某铀尾矿库周围农田土壤重金属污染与评价

Contamination and Assessment of Heavy Metals in Farmland Soils Near an Uranium Tailings Pond

为能够定量评价铀尾矿库周围农田土壤重金属污染程度,采用地积累指数和内梅罗污染指数2种方法相结合来进行土壤中重金属污染综合评价。研究结果表明,铀尾矿库周围部分农田土壤中重金属Cd、Ni、As、Cu、Hg、Zn含量存在积累和超标情况,尤以Cd的超标率最大,Ni和As次之;Pb、Cr含量能够满足标准限值要求。总体上,铀尾矿库周围农田土壤中未受重金属污染(清洁、尚清洁)、轻度污染的分别约占1/3;土壤受重金属中度污染占21.4%,重污染占12.2%。主要污染因子为Cd,其次是Ni和As,该区大部分土壤环境质量未受到Cr、Pb、Cu和Zn的影响。铀尾矿库周围土壤正以Cd、Ni、As等重金属复合污染的形式出现积累,应加强对铀尾矿库周围农田土壤重金属的污染防治。

Abstract： Geoaccumulation index （Igeo） and Nemerow integrated pollution index, as the quantitative diagnostic tools, were used to evaluate the contamination status of various heavy metals including Cd, Hg, Ni, Zn, Cu, As, Pb and Cr in farmland soils near an uranium tailings pond. Results showed that some heavy metals such as Cd, Ni, As, Cu, Hg, Zn contents were accumulated in farmland soils and the farmland soils were polluted according to common soil assessment standards, with the most serious contamination by Cd , followed by Ni and As, while Pb and Cr contents in the soils satisfactory to the standard limit. On the whole, the soils uncontaminated and mildly contaminated by heavy metals near the uranium tailings pond accounted for one-third respectively, the soils moderately contaminated by heavy metals accounted for 21.4%, severely contaminated accounted for 12.2%.The main pollution factor was Cd element, followed by Ni and As, and most of the soils were uncontaminated by Cr, Pb, Cu and Zn elements. It was found that heavy metal contamination was accumulated in the farmland soils and it belonged to Cd-Ni-As combined type. The prevention and control of heavy metal pollution in farmland soils near the uranium tailings pond should be strengthen.