On the inventory of artificial tritium and its occurrence in atmospheric methane

Consideration of the bomb-produced tritium inventory and features of the budget and distribution of tritium in atmospheric water vapor, hydrogen, and methane provides a basis for rejecting previous explanations for the incorporation of artificial tritium into atmospheric methane. It is concluded that tritiated hydrogen is produced in thermonuclear clouds by radiative dissociation of water under oxidizing conditions. The occurrence of tritiated methane is explained by tropospheric exchange of methane with tritiated hydrogen which has mixed downward from the stratosphere. Chemical and energy criteria for the exchange of methane and hydrogen in the lower atmosphere are discussed. High tritium concentration of formaldehyde from thunderstorm rains is predicted. The possibility of equilibrium isotope exchange between tritiated water and tritiated hydrogen in thermonuclear clouds and in the upper atmosphere is also noted.