水城三岔河河道沉积物重金属分布特征与风险评价

Distribution features and risk assessment of heavy-metal pollutants in the sediments from the Sancha River in Shuicheng

为了查明水城三岔河大湾段河道沉积物重金属污染状况,对水城三岔河流域大湾段河道沉积物进行分层采样,分析7种重金属(Cd、Pb、Zn、As、Cu、Hg、Ni)的分布特征,并采用潜在生态风险指数法评价重金属的环境风险。结果表明,三岔河河道沉积物重金属呈现明显的上下游差异和垂直分布差异。在泥煤层,重金属含量均达到了最大值,泥煤层严格控制着重金属在垂直剖面上的分布,是三岔河重要的"二次污染"支援。沉积物重金属潜在生态风险指数评价结果表明,三岔河大湾段河道沉积物RI值在1 502~17 690之间,处于很强的生态风险水平。

In order to find out the heavy metal pollution in the sediment from the section of Dawan of the Sancha River,three points were sampled by the way of layering.Then the distribution features of seven heavy metals including Cd,Pb,Zn,As,Cu,Hg and Ni were analyzed.The environmental risk of heavy metals was assessed by using potential ecological risk index.The results show that there exist both the upper-to-down stream differences and vertical distribution differences about the content of heavy metals.In the mud coal layer,heavy metal contents reach to the maximum,and the vertical distribution of heavy metals is controlled by the mud coal layer strictly.Consequently,it is an important secondary pollution source of the Sancha River.The results of the potential ecological risk assessment show that the potential ecological risk index(RI)of the sediments is between1 502-17 690,which is a strong ecological risk level.