重庆某工业园土壤重金属污染特征、风险及源解析

以重庆市某工业园区表层土壤为研究对象,探讨了土壤重金属在不同季节的污染特征,利用污染指数法、健康风险模型和主成分/绝对主成分得分受体模型进行风险评价和源分析。结果表明:不同季节土壤样品间各重金属含量差异显著。35.5%的样品中汞含量超出土壤污染风险筛选值,其他元素未超标。与土壤背景值相比,各元素表现出不同程度的富集,汞超标约110~1300倍。内梅罗指数显示土壤整体和汞元素处于轻度污染及以下,其他元素为安全。潜在生态危害指数显示,土壤整体和汞属于极强污染,镉属于轻微~强污染,其他元素为轻微污染。土壤重金属总致癌风险为2.6×10^-7~1.0×10^-5,总非致癌风险熵均小于1,砷存在致癌风险,主要通过经口摄入暴露。秋季中,汞、六价铬、铅、镍、砷和铜来自工业源,镉主要来源于自然成因。春季中,镉和铅来自交通、冶金和燃煤等排放,镍、砷和铜源于冶炼和金属表面处理等排放,汞主要来自化工生产和燃料燃烧。交通运输、工业生产和燃料燃烧等污染的排放是土壤重金属的主要来源,今后应加强园区内汞、砷和镉的源头减排和治理。

Pollution Characteristics, Risk Assessment and Sources Analysis of Soil Heavy Metals in an Industrial Park of Chongqing

The pollution characteristics of soil heavy metals in an industrial park of Chongqing in different seasons were investigated. The pollution index method and health risks model were employed to evaluate the pollution risks. The principle component analysis and absolute principal component scores were conducted to identify pollution sources. The results showed that there were significant differences in the contents of heavy metals among soil samples in different seasons. In 35. 5% of the soil samples,Hg content exceeded the screening values, and other elements did not exceed the standard. Compared with the background values,there was a certain degree of heavy metals accumulation in the soil,and Hg content exceeded the standard about 110-1 300 times. Nemerow index and the potential ecological hazard index both indicated that soil was seriously polluted and mainly due to Hg element. The total carcinogenic risks of soil heavy metals ranged from 2. 6×10^-7 to 1. 0×10^-5,and the total noncarcinogenic risks were all less than 1. As element posed a potential carcinogenic risk to adults via oral intake. In autumn,Hg, Cr⁶⁺,Pb,Ni,As and Cu were from industrial sources,while Cd was mainly from natural origin. In spring,Cd and Pb came from transportation,metallurgy and coal burning;Ni,As and Cu came from smelting and metal surface treatment;Hg was from chemical production and fuel combustion. Therefore,emissions from transportation,industrial production and fuel combustion were the main sources of heavy metals. In the future,source reduction and treatment of Hg,As and Cd should be strengthened.