大冶矿区周边农田土壤和油菜重金属污染特征研究

Investigation on the Heavy Metal Contamination of Farmland Soil and Brassica Campestris Nearby Mining Areas in Daye City,China

以大冶典型铜矿区为中心,辐射周边农田,探索农田土壤重金属污染特征及重金属在油菜中的积累变化规律。结果表明,以湖北省土壤背景值进行评价,土壤受到重金属不同程度的污染,其中Cd严重超标,Cu次之;采用国家二级标准进行评价,Zn、Cr和Pb未对土壤造成污染。进行内梅罗综合污染指数法评价发现,以土壤背景值为评价标准,各采样点均达到重金属严重污染水平;以国家二级标准评价时,只有2号采样点土壤属于中度污染水平,其他样点土壤都受到了较为严重的重金属污染。矿区农田油菜各部位重金属含量变化幅度较大,包括Cu、Pb、Zn、Cd和Co在内的5种重金属含量分布规律都是茎叶>籽粒≈根,Mn则是籽粒>茎叶>根。油菜地上部植株中Cu、Pb、Zn、Cd含量均超出食品卫生标准最高限值,且Cd、Pb超标倍数远大于Cu、Zn。富集系数变化规律为Mn>Zn>Cd>Ni>Cu>Pb垌Co。

Many mining enterprises are distributed in Daye City because of the abundant mineral resources.With the development of industrialization,the environments nearby these enterprises were destroyed severely.Investigation was conducted to evaluate the heavy metal contamination of farmland soil and Brassica campestris plant around typical copper mining areas in Daye City.The results showed that the soils were contaminated with different heavy metals compared with soil natural background values of Hubei Province,and among them cadmium（Cd） was mostly contaminated,followed by copper（Cu） as second severely contaminated element.While using China National Standard（CNS） as an evaluation standard,the soils were contaminated with heavy metals except for Zn,Cr and Pb.Nemorow integrative index method was further employed to evaluate the heavy metal contamination level,and the result showed that all the tested soils were severely contaminated based on both soil natural background values and CNS as evaluation standard,with soil sample No.2 as an exception,which was subjected to the moderate pollution level.The heavy metal concentrations varied in different parts of Brassica campestris,with a character of leafgrain≈root for Cu,Pb,Zn,Cd,and Co,and seedleafroot for Mn.The concentrations of Cd,Pb,Cu and Zn in Brassica campestris were all exceeded the national food sanitation standard,and the exceed level for Cd and Pb were higher than Cu and Zn.The order of the enrichment coefficients was MnZnCdNiCuPb》Co.