ANALYSIS OF PRESSURES FROM THE BIOGENIC AQUATIC ECOSYSTEM OF THE HORYN RIVER

Abstract

The purpose of our work was to analyze loads of biogenic surface waters of the Horyn River. The objectives of the studies were to monitor nitrate ion and phosphate ion, followed by an assessment of the environmental status of surface waters, and to establish the relationship between nitrate and phosphate. We determined the direction of eutrophication and deficiency of one of the elements in the river’s aquatic ecosystem. Data from the 2005–2021 monitoring program of the State Water Resources Agency of Ukraine were used in the studies. Thus, according to our studies, there has been a general downward trend in the concentrations of nutrients such as nitrates and phosphates, with variations from year to year. The average nitrate ion content was higher than the source of the river (checkpoint 1) than the area near the mouth (checkpoint 2) by more than three times. The average phosphate ion content doubled within the second flank compared to the first. During the observation period, environmental assessment of the quality of the surface waters of the Horyn River in terms of nitrate content revealed fluctuations in the quality of nitrate content from category 2.5 (water condition «very good – good») within the second section to category 7.0 (water condition «very bad») in the first view. In terms of phosphate content from category 2,3 (water state «good») in the first section to category 5,8 (water state «bad») within the second section. The nitrate content of both vents did not exceed the regulatory value. The phosphate content was found to exceed the fishery boundary concentrations and the norms of the European Union Directive, in the first case only up to 2007 and in the second case only up to the 16-year observation period.The calculation of the stoichiometric ratio of nitrates to phosphates revealed an average of 68.26 within the first flank and 40.63 within the second flank. Thus, phosphates are the limiting element at both Нoryn sections of the river, and green algae dominate phytoplankton groups, with a marked increase in eutrophication within checkpoint 2.