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Methane and carbon dioxide emissions from thermokarst lakes on mineral soils.

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Matveev, Alex; Laurion, Isabelle; Vincent, Warwick F. (9999). Methane and carbon dioxide emissions from thermokarst lakes on mineral soils. Arctic Science . DOI: 10.1139/AS-2017-0047. (Sous Presse)

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Résumé

Thermokarst lakes are known to emit methane (CH₄) and carbon dioxide (CO₂), but little attention has been given to those formed from the thawing and collapse of lithalsas, ice-rich mineral soil mounds that occur in permafrost landscapes. The present study was undertaken to assess greenhouse gas stocks and fluxes in eight lithalsa lakes across a 200-km gradient of permafrost degradation in subarctic Québec. The northernmost lakes varied in their surface-water CO₂ content, from below to above saturation, but the southern lakes in this gradient had much higher surface concentrations that were well above air-equilibrium. Surface-water CH₄ concentrations were at least an order of magnitude above air-equilibrium values at all sites, and the diffusive fluxes of both gases increased from north to south. Methane oxidation in the surface waters from a northern lake was only 10% of the emission rate, but at the southern end it was around 60% of the efflux to the atmosphere, indicating that methanotrophy can play a substantive role in reducing net emissions. Overall, our observations show that lithalsa lakes can begin emitting CH₄ and CO₂ soon after they form, with effluxes of both gases that persist and increase as the permafrost continues to warm and erode.

Type de document: Article
Mots-clés libres: lithalsa; methane; permafrost; subarctic; thermokarst
Centre: Centre Eau Terre Environnement
Date de dépôt: 08 juin 2018 19:47
Dernière modification: 08 juin 2018 19:47
URI: http://espace.inrs.ca/id/eprint/7280

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