Uptake of NO3 on Water Solutions: Rate Coefficients for Reactions of NO3 with Cloud Water Constituents

The reactive uptake coefficients, γ, of NO3 onto aqueous solutions containing ions X- = HSO3 -, SO3 2-, HCOO-, CH3COO-, and OH- were measured at 273 ± 1 K using a wetted-wall flow tube reactor. The values of H 2 D l k (H = Henry's law coefficient, D l = diffusion coefficient in the liquid phase, and k = second-order rate coefficient for the liquid phase reactions of NO3 with X-) for the reactive uptake of NO3 were determined by measuring γ as a function of liquid phase reactant concentration. The linear correlation between the measured rate coefficients and those for corresponding SO4 - reactions, and the dependence of the measured rate coefficients on the redox potential of the X/X- pair suggest that the NO3 + X- reactions proceed by electron transfer. The atmospheric implications of these findings are briefly discussed.