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The vertical distribution of 137Cs is shown for two types of soil: silty loamy "supposed" soil and silty lessive one, slightly eroded, occurring in the vicinity of Lublin (Eastern Poland). Based on the distribution data the vertical migration rates of 137Cs are calculated for both soils. These rates are found to be 0.045 and 0.3 cm/year respectively. The percent contribution of 137Cs originating from the damaged reactor in Chemobyl is also calculated. The kinetics of cesium adsorption and its adsorption isotherms on minerals separated from the tested soils are also studied. The sorption of Cs on soil minerals markedly affects the migration rate of 137Cs in soil. The experimental results indicate that, among the extracted mineral fractions, the largest adsorption takes place on marls from the silty loamy soil. This work is supplemented by results of a physicochemical analysis of the studied soils.

The results of field, column and laboratory studies carried out on three types of mineral soils are encloses presented. Based on the field tests, average migration rates of 137Cs were calculated. The highest rate was found for the brown soil (FAO/UNESCO -Cambisol). Cesium migrated with the lowest rate in the podzol soil (FAO/UNESCO -Cambic Podzol). The column experiments confirmed the above observation. In laboratory tests the adsorption and desorption isotherms of Cs were determined on samples taken from 0-2 cm layers of each soil profile. It was found from the calculated partition coefficients that Cs is always irreversibly bonded to some extent, but it appears to be completely and irreversibly immobilized on the podzol soil. The permanent retention of cesium in the podzol soil was also confirmed by microcalorimetric studies. The desorption energy was negligibly small and amounted to -0.21 mJ/g. In the brown soil, containing prevailing amounts of loamy minerals, the desorption energy was found to be 106.89 mJ/g. The investigations are supplemented by the sorption kinetics measurements. These indicate that the adsorption equilibrium is reached after a dozen, up to twenty or so minutes.

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