Assessment of the quality of waters and bottom sediments of the Kamenka river by biotesting

The Kamenka River, which flows through the territory of the Kokuisky oil field in Perm Krai as a result of intensive oil production and the intensive karst spread, has undergone serious man-made changes, which are manifested in the increased content of chlorides and petroleum products in the water. We assessed the ecological state of the ecosystem of the Kamenka river by biotesting, using Daphnia magna Straus and Chlorella vulgaris Beijer as test objects. 8 water samples and 11 sediment samples were examined. Most of the studied sampling points located at the source of the river are distinguished by the presence of pronounced oil manifestations, a sharp smell of hydrogen sulfide, white flakes and a bright blue color uncharacteristic of natural waters. The percentage deviations of the optical density values in the studied samples from the background value, and the indicators of the toxic dilution factor (TDF) calculated from the control (distilled water) values are given. In all the studied water samples, the growth of chlorella algae (Chlorella vulgaris) is stimulated in comparison with the background, the highest percentage of deviation of the optical density value from the background is 112% in sample № 1, the lowest in sample № 5 is 26%. In two samples of bottom sediments: №1 and № 4, the optical density values significantly exceed the background indicator by 121 and 27%, respectively. The remaining samples of bottom sediments were characterized by a decrease in optical density compared to the background from 17 to 55%. The TDF of the studied water samples ranges from 6 - in Iren river (background), up to 26 - at point № 8, in samples of bottom sediments, the lowest value of TDF at the source of the river is 0.6, the highest is in sample № 8. Comparison of the optical density of the studied samples with the control indicator (on distilled water) is considered unacceptable, since the results are misleading and contradict reality. To assess the toxicity of natural and man-made waters, we consider the use of background indicators to be promising. The results with the use of Daphnia magna as a test object showed the insensitivity of this organism to the toxic effects of the studied samples. The maximum percentage of daphnia death in the test sample was 20% (8 surviving crustaceans out of 10), while the criterion of acute toxicity is the death of 50% or more daphnia.