武汉市不同功能区土壤重金属污染特征及健康风险评价

Pollution Characteristics and Health Risk Assessment of Heavy Metals in Soil of Different Functional Zones in Wuhan City

以武汉市不同功能区的表层土壤为研究对象,通过荧光光谱分析法测定土壤样品中的重金属含量,采用单因子污染指数和内梅罗综合污染指数评价其重金属污染程度,并结合重金属污染来源,利用健康风险评价模型评价其对人体的健康风险。结果表明,除Pb以外,重金属Cr,Mn,Ni,Zn和V的平均含量均未超过湖北省土壤重金属背景值。单因子污染指数评价结果显示,各功能区Pb为轻度污染,Cr,Mn,Ni,Zn和V处于警戒水平;内梅罗综合污染指数显示,学校绿地污染最为严重,处于中度污染水平。研究还发现,武汉市不同功能区表层土壤重金属的来源存在差异,其中V,Cr,Ni和Mn主要来自于工业排放,Pb和Zn来源于交通源排放,都属人为污染源。各重金属的非致癌风险指数为Cr>Pb>Ni>Zn;致癌元素Cr对成人和儿童的风险指数均高于1×10^-4,说明存在不可接受的致癌风险;Ni的致癌风险指数介于阈值范围(1×10^-6~1×10^-4),处于可接受水平。

Surface soil samples from different functional areas in Wuhan city were collected.The contents of heavy metals in soil were analyzed by X-ray Fluorescence Spectroscope.The heavy metal pollution levels in soil in different functional zones in Wuhan were assessed with single factor pollution index and Nemerow integrated pollution index,and the pollution sources were discriminated by Principal Component Analysis(PCA).The health risk of heavy metals to human was assessed by using US EPA health risk assessment model.The results showed that the average concentrations of heavy metals such as Cr,Mn,Ni,Zn,and V were lower than the background values of soil in Hubei Province except for Pb.Single factor pollution index showed the pollution degree was in the following order:Pb>Ni=Zn>Cr>Mn=V.Pb element in different functional zones was in mild pollution,while Cr,Mn,Ni,Zn,and V were at the alert level.Nemerow integrated pollution index showed that the soils from the green land of campus were most contaminated by heavy metals,and it was in moderate pollution level.The results of PCA showed that the heavy metals in soil of Wuhan city came from different sources.V,Cr,Ni,and Mn were mainly from industrial emissions,while Pb and Zn were originated from traffic emissions,which all were affected by anthropogenic sources.The non-carcinogenic risk index of heavy metals in soil from Wuhan city ranked as follows:Cr>Pb>Ni>Zn.The carcinogenic risk index of Cr for adult and children were both higher than 1×10^-4,indicating an unacceptable risk of cancer;while the values of Ni were below the carcinogenic risk threshold range(1×10^-6~1×10^-4),at an acceptable level.