Evaluation of potential ecological risk of heavy-metal pollution in bottom mud of the Xiyu River in the Xiaoqinling gold mining area

Heavy metals are easy to accumulative, which may yield strong ecological effects. This paper analyzes contents of the seven heavy metals Hg, Pb, Cd, As, Cr, Cu and Zn in sediments of the Xiyu River on the Shaanxi-Henan border. According to the contrast parameter, the pollution of bottom sediments of the Xiyu River by gold mining operations was evaluated. The results show that mercury and lead were main pollution elements. The potential ecological risk of heavy-metal pollution is discussed using the potential ecological risk index. The authors think that: the potential ecological risk of mercury and lead in the whole Xiyu River drainage area is very strong and Cd has strong potential ecological risk, while the potential ecological risks of Cr, As and Zn are weak.