Abstract：Surface sediment samples were taken from Chaohu Basin, total and fractions of eight heavy metals (Cd, Cr, Cu, Zn, Ni and Pb) were studied. The pollution of heavy metals were evaluated by the potential ecological risk index (RI). Heavy metal distribution of surface sediment indicated the highest degree of contamination in Nanfei-Shiwuli River, followed by Yuxi river and its tributaries, finally the other 5 rivers. Fractions of heavy metals analysis showed that Hg, Cr, Ni and Cu existed mainly in residual fractions (77.56%, 64.83%, 56.52% and 48.93%) , and extractable fraction was dominant for Cd (89.22%), followed by Zn, Pb and As (70.35%, 69.50% and 63.70%). Potential ecological risk assessment showed that Cu, Zn, Pb, Cr, Ni and As had low pollution level, Cd had a higher pollution level and Hg had heavily pollution level, the potential ecological risk of heavy metals was in the descending order of Nanfei-Shiwuli river>Yuxi river>Zhegao river>Hangbu-Fengle river>Pai river>Baishishan river>Zhao river. The risk assessment code showed that Cd had very high risk level, Zn had high risk level, Cu and Ti were between low risk and medium risk level, Pb was between no risk and low risk level, Cr posed no risk. Therefore, emergent management measures must be taken to control pollution of Cd and Hg in Nanfei River and Yuxi River.
