Hydrological Connectivity in a Permafrost Tundra Landscape near Vorkuta, North-European Arctic Russia

Abstract

Hydrochemical and geophysical data collected during a hydrological survey in September 2017, reveal patterns of small-scale hydrological connectivity in a small water track catchment in the north-European Arctic. The stable isotopic composition of water in different compartments was used as a tracer of hydrological processes and connectivity at the water track catchment scale. Elevated tundra patches underlain by sandy loams were disconnected from the stream and stored precipitation water from previous months in saturated soil horizons with low hydraulic conductivity. At the catchment surface and in the water track thalweg, some circular hollows, from 0.2 to 0.4 m in diameter, acted as evaporative basins with low deuterium excess (d-excess) values, from 2‰ to 4‰. Observed evaporative loss suggests that these hollows were disconnected from the surface and shallow subsurface runoff. Other hollows were connected to shallow subsurface runoff, yielding d-excess values between 12‰ and 14‰, close to summer precipitation. ‘Connected’ hollows yielded a 50% higher dissolved organic carbon (DOC) content, 17.5 ± 5.3 mg/L, than the ‘disconnected’ hollows, 11.8 ± 1.7 mg/L. Permafrost distribution across the landscape is continuous but highly variable. Open taliks exist under fens and hummocky depressions, as revealed by electric resistivity tomography surveys. Isotopic evidence supports upward subpermafrost groundwater migration through open taliks under water tracks and fens/bogs/depressions and its supply to streams via shallow subsurface compartment. Temporal variability of isotopic composition and DOC in water track and a major river system, the Vorkuta River, evidence the widespread occurrence of the described processes in the large river basin. Water tracks effectively drain the tundra terrain and maintain xeric vegetation over the elevated intertrack tundra patches.

Late Summer Water Sources in Rivers and Lakes of the Upper Yana River Basin, Northern Eurasia, Inferred from Hydrological Tracer Data

“…Rivers of the region plot above the GMWL and, with δ 18 O below −21.5‰, have the most depleted isotopic signature, and d-excess ranging from 18 to 20‰. On the δ 18 O vs. dexcess diagram (Figure 3b) these samples plot at the upper left corner, that can be indicative of sub-permafrost groundwater sources [19], or winter and spring precipitation [40]. In the sampling point, the Dulgalakh River had ultra-low TDS, about 50 mg/L, unsupportive of important sub-permafrost groundwater contribution, or evidencing its heavy dilution by precipitation or supra-permafrost groundwater.…”

“…In continuous permafrost, water transfer is confined to the active layer and local open (through) taliks under lakes and major rivers [13,15,16]. In discontinuous permafrost, hydrological Hydrology 2022, 9, 24 2 of 15 connectivity extends to multiple non-frozen zones within catchments, allowing better surface-subsurface connectivity and increased groundwater drainage to streams [17][18][19][20]. Wildfires [21,22] and higher snow accumulation, owing to climate change or snow retention in shrubs and snow fences [23][24][25], lead to thermally-driven permafrost degradation, and development of non-merging permafrost, also termed 'isolated talik' [26,27], 'lateral talik' [28], 'residual talik', or 'residual thaw layer' [18,29,30], 'perennial thaw zone' [31].…”

Reemission of inorganic pollution from permafrost? A freshwater hydrochemistry study in the lower Kolyma basin (North‐East Siberia)

“…Hydrochemical changes in permafrost regions are increasingly probable, leading to both temporary and permanent hazards to the surface water quality in the Arctic (Brubaker et al, 2012; Gunnarsdóttir et al, 2019). Permafrost active layer deepening and the formation of new thermokarst lakes, taliks and drainage pathways (Dzhamalov & Safronova, 2018; in't Zandt et al, 2020; Tananaev & Lotsari, 2022) all lead to changes in the migration of chemical compounds (Frey & Mcclelland, 2009; Monhonval et al, 2021) both horizontally and vertically (Ji et al, 2021; Tananaev et al, 2021). The newly formed drainage pathways may leach chemical compounds from layers previously disconnected from groundwater flow (Ji et al, 2021; Lim et al, 2019).…”