Molecular Composition of Anthropogenic Oxygenated Organic Molecules and Their Contribution to Organic Aerosol in a Coastal City.

Organic aerosols (OA) have gained attention as a substantial component of atmospheric aerosols owing to their impact on atmospheric visibility, climate, and human health. Although oxygenated organic molecules (OOMs) are essential contributors to OA formation, the sources, transformations, and fates of the OOMs are not fully understood. Herein, anthropogenic OOMs (AOOMs), anthropogenic volatile organic compounds (AVOCs), and OA were concurrently measured in Xiamen, a coastal city in southeastern China. Our results show that the AOOMs exhibited a high nitrogen content (76%) and a low oxidation degree. Strong photochemical processes of aromatic VOCs were the predominant sources of AOOMs. Also, NO concentrations and the occurrence of multigeneration OH radical oxidations were the critical factors that might influence the formation of AOOMs. Finally, the newly developed aerosol dynamic model's results show that more than 35% of the OA mass growth rate is attributed to the gas-particle partitioning of AOOMs. Further sensitivity testing demonstrates that the contribution of AOOMs to OA growth is significantly enhanced during high-particulate-concentration periods, especially under low-temperature conditions. This study emphasizes the vital role of photochemically produced AOOMs derived from AVOCs in OA growth in a coastal urban atmosphere.