Sorption of 137Cs and Pb on sediment samples from a drinking water reservoir

This study focused on 137Cs and Pb accumulation in sediments from the Dobczyce Reservoir in southern Poland. Elements' spatial distribution as well as their distribution in sediment core samples were analyzed. The conditions of cesium and lead desorption were also investigated. The distribution coefficient for 137Cs (KCs) was obtained using a radiometric determination in combination with static ion-exchange chromatography. Determination of the distribution coefficient for Pb (KPb) was performed by means of atomic absorption spectrometry (electrothermal technique). The experiments were carried out considering various concentrations of potassium and calcium ions (from 5 x 10-3 to 10-5 mol x dm-3 by addition of KNO3 and Ca(NO3)2, respectively). It was found that: a) spatial distribution of anthropogenic 137Cs and Pb in the sediments of the Dobczyce Reservoir results mainly from hydrological conditions of the sedimentation process and, on the other hand, from the sorptive properties of the deposited material, b) in the case of 137Cs sorption, a pronounced competitive effect was noted for K ions; much less effect was found for Ca. On the contrary, in the case of lead such a competitive effect was visible for Ca, much less for K. The conditions of 137Cs desorption from the sediments caused by K and Ca ions present in water were estimated. (authors)