某铁尾矿库周边土壤典型重金属污染评价

Pollution Assessment on Some Typical Heavy Metals in Soils Surrounding an Iron Tailings Reservoir

通过测定某铁尾矿库周边土壤中4种重金属元素(Cu、Cr、Pb、Cd)的含量及其形态特征,采用地累积指数法和次生相与原生相比值法(RSP法),探讨了研究区土壤重金属的污染程度。研究结果表明:土壤中重金属Cr、Cu、Cd的平均含量超过北京市土壤背景值,呈现一定的累积效应,重金属元素含量变化趋势为Cr>Cu>Pb>Cd。除Cd元素外,其它重金属形态以残渣态为主,占比均为50%以上,各样品重金属酸可溶态(F1)的含量占比大小顺序为Cd>Pb>Cu>Cr。评价结果显示75%样品中的Cr、58%的Cu和33%的Cd达到了轻度—中度污染;8%样品中的Cr和17%的Cu达到了中等污染;17%样品中的Cr达到了中等—强污染。区域内各个采样点中Cd元素污染风险较大,除Pb有一个点达到轻度污染风险外,其它Cr、Cu元素基本处于无风险的状态。研究区重金属元素污染风险大小的顺序为Cd>Pb>Cu>Cr。

The contents and biological characteristics of four heavy metals(Cu,Cr,Cd,Pb)are detected around a polluted tailings area.The degree of pollution of the heavy metals in this area is analyzed by geo-accumulation index and RSP method.Research indicates that the average contents of Cr,Cu and Cd in soil exceeded the background value of Beijing,showing a certain cumulative trend.The contents of the four heavy metals shows Cr>Cu>Pb>Cd.Except for Cd,the main forms of other heavy metals are residual state,accounting for more than 50%.The contents of the acid soluble state shows Cd>Pb>Cu>Cr.Evaluation results show that 75%of Cr,58%of Cu,and 33%of Cd are slightly to moderately contaminated.8%of Cr and 17%of Cu are moderately contaminated.17%of Cr is moderately to strongly contaminated.The risk of contamination of Cd is relatively high among sampling points in the study area.Except for one sampling point of Pb reaches a slight pollution risk,other heavy metals such as Cr and Cu are generally of risk-free.The order of pollution risk of the heavy metals in the study area is Cd>Pb>Cu>Cr.