ENVIRONMENTAL STANDARDIZATION OF WATER QUALITY IN REPRESENTATIVE SECTIONS OF THE DNIESTER RIVER

Abstract

The development of environmental standards that will limit anthropogenic pressure on natural and modified water bodies of Ukraine and improve their environmental safety is a prerequisite for the preservation and restoration of their aquatic ecosystems. The scientific substantiation and establishment of ecological norms for surface water quality was carried out on the example of representative sites in the Dniester River basin (near the towns of Zalishchyky and Mohyliv- Podilskyi), which differ in physical and geographical location, natural conditions of water quality formation, level of anthropogenic pressure and different sectoral distribution of water use. The basis for the development of ecological norms was the results of an environmental assessment of water quality at selected design levels: 1964, 1973, 1985, 1995, 2000, 2005 and 2021 which were similar in terms of water content (average and close to average water content). The spatial and temporal specificity of natural conditions and anthropogenic factors of water quality formation in the represented sections of the Dniester River was studied to substantiate the values of ecological norms. The optimal and permissible values of the ecological water quality norms (EN(o) and EN(d)) of the Dniester River in the area of Zalishchyky and Mohyliv-Podilskyi for 21 priority indicators (in absolute values and categories). They are grouped into blocks: salt composition (3 indicators), tropho-saprobiological (10 indicators) and specific substances of toxic effect (8 indicators). The block indices (I1, I2, I3) for EN(o) and EN(o) were determined. It is determined that the optimal values most fully correspond to the natural characteristics of water quality and are most desirable in water protection activities, while the permissible values reflect the inevitable deviations of water quality indicators towards deterioration due to the instability of environmental conditions. The current state of water quality in representative sections of the Dniester River was studied to determine whether it meets the developed ecological norms, whether the background level of pollution is exceeded, and a list of priority substances that need to be controlled was identified.