HR: 1340h
AN: OS33A-0576    [Abstracts]
TI: Chemical Composition of Sinking Particulate Organic Matter in the Water Column and Sediments of the Cariaco Basin
AU: * Benitez-Nelson, B
AF: University of South Carolina, Department of Geological Sciences, Columbia, SC 29208 United States
AU: Goni, M A
EM: goni@geol.sc.edu
AF: University of South Carolina, Department of Geological Sciences, Columbia, SC 29208 United States
AU: Aceves, H
AF: University of South Carolina, Department of Geological Sciences, Columbia, SC 29208 United States
AU: Woodworth, M
AF: University of South Carolina, Department of Geological Sciences, Columbia, SC 29208 United States
AU: Thunell, R
AF: University of South Carolina, Department of Geological Sciences, Columbia, SC 29208 United States
AU: Tappa, E
AF: University of South Carolina, Department of Geological Sciences, Columbia, SC 29208 United States
AB: Sinking particles have been collected at bi-weekly intervals from three different water depths in the eastern region of the Cariaco Basin since late 1995 as part of the CARIACO time series study. A subset of samples collected from 1997 to 1999 have been analyzed by alkaline CuO oxidation to characterize the magnitude and composition of the organic matter exported from the euphotic zone over several upwelling-stratification cycles. As part of this study we quantified CuO reaction products from a variety of common biochemicals, including amino acids, lipids (fatty acids and dicarboxylic acids) and lignin. The compositions of the sinking particles in the Cariaco Basin were dominated by amino acid and lipid-derived products, which in past studies have been shown to be predominantly derived from marine organic matter sources such as phytoplankton and zooplankton. The seasonal fluxes of these products correlated well with both organic carbon and opal fluxes, further reinforcing the interpretation that marine organic matter is the major source of these compounds. In contrast, lignin-derived products, which are characteristic of terrigenous organic matter, showed seasonal fluxes that correlated best with lithogenic fluxes. We will investigate the attenuation in the export fluxes of all these compounds as they travel through the water column of the Cariaco Basin in order to provide insight into organic matter degradation processes. Additionally, we will compare the magnitude of the annually integrated water column export fluxes of these compounds to their accumulation fluxes in underlying sediments in order to assess the burial efficiency of different organic matter components. Finally, we will reconstruct the burial fluxes of these compounds over a 6,000 year time period by analyzing samples from sediment cores from the basin in order to provide a historical record of organic matter preservation at this location.
DE: 4805 Biogeochemical cycles (1615)
DE: 4806 Carbon cycling
DE: 4850 Organic marine chemistry
DE: 4267 Paleoceanography
DE: 4279 Upwelling and convergences
SC: Ocean Sciences [OS]
MN: 2004 AGU Fall Meeting