Acquisition of an isotope-ratio-monitoring mass spectrometer at the University of Massachusetts Amherst

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This award funds a replacement for a 17-year old stable isotope mass spectrometer at the University of Massachusetts Amherst. Faculty members, postdoctoral scholars, and graduate and undergraduate students from the Five Colleges Geology Consortium (Amherst College, Hampshire College, Mount Holyoke College, Smith College and UMass Amherst) will use this instrument to investigate diverse questions relating to Eart's history and environmental change. Two primary isotopes that will be measured are oxygen and deuterium, which are used to trace processes occurring within the water cycle. Measuring oxygen or deuterium isotopes in geological archives, such as speleothems or ocean sediments, provides a way of examining what Earth's water cycle was like during times in the past when atmospheric carbon dioxide (CO2; an important greenhouse gas) levels were similar to today. By using isotopes to study the water cycle in the past, we gain important information on what future conditions on Earth will be like. The researchers will offer a short course on isotopes, which will be open to faculty, postdoctoral scholars, graduate students and undergraduates from nearby community colleges and state colleges, to reach new users and communicate scientific results to a wider audience; all participants will gain hands-on experience measuring isotopes with the new mass spectrometer.This award allows for the purchase a ThermoElectron Delta V, equipped with a dual inlet, an IsoLink II, a Trace GC, and Conflow IV. Three major research projects will be enabled by the new instrumentation: (1). The mid-Pliocene warm period (mPWP), from ~3.3 to 3.0 Ma, is a current priority of the international research community because it is the most recent interval in Earth's history with higher carbon dioxide (CO2) concentrations than the pre-industrial Holocene. Carbon and hydrogen (deuterium) isotopes of leaf waxes preserved in marine and lacustrine sediments from key sites in the Arctic (Siberia) and tropics (Africa, Australia) provide information regarding past hydroclimate variability and vegetation response to past warm periods, including the mPWP and Pleistocene interglacials, with direct relevance to projections of future climate. (2). The production of CO2 in upland soil environments profoundly shapes the fluxes of carbon from terrestrial streams to the ocean-atmosphere system. This occurs through both its modulation of (a) groundwater pCO2 and subsequent evasion rates to the atmosphere in stream headwaters, and (b) proton supplies to chemically weather bedrock and transport alkalinity. The quantitative description of these connections between soil respiration and stream carbon fluxes will help constrain terrestrial carbon budgets and provide frameworks for predicting the response of these fluxes to climate change in the future and through Earth history. (3). 80% of Madagascar's population lives in poverty and is almost entirely dependent on local, subsistence agriculture to survive. Understanding past rainfall variability may provide insight to how rainfall might vary in a warming world. Studies of changes in tropical hydrology in Madagascar from speleothem isotopes will provide important new data from the Southern Hemisphere tropics and thereby help establish the timing of changes in the Indian Monsoon in the Southern versus Northern Hemispheres on orbital and millennial timescales. They will also help determine what drives interannual rainfall variability. The researchers will offer an intensive short course during the winter session in January 2020 "An Introduction to Carbon, Oxygen and Hydrogen Stable Isotopes: Application to Earth and Environmental Sciences", which will be open to students (undergraduate and graduate), postdoctoral scholars and faculty from nearby state and community colleges. Students will learn about isotopic analysis of waters, carbonates, plant leaf waxes, CO2 and dissolved inorganic carbon (DIC). The workshop, and research opportunities available at UMass, will be advertised in part by delivering short presentations to relevant classes at nearby community colleges. Through these activities, the team hopes to attract a new and diverse group of users to the UMass Stable Isotope Laboratory.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.