Modeling the Ionic Strength Effect on Diffusion in Clay. The DR-A Experiment at Mont Terri

Solute diffusion in compacted clays depends on ionic strength through its control on the thickness of the electrical double layer (EDL) on the charged clay surfaces. In the DR-A field experiment (Mont Terri, Switzerland), synthetic porewater was circulated through a borehole for 189 days, leading to the out-diffusion of a variety of tracers into the Opalinus Clay. The borehole solution was then replaced with a higher-salinity solution for an...