The Influence of Trace Elements in Consolidated Sedimentary Rocks on the Migration Behaviour of Radionuclides

ABSTRACTThe effects of trace contents of 15 elements in the sedimentary rocks on the Rs- and Rd-values (Maass, 1983) of the dissolved radionuclides of the elements C (as carbonates), Se, Sr, Tc, I, Cs, Pb, Ra, Ac, Pa, U, Np, Pu, Am. and Cm were investigated and discussed. For this purpose Sr, Ba, B, Corg., Pb, P, F, Cu, Zn, Cd, V, Mn, Fe, Co and N1 contents in the rocks were compared to the sorptlon/desorption coefficients of the above mentioned 15 radionuclides and plotted in x-y diagrammes (a total of 225). While the magnitude of most trace element contents has no or only a slight influence on the retention properties of most radionuclides, a distinct correlation between the trace element contents and the magnitude of the distribution coefficients was found for some radionuclides. Particularly copper, organic carbon, and barium are found to take a positive influence on the Rs-/Rd-values of certain radionuclides. The presence of other trace elements (eg. B and F) can have a negative effect on the retention behaviour of the rock matrix as regards certain dissolved radionuclides. Seen as a whole, the magnitude of the desorption coefficients (Rd-val-ues) appears to be more closely correlated to the trace element contents than to the sorption coefficients (Rs-values).