suggested likely 3D overlap. Parallel factor analysis (PARAFAC) decomposition of the hit location, confirmed that overlap was occurring, and successfully decomposed α-pinene from a highly overlapped (3Rs = 0.1) matrix interferent.

Truong-Lam, H.S., Seo, S., Kim, S., Seo, Y., Lee, J.D., 2020. In situ Raman study of the formation and dissociation kinetics of methane and methane/propane hydrates. Energy & Fuels 34, 6288-6297.


In this study, the kinetics of methane and methane/propane hydrate formation/dissociation were investigated. Simultaneously, microlevel studies, including hydrate structure, preferential cage occupancy, and gas-dissolving behavior studies were also carried out using an in situ Raman spectrometer. In the methane hydrate experiment, the small cages of methane in structure I seemed to be formed preferentially in the initial period of hydrate formation. The results showed that methane collapsed faster in large 51262 cages than in small 512 cages as hydrate dissociation progressed. During kinetic experiments on a binary gas mixture of methane/propane, vapor composition was measured by an in situ Raman spectrometer, and the results were consistent with those obtained by gas chromatography. Small 512 cages of methane in structure II formed quickly during methane/propane hydrate formation and broke down rapidly during hydrate dissociation. The order of cage formation and the dissociation rate was CH4 in 512 ≫ CH4 in 51264 > C3H8 in 51264. The results of the in situ Raman analysis revealed that methane and methane/propane hydrates showed different spectral behaviors for the O–H stretching band, depending on the gas hydrate structure type. Additionally, the mole fractions of dissolved methane were also measured in specific regions, and our results were consistent with those reported in the literature. These findings contribute to a better understanding of the nature of guest–host interactions in clathrate hydrates.

Ugelow, M.S., Berry, J.L., Browne, E.C., Tolbert, M.A., 2020. The impact of molecular oxygen on anion composition in a hazy Archean Earth atmosphere. Astrobiology 20, 658-669.

https://doi.org/10.1089/ast.2019.2145

Atmospheric organic hazes are common in planetary bodies in our solar system and likely exoplanet atmospheres as well. In addition, geochemical data support the existence of an organic haze in the early Earth's atmosphere. Much of what is known about organic haze formation derives from studies of Saturn's moon Titan. It is believed that on Titan ions play an important role in haze formation. It is possible, by using Titan as an analog for the Archean Earth, to consider that an Archean haze could have formed by similar processes. Here, we examine the anion chemistry that occurs during laboratory simulations of early Earth haze formation and measure the composition of gaseous anions as a function of O2 mixing ratio. Gaseous anion composition and relative abundances are measured by an atmospheric pressure interface time-of-flight mass spectrometer and are compared to previous photochemical haze mass loading measurements. Numerous anions are observed spanning from mass-to-charge ratio 26 to 246, with a majority of the identified anions containing carbon, hydrogen, nitrogen, and/or oxygen. A shift in the anion composition occurs with increasing the precursor O2 mixing ratio. With 0–20 ppmv O2 in CH4/CO2/N2 mixtures, ions contain mostly organic nitrogen, with CNO− being the most intense ion peak. As the precursor O2 is increased to 200 and 2000 ppmv, inorganic nitrogen ions become the dominant chemical group, with NO3

− having the most intense ion signal. The clear shift in the ionic composition could be indicative of a modification to the gas-phase chemistry that occurs in the transition from an anoxic atmosphere to an oxygen-containing atmosphere, with potential astrobiological significance.

Ütnü, Y.E., Okutan, H., Aydın, A.A., 2020. Polycyclic aromatic hydrocarbon (PAH) content of Malkara lignite and its ex-situ underground coal gasification (UCG) char residues. Fuel 275, 117949.


Although underground coal gasification (UCG) is described and introduced as a clean coal technology, side effects of gasification process and its residues should be well examined for protection of surface water and groundwater systems. PAHs are one of the typical organic pollutants rising from UCG process, which are highly mutagenic, carcinogenic and toxic compounds. Due to reported environmental and health hazards of PAHs, PAH content of Malkara lignite and its UCG char residue has been investigated in this study. 16 PAHs listed by the United States Environmental Protection Agency (EPA) and DIN CEN/TS 15439 (Tar Protocol) are the main focus. Three different solvents with different polarity and composition have been used to understand the extraction mechanism in lignite and char samples and research data have been presented based on GC/MS, FT-IR and thermogravimetric analyses of samples. Malkara lignite and its UCG char contain 7.159 mg/kg and 2.758 mg/kg of EPA PAHs, respectively. Besides, lignite is rich with high molecular weight, whereas its char is abundant in low molecular weight PAHs and PAH derivatives according to data evaluation based on Tar Protocol. In addition to GC/MS data, FT-IR and thermogravimetric analyses also provide valuable information on organic content distribution in samples. The presented data in this paper provide PAH and PAH derivative compositions of Malkara lignite (Tekirdağ, Turkey) and its UCG char residue in detail, together with discussions on organic content distributions in samples.

Van De Ven, C.J.C., Mumford, K.G., 2020. Intermediate-scale laboratory investigation of stray gas migration impacts: Methane source architecture and dissolution. Environmental Science & Technology 54, 6299-6307.


Stray gas migration as a result of hydrocarbon extraction has caused environmental concern and is receiving widespread attention. Natural gas migration in the subsurface can have environmental implications when gas components (e.g., methane, longer-chained hydrocarbons) dissolve into shallow groundwater or pass through groundwater systems to the atmosphere. Because of the complexity of the subsurface systems and the parameters affecting stray gas migration, systematic quantification is difficult, particularly in field studies. To focus on key processes of gas migration, laboratory experiments offer a controlled environment to collect data which can be applied to field and modeling efforts. In this study, methane was injected into an intermediate-scale (150 × 150 × 2 cm3) two-dimensional flow cell packed with saturated homogeneous or heterogeneous unconsolidated sands. The impact of active methane leakage versus stopping of leakage was investigated. High-resolution, visualization techniques coupled with high-frequency water sampling at multiple depth-discrete intervals allowed for understanding of coupled methane migration and mass transfer. Results show that methane dissolution is affected by heterogeneity, active versus inactive leakage, and multicomponent mass transfer, prolonging the longevity of both free- and dissolved-phase methane in the subsurface. Findings highlight the importance of considering geology, hydrogeologic conditions, and multicomponent mass transfer in gas migration systems at the field scale.


https://doi.org/10.1134/S1028334X20020154

Accelerator mass spectrometry dating of organic microinclusions was performed on eight samples from the lower part of the thick Pleistocene syngenetic ice wedges exposed in the Batagay mega-slump in northern Yakutia, the upper reaches of the Yana River (67.58° N, 134.77° E). Radiocarbon dating suggests that ice wedge growth took place between 38 120 and 45 570 14C BP (42.1–49 cal ka BP). The Late Pleistocene mean January air temperatures from 42 to 49 cal ka BP have been reconstructed from the isotope data for the Batagay section and a number of reference sections in northwestern Yakutia. The lowest mean January air temperature of –51°С for this period was in Batagaika, whereas in the areas located 500–600 km to the north, it was 5–7°C higher. This is accounted for by the influence of the Yakutian anticyclone in winter during the Late Pleistocene from 42 to 49 cal ka BP, which was as pronounced at that time as it is now.

Vaughn, D.R., Bianchi, T.S., Shields, M.R., Kenney, W.F., Osborne, T.Z., 2020. Increased organic carbon burial in northern Florida mangrove-salt marsh transition zones. Global Biogeochemical Cycles 34, e2019GB006334.

https://doi.org/10.1029/2019GB006334

Blue carbon habitats like salt marshes and mangroves bury large amounts of carbon with limited area; however, they also are increasingly susceptible to current climate change. Combined effects of rising temperatures, decreasing freeze frequencies, and increasing sea level rise rates are resulting in mangrove replacement of salt marshes along the southern United States. Surface soils analyzed here from wetlands along northern Florida Atlantic and Gulf Coasts showed higher apparent sedimentation rates in mangrove dominated sites (1.5–3.2 mm yr‐ −1) and where mangroves are migrating into the marsh (termed transition sites, 2.3–3.8 mm yr−1). Average carbon burial rates were higher in transition sites for both coasts (27–47 g C·m−2·yr−1) compared to the respective mangrove (10–22 g C·m−2·yr−1) and salt marsh (4–7 g C·m−2·yr−1) sites. Lignin biomarker data (Λ 6, Λ‐ ‐8, and C/V) indicated that mangrove and transition sites had higher lignin inputs from woody vascular plants compared to salt marsh sites, which may slow decadal to centennial scale decay. ‐ ‐Higher amino acid concentrations in mangrove soils relative to mangrove biomass (1.8–2.3 mmol g C−1 vs. 0.2–0.9 mmol g C−1) and lower C/N indicated that these mangrove sites receive higher algal inputs than the transition and salt marsh sites, attributed to greater tidal inundation in the mangrove sites given their position near the shoreline. Overall, increased accretion, carbon burial, and lignin in mangrove transition sites indicate that this migration may increase carbon burial and increase the stability and residence time of buried soil carbon. Future studies on mangrove migration in northern Florida can verify this through replication and elevation analysis.

Viehmann, S., Reitner, J., Tepe, N., Hohl, S.V., Van Kranendonk, M., Hofmann, T., Koeberl, C., Meister, P., 2020. Carbonates and cherts as archives of seawater chemistry and habitability on a carbonate platform 3.35 Ga ago: Insights from Sm/Nd dating and trace element analysis from the Strelley Pool Formation, Western Australia. Precambrian Research 344, 105742.


Carbonates and cherts in the 3.35 billion-year-old Strelley Pool Formation (Fm.; Australia) host stromatolites that are among the oldest remnants of life on Earth. However, it is still not entirely clear whether these mineral phases are authigenic precipitates, and whether they represent reliable geochemical archives of early Earth environments. Here we present major/trace-element and Nd-isotope data of stromatolitic carbonates, associated crystal-fan carbonates, and cherts in the Strelley Pool Fm. (i) to assess the reliability of these chemical sediments as geochemical archives of the fluids from which they precipitated, (ii) to date the time of formation of carbonate and silica phases, and (iii) to trace the sources of elements prevailing in microbial habitats 3.35 Ga ago.

Stromatolitic carbonates plot together with the stratigraphically underlying Marble Bar cherts on a Sm-Nd regression line yielding 3253 ± 320 Ma. In contrast, associated crystal-fan carbonates together with altered Marble Bar cherts yield 2718 ± 220 Ma, suggesting that their Sm-Nd isotope system was reset after deposition. Both types of carbonates, as well as white cherts, show shale-normalized rare earth element and yttrium patterns (REYSN; with the exception of redox-sensitive Ce and Eu and heavy REYSN to middle REYSN depletion) that are parallel to those of modern seawater, indicating a predominantly seawater-derived origin. Positive EuSN anomalies (2.1–2.4), combined with heterogeneous ɛNd3.35Ga values between −3.2 and +5.8 within individual alternating stromatolite laminae, further support that the dissolved fraction of seawater on the ancient carbonate platform was variably affected by both continental weathering and high-temperature hydrothermal fluids contributing elements of both young mafic or older felsic rocks. In conclusion, trace element and Nd isotope data presented here match well with the depositional environment, as characterized based on lithological, geochemical, and stratigraphic relationships, on an early

continent, showing at least episodic emergence above the sea level, supporting microbial life on a shallow marine platform.



A better understanding of the nature of crude oil compounds that preferentially interact with certain types of solids is essential to visualize solutions to challenges in oil fields, such as enhancing the oil recovery factor, via wettability alteration, and remediating emulsions stabilized by fines, among others. The simplistic assumption that the organic matter linked to hydrophilic solids corresponds to polar fractions (i.e., asphaltenes) needs more compositional detail. In an attempt to elucidate this important issue, in the present work, the organic species from an oil adsorbed on silica, alumina (synthetic solids), bentonite, and kaolinite (clays) were isolated and subsequently identified by infrared spectroscopy and Fourier transform ion cyclotron resonance mass spectrometry in atmospheric pressure photoionization positive mode. The solids were characterized by X-ray powder diffraction and point of zero charge. Interestingly, the nature of adsorbed compounds depends upon either the surficial charge of the solids or the acidic character of the functional groups. Through both infrared spectroscopy and mass spectrometry, consistent and complementary results were achieved. The preferential adsorption of nitrogen basic compounds on bentonite and kaolinite was evidenced, promoted by the presence of metal–OH groups on the clay surface. Furthermore, that compounds adsorbed on all of the materials had slightly lower aromaticity than asphaltene-type compounds but an important contribution of oxygen compounds, which included sulfone-type compounds not detected in the asphaltene fraction. Highly conjugated aromatic oxygenated species were identified in the adsorbed organic matter by alumina, while oxygenated acidic compounds (carbonyl derivatives) were identified in the extracts recovered from silica, kaolinite, and bentonite.

Vítek, P., Ascaso, C., Artieda, O., Casero, M.C., Wierzchos, J., 2020. Raman imaging of microbial colonization in rock—some analytical aspects. Analytical and Bioanalytical Chemistry 412, 3717-3726.

https://doi.org/10.1007/s00216-020-02622-8

Raman imaging allows one to obtain spatially resolved chemical information in a nondestructive manner. Herein, we present analytical aspects of effective in situ and in vivo Raman imaging of algae and cyanobacteria from within their native rock habitats. Specifically, gypsum and halite inhabited by endolithic communities from the hyperarid Atacama Desert were analyzed. Raman imaging of these phototrophic colonization reveals a pigment composition within the aggregates that helps in understanding some of their adaptation strategies to survive in this harsh polyextreme environment. The study is focused on methodical aspects of Raman imaging acquisition and subsequent data processing. Point imaging is compared with line imaging in terms of their image quality, spatial resolution, spectral signal-to-noise ratio, time requirements, and risk of laser-induced sample alteration. The roles of excitation wavelength, exposure time, and step size of the imaging grid on successful Raman imaging results are also discussed.



Future supplies of rare minerals for global industries with high-tech products may depend on deep-sea mining. However, environmental standards for seafloor integrity and recovery from environmental impacts are missing. We revisited the only midsize deep-sea disturbance and recolonization experiment carried out in 1989 in the Peru Basin nodule field to compare habitat integrity, remineralization rates, and carbon flow with undisturbed sites. Plough tracks were still visible, indicating sites where sediment was either removed or compacted. Locally, microbial activity was reduced up to fourfold in the affected areas. Microbial cell numbers were reduced by ~50% in fresh “tracks” and by <30% in the old tracks. Growth estimates suggest that microbially mediated biogeochemical functions need over 50 years to return to undisturbed levels. This study contributes to developing environmental standards for deep-sea mining while addressing limits to maintaining and recovering ecological integrity during large-scale nodule mining.

Voosen, P., 2020. UV radiation blamed in ancient mass extinction. Science 368, 926.


The end of the Devonian period, 359 million years ago, was an eventful time: Fish were inching out of the ocean, and fernlike forests were advancing on land. The world was recovering from a mass extinction 12 million years earlier, but the climate was still chaotic, swinging between hothouse conditions and freezes so deep that glaciers formed in the tropics. And then, just as the planet was warming from one of these ice ages, another extinction struck, seemingly without reason. Now, spores from fernlike plants, preserved in ancient lake sediments from eastern Greenland, suggest a culprit: The planet's protective ozone layer was suddenly stripped away, exposing surface life to a blast of mutation-causing ultraviolet (UV) radiation.

Just as the extinction set in, the spores became misshapen and dark, indicating DNA damage, John Marshall, a palynologist at the University of Southampton, and his co-authors say in a paper published this week in Science Advances. It's evidence, he says, that “all of the ozone protection is gone.”

Scientists have long believed—at least before humanity became a force for extinction—that there were just two ways to wipe out life on Earth: an asteroid strike or massive volcanic eruptions. But 2 years ago, researchers found evidence that in Earth's worst extinction—the end-Permian, 252 million years ago—volcanoes lofted Siberian salt deposits into the stratosphere, where they might have fed chemical reactions that obliterated the ozone layer and sterilized whole forests. Now, spores from the end-Devonian make a compelling case that, even without eruptions, a warming climate can deplete the ozone layer, says Lauren Sallan, a paleobiologist at the University of Pennsylvania. “Because the evidence is so strong, it will make people rethink other mass extinction events.”

The end-Devonian die-off has long sat in the shadow of the Late Devonian extinction 12 million years earlier, one of the planet's largest. Likely driven by volcanoes that emitted gases that drastically cooled and warmed the planet, it killed most corals and many shelled sea creatures. But 10 years ago, work by Sallan and others revealed the end-Devonian was mighty in its own right, wiping out many plants and vertebrates, including most tetrapods, the four-limbed fish that had begun to evolve fingers and toes. Only the five-toed tetrapods survived. “It resets our own evolution,” Marshall says. “All these archaic lineages, it kicked them out of the frame.”

What the end-Devonian lacked was a cause. There was no evidence for volcanism or a giant impact, but one alluring clue was seen in the rapid formation and disappearance of rock deposits associated with glaciers, Sallan says. “Something was really screwed up with climate at that time.”

Over the past 3 decades, Marshall has explored rocks surviving from this time in eastern Greenland. At the time, this terrain lay far from the arctic, at lower latitudes, locked in the arid interior of a landmass called the Old Red Sandstone Continent. As the climate warmed after the Devonian's last ice age, lakes formed and filled with sediment that slowly turned to mudstone, recording conditions before and during the extinction. In 2017, Marshall exhumed the perfect mudstone in a 6-meter-long drilled core.

It captures a startling transformation: Healthy fossilized spores, coated in distinctive symmetrical spikes, suddenly grow misshapen, their spikes dilapidated and uneven. Spores are a common fossil because of their armored coat, but they are vulnerable to UV radiation, much like humans; spores can even develop a “tan” in response to UV. The damage Marshall saw is consistent with such exposure, says Jeffrey Benca, an experimental paleobotanist who has linked such damage to the end-Permian extinction. “What they propose seems quite plausible,” he says.

Marshall argues that the warming climate drove more powerful summer thunderstorms, which could have injected an ozone-depleting mix of water and salts into the stratosphere. As UV rays killed off forests, nutrient runoff into the sea could have caused blooms of plankton and algae, which would have produced more ozone-destroying salts in a runaway feedback. “It looks like it might be a perfect storm,” he says.

Marshall's scenario could explain not just the extinction, but also the many natural gas deposits dating from the period, says Sarah Carmichael, a geochemist at Appalachian State University. They formed from decaying organic matter, but no one has explained the needed surge in plankton growth. Nutrient runoff from dead forests could have fertilized the marine life.

It's also a portent of what could happen in today's warming world, where more powerful thunderstorms sometimes “overshoot” the troposphere and inject moisture into the dry, cold stratosphere. When combined with aerosol particles and chlorine molecules, the moisture may eat away ozone (Science, 26 April 2019, p. 322).

But atmospheric scientists can barely agree on whether these ozone depletions are happening now, let alone hundreds of millions of years ago. More overshoots occur now than expected, but whether they are spurring damaging reactions is not yet clear. Elliot Atlas, an atmospheric chemist at the University of Miami who studies this dynamic, is skeptical of Marshall's theory. It needs much more rigorous testing in models, he says. “Is it impossible? I can't say that.”

Carmichael, for her part, would like to see evidence beyond the pollen grains that UV drove the extinction. “I'm wary of saying UV radiation is the reason,” she says. “But I think it's a reason.”

Vorrath, M.-E., Müller, J., Rebolledo, L., Cárdenas, P., Shi, X., Esper, O., Opel, T., Geibert, W., Muñoz, P., Haas, C., Lange, C.B., Lohmann, G., Mollenhauer, G., 2020. Sea ice dynamics at the Western Antarctic Peninsula during the industrial era: a multi-proxy intercomparison study. Climate of the Past Discussions 2020, 1-43.


In the last decades, changing climate conditions have had a severe impact on sea ice at the Western Antarctic Peninsula (WAP), an area rapidly transforming under global warming. To study the development of spring sea ice and environmental conditions in the pre-satellite era we investigated three short marine sediment cores for their biomarker inventory with particular focus on the sea ice proxy IPSO25 and micropaleontological proxies. The core sites in the Bransfield Strait are located in shelf to deep basin areas characterized by a complex oceanographic frontal system, coastal influence and sensitivity to large-scale atmospheric circulation patterns. We analyzed geochemical bulk parameters, biomarkers (highly branched isoprenoids, glycerol dialkyl glycerol tetraethers, sterols), and diatom abundances and diversity over the past 200 years (210Pb dating), and compared them to observational data, sedimentary and ice core climate archives as well as results from numerical models. Based on biomarkers we could identify four different stratigraphic units with (1) stable conditions and moderate sea ice cover before 1860, (2) low to moderate sea ice cover between 1860 and 1930, (3) high seasonal variability and changes in sea ice regimes from 1930 to 1990 and (4) a shift to increasing sea ice cover despite anthropogenic warming since 1990. Although IPSO25 concentrations correspond quite well with satellite sea ice observations for the past 40 years, we note discrepancies between the biomarker-based sea ice estimates and the long-term model output for the past 200 years, ice core records and reconstructed atmospheric circulation patterns such as El Niño Southern Oscillation (ENSO) and Southern Annular Mode (SAM). We propose that the sea ice biomarker proxies IPSO25 and PIPSO25 are not linearly related to sea ice cover and, additionally, each core site reflects specific, local environmental conditions. High IPSO25 and PIPSO25 values may not be directly interpreted as referring to high spring sea ice cover because variable sea ice conditions and enhanced nutrient supply may affect the production of both the sea-ice associated and phytoplankton-derived (open marine, pelagic) biomarker lipids. For a more meaningful interpretation we recommend to carefully consider individually biomarker records to distinguish between cold, sea ice favoring and warm, sea ice diminishing environmental conditions.


https://doi.org/10.1038/s41598-020-65018-9

Active methane seepage occurs congruent with a high density of up to 1 km-wide and 35 m deep seafloor craters (>100 craters within 700 km2 area) within lithified sedimentary rocks in the northern Barents Sea. The crater origin has been hypothesized to be related to rapid gas hydrate dissociation and methane release around 15–12 ka BP, but the geological setting that enabled and possibly controlled the formation of craters has not yet been addressed. To investigate the geological setting beneath the craters in detail, we acquired high-resolution 3D seismic data. The data reveals that craters occur within ~250–230 Myr old fault zones. Fault intersections and fault planes typically define the crater perimeters. Mapping the seismic stratigraphy and fault displacements beneath the

craters we suggest that the craters are fault-bounded collapse structures. The fault pattern controlled the craters occurrences, size and geometry. We propose that this Triassic fault system acted as a suite of methane migration conduits and was the prerequisite step for further seafloor deformations triggered by rapid gas hydrate dissociation some 15–12 ka BP. Similar processes leading to methane releases and fault bounded subsidence (crater-formation) may take place in areas where contemporary ice masses are retreating across faulted bedrocks with underlying shallow carbon reservoirs.

Walters, A.P., Meyers, S.R., Carroll, A.R., Hill, T.R., Vanden Berg, M.D., 2020. Lacustrine cyclicity in the early Eocene Green River Formation, Uinta Basin, Utah: Evidence from X-ray fluorescence core scanning. Journal of Sedimentary Research 90, 429-447.

https://doi.org/10.2110/jsr.2020.24

The Green River Formation preserves an extraordinary archive of terrestrial paleoclimate during the Early Eocene Climatic Optimum (EECO; ∼ 53–50 Ma), expressing multiple scales of sedimentary cyclicity previously interpreted to reflect annual to Milankovitch-scale forcing. Here we utilize X-ray fluorescence (XRF) core scanning and micro X-ray fluorescence (micro-XRF) scanning in combination with radioisotopic age data to evaluate a rock core record of laminated oil shale and carbonate mudstone from Utah's Uinta Basin, with the parallel objectives of elucidating the paleo-environmental significance of the sedimentary rhythms, testing a range of forcing hypotheses, and evaluating potential linkages between high- and low-frequency forcing. This new assessment reveals that the ∼ 100-μm-scale laminae—the most fundamental rhythm of the Green River Formation—are most strongly expressed by variations in abundance of iron and sulfur. We propose that these variations reflect changes in redox state, consistent with annual stratification of the lake. In contrast to previous studies, no support was found for ENSO or sunspotcycles. However, millimeter- to centimeter-scale rhythms—temporally constrained to the decadal to centennial scale—are strongly expressed as alternations in the abundance of silicate- versus carbonate-associated elements (e.g., Al and Si vs. Ca), suggesting changes in precipitation and sediment delivery to the paleo-lake. Variations also occur at the meter scale, defining an approximate 4 m cycle interpreted to reflect precession. We also identify punctuated intervals, associated principally with one phase of the proposed precession cycle, where Si disconnects from the silicate input. We propose an alternative authigenic or biogenic Si source for these intervals, which reflects periods of enhanced productivity. This result reveals how long-term astronomical forcings can influence short-term processes, yielding insight into decadal- to millennial-scale terrestrial climate change in the Eocene greenhouse earth.

Wan, X., Rasouli, V., Damjanac, B., Yu, W., Xie, H., Li, N., Rabiei, M., Miao, J., Liu, M., 2020. Coupling of fracture model with reservoir simulation to simulate shale gas production with complex fractures and nanopores. Journal of Petroleum Science and Engineering 193, 107422.


