Abstract
Major ions, stable isotopes, and trace elements, including rare earth elements (REEs), are used as natural tracers in the qualitative assessment of potential water sources in lakes and rivers of the upper Yana River basin, between Verkhoyansk and Chersky Ranges, during the late summer period. Three distinct regions were sampled, and a dominant water source in each region was qualitatively inferred from water chemistry data. The REE distribution pattern was found to be highly regional and controlled by pH and carbonate contents. Mountain headwater stream at the Verkhoyansk Range north slope, the Dulgalakh River, shows an input from a mixture of shallow groundwater and icing meltwater, with a depleted isotopic signature (δ18O below –21‰), d-excess (dex = δ2H − 8·δ18O) above 18, enrichment in Mg and Sr, and depletion in heavy REEs. The Derbeke Depression lakes and streams are fed by rainfall having ultra-low total dissolved solids (TDS) content, below 25 mg/L, and a convex-up REE pattern. In a medium mountainous river at the Chersky Range flank, the Dogdo River, leaching through fissured Jurassic carbonates is a dominant runoff pathway. Riverine water is heavily depleted in light REEs, but enriched in Mo, Rb, Sb, W and U. In the Dulgalakh River water, high positive Sm and Gd anomalies were observed, attributed either to local geology (greenshists), historical mining legacy, or contemporary winter road operations.
Highlights
Frozen soils of permafrost regions are an important stock of chemical elements currently withdrawn from geochemical cycling [1], and contain over 800 Pg C of soil organic carbon [2,3]
This study presents the first data on basic water chemistry, stable water isotopes (δ2H and δ18O), and trace elements, including rare earth elements (REEs), in streams and lakes of a remote and isolated inland region in the Verkhoyansk and Chersky Range system, Northern Eurasia
Lowest total dissolved solids (TDS) values were observed in creeks and lakes of Region 2 (Derbeke Depression), and ranged from 14.7 to 21.3 mg/L
Summary
Frozen soils of permafrost regions are an important stock of chemical elements currently withdrawn from geochemical cycling [1], and contain over 800 Pg C of soil organic carbon [2,3]. Arctic climate warming and projected permafrost degradation are expected to release substantial amounts of organic carbon and chemical elements into the hydrographic network, reintroducing them into global turnover [5,6,7,8]. Hydrological connectivity extends to multiple non-frozen zones within catchments, allowing better surface-subsurface connectivity and increased groundwater drainage to streams [17,18,19,20]. Non-merging permafrost conveys water toward streams and rivers during winter, when other streamflow sources are inactive, leading to increased winter daily flows across the global Arctic [32,33,34]
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