滇池外海底泥重金属污染分布特征及风险评价

Heavy metals distribution characteristics and potential ecological risk evaluation in the sediment of outer area of Lake Dianchi

采用底泥质量标准(SQGs)法和潜在生态风险(RI)法对滇池外海22个点位20cm柱状底泥中重金属As、Hg、Cr、Cd、Pb、Zn和Cu浓度分布及潜在生态风险进行了研究.结果表明,Pb的最高浓度达319mg/kg,9个点位超过风险评价中值或高概率效应浓度,是超标最严重的重金属.各元素污染程度顺序为Pb】Cu】Hg】As】Cd】Cr】Zn.Pb、Cu、Hg的污染层为15~20cm,其余重金属污染层为10~15cm.潜在生态风险(RI)评价表明,滇池外海底泥重金属污染总体处于中等生态风险水平,北部为'强'等级,潜在风险顺序为Hg】Cd】As】Pb】Cu】Cr】Zn.两种方法的评价结果具有一定的差异性,在实际应用中需结合起来使用.此外,滇池底泥重金属浓度与潜在生态风险表现出一致的区域性差异,即北部大于南部,西部大于东部.

Heavy metals such as As, Hg, Cr, Cd, Pb, Zn and Cu in the 20cm sediment core of 22 sampling sites in the outer area of Lake Dianchi were analyzed. The results evaluated using sediment quality guidelines (SQGs), showed that the highest content of Pb was 319mg/kg, which seriously exceeded the guidelines values, and 9 sampling sites exceeded ERM/PEL values. The degree of contamination in descending order was Pb>Cu>Hg>As>Cd>Cr>Zn, the content of Pb, As and Cu was still high in the 15-20cm sediment core,and the depth of contamination of the others was generally as deep as 10-15cm.In potential ecological risk index (RI), suggested that Lake Dianchi hasmid level of ecological risk, whereas the north area has high level, and the order of descent was Hg>Cd>Pb>As>Cu>Cr>Zn. The two evaluation approaches should be applied together to overcome the diversity problem. The contamination degree and potential ecological risk were spatially different; most obviously the condition in the north area was more serious than the south and the content in the west was higher than the east.