Award Abstract # 1458305
Collaborative Research: GEOTRACES Arctic Section: Radium and Thorium Isotopes as Natural Geochemical Tracers in the Arctic Ocean

NSF Org: OCE
Division Of Ocean Sciences
Recipient: WOODS HOLE OCEANOGRAPHIC INSTITUTION
Initial Amendment Date: February 12, 2015
Latest Amendment Date: January 17, 2017
Award Number: 1458305
Award Instrument: Continuing Grant
Program Manager: Henrietta Edmonds
hedmonds@nsf.gov
 (703)292-7427
OCE
 Division Of Ocean Sciences
GEO
 Directorate For Geosciences
Start Date: February 15, 2015
End Date: January 31, 2019 (Estimated)
Total Intended Award Amount: $1,244,524.00
Total Awarded Amount to Date: $1,244,524.00
Funds Obligated to Date: FY 2015 = $511,679.00
FY 2016 = $581,393.00

FY 2017 = $151,452.00
History of Investigator:
  • Matthew Charette (Principal Investigator)
    mcharette@whoi.edu
  • Ken Buesseler (Co-Principal Investigator)
Recipient Sponsored Research Office: Woods Hole Oceanographic Institution
266 WOODS HOLE RD
WOODS HOLE
MA  US  02543-1535
(508)289-3542
Sponsor Congressional District: 09
Primary Place of Performance: Woods Hole Oceanographic Institution
360 Woods Hole Road
Woods Hole
MA  US  02543-0151
Primary Place of Performance
Congressional District:
09
Unique Entity Identifier (UEI): GFKFBWG2TV98
Parent UEI:
NSF Program(s): Chemical Oceanography,
ANS-Arctic Natural Sciences
Primary Program Source: 01001617DB NSF RESEARCH & RELATED ACTIVIT
0100XXXXDB NSF RESEARCH & RELATED ACTIVIT
Program Reference Code(s): 1079, 4444, 9156, 9189
Program Element Code(s): 1670, 5280
Award Agency Code: 4900
Fund Agency Code: 4900
Assistance Listing Number(s): 47.050

ABSTRACT

In this project, investigators participating in the 2015 U.S. GEOTRACES Arctic expedition will measure radium and thorium isotopes in the western Arctic Ocean. In common with other national initiatives in the International GEOTRACES Program, the goals of the U.S. Arctic expedition are to identify processes and quantify fluxes that control the distributions of key trace elements and isotopes in the ocean, and to establish the sensitivity of these distributions to changing environmental conditions. Some trace elements are essential to life, others are known biological toxins, and still others are important because they can be used as tracers of a variety of physical, chemical, and biological processes in the sea. The radionuclides to be measured as part of this project are important because they are oceanographic tracers that provide information on rates of cycling of other trace elements. The project will involve training opportunities for graduate student researchers and for undergraduate students from under-represented groups. Results from the study will be shared publicly through the Woods Hole Oceanographic Institution?s Center for Marine and Environmental Radioactivity.

While other GEOTRACES projects will map the distribution of numerous trace elements and their isotopes (TEIs), their distribution cannot be properly interpreted without concurrent measurement of tracers capable of providing rates of internal TEI cycling processes and fluxes at boundaries and across interfaces. The isotopes to be measured in this project include a suite of uranium/thorium series radionuclides, including the shorter-lived 234-Th and 228-Th as well as the radium quartet (224-Ra, 223-Ra, 228-Ra, 226-Ra). These tracers have the appropriate half-lives and reactivities to allow for study of horizontal and vertical transport and mixing, as well as removal at ocean boundaries, supply via rivers and submarine groundwater discharge, surface scavenging and export and subsurface remineralization. The researchers have considerable experience developing and implementing the most efficient methods to sample and quantify this suite of tracers, which includes use of battery powered in-situ pumps for large volume sampling. Hence, in addition to the proposed work on uranium/thorium series radionuclides, the team will also provide a service to other GEOTRACES researchers by coordinating pump use and sampling for many essential particulate TEIs.

