Icings and groundwater conditions in permafrost catchments of northwestern Canada.

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 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.

Ecological recovery in an Arctic delta following widespread saline incursion.

Arctic ecosystems are vulnerable to the combined effects of climate change and a range of other anthropogenic perturbations. Predicting the cumulative impact of these stressors requires an improved understanding of the factors affecting ecological resilience. In September of 1999, a severe storm surge in the Mackenzie Delta flooded alluvial surfaces up to 30 km inland from the coast with saline waters, driving environmental impacts unprecedented in the last millennium.

Spatial and temporal assessment of mercury and organic matter in thermokarst affected lakes of the Mackenzie Delta uplands, NT, Canada.

We examined dated sediment cores from 14 thermokarst affected lakes in the Mackenzie Delta uplands, NT, Arctic Canada, using a case-control analysis to determine how retrogressive thaw slump development from degrading permafrost affected the delivery of mercury (Hg) and organic carbon (OC) to lakes. We show that sediments from the lakes with retrogressive thaw slump development on their shorelines (slump-affected lakes) had higher sedimentation rates and lower total Hg (THg), methyl mercury (MeHg), and lower organic carbon concentrations compared to lakes where thaw slumps were absent (reference lakes). There was no difference in focus-corrected Hg flux to sediments between reference lakes and slump-affected lakes, indicating that the lower sediment Hg concentration in slump-affected lakes was due to dilution by rapid inorganic sedimentation in the slump-affected lakes.