[Seasonal Pollution Characteristics and Source Apportionment of Atmospheric VOCs in Central Urban Area of Chongqing].

Abstract

The long-term seasonal pollution characteristics, environmental effects, and sources of atmospheric volatile organic compounds （VOCs） were investigated based on the one-year （06/2021-05/2022） online observation data of VOCs in the central urban area of Chongqing. The results showed that during the observation period, the mean value of φ（VOCs） was 31.5×10^-9, of which alkane accounted for the highest proportion （39.6%）, followed by oxygenated VOCs （OVOCs） （15.6%）, halogenated hydrocarbons （13.9%）, aromatic hydrocarbons （11.6%）, olefin （10.5%）, and alkyne （8.3%）. In terms of time, the volume fraction changed to winter （35.7×10^-9） > autumn （32.5×10^-9） > summer （31.3×10^-9） > spring （27.6×10^-9）. In summer, the highest contribution of aromatic hydrocarbons to ozone generation was observed in 1,2,4-tritylene, toluene, and m/p-xylene species with higher ozone generation potential （OFP）. In winter, the contribution of aromatic hydrocarbons to the formation potential of secondary organic aerosols （SOA） was as high as 96%, and toluene and m/p-xylene were the main contributing species to the formation potential of SOA. The main sources of VOCs in summer were motor vehicle emissions （30.9%）, industrial emissions （21.2%）, and solvent use sources （18.6%）, and the main sources in winter were motor vehicle exhaust （35.8%）, combustion sources （30.9%）, and industrial sources （20.6%）. The contribution of combustion sources to VOCs in winter （30.9%） was significantly higher than that in summer （17.4%）.