A novel integrated approach that couples hydraulic fracturing and production simulation was proposed for Marcellus shale gas reservoir. A discrete element method based hydraulic fracturing simulator was utilized for multi-stage hydraulic fracturing simulation. Moving tip clustering (MTC) and linear regression clustering (LRC) algorithms were proposed to characterize the complex

fracture geometry. Embedded discrete fracture model method was used to transfer the complex geometry of multiple fractures into a third-party reservoir simulator for history matching of shale gas production and production forecasting. It was observed that the LRC algorithm can generate smooth fracture geometries and detect overall fracture paths reasonably. The MTC algorithm, however, can capture more branches of microcracks and recover zig-zag fracture paths with larger apparent fracture lengths. The zig-zag fractures contribute to larger stimulated reservoir volume and result in an extra shale gas production of 5.2% compared to the smooth fractures. The gas slippage effect increases apparent matrix permeability to 4.6 times of intrinsic permeability. Reduction of fracture conductivity and matrix permeability due to decreasing bottomhole pressure leads to 9.25% and 9.28% decrease of gas production respectively in 30 years and should be taken into account for long-term production prediction.

Wang, C., Lo Cascio, M., Liang, Y., Xu, W., 2020. An experimental study of peridotite dissolution in eclogite-derived melts: Implications for styles of melt-rock interaction in lithospheric mantle beneath the North China Craton. Geochimica et Cosmochimica Acta 278, 157-176.


Interaction between eclogite-derived melt and peridotite has played an important role in modifying the cratonic lithospheric mantle and generation of high-Mg igneous rocks. To better understand the effect of peridotite physical state on melt-peridotite interaction, we conducted reaction experiments of lherzolite with two basaltic andesites and a ferro-basalt at temperatures of 1300 °C, 1375 °C, and 1425 °C and a pressure of 2 GPa using the reaction couple method. At 1300 °C, when lherzolite is subsolidus, its dissolution rate is slow, and it is mineralogically and texturally unchanged. Garnet and clinopyroxene precipitate at the melt-rock interface. The low-temperature reaction enriches the melt with SiO2 and Na2O, and depletes the melt with Al2O3, FeO, and CaO. At 1375 °C and 1425 °C, when the lherzolite is partially molten, the dissolution and re-equilibration rates are fast due to grain-scale process that involves dissolution, precipitation, and reprecipitation. Dissolution of olivine and precipitation of orthopyroxene produce a melt-bearing orthopyroxene-rich lithology at the melt-rock interface followed by a melt-bearing harzburgite and a melt-bearing lherzolite. The lithology near the interface can be an orthopyroxene-rich harzburgite or an orthopyroxenite depending on the reacting melt composition. The high-temperature reaction produces melt with increased MgO, FeO, CaO, and Mg#, and decreased SiO2, Al2O3, and Na2O. The dissolution rate obtained from the experiments is used to assess the survival of mantle xenoliths in the early Cretaceous high-Mg diorites. Combined with field observations from mantle samples, the experimental results provide insight into the style of eclogite-derived melt and peridotite interaction in the lithospheric mantle beneath the North China Craton. At the lithosphere-asthenosphere boundary, the reaction is dominated by the high-temperature regime, which produces orthopyroxene-rich lithologies such as orthopyroxene-rich harzburgite and orthopyroxenite-veined peridotite. Above the lithosphere-asthenosphere boundary where peridotite is subsolidus, the reaction is characterized by the low-temperature regime, which produces garnet-bearing or garnet-rich lithologies such as garnet pyroxenite, garnetite, and high-Mg granulite. Interactions between eclogite-derived melts and peridotite in the two regimes are responsible for the geochemical features of the early Cretaceous high-Mg igneous rocks from the North China Craton.

Wang, D., Guo, W., Kong, S., Xu, T., 2020. Estimating offshore exposure to oil spill impacts based on a statistical forecast model. Marine Pollution Bulletin 156, 111213.


A statistical oil spill risk forecast model in support of emergency response and environmental risk assessment is presented by combing the deterministic model, probabilistic strategy and frequency estimation. When applied to evaluate various potential spill sources (oil port, fairway, anchorage and pipeline) in the Zhoushan offshore area, the model provides the probability of slick spatial position, oil slick thickness, and exposure duration of floating slick. An oil spill risk map is generated after integrating multiple spill sources, which is a powerful tool for identifying high-risk areas and developing contingency plan. Impact scope and damage degree vary among different sources because of special local topographical, hydrological, and meteorological conditions, where generally exists high pollution intensity of point-source and wide range of line-source. Huge Changjiang River runoff prevents coastal sea in the north from being contaminated by spilled oil from the southern Zhoushan offshore area.

Wang, D., Wang, K., Zheng, X., Butterbach-Bahl, K., Díaz-Pinés, E., Chen, H., 2020. Applicability of a gas analyzer with dual quantum cascade lasers for simultaneous measurements of N2O, CH4 and CO2 fluxes from cropland using the eddy covariance technique. Science of The Total Environment 729, 138784.


We evaluated the applicability of a closed-path gas analyzer with two mid-infrared quantum cascade lasers (QCLs) for simultaneous measurement of nitrous oxide (N2O), methane (CH4) and carbon dioxide (CO2) fluxes from a cropland using the eddy covariance (EC) technique. The measurements were carried out in a typical vegetable field in the subtropical China during the wintertime, when the gas fluxes are at their lowest level in the year. A new approach was proposed to optimize the determination of lag times between the wind and gas concentration data, which was proven efficient to increase the reliability of the measured fluxes when the gas exchanges are weak. The dual-QCL analyzer showed a median precision (1σ) of 0.14 nmol mol−1 for N2O, 3.3 nmol mol−1 for CH4 and 0.36 μmol mol−1 for CO2 at sampling frequency of 10 Hz under the field conditions. Such precisions are better than, or comparable with, those of other commonly used closed-path or open-path gas analyzers, which are capable of measuring ony one or two ot the three gases. The detection limit of the EC system for measuring half-hourly fluxes were 0.05 nmol m−2 s−1 for N2O, 1.12 nmol m−2

s−1 for CH4 and 0.14 μmol m−2 s−1 for CO2. The results showed that 100% of the N2O, 85% of the CH4 and 96% of the CO2 fluxes were larger than the above detection limits. This study suggests that the EC technique using a closed-path gas analyzer with two quantum cascade lasers is qualified for reliable and simultaneous measurements of N2O, CH4 and CO2 fluxes from a subtropical cropland throughout the year. Moreover, EC method based on this type of gas analyzer provides an additional option for long-term and simultaneous flux measurements of the three greenhouse gases in a wide range of agricultural and natural ecosystems.

Wang, G., Qin, Y., Xie, Y., Wang, Z., Wang, B., Wang, Q., Zhang, X., 2020. Cyclic characteristics of the physical properties of key strata in CBM systems controlled by sequence stratigraphy—an example from the Gujiao Block. Acta Geologica Sinica - English Edition 94, 444-455.

https://doi.org/10.1111/1755-6724.14300

Multiple coal seams and interbedded rock assemblages formed in vertical progression due to the influence of multiple stages of sea level transgressions. Based on mercury injection experiment, low temperature liquid nitrogen experiment, porosity and permeability experiment and breakthrough pressure experiment, the vertical variation characteristics of coal bearing strata in Gujiao block are ‐explained in detail. The results of the mercury injection and low temperature liquid nitrogen experiments show that the pore structure characteristics fluctuate with increasing depth in the strata, with fewer micropores followed by transition pores. The BET specific surface area and average pore diameter of the Shanxi Formation are generally larger than those of the Taiyuan Formation. Due to the continuous cyclic sequence stratigraphy changes, the porosity, permeability, breakthrough pressure and breakthrough time of the samples show a certain cyclicity. Within the same sequence, the porosity is larger, and the permeability is smaller near the maximum flooding surface. Although the permeability of the sandstone samples is higher, the porosity is lower, and the breakthrough pressure and breakthrough times are greater. The strata in the study area formed in an oxidized environment that was affected by freshwater, and the pore structure of different lithologies is quite different. After the formation of sandstone, the intergranular pores generally underwent filling with secondary quartz, clay minerals and organic matter, resulting in low porosity and permeability.

Wang, H., Lhotka, H.R., Bennett, R., Potapenko, M., Pickens, C.J., Mann, B.F., Haidar Ahmad, I.A., Regalado, E.L., 2020. Introducing online multicolumn two-dimensional liquid chromatography screening for facile selection of stationary and mobile phase conditions in both dimensions. Journal of Chromatography A 1622, 460895.


Baseline separation and analysis of multicomponent mixtures of closely related pharmaceuticals using single column selectivity can often be challenging, requiring the combination of orthogonal stationary and mobile phase methods to monitor all the species and optimize reaction outcomes. In recent years, two-dimensional liquid chromatography (2D-LC) has become a valuable tool for improving peak capacity and selectivity. Though powerful, standard 2D-LC instrumentation and software can often lead to tedious method development and has a requirement for very specific expertise that is poorly suited for a fast-paced industrial environment. In this regard, the introduction of an automated online 2D-LC setup that could screen multiple columns in both dimensions without manual intervention will undeniably serve to streamline column/mobile phase selection and secure the viability of 2D-LC as a mainstay instrument for industrial applications. Herein, we introduce and investigate a multicolumn online 2D-LC approach that simplifies column screening and method development dramatically. This setup incorporates 6-position column selection valve technology whose functionality enables us to combine multiple columns in the first and second dimensions. This strategy in conjunction with diode array detection (DAD) in both dimensions and mass spectrometry (MS) acquisition in the second dimension serves to explore different columns and mobile phases as a framework for screening targeted compounds in multicomponent mixtures without having to perform chromatographic purification. Multiple online heart cutting achiral RPLC – achiral RPLC and achiral RPLC – chiral RPLC coupled to DAD and ESI-MS methods combining several stationary phase selectivity in an automated fashion are successfully applied to the separation and analysis of complex mixtures of drug substances, where in many instances, traditional 1D-ultra-high performance liquid chromatography (UHPLC) fails or delivers sub-optimal results. This automated online multicolumn 2D-LC workflow enables rapid and efficient

identification of column/eluent combinations, as well as sample analysis across multiple columns in both dimensions overnight with a single click.

Wang, J., Jaeger, P., Samara, H., Ryan, D., 2020. Simultaneous evaluation of time-dependent phase and wetting properties of hydrocarbon liquids for CO2-enhanced recovery of oil and gas from tight reservoirs. Energy & Fuels 34, 5128-5134.


A new method is presented for simultaneous observation of time-dependent interfacial and wetting behavior for a system of hydrocarbon liquids, water, rock sample, and CO2. Application of this method for assessment of using CO2 to enhance oil and gas recovery from water-rich tight reservoirs is discussed with exemplary results. The discussion includes predicting time evolution of capillary pressure in tight rocks and swelling of liquid hydrocarbons trapped by water, and estimating the composition of the liquid phase composed by the trapped hydrocarbons and CO2 transferred through the water barrier.

Wang, J., Liu, J., Zhang, H., Zhang, H., Li, Y., 2020. Metamorphism, geochemistry, and carbon source on sedimentary-metamorphic graphite deposits in eastern Shandong, China. Geological Journal 55, 3748-3769.


Eastern Shandong is one of the most economically important regions for ore-producing sedimentary-metamorphic graphite deposits in China. The Liugezhuang and Daliangzikou graphite deposits in the Pingdu?Laixi Graphite Belt are typical examples. The ores in the Liugezhuang deposit and Daliangzikou deposit are typically gneiss/granulite type and biotite granulite type, respectively. Graphite occurs as stratabound layers of slender flakes associated with biotite, clinopyroxene, and plagioclase and as slender flakes and disseminated grains associated with biotite and filling tiny fractures in mineral grains. The mineral associations indicate that the ore rocks can be classified into four metamorphic facies: (a) amphibolite granulite facies, Cpx (Hy) + Opx (Di) + Pl ± Hbl ± Qz; (b) amphibolite facies, Hbl + Pl + Cpx (Opm) + Ep + Bt + Ms + Qz ± Chl ± Mic; (c) high-grade greenshist facies, Hbl + Pl + Ep + Bt + Chl + Qz ± Cpx; and (d) low-grade greenshist facies, Ep + Chl + Pl + Bt + Ms + Chl + Qz + Rt. Study of the variation in graphite crystals and fixed carbon with increasing metamorphic grade suggests that more than one metamorphism process (graphitization) occurred during ore formation. Geochemical analysis indicates that the primary condition under which the Liugezhuang and Daliangzikou graphite deposits formed was a marine facies sedimentary environment of which the material source was terrestrial weathering detritus and compounds and also a participation of terrestrial material in the graphite deposits. Trace element data suggest that the sedimentary condition was from a reducing condition in the Liugezhuang graphite deposit to a weaker reducing condition in the Daliangzikou graphite deposit, whereas samples from a Jingshan Group stratum show multiple oxidation?reduction conditions but dominantly oxidation. Carbon isotope analysis indicates that the carbon source of the Liugezhuang graphite deposit was organic, whereas that of the Daliangzikou graphite deposit was mainly organic carbon but with some inorganic participation.

Wang, J., Zhang, L., Lian, S., Qin, Z., Zhu, X., Dai, X., Huang, Z., Ke, C., Zhou, Z., Wei, J., Liu, P., Hu, N., Zeng, Q., Dong, B., Dong, Y., Kong, D., Zhang, Z., Liu, S., Xia, Y., Li, Y., Zhao, L., Xing, Q., Huang, X., Hu, X., Bao, Z., Wang, S., 2020. Evolutionary transcriptomics of metazoan biphasic life cycle supports a single intercalation origin of metazoan larvae. Nature Ecology & Evolution 4, 725-736.

https://doi.org/10.1038/s41559-020-1138-1

The transient larva-bearing biphasic life cycle is the hallmark of many metazoan phyla, but how metazoan larvae originated remains a major enigma in animal evolution. There are two hypotheses for larval origin. The ‘larva-first’ hypothesis suggests that the first metazoans were similar to extant larvae, with later evolution of the adult-added biphasic life cycle; the ‘adult-first’ hypothesis suggests that the first metazoans were adult forms, with the biphasic life cycle arising later via larval intercalation. Here, we investigate the evolutionary origin of primary larvae by conducting ontogenetic transcriptome profiling for Mollusca—the largest marine phylum characterized by a trochophore larval stage and highly variable adult forms. We reveal that trochophore larvae exhibit rapid transcriptome evolution with extraordinary incorporation of novel genes (potentially contributing to adult shell evolution), and that cell signalling/communication genes (for example, caveolin and innexin) are probably crucial for larval evolution. Transcriptome age analysis of eight metazoan species reveals the wide presence of young larval transcriptomes in both trochozoans and other major metazoan lineages, therefore arguing against the prevailing larva-first hypothesis. Our findings support an adult-first evolutionary scenario with a single metazoan larval intercalation, and suggest that the first appearance of proto-larva probably occurred after the divergence of direct-developing Ctenophora from a metazoan ancestor.



The hydrogen transfer reaction is one of the key chemical processes of coal conversion. The elucidation of the hydrogen transfer mechanism is essential for rational control of the properties and distribution of products. This paper is focused on the hydrogen transfer mechanism of lignite modification in a subcritical D2O–CO system. Using Soxhlet extraction, isotope ratio mass spectrometry, 1H nuclear magnetic resonance, and pyrolysis–gas chromatography–mass spectrometry (Py-GCMS), the deuterium transfer routes in deuterated products and their representative structures were studied. The existing form of deuterium in deuterated products was also proposed. The results showed that the subcritical D2O–CO system can generate active deuterium, which combines with the free radical fragments resulting from coal pyrolysis to form three kinds of deuterated products: n-hexane solute (NS-D), benzene solute (BS-D), and tetrahydrofuran solute (TS-D). Deuterium in the three solutes migrates in the order TS-D → BS-D → NS-D. It was observed that the active deuterium is not transferred to the β sites of the solutes but rather to their ar, α,2, α, and γ sites. Py-GCMS detection results showed that the solutes mainly consist of six representative structures, that is, monocyclic and polycyclic aromatics, alkenes, alkanes, alcohols, and esters. In the modification process, deuterium is incorporated into the monocyclic aromatic structures in the aliphatic side chains first and then in the aromatic ring. For the polycyclic aromatic structures, the active deuterium enters the side chain first and then the aromatic ring having that side chain. A small amount of active deuterium can be incorporated into

the alkene and alkane structures directly. However, it mainly transfers to such structures indirectly through thermal cracking of deuterium-containing macromolecular aromatic structures. Active deuterium reduces oxygen in the oxygen-containing structures to form OD or DHO, yet it cannot easily enter the aliphatic and aromatic structures linked to the oxygen-containing structures. This research provides a new perspective for the study of hydrogen transfer routes and can serve as a reference for discussing the molecular mechanisms involved in various coal conversion processes.

Wang, Q., Zheng, J., Sun, B., Ma, F., Wang, Z., Wang, W., 2020. Carbon isotope and paleoclimatic implications of three plants from the Oligocene Ningming Formation, Guangxi Acta Sedimentologica Sinica 38, 358-366 http://www.cjxb.ac.cn/EN/abstract/abstract4098.shtml

The Oligocene represented an early "icehouse" epoch and is a significant period in which global climates and organisms had pronounced evolutions. Carbon isotope data for plant fossils from the Oligocene strata records the evolution of contemporaneous climates. Three plants from the Oligocene Ningming Formation in Guangxi were selected for carbon isotope analysis,along with their nearest living relatives(NLRs). The carbon isotope composition(δ13C) values of the fossil plants Buxus ningmingensis,Chuniophoenix slenderifolia and Cephalotaxus ningmingensis were -29.0‰,-28.3‰,-28.0‰,with carbon isotope discrimination(Δ13C)values 23.48‰,22.74‰,22.43‰ and Cplant/Cair ratios(intra-leaf CO2:atmospheric CO2)0.84,0.81,0.80. Their water-use efficiency(WUE)were 42.63 μmol CO2/mol H2O,51.56 μmol CO2/mol H2O,55.38 μmol CO2/mol H2O. δ13C values of their NLRs were -27.9‰,-29.7‰,-28.8‰,with Δ13C values 20.47‰,22.36‰,21.42‰,Cplant/Cair ratios 0.71,0.79,0.75 and WUE 72.22 μmol CO2/mol H2O,51.28 μmol CO2/mol H2O,61.76 μmol CO2/mol H2O. The carbon isotope analysis shows that δ13C values of the three fossil plants were within the range of δ13C of extant C3 plants,and their Δ13C and Cplant/Cair also showed higher values than their NLRs. The WUE values of Buxus ningmingensis and Cephalotaxus ningmingensis were lower than their NLRs;WUE of Chuniophoenix slenderifolia is slightly higher than its NLR(C. hainanensis),which may have grown in a wetland environment alongside a small stream or lake. The δ13C, Cplant/Cair and WUE values all suggest that the fossil plants may have lived in a warmer and wetter climate. This is supported by paleoclimatic reconstruction based on the three fossil taxa and other plant fossils from the same horizon.



Perfluoroalkyl substances (PFASs) are persistent chemicals in the environment. So far, little is known about their uptake potential in wetland plants. Here, we investigated the uptake and translocation of perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) in eight common wetland plants, namely, Canna indica (Ci), Thalia dealbata (Td), Cyperus alternifolius (Ca), Phragmites australis (Pa), Arundo donax (Ad), Pontederia cordata (Pc), Cyperus papyrus (Cp), and Alisma orientale (Ao) by hydroponic experiments and visualized their tissue- and cell-level distribution with desorption electrospray ionization mass spectrometry (DESI-MS) and transmission electron microscopy equipped with energy-dispersive spectroscopy (TEM-EDS). The results showed that the

PFASs accumulated in plants accounted for 1.67–16.7% of the total mass spiked into the hydroponic systems, and PFOS accumulated largely in roots (48.8–95.8%), while PFOA was stored mostly in the aboveground part (29.3–77.4%). DESI-MS and TEM-EDS analysis showed that PFASs in Ci, Td, Pa, and Ca were transported from the hydroponic solution to the root cortex via both apoplastic (e.g., across cell walls and/or intercellular spaces) and symplastic routes (e.g., across plasma membranes or via plasmodesmata) and further to the vascular bundle via symplastic route in Td and Pa and via both routes in Ci and Ca. These two chemicals were transported from roots to stems mainly through the cortex in Td and through both the cortex and vascular bundles in Ci and Ca.



Soil organic carbon (SOC) stored in permafrost across the high-latitude/altitude Northern Hemisphere represents an important potential carbon source under future warming. Here, we provide a comprehensive investigation on the spatiotemporal dynamics of SOC over the high-altitude Tibetan Plateau (TP), which has received less attention compared with the circum-Arctic region. The permafrost region covers ~42% of the entire TP and contains ~37.21 Pg perennially frozen SOC at the baseline period (2006–2015). With continuous warming, the active layer is projected to further deepen, resulting in ~1.86 ± 0.49 Pg and ~3.80 ± 0.76 Pg permafrost carbon thawing by 2100 under moderate and high representative concentration pathways (RCP4.5 and RCP8.5), respectively. This could largely offset the regional carbon sink and even potentially turn the region into a net carbon source. Our findings also highlight the importance of deep permafrost thawing that is generally ignored in current Earth system models.

Wang, T., Zhang, D.-L., Yang, X.-Y., Xu, J.-Q., Matthew, C., Tang, Y.-J., 2020. Light hydrocarbon geochemistry: insight into oils/condensates families and inferred source rocks of the Woodford–Mississippian tight oil play in North-Central Oklahoma, USA. Petroleum Science 17, 582-597.

https://doi.org/10.1007/s12182-020-00441-1

The Woodford–Mississippian “Commingled Production” is a prolific unconventional hydrocarbon play in Oklahoma, USA. The tight reservoirs feature variations in produced fluid chemistry usually explained by different possible source rocks. Such chemical variations are regularly obtained from bulk, molecular, and isotopic characteristics. In this study, we present a new geochemical investigation of gasoline range hydrocarbons, biomarkers, and diamondoids in oils from Mississippian carbonate and Woodford Shale. A set of oil/condensate samples were examined using high-performance gas chromatography and mass spectrometry. The result of the condensates from the Anadarko Basin shows a distinct geochemical fingerprint reflected in light hydrocarbon characterized by heptane star diagrams, convinced by biomarker characteristics and diamantane isomeric distributions. Two possible source rocks were identified, the Woodford Shale and Mississippian mudrocks, with a variable degree of mixing. Thermal maturity based on light hydrocarbon parameters indicates that condensates from the Anadarko Basin are of the highest maturity, followed by “Old” Woodford-sourced oils and central Oklahoma tight oils. These geochemical parameters shed light on petroleum migration within Devonian–Mississippian petroleum systems and mitigate geological risk in exploring and developing petroleum reservoirs.

Wang, Y.-F., Wang, L.-B., Li, Y., Gu, J.-X., Sun, C.-Y., Chen, G.-J., Wang, X.-H., Yuan, Q., Li, N., 2020. Effect of temperature on gas production from hydrate-bearing sediments by using a large 196-L reactor. Fuel 275, 117963.


Methane hydrate exploitation via depressurization for a reservoir with a bottom gas-rich zone was simulated using a large-sized three-dimensional hydrate simulator. A single vertical well system and a system with a combination of vertical and horizontal wells were employed to elucidate the different effects of horizontal and vertical wells on the exploitation process. The results showed that effect of promoting gas production using a horizontal well is not obvious for a high permeability reservoir. A large exploitation temperature drop may lead to ice blockage in the pipelines, and fracturing technology was introduced to solve this blockage problem. Experiments performed above and below the freezing point inferred that the decomposition of the hydrate in different areas of the reactor was not simultaneous, according to analysis of the temperature distribution of the entire reactor during the exploitation process. For exploitation above the freezing point, temperatures in the bottom of the reactor tend to maintain a low level and work against hydrate decomposition. However, for exploitation below the freezing point, the low-temperature area in the bottom of the reactor preferentially converts to ice. Heat release and salt precipitation promoted hydrate decomposition, and the decomposition rate was significantly accelerated.

Wang, Y., Cao, J., Jin, J., Zhang, J., Hu, G., Zhou, N., Shi, T., 2020. Diverse oil and gas seeps in the southern Junggar Basin, NW China (piedmont Northern Tian Shan): Origins and links to tectono-sedimentary evolution. Geological Journal 55, 3497-3521.


The southern Junggar Basin in NW China is a world class location for the study of oil and gas seeps, ‐with widely distributed, highly variable oil and gas seeps including gaseous mud volcanoes, liquid oil seeps, and solid bitumen deposits. However, the sources and origins of these seeps are poorly understood, as there are many potential source sequences of Permian to Paleogene age. The uncertainty surrounding the seeps means that it has not been possible to address their significance for oil and gas exploration in the area, and they are not understood in the context of the tectono‐sedimentary evolution of the basin within the piedmont region of the northern Tian Shan Mountains (in the eastern part of the Central Asian Orogenic Belt, CAOB). In the present study, these issues were addressed using combined geological and geochemical methods. Results show that there are five main types of seeps in the region from west to east. Type A seeps originate from Jurassic source rocks and are best represented by the A'erqingou mud volcano. Type B seeps originate mainly from Paleogene source rocks but also contain a Jurassic sourced component; they are best represented ‐by the Dushanzi mud volcano. Type C seeps originate from a Cretaceous source and are best represented by the South Anjihai and Horgos oil sands. Type D seeps originate mainly from Jurassic source rocks but also contain a Triassic sourced component; they are best represented by the Qigu ‐oil seep. Type E seeps originate from Permian source rocks and are best represented by the Dalongkou bituminous deposit. The primary controls on seep distribution are both sedimentological (deposition of source rock) and tectonic (faulting). The position and burial history of sedimentary centres controlled the distribution and maturation of source rocks. Tectonic faults provided

migration pathways and traps for the oil and gas. The results of this study will help to reduce uncertainty during exploration for oil and gas in the area. The findings also have general implications for petroleum systems and exploration in the piedmont areas of foreland basins worldwide.



