Dataset Information

Icings and groundwater conditions in permafrost catchments of northwestern Canada.

ABSTRACT: Icings are sheet-like masses of ice that form on the ground surface or in fluvial channels from groundwater seepage. Although the presence of icings in the landscape is known, few studies investigated their regional distribution and explored relations with terrain factors including permafrost and winter baseflow conditions. Here, we mapped the distribution of icings in a 618,430 km2 area of northwestern Canada from a stack of 573 Landsat imageries (1985-2017) and determined using hydrometric data the winter baseflow contribution to the total annual discharge of 17 rivers in the study area. The 1402 mapped icings occur preferentially at the foothills of heavily faulted karstic mountainous regions in the continuous permafrost. Winter baseflow and its contribution to annual discharge was lower in continuous permafrost catchments than in discontinuous permafrost but showed a general increase over the 1970-2016 period. As such, the distribution of icings appears to be sensitive to winter air temperatures and winter baseflow conditions and icings located at the southern boundary of continuous permafrost would be more sensitive to degrading permafrost and the predicted increase in winter baseflow.

SUBMITTER: Crites H

PROVIDER: S-EPMC7039954 | biostudies-literature | 2020 Feb

REPOSITORIES: biostudies-literature

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Icings and groundwater conditions in permafrost catchments of northwestern Canada.

Crites Hugo H Kokelj Steve V SV Lacelle Denis D

Scientific reports 20200224 1

Icings are sheet-like masses of ice that form on the ground surface or in fluvial channels from groundwater seepage. Although the presence of icings in the landscape is known, few studies investigated their regional distribution and explored relations with terrain factors including permafrost and winter baseflow conditions. Here, we mapped the distribution of icings in a 618,430 km<sup>2</sup> area of northwestern Canada from a stack of 573 Landsat imageries (1985-2017) and determined using hydr ...[more]

PMID: 32094502

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Project description:A global warming-induced transition from glacial to periglacial processes has been identified in mountainous regions around the world. Degrading permafrost in pristine periglacial environments can produce acid rock drainage (ARD) and cause severe ecological damage in areas underlain by sulfide-bearing bedrock. Limnological and paleolimnological approaches were used to assess and compare ARDs generated by rock glaciers, a typical landform of the mountain permafrost domain, and their effects on alpine headwater lakes with similar morphometric features and underlying bedrock geology, but characterized by different intensities of frost action in their catchments during the year. We argue that ARD and its effects on lakes are more severe in the alpine periglacial belt with mean annual air temperatures (MAAT) between -2°C and +3°C, where groundwater persists in the liquid phase for most of the year, in contrast to ARD in the periglacial belt where frost action dominates (MAAT < -2°C). The findings clearly suggest that the ambient air temperature is an important factor affecting the ARD production in alpine periglacial environments. Applying the paleoecological analysis of morphological abnormalities in chironomids through the past millennium, we tested and rejected the hypothesis that unfavorable conditions for aquatic life in the ARD-stressed lakes are largely related to the temperature increase over recent decades, responsible for the enhanced release of ARD contaminants. Our results indicate that the ARDs generated in the catchments are of a long-lasting nature and the frequency of chironomid morphological deformities was significantly higher during the Little Ice Age (LIA) than during pre- or post-LIA periods, suggesting that lower water temperatures may increase the adverse impacts of ARD on aquatic invertebrates. This highlights that temperature-mediated modulations of the metabolism and life cycle of aquatic organisms should be considered when reconstructing long-term trends in the ecotoxicological state of lakes.

Dataset Information

Icings and groundwater conditions in permafrost catchments of northwestern Canada.

Publications

Icings and groundwater conditions in permafrost catchments of northwestern Canada.

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