某酸性历史遗留矿山排土场土壤重金属污染特征及环境评价

Soil Heavy Metal Pollution Characteristics and Environmental Evaluation of Some Historical Acid Mine Dump

为了解多金属矿酸性排土场土壤污染现状,选择某酸性历史遗留矿山排土场表层土壤(0~20 cm)为研究对象,采集了表层9个混合土壤样品,分析了土壤中Pb、Cu、Zn、Cd共4种重金属含量,采用单因子指数法、内梅罗综合指数法,ArcGIS空间插值法探讨了重金属污染现状和空间分布特征,评价了研究区的土壤环境。结果表明,1)研究区土壤pH值均值为3.70,为强酸性。研究区存在重金属污染,Pb、Cu、Zn、Cd平均含量分别为6 134.36 mg/kg、642.01 mg/kg、1 035.83 mg/kg、1.52 mg/kg,分别为其风险筛选值的87.6倍、12.8倍、5.2倍、5.1倍;2)研究区土壤环境质量评价分级均处于Ⅴ级,为重度污染。4种金属元素污染指数P_(i)平均值排序为:P_(Pb)(87.63)>P_(Cu)(12.84)>P_(Zn)(5.18)>P_(Cd)(5.08),Pb、Zn污染面积更大,P_(综)平均值为65.06,各样点间相差较大,范围为28.23~89.23;3)研究区土壤pH值与重金属元素Cu之间具有极显著的正相关关系,而各重金属元素之间相关性较弱。

To understand the status of soil pollution in acid dumps of polymetallic mines,a study was carried out for some historical acid mine dump,collecting 9 mixed soil samples and analyzing heavy metal contents of Pb,Cu,Zn and Cd in the soil.The present situation and spatial distribution characteristics of heavy metal pollution were discussed by using single factor index method,Nemerow index method and ArcGIS spatial interpolation method,and the soil environment in the study area was evaluated.The results show as follows:1) The average pH value of soil in the study area is 3.70,which is highly acidic.There is heavy metal pollution in the study area,and the contents of Pb,Cu,Zn and Cd are all higher than the risk filter value,with the average contents of 6 134.36 mg/kg,642.01 mg/kg,1 035.83 mg/kg and 1.52 mg/kg,and are 87.6 times,12.8 times,5.2 times,and 5.1 times of the risk filter value,respectively;2) The soil environmental quality assessment grade in the study area is V,indicating heavy pollution.The average pollution index P_(i) value of the four metal elements is ranked as:P_(Pb)(87.63)>P_(Cu)(12.84)>P_(Zn)(5.18)>P_(Cd)(5.08).The contaminated areas of Pb and Zn are larger,the average P_(com) value is 65.06,and the difference among sample points is large,ranging from 28.23 to 89.23;3) The pH value and the heavy metal element Cu of soil in the study area show significant positive correlation,and the correlation among heavy metal elements is weak.