ENVIRONMENTAL ASSESSMENT OF SURFACE WATER QUALITY OF THE BASIN OF THE INGULETS RIVER IN THE MIDDLE REACHES

Abstract

According to the results of analytical studies revealed that the hydrochemical regime is divided into three parts of the Ingulets river: upper (from Alexandria to Krivoy Rog), middle (from Krivoy Rog to Snigirevka), lower (from Snigirevka to the mouth). Gradual decrease in surface water quality due to discharges of insufficiently treated wastewater of Znamenka and Alexandria, Kirovograd region. A significant deterioration in water quality begins from the observation point at the Karachun Reservoir. The worst indicators of hydrochemical composition of waters are recorded near the village of Andreevka, which is located within the Dnipropetrovsk region, the lowest downstream of the Ingulets river, on the border with the Mykolaiv region. Based on the analysis of the dynamics of the hydrochemical composition of the waters of the Ingulets river, an intensive anthropogenic impact on surface waters during the course within the Krivoy Rog iron ore basin was recorded, which is manifested primarily by increased mineralization and high content of sulphates and chlorides. For example, during 2005-2017 the average annual content of dry residue in the waters of the Ingulets river in the middle and lower reaches varied from 0.7 g/l in thevillageofPetrovoto 3.6 g/l in thevillageofArkhangelsk, Dnipropetrovsk region. On the basis of environmental assessment of surface water quality in the relevant categories established: - the waters of the Ingulets river for the period 2005-2006 and 2015-2018 for most of the channels belong to the II class of water quality «Good», the corresponding category 3 «Good» and to the II class of water quality «Clean» in terms of their purity (pollution), the corresponding category 3 «Sufficiently clean»; - the waters of the Ingulets river at the observation point of Andreevka village on 15.08.2005 are characterized by the worst indicators and belong to the II class of water quality «Good», the corresponding category 3 «Good» and to the II class of water quality «Clean» in terms of their purity (pollution), the corresponding category 3 «Sufficiently clean»; - water of Yellow river for the period 2005-2006 and 2015-2018 for most of the sites belong to the THIRD quality class «Good», corresponding to category 3, «Good» and to III class of water quality «Contaminated» according to their degree of purity (contamination), corresponding to category 4 «Cabosanlucas». The calculations showed that the environmental assessment of surface water quality in the relevant categories needs to be improved, as it does not take into account the priority of the identified pollutants typical for areas with developed mining industry. This is contrary to the detected non-compliance of the quality of the waters of the Ingulets river to meet the needs of the local population for recreation, drinking water and irrigation without additional measures. In accordance with the requirements of SanRN (sanitary regulations and norms) 2.1.5.980-00 found: excess MPC (maximum permissible concentration) in terms of – aluminum, BSC5, pH, hardness, odor, iron, manganese, sulfates, dry residue, chlorides; excess MPC is not observed in terms of (dissolved oxygen, copper, nitrites, nitrates, phenols, chromium. Thus, the deterioration of social conditions is observed in the middle and lower reaches of the Ingulets river, due to the anthropogenic impact of mining enterprises of the Krivoy Rog iron ore basin on the quality of surface waters. Significant amplitude fluctuations of hydrochemical indicators, mainly due to discharges of mine waters. Annually, waste water of mining enterprises of the Krivoy Rog iron ore basin is accumulated in the pond-storage beam Svistunov, where before the irrigation period, usually in November and February, controlled discharge volume of 9.6-11.7 million m3 to the Ingulets river. Mineralization of accumulated mine waters in the Svistunov basin reaches 41 g/l. Improvement of the water situation is achieved by annual washing of the Ingulets river bed, which leads to a temporary improvement in water quality. After its completion in 2-3 months the chemical composition of surface waters deteriorates significantly. However, according to the method of water quality assessment, they are classified as «good» and «clean», which does not correspond to their actual condition. Therefore, additional post-treatment of surface waters is necessary for their further use for domestic purposes.