PRESENT-DAY FLUORINE CONCENTRATION IN THE OB RIVER WATER

Based on the potentiometric measurements average fluorine concentrations for different phases of the hydrological regime were determined in water samples taken in 2018-2020 in the outlet of the Ob River: 0,103 mg/L in the winter low-water period, 0,079 mg/L in the spring - summer flood, and 0,095 mg/L in the summer - autumn low-water period. The present-day weighted average concentration of fluorine in the Ob River water (0,086 mg/L) closely corresponds to the values measured in 1954-1956 and 1976-1980 (0,090 and 0,084 mg/L, respectively), therefore the fluorine content of 0,08-0,09 mg/L could be taken as a natural background.