Characterization of PM2.5-bound PAHs and carbonaceous aerosols during three-month severe haze episode in Shanghai, China: Chemical composition, source apportionment and long-range transportation

To investigate the characterization of PM2.5-bound polycyclic aromatic hydrocarbons (PAHs) and carbonaceous aerosols as well as the regulation of formation and transition in the haze episode, daily PM2.5 samples (from Nov.2017 to Feb. 2018) were collected from an industrialized district in Shanghai, China. The average concentrations of PAHs and element carbon (EC) were 10.4 ± 4.55 ng/m3 and 8.08 ± 2.97 μg/m3 during haze episodes, which were 1.33 and 2.27 times higher than those during clear period, respectively. Secondary organic carbon (SOC) consisting of 52.2% organic carbon (OC) were the main chemical constitution of the aerosols resulting in heavy haze in Shanghai. Spearman correlation coefficient indicated that low temperature and relative humidity were the crucial factors attributing to the severe haze events. The Positive Matrix Factorization (PMF) model indicated that vehicle emissions (33.2%) were the predominant sources during haze period, followed by coal and biomass combustion (32.5%), coking (25.5%) and petroleum spill and leakages (8.87%). Zhejiang, Anhui and Jiangsu provinces were identified as potential major source areas of PAHs and EC according to potential source contribution function (PSCF) and concentration weighted trajectory (CWT) models. This study made contributions to target the prevention of pollutants in terms of severe haze event and long-range transportation as well as putting forward control measures and policies.