[Phytoplankton and zooplankton of the industrial reservoir R-9 (Lake Karachay)].

Planktonic communities of the Reservoir-9 (Lake Karachay, storage reservoir of liquid medium-level radioactive waste of the Mayak Production Association) are exposed to the severe radioactive forcing (in 2010 the total beta-activity of the water was 1.8 x 10(7) Bq/L, total alpha-activity was 1.1 x 10(4) Bq/L), aswell as to the chemical contamination (level of nitrates in water 4.1 g/L). The calculated values of the absorbed dose rate were 130 Gy/day for phytoplankton and 4.0 Gy/day for zooplankton. Extremely low species diversity, the overwhelming dominance of one species (phytoplankton is close to a monoculture of ubiquitous cyanobacteria Geitlerinema amphibium, zooplankton--to a monoculture of rotifers Hexarthrafennica), wide fluctuations in numbers of algae, a low number of zooplankton were the most substantial characteristics of the plankton communities in Lake Karachay. So, plankton communities status is a sign of environmental retrogress in this ecosystem.

[Experimental assessment of combined effect of nitrates and acute gamma-irradiation on green algae Scenedesmus quadricauda growth].

The combined effect of acute gamma-irradiation at doses of 0, 50, 100, 150 and 200 Gy and nitrates in concentrations of 0.04 g/dm3 (that corresponds to maximum permissible concentrations for fishery waters), 0.1, 0.25, 0.5, 1.0, 2.5 g/dm3 (that is close to NO3(-) level in water of a reservoir R-17 used as radioactive waste storage of the "Mayak" Production Association) and 5.0 g/dm3 (that is close to NO3(-) level in the water of radioactive waste storage reservoir R-9) on the unicellular green algae Scenedesmus quadricauda growth has been studied in laboratory conditions. It was shown that the joint effects of nitrates and y-radiation had an antagonistic character. Thus, it may be concluded that chemical pollution is the factor limiting the development of green algae in reservoir R-17; probably, both factors, chemical and radiating, are essential to the algocenosis degradation in reservoir R-9.