CALL FOR PROPOSALS:

ORGANIZERS

  • Harvey Thorleifson, Chair
    Minnesota Geological Survey
  • Carrie Jennings, Vice Chair
    Minnesota Geological Survey
  • David Bush, Technical Program Chair
    University of West Georgia
  • Jim Miller, Field Trip Chair
    University of Minnesota Duluth
  • Curtis M. Hudak, Sponsorship Chair
    Foth Infrastructure & Environment, LLC

 

Paper No. 1
Presentation Time: 8:00 AM

REGIONAL SCALE VARIABILITY IN METHANE EMISSIONS FROM THERMOKARST LAKES


WALTER ANTHONY, Katey, University of Alaska, Fairbanks, Water and Environmental Research Center, 525 Duckering Building, 306 Tanana Loop PO Box 755960, Fairbanks, AK 99775, kmwalteranthony@alaska.edu

The relationship between thermokarst (permafrost thaw) and methane emissions from lakes and wetlands has been investigated at relatively few sites around the Arctic with highly variable results. The goal of this paper is to explore the relationship between soil and peat carbon inputs to lakes via thermokarst erosion and methane emissions from lakes in order to explain regional-scale variability in methane emissions. Ground-based surveys of biogenic methane ebullition seeps in 75 lakes along a North-South transect in Alaska revealed that the majority of lakes emit methane via ebullition; however, geographic differences in permafrost, soil organic matter, climate and geology result in large (>10-fold) regional differences in lake methane production and emission on a lake-area basis. Thermokarst lakes that formed in icy, organic-rich Pleistocene-aged yedoma-type permafrost, common in previously unglaciated regions of Alaska, had the highest methane emissions. Erosion of Holocene-aged peat into thermokarst lakes formed in polygonal tundra had lower methane emissions. Non-thermokarst lakes had among the lowest levels of methane emissions. Radiocarbon ages of lake methane reflected the age of soil carbon inputs to thermokarst lakes. These results have implications for using knowledge of soil carbon storage and erosion for upscaling lake methane emissions in the Arctic.
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