Chemical Oceanography Organic Materials II Dr. David K. Ryan - - PowerPoint PPT Presentation

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Chemical Oceanography Organic Materials II Dr. David K. Ryan - - PowerPoint PPT Presentation

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Chemical Oceanography Organic Materials II Dr. David K. Ryan Department of Chemistry University of Massachusetts Lowell & Intercampus Graduate School of Marine Sciences and Technology http://faculty.uml.edu/david_ryan/84.653 1 Organic

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Chemical Oceanography

Organic Materials II

  • Dr. David K. Ryan

Department of Chemistry University of Massachusetts Lowell & Intercampus Graduate School

  • f 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? POC Why are they important?  Detritus Where 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?

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4 Emerson & Hedges 2010 Flame Ionization (FI), Fluorescence (Flu), Pulsed Amperometric (PA)

Mass Spectrometry (MS), UV absorption

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All Dissolved Organic Compounds

Organic Dissolved Natural Carbon Matter Humic Materials Substances Humic Acid Fulvic Acid

OC DOC NOC OM NOM DOM HM HS HA FA

Chromophoric

  • r Colored DOM

CDOM

Humic Subset Ryan & Zhu 2013

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6 20 Libes, 1992

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Humic Materials

Complex natural organic molecules Properties & importance understood Some structural components known Exact chemical nature or exact structure 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 Cycle Libes, 1992 Inventories in 1015 g C = BMT Fluxes (arrows) 1015 g C/yr

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Cauwet, 1978

Distribution of Organic Carbon (a) Major compartments in the global ocean (b) Major compartments for the planet

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Active Carbon Reservoirs (excluding Ocean DIC)

Soil IC 22%

  • Atm. CO2

13%

  • Terr. Plants

19% Ocean DOC 12%

  • Surf. Ocean

Seds. 3% Soil OC 32%

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Organic Compounds in Marine Environment

Where do they come from? What are they?

Hydrocarbons Carbohydrates (polysaccharides), sugars Lipids, fats, waxes, oils, fatty acids Pigments Nucleic acids, RNA, DNA Amino acids, polypeptides, proteins, enzymes Low molecular weight carboxylic acids Humic Substances Bio & Geo

Bio ?

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15 ers

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Organic Compounds in Marine Environment

Where do they come from? What are they?

Hydrocarbons Carbohydrates (polysaccharides), sugars Lipids, fats, waxes, oils, fatty acids Pigments Nucleic acids, RNA, DNA Amino acids, polypeptides, proteins, enzymes Low molecular weight carboxylic acids Humic Substances Bio & Geo

Bio ?

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Organic Carbon Inputs to the Ocean

Allochthonous = formed externally (ex situ) Autochthonous = formed internally (in situ) Most Marine Humic Material is formed in situ through both biotic & abiotic processes Some Humic Material (i.e., coastal) is introduced from terrestrial sources (formed

  • n land)
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Transformation of DOC

Biological molecules are labile = readily broken down

  • r degraded quickly

By-products of this breakdown (substances not completely remineralized) can react with other organic compounds in a process called Humification or Early Diagenesis This results in non-labile Humic Materials Humics 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 soils Humification is the first step, fast, aerobic Fossilization or carbonification occur more slowly on geologic time scales, anaerobicly, after burial in sediments Diagenesis, Catagenesis, Metagenesis

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21 Humification of Organic Matter (possible scheme)

Libes, 1992

Hydrocarbons, Fats, Waxes Oils, Sterols, Vitamins, etc.

Biotic Abiotic Macromoloecules

aggregation agglomeration

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22 Humification of Organic Matter (another scheme) Libes, 1992

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Emerson & Hedges Figure 8.2

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24 Morel & Hering, 1993 See also Emerson & Hedges Figure 8.11 & 8.12

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Humic Structure Proposed by Schnitzer (Rashid 1985)

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Structure Attributed to Gamble et al. (1985)

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Morel & Hering (1993) Based on Aiken et al. (1985)

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Possible Structural Units Set Forth by Averett, Leenheer, McKnight & Thorn (1989) From Morel & Hering, 1993

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Kleinhempel reprinted from Albrecht Thaer Archiv (1970)

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Organic Solute Macromolecule (ORSMAC) Leenheer 1985)

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31 Davies & Ghabbour, 1999

Carbon atoms-green Oxygen atoms-red Nitrogen-blue Hydrogen not shown Molecular model of the lowest energy conformation of humic acid building blocks

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Importance of Humic Materials

Global Carbon Reservoir Take Part in Interfacial Phenomena Undergo Coagulation and Aggregation Involved in Photochemical Reactions Contain Radicals Known Reducing Agents Methylate Metals Form Chlorinated Species, THMs DBPs Detoxify Metals Limit Bioavailability of Metals Alter Solubility Influence Bind Metals & Organic Pollutants Terminal 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 Complexation by Humic Materials

Leenheer et al. (1998) Morel (1983)

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References

Cauwet, G. (1978) Oceanologica Acta 1, 99 Davies & Ghabbour (1999) Chemistry & Industry 7, 426 Fox, L. (1983) Estuarine Coastal Shelf Sci. 16, 431 Hedges, J.I. (1992) Global Biogeochemical Cycles: Progress and Problems, Mar. Chem. 39, 67 Leenheer, 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, 2410 Rashid, M.A. (1985) Geochemistry of Marine Humic Compounds, Springer-Verlag, NY, NY, 300 pages

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Chemical Oceanography

Organics III

  • Dr. David K. Ryan

Department of Chemistry University of Massachusetts Lowell & Intercampus Graduate School

  • f Marine Sciences and Technology

http://faculty.uml.edu/David_Ryan/84.653

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Sea Foam caused by naturally

  • ccuring

surface active agents

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Air-Sea Interfacial Chemistry

Surface active compounds concentrated at interface

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42 Morel & Hering, 1993

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Importance of Humic Materials

Global Carbon Reservoir Take Part in Interfacial Phenomena Undergo Coagulation and Aggregation Involved in Photochemical Reactions Contain Radicals Known Reducing Agents Methylate Metals Form Chlorinated Species, THMs DBPs Detoxify Metals Limit Bioavailability of Metals Alter Solubility Influence Bind Metals & Organic Pollutants Terminal 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 radical present in humic material

Scott, McKnight, Blunt-Harris, Kolesar & Lovely (1998) Environ. Sci. Technol. 32, 19

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