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, HCOO-, CH3COO, and OHwere measured at 273 ( 1 K using a wetted-wall flow tube reactor. The values of HDl k (H ) Henry’s law coefficient, Dl ) 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/Xpair suggest that the NO3 + Xreactions proceed by electron transfer. The atmospheric implications of these findings are briefly discussed.