杭州某污染场地土壤重金属污染调查及风险评价

Pollution investigation and risk assessment of heavy metals in soils from a contaminated site in Hangzhou

以杭州市某土壤污染地块为研究对象,分析了土壤中重金属As、Cd、Cr、Cu、Pb、Ni及Zn的含量,结果表明,该场地受到了不同程度的重金属污染,主要以Cd、Zn污染为主,均超出《土壤环境质量标准》(GB15618-1995)中的三级标准。运用Nemerow污染指数法评估了土壤重金属污染程度,结果表明,4个土层中重度污染的样点分别占所有采样点的13.8%、17.2%、3.4%、3.4%,主要是Cd、Zn的单因子指数较大引起的。运用生态危害指数法评估了土壤重金属的潜在生态风险,结果表明,4个土层(1~2m、2~4m、4~6m、6~8m)中As、Cr、Cu、Pb、Ni 5种土壤重金属的Eir值均处于安全范围,Cd处于极强潜在生态风险,潜在生态风险点位占所有采样点的11.2%,Zn处于中等潜在生态风险,潜在生态风险点位占所有采样点的0.86%。

The pollution situation of As,Cd,Cr,Cu,Pb,Ni,and Zn was investigated in soil samples from a contaminated site in Hangzhou. The results showed that this site was polluted by heavy metals in different extent. Compared to the Environmental Quality Standard for Soils（GB15618-1995）,Cd and Zn were the main pollutants,and their concentrations exceeded the class III standards in all soil samples. Based on Nemerow index method,the soil pollution status was evaluated. It was found that the heavily polluted points accounted for13.8%,17.2%,3.4% and 3.4% of the total sampling points respectively from up to down,in four soil layers,and the major pollutants were Cd and Zn. Based on Ecological Risk Index method,the potential ecological risk index（Eir）of the heavy metals in soils were assessed. Thevalues of As,Cr,Cu,Pb,and Ni in four-layer soils（1-2m,2-4m,4-6m and 6-8m）lied in the safe range. However,Cd in 11.2% of the sampling points posed an extremely strong potential ecological risk,and Zn in 0.86% of the sampling points posed a medium potential ecological risk.