Simultaneous Measurement of Diffusive and Ebullitive Methane Emissions in Aquatic Ecosystems Using a Combined Floating Chamber and Thin Boundary Layer Model

In aquatic ecosystems, diffusive and ebullitive methane (CH4) exhibit distinct behaviors and contribute differently to total CH4 emissions to the atmosphere, necessitating their separate quantification. However, it remains challenging to quantify both pathways simultaneously. In this study, we developed a new method that overcomes this challenge. By tracking how other diffusion-dominated gases, such as carbon dioxide (CO2) or nitrous oxide (N2O), move across the water surface, we could estimate diffusive CH4 fluxes and, combined with total flux measurements, determine ebullitive emissions. Compared with the traditionally used CO2-based method, the proposed N2O-based method demonstrated excellent applicability and stability across lakes, reservoirs, and rivers, with strong agreement between estimated and measured CH4 fluxes, confirming its high reliability across diverse aquatic environments.