Environmental Assessment of Surface Water Quality in the Umanka River Basin

Abstract—

The intense pollution due to increased anthropogenic load on the water catchment areas is a problem of small rivers. Changes in the hydrochemical regime of small rivers have an impact on large rivers as well, since the former feed the latter with transfer of pollutants from the land. Agricultural and communal water pollution of small rivers can be the cause of degradation of the river system. Therefore, systematic monitoring and comprehensive evaluation of the water quality of small rivers against the background of climatic changes and low water is an urgent problem for the water management of Ukraine. This study is aimed at assessing the ecological state of the Umanka River (the left tributary of the Yatran’ River) in a certain period of time, which makes it possible to follow changes in water quality under the influence of anthropogenic factors and natural and climatic conditions of low water. Based on the results of analytical measurements of water samples of the Umanka River bed, the following block indices of water quality are calculated: index I₁ of contamination by the components of the saline composition (the sum of the Cl^– and \({\text{SO}}_{4}^{{2 - }}\) ions); ecological and sanitary index I₂ (\({\text{NH}}_{4}^{ + }\), \({\text{NO}}_{2}^{ - }\), \({\text{NO}}_{3}^{ - }\), PO, and pH); and index I₃ of specific indicators of toxic action (Fe_tot, Cd, Pb, Cu, and Zn). According to hydrochemical parameters, the Umanka River water—which is a potential source of drinking water supply—is contaminated with nitrogen compounds \({\text{NH}}_{4}^{ + }\), \({\text{NO}}_{2}^{ - }\), and \({\text{NO}}_{3}^{ - }\), and with Cd and Pb, and has a high level of permanganate oxidation exceeding the fourth class level of surface water quality. A comprehensive ecological assessment of the river water with values ranging from 3.51 to 4.36 along the stream is carried out, and the water quality is characterized as transitioning from “good” and “fairly pure” to “satisfactory” and “slightly polluted” with a tendency to approach “mediocre” and “moderately polluted”, while the Umanka River water in 2004 was classified as “good” and “fairly pure”.