The silicon (Si) isotope proxy is increasingly being used to assess the role of diatoms and silicic acid in past shifts in ocean productivity and their implication for climate; however, before it can be successfully used, we need to understand the mechanisms that control the spatial and temporal variability of the Si isotope composition in ventilating water masses. A scientist from the University of California, Santa Barbara put forth the hypothesis that the Si isotope distribution is a function of the coupling of fractionation during silica production and during silica dissolution to the biological pump and the meridional overturning circulation (MOC). To test the hypothesis, the researcher plans to measure Si isotopes within the major water masses of the North Atlantic, a key end member within the MOC (i.e., surface and mode waters, the southward flowing North Atlantic Deep Water, and its northward flowing counterparts: Antarctic Intermediate Water and Antarctic Bottom Water). In addition, because the samples for the Si isotope work are being collected as part of the 2011 GEOTRACES North Atlantic zonal section, the scientist has the opportunity to collaborate with researchers working on nitrogen (N) isotopes to determine the controls on N and Si isotope dynamics and create the first numerical model that includes both isotopes, as well as incorporates Si isotope fractionation during silica dissolution.

In terms of the broader impacts, data generated will be submitted to the GEOTRACES databases and thereby be readily available to the science community. Two undergraduate students will be supported and trained as part of this project.

Agency
National Science Foundation (NSF)
Institute
Division of Ocean Sciences (OCE)
Type
Standard Grant (Standard)
Application #
1129227
Program Officer
Donald L. Rice
Project Start
Project End
Budget Start
2011-09-15
Budget End
2014-08-31
Support Year
Fiscal Year
2011
Total Cost
$248,737
Indirect Cost
Name
University of California Santa Barbara
Department
Type
DUNS #
City
Santa Barbara
State
CA
Country
United States
Zip Code
93106