Significance of peroxynitric acid in atmospheric chemistry of nitrogen oxides

Abstract

KNOWLEDGE of the life cycle and budget of nitrogen oxides in the atmosphere is important for several reasons. In the stratosphere, NO and NO₂ (NO_X) play a dominant part in maintaining the structure and stability of the ozone distribution. In the troposphere, NO_X is involved in the production and destruction of OH radicals which control the fluxes of many important species such as CH₄, CO, H₂ and CH₃Cl, to the stratosphere. In polluted urban areas, NO_X chemistry provides the basic formation mechanism of photochemical air pollution. In all these areas of atmospheric chemistry, the interactions of NO_X with HO_X species (HO, HO₂ and so on) are of great significance, particularly the reactions of HO₂ with NO and of HO with NO₂. A further HO_X–NO_X interaction is the proposed¹ formation of peroxynitric acid in reactions (1) and (−1): We present here a study of the extent to which reaction (1) and (−1) acts as a sink for HO_X and NO_X in the atmosphere.