Atmospheric sulphur oxidation: Impact of ozonolysis reactions on the sulfate production in cloud droplets.

摘要

Clouds play a major role in the production of acids in the atmosphere. One of the most studied in-cloud processes is the aqueous-phase oxidation of sulfur IV into sulfate. From previous studies, large observed concentration of sulfate species resulting from sulfur IV oxidation in the atmosphere during the late fall and winter are still unexplained. Ariya found that ozonolysis of alkenes can be an additional source of oxidant in the gasphase.; In this project, we assessed the effect of ozonolysis of alkenes on in-cloud sulfur chemistry. We used a tropospheric chemistry box-model called MOCCA (Model of Chemistry Considering Aerosols) coupled with a simple cloud droplet model in the presence and absence of ozonolysis. The results obtained reinforce the hypothesis that ozonolysis of alkenes can play a role in the sulfate production in cloud droplets. In fact, we observed that ozonolysis could, in a situation of a high pH, slow down the in-cloud oxidation and can possibly lead to an overall negative impact on the in-cloud sulfate production over an average cloud lifetime. (Abstract shortened by UMI.)