Levels and Sources of PAHs in Air-borne PM2.5 of Hefei City, China.

This work studied the concentrations and sources of polycyclic aromatic hydrocarbons (PAHs) in air-borne particulate matter of Hefei, China. Samples of PM2.5 were collected daily at two sites during May, 2014, and January, 2015. The average daily concentration of PM2.5 was 96.88 µg m-3, which is higher than the 2012 China Ambient Air Quality Standard (GB3095-2012 24-h grade II) of 75 µg m-3. The concentrations of 16 EPA priority polycyclic aromatic hydrocarbons (PAHs) were analyzed by gas chromatography-mass spectrometry. The PM2.5-bound PAH concentrations ranged from 4.92 to 71.00 ng m-3 (mean = 21.34 ng m-3), and exhibited obvious seasonal (31.38 ng m-3 in winter and 14.05 ng m-3 in summer) and spatial variability (27.23 ng m-3at site ME and 18.20 ng m-3 at site MS). Meteorological conditions such as ambient temperature, wind speed and humidity had influences on the concentrations of PAHs. As an index for PAH carcinogenicity, the annual average concentration of benzo(a)pyrene ranged from 0.46 to 2.31 ng m-3, with a mean of 1.15 ng m-3. This mean was lower than the China Ambient Air Quality Standard (GB3095-2012) of 2.5 ng m-3. The diagnostic PAH ratios and principal component analysis (PCA) suggested that combustion of coal and vehicle emissions were the main sources of PAHs in PM2.5.