HR: 0800h
AN: PP41B-0542    [Abstracts]
TI: Water-Column Redistribution of Biogenic Particles in the Central Equatorial Pacific: Evidence From the Spatial and Temporal Variations in Flux and Isotope Compositions of Planktonic Foraminifers in Sediment Traps
AU: * Luo, S
EM: sluo@mail.ncku.edu.tw
AF: National Cheng-Kung University, 1 University Road, Tainan, 701, Taiwan
AU: Wang, C
EM: sluo@mail.ncku.edu.tw
AF: National Cheng-Kung University, 1 University Road, Tainan, 701, Taiwan
AB: The flux of biogenic particles (e.g., carbonates, opal, and organic carbon) exported from the surface to deep oceans plays an important role in controlling the oceanic carbon cycling and the concentration of CO2 in the atmosphere. This flux is assessed by sediment-trap deployment in the modern ocean and by using proxies preserved in the sea-floor sediments for the past oceans. In this study, based on the sediment-trap deployment, we measured the spatial and temporal variations in the flux and isotopic compositions of the calcareous tests of planktonic foraminifers in the central equatorial Pacific. The results show that significant fluxes of the foraminiferal tests collected respectively at 5° south and north of the equator can not be attributed to the export from the overlying surface oceans. Rather, the isotope measurements indicate that these biogenic particles may have a common origin at the equator and are likely to be transported from there by horizontal currents. It seems that the high fluxes of biogenic particles preserved respectively 5° south and north in the sea-floor sediments can not be used to reflect the productivities in the overlying surface oceans. Such redistribution of biogenic particles in the water column is also subject to significant seasonal variations. The results bear implications on not only the quantification of modern-ocean carbon flux, but also the use of the flux and/or isotopic/chemical compositions of foraminifers in sediment cores as a paleoceanographic proxy.
DE: 4806 Carbon cycling (0428)
DE: 4808 Chemical tracers
DE: 4870 Stable isotopes (0454, 1041)
DE: 4875 Trace elements (0489)
DE: 4924 Geochemical tracers
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2007 Fall Meeting