ASSESSMENT OF THE ECOLOGICAL STATE OF THE SEIM RIVER IN THE CONTEXT OF TRANSBOUNDARY POLLUTION

Abstract

Preservation of the quality of transboundary water resources of Ukraine in conditions of military aggression of the aggressor state becomes particularly urgent, since the destruction of industrial infrastructure in adjacent territories leads to emergency discharges of highly concentrated pollutants into border river systems. The events of August–October 2024 became a vivid example of such an ecological threat: in the Seim River basin, large-scale fish mortality and a sharp deterioration in the hydrochemical parameters of water were recorded, which is associated with emergency discharges of waste from industrial enterprises, in particular the Tyotkino Sugar Plant in the Kursk Region. Wastewater from the sugar industry is characterized by an extremely high organic load (BOD up to 7,000 mgO₂/dm³, COD up to 10,000 mgO₂/dm³), an increased content of ammonium, suspended substances and compounds capable of reducing pH and creating oxygen deficiency in aquatic ecosystems. Such processes demonstrate the critical vulnerability of transboundary water systems to military risks and confirm the need to modernize the national monitoring system and harmonize it with European environmental standards. The purpose of the study is to assess the current hydrochemical state of the Seim River in Ukraine under conditions of transboundary pollution caused by accidental discharges of organic compounds from industrial facilities of the aggressor state during active hostilities. The study was carried out based on the analysis of physicochemical indicators of water quality (pH, content of ammonium nitrogen, sulfates, chlorides, nitrites, nitrates, total iron, chemical and biochemical oxygen demand) in accordance with the current DSTU ISO standards. For comparison, multi-year hydrochemical data (1967–1979; 1993–2013) and current monitoring results in 2024 were used. The results obtained indicate that most of the main water quality indicators (pH 7.3–7.4; sulfates ≈40 mg/dm³; chlorides 29.4 mg/dm³; nitrites 0.02–0.06 mg/dm³; nitrates 0.75–1.0 mg/dm³) remain within ecologically acceptable levels and even below the long-term average values. At the same time, a significant excess of the concentration of total iron (0.37–0.79 mg/dm³ at a maximum concentration of 0.1 mg/dm³) and organic load was recorded: CSC reached 58–60 mgO₂/dm³ (at a norm of 50 mgO₂/dm³ and a historical average of 18.1 mgO₂/dm³), BOD₅ – 7.3–7.4 mgO₂/dm³ (at a norm of 3 mgO₂/dm³ and a long-term average of 2.8 mgO₂/dm³). Increased iron concentrations can have both a natural origin (inflow from swampy soils and groundwater) and be enhanced by transboundary technogenic impacts. The high level of organic pollution directly correlates with emergency discharges of wastewater from sugar and related industries during the period of hostilities. The scientific novelty of the work lies in the identification and quantitative assessment of the hydrochemical response of a transboundary river to military-induced man-made discharges, which was documented for the first time for the Seim basin based on a combination of multi-year data and current observations in 2024. The practical significance lies in substantiating the need for integrated basin management and harmonization of the environmental monitoring system of Ukraine with the EU Water Framework Directive (Directive 2000/60/EC …, 2000) for early detection of transboundary environmental crises and legal documentation of damage from war crimes against the environment.