Significant impact of VOCs emission from coking and coal/biomass combustion on O3 and SOA formation in taiyuan, China

Volatile organic compounds (VOCs) are the significant precursors of ozone (O3) and secondary organic aerosols (SOA) in fine particles (PM2.5). To effectively control O3 and PM2.5 pollution, VOCs were measured in Taiyuan during the prevailing seasons of pollution: summer (July 16 to 29), autumn (October 21 to November 5), and winter (December 26, 2021, to January 4, 2022). The highest total VOC (TVOC) concentrations were observed in winter (30.62 ± 14.81 ppbv), followed by autumn (25.98 ± 12.83 ppbv) and summer (11.43 ± 8.01 ppbv). Alkanes and alkenes were the dominant species, which together accounted for 78.35%–85.35% of TVOC concentration during the observation period. The ozone formation potential (OFP) and secondary organic aerosol production potential (SOAP) were used to estimate the contribution of VOC species and sources to O3 and SOA production. Alkenes were the dominant contributor to OFP, accounting for 71.88%–80.82%, while aromatics were the primary contributor to SOAP, accounting for 92.66%–96.14%. Based on the positive matrix factorization (PMF) model results, coking sources (21.89%) and coal/biomass combustion (22.86%) were not only the major VOC sources during the observation, but also contributed significantly to OFP (64.16%–81.38%) and SOAP (57.09%–75.28%), respectively. According to the potential source area of TVOC, and the VOCs, OFP and SOAP concentration of each source under different trajectories, VOC contributions were increasingly coming from the coking sources and coal/biomass combustion in local and southwest of Taiyuan. Consequently, it is essential to control the VOC emissions from coking sources and coal/biomass combustion in local and southwest regions to alleviate PM2.5 and O3 pollution in Taiyuan.