江安县红桥镇典型煤矿周边农田土壤重金属污染及生态风险评价

Heavy Metal Pollution and Potential Ecological Risk Assessment of Farmland Soils Surrounding a Typical Coal Mine in Hongqiao Town,Jiang’an County

为了详细查明江安县红桥镇极具代表性的煤矿周边农田土壤的环境现状,选择107份土壤监测样品以及10份背景样品来测试其重金属含量以及pH值。经过分析测定后,针对农田土壤以我国GB 15618-2018中规定的土壤筛选值为评价标准值,采用单因子以及内梅罗综合污染指数法来评价其污染现状,同时也充分结合潜在生态风险指数法来全面评价其生态风险。结果表明,农田土壤中8种重金属平均值均高于土壤背景值,存在一定程度的富集现象且累积程度最为突出的元素为Cd、Hg;靠近煤矿这一侧农田土壤中重金属含量较高于另一侧;从污染评价结果来看,按照由高到低的次序重金属单因子污染指数的排列顺序为Cd、Cu、Cr、Ni、Zn、As、Pb、Hg;清洁、尚清洁、轻度污染、中度污染、重度污染的土壤占比分别为27.10%、11.22%、27.10%、14.02%、20.56%;从生态风险评价结果来看,存在生态风险的元素为Cd,其他元素则主要体现为了低危害特征。

In order to explore the heavy metal pollution and potential ecological risks of farmland soils surrounding a typical coal mine in Hongqiao Town,Jiang.an County,107 surface soil samples and 10 background soil samples were collected systematically to determine pH values and As,Cd,Cr,Cu,Hg,Ni,Pb,and Zn concentrations.On this basis,the single factor pollution index method,Nemerow comprehensive pollution index method and potential ecological risk index method were used to evaluate the heavy metals in farmland soils based on the soil environmental quality risk management and control standard(GB 15618-2018).The results showed that the average values of soil heavy metals in the study area were higher than the regional background values,indicating the enrichment of heavy metals in the soil to different degrees,and Cd and Hg enrichment were the most prominent.The areas with higher heavy metal content were located on the side close to the coal mine.Results of heavy metal pollution assessment showed that heavy metal single factor pollution indexes were Cd>Cu>Cr>Ni>Zn>As>Pb>Hg,the cleanliness level,early warning,mild pollution,moderate pollution and heavy pollution accounted for27.10%,11.22%,27.10%,14.02%,and 20.56%,respectively;The potential ecological risk index showed that Cd was the main ecological hazard element,the remaining heavy metals were the low ecological hazard elements.