NSF East Asia and Pacific Summer Institute (EAPSI) for FY 2013 in Japan

Enders Sara K, Davis CA

Investigators

Abstract

This action funds Sara Enders of the University of California, Davis to conduct a research project in Geology during the summer of 2013 at The Japan Agency for Marine Earth-Science and Technology (JAMSTEC) in Yokuska, Japan. The project title is "Developing a New Biomarker-Based Proxy for Past Terrestrial Nitrogen Cycles." The host scientist is Dr. Naohiko Ohkouchi. This project develops a method to reconstruct how nitrogen cycles of pre-industrial landscapes behaved in the past during periods of environmental and ecological change. Changes in past nitrogen cycle behavior--e.g. the availability of nitrogen to plants, and whether nitrogen losses from the ecosystem have a dominant atmospheric or hydrologic fate--may be inferable from information contained in the isotope ratios (delta-N-15) of nitrogenous plant compounds that persist in soil. The project investigates the potential to reconstruct delta-N-15 of leaves on past landscapes from the delta-N-15 of chlorophyll degradation products extractable from soil. This research evaluates 1) the persistence of the target plant compounds in soil--duration and mechanisms; and 2) the quality of information obtainable--whether isotope ratios are conserved as plants tissues degrade to soil organic matter. This method could remove significant limitations (e.g. diagenetic vulnerability, confounding trophic effects, and availability of fossil material) to a paleoreconstruction approach to testing major working hypotheses about how N and C biogeochemical cycles interact over decade to millennial timescales. Broader impacts of an EAPSI fellowship include providing the Fellow a first-hand research experience outside the U.S.; an introduction to the science, science policy, and scientific infrastructure of the respective location; and an orientation to the society, culture and language. These activities meet the NSF goal to educate for international collaborations early in the career of its scientists, engineers, and educators, thus ensuring a globally aware U.S. scientific workforce. Furthermore, this project represents a new interdisciplinary collaboration uniting different and complementary expertise: in terrestrial vs. aquatic ecosystems, modern vs. ancient environments, and analytical vs. modeling methodologies.