Post on 08-Jun-2020
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ChemicalOceanographyOrganic Materials II
Dr. David K. RyanDepartment of ChemistryUniversity of Massachusetts Lowell&Intercampus Graduate Schoolof Marine Sciences and Technology
http://faculty.uml.edu/david_ryan/84.653
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Organic Compounds in Marine Environment
Where do they come from?What are they? POCWhy are they important? DetritusWhere do they go? Fecal Mat.
DOC Biological molecules (lipids,
proteins, carbohydrates, etc., etc.) Hydrocarbons Humic Materials (=other stuff)
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Morel, 1983
What is this stuff?
4Emerson & Hedges 2010 Flame Ionization (FI), Fluorescence (Flu), Pulsed Amperometric (PA)Mass Spectrometry (MS), UV absorption
All Dissolved Organic Compounds
OrganicDissolved
Natural
Carbon
Matter
HumicMaterials
Substances
Humic AcidFulvic Acid
OCDOCNOC
OMNOMDOM
HM
HS
HAFA
Chromophoric or Colored DOM
CDOM
Humic Subset
Ryan &Zhu 2013
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Libes, 1992
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Humic Materials
Complex natural organic moleculesProperties & importance understoodSome structural components knownExact chemical nature or exactstructure unknown because: Complexity Deficiencies in analytical Heterogeneity techniques Concentrations Interfering species
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Organic Carbon Continuum
Libes,1992
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Millero,2007
um)
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Carbon CycleLibes, 1992
Inventories in1015 g C = BMT
Fluxes (arrows)1015 g C/yr
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Cauwet, 1978
Distribution ofOrganic Carbon
(a) Major compartmentsin the global ocean
(b) Major compartmentsfor the planet
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Active Carbon Reservoirs (excluding Ocean DIC)
Soil IC22%
Atm. CO213%
Terr. Plants19%
Ocean DOC12%
Surf. Ocean Seds.
3%
Soil OC32%
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Organic Compounds inMarine Environment
Where do they come from?What are they?
HydrocarbonsCarbohydrates (polysaccharides), sugarsLipids, fats, waxes, oils, fatty acidsPigmentsNucleic acids, RNA, DNAAmino acids, polypeptides, proteins, enzymesLow molecular weight carboxylic acidsHumic Substances
Bio & Geo
Bio
?
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ers
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Organic Compounds inMarine Environment
Where do they come from?What are they?
HydrocarbonsCarbohydrates (polysaccharides), sugarsLipids, fats, waxes, oils, fatty acidsPigmentsNucleic acids, RNA, DNAAmino acids, polypeptides, proteins, enzymesLow molecular weight carboxylic acidsHumic Substances
Bio & Geo
Bio
?
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Organic Carbon Inputsto the Ocean
Allochthonous = formed externally (ex situ)Autochthonous = formed internally (in situ)
Most Marine Humic Material is formed in situthrough both biotic & abiotic processes
Some Humic Material (i.e., coastal) is introduced from terrestrial sources (formed on land)
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Transformation of DOCBiological molecules are labile = readily broken downor degraded quicklyBy-products of this breakdown (substances not completely remineralized) can react with other organic compounds in a process called Humification or Early DiagenesisThis results in non-labile Humic MaterialsHumics may degrade slowly or be removed to the sediments (refractory or non-labile)
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Transformation of DOC
These processes occur in the water column, in sediments, & in soilsHumification is the first step, fast, aerobicFossilization or carbonification occur more slowly on geologic time scales, anaerobicly, after burial in sedimentsDiagenesis, Catagenesis, Metagenesis
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Humification ofOrganic Matter(possible scheme)
Libes, 1992
Hydrocarbons, Fats, WaxesOils, Sterols, Vitamins, etc.
Biotic
Abiotic
Macromoloecules
aggregationagglomeration
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Humification ofOrganic Matter(another scheme)
Libes, 1992
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Emerson & Hedges Figure 8.2
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Morel & Hering,1993See also Emerson & HedgesFigure 8.11 & 8.12
25Humic Structure Proposed by Schnitzer (Rashid 1985)
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Structure Attributed to Gamble et al. (1985)
27Morel & Hering (1993) Based on Aiken et al. (1985)
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Possible StructuralUnits Set Forth byAverett, Leenheer,McKnight & Thorn(1989) From Morel& Hering, 1993
29Kleinhempel reprinted from Albrecht Thaer Archiv (1970)
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Organic Solute Macromolecule (ORSMAC) Leenheer 1985)
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Davies & Ghabbour, 1999
Carbon atoms-greenOxygen atoms-redNitrogen-blueHydrogen not shown
Molecular model of the lowestenergy conformation ofhumic acid building blocks
Importance of Humic Materials
Global Carbon ReservoirTake Part in Interfacial PhenomenaUndergo Coagulation and AggregationInvolved in Photochemical ReactionsContain RadicalsKnown Reducing AgentsMethylate MetalsForm Chlorinated Species, THMs DBPsDetoxify MetalsLimit Bioavailability of MetalsAlter SolubilityInfluenceBind Metals & Organic PollutantsTerminal Electron Transport Acceptor for Bacteria
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Fox, 1983
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CDOM = Chomophoric (Colored) Organic Matter
Photochemistry
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Metal Complexationby Humic Materials
Leenheer et al. (1998)Morel (1983)
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References
Cauwet, G. (1978) Oceanologica Acta 1, 99Davies & Ghabbour (1999) Chemistry & Industry 7, 426Fox, L. (1983) Estuarine Coastal Shelf Sci. 16, 431Hedges, J.I. (1992) Global Biogeochemical Cycles: Progress
and Problems, Mar. Chem. 39, 67Leenheer, J.A. (1985) in Humic Substances in Soil Sediment
and Water: Geochemistry, Isolation and Characterization, Wiley, NY, pp. 409-429
Lenheer, J.A. et al. (1998) Environ. Sci. Technol. 32, 2410Rashid, M.A. (1985) Geochemistry of Marine Humic
Compounds, Springer-Verlag, NY, NY, 300 pages
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ChemicalOceanographyOrganics III
Dr. David K. RyanDepartment of ChemistryUniversity of Massachusetts Lowell&Intercampus Graduate Schoolof Marine Sciences and Technology
http://faculty.uml.edu/David_Ryan/84.653
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Sea Foam caused by naturally occuring surface active agents
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Air-Sea Interfacial Chemistry
Surface active compoundsconcentrated at interface
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Morel & Hering,1993
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Importance of Humic MaterialsGlobal Carbon ReservoirTake Part in Interfacial PhenomenaUndergo Coagulation and AggregationInvolved in Photochemical ReactionsContain RadicalsKnown Reducing AgentsMethylate MetalsForm Chlorinated Species, THMs DBPsDetoxify MetalsLimit Bioavailability of MetalsAlter SolubilityInfluenceBind Metals & Organic PollutantsTerminal Electron Transport Acceptor for Bacteria
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Fox, 1983
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Millero, 1996
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CDOM = Chomophoric (or Colored) Dissolved Organic Matter
Photochemistry
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Quinone radicalpresent in humic material
Scott, McKnight, Blunt-Harris, Kolesar & Lovely (1998) Environ. Sci. Technol. 32, 19
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