Type of Document	Thesis
Author	Fields, Dana Lynn
URN	etd-06262004-182319
Title	Stable Isotope Studies of Methane Production in Northern Wetlands
Degree	Master of Science
Department	Oceanography, Department of
Advisory Committee	Advisor Name Title Jeffrey P. Chanton Committee Chair Joel Kostka Committee Member William M. Landing Committee Member
Keywords	Methane Production Natural Abundance Isotopes Methane Stable Isotopes Alpha Fractionation Factors
Date of Defense	2003-09-19
Availability	unrestricted
Abstract Northern peatlands are complex wetland ecosystems that are characterized as bogs, fens, or tundra. Since these systems are flooded for much of the growing season, organic matter often decomposes anaerobically. Methanogenesis is the dominant means of anaerobic metabolism occurring in these wetlands and can occur via two separate pathways. Acetoclastic methanogenesis involves the formation and subsequent degradation of acetate to form carbon dioxide and methane. Methane can also be produced by the reduction of carbon dioxide by hydrogen gas. This research uses natural abundance isotopes to discern the proportion of methane produced by each of these mechanisms in peatlands along a north-south transect across Alaska. The focus of this research was to investigate pathway shifts in methane production across latitudinal and vegetation gradients in order to discover if acetoclastice methanogenesis becomes less important at higher latitudes. Our study concluded that factors other than latitude (vegetation type and/or pH) have greater impact on methane production mechanism than does latitude. Another objective of this research was to determine if the methanogenic pathway influences the stable deuterium (äD) isotope ratios of the methane produced. This study provided further evidence that methane production mechanism influences the äD of methane causing an antipathetic relationship between the fractionation factors of D and 13C (áD and áC).
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