The Dongying depression is an important oil-producing area in northeastern China, where the Paleogene Shahejie Formation is the main oil-bearing feature. Although petroleum migration and accumulation in the Dongying depression have been extensively studied, the charging history is still unclear. This paper defines the timeframe of petroleum migration on the basis of a comprehensive investigation of fluid inclusions coupled with basin modeling. According to the petrography and microthermometry of the fluid inclusions, types of fluid inclusion with low-peak-range distributions of the homogenization temperature (Th) (85–95 °C for the Niuzhuang sag and 90–105 °C for the Lijin sag) and high-peak-range Th distributions (105–120 °C for the Niuzhuang sag and 115–130 °C for the Lijin sag) were identified. By recovering the burial and thermal histories of Niuzhuang and Lijin sags with pressure–volume–temperature–composition simulation and one-dimensional basin modeling, it can be inferred that the trapping pressures of two types of hydrocarbon inclusions were higher than the corresponding paleopressure. (42.4 and 42.0 MPa, respectively), indicating rapid hydrocarbon charging resulting from abnormally high pressure. Two hydrocarbon charging events associated with the regional tectonic evolution of the Dongying depression, namely, continuous deposition and tectonics in the Paleogene Dongying Formation (Ed) and rapid deposition and tectonics in the Paleogene Minghuazhen Formation (Em), were inferred. The direction of oil charging was traced from the center to the margin in the north, and from the center to the central fault in the southeastern part of the depression in general, as indicated by the molecular maturity parameters, which roughly coincided with the abnormal pressure.

Wang, Y., Qin, Y., Yang, L., Liu, S., Elsworth, D., Zhang, R., 2020. Organic geochemical and petrographic characteristics of the coal measure source rocks of Pinghu Formation in the Xihu sag of the East China Sea Shelf Basin: Implications for coal measure gas potential. Acta Geologica Sinica - English Edition 94, 364-375.

https://doi.org/10.1111/1755-6724.14303

Coal measure source rocks, located in the Xihu Sag of the East China Sea Shelf Basin, were analyzed to define the hydrocarbon generation potential, organic geochemistry/petrology characteristics, and coal preservation conditions. The Pinghu source rocks in the Xihu Sag are mainly gas prone ‐accompany with condensate oil generation. The coals and shales of the Pinghu Formation are classified from “fair” to “excellent” source rocks with total organic carbon (TOC) contents ranging from 25.2% to 77.2% and 1.29% to 20.9%, respectively. The coals are richer in TOC and S1+S2 than the shales, indicating that the coals have more generation potential per unit mass. Moreover, the kerogen type of the organic matter consists of types II III and III, which the maturity Ro ranges from ‐0.59% to 0.83%. Petrographically, the coals and shales are dominated by vitrinite macerals (69.1%–96.8%) with minor proportions of liptinite (2.5%–17.55%) and inertinite (0.2%–6.2%). The

correlation between maceral composition and S1+S2 indicates that the main contributor to the generation potential is vitrinite. Therefore, the coals and shales of the Pinghu Formation has good hydrocarbon generation potential, which provided a good foundation for coal measure gas accumulation. Furthermore, coal facies models indicates that the Pinghu coal was deposited in limno telmatic environment under high water levels, with low tree density (mainly herbaceous) and ‐with low moderate nutrient supply. Fluctuating water levels and intermittent flooding during the ‐deposition of peat resulted in the inter layering of coal, shale and sandstone, which potentially ‐providing favorable preservation conditions for coal measure gas.

Wang, Z.-Z., Liu, S.-A., Liu, Z.-C., Zheng, Y.-C., Wu, F.-Y., 2020. Extreme Mg and Zn isotope fractionation recorded in the Himalayan leucogranites. Geochimica et Cosmochimica Acta 278, 305-321.


High-silica granites (typically > 70 wt.% SiO2) represent the products of extreme crustal differentiation, but whether their distinctive chemical compositions reflect source lithology or are produced via magmatic differentiation is commonly difficult to discriminate. To provide new insights into this issue, here we present high-precision Mg and Zn isotope data for high-silica, peraluminous leucogranites from the Himalayan orogen. The samples are subdivided into two-mica leucogranite, tourmaline leucogranite and garnet-bearing leucogranite based on their mineral assemblages. The two-mica leucogranites, representing the least evolved Himalayan leucogranites, have similar δ66ZnJMC 3-0749L (mean = 0.31 ± 0.06‰) but heavier δ26MgDSM-3 values (mean = −0.01 ± 0.12‰) relative to more mafic igneous rocks. This indicates that they were formed by anatexis of weathered silicates, consistent with the well-acknowledged metasedimentary source of the Himalayan leucogranites. In contrast, the more evolved tourmaline leucogranites and garnet-bearing leucogranites have lower δ26Mg and higher δ66Zn values compared with the two-mica leucogranites. The extremely low δ26Mg (−1.32‰ to −0.54‰) and high δ66Zn values (0.35–0.69‰) of garnet-bearing leucogranites vary systematically with indices of granitic differentiation (e.g., Zr/Hf, K/Rb, Eu/Eu*, 1/TiO2). Although exsolution of chlorine-rich fluid may result in elevated δ66Zn values, it is unlikely to explain the low δ26Mg signatures of the same samples. Analysis of major Mg-bearing minerals suggests that substantial segregation of tourmaline and/or Fe-Ti oxide could have driven the differentiated leucogranites towards very low δ26Mg values. In this regard, the slightly lower δ26Mg values (mean = −0.17 ± 0.06‰) of tourmaline leucogranites relative to the two-mica leucogranites may also reflect that the former were more differentiated than the latter. Thus, although source heterogeneity may be responsible for the Mg isotopic variations observed in some high-silica granites, our study implies that high-silica granites could be remarkably heterogeneous in terms of Mg isotopes primarily as a result of prolonged fractional crystallization at the late stage of melt evolution. The anomalously light Mg and heavy Zn isotopic signatures of garnet-bearing leucogranites highlight that Mg and Zn isotopes may be treated as important makers of highly fractionated granites in future studies.



Based on drilling cores, thin sections, FIB-SEM and geochemistry data, shale lithofacies in the lowermost part of the Longmaxi-Wufeng Formation were studied in the Southeast Sichuan Basin. This formation is the main shale gas producing layer in Jiaoshiba and its surrounding areas. In this article, with the combination of the three-end-member method (using mineral components) and TOC, six lithofacies, namely, organic-rich siliceous shale, organic-rich mixed shale, organic-rich argillaceous shale, organic-lean siliceous shale, organic-lean mixed shale, and organic-lean argillaceous shale, were identified. Relevant parameters that could represent reservoir quality of the different lithofacies, including porosity, permeability, pore spaces, TOC and gas content, were analyzed and compared. In the end, some of those parameters (e.g., porosity, TOC and gas content), together with special mineral contents (e.g., QMF and clay), were used to establish shale lithofacies evaluation criteria. The results show that organic-rich siliceous shale could be considered as an excellent lithofacies for shale gas and is mainly concentrated in the first section; organic-rich mixed shale, organic-lean siliceous shale and organic-lean mixed shale are assumed to be moderately promising for shale gas, while organic-rich argillaceous shale and organic-lean argillaceous shale are ranked as the least-promising lithofacies in the research area. Consequently, the first section contains the most favorable lithofacies for shale gas exploration.


http://dx.doi.org/10.1039/C9EM00504H

In sunlit waters, photodegradation of dissolved organic matter (DOM) yields completely oxidized carbon (i.e., CO2) as well as a suite of partially oxidized compounds formed from oxygen incorporation (i.e., partial photo-oxidation). Of these two groups of DOM photo-products, more studies focus on CO2 (a greenhouse gas) than on partially oxidized DOM, which is likely a diverse group of compounds with poorly constrained roles in aquatic carbon cycling or biogeochemistry. The objective of this study is to address knowledge gaps on the prevalence, products, and pathways of DOM partial photo-oxidation. Here we traced the photochemical incorporation of isotopically labelled 18O2 into DOM isolated from Alaskan Arctic surface waters using high-resolution mass spectrometry. Complete and partial photo-oxidation of DOM was also quantified as CO2 production and O2 consumption. The majority of 18O-containing partial oxidation photo-products were classified as carboxylic rich alicyclic molecules (CRAM) and overlapped in composition with previously reported photo-products known to result from the oxidation of DOM by singlet oxygen. These results support a previously proposed hypothesis that photo-oxidation by singlet oxygen may contribute to the formation of CRAM, a compound class of DOM ubiquitously observed in surface waters. The novel application of an isotopic tracer for oxygen incorporation with a mass balance approach to quantify complete and partial photo-oxidation of DOM revealed that less than one mol of O2 is required to produce one mol of CO2. A sensitivity analysis based on this new knowledge demonstrated that the magnitude of DOM partial photo-oxidation may be underestimated by up to four-fold. Consequently, partial photo-oxidation likely plays a more prominent role in shaping DOM composition in sunlit waters of the Arctic than previously understood. Therefore, partial photo-oxidation should be increasingly incorporated into the experimental framework of studies focused on DOM composition in surface waters.

Ward, C.P., Overton, E.B., 2020. How the 2010 Deepwater Horizon spill reshaped our understanding of crude oil photochemical weathering at sea: a past, present, and future perspective. Environmental Science: Processes & Impacts 22, 1125-1138.

http://dx.doi.org/10.1039/D0EM00027B

The weathering of crude oil at sea has been researched for nearly half a century. However, there have been relatively few opportunities to validate laboratory-based predictions about the rates, relative importance, and controls of oil weathering processes (e.g., evaporation, photo-oxidation, and emulsification) under natural field conditions. The 2010 Deepwater Horizon (DWH) spill in the Gulf of Mexico provided the oil spill science community with a unique opportunity to evaluate our laboratory-based predictions in nature. With a focus on photochemical weathering, we review what we knew prior to the DWH spill, what we learned from the DWH spill, and what priority gaps in knowledge remain. Three key findings from the DWH spill are discussed. First, the rate and extent of photochemical weathering was much greater for the floating surface oil than expected based on early conceptual models of oil weathering. Second, indirect photochemical processes played a major role in the partial oxidation of the floating surface oil. Third, the extensive and rapid changes to the physical and chemical properties of oil by sunlight may influence oil fate, transport, and the selection of response tools. This review also highlights findings and predictions about photochemical weathering of oil from several decades ago that appear to have escaped the broader scientific narrative and ultimately proved true for the DWH spill. By focusing on these early predictions and synthesizing the numerous findings from the DWH spill, we expect this review will better prepare the oil spill science community to respond to the next big spill in the ocean.

Warke, M.R., Strauss, H., Schröder, S., 2020. Positive cerium anomalies imply pre-GOE redox stratification and manganese oxidation in Paleoproterozoic shallow marine environments. Precambrian Research 344, 105767.


The Paleoproterozoic Koegas Subgroup (Transvaal Supergroup, South Africa) was deposited in the immediate prelude to the Great Oxidation Event (GOE), and can therefore shed light on oceanic paleoredox conditions just before atmospheric oxidation. Manganese enrichments of ~16 wt% in diagenetic kutnahorite horizons suggest that Mn2+ oxidation occurred, either by free O2 or by an ancient photosystem. Iron and molybdenum isotope trends also support the existence of a Mn4+ oxide sediment flux, suggesting that the Koegas basin may have been redox stratified. Evidence from detrital and authigenic pyrite with mass-independently fractionated sulfur isotopes, however, suggests that the atmosphere was devoid of oxygen. To resolve this contradiction, this paper presents new constraints on pathways of Mn2+ oxidation from field, petrographic, stable isotope, and rare earth element and yttrium (REYSN) analysis of stromatolitic carbonates from the upper Koegas Subgroup. Ferroan dolostones and limestones preserve marine REYSN arrays with positive CeSN anomalies. These differences are explained by a redox stratified basin, whereby Mn2+ and Ce3+ are oxidized at a redoxcline and Ce is adsorped onto sinking Mn oxide particles. Mn oxide particles and a negative Ce anomaly from the oxidized upper water column are transferred into carbonates accumulating above the redoxcline. Diagenetic fluids later reduce the Mn oxides to kutnahorite. Below the redoxcline, reduction of Mn oxides enriches carbonates in Mn and a positive Ce anomaly. This contribution adds evidence for the development of oxygen oases and redox-stratified basins before the GOE. Redox stratification was best developed during transgressions. During regressions, a

deltaic system prograded into the Koegas Basin. High sedimentation rates likely allowed for preservation of detrital pyrite only in the deltaic sandstones, thus explaining the contradictory geochemical evidence. No previously unknown ancient photosystem of Mn oxidation is required to explain Mn oxidation.



Macroalgal beds have drawn attention as one of the vegetated coastal ecosystems that act as atmospheric CO2 sinks. Although macroalgal metabolism as well as inorganic and organic carbon flows are important pathways for CO2 uptake by macroalgal beds, the relationships between macroalgal metabolism and associated carbon flows are still poorly understood. In the present study, we investigated carbon flows, including air–water CO2 exchange and budgets of dissolved inorganic carbon, total alkalinity, and dissolved organic carbon (DOC), in a temperate macroalgal bed during the productive months of the year. To assess the key mechanisms responsible for atmospheric CO2 uptake by the macroalgal bed, we estimated macroalgal metabolism and lateral carbon flows (i.e., carbon exchanges between the macroalgal bed and the offshore area) by using field measurements of carbon species, a field-bag method, a degradation experiment, and mass-balance modeling in a temperate Sargassum bed over a diurnal cycle. Our results showed that macroalgal metabolism and lateral carbon flows driven by water exchange affected air–water CO2 exchange in the macroalgal bed and the surrounding waters. Macroalgal metabolism caused overlying waters to contain low concentrations of CO2 and high concentrations of DOC that were efficiently exported offshore from the macroalgal bed. These results indicate that the exported water can potentially lower CO2 concentrations in the offshore surface water and enhance atmospheric CO2 uptake. Furthermore, the Sargassum bed exported 6 %–35 % of the macroalgal net community production (NCP; 302–1378 mmol C m−2 d−1) as DOC to the offshore area. The results of degradation experiments showed that 56 %–78 % of macroalgal DOC was refractory DOC (RDOC) that persisted for 150 d; thus, the Sargassum bed exported 5 %–20 % of the macroalgal NCP as RDOC. Our findings suggest that macroalgal beds in habitats associated with high water exchange rates can create significant CO2 sinks around them and export a substantial amount of DOC to offshore areas.

Way, M.J., Del Genio, A.D., 2020. Venusian habitable climate scenarios: Modeling venus through time and applications to slowly rotating Venus-like exoplanets. Journal of Geophysical Research: Planets 125, e2019JE006276.

https://doi.org/10.1029/2019JE006276

Abstract: One popular view of Venus' climate history describes a world that has spent much of its life with surface liquid water, plate tectonics, and a stable temperate climate. Part of the basis for this optimistic scenario is the high deuterium to hydrogen ratio from the Pioneer Venus mission that was interpreted to imply Venus had a shallow ocean's worth of water throughout much of its history. Another view is that Venus had a long lived (‐ ∼100 million years) primordial magma ocean with a CO2 and steam atmosphere. Venus' long lived steam atmosphere would sufficient time to ‐dissociate most of the water vapor, allow significant hydrogen escape, and oxidize the magma

ocean. A third scenario is that Venus had surface water and habitable conditions early in its history for a short period of time (<1 Gyr), but that a moist/runaway greenhouse took effect because of a gradually warming Sun, leaving the planet desiccated ever since. Using a general circulation model, we demonstrate the viability of the first scenario using the few observational constraints available. We further speculate that large igneous provinces and the global resurfacing hundreds of millions of years ago played key roles in ending the clement period in its history and presenting the Venus we see today. The results have implications for what astronomers term “the habitable zone,” and if Venus like exoplanets exist with clement conditions akin to modern Earth, we propose to place ‐them in what we term the “optimistic Venus zone.”

Plain Language Summary: We have little data on our neighbor Venus to help us understand its climate history. Yet Earth and Venus are sister worlds: They initially formed close to one another and have nearly the same mass and radius. Despite the differences in their current atmospheres and surface temperatures, they likely have similar bulk compositions, making comparison between them extremely valuable for illuminating their distinct climate histories. We analyze our present data on Venus alongside knowledge about Earth's climate history to make a number of exciting claims. Evaluating several snapshots in time over the past 4+ billion years, we show that Venus could have sustained liquid water and moderate temperatures for most of this period. Cloud feedbacks from a slowly rotating world with surface liquid water reservoirs were the keys to keeping the planet clement. Contrast this with its current surface temperature of 450° and an atmosphere dominated by carbon dioxide and nitrogen. Our results demonstrate that it was not the gradual warming of the Sun over the eons that contributed to Venus present hothouse state. Rather, we speculate that large igneous provinces and the global resurfacing hundreds of millions of years ago played key roles in ending the clement period in its history.

Weber, J., Bauersachs, T., Schwark, L., 2020. A multiphasic Younger Dryas cold period recorded in sediments of Lake Steisslingen, SW-Germany: A biomarker perspective. Quaternary International 542, 121-136.


The Younger Dryas (12,680–11,590 yr BP) was the last millennial scale cold event of the Quaternary, when a mean annual temperature decline of 3–5 °C impacted severely on the environment. Whereas pollen distributions document changes in land vegetation, details of limnic ecosystem responses to the cooling event and to its recovery are still not well known. Here, we studied the laminated sediments of Lake Steisslingen (SW-Germany) deposited between 13,500 and 11,100 yr BP in order to investigate the evolution of an aquatic ecosystem. Bulk sediment and organic matter composition mark onset and termination of the Younger Dryas, but remain monotonous through this interval, requiring application of organic and isotope geochemical techniques to follow past ecosystem dynamics. The Younger Dryas is characterized by both an abrupt appearance and demise of long-chain alkenones indicative for haptophyte algae. Based on algal and bacterial biomarker distribution, the Younger Dryas can be divided into three stages, each characterized by the dominance of a microorganism group. The first phase was dominated by nC17 alkanes and hopanoids indicative of cyanophytes and heterotrophic bacteria. The second phase shows a proliferation of cold-adapted haptophyte algae, while in the latest phase highly-branched isoprenoids (HBI) reveal an aquatic community shift towards diatoms. Heterocyte glycolipids document a moderate change in N2-fixing cyanobacterial community structure over the Allerød/Younger Dryas transition but show a marked collapse of the cyanobacteria association at the Younger Dryas/Preboreal climate

recovery. Terrigenic wax lipids indicate significant changes in vegetation between the Allerød, Younger Dryas and Preboreal chronozones but remain homogeneous within the Younger Dryas.

Wheatley, D., Hollingworth, S., Steele, P., Chan, M., 2020. Sedimentology, diagenesis, and reservoir characterization of the Permian White Rim Sandstone, southern Utah: Implications for carbon capture and sequestration potential. American Association of Petroleum Geologists Bulletin 104, 1357-1373.


Rising CO2 emissions have caused scientists and policy makers to explore potential solutions to reduce atmospheric CO2 levels, including carbon capture and sequestration. This project, funded through the Department of Energy CarbonSAFE initiative, aims to characterize the potential storage capacity and preferential fluid-flow pathways through the Permian White Rim Sandstone on and near the San Rafael Swell, Utah, to assess the formation’s viability as a possible CO2 sequestration reservoir. A diverse suite of sedimentological observations and diagenetic analyses was used to assess the White Rim Sandstone’s reservoir potential, including detailed outcrop observations, facies descriptions and ichnology, measured stratigraphic sections with associated correlations, permeability measurements, thin-section petrography, and visible and near-infrared spectroscopy. Stratigraphically, the White Rim Sandstone has two major units separated by a marine transgressive surface. The lower eolian unit is characterized by decimeter- to meter-scale trough cross-bedded grain-flow and wind-ripple facies. The upper reworked, shallow-marine unit has a consistent set of facies at all three field sites: (1) soft-sediment deformation facies (e.g., contorted bedding or clastic pipes), (2) symmetric ripple laminations, (3) bioturbated (dominantly horizontal), and (4) bioturbated (dominantly vertical). This set of four facies represents the transgression of the Permian Kaibab sea over the Permian White Rim coastal dune field.

The outcrop samples and subsurface core samples (∼1561–2243 m deep and ∼33–50 km away from the outcrop localities) experienced different diagenetic fluid-flow histories that drastically impacted the reservoir properties. Outcrop samples have initial quartz overgrowth cements followed by rim-forming calcite cements, iron oxide cements, and occasional oil staining. In contrast, the core samples show significant compaction, followed by quartz overgrowth cementation and a later stage of patchy, large, pore-filling calcite cement that eliminated the porosity and permeability of the potential reservoir (<0.1 md). Outcrop permeability values tend to reflect textural differences in facies, particularly the presence and spacing of internal laminations and bounding surfaces. Facies with fewer internal laminations, such as the grain-flow facies, have higher permeability values than facies with closely spaced internal laminae, such as the wind-ripple facies. Disruption of original bedding (e.g., soft-sediment deformation or bioturbation) alters original depositional textures and creates preferential flow pathways with the potential to increase permeability. Overall, if the diagenesis and resulting low permeability values of the core samples are representative of the White Rim Sandstone at depth, then the White Rim Sandstone would not make a high-quality storage reservoir despite initial, promising outcrop results.



During the Deepwater Horizon oil spill, the unprecedented injection of millions of liters of chemical dispersant at the wellhead generated large quantities of submillimeter oil droplets that became entrained in a deep sea plume. The unexpected generation of these droplets has resulted in many studies in the last decade aiming to understand their transport and fate during and after the spill. Complicating matters, the plume coincided with a microbial bloom, and in addition to ocean dynamics these droplets were subjected to biological processes such as biodegradation and microbial aggregation. A lack of field observations and laboratory experiments using relevant conditions has left our understanding of these biotic processes and the role they played in the fate of the oil droplets poorly constrained. Furthermore, while biodegradation has been incorporated into drop transport models using available data, the effects of microbial aggregation involving extracellular polymeric substances (EPS) on their transport has seldom been incorporated into modeling efforts particularly due to our lack knowledge of these processes. We use a microfluidic platform to observe bacterial suspensions interacting with a single ~200 μm oil drop in conditions relevant to the drop rising through the microbial bloom. We observe the development of individual, invisible bacterial EPS threads extending from the drop surface which can capture additional passing bacteria and form bacteria-EPS aggregates. Using high speed imaging, we make high resolution flow measurements both with and without EPS threads present and analyze the momentum balance to elucidate the hydrodynamic impact of these filaments. Surprisingly, these thin individual EPS filaments alter significantly the pressure field around the drop and increase the drag, which would drastically reduce the drop's rising velocity in the water column. We demonstrate that this mechanism which plausibly occurred in the deep sea plume would have major impacts on both the drop and bacteria transport during and after the Deepwater Horizon oil spill.



Understanding the timing and mechanisms of amino acid synthesis and racemization on asteroidal parent bodies is key to demonstrating how amino acids evolved to be mostly left-handed in living organisms on Earth. It has been postulated that racemization can occur rapidly dependent on several factors, including the pH of the aqueous solution. Here, we conduct nanoscale geochemical analysis of a framboidal magnetite grain within the Tagish Lake carbonaceous chondrite to demonstrate that the interlocking crystal arrangement formed within a sodium-rich, alkaline fluid environment. Notably, we report on the discovery of Na-enriched subgrain boundaries and nanometer-scale Ca and Mg layers surrounding individual framboids. These interstitial coatings would yield a surface charge state of zero in more-alkaline fluids and prevent assimilation of the individual framboids into a single grain. This basic solution would support rapid synthesis and racemization rates on the order of years, suggesting that the low abundances of amino acids in Tagish Lake cannot be ascribed to fluid chemistry.

Wicking, C., Tessarolo, N., Savvoulidi, M., Crouch, J., Collins, I., Couves, J., Kot, E., Banks, N., Hodges, M., Zeng, H., 2020. Sequential extraction and characterization of the organic layer on sandstone reservoir rock surface. Fuel 276, 118062.


Reservoir rocks are partially coated by certain organic molecules (organics) which could have a strong impact on the wettability of the rock and, subsequently, oil recovery. It is important to understand the detailed chemical composition of this “organic layer” in order to design better oil/gas recovery methods. Herein, we report the sequential extraction and the qualitative characterization of the organics from reservoir rocks based on high resolution mass spectrometry (HRMS). The composition of these organics is significantly different from those in the bulk oil. The methodology and findings of this study will be useful for the identification of molecular markers important for enhanced oil recovery.

