Spatial variation of net methane uptake in Arctic and subarctic drylands of Canada and Greenland

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The importance of uptake of atmospheric methane (CH4) in dry Arctic soils for the total Arctic CH4 budget is unresolved. This is partly due to lack of data on the spatial variability of net CH4 consumption and understanding of the main process drivers. We measured net CH4 consumption in Arctic and subarctic landscapes located in in Disko Bay Area and Kangerlussuaq in Western Greenland and in the St. Elias Range in the Yukon, Canada, respectively. Our aim was to characterize the in situ spatial variability of net CH4 uptake in hitherto unexplored Arctic dry upland soils to explore possible limits and environmental drivers across the Arctic geodiversity. Furthermore, we sampled soil for incubation experiments to investigate how net CH4 oxidation responded to changes in soil moisture in contrasting geomorphic settings and parent geological parent materials. We used a laser-based fast deployable chamber system for flux measurements. All studied sites were net sinks of atmospheric CH4 with an average flux −7.5 ± 5.6 μmol CH4 m-2h−1, that are in the upper range of reported net CH4 uptake fluxes in similar soils of the Arctic. The large observed spatial variability within all studied sites (coefficient of variation 50 – 120 %) highlights the need for careful research design allowing for many spatial replicates to achieve representative values. Sites with an active geomorphic environment (abrasion plateau, riverbeds, mountain tops) generally had lower than average net CH4 uptake. Our incubation studies revealed that subsurface CH4 oxidation is the main driver of net surface-atmosphere exchange and that net CH4 oxidation in these layers responded more to changes to soil moisture than in near surface layers. Our study shows surprisingly similar flux magnitudes of net CH4 uptake across widely different landscape forms and geologic parent material, but responding similarly to soil hydrology and geomorphic disturbance, indicating global controls on the net CH4 oxidation in these dry upland environments.
OriginalsprogEngelsk
Artikelnummer116815
TidsskriftGeoderma
Vol/bind443
Antal sider12
ISSN0016-7061
DOI
StatusUdgivet - 2024

Bibliografisk note

Funding Information:
The study was supported by 1) European JPI Climate Joint Call for Transnational Collaborative Research Projects - JPI Climate - Topic 2: Russian Arctic and Boreal Systems for the project “Constraining uncertainties in the permafrost carbon feedback (Application: #66061)” and 2) EU Interact TA for the project “CH4Cool - End members of CH4 oxidation in cold mountain soils”. The employees and board at Arctic Station (University of Copenhagen) are also thanked profoundly for their support and good company during the Disko Bay campaign. The authors would also to thank the two anonymous reviewers for their constructive comments and recommendations for improving the manuscript.

Publisher Copyright:
© 2024 The Authors

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