On the influence of atmospheric chemical reactions on the ion composition of aerosol particles in the Baikal region

Abstract

Monitoring data on the ion composition of aerosols and gas admixtures in the background and polluted atmosphere of the Lake Baikal region are presented. The ion composition and morphology of aerosols are affected by heterogeneous chemical reactions and variations in relative humidity. Two types of aerosol particles are revealed over this region. The fraction of solid particles recorded in most episodes includes primarily carbonates of alkaline and alkaline-earth metals. With increased atmospheric humidity, these particles are engaged in heterogeneous chemical reactions with gas-phase NH3 and H2SO4, proceeding through the phase of watering. As a result, the composition of these aerosols is changed, and a fraction of aqueous H2O/H2SO4/(NH4)2SO4 aerosol particles of a different composition is formed. On the basis of a physical and chemical analysis of monitoring data on the aerosol composition and concentrations of gas admixtures, the average aerosol-size distribution of different types is estimated. For the first time, the mean acidity of aqueous aerosol particles is estimated.