SPATIAL VARIABILITY OF THE INTENSITY OF MERCURY ACCUMULATION IN THE MUSCLES OF DIFFEREENT-SIZED PERCH FROM THE RYBINSK RESERVOIR

The study investigates the relationship between the mercury (Hg) content in the muscles of the perch Perca fluviatilis L., 1758 from different areas of the Rybinsk Reservoir including tail-water of the Uglich hydroelectric power plant, which differ in their physico-chemical characteristics, and the length of the fish. The measurement of Hg was carried out using the atomic absorption method on a RA-915+ mercury analyzer with the PYRO prefix (Lumex), without any preliminary sample preparation. The detection limits for Hg concentrations in biological samples on this device range from 0.0005 to 2.0000 mg/kg. Average metal concentrations ranged from 0.04 to 0.87 mg/kg of wet weight for fish with an average length of 2.2–45.0 cm, and differed by reservoir sections. The magnitude of effect of the fish length on the metal content in fish muscles was determined by the slope of the regression line, which indicates the rate of Hg accumulation, and the intercept of the line on the Y-axis representing the baseline level of Hg in organisms at the beginning of the food chain for each specified group. It was found that the maximum intensity of Hg accumulation is attained in the perch of up to 10 cm long and then significantly decreased in larger fishes, variably depending on the sampling area within the Rybinsk Reservoir.