EA: Peripheral Replacements for the Northwestern University Stable Isotope Biogeochemistry Laboratory

Light stable isotopes of elements including carbon (C), nitrogen (N), oxygen (O), hydrogen (H) and sulfur (S) provide records of their behaviors in biological and geological systems. Measurements of these isotopes are made to investigate land use, constrain modern climate change, unravel microbial metabolic pathways, understand biogeochemical cycling through critical time periods in Earth History, and reconstruct past environmental changes. This award funds the acquisition of instruments to maintain and expand analytical capabilities at the Northwestern Stable Isotope Biogeochemistry Laboratory (NU-SIBL), a core research facility used by Earth scientists at Northwestern University as well as across the country. Active NSF-funded grants which will be supported by this acquisition include an isotope informed paleoclimate reconstruction and proxy calibration of the Younger Dryas in Greenland, investigation of carbon cycling and sedimentation in intensively managed landscapes, characterization of microbial food webs using C, N, and H isotopes of biomass,, and interrogation of deep subsurface microbe-rock-fluid interactions. The equipment replacement and upgrade permit current and future isotope-based research within NU-SIBL as well as carry on the strong history of student training in this shared laboratory. This award funds the replacement of two peripheral instruments within the Northwestern University Stable Isotope Biogeochemistry Laboratory (NU-SIBL) including a Gas Chromatograph with combustion and pyrolysis interfaces and an Elemental Analyzer, as well as a water purification system for sample preparation. These instruments will replace nearly 15-year-old obsolete versions that have been used extensively and productively by faculty, students and collaborators in addition to external users nationally and internationally. The Gas Chromatograph system will be used to analyze compound-specific isotopic (C, H, N) composition of organic materials including plant waxes, microbial lipids, methane, and amino acids. The elemental analyzer will be used for bulk measurement of organic C, N, and S, as well as inorganic S. Funds from this award will also support direct participation high school interns to stable isotope research in cooperation with NU-Geopaths, an outreach program run by the Department of Earth and Planetary Sciences that exposes high school students from diverse backgrounds to geoscience research. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.