Gas diffusivity‐based characterization of aggregated soils linking to methane migration in shallow subsurface

Methane transport in soil is primarily affected by physical conditions such as texture and structure, moisture, soil-gas diffusivity, permeability, temperature. Aggregated soils have distinct structure with two pore regions characteristics (i.e., interaggregate intraaggregate regions) therefore show bimodal behavior respect to properties controlling gas migration. This study characterized an aggregated retrieved near a natural (NG) extraction site at Denver–Julesburg (D-J) basin northeast Colorado (USA) soil-water characteristic (SWC), pore-size distribution, diffusivity thermal conductivity. The investigated exhibited distinctive two-region characteristics, which were adequately parameterized extended, existing, newly developed functions. We carried out analysis integrated model parameters obtain graphical insight on the correlation of properties. In addition, CH4 concentration profiles originated from point source representing buried pipeline leakage three different flow rates (6, 12, 24 L min–1) simulated numerical tool that can simulate multiphase mixture under dry saturation soil. Simulated results highlighted pronounced effects moisture and, lesser degree, rate subsurface concentrations profiles, suggesting diffusion-dominated movement subsurface.