Organic proxies for paleoclimate · 2019-10-29 · Organic proxies for paleoclimate Sabine Lengger...
Transcript of Organic proxies for paleoclimate · 2019-10-29 · Organic proxies for paleoclimate Sabine Lengger...
![Page 1: Organic proxies for paleoclimate · 2019-10-29 · Organic proxies for paleoclimate Sabine Lengger University of Plymouth, UK BETR workshop September ... What Fossil Molecules Reveal](https://reader030.fdocuments.net/reader030/viewer/2022040610/5ecebb2145693554a363aea9/html5/thumbnails/1.jpg)
Organic proxies for paleoclimate
Sabine LenggerUniversity of Plymouth, UKBETR workshop September 2018, XTBG
![Page 2: Organic proxies for paleoclimate · 2019-10-29 · Organic proxies for paleoclimate Sabine Lengger University of Plymouth, UK BETR workshop September ... What Fossil Molecules Reveal](https://reader030.fdocuments.net/reader030/viewer/2022040610/5ecebb2145693554a363aea9/html5/thumbnails/2.jpg)
Assistant professor* at the University of PlymouthInterests: Organic biomarkers, proxy development, analytical methodsTime periods: Contemporary Æ DevonianOpen access
Æ EarthArXiV.org
* In the UK, Assisstant professors are called “Lecturer”
![Page 3: Organic proxies for paleoclimate · 2019-10-29 · Organic proxies for paleoclimate Sabine Lengger University of Plymouth, UK BETR workshop September ... What Fossil Molecules Reveal](https://reader030.fdocuments.net/reader030/viewer/2022040610/5ecebb2145693554a363aea9/html5/thumbnails/3.jpg)
Plymouth
![Page 4: Organic proxies for paleoclimate · 2019-10-29 · Organic proxies for paleoclimate Sabine Lengger University of Plymouth, UK BETR workshop September ... What Fossil Molecules Reveal](https://reader030.fdocuments.net/reader030/viewer/2022040610/5ecebb2145693554a363aea9/html5/thumbnails/4.jpg)
Developed in Plymouth: Sea ice proxy IP25
Belt et al. (2013)
Belt et al. (2007)
![Page 5: Organic proxies for paleoclimate · 2019-10-29 · Organic proxies for paleoclimate Sabine Lengger University of Plymouth, UK BETR workshop September ... What Fossil Molecules Reveal](https://reader030.fdocuments.net/reader030/viewer/2022040610/5ecebb2145693554a363aea9/html5/thumbnails/5.jpg)
Overview
1. Lipids: a brief history of organic geochemistry2. Alkenones / UK
37
3. GDGTs / TEX86• Practical
4. Branched GDGTs / MBT/CBT • Practical
5. n-alkanes6. Isotopes!
• Practical
![Page 6: Organic proxies for paleoclimate · 2019-10-29 · Organic proxies for paleoclimate Sabine Lengger University of Plymouth, UK BETR workshop September ... What Fossil Molecules Reveal](https://reader030.fdocuments.net/reader030/viewer/2022040610/5ecebb2145693554a363aea9/html5/thumbnails/6.jpg)
Lipids & brief history of organic geochemistry
![Page 7: Organic proxies for paleoclimate · 2019-10-29 · Organic proxies for paleoclimate Sabine Lengger University of Plymouth, UK BETR workshop September ... What Fossil Molecules Reveal](https://reader030.fdocuments.net/reader030/viewer/2022040610/5ecebb2145693554a363aea9/html5/thumbnails/7.jpg)
1. Lipids – a brief history of organic geochemistry
Lipids: A loosely defined term for substances of biological origin that are soluble in nonpolar solvents. They consist of saponifiable lipids, such as glycerides (fats and oils) and phospholipids, as well as nonsaponifiable lipids, principally steroids.
![Page 8: Organic proxies for paleoclimate · 2019-10-29 · Organic proxies for paleoclimate Sabine Lengger University of Plymouth, UK BETR workshop September ... What Fossil Molecules Reveal](https://reader030.fdocuments.net/reader030/viewer/2022040610/5ecebb2145693554a363aea9/html5/thumbnails/8.jpg)
Lipid membranes – basic structures
Prokaryota
Hopanols
Eukaryota
Sterols
Fatty acids
Diacylglycerols
by Charles West
![Page 9: Organic proxies for paleoclimate · 2019-10-29 · Organic proxies for paleoclimate Sabine Lengger University of Plymouth, UK BETR workshop September ... What Fossil Molecules Reveal](https://reader030.fdocuments.net/reader030/viewer/2022040610/5ecebb2145693554a363aea9/html5/thumbnails/9.jpg)
Types of membrane lipids
Schubotz (2009)
![Page 10: Organic proxies for paleoclimate · 2019-10-29 · Organic proxies for paleoclimate Sabine Lengger University of Plymouth, UK BETR workshop September ... What Fossil Molecules Reveal](https://reader030.fdocuments.net/reader030/viewer/2022040610/5ecebb2145693554a363aea9/html5/thumbnails/10.jpg)
Other “lipids”
• Pigments: adsorption of / protection from radiation• Carotenoids• Porphyrins
• Storage lipids• Alkenones• Long-chain diols (?)
• Transpiration protection• n-alkanes in leaves
![Page 11: Organic proxies for paleoclimate · 2019-10-29 · Organic proxies for paleoclimate Sabine Lengger University of Plymouth, UK BETR workshop September ... What Fossil Molecules Reveal](https://reader030.fdocuments.net/reader030/viewer/2022040610/5ecebb2145693554a363aea9/html5/thumbnails/11.jpg)
Why are lipids good biomarkers?
1. Easy to analyse
2. Recalcitrant
pKa ≈ 50http://web.chem.ucla.edu/~harding/IGOC/S/sigma_bond.html
3. Specific
Eglinton et al. (1962)
![Page 12: Organic proxies for paleoclimate · 2019-10-29 · Organic proxies for paleoclimate Sabine Lengger University of Plymouth, UK BETR workshop September ... What Fossil Molecules Reveal](https://reader030.fdocuments.net/reader030/viewer/2022040610/5ecebb2145693554a363aea9/html5/thumbnails/12.jpg)
Isorenieratene biomarker
![Page 13: Organic proxies for paleoclimate · 2019-10-29 · Organic proxies for paleoclimate Sabine Lengger University of Plymouth, UK BETR workshop September ... What Fossil Molecules Reveal](https://reader030.fdocuments.net/reader030/viewer/2022040610/5ecebb2145693554a363aea9/html5/thumbnails/13.jpg)
Isorenieratane
• Isorenieratane is a biomarker for Chlorobiaceae, bacteria which thrive under anoxic, sulfidic conditions but need light too.
