Quantifying Multiple Reaction Pathways for Ambient Consumed Volatile Organic Compounds Derived from Emission Sources

A novel method was developed to quantify source-specific volatile organic compound (VOC) consumption via multiple reaction pathways, including daytime hydroxyl (•OH) radical reactions and nighttime ozone (O3) and nitrate radical (NO3•) reactions. This approach integrates positive matrix factorization (PMF) with observed and initial-concentration data, enabling simultaneous source apportionment of both emitted and chemically consumed VOCs. The method was applied to hourly VOC measurements made in Linfen, a typical industrial city in China, from April to October 2023. Eight emission sources were resolved and quantified for their contributions to VOC consumption through different reaction pathways. During the study period, the mixed source of industrial emissions and solvent usage was the dominant contributor (31.4%) to consumed VOCs, primarily driven by daytime •OH reactions of alkenes. Natural gas and liquefied petroleum gas usage (15.6%) exhibited higher nighttime consumption due to late-evening emissions from residential and commercial activities. Biogenic emissions contributed 10.8% to the consumed VOCs, mainly driven by daytime •OH and nighttime NO3• reactions. Diesel vehicle emissions, petrochemical industry, coking enterprise emissions, combustion emissions, and gasoline vehicle emissions contributed modestly (∼6-12%). This method advances the understanding of VOC loss mechanisms and provides scientific support for source-specific O3 control strategies.