Sorption–desorption phenomena of contaminants by soils are of great importance from the viewpoint of environmental and agricultural concerns. The knowledge of sorption–desorption characteristics of contaminants by soil is useful in simulation and prediction of contaminants, transport and diffusion in soil–water systems and uptake by plants. The adsorption behavior of Cs and Sr on two selected calcareous soils (clay and silty clay loam) with contrasting physical and chemical characteristics was studied in different concentrations of Cs and Sr by a batch method. The selected chemical and physical properties of the soils were determined and the dominant clay minerals of the soils were identified by XRD. Cs and Sr sorption characteristics were determined at 22.5 ± 0.5 °C in the presence of 0.01 M CaCl2. Freundlich isotherms were found to fit well with experimental data obtained for adsorbed Cs and Sr. This experiment showed that using the relative ratio of cations in the soil solution was better index to understand the phenomenon of the adsorption of Sr and Cs in saline-sodic soils. The higher amount of illite and vermiculite clay minerals in the soils contributed significantly to the higher affinity of Cs by the soils.