• Photic zone euxinia.
http://ocw.mit.edu/courses/earth-atmospheric-and-planetary-sciences/12-158-molecular-biogeochemistry-fall-2011/lecture-notes
Isorenieratene
Isorenieratane
![Page 14: Organic proxies for paleoclimate · 2019-10-29 · Organic proxies for paleoclimate Sabine Lengger University of Plymouth, UK BETR workshop September ... What Fossil Molecules Reveal](https://reader030.fdocuments.net/reader030/viewer/2022040610/5ecebb2145693554a363aea9/html5/thumbnails/14.jpg)
Biomarker Tree of Life
Many types of organisms have specific biomarkers
Briggs and Summons (2014)
![Page 15: Organic proxies for paleoclimate · 2019-10-29 · Organic proxies for paleoclimate Sabine Lengger University of Plymouth, UK BETR workshop September ... What Fossil Molecules Reveal](https://reader030.fdocuments.net/reader030/viewer/2022040610/5ecebb2145693554a363aea9/html5/thumbnails/15.jpg)
The analysis of biomarkers
Rockmin 0.1 % TOC
crush
grindPowder
ExtractionElevated temperatureSoxhlet extractionElevated temperature, pressureAccelerated solvent extractionMicrowave extraction Low temperatureBligh Dyer extractionUltrasonic extraction
Gaines et al. (2009)
![Page 16: Organic proxies for paleoclimate · 2019-10-29 · Organic proxies for paleoclimate Sabine Lengger University of Plymouth, UK BETR workshop September ... What Fossil Molecules Reveal](https://reader030.fdocuments.net/reader030/viewer/2022040610/5ecebb2145693554a363aea9/html5/thumbnails/16.jpg)
Analysis of Biomarkers
In which fraction do we expect to find biomarkers?
Hexane/DCM 9:1(Aliphatic
Hydrocarbons)
Hexane/DCM 1:1(Aromatic Hydrocarbons,
ketones)
DCM/Methanol 1:1
e.g.R
R
e.g. e.g.
CO2H
by Charles West
![Page 17: Organic proxies for paleoclimate · 2019-10-29 · Organic proxies for paleoclimate Sabine Lengger University of Plymouth, UK BETR workshop September ... What Fossil Molecules Reveal](https://reader030.fdocuments.net/reader030/viewer/2022040610/5ecebb2145693554a363aea9/html5/thumbnails/17.jpg)
Mixture of compoundsVolatilised
Stationary phase
Compounds separated in time
Heat
Gas flow
Detector
Chromatography
typically 10 – 60 m
![Page 18: Organic proxies for paleoclimate · 2019-10-29 · Organic proxies for paleoclimate Sabine Lengger University of Plymouth, UK BETR workshop September ... What Fossil Molecules Reveal](https://reader030.fdocuments.net/reader030/viewer/2022040610/5ecebb2145693554a363aea9/html5/thumbnails/18.jpg)
Gas chromatogram: aliphatic Hydrocarbon fraction
1615
14
13
12
11
10
1819 20
21
22 23
2425
2627
28 2930
17 n-alkanes usually dominate
Retention Timeby Charles West
![Page 19: Organic proxies for paleoclimate · 2019-10-29 · Organic proxies for paleoclimate Sabine Lengger University of Plymouth, UK BETR workshop September ... What Fossil Molecules Reveal](https://reader030.fdocuments.net/reader030/viewer/2022040610/5ecebb2145693554a363aea9/html5/thumbnails/19.jpg)
CULE
Organic mass spectrometry
• Ionised molecule ÆMolecular ion
• Breaks apart into smaller fragments
• Weight is detected (only positively charged)
• Largest mass Æmolecular mass
MOLECULE
MOLECULE
Ionisation
+•
MOLE• + LECULEMO • +•
Fragmentation
UE+CLLE+CU
FragmentationRearrangement
![Page 20: Organic proxies for paleoclimate · 2019-10-29 · Organic proxies for paleoclimate Sabine Lengger University of Plymouth, UK BETR workshop September ... What Fossil Molecules Reveal](https://reader030.fdocuments.net/reader030/viewer/2022040610/5ecebb2145693554a363aea9/html5/thumbnails/20.jpg)
n-Hexane
8671
5743
29
15
C4H9+
C3H7+
C2H5+
M+∙
Base peak
![Page 21: Organic proxies for paleoclimate · 2019-10-29 · Organic proxies for paleoclimate Sabine Lengger University of Plymouth, UK BETR workshop September ... What Fossil Molecules Reveal](https://reader030.fdocuments.net/reader030/viewer/2022040610/5ecebb2145693554a363aea9/html5/thumbnails/21.jpg)
Branched alkanes
71
127
![Page 22: Organic proxies for paleoclimate · 2019-10-29 · Organic proxies for paleoclimate Sabine Lengger University of Plymouth, UK BETR workshop September ... What Fossil Molecules Reveal](https://reader030.fdocuments.net/reader030/viewer/2022040610/5ecebb2145693554a363aea9/html5/thumbnails/22.jpg)
Straight-chain vs branched alkanes
71
127
m/z 14 series
![Page 23: Organic proxies for paleoclimate · 2019-10-29 · Organic proxies for paleoclimate Sabine Lengger University of Plymouth, UK BETR workshop September ... What Fossil Molecules Reveal](https://reader030.fdocuments.net/reader030/viewer/2022040610/5ecebb2145693554a363aea9/html5/thumbnails/23.jpg)
Which one is the straight chain alkane?
141
57
71
127
43
127
m/z 14 series
AA B
C D
![Page 24: Organic proxies for paleoclimate · 2019-10-29 · Organic proxies for paleoclimate Sabine Lengger University of Plymouth, UK BETR workshop September ... What Fossil Molecules Reveal](https://reader030.fdocuments.net/reader030/viewer/2022040610/5ecebb2145693554a363aea9/html5/thumbnails/24.jpg)
A three dimensional technique
http://people.whitman.edu/~dunnivfm/C_MS_Ebook/CH5/index.html
![Page 25: Organic proxies for paleoclimate · 2019-10-29 · Organic proxies for paleoclimate Sabine Lengger University of Plymouth, UK BETR workshop September ... What Fossil Molecules Reveal](https://reader030.fdocuments.net/reader030/viewer/2022040610/5ecebb2145693554a363aea9/html5/thumbnails/25.jpg)
Recommended ReadingIntroduction to organic geochemistryS. D. Killops and V. J. KillopsBlackwell Pub (2005). Available for free (legally!) at: https://sites.google.com/site/killopsiog/
Echoes of Life: What Fossil Molecules Reveal about Earth History. S. M. Gaines, G. Eglinton and J. Rullkötter. Oxford University Press (2009).