Wiechmann, A., Ciurus, S., Oswald, F., Seiler, V.N., Müller, V., 2020. It does not always take two to tango: “Syntrophy” via hydrogen cycling in one bacterial cell. The ISME Journal 14, 1561-1570.

https://doi.org/10.1038/s41396-020-0627-1

Interspecies hydrogen transfer in anoxic ecosystems is essential for the complete microbial breakdown of organic matter to methane. Acetogenic bacteria are key players in anaerobic food webs and have been considered as prime candidates for hydrogen cycling. We have tested this hypothesis by mutational analysis of the hydrogenase in the model acetogen Acetobacterium woodii. Hydrogenase-deletion mutants no longer grew on H2 + CO2 or organic substrates such as fructose, lactate, or ethanol. Heterotrophic growth could be restored by addition of molecular hydrogen to the culture, indicating that hydrogen is an intermediate in heterotrophic growth. Indeed, hydrogen production from fructose was detected in a stirred-tank reactor. The mutant grew well on organic substrates plus caffeate, an alternative electron acceptor that does not require molecular hydrogen but NADH as reductant. These data are consistent with the notion that molecular hydrogen is produced from organic substrates and then used as reductant for CO2 reduction. Surprisingly, hydrogen cycling in A. woodii is different from the known modes of interspecies or intraspecies hydrogen cycling. Our data are consistent with a novel type of hydrogen cycling that connects an oxidative and reductive metabolic module in one bacterial cell, “intracellular syntrophy.”

Wignall, P.B., Bond, D.P.G., Grasby, S.E., Pruss, S.B., Peakall, J., 2020. Controls on the formation of microbially induced sedimentary structures and biotic recovery in the Lower Triassic of Arctic Canada. GSA Bulletin 132, 918-930.

https://doi.org/10.1130/B35229.1

Microbially induced sedimentary structures (MISS) are reportedly widespread in the Early Triassic and their occurrence is attributed to either the extinction of marine grazers (allowing mat preservation) during the Permo-Triassic mass extinction or the suppression of grazing due to harsh, oxygen-poor conditions in its aftermath. Here we report on the abundant occurrence of MISS in the Lower Triassic Blind Fiord Formation of the Sverdrup Basin, Arctic Canada. Sedimentological analysis shows that mid-shelf settings were dominated by deposition from cohesive sand-mud flows that

produced heterolithic, rippled sandstone facies that pass down dip into laminated siltstones and ultimately basinal mudrocks. The absence of storm beds and any other “event beds” points to an unusual climatic regime of humid, quiet conditions characterized by near continuous run off. Geochemical proxies for oxygenation (Mo/Al, Th/U, and pyrite framboid analysis) indicate that lower dysoxic conditions prevailed in the basin for much of the Early Triassic. The resultant lack of bioturbation allowed the development and preservation of MISS, including wrinkle structures and bubble textures. The microbial mats responsible for these structures are envisaged to have thrived, on sandy substrates, within the photic zone, in oxygen-poor conditions. The dysoxic history was punctuated by better-oxygenated phases, which coincide with the loss of MISS. Thus, Permo-Triassic boundary and Griesbachian mudrocks from the deepest-water settings have common benthos and a well-developed, tiered burrow profile dominated by Phycosiphon. The presence of the intense burrowing in the earliest Triassic contradicts the notion that bioturbation was severely suppressed at this time due to extinction losses at the end of the Permian. The notion that Early Triassic MISS preservation was caused by the extinction of mat grazers is not tenable.


http://dx.doi.org/10.1039/D0EM00026D

Surface adsorption of two commonly detected emerging contaminants, amlodipine (AMP) and carbamazepine (CBZ), onto model colloidal microplastics, natural organic matter (NOM), and fullerene nanomaterials have been investigated. It is found that AMP accumulation at these colloidal–aqueous interfaces is markedly higher than that of CBZ. Measurements of surface excess and particle zeta potential, along with pH-dependent adsorption studies, reveal a distinct influence of colloidal functional group on the adsorption properties of these pharmaceuticals. AMP shows a clear preference for a surface containing carboxylic group compared to an amine modified surface. CBZ, in contrast, exhibit a pH-dependent surface proclivity for both of these microparticles. The type of interactions and molecular differences with respect to structural rigidity and charge properties explain these observed behaviors. In this work, we also demonstrate a facile approach in fabricating uniform microspheres coated with NOM and C60 nanoclusters. Subsequent binding studies on these surfaces show considerable adsorption on the NOM surface but a minimal uptake of CBZ by C60. Adsorption induced colloidal aggregation was not observed. These findings map out the extent of contaminant removal by colloids of different surface properties available in the aquatic environment. The methodology developed for the adsorption study also opens up the possibility for further investigations into colloidal–contaminant interactions.



Detailed facies characterization in the Wolfcamp B and lower Spraberry intervals of two drill cores in the Midland Basin has yielded five main lithofacies with distinctive physical, chemical, and biologic

attributes. The main attributes for facies identification include lithology and/or mineralogy, texture and/or fabric, porosity, hydrogen index, and total organic carbon content. The methodologies are focused on detailed core description, thin-section petrography, quantitative x-ray diffraction, and field emission scanning electron microscopy (SEM). Porosity data are primarily based on Gas Research Institute (Core Laboratories) measurements and field emission SEM assessment. Moreover, the depositional and diagenetic controls on facies development are addressed to assess the dominant geological processes that govern reservoir quality and distribution.

A model of five end-member facies is proposed to characterize source and reservoir elements through delineating facies tracts. The five end-member facies are as follows: facies 1: silty mudstone, optimal source, and optimal to fair reservoir; facies 2: muddy siltstone (optimal source and optimal reservoir); facies 3: silty calcareous mudstone (good source and good reservoir); facies 4: bioclastic wackestone–floatstone (fair source and fair reservoir); and facies 5: packstone–grainstone (poor source and poor to excellent reservoir). The proposed facies scheme aims to provide a more comprehensive approach to capture the high vertical and lateral variability in this mixed carbonate and fine-grained clastic succession. Through this detailed textural, compositional, sedimentologic, and diagenetic approach, this facies model can be used to better understand reservoir quality and distribution throughout the Midland Basin.

Wohl, C., Brown, I., Kitidis, V., Jones, A.E., Sturges, W.T., Nightingale, P.D., Yang, M., 2020. Underway seawater and atmospheric measurements of volatile organic compounds in the Southern Ocean. Biogeosciences 17, 2593-2619.


Dimethyl sulfide and volatile organic compounds (VOCs) are important for atmospheric chemistry. The emissions of biogenically derived organic gases, including dimethyl sulfide and especially isoprene, are not well constrained in the Southern Ocean. Due to a paucity of measurements, the role of the ocean in the atmospheric budgets of atmospheric methanol, acetone, and acetaldehyde is even more poorly known. In order to quantify the air–sea fluxes of these gases, we measured their seawater concentrations and air mixing ratios in the Atlantic sector of the Southern Ocean, along a ∼ 11 000 km long transect at approximately 60∘ S in February–April 2019. Concentrations, oceanic saturations, and estimated fluxes of five simultaneously sampled gases (dimethyl sulfide, isoprene, methanol, acetone, and acetaldehyde) are presented here. Campaign mean (±1σ) surface water concentrations of dimethyl sulfide, isoprene, methanol, acetone, and acetaldehyde were 2.60 (±3.94), 0.0133 (±0.0063), 67 (±35), 5.5 (±2.5), and 2.6 (±2.7) nmol dm−3 respectively. In this dataset, seawater isoprene and methanol concentrations correlated positively. Furthermore, seawater acetone, methanol, and isoprene concentrations were found to correlate negatively with the fugacity of carbon dioxide, possibly due to a common biological origin. Campaign mean (±1σ) air mixing ratios of dimethyl sulfide, isoprene, methanol, acetone, and acetaldehyde were 0.17 (±0.09), 0.053 (±0.034), 0.17 (±0.08), 0.081 (±0.031), and 0.049 (±0.040) ppbv. We observed diel changes in averaged acetaldehyde concentrations in seawater and ambient air (and to a lesser degree also for acetone and isoprene), which suggest light-driven production. Campaign mean (±1σ) fluxes of 4.3 (±7.4) µmol m−2 d−1 DMS and 0.028 (±0.021) µmol m−2 d−1 isoprene are determined where a positive flux indicates from the ocean to the atmosphere. Methanol was largely undersaturated in the surface ocean with a mean (±1σ) net flux of −2.4 (±4.7) µmol m−2 d−1, but it also had a few occasional episodes of outgassing. This section of the Southern Ocean was found to be a source and a sink for acetone and acetaldehyde this time of the year, depending on location, resulting in a mean net flux

of −0.55 (±1.14) µmol m−2 d−1 for acetone and −0.28 (±1.22) µmol m−2 d−1 for acetaldehyde. The data collected here will be important for constraining the air–sea exchange, cycling, and atmospheric impact of these gases, especially over the Southern Ocean.

Woods, P., 2020. The discovery of cosmic fullerenes. Nature Astronomy 4, 299-305.

https://doi.org/10.1038/s41550-020-1076-5

In 2010, the Spitzer Space Telescope detected evidence of a complex form of carbon that had never been seen in extraterrestrial environments. Jan Cami recounts the discovery of buckminsterfullerene in space.


https://doi.org/10.1029/2019JB019103

In this study, a microfocus X ray computed tomography based triaxial testing apparatus was used to‐ ‐ observe and quantify the microstructure evolution of hydrate bearing sands during thermal ‐dissociation of hydrate. Three triaxial shear tests with X ray computed tomography were conducted ‐to study the influence of hydrate dissociation on the mechanical behavior of hydrate bearing sands. ‐The results show that hydrate covering the sand particle surface dissociates first and then at the menisci between sand particles. The secondary hydrate formation mainly occurs on the menisci between sand particles and the surfaces of the hydrate shells where hydrates already exist. Hydrate dissociation could cause fabric changes in hydrate bearing sands, resulting in a more isotropic ‐orientation distribution of sand particles. The failure behavior of the hydrate free sand specimen is ‐similar to that of the specimen after hydrate dissociation, which shows an obvious drum shaped ‐failure pattern with X shaped shear bands. However, the hydrate bearing sand specimen exhibits a ‐ ‐shear band with a determined thickness and inclination angle. Hydrate dissociation could cause a significant loss of supporting cementation, resulting in a decline in the stiffness and failure strength. The failure strength of hydrate free sand specimen is slightly higher than that of the specimen after ‐hydrate dissociation; this may due to that the homogeneous orientation frequency distribution can enhance the stability of the force chain between sand particles. The secondary hydrate formation causes sediment deformation resulting in a decrease in absolute permeability due to pore blockage.

Wu, R., Liu, J., Calner, M., Gong, F., Lehnert, O., Luan, X., Li, L., Zhan, R., 2020. High-resolution carbon isotope stratigraphy of the Lower and Middle Ordovician succession of the Yangtze Platform, China: implications for global correlation. Journal of the Geological Society 177, 537.

http://jgs.lyellcollection.org/content/177/3/537.abstract

The Lower and Middle Ordovician of the Yangtze Platform, China, is characterized by a sedimentary succession dominated by carbonate rocks. Three sections spanning the Nantsinkuan/Lunshan, Fenhsiang, Hunghuayuan, and Dawan/Zitai formations, corresponding to the Tremadocian–Dapingian in age, have been sampled for high-resolution δ13C chemostratigraphy (542 samples in total). Our new δ13C data reveal five tie-points with the potential for global correlation: (1) a positive

δ13C excursion in the lower Nantsinkuan Formation within the Tremadocian Rossodus manitouensis Zone; (2) an excursion with two peaks roughly within the late Tremadocian Paltodus ‘deltifer’ Zone; (3) a positive δ13C shift in the lower Hunghuayuan Formation, within the early Floian Serratognathus diversus Zone; (4) a gradual positive δ13C shift in the late Floian, ranging from the uppermost S. diversus Zone to the basal Oepikodus evae Zone; (5) a minor negative shift in the lower Dawan/Zitai Formation, within the early Dapingian Baltoniodus triangularis Zone. These excursions are herein used for correlation of the Yangtze Platform strata with successions from South China, North China, the Argentine Precordillera, North America and Baltica. From a palaeogeographical perspective the Gudongkou, Xiangshuidong and Daling sections represent depositional environments along an inner to outer ramp profile. δ13C data from these sections show successively heavier (higher) δ13C values with increasing depositional depth. This is interpreted as due to remineralization of organic carbon within the carbonate rocks.

Supplementary material: Carbon and oxygen isotope data are available at: https://doi.org/10.6084/m9.figshare.c.4767080



The special intrinsic characteristics of shale formations, such as multiscale pore systems and complex mineral components, make the simulation of shale properties more difficult than that of sandstone properties. As such, one prerequisite of numerically predicting the physical properties of shale samples is to construct accurate shale models that include those special features. To this end, the study presents a novel hybrid stochastic modeling algorithm, called DEM-QSGSA, which integrates the discrete element method (DEM) and the quartet structure generation set algorithm (QSGSA), to build the necessary multicomponent and multiscale shale models. To investigate the effects of the components on the shale properties, the DEM-QSGSA was used to generate a dozen digital shale models with different mineral components containing quartz, feldspar, calcite, clay minerals, pyrite, and organic matter. The accuracy of the models was verified by comparing the characteristics of pore systems and the percentages of mineral components of the generated models with the ones of the SEM images of real shale samples. The electrical resistivity, bulk modulus, and shear modulus of these shale models were obtained using FEM. The results of electrical and elastic properties of these digital rocks indicate that the increase in abundance of the organic matter (OM) pores, intraparticle (intraP) pores, clay minerals, or OM results in a decrease in the electrical resistivity and elastic moduli when the pore systems of shale models are saturated with water. However, when the volume fraction of pyrite becomes larger, the elastic moduli increases and electrical resistivity decreases. Moreover, comparison of the sensitivity indices of the variables shows that pyrite has the largest effect on the electrical and elastic properties of shale samples, whilst clay minerals exert a moderate impact on them.

Wu, Y., Tong, J., Algeo, T.J., Chu, D., Cui, Y., Song, H., Shu, W., Du, Y., 2020. Organic carbon isotopes in terrestrial Permian-Triassic boundary sections of North China: Implications for global carbon cycle perturbations. GSA Bulletin 132, 1106-1118.

https://doi.org/10.1130/B35228.1

The end-Permian mass extinction (ca. 252 Ma) represents the most severe biotic crisis of the Phanerozoic, and it was accompanied by profound environmental perturbations, especially to the global carbon cycle, as indicated by sharp negative carbon isotope excursions (CIE) in both carbonates (δ13Ccarb) and organic matter (δ13Corg). To date, carbon isotope records are mostly from marine Permian-Triassic transitional sequences with relatively few high-resolution carbon isotope profiles having been generated for terrestrial facies. Terrestrial Permian-Triassic sequences suitable for high-resolution carbon isotope study are rare globally and are difficult to correlate with better-studied marine sequences. However, carbon isotope records from continental facies are essential to a full understanding of global carbon cycle changes during the Permian-Triassic transition. Here, we present bulk δ13Corg profiles for three terrestrial sections in North China representing Permian-Triassic transitional beds. These profiles exhibit similar patterns of secular variation defining three stages: (1) a pre-CIE interval, (2) a CIE interval, characterized by a rapid negative shift of 1.7‰–2.2‰ within the middle part of the Sunjiagou Formation, and (3) a post-CIE interval. The similarity of the CIE in all three study sections facilitates correlations among them, and its presence in the Permian-Triassic transitional beds suggests that it is equivalent to the negative CIE at the Permian-Triassic boundary in the Meishan global stratotype section and point (GSSP) and in coeval marine and terrestrial sections globally. The end-Permian CIE was probably triggered by a massive release of 13C-depleted carbon from volcanogenic sources leading to elevated atmospheric pCO2, although oceanic sources of CO2 cannot be ruled out at present.



Whether the emplacement of petroleum in sandstone reservoirs can preserve porosity during burial remains controversial. In the Kessog Field, UK Central North Sea, average porosities of the crestal sections of the fluvial-deltaic Pentland Formation reservoir can exceed 25% despite burial to 4 km or more. The predicted porosity for the reservoir at this depth is only around 14% based on regional data. Oil saturation data, thin-section point counts, grain-size and sorting measurements, reservoir pressure, and SEM images were combined to analyze the cause of the high reservoir porosity. Petroleum emplacement preventing cementation is the most likely mechanism for porosity preservation. Facies variation is not responsible, as the high-porosity sandstones from the crestal well are, in terms of average grain-size (fine-grained) and sorting coefficient (moderately well-sorted), nearly the same as the lower porosity sandstones from the flanks of the field (average porosity 13–15%). Other potential porosity-preservation mechanisms, such as overpressure, grain-coats and feldspar dissolution can be discounted. The sandstones with high oil saturations are characterized by: 1) most porosity being primary as opposed to secondary; 2) there being 2–5% less quartz cement than in the water-saturated sandstones; 3) there being 2–3% more K-feldspar and 2–6% less kaolin than the water-saturated counterparts. This study demonstrates that petroleum emplacement can effectively inhibit quartz cementation and K-feldspar transformation to kaolin in sandstone reservoirs.

Xia, J., Liu, H., Nie, Z., Fan, X., Zhang, D., Zheng, X., Liu, L., Pan, X., Zhou, Y., 2020. Taking insights into phenomics of microbe-mineral interaction in bioleaching and acid mine drainage: Concepts and methodology. Science of The Total Environment 729, 139005.


Phenomics is originally a biological concept. In the most recent years, the studies of plant and human phenomics have started, and show a strong momentum and trend of development. In this paper, based on the related research on bioleaching/acid mine drainage (AMD), we put forward the relevant concepts and methodology of phenomics of microbe-mineral interaction (MMI) in bioleaching/AMD environments. It refers to the systematic study on phenotypes of MMI on both levels of microbiome and mineralome under various environmental conditions, by which it gives the relationship between microbial/mineral genome and phenome of MMI responding to the varying environmental conditions. The pertinent methodology is of mainly (meta)-omics, synchrotron radiation-based techniques and supercomputing-based density function theory (DFT) calculation.



Ambient mass spectrometry imaging (AMSI) is a molecular imaging technique developed in recent years for in situ and real time visualization of the distribution of chemical compounds in biological tissues without the need of labeling or staining. With the development for more than one decade, AMSI becomes a powerful molecular imaging technique in variousfields such as forensics, metabolomics, cancer diagnosis, and drug monitoring. In this review, we describe the recent advances of AMSI for imaging biological tissues in details. Three types of AMSI techniques based on different ionization mechanisms and analytical strategies are summarized, i.e., direct desorption/ionization of analytes for AMSI, desorption and then ionization of analytes for AMSI, and extraction of analytes for AMSI, and the features of them are presented from the aspects of tissue origin, target image molecule, and spatial resolution among others. In addition, future development directions for AMSI are discussed.


https://doi.org/10.1029/2019JD032200

Organosulfates (OSs), a key component of secondary organic aerosols (SOA), account for up to one third of organic matter in the atmosphere. However, high molecular weight (HMW, 500?800 Da) OSs in ambient aerosols are poorly characterized at a molecular level, due to experimental difficulties. With Fourier transform-ion cyclotron resonance mass spectrometry (FT-ICRMS), we are able to identify more than 8,000 OSs in wintertime aerosols in Beijing. We found that both the number and signal magnitudes of HMW OSs with low H/C and O/C ratios and degrees of unsaturation were greatly enhanced during hazy days, indicating that most HMW OSs were freshly formed during stagnant air pollution episodes. They are most likely to be the oxidation products of semivolatility to

low-volatility precursors (e.g., polycyclic aromatic hydrocarbons and fatty acids) and have showed a strong influence of anthropogenic emissions. The molecular corridor analysis suggests that the high abundance of HMW aromatic-like and aliphatic OSs considerably decreases the volatility of organic aerosols in the urban atmosphere.

Xie, X., Li, M., Xu, J., Snowdon, L.R., Volkman, J.K., 2020. Geochemical characterization and artificial thermal maturation of kerogen density fractions from the Eocene Huadian oil shale, NE China. Organic Geochemistry 144, 103947.


Oil shales are an important alternative energy resource, through retorting, for the production of liquid hydrocarbons. A key factor in determining the value of an oil shale resource is its hydrocarbon generation potential; particularly its maceral distribution. To examine this, single maceral concentrates were obtained from a 1 kg Eocene Huadian oil shale sample using float-sink separation of chemically demineralized kerogen. Nine different density fractions were separated: the Botryococcus fraction occurred in the lightest (<1.06 g/mL) material, lamalginite in the 1.06–1.23 g/mL fraction, while detrovitrinite dominated in a higher density fraction (1.26–1.36 g/mL), which also contained some lamalginite.

Rock-Eval S2 and hydrogen index (HI) parameters, as well as the aliphatic compound peaks in Fourier transform infrared (FTIR) spectra, all decreased with increasing kerogen density, whereas the Rock-Eval oxygen index and the aromatic compound peaks in FTIR spectra, increased. The δ13C values showed slight variations within the different density fractions. The δ13C value of parent shale kerogen was very close to that of the density fraction dominated by lamalginite (−25.1‰), because the sample is dominated by lamalginite macerals (>70%). The Botryococcus sp. fraction is isotopically enriched because Botryococcus sp. is typically significantly enriched in 13C (δ13C = −24.6‰).

Artificial thermal maturation hydrocarbon generation results show that absolute hydrocarbon gas yields were similar among the different density fractions. The 1.06–1.12 g/mL fraction, dominated by lamalginite, generated nearly twice as much liquid hydrocarbons as the 1.26–1.30 g/mL fraction dominated by detrovitrinite. The maximum hydrocarbon yields corresponded well with the Rock-Eval HI values. Calculated by the relationships among HI, detrovitrinite and alginite compositions, the HI is 909 and 177 mg HC/g TOC for the purified alginite and detrovitrinite fractions, respectively. Kinetics analysis shows that Ea (activation energy) is higher for the low-density fraction (1.06–1.12 g/mL) than that for the heavy fraction (1.26–1.30 g/mL), indicating that lamalginite not only has a much better hydrocarbon generation potential, but also higher thermal stability. Therefore, this lamalginite-rich oil shale is well suited for exploitation by retorting, even though the retorting temperature would be higher than for detrovitrinite-rich fractions.

Xie, X., Snowdon, L.R., Volkman, J.K., Li, M., Xu, J., Qin, J., 2020. Inter-maceral effects on hydrocarbon generation as determined using artificial mixtures of purified macerals. Organic Geochemistry 144, 104036.


Different proportions of purified, low maturity maceral concentrates (∼0.4 %Ro) have been artificially mixed to evaluate changes in the hydrocarbon generation characteristics as a function of

maceral-maceral interactions. The purified maceral concentrates (lamalginite [L], detrovitrinite [D] and resinite [R]) were obtained from an Eocene lacustrine oil shale and an Eocene coal sample from NE China. Four artificial mixtures (L:D:R = 80:20:0 wt%, 50:50:0 wt%, 70:25:5 wt%, and 20:80:0 wt% were prepared for analysis. Comparison of the measured and calculated geochemical parameters of artificial mixtures shows that bulk characteristics such as Rock-Eval data, carbon isotope values, Fourier transform infrared (FTIR) parameters, the Py-GC gaseous hydrocarbon content and gas–oil ratios of the maceral mixtures are consistent with the calculated values. However, the Py-GC hydrocarbon distribution patterns of the liquid oil (C5-14) and C15+ fractions show deviations from the expected values. In particular, the Py-GC distribution pattern and n-alkene/n-alkane pattern of the mixtures are similar to that of the purified lamalginite maceral concentrate, even when the lamalginite content in the mixture is low (i.e. 20%). Py-GC of the mixtures with detrovitrinite yields much more of the C15+ fraction than calculated and the deviation is larger in mixtures with a smaller amount of detrovitrinite. It is apparent that the alginite maceral is the main source of hydrocarbons and will strongly influence the hydrocarbon distribution pattern, while the presence of vitrinite could lead to enhanced C15+ hydrocarbon amounts. These results suggest that geochemical properties and generated hydrocarbon amounts can be influenced by the interaction of different organic matter types. Further research is needed to determine the specific chemical/physical nature of these interactions.

Xiong, J., Yang, J., 2020. Examining the role of varying surface pressure in the climate of early Earth. Climate of the Past Discussions 2020, 1-20.


During the Archean Eon in 2.7 billion years ago, solar luminosity was about 75 % of the present-day level, but the surface temperature was suggested to similar to or even higher than modern. What mechanisms act to maintain the temperate climate of early Earth is not clearly known yet. Recent studies suggested that surface air pressure was different from the present level. How does varying surface air pressure influence the climate? Using an atmospheric general circulation model coupled to a slab ocean with specified oceanic heat transport, we show that decreasing (increasing) surface pressure acts to cool (warm) the surface mainly because the greenhouse effect of pressure broadening becomes weaker (stronger). The effect of halfing or doubling the surface pressure on the global-mean surface temperature is about 10 K or even larger when ice albedo feedback or water vapor feedback is strong. If the surface pressure was 0.5 bar, a combination of a CO2 partial pressure of about 0.04 bar and an oceanic heat transport of twice the present-day level or a combination of a CO2 partial pressure of about 0.10 bar and an oceanic heat transport of half the present-day level is required to maintain a climate similar to modern, under a given CH4 partial pressure of 1 mbar. Future work with fully coupled atmosphere-ocean models is required to explore the strength of oceanic heat transport and with cloud resolving models to examine the strength of cloud radiative effect under different surface air pressures.

