The current status of the Kambileyevka River and its tributaries

Abstract

Relevance. Mining is the most waste-intensive industry. As a result of the activities of non-ferrous metal processing plants, millions of tons of wastes have accumulated, which have led to significant pollution of adjacent territories, including surface waters. The aim of this work is to assess the current state of the surface waters of the Kambileyevka River basin in terms of the content of potentially toxic elements and nitrogen and phosphorus compounds. Materials and methods. A comparative analysis of the surface waters pollution of the Kambileyevka River (Republic of North Ossetia-Alania) and its tributaries was carried out during the operation of “Electrozink” (2004–2018) and 7 years after its closure. The study of the current state of surface waters was conducted in 2025. Concentrations of Al, As, Cu, Mn, Mo, Pb, and Zn were determined using atomic absorption spectrometry (AAS). The concentrations of nitrites, ammonium, and phosphates were determined by capillary electrophoresis. Results. During the period of operation of the enterprise, concentrations of copper, manganese, cadmium and molybdenum in the Kambileyevka River varied within 3-5.5 MACfish. 7 years after the closure of the enterprise, the concentrations of these metals do not exceed the maximum permissible concentration. Zinc concentrations remained elevated to 6 MACfish. During the operation of the plant, high concentrations of zinc were recorded up to 11–19 MACfish. In the Sobachya Balka River, a decrease in concentrations of potentially toxic elements was manifested much greater. Concentrations of cadmium and molybdenum decreased by 5 times, manganese and copper by 10-12 times. Zinc concentrations remained the same 6 MACfish. (excluding 2007 and 2013). Currently, the increased zinc concentrations correspond to the level of natural pollution and are explained by the presence of geochemical anomalies in the region. In the Kambileyevka River, the content of ammonium and phosphates decreased, while nitrites remained high (8.4 MACfish.). There is an increased level of pollution with nitrites, ammonium and phosphates in the Sobachya Balka River. Thus, the closure of “Electrozink” led to a decrease in heavy metal concentrations to the level of natural pollution. Ion pollution remained high, which indicates another source of their intake.