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 (332KB)
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19,988,000 Yen (FY1998: 6,299,000 Yen)
Seawater samples were taken from two coastal stations in the East China Sea near the mouth of the Changjian River in May 1998. Filtered samples were analyzed for Cd, Co, Cu, Fe, Mn, Mo, Ni, Pb, V, Zn, As and Sb. The concentration ranged from 0.1 to 0.4nM, from 1 to 13 nM, from 9.1 to 17.3 nM, from 21 to 2631 nM, from 18 to 93 nM, from 3 to 8 nM, l.5 to 1 1,8 nM, from O to 0.5 nM, from 11 to 19 nM from 38 to 90 nM, from 22.0 to 25.9 nM and from I . 1 9 to 2.07 nM for the above 1 2 trace elements, respectively. With the exception of Zn and Pb, these concentration levels are similar to other coastal waters, implying no significant effect of the Changjian River could be detected at this sampling time. Surface seawater samples were also taken from mesocosms installed near the mouth of the Changjian River. Filtered samples were analyzed for the same 1 2 trace elements. The concentrations of Cd, Cu, Ni, and most prominently As decreased with time in the phosphate-enriched mesocosm. The most likely cause of trace element variations is biological processes including phytoplankton bloom. The speciation study suggests that phyioplankton can actively take up As (V) together with phosphate and concomitantly release As (III) . On the other hand, in the phosphate-enriched mesocosm, the concentrations of Mn and Sb increased with time. The concentrations of Mo, V, and Co showed no significant changes.
Trace Metals, Geochemical Cycling, Biological Activity, Coastal Ecosystem