Heavy metal complexation capacity of the South China Sea water

The seawater complexation capacity for heavy metals (copper, lead and cadmium) in the South China Sea was determined by anodic voltammetry and the conditional stability constants of these complexes were calculated. The data showed that the complexation capacity of the South China Sea water was greater than that of seawater in the Huanghe Estuary and the coast water of Qingdao. The sequence of complexation capacity is C (CuL)>C(PbL)>C(CdL), and the conditional stability constants were in an opposite sequence: K(CuL)<K(PbL)<K(CdL). The types, and shapes of the complexation capacity profiles for Cu, Cd and Pb were similar to those obtained by Buckley (1986) for the Atlantic Ocean water. Complexation capacity is maximum at the surface layer, decreasing with depth, reaching minimum at 750m, but increasing again near the sea bottom. This project was supported by a grant from the State Educational Commission for subsidizing excellent young teachers and a grant from the National Science Foundation Commission of China. Guo Boshu is a visiting scholar from Inner Mongolia Normal University at Huho Haote. This paper is part of her work at Ocean University of Qingdao.