The effects on sorption on geological media caused by the presence of materials derived from a cementitious repository have been studied. This work includes an investigation of the influence of cellulosic degradation products on the sorption of tin and radium on London clay and Caithness flagstones and the sorption of radium as a function of calcium concentration.
Experimental conditions were chosen to simulate those expected close to a cementitious repository (pH=l1) and at the edge of the zone of migration of the calcium plume (pH=8). Work was carried out, (i) under baseline conditions in the absence of organic materials; (ii) with gluconate, acting as a well-characterized organic degradation product simulant; (iii) with authentic cellulosic degradation products.
This investigation has shown that the sorption of tin can be affected by the presence of cellulosic degradation products whereas the sorption of radium is little affected. The sorptive behaviour of radium is however strongly influenced by the calcium concentration.