THE ROLE OF DISSOLVED ORGANIC CARBON AND OTHER ENVIRONMENTAL CONTROLS ON METHANE PROCESSES IN ICELANDIC LAKES
As the climate warms, it is critical to understand feedback mechanisms influencing ecosystem greenhouse gas emissions, particularly in polar lakes, which contribute disproportionately to the global methane budget. Yet there is considerable uncertainty surrounding the mechanisms that control methanogenesis and methanotrophy within these systems. In addition to temperature, recent work has emphasized the role of ecosystem productivity and the associated quality and quantity of dissolved organic carbon (DOC) in determining methanogen abundance, community structure, and rates of CH4 flux. In this study, we combined lake physiochemical data, in-situ experiments measuring the rate of methane production and oxidation from water and sediment/water incubations, and lake-surface emission measurements to relate methane dynamics in nine polymictic lakes in Iceland to environmental controls. Stepwise regression identified DOC and temperature as important variables in predicting in-lake CH4 concentrations. Experimental incubations suggest that increased DOC may contribute to increased methane production and emission, while warming may lead to increased methane consumption and reduced emissions from Icelandic lakes. As temperatures continue to warm, it is increasingly important to understand and predict how these changes will influence feedback loops in the biosphere that further magnify or mitigate warming.
Kristin Strock (Co-Presenter/Co-Author), Environmental Science Department, Dickinson College, firstname.lastname@example.org;
Bridget Deemer (Co-Presenter/Co-Author), U.S. Geological Survey, Southwest Biological Science Center, email@example.com;
Nicole Hayes (Co-Presenter/Co-Author), Department of Ecology, Evolution and Behavior, University of Minnesota, firstname.lastname@example.org;
Madaline Ritter (Primary Presenter/Author), Department of Environmental Science, Dickinson College, email@example.com;