再开发利用工业场地土壤重金属含量分布及生态风险

Distribution and Ecological Risk of Heavy Metals in the Soil of Redevelopment Industrial Sites

选取上海市普陀、宝山、闵行和嘉定这4个区内50块典型场地,测定1847个不同垂直剖面深度土壤样品中重金属Hg、Cd、Pb、Cr和As含量,并通过内梅罗综合指数法和潜在生态风险指数法进行评价.从总体上看,Hg、Cd、Pb、Cr和As在表层土壤样品中的平均含量分别为0.33、0.37、74.55、69.23和9.05 mg·kg^-1,其中Hg、Cd和Pb均超过上海市土壤背景值,分别是背景值的2.75、2.85和2.93倍;5种重金属含量随着土壤垂直剖面深度的增加逐渐降低,深层和饱和带土壤重金属含量接近或低于背景值水平,这表明人类活动扰动影响主要局限于表层.普陀区表层土壤中Hg、Cd和Pb的累积程度最为明显,平均含量是背景值的4.25、4.85和3.09倍;宝山区的Hg和Pb平均含量则为背景值的4.92和6.43倍.宝山区和普陀区的内梅罗综合指数分别为3.70和3.20,属重污染等级;普陀区潜在生态风险指数最高为398.59,具有很强风险,宝山潜在生态风险指数为303.08,具较强风险.闵行和嘉定土壤重金属含量和生态风险水平相对较低.综上,再开发利用工业场地土壤重金属污染受企业生产年限、行业类型及历史管理水平等因素的综合影响,工业发展较早的普陀和宝山土壤重金属累积程度明显高于闵行和嘉定.工业场地土壤中重金属Hg、Cd和Pb的污染值得关注.

Fifty typical redevelopment industrial sites in the Putuo,Baoshan,Minhang,and Jiangding districts of Shanghai were chosen to evaluate the ecological risk of heavy metals in the soil.The contents of heavy metal(Hg,Cd,Pb,Cr,and As)in 1847 soil samples,taken from vertical sections,were determined,and their risks were evaluated using the Nemero composite index and Hakanson potential ecological risk index.The average contents of Hg,Cd,Pb,Cr,and As in topsoil samples were 0.33,0.37,74.55,69.23,and 9.05 mg·kg^-1,respectively.The contents of Hg,Cd,and Pb exceeded the soil background values of Shanghai,which were 2.75,2.85,and 2.93 times the background values,respectively.The contents of five heavy metals in soil decreased gradually with increased depth.The contents of heavy metals in deep and saturated soils were close to,or below,the background values,indicating that the anthropic activity disturbance was mainly confined to the topsoil.The accumulation of Hg,Cd,and Pb was the most obvious in Putuo topsoil,with the average contents being 4.25,4.85,and 3.09 times the background values,respectively.The average contents of Hg and Pb in Baoshan were 4.92 and 6.43 times the background values,respectively.The Nemero Composite Index of Baoshan and Putuo districts were 3.70 and 3.20,respectively,representing heavy pollution level at these sites.The Hakanson potential ecological risk indexes of the Putuo and Baoshang districts were 398.59 and 303.08,respectively,with considerable ecological risk levels.The content and ecological risk of heavy metals at the Minhang and Jiading sites were relatively low.In summary,the pollution of heavy metal in the redeveloped industrial sites is influenced by the operating time,industry type,and past management level of the enterprises.The heavy metal accumulation in the Putuo and Baoshan districts,whose industries developed earlier,were higher than those in the Minhang and Jiading districts.The pollution of heavy metal Hg,Cd,and Pb in soil should be a focus of future work.