Xu, H., Hou, D., Löhr, S.C., Liu, Q., George, S.C., 2020. Early diagenetic pyrite cementation influences molecular composition of sedimentary organic matter in the Dongying Depression, China. Organic Geochemistry 144, 104019.


Micro-variations of lipid hydrocarbons and biomarkers in well-laminated shales have not been extensively documented, especially within different rock textures, fabrics and mineralogies. Comparison of a pyrite cemented zone and its surrounding sediment may offer a new perspective on mineral control on preservation of hydrocarbons and organic carbon. A black well-laminated shale comprising two adjacent and contrasting calcareous (light) and pyrite (dark) laminae at the millimetre scale was selected from the Eocene Shahejie Formation, Dongying Depression, Bohai Bay Basin. It was horizontally sliced to separate a pyrite cemented concretion from the unaltered laminated shale, and investigated using geochemical techniques to assess the heterogeneity of elements, minerals, microfossils and hydrocarbons within the two slices. Micro-scale changes in source inputs were noted. For instance, the 4α-methylsteranes, dinosteranes and the triaromatic dinosteranes show varying distributions between the two slices, attributed to slight differences in dinoflagellate contributions. Similarly, variation in the amount of bacterial sulfate reduction is indicated by variations in the aryl isoprenoid ratio, relative amount of isorenieratane, long-chain n-alkane carbon isotopic composition and other molecular indicators including the relative amounts of dibenzothiophene, dibenzofuran, methyldibenzothiophene and methyltrimethyltridecylchromans. The primary control on these variations appears to be different euxinic water conditions, but diagenesis has also influenced the distributions. Differential anaerobic bacterial reworking of organic matter and pyrite concretion protection are responsible for organic geochemical variations on a millimetre-scale in the shale. The pyrite concretion has an altered record of its thermal history, but has a more accurate record of the organic geochemistry of microfossils and water column conditions. This study shows the potential for future investigations of closely-spaced vertical variation in organic geochemical parameters that may shed light on rapid temporal variation in organic matter input and depositional environment.

Xu, J., Huang, Q., 2020. Geological characteristics of shale in the Silurian (Sichuan) basin and chemical reaction of its reservoir under the action of fracturing fluid. Journal of Petroleum Exploration and Production Technology 10, 1775-1782.

https://doi.org/10.1007/s13202-020-00875-8

The exploitation and exploration of shale gas is of great values to solve the energy problem. Taking the shale from Silurian Longmaxi formation in Sichuan Basin as an example, its geological characteristics and reservoir chemical reaction under the action of fracturing fluid were analyzed, and moreover, a series of data determination and fracturing fluid chemical reaction experiments were carried out. The results showed that the average total organic carbon value of shale in the study area was 4.79%, the kerogen type was type I, the ratio of aliphatic structure to aromatic structure was smaller than 1, the average RO value was 2.15%, the content of clay mineral in the mineral composition was high, the average porosity was 3.16%, and the average permeability was 0.036 × 103 μm2, which was conducive to shale gas generation; under the action of fracturing fluid, the sulfate mineral in the shale dissolved, clay mineral expanded, and the pore volume and specific surface area reduced. The results verify that the research area has shale gas mining value, and this study makes some contributions to further study the optimization of fracturing fluid and improve exploitation technology.

Xu, R., Alam, M.S., Stark, C., Harrison, R.M., 2020. Composition and emission factors of traffic- emitted intermediate volatility and semi-volatile hydrocarbons (C10–C36) at a street canyon and urban background sites in central London, UK. Atmospheric Environment 231, 117448.


Hydrocarbons in both gas and particle phases from C10 to C36 (I/SVOCs) were analysed at sites in central London. Samples were collected from a street canyon, Marylebone Road (MR), a rooftop site (WM) above MR, and a site in the adjacent Regent's Park (RU), north of MR to evaluate the change in composition of I/SVOCs during advection from the traffic to the cleaner atmosphere of the urban background. Groups of compounds identified and quantified in gas and particle phases include C13–C36 n-alkanes and branched alkanes, C12–C25 monocyclic alkanes, C13–C27 bicyclic alkanes and C10–C24 monocyclic aromatics. The similarities found in the aliphatic and aromatic region above C12 in urban air and diesel exhaust demonstrate the impact of diesel-powered vehicles on urban air quality. Diesel exhaust is suggested to be the dominant emission source, while small differences between sites indicate the possibility of other sources which are also discussed. The ambient concentrations of I/SVOCs in the street canyon at MR were highest when the southerly winds brought the traffic emitted pollutants to the sampler. Emission factors (EFs) for all compound groups were estimated from the concentrations at the MR site. Particle-phase n-alkane EFs are broadly similar to those measured elsewhere in the world, despite differences in traffic fleet composition. A comparison between n-alkane EFs estimated from field measurements and those measured from diesel engines in the laboratory suggests a large contribution from vehicles with higher emissions than recent passenger cars to London air.

Xu, S.-l., Wu, B.-f., Orešič, M., Xie, Y., Yao, P., Wu, Z.-y., Lv, X., Chen, H., Wei, F., 2020. Double derivatization strategy for high-sensitivity and high-coverage localization of double bonds in free fatty acids by mass spectrometry. Analytical Chemistry 92, 6446-6455.


Free fatty acids (FFAs) are key intermediates of lipid metabolism that have a crucial role in many critical biological processes. The specific locations of carbon–carbon double bonds (C═C) in FFAs are often associated with distinct biological functions. Despite the rapid development of analytical techniques, identification of C═C locations in FFAs with more than three C═C bonds in complex biological matrices remains a challenge. Herein, we describe a double derivatization strategy, coupled with shotgun-mass spectrometry (MS), for unambiguous and sensitive determination of a high-coverage C═C bond (from 1 to 6) locations of FFAs. Our approach is based on combination of acetone labeling of C═C bonds and N,N-diethyl-1,2-ethanediamine (DEEA) labeling of carboxyl groups within FFAs. Acetone labeling of C═C bonds via photochemical reaction provides diagnostic ions, specific to C═C locations, and DEEA labeling of carboxyl groups significantly enhances MS response of diagnostic ions, by invoking a readily protonated tertiary amine group on FFA analytes. By exploiting this double derivatization strategy, the assignment of C═C locations of FFAs with more than three C═C bonds was achieved with high sensitivity (limit of quantitation (LOQ) 0.1–1.5 nmol/L). In contrast, such assignments were not possible by acetone labeling alone, because of the low sensitivity of diagnostic ions in negative ionization mode of MS. The applicability of our method was demonstrated by profiling of FFAs, including unsaturated FFA C═C positional isomers, in liver samples from mice with nonalcoholic fatty liver disease (NAFLD) and their lean controls. The study showed that the high-specificity and high-sensitivity method developed here is promising for accurate identification and quantitation of a wide array of FFAs in biological samples.

Xu, X., Lu, X., Li, X., Liu, Y., Wang, X., Chen, H., Chen, J., Yang, X., Fu, T.-M., Zhao, Q., Fu, Q., 2020. ROS-generation potential of humic-like substances (HULIS) in ambient PM2.5 in urban Shanghai: Association with HULIS concentration and light absorbance. Chemosphere 256, 127050.


Ambient fine particulate matter (PM2.5) can cause adverse health effects through the generation of reactive oxygen species (ROS) after inhalation. Humic-like substances (HULIS) are major constituents contributing to the ROS-generation potential in organic aerosols. In this study, PM2.5 samples in urban Shanghai during autumn and winter (2018–2019) were collected. Mass-normalized ·OH generation rate in surrogate lung fluid (SLF) was used to denote the intrinsic ROS-generation potential of PM2.5 or of the HULIS isolated from PM2.5. In this study, ROS-generation potential of PM2.5 decreased with increasing ambient PM2.5 concentration due to higher percentage of inorganic components in high PM2.5 event. Same trend was observed for the ROS-generation potential of unit mass of HULIS, which was higher when HULIS and PM2.5 concentrations were both relatively lower. The HULIS with high ROS-generation potential but low concentration (High-ROS/Low-Conc HULIS) were likely produced by the atmospheric aqueous-phase reactions during nighttime or under high relative humidity conditions, not from biomass burning emissions or the photochemical pollution products. The association between ROS-generation potential and light absorption properties of HULIS was studied as well. The High-ROS/Low-Conc HULIS also showed stronger light absorbance than the other HULIS. Our results implied the potentially important roles that HULIS species might play in atmospheric environment and human health even when the PM2.5 pollution is low.

Xue, Y., Jonassen, I., Øvreås, L., Taş, N., 2020. Metagenome-assembled genome distribution and key functionality highlight importance of aerobic metabolism in Svalbard permafrost. FEMS Microbiology Ecology 96, fiaa057.


Permafrost underlies a large portion of the land in the Northern Hemisphere. It is proposed to be an extreme habitat and home for cold-adaptive microbial communities. Upon thaw permafrost is predicted to exacerbate increasing global temperature trend, where awakening microbes decompose millennia old carbon stocks. Yet our knowledge on composition, functional potential and variance of permafrost microbiome remains limited. In this study, we conducted a deep comparative metagenomic analysis through a 2 m permafrost core from Svalbard, Norway to determine key permafrost microbiome in this climate sensitive island ecosystem. To do so, we developed comparative metagenomics methods on metagenomic-assembled genomes (MAG). We found that community composition in Svalbard soil horizons shifted markedly with depth: the dominant phylum switched from Acidobacteria and Proteobacteria in top soils (active layer) to Actinobacteria, Bacteroidetes, Chloroflexi and Proteobacteria in permafrost layers. Key metabolic potential propagated through permafrost depths revealed aerobic respiration and soil organic matter decomposition as key metabolic traits. We also found that Svalbard MAGs were enriched in genes involved in regulation of ammonium, sulfur and phosphate. Here, we provide a new perspective on how permafrost microbiome is shaped to acquire resources in competitive and limited resource conditions of deep Svalbard soils.


http://www.cjxb.ac.cn/EN/abstract/abstract4099.shtml

The conglomerate reservoirs discovered recently in the Mahu Depression, Junggar Basin have been characterized as near-source,coarse-grained,deep-buried,and low-permeability. The conglomerate reservoir quality of the Lower Urhe Formation is closely related to the authigenic chlorite and its associated diagenesis. Petrology and mineralogy were studied for the Permian Lower Urhe Formation in the northern Mahu Depression using thin section observation,scanning electron microscopy,electron probe,and X-ray fluorescence(XRF)spectrum to clarify the content, distribution,and genesis of authigenic chlorite and its impact on reservoir quality and to explore the reservoir difference mechanism of diagenesis. The research shows that:1)The authigenic chlorites in the northern Mahu Depression belong to iron-magnesium transitional iron-rich chlorites,produced by grain-coating,pore lining,and pore filling and controlled by iron-magnesium-rich volcanic material;2)Four conglomerate fans were developed in the northern Mahu Depression,and the provenance properties of the source rock are obvious. The Xiayan and Madong fans along the slope of eastern Mahu Depression are characterized by the development of a combination of authigenic chlorites and laumontites,while both the Xiazijie and Huangyangquan fans along the slope of the western Mahu Depression are characterized only by laumontite cementation. Different conglomerate reservoirs from various source rocks are characterized by obvious differences within their diagenetic sequence;3)The conglomerate reservoir quality is closely related to the properties of their source rock. The precipitation of authigenic chlorites and laumontites along the slope of the eastern Mahu Depression leads to high cementation and tightness overall. The good reservoir depends on later fracturing. Due to the lack of authigenic chlorites along the slope of the western Mahu Depression, the development of laumontite resists normal compaction and retains some of the primary pores,providing possible migration channels for the injection of later acidic fluids and laumontite dissolution. The conglomerate reservoirs located in the high part of the topography are possibly good quality due to a high degree of laumontite dissolution.

Yan, Y., de Klerk, A., Prado, G.H.C., 2020. Visbreaking of vacuum residue deasphalted oil: New asphaltenes formation. Energy & Fuels 34, 5135-5147.


The formation of new heavier material during thermal processing has long been known, and under typical visbreaking conditions, vacuum conversion of deasphalted oil is described using a first-order kinetic reaction. Using the equivalent residence time (ERT) assumption, the residence time and reaction temperature are interchangeable variables to achieve the same conversion, where conversion is defined as the decrease of the vacuum residue through its conversion to lighter boiling fractions. With the combination of these observations about the visbreaking process, the following research question was raised: would process conditions that, in principle, lead to the same conversion also lead to the same asphaltenes content in the final product? The answer to this question was evaluated in this work, where vacuum residue deasphalted oil was submitted to visbreaking. Isoconversion conditions were obtained by the ERT concept. As expected, an increase in n-pentane-insoluble material was obtained at all process conditions studied. The kinetics of

asphaltenes formation was different to the kinetics of vacuum residue conversion because the amount of asphaltenes formed were different at the same conversion and vice versa. Subsequent analysis of the new n-pentane-insoluble material revealed that asphaltenes were participating in hydrogen transfer reactions. The amount of hydrogen transferred during conversion at 438 °C were around 20 mg of H/g of asphaltenes in the product. Free radicals were formed as a consequence of hydrogen transfer reactions, and their recombination resulted in the formation of heavier material, which was reflected in an increase in n-pentane-insoluble material during visbreaking. Further investigation revealed that the free radicals remained reactive upon storage, which resulted in a 9 wt % increase in asphaltenes after 210 days of storage under nitrogen. Results also showed that isoconversion was not achieved as predicted by the ERT definition and the differences between predicted and experimental values are discussed on the basis of the assumptions to calculate ERT.


https://doi.org/10.1111/1755-6724.14301

In this study, the types of micropores in a reservoir are analyzed using casting thin section (CTS) observation and scanning electron microscopy (SEM) experiments. The high pressure mercury ‐injection (HPMI) and constant rate mercury injection (CRMI) experiments are performed to study ‐the micropore structure of the reservoir. Nuclear magnetic resonance (NMR), gas water relative ‐seepage, and gas water two phase displacement studies are performed to examine the seepage ‐ ‐ability and parameters of the reservoir, and further analyses are done to confirm the controlling effects of reservoir micropore structures on seepage ability. The experimental results show that Benxi, Taiyuan, Shanxi, and Shihezi formations in the study area are typical ultra low porosity and ‐ultra low permeability reservoirs. Owing to compaction and later diagenetic transformation, they ‐contain few primary pores. Secondary pores are the main pore types of reservoirs in the study area. Six main types of secondary pores are: intergranular dissolved pores, intragranular dissolved pores, lithic dissolved pores, intercrystalline dissolved pores, micropores, and microfracture. The results show that reservoirs with small pore throat radius, medium displacement pressure, and large ‐differences in pore throat structures are present in the study area. The four types of micropore ‐structures observed are: lower displacement pressure and fine pores with medium fine throats, low ‐displacement pressure and fine micropores with fine throats, medium displacement pressure and micropores with micro fine throats, and high displacement pressure and micropores with micro ‐throats. The micropore structure is complex, and the reservoir seepage ability is poor in the study areas. The movable fluid saturation, range of the gas water two phase seepage zone, and ‐ ‐displacement types are the three parameters that well represent the reservoir seepage ability. According to the characteristic parameters of microscopic pore structure and seepage characteristics, the reservoirs in the study area are classified into four types (I–IV), and types I, II, and III are the main types observed. From type I to type IV, the displacement pressure increases, and the movable fluid saturation and gas water two phase seepage zone decrease, and the ‐ ‐displacement type changes from the reticulation uniform displacement to dendritic and snake like.‐

Yang, C., Sun, J., Yang, Y., Yang, C., Wang, J., Xiao, G., Wang, J., 2020. Key factors controlling Mesozoic hydrocarbon accumulation in the Southern East China Sea Basin. Marine and Petroleum Geology 118, 104436.


The East China Sea Basin is located on the southeastern edge of the Eurasian Plate. Since the Mesozoic era, the basin formation and evolution processes have been superimposed with the multi-period oceanic subduction of the paleo-Pacific Plate and multi-structural systems interacting with the Indo–Australian Plate, Pacific Plate, and Eurasian Plate. As previous studies have mainly focused on the Cenozoic era, the basin prototype, tectono-sedimentary characteristics, and key factors controlling hydrocarbon accumulation during the Mesozoic era have always been hotspots for research and scientific questions as part of a “New horizon” for oil and gas exploration in the East China Sea Basin. Based on the latest data from seismic, drilling, and onshore-offshore comparison studies in the Southern East China Sea Basin (SECSB), this study explored the key factors controlling the oil and gas generation, migration and accumulation, and exploration direction of the Mesozoic hydrocarbon accumulation by employing onshore-offshore comparisons, seismic stratigraphy, and structural-sedimentary evolutionary reconstruction. The results showed that three regional unconformities and seven seismic sequences formed during the Mesozoic period in the SECSB. The evolution since the Mesozoic era included the formations of a basement by the passive continental margin before the Late Triassic, the Late Triassic–Middle Jurassic depression of the active continental margin, and the Cretaceous faulted basins at continental margins. It is proposed that 1) the early basal NE-trending structural framework controlled the structural pattern of the Mesozoic basin and the macro-hydrocarbon properties, according to which the Cretaceous should be dominated by oil, and the Upper Triassic-Middle Jurassic should be dominated by gas; 2) two sets of source rocks (i.e., Upper Triassic-Lower Jurassic mud shale and Lower Cretaceous mudstone source rocks) were deposited, which formed the material basis for hydrocarbon accumulation and the source-reservoir-seal combinations during two stages of basin evolution in the Mesozoic era; 3) the East China Sea Basin has experienced at least seven tectonic movements since the Mesozoic period, including the Keelung, Yushan, Yandang, Oujiang, Yuquan, Longjing, and Okinawa Trough movements, among which the Keelung, Yushan, and Yandang movements dominated the formation and accumulation of early oil and gas, and the adjustment, transformation, and re-establishment of early reservoirs was accomplished by the Longjing Movement; and 4) the Minjiang Slope and the Taipei Turning Belt are the main petroleum exploration areas in the Mesozoic basin, in which the Cretaceous should be the main target layer in the east of the basin, and the Upper Triassic–Middle Jurassic in the west.

Yang, R., Jia, A., He, S., Hu, Q., Dong, T., Hou, Y., Yan, J., 2020. Water adsorption characteristics of organic-rich Wufeng and Longmaxi Shales, Sichuan Basin (China). Journal of Petroleum Science and Engineering 193, 107387.


Water is ubiquitously present within organic-rich shale and can exert an important effect on the gas-in-place and gas adsorption capacity of shale reservoirs. Thus, understanding the water adsorption characteristics of gas shale reservoir is critical for optimizing shale-gas productivity. In this work, the water vapor adsorption characteristics of organic-rich Wufeng and Longmaxi Shales in the Sichuan Basin were studied over a wide range of relative humidities (RHs, 5–95%) utilizing a gravimetric method. All the water vapor adsorption isotherms are categorized as type II, suggesting similar water adsorption behaviors between samples. Being pronounced at approximately 70–80% RH, hysteresis loops from water adsorption curves are characterized by calculating areal hysteresis index (AHI) values. The Wufeng Shales have higher AHI values than those of Longmaxi Shales, which are

mainly related to the variation of TOC content and pore structure characteristics. Pore size distribution obtained from water vapor adsorption show unimodal distribution of pore sizes, which are generally comparable to that derived from nitrogen physisorption. The mineral content (e.g., quartz and clay contents) and pore structure characteristics (e.g., pore type, porosity and surface area) have great effects on the water vapor uptake in the Wufeng and Longmaxi Shales. Compared to the shales with low surface area and porosity, Wufeng and Longmaxi Shale samples with higher surface area and porosity exhibit much higher water vapor uptake, suggesting that moisture sorption is mainly controlled by the amount of adsorption sites and volumes. When RH increases from low to high values, methane capacity of partially moisture-equilibrated shale could have experienced rapid decline, moderate decrease and slow decrease stages, finally reaching the minimum adsorption capacity for full moisture-equilibrated shale.

Yang, R., Zhang, B., Wang, J., Tai, X., Sun, H., Zhang, G., Zhang, W., Chen, T., Liu, G., 2020. Planococcus lenghuensis sp. nov., an oil-degrading bacterium isolated from petroleum-contaminated soil. Antonie van Leeuwenhoek 113, 839-850.

https://doi.org/10.1007/s10482-020-01394-6

A Gram-staining-positive and aerobic coccus with the ability to degrade petroleum bacterium, designated Y42T, was isolated from the Lenghu oil field located in the northern margin of the Qaidam Basin. Phylogenetic and signature nucleotides analyses revealed that strain Y42T belongs to the genus Planococcus. The multiple sequence alignments of 16S rRNA and housekeeping genes showed that strain Y42T formed a distinct lineage with the other Planococcus clade. The average nucleotide identity (ANI) and DNA–DNA hybridization values (DDH) between strain Y42T and the reference strains were 69.5–70.1 and 19.4–21.7%, respectively, which values were below the threshold for species delineation. The major fatty acids of strain Y42T were anteiso-C15:0. The respiratory quinone was MK-7 (71.8%) as the predominant menaquinone followed the MK-6 (28.2%) and the cell-wall hydrolysates contained LL-diaminopimelic acid. The polar lipid was composed of diphosphatidyl glycerol, phosphatidyl glycerol, phosphoglycolipid, aminophospholipid and four unidentified lipids. The peptidoglycan type was A4α (l-Lys–d-Glu). The strain Y42T possessed larger genome (approximately 4 MB) and revealed obvious differences for the abundance of the COG categories compared with the other Planococcus bacteria. Also, the strain Y42T also possessed more unique orthologous proteins. The structural characteristics of the strain Y42T genome provided a competitive advantage for better survival in petroleum-polluted environments. Combined with the 16S rRNA gene and genome sequence, phenotypic as well as chemotaxonomic characterisations, strain Y42T is considered to represent a novel species of the genus Planococcus, for which the name Planococcus lenghuensis sp. nov. be proposed. The type strain is Y42T (= CGMCC 1.15921T = JCM 32719T).

Yang, S., Horsfield, B., 2020. Critical review of the uncertainty of Tmax in revealing the thermal maturity of organic matter in sedimentary rocks. International Journal of Coal Geology 225, 103500.


For more than forty years, the Rock-Eval pyrolysis technique has been widely used to rapidly assess the petroleum generating characteristics of organic matter in petroleum source rocks. Tmax, which is the temperature at which the rate of hydrocarbon generation is at its maximum during pyrolysis

(25 °C/min), is used mainly as a thermal maturity parameter. This paper presents a systematic review of the numerous other factors that control Tmax. Besides including the classical literature on this topic, the review discusses revelations from recent case studies with emphasis on new developments in unconventional hydrocarbon exploration and organic-inorganic interactions.

Experimental issues related to the model of Rock-Eval instrument, sample loading and the resolution and form of the pyrolysate (S2) peak(s), define the quality and reliability of Tmax data. Kerogen type sensu lato, controls the kinetics of bulk petroleum generation and thence Tmax. Thus, conversions between Tmax and the main maturity reference parameter, vitrinite reflectance, for marine (Type II) kerogen vary from shale to shale. Tmax anomalies induced by the mineral matrix effect, heavy bitumen carryover, weathering, and uranium irradiation are also discussed. On a practical note, checking the original pyrogram, comparing with adjacent samples with different organofacies, and cross-checking with other maturity proxies are helpful in identifying possible anomalies.

Yang, Y., Cheng, T., Wu, H., You, Z., Shang, D., Hou, J., 2020. Enhanced oil recovery using oleic acid-modified titania nanofluids: Underlying mechanisms and oil-displacement performance. Energy & Fuels 34, 5813-5822.


Oleic acid-modified titania (OA-TiO2) nanoparticles are synthesized for the application of enhanced oil recovery (EOR) in low-permeability reservoirs. The oleic acid is grafted onto the surface of titania by the esterification reaction under a specific condition. The well-dispersed OA-TiO2 is expected to exhibit an excellent interfacial activity and a strong wettability alteration capability, owing to its amphiphilic features. This work aims to explore the potential of employing OA-TiO2 in EOR and to unveil its mechanisms of displacing oil in porous media. The interfacial properties of OA-TiO2 are systematically investigated by determining its interfacial tension and contact angle. A microfluidic test on a 2.5-D microfluidic model and a series of core floods are carried out to study the oil-displacement efficiency of OA-TiO2 nanofluids. The experimental results demonstrate that oleic acid-modified titania nanoparticles show great potential in not only reducing the injection pressure but also enhancing hydrocarbon recovery in low-permeability reservoirs.

Yang, Y., Ruan, X., Gao, C., Lü, X., Yang, H., Li, X., Yao, Y., Pearson, A., Xie, S., 2020. Assessing the applicability of the long-chain diol (LDI) temperature proxy in the high-temperature South China Sea. Organic Geochemistry 144, 104017.


The Long-chain Diol Index (LDI) is a palaeotemperature proxy applied to marine sediments up to Miocene in age. Recent studies have revealed that the LDI-inferred temperature yields significant errors in waters >27 °C. This necessitates further assessment of the performance of the LDI proxy in high-temperature marine regimes. For this purpose, we collected 58 surface sediment samples from the tropical South China Sea (SCS), where annual sea surface temperature (SST) ranges from 24 °C to 29 °C. The original LDI calibration yields temperatures <27 °C for these samples, and the residual between the LDI-inferred temperature and the measured SST (ΔT) increases (to >4 °C) as SST increases. This ΔT, or mis-calibration, is significantly correlated with the measured SST as the temperature increases above 27 °C. This relationship also exists in sediment trap data. We therefore

re-calibrated the LDI-inferred temperature to generate a new relationship that can be applied to environments with SST >27 °C, which is beyond the range of the original LDI proxy. Both the recalibrated LDI and, for comparison, archaeal lipid temperature proxies were applied in the high-temperature SCS; the improved correlation shows the LDI recalibration could be applied to palaeo-records from tropical oceans.

