Atmospheric carbon tetrafluoride: a nearly inert gas.

An analysis of existing thermodynamic, photochemical, and kinetic data indicates that the dominant sinks for atmospheric carbon tetrafluoride (CF(4)) are in and above the mesosphere. Theoretical calculations predict an atmospheric residence time for CF(4) of over 10,000 years, about 100 times that for dichlorodifluoromethane (CF(2)Cl(2)) and monofluorotrichloromethane (CFC1(3)). It is predicted that CF(4) will be well mixed through the stratosphere and mesosphere; only one or two parts of hydrogen fluoride in 10(12) are predicted in the high stratosphere as a result of the decomposition of CF(4). Although natural sources of CF(4) cannot be ruled out, there are several likely industrial sources that may account for its present concentration. The principal environmental effect of CF(4) could be the trapping of outgoing planetary infrared energy in its intense bands near 8 micrometers.