Oxidation of dissolved SO2 by NO2 may be important if the aerosol pH is high (4, 6) and inclusion of a hypothetical heterogeneous oxidation ...
Explanation:
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 (SO2) by hydrogen peroxide (H2O2) 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 H2O2-driven oxidation of SO2 in aqueous aerosol particles can contribute to the missing sulfate source during severe haze pollution events.
