the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 10 Oct 2025
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.
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Status: open (until 30 Nov 2025)
- RC1: 'Comment on egusphere-2025-4754', Anonymous Referee #1, 03 Nov 2025 reply
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Thank you for having an opportunity to review the paper named “Spatiotemporal Variability and Environmental Controls on Aquatic Methane Emissions in an Arctic Permafrost Catchment” by Thayne et al. The authors evaluated methane emissions by using floating chambers in an Arctic permafrost catchment and compared the results from different water conditions, e.g., lake, streams, and ice/snow-covered surfaces. This is an interesting paper that used the observed data, combined with the statistical analysis, to constrain methane emissions in the study area. Though this is a small area, the authors discussed the potential factors that might influence methane variability. They also pointed out detailed environmental control mechanisms on methane biogeochemistry during seasonal transition, which improves the current knowledge of methane fluxes in such permafrost catchments. From my point of view, the descriptions and discussion are basically correct. I have some suggestions for the author reference.
My comments are line by line – not in order of importance.
Line 25 (Fox-Kemper et al., 2021)
Line 40 The reference to "Saunois et al., 2016” can be updated in 2025.
Line 64 “methanotroph and methanogen microbial assemblages along an upland-wetland environmental gradient were…” I suggest rephrasing this sentence to improve readability.
Line 104 I suggest outlining the specific locations of wetlands, rivers, and tributaries in Fig. 1.
Line 121 semi-transparent plastic material. This is one of my concerns in the paper. Could you please give the detailed information about this chamber, e.g., sealing performance? This raises my concern because the plastic material is not a “regular” material in detecting trace gases. This may cause systematic error when calculating methane fluxes by using linear fitting. In addition, the data between 2023 and 2024 were collected by using different chamber types, which weakens the results and discussion when comparing these two years of data.
Another concern is that the calculation fluxes were not revised for the real wind speed. I know this is difficult based on current data, but a discussion on how the wind speed would disturb the water surface and methane emission should be included. Besides, an uncertainty evaluation of chamber-based flux should also be included so that it is convenient to compare with the fluxes reported in other areas.
Line 138 Did the 707 chamber measurements take place twice (2023 and 2024) or several times on different days? I think this information is important to evaluate the significance of this study, though I found some of it in the figures.
Line 197 Typo after the word “ebullition”.
Line 205 How did you measure the DO concentration? At a one-minute frequency, I suppose a probe was used. The method, precision, and uncertainty should be clarified.
Line 223 Should be section 2.6 instead of 2.4.
Line 244 Should be Section 2.7.
Line 256 Why did you use the soil at 40 cm but not at the surface or top 10 cm to match the soil volumetric water content’s standard?
Line 270 "7 of the 21 weighted predictors." This was inconsistent with that in Fig. 3, which says 8 of the 21 of the weighted predictors. Please check.
Line 335-338 The discussion jumped from different figures, weakening the flow. In addition, these sentences were saying the advantages of KDE, which I think is not suitable in the Discussion, but in the Method.