Biomarkers and Isotopes in the Environment and Human History. K. E. Peters, C. C. Walters and J. M. Moldowan. Cambridge Univ. Press (2005).
![Page 26: Organic proxies for paleoclimate · 2019-10-29 · Organic proxies for paleoclimate Sabine Lengger University of Plymouth, UK BETR workshop September ... What Fossil Molecules Reveal](https://reader030.fdocuments.net/reader030/viewer/2022040610/5ecebb2145693554a363aea9/html5/thumbnails/26.jpg)
Recommended Reading
Briggs, D.E.G., Summons, R.E., 2014. Ancient biomolecules: Their origins, fossilization, and role in revealing the history of life: Prospects & Overviews. BioEssays 36, 482–490. https://doi.org/10.1002/bies.201400010
Eglinton, T.I., Eglinton, G., 2008. Molecular proxies for paleoclimatology. Earth and Planetary Science Letters 275, 1–16. https://doi.org/10.1016/j.epsl.2008.07.012
![Page 27: Organic proxies for paleoclimate · 2019-10-29 · Organic proxies for paleoclimate Sabine Lengger University of Plymouth, UK BETR workshop September ... What Fossil Molecules Reveal](https://reader030.fdocuments.net/reader030/viewer/2022040610/5ecebb2145693554a363aea9/html5/thumbnails/27.jpg)
Alkenonesor the serendipitous discovery of a temperature proxy
![Page 28: Organic proxies for paleoclimate · 2019-10-29 · Organic proxies for paleoclimate Sabine Lengger University of Plymouth, UK BETR workshop September ... What Fossil Molecules Reveal](https://reader030.fdocuments.net/reader030/viewer/2022040610/5ecebb2145693554a363aea9/html5/thumbnails/28.jpg)
Discovery of alkenones
• Boon et al. (1978): first ID in sediments, DSDP core from Walvis Ridge, SW Africa – field desorption MS of TLE and TLC fractions
• Identified as ketones with elemental composition of C37H70O(m/z 530) and ~C38H72O (m/z 544)
• De Leeuw et al. (1980): Confirmation of structure as C37-C39 methyl and ethyl ketones in sediments
![Page 29: Organic proxies for paleoclimate · 2019-10-29 · Organic proxies for paleoclimate Sabine Lengger University of Plymouth, UK BETR workshop September ... What Fossil Molecules Reveal](https://reader030.fdocuments.net/reader030/viewer/2022040610/5ecebb2145693554a363aea9/html5/thumbnails/29.jpg)
Discovery of producing organisms
Brassell, Eglinton, Marlowe, Pflaumann, Sarnthein (1986)De Leeuw et al. (1980), Volkman et al. (1980)
Volkman et al. (1980)Identification of same compounds in Emiliania huxleyiMarlowe et al. (1984) Common to Prymnesiophyceae, Degree of unsaturation related to growth temperature. Proposed as markers for E. hux
![Page 30: Organic proxies for paleoclimate · 2019-10-29 · Organic proxies for paleoclimate Sabine Lengger University of Plymouth, UK BETR workshop September ... What Fossil Molecules Reveal](https://reader030.fdocuments.net/reader030/viewer/2022040610/5ecebb2145693554a363aea9/html5/thumbnails/30.jpg)
Emiliania huxleyi
• Class: Haptophyta (Prymnesiophyta)• Order: Isochrysidales• Family: Gephyrocapsaceae• First appearance during Late Pleistocene (ca. 250 ka)• Cosmopolitan, eurythermal, most widespread
coccolithophores• Dominant source of alkenones in open ocean• Isochrysis and Chrysotila limited to coastal environments
• Morphotypes: warm and cold water form
![Page 31: Organic proxies for paleoclimate · 2019-10-29 · Organic proxies for paleoclimate Sabine Lengger University of Plymouth, UK BETR workshop September ... What Fossil Molecules Reveal](https://reader030.fdocuments.net/reader030/viewer/2022040610/5ecebb2145693554a363aea9/html5/thumbnails/31.jpg)
Types of lipids in coccolithophores
http://www.whoi.edu/cms/files/MOG11_molecular_proxies_81764.pdf
![Page 32: Organic proxies for paleoclimate · 2019-10-29 · Organic proxies for paleoclimate Sabine Lengger University of Plymouth, UK BETR workshop September ... What Fossil Molecules Reveal](https://reader030.fdocuments.net/reader030/viewer/2022040610/5ecebb2145693554a363aea9/html5/thumbnails/32.jpg)
The discovery of organic temperature proxies – UK37
Brassell, Eglinton, Marlowe, Pflaumann, Sarnthein (1986)De Leeuw et al. (1980), Volkman et al. (1980)Brassell et al. (1986) Æ Molecular stratigraphy
Relationship in degree of unsaturation and δ18O observed,
Proposed as a molecular marker for sea surface temperature Æ
Correlation between latitude, SST, and UK
37 in quarternary sediments
![Page 33: Organic proxies for paleoclimate · 2019-10-29 · Organic proxies for paleoclimate Sabine Lengger University of Plymouth, UK BETR workshop September ... What Fossil Molecules Reveal](https://reader030.fdocuments.net/reader030/viewer/2022040610/5ecebb2145693554a363aea9/html5/thumbnails/33.jpg)
Gas chromatogram of TLE of Kane Gap sediments
http://www.whoi.edu/cms/files/MOG11_molecular_proxies_81764.pdf
![Page 34: Organic proxies for paleoclimate · 2019-10-29 · Organic proxies for paleoclimate Sabine Lengger University of Plymouth, UK BETR workshop September ... What Fossil Molecules Reveal](https://reader030.fdocuments.net/reader030/viewer/2022040610/5ecebb2145693554a363aea9/html5/thumbnails/34.jpg)
Why is unsaturation related to temperature?
