Peculiarities of radionuclide migration in main links of water reservoir

Rate of radionuclide uptake by phyto- and zooplankton as well as by other hydrobionts depends on many accompanying factors (residence medium temperature, water pH value, a season, cheical composition of an organism, rate of exchange processes, etc.). Zooplankton accumulates radionuclides mainly to a lower extent than phytoplankton. Protococcus accumulates 106Ru up to values, exceeding the radionuclide content in water thousand times, during a short time (about a day), then the alga radioactivity gradually decreases and by the 30 th day exceeds the water radioactivity just 3 to 4 times. In many species of zooplankton the duration of the uptake process for most of radionuclides, to attain the equilibrium, makes up several days. Zooplankton organisms are characterized by low content of calcium, potassium and such radionuclides as 89Sr, 90Sr, 137Cs, 140Ba, 226Ra