Tritium in Natural Water of the Lena River Basin

The long-term dynamics of tritium content in atmospheric precipitation and in surface and ground water of the Lena River basin is characterized on the basis of new data obtained in 2019 and 2020 and historical information. The relationship between the tritium content and the concentration of dissolved chemicals is analyzed. In 2019 and 2020, during the periods of winter and summer low water, 44 water samples were taken from the Lena River, its large, medium, and small nonfreezing tributaries, intrapermafrost and subpermafrost groundwater, snow cover, and liquid precipitation. Data on tritium concentrations in the upper and middle Lena River and its tributaries are given for the first time. The element content in samples from river water, snow cover, and rain corresponds to its long-term descending curve. The tritium concentration in river waters during the winter low-water period is smaller than in the summer period, when its content in the rivers approaches its values in atmospheric precipitation. This testifies to the contribution of groundwater to river recharge in spite of the wide spread permafrost. Statistically significant correlations of the tritium content with the redox potential and the contents of bicarbonate, lithium, and sodium ions, total dissolved solids, and pH have been revealed.