Solid phase speciation of radiocaesium in bottom sediments

A comprehensive laboratory study is presented on the solid-phase speciation of ionic radiocaesium in bottom sediments (riverine, lacustrine, estuarine) covering some 75 samples of widely differing textural properties and originating from various locations in Europe. Sediments are characterised in terms of cation exchange capacities, exchangeable potassium and ammonium and specific radiocaesium sorption properties. It is shown that radiocaesium is quantitatively retained in the specific sorption sites associated with the micaceous clay minerals in the sediments. The practical consequences of this finding are discussed in terms of a predictive equation allowing forecasting of radiocaesium levels in the watercolumn or in the interstitial fluid of the sediment.