Destruction and production rates of carbon monoxide in arid soils under field conditions

Carbon monoxide destruction and production processes take place simultaneously in soils (Seiler, 1978; Conrad and Seiler. 1980, 1982). The resulting net effect of both processes is usually the destruction of atmospheric CO (Inman, Ingersoll, and Levy, 1971; Heichel, 1973; Ingersoll, Inman, and Fisher, 1974; Liebl and Seiler, 1976; Seiler, 1978). Under arid soil conditions, however, soils may act as a net source for atmospheric CO. Desert and semidesert soils in southern Africa have been found to act permanently as a source for atmospheric CO (Conrad and Seiler, 1982). On the other hand, German soils under arid conditions showed a net emission of CO during daytime, but a net deposition of atmospheric CO at night (Seiler, 1978; Conrad and Seiler, 1982). The observed change of soil activity is caused by the changing rates of the individual CO destruction, or by production processes in the upper soil layers, or both. However, the parameters influencing the production and destruction proces ses of CO in the soil under field conditions are unknown. Field measurements were carried out on arid soils in Andalusia, Spain. The results indicate that the net flux of CO at the soil-air interface is determined mainly by changing CO production rates. These rates were found to be strongly dependent on the soil surface temperature. (IFU)