Kinetics of the Reaction MSI− + O3 in Deliquesced Aerosol Particles: Implications for Sulfur Chemistry in the Marine Boundary Layer

Abstract

Abstract Multiphase oxidation of methane sulfinic acid (MSIA) by ozone (O3) in deliquesced aerosol particles is an important but poorly constrained reaction in the marine boundary layer, hindering the accurate prediction of radiative forcing of natural aerosols. Large uncertainties arise from the unmeasured reaction rate constant for the aerosol multiphase reaction between O3 and methanesulfinate (MSI−), the dominant MSIA species in sea salt aerosols. Here, we directly measured kMSI−+O3 by performing flow cell experiments coupled with a Raman spectroscopy to investigate the kinetics of multiphase oxidation of MSI− by O3 in pH‐buffered deliquesced aerosol particles relevant to marine atmospheric conditions. kMSI−+O3 for aerosol particles was determined to be (2.2 ± 0.5) × 107 M−1 s−1, 10 times the value in dilute solutions. This higher rate constant would increase the yield of methane sulfonic acid from multiphase oxidation of MSIA and has important implications for accurate modeling of sulfur species.

Keywords

• sulfur chemistry
• kinetics
• multiphase oxidation
• methane sulfinic acid
• marine boundary layer