北京市PM_(2.5)载带重金属污染特征、来源及健康风险变化与政策效果评估

Characteristics,Sources,and Health Risk Changes of Heavy Metal Pollution Carried by PM_(2.5) in Beijing and Evaluation of Policy Effectiveness

为评估北京地区大气污染防控相关措施的效果,通过对北京城区4年逐日PM_(2.5)采样(n=934),测定了13种金属元素,其中包括7种重金属元素[As、Cd、Co、Cr(Ⅵ)、Ni、Pb和V].分析了各金属浓度水平的年际变化和采暖季与非采暖季的差异,利用正定矩阵因子分解(PMF)模型进行定量源解析,并采用健康风险评价方法对其中6种金属的健康风险进行评估.结果表明,除Cr(Ⅵ)和Ni等少数金属元素在个别年份存在浓度升高的现象,各元素浓度整体上呈现下降的趋势;V、Co、Pb和Mn等10种金属的采暖季浓度显著高于非采暖季(P<0.05).北京市的大气重金属污染源主要有5类:扬尘源、交通源、燃煤源、工业源和燃料油燃烧源,其中燃煤源的占比整体上呈现下降的趋势.各金属的HQ值均小于1,不存在非致癌健康风险;Ni和Cd的致癌风险可忽略,而各年份的As、Co和Cr(Ⅵ)的R值均介于10^(-6)和10^(-4)之间,具有一定的致癌风险.大气浓度、源和健康风险的年际变化趋势表明,北京地区大气污染防控的相关措施取得了积极的成效.

To evaluate the effectiveness of air pollution prevention and control measures in Beijing,this study measured the content of 13 metal elements,including seven heavy metal elements[As,Cd,Co,Cr(Ⅵ),Ni,Pb,and V],through daily PM_(2.5) sampling(n=934)in the urban area of Beijing for four years.We analyzed the interannual changes in the concentration levels of various metals and the differences between heating and non-heating seasons,used a positive definite matrix factorization(PMF)model for quantitative source analysis,and used health risk assessment methods to evaluate the health risks of six metals.The results showed that,except for a few metal elements such as Cr(Ⅵ) and Ni,which showed an increase in concentration in individual years,the overall concentration of each element showed a downward trend.The concentrations of ten metals,including V,Co,Pb,and Mn,during the heating season were significantly higher than those during the non-heating season(P<0.05).There were five main types of atmospheric heavy metal pollution sources in Beijing:dust sources,transportation sources,coal sources,industrial sources,and fuel oil combustion sources.Among them,the proportion of coal sources was generally decreasing.The HQ values of each metal were all less than 1,indicating no non-carcinogenic health risk.The carcinogenic risk of Ni and Cd could be ignored,while the R values of As,Co,and Cr(Ⅵ) in each year were between 10^(-6) and 10^(-4),indicating a certain carcinogenic risk.The interannual trends in atmospheric concentration,sources,and health risks indicate that the relevant measures for air pollution prevention and control in Beijing have achieved positive results.