武汉市大气PM_(2.5)中多环芳烃的分布特征及来源

Characteristics and Source Apportionment of Polycyclic Aromatic Hydrocarbons in Atmospheric PM_(2.5) of Wuhan City,China

为研究武汉市大气质量状况,在武汉市ID(工业区)、DT(中心城区)、BG(植物园)设3个采样点,连续1 a同步采集了大气中的PM2.5(细颗粒物)样品,并研究了其中PAHs(多环芳烃)的质量浓度、来源和健康风险.结果表明,武汉市ID、DT、BG采样点的ρ(PAHs)年均值分别为(75.60±28.12)(59.77±22.81)(24.27±9.15)ng/m3,并呈冬季最高、夏季最低的季节性变化趋势.PMF(正定矩阵因子分析)结果显示,ID、DT、BG采样点的PAHs的主要来源分别为燃煤和扬尘(35%和33%)、机动车和扬尘(30%和34%)、机动车和木质燃烧(33%和32%),在ID和DT采样点,扬尘对大气颗粒物中PAHs的贡献都很大,而燃煤和木质燃烧分别是ID和BG采样点PAHs的重要来源,在3个采样点中,机动车对颗粒物中PAHs贡献都较大,尤其是DT和BG采样点,机动车的贡献都超过30%.利用后向轨迹模型分析采样期间武汉市的气团来源,并结合每天的ρ(PAHs)发现,不同聚类气团对应的ρ(PAHs)差异很小,表明区域传输对武汉市PAHs贡献不大.通过武汉市大气颗粒物中PAHs吸入风险评估发现,武汉市PAHs的吸入风险范围在10-7~10-5之间,ID和DT采样点的部分人群的吸入风险稍高于安全范围(10-6以下),有潜在的致癌风险.

Fine particle(PM 2.5)samples were collected simultaneously at three sites in Wuhan City for one year in an industrial area(ID),downtown area(DT),and botanical gardens(BG).The spatiotemporal variations and sources of PAHs were studied by the health risk estimation.The highest annual average concentration of PAHs was found to be(75.60±28.12)ng m 3 at ID site while the lowest one was observed in the BG site with an average of(24.27±9.15)ng m 3.The annual average concentration of PAHs in DT site was(59.77±22.81)ng m 3.Additionally,the concentrations of PAHs exhibited a clear season pattern across all sites,with the highest values occurring during wintertime and the lowest values occurring in summer.Positive matrix factorization(PMF)model revealed that coal combustion and dust(35%and 33%),vehicle exhaust and dust(30%and 34%),vehicle exhaust and wood burning(33%and 32%)were the primary contributors at ID,DT,and BG sites,respectively.Dust had a great impact at ID and DT sites,coal combustion had the largest impact at ID,while wood burning had a great impact at BG.It noteworthy that vehicle exhaust was a major contributor to PAHs at all sites,especially at ID and DT,which contributed more than 30 percent of total PAHs.Backward trajectory analysis accompanied with daily PAHs concentrations was used to investigate the transport pathway of air masses arriving at Wuhan.Given the PAHs concentrations were comparable in different trajectories,it can be concluded that regional transport of air mass has insignificant contributions to the PAHs in Wuhan.In addition,health risk assessment indicated the inhalation risk of PAHs was 10-7-10-5,which was slightly higher than the safe criteria of 10-6,illustrating the potential cancer risk of PAHs inhalation in Wuhan City.