Yao, L., Aretz, M., Chen, J., Qi, Y., 2020. Earliest Carboniferous stromatolites from the Qianheishan Formation, Dashuigou section, northwestern China: Implications for microbial proliferation after the end-Devonian mass extinction. Geological Journal 55, 3361-3376.


Earliest Carboniferous stromatolites were found in the Qianheishan (QHS) Formation in the Dashuigou section, Gansu Province, northwestern China. These stromatolites are exposed in a conglomerate-dominated succession of about 22.5 m in thickness, which can be traced laterally for more than 200 m in outcrop. They consist mainly of micrite, peloids, oncoids, silt-sized quartz grains, and sparry calcite with rare fine to coarse quartz grains and bioclasts. The occurrence of marine fossils (e.g., bryozoans) and fenestral structures in the stromatolites suggests that they developed in intertidal environments. Three types of stromatolite laminae were distinguished including micritic laminae, grain-dominated mixed laminae, and micrite-dominated mixed laminae. These laminae are separated by thin micritic crusts and form two lamination styles of repetitive lamination and alternating lamination. The development of grain-rich and micrite-rich laminae in the stromatolites implies that they were formed by the combination of microbial baffling, binding, and calcification. Facies analysis suggests that growth and demise of the stromatolites were controlled by relative sea-level changes. They grew during a continuous relative sea-level rise, indicated by variations in their thickness and morphology. Stromatolites change from thin-bedded laminar forms in the lower part of the studied interval to medium-bedded wavy-laminar forms and thick-bedded domal forms in the middle and upper parts, respectively. Their demise was triggered by dramatic relative sea-level fall, evidenced from the sandstone facies overlying the stromatolite interval. The occurrence of the QHS stromatolites provides an excellent example for microbial proliferation and profound changes in the marine biosphere after the end-Devonian Hangenberg extinction event.

Yasue, M., Masuda, Y., Liang, Y., 2020. Estimation of methane recovery efficiency from methane hydrate by the N2–CO2 gas mixture injection method. Energy & Fuels 34, 5236-5250.


Methane hydrate (MH) is the best-known unconventional energy resource and has begun to open its promising future, especially for Japan. In 2017, the second offshore gas hydrate field test was conducted in the Eastern Nankai Trough, Japan, where a depressurization technique was adopted for producing methane gas. Alongside the depressurization method, the replacement of CH4 from gas hydrates by a N2–CO2 gas mixture was suggested and adopted to increase performance for both methane gas recovery and carbon dioxide sequestration. The amount of abundant MHs is estimated to exist in the permafrost area; therefore, this method, which does not require any heat source, can be used as a standard method for recovering methane. In this study, experiments to continuously inject a N2–CO2 gas mixture (59 mol % CO2) into hydrate-bearing cores with different MH saturations were conducted. Simultaneously, the numerical simulation model was constructed, and to express

the gas exchange phenomenon of CH4–(N2 + CO2), the phase equilibrium analyses were used between the gas mixture and hydrates. Good agreements were obtained between experiments and simulations. At these experiments, the recovery factor of 40.8% and the exchange ratio of 8.22% were recorded as an example. The validation of the simulation with experimental results strongly supported our study to find the efficient injection gas composition for methane recovery. Case studies of the numerical simulation were conducted with various CO2 concentrations of injection gas in the range of 24–72 mol %. Simulation results showed that the highest recovery factor was obtained for the 30–40 mol % CO2 gas injection cases. The higher the N2 concentration of the gas mixture, the more CH4 molecules in the hydrate phase can be replaced. In the gas exchange process, the portion of N2 occupied in guest gas molecules of the hydrate became larger with increasing the N2 concentration of the gas mixture. From the discussion above, we concluded that the CO2 concentration of 30–40 mol % was the most effective for CH4 recovery by the N2–CO2 gas mixture injection method.



Black shale of the Cryogenian Nantuo Formation, Shennongjia area, South China contains spheroids which co-occur with fossils of macroalgae. These three-dimensional structures occur sparsely as isolated specimens or abundantly as clusters which show different types of boundaries between individuals. They are generally circular on bedding surfaces and elliptical on transecting sections, and range up to several millimeters in diameter. Both petrographic thin sections and scanning electron microscopy (SEM) reveal that these spheroids are mostly organic carbon in composition and exhibit sharp, well-rounded external margins composed of microcrystalline clay minerals. The carbonaceous nature of these spheroids and different elemental abundances between spheroids and matrix are also confirmed by Raman spectroscopy and energy dispersive X-ray spectroscopy (EDS). Organic carbon isotopic values of individual spheroids range from −28.55‰ to −28.83‰, with an average of −28.72‰, which show indistinguishable δ13Corg values with the surrounding sedimentary matrix but exhibit statistically significant difference to those of contemporaneous macroalgae. A range of physical origins for these spheroids—including concretions, fluid escape structures, raindrop impressions, or bubble impressions—are considered and cannot be entirely rejected. Alternatively, biogenic origin is also a possible interpretation from observations of their morphological, mineralogical, geochemical, and sedimentological characteristics. Although their nature remains unresolved, the documentation of these new carbonaceous spheroids from the Nantuo Formation of Shennongjia area adds to a growing list of fossil-like structure records in the Cryogenian Period.

Yin, Y., Mastalerz, M., Lennon, J.T., Drobniak, A., Schimmelmann, A., 2020. Characterization and microbial mitigation of fugitive methane emissions from oil and gas wells: Example from Indiana, USA. Applied Geochemistry 118, 104619.


AbstractHydrocarbon gas emissions from active, inactive, and improperly sealed or abandoned oil/gas wells significantly contribute to anthropogenically emitted greenhouse gases, predominantly

in the form of methane (CH4). We explored the extent of hydrocarbon gas emissions from 20 active, inactive, plugged and abandoned oil/gas wells in Indiana (USA), where it is estimated that there are more than 80,000 well sites throughout the state. After this initial survey, using a static flux tent, we quantified fugitive CH4 emissions from an active gas well to approximately 2 L h−1. To evaluate the potential for microbial mitigation of hydrocarbon emissions to the atmosphere, we conducted laboratory microcosm experiments to quantify the CH4 oxidizing potential of soils collected from sites with varying distances to the leaking gas well. Soils in close proximity to the well (0.5 m) efficiently consumed nearly all (97%) of the added CH4, while only 14% of added CH4 was consumed by soils that were more distant from the well (20 m). These results suggest that fugitive CH4 emissions enrich methanotrophic bacteria in soils immediately adjacent to the well. Consistent with this view, we found that prolonged exposure of soils to elevated concentrations of CH4 enhanced the methanotrophic activity. Together, these findings prompted us to design a “methanotrophic soil mound” to assess the feasibility of mitigating point sources of CH4 by harnessing the natural methanotrophic capacity of soil microbial communities. We found that a methanotrophic soil mound from a landfill could sustainably mitigate the CH4 emission from the artificial source, providing a promising low-cost solution to ameliorate fugitive CH4 emissions from abandoned oil and gas wells to the atmosphere. The effectiveness of microbe-based remediation is limited in cold climates and arid environments.

Yokota, S., Terada, K., Saito, Y., Kato, D., Asamura, K., Nishino, M.N., Shimizu, H., Takahashi, F., Shibuya, H., Matsushima, M., Tsunakawa, H., 2020. KAGUYA observation of global emissions of indigenous carbon ions from the Moon. Science Advances 6, eaba1050.


Carbon is a volatile element that has a considerable influence on the formation and evolution of planetary bodies, although it was previously believed to be depleted in the Moon. We present observations by the lunar orbiter KAGUYA of carbon ions emitted from the Moon. These emissions were distributed over almost the total lunar surface, but amounts were differed with respect to lunar geographical areas. The estimated emission fluxes to space were ~5.0 × 104 per square centimeter per second, which is greater than possible ongoing supplies from the solar wind and micrometeoroids. Our estimates demonstrate that indigenous carbon exists over the entire Moon, supporting the hypothesis of a carbon-containing Moon, where the carbon was embedded at its formation and/or was transported billions of years ago.

Yu, K., Ju, Y., Zhang, B., 2020. Modeling of tectono-thermal evolution of Permo-Carboniferous source rocks in the southern Qinshui Basin, China: Consequences for hydrocarbon generation. Journal of Petroleum Science and Engineering 193, 107343.


As a main coalbed methane-producing area in China, Qinshui Basin has undergone typical tectonic thermal evolution as a result of the destruction of the North China Craton since the Late Paleozoic. This work describes the construction of a comprehensive tectono-thermal model for the southern Qinshui Basin (SQB) with which to reveal the maturation and hydrocarbon generation of the coal-bearing source rocks. The organic geochemical results show that in the present day, the source rocks comprise Type III kerogen containing more than 2.0 wt % TOC and that the Ro ranges from 2.05% to

3.24%, suggesting appropriate thermal maturity and excellent gas generation potential. Modeling results indicate that from the Late Carboniferous to the Late Triassic, the coal-bearing strata entered the first rapid subsidence stage and reached a burial depth of about 5000 m in the Late Triassic, with a geothermal gradient of 42 °C/km and maximum temperature of 118 °C. Consequently, the maturity of source rocks increased to the first peak and entered the late oil stage. Due to the destruction of the North China Craton, lithospheric thinning, and associated magmatic activity during the Late Jurassic to Early Cretaceous, the study area experienced an abnormal thermal event, with an average geothermal gradient of 58 °C/km and a maximum heat flow of 124 mW/m2, and the source rocks reached the dry gas stage rapidly, so that secondary large-scale hydrocarbon generation occurred in the Early Cretaceous. Overall, the coal-bearing source rocks of the SQB underwent deep burial thermal metamorphism in the Late Triassic and intense magmatic thermal metamorphism in the Early Cretaceous, and the latter was completely controlled by magmatic events caused by the Craton destruction.

Yu, W., Algeo, T.J., Zhou, Q., Du, Y., Wang, P., 2020. Cryogenian cap carbonate models: a review and critical assessment. Palaeogeography, Palaeoclimatology, Palaeoecology 552, 109727.


The Cryogenian Period spans two major glaciations, the Sturtian Ice Age (~720–660 Ma) and the Marinoan Ice Age (~650–635 Ma), the termination of each of which was associated with a unique type of cap carbonate deposit. Cap carbonates are significant in providing a record of as-yet not fully understood ocean-chemical changes during the deglaciations following Snowball Earth events and in serving as readily recognizable event beds useful in global stratigraphic correlation of Neoproterozoic successions. Debate regarding the formation of cap carbonates has focused on three key issues: (1) alkalinity sources, (2) abiotic (chemical) versus biotic (microbial) precipitation, and (3) formation rates. Multiple hypotheses regarding cap carbonate formation have been advanced, including the weathering alkalinity model, the oceanic overturn model, the gas hydrate destabilization model, the plumeworld model, the starvation sediment model, the enhanced microbial activity model, and the calcareous loess model. We evaluated these models by considering their proposed solutions to the key issues above in the context of a global compilation of location, thickness, carbonate C-isotope, and paleomagnetic data for Cryogenian cap carbonates.

Cap carbonates were probably produced through a combination of chemical and microbial processes in a strongly stratified deglacial ocean with a low-salinity lid. Correlation of δ13Ccarb profiles shows that cap carbonate precipitation began synchronously but terminated diachronously at a global scale. Cap carbonates are markedly thicker in low-paleolatitude regions, suggesting greater alkalinity production and/or more rapid carbonate precipitation in those regions, which favors alkalinity production through continental weathering rather than through oceanic upwelling or methane oxidation. Calculation of alkalinity production rates based on a range of cap carbonate masses and formation intervals shows that minimum masses (~2.2 × 1021 g, i.e., comprising only known continental deposits) could have been produced through intense continental weathering at short timescales (103–104 yr), validating rapid deposition models. Longer timescales of cap carbonate formation (105–106 yr) are not precluded by these calculations but are hard to reconcile with physical evidence of rapid accumulation and near-complete lack of terrigenous clastic impurities. Alkalinity production rate calculations also show that maximum cap carbonate masses (to ~14.4 × 1021 g; i.e., assuming unproven deep-ocean cap carbonate deposits) are probably unrealistic,

requiring more alkalinity than could be generated even through a combination of mechanisms including continental weathering, deep-ocean microbial sulfate reduction, and methane release.

Yuan, Y., Shan, Y., Tang, Y., Cao, D., 2020. Coalbed methane enrichment regularity and major control factors in the Xishanyao Formation in the western part of the southern Junggar Basin. Acta Geologica Sinica - English Edition 94, 485-500.

https://doi.org/10.1111/1755-6724.14339

There are abundant coal and coalbed methane (CBM) resources in the Xishanyao Formation in the western region of the southern Junggar Basin, and the prospects for CBM exploration and development are promising. To promote the exploration and development of the CBM resources of the Xishanyao Formation in this area, we studied previous coalfield survey data and CBM geological exploration data. Then, we analyzed the relationships between the gas content and methane concentration vs. coal seam thickness, burial depth, coal reservoir physical characteristics, hydrogeological conditions, and roof and floor lithology. In addition, we briefly discuss the main factors influencing CBM accumulation. First, we found that the coal strata of the Xishanyao Formation in the study area are relatively simple in structure, and the coal seam has a large thickness and burial depth, as well as moderately good roof and floor conditions. The hydrogeological conditions and coal reservoir physical characteristics are also conducive to the enrichment and a high yield of CBM. We believe that the preservation of CBM resources in the study area is mainly controlled by the structure, burial depth, and hydrogeological conditions. Furthermore, on the basis of the above results, the coal seam of the Xishanyao Formation in the synclinal shaft and buried at depths of 700–1000 m should be the first considered for development.

Zakrzewski, A., Kosakowski, P., Waliczek, M., Kowalski, A., 2020. Polycyclic aromatic hydrocarbons in Middle Jurassic sediments of the Polish Basin provide evidence for high-temperature palaeo-wildfires. Organic Geochemistry 145, 104037.


The distributions and concentrations of polycyclic aromatic hydrocarbons (PAHs) and plant-derived aromatic biomarkers were analysed in Middle Jurassic strata from central Poland. These compounds were abundant in all samples indicating the occurrence of specific palaeoflora families and the intensity of palaeo-wildfires. Moreover, calculated fusinite reflectance values revealed that the temperature of Middle Jurassic wildfires may have exceeded 950 °C, consistent with high oxygen concentrations in the atmosphere during this period. The high content of charred organic matter has an influence on certain biomarker maturity indicators based on terrestrial organic matter such as C29 20S/(S + R). A new indicator was developed, benzo[ghi]perylene/(perylene + benzo[ghi]perylene), abbreviated as BgP/(Per + BgP, high values of which are characteristic of samples in which terrestrial organic matter is mostly charred. The use of this indicator is limited to immature organic matter, since perylene disappears when vitrinite reflectance is higher than 0.7 %Ro. Measurements of vitrinite reflectance indicated that Middle Jurassic organic matter with a reflectance value < 0.51 %Ro was immature or early-mature. Juxtaposition of the modified higher plant index (mHPI) calculated from mHPI = (retene + cadalene + ip-iHMN)/(retene + cadalene + ip-iHMN + 1,3,6,7-TeMN) and BgP/(Per + BgP) showed that samples from the central part of the Polish Basin contained more charred than unburnt terrestrial organic matter, as values of BgP/(Per + BgP) > 0.5 are

correlated with lower mHPI values. This is evidence for the transport of wildfire products by rivers, wind, and/or sea currents over large distances. Tracers for conifers, non-vascular plants, and fungi were identified.



Two basic homogeneous lithotypes, defined as elementary coal layers, within the seam of lignite can be distinguished: xylitic and detritic coal. As each of them exhibits various features, including structure, mechanical, technological properties, and chemical ash composition, the share of lithotypes within a lignite deposit provides important information regarding the applicability of this fuel. This study describes a unique three-dimensional reconstruction of a lignite microstructure using scanning electron microscopy (SEM) to acquire images of subsequent coal cross-sections which are exposed by focused ion beam (FIB) milling at cryogenic temperatures. Because of the organic origin and high moisture content, the fully hydrated lignite sample was frozen in nitrogen slush for the SEM observation in its frozen native state in order to avoid dehydration and other sample modifications. The acquired data cube contained distinguished petrographic phases, identified with coaly macerals of xylitic and detritic coal along with the fragment of the gelified leaf tissue, typical for ortho-lignite structure. The 3D reconstruction and phase segmentation process was performed using the Avizo software to constitute a cuboid model with an edge length of ca. 10 µm. Lignite exhibits low local uniformity, therefore to draw generally valid conclusions, a statistical relevant number of similar three dimensional reconstructions at representative locations for the different lithotypical and petrographic coal compositions within the analysed fragment would be demanded.

Zeng, Q., Chen, J., Zhan, C., Lin, Y., Chen, Z., 2020. Fully exploiting the power of 2D NMR J-resolved spectroscopy. Analytical Chemistry 92, 6893-6899.


Nuclear magnetic resonance (NMR) spectroscopy is a powerful analytical tool that enables one to study molecular properties and interactions. Homonuclear couplings provide valuable structural information but are often difficult to disentangle in crowded 1H NMR spectra where complex multiplets and signal overlap commonly exist. Multidimensional NMR experiments push the power of NMR to a new level by providing better signal dispersion. Among them, 2D J-resolved spectroscopy is widely used for multiplet analysis and the measurement of scalar coupling constants. Here, we present a new 2D J-resolved method, CASCADE, through which easier multiplet analysis and unambiguous measurement of specific coupling constants can be achieved at the same time, fully exploiting the power of 2D J-resolved spectroscopy. It is expected that this method may replace a conventional 2D J experiment in many cases, facilitating structural and configurational studies as well as chemical and biological analyses.

Zeng, T., Kim, K.T., Werth, C.J., Katz, L.E., Mohanty, K.K., 2020. Surfactant adsorption on shale samples: Experiments and an additive model. Energy & Fuels 34, 5436-5443.


Adsorption of surfactants in shales is not well studied. The goal of this work is to quantify and understand surfactant adsorption in several shale samples. Shale samples were obtained from several formations and are referred to by the formation names; but considering the fact that these formations are highly heterogeneous and huge, these few samples do not represent the shales. Shales are multimineral substrates with pores in the range of 1–300 nm. The adsorption capacity of three surfactants (cationic, nonionic, and anionic) on an Eagle Ford reservoir shale sample was measured. The cationic surfactant, cetyltrimethylammonium bromide (CTAB), showed the highest adsorption capacity in molar units, followed by anionic internal olefin sulfonate (IOS) C15-18 and then nonionic NP-40s. CTAB also had the highest adsorption in mass units, followed by NP-40 and then IOS. Adsorption of the anionic surfactant onto two pure minerals (calcite and quartz) and six shales were investigated, and all of them showed Langmuir-type sorption. The adsorption capacity of calcite and quartz are about the same (∼1.1 mg/g of rock). The adsorption capacity of shales depends on the mineral composition. The adsorption in Mancos outcrop and Green Shale samples is dominated by clay, whereas that in Wolfcamp and Eagle Ford outcrop shale samples is dominated by calcite. The adsorption in Eagle Ford (reservoir) and Marcellus shale samples is dominated by total organic carbon (TOC). An additive model was built to estimate the adsorption capacity, given the mineral composition and TOC. The model shows that organic matter and clay have the most significant impact on adsorption per unit mass; the contribution of each shale component on adsorption depends on its corresponding mass fraction.



Petrophysical properties are important parameters for quantitatively evaluating the production of oil and gas reservoirs. Shale reservoirs have complicated pore structures and solid compositions, which makes reservoir evaluations more difficult than the conventional reservoirs. As a nondestructive technique, nuclear magnetic resonance (NMR) has been widely applied in both laboratory and field explorations of shale reservoirs. Many researchers have measured water-saturated shale samples using NMR to investigate porosities, pore structures, and free fluid saturations. However, because of the presence of organic matter and complex wettabilities, saturating shale samples with different types of fluids may change the obtained results. To provide new insight into the petrophysical characterization of shale, we performed NMR experiments (both one-dimensional and two-dimensional NMR) on marine gas shale samples from the upper Ordovician Wufeng formation–the lower Silurian Longmaxi formation in the Sichuan Basin of China. Shale samples were examined by NMR in three states, including oil-saturated, water-saturated, and oven-dried. Moreover, we performed routine porosity measurements, scanning electron microscopy, and nitrogen (N2) adsorption experiments to comprehensively study the effect of different fluid saturation states on the petrophysical characterization results. The results indicate that more NMR signals can be detected by saturating shale with water, which is useful for estimating petrophysical properties; however, the T2 distributions of the water-saturated shale

samples provide limited information for gas production. The oil-saturated shale samples show two different shapes of T2 distributions. Shale samples from low-production wells show one main peak, while samples from high-production wells show distinct triple peaks in the T2 distributions (approximately at 0.22, 3.3, and 170 ms). These peaks represent the existence of microorganic pores, macroorganic pores, and microfractures. A novel identification graph of hydrogen-bearing compositions of organic-rich shale was put forward by analyzing the results of T1–T2 maps. The wettability index calculated with the NMR results was determined to be related to the gas production capacity of a well. The findings of our research studies will be useful for studying the pore type and wettability of shale and evaluating the gas production capacity of the well.

Zeng, Y., Shen, Z., Takahama, S., Zhang, L., Zhang, T., Lei, Y., Zhang, Q., Xu, H., Ning, Y., Huang, Y., Cao, J., Rudolf, H., 2020. Molecular absorption and evolution mechanisms of PM2.5 brown carbon revealed by electrospray ionization Fourier transform–ion cyclotron resonance mass spectrometry during a severe winter pollution episode in Xi'an, China. Geophysical Research Letters 47, e2020GL087977.

https://doi.org/10.1029/2020GL087977

Abstract: Knowledge of the molecular level chemistry of brown carbon (BrC) is important in ‐reducing the uncertainties in aerosol radiative forcing. Time resolved ambient PM‐ 2.5 samples were collected during a severe pollution episode in January 2017 over Xi'an, China for a comprehensive nontarget and full scanning of BrC molecules and their absorption properties using electrospray ionization Fourier transform–ion cyclotron resonance mass spectrometry combined with partial least squares regression analysis, which apportioned the overall ultraviolet absorption to individual molecules. The estimated absorption of CHNO and CHNOS molecules exhibited nighttime prevalence, whereas CHOS, CHNS, CHN, CHO, CHS, and CH molecules presented a dynamic trend. Carbon conjugation was positively correlated with estimated absorption by CHO and CHNO molecules, while exhibiting a mixed relationship with CHNOS. Higher nitrogen content was associated with enhanced light absorption properties of BrC molecules, while higher oxygen and ‐sulfur content appeared to be associated with photobleaching during secondary transformation.

Plain Language Summary: Individual molecular absorption has significant implications for ambient brown carbon analysis, but existing studies mostly focused on bulk absorption properties for the sample as a whole. A novel method is presented here to evaluate individual brown carbon absorption at the molecular level through high resolution mass spectrometry, and partial least squares regression analysis was applied to PM2.5 samples collected during a heavy pollution episode in Xi'an, China. Nitrogen containing compounds were found to be the strongest contributor to ‐brown carbon absorption, especially during the nighttime, while processes involving oxidation and sulfur addition appeared to weaken the molecular absorption. This study bridges the gap between real atmospheric PM2.5 absorption and knowledge from controlled laboratory studies, which support these findings.

Zhang, D., Wu, J., Yang, F., Chen, Q., Feng, J., Li, Q., Zhang, Q., Wang, W., Cheng, X., 2020. Linkages between soil organic carbon fractions and carbon-hydrolyzing enzyme activities across riparian zones in the Three Gorges of China. Scientific Reports 10, 8433.

https://doi.org/10.1038/s41598-020-65200-z

The effect of flooding on soil enzyme activities and soil organic carbon (SOC) dynamics remains a widely debated topic. Here, we investigated spatial variations in C-hydrolyzing enzyme activities, soil C contents in different fractions [i.e. labile and recalcitrant carbon (LC and RC)] from 6 sites with four different elevations at two soil depths (0–10 cm and 10–30 cm) in riparian zones of the Three Gorges Reservoir, China. At region scales, the SOC, RC contents, and RC/SOC (RIC) generally showed decreasing tendency from the upstream to the downstream. The C-hydrolyzing enzyme activities were higher in the midstream compared to other sites, which did not correspond well with the changing trend of SOC content, but matched with the spatial variation in LC content. At ecosystem scales, the RC and RIC declined with decreased elevations, but the LC showed opposite trend. Whereas, the four C-hydrolyzing enzyme activities and the specific enzyme activities were corresponded well with the changing trend of LC content. Soil C contents and enzyme activities were generally higher in top soil than deep soil across sites and elevation zones. These results reveal that the LC is the tightest factor in regulating C-hydrolyzing enzyme activities, whereas the soil C quality (i.e. RIC) and flooding collectively drive C-hydrolyzing enzyme activities possibly by affecting decomposition rates of SOC in the riparian zones.

