Leaching characteristics of strontium from gypsum soil and calcareous sand present in saline land in arid regions: consequences for migration of radiostrontium.

The research presents a novel investigation into Aridosol, which are characteristic of arid regions and have not been previously studied concerning radionuclide migration. Additionally, the role of salinity as a factor affecting radionuclide adsorption has been largely overlooked. To elucidate the adsorption characteristics of strontium in these local soils, both batch and column experiments were conducted. The Sr was deposited in the calcareous sand when the mobile phase salinity decreased from the saturated solution. A similar situation occurred when the salinity increased after previous applying the milli-Q water. Notably, the impact of sudden salinity fluctuations was not evident in gypsum soils. The effect of milli-Q water on the leaching of Sr and Ca was different in calcareous sand and gypsum: the release of Sr and Ca from the sand is characterized by an initial substantial release, followed by a pronounced decline. The concentrations changed within several orders of magnitude. In contrast, the effect in gypsum was less intensive, with concentration variations occurring within a single order of magnitude. Gypsisols and calcareous sands allow running a broad spectrum of processes that influence the retention or release of Sr from soil. The impact of milli-Q water is mainly in dissolving matrix minerals, which release previously deposited strontium. Given that the local soil lacks strong Sr adsorbers, the behavior of strontium is predominantly governed by the chemical equilibrium in the soil solution. The rainwater could have an intensive impact on the Sr leaching from the soil, thereby increasing its mobility.