Image: Brock Microbiology
O
O
CH3
O CH3
O
OH
O
O
CH3
O CH3
O
OH
A certain, stable consistency is necessary for membranes
Cells needs to adjust their lipids and use more “oil” when it is cold and more “pork fat” when it is warm
![Page 35: Organic proxies for paleoclimate · 2019-10-29 · Organic proxies for paleoclimate Sabine Lengger University of Plymouth, UK BETR workshop September ... What Fossil Molecules Reveal](https://reader030.fdocuments.net/reader030/viewer/2022040610/5ecebb2145693554a363aea9/html5/thumbnails/35.jpg)
Alkenone unsaturation index• Initial ratio
::
: : :
(Brassell et al., 1986)• Modified ratio
:
: :
(Prahl and Wakeham, 1987)• Calibration
(Prahl and Wakeham, 1987)
(Müller et al., 1998)
• Calibration Error: ± 1 °C in open ocean, temperate and sub-polar waters
![Page 36: Organic proxies for paleoclimate · 2019-10-29 · Organic proxies for paleoclimate Sabine Lengger University of Plymouth, UK BETR workshop September ... What Fossil Molecules Reveal](https://reader030.fdocuments.net/reader030/viewer/2022040610/5ecebb2145693554a363aea9/html5/thumbnails/36.jpg)
Global calibration (surface sediment)
Conte et al., 2006
![Page 37: Organic proxies for paleoclimate · 2019-10-29 · Organic proxies for paleoclimate Sabine Lengger University of Plymouth, UK BETR workshop September ... What Fossil Molecules Reveal](https://reader030.fdocuments.net/reader030/viewer/2022040610/5ecebb2145693554a363aea9/html5/thumbnails/37.jpg)
Other calibration studies
Prahl et al., 1988 Zink et al., 2001
Cultures LakesCranwell et al. (1985): freshwater lake sediments
![Page 38: Organic proxies for paleoclimate · 2019-10-29 · Organic proxies for paleoclimate Sabine Lengger University of Plymouth, UK BETR workshop September ... What Fossil Molecules Reveal](https://reader030.fdocuments.net/reader030/viewer/2022040610/5ecebb2145693554a363aea9/html5/thumbnails/38.jpg)
Application
Ruan et al. (2015)
Sea surface temperature record – Southern Okinawa Trough
B/A warm periods and YD and OD cold periods clearly present
![Page 39: Organic proxies for paleoclimate · 2019-10-29 · Organic proxies for paleoclimate Sabine Lengger University of Plymouth, UK BETR workshop September ... What Fossil Molecules Reveal](https://reader030.fdocuments.net/reader030/viewer/2022040610/5ecebb2145693554a363aea9/html5/thumbnails/39.jpg)
Bayspline
Tierney and Tingley (2018)
![Page 40: Organic proxies for paleoclimate · 2019-10-29 · Organic proxies for paleoclimate Sabine Lengger University of Plymouth, UK BETR workshop September ... What Fossil Molecules Reveal](https://reader030.fdocuments.net/reader030/viewer/2022040610/5ecebb2145693554a363aea9/html5/thumbnails/40.jpg)
Haptophyte evolution
• Alkenones: 100 Myr first occurrence, 56 Ma first application
• E. hux only 250 ka old • Farrimond et al. (1986): Alkenones reported in
Cretaceous black shales• Marlowe et al. (1990): Micropalaeontological and
molecular data suggests genera belonging to family Gephyrocapsaceae were all potential sources of alkenones in sediments deposited since Eocene (45 Ma) • Cretaceous: ancestors of these organisms
![Page 41: Organic proxies for paleoclimate · 2019-10-29 · Organic proxies for paleoclimate Sabine Lengger University of Plymouth, UK BETR workshop September ... What Fossil Molecules Reveal](https://reader030.fdocuments.net/reader030/viewer/2022040610/5ecebb2145693554a363aea9/html5/thumbnails/41.jpg)
Limitations and open questions
• Species assemblages (e.g. coastal vs. open ocean)• Evolution of haptophytes • Preferential degradation (e.g. Sales de Freitas et al., 2017)• Spatial and temporal productivity patterns (e.g. Haug et al. 2005) • Lateral advection
Not always present/working Æ Other SST proxies
![Page 42: Organic proxies for paleoclimate · 2019-10-29 · Organic proxies for paleoclimate Sabine Lengger University of Plymouth, UK BETR workshop September ... What Fossil Molecules Reveal](https://reader030.fdocuments.net/reader030/viewer/2022040610/5ecebb2145693554a363aea9/html5/thumbnails/42.jpg)
Productivity patterns
Haug et al. (2005)
Cooling is observed, but UK
37’ shows warming
Changes in season of production of alkenones Æ shows the summer temperature
![Page 43: Organic proxies for paleoclimate · 2019-10-29 · Organic proxies for paleoclimate Sabine Lengger University of Plymouth, UK BETR workshop September ... What Fossil Molecules Reveal](https://reader030.fdocuments.net/reader030/viewer/2022040610/5ecebb2145693554a363aea9/html5/thumbnails/43.jpg)
3. TEX86
![Page 44: Organic proxies for paleoclimate · 2019-10-29 · Organic proxies for paleoclimate Sabine Lengger University of Plymouth, UK BETR workshop September ... What Fossil Molecules Reveal](https://reader030.fdocuments.net/reader030/viewer/2022040610/5ecebb2145693554a363aea9/html5/thumbnails/44.jpg)
ARCHAEA
Archaea
Bacteria
Archaea Slime mouldsPlants
Fungi
Animals
![Page 45: Organic proxies for paleoclimate · 2019-10-29 · Organic proxies for paleoclimate Sabine Lengger University of Plymouth, UK BETR workshop September ... What Fossil Molecules Reveal](https://reader030.fdocuments.net/reader030/viewer/2022040610/5ecebb2145693554a363aea9/html5/thumbnails/45.jpg)
Membranes of Archaea
Brock (2000) Biology of Microorganisms, 9th edition
Diether(Archaeol)
Tetraether (GDGT)
Archaea have diether and tetraether membrane lipids
Tetraether lipids are membrane-spanning.
Image: Brock Microbiology
![Page 46: Organic proxies for paleoclimate · 2019-10-29 · Organic proxies for paleoclimate Sabine Lengger University of Plymouth, UK BETR workshop September ... What Fossil Molecules Reveal](https://reader030.fdocuments.net/reader030/viewer/2022040610/5ecebb2145693554a363aea9/html5/thumbnails/46.jpg)
What is a GDGT?
