diffusion and rock sorption capability

mainly controlled by mineral spatial arrangements and contents, since micro- to macrostructures of centimetric size are www.elsevier.com/locate/clay Applied Clay Science 23 (2003) 157–166encountered in each lithofacies. Effects of surface interactions and pore-constriction electrochemical controls were underscored for a large proportion of the effective porosity. Although the effective porosity is physically interconnected in the rock volume, diffusion and sorption are discussed in terms of structure and accessibility to sorption sites. These data could be the basis for the construction of a quantitative transport model by diffussion taking into account the sample heterogeneities from the mineral pore size to the centimetric core size ranges. The conceptualisation of the organization of the porosity in such low permeability clayey medium, considered together with the analysis of interface-derived effects constitutes an important step forward in understanding the mechanisms affecting the migration of single ionic species. This understanding should help in extrapolating transport parameters obtained at the centimetric scale from laboratory experiments to the geological formation scale