Trace gas absorption by soil -: Simulation study on diffusion processes of trace gases, CO, H2, and CH4 in soil

A two-layered diffusion model was applied to the uptake process of trace gases as CO, H-2, 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, H-2, 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 H-2, respectively, which are in reasonable consistence with field measurements.