A qualitative analysis of atmospheric reactions between SO 2 and NH 3

Abstract

The reactions between SO 2 and NH 3 are of great significance in the understanding of the formation of the atmospheric aerosols, the environmental sulfur cycle and the fate of atmospheric sulfur dioxide. The majority of the studies of this reaction system, so far, have been on the catalytic role of the ammonium ion in the oxidation of sulfur dioxide in solution and on the formation of ammonium sulfate in solution through a weak acid-base reaction. Thus, a number of very significant side reactions have been largely ignored. The qualitative analysis of the products of reactions between very dilute concentrations of SO 2 and NH 3 both in the presence and absence of water suggests a wide range of possible parallel reactions to sulfate formation with a number of both stable, metastable and unstable sulfur compounds, as well as elemental sulfur. Very dilute, slightly SO 2 rich SO 2/NH 3 reaction system in a dry atmosphere leads to eight distinct reactions. In the presence of water, the number of reactions exceeds nineteen. In the laboratory, it was possible to confirm most of these reactions directly from the presence of the primary reaction products; the remaining reactions were inferred through the presence of secondary products.