Home – Home – Jornals – Earth’s Cryosphere 2022 number 2

We studied the distribution of fluoride (F^-) in fresh and moderately mineralized waters of subpermafrost aquifers of Central Yakutia. We analyzed the data archive of 296 water samples collected by the Melnikov Permafrost Institute staff members during hydrochemical surveys between 1984 and 2019. The average fluoride concentrations varied between 5 and 10 mg/L. Highest concentrations (up to 15.5 mg/L) are observed in waters of the terrigenous aquifer systems occurring over the crystalline basement. The sources of fluoride can likely be the various fluoride-bearing minerals of aluminosilicate rocks. The high fluoride concentrations in these aquifers are associated with geochemistry (alkaline environment and sodium-bicarbonate water type) resulted from cryogenic metamorphism of rocks. Lowest concentrations (0.4-0.8 to 2-3 mg/L) are observed in subpermafrost groundwater samples collected from wells near the Lena River channel. These low concentrations indirectly indicate the presence of open taliks beneath the channel and the infiltration of stream water into the subpermafrost aquifers.