Glycerol phytanylbidi glycerol tetraether
G D G T
Isoprenoid
![Page 47: Organic proxies for paleoclimate · 2019-10-29 · Organic proxies for paleoclimate Sabine Lengger University of Plymouth, UK BETR workshop September ... What Fossil Molecules Reveal](https://reader030.fdocuments.net/reader030/viewer/2022040610/5ecebb2145693554a363aea9/html5/thumbnails/47.jpg)
Distributions of archaeal lipids
Schouten et al. (2002) Earth Planet Sci Lett 204, 265-274
Surface sediment, Antarctica
Surface sediment, Arabian Sea
Schouten et al. (2002)
![Page 48: Organic proxies for paleoclimate · 2019-10-29 · Organic proxies for paleoclimate Sabine Lengger University of Plymouth, UK BETR workshop September ... What Fossil Molecules Reveal](https://reader030.fdocuments.net/reader030/viewer/2022040610/5ecebb2145693554a363aea9/html5/thumbnails/48.jpg)
Schouten et al. (2002)
Calibration based on core tops
Schouten et al. (2002)
![Page 49: Organic proxies for paleoclimate · 2019-10-29 · Organic proxies for paleoclimate Sabine Lengger University of Plymouth, UK BETR workshop September ... What Fossil Molecules Reveal](https://reader030.fdocuments.net/reader030/viewer/2022040610/5ecebb2145693554a363aea9/html5/thumbnails/49.jpg)
Calibration“Mesocosm” (Wuchter et al. 2004)
Core-top studies
Tierney (2012)
Tierney and Tingley (2015)Bayesian
![Page 50: Organic proxies for paleoclimate · 2019-10-29 · Organic proxies for paleoclimate Sabine Lengger University of Plymouth, UK BETR workshop September ... What Fossil Molecules Reveal](https://reader030.fdocuments.net/reader030/viewer/2022040610/5ecebb2145693554a363aea9/html5/thumbnails/50.jpg)
Bayesian Calibration
The Bayesian calibration for TEX86 allows the use of probability estimates
Can be used for surface and upper subsurface (upwelling)
Tierney and Tingley (2015)
![Page 51: Organic proxies for paleoclimate · 2019-10-29 · Organic proxies for paleoclimate Sabine Lengger University of Plymouth, UK BETR workshop September ... What Fossil Molecules Reveal](https://reader030.fdocuments.net/reader030/viewer/2022040610/5ecebb2145693554a363aea9/html5/thumbnails/51.jpg)
Application
• Deep time Æ stable molecules
• Earliest application: Sinemurian (Early Jurassic) – 193 Myr
(Robinson et al., 2017)
![Page 52: Organic proxies for paleoclimate · 2019-10-29 · Organic proxies for paleoclimate Sabine Lengger University of Plymouth, UK BETR workshop September ... What Fossil Molecules Reveal](https://reader030.fdocuments.net/reader030/viewer/2022040610/5ecebb2145693554a363aea9/html5/thumbnails/52.jpg)
Arctic Ocean temperatures during the Paleocene-Eocene thermal maximum
Sluijs et al. (2006)
![Page 53: Organic proxies for paleoclimate · 2019-10-29 · Organic proxies for paleoclimate Sabine Lengger University of Plymouth, UK BETR workshop September ... What Fossil Molecules Reveal](https://reader030.fdocuments.net/reader030/viewer/2022040610/5ecebb2145693554a363aea9/html5/thumbnails/53.jpg)
Many Archaea produce GDGTs
Schouten et al. (2013)
And many have not been cultured yet – so we don’t know if they make GDGTs.
![Page 54: Organic proxies for paleoclimate · 2019-10-29 · Organic proxies for paleoclimate Sabine Lengger University of Plymouth, UK BETR workshop September ... What Fossil Molecules Reveal](https://reader030.fdocuments.net/reader030/viewer/2022040610/5ecebb2145693554a363aea9/html5/thumbnails/54.jpg)
TEX86 exported from below the photic zone
Karner et al. (2006)
Subsurface temperature is correlated with surface temperature.
![Page 55: Organic proxies for paleoclimate · 2019-10-29 · Organic proxies for paleoclimate Sabine Lengger University of Plymouth, UK BETR workshop September ... What Fossil Molecules Reveal](https://reader030.fdocuments.net/reader030/viewer/2022040610/5ecebb2145693554a363aea9/html5/thumbnails/55.jpg)
Bias: Export from below photic zone
Tierney et al. (2014)
Data from: Castañeda et al. (2010), Huguet et al. (2006)
In the Eastern Mediterranean, the TEX86 has recorded surface temperature correctly. In the Arabian Sea, subsurface Æ increase in TEX86 when enhance upwelling during cold periods.
