Characteristics and sources of volatile organic compounds and their impacts on ozone formation in a coastal city of southeastern China

Abstract

Ozone (O₃) pollution is a severe environmental issue, highlighting the critical role of volatile organic compounds (VOCs), a precursor of O₃, in urban air pollution control. In this study, we analyzed continuous hourly measurements of VOCs and O₃ in 2022 in a coastal city of southeast China, Fuzhou, to characterize VOC seasonal variations and sources, as well as their contributions to O₃ formation in the region. The results show that the annual mean concentrations of VOCs is 18.3 ± 10.4 ppbv, which is much lower than cities in northern and central China. According to the emission ratios, VOCs in Fuzhou are significantly impacted by liquefied petroleum gas and natural gas (LPG/NG) (30.6 %), but are less affected by vehicle exhaust emissions (20.9 %) than those in Chinese megacities, because of the consumption of clean energy increased to 30 % in Fuzhou. Seasonally, VOC sources exhibit a higher proportion of the solvent source in summer, driven by increased production from the agricultural fertilizers, integrated circuits, and beverage production. In autumn, the elevated industrial VOC emissions, including cement and petrochemical industries, contribute a high proportion of 23.1 % to the total VOC. The proportion of LPG/LPG source in winter is higher than in other seasons, mainly due to the growth in VOCs emissions and the increase in emissions from burning sources. The LPG/NG and vehicle exhaust source are the primary contributors to O₃ formation potential (OFP) throughout the year, except in summer when vehicle and solvent emissions become the leading contributors to OFP. Finally, we identified multiple elevated O₃ events associated with increases in VOCs. We conservatively estimate that on average of these events, a 59.4 % increase in VOCs and a 37.3 % increase in NO₂ could lead to a rise of 38.5 % in O₃ concentrations on the following day under comparable local meteorological conditions. This study provides policymakers with new scientific references to formulate effective VOC control measures for curbing O₃ pollution in southeastern China.