成都市PM2.5中有毒重金属污染特征及健康风险评价

2009年4月至2010年1月在成都市城区采集PM2.5样品.采用X射线荧光光谱法分析20种元素,并重点分析As、Cd、Cr、Mn、Ni、Pb和Sb 7种有毒重金属元素.采用富集因子法、地累积指数法、相关性分析法和美国环保局暴露模型分别讨论了有毒重金属的污染特征、来源和健康风险.结果表明:成都市PM2.5中有毒重金属浓度处于较高水平,分别是:As(40.5±30.3),Cd(9.5±13.2),Cr(17.9±10.5)、Mn(137.6±84.3),Ni(5.1±4.1),Pb(320.5±186.0)和Sb(11.0±16.0)ng/m3.As严重超标,Cd和Pb也有超标现象.多数元素均在冬季达到最大值,夏季达到最小值.Cr、Mn、Ni污染程度较低,属于轻微污染,As、Cd、Pb、Sb的污染程度极高.PM2.5中有毒重金属主要来源于土壤尘及其扬尘,机动车排放和煤燃烧,冶金及机械制造和刹车磨损.Mn对儿童、成人均产生较严重的非致癌健康风险,分别为6.01、2.59、2.46,As、Cd、Cr、Ni、Pb、Sb的非致癌风险值均小于1,健康影响较小.As、Cr对人体有致癌健康风险.

Contamination characteristics and health risk assessment of toxic heavy metals in PM25 in Chengdu

To study the pollution characteristics, sources and human health risks of toxic heavy metals in PM2.5 in Chengdu, the samples were collected from April 2009 to January 2010, in which 20 elements were analyzed by the XRF. The Enrichment Factor (EF) and Geo-accumulation Index methods were used to investigate the pollution levels of 7 toxic heavy metals (As, Cd, Cr, Mn, Ni, Pb and Sb); the correlation analysis (CA) was applied to study their sources; the health risk assessment model of US EPA was exploited. The results indicated that the concentrations of toxic heavy metals in PM2.5 were at a high level as follows: As (40.5±30.3), Cd (9.5±13.2), Cr (17.9±10.5), Mn (137.6±84.3), Ni (5.1±4.1), Pb (320.5±186.0) and Sb (11.0±16.0) ng/m3. The concentrations of As in all samples significantly exceeded the 6.0 ng/m3 standard. Concentrations of Cd and Pb in some samples also exceeded the 5.0 ng/m3 and 500.0 ng/m3 standards. Most of the elements reached their highest concentrations in winter and lowest in summer. It was demonstrated that the enrichment factors of Cr, Mn, Ni were lower than those of As, Cd, Pb, Sb indicating moderate pollution. The sources of toxic heavy metals in PM2.5 included soil dust, vehicle emission and coal combustion, metallurgy and machinery manufacturing and brake wear. Mn was found to cause highly non-cancer risks to children and adults which values were estimated as 6.01, 2.59 and 2.46, respectively. The non-cancer risks of As, Cd, Cr, Ni, Pb, Sb were less than 1, indicating relatively small impacts. The high pollution levels of As, Cr were found to be with cancer-risks.