Methane Emissions to the Atmosphere from Lakes and Wetlands in the Southeast United States

Authors: Emily Ritz*, Furman University, Emily Ritz, Earth and Environmental Sciences, Furman University, C Brannon Andersen, Earth and Environmental Sciences, Furman University, Christopher Romanek, Earth and Environmental Sciences, Furman University
Topics: Environmental Science, Coupled Human and Natural Systems
Keywords: biogeochemistry, methane, carbon cycle, GIS
Session Type: Poster
Day: 4/5/2019
Start / End Time: 1:10 PM / 2:50 PM
Room: Lincoln 2, Marriott, Exhibition Level
Presentation File: No File Uploaded

The biogeochemical cycling of methane includes several sources and sinks which are poorly constrained in the global budget. Previous studies have focused primarily on methane emissions from boreal and tropical regions, with less emphasis on temperate climates. Globally, the largest contributor of natural methane to the atmosphere are lakes, ponds, and wetlands. Our objective was to estimate the amount of methane emitted to the atmosphere from water bodies in a temperate environment. A GIS model of all water bodies (rivers, ponds, lakes, and wetlands) in South Carolina estimated the flux of methane to the atmosphere under the assumption that methane concentrations were oversaturated in the water column. Taking into account the flux variations between different types of water bodies, the model suggests that 0.73 Tg of methane are emitted to the atmosphere annually from all bodies of water in South Carolina. In order to verify this assumption, samples were collected and analyzed from 19 locations within a wetland (n=12) and small lake (n=7) near Greenville, South Carolina. Methane concentrations ranged from 0.02 to 32.4 ╬╝mol/L. Concentrations measured in samples from a wetland were significantly greater than those measured from a lake. All samples measured were oversaturated with respect to methane, ranging from 6 to 14,000 times the atmospheric concentration. The results support the GIS model and suggest rivers, lakes, and wetlands in the Southeastern United States are potentially important sources of methane to the atmosphere.

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