[Concentration, Water-Soluble Ionic and Polycyclic Aromatic Hydrocarbons Composition and Sources of PM_2.5 During...

Atmospheric PM_2.5 samples were collected in Hongshan district, Wuhan from June 12^th to July 22^th, 2014. This study analyzed the characteristics and chemical composition of PM_2.5, 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 PM_2.5 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 PM_2.5 correlated significantly with wind speed in meteorological parameters, when the wind speed increased, the concentration of PM_2.5 showed a trend of decline. The water-soluble ionic components of PM_2.5 were SO₄^2-, NO₃^-, NH₄⁺ and K⁺ which accounted for 40.67%, and the aerosol partial acid. The influencing factors of formation process of SO₄^2- were different from those of NO₃^-, and NH₄HSO₄ and (NH₄)₂SO₄ were the main compounds of NH₄⁺ in PM_2.5. The average concentration of PAHs in PM_2.5 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 PM_2.5. 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 (TEQ_BaP) ranged from 0.22 to 11.19 ng·m^-3 (mean, 1.74 ng·m^-3), and the exceeding criteria rate was 7.41%.