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キーワード:
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要旨:
The flux of a trace gas between soil and atmosphere is usually the result of simultaneously operating production and consumption processes. The compensation concentration is the concentration at which the rate of production equals the rate of consumption so that the net flux between soil and atmosphere is zero. Production and uptake may be due to different processes, which are at least partially known for some of the trace gases, and which may be differently regulated. The direction and the magnitude of the flux between soil and atmosphere is a function of both the compensation concentration and the trace gas concentration in the ambient atmosphere. Compensation and/or ambient concentrations may fluctuate and thus may have a strong impact on the flux of CO, NO and NO2, and to a smaller extent also on that of H-2. Compensation concentrations also exist for N2O and OCS, but are too high to affect the flux under field conditions. Compensation concentrations have so far not been demonstrated for the flux of CH4. However, the uptake of CH4 by soil exhibits a threshold concentration below which no uptake occurs.
