Project Information
High-resolution, Assemblage-specific Records of Diatom-bound N Isotopes from the Indian Sector of the Antarctic Ocean
Start Date:
End Date:
Intellectual Merit:
The high concentration of the major nutrients nitrate and phosphate is a fundamental characteristic of the Antarctic Zone in the Southern Ocean and is central to its role in global ocean fertility and the global carbon cycle. The isotopic composition of diatom-bound organic nitrogen is one of the best hopes for reconstructing the nutrient status of polar surface waters over glacial cycles, which in turn may hold the explanation for the decline in atmospheric carbon dioxide during ice ages. The PIs propose to generate detailed diatom-bound nitrogen isotope (δ15Ndb) records from high sedimentation rate cores from the Kerguelen Plateau. Because the cores were collected at relatively shallow seafloor depths, they have adequate planktonic and benthic foraminifera to develop accurate age models. The resulting data could be compared with climate records from Antarctic ice cores and other archives to investigate climate-related changes, including the major steps into and out of ice ages and the millennial-scale events that occur during ice ages and at their ends. The records generated in this project will provide a critical test of hypotheses for the cause of lower ice age CO2.

Broader impacts:
This study will contribute to the goal of understanding ice ages and past CO2 changes, which both have broad implications for future climate. Undergraduates will undertake summer internships, with the possibility of extending their work into junior year projects and senior theses. In addition, the PI will lead modules for two Princeton programs for middle school teachers and will host a teacher for a six-week summer research project.
Person Role
Sigman, Daniel Investigator and contact
Antarctic Earth Sciences Award # 1401489
AMD - DIF Record(s)
Data Management Plan
None in the Database
  1. Studer, Anja S., et al. "Antarctic Zone nutrient conditions during the last two glacial cycles." Paleoceanography 30.7 (2015): 845-862. (doi:10.1002/2014PA002745)
  2. Studer, Anja S., et al. "Increased nutrient supply to the Southern Ocean during the Holocene and its implications for the pre-industrial atmospheric CO 2 rise." Nature geoscience 11.10 (2018): 756. (doi:10.1038/s41561-018-0191-8)
  3. Wang, Xingchen Tony, et al. "Deep-sea coral evidence for lower Southern Ocean surface nitrate concentrations during the last ice age." Proceedings of the National Academy of Sciences 114.13 (2017): 3352-3357. (doi:10.1073/pnas.1615718114)
  4. Fripiat, François, et al. "The isotope effect of nitrate assimilation in the Antarctic Zone: Improved estimates and paleoceanographic implications." Geochimica et Cosmochimica Acta 247 (2019): 261-279. (doi:10.1016/j.gca.2018.12.003)
  5. Kemeny P C, Kast E R, Hain M P, et al. A seasonal model of nitrogen isotopes in the ice age Antarctic Zone: Support for weakening of the Southern Ocean upper overturning cell[J]. Paleoceanography and Paleoclimatology, 2018, 33(12): 1453-1471. (doi:10.1029/2018PA003478)
  6. Smart, S. M., Fawcett, S. E., Ren, H., Schiebel, R., Tompkins, E. M., Martínez‐García, A., … Sigman, D. M. (2020). The Nitrogen Isotopic Composition of Tissue and Shell‐Bound Organic Matter of Planktic Foraminifera in Southern Ocean Surface Waters. Geochemistry, Geophysics, Geosystems, 21(2). (doi:10.1029/2019gc008440)