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

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 431.2mg/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.