Speciation study of chromium, copper and nickel in coastal estuarine sediments polluted by domestic and industrial effluents

Speciation of Cr, Cu and Ni in coastal sediments of Hong Kong was studied by the sequential extraction scheme of Tessier et al. (1979). Surface sediment samples were retrieved from eleven sampling points located in Victoria and Tolo Harbours. Multivariate analysis of the speciation data revealed significant differences in the speciation patterns among metals, and between the two water bodies. Speciation data for labile Cr and Ni showed distinct spatial patterns, which can be attributed to the difference in sediment condition of the two water bodies and the similar solubility of their corresponding sulphide compounds. The speciation pattern for labile Cu, on the other hand, appeared to be influenced by the differences in pattern and degree of pollution. Multiple regression analysis of the speciation pattern of individual metals against four sediment parameters (Eh, TOC, Fetotal and TS) revealed that total sulphide content in sediment was the most important factor controlling the distribution of metal species among various geochemical phases.