Methane and carbon dioxide emissions from thermokarst lakes on mineral soils

Arctic Science

article

Alex Matveev¹  Isabelle Laurion²  Warwick F. Vincent¹ 

[1] Centre d’études nordiques (CEN) and Département de biologie, Université Laval;Institut national de la recherche scientifique, Centre Eau Terre Environnement (INRS-ETE) and Centre d’études nordiques (CEN)

关键词: lithalsa;    methane;    permafrost;    subarctic;    thermokarst.;   

DOI  :  10.1139/as-2017-0047

学科分类：地球科学(综合)

来源: NRC Research Press

【 摘 要 】

Thermokarst lakes are known to emit methane (CH 4 ) and carbon dioxide (CO 2 ), 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 CO 2 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 CH 4 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 CH 4 and CO 2 soon after they form, with effluxes of both gases that persist and increase as the permafrost continues to warm and erode.

【 授权许可】

CC BY