Increased Arctic NO 3 - Availability as a Hydrogeomorphic Consequence of Permafrost Degradation and Landscape Drying

• Published in: Nitrogen
• Main Authors: Arendt, Carli A., Heikoop, Jeffrey M., Newman, Brent D., Wilson, Cathy J., Wainwright, Haruko, Kumar, Jitendra, Andersen, Christian G., Wales, Nathan A., Dafflon, Baptiste, Cherry, Jessica, Wullschleger, Stan D.
• Language: unknown
• Published: 2023
• Subjects: 54 ENVIRONMENTAL SCIENCES; Arctic; permafrost; Tundra
• Online Access: http://www.osti.gov/servlets/purl/1870204; https://www.osti.gov/biblio/1870204; https://doi.org/10.3390/nitrogen3020021

Climate-driven permafrost thaw alters the strongly coupled carbon and nitrogen cycles within the Arctic tundra, influencing the availability of limiting nutrients including nitrate (NO 3 - ). Researchers have identified two primary mechanisms that increase nitrogen and NO 3 - 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 NO 3 - 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 NO 3 - production and accumulation. We extrapolate relationships between NO 3 - and soil moisture in elevated topographic features within our study area and the broader Alaskan Coastal Plain and investigate potential changes in NO 3 - availability in response to possible hydrogeomorphic evolution scenarios of permafrost landscapes. These approximations indicate that such changes could increase Arctic tundra NO 3 - availability by ~250–1000%. Thus, hydrogeomorphic changes that accompany continued permafrost degradation in polygonal permafrost landscapes will substantially increase soil pore water NO 3 - availability and boost future fertilization and productivity in the Arctic.