[Modeling of Processes of Migration and Accumulation of Radionuclides in Freshwater Ecosystems by the Example of the Samson, Lev, Vandras Rivers Related to the Ob-Irtysh River Basin].

Mathematical models of horizontal distribution and migration of radionuclides are presented in water and floodplain soils of the Samson-Lev-Vandras river system related to the Ob-Irtysh river basin. Integral inventory of radionuclides in the main components of the river ecosystems is calculated. The estimated annual discharge of radionuclides from the Vandras river to the Great Salym river is given. The effect of the removal of man-made radionuclides in the Samson, Lev, Vandras rivers on radioactive contamination of the Ob-Irtysh river system is shown in comparison with the Techa river, that also belongs to the Ob-Irtysh river basin. Despite the presence of an additional radioactive contamination of the Samson floodplain, the transfer of radioactive substances in the Samson, Lev, Vandras rivers has a much smaller impact on the contamination of the Ob-Irtysh river system, compared to the Techa river, prone to a large-scale radioactive contamination.