Print PageArctic wetlands release significant volumes of methane, a greenhouse gas 25 times more potent than CO2, to the atmosphere. However, the mechanisms governing methane emissions are not fully understood, particularly the Anaerobic Oxidation of Methane (AOM) pathway. Current understanding of AOM and its drivers theorizes that AOM likely occurs in Arctic wetland systems, but to date this process has received little to no attention. This research asks: what is the influence of AOM on total methane emissions in the Arctic tundra wetlands near Barrow, Alaska? Barrow soils are unique in that Fe is a significant factor in the system’s redox chemistry, the energetics of which influence methane cycling. A series of anaerobic incubations were used to examine the influence of iron transformations and other electron acceptors on AOM rates. In addition, the incubations were used to investigate the influence of changing temperature and soil moisture regimes on AOM rates. Quantifying the importance of AOM on methane emissions, as well as determining the specific conditions which optimize this process, will lead to more accurate carbon cycling and climate change models for Arctic ecosystems.
Results/Conclusions
Through the use of stable isotope enrichment techniques, anaerobic incubations of soils collected in July 2010 from a variety of landscape subtypes were performed. AOM was found to occur, and to respond negatively to all added electron acceptors, at least during the 180-hour incubation. Potential AOM rates were of similar significance to estimated aerobic oxidation rates for peatlands. AOM is an important sink for methane in these systems, but the electron acceptor is still not fully understood. This highlights the need for further incubation studies using stable isotope pool dilution techniques, and a range of electron acceptors concentrations. In situ field experiments will also be conducted in Summer 2011 to validate the conclusions found from the laboratory incubations.
