Organic carbon content in degrading permafrost beneath expanding thermokarst lakes
Arctic lakes are globally significant sources of methane, resulting from anaerobic decomposition of thawed organic matter in lake bottoms. We examined patterns of permafrost degradation near thermokarst lakeshores in the tundra of Old Crow Flats, a 5600 km2 peatland in the continuous permafrost of northern Yukon. Despite a maximum lake-ice thickness of 1.55 m, mean annual lake-bottom temperatures below shallow water were > 0C and taliks occurred under water depths < 0.6 m. There was 45 kg/m2 organic carbon in the top 1.5 m of lake-bottom sediment. Potential decomposability was highest for recently fallen debris.
Poster presented at the 2014 Thermokarst Aquatic ecosystems Workshop in Quebec City:
Roy-Léveillée P, Burn, CR, Humphreys, E, Braul, Z. (2014) Near-shore talik geometry beneath thermokarst lakes in the Old Crow Flats, Northern Yukon. THAW 2014 - Thermokarst Aquatic Ecosystem Workshop, March 12-15, 2014,Quebec City, QC.