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.