ASSESSMENT FOR THE HEAVY METAL POLLUTION IN THE SEDIMENTS OF WULIANGSHUHAI LAKE, INNER MONGOLIA

Based on survey data of the sediments (0-20 cm) collected from Wuliangshu Lake, the risk of heavy metal pollution is assessed by ecological risk index method. According to the national standard of ocean sediment quality (first level), threshold effective level and national standard of soil quality (first level), the lake presents a combined pollution, mainly with pollutants of Cu, Cd, Ni and Zn. There are a remarkable correlation among the total contents of Pb, Cd, As, Cu, Cr, Hg and Zn, suggesting the same origin of pollutants. The ecological risk index method shows that most part of the lake is of slight pollution risk. The extreme pollution areas are distributed only near the mouth of three drainage-irrigation channels. The other areas are heavily polluted.