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    南京东郊沿江地区农用地土壤重金属分布特征及风险性评价

    Distribution characteristics and risk assessment of the heavy metals in agricultural land along the Yangtze River in the eastern suburbs of Nanjing City

    • 摘要: 为查明南京东郊沿江地区农用地土壤重金属污染物类型及其影响范围,在该区采集了688个表层土壤样品,测定了pH值及As、Cd、Cr、Cu、Hg、Ni、Pb、Zn等重金属元素含量,采用单因子指数法、内梅罗综合污染指数法、潜在生态危害指数法进行污染风险性评估。结果表明:与南京市土壤元素背景值相比,除Hg外,As、Cd、Cr、Cu、Hg、Ni、Pb、Zn 等重金属元素均富集; 该区重金属污染元素主要为Cd,点位超标率为36.4%,以轻微污染为主,Cd污染区主要分布在中性及酸性土壤中。Cd单因子潜在生态危害指数表明:Ⅱ级(中度)以上风险区约占全区总面积的90%,Ⅲ级(较高)风险区约占全区总面积的10%。综合8种重金属污染风险分析结果,发现研究区大部分农用地处于安全生产等级,少部分农用地处于Ⅱ级和Ⅲ级风险区,总体上农用地土壤重金属潜在生态危害性较低。

       

      Abstract: To find out the heavy metal pollutant types and influence range of the agricultural land along the Yangtze River in the eastern suburbs of Nanjing City, 688 topsoil samples are collected to determine the pH values and contents of heavy metals such As As, Cd, Cr, Cu, Hg, Ni, Pb and Zn. The methods of single factor index, nemero comprehensive pollution index and potential ecological risk index are used to conduct the pollution risk assessment. The results show that compared with the background values of soil elements in Nanjing City, except Hg, 7 other heavy metals are all enriched. Cd is the main heavy metal pollution element in the area with the point exceeding rate of 36.4%, light pollution dominated. The Cd-contaminated areas are mainly distributed in neutral soil and acid soil. The Cd single factor potential ecological risk indexes indicate the risk areas above II level(moderate)account for 90% of the total area, and III level(high)risk areas occupy about 10%. Combined with the pollution risk of 8 heavy metals, most agricultural land are in the safe production level, with only a few farmlands in II and III risk levels. The potential ecological hazards of heavy metals in agricultural land is low on the whole.

       

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