Although soil structure and pore geometry characteristics largely control transport processes in soils, there is a general lack of experiments that study the effects of soil structure and pore space characteristics on gaseous and solute diffusion. Our objective was to determine the dependency of soil gaseous and solute diffusion on fluid content, and compare results for both disturbed (D) and undisturbed (UD) soils. For that purpose, we first measured the gaseous diffusion and electrical conductivity for several intact, undisturbed soil samples at different water content level. Then, the solute diffusion coefficients were estimated from the measured soil bulk electrical conductivity data as a function of water content. Subsequently, the same samples were crushed and repacked into the same soil cores to create the disturbed equivalent for the same soil material. Measurements showed large differences between disturbed and undisturbed samples, confirming the enormous impact of soil structure and pore space characteristics on transport of gaseous and solutes. The diffusion of gaseous and solutes was distinctively reduced for the disturbed samples, especially for soil gaseous diffusion due to its greater dependency on pore continuity and connectivity at given water content.
See more of Flow and Transport Processes
See more of S01 Soil Physics
See more of The ASA-CSSA-SSSA International Annual Meetings (November 6-10, 2005)