ECOLOGICAL ASSESSMENT OF THE CONTENT OF HEAVY METALS IN FISH OF THE RIVER IRTYSH

The article presents the results of a study of surface waters and fish (perch (Perca fluviatilis L.), carp (Cyprinus carpio L.), bream (Abramis brama L.), pike (Esox lucius L.) of the Irtysh river. The content of Cu and Pb in the organs and tissues of fish living in the Irtysh River within the city of Semey was determined by the ditizon photometric method. The ecological assessment of the results indicates that the concentrations of Cu and Pb in the studied fish specimens do not exceed the MPC. A significant difference in the specific features of the accumulation of heavy metals has been established, depending on the type of fish nutrition and the time of year. The Pb content in various organs of perch, carp, bream and pike ranges from 0.062 mg/kg to 0.083 mg/kg. The highest concentration of Cu is observed in predatory fish (3.27 mg/kg), the lowest – in planktonivores (2.82 mg/kg). Pb also mainly accumulates in pike (0.073 mg/kg). In spring, the content of Pb in the gills of perch and pike increases, Cu – in the gills of bream and pike. The maximum concentrations of Cu in fish were observed in summer, which is associated with an increase in the food supply. The Pb content in summer, on the contrary, decreases due to its adsorption by suspended solids and deposition with them into bottom sediments.