保定城区地表灰尘污染物分布特征及健康风险评价

以河北省保定市城区为研究区域，采集了保定城区内办公区、商业区、居住区、工业区、交通区和屋顶6个类别共14个采样点的地表灰尘，分析了地表灰尘重金属和营养元素N、P在不同区域的分布特征，并分析了其可能来源.最后，应用重金属健康风险评价模型（Chronic Daily Intake，CDI）对地表灰尘中Cd、Cr、Cu、Pb和Zn 5种重金属进行了健康风险评价.结果表明，城市屋顶灰尘污染物质含量普遍高于其它区域，之后依次是商业区>交通区>工业区>办公区>居住区，Cd(5.10 mg·kg-1)、Cr(470 mg·kg-1)、Pb(997 mg·kg-1)、Zn(1377 mg·kg-1)和P(999 mg·kg-1)的最大值均来自屋顶灰尘，而Cu(867 mg·kg-1)和N(19.40 mg·kg-1) 的最大值则来自商业区的地表灰尘.重金属Cd和Cr具有复合污染特征，来源复杂且多样化；重金属Pb、Zn和Cu的含量在各区域中的变化趋势较一致且显著相关，主要来源于交通排放.Cd的平均致癌风险指数均达到了1.25×10-5，超过了美国EPA 10-6的标准，由此将导致每百万人增加12.5个癌症患者，已对当地居民的身体健康造成了严重的威胁；各种重金属的平均叠加风险度达0.124，重金属摄入为慢性参考剂量的10%左右，不会对居民的身体健康产生较大的非致癌风险.

Pollutant distribution in urban dusts of Baoding and health risk assessment

This study focused on characterization of heavy metals and nutrients in the dust of the city of Baoding, China. Thirty six samples were collected from fourteen sampling points including six land-use types. Most of the sites were impervious ground such as office, commercial, residential, industrial and traffic areas, as well as building roofs. Concentrations of Cd, Cr, Cu, Pb, Zn and organic N and P were measured to investigate their distribution and possible sources. The results showed that the mean concentration of pollutants in the building roofs was generally higher than in other areas, followed by the commercial, traffic, industrial, office and residential areas. In addition, the highest concentrations of Cd (5.10 mg·kg-1), Cr (470 mg·kg-1), Pb (997 mg·kg-1), Zn (1377 mg·kg-1) and P (999 mg·kg-1) were found on the building roofs. However, the highest concentration of Cu (867 mg·kg-1) and N (19.40 mg·kg-1) were found in commercial areas. Cd and Cr had the most complex and varied sources. The concentrations of Pb, Zn and Cu in all areas were more consistent and had significant correlations, indicating they were mainly from traffic emissions. Based on the above data, the CDI (chronic daily intake) model was applied to assess the health risks associated with Cd, Cr, Cu, Pb and Zn in the dust of Baoding. The results showed that the cancer risk index of Cd was 1.25×10-5, which was higher than the soil management standard of the EPA. The high cancer risk indexes indicate a possible increase of approximately 12.5 cancer patients per million people. The non-cancerous average risk index (0.124) of the five heavy metals was less than the standard value, which implied a non-carcinogenic risk to the health of the residents.