Abstract: Surface sediment samples and Bellamya were taken from the Chaohu Lake. The concentration and space distribution of heavy metals (Cd, Cr, Cu and Pb) were studied by HNO₃-HF-HClO₄ digestion-ICP-AES (Inductively coupled plasma atomic emission spectrometry). The pollution levels of the four heavy metals were evaluated by the potential ecological risk index, single factor pollution index and root mean square composite index. Results suggest that the sediments in Chaohu Lake have been polluted to a certain extent by heavy metals (Cd, Cr, Cu and Pb), among which Cd poses the largest potential ecological risk, while Pb and Cr are the high risk elements for Bellamya. The distribution characteristics and correlation analysis of heavy metals showed that the heavy metal sources in the sediments of Chaohu Lake are of similarity; whereas the sources of heavy metals in Bellamya are different due to multiple environmental factors. In conclusion, treatments of heavy metals (Cd, Cr, Cu and Pb) should be emphasized and the application of biological monitoring mwasures to shellfish should be strengthened.

Key words: surface sediment, Bellamya, heavy metal, risk assessment, environmental governance of Chaohu Lake