贵州土地整治项目区耕地土壤重金属含量特征及评价——以六枝特区岩脚镇为例
Characteristics and contamination evaluation on cultivated soil heavy metals in consolidation project areas in Guizhou province—A case study on Yanjiao town in Liuzhi District
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摘要: 为探明贵州省六枝特区岩脚镇土壤整治项目区重金属污染状况,通过对该区域中耕地土壤中Cr、Cu、Zn、Cd、Pb、Hg、As 等重金属元素进行分析,并采用单因子污染指数法,内梅罗综合污染指数法和潜在生态危害指数法,将土壤质量环境标准和贵州省背景值等2 种标准作为评价标准,对研究区土壤污染状况和生态风险进行评价,综合评价结果表明:以土壤环境质量标准作为评价标准时,其综合污染指数为0.923,处于警戒线水平;以贵州省背景值作为标准评价时,项目区存在一定程度的污染,旱地的综合污染指数高于水田。两种评价结果中单因子指数大于1 的元素为Cd、Cr 和Cu 3 种元素,为主要污染元素。生态评价结果显示,该区域耕地土壤处于为轻微生态危害级别,其中Cd 和Hg 为主要风险贡献因子。因此,在土地整治成果验收过程中,应重视重金属污染问题,合理布局高标准基本农田和无公害生产基地,从而更好的惠及民生和农业生产。Abstract: In order to find out the heavy metals contamination characteristics of cultivated soil in Yanjiao town consolidation project area of Liuzhi Special District in Guizhou province,the concentrations of heavy metals such as Cr,Cu,Zn,Cd,Pb,Hg,As etc. of cultivated soil in nine typical land remediation project areas were analyzed. Single factor contamination index method,Nemerow contamination index,contamination load index method and potential ecological risk index method were used to assess soil heavy metal pollution,State environmental standards and soil heavy metal background values of Guizhou province were used to obtain the soil environmental quality database in project areas. Assessment on the heavy metal contamination and ecological risk of cultivated soils in the project area,comprehensive evaluation results showed that,evaluating based on the secondary limit values of national standards,the comprehensive contamination index was 0.923 and was below alertness line level. There was already a high level of environmental contamination,dry land was higher than paddy fields. Two kinds of evaluation results showed that single factor index of Cd,Cr and Cu were above 1,these three elements were the major contributors to pollution in project areas. Ecological evaluation results showed that the cultivated soil of the areas was at slight ecological risk level,Cd and Hg were the main risk factos. Therefore,the high standard basic farmland and contamination-free production bases should be reasonable layout.