Seasonal Variation Characteristics of VOCs and Their Influences on Secondary Pollutants in Yibin, Southwest China

Abstract

Volatile organic compounds (VOCs) have a crucial impact on the formation of ozone and secondary organic aerosols in the near-surface atmosphere. Understanding the composition characteristics and sources of VOCs is necessary for determining effective control policies to mitigate VOCs and related secondary pollutions. We performed on-line measurements of VOC species in typical months of each season in Yibin, a fast-growing city in Sichuan Basin in China, to identify VOC seasonal characteristics, sources, and the potential for secondary pollution formation. The average mixing ratio of VOCs in Yibin was 22.3 ppbv. Five major emission sources were identified through the positive matrix factorization model, namely, gasoline vehicle, diesel vehicle, industrial manufacturing, solvent utilization, regional background, and secondary formation. Aromatics and alkenes played leading roles in the secondary formation of ozone and secondary organic aerosols. Furthermore, m/p-xylene, ethylene, and toluene were identified to be the major reactive species. Future management should consider targeting these compounds when evaluating ozone and aerosol reduction strategies. Vehicle and solvent utilization emission mitigation would be the primary and effective ways to improve air quality in the fast-developing city in this region.