Journal
RAPID COMMUNICATIONS IN MASS SPECTROMETRY
Volume 32, Issue 10, Pages 801-814Publisher
WILEY
DOI: 10.1002/rcm.8099
Keywords
-
Funding
- Japan Society for the Promotion of Science [21671001, 26241011, 15KK0027, 17H06320]
- National Science Foundation [05-3863009-44343]
- Schweizerischer Nationalfonds zur Forderung der Wissenschaftlichen Forschung [P2BEP2_152071]
- Swiss National Science Foundation (SNF) [P2BEP2_152071] Funding Source: Swiss National Science Foundation (SNF)
- Grants-in-Aid for Scientific Research [15KK0027, 26241011] Funding Source: KAKEN
Ask authors/readers for more resources
RationaleThe global ocean constitutes the largest heat buffer in the global climate system, but little is known about its past changes. The isotopic and elemental ratios of heavy noble gases (krypton and xenon), together with argon and nitrogen in trapped air from ice cores, can be used to reconstruct past mean ocean temperatures (MOTs). Here we introduce two successively developed methods to measure these parameters with a sufficient precision to provide new constraints on past changes in MOT. MethodsThe air from an 800-g ice sample - containing roughly 80mL STP air - is extracted and processed to be analyzed on two independent dual-inlet isotope ratio mass spectrometers. The primary isotope ratios (N-15, Ar-40 and Kr-86 values) are obtained with precisions in the range of 1 per meg (0.001) per mass unit. The three elemental ratio values Kr/N-2, Xe/N-2 and Xe/Kr are obtained using sequential (non-simultaneous) peak-jumping, reaching precisions in the range of 0.1-0.3. ResultsThe latest version of the method achieves a 30% to 50% better precision on the elemental ratios and a twofold better sample throughput than the previous one. The method development uncovered an unexpected source of artefactual gas fractionation in a closed system that is caused by adiabatic cooling and warming of gases (termed adiabatic fractionation) - a potential source of measurement artifacts in other methods. ConclusionsThe precisions of the three elemental ratios Kr/N-2, Xe/N-2 and Xe/Kr - which all contain the same MOT information - suggest smaller uncertainties for reconstructed MOTs (+/- 0.3-0.1 degrees C) than previous studies have attained. Due to different sensitivities of the noble gases to changes in MOT, Xe/N-2 provides the best constraints on the MOT under the given precisions followed by Xe/Kr, and Kr/N-2; however, using all of them helps to detect methodological artifacts and issues with ice quality.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available