Woods Hole Oceanographic Institution

Rachel Stanley

»Hotspots of Productivity and Respiration
»Helium Flux Gauge
»Patchiness in Net Community Production
»Arctic Ocean Primary Productivity
»Noble Gases in Seawater
»Microphytobenthos Photosynthesis
»Apparent Oxygen Utilization Rates
»Biological Production in Western Equatorial Pacifific
»Improved Air-Sea Gas Exchange Parameterization
»Measuring Noble Gases
»Design Experiment: Air-Sea Gas Exchange
»Neutrally Buoyant Sediment Traps
»Tritium in Trees
»Heavy Metals in Trees
»Clumping of Oligonucleotides

Rachel H.R. Stanley, Burkard Baschek, Dempsey E. Lott III, and William J. Jenkins , A New Automated Method for Measuring Noble Gases and Their Isotopic Ratios in Water Samples , G3: Geochemistry, Geophyics, Geosystems, 2009

A method is presented for precisely measuring all five noble gases and their isotopic ratios in water samples using multiple programmed multistage cryogenic traps in conjunction with quadrupole mass spectrometry and magnetic sector mass spectrometry. Multiple automated cryogenic traps, including a two-stage cryotrap used for removal of water vapor, an activated charcoal cryotrap used for helium separation, and a stainless steel cryotrap used for neon, argon, krypton and xenon separation, allow reproducible gas purification and separation. The precision of this method, determined by repeated measurements on air standards, is ±0.1% for He, ±0.14% for Ne, ±0.10% for Ar, ±0.14% for Kr, and ±0.17% for Xe.  The precision of the isotopic ratios of the noble gases in gas standards are ±1.9 permil  for 20Ne/22Ne, ±2.0 permil  for 84Kr/86Kr, ±2.5 permil for 84Kr/82Kr, ±0.9 permil  for 132Xe/129Xe and ±1.3 permil  for 132Xe/136Xe.  The precision of this method for water samples, determined by measurement of duplicate pairs, is ±1% for He, ±0.9% for Ne,  ±0.3% for Ar, ±0.3% for Kr, and  ±0.2% for Xe. An attached magnetic sector mass spectrometer measures 3He/4He with precisions of ±0.1% for air standards and ±0.14% for water samples.

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