Ухань О. А.

Purpose. To carry out the surface water quality assessment of the Southern Bug river basin and to inves-tigate the ability of surface water to self-purify. Methods. Statistical calculations, system analysis. Results. The long-term dynamic of the integrated quality index values of the Southern Bug during 2000-2016 was heterogeneous, but the general trend indicated a slight increase due to the sanitary-ecological index and pollution index. The highest level of water pollution was observed in Khmelnytsky city and Alexandrovka settlement. To assess the self-purification capacity of surface waters, the hydrological zoning of the basin was taken. According to it three regions were identified by the types of intra-annual runoff distribution: Verkhnyobuzky, Serednyobuzky and Nizhnobuzsky. The obtained results of EC coefficient calculations for mineral nitrogen compounds show the inability of rivers to self-purify for Verkhnyobuzky and Serednyobuzky regions. Instead, the ability to self-purify is preserved for phosphorus compounds.Using the nonparametric Mann - Kendall test allowed to estimate the long - term trend of nutrients for the Nizhnobuzsky hydrological region. Trends N-NO3-, N NH4+and Р-РО43- are characterized by positive values of the statistical parameter, which means the increasing of these elements’ concentrations. Conclusions. Rivers of the Southern Bug basin are classified as "good, clean enough". The main ecologi-cal and hydrochemical problems of the river are pollution by nutrients and indicators of toxic action. The results of the self-purification criterion calculations indicate their inability (in the upper and middle parts of the basin) to self-purification. Using of the nonparametric Mann-Kendall test for determining changes in nutrient compounds shows an upward trend, that means increasing of their concentrations.

Purpose. Features spatial-temporal distribution of major ions, organic matter and nutrients downstream. Methods. The chemical-analytical. Results. The results of spatial and temporal distribution of chemical elements by the length Southern Bug river. It was shown that changes of major ions concentrations due to the location of the natural features of the river. The long-term dynamics of nutrients in the water of the river Southern Bug and the estimated impact of Khmelnitsky city on it condition were studied. Conclusions. The surface water of the river within the influence of Khmelnitsky city characterized by chronic pollution of ammonium nitrogen and phosphorus mineral.