Importance of photolysis of nitrate in oxidation of atmospheric sulfur dioxide

Photochemical oxidation of sulfite in concentrated solution of ammonium nitrate was studied with a mercury lamp and solar radiation as a chemical model system of the water-film on the atmospheric nitrate aerosol. Sulfite was found to be photo-oxidized with first-order reaction kinetics. Temperature and nitrate concentration dependences of the rate constant suggested that low temperature hardly decreased the atmospheric significance of this reaction and that the oxidation favored high conentration.