HR: 10:35h
AN: B12B-02 INVITED     [Abstracts]
TI: Compound Specific Isotope Analysis of Individual Biochemicals: Insights into Biogeochemistry
AU: * Macko, S A
EM: sam8f@virginia.edu
AF: Department Of Environmental Sciences, University of Virginia, Charlottesville, VA 22901 United States
AB: Stable isotopic determinations made on bulk organic materials are the weighted averages of the compositions of hundreds to thousands of chemical compounds, each of which has its own isotopic abundance. The stable isotope analysis of individual molecular components holds great potential as a method of tracing the source, biochemistry, diagenesis or indigeneity of a material. Through the advancements of continuous flow technologies, compound specific isotope analysis (CSIA) is unique in allowing for the resolution of a material's history or for partitioning the sources of organic inputs to a product or sink. Inscribed in the isotopic signature are indicators of the source material and pathways used in the formation of the compound. Perspectives on the use of this powerful tool will be presented. Isotope compositions of carbon and nitrogen on individual amino acids or of the isotopic compositions carbon on individual fatty acids or carbohydrates, hold the potential for delineation of production by an organism in an environment. The modification of the original signature can be used to suggest the contribution of new production of that same compound by microbial action or alteration of another substrate. Additionally, the partitioning of the signatures of individual amino acids between the D- and L- steroeoisomers can be utilized to further resolve new production within a sedimentary environment from the original primary photosynthetic source of production. Though standard mass balance approaches we suggest that perhaps a third of the organic matter preserved in an environment can be attributed to modified or new production from microbial processes. The questions as to the origins of individual molecular components, whether existing as environmental problems, or in potentially pristine materials, or serving as a proxy for bigger questions on depositional history or climate, can now be addressed. The tool of CSIA now uniquely offers an incredibly powerful probe into the origin of compound, and its history, and perhaps its eventual fate.
DE: 4825 Geochemistry
DE: 4840 Microbiology
DE: 4235 Estuarine processes
SC: Biogeosciences [B]
MN: 2004 AGU Fall Meeting