HR: 0800h
AN: OS51C-1324    [Abstracts]
TI: Marine DOC Radiocarbon Methods and DOC/POC Exchange
AU: * Beaupre, S R
EM: beaupre@essgrad.ps.uci.edu
AF: Department of Earth System Science, University of California, Irvine, Irvine, CA 92697-3100 United States
AU: Hwang, J
EM: jshwang@essgrad.ps.uci.edu
AF: Department of Earth System Science, University of California, Irvine, Irvine, CA 92697-3100 United States
AU: Druffel, E R
EM: edruffel@uci.edu
AF: Department of Earth System Science, University of California, Irvine, Irvine, CA 92697-3100 United States
AB: Dissolved Organic Carbon (DOC), defined as the carbon contained in that fraction of organic matter which passes through a 0.2-1.0 micrometer filter, is the largest oceanic reservoir of organic carbon with approximately 600 Gt C. Sources and sinks of this carbon pool are not yet well constrained, with some suggestions that a portion exchanges with the Particulate Organic Carbon pool (POC), i.e. that fraction retained by filters. Progress in examining this proposed phenomenon necessitates accurate and precise methods for quantifying DOC concentrations and isotope ratios. A simple experiment was performed whereby deep seawater was inoculated with dried, ground plankton as a known source of POC, and incubated two weeks in darkness at ambient temperature (Jeomshik Hwang, "Radiocarbon in Organic Compound Classes of Particulate and Sedimentary Organic Matter in the Northeast Pacific Ocean", Ph.D. Thesis, University of California, Irvine, 2004). The final DOC concentrations and isotope ratios were measured via prototype UV oxidation/vacuum line collection systems. The method performs with a system blank of 15 micrograms carbon, achieves 100% yield for the oxidation of ca. 1 liter solutions of NBS oxalic acid I, and preserves the standard's isotopic signature. Analytical performance of the DOC systems and results of the addition experiment are presented.
DE: 4806 Carbon cycling
DE: 4850 Organic marine chemistry
DE: 4860 Radioactivity and radioisotopes
DE: 4894 Instruments and techniques
DE: 4800 OCEANOGRAPHY: BIOLOGICAL AND CHEMICAL
SC: Ocean Sciences [OS]
MN: 2004 AGU Fall Meeting