Oxidation of Methane in the Natural Atmosphere and OH Radical Chain Reaction

1 Oxidation of Methane in the Natural Atmosphere and OH Radical Chain Reaction 

As described in Chap. 1, in contrast to stratospheric chemistry that can be traced back to the 1930s when the chemical theory of ozone layer formation was published by Chapman (1930), research on chemical reaction system in the tropospheric 

Akimoto, Atmospheric Reaction Chemistry, Springer Atmospheric Sciences, DOI 10.1007/978-4-431-55870-5 7 

As for the primary trace chemical species in the remote natural atmosphere where there is no influence of anthropogenic activities, methane (CH4) emitted from lakes and marshes, biogenic volatile organic compounds (BVOCs), nitric oxide (NO) from natural soils and lightning, dimethyl sulfide (DMS) from marine organisms, O3 descended from the stratosphere can be conceived. Among them, the most important chemical species that is subjected to photolysis by the actinic flux (see Sect. 3.5) in the troposphere is O3 and NO2 (see Sects. 4.2.1 and 4.2.2). 

The OH radicals formed by the reaction of water vapor H2O with excited oxygen atoms 0( D) produced by the photolysis of O3 (Sects. 4.2.1 and 5.1.4), play an unequivocally important role in tropospheric chemistry. 

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