CAREER: Nitrate Isotopes and Biogeochemistry: A Plan for Coupling

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ABSTRACTOCE-0447570Biogeochemistry, which investigates the environmental fluxes of biologically important elements, is an emerging interdisciplinary field, and the use of the stable isotope distributions of nitrogen-bearing compounds is a developing area within biogeochemistry. In this project, a faculty member at Princeton University expects to promote the future of biogeochemistry as a field by integrating undergraduate education into his research into the use of stable isotopes to understand the marine nitrogen cycle.The Princeton University community has remarkable expertise in biogeochemistry and its interaction with the physics of the ocean and atmosphere. Complementarily, the university works to engage undergraduates in research activities through the universal requirement of a senior thesis. To link these two strengths, this project will feature a summer undergraduate research program to fund senior thesis-related projects that benefit from and support the research of graduate students in biogeochemistry. Working with a graduate student mentor, the principal investigator himself, and another faculty member or NOAA Geophysical Fluid Dynamics Laboratory scientist in some cases, each undergraduate will pursue a project that is appropriate for a senior thesis and potentially publishable. Because the project will also be designed to further the research goals of the graduate student mentor, the mentor will have appropriate expertise and additional motivation. The continuity of the summer research program with the completion of the thesis during the next academic year increases the potential for significant accomplishment and true synergy between the educational and research goals of the program. This program builds upon the principal investigator's effort to engage students in the environmental Earth sciences at multiple stages in their undergraduate career.Nitrate is a ubiquitous form of biologically available nitrogen in the environment. Based on previous method development in the principal investigator's laboratory, the graduate students and undergraduates will investigate the nitrogen (N) and oxygen (O) isotopes of nitrate as 'tracers' of the N cycle, focusing on the marine environment. Research will center on two projects that draw upon the expertise from across the university: (1) lab culture, in vitro assay, and field incubation studies of the coupled N and O isotope dynamics of nitrate assimilation and denitrification, two of the critical reactions in the N cycle; and (2) incorporation of the N and O isotopes of nitrate into numerical models of ocean circulation and biogeochemistry. These projects, in the context of the oceanic data sets generated in the principal investigator's laboratory, will allow for the quantification of biogeochemical processes the signals of which are otherwise complicated by their simultaneous occurrence and by ocean circulation. The broader impacts of this project include the anticipated recruitment of highly capable students into the environmental Earth sciences and the exposure of future individuals of influence to scientific studies of the environment. This program directly involves only a modest number of students, but it completes a multi-stage strategy for engaging students in the environmental Earth sciences. Moreover, its impact will be amplified by the campus presence of such advanced undergraduate activities in environmental Earth science and the role of the program as a testing ground for senior thesis-supported activities in this area.