CHEMICAL STATE OF TRITIUM IN THE ATMOSPHERE ee 4 m ee e ee HYDROGEN DATA e, Bainbridge et al.! — 2f- ee e 145 eee METHANE DATA mw, Bishop et al.é —_ a, Faltings and Harteck? e, Bainbridge et al.! gv, Rowland and Fireman? o, Bainbridge (quoted by Morte/!)? 7 oO, Grosse et al.4 ~ ©, Begemann and Friedman® 10° }— — — 8 — , — T/H IN H, ™ _] —_ + —~| | 4 Tt | T/H IN CH, SOUTHERN HEMISPHERE Lt ude TRITIUM UNITS = T/H IN Cry NORTHERN HEMISPHERE 10? -— YEAR 1948 1 o| 1950 | tT 1952 1954 | cE 1956 — dE 1958 1960 1962 1964 Fig, 1—Tritium concentration in hydrogen and methane. data of Rowland and Fireman? and Grosse et al.* tend to support the idea of an increase. Since the report of Bishop et al.® that there is a significant tritium level in methane in the atmosphere, a variety of proposals concerning the mechanism of the incorporation of tritium into methane have been advanced. Some of the proposals are based on the assumption that the tritium becomes incorporated in the methane during a nuclear explosion or by reactions occurring in the atmosphere under ordinary conditions. Martell’ has discussed the various proposals and offered a mechanism based on the incorporation of HT into methane through radical reactions initiated by energy released by elec- tric discharges, such as lightning, etc. The rate of the T/H increase in southern-hemisphere methane is consistent with a source in the northern troposphere which does not inject all the tritium at a single time.°

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