U.S.
JGOFS
Synthesis & Modeling Project |
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Fei Chai
Co-Investigators:
Biogeochemical modeling of carbon partitioning in the Pacific: the role of Si and Fe in regulating production by siliceous and calcifying phytoplankton For Period: 4/1/2002 - 3/31/2005 |
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PROJECT DESCRIPTION: |
Physical and biological interactions play a complex role in the
partitioning of carbon between the atmosphere, upper ocean, deep ocean
and sediments. At present, interdisciplinary models offer the best means
to test hypotheses about how carbon partitioning is regulated in various
oceanic regions on time scales of years to centuries. The work proposed
here is a new interdisciplinary modeling effort that brings together
advances made in several areas important to the oceanic carbon cycle, and
builds upon our current modeling effort. Our existing 1-D model for the
equatorial Pacific upwelling system includes total dissolved inorganic
carbon (TCO2), three nutrients (nitrate, ammonium and silicate), two
phytoplankton components (diatoms and picoplankton), two grazing
components (mesozooplankton and microzooplankton), and two detrital
components (detrital N and Si). Based upon results from the existing
model, we propose to investigate two related hypotheses:
1) that switches between diatoms and other phytoplankton groups (e.g.
non siliceous picoplankton and calcifying phytoplankton) control carbon
partitioning, such switches vary spatially and temporally and are regulated
by Si and Fe in combination;
2) that changes in Si trapping in the Southern Ocean affect Si(OH)4
concentrations and Si and C uptake by equatorial phytoplankton that
affect TCO2 thereby altering air-sea exchange of CO2 at the equator.
To test these hypotheses, we propose to 1) add a calcifying phytoplankton component to the existing phytoplankton compartments in the biogeochemical model to investigate the role of biogenic calcite formation with its potential to affect alkalinity and hence air-sea CO2 flux and downward carbon flux out of the euphotic zone; 2) include carbon system dynamics so that it will be possible to model alkalinity and inorganic carbon speciation due to calcite production and dissolution; 3) spatially expand the improved biogeochemical model developed for the equatorial Pacific to include the Polar Front of the Southern Ocean to the equatorial region; and 4) improve application of the Fe-sensitive growth parameters of the model to enable model experiments to be conducted to understand ecosystem response to Fe enrichments in the equatorial Pacific Ocean and the Southern Ocean. Accomplishing these objectives will provide an improved modeling approach to evaluate partitioning of carbon in the ocean and the importance of biological production by different phytoplankton in affecting surface TCO2 and thereby global air-sea flux of CO2.
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DATA: |
no data submitted
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PUBLICATIONS: |
no publications listed
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RELATED PROJECTS: | Barber et al.
"New and export productivity regulation by Si and Fe in the Equatorial
Pacific Ocean."
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INVESTIGATOR
INFORMATION: |
Fei Chai
School of Marine Sciences University of Maine 5741 Libby Hall Orono, ME 04469-5741 tel: (207) 581-4317 fax: (207) 581-4388 fchai@maine.edu http://www.ume.maine.edu/~marine/chai.htm Richard Dugdale
Richard Barber
Tsung-Hung Peng
Frances P. Wilkerson
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