Fast oxidation of sulfur dioxide by hydrogen peroxide in deliquesced aerosol particles
Tengyu Liu, Simon L. Clegg, Jonathan P. D. Abbatt
Abstract
Significance Atmospheric sulfate aerosol particles contribute significantly to poor air quality and direct forcing of the Earth’s climate. However, air pollution and climate models simulate the formation of sulfate using acid rain chemistry known to be appropriate only for cloudwater conditions. By measuring the oxidation of sulfur dioxide (SO 2 ) by hydrogen peroxide (H 2 O 2 ) directly in hygroscopic, pH-buffered aerosol particles with high solute strength characteristic of many tropospheric conditions, we show that sulfate formation occurs significantly faster than under the cloudwater conditions previously explored. In part, ionic strength and general acid catalysis effects drive the fast chemistry. These results indicate that the H 2 O 2 -driven oxidation of SO 2 in aqueous aerosol particles can contribute to the missing sulfate source during severe haze pollution events.