![Page 56: Organic proxies for paleoclimate · 2019-10-29 · Organic proxies for paleoclimate Sabine Lengger University of Plymouth, UK BETR workshop September ... What Fossil Molecules Reveal](https://reader030.fdocuments.net/reader030/viewer/2022040610/5ecebb2145693554a363aea9/html5/thumbnails/56.jpg)
Oxygen exposure time
Bias: Deep water export (Arabian Sea)
“Warm” subsurface signal in the Arabian Sea is only preserved under low oxygen conditions
Schouten et al. (2012) Lengger et al. (2014)
![Page 57: Organic proxies for paleoclimate · 2019-10-29 · Organic proxies for paleoclimate Sabine Lengger University of Plymouth, UK BETR workshop September ... What Fossil Molecules Reveal](https://reader030.fdocuments.net/reader030/viewer/2022040610/5ecebb2145693554a363aea9/html5/thumbnails/57.jpg)
Compounds produced in terrestrial environments vs marine environments
BIT index describes the amount of terrigenous vs marine material
Bias: Terrestrial – BIT index
Hopmans et al. (2004)
![Page 58: Organic proxies for paleoclimate · 2019-10-29 · Organic proxies for paleoclimate Sabine Lengger University of Plymouth, UK BETR workshop September ... What Fossil Molecules Reveal](https://reader030.fdocuments.net/reader030/viewer/2022040610/5ecebb2145693554a363aea9/html5/thumbnails/58.jpg)
BIT index
Always needs to be measured
High BIT index can cause too high TEX86temperatures
Weijers et al. (2006)
![Page 59: Organic proxies for paleoclimate · 2019-10-29 · Organic proxies for paleoclimate Sabine Lengger University of Plymouth, UK BETR workshop September ... What Fossil Molecules Reveal](https://reader030.fdocuments.net/reader030/viewer/2022040610/5ecebb2145693554a363aea9/html5/thumbnails/59.jpg)
Bias: Methane seeps – Methane index
In sediments characterised by diffusive methane flux, more GDGT-2 is produced
Methane index: GDGT-2/crenarchaeol
Weijers et al. (2011)
![Page 60: Organic proxies for paleoclimate · 2019-10-29 · Organic proxies for paleoclimate Sabine Lengger University of Plymouth, UK BETR workshop September ... What Fossil Molecules Reveal](https://reader030.fdocuments.net/reader030/viewer/2022040610/5ecebb2145693554a363aea9/html5/thumbnails/60.jpg)
Bias: Benthic production
Benthic production can occur, but does not affect the TEX86
But if SMTZ occurs in sediment, can have local influence
Lengger et al. (2012, 2014)
![Page 61: Organic proxies for paleoclimate · 2019-10-29 · Organic proxies for paleoclimate Sabine Lengger University of Plymouth, UK BETR workshop September ... What Fossil Molecules Reveal](https://reader030.fdocuments.net/reader030/viewer/2022040610/5ecebb2145693554a363aea9/html5/thumbnails/61.jpg)
Exercise TEX86
![Page 62: Organic proxies for paleoclimate · 2019-10-29 · Organic proxies for paleoclimate Sabine Lengger University of Plymouth, UK BETR workshop September ... What Fossil Molecules Reveal](https://reader030.fdocuments.net/reader030/viewer/2022040610/5ecebb2145693554a363aea9/html5/thumbnails/62.jpg)
Naafs et al. 2016Aquilina et al. 2010
![Page 63: Organic proxies for paleoclimate · 2019-10-29 · Organic proxies for paleoclimate Sabine Lengger University of Plymouth, UK BETR workshop September ... What Fossil Molecules Reveal](https://reader030.fdocuments.net/reader030/viewer/2022040610/5ecebb2145693554a363aea9/html5/thumbnails/63.jpg)
4. MBT/CBT – An organic proxy for temperatures in the terrestrial realm
![Page 64: Organic proxies for paleoclimate · 2019-10-29 · Organic proxies for paleoclimate Sabine Lengger University of Plymouth, UK BETR workshop September ... What Fossil Molecules Reveal](https://reader030.fdocuments.net/reader030/viewer/2022040610/5ecebb2145693554a363aea9/html5/thumbnails/64.jpg)
Branched GDGTs are bacterial membrane-spanning tetraether lipids
![Page 65: Organic proxies for paleoclimate · 2019-10-29 · Organic proxies for paleoclimate Sabine Lengger University of Plymouth, UK BETR workshop September ... What Fossil Molecules Reveal](https://reader030.fdocuments.net/reader030/viewer/2022040610/5ecebb2145693554a363aea9/html5/thumbnails/65.jpg)
Branched GDGTs are bacterial membrane-spanning tetraether lipids
Glycerol alkyldi glycerol tetraether
G D G T
branched
br
![Page 66: Organic proxies for paleoclimate · 2019-10-29 · Organic proxies for paleoclimate Sabine Lengger University of Plymouth, UK BETR workshop September ... What Fossil Molecules Reveal](https://reader030.fdocuments.net/reader030/viewer/2022040610/5ecebb2145693554a363aea9/html5/thumbnails/66.jpg)
brGDGTs are diverse and abundant in terrestrial environments
• First discovered in peat and coastal sediments
• Sinninghe Damsté et al. (2000)
• From anaerobic bacteria• Weijers et al. (2006)
• Temperature dependence discovered in soils
• Weijers et al. (2007)
• Source organisms Acidobacteria• Latest: Sinninghe Damsté et al.
(2018)
Can have 1, 2 extra methylations (Æ II, III)Can have 1, 2 cyclopentyl rings (Æ b, c)
![Page 67: Organic proxies for paleoclimate · 2019-10-29 · Organic proxies for paleoclimate Sabine Lengger University of Plymouth, UK BETR workshop September ... What Fossil Molecules Reveal](https://reader030.fdocuments.net/reader030/viewer/2022040610/5ecebb2145693554a363aea9/html5/thumbnails/67.jpg)
Distribution correlates with temperature
https://www.geo.arizona.edu/~jesst/resources/TierneyPSP_GDGTs.pdf
![Page 68: Organic proxies for paleoclimate · 2019-10-29 · Organic proxies for paleoclimate Sabine Lengger University of Plymouth, UK BETR workshop September ... What Fossil Molecules Reveal](https://reader030.fdocuments.net/reader030/viewer/2022040610/5ecebb2145693554a363aea9/html5/thumbnails/68.jpg)
New and improved calibration for soils
De Jonge et al. (2014)
![Page 69: Organic proxies for paleoclimate · 2019-10-29 · Organic proxies for paleoclimate Sabine Lengger University of Plymouth, UK BETR workshop September ... What Fossil Molecules Reveal](https://reader030.fdocuments.net/reader030/viewer/2022040610/5ecebb2145693554a363aea9/html5/thumbnails/69.jpg)
Peat calibration
Naafs et al. (2017)
![Page 70: Organic proxies for paleoclimate · 2019-10-29 · Organic proxies for paleoclimate Sabine Lengger University of Plymouth, UK BETR workshop September ... What Fossil Molecules Reveal](https://reader030.fdocuments.net/reader030/viewer/2022040610/5ecebb2145693554a363aea9/html5/thumbnails/70.jpg)
Other factors
![Page 71: Organic proxies for paleoclimate · 2019-10-29 · Organic proxies for paleoclimate Sabine Lengger University of Plymouth, UK BETR workshop September ... What Fossil Molecules Reveal](https://reader030.fdocuments.net/reader030/viewer/2022040610/5ecebb2145693554a363aea9/html5/thumbnails/71.jpg)
Applications: Loess soil depositsPeterse et al. (2011)
Mangshan loess plateau
MAT varies in phase with NH summer insolation Æonset of
deglacial warming
![Page 72: Organic proxies for paleoclimate · 2019-10-29 · Organic proxies for paleoclimate Sabine Lengger University of Plymouth, UK BETR workshop September ... What Fossil Molecules Reveal](https://reader030.fdocuments.net/reader030/viewer/2022040610/5ecebb2145693554a363aea9/html5/thumbnails/72.jpg)
Applications: Eocene peat
Inglis et al. 2017
![Page 73: Organic proxies for paleoclimate · 2019-10-29 · Organic proxies for paleoclimate Sabine Lengger University of Plymouth, UK BETR workshop September ... What Fossil Molecules Reveal](https://reader030.fdocuments.net/reader030/viewer/2022040610/5ecebb2145693554a363aea9/html5/thumbnails/73.jpg)
Very high temperatures?
