A Macro-Scale Framework to Analyze Integrated Nitrogen Dynamics in large Drainage Systems: Application to the Mississippi River Basin

A MACRO-SCALE FRAMEWORK TO ANALYZE INTEGRATED NITROGEN DYNAMICS IN LARGE DRAINAGE SYSTEMS: APPLICATION TO THE MISSISSIPPI RIVER BASIN

 

Charles J. Vörösmarty^1,2

 

¹ Environmental Sciences Initiative of the CUNY Advanced Science Research Center at the Graduate Center, New York, NY (USA)

 

² Department of Geography and Environmental Science at CUNY Hunter College, New York, NY (USA)

 

 

Global disturbance of the nitrogen cycle is driven by anthropogenic alteration to ecosystem function through increased fertilizer use for agriculture, urbanization/sewage, and destruction of natural habitat. The Mississippi River Basin/Gulf of Mexico (MRB/GoM) is among the clearest examples of such disruption, leading to deterioration of water quality and hypoxic bottom water developing each summer at the coast. Increasing flux of reactive nitrogen (N) to rivers represents significant vulnerabilities to human health, economic productivity, and ecosystem function. Climate is a major component in determining the system’s N metabolism, and extremes such as droughts and floods have been known to result in N from fertilizer lost to the atmosphere or surface/ground water, rather than incorporation into crops. This talk describes an environmental surveillance system to monitor and understand dynamics of the near contemporary N cycle across the MRB/GoM land-to-ocean continuum. The multi-institutional effort focuses on near real-time N cycle responses to 5 categories of climate events: short-term wetting/drying, rapid freeze/thaw, heatwaves, extreme precipitation/flooding, and drought. It tests the hypothesis is that the fluxes of reactive N from the Mississippi River drainage basin to the Gulf of Mexico over the recent past are determined by the conjunction of nature-based and human-engineered infrastructures associated with a relatively small fraction of the total land mass drained by the river. We address this hypothesis via six technical objectives: (1) coalesce and integrate remotely sensed and modeled geospatial data for estimation of terrestrial loading of N for ingestion by biogeochemical models, (2) apply estimation techniques (modeling, remote sensing, and in-situ data integration) for land-to-atmosphere gaseous losses and analyze the impact of climate variability, (3) create aquatic transport and processing model estimates of N flux, representing the behavior of both engineered and natural systems, (4) carry out and validate remotely sensed inland and coastal plume analysis, (5) reconfigure existing technical integration frameworks to create C-FrAMES, uniting results and workflows described under objectives 1-4, (6) engage stakeholders including through NASA mission early adopters. The discussion explains how these activities poise us to move from contemporary monitoring into forecast mode.