Biotesting of the Iva river and its tributaries by measuring the optical density of Chlorella vulgaris beijer

The article gives an assessment of the quality of water in the Iva River (Perm), as well as its tributaries: Bolshaya Iva, Malaya Iva, Talazhanka and Uinka. The quality of water in the rivers was assessed using the method of toxicological control. The method is based on measuring the optical density of a culture of algae chlorella (Chlorella vulgaris Beijer). This biotesting method, due to its higher sensitivity relative to chemical methods of analysis, provides an opportunity for a comprehensive assessment of the content of pollutants in the aquatic environment. As a result of the work carried out, data were obtained on the change in the degree of toxicity of water from the sources of rivers to their mouths. A decrease in the optical density of chlorella and an increase in the degree of toxicity were observed for the waters of the Iva River and all its tributaries, except for the Uinka River. For the Iva River, a decrease in optical density by 58% relative to the mouth was revealed, which may be associated with an increasing degree of development of the river banks. The value of the toxicity dilution factor (TDF) for all rivers ranges from 3.95 to 32.43, which corresponds to a change in water quality from moderately toxic to highly toxic. The waters in the Bolshaya Iva River are the least toxic.