Mean annual air temperature by brGDGTs might not be high enough
Maximum: 29 °C
Eocene: higher in the tropics?
Naafs et al. (2018)
![Page 74: Organic proxies for paleoclimate · 2019-10-29 · Organic proxies for paleoclimate Sabine Lengger University of Plymouth, UK BETR workshop September ... What Fossil Molecules Reveal](https://reader030.fdocuments.net/reader030/viewer/2022040610/5ecebb2145693554a363aea9/html5/thumbnails/74.jpg)
Practical MBT
![Page 75: Organic proxies for paleoclimate · 2019-10-29 · Organic proxies for paleoclimate Sabine Lengger University of Plymouth, UK BETR workshop September ... What Fossil Molecules Reveal](https://reader030.fdocuments.net/reader030/viewer/2022040610/5ecebb2145693554a363aea9/html5/thumbnails/75.jpg)
Dang et al. 2014
Naafs et al. 2017
![Page 76: Organic proxies for paleoclimate · 2019-10-29 · Organic proxies for paleoclimate Sabine Lengger University of Plymouth, UK BETR workshop September ... What Fossil Molecules Reveal](https://reader030.fdocuments.net/reader030/viewer/2022040610/5ecebb2145693554a363aea9/html5/thumbnails/76.jpg)
5. n-alkanes
![Page 77: Organic proxies for paleoclimate · 2019-10-29 · Organic proxies for paleoclimate Sabine Lengger University of Plymouth, UK BETR workshop September ... What Fossil Molecules Reveal](https://reader030.fdocuments.net/reader030/viewer/2022040610/5ecebb2145693554a363aea9/html5/thumbnails/77.jpg)
https://www.flickr.com/photos/jritch/4703253208/
![Page 78: Organic proxies for paleoclimate · 2019-10-29 · Organic proxies for paleoclimate Sabine Lengger University of Plymouth, UK BETR workshop September ... What Fossil Molecules Reveal](https://reader030.fdocuments.net/reader030/viewer/2022040610/5ecebb2145693554a363aea9/html5/thumbnails/78.jpg)
St. John’s Wort, Hypericumhttp://aobblog.com/2010/09/nanotechnology-and-self-cleaning-from-plant-leaf-surfaces/
![Page 79: Organic proxies for paleoclimate · 2019-10-29 · Organic proxies for paleoclimate Sabine Lengger University of Plymouth, UK BETR workshop September ... What Fossil Molecules Reveal](https://reader030.fdocuments.net/reader030/viewer/2022040610/5ecebb2145693554a363aea9/html5/thumbnails/79.jpg)
n-alkanes
Eglinton et al. (1962)
C31 n-alkane
C33 n-alkane
C29 n-alkane
![Page 80: Organic proxies for paleoclimate · 2019-10-29 · Organic proxies for paleoclimate Sabine Lengger University of Plymouth, UK BETR workshop September ... What Fossil Molecules Reveal](https://reader030.fdocuments.net/reader030/viewer/2022040610/5ecebb2145693554a363aea9/html5/thumbnails/80.jpg)
Plant waxes are found in many environments
http://www.whoi.edu/cms/files/MOG11_molecular_proxies_81764.pdf
![Page 81: Organic proxies for paleoclimate · 2019-10-29 · Organic proxies for paleoclimate Sabine Lengger University of Plymouth, UK BETR workshop September ... What Fossil Molecules Reveal](https://reader030.fdocuments.net/reader030/viewer/2022040610/5ecebb2145693554a363aea9/html5/thumbnails/81.jpg)
Leaf wax transport
Eglinton and Eglinton (2008)
![Page 82: Organic proxies for paleoclimate · 2019-10-29 · Organic proxies for paleoclimate Sabine Lengger University of Plymouth, UK BETR workshop September ... What Fossil Molecules Reveal](https://reader030.fdocuments.net/reader030/viewer/2022040610/5ecebb2145693554a363aea9/html5/thumbnails/82.jpg)
Terrestrial plants have longer chains
Song et al. (2015)
Terrigenous / Aquatic ratio
![Page 83: Organic proxies for paleoclimate · 2019-10-29 · Organic proxies for paleoclimate Sabine Lengger University of Plymouth, UK BETR workshop September ... What Fossil Molecules Reveal](https://reader030.fdocuments.net/reader030/viewer/2022040610/5ecebb2145693554a363aea9/html5/thumbnails/83.jpg)
C3 vs C4 plants
C4 plants pre-concentrate CO2 and can survive in drier climates (corn, grasses)
Diefendorf et al. (2015)
![Page 84: Organic proxies for paleoclimate · 2019-10-29 · Organic proxies for paleoclimate Sabine Lengger University of Plymouth, UK BETR workshop September ... What Fossil Molecules Reveal](https://reader030.fdocuments.net/reader030/viewer/2022040610/5ecebb2145693554a363aea9/html5/thumbnails/84.jpg)
Average chain length (ACL)
http://www.whoi.edu/cms/files/MOG11_molecular_proxies_81764.pdf
ACL is specific for vegetation type
C3, C4
Gymnosperms/Angiosperms(Diefendorf et al. 2015)
Marine / Terrestrial
Æ Biomarker GuideÆ mixing models
![Page 85: Organic proxies for paleoclimate · 2019-10-29 · Organic proxies for paleoclimate Sabine Lengger University of Plymouth, UK BETR workshop September ... What Fossil Molecules Reveal](https://reader030.fdocuments.net/reader030/viewer/2022040610/5ecebb2145693554a363aea9/html5/thumbnails/85.jpg)
6. Isotopes
![Page 86: Organic proxies for paleoclimate · 2019-10-29 · Organic proxies for paleoclimate Sabine Lengger University of Plymouth, UK BETR workshop September ... What Fossil Molecules Reveal](https://reader030.fdocuments.net/reader030/viewer/2022040610/5ecebb2145693554a363aea9/html5/thumbnails/86.jpg)
Stable carbon isotopesWe define these values as compared to a standard material with defined value of “0” ÆVienna Pee Dee Belemnite (VPDB)
