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ChemicalOceanographyOrganic Materials II

Dr. David K. RyanDepartment of ChemistryUniversity of Massachusetts Lowell&Intercampus Graduate Schoolof Marine Sciences and Technology

http://sites.uml.edu/david-ryan/teaching/chem-6530

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Organic Materials inMarine Environment

What are they? POC Detritus

DOC Fecal Mat. Biological molecules (lipids,

proteins, carbohydrates, 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

Organic

Dissolved

Natural

Carbon

Matter

HumicMaterials

Substances

Humic AcidFulvic Acid

OCDOCNOC

OMNOMDOM

HM

HS

HAFA

Chromophoric or Colored DOM

CDOM

Humic Subset

Ryan &Zhu 2013

620

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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