Abstract
Herein, theoretical studies were performed on the atmospheric oxidation of sulfurous acid (H2SO3) and sulfite ions (HSO3−) by ozone (O3) to produce sulfuric acid and hydrosulfate ions. The most favorable path for the H2SO3 + O3 reaction has been found to be initiated from concerted H-abstraction and oxygen addition, with an overall energy barrier of 18.3 kcal mol−1. On the other hand, the most favorable path for the HSO3− + O3 reaction is initiated from oxygen addition, with an overall energy barrier of only 0.3 kcal mol−1. Kinetic simulations were performed to estimate the significance of these reactions in the formation of atmospheric sulfate and destruction of the ozone layer. The results provide new insight into the missing source of atmospheric sulfate and particulate matter.
Highlights
Oxidation reactions are the most important reactions in the atmosphere, which connect anthropogenic and natural species.[1,2] The oxidation of sulfur species is considered to be the main channel for the production of atmospheric sulfuric acid (H2SO4) or sulfate species.[3,4] Gaseous sulfuric acid and sulfate have been identi ed as the major drivers to generate atmospheric aerosols.[3,5,6,7] As is well known, aerosols have a signi cant impact on the global environment such as climate change, reduction in visibility, and public health effects.[8]
It is clear that the oxidation of H2SO3 by O3 plays a minor role in the formation of sulfuric acid, and the energy barrier of the favorable reaction channel is 18.3 kcal molÀ1
The kinetic analysis veri ed that the oxidation of HSO3À played an important role in the formation of atmospheric sulfate
Summary
Oxidation reactions are the most important reactions in the atmosphere, which connect anthropogenic and natural species.[1,2] The oxidation of sulfur species is considered to be the main channel for the production of atmospheric sulfuric acid (H2SO4) or sulfate species.[3,4] Gaseous sulfuric acid and sulfate have been identi ed as the major drivers to generate atmospheric aerosols.[3,5,6,7] As is well known, aerosols have a signi cant impact on the global environment such as climate change, reduction in visibility, and public health effects.[8] In addition, hexavalent sulfur species are con rmed as the major fraction of PM2.5 (aerosol particles with an aerodynamic diameter less than 2.5 mm), which are associated with certain sicknesses and other acute or chronic health effects.[7] Air pollution caused by sulfur emissions will remain for a long time in China due to its coal-based energy structure.[9] Haze days with high concentrations of PM2.5 appear frequently in the northern cities of China during the cold winter and spring seasons[10] due to the increase in emissions from heating.[11,12] Atmospheric aerosols are hazardous to both human health and the environment.[3,7,8] understanding the
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