高砷煤矿区土壤重金属污染及潜在的生态风险

Heavy Metal Pollution and Potential Ecological Risk in the Soils Around a High-arsenic Coal Mine Area

为考察黔西南煤矿区土壤重金属的污染状况,采集了5个典型高砷煤矿周围土壤作为研究对象,并对其重金属（Pb、Cd、Hg、As、Cu和Ni）的含量进行分析测定,分别采用地累积指数法和潜在生态风险指数法对其重金属污染状况、生态风险进行评价。结果表明：黔西南5个典型高砷煤矿周围土壤重金属的平均含量均高于贵州省土壤重金属的平均背景值,小尖山煤矿周围土壤重金属污染最严重,其中Hg和As的平均含量分别为0.65mg/kg和431.2mg/kg。5个煤矿周围土壤As污染突出,其中小尖山、大丫口和梨树坪煤矿周围土壤As的地累积指数分别为3.85、3.42和3.02,均为偏重污染水平,同时还受Pb、Cd、Hg、Cu和Ni不同程度的污染。5个煤矿周围土壤重金属的潜在生态风险指数300-600,具有＂强＂生态风险。其中,Hg的潜在生态风险参数最高,As次之,这2种污染因子均达到＂强＂以上生态风险水平,应引起相关部门的高度重视。

To evaluate the contamination status of soil heavy metal in a coal mine area from Southwest Guizhou, in this case study, the concentrations of heavy metals （Pb, Cd, Hg, As, Cu, Ni） in soils around five typical high-arsenic collieries in a coal mine area from southwest Guizhou were analyzed, and the contamination status and potential ecological risks of heavy metals in soils were investigated by using the geo-accumulation index and the potential ecological risk index, respectively. The results indicated that the average contents of heavy metals in soils surrounding the five collieries were higher than Guizhou soil average background values. The soils collected from the Xiaojianshan colliery had the most serious heavy metal contamination. The average content of Hg in soils was 0. 65 mg/kg around Xiaojianshan colliery. The average content of As in soils was 431.2 mg/kg around Xiaojianshan colliery. According to the geoaccumulation index, the soil samples collected from the five high-arsenic collieries were severely contaminated with As, the geo-accumulation index of As in soils around three collieries were 3. 85 in Xiaojianshan colliery,3.42 in Dayakou colliery and 3.02 in Lishuping colliery, indicating As pollution was relatively serious in soils of three collieries. Moreover, other heavy metals, such as Pb, Cd, Hg, Cu and Ni were found in soils at various elevated concentrations. According to potential ecological risk index, the results indicated that the potential ecological risk index of heavy metals in soils around five high-arsenic collieries were between 300-600, and reached strong ecological risk level. The potential ecological risk factors for Hg were the highest, followed by As. These two kinds of heavy metal achieved strong ecological risk above,which should cause the administration department＇s enough attention.