Impact of humic matter on sorption of radionuclides by montmorrilonite

The paper has analyzed the impact on sorption by montmorrilonite of the chemical nature of radionuclides, forms of their finding and concentration of humic matter. It has been found that for Eu(III) and Th(IV) in the presence of humic matter one can observe reduction of sorption within the pH wide interval, which is determined by the formation of fulvate and various ligand hydroxofulvate complexes, while for U(VI)—in an acid region, which indicates the formation of only fulvate complexes. It has been shown that in the presence of humic matter in the aqueous medium an increase of migration of radionuclides is determined by a decrease of their sorption on mineral suspensions and precipitation on the surface of silt sedimentations as a result of the formation of soluble complex compounds, while the presence of humic matter on the surface of clayey components of soils substantially increases immobilization of radionuclides, i.e., reduced migration of the latter to the environment.