Workshop Sponsors

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Workshop Sponsors

• National Science Foundation, Division of
  Environmental Biology
• National Science Foundation, Division of Earth
  Sciences
• Environmental Protection Agency, Clean Air
  Markets Division
• International Global Atmospheric Chemistry
  (IGAC) Program Seattle, Roma, and Tapei offices
• National Aeronautics and Space Administration,
  Terrestrial Ecology Program

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Atmosphere
Terrestrial Ecosystems
Human Activities
The Nitrogen Cascade
Aquatic Ecosystems
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Atmosphere
PM Visibility Effects
Ozone Effects
NOx
Energy Production
Terrestrial Ecosystems
Human Activities
The Nitrogen Cascade
Aquatic Ecosystems
--Indicates denitrification potential
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Atmosphere
PM Visibility Effects
Ozone Effects
NOx
Energy Production
Terrestrial Ecosystems
Forests Grassland
Soil
Groundwater Effects
Human Activities
The Nitrogen Cascade
Surface water Effects
Coastal Effects
Aquatic Ecosystems
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Atmosphere
PM Visibility Effects
Ozone Effects
NOx
Energy Production
Terrestrial Ecosystems
Food Production
NHx
Agroecosystem Effects
Forests Grassland
Crop
Animal
People (Food Fiber)
Soil
Soil
Norg
Groundwater Effects
Human Activities
The Nitrogen Cascade
Surface water Effects
Coastal Effects
Aquatic Ecosystems
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Atmosphere
PM Visibility Effects
Ozone Effects
NOx
Energy Production
Terrestrial Ecosystems
NOx
NH3
Food Production
NHx
Agroecosystem Effects
Forests Grassland
Crop
Animal
People (Food Fiber)
Soil
Soil
Norg
NO3
Groundwater Effects
Human Activities
The Nitrogen Cascade
Surface water Effects
Coastal Effects
Aquatic Ecosystems
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Atmosphere
Stratospheric Effects
PM Visibility Effects
Ozone Effects
Greenhouse Effects
NOx
Energy Production
Terrestrial Ecosystems
N2O
NOx
NH3
Food Production
NHx
Agroecosystem Effects
Forests Grassland
Crop
Animal
People (Food Fiber)
Soil
Soil
Norg
NO3
Groundwater Effects
Human Activities
The Nitrogen Cascade
Surface water Effects
Coastal Effects
N2O
Aquatic Ecosystems
--Indicates denitrification potential
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Seitzinger Kroeze, 1998
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Reasons for lack of knowledge about N2
production (1) it is difficult to measure due
to the high atmospheric background
concentrations (2) N2 production rates are very
heterogeneous in space and time and (3) there
is a lack of synergy between the scientific
communities that determine N2 production rates.
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Objectives (1) to evaluate the state of our
knowledge of denitrification rates in a wide
range of terrestrial and aquatic ecosystems (2)
to compare methodologies that have been adopted
by different scientific disciplines, with the
expectation that collaborations across
disciplines could yield methodological advances
(3) to chart out the current weaknesses and the
actions needed to address those weaknesses for an
improved global assessment of where, when, and
how much reactive N is converted to N2 in the
biosphere.
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The Enigma of Soil Nitrogen Balance Sheets
regardless of years of research, an accurate soil
nitrogen balance sheet for a field soil can
seldom be drawn up. we usually lack
quantitative data because of the experimental
difficulties encountered in obtaining them. In
order to obtain accurate values for some sources
of gains and losses it is necessary to make the
experimental conditions artificial. The
experimenter then wonders how closely the data
obtained apply under field conditions. the
enigma of soil nitrogen balance sheets is much
less of an enigma now than it was a few years
ago. Enough facts have been established to
permit rather satisfactory explanations for most
observed unsatisfactory balances Although the
main mechanisms of loss are probably known,
quantitative data relating to each type of loss
are certainly inadequate.
F.E. Allison, Advances in Agronomy 7213-251. 1955
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Investigations on Denitrification Quantified NO,
N2O, and N2 emissions from soils in laboratory
incubations receiving K15NO3, using mass
spectrometry Systematically varied one variable
while holding others constant temperature,
water content, pO2, aggregate size, pH,
organic-C, nitrite, nitrate, iron Formed the
basis of our current understanding of the roles
of electron donors and electron acceptors as
regulators of denitrification rates and relative
proportions of gaseous end products
Hans Nõmmik, Acta Agriculturx Scandinavica
6195-228, 1956.
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Original idea Jim Galloway
Fund raisers and organizers Sybil Seitzinger
Eric Davidson
Advisors Elizabeth Boyer, Mary Firestone, Anne
Giblin, Wendell Gilliam, Peter Groffman, Luiz
Martinelli, Lars Peter Nielsen, and Mary Scholes
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Two important considerations superimposed over
the matrix of ecosystem types and methodological
approaches (1) What are the appropriate scales
over which N2 production can and should be
measured? and (2) How can models be integrated
with the measurements to improve mechanistic
understanding of the processes and permit
estimation of fluxes at larger spatial scales,
longer temporal scales, and across a range of
forecasted scenarios?
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• Workshop products
• Special issue of Biogeochemistry
• Report to funding agencies
• Research Coordination Network
• Integrated Research Projects

