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- Title
Characterization of atmospheric methane release in the outer Mackenzie River delta from biogenic and thermogenic sources.
- Authors
Wesley, Daniel; Dallimore, Scott; MacLeod, Roger; Sachs, Torsten; Risk, David
- Abstract
The Mackenzie River delta is the second largest Arctic river delta in the world. Thin and destabilizing permafrost coupled with vast natural gas reserves at depth, high organic-content soils, and a high proportion of wetlands create a unique ecosystem conducive to high rates of methane (CH 4) emission from biogenic and thermogenic sources. Hotspots are known to have a significant contribution to summertime CH 4 emissions in the region. Still, little research has been done to determine how often geologic or biogenic CH 4 contributes to hotspots in the Mackenzie River delta. In the present study, stable carbon isotope analysis was used to identify the source of CH 4 at several aquatic and terrestrial sites thought to be hotspots of CH 4 flux to the atmosphere. Walking transects and point samples of atmospheric CH 4 and CO 2 concentrations were measured. Source stable carbon isotope (δ13 C-CH 4) signatures were derived from keeling plots of point samples and ranged from -42‰ to -88‰ δ13 C-CH 4 , identifying both biogenic and thermogenic sources. A CH 4 source was determined for eight hotspots, two of which were thermogenic in origin (-42.5‰ , -44.7‰), four of which were biogenic in origin (-71.9‰ to -88.3‰), and two of which may have been produced by the oxidation of biogenic CH 4 (-53.0‰ , -63.6‰), as evidenced by δ13 C-CH 4 signatures. This indicates that the largest hotspots of CH 4 production in the Mackenzie River delta are caused by a variety of sources.
- Subjects
STABLE isotope analysis; NATURAL gas reserves; WETLAND soils; ATMOSPHERIC methane; CARBON isotopes; STABLE isotopes; CARBON dioxide
- Publication
Cryosphere, 2023, Vol 17, Issue 12, p5283
- ISSN
1994-0416
- Publication type
Article
- DOI
10.5194/tc-17-5283-2023