EAR-PF: Nitrogen processing in Arctic deltas and role of channel network orientation on flux to the coast

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An EAR Postdoctoral Fellowship has been awarded to Dr. Deon Knights to work at West Virginia University to undertake research and educational activities. The research will examine how deltas control the flux of terrestrially derived nitrate to the Arctic Ocean, which contains only 1% of global ocean volume but receives 10% of global river discharge. Consequently, the Arctic Ocean is sensitive to high riverine flux of particulates and nutrients, with implications on global carbon cycling, marine biogeochemistry, and fishery health. Although Arctic deltas may alter the nutrient composition of river water discharging to the ocean, almost all discharge and nutrient data for Arctic rivers are based on measurements upstream of deltas, so the extent to which Arctic deltas alter nutrient fluxes to the ocean remains largely unexplored. Through field measurements, laboratory analyses, and modeling efforts, this research will investigate the capacity of Arctic deltas to remove nitrate that would otherwise discharge to the Arctic Ocean. Findings will give insight into the response of nutrient processing in Arctic deltas in response to potential scenarios of climate change which may be used to improve global climate ocean and atmospheric models. This project relies on new field and remote sensing techniques which will be used as a teaching tool for laboratory and field-based courses at West Virginia University at the undergraduate and graduate level. With assistance from project mentor Professor Christopher Russoniello, Dr. Deon Knights will lead seminars through service organizations at West Virginia University aimed at mentoring and supporting underrepresented students in STEM fields.This proposal aims to use a multi-scale approach to investigate how the morphology of channel networks within Arctic deltas influences nitrate retention and transport under current and future climate scenarios. Three main objectives will be met: (1) measure how the percent nitrate removal within delta channels varies as a function of channel size, (2) quantitatively relate nitrate retention in large Arctic deltas to structural differences between deltas to inform the potential of different Arctic delta types to act as nitrate removal hotspots and (3) explore and compare nitrate retention under future climatic scenarios in the six Arctic Great River deltas. The relationship between stream size and nitrate removal will inform the removal kinetics necessary for upscaling to network-wide models. Morphologic and hydrologic models of the six largest Arctic deltas will be developed based on remotely-sensed surface water observations and delta morphometrics will be used to compare nitrate retention between deltas of differing structures. Except for insight from a few studies, nitrate processing downstream of delta apexes and upstream of the coast are virtually unknown. This study provides a necessary step to understanding nitrate removal across vast remote areas of the Arctic by using remotely-sensed surface water observations coupled with removal kinetics. This project received co-funding from the Hydrologic Science program in the Division of Earth Sciences and the Established Program to Stimulate Competitive Research (EPSCoR).This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.