Understanding Anaerobic Oxidation of Methane in a Climate-Manipulated Northern Peatland

dc.contributor.authorBrunik, Kaitlin
dc.date.accessioned2017-08-04T18:04:43Z
dc.date.available2017-08-04T18:04:43Z
dc.date.issued2017-06-01
dc.description44 pagesen_US
dc.description.abstractAlthough peatlands cover < 3% of the Earth’s surface, they are among the most important terrestrial ecosystems partially because they are responsible for roughly 10% of global methane (CH_4) flux. The consumption of CH_4 (methanotrophy) is an important control on wetland emissions of this greenhouse gas. Anaerobic oxidation of methane (AOM) was thought to be unimportant in peatlands; however, recent studies suggest that this process is ubiquitous in freshwater wetlands, but report a wide range of rates of AOM in peatlands. Due to the lack of understanding of the magnitude and controls over AOM, it is not currently included in Earth system models. The Spruce and Peatland Responses Under Climatic and Environmental Change (SPRUCE; http://mnspruce.ornl.gov) experiment is assessing how northern peatland ecosystems react to a changing climate with a regression-based, ecosystem-scale climate manipulation that incorporates surface and deep (up to 2 m depth) peat heating from 0 to +9 °C above ambient. Soil cores were collected throughout the 2016 growing season following 13 months of deep peat heating and 14 months of subsequent whole-ecosystem warming (surface and deep heating) at 30, 50, 75, 125, and 200 cm depths from each enclosure at the SPRUCE site. Samples were slurried with a 1:3 mixture of peat and porewater (collected from the same plot and depth) and anaerobically incubated within 1°C of in situ temperatures for approximately three weeks using a radioactive tracer method. AOM was measured by the accumulation of tritiated water over time and CH_4 production rates were determined with gas chromatography. We found that AOM was ubiquitous throughout the entire peat profile, with the highest rates occurring at the surface and then decreasing with depth. Additionally, rates of AOM were the greatest at the beginning of the incubation and decreased over time, indicating that organic or inorganic terminal electron acceptors may be driving this process in peatlands. Finally, there was suggestive evidence that temperature is positively correlated with rates of AOM. Collectively, these results suggest that AOM may be important process in northern peatlands, warranting further study and consideration in Earth system models.en_US
dc.description.sponsorshiphis research was supported by U.S. Department of Energy’s Office of Science DE-SC0008092, NICHD Summer Research Program at the University of Oregon NIH-R25HD070817 and the University of Oregon Alden Award.en_US
dc.identifier.urihttps://hdl.handle.net/1794/22552
dc.language.isoenen_US
dc.publisherUniversity of Oregonen_US
dc.rightsCreative Commons BY-NC-ND 4.0-USen_US
dc.subjectPeatlandsen_US
dc.subjectAnaerobic oxidation of methane (AOM)en_US
dc.subjectNorthern peatlandsen_US
dc.subjectMethaneen_US
dc.subjectEnvironmental changeen_US
dc.titleUnderstanding Anaerobic Oxidation of Methane in a Climate-Manipulated Northern Peatlanden_US
dc.typeThesis / Dissertationen_US

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