Soil–Radionuclide Interaction under Varied Experimental Conditions

Studies on sorption behavior of fission products like cesium (${}^{137}\mathrm{Cs}$) and strontium (${}^{90}\mathrm{Sr}$) with the soils of some Near Surface Disposal Facility sites have been undertaken along with activation products like cobalt (${}^{60}\mathrm{Co}$). Soil used in this study are silty sands and inorganic silts and clays. Sorption behaviors of these stated radioisotopes have been studied using laboratory batch experiments under varying conditions of equilibration time, pH, and liquid-to-solid ratios. The study reveals that the sorption partition coefficient is strongly affected by contact time, pH, and liquid-to-solid ratio. Initially, the sorption reaction rate increases very rapidly with increases in time and approximately after 24 h, it attains equilibrium for the radionuclide–soil system. The study reveals that chemical constituents of the soil and their amount present in the soil also control the sorption of radionuclides. The study indicates that soil that has some clay minerals (montmorillonite) has comparatively higher distribution coefficient ($K_d$) and attains dynamic equilibrium early compared to soil with lower clay content. It was also observed that $K_d$ increases with increase in liquid-to-solid ratio almost linearly but steeply.