吴忠市表层土壤重金属污染及其潜在生态风险评价

为查明吴忠市土壤重金属的污染现状及来源,测定了区内100个表层土壤样品中8种重金属Cu、Pb、Ni、Cr、Cd、Zn、As、Hg的含量。对比背景值可知,除Ni外其它重金属均有不同程度的富集,其中Cd富集最严重；采用地累积指数法、潜在生态风险评价法对土壤重金属进行污染程度及风险评价。结果表明吴忠市土壤重金属的环境总体处于无污染,总体生态危害程度处于中等,Cd和Hg是构成生态危害的主要风险因子,吴忠市土壤重金属的潜在生态危害主要是受到城区的生活、生产活动和部分农业用地区域的农耕活动影响。运用多元统计分析对吴忠市土壤重金属来源进行研究,结果表明Cu、Pb、Zn主要来源于交通运输产生的污染；Ni主要受成土母质、地形、气候等自然因素控制,Cr、As为成土母质和农业污染混合来源,Cd主要来源于农业活动造成的污染。

Assessment of Heavy Metal Pollution and its Potential Risk in the Urban Topsoil of Wuzhong, China

In order to determine the pollution state and main sources of heavy metals in the soils of Wuzhong city in northwest of China, 100 topsoil samples were collected and analyzed for Cu, Pb, Ni, Cr, Cd, Zn, As and Hg. Contrasted with local background value, it can be found that various heavy metals were enriched in varying degrees in addition to Ni, while Cd was enriched seriously. The Index of Geoaccumulation and Risk Index were used to estimate the pollution degree and potential risk of heavy metals, for which results indicated that heavy metals in soils of Wuzhong city was generally pollution-free, and the overall degree of potential risk was moderate. The risk index assessment results showed that Cd and Hg were the main factors of ecological risk. The potential risk of heavy metals in Wuzhong city were mainly caused by the living and production activities in urban and rural areas. Meanwhile, the multivariate statistics were applied to explore the sources of those heavy metals in topsoil, for which results indicated that Cu, Pb and Zn were mainly sourced from traffic pollution, Ni was the natural source of soil matrix, Cr and As were sourced from natural of soil matrix and agricultural production activities, As was sourced from natural of soil matrix and industrial pollution, Cd was mainly sourced from agricultural pollution.