Modern ecological condition of surface waters of Trubizh river

Abstract

The problem of environmental safety of water bodies is relevant today, especially for the basins of small and medium-sized rivers, which are clear indicators of the environment state. One of them is the Trubizh River. The water resources of this river are formed under the anthropogenically changed conditions of the drainage and humidification complex of the Trubizh reclamation system. These resources are also receivers of effluents from point and diffuse sources. Thus, there is a need for constant monitoring of the ecological condition of the river. The water quality of it is a consequence of anthropogenic activities in the watershed. The aim of the work is a comprehensive assessment of the Trubizh River ecological condition under the modern conditions of water quality formation. The analysis has been conducted using official data from the state monitoring of water quality for 2015-2019 years and our own research for 2015-2016 years. 7 observation points have been considered from souse to mouth of the river: border areas of Brovary and Baryshivka; Baryshivka – 1 km above and 0.9 km below the village, Pereyaslav-Khmelnytsky – 0.5 km above and 1 km below the town, the mouth of the Alta and Trubizh rivers). We used such methods as analytical (determination of water quality indicators according to generally accepted standardized methods); analysis, systematization and generalization of the monitoring database; method of calculation of integrated block indices and complex ecological index of water quality (IE). It is established that during the five-year period (2015-2019) according to the weighted average and the worst values of the complex ecological index (IEworst 4.2) the waters are characterized as "satisfactory", "slightly polluted" of the III class quality 4 category. In 2018 and 2019 years, there was a deterioration in water quality by one category (III quality class 5 category) - "mediocre", "moderately polluted" water. This is due to a set of conditions of natural and climatic (insufficient rainfall and rising air temperature) and anthropogenic nature (water pollution, unauthorized surface water abstraction, runoff obstruction, etc.). It is noted that Trubizh river is characterized by stable uniform spatial water pollution. The largest values of IE are recorded in the area of influence of the village Baryshivka (IE worst 3.7-3.8) and Pereyaslav-Khmelnytskyi in the sampling points: the Alta river mouth (IEworst 4.0) and the Trubizh river mouth (IEworst 3.7). The water quality in these sampling points corresponded to class III of category 4 and was generally characterized as "satisfactory", "polluted". In general, the deterioration of water quality is caused by organic pollution (according to the indicator of dichromate oxidation (IV class, 6 category), BOD5 (Biochemical oxygen demand) (III class, 5 category), nitrogen compounds (ammonium, nitrite and nitrate) – V class, 7 category) and phosphorus compounds (phosphate ions – III class, 5 category), total iron and general chromium – III class, 5 category, phenols and SSAS (synthetic surfactants active substances) – IV class, 6 category. Thus, one of the main reasons for the degradation of the river is the anthropogenic conditionality of its development as a result of the urbanized and agricultural areas impact. The obtained data open the prospect of continuing work on monitoring and assessing the ecological status of aquatic ecosystems of the Trubizh River for the further development of scientifically based recommendations. It is necessary for making management decisions for sustainable use and protection of surface waters and restoration of aquatic ecosystems of Trubizh River Basin.