FIXATION AND RELEASE OF Cs-137 IN SOILS AND SOIL SEPARATES

Abstract

In a series of experiments designed to describe Cs fixation and release by soils and sou separates, considerable Cs-137 was found to be fixed by the sand fractions of agricultural soils. The amount fixed by the sand exceeded that fixed by the clay m calcium-saturated samples taken from Podzolic soils. Cesium fixed when added as CsCl in macroconcentrations (5 meq per 100-g sample) was greater in the clay fractions than the sand fractions for all soils. These findings support the findings of others that there is more than one site for CS fixation depending on the concentration. Considerable Cs-137 was released by soil separates when shaken in the presence of H-resin. The amount released by the sand fraction was substantially greater than that released by the clay fraction for two of the three soils investigated. The fixation of Cs-137 was found to be approximately proportional to applied dose over a large range of carrier-free Cs-137 concentrations. The amount fixed by soils of alkaline pH was higher than that fixed by samples from Podzolic soils at all concentrations. When the soils were calcium-saturated after the removal of the colloidal sesquioxides by oxalate extractions, the difference between the fixation of Cs-137 by acid and alkaline soils was greatly decreased. This suggests strongly that these colloidal coatings blocked Cs-137 fixation by Podzolic soils.