西安市地表灰尘中重金属污染水平与健康风险评价

在西安市三环内采集58个地表灰尘样品,分析了其中重金属含量,利用单因子污染指数法和污染负荷指数法对西安市地表灰尘中重金属污染进行了评价,应用美国环境保护部(US EPA)人体暴露风险评价模型对人群暴露地表灰尘中重金属的健康风险进行了分析。结果表明,地表灰尘中Zn、Pb、Cu、Cr、Ni、As、Co和Mn的平均含量分别为231.0、145.4、59.4、213.0、48.7、9.8、12.6和417.0 mg kg~(-1),其中Zn、Pb、Cu、Cr和Ni的含量是陕西省土壤元素背景值的1.7~6.8倍。地表灰尘中Zn、Cr和Pb达到了重度污染,Cu处于中度污染,Ni、Co、As和Mn为轻度或无污染。人群暴露地表灰尘中重金属的主要途径是手-口直接摄入,且儿童大于成人。西安市及其不同功能区地表灰尘中重金属的非致癌风险均低于风险阈值,8种重金属不存在明显非致癌危害。Cr、Co、As和Ni的致癌风险在可接受范围内。

Assessment of Pollution Level and Health Risks of Heavy Metals in Surface Dust in Xi'an City,NW China

Surface dust samples were collected from fifty eight sampling sites in Xi'an City,NW China.The contents of heavy metal in all samples were analyzed.Single pollution index and pollution load index were used to evaluate the pollution level of heavy metals and the health risk of human exposure to heavy metals was assessed by the health risk assessment models recommended by the United States Environmental Production Agency (US EPA).The results showed that the average concentrations of Zn,Pb,Cu,Cr,Ni,As,Co and Mn were 231.0,145.4,59.4,213.0,48.7,9.8,12.6 and 417.0 mg kg-1,respectively.Among the studies on heavy metals,the mean values of Zn,Pb,Cu,Cr and Ni were all higher than soil element background values in Shaanxi,which were more than 1.7-6.8 times.In the surface dust,Zn,Cr and Pb were up to severe pollution,Cu belonged to moderate pollution,Ni,Co,As and Mn presented slight or no pollution.The main pathway of human exposure to heavy metals from surface dust was the direct ingestion via hand and mouth activities.Meanwhile,the exposure dose of children was higher than that of adults.The Non-cancer risk of human exposure to heavy metals from surface dust were lower than the risk threshold in Xi'an City and its different areas,and the studied eight heavy metals had no significant non-carcinogenic hazard to human health.The cancer risk of Cr,Co,As and Ni was in the acceptable range.