Abstract
The presence of organic sulfur compounds (OSs) at the water surface, acting as organic surfactants, may influence the air-water interaction and contribute to new particle formation in the atmosphere. However, the impact of ubiquitous anthropogenic pollutant emissions, such as SO2 and polycyclic aromatic hydrocarbons (PAHs) on the formation of OSs at the air-water interface still remains unknown. Here, we observe large amounts of OSs formation in presence of SO2, upon irradiation of aqueous solutions containing typical PAHs such as pyrene (PYR), fluoranthene (FLA), and phenanthrene (PHE), as well as dimethylsulfoxide (DMSO). We observe rapid formation of several gaseous OSs from light-induced heterogeneous reactions of SO2 with either DMSO or a mixture of PAHs/DMSO, and some of these OSs (e.g. methanesulfonic acid) are well established secondary organic aerosol (SOA) precursors. A myriad of OSs and unsaturated compounds are produced and detected in the aqueous phase. The tentative reaction pathways are supported by theoretical calculations of the reaction Gibbs energies. Our findings provide new insights into potential sources and formation pathways of OSs occurring at the water (sea, lake, river) surface, that should be considered in future model studies to better represent the air-water interaction and SOA formation processes.
Highlights
Organic sulfur compounds (OSs) are ubiquitous in atmospheric aerosols, and organosulfates are considered as important tracers of secondary organic aerosols (SOA)
To detect the gas-phase compounds formed by heterogeneous SO2 oxidation of Polycyclic aromatic hydrocarbons (PAHs)/DMSO
Among all detected m/z signals (Table S4), we tentatively identified a number of unsaturated multifunctional molecules and OSs released in the gas phase from the reaction of SO2 with either DMSO or
Summary
Organic sulfur compounds (OSs) are ubiquitous in atmospheric aerosols, and organosulfates are considered as important tracers of secondary organic aerosols (SOA). Based on the occurrence of hydrophilic and hydrophobic moieties in the same molecule, OSs are surfaceactive compounds that cause reductions of surface tension and enhance the formation potential of cloud condensation nuclei (CCN) in aerosol particles (Bruggemann et al, 2020). Both biogenic and anthropogenic sources such as biomass and fossil fuel burning release OSs into the atmosphere (Bruggemann et al, 2020). We show that oxidation by SO2 of PAHs/DMSO can release gaseous OSs, such as methanesulfonic acid (MSA), which are known precursors of secondary organic aerosols (SOA) in the atmosphere. We highlight the large amounts of generated linear and aromatic OSs, with potential to greatly influence the air-water exchange of organic compounds
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