HR: 1340h
AN: OS33B-0589    [Abstracts]
TI: Bioturbation in near-surface sediments from western Clarion-Clipperton zones: evidence from excess $^{210}$Pb measurement
AU: Yang, Q
AF: Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, P.O. Box 1131, Guangzhou, GZ 510640 China
AU: * Zhou, H
EM: zhouhy@gig.ac.cn
AF: Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, P.O. Box 1131, Guangzhou, GZ 510640 China
AB: In order to evaluate bioturbation in sediments from the western part of Clarion-Clipperton fracture zones, northeast tropical Pacific, excess $^{210}$Pb profiles in sediments cores collected with multiple corers during R/V DAYANGYIHAO Environmental Program Cruise in 1998 were measured by direct gamma assay using Ortec GWL series HPGe well detector. Based on a steady-state diffusion model of excess $^{210}$Pb profiles, it is calculated that bioturbation mixing depths and biodiffusion coefficients are 16 cm and 2.75cm$^{2}$/a in station ES9801 (145\deg 25'40"W, 8\deg 31'06"N, 5374 m in water depth), and 6 cm and 0.26 cm$^{2}$/a in station WS9805 (154\deg 04'31"W, 10\deg 03'48"N, 5140 m in water depth), respectively. The bioturbation mixing depth and mixing intensity becomes higher from west to east in the survey area. Besides, mean density of {\it polychaete} and total organic carbon (TOC) content are also higher in station ES9801 than that in station WS9805. It is proposed that bioturbation is directly controlled by species and abundance of benthic fauna as well as the organic matter content in the sediments.
DE: 4808 Chemical tracers
DE: 4825 Geochemistry
DE: 4200 OCEANOGRAPHY: GENERAL
SC: Ocean Sciences [OS]
MN: 2004 AGU Fall Meeting