HYDROCHEMISTRY OF SPRING waters IN THE CENTRAL PART OF CHARA DEPRESSION, NORTHERN TRANSBAIKALIA
V.A. Palamarchuk1,2, L.S. Lebedeva3, N.A. Pavlova3, A.P. Ginzburg4
1Sergeev Institute of Environmental Geoscience, Russian Academy of Sciences, Moscow, Russia
2Tyumen Research Centre, Siberian branch of the Russian Academy of Sciences, Earth Cryosphere Institute, Tyumen, Russia
3Melnikov Permafrost Institute, Siberian Branch of the Russian Academy of Sciences, Yakutsk, Russia
4Federal Research Center "Pushchino Scientific Center for Biological Research of the Russian Academy of Sciences", Institute of Physico-Chemical and Biological Problems in Soil Science, Pushchino, Russia
Keywords: sandy massifs of the cryolithozone, aquifers, springs, hydrochemical research, Eastern Siberia, Сhara depression
Abstract
The study examines the chemical composition of spring waters in the central part of the Chara basin and its evolution over the past four decades. The current chemical composition of the spring waters is characterized as magnesium-calcium bicarbonate with total dissolved solids (TDS) ranging from 36 to 162 mg/L and fluorine content varying between 0.01 and 4.0 mg/L. This research presents, for the first time, data on the stable oxygen and hydrogen isotopes in the springs of the “Sands” massif. The isotopic composition of these springs is as follows: δ18O = (-16.95 ± 0.69) ‰, δD = (-130.20 ± 4.42) ‰, dexc = (5.40 ± 1.38) ‰. The combined results of chemical and isotopic analyses suggest the involvement of glacial waters from the Kodar mountains in the formation of the springs within the massif. These springs are formed through the mixing of waters from aeolian and lacustrine-alluvial deposits with more mineralized intrapermafrost waters of fluvioglacial deposits. The degree of participation of waters from different aquifers is reflected in the fluorine content and isotopic composition of springs. The first aquifer system waters have a heavy isotopic composition and contain less fluorine (0.4-2.0 mg/L). The waters from the second aquifer system have a light isotopic composition and a fluorine content of 2-4 mg/L or more. Over the past 40 years, a decrease in mineralization, the content of Na+ + K+, Cl- and F- in spring waters indirectly indicates an increase in the share of glacial runoff in their nutrition.
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