Methane Production and Consumption in Alaskan Arctic Lake Sediments

• Main Author: Bretz, Kristen Alexandra.
• Other Authors: Whalen, Stephen Charles, 1952-;
• Format: Thesis
• Language: English
• Published: University of North Carolina at Chapel Hill. Library 2012
• Subjects: Arctic; Arctic Lake; permafrost
• Online Access: http://dc.lib.unc.edu/u?/etd,5427

Methanogenesis and methane oxidation were studied in the sediments of 6 Alaskan arctic lakes during the 2010 and 2011 thaw seasons. Rates of methane production were significantly higher in shallow than in deep lake types, varying from 848 to 21791 μmol m-2 d-1 and were correlated to sedimentation rate and oxygen penetration depth; the data overall indicate that higher organic supply to sediments leads to greater methanogenic activity. Addition of hydrogen provided a significantly stimulating effect on methanogenesis in sediments from every lake, while other methanogenic substrates and alternate electron acceptors (NO3-, Fe3+, SO42-) had variable effects. Methane oxidation rates were much more consistent among lakes (246 μmol m-2 d-1 to 536 μmol m-2 d-1). Increased loading of nutrients and organic matter to lakes from melting permafrost along with warming sediment temperatures may stimulate methanogenesis, but based on calculated rates of CH4 diffusion to oxic sediments, methane oxidize