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Award Detail

Doing Business As Name:University of Southern Mississippi
  • Christopher T Hayes
  • (228) 688-3469
Award Date:09/07/2017
Estimated Total Award Amount: $ 249,803
Funds Obligated to Date: $ 249,803
  • FY 2017=$67,613
  • FY 2019=$87,946
  • FY 2018=$94,244
Start Date:11/01/2017
End Date:10/31/2021
Transaction Type:Grant
Awarding Agency Code:4900
Funding Agency Code:4900
CFDA Number:47.050
Primary Program Source:040100 NSF RESEARCH & RELATED ACTIVIT
Award Title or Description:Collaborative Research: U.S. GEOTRACES Pacific Meridional Transect: Thorium-232, Thorium-231 and Protactinium-231 as tracers of trace element supply and removal
Federal Award ID Number:1737023
DUNS ID:623335775
Parent DUNS ID:623113990
Program:Chemical Oceanography
Program Officer:
  • Henrietta Edmonds
  • (703) 292-7427

Awardee Location

Street:2609 WEST 4TH ST
Awardee Cong. District:04

Primary Place of Performance

Organization Name:University of Southern Mississippi
Street:118 College Drive #5157
Cong. District:04

Abstract at Time of Award

The goal of the international GEOTRACES program is to understand the distributions of trace chemical elements and their isotopes in the oceans. Many trace elements are essential for life and their extremely low concentrations in seawater are thought to limit biological productivity (fertility) throughout much of the ocean. This limitation, in turn, partially constrains the level of fisheries that can be supported by marine ecosystems as well as the ocean's capacity to absorb carbon dioxide from the atmosphere. Whereas the importance of these trace-element micronutrients is well established, many basic features of their ocean distribution remain unknown. Measurements of other elements and isotopes can be used to understand the processes that influence the distributions of the micronutrient elements. Two naturally-occurring radioactive isotopes that are particularly important in this regard are thorium-230 and protactinium-231, which have been designated as key parameters to be measured as part of GEOTRACES. This project will focus on the measurement of these two isotopes in order to provide critical information about the processes that supply iron to the Pacific Ocean, as well as the rates of those processes. The project will support an early career investigator, a postdoctoral researcher, and students at the undergraduate and graduate levels. Samples of seawater and of suspended particulate material will be collected along a north-south transect between Alaska and Tahiti to examine the processes that supply and remove trace elements. These samples will be analyzed for naturally-occurring radionuclides thorium-232, thorium-230 and protactinium-231. Aerosol samples and sediments collected along the transect will be analyzed as well. In collaboration with other investigators involved in the expedition, this project will: 1) Interpret the distributions of thorium-232 and thorium-230 to quantify the supply of iron and other trace elements delivered by dust as well as the trace elements supplied by chemical reactions in volcanic sediments along the Alaskan margin, 2) Determine the sinking flux of major particulate phases and of particulate trace elements throughout the water column to quantify their rate of removal from the ocean, and 3) Compare the rate of trace element removal among contrasting environmental regimes to be encountered along the Alaska to Tahiti transect to identify the key physical, chemical and biological factors, such as dust supply and biological productivity, that regulate the rate of trace element removal from the ocean.

Publications Produced as a Result of this Research

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Howe, Samantha and Miranda, Carlos and Hayes, Christopher T. and Letscher, Robert T. and Knapp, Angela N. "The Dual Isotopic Composition of Nitrate in the Gulf of Mexico and Florida Straits" Journal of Geophysical Research: Oceans, v.125, 2020, p.. doi:10.1029/2020JC016047 Citation details  

Hayes, Christopher T. and Fitzsimmons, Jessica N. and Jensen, Laramie T. and Lanning, Nathan T. and Hatta, Mariko and McGee, David and Boyle, Edward A. "A Lagrangian View of Trace Elements and Isotopes in the North Pacific" Journal of Geophysical Research: Oceans, v.125, 2020, p.. doi:10.1029/2019JC015862 Citation details  

Costa, Kassandra M. and Hayes, Christopher T. and Anderson, Robert F. and Pavia, Frank J. and Bausch, Alexandra L. and Deng, Feifei W. and Dutay, Jean‐Claude S. and Geibert, Walter F. and Heinze, Christoph L. and Henderson, Gideon F. and Hillaire‐Marcel, "230 Th Normalization: New Insights on an Essential Tool for Quantifying Sedimentary Fluxes in the Modern and Quaternary Ocean" Paleoceanography and Paleoclimatology, v.35, 2020, p.. doi:10.1029/2019PA003820 Citation details  

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