Mechanism of non-photochemical formation and estimation of rate of sulphate accumulation in atmospheric haze
G.B. Pronchev, A.N. Yermakov
N.N. Semenov Federal Research Center for Chemical Physics, Russian Academy of Sciences, V.L. Talroze Institute of Energy Problems of Chemical Physics of the Russian Academy of Sciences, Moscow, Russia
Keywords: aerosol, atmospheric haze, sulfate, non-photochemical reaction, catalysis, Fe/Mn ions
Abstract
The causes of dense non-photochemical haze (smog) over Beijing in winter conditions are still poorly understood. The purpose of the work is to study the mechanism of catalytic oxidation of sulfur dioxide with molecular oxygen in aerosol particles and the formation of dense non-photochemical haze. It is shown that the rapid accumulation of SO42- (tens of μg × m-3 × h-1) is observed only at high humidity and moisture acidity in particles рН = 3.7÷4.8. The reason is the transition in these conditions of the catalytic (non-photochemical) oxidation of SO2 by atmospheric oxygen with the participation of Fe and Mn ions into a fast degenerate branched mode. Modeling of the occurrence of catastrophically dangerous atmospheric haze should necessarily be carried out taking into account the mechanism of this catalytic reaction.
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