Landscape-scale variability of methane in the Mackenzie-Beaufort Delta region of northern Canada, during winter and summer.
Abstract
The Mackenzie-Beaufort Delta (MBD) in northern Canada is an area rich in hydrocarbon deposits, with known natural geologic methane seeps that are aided by permafrost heterogeneity. A recent airborne Eddy Covariance study found hotspots of activity in which methane was moderately elevated and presumed to be geologic in nature, but researchers have also shown that surface biogenic emissions can be prolific in Arctic landscapes, even in winter. In this study, we investigated landscape-scale methane variability in the MBD region, during late winter and summer. We conducted vehicle-based surveys both on and off the highway, using a portable gas analyzer mounted on a truck or boat, and also characterized known hotspots using geochemical analysis to determine source type (biogenic or thermogenic). Below Inuvik in the south of the MBD, we observed spatially-extensive methane enhancements indicative of soil respiration, including in winter, when biological activity is assumed to be negligible. Often, enhancements were associated with known hydrological networks. We compared winter methane distributions with multiple Landsat-8 data products, and found a correlation between the thermal band, and the magnitude of methane enhancements presumed to be biogenic on the basis of spatial occurrence. The pattern of methane emission was different to the north of Inuvik, with more spatial complexity. Geochemical analysis of known persistent (>6 yr) hotspots confirmed 3 sources of methane, including surface biogenic (surface), biogenic/mixed (likely permafrost base), and thermogenic (deep geologic reservoirs). Emission from all sources and in all areas was hotspot-driven, so future studies should include multiple spatial scales of measurement to create a good understanding of each source in this complex Arctic region.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.B23K2462W
- Keywords:
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- 0426 Biosphere/atmosphere interactions;
- BIOGEOSCIENCES;
- 0428 Carbon cycling;
- BIOGEOSCIENCES;
- 0439 Ecosystems;
- structure and dynamics;
- BIOGEOSCIENCES;
- 0475 Permafrost;
- cryosphere;
- and high-latitude processes;
- BIOGEOSCIENCES