Atmospheric PM2.5 samples were collected in Hongshan district, Wuhan from June 12th to July 22th, 2014. This study analyzed the characteristics and chemical composition of PM2.5, and the concentrations of Polycyclic Aromatic Hydrocarbons (PAHs) were analyzed by gas chromatography-mass spectrometry (GC-MS), to discuss the pollution sources and formation mechanism. The results indicated the total concentrations of PM2.5 ranged from 36.41 to 220.02 μg·m-3, with the mean of 97.38 μg·m-3. and the exceeding criteria rate was 59.26%. Furthermore, the concentration of PM2.5 correlated significantly with wind speed in meteorological parameters, when the wind speed increased, the concentration of PM2.5 showed a trend of decline. The water-soluble ionic components of PM2.5 were SO42-, NO3-, NH4+ and K+ which accounted for 40.67%, and the aerosol partial acid. The influencing factors of formation process of SO42- were different from those of NO3-, and NH4HSO4 and (NH4)2SO4 were the main compounds of NH4+ in PM2.5. The average concentration of PAHs in PM2.5 was 11.30 ng·m-3, and the dominant compounds were 4-6 ring PAHs. Industrial waste gas and vehicle emissions were the sources of PM2.5. The various sources of the PAHs had contribution of 83.90% from vehicle emission and combustion of coal, 10.17% from petroleum sources, and 5.08% from coking emission. The concentration of toxic benzo[a]pyrene equivalent (TEQBaP) ranged from 0.22 to 11.19 ng·m-3 (mean, 1.74 ng·m-3), and the exceeding criteria rate was 7.41%.
Keywords: Hongshan District of Wuhan; PAHs; PM2.5; sources; water soluble ion.