Nitrate formation in atmospheric aerosols

Abstract

Equilibrium nitrate levels in aqueous solution in the presence of sodium chloride, nitric oxide, nitrogen dioxide, sulfur dioxide, carbon dioxide, ammonia, and sulfuric acid are calculated. Nitrate levels in solution are of the order of those observed in the atmosphere when the gaseous concentrations are at typical urban levels. Sulfate levels in such solutions are predicted to be relatively low in the absence of oxidation catalysts. When sulfate formation is assumed to occur by gas-phase oxidation of sulfur dioxide to sulfuric acid followed by absorption of the sulfuric acid in aerosols, predicted nitrate and sulfate size distributions are in qualitative agreement with those observed in the atmosphere.

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