Spatiotemporal Variability and Environmental Controls on Aquatic Methane Emissions in an Arctic Permafrost Catchment

Abstract. Understanding spatiotemporal dynamics and drivers of methane (CH₄) fluxes from rapidly changing permafrost regions is critical for improving our understanding of such changes. Between May and August 2023 and 2024, we measured CH₄ using floating chambers in a small Arctic permafrost catchment on Disko Island, Greenland. Diffusive and ebullitive fluxes were derived from 707 measurements using a semi-automated algorithm incorporating boosted regression trees and generalized additive models. Highest fluxes occurred in streams and along lakeshores associated with inlets. Diffusion processes dominated (98 %), while 2 % were split between ebullition and uptake. Median diffusive fluxes were 5.0 nmol m^-2s^-1, (-0.1 to 271.8), peaking at ice-break. Ebullition had a median of 939 nmol m^-2s^-1 (5.2–14,893), but did not impact overall fluxes. Model results suggest thaw-season fluxes reflected meteorology and soil wetness effects, later shifting to biogeochemical controls: dissolved organic matter, oxygen saturation, and pH. Spatial variability arose from patchy conditions shaped by substrate, primary producers and microbial assemblages.