贵州丹寨县铅锌矿区小流域土壤重金属污染特征及生态风险评价

为探究贵州丹寨县铅锌矿区矿业活动对土壤系统运转对环境影响,以丹寨县兴仁镇铅锌矿区土壤为研究对象,采集小流域内河流周边不同土地利用类型土壤表层(0~20cm)的样品,分析测定土壤中Cu、Cd、Pb、Zn、Mn、Hg、As 7种重金属含量。应用单因子污染指数法、内梅罗综合污染指数法、地质累积指数法、潜在生态指数法对矿区不同土壤层重金属进行污染程度和潜在生态风险进行评价。结果表明,0~10cm土壤中Cu、Cd、Pb、Zn、Mn、Hg、As含量分别是贵州省土壤背景值的0.65、5.13、1.74、2.45、0.59、5.08、0.27倍。10~20cm土壤中Cu、Cd、Pb、Zn、Mn、Hg、As含量分别是贵州省土壤背景值的0.71、3.11、1.18、2.21、0.65、4.88、0.21倍。不同小流域与不同深度土层危害程度有所差异,通过评价结果得出研究区主要污染重金属元素为Cd、Hg,土壤重金属处于中等及以上潜在生态危害程度。

Heavy Metal Pollution Characteristics and Ecological Risk Assessment of Soils in Small Watershed of Lead-Zinc Mine in Danzhai County, Guizhou Province

In order to explore impact of mining activities on operation of soil system in lead-zinc mining area of Danzhai county,Guizhou province,soil of lead-zinc mining area in Xingren town,Danzhai county was taken as research object,and soil surface layers(0~20 cm)of different land use types around rivers in small watersheds were collected.Contents of 7 heavy metals Cu,Cd,Pb,Zn, Mn, Hg, As in soil samples were analyzed.Pollution degree and potential ecological risk of heavy metals in different soil layers in the mining area were evaluated through single-factor pollution index method,Nemeiro comprehensive pollution index method,geological accumulation index method,and potential ecological index method.The results show that contents of Cu,Cd,Pb,Zn,Mn,Hg and As in 0—10 cm soil are 0.65,5.13,1.74,2.45,0.59,5.08,and 0.27 times of the soil background value in Guizhou province.Contents of Cu,Cd,Pb,Zn,Mn,Hg,and As in 10—20 cm soil are 0.71,3.11,1.18,2.21,0.65,4.88,and 0.21 times of the soil background value in Guizhou province.Different small watersheds and different depths of soil layers have different levels of damage.The evaluation results show that the main polluting heavy metal elements in study area are Cd and Hg,and the soil heavy metals are at a medium or above potential ecological hazard level.