Evolution of the Composition and pH of Single Aqueous Aerosols Produced from Bulk Aqueous Sulfite Solutions

), S(IV) is completely oxidized to S(VI), as sulfate, on the time scale of minutes and occurs several hundred times faster than for bulk solutions. In addition to soluble S(IV) oxidation, we also establish the time scales for gas-phase partitioning and aerosol pH changes. Overall, this study shows the need to quantify aqueous aerosol composition, pH, and charge following production from bulk solutions and the role of aqueous surfaces in driving compositional changes, highlighting the role of surfaces in multiphase sulfur chemistry for accurate representation in air quality models.