EGU General Assembly 2023
© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.

Characterization of atmospheric methane release at hotspots in the outer Mackenzie River Delta

Daniel Wesley1,2, Scott Dallimore3, Roger MacLeod3, Torsten Sachs4, and Dave Risk1
Daniel Wesley et al.
  • 1Department of Earth Science, St Francis Xavier University, Antigonish, Canada
  • 2Department of Environmental Science, Memorial University, St. John’s, Canada
  • 3Geological Survey of Canada-Pacific, Natural Resources Canada, Sidney, Canada
  • 4GFZ German Research Centre for Geosciences, Potsdam, Germany

Spatio-temporal patterns of methane (CH4) and carbon dioxide (CO2) release from natural sources needs to be better understood across the Arctic region. Climate change in the Arctic is occurring at a pace that may be 2 to 4 times the global average, and existing measurements derive from a limited number of field sites, and most originate during the growing season although important studies show that release continues during winter. The Mackenzie River Delta in the western Canadian Arctic holds thin and destabilizing permafrost, high organic content soils, a high proportion of wetlands, and vast natural gas occurrences at depth, all of which create high methane potential. In the present study, we conducted atmospheric CH4 and CO2 measurements using a mobile laboratory equipped with a greenhouse gas analyzer during the summer and winter. We also visited known aquatic and terrestrial CH4 flux hotspots, including pingos, lakes, river channels and wetlands, where we measured concentration transects and stable carbon isotope (13C-CH4) values to characterize CH4source and spatial pattern. Source stable carbon isotope (δ13C-CH4) signatures at hotspots ranged from -42 to -88 ‰ δ13C-CH4. Active surface microbial production was responsible for at least 4 of the 8 hotspots investigated, indicating that microbial production may be responsible for a greater number of CH4 hotspots than is indicated by previous studies in the region. Mobile surveys showed that shrubland, grassland and deep water were the most important ecosystems for CH4 and CO2 production during the wintertime and that low lying areas of the Delta had the highest atmospheric mixing ratios of CH4.

How to cite: Wesley, D., Dallimore, S., MacLeod, R., Sachs, T., and Risk, D.: Characterization of atmospheric methane release at hotspots in the outer Mackenzie River Delta, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-10711,, 2023.