2019年西宁市城区PM2.5中重金属污染特征及健康风险评价

目的 分析西宁市城区PM2.5中重金属的污染水平，并对其健康风险进行评价。方法 2019年每月10-16日在西宁市城区2个监测点采集PM2.5样品，分析其中砷、镉、铬、镍、铅、汞、锰7种重金属的含量和污染特征，用健康风险评价模型对重金属进行呼吸暴露健康风险评价。结果 2019年1月至12月西宁市城区2个监测点PM2.5中7种重金属元素的年均浓度范围为2.50×10-8～3.38×10-5 mg/m³，由高到低依次为铅>锰>砷>铬>镍>镉>汞，2个监测点PM2. 5中铅、镉、汞、砷的年均浓度低于GB3095-2012《环境空气质量标准》标准限值,富集因子均小于10。PM2. 5中重金属对人群的超额危险度为6.73×10-13～1.40×10-7，致癌金属的超额危险度由高到低依次为铬>砷>镉>镍，非致癌金属的超额危险度依次为铅>锰>汞，砷、镉、铬、镍的终生致癌超额危险度均低于人群可接受的危险度水平（10-6）。结论 西宁市城区PM2. 5中重金属主要来自自然源，其中铬对人体健康的年均超额危险度较高，应密切关注。

Heavy metals pollution characteristics and health risk assessment of PM2.5, Xining, 2019

Objective To analyze the distribution characteristics and source of heavy metals in ambient PM2.5, and to assess health risk assessment in Xining. WTHZ]Methods Samples of PM2.5 were collected in communities Chengbei and Chengdong of Xining district from 10 to 16 of each month in 2019. The content and distribution characteristics were determined for seven heavy metals (As, Sb, Cr, Ni, Pb, Hg and Mn) in PM2.5, the pollution sources of which were identified based on enrichment factors(EF), inhalation exposure to which was estimated for the risk assessment recommended by US EPA. WTHZ]Results The annual average concentration of seven heavy metals in PM2.5 were 2.50×10-8-3.38×10-5mg/m3, with the order of carcinogenic metals ranked as Pb>Mn>As>Cr>Ni>Sb>Hg. The annual average concentrations of seven heavy metals in two monitoring sites were lower than the limit of grade ruled by GB3095-2012 Ambient Air Quality Standards. The enrichment factor of seven heavy metals were lower than 10. The hazard indexes of seven heavy metals in PM2.5 were 6.73×10-13-1.40×10-7, with the order of carcinogenic metalsranked as Cr>As>Cd>Ni, the order of non-carcinogenic metalsranked as Pb>Mn>Hg. The carcinogenic hazard indexes of As, Cr, Cd and Ni were lower than the risk threshold level (10-6).WTHZ]Conclusion Heavy metals in ambient PM2.5 in Xining mainly come from natural pollution, and Cr have higher potential health riskthan other heavy metals.