Khokhlova L. The role of bivalve mollusks of the genus Dreissena in the removal of heavy metals from the water of the irrigation systems in the South of Ukraine

Dissertation for the degree of Doctor of Philosophy in the field of Natural sciences in the specialty 101 “Ecology” (10 ‒ Natural sciences). ‒ Taras Shevchenko National University of Kyiv. ‒ Educational and Scientific Center "Institute of Biology and Medicine" Taras Shevchenko National University of Kyiv, Kyiv, 2021. Irrigated agriculture is a significant consumer of water in agriculture. The primary task in organizing a balanced rational water use in the process of Ukraine's transition to sustainable development is to provide the agricultural sector with high quality irrigation water. The content of heavy metals in irrigation water is an important indicator of its environmental safety for irrigation. Most of Ukraine's arable agricultural land is located in the Southern Arid Region. There, the Kakhovka irrigation system was created, on an area of 318.6 thousand hectares, including the Main Canal and distribution canals. The only source of their filling is the water from the Kakhovka reservoir on the Dnipro river, which is characterized by the greatest pollution among the entire Dnipro cascade of reservoirs. Bivalves, which are today used as biomonitors for studying the state of the aquatic environment, play an important role in the migration, accumulation, and bio-sedimentation of pollutants in hydroecosystems. Their dense settlements at hydraulic structures can significantly influence the processes of cleaning the water column from suspensions and heavy metals. The presented work considers the influence of periphyton settlements of bivalve mollusks of the genus Dreissena as a biotic factor determining the quality of the irrigation water in the Kakhovka irrigation system. Under the conditions of anthropogenic pollution of the water intake, the Kakhovka reservoir on the Dnipro river, Dreissena was used as a classical marker group of the structural and functional organization of hydrobiocenosis, common among invertebrates, sensitive to environmental factors.