Zhang, H., Hou, F., Xie, W., Wang, K., Zhou, X., Zhang, D., Zhu, X., 2020. Interaction and assembly processes of abundant and rare microbial communities during a diatom bloom process. Environmental Microbiology 22, 1707-1719.

https://doi.org/10.1111/1462-2920.14820

Diatom blooms can significantly influence the dynamics of microbial communities, yet little is known about the interaction and assembly mechanisms of abundant and rare taxa during bloom process. Here, using 16S rRNA gene amplicon sequencing, we investigated the co occurrence patterns and ‐assembly processes of abundant and rare microbial communities during an early spring diatom bloom in Xiangshan bay. Our results showed that α diversity indices in the rare subcommunity (RS) ‐were significantly higher than those in the abundant and common subcommunities. β Diversity of ‐the RS was the highest among three subcommunities, and the variation of β diversity in the three ‐subcommunities was mainly induced by species turnover, which was also the highest in the RS. The assembly of microbial communities was mainly driven by the neutral processes, but the roles of neutral processes might differ in each subcommunity. Co occurrence network analysis revealed that‐ abundant and common operational taxonomic units were more often located in central positions within the network. Most of the modules in the network were specific to a particular bloom stage, owing to the succession of Skeletonema costatum . Overall, these findings expand current understanding of the microbial interaction and assembly mechanisms in marine environment suffering harmful algal bloom disturbance.

Zhang, H.J., Lv, Y., Chua, C.K., Guo, T., Sun, Z., Zhan, Z., 2020. Mass spectral reconstruction of LC/MS data with entropy minimization. International Journal of Mass Spectrometry 454, 116359.


Liquid chromatography-mass spectrometry (LC/MS) is a major technique for the analysis of complex samples. Data processing for LC/MS untargeted analysis is very challenging due to the presence of asymmetric, co-eluted at trace-level peaks. We report a multivariate curve resolution approach based on entropy minimization to resolve LC/MS data. Our liquid chromatography band-target

entropy minimization (lc-BTEM) approach enables automated resolution of complex LC/MS peaks without the requirement of any parameter inputs. We demonstrated the performance of our approach on a co-eluted and trace-level peaks in an American ginseng extract. Consequently, we were able to putatively annotate the presence of more than 50 ginsenosides. The extracted pure mass spectra and in-source fragments information further enabled the annotation of [M+H]+, [M+H-Neu]+ and [M-H]- ions. This approach is expected to benefit LC/MS untargeted analysis and data independent analysis of complex samples.

Zhang, J., Han, F., Yang, Z., Zhang, L., Wang, X., Zhang, X., Jiang, Y., Chen, K., Pan, H., Lin, R., 2020. Significance of aquathermolysis reaction on heavy oil recovery during the steam-assisted gravity drainage process. Energy & Fuels 34, 5426-5435.


The steam-assisted gravity drainage (SAGD) process is effective to improve oil recovery performance, but it also promotes the aquathermolysis reaction of heavy oil under high-temperature reservoir environment. In the present work, a geological model considering core-catalyzed aquathermolysis was established and used to simulate mining in the SAGD process. Results showed that gas generation from aquathermolysis reaction was enhanced by core. Then, the gas production model considering aquathermolysis catalyzed by core was embedded into the geological model. The simulation results show that the main reaction areas of aquathermolysis occurred at the top of the reservoir and the liquid pool near the production well. The steam chamber growth was suppressed, and the simulation results of oil production and cumulative steam–oil ratio were closer to the actual recovery date. By adopting the new model, the recovery situation can be predicted more accurately, so that we can determine the impact of different harvest conditions on the SAGD process.


https://doi.org/10.1038/s41561-020-0571-8

Inland waters are large sources of methane to the atmosphere. However, considerable uncertainty exists in estimating the emissions of this potent greenhouse gas from global streams and rivers due, in part, to a lack of direct measurements in the high-altitude cryosphere and poor accounting for ebullition. Here we present methane concentrations and fluxes over three years in four basins on the East Qinghai–Tibet Plateau. Methane ebullition rates decrease exponentially whereas diffusion declines linearly with increasing stream order. Nonetheless, the average ebullition rate (11.9 mmolCH4 m−2 d−1) from these streams and rivers—which have large organic stocks in surrounding permafrost, abundant cold-tolerant methanogens, shallow water depths, and experience low air pressure—were six times greater than the global average and reached a maximum of 374.4 mmolCH4 m−2 d−1. Upscaled total emissions from sampled third- to seventh-order waterways of the East Qinghai–Tibet Plateau are estimated to be 0.20 TgCH4 yr−1, 79% of which was attributed to ebullition. These methane emissions are approximately 20% of CO2 emissions (2.70 TgCO2 yr−1) in terms of carbon release and two times greater in terms of CO2-equivalent emissions. When upscaled to first- to seventh-order waterways, we estimate emissions of 0.37–1.23 TgCH4 yr−1. Our findings

demonstrate that high-elevation rivers on the Qinghai–Tibet Plateau are hotspots of methane delivery to the atmosphere. The large ebullitive fluxes, which constitute a substantial fraction of global fluvial methane emissions, reveal a positive feedback between climate warming, permafrost thaw and methane emissions.

Zhang, Q., Luo, S., Zhao, L., Zhang, P., Wang, S., Sun, C., Zhang, L., 2020. Effect of Darcy flux on the release of dissolved organic matter and nitrogen from coal gangue in a coal mine underground reservoir: Column experiments. Chemical Geology 545, 119652.


Underground reservoirs packed with coal gangue have been widely used to store and purify mine water in the coal mine areas of China; however, minimal information is available about the effects of pollutants released from the packed matrix on the quality of stored water. Column experiments were performed at 25 °C and Darcy fluxes of 0.39, 0.73, and 1.56 cm/h to investigate the effect of Darcy flux on the dynamic changes of dissolved organic matter (DOM) and nitrogen released from the packed coal gangue. Results showed that the values of dissolved organic carbon (DOC), UV254, organic nitrogen (ORG-N), nitrate, and total dissolved solids (TDS) in the effluent decreased rapidly within 3.7 pore volumes (PV) at the three Darcy fluxes and then decreased slowly and tended to become stable during the column experiments. However, the effluent concentrations of NH4

+–N, which is the major nitrogen released from the packed matrix, and total nitrogen (TN) decreased and increased alternately, which can be relative to the lithology, mineral, and chemical composition of the studied matrix. The quantities of DOC, NH4

+–N, ORG-N, and TN released from the studied matrix decreased with Darcy flux, suggesting a positive effect of hydraulic retention time (HRT) on the resolution of pollutants from the studied matrix. Moreover, the microbial environment got weakened with an increase in Darcy flux, as confirmed by the variation trends of the biological/autochthonous index (BIX) and the fluorescence index (FI). Thus, the evident accumulation of NO2

− –N and the highest content of NO3−−N were observed due to incomplete

nitrate reduction with a low efficiency at 1.56 cm/h. The findings will be helpful in estimating the variation of water quality during the storage of mine water in a coal mine underground reservoir in China.


https://doi.org/10.1038/s41598-020-63054-z

In this study, systematic soil methane cycle geochemical monitoring was carried out in a typical gas hydrate region in the Qinghai-Tibet Plateau. Soil gas samples were collected for hydrocarbon components and carbon isotope analysis. Meanwhile, soil-methane fluxes from the upper active layer (20–30 cm) were monitored during six months of one year. The results of this research provide evidence of a new source of methane emission from wetland soils in permafrost regions: gas hydrate release. Sites with large methane emissions were found using flux monitoring, the characteristics of thermogenic methane were identified using carbon isotope tracing, and the relationship between emission by soils and effusion from gas hydrates was determined through correlation analyses of soil-adsorbed hydrocarbons. Seasonal variation of methane emissions are

also discussed by considering the emission of bacterial methane, thermogenic methane, and the absorption of methane from the soil active layer. These comprehensive findings provide valuable information for carbon cycle research of wetlands in permafrost regions.



Mapping the complete molecular composition of a lipidome is considered an important goal of lipidomics for unraveling pathways and mechanisms behind lipid homeostasis. Conventional dissociation methods of mass spectrometry (MS) usually cannot give detailed structural information on lipids such as locations of carbon–carbon double bonds (C═C) in acyl chains. Double-bond derivatization via the Paternò–Büchi (PB) reaction has been demonstrated as a simple and highly efficient method for identification of C═C locations of different classes of lipids when paired with tandem mass spectrometry (MS/MS). In this work, reversed-phase lipid chromatography (RPLC)-MS was coupled with an online PB reaction to achieve enhanced analysis of isomers and isobars of phospholipids. A new acetone-containing mobile phase was developed that showed good elution performance for the separation of phospholipids by C18 columns. An improved flow microreactor was developed, enabling online derivatization of phospholipid C═C in 20 s. The workflow of RPLC-PB-MS/MS was developed and optimized for identification of C═C locations in isobaric ether-linked and diacyl phospholipids, 13C isobars, and acyl chain isomers in biological lipid extracts. Separation and identification of C═C locations of cis/trans phospholipid isomers were achieved for lipid standards. The incorporation of the PB reaction into the RPLC-MS workflow enabled analysis of phospholipid isomers and isobars with high confidence, demonstrating its potential for high-throughput phospholipid identification from complex mixtures.



Massive occurrences of microbialites near the Permian–Triassic boundary have been interpreted as being due to benthic microbial proliferation in unusual marine conditions after the end-Permian mass extinction. Here, we present large populations of Polybessurus-like microfossils in the microbialites of the South China Craton to reveal their morphological structures, growth patterns, and ecological implications. These distinctive microfossils are composed of layered stalks and spherical endpoints. The spheroids, 20–40 μm in diameter, comprising external thin micritic walls and internal sparry parts, are interpreted as coccoid cyanobacteria. The stalks consist of multiple “stacked-cup” micritic envelopes consisting of micron-sized magnesian calcite/dolomite grains and are catalogued as calcified remains of coccoid cyanobacterial extracellular polymeric substances (EPS). Early microbially mediated calcification of EPS increased the preservation potential of microfossils. The microfossils stand upright as coccoid unicells supported by the highly unidirectional secretion of EPS, revealing their benthic behaviours. The successively secreted EPS lift the cells away from the substrate, expanding their ecological niches to gain more sunlight for photosynthesis in the barren marine floor. The distinctive Polybessurus-like microfossils can be viewed both in laminae of

stromatolites and in spotted/digitate clots of thrombolites, suggesting their critical roles in microbe-dominated reefs in the aftermath of the end-Permian mass extinction. The morphological features and growth patterns of the Polybessurus-like fossils resemble their Proterozoic counterpart—Polybessurus bipartitus Fairchild ex Green et al. (1987). The widespread Polybessurus-like fossils in the Permian–Triassic boundary microbialites of the South China Craton suggest pervasive retrogressive ecosystems on carbonate platforms after the largest extinction event during the Earth's history.

Zhang, X., Li, L.-F., Du, Z.-F., Hao, X.-L., Cao, L., Luan, Z.-D., Wang, B., Xi, S.-C., Lian, C., Yan, J., Sun, W.-D., 2020. Discovery of supercritical carbon dioxide in a hydrothermal system. Science Bulletin 65, 958-964.


Supercritical CO2 appearing as bubbles in hydrothermal vents was identified in the south part of the Okinawa Trough using in situ Raman spectroscopy. Significantly, the N2 peak in supercritical CO2 is much larger than those in seawater and vent fluids, indicating that supercritical CO2 enriches N2 from the surrounding environment. Considering that the partial pressures of CO2 and N2 in the Earth’s proto-atmosphere were ~10–20 MPa, supercritical CO2 with high N2 was likely the dominant CO2 phase near the water-air interface in the early history of the Earth, which promoted the synthesis, pre-enrichment and preservation of amino acids and other organic matters that are essential to the origin of life.


https://doi.org/10.1111/1755-6724.14328

The Songliao Basin is one of the most important petroliferous basins in northern China. With a recent gradual decline in conventional oil production in the basin, the exploration and development of unconventional resources are becoming increasingly urgent. The Qingshankou Formation consists of typical Upper Cretaceous continental strata, and represents a promising and practical replacement resource for shale oil in the Songliao Basin. Previous studies have shown that low‐mature to mature Qingshankou shale mainly preserves type I and type II1 organic matter, with relatively high total organic carbon (TOC) content. It is estimated that there is a great potential to explore for shale oil resources in the Qingshankou Formation in this basin. However, not enough systematic research has been conducted on pore characteristics and their main controlling factors in this lacustrine shale reservoir. In this study, 19 Qingshankou shales from two wells drilled in the study area were tested and analyzed for mineral composition, pore distribution and feature evolution using X ray diffraction (XRD), scanning electron microscopy (SEM), low pressure nitrogen ‐ ‐gas adsorption (N2 GA), and thermal simulation experiments. The XRD results show that clay, quartz,‐ and feldspar are the dominant mineral constituents of Qingshankou shale. The clay minerals are mostly illite/smectite mixed layers with a mean content of 83.5%, followed by illite, chlorite, and kaolinite. There are abundant deposits of clay rich shale in the Qingshankou Formation in the study ‐area, within which many mineral and organic matter pores were observed using SEM. Mineral pores

contribute the most to shale porosity; specifically, clay mineral pores and carbonate pores comprise most of the mineral pores in the shale. Among the three types of organic matter pores, type B is more dominant the other two. Pores with diameters greater than 10 nm supply the main pore volume; most are half open slits and wedge shaped pores. The total pore volume had no obvious ‐ ‐linear relationship with TOC content, but had some degree of positive correlation with the content of quartz + feldspar and clay minerals respectively. However, it was negatively correlated with carbonate mineral content. The specific surface area of the pores is negatively related to TOC content, average pore diameter, and carbonate mineral content. Moreover, it had a somewhat positive correlation with clay mineral content and no clear linear relationship with the content of quartz + feldspar. With increases in maturity, there was also an increase in the number of carbonate mineral dissolution pores and organic matter pores, average pore diameter, and pore volume, whereas there was a decrease in specific surface area of the pores. Generally, the Qingshankou shale is at a low mature to mature stage with a TOC content of more than 1.0%, and could be as ‐thick as 250 m in the study area. Pores with diameters of more than 10 nm are well developed in ‐the shale. This research illustrates that there are favorable conditions for shale oil occurrence and enrichment in the Qingshankou shale in the study area.

Zhang, Y.-X., Li, X., Li, F.-L., Ma, S.-C., Zheng, G.-D., Chen, W.-F., Li, W.-J., Wang, L., 2020. Paracoccus alkanivorans sp. nov., isolated from a deep well with oil reservoir water. International Journal of Systematic and Evolutionary Microbiology 70, 2312-2317.


A Gram-stain-negative, non-motile and ovoid bacterial strain, designated 4-2T, was isolated from oil-contaminated water which was collected from Xinjiang Province, north-west PR China. The 16S rRNA gene sequence analysis showed that strain 4-2T belonged to the genus Paracoccus . The species with highest similarity to strain 4-2T was Paracoccus saliphilus YIM 90738T (97.83 %), followed by ‘ Paracoccus siganidrum ’ M26 (97.83 %) and Paracoccus endophyticus SYSUP0003T (97.25 %). The average nucleotide identity values between 4-2T and three type strains were 84.69, 77.88 and 74.07 %, respectively. The genomic DNA G+C content of strain 4-2T was 61.4 mol%. Chemotaxonomical characteristic results showed that the respiratory quinone was ubiquinone Q-10 and the major fatty acids were summed feature 8 (C18 : 1 ω7c or C18 : 1 ω6c) and C19 : 0 cyclo ω8c. The polar lipid profile consisted of diphosphatidylglycerol, phosphatidylglycerol, phosphatidylcholine, unidentified phospholipids, an unidentified aminolipid and an unidentified polar lipid. The predominant polyamines were putrescine, cadaverine and spermidine. On the basis of phenotypic, chemotaxonomic and phylogenetic inferences, strain 4-2T represents a novel species of the genus Paracoccus , for which the name Paracoccus alkanivorans sp. nov. is proposed. The type strain is 4-2T (=CGMCC 1.13669T=LMG 30882T).

Zhang, Y., Sun, Y., Chen, J., 2020. Stable carbon isotope evidence for the origin of C28 steranes in lacustrine source rocks from the Qikou Sag, Bohai Bay Basin, Eastern China. Organic Geochemistry 145, 104028.


C27–C29 steranes are common constituents of crude oils and hydrocarbon source rocks and are usually dominated by either C27 or C29 compounds. In the current study, however, steranes

dominated by C28 components were detected in eight lacustrine source rock samples in the first member of the Shahejie Formation in the Qikou Sag, Bohai Bay Basin of Eastern China. Ratios of C28/(C27 + C28 + C29) ααα 20R steranes in four samples can exceeded 50%. Furthermore, C27 triaromatic steroids, presumably originating from C28 steranes, were also observed at high levels, relative to C26 and C28 homologues. Stable carbon isotope compositions of a C28 ααα 20R sterane and C27 20R triaromatic steroid were found to be similar, with δ13C at −37‰ and −36‰ respectively, much lower than values for pristane (by ∼7‰) and total organic carbon (by ∼10‰). The abnormally low δ13C values of the steroids suggest that C28 ααα 20R sterane was biosynthesized by algae blooming in the water column during phases of overturn and mixing, such as in autumn, during which recycled CO2 and nutrients welling up from hypolimnion to the epilimnion are assimilated, contributing to a high algal productivity and low δ13C in algal organic matter.

Zhang, Y., Yang, T., Hohl, S.V., Zhu, B., He, T., Pan, W., Chen, Y., Yao, X., Jiang, S., 2020. Seawater carbon and strontium isotope variations through the late Ediacaran to late Cambrian in the Tarim Basin. Precambrian Research 345, 105769.


The radiation of early animals during the Cambrian explosion was accompanied by widespread perturbations in oceanic and atmospheric conditions. However, the cause-effect relationships between evolutionary innovations, carbon (C) cycling, and continental weathering are still a matter of debate. Further paleoenvironmental reconstructions of poorly studied paleo-continents covering the Precambrian/Cambrian (PC/C) transition may improve the correlation of the events and their impact on the Earth system on a global scale. The Tarim Basin was presumably located proximal to the well-studied South China craton during the Ediacaran-Cambrian boundary and is expected to contribute equally to our paleoenvironmental reconstructions. Here we apply carbon and strontium (Sr) isotope records (δ13C and 87Sr/86Sr) obtained from well-preserved marine carbonates spanning the late Ediacaran to the late Cambrian from the Keping region in the northwestern Tarim Basin, NW China. By comparison to other carbonate successions from various paleo-continents, our obtained seawater 87Sr/86Sr curve in this study shows a stepwise first-order increase to more radiogenic values superimposed by second-order presumably regional variations. Our obtained δ13C variations exhibit four prominent negative and three positive excursions identical to the global δ13C record. Based on existing paleontological evidence and our new Tarim δ13C and 87Sr/86Sr curves, we propose a stratigraphic correlation from the late Ediacaran to the late Cambrian between the Tarim Basin and other paleo-continents. Besides, our paleoenvironmental reconstruction reveals both regional and global sea-level changes that may have controlled the influx of radiogenic Sr and presumably the influx of nutrients controlling primary production and the rate of organic carbon burial in the Tarim Basin at the time of deposition. These feedbacks may have ultimately influenced the rapid diversification of metazoans and the oxygenation of the Cambrian ocean and atmosphere approaching-present pO2 levels.

Zhang, Y., Yuan, C., Sun, M., Li, J., Long, X., Jiang, Y., Huang, Z., 2020. Molybdenum and boron isotopic evidence for carbon-recycling via carbonate dissolution in subduction zones. Geochimica et Cosmochimica Acta 278, 340-352.


Subduction zones are critical sites for carbon cycling between Earth’s surface and interior. However, how subducted carbon is released and transferred to the surface is not well understood, especially regarding the role of slab-derived fluids in the deep carbon cycle. Here we report Mo and B isotopic data for the Silurian normal arc andesites and adakitic andesites from the Chinese North Tianshan, which represent partial melts of fluid-modified mantle wedge and dehydrated oceanic crust, respectively. The normal arc andesites yielded δ98Mo values (0.33–1.08‰) significantly higher than that (about –0.20‰) of the depleted mantle. Because their limited range of SiO2 (53.8–55.3 wt.%) precludes differentiation as a cause for their variable δ98Mo values and Mo isotopic fractionation solely by fluid mobilization is limited (≤0.3‰), the elevated δ98Mo values could be ascribed to the incorporation of crustal material with heavy Mo isotopes in the mantle source. Since marine carbonate is featured by both heavy Mo and B isotopes and our normal arc andesites also give heavy δ11B (−1.63 to +4.00‰) values, we consider that marine carbonate was possibly involved as a component of the subducted slab, which modified Mo–B isotopic compositions of the mantle source. The positive correlations between δ98Mo and δ11B and between δ98Mo and Ba/Rb suggest transport of subducted carbonates to the overlying mantle wedge via slab fluids, thus providing robust evidence for transfer of subducted carbon to the overriding plate by carbonate dissolution. In contrast, the younger adakitic andesites have light δ98Mo (−0.48 to −0.27‰) and δ11B (−9.43 to −2.05‰) values, implying an isotopically Mo- and B-light source. Given the preferential transport of heavy 98Mo and 11B to the fluid phase during slab dehydration, their remarkably light δ98Mo and δ11B values support a dehydrated oceanic crust as their magma source. The contrasting Mo–B isotopes for such two kinds of andesites highlight that most carbonates can be removed from the subducted slab to the overriding plate during oceanic subduction.

Zhang, Y., Zhao, P., Cai, M., Lu, F., Wu, X., Guo, Z., 2020. Occurrence state and forming mechanism of microscopic remaining oil controlled by dynamic and static factors. Journal of Petroleum Science and Engineering 193, 107330.


In order to reveal the occurrence state and forming mechanism of multi-type microscopic remaining oil controlled by both static reservoir factors and dynamic development factors, cores of the alluvial fan reservoir in the eastern steep slope zone of the Cangdong sag, the Bohai Bay Basin, China was selected, and then the occurrence state of multi-type microscopic remaining oil was quantitatively characterized and the forming process and mechanism of multi-type microscopic remaining oil was discussed based on waterflooding experiments on glass etching models and CT scanning on waterflooding process in real cores, and the basic classification of microscopic remaining oil. The results show that the two-dimensional microscopic remaining oil as individual oil blocks can be divided into two movable types -- isolated and semi-filled in pores, two adhering types – to pore walls and pore corners, and two retained types –in pores and throats. The three-dimensional microscopic remaining oil as accumulated oil blocks can be divided into three types, including cluster remaining oil, droplet remaining oil and flocculent remaining oil. The greater the permeability, the weaker the heterogeneity, the greater the waterflooding rate and the more displacement along the paleocurrent direction, the more the retained remaining oil tends to be movable. Changing the measures of dynamic water injection, the remaining oil retained in pores is the easiest to be recovered, followed by the remaining oil retained in throats and that semi-filled in pores. The movable remaining oil is formed when oil blocks are dispersed or gradually peeled off after being swept by injected water; the adhering remaining oil is formed when the part between oil block and

pore wall or corner does not overcome its friction and capillary force and adheres to pore wall or corner; the retained remaining oil is the result that oil blocks are not swept or driven because of the bypassing injected water. The microscopic remaining oil as accumulated oil blocks is the aggregation of the microscopic remaining oil as independent oil blocks in a three-dimensional space.

Zhang, Y.G., Henderiks, J., Liu, X., 2020. Refining the alkenone-pCO2 method II: Towards resolving the physiological parameter ‘b’. Geochimica et Cosmochimica Acta 281, 118-134.


