Organic geochemistry of particulate matter in the ocean: The role of particles in oceanic sedimentary cycles

Abstract

Organic geochemists often use the occurrence of specific organic compounds in marine sediments as biomarkers to relate sedimentary organic matter to biological processes in the overlying water column. However, organic matter undergoes many diagenetic changes during transport through the water column. Only a small fraction of the organic matter produced in surface waters reaches the sea floor to be incorporated into the sediments. This material is subject to considerable transformation by heterotrophic organisms. The initial structures of individual compounds can be altered and the proportion of various compounds and compound classes can change as a result of varying stabilities. We summarize here the results of our studies of the organic geochemistry of suspended and sinking particles collected as part of the PARFLUX and VERTEX programs and present new results for amino acids, fatty acids, sterols and steroidal ketones from the VERTEX project site north of Hawaii.