A new method to study simultaneous methane oxidation and methane production in soils

Results of laboratory experiments show that 14 C‐labeled methane added to soil was consumed faster than atmospheric 12 C methane. This implies a source of methane, presumably through methanogenesis, in a soil that is a net consumer of atmospheric methane. The soil was well‐drained forest soil from Ispra, Italy. An undisturbed sample was taken with a steel corer and incubated under oxic conditions in a jar. Headspace samples were taken at time intervals and analyzed for total methane by gas chromatography and analyzed for 14 C methane by liquid scintillation counting. Fluxes calculated from the decreasing headspace mixing ratios were, for example, −6.5 and −7.1 μmol m −2 hr −1 for 12 C methane and 14 C methane, respectively. A simple model is considered which reproduces reasonably well the observed mixing ratios as function of time.