Epilimnetic Mixing Increases Methane Ebullition Fluxes in a Small Eutrophic Drinking Water Reservoir

Science Center, Bent Corridor

Inland waters are substantial sources of carbon (C) greenhouse gases to the atmosphere. Reservoirs, in particular, emit a large portion of inland water C emissions, generally in the form of methane (CH4) bubble fluxes (ebullition) from the sediments. CH4 ebullition can contribute the majority of reservoir C emissions; however, little is known how CH4 ebullition responds to water management practices like epilimnetic aeration, a common technique to prevent harmful algal blooms in reservoirs used for drinking water supply and recreation. In summer 2017, we measured CH4 ebullition rates in a managed eutrophic drinking water reservoir during two planned epilimnetic aeration mixing events, and observed an overall significant increase in ebullition rates after the first mixing event but only a marginal increase after the second. Our data suggests that epilimnetic mixing management may increase ebullition rates, but that any stimulation of CH4 fluxes may be dependent on the duration and timing of mixing.