Dual filtration effect of geochemical and biogeochemical processes in the Changjiang Estuary |
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Authors: | Tian Rucheng Chen Jiyu Zhou Juzhen |
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Institution: | (1) Institute of Estuarine and Coastal Research, East China Normal University, 200062 Shanghai |
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Abstract: | Dissolved nutrients (NO
3
−
, PO4
3−, SiO3
2−) and oxygen, chlorophyll- a, pH, and Eh were measured on board during a cruise in August 1988 in the Changjiang Estuary region.
Heavy metals, organic matter and carbonate contents were analyzed in laboratory. The results show that geochemical processes
in the Changjiang Estuary have dual filtration effect: on the one hand geochemical filtration effect, reflected by ferromanganese
oxide flocculation and sedimentation, occurs near the turbidity maximum, and leads to enrichment of heavy metals in suspended
matter and sediments; on the other hand biogeochemical filtration, reflected by nutrients consumption, organic matter and
carbonate sedimentation and enrichment of trace elements in suspended matter, occurs outside the plume water front. The biogeochemical
filtration affects the environmental conditions; the dissolved oxygen and pH increase, in surface water and decrease in bottom
water. The biogeochemical filtration effect outside the plume front is more important than the geochemical filtration effect
near the turbidity maximum. |
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Keywords: | |
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