1 Introduction
Determination of complexation capacity of trace metal-organic in natural water

-- The complexation capacity for heavy metals (Cu, Cd, Pb) were determined by anodic stripping voltammetry in South China Sea, Hulun Lake and Wuliang Suhai. The conditional stability constants and complexation capacity index were calculated. The data showed that the complexation capacity of the Hulun Lake was greater than that of seawater and Wuliang Suhai. The sequence of complexation capacity is C (CuL) > C (CdL) > C (PbL), the values are in concord with results of analysis on dissolved organic carbon. The conditional stability constants were in an opposite sequence K (CuL) < K(CdL) < K (PbL). When logK are similar, the greater the complexation capacity, the greater the complexation capacity index.