大冶古铜矿遗址周边农田土壤重金属污染及潜在生态风险评价

Assessment of Heavy Metal Pollution and Potential Ecological Risk of Farmland Soil around Ancient Copper Mine Site in Daye City

为清楚认识大冶市古铜矿遗址周边农田土壤的重金属污染及潜在生态风险,并为农田土壤重金属修复提供科学依据,采用单因子污染指数法、内梅罗综合污染指数法和Hakanson潜在生态风险指数法,评价该地区农田的重金属污染状况和潜在生态风险程度,并通过Arc GIS绘制出重金属污染和潜在生态风险的空间分布情况。结果表明:该地区重金属含量的平均值均高于大冶市土壤背景值,土壤重金属超标问题显著。60个样品中,Cu和Cd分别高达35%和32%的重度污染率,特别是由Cd元素引起的潜在生态风险十分严重,35%以上的样品土壤处于较高潜在生态风险及以上;综合评价结果显示,38%的样品土壤处于重度污染,23%的样品土壤处于较高潜在生态风险及以上。大部分重金属元素含量和潜在生态风险程度的空间分布特征表现为矿区中心地区高,向外辐射区域逐渐降低,说明矿业活动中采矿粉尘、采矿废水、矿石运输是造成重金属污染及潜在生态风险的主要原因。另外,村民从矿山取回土壤作为农田土壤也在一定程度上造成了核心矿区土壤的转移。

In order to clearly understand the heavy metal pollution and potential ecological risk of farmland soil around the ancient copper mine site in Daye City,and provide scientific basis for heavy metal remediation technology in farmland soil,in this study,the single factor pollution index method,Nemerow comprehensive pollution index method and Hakanson potential ecological risk index method were used to evaluate the heavy metal pollution status and potential ecological risk of farmland in this area,and the spatial distribution of heavy metal pollution and potential ecological risk was drawn by ArcGIS.The results showed that the average value of heavy metals in the region was higher than the soil background value of Daye City,and the problem of excessive soil heavy metals was obvious.Among the 60 samples,the heavy pollution rates of Cu and Cd were as high as 35%and 32%respectively.Especially,the potential ecological risk caused by Cd was very serious,and more than 35%of the soil samples were in high potential ecological risk and above.The comprehensive evaluation results showed that 38%of the sample soil was in severe pollution,and 23%of the sample soil was in high potential ecological risk and above.The spatial dis-tribution characteristics of most heavy metal contents and potential ecological risks were high in the central area of the mining area and gradually decreased in the outward area,indicating that mining dust,mining wastewater and ore transportation in min-ing activities were the main causes of heavy metal pollution and potential ecological risks.In addition,some villagers used mine soil as farmland soil also caused the transfer of core mining soil to a certain extent.