Dust-Promoted Heterogeneous Transformation of Gas-Phase Oxygenated Organics and Organosulfate Formation

Abstract Although dust is increasingly recognized as an important driver of volatile organic compound (VOC) transformation, a comprehensive understanding of its effects on VOC composition and potential reaction pathways remains lacking. Here, based on field observations in Beijing during April 2022, we systematically investigated oxygenated organic molecule (OOM) distributions and formula-based potential functionalization pathways during the clean, dust, and nondust-dominated pollution periods. Relative to the clean period, the dust period exhibited significantly higher proportions of compounds with high oxygen numbers (O7–O12), together with elevated oxidation states, consistent with enhanced dust-mediated oxidation of organic compounds. Notably, organosulfates showed markedly higher concentrations and proportions during the dust period than during any other period. Potential functional-pair and functionalization-pathway analyses further showed that the S-containing functionalization pathway exhibited the strongest relative enhancement under dust influence. Combined with synchronous measurements of SO2 and inorganic sulfate, these findings highlighted the potentially important role of dust-associated heterogeneous chemical processing in altering OOM composition and promoting the enrichment of sulfur-containing organic species. These results provide a robust framework for investigating complex atmospheric chemical processes and offer new insights into the enrichment of atmospheric organosulfates.