Trace Gas Absorption by Soil

A two-layered diffusion model was applied to the uptake process of trace gases as CO, H₂, and CH₄ which are utilized by soil microorganisms or enzymes assuming that its uptake obey first-order kinetics about its concentration. Analytical solutions for mono-layered model exhibit that the physical property as gas diffusivity in soil is more important for uptake process than emission process. The numerical simulation shows that the deposition of CO, H₂, and CH₄ are limited by the combination of transport process and the localization of the soil uptake zone, within 0.06cm s−1 for CO and 0.1cm s−1 for H₂, respectively, which are in reasonable consistence with field measurements.