Time series and isotopic evidence for gaseous components (222Rn, CO2 and its carbon isotopes) of soil under a cool temperate deciduous forest in Hokkaido, Japan

The behavior of gaseous components of forest soil was assessed by simultaneous monitoring of Rn-222, CO2 and its carbon isotopes (delta C-13, Delta C-14) in soil air under a semi natural forest in northern Japan. The isotope ratio of C-14 (Delta C-14) in soil air CO2 was found to decrease towards late summer, suggesting gradual depletion of easily decomposed soil organic matter. There was a specific case that soil air CO2 with depleted C-14 appeared suddenly under snowpack in winter. It is not always appropriate to use soil Rn-222 as a tracer of CO2 efflux from the soil surface to the atmosphere.