Increased Arctic NO3− Availability as a Hydrogeomorphic Consequence of Permafrost Degradation and Landscape Drying
Authors:
- Carli A. ArendtCarli A. Arendt
- Jeffrey M. HeikoopJeffrey M. Heikoop
- Brent D. NewmanBrent D. Newman
- Cathy J. WilsonCathy J. Wilson
- Haruko WainwrightHaruko Wainwright
- Jitendra KumarJitendra Kumar
- Christian G. AndersenChristian G. Andersen
- Nathan A. WalesNathan A. Wales
- Baptiste DafflonBaptiste Dafflon
- Jessica CherryJessica Cherry
- Stan D. WullschlegerStan D. Wullschleger
Open Access
Abstract
Climate-driven permafrost thaw alters the strongly coupled carbon and nitrogen cycles within the Arctic tundra, influencing the availability of limiting nutrients including nitrate (NO3−). Researchers have identified two primary mechanisms that increase nitrogen and NO3− availability within permafrost soils: (1) the ‘frozen feast’, where previously frozen organic material becomes available as it thaws, and (2) ‘shrubification’, where expansion of nitrogen-fixing shrubs promotes increased soil nitrogen. Through the synthesis of original and previously published observational data, and the application of multiple geospatial approaches, this study investigates and highlights a third mechanism that increases NO3− availability: the hydrogeomorphic evolution of polygonal permafrost landscapes. Permafrost thaw drives changes in microtopography, increasing the drainage of topographic highs, thus increasing oxic conditions that promote NO3− production and accumulation. We extrapolate relationships between NO3− and soil moisture in elevated topographic features within our study area and the broader Alaskan Coastal Plain and investigate potential changes in NO3− availability in response to possible hydrogeomorphic evolution scenarios of permafrost landscapes. These approximations indicate that such changes could increase Arctic tundra NO3− availability by ~250–1000%. Thus, hydrogeomorphic changes that accompany continued permafrost degradation in polygonal permafrost landscapes will substantially increase soil pore water NO3− availability and boost future fertilization and productivity in the Arctic.Keywords
Funding Information
- the United States Department of Energy (DOE) Office of Science, Biological and Environmental Research program (DE-AC05-00OR22725)
- U.S. Department of Energy (DE-AC05-00OR22725)
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