Chemical evolution of particle-phase dimethyl sulfide oxidation products

Abstract:

Dimethyl sulfide (DMS) is the largest natural source of sulfur to the atmosphere and an important source of oceanic non-sea salt aerosol, but uncertainties remain in its oxidative pathway and ultimate fate. With the recent discovery of hydroperoxymethyl thioformate (HPMTF) prompting a reexamination of DMS chemistry, close study of the DMS-derived aerosol particle phase is likewise important. Peroxy radical isomerization, a process not generally considered relevant in the DMS system before the identification of HPMTF, is known to contribute to the formation of highly oxidized molecules and nucleation in other systems and could play a role in particle formation here. In this study, we perform chamber experiments under varied conditions to study the aerosol particles resulting from the oxidation of DMS. We evaluate products using an Aerosol Mass Spectrometer, Scanning Mobility Particle Sizer, and complementary gas-phase mass spectrometric measurements. Specific results include the measurements of multi-generational particle-phase chemistry, discussion of unidentified particle-phase products, and analysis of particle size evolution.