[Untitled]

The contents of 90 Sr and 137 Cs and the pattern of their redistribution in the soil and plant cover of floodplain ecosystems have been assessed. It is shown that the radionuclide distribution across the floodplain and along the river flow is determined by the formation of a barrier to their migration near the river channel, at which less mobile 137 Cs accumulates. The soil and plant cover of the central floodplain are enriched with 90 Sr. Differences in radionuclide migration in floodplain soils and their input into plants are determined by the rela- tionship between the processes of their immobilization and migration with soil water.