Characterization and source apportionment of volatile organic compounds in urban and suburban Tianjin, China

Tianjin is the third largest megacity and the fastest growth area in China, and consequently faces the problems of surface ozone and haze episodes. This study measures and characterizes volatile organic compounds (VOCs), which are ozone precursors, to identify their possible sources and evaluate their contribution to ozone formation in urban and suburban Tianjin, China during the HaChi (Haze in China) summer campaign in 2009. A total of 107 species of ambient VOCs were detected, and the average concentrations of VOCs at urban and suburban sites were 92 and 174 ppbv, respectively. Of those, 51 species of VOCs were extracted to analyze the possible VOC sources using positive matrix factorization. The identified sources of VOCs were significantly related to vehicular activities, which specifically contributed 60% to urban and 42% to suburban VOCs loadings in Tianjin. Industrial emission was the second most prominent source of ambient VOCs in both urban and suburban areas, although the contribution of industry in the suburban area (36%) was much higher than that at the urban area (16%). We conclude that controlling vehicle emissions should be a top priority for VOC reduction, and that fast industrialization and urbanization causes air pollution to be more complex due to the combined emission of VOCs from industry and daily life, especially in suburban areas.