Integration of Denitrification Across Waterscapes: The EstuaryContinental ShelfOcean Continuum

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Integration of Denitrification Across
Waterscapes The Estuary-Continental
Shelf-Ocean Continuum

• Sybil P. Seitzinger
• Rutgers University
• Institute of Marine and Coastal Sciences
• Rutgers/NOAA CMER Program
• New Brunswick, NJ

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Rivers
Estuaries
Continental Shelf
Oceanic
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Rivers
Estuaries
Continental Shelf
Oceanic
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N2
N2
N2
Rivers
Estuaries
Continental Shelf
Oceanic
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Integrating Landscapes to Waterscapes
Terrestrial Rivers
Estuaries Ocean Margins Oceanic
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Estuaries - Approaches

• Small scale sediment incubations scaled up to
  whole estuary
• Mass balance calculations (ecosystem scale)
• Experimental mesocosms

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Integrating Landscapes to Waterscapes
Terrestrial Rivers
Estuaries Ocean Margins Oceanic
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Connecting land-based N inputs to estuarine
denitrification
As N Inputs to Estuaries Denitrification

Seitzinger 2000
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Connecting land-based N inputs to estuarine
denitrification
As N Inputs to Estuaries Denitrification

N inputs
Phytoplankton
N2
NO3
Seitzinger 2000
NO3 NH4 OM
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Denitrification at the Whole Estuary Scale
As Water Residence Time TN Inputs
Denitrified
Modified from Nixon et al. 1996
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• Similar relationship holds across estuaries and
  river reaches

Seitzinger 2000
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Seitzinger 2001
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Integrating Landscapes to Waterscapes
Terrestrial Rivers
Estuaries Ocean Margins Oceanic
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Integrating Landscapes to Waterscapes
Terrestrial Rivers
Estuaries Ocean Margins Oceanic
Anthropogenic N
Natural N
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Integrating Landscapes to Waterscapes
Terrestrial Rivers
Estuaries Ocean Margins Oceanic
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Connecting Estuaries to Ocean Margins
Terrestrial Rivers
Estuaries Ocean Margins Oceanic
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Connecting Estuaries to Ocean Margins
As Water Residence Time N Export to Shelf
Modified from Nixon et al. 1996
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Ocean Margins - Approaches

• Site specific measurements scaled up to whole
  shelf
• cores in situ chambers
• N2 N2Ar
• 15N annual
• stoichiometry
• sediment models
• Dynamic biogeochemical/hydrodynamic modeling

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Connecting the Ocean Margin to Estuaries and
Oceans
Terrestrial Rivers
Estuaries Ocean Margins Oceanic
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Application of stoichoimetric method in cores and
chambers scaled up using averages of other
sediment fluxes (usually benthic oxygen demand).
Regional estimates then been made by estimating
oxygen demand from overlying water primary
production (Seitzinger and Giblin 1996)
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Connecting the Ocean Margin to Estuaries and
OceansNorth Atlantic
143

• From Seitzinger Giblin 1996

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Connecting the Ocean Margin to Estuaries and
OceansNorth Atlantic
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143
59-76
46-63

• From Seitzinger Giblin 1996

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Connecting the Ocean Margin to Estuaries and
OceansNorth Atlantic
13
143
59-76
72-97
46-63

• From Seitzinger Giblin 1996

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North Atlantic

• Modified from Seitzinger Giblin 1996

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Integrating Landscapes to Waterscapes
Terrestrial Rivers
Estuaries Ocean Margins Oceanic
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Integrating Landscapes to Waterscapes
Terrestrial Rivers
Estuaries Ocean Margins Oceanic
Anthropogenic N
Natural N
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A Dynamic Biogeochemical/Hydrodynamic Model of
the MAB K. Fennel et al. unpubl. ASLO 2004

• N Based Plankton Model
• Fasham et al. 1990
• Sediment Denitrification
• Seitzinger Giblin 1996

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2-yr simulations, starting from same initial
condition in January 1994 after a 1-yr spinup
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Annual Primary Production
K. Fennel et al. unpubl. ASLO 2004
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Annual Primary Production
Denitrification River Nutrients
K. Fennel et al. unpubl. ASLO 2004
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K. Fennel et al. unpubl. ASLO 2004
Denitrification River Nutrients
Denitrification River Nutrients
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Oxygen Minimum Zones
Denitrification Tg N/y ETNP1 22 ETSP1 26 Ar
abian Sea2 33
1 Deutsch et al. 2001 2 Howell et al. 1997 Naqvi
1994
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Denitrification Not Well Quantified

• Pelagic sediments
• Microsites in aerobic water

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Integrating Landscapes to Waterscapes
Terrestrial Rivers
Estuaries Ocean Margins Oceanic
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Integrating Landscapes to Waterscapes
Terrestrial Rivers
Estuaries Ocean Margins Oceanic
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N and Beyond

• Basic explanation of N
• What papers tell us and what they dont

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Integrating Landscapes to Waterscapes
Terrestrial Rivers
Estuaries Ocean Margins Oceanic
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• Table or graph that builds DNF through
• Anthropogenic N Natural N Total
• Estuaries
• Margins
• Oceanic

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From Seitzinger 2000
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Applications for Isotope Natural Abundanced15N
and d18O (the latter in NO3-)

• In the modern, has the potential for quantitative
  verification of flux estimates through isotopic
  mass balance
• In the modern, can quantify partitioning of
  denitrification between sediments and water
  column due to nil net isotopic effect for the
  former
• In the modern, dual N and O isotope studies of
  NO3-) distinguishes between source and
  denitrification (removal) effects
• In the modern, can trace the flux of N species
  influence by denitrification (e.g. isotopically
  enriched NO3-) through watersheds and estuaries
  out to the shelf environment
• In the past, sediment d15N can be used to
  reconstruct local and regional changes in water
  column denitrification on time scales only
  limited by the resolution, extent, and fidelity
  of the sedimentary record

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Deutsch et al. GBC 2001 15483-506
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• Global map start building with where dnf
  measurements dots
• estuaries