东莞市不同区域菜地土壤重金属污染状况研究

The heavy metal contamination of vegetable soil in Dongguan city

对东莞市及其不同区域菜地土壤重金属污染情况进行了调查和分析,参照国家土壤环境质量标准,运用单因子污染指数法和综合污染指数法对上述土壤质量进行了评价。结果表明,全市和各区土壤受到了不同程度的重金属污染,具体表现为:全市土壤Cd、Cu、Ni和Pb的超标率分别为4.9%,6.6%,3.3%和95.1%,均处于轻污染状态,以Pb污染最严重;土壤Cr未有超标,仅西北区域达到了警戒级水平。全市土壤重金属含量各样点间变异较大(Zn、Cr、Pb、Cd、Cu、Ni和有效Cu、Zn的变异系数分别为51.5%,54.1%,37.5%,48.8%,60.2%,57.3%和85.3%,64.7%),但对各重金属元素而言却存在着不同程度的区域差异。

Contamination characteristics of heavy metal elements of agriculture soils in Dongguan city and its 6 part regions were studied. In addition, the contamination status of above-mentioned soils was assessed by means of single and comprehensive pollution index method comparing with the environmental quality standard for soils of China. The results showed that soils of Dongguan city and its part regions were contaminated by Cd, Cu, Ni, Zn and Pb to a different extent. The over standard rates of Cd, Cu, Ni and Pb in Dongguan soils were 4.9%, 6.6%, 3.3% and 95.1%, respectively. Soils contaminated by Pb were the most severe. There was no sample site contaminated by soil Cr, and only took on alert degree in northwest region. Total and available content variance of heavy metal elements among sample sites was big (The variance coefficients of Zn, Cr, Pb, Cd, Cu, Ni and available Cu, Zn were 51.5%, 54.1%, 37.5%, 48.8%, 60.2%, 57.3% and 85.3%, 64.7%, respectively) but there was a spatial variance of different extent for the heavy metal elements.