芜湖市区地表灰尘中重金属粒径效应及其健康风险评价

对芜湖市区高新技术开发区、中心城区、经济技术开发区等21个地表灰尘样品中重金属含量的粒径分布效应及其细粒径灰尘重金属健康风险进行分析。结果表明:芜湖市区地表灰尘中9种重金属含量的变化范围较大,并存在不同程度的污染,其中Cd的平均值是土壤背景值的30倍以上。Zn、Cd、Pb、Co、Ni、Cu含量在经济技术开发区最大,Mn在高新技术开发区最大,Cr、V在中心城区最大。不同重金属的粒径分布效应差异较大,大部分重金属在160~200目粒径段的含量最高。重金属主要富集在75μm粒径级别上,富集比例约为50%,大小顺序依次为:CdCuZnCrNiPbCoVMn。手-口摄入途径是儿童对细粒径地表灰尘重金属暴露的主要途径。不同重金属非致癌风险大小依次为:PbCrMnVCuCdCoNiZn,均不构成明显的风险,但经济技术开发区的各重金属叠加风险指数达1.266,存在非致癌风险。Cr、Cd、Co和Ni致癌风险均低于风险阈值,不会对人体造成健康危害。

Particle size distribution and health risk assessment of heavy metals in surface dust of Wuhu urban area

A total of 21 surface dust samples were collected in High-tech Development Zone, Center City, Economic and Technological Development Zone in Wuhu urban area. Concentrations of Zn, Cd, Pb, Co, Ni, Mn, Cr, V and Cu on different particle sizes were analyzed by ICP-OES in this paper. Research into the exposure and health risk assessment of heavy metals on the fine size dust was carried out by using USEPA health risk assessment model. Results showed that: the range of the change for the nine heavy metals in surface dust in Wuhu urban area was quite large and there exit different degrees of pollution, in which the average concentration of Cd was over 30 times of the soil background value. As far as the concentration was concerned, Economic and Technological Development Zone witnessed the highest concentrations of Zn, Cd, Pb, Co, Ni and Cu, High-tech Development Zone found the highest concentration of Mn, and Central City saw the highest concentrations of Cr and V. Particle size distribution had a significant influence on pollutant concentrations. Some 160-200 and >200 mesh sizes were at the main pollution level. Heavy metals were mainly enriched in the >200 mesh particle size and the enrichment ratio was about 50% in the order of Cd>Cu>Zn>Cr>Ni>Pb>Co>V>Mn. Human exposure risk assessment showed that hand-mouth intake was the main way for childrens' heavy metals exposure to fine particle size of surface dust, followed by skin absorption, and the exposure to heavy metals through air inhalation was the smallest. The order of non-cancerous hazard indexes of metals was Pb>Cr>Mn>V>Cu>Cd>Co>Ni>Zn. There were no significant risks, but the superposition of all the heavy metals on childrens' degree of non-cancer risk was up to 0.753, so we should pay more attention to cumulative pollution and potential risks. The non-cancerous risk indexes of the nine heavy metals from the three ways was 1.266 in Economic and Technological Development Zone, showing a potential non-cancerous risk to the health of the children. Cancer risks of Cr, Cd, Co and Ni were lower than their threshold values, indicating a lower risk of cancer and without health hazards.