Prediction of solid/liquid distribution coefficients of radiocaesium in soils and sediments. Part two: a new procedure for solid phase speciation of radiocaesium

A new procedure is developed for assessing the speciation of radiocaesium in soils and freshwater sediments. The method relies on the difference in the variation ofKD137Cs CS with NH4 concentration when Cs is present in the regular ion exchange complex or the micaceous frayed edge sites. The theoretical basis for the method is presented. The experimental procedure is based on the measurement ofKD137Cs as a function of NH4 concentration in a mixed Ksingle bondCa solution of constant composition. It is demonstrated that in most sediments and some soils, even some peat soils of 80% organic matter content,KD137Cs response to NH4 concentration coincides with the one obtained for a reference illite clay, thus showing quantitative adsorption of radiocaesium in the frayed edge sites of the micaceous clays.