| NSF Org: |
OCE Division Of Ocean Sciences |
| Recipient: |
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| Initial Amendment Date: | June 28, 2024 |
| Latest Amendment Date: | June 28, 2024 |
| Award Number: | 2408962 |
| Award Instrument: | Standard Grant |
| Program Manager: |
Alan Wanamaker
awanamak@nsf.gov (703)292-7516 OCE Division Of Ocean Sciences GEO Directorate for Geosciences |
| Start Date: | September 1, 2024 |
| End Date: | August 31, 2026 (Estimated) |
| Total Intended Award Amount: | $213,145.00 |
| Total Awarded Amount to Date: | $213,145.00 |
| Funds Obligated to Date: |
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| History of Investigator: |
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| Recipient Sponsored Research Office: |
9 OLD CHAPEL RD MIDDLEBURY VT US 05753-6000 (802)443-5000 |
| Sponsor Congressional District: |
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| Primary Place of Performance: |
9 Old Chapel Rd. Middlebury VT US 05753-6000 |
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Performance Congressional District: |
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| Unique Entity Identifier (UEI): |
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| NSF Program(s): |
Marine Geology and Geophysics, EPSCoR Co-Funding |
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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, 47.083 |
ABSTRACT
As the global oceans experience increasing stress from anthropogenic climate change, improving our knowledge of the responses of primary production and the concentrations of dissolved oxygen and carbon in the ocean is crucial for predicting impacts for ecosystems and human populations. Critical for refining our understanding and improving model representations of biogeochemical processes, are quantitative reconstructions of how these variables have responded to different climate states in the past. This research investigates a new proxy for bottom water oxygen concentrations and provides new records of organic carbon flux. Data generated by the project will help constrain the response of these key environmental variables to changes in global climate over the last two glacial-interglacial cycles (150 ka). This proposal broadens participation in the Earth Sciences by supporting an early career Principal Investigator from an undergraduate-only institution, providing research and professional development opportunities for an undergraduate from an underrepresented background, and supporting K-12 students via a University of Colorado at Boulder Museum of Natural History program: Girls At the Museum Enjoying Science (GAMES).
This project quantitatively investigates the variables that control alkenone biomarker preservation in open ocean marine sediments. Previous work has used sedimentary alkenone biomarker concentrations as a proxy for surface ocean export production, neglecting the well-documented influence of changes in bottom water oxygen conditions on biomarker preservation. The investigator will employ a latitudinal transect of existing sediment cores from the equatorial Pacific?s Line Islands region (cruise MGL1208) that have experienced synchronous changes in BWO to evaluate several hypotheses, including: 1) alkenone biomarkers experience quantifiable preservation changes driven by variations in sedimentary bottom water concentrations, and 2) time series of preserved biomarker fluxes, measured at sites with a range of export carbon fluxes and conditions of sedimentary preservation, can be used to quantitatively constrain the multivariate equation that relates alkenone preservation, bottom water oxygen, surface ocean carbon export, and oxygen exposure time. To evaluate these hypotheses the investigator will use cores from five sites to constrain A) alkenone biomarker flux (C37:total), B) sedimentation rate (14C and ?18O-derived age models), C) oxygen exposure time (multisensor track data), and D) organic carbon fluxes (230Th-normalized Baxs fluxes). The investigator will also generate records of E) sedimentary redox state (aU), and F) alkenone-based sea surface temperatures (UK?37). New data, in combination with published results, will refine estimates of oxygen and respired carbon storage during the Last Glacial Maximum (~20 ka), and provide the first estimates for the penultimate glacial period (~140 ka). Results will also improve our understanding of C37:total-based paleoproductivity estimates by quantifying the extent to which reconstructions may be altered by changes in bottom water oxygen. These findings will permit better reconstructions of photic zone carbon export ? a key determinant of carbon cycle changes, and a more quantitative understanding of variations in bottom water oxygen and their global drivers. This project is jointly funded by Marine Geology and Geophysics (MGG) and the Established Program to Stimulate Competitive Research (EPSCoR).
This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
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