Forms of radionuclide occurrence in soil

This paper covers research into the forms of the 137Cs and 144Ce radionuclides having entered the soil as a result of the Chernobyl accident. The difference between the sorptive behaviour of these radionuclides and that of the same radionuclides introduced into the same soil in ionic form may be useful in drawing conclusions about the forms of radionuclides in the soil. 86 soil samples were taken at the following distances to the north of the reactor: 6, 80 and 150 km (Gomel region) and 260 km (Mogilev region) of Byelorussia. In addition to sorption and desorption experiments using solutions of different composition, we also carried out experiments involving ultrafiltration of solutions (using membranes with a pore diameter of 0.5, 0.19, 0.1 and 0.06 microns) produced by desorption of Cs and Ce in real and model experiments. From the overall results we conclude that Cs and Ce are present in soils of widely differing composition, partly in ionic forms and partly in the form of particles, the matrices of which are either uranium dioxide or graphite. (author)