PUBLICATIONS PRODUCED AS A RESULT OF THIS RESEARCH

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Kipp, Lauren E. and Charette, Matthew A. and Moore, Willard S. and Henderson, Paul B. and Rigor, Ignatius G. "{Increased fluxes of shelf-derived materials to the central arctic ocean}" Science Advances , 2018 10.1126/sciadv.aao1302
{Rutgers van der Loeff}, Michiel and Kipp, Lauren and Charette, Matthew A. and Moore, Willard S. and Black, Erin and Stimac, Ingrid and Charkin, Alexander and Bauch, Dorothea and Valk, Ole and Karcher, Michael and Krumpen, Thomas and Casacuberta, N{\'{u}} "{Radium Isotopes Across the Arctic Ocean Show Time Scales of Water Mass Ventilation and Increasing Shelf Inputs}" Journal of Geophysical Research: Oceans , 2018 10.1029/2018JC013888
Kipp, L.E., Charette, M.A., Moore, W.S., Henderson, P.B., Rigor, I.G. "Increased fluxes of shelf-derived materials to the central Arctic Ocean" Science Advances , v.4 , 2018 , p.eaao1302
Charette, M.A., P.J. Lam, M.C. Lohan, E.Y. Kwon, V. Hatje, C. Jeandel, A.M. Shiller, G.A. Cutter, A. Thomas, P.W. Boyd, W.B. Homoky, A. Milne, H. Thomas, P.S. Andersson, D. Porcelli, T. Tanaka, W. Geibert, F. Dehairs, J. Garcia-Orellana "Coastal ocean and shelf-sea biogeochemical cycling of trace elements and isotopes: lessons learned from GEOTRACES" Philosophical Transactions of the Royal Society A , v.374 , 2016 , p.20160076 10.1098/rsta.2016.0076

PROJECT OUTCOMES REPORT

Disclaimer

This Project Outcomes Report for the General Public is displayed verbatim as submitted by the Principal Investigator (PI) for this award. Any opinions, findings, and conclusions or recommendations expressed in this Report are those of the PI and do not necessarily reflect the views of the National Science Foundation; NSF has not approved or endorsed its content.

This NSF funded research project found surprising evidence of rapid climate change in the Arctic: In the middle of the Arctic Ocean near the North Pole, scientists discovered that the levels of radium-228 have almost doubled over the last decade.

The finding indicates that large-scale changes are happening along the coast?because the source of the radium is the land and shallow continental shelves surrounding the ocean. These coastal changes, in turn, could also be delivering more nutrients, carbon, and other chemicals into the Arctic Ocean and lead to dramatic impacts on Arctic food webs and animal populations.

The research team suspects that melting sea ice has left more open water near the coast for winds to create waves. The wave action reaches down to the shallow shelves and stirs up sediments, releasing radium that is carried to the surface and away into the open ocean. The same mechanism would likely also mobilize and deliver more nutrients, carbon, and other chemicals into the Arctic Ocean, fueling the growth of plankton at the bottom of the food chain. That, in turn, could have significant impacts on fish and marine mammals and change the Arctic ecosystem.

But there are other possible contributing factors that are causing changes over the shelf, the scientists say. More wave action can also cause more coastline erosion, adding more terrestrial sediment into the ocean. Warming temperatures can thaw permafrost, liberating more material into the ocean, and increasing river and groundwater runoff can carry more radium, nutrients, carbon, and other material into the Arctic.

The researchers contend that continued monitoring of shelf inputs to Arctic surface waters is vital to understand how the changing climate will affect the chemistry, biology, and economic resources of the Arctic Ocean. 

-Lonny Lippsett, Lauren Kipp, and Matt Charette


Last Modified: 04/19/2019
Modified by: Matthew A Charette

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