Sediment methane cycling dynamics, deep vs shallow lakes

Aspects of sediment methane cycling were measured in 3 shallow (mean depth ~2m) and three deep (mean depth ~6.5 m) lakes in the Foothills region of the Alaskan arctic. The overall goal was to identify lake size-dependent differences in rates and controls on methane consumption and production. Lakes were sampled intensely during one summer each at a permanently established station at the mean depth. Lakes GTH 99, 100 and 114 were sampled during the summer of 2010, while GTH 112, Toolik and NE14 were sampled during the summer of 2011. In each lake the following were measured: depth distributions of basic sediment physical properties; depth distributions of methane and dissolved oxygen; sediment chlorophyll a; sedimentation rate (at maximum depth in each lake); chemistry of surficial sediment (total Fe, Mn, NO3, SO4), rates of methanogenesis and methane oxidation; response of methanogenesis to amendment with alternate electron acceptors (Fe, Mn, NO3, SO4), direct methanogenic substrates (acetate, H2, trimethylamine) and a methanogenic precursor (maltose). Methods are given in Bretz and Whalen (2014), Inland Waters 4:65-78.