SO<sub>2</sub> and NH<sub>3</sub> emissions enhance organosulfur compounds and fine particle formation from the photooxidation of a typical aromatic hydrocarbon

Abstract. Aromatic hydrocarbons can dominate the volatile organic compound budget in urban atmosphere. Among them, 1,2,4-trimethylbenzene (TMB), mainly emitted from solvent use, is one of most important secondary aerosol (SOA) precursors. Although atmospheric SO2 and NH3 levels affect formation, influenced extent their impact detailed driving mechanisms are not well understood. The focus present study to examine chemical compositions formation SOA TMB photooxidation by and/or NH3. Here, we show that emission could considerably enhance particle due SO2-induced sulfate generation acid-catalyzed heterogeneous reactions. Orbitrap mass spectrometry measurements revealed only typical products but also hitherto unidentified organosulfates (OSs) SO2-added experiments. OSs designated as being unknown origin earlier field were detected SOA, indicating might be originated photooxidation. For NH3-involved experiments, results demonstrated a positive correlation between volume number concentrations. effects on composition slight under SO2-free conditions stronger presence SO2. A series multifunctional with carbonyl, alcohols, nitrate functional groups tentatively characterized experiments based infrared spectra analysis. Plausible pathways proposed for phase. volatility distributions products, estimated using parameterization methods, suggested gradually condense onto nucleation particles contribute growth. Our suggest strict control emissions remarkably reduce burden Updating aromatic oxidation mechanism models result more accurate treatment regions considerable SO2, NH3, aromatics emissions.