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| Titel |
Modern to millennium-old greenhouse gases emitted from ponds and lakes of the Eastern Canadian Arctic (Bylot Island, Nunavut) |
| VerfasserIn |
F. Bouchard, I. Laurion, V. Preskienis, D. Fortier, X. Xu, M. J. Whiticar |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 12, no. 23 ; Nr. 12, no. 23 (2015-12-14), S.7279-7298 |
| Datensatznummer |
250118211
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| Publikation (Nr.) |
 copernicus.org/bg-12-7279-2015.pdf |
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| Zusammenfassung |
| Ponds and lakes are widespread across the rapidly changing permafrost
environments. Aquatic systems play an important role in global
biogeochemical cycles, especially in greenhouse gas (GHG) exchanges between
terrestrial systems and the atmosphere. The source, speciation and emission
rate
of carbon released from permafrost landscapes are strongly influenced by
local conditions, hindering pan-Arctic generalizations. This study reports
on GHG ages and emission rates from aquatic systems located on Bylot Island,
in the continuous permafrost zone of the Eastern Canadian Arctic. Dissolved
and ebullition gas samples were collected during the summer season from
different types of water bodies located in a highly dynamic periglacial
valley: polygonal ponds, collapsed ice-wedge trough ponds, and larger lakes.
The results showed strikingly different ages and fluxes depending on aquatic
system types. Polygonal ponds were net sinks of dissolved CO2, but
variable sources of dissolved CH4. They presented the highest
ebullition fluxes, 1 or 2 orders of magnitude higher than from other
ponds and lakes. Trough ponds appeared as substantial GHG sources,
especially when their edges were actively eroding. Both types of ponds
produced modern to hundreds of years old (< 550 yr BP) GHG, even if
trough ponds could contain much older carbon (> 2000 yr BP)
derived from freshly eroded peat. Lakes had small dissolved and ebullition
fluxes, however they released much older GHG, including millennium-old
CH4 (up to 3500 yr BP) from lake central areas. Acetoclastic
methanogenesis dominated at all study sites and there was minimal, if any,
methane oxidation in gas emitted through ebullition. These findings provide
new insights on GHG emissions by permafrost aquatic systems and their
potential positive feedback effect on climate. |
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