Inland river networks regulate the export of nutrients from the terrestrial landscape, making them critical for mitigating eutrophication of downstream ecosystems. Yet the ability of rivers to process and retain nutrients has been understudied as previous research has focused mainly on small headwater streams. It is critical to understand how entire river ecosystems, not just sections of streams, influence regional and continental patterns of nutrient export to protect water resources. This research will use a novel field approach to gather empirical measurements of nutrient uptake in multiple rivers across the west and midwest and integrate the data into a dynamic network scale model to evaluate controls on nutrient uptake, thereby integrating aquatic ecosystem ecology and hydrological modeling. This approach will generate critical predictive relationships regarding the capacity of rivers spanning a range of nutrient and sediment conditions to mitigate downstream nutrient export, which is an essential step towards effective water quality management at the river network scale. The intellectual merit of the research includes the transformation of ecological theory regarding nutrient cycling in rivers and improved understanding of the ecosystem services that rivers provide. In turn, the broader impacts of the work will result in unparalleled educational opportunities for graduate students to collaborate on cutting edge river research, watershed modeling tools immediately useful to water resource managers, and data to improve emerging technologies for real-time nutrient monitoring to be used by national observatory programs.
