[摘要] The uptake ofHNO
3 to deliquescent airborne sea-salt particles (RH = 55%, P =760 torr, T = 300 K) at concentrations from 2 to 575 ppbv is measured in an aerosolflow tube using
13N as a tracer. Small particles(
70 nm diameter) are used in order to minimize the effect of diffusion in the gas phase on the mass transfer. Below 100ppbv, an uptake coefficient (gupt) of 0.50 ± 0.20 is derived. At higher concentrations,the uptake coefficient decreases along with the consumption of aerosol chloride. Datainterpretation is further supported by using the North American Aerosol InorganicsModel (AIM), which predicts the aqueous phase activities of ions and the gas-phasepartial pressures of H2O,HNO3, and HCl at equilibrium for theNaCl/HNO3/H2Osystem. These simulations show that the low concentration data are obtained far fromequilibrium, which implies that the uptake coefficient derived is equal to the massaccommodation coefficient under these conditions. The observed uptake coefficientcan serve as input to modeling studies of atmospheric sea-salt aerosol chemistry. Themain sea-salt aerosol burden in the marine atmosphere is represented by coarse modeparticles (> 1 µm diameter). This implies that diffusion in the gas-phase is the limitingstep to HNO3 uptake until the sea-salt has been completely processed.
