Silicon isotope constraints on sources and utilization of silicate in the northern South China Sea.

Cao, Zhimian, Frank, Martin , Dai, Minhain, Grasse, Patricia and Ehlert, Claudia (2012) Silicon isotope constraints on sources and utilization of silicate in the northern South China Sea. [Poster] In: 2012 Ocean Sciences Meeting, OSM. , 20.02.-24.02.2012, Salt Lake City, Utah, USA . 2012 Ocean Sciences Meeting : abstract book ; February 20-24. 2012 ; Salt Palace Convention Center, Salt Lake City, Utah, USA. ; ID 10110 .

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Abstract ID: 10110
PosterID: B1276
We measured for the first time seawater δ30SiSi(OH)4 and δ30SiBSi to examine sources and utilization of Si(OH)4 in the northern South China Sea (NSCS). δ30SiBSi values were systematically lower than the correspondingδ30SiSi(OH)4 in the euphotic zone (< 100 m) on the shelf and slope. In contrast, δ30SiBSi were equal to δ30SiSi(OH)4 in the surface mixed layer (< 50 m) of the deep basin and δ30SiBSi in waters below were significantly higher than the corresponding δ30SiSi(OH)4. By comparing the field data with calculation according to Rayleigh or steady state models, we demonstrated surface waters on the inner shelf were largely fed by nutrients from the Pearl River input. While the primary Si(OH)4 source for the euphotic zone on the outer shelf and slope was upwelling or mixing from underlying waters, the Si(OH)4 in the surface mixed layer of the NSCS basin might originate from horizontal mixing with highly fractionated waters. As a consequence, the Si isotope dynamics in the NSCS are largely modulated by variable biological fractionation of Si derived from different mixing-induced initial conditions rather than any single source water.

Document Type: Conference or Workshop Item (Poster)
Keywords: Oceanography; Biogeochemistry; Silicon; South China Sea
Research affiliation: OceanRep > GEOMAR > FB1 Ocean Circulation and Climate Dynamics > FB1-P-OZ Paleo-Oceanography
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Date Deposited: 12 Apr 2012 12:15
Last Modified: 29 Nov 2012 14:14

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