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• Discussion Foci for Breakout Groups on Day 1
• Group A Technological advances for quantifying
  N2 production
• Discussion leader R. James Stevens
• Rapporteur Tibisay Perez
• What are the current technological limitations
  of measuring denitrification in various
  environments?
• How could we improve and/or adapt existing
  techniques that have proven effective in one
  environment and at one scale
• - for use in other environments
• - to address larger temporal and spatial scales
• How can information about methodological
  developments be shared most efficiently across
  disciplines and among both aquatic and
  terrestrial researchers? Would an Research
  Coordination Network (RCN) help?

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Discussion Foci for Breakout Groups on Day
1 Group B Application of methodologies to
ecosystem studies Discussion leader Jerry
Melillo Rapporteur John Harrison How can we
apply existing tools and combinations of tools in
a more integrated way across landscapes and
waterscapes? What sets of measurements (for
denitrification and other parameters) complement
each other best and in which environments? How
do we get at controlling factors and move toward
an integrated measurement/ modeling approach from
microbasins to large river basins, to global
assessments? Is the time ripe for assembling a
research group that addresses denitrification
from several disciplines and methodologies, as in
a Frontiers in Integrative Biological Research
(FIBR)-like project? If so, what might that
project look like?
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Discussion Foci for Breakout Groups on Day
2 Group C Integrating denitrification
estimates from soils to streams Discussion
leaders Wendell Gilliam and Louis
Shipper Rapporteur Madura Kulkarni Group D
Integrating denitrification estimates from fresh
to salt water Discussion leader Anne
Giblin Rapporteur Kevin Kroeger
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• Discussion Foci for Breakout Groups on Day 2
• Both groups have the same set of questions
• What do we know/not know about tracing the
  transport and ultimate removal by denitrification
  of natural and anthropogenic N sources across
  ecosystems (from terrestrial to marine)?
• How can we scale up in space and time? Can we
  make quantitative estimates of denitrification
  rates for specific regions or land uses,
  watershed, coastal shelves, etc.? Can we color a
  map (at any scale) with ranges of kgN/ha/yr
  denitrified, supported either by field
  measurements or model output? What is the
  current uncertainty in such estimates? Where are
  the gaps? Which ecosystems and where on earth do
  we have/not have reliable N2 production
  measurements?
• What knowledge would be required to develop an
  integrated assessment/understanding of N removal
  (specific natural anthropogenic sources) by
  denitrification at watershed/regional/global
  scales? What steps (measurements/methods/models/s
  cales) would be required to attain that knowledge?

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• Discussion Foci for Breakout Groups on Day 2 -
  continued
• Would a Research Coordinated Network (RCN)
  provide some benefit for scaling up
  denitrification rates to the globe or for
  identifying weaknesses in our understanding of
  denitrification rates throughout the world?
• What network of people (expertise and
  disciplines) would be required to accomplish
  this? (e.g., biogeochemists, groundwater
  hydrologists, engineers, instrument development
  specialists, nanotechnologists, statisticians,
  agronomists, etc.). What group(s) should be
  invited to the next workshop that is (are) not
  present here?
• Would the development of this knowledge benefit
  by integrating managers and policy makers into
  the process? If so, what would be the benefit
  and how might this be accomplished?

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