“…The first type makes assumptions on physico-chemical mechanisms which govern the migration of radionuclides in soil and their interaction with soil particles (e.g. Frissel and Poelstra, 1967;Bear, 1972;Selim and Mansell, 1976;Bunzl, 1978;van Genuchten and Cleary, 1983;McKinley and Alexander, 1992;Roth, 1996). An analytical model sui generis has been proposed by Kirchner (1998) based on assumptions about statistical distributions of soil properties.…”