Dynamic models for estimating radiation doses to hydrobionts in a freshwater ecosystem.

A model of radionuclide transfer in freshwater bodies, along with dosimetric models for estimating doses to aquatic biota species (including phytoplankton, zooplankton, zoobenthos, and fish), is presented. The results of the reconstruction of radiation doses to aquatic organisms living in the closed (non-flowing, lentic) Lake Uruskul, located in the vicinity of the Kyshtym accident, are provided. The contributions of the main dose-forming radionuclides, as well as both internal and external exposures, to the doses received by aquatic organisms over the 50 years following the Kyshtym accident are discussed. It is shown that benthic organisms received the highest doses (2.6-8.3 Gy per day), while zooplankton experienced somewhat lower doses (up to 3.3 Gy per day). Fish received doses of up to 4 mGy per day during the first 100 days. Phytoplankton, with doses reaching up to 0.5 Gy per day, occupied an intermediate position in this sequence. These doses could lead to long-term radiation effects.