Haptophyte algal biomarkers called alkenones are widely used to reconstruct atmospheric CO2 in Earth’s Cenozoic history. This method is based on the notion that the algal carbon isotope fractionation during photosynthesis, as represented by εp37:2, is a function of seawater CO2 concentration and algal physiology. Constraining the algal physiological parameter, known as the ‘b’ term, is the key for successful applications of the alkenone-CO2 method. Using sensitivity analyses, we show that the growth rate (μ), cell size (r), and membrane permeability (P) are the most important variables to determine b. For all life on Earth, body size is a key factor that regulates metabolic rates. Exploiting the interdependence between phytoplankton cell size and growth rate, and specifically, the r – μ relationship for coccolithophores, we show that the length of fossil coccoliths (Lcoccolith) produced by ancient alkenone-synthesizers can be used to estimate r and therefore μ. Combining our new Lcoccolith data and published εp37:2 from the South China Sea Site MD01-2392, existing results from ODP Site 925, and ice core CO2, we determined the cell membrane permeability (P = 5.09 × 10−5 m s−1) for the Pleistocene community employing a bootstrap resampling technique. These new methods of constraining r, μ and P, combined with proxy-derived temperature (T), led us to rebuild b as a variable for each sample individually, which is subsequently used for alkenone-CO2 calculations. Application of this approach established pCO2 of the last 3 glacial-interglacial cycles, which turns out to be comparable with the ice core data in both the amplitude of changes and absolute values. It also reconciles the published Eocene – Oligocene alkenone-CO2 data which showed large geographical differences, with the new estimates much more consistent among different sites, and in line with other proxy-based results and ice sheet model predictions.



n-Alkan-2-ones (methyl ketones) ranging from C14 to C31, were recovered from the polar fraction of an extract of a torbanite from the Sydney Basin, Australia. There was a very slight even-over-odd predominance between C20 and C24 n-alkan-2-ones, together with remarkably high contents of the C24, C26 and C28 homologues. A range of C16 to C28 macrocyclic alkanes, as well as their corresponding methylated counterparts (C19–C24), was also detected in the saturate fraction obtained after molecular sieve treatments. Due to the relatively high contents of the n-alkan-2-ones and macrocyclic alkanes, we were able to carry out GC–irMS analysis to determine the δ13C values of specific compounds. The even-numbered n-alkan-2-ones from C24 to C28 were significantly 13C-enriched, compared to the other n-alkan-2-ones, which had similar isotopic values to the macrocyclic alkanes. The majority of the n-alkan-2-ones detected here probably had the same algal

source as the macrocyclic alkanes, which is likely to be lipids and algaenan of the green microalga Botryococcus braunii. However, the distribution and 13C enrichment of C24, C26 and C28 n-alkan-2-ones indicates that an additional source must be present.


https://doi.org/10.1007/s12517-020-05397-5

The coal seams in Kuba coalfield are near-vertical distributed, and the composition of the seepage channel and gas–water differentiation is quite different from that of the horizontal coal seam. By using high-precision tectonic fracture mapping technique, fine observation and dissection technique of coal reservoirs in the underground, and microscopic observation, the seepage channel model of near-vertical coal reservoir is established, and the gas–water distribution is researched. The seepage channel is mainly composed of four fractures, that is, tectonic fractures, bedding fractures, cleats, and micro-fractures. Furthermore, the characteristics of the four fractures are studied in detail; the dominant direction of coal reservoir permeability is analyzed. Coal seam water and gas in near-vertical coal reservoir have serious gas–water differentiation. Coal seam water moves to the lower coal and gas to the upper coal due to the influence of gravity. The seepage channel model and gas–water differentiation of near-vertical coal reservoir research the high-permeability area of coalbed methane (CBM) development block from the vertical and horizontal directions, which is of great significance for CBM development.

Zhao, C., Qiao, X., Shao, Q., Hassan, M., Ma, Z., 2020. Evolution of the lignin chemical structure during the bioethanol production process and its inhibition to enzymatic hydrolysis. Energy & Fuels 34, 5938-5947.


To illuminate the lignin evolution after hydrogen peroxide presoaking prior to ammonia fiber expansion (H-AFEX) pretreatment and enzymatic hydrolysis, ball-milled wood lignins were separated from untreated corn stover, H-AFEX-treated corn stover, and enzymatic hydrolyzed residue, labeled as UN-L, HA-L, and EH-L, respectively. The structural features of EH-L were compared with HA-L and UN-L by elemental analysis, GPC, FT-IR, and NMR. The inhibition deriving from lignin loading and the structure were assessed by adding UN-L/HA-L in enzymatic hydrolysis. The thermogravimetric analysis and thermal degradation kinetics analysis of EH-L were performed to evaluate its industrial utilization. The results showed that a significant decline in molecular weight was observed in EH-L, while the polydispersity index was almost unchanged. The decrease of the G unit and the increase of the S unit were shown in EH-L when comparing to UN-L. The G unit had the strongest inhibition to enzymatic hydrolysis, and the increasing relative proportion of S/G in lignin was beneficial for enzymatic hydrolysis. The resinol structure in lignin was relatively stable after pretreatment and enzymatic hydrolysis. The thermogravimetry analysis indicated that the EH-L exhibited better thermal stability than that of UN-L, offering potential to prepare lignin-based heat-resistant epoxy resin and new flame-resistant materials.

Zhao, D., Guo, Y., Wang, G., Li, G., Zeng, C., Jiao, W., 2020. Sequence stratigraphic framework and its influence on the development characteristics of shale reservoirs: Taking the Longmaxi Formation shale in the Sichuan Basin as an example. Acta Sedimentologica Sinica 38, 379-397.

http://www.cjxb.ac.cn/EN/abstract/abstract4100.shtml

To explore marine shale sedimentary sequences and their control on shale reservoir development characteristics,the sequence stratigraphic framework of the Longmaxi Formation in the sichuan Basin is synthetically established through the study of outcrops and cores in combination with experimental analysis(including a geochemical test,organic matter test,mineral composition test,pore development characteristics test,etc.)and logging wavelet analysis. The relationship between the sequence and reservoir development is also discussed in combination with the experimental study of the reservoir characteristics. The research shows that there are two third-order sequences and four mid-term cycles,A-D,developed in the Longmaxi Formation shale strata in the study area,and high-resolution sequence stratigraphy framework is established based on logging wavelet analysis of multi-cores in the study area. There are significant petrological differences between reservoirs of Cycle-A and Cycles B-D. The results show that the content of organic matter and brittleness micerals in Cycle A is higher,the horizontal bedding is more developed, and the microcosmic storage space(Micro-nano-scale pores and micro-fractures)is more developed than Cycles B-D. The correlation between the sequence cycle and reservoir composition,structure parameters,mechanical brittleness indexes,and gas-bearing characteristics indicates that sequence cycle is an important influencing factor for reservoir physical properties and gas-bearing capacity. Based on the experimental and analytical research results,the controlling mechanism of sequence stratigraphic framework on reservoir development is discussed. The differences of sedimentary environment and sedimentary conditions in each sequence cycle under the sequence stratigraphic framework lead to internal differences of sedimentary structure,material composition,and their distribution,affecting reservoir characteristics. The establishment of high-resolution sequence framework in sedimentary basins can provide a time frame for reservoir correlation,evaluation,and resource prediction. The establishment of logging high-resolution sequence stratigraphic framework based on logging wavelet analysis is helpful in reducing the interference of human subjectivity and provides a scientific basis and new approach for studying the genesis and prediction of high-quality shale reservoirs. Also,a new sequence framework-based workflow of reservoir characterization and evaluation for a shale reservoir is proposed based on reservoir internal analysis and evaluation.

Zhao, S., Pu, W., Varfolomeev, M.A., Liu, Y., Liu, Z., 2020. Oxidation characteristics of heavy oil and its SARA fractions during combustion using TG-FTIR. Journal of Petroleum Science and Engineering 192, 107331.


The oxidation reactions between air and crude oils play a key role in in-situ combustion (ISC). This study is intended to explore the oxidation characteristics of one heavy oil and its SARA fractions by thermogravimetry associated with Fourier transform infrared spectroscopy (TG-FTIR). The results indicated the release behavior of typical evolved gases (hydrocarbons, CO2, CO, and H2O) during oxidation for the oil and its SARA fractions existed huge difference because of different structures and compositions. The heavy oil encountered appreciable weight loss at the low temperature oxidation (LTO) region where hydrocarbons, CO2, H2O, etc., were released. Quite a few coke could be formed from the LTO residue of heavy oil during fuel deposition (FD), thus resulting in a

pronounced high temperature oxidation (HTO) stage characterized with apparent mass loss and one notably sharp peak of CO2. Saturates experienced a great amount of mass loss and release of hydrocarbons in the LTO regime. Aromatics showed obvious LTO and FD intervals in terms of mass loss and evolved gases, but its most of intermediate products during FD were evaporated with the temperature leading to the occurrence of weak HTO reactions. Resins was subjected to a small amount of mass loss and release of hydrocarbons and H2O in the LTO interval, and some of its intermediate products during FD formed coke through condensation reactions, which consequently led to a pronounced HTO stage. For asphaltenes, almost no hydrocarbons, CO2 and CO were released in the LTO region, and most of intermediate products at the initial FD stage condensed with each other to form coke. During HTO of asphaltenes, an extremely distinctive peak of CO2 and a small shoulder peak of CO and H2O were observed, verifying the occurrence of fierce combustion reactions.



Desert ecosystems with a high soil pH are considered as a sink for atmospheric CO2. Although high CO2-uptakevia chemical processes is the major CO2-uptake process in saline and alkaline soil, microorganisms may affect the exchange of inorganic carbon between the soil solution and the solid phase. Some studies related to microbial processes on carbonate formation have been published, but seldom focus on saline and alkaline soils. To determine the microbial effects on the inorganic C flux and CaCO3 recrystallization, sterile and non-sterile Solonchak samples were incubated in a 14CO2-labelled atmosphere at two CO2 concentrations (0.2% and 2%). The 14C activity was measured in the soil solution, air, and in CaCO3 after 2, 7, 21, 92 and 197 days. The 14C in dissolved organic carbon in the sterile and non-sterile soils was below 5% of the 14C input. 14C trapping in CaCO3 increased with the decrease of the 14C remaining in the gaseous CO2. Carbonate recrystallization increased logarithmically with time (R2 > 0.96). A two percent initial CO2 concentration lead to higher CaCO3 recrystallization (5–50 × 10−3% of initial CaCO3) compared to a 0.2% initial CO2 concentration (0.8–7 × 10−3% of initial CaCO3) from 2 to 197 days. CaCO3 recrystallization (% of initial CaCO3) in the sterile Solonchak was higher by 10% to 190% than the non-sterile Solonchak, indicating that the microorganisms decreased the 14C trapping of CaCO3 by 4–23% from 2 to 197 days. We assume that microorganisms grew on the carbonate surface like a coating. This must have retarded the carbonate recrystallization. We concluded that the soil CO2 concentration is the most important factor for CaCO3 recrystallization. The presence of microorganisms strongly decreased the CaCO3 recrystallization. CaCO3 recrystallization process including CO2 in soil water could be the abiotic CO2 uptake from the atmosphere by saline and alkaline soil.

Zhao, Y., Tzedakis, P.C., Li, Q., Qin, F., Cui, Q., Liang, C., Birks, H.J.B., Liu, Y., Zhang, Z., Ge, J., Zhao, H., Felde, V.A., Deng, C., Cai, M., Li, H., Ren, W., Wei, H., Yang, H., Zhang, J., Yu, Z., Guo, Z., 2020. Evolution of vegetation and climate variability on the Tibetan Plateau over the past 1.74 million years. Science Advances 6, eaay6193.

http://advances.sciencemag.org/content/6/19/eaay6193.abstract

The Tibetan Plateau exerts a major influence on Asian climate, but its long-term environmental history remains largely unknown. We present a detailed record of vegetation and climate changes over the past 1.74 million years in a lake sediment core from the Zoige Basin, eastern Tibetan Plateau. Results show three intervals with different orbital- and millennial-scale features superimposed on a stepwise long-term cooling trend. The interval of 1.74–1.54 million years ago is characterized by an insolation-dominated mode with strong ~20,000-year cyclicity and quasi-absent millennial-scale signal. The interval of 1.54–0.62 million years ago represents a transitional insolation-ice mode marked by ~20,000- and ~40,000-year cycles, with superimposed millennial-scale oscillations. The past 620,000 years are characterized by an ice-driven mode with 100,000-year cyclicity and less frequent millennial-scale variability. A pronounced transition occurred 620,000 years ago, as glacial cycles intensified. These new findings reveal how the interaction of low-latitude insolation and high-latitude ice-volume forcing shaped the evolution of the Tibetan Plateau climate.

Zheng, D., Chang, S.-C., Algeo, T., Zhang, H., Wang, B., Wang, H., Wang, J., Feng, C., Xu, H., 2020. Age constraint for an earliest Famennian forest and its implications for Frasnian-Famennian boundary in West Junggar, Northwest China. Palaeogeography, Palaeoclimatology, Palaeoecology 552, 109749.


As one of the five major extinction events in Earth history, the Frasnian-Famennian boundary (FFB) crisis caused dramatic reductions in marine and terrestrial diversity. The effects of this event on terrestrial ecosystems are not well understood due to the limited preservation of terrestrial sedimentary rocks and the relative scarcity of plant fossils. This study generates a robust zircon U-Pb age (371.5 ± 0.9 Ma; earliest Famennian) for a new fossil assemblage containing Lycopsida, Archaeopteridales, and Cladoxylopsida from the upper Zhulumute Formation of the West Junggar Basin, NW China. These taxa are typical arborescent plants of the Late Devonian and represent the oldest-known forest in China, documenting afforestation in West Junggar coevally with or just after the Upper Kellwasser event (~372 Ma). The new U-Pb ages generated in this study refine the placement of the FFB in West Junggar to within the Zhulumute Formation, instead of the Hongguleleng Formation as previously thought.



The response of microbial communities to releases of hydraulic fracturing flowback and produced water (PW) may influence ecosystem functions. However, knowledge of the effects of PW spills on freshwater microbiota is limited. Here, we conducted two separate experiments: 16S rRNA gene sequencing combined with random forests modelling was used to assess freshwater community changes in simulated PW spills by volume from 0.05% to 50%. In a separate experiment, live/dead cell viability in a freshwater community was tested during exposure to 10% PW by volume. Three distinct patterns of microbial community shifts were identified: (i) indigenous freshwater genera remained dominant in <2.5% PW, (ii) from 2.5% to 5% PW, potential PW organic degraders such as Pseudomonas, Rheinheimera and Brevundimonas became dominant, and (iii) no significant change in the relative abundance of taxa was observed in >5% PW. Microbial taxa including less abundant

genera such as Cellvibrio were potential bioindicators for the degree of contamination with PW. Additionally, live cells were quickly damaged by adding 10% PW, but cell counts recovered in the following days. Our study shows that the responses of freshwater microbiota vary by spill size, and these responses show promise as effective fingerprints for PW spills in aquatic environments.

Zhou, L., Lu, Y.-W., Wang, D.-W., Zhang, S.-L., Tang, E.-G., Qi, Z.-Z., Xie, S.-N., Wu, J., Liang, B., Liu, J.-F., Yang, S.-Z., Zhang, J., Gu, J.-D., Mu, B.-Z., 2020. Microbial community composition and diversity in production water of a high-temperature offshore oil reservoir assessed by DNA- and RNA-based analyses. International Biodeterioration & Biodegradation 151, 104970.


Microbial activity is ubiquitous and important in petroleum reservoir systems; however, current knowledge regarding the diversity and functions of microbial communities that are active in offshore petroleum reservoirs remains very limited. In the present work, high-throughput sequencing analysis of the 16S rRNA gene (DNA) and transcripts (RNA) was applied to respectively characterize the genomic and active microbial communities from two production wells in a high-temperature offshore oilfield in China. The results showed that the microbial community compositions in the two wells (X1 and X2) were very different. At the genus level, the dominant members in both genomic and active communities of sample X1 were Bosea, Acinetobacter, Sphingomonas, Candidatus Methanofastidiosum and Methanocalculus. Both genomic and active communities in sample X2 were mainly represented by Pseudomonas, Acinetobacter, Methanothermobacter, Methanosaeta, Candidatus Nitrosopumilus, Candidatus Methanomethylicus, Thermococcus, Candidatus Methanofastidiosum and Methanocalculus. Moreover, using an RNA-based approach, genera with a very low abundance and even undetected genera (based on a DNA approach) were shown to have increased activity. Besides the abundant active members, the comparison between the DNA- and RNA-based datasets also permitted the identification of genera that were relatively more active in the two production water samples. The existence of these active microorganisms suggested they might have potential functions associated with reservoir issues in the offshore oilfield. This study highlights the importance of assessing microbial diversity through a combination of DNA- and RNA-based analyses, and promotes a comprehensive and deep understanding of microbial compositions and their roles in offshore petroleum reservoirs.

Zhou, X., Kang, F., Qu, X., Fu, H., Alvarez, P.J.J., Tao, S., Zhu, D., 2020. Role of extracellular polymeric substances in microbial reduction of arsenate to arsenite by Escherichia coli and Bacillus subtilis. Environmental Science & Technology 54, 6185-6193.


We show that arsenate can be readily reduced to arsenite on cell surfaces of common bacteria (E. coli or B. subtilis) or in aqueous dissolved extracellular polymeric substances (EPS) extracted from different microorganisms (E. coli, B. subtilis, P. chrysosporium, D. gigas, and a natural biofilm) in the absence of exogenous electron donors. The efficiency of arsenate reduction by E. coli after a 7-h incubation was only moderately reduced from 51.3% to 32.7% after knocking out the arsenic resistance genes (arsB and arsC). Most (>97%) of the reduced arsenite was present outside the bacterial cells, including for the E. coli blocked mutant lacking arsB and arsC. Thus, extracellular processes dominated arsenate reduction. Arsenate reduction was facilitated by removing EPS

attached to E. coli or B. subtilis, which was attributed to enhanced access to reduced extracellular cytochromes. This highlights the role of EPS as a permeability barrier to arsenate reduction. Fourier-transform infrared (FTIR) combined with other chemical analyses implicated some low-molecular weight (<3 kDa) molecules as electron donors (reducing saccharides) and electron transfer mediators (quinones) in arsenate reduction by dissolved EPS alone. These results indicate that EPS act as both reducing agent and permeability barrier for access to reduced biomolecules in bacterial reduction of arsenate.

Zhou, Y., Ni, H., Shen, Z., Wang, M., 2020. Study on proppant transport in fractures of supercritical carbon dioxide fracturing. Energy & Fuels 34, 6186-6196.


Supercritical carbon dioxide (SC-CO2) fracturing is a promising stimulation treatment in the unconventional oil and gas industry, which combines the utilization of greenhouse gas and the development of energy resources. Aiming to study the proppant transport in fractures, which is one of the most important issues in this technology, a generalized and pragmatic numerical method coupled with multiphase flows, physical property models of CO2, and heat and mass transfer in the formation rock has been established to calculate the proppant transport in fractures of SC-CO2 fracturing. Experimentally, experimental validation of the proppant transport was conducted, which verifies the accuracy of the simulation results. Combining experimental and simulation results, the flow condition of proppant–CO2 two-phase flow was divided into a stationary layer, a rolling layer, a saltatory layer, a suspending layer, and a pure liquid/gas layer. Numerically, movement laws of proppant beds in fracture and influence factors on the distribution of proppant beds were analyzed. Proppant bed was formed near the inlet of the fracture at the initial stage of fracturing, and the height and length of the bed would increase concurrently until reaching a steady state. The equilibrium height has positive correlations with the injection temperature, proppants’ volume fraction, density, and diameter and negative correlations with the injection pressure and displacement. Nevertheless, the equilibrium time has negative correlations with all these factors except pressure. Additionally, the proppant transports of SC-CO2 and water were compared, which indicated that water has better proppant-carrying capacity with lower proppant bed height and longer proppant bed length at the same fracturing time. The distribution of the proppant bed with the structure of a nozzle inlet is relatively homogeneous in the near-wellbore zone of the fracture compared to the cuboid structure, which could reduce the risk of fracture closure in the near-wellbore zone. Results obtained in this paper could provide references for SC-CO2 fracturing design which would promote the development of this technology.

Zhu, J., Yang, H., Hu, H., Zhou, Y., Li, J., Jin, L., 2020. Novel insight into pyrolysis behaviors of lignin using in-situ pyrolysis-double ionization time-of-flight mass spectrometry combined with electron paramagnetic resonance spectroscopy. Bioresource Technology 312, 123555.


In-situ detection on primary volatiles and stable radicals is of great importance for better understanding of lignin pyrolysis mechanisms and utilization. In this study, a novel in-situ pyrolysis time-of-flight mass spectrometry with double ionization sources was taken to in-situ detect primary volatiles and gas products, and the evolution of stable radicals in lignin pyrolysis residues was

explored by EPR spectroscopy. The results show that the cleavage of β-O-4 linkage is mainly responsible for lignin depolymerization at 100−300 °C, releasing the G-type compounds. And these G-type compounds can further undergo O-CH3, Car-OCH3 and Car-OH bond cleavages to form biphenolic hydroxyl compounds, phenols and aromatic hydrocarbons. According to the EPR analysis, the radical concentration increased from 1017 to 1019 spins/g with the temperature, and stable free-radical species are mainly composed of the o-methoxy and hydroxyl substituted phenoxy radicals and carbon-centered aromatic radicals, which can well interpret the demethylation, demethoxylation and dehydroxylation mechanisms.

Zhu, L., Shi, W., Van Dam, B., Kong, L., Yu, J., Qin, B., 2020. Algal accumulation decreases sediment nitrogen removal by uncoupling nitrification-denitrification in shallow eutrophic lakes. Environmental Science & Technology 54, 6194-6201.


In eutrophic lakes, the decay of settled algal biomass generates organic carbon and consumes oxygen, favoring sediment nitrogen loss via denitrification. However, persistent winds can cause algae to accumulate into dense mats, with uncertain impacts on sediment nitrogen removal. In this study, we investigated the effects of algal accumulation on sediment nitrogen removal in a shallow and eutrophic Chinese lake, Taihu. We found that experimental treatments of increased algal accumulation were associated with decreased sediment nitrogen losses, indicating the potential for a break in coupled nitrification-denitrification. Likewise, field measurements indicated similar decreases in sediment nitrogen losses when algal accumulation occurred. It is possibly caused by the decay of excess algal biomass, which likely depleted dissolved oxygen, and could have inhibited nitrification and thereby denitrification in sediments. We estimate that if such algal accumulations occurred over 20% or 10% of lake area in Taihu, sediment nitrogen removal rates decreased from 835.6 to 167.2 and 77.2 μmol N m–2h–1, respectively, during algal accumulation period. While nitrogen removal may recover later, the apparent nitrogen removal decrease may create a window for algal proliferation and intensification. This study advances our knowledge on the impacts of algal blooms on nitrogen removal in shallow eutrophic lakes.

Zhu, Z.-Y., Oakes, J., Eyre, B., Hao, Y., Sia, E.S.A., Jiang, S., Müller, M., Zhang, J., 2020. The nonconservative distribution pattern of organic matter in the Rajang, a tropical river with peatland in its estuary. Biogeosciences 17, 2473-2485.


Southeast Asian peatland-draining rivers have attracted much attention due to their high dissolved organic carbon (DOC) yield and high CO2 emissions under anthropogenic influences. In August 2016, we carried out a field investigation of the Rajang River and its estuary, a tropical system located in Sarawak, Malaysia. The Rajang has peatland in its estuary, while the river basin is covered by tropical rainforest. DOC-δ13C in the Rajang ranged from −28.7 ‰ to −20.1 ‰, with a U-shaped trend from river to estuary. For particulate organic carbon (POC), δ13C ranged between −29.4 ‰ and −31.1 ‰ in the river, and there was a clear increasing trend towards more enriched δ13C values with higher salinity. In the estuary, there was a linear conservative dilution pattern for dissolved organic matter composition (as quantified by D- and L-amino acid enantiomers) plotted against DOC-δ13C, whereas when plotted against salinity, dissolved D- and L-amino acid enantiomer values were higher than the

theoretical dilution value. Together, these data indicate that the addition of DOC to the estuary (by peatland) not only increased the DOC concentration but also altered its composition, by adding more biodegraded, 13C-depleted organic matter into the bulk dissolved organic matter. Alteration of organic matter composition (addition of a more degraded subpart) was also apparent for the particulate phase, but patterns were less clear. The Rajang was characterized by DOC to DON (dissolved organic nitrogen) ratios of 50 in the river section, with loss of DON in the estuary increasing the ratio to 140, suggesting an unbalanced export of organic carbon and nitrogen. Where affected by anthropogenic activities, further assessment of organic carbon to nitrogen ratios is needed.


https://www.frontiersin.org/article/10.3389/feart.2020.00152

Mounting evidence suggests that biogeochemical processing of permafrost substrate will amplify dissolved inorganic carbon (DIC = Σ[CO2, HCO3,- CO3

-2]) production within Arctic freshwaters. The effects of permafrost thaw on DIC may be particularly strong where terrain subsidence following thaw (thermokarst) releases large amounts of sediment into fluvial networks. The mineral composition and chemical weathering of these sediments has critical yet untested implications for the degree to which streams represent a source of CO2 to the atmosphere vs. a source of bicarbonate to downstream environments. Here, we experimentally determine the effects of mineral weathering on fluvial CO2 by incubating sediments collected from three retrogressive thaw slump features on the Peel Plateau (NWT, Canada). Prehistoric warming and contemporary thermokarst have exposed sediments on the Peel Plateau to varying degrees of thaw and chemical weathering, allowing us to test the role of permafrost and substrate mineral composition on CO2:HCO3

− balance. We found that recently-thawed sediments (within years to decades) and previously un-thawed tills from deeper permafrost generated substantial amounts of solutes and DIC. These solutes and the mineralogy of sediments suggested that carbonate weathering coupled with sulfide oxidation was a net source of abiotic CO2. Yet, on average, more than 30% of this CO2 was converted to bicarbonate via carbonate buffering reactions. In contrast, the mineralogy and geochemical trends associated with sediments from the modern and paleo-active layer, which were exposed to thaw over longer timescales than deeper permafrost sediments, more strongly reflected silicate weathering. In treatments with sediment from the modern and paleo-active layer, minor carbonate and sulfide weathering resulted in some DIC and net CO2 production. This CO2 was not measurably diminished by carbonate buffering. Together, these trends suggest that prior exposure to thaw and weathering on the Peel Plateau reduced carbonate and sulfide in upper soil layers. We conclude that thermokarst unearthing deeper tills on the Peel Plateau will amplify regional inorganic carbon cycling for decades to centuries. However, CO2 consumption via carbonate buffering may partly counterbalance CO2 production and release to the atmosphere. Regional variability in the mineral composition of permafrost, thaw history, and thermokarst intensity are among the primary controls on mineral weathering within permafrost carbon-climate feedbacks.

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