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The Conversion of SO 2 to Sulfate in the Atmosphere
Author(s) -
Eatough D.J.,
Caka F.M.,
Farber R.J.
Publication year - 1994
Publication title -
israel journal of chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.908
H-Index - 54
eISSN - 1869-5868
pISSN - 0021-2148
DOI - 10.1002/ijch.199400034
Subject(s) - chemistry , ozone , sulfate , relative humidity , atmospheric chemistry , aqueous solution , sulfate aerosol , ammonia , aerosol , homogeneous , hydrogen peroxide , atmosphere (unit) , meteorology , environmental chemistry , thermodynamics , organic chemistry , physics
The atmospheric chemistry responsible for the conversion of SO 2 (g) to particulate sulfate in areas impacted by anthropogenic emission of SO 2 is reviewed. The major reaction mechanism for the homogeneous conversion process in the absence of clouds or fog is the oxidation of SO 2 (g) by the hydroxyl radical. The rate of this conversion process increases with both increasing temperature and relative humidity. Correlations are described for the effects of these two variables on the conversion process, and equations given which correlate all of the available literature data for the homogeneous conversion process in ambient atmospheres. The conversion of S(IV) to sulfate via aqueous solution chemistry in clouds and fog is more complex and dependent on several variables, including concentrations of the principal oxidants (hydrogen peroxide and ozone), ammonia, droplet size and composition, and meteorology. The gas‐phase homogeneous conversion process can vary from less than 1% SO 2 (g) converted per hour to a maximum of about 10% converted per hour at high temperature and relative humidity. In contrast, the rate of conversion of S(IV) to sulfate in the aqueous‐phase homogeneous process is controlled by mixing and reactant limitations, rather than kinetic considerations. The process can involve 100% SO 2 converted per hour under optimum conditions. Consequences of the various conversion processes on environmental quality are briefly illustrated with a discussion of the impact of sulfate‐containing aerosols on PM 10 concentrations and visibility degradation.