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

The reactive uptake coefficients, γ, of NO 3 onto aqueous solutions containing ions X - = HSO 3 -, SO 3 2-, HCOO -, CH 3 COO -, 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 NO 3 with X - ) for the reactive uptake of NO 3 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 SO 4 - reactions, and the dependence of the measured rate coefficients on the redox potential of the X/X - pair suggest that the NO 3 + X - reactions proceed by electron transfer. The atmospheric implications of these findings are briefly discussed.