Forms and rates of release of 137Cs in two peat soils

Cation exchange resin saturated with H+ and Ca2+ was used to extract 137Cs from peat soil at two sites in Britain affected by l37Cs deposition following the Chernobyl accident. The technique identified three classes of 137Cs, similar to those observed for K+ in soils: ‘Fast’, ‘Intermediate’ and ‘Slow’. These classes are probably related to the selectivity for 137Cs of the cation exchange sites on the organic matter and the clay minerals, and to the structure of the soil. With one exception, most 137Cs was in the ‘Slow’ form and was only very slowly released to the resins, if at all. However, there was enough l37Cs in the ‘Fast’ and ‘Intermediate’ forms to contaminate pasture and thus grazing animals for some years. Based on the resin technique, it is estimated that contamination will persist for several decades in uplands contaminated at these activity concentrations.