Abstract
Thawing Arctic permafrost can induce hydrologic change and alter redox conditions, shifting the balance of soil organic matter (SOM) decomposition. There remains uncertainty about how soil saturation and redox transitions impact dissolved and gas phase carbon fluxes, and efforts to link hydrobiogeochemical processes to ecosystem-scale models are limited. This study evaluates SOM decomposition of Arctic tundra soils using column experiments, water chemistry measurements, microbial community analysis, and a PFLOTRAN reactive transport model. Soil columns from a thermokarst channel (TC) and an upland tundra (UC) were exposed to cycles of saturation and drainage, which controlled carbon emissions. During saturation, an outflow of dissolved organic carbon from the UC soil correlated with elevated reduced iron and decreased pH; during drainage, UC carbon dioxide fluxes were 70% higher than TC fluxes. Intermittent methane release was observed for TC, consistent with higher methanogen abundance. Slower drainage in the TC soil correlated with more subtle biogeochemical changes. PFLOTRAN simulations captured experimental trends in soil carbon fluxes, oxygen concentrations, and water contents. The model was then used to evaluate additional soil water drainage rates. This study emphasizes the importance of considering hydrologic change when evaluating and simulating SOM decomposition in dynamic Arctic tundra environments.
| Original language | English |
|---|---|
| Article number | 3093 |
| Journal | Scientific Reports |
| Volume | 15 |
| Issue number | 1 |
| DOIs | |
| State | Published - Dec 2025 |
Funding
We thank the Council Native Corporation for access to the Council research site and permitted soil sampling. This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Biological and Environmental Research through the Next Generation Ecosystems Experiment in the Arctic (NGEE Arctic) project under contract number DE-AC05-00OR22725. We also acknowledge Stan Wullschleger for his leadership on this project. We thank Leah Hochanadel for her support sampling column experiments and her valuable advice. We are grateful to Xiangping Yin and Geoff Schwaner for training and support with analytical equipment, and Verity Salmon and Fernanda Santos for helpful and supportive discussions related to organic carbon cycling during this project. We sincerely thank Fengming Yuan for his support with the PFLOTRAN simulations. This research used resources of the Advanced Photon Source, an Office of Science User Facility operated for the U.S. Department of Energy (DOE) Office of Science by Argonne National Laboratory, and was supported by the U.S. DOE under Contract No. DE-AC02-06CH11357. We acknowledge Benjamin Reinhart at beamline 9-BM at APS for assistance with data collection.