Methane Emission from a Small Lake after Artificially Created Ebullition

Forner, Jan; Schaller, Carsten; Klemm Otto

Abstract

The total amount of methane (CH4) that is emitted from wetlands worldwide is still uncertain. A major factor contributing to this uncertainty is ebullition, which is the emission of virtually pure methane gas bubbles from water bodies; these short, high-flux pulses are highly variable in space and time. Small, shallow lakes have been found to be prone to high CH4 emissions related to ebullition, and the fluxes from these ecosystems have been quantified using the eddy covariance (EC) method. However, this method was found to cause systematic biases during high-flux events. In this study, the EC method was used to quantify the CH4 flux from a small, shallow lake in which an artificial ebullition event was conducted to analyze the EC method’s performance under such conditions. Results showed that the flux quality was not necessarily subject to flux biases during the ebullition event but was of sufficient quality to quantify the CH4 emissions. The total emission flux of CH4 from the small lake during the artificial ebullition event was of the same magnitude as the respective CH4 flux over 2.7 days during regular conditions.