Methane and Carbon Dioxide Production and Methane Oxidation Potential From a Melt Feature in the Discontinuous Permafrost Zone of Northern Alberta, Canada

With warming in northern latitudes, collapse scars have developed in permafrost regions resulting in wet bogs dominated by Sphagnum species with some vascular plants. The amount of methane and carbon dioxide produced and emitted can have an important impact on global atmospheric budgets. From a collapse scar in the discontinuous permafrost zone of northern Alberta, Canada, peat cores were taken in order to estimate the potential CH₄ production (PMP), potential anaerobic and aerobic CO₂ production (PCP), and potential CH₄ oxidation (PMO), as well as the effect of temperature on all three processes. A depth profile of PMP and anaerobic PCP and their response to temperature was determined on 3 cores from the central portion of the collapse scar in August 2003. The cores were field extruded and representative slices from 0 to 100 cm were made anaerobic and incubated at 2C, 12C and 22C. Additionally, the same temperature regime was used to examine the effect of temperature on PMO, and aerobic PCP from 3 cores collected during the same month. PMP peaked between 10 to 15 cm below the water table with an average production of 0.08 μ g CH₄ g^-1 d^-1. Anaerobic PCP was greatest between 0 to 5 cm below the peat surface in all cores with an average production of 0.65 μ g CO₂ g^-1 d^-1. Anaerobic PCP at peak PMP depth was 0.19 μ g CO₂ g^-1 d^-1. The average anaerobic PCP to PMP ratio for core depths with significant PMP was 1.4 (mole/mole). At peak PMP depth the average Q₁₀ response was 8.6 for 2 to 22C and for anaerobic PCP the average Q₁₀ response at the depth of maximum production was 1.7 for 2 to 22C. Incubation temperature had a greater effect on PMP and anaerobic PCP between 2 and 12C then it did between 12 and 22C. On average, PMO was greatest 12 cm below the water table with a peak oxidation of 1.2 μ g CH₄ g^-1 d^-1 at a depth of 25 to 30 cm. The area of maximum PMO and PMP occurred at the same depth interval, 10 to 15 cm below the water table. Aerobic PCP was greatest at a depth of 0 to 5 cm with an average production of 2.2 μ g CO₂ g^-1 d^-1. The average aerobic PCP to anaerobic PCP ratio for depths 0 to 80 cm was 3.2.