ATMOSPHERIC CARBON TETRAFLUORIDE - 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 CF4 of over 10,000 years, about 100 times that for dichlorodifluoromethane (CF2Cl2) and monofluorotrichloromethane (CFCl3). It is predicted that CF 4 will be well mixed through the stratosphere and mesosphere; only one or two parts of hydrogen fluoride in 1012 are predicted in the high stratosphere as a result of the decomposition of CF4. Although natural sources of CF4 cannot be ruled out, there are several likely industrial sources that may account for its present concentration. The principal environmental effect of CF4 could be the trapping of outgoing planetary infrared energy in its intense bands near 8 micrometers. Copyright © 1979 AAAS.