![Page 87: Organic proxies for paleoclimate · 2019-10-29 · Organic proxies for paleoclimate Sabine Lengger University of Plymouth, UK BETR workshop September ... What Fossil Molecules Reveal](https://reader030.fdocuments.net/reader030/viewer/2022040610/5ecebb2145693554a363aea9/html5/thumbnails/87.jpg)
Compound-specific isotopes
Modified from: Elementar Ltd. UK
![Page 88: Organic proxies for paleoclimate · 2019-10-29 · Organic proxies for paleoclimate Sabine Lengger University of Plymouth, UK BETR workshop September ... What Fossil Molecules Reveal](https://reader030.fdocuments.net/reader030/viewer/2022040610/5ecebb2145693554a363aea9/html5/thumbnails/88.jpg)
n-alkane standard: GC-IRMS
With GC-IRMS, we can determine isotopes of a single compound
![Page 89: Organic proxies for paleoclimate · 2019-10-29 · Organic proxies for paleoclimate Sabine Lengger University of Plymouth, UK BETR workshop September ... What Fossil Molecules Reveal](https://reader030.fdocuments.net/reader030/viewer/2022040610/5ecebb2145693554a363aea9/html5/thumbnails/89.jpg)
δ13C of n-alkanes as a proxy for OM source
Marine: more enriched, terrigenous: more depleted
Also: C3 and C4 vegetation and thus dry / wet climate
http://www.whoi.edu/cms/files/MOG11_molecular_proxies_81764.pdf
![Page 90: Organic proxies for paleoclimate · 2019-10-29 · Organic proxies for paleoclimate Sabine Lengger University of Plymouth, UK BETR workshop September ... What Fossil Molecules Reveal](https://reader030.fdocuments.net/reader030/viewer/2022040610/5ecebb2145693554a363aea9/html5/thumbnails/90.jpg)
δ13C values of n-alkanes% of C3/C4 vegetation traces dust input from African continent
Schefuβ et al. (2013)
![Page 91: Organic proxies for paleoclimate · 2019-10-29 · Organic proxies for paleoclimate Sabine Lengger University of Plymouth, UK BETR workshop September ... What Fossil Molecules Reveal](https://reader030.fdocuments.net/reader030/viewer/2022040610/5ecebb2145693554a363aea9/html5/thumbnails/91.jpg)
Problem: Source shiftShift in sources of organic matter can cause a shift in δ13C
http://www.whoi.edu/cms/files/MOG11_molecular_proxies_81764.pdf
![Page 92: Organic proxies for paleoclimate · 2019-10-29 · Organic proxies for paleoclimate Sabine Lengger University of Plymouth, UK BETR workshop September ... What Fossil Molecules Reveal](https://reader030.fdocuments.net/reader030/viewer/2022040610/5ecebb2145693554a363aea9/html5/thumbnails/92.jpg)
δ13C of alkenones as a pCO2 proxy
C37:2 alkenones can be used as a proxy for pCO2 – but many processes, such as a productivity, and nutrients, complicate this proxy system
M. Pagani (2014)
![Page 93: Organic proxies for paleoclimate · 2019-10-29 · Organic proxies for paleoclimate Sabine Lengger University of Plymouth, UK BETR workshop September ... What Fossil Molecules Reveal](https://reader030.fdocuments.net/reader030/viewer/2022040610/5ecebb2145693554a363aea9/html5/thumbnails/93.jpg)
Hydrogen isotopes: the hydrological cycleHydrogen isotopes (δ2H or δ D values) experience fractionation during evaporation and precipitation
http://www.animalmigration.org/stable_isotopes/kinetic_fractionation.jpg
![Page 94: Organic proxies for paleoclimate · 2019-10-29 · Organic proxies for paleoclimate Sabine Lengger University of Plymouth, UK BETR workshop September ... What Fossil Molecules Reveal](https://reader030.fdocuments.net/reader030/viewer/2022040610/5ecebb2145693554a363aea9/html5/thumbnails/94.jpg)
www.isomap.orgwww.waterisotopes.org
δ2H of water varies globally
![Page 95: Organic proxies for paleoclimate · 2019-10-29 · Organic proxies for paleoclimate Sabine Lengger University of Plymouth, UK BETR workshop September ... What Fossil Molecules Reveal](https://reader030.fdocuments.net/reader030/viewer/2022040610/5ecebb2145693554a363aea9/html5/thumbnails/95.jpg)
D/H ratio (δ2H or δD) of leaf wax n-alkanes is related to source water
Sachse et al. (2006)
![Page 96: Organic proxies for paleoclimate · 2019-10-29 · Organic proxies for paleoclimate Sabine Lengger University of Plymouth, UK BETR workshop September ... What Fossil Molecules Reveal](https://reader030.fdocuments.net/reader030/viewer/2022040610/5ecebb2145693554a363aea9/html5/thumbnails/96.jpg)
Sachse et al. (2012)Schefuss et al. (2005)
Application: African hydroclimatePlant-derived C29n-alkaneWetter towards the Holocene climatic optimum
![Page 97: Organic proxies for paleoclimate · 2019-10-29 · Organic proxies for paleoclimate Sabine Lengger University of Plymouth, UK BETR workshop September ... What Fossil Molecules Reveal](https://reader030.fdocuments.net/reader030/viewer/2022040610/5ecebb2145693554a363aea9/html5/thumbnails/97.jpg)
d2H values of etherlipids
Archaeol
Hydroxyarchaeol
GDGT-0
GDGT-1
GDGT-2
GDGT-3
![Page 98: Organic proxies for paleoclimate · 2019-10-29 · Organic proxies for paleoclimate Sabine Lengger University of Plymouth, UK BETR workshop September ... What Fossil Molecules Reveal](https://reader030.fdocuments.net/reader030/viewer/2022040610/5ecebb2145693554a363aea9/html5/thumbnails/98.jpg)
Questions & Discussion
Email: [email protected]://www.whoi.edu/cms/files/MOG11_molecular_proxies_81764.pdfhttp://www.bris.ac.uk/nerclsmsf/content/gccirmscourse.pdf https://ocw.mit.edu/courses/earth-atmospheric-and-planetary-sciences/12-158-molecular-biogeochemistry-fall-2011/lecture-notes/
Mod. From H. ElderfieldBy J. Tierney