title: Atmospheric CH4oxidation by Arctic permafrost and mineral cryosols as a function of water saturation and temperature.
abstract: The response of methanotrophic bacteria capable of oxidizing atmospheric CH4to climate warming is poorly understood, especially for those present in Arctic mineral cryosols. The atmospheric CH4oxidation rates were measured in microcosms incubated at 4 °C and 10 °C along a 1-m depth profile and over a range of water saturation conditions for mineral cryosols containing type I and type II methanotrophs from Axel Heiberg Island (AHI), Nunavut, Canada. The cryosols exhibited net consumption of ~2 ppmv CH4under all conditions, including during anaerobic incubations. Methane oxidation rates increased with temperature and decreased with increasing water saturation and depth, exhibiting the highest rates at 10 °C and 33% saturation at 5 cm depth (260 ± 60 pmol CH4gdw-1d-1). Extrapolation of the CH4oxidation rates to the field yields net CH4uptake fluxes ranging from 11 to 73 μmol CH4m-2d-1, which are comparable to field measurements. Stable isotope mass balance indicates ~50% of the oxidized CH4is incorporated into the biomass regardless of temperature or saturation. Future atmospheric CH4uptake rates at AHI with increasing temperatures will be determined by the interplay of increasing CH4oxidation rates vs. water saturation and the depth to the water table during summer thaw.
authors.affiliation: Department of Geosciences, Princeton University, Princeton, NJ, USA.
authors.forename: B
authors.initials: B
authors.lastname: Stackhouse
authors.affiliation: Department of Geosciences, Princeton University, Princeton, NJ, USA.
authors.forename: M C Y
authors.initials: MC
authors.lastname: Lau
authors.affiliation: The Center for Environmental Biotechnology, University of Tennessee, Knoxville, TN, USA.
authors.forename: T
authors.initials: T
authors.lastname: Vishnivetskaya
authors.affiliation: Department of Geosciences, Princeton University, Princeton, NJ, USA.
authors.forename: N
authors.initials: N
authors.lastname: Burton
authors.affiliation: Department of Geosciences, Princeton University, Princeton, NJ, USA.
authors.forename: R
authors.initials: R
authors.lastname: Wang
authors.affiliation: Department of Geosciences, Princeton University, Princeton, NJ, USA.
authors.forename: A
authors.initials: A
authors.lastname: Southworth
authors.affiliation: Department of Natural Resource Sciences, McGill University, Montreal, QC, Canada.
authors.forename: L
authors.initials: L
authors.lastname: Whyte
authors.affiliation: Department of Geosciences, Princeton University, Princeton, NJ, USA.
authors.forename: T C
authors.initials: TC
authors.lastname: Onstott
mesh_terms: D001110:Arctic Regions; D008697:Methane / Q000378:metabolism*; D008903:Minerals / Q000378:metabolism*; D020957:Nunavut; D010084:Oxidation-Reduction; D065946:Permafrost; D013696:Temperature; D014867:Water / Q000378:metabolism*
chemical_list: D008903:Minerals; D014867:Water; D008697:Methane