Determination of distribution coefficient of Pliocene clay (Brusartsi Formation) in the Kozloduy area, Bulgaria

The Pliocene sediments of the Brusartsi Formation play a role of the bedrock in the Kozloduy lowland. Several important nuclear facilities have been constructed in this area. The upper part of the formation falls into the vadose zone and this part of the sediments is the main natural barrier against eventual radionuclide migration in the geoenvironment. One of the most important parameters used in estimation of mass transport is the distribution (or partition) coefficient Kd. It is a key parameter for the evaluation of the retention capacity of a given soil to adsorb dissolved contaminants. In the current paper the determination of the site-specific Kd values of Ni and Sr for clayey soil from the Brusartsi Formation derived by direct and indirect methods is described.