Acquisition of High-Precision Mass Spectrometers for Noble Gas Isotopes as Environmental Tracers

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This award provides support to extend the capability of the Noble Gas Isotope Laboratory at Scripps Institution of Oceanography to neon, krypton and xenon isotopes, with the purchase of two new mass spectrometers. One mass spectrometer will be dedicated to measurements of natural isotopic variations in krypton and xenon, which should reveal the thickness of past "convective zones" in polar firn, as well as improving temperature change estimates made from trapped air in ice. The second mass spectrometer will be specially designed to measure neon isotopes and neon/xenon ratios in dual-collector mode which will enable monitoring of this ratio in the atmosphere, which should rise due to current ocean warming and consequent outgassing. Past variations in atmospheric Kr/N2 and Xe/N2 from ice core gases will also provide an average-ocean-temperature estimate over the past million years due to the solubility differences in these gases. Neon isotopes will shed light on fractionation processes during bubble close-off in polar ice, as well as the mechanism of supersaturation in seawater and groundwater. Neon/argon ratios in seawater as a tracer of sea ice formation by brine rejection will also be explored. . The broader impacts of the proposed acquisition are that education and training will be enhanced since graduate students will be among the primary users of the equipment. Outreach activities involving polar ice cores and climate change will be enhanced. These facilities will be available widely to others at the Institution for collaborative projects and will enhance the capabilities of Scripps and position it for a leadership role in environmental noble gas geochemistry.