Molecular characteristics, sources, and formation pathways of organosulfur compounds in ambient aerosol in Guangzhou, South China

Abstract. Organosulfur compounds (OrgSs), especially organosulfates, have been widely reported to be present in large quantities particulate organic matter found various atmospheric environments. Despite hundreds of organosulfates and their formation mechanisms being previously identified, a fraction OrgSs remain unexplained at the molecular level, better understanding pathways critical environmental parameters is required explain variations concentrations. In this study, abundance composition fine samples collected Guangzhou were reported. The results revealed that ratio annual average mass sulfur total was 33 ± 12 %, had positive correlations with SO2 (r=0.37, p<0.05) oxidant (NOx + O3, r=0.40, p<0.01). A Fourier transform ion cyclotron resonance spectrometry (FT-ICR MS) analysis more than 80 % sulfur-containing formulas detected elemental o/(4s+3n)?1, indicating they largely form oxidized or nitrooxy organosulfates. Many tentatively identified as having biogenic anthropogenic origins also freshly emitted aerosols derived from combustion sources. indicated through an epoxide intermediate pathway could account for up 46 upper bound estimation, levels 20 variation sulfur. our dataset FT-ICR MS suggested relative humidity, oxidation volatile via ozonolysis, NOx-related organosulfate major reasons OrgSs, possibly highlighting importance acid-catalyzed ring-opening epoxides, processes, heterogeneous reactions involving either uptake into additional unrecognized OrgSs.