USAP-DC

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Application of a New Method for Isotopic Analysis of Diatom Microfossil-bound Nitrogen Description/Abstract The Southern Ocean may play a central role in causing ice ages and general global climate change. This work will reveal key characteristics of the glacial ocean, and may explain the cause of glacial/interglacial cycles by measuring the abundances of certain isotopes of nitrogen found in fossil diatoms from Antarctic marine sediments. Diatom-bound N is a potentially important recorder of nutrient utilization. The Southern Ocean's nutrient status, productivity and circulation may be central to setting global atmospheric CO2 contents and other aspects of climate. Previous attempts to make these measurements have yielded ambiguous results. This project includes both technique development and analyses, including measurements on diatoms from both sediment traps and culture experiments. With regard to broader impacts, this grant is focused around the education and academic development of a graduate student, by coupling their research with mentorship of an undergraduate researcher Personnel Person Role Sigman, Daniel Investigator Funding Antarctic Earth Sciences Award # 0453680 AMD - DIF Record(s) NSF-ANT04-53680 Data Management Plan None in the Database Product Level: Not provided Datasets Repository Title (link) Format(s) Status NCEI Robinson et al. 2004 Southern Ocean Diatom-bound Nitrogen and d15N Data None exist Publications Morales, L. V., Granger, J., Chang, B. X., Prokopenko, M. G., Plessen, B., Gradinger, R., & Sigman, D. M. (2014). Elevated 15N/14N in particulate organic matter, zooplankton, and diatom frustule-bound nitrogen in the ice-covered water column of the Bering Sea eastern shelf. Deep Sea Research Part II: Topical Studies in Oceanography, 109, 100–111. (doi:10.1016/j.dsr2.2014.05.008) Rafter, P. A., DiFiore, P. J., & Sigman, D. M. (2013). Coupled nitrate nitrogen and oxygen isotopes and organic matter remineralization in the Southern and Pacific Oceans. Journal of Geophysical Research: Oceans, 118(10), 4781–4794. (doi:10.1002/jgrc.20316) Fripiat, F., Sigman, D. M., Massé, G., & Tison, J. (2015). High turnover rates indicated by changes in the fixed N forms and their stable isotopes in Antarctic landfast sea ice. Journal of Geophysical Research: Oceans, 120(4), 3079–3097. (doi:10.1002/2014jc010583) Ren, H., Brunelle, B. G., Sigman, D. M., & Robinson, R. S. (2013). Diagenetic aluminum uptake into diatom frustules and the preservation of diatom-bound organic nitrogen. Marine Chemistry, 155, 92–101. (doi:10.1016/j.marchem.2013.05.016) Platforms and Instruments