峡江枢纽库区沉积物表层重金属分布及风险评价

Distribution and Risk Assessment on Heavy Metals in Surface Sediments of Xiajiang Reservoir

为掌握淹没前峡江枢纽库区沉积物表层重金属的污染特征,采集5个典型代表性断面沉积物表层样品,并对7种重金属进行了测定分析。结果表明,沉积物中7种重金属Cu、As、Pb、Cr、Hg、Cd和Zn的含量均值分别为11.19、9.48、40.69、58.82、0.15、0.27、79.85 mg/kg;库区沉积物表层重金属存在一定程度污染,除As、Cd外,其余重金属元素均已经超过鄱阳湖背景值。地累积指数法和污染指数法分析表明,Cd与Hg是主要污染因子,各元素污染程度排序为Cd>Hg>Pb>Cr>Zn>As>Cu,大部分重金属元素呈正相关,具有相似迁移过程的规律与污染来源。Hakanson潜在生态风险指数法评价与污染程度评价结果基本一致,Cd和Hg达到中等风险水平,其余元素在各断面都处于低风险水平。

In order to have an overall understanding on the pollution characteristics of heavy metals in the sediments of Xiajiang Reservoir,five typical representative cross sections of surface sediment samples were collected,of which seven kinds of heavy metals were determined. The contents of Cu,As,Pb,Cr,Hg,Cd,Zn were 11.19,9.48,40.69,58.82,0.15,0.27,79.85 mg / kg.There was a certain degree of heavy metal pollution in the surface sediments in reservoir area. In addition to As and Cd,the contentration of other metal elements were higher than that of the background of Poyang Lake. The indexs of geo-accumulation and pollution indexs analysis showed that Cd and Hg were the main pollution factors, the sequence of pollution degree was Cd〉Hg〉Pb〉Cr〉Zn〉As〉Cu. A significant positive correlation was found among most of heavy metals with similar rules and sources of the migration process. Hakanson potential ecological risk indexs were basically consistent with the evaluation of the pollution degree evaluation results. Cd and Hg were in the medium risk level,while the remaining elements were in a low level of risk.