Monitoring of hydrochemical and toxicological status of the Don River waters near Stanitsa Romanovskaya (Rostov Region) in the late spring season of 2025

Background. The lower reaches of the Don River present the main habitat for the aquatic biological resources of the Southern Russia and play a crucial role in their reproduction. Through the ages, the current area of the Rostov Region supported active fisheries, including exploitation of sturgeons and other valuable fish species. Along with food security provision for the population, the Don River serves as an important source of potable and utility water. Relevance. Investigation of the water quality in the Don River as a living environment for aquatic biological resources presently remains relevant. The aim of this work is to analyse hydrochemical and toxicological parameters of the Don River water in the late spring season of 2025 near stanitsa Romanovskaya in the Rostov Region. This article initiates a series of publications presenting the results of ecological monitoring of the aquatic bioresource habitat in the lower reaches of the Don River. Methods. Collection of samples and identification of hydrochemical parameters have been conducted according to the standard research methods. Analysis for pollution with priority toxicants has been carried out in compliance with the methodological guidelines adopted at the federal level. Results. Content of dissolved oxygen in the water of the investigated area was 7.9 mg/dm3, concentrations of ammonium nitrogen and nitrite nitrogen were 0.085 and 0.029 mg/dm3, total dissolved solids were 470 mg/dm3, and the trophic level of the water (23 units) was indicative of the eutrophic status of the Don River near stanitsa Romanovskaya. Total content of petroleum products did not exceed the lower detection limits for the used methods of measurement. Anionic synthetic surface-active substances, organochlorine pesticides, and polychlorinated biphenils in the water and bottom sediments of the investigated area were not identified, and the content of iron, manganese, zinc, chromium, copper, lead, nickel, cadmium, mercury, and arsenic did not exceed MACs for the water bodies of fishery importance and was in line with the average long-term values. Conclusion. Results of this study indicate that the aquatic environment of the Don River near stanitsa Romanovskaya was favorable for aquatic living organisms.