内蒙古草原某铜钼矿区土壤重金属污染特征研究

Characteristics of Heavy Metals in Soils from a Copper-Molybdenum Mining Area of Grassland in Inner Mongolia

对位于内蒙古草原的某大型铜钼矿采选矿区土壤和尾矿库区周围土壤的重金属污染状况进行了调查研究。单项污染评价结果表明,矿区土壤中Cd、Cr、Cu、As、Hg、Ni、Pb和Mo 8种重金属元素的含量均低于国家土壤环境质量Ⅱ级标准限值;与内蒙古呼伦贝尔盟土壤重金属背景值相比较,8种元素均有不同程度的超标,超标率介于25.85%-100%,但超标倍数较低,从侧面说明了有色金属铜钼矿的开发对土壤环境造成了累积污染,但由于开发年限较短（2009年建成投产）,累积污染并不严重。内梅罗综合污染评价结果表明,矿区147件土壤样品累积综合污染指数PN在1以上（轻度污染以上）的有95件,所占比例为64.63%,说明矿区土壤已经受到不同程度的重金属累积污染。重金属含量纵向分布结果表明,表层土壤的重金属含量高于深层土壤。由于矿区周边地势较为平坦开阔,故该地区主导风向对矿区不同方位土壤重金属污染水平影响较为显著。

The pollution characteristics of soil heavy metals were surveyed and analyzed in mining,mineral processing area and around the tailing reservoir of a large copper-molybdenum mine,which located in the Inner Mongolia grassland. The results of single contamination index method showed that the content of eight heavy metals in soils were all lower than Grade II of National Soil Environmental Quality Standard but higher than the soil background values of Hulunbeier league,with exceeding between 25.85% ~100%. However,the exceed multiples were minor which showed not serious accumulative pollution. The results of Nemerow multifactor index method showed that the comprehensive pollution index（PN）of 95 soil samples were higher than 1,belonging to slight pollution and above. From the results of vertical distribution,it could be seen that the content of heavy metals were decreased with the depth. Because the surrounding terrain of the mining area was relatively open and flat,the local dominant wind had significant effect on the heavy metals pollution level around the mining area.