MRI: Acquisition of a Cavity Ring-Down Spectrometer for Analyzing Stable Isotopes in Water Samples at Middlebury College

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This Major Research Instrumentation (MRI) Program award supports acquisition of a cavity ring-down spectrometer (CRDS) for analysis of stable isotopes of oxygen in water samples. The CRDS will support research and research training in the Geology Department at Middlebury College, a non-Ph.D. granting institution. Undergraduate students at this non-Ph.D.-granting institution will be engaged in experiential learning using the CRDS for required senior theses. In total, the Geology Department typically offers ~300 seats/year in classes at all levels, and it is expected that the majority of these students will have the opportunity to use this instrument during their coursework and research. The CRDS will also serve colleagues and their students from surrounding institutions who will be invited to come to Middlebury to make analyses as part of their own research. Acquisition of a CRDS for analyzing water isotopes at Middlebury will, therefore, catalyze significant learning opportunities and hands-on research training for undergraduate students in this region.The instrument will be used extensively in the research programs of Drs. Jeffrey Munroe and Peter Ryan in the Department of Geology. Research to be facilitated by the CRDS will include: investigations of Holocene paleoclimate as recorded in in the stable oxygen and isotopes of perennial cave ice deposits; studies of rock glaciers as surface water resources in alpine landscapes; karst processes; and studies of the transport and fate of deleterious compounds in fractured groundwater aquifers. Munroe is actively studying the stable isotopic composition and glaciochemistry of perennial cave ice deposits in order to develop Holocene paleoclimate records, is investigating the significance of rock glaciers as sources of surface water in alpine landscapes, and the contribution of melting perennial ice to rock glacier outflow, and is working to develop a long-term paleoclimate records from stable isotopes in cave speleothems. Properly interpreting these records requires information about the stable isotopic composition of modern precipitation and dripwater in the caves with the speleothems were collected. The CRDS will be used in analyzing water samples collected with a recently deployed automatic drip water sampler. Ryan is low-temperature geochemist who will use the instrument in a variety of studies of aquifer recharge, flow and discharge in Vermont, as it relates to transmissivity and composition. Ryan and undergraduate student collaborators have investigated the sources of geogenic arsenic in fractured rock aquifers, evaluated heterogeneity in a uranium-rich carbonate aquifer, and considered the transport and fate of agricultural and industrial contaminants. Acquisition of a CRDS will be a major step forward for all of these projects, allowing measurements of stable isotopes in water and facilitating their use as tracers of groundwater flow.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.