呼伦贝尔露天煤矿堆土场外围牧场土壤的重金属污染评价

为露天煤矿矿区的土壤改良与修复提供依据,采用单因子污染指数法、内梅罗综合污染指数法与Hakanson潜在生态指数法相结合对呼伦贝尔市东明露天煤矿堆土场外围东南侧牧场土壤Cr、Cu、Zn、Cd、Pb、As和Hg等7种重金属的含量特征、污染程度与潜在生态风险进行研究,同时运用相关分析及主成分分析探讨牧场土壤重金属的主要来源。结果表明:牧场土壤7种重金属含量与国家土壤环境质量标准(GB15618—1995)二级标准相比均未超过规定限值,与内蒙古土壤重金属背景值相比,Zn和Pb的含量均超标,超标率为5.56%和83.33%。牧场土壤7种重金属的单项污染指数均1,土壤污染等级为清洁;综合污染指数0.7,土壤污染等级为安全。Cd的潜在生态危害系数平均值为53.04(40),呈中等生态危害程度,其他金属均为低生态危害程度;7种重金属综合潜在生态危害指数平均为86.43(90),呈轻微生态危害程度。主要贡献因子是Cd。Cu、Zn、Cd与Pb及As与Hg具有相同来源的可能性大,Cr具有单独的污染来源。

Heavy Metal Pollution of Pasture Soil around Soil Accumulated Place of Hulunbuir Opencast Coal Mine

The content,pollution degree and potential ecological risk of Cr,Cu,Zn,Cd,Pb,As and Hg in pasture soil around soil accumulated space of Dongming Opencast Coal Mine in Hulunbuir City weredetermined by single-factor pollution index,Nemerow comprehensive pollution index and Hakanson potential ecological index methods and the main source of heavy metals in pasture soil was discussed by correlation analysis and principal component analysis to provide the scientific basis for soil improvement and remediation in opencast coal mining area.Results:The content of Cr,Cu,Zn,Cd,Pb,As and Hg in pasture soil does not exceed the specified limits compared with the secondary national soil environmental quality standard.The content of Zn and Pb exceeds the standard compared with the background value of soil heavy metals in Inner Mongolia and the exceeding rate of Zn and Pb is 5.56％ and 83.33％ respectively.The single pollution index of seven heavy metals in pasture soil is less than 1 and the soil pollution grade is clean.The comprehensive pollution index is less than 0.7 and the soil pollution grade is safe.The mean value of Cd potential ecological hazard coefficient is 53.04 (＞40) which indicates a moderate ecological hazard degree and other heavy metals all are in a low ecological hazard degree.The mean comprehensive potential ecological hazard index of seven heavy metals is 86.43 (＜ 90) which indicates a slight ecological hazard degree and the main contribution factor is Cd.Cu,Zn,Cd and Pb,As and Hg may came from the same source but Cr may came from a sole pollution source.