Dynamics of sulfate origination in atmospheric haze
A.N. Yermakov1, A.E. Aloyan2, V.O. Arutyunyan2
1V.L. Talroze Institute of Energy Problems of Chemical Physics of the Russian Academy of Sciences, Moscow, Russia
2Marchuk Institute of Numerical Mathematics of the Russian Academy of Sciences, Moscow, Russia
Keywords: aerosol haze, sulfur dioxide, catalysis, chain branching, Fe/Mn ions
Abstract
We consider data from laboratory simulation of the dynamics of sulfate origination in atmospheric haze particles during oxidation of SO2 captured from the gas phase in the presence of Mn/Fe ions. The rates of sulfate origination under dark conditions of these experiments (tens of micrograms m-3 × h-1) have been found to correspond to a previously unknown mode of catalytic reaction. Its key element is the branching of chains involving the intermediate HSO5- ( Caro’s acid) and Mn2+ ions. Estimates are given for the rate constant of this aqueous-phase reaction, and a criterion for separation the slow and degenerate-branched (fast) modes of SO2 oxidation is considered. The observed rate constant of sulfate origination in particles k*obs = 1.4 L × mol-1 × s-1 ( T = 298 K). The calculations of the dynamics of sulfate origination agree with data of laboratory experiments (smog chamber data). Their results also do not contradict the monitoring data on sulfate content in the haze over Beijing (December 2016).
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