Diagnostics of the water body ecological state: Comparing results of chemical analysis, bioassay and bioindication

Abstract

Introduction: In the European Union, the Water Framework Directive (WFD) provides a legislative opportunity for an integrated approach to diagnosing the ecological state of water bodies, including chemical control, water bioassay, bioindication of pollution in terms of characteristics of aquatic communities and biomarkers in individual species. In the Russian Federation, we also use an integrated approach to conduct state environmental monitoring of water bodies. However, not all water bodies are covered by state monitoring points. Information on most of them comes from water users conducting industrial environmental monitoring, which does not include assessment of biota condition in the water body used. In this paper, we show that in some instances perennial observations of the chemical composition of wastewater (and natural waters it is discharged into) are not informative from an environmental point of view. Comparison of the results of industrial monitoring and researches in the field of reservoir bio-diagnostics will allow defining the ecological state of the water body and, in future, its transformation trend. Methods and materials: We examined Ivanovskoye Lake (Russia, Kirov Region) of bayou type, receiving wastewater from a thermal power plant (TPP) and simultaneously communicating with the Vyatka River — a source of drinking-water supply. The chemical composition of wastewater from the TTP and surface waters of the lake was analyzed. The results were compared with the bioassay data regarding response of Daphnia magna, Scenedesmus quadricauda, Paramecium caudatum, Escherichia coli and bioindication data regarding the species composition of the coastal aquatic vegetation. Results: Ammonium ions and organic substances (according to biochemical oxygen consumption for 20 days) turned out to be priority pollutants. The maximum concentration of ammonium ions reached 3.17 mg/dm3, which is 6 times higher than the standard value in Russia. In one of the wastewater sources, water is alkaline (pH — up to 9.01). In the bioassay for the mortality of D. magna, toxicity was not established. Most samples had no effect on test organisms or were moderately toxic. The water samples from the lake had a stimulating effect on S. quadricauda, P. caudatum, E. coli, which indicates eutrophication of the reservoir. According to the analysis of coastal aquatic vegetation indicator species, Ivanovskoye Lake is of mesotrophic type. The number of pollution indicator species increases when approaching wastewater sources. Conclusion: In general, the bioindication results show deeper anthropogenic changes than those revealed using chemical methods and bioassay. Such data demonstrate both feasibility of combining industrial monitoring with scientific research, and changes in the list of the chemical as well as physical and chemical parameters observed.