太原城区周边土壤重金属分布特征及生态风险评价

Distribution and Risk Assessment of Soil Heavy Metals in Area Surrounding Taiyuan City

以太原市城区周边土壤为研究对象,分析了土壤重金属Cu、Zn、Ni、Cr、Pb、Cd、Hg和As的污染特征及其空间分布特征,并通过对研究区的污染源进行资料收集和实地调查,探究了污染源与土壤重金属污染间的关系。结果表明:研究区土壤重金属元素Zn、Cr、Hg、Pb、Cd的均值都超过了山西省土壤背景值,元素Ni、Cu和As与背景值相差不大;从Hankson生态风险评价来看,研究区的综合生态风险程度处于中等水平,Hg和Cd的风险较为明显,其达到中等风险强度以上的样点分别有74.1%和30.8%;从空间分布来看,研究区的南部土壤重金属元素Pb、Hg、Cd、Cu、Zn、Ni和Cr的含量较高,As含量较高的区域集中分布于东北部;化工类污染源和矿石类污染源是造成研究区重金属污染的两个主要污染源。

Using Taiyuan City as a study area, we measured the concentrations of soil heavy metals(Cu, Zn, Ni, Cr, Pb, Cd, Hg, and As),mapped the spatial distribution of heavy metals based on Kriging interpolation, evaluated the ecological risks of heavy metals by Hankson index, and explored the relationships between soil heavy metal concentrations and pollution sources based on the pollution source investigation in Taiyuan. Results showed that:mean values of Zn, Cr, Pb, Cd and Hg were higher than the background values of Taiyuan City soils,while those of Ni, Cu and As were almost equal to their background values. According to the Hankson ecological risk assessment, the soils in the studied area were at medium risk level. Mercury and Cd were the main risk factors. The 74.1% and 30.8% of samples exceeded medium risk levels of Hg and Cd, respectively. The concentrations of Pb, Hg, Cd, Cu, Zn, Ni and Cr were high in the south part of the area, and As was high in the south and northeast areas. Chemical industries and mineral industries were two major sources of soil heavy metal pollution in Taiyuan City.