A physicochemical characterisation and geochemical modelling approach for determining porewater chemistries in argillaceous rocks

Argillaceous sediments are being investigated in many countries as potential host rock formations for the disposal of high level radioactive waste. Quantification of the water chemistry in such formation is often difficult because the groundwater flow rates are so low that reliable samples for chemical analysis cannot be obtained. A physicochemical characterisation procedure for rock samples combined with geochemical modelling is described which allows porewater composition to be determined in low porosity/permeability clay rich systems. The methodology was applied to core samples of Opalinus clay within the framework of an international investigation being carried out at Mt. Terri, Canton Jura, Switzerland. Copyright (C) 1998 Elsevier Science Ltd.