Generalized studies of the world scientific literature on the fate and risk assessment of exposure to silver nanoparticles (NPAg) both at the ecosystem level and at the organism level, as well as in the laboratory. It is emphasized that the toxic effect of silver nanoparticles, mechanisms and methods of action of NPAg on the body of aquatic organisms have been sufficiently studied in laboratory practice. However, there are some gaps and discrepancies between the results of laboratory tests and the study of real environmental consequences, and such inconsistencies hinder the development of appropriate effective measures to achieve environmental well-being. To bridge such gaps, this review summarizes how environmental conditions and the physicochemical properties of NPAg influence conflicting conclusions between laboratory and real-world environmental studies. It is emphasized that modern research on the pathways of entry, transformation and bioaccumulation of silver nanoparticles in natural aquatic ecosystems emphasizes the ability of such nanoparticles to penetrate intact physiological barriers, which is extremely dangerous. It is proved that silver nanoparticles have a toxic effect on microorganisms, macrophytes and aquatic organisms. The toxic effects of NPAg cover almost entire aquatic ecosystems. A study by a number of authors on the factors influencing the mobility, bioavailability, toxicity and environmental fate of Ag nanoparticles was analyzed to assess the environmental risk. In addition, this review systematically examines the various toxic effects of silver nanoparticles in the environment and compares these effects with the results obtained in laboratory practice, which is useful for assessing the environmental effects of such compounds. The dangerous chronic effects of low-concentration NPAg (μg/l) on natural aquatic ecosystems over a long period of time (months to several years) have been described in detail. In addition, the prospects for future studies of NPAg toxicity in natural freshwater environments are emphasized. Key words: nanoparticles of the medium (NPAg), ecosystem, laboratory wash, toxicity, aquatic organisms, ecological factors.

The Ros River is polluted with heavy metals, petroleumproducts and organic matter due to the activities of variousindustries, including agriculture (washing away pesticides and fertilizers), food, light and petrochemical industries, etc.Intake of drinking water in Bila Tserkva district is carried outfrom the river Ros, so the aim of the work was to systematizethe results of research over the past 10 years and identify thedynamics of changes in the ecological state of the river.Object of research: Ros River within Bila Tserkva district of Kyiv region.Subject of research: negative environmental factors,water quality indicators. The study of the state of the question was carried out by methods of analysis and synthesis.Water quality assessment was conducted in the Ros Riveron a monthly basis. Initial data (monthly results) are averaged by seasons: spring (March-May, 2010-2020), summer(June-August, 2010-2020), autumn (September-November,2010-2020), winter (December of the previous year - January, February of the current year, 2010/2011-2020/2021).Among the studied indicators there are ammonium salt, nitrates, nitrites, chemical oxygen demand (COD), biochemicaloxygen demand (BOD5), phosphates, total iron, manganese.Seasonal concentrations throughout the study period for ammonium salt ranged from 0.11 to 2.17 mg/dm3, nitrites – from0.01 to 0.82 mg/dm3, nitrates did not exceed 40.0 mg/dm3,COD– in the range from 15.9 to 61.1 mg/dm3, BOD5– in therange from 1.5 to 8.3 mg/dm3, phosphates – from 0.05 to 0.49mg/dm3. Excess concentration of total iron and manganesewere observed in 59% and 29% of cases, respectively. Thatis, there is a tendency to deterioration water quality by somecomponents; the main reason for this is anthropogenic activity, namely the inconsistency of water treatment equipmentof economic entities with modern environmental standardsand the presence of unidentified sources of discharges intothe Ros River basin. Key words: Rosriver, hydrochemical indicators, ecological condition, seasonal values, MPC.