Hydrogen, tropospheric mixing ratio

Molecular hydrogen is assumed to be well mixed in the troposphere, with a mixing ratio of 0.4 to 0.6 ppm [Junge (128) and Scholz, Ehhalt, Heidt, and Martell (219)]. Koyama (142) found that swamps and paddies are very small natural sources. Levy (153) proposed both an atmospheric source (photodissociation of formaldehyde) and an atmospheric sink (oxidation by hydroxyl radical). From daily average number densities for the hydroxyl radical and a daily average hydrogen production rate,... 

Hydrogen peroxide H2O2 is formed by the radical termination reaction HO2 + HO2, and exists in the troposphere generally at the mixing ratio in order of ppbv. Since H2O2 is water soluble, it is removed by the dissolution into cloud and fog water, while photolytic reaction is another important removal process. Methyl hydroperoxide CH3OOH also exists in the whole region of the troposphere in natural atmosphere as an oxidation product of methane. Its photolytic reaction is important as its removal process, and also as a radical source in the upper troposphere. 

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