汾渭平原典型城乡PM2.5中多环芳烃特征与健康风险

为查明汾渭平原典型城乡地区重度污染天气PM_2.5中多环芳烃（PAHs）污染特征及其人群健康效应,本文于2018—2019年冬季分别选取西安和陇县作为城乡对比参照点,采集了重度污染天气PM_2.5颗粒态气溶胶样品。利用气相色谱—质谱联用仪（GC-MS）检测样品中具有“三致效应”的15种PAHs含量及组分特征,使用特征比值法及主成分法进行PAHs源解析,并分析了气象因素对PAHs质量浓度的可能影响,通过对苯并芘（BaP）等效毒性浓度和终生超额致癌风险度（ILCR）的计算,对人群健康风险进行评估。结果表明：西安与陇县在重度污染天气条件下PM_2.5中15种PAHs总平均质量浓度分别为243.78 ng/m³、609.39 ng/m³,其中4~6环PAHs占比最高;且PAHs浓度与气温、气压及风速呈显著负相关,与相对湿度则无明显相关性。西安PAHs污染主要来自燃烧源与交通排放源,而煤炭及生物质燃烧是造成陇县PAHs质量浓度偏高的主要原因。健康风险评估结果显示,重污染天气下陇县人群通过呼吸引发的致癌风险要高于西安,女性致癌风险高于男性,成人致癌风险高于儿童,且两地区成人ILCR值均超过风险阈值,存在潜在致癌风险,儿童则无明显致癌风险。

Characteristics and health risk of polycyclic aromatic hydrocarbons in PM2.5 in the typical urban and rural areas of the Fenwei Plain

In order to investigate the pollution characteristics and human health risk of polycyclic aromatic hydrocarbons(PAHs) in heavy polluted weather in the typical urban and rural areas of the Fenwei Plain, PM2.5 samples were collected from Xi’an and Longxian in the winter of 2018-2019. The mass concentrations of 15 PAHs characterized by carcinogenicity,mutagenicity and teratogenicity in the samples were determined using gas chromatograph-mass spectrometer(GC-MS). The source of PAHs was analyzed by the diagnostic ratio and principal component method and the possible relation between PAHs mass concentrations and meteorological parameters was elaborated. In addition, human health risk caused by PAHs in PM2.5 was assessed through the equivalent carcinogenic concentration of benzo(a)pyrene(BaP)and incremental lifetime cancer risk(ILCR). The results showed that the average mass concentrations of PAHs in PM2.5 in heavy polluted weather in Xi’an and Longxian were 243.78μg/m³ and 609.39 μg/m³, respectively, and 4-6 rings of PAHs had the highest proportion of the total. Moreover, PAHs concentrations had a significant negative correlation with atmospheric temperature, atmospheric pressure and wind speed, but irrelevant with relative humidity.Combustion source and automobile exhaust emissions were the main factors contributing to the high concentration of PAHs in Xi’an, while coal and biomass burning were the main factors contributing most to PAHs of Longxian. Health risk assessment results revealed that the carcinogenic risk caused by breathing during heavy polluted weather was higher in Longxian than that in Xi’an and the cancer risk for females was higher than that for males, and the cancer risk for adults was higher than that for children. In addition, the ILCR value of adults in both urban and rural areas exceeded the risk threshold recommended by EPA and had potential carcinogenic risks, while there was no obvious carcinogenic risk for children.