Level and Fate of Heavy Metals in the Changjiang Estuary and Its Adjacent Waters

Dissolved concentrations of Cu, Pb, Zn, and Cd were measured in the Changjiang estuary and its adjacent waters. The results indicate that the ranges of dissolved heavy metals in the studied waters are as follows: Cu = 1.0 - 6.9 mu g/L, Pb = 0.10 - 0.39 mu g/L, Zn = 3.2 - 9.1 mu g/L, and Cd = 0.011 - 0.049 mu g/L. The behavior of the dissolved Cu was essentially conservative, but a high scatter was observed for the high salinity samples, and it is the same with Zn and Pb. The overall concentrations of dissolved Cd increase with the salinity. There were no differences between the surface, middle, and bottom layer for Cu, Pb, Zn, and Cd. Seasonal changes of their averages were not obvious on the whole. River discharges, sedimentary dynamics, and biological processes might determine the profiles of heavy metals.