张掖市某铁尾矿库的土壤重金属污染状况及潜在生态风险评价

Assessment of Soil Heavy Metal Pollution and Potential Ecological Risk for an Iron Tailing Pond in Zhangye City

为了解尾矿区及周边土壤环境质量,采集张掖市临泽县境内某铁尾矿库及周边闲置农用地的土壤样品,分析其理化性质、土壤养分和Cd、Pb、Cr、Cu、Ni、Zn六种重金属的含量;引入内梅罗综合污染指数法、地累积指数法和Hakanson生态风险指数法,科学评价该区域土壤的重金属污染状况和潜在生态风险.结果表明:各采样点的土壤理化性质极端,pH值均大于7;土壤营养成分匮乏,有机质含量处于土壤养分4级标准及以下,全氮和全钾含量分别为6级和5级标准;与对照样点CK相比,尾矿库区土壤Pb、Cd和Zn含量均达到严重污染水平,而Cu为轻度污染,Cr和Ni含量未超标,铁尾矿的排放已造成极高的潜在生态风险,亟需采取有效措施,开展污染治理和生态修复.

In order to understand the soil environmental quality in and around the tailing area,soil samples were collected from an iron tailing pond and its surrounding idle cropland in Linze county,Zhangye city.Physicochemical properties,soil nutrients and content of six heavy metals(Cd,Pb,Cr,Cu,Ni and Zn)were analyzed.Then,the Nemerow integrated pollution index,geo-accumulation index and Hakanson ecological risk index were used to assess the soil heavy metal pollution and the potential ecological risk of the study area.The results show that the physicochemical properties of each sampling site are extreme.The pH values are more than 7,and the soil nutrients are deficient,with the content of organic matter below the level 4 of soil nutrient standard,and the content of total nitrogen and total potassium at level 6 and level 5,respectively.Besides,the content of Pb,Cd and Zn in the soil of the tailing area reach the serious pollution level,as compared with the CK site,while Cu is subject to slightly pollution,and Cr and Ni level do not exceed the standard.The discharge of iron tailings in the region has caused extremely high potential ecological risks,so there is an urgent need to take effective measures to carry out pollution control and ecological remediation.