Control of Nitrogen Exports From River Basins to the Coastal Ocean: Evaluation of Basin Management Strategies for Reducing Coastal Hypoxia

Details

• Journal Title:
  Journal of Geophysical Research: Biogeosciences
• Personal Author:
  Lee, M. ; Jung, C. ; Shevliakova, E. ; Malyshev, S. ; Han, H. ; Kim, S. ; Kim, K. ; Jaffé, P. R.
• NOAA Program & Office:
  OAR (Oceanic and Atmospheric Research) ; CICSP (Cooperative Institute for Climate Science) ; GFDL (Geophysical Fluid Dynamics Laboratory)
• Description:
  The spread of coastal hypoxia is a pressing global problem, largely caused by substantial nitrogen (N) exports from river basins to the coastal ocean. Most previous process-based modeling studies for investigating basin management strategies to reduce river N exports focused on the impacts of different farming practices or land use, used watershed models that simplified many mechanisms that critically affect the state of N storage in land, were limited mainly to fairly small basins, and did not span multiple climate regimes. Here we use a process-based land-river model to simulate historical (1999-2010) river flows and nitrate-N exports throughout the entire drainage network of South Korea (100,210km(2)), which encompasses varying climate, land use, and hydrogeological characteristics. Based on projections by using multiple scenarios of N input reductions and climates, we explore the impacts of various ecosystem factors (i.e., N storage in basins, climate and its variability, anthropogenic N inputs, and basin location) on river nitrate-N exports. Our findings have fundamental implications for reducing coastal hypoxia: (1) a small reduction of N inputs in basins, including intensively utilized human land use, can have a greater improvement on water quality; (2) heightening climate variability may not increase long-term mean river N exports yet can significantly mask N input reduction effects by producing N export extremes associated with recurring coastal hypoxia; and (3) N exports to the coastal ocean can be most efficiently reduced by decreasing N inputs in subbasins, which are receiving high anthropogenic N inputs and are close to the coast.
• Source:
  Journal of Geophysical Research-Biogeosciences, 123(10), 3111-3123.
• DOI:
  https://doi.org/10.1029/2018jg004436
• Document Type:
  Journal Article
• Funding:
  Grant no. NA08OAR4320752 ; Grant no. NA14OAR4320106
• Rights Information:
  Other
• Compliance:
  Submitted
• Main Document Checksum:
  urn:sha256:3bf091fbcc99b62cb78e27bc1cada425185375491845acc11655d994ebfa4492
• Download URL:
  https://repository.library.noaa.gov/view/noaa/20333/noaa_20333_DS1.pdf
• File Type:
  [PDF - 1.04 MB ]