密云水库入库河流沉积物重金属的风险评价

密云水库作为首都北京重要的水源地,了解其入库河流的重金属污染具有重要现实意义。文章在流入密云水库的潮白河水系选择了6个监测断面,测定了沉积物中Cu、Zn、Pb、Cr、Cd五种重金属的含量,并利用地累积指数法和Hakanson潜在生态风险指数法对沉积物重金属进行了生态风险评价,结果表明:(1)基于地累积指数法的评价表明研究区内5种重金属生态风险等级的排列顺序为Cd>Cr>Cu>Zn>Pb;(2)基于单项潜在生态风险指数的评价表明研究区内沉积物中Cu、Pb、Zn、Cr处于轻微等级,Cd则有不同程度的污染;该区域重金属生态风险等级顺序为Cd>Cu>Cr>Pb>Zn;(3)根据综合潜在生态风险指数,汤河怀柔区段处于中等风险等级;潮河、白河及黑河段的风险等级为轻微。

Risk Assessment on Heavy Metals in Sediments of Rivers Flowing into Miyun Reservoir

In order to understand the potential heavy metal pollution risk levels,six sediments were sampled in Chao River and Bai River and the concentrations of Cu,Zn,Pb,Cr and Cd in the samples were determined.Based on the analysis,a comprehensive assessment on heavy metals in the sediments was presented using index of geo-accumulation and Hakanson potential ecological risks index.The results indicate that,based on the geo-accumulation index,the risk levels of the heavy metal in the area rank as Cd>Cr>Cu>Zn>Pb.Based on the single heavy metal ecological risk index,the risk levels of Cu,Pb,Zn and Cr belong to "slight" level,while the risk level of Cr is a bit serious.The risk order of the heavy metals is Cd>Cu>Cr>Pb>Zn.According to the Hakanson potential ecological risk index,Tang River in Huairou is of the middle level;Chao River,Bai River and Hei River are of the slight level.