| NSF Org: |
OCE Division Of Ocean Sciences |
| Recipient: |
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| Initial Amendment Date: | March 2, 2007 |
| Latest Amendment Date: | March 2, 2007 |
| Award Number: | 0648414 |
| Award Instrument: | Standard Grant |
| Program Manager: |
Donald L. Rice
OCE Division Of Ocean Sciences GEO Directorate for Geosciences |
| Start Date: | March 1, 2007 |
| End Date: | February 28, 2011 (Estimated) |
| Total Intended Award Amount: | $482,540.00 |
| Total Awarded Amount to Date: | $482,540.00 |
| Funds Obligated to Date: |
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| History of Investigator: |
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| Recipient Sponsored Research Office: |
3112 LEE BUILDING COLLEGE PARK MD US 20742-5100 (301)405-6269 |
| Sponsor Congressional District: |
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| Primary Place of Performance: |
3112 LEE BUILDING COLLEGE PARK MD US 20742-5100 |
| Primary Place of
Performance Congressional District: |
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| Unique Entity Identifier (UEI): |
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| Parent UEI: |
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| NSF Program(s): | Chemical Oceanography |
| Primary Program Source: |
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| Program Reference Code(s): |
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| Program Element Code(s): |
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| Award Agency Code: | 4900 |
| Fund Agency Code: | 4900 |
| Assistance Listing Number(s): | 47.050 |
ABSTRACT
OCE-0648414
Chromophoric dissolved organic matter (CDOM) is found ubiquitously in aquatic environments where its plays a central role, both through its impact on the aquatic light field and its photochemical reactions. Two researchers from the University of Maryland-College Park have proposed that optical absorption and emission properties of CDOM arise in part from intramolecular charge transfer interactions between hydroxy-aromatic donors and quinoid acceptors formed by the partial oxidation of soluble lignin precursors (i.e., charge transfer model). The scientists propose that the charge transfer model can largely explain the diverse suite of photochemical reactions attributed to this material and plan to test the hypothesis using a series of photochemical and photophysical measurements including the following: 1) the dependence of H2O2 quantum yields on O2 concentration and its associated wavelength dependence; 2) the dependence of the oxidation rates of selected (phenol) donors on both O2 concentration and donor concentration, as well as the associated wavelength dependencies; 3) the dependence of 1O2 yields on O2 concentrations; and 4) the wavelength dependence of emission quantum yields and lifetimes. The complete suite of measurements will be performed on one standard (Suwanee River fulvic acid) and three well-characterized aquatic humic substances (HS) collected on prior field work from oligotrophic, shelf and estuarine waters. The spectral dependence of the H2O2 yields on O2 concentration for 0.2 M-filtered, whole water samples will be compared to that of the HS samples to quantify the extent to which the properties of the HS samples reflect those of the original waters from which they were obtained. Further tests examining the impact of potentially key parameters such as pH, salinity, and metal ion content will also be conducted.
As regards broader impacts, one post doc and one graduate student will be supported and trained as part of this project. It is anticipated that undergraduate students will also participate in this study and learn about state of the art photochemical and photophysical methods.
PUBLICATIONS PRODUCED AS A RESULT OF THIS RESEARCH
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