汾渭平原典型城乡PM_2.5中多环芳烃特征与健康风险

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, PM_2.5 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 PM_2.5 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 PM_2.5 in heavy polluted weather in Xi'an and Longxian were 243.78 μg/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.