HR: 0830h
AN: PP51C-0934    [PDF]
TI: Differential sorting, delivery and preservation of organic matter along the Washington margin, USA
AU: * Keil, R
EM: rickkeil@u.washington.edu
AF: School of Oceanography University of Washington, Box 355351, Seattle, WA 98195-5351 United States
AU: Arnarson, T
EM: thor@ocean.washington.edu
AF: School of Oceanography University of Washington, Box 355351, Seattle, WA 98195-5351 United States
AB: The quantity of organic matter preserved along the Washington margin (USA) is correlated with mineral specific surface area and this organic matter is present in core top (upper 20 cm) sediments as aggregated organo-mineral complexes. Previous studies have illustrated that certain organic components delivered to the shelf (e.g. diploptene, angiosperm-derived lignins) are preferentially transported offshore while other organic matter is effectively preserved along the upper margin (e.g cutins). Using size and density fractionation techniques, we isolated organo-clay aggregates and investigated their organic matter form and content using a combination of synoptic (e.g. X-ray photoelectron spectroscopy) and compound-specific analyses (e.g. amino acid analyses). Every sediment sample, from sand-rich shelf sediments to low organic content deep slope sediments, contains a `highly degraded' component of organic matter. Sorting, transport and delivery of this `degraded' organic matter from the shelf to the deep slope can account for all the burial of organic matter deeper than 200 meters water depth. Molecular mass balances suggest that, at best, 50 percent of the shelf-derived organic matter is replaced with organic matter derived from the local vertical rain. These estimates strengthen the view that winnowing and transport of organic matter is an important process that delivers near-shore-derived organic molecules that can be used as paleoindicators to deep sediments.
DE: 1055 Organic geochemistry
DE: 3022 Marine sediments--processes and transport
DE: 4219 Continental shelf processes
DE: 4806 Carbon cycling
DE: 4850 Organic marine chemistry
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2003 Fall Meeting