FORMS AND RATES OF RELEASE OF CS-137 IN 2 PEAT SOILS

Cation exchange resin saturated with H+ and Ca2+ was used to extract C s-137 from peat soil at two sites in Britain affected by Cs-137 deposi tion following the Chernobyl accident. The technique identified three classes of Cs-137, similar to those observed for K+ in soils: 'Fast', 'Intermediate' and 'Slow'. These classes are probably related to the s electivity for Cs-137 Of the cation exchange sites on the organic matt er and the clay minerals, and to the structure of the soil. With one e xception, most Cs-137 was in the 'Slow' form and was only very slowly released to the resins, if at all. However, there was enough Cs-137 in the 'Fast' and 'Intermediate' forms to contaminate pasture and thus g razing animals for some years. Based on the resin technique, it is est imated that contamination will persist for several decades in uplands contaminated at these activity concentrations.