TROPOSPHERIC HONO AND REACTIONS OF OXIDES OF NITROGEN WITH NACL

Although nitrous acid is important in both the polluted and remote troposphere, as well as indoors, its mechanisms of production from oxides of nitrogen are not well known. The reactions of N2O5 with NaCl and NaBr in sea salt particles in the presence of water have been hypothesized recently to act as sources of particulate nitrite and which forms gaseous HONO. We report here the results of studies of the reactions of N2O5, HONO and NO2 with NaCl using diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) to follow the formation of products on the salt surface. The infrared bands arising from species formed on the salt surface can be attributed to nitrate ions associated with water molecules; the presence of NO3- was confirmed by chemical analysis of the reacted salts. No nitrite was detected either by DRIFTS or by chemical analysis. Thus the reactions of sea salt particles with N2O5 in the troposphere are not expected to be significant sources of particle nitrite nor of gaseous HONO via conversion of the particle nitrite.