[Radionuclide transfer by migratory birds]

Evaluation of the zoogenic transfer of radionuclides from the 30-km zone around the Chernobyl NPP was necessary because of the enormous heavily polluted territory and mighty flow of migratory birds who tended to large rivers, the Dnieper and Pripyat. The integral estimate of the transferred amount was obtained as a product of three variables: the transfer factor (0.0077 m2/kg for 137Cs; 0.0107 m2/kg for 90Sr), the density of birds (0.002 kg/m2, at the mass of migrants about 5000 t per year), and the total fund of radionuclides throughout the territory. The upper estimated limit of the annual transfer rate was 5.5 Ci (2E + 11 Bq) for 137 Cs and 1.8 Ci (6.7E + 10 Bq) for 90 Sr. Restrictions of hunting are recommended within the northern part of the Kiev reservoir.