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

Shanujah, M and Deepagoda, TKK and Smits, KM and Shreedharan, V and Paramrswaran, TG and Babu, GLS (2021) Gas diffusivity-based characterization of aggregated soils linking to methane migration in shallow subsurface. In: Vadose Zone Journal .

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Abstract

Methane transport in soil is primarily affected by soil physical conditions such as soil texture and soil structure, soil moisture, soil-gas diffusivity, permeability, and soil temperature. Aggregated soils have distinct soil structure with two pore regions characteristics (i.e., interaggregate and intraaggregate regions) and therefore show bimodal behavior with respect to soil physical properties controlling gas migration. This study characterized an aggregated soil retrieved near a natural gas (NG) extraction site at Denver�Julesburg (D-J) basin in northeast Colorado (USA) with respect to soil-water characteristic (SWC), pore-size distribution, gas diffusivity and thermal conductivity. The investigated soil exhibited distinctive two-region characteristics, which were adequately parameterized with extended, existing, and newly developed bimodal functions. We carried out an analysis with integrated model parameters to obtain a graphical insight on the correlation of properties. In addition, CH4 concentration profiles originated from a point source representing a buried pipeline leakage at three different flow rates (6, 12, and 24 L min�1) were simulated with a numerical tool that can simulate the multiphase flow of gas mixture under dry and different saturation conditions of the soil. Simulated results highlighted pronounced effects of soil moisture and, to a lesser degree, of gas leakage rate on subsurface CH4 concentrations profiles, suggesting diffusion-dominated movement of CH4 in subsurface. © 2021 The Authors. Vadose Zone Journal published by Wiley Periodicals LLC on behalf of Soil Science Society of America

Item Type:	Journal Article
Publication:	Vadose Zone Journal
Publisher:	John Wiley and Sons Inc
Additional Information:	The copyright for this article belongs to Authors
Keywords:	Diffusion; Gas permeability; Gases; Pore size; Soil moisture; Textures; Thermal conductivity of gases, Aggregated soil; CH 4; Concentration profiles; Gas diffusivity; Region characteristics; Shallow subsurface; Soil science; Soil structure; Soil-structure; Vadose Zone, Methane
Department/Centre:	Division of Biological Sciences > Molecular Biophysics Unit
Date Deposited:	26 Nov 2021 10:56
Last Modified:	26 Nov 2021 10:56
URI:	http://eprints.iisc.ac.in/id/eprint/70462

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