基于GIS的上海市不同功能区土壤重金属污染评价及健康风险评估

Assessment of soil heavy metal pollution and health risk in different functional areas of Shanghai City based on GIS

  • 摘要: 为探明上海市土壤重金属污染水平,对上海市公园、交通、教育、居住、企业和农田6个功能区70个表层土壤样品中的8种重金属浓度进行测定,采用污染指数评价法和健康风险模型对不同功能区的重金属污染水平和人体暴露风险进行评估,并在GIS支持下对土壤重金属空间分布格局进行分析。结果表明:土壤中As、Cd、Cr、Cu、Hg、Ni、Pb、Zn浓度平均值分别为8.03、0.22、62.73、35.52、0.19、33.67、29.54和116.78 mg/kg,Cd、Cu、Hg、Pb和Zn浓度超过上海市土壤背景值,其中Hg、Cd、Pb富集现象明显,浓度高值集中于中心城区;10%采样点呈现重度污染,15.7%采样点为中度污染,污染指数较高区域主要位于市区、西部以及东北部郊区;从不同功能区来看,交通区和企业区分别达重度和中度污染,且Cu、Hg、Cd等污染指数较高。人体健康风险评估结果显示:各功能区总致癌风险依次为企业区>交通区>居住区>农田区>教育区>公园区,其中As为致癌风险的主要贡献元素,高风险区域集中于市区及南部郊区;总非致癌风险依次为居住区>农田区>教育区>交通区>企业区>公园区,As、Pb、Ni是影响非致癌风险的主要污染物,超风险点位位于偏东部区域。研究显示,城市土壤重金属在不同的污染评价方式下,会表现出差异化的空间分布特征,且各功能区相对污染程度存在一定区别。

     

    Abstract: The contents of 8 heavy metals in 70 surface soil samples were determined, which were collected in Shanghai City, including six functional areas of parks, traffic areas, education areas, residential areas, industrial enterprises and farmlands. The pollution status and human exposure risk of heavy metals (HMs) in different functional areas were evaluated by pollution index evaluation method and health risk model. Meanwhile, the spatial distributions of HMs based on the geography information system (GIS) were plotted. The results showed that the average values of As, Cd, Cr, Cu, Hg, Ni, Pb and Zn were 8.03, 0.22, 62.73, 35.52, 0.19, 33.67, 29.54 and 116.78 mg/kg, respectively. The contents of Cd, Cu, Hg, Pb and Zn were higher than the soil background values in Shanghai, the enrichment of Hg, Cd and Pb was obvious and the high values were concentrated in the center city. 10% of the soil samples were heavily polluted and 15.7% of the soil samples were moderately polluted. The areas with higher pollution index were mainly located in the urban areas, and the western and northeastern suburbs as well. From the perspective of different functional areas, the traffic areas and the enterprises were severely and moderately polluted, respectively, with a higher pollution index of Cu, Hg and Cd. Human health risk assessment results showed that the descending order of total carcinogenic risk in different functional areas was as follows: enterprises > traffic areas > residential areas > farmlands > education areas > parks, and As contributed the most to carcinogenic risk. High risk areas were concentrated in urban and the southern suburb. The total noncarcinogenic risks were found to be in descending order of residential areas > farmlands > education areas > traffic areas > enterprises > parks. As, Pb and Ni were the main pollutants affecting noncarcinogenic risk. The sampling sites exceeding the acceptable level were located in the eastern area. The study showed that under different assessment methods, heavy metals in urban soils displayed differentiated spatial distribution characteristics, with certain differences in terms of the relative pollution degree in each functional area.

     

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