MONITORING OF THE WATER QUALITY OF THE STRYI RIVER

Abstract

The work is devoted to water quality monitoring of the Stryi River (Lviv region, Ukraine) according to some hydrophysical and hydrochemical parameters of water quality for fish farming waters. The research was conducted in the spring-autumn period during 2022–2023, in places where there are no stationary creatures. Deterioration of the natural water quality of the Stryi River due to excessive anthropogenic influence has been established. In the studied water samples of the Stryi River, an increased content of suspended substances (by 1–1,4 mg/dm3), ammonium ions (by 0,5–0,8 mg/dm3), nitrite ions (by 0,2 mg/dm3) was recorded. dm3) and chemical oxygen consumption (by 1–2 mg/dm3). It was found that the main causes of these negative changes are insufficiently treated or untreated wastewater from the residential and communal sector, effluents from recreational and agricultural activities, as well as effluents from industrial productions. The transboundary nature of the pollution of the Stryi River has been established, as a result of the accumulation of harmful substances downstream of the water body, which is associated with an increase in the impact of human activity. In the water sample taken in the upper part of the watercourse below the mouth of the Zavadka River (where the anthropogenic impact on the water body is the least), the content of suspended solids, ammonium ion and nitrite ions does not exceed the normalized values for waters intended for fishing. In the water samples taken downstream, namely below the mouth of the Ilnyk and Opir rivers, an increased content of the specified hydrochemical parameters can be traced. It was established that the determined hydrophysical and hydrochemical water quality indicators of the Stryi River are characterized by minimal dispersion in different phases of the water regime and seasonally throughout the year, which indicates positive hydrodynamics of the watercourse. Most of the standardized indicators that characterize the quality of surface waters do not exceed the maximum permissible concentrations for waters used for fishing, which indicates the II class and 2–3 category of water quality of the Stryi River.