Pollution characteristics and source identification of polycyclic aromatic hydrocarbons in airborne particulates of Beijing-Tianjin-Hebei Region, China

PM2.5 and PM10 were synchronously collected in the ambient air of Beijing, Tianjin and Shijiazhuang City in four seasons of 2013. The samples were first pretreated by ultrasonic extraction with acetonitrile, and then sixteen polycyclic aromatic hydrocarbons(PAHs) were analyzed by ultrahigh-pressure liquid chromatography. The variation of total PAHs concentration was 6.3~251.4ng/m3 and 7.0~285.5ng/m3 in PM2.5 and PM10 of Beijing-Tianjin-Hebei Region, respectively. It was found that the degree of seasonal variation of PAHs pollution was as following: winterspringautumnsummer, and the degree of spatial variation of PAHs pollution was as following: ShijiazhuangBeijingTianjin. PAHs were mainly composed of 4, 5and 6-ring PAHs with the percentage of 25.0%~45.1%, 31.7%~40.1% and 15.1%~28.2%, while the sum percentage of 2and 3-ring PAHs was below 10.3%. Compared with non-heating season, the percentage of 4-ring PAHs increased in heating season, while it was obviously deceased for 5and 6-ring PAHs. PAH diagnostic ratios showed that PAHs sources varied with season, indicating that coal burning and vehicular emission were the two main emission sources of PAHs sources. Coal burning played an important role in heating season, and vehicular emission was the main emission source in non-heating season.