宿州市煤矿区农田土壤重金属污染及生态风险评价

HEAVY METAL POLLUTION AND ECOLOGICAL RISK ASSESSMENT OF FARMLAND SOIL AROUND COAL MINE IN SUZHOU CITY

为揭示矿区周边土壤中重金属元素的污染特征,采用金属污染指数法(MPI)、污染负荷指数法(PLI)和Hakanson潜在生态风险指数法,对宿州市4矿区周边农田土壤中Zn、Cr、Cd、Pb、Cu、As和Hg等7种重金属元素进行测试分析,研究了宿州市矿区周边土壤重金属污染程度及潜在的生态危害性.结果表明:1)7种重金属元素平均含量均高于非矿区土壤环境背景值,尤其Cr含量达到非矿区土壤背景值的2-4.17倍,Cd含量达到非矿区土壤背景值的1-3.05倍;矿区重金属综合污染程度范围为8.682-19.108,在100 m距离处属于强污染,其他距离处均属于中等污染.2)矿区土壤重金属污染指数变化范围在9.811-18.768之间,各样品的重金属污染指数均高于非矿区土壤环境背景值的污染指数,土壤重金属具有一定的富集效应;土壤综合污染负荷指数为1.699,为中等污染.3)除Cd和Hg外,重金属潜在生态风险系数均属于轻度风险危害,Cd和Hg在宿州市矿区农田土壤生态污染中的贡献率较高.矿区农田土壤潜在生态风险指数RI范围在125.51-365.49,4个矿区平均值均属于中等污染水平,其中桃园矿污染最为严重.

In order to research the pollution characteristics of heavy metals around coal mine soil, heavy metal elements Zn, Cr, Cd, Pb, Cu, As and Hg were quantitatively analyzed around coal mine soils in Suzhou city. The pollution degree and potential ecological risk of the heavy metals around coal mine soils in Suzhou city were evalua- ted using metal pollution index（MPI） , pollution load index（PLI） and Hakanson ecological risk index. The results were summarized as follows ： 1 ） The average contents of 7 kinds of heavy metal are higher than the soil background values of the non-mining. Compared with the soil background value of non-mining area, the content of Cr reached 2-4.17 times, and Cd was 1-3.05 times, respectively. The comprehensive pollution degree of heavy metals around coal mine is range from 8.682 to 19.108, which belongs to the strong pollution at the distance of 100 m and other distances are moderate pollution. 2） Heavy metal pollution indexes in soil around coal mine are range from 9.811 to 18.768, and heavy metal pollution indexes of all samples are higher than soil environmental background values of non-mining, which explain soil heavy metals have certain enrichment effect around coal mine because of human ac- tivity. The soil comprehensive pollution load index was 1.699, which was moderately polluted. 3） Except for Cd and Hg, the potential ecological risk coefficient of heavy metals is lower than 40 that belongs to light risk harm, and Cd and Hg have higher contribution rate in soil ecosystem pollution in Suzhou city mining area. Soil potential ecological risk indexes （ RI ） around coal mine are range from 125.51to 365.49, and the average values of four mining area are all belonged to moderate pollution levels, among which, the pollution level of Taoyuan mine is the most serious.