New Methods for Measuring Atmospheric Heavy Noble Gas Isotope and Elemental Ratios in Ice Core Samples
RATIONALE The 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 reconstru...
Published in: | Rapid Communications in Mass Spectrometry |
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ftunivbern:oai:boris.unibe.ch:113870 2023-08-20T04:07:13+02:00 New Methods for Measuring Atmospheric Heavy Noble Gas Isotope and Elemental Ratios in Ice Core Samples Bereiter, Bernhard Kawamura, Kenji Severinghaus, Jeffrey P. 2018 application/pdf https://boris.unibe.ch/113870/1/Bereiter_et_al-2018-Rapid_Communications_in_Mass_Spectrometry.pdf https://boris.unibe.ch/113870/7/Bereiter_et_al-2018-Rapid_Communications_in_Mass_Spectrometry.pdf https://boris.unibe.ch/113870/ eng eng Wiley https://boris.unibe.ch/113870/ info:eu-repo/semantics/openAccess info:eu-repo/semantics/restrictedAccess Bereiter, Bernhard; Kawamura, Kenji; Severinghaus, Jeffrey P. (2018). New Methods for Measuring Atmospheric Heavy Noble Gas Isotope and Elemental Ratios in Ice Core Samples. Rapid communications in mass spectrometry, 32(10), pp. 801-814. Wiley 10.1002/rcm.8099 <http://dx.doi.org/10.1002/rcm.8099> 530 Physics info:eu-repo/semantics/article info:eu-repo/semantics/publishedVersion PeerReviewed 2018 ftunivbern https://doi.org/10.1002/rcm.8099 2023-07-31T21:42:42Z RATIONALE The 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 MOT changes. METHODS The air from an 800g ice sample – containing roughly 80 ml STP air – was extracted and processed to be analyzed on two independent dual inlet isotope ratio mass spectrometers. The primary isotope ratios (δ15N, δ40Ar and δ86Kr values) were obtained with precisions in the range of 1 per meg (0.001‰) per mass unit. The three elemental ratio values δKr/N2, δXe/N2 and δXe/Kr were obtained using sequential (non‐simultaneous) peak‐jumping, reaching precisions in the range of 0.1 ‐ 0.3‰. RESULTS The 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. CONCLUSIONS The precisions of the three elemental ratios δKr/N2, δXe/N2 and δXe/Kr – which all contain the same MOT information – suggest smaller uncertainties for reconstructed MOTs (+/‐0.3‐0.1°C) than previous studies have attained. Due to different sensitivities of the noble gases to MOT changes, δXe/N2 provides the best constraints on the MOT under the given precisions followed by δXe/Kr, and δKr/N2; however, using all of them helps to detect methodological artifacts and issues with ice quality. Article in Journal/Newspaper ice core BORIS (Bern Open Repository and Information System, University of Bern) Rapid Communications in Mass Spectrometry 32 10 801 814 |
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Open Polar |
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BORIS (Bern Open Repository and Information System, University of Bern) |
op_collection_id |
ftunivbern |
language |
English |
topic |
530 Physics |
spellingShingle |
530 Physics Bereiter, Bernhard Kawamura, Kenji Severinghaus, Jeffrey P. New Methods for Measuring Atmospheric Heavy Noble Gas Isotope and Elemental Ratios in Ice Core Samples |
topic_facet |
530 Physics |
description |
RATIONALE The 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 MOT changes. METHODS The air from an 800g ice sample – containing roughly 80 ml STP air – was extracted and processed to be analyzed on two independent dual inlet isotope ratio mass spectrometers. The primary isotope ratios (δ15N, δ40Ar and δ86Kr values) were obtained with precisions in the range of 1 per meg (0.001‰) per mass unit. The three elemental ratio values δKr/N2, δXe/N2 and δXe/Kr were obtained using sequential (non‐simultaneous) peak‐jumping, reaching precisions in the range of 0.1 ‐ 0.3‰. RESULTS The 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. CONCLUSIONS The precisions of the three elemental ratios δKr/N2, δXe/N2 and δXe/Kr – which all contain the same MOT information – suggest smaller uncertainties for reconstructed MOTs (+/‐0.3‐0.1°C) than previous studies have attained. Due to different sensitivities of the noble gases to MOT changes, δXe/N2 provides the best constraints on the MOT under the given precisions followed by δXe/Kr, and δKr/N2; however, using all of them helps to detect methodological artifacts and issues with ice quality. |
format |
Article in Journal/Newspaper |
author |
Bereiter, Bernhard Kawamura, Kenji Severinghaus, Jeffrey P. |
author_facet |
Bereiter, Bernhard Kawamura, Kenji Severinghaus, Jeffrey P. |
author_sort |
Bereiter, Bernhard |
title |
New Methods for Measuring Atmospheric Heavy Noble Gas Isotope and Elemental Ratios in Ice Core Samples |
title_short |
New Methods for Measuring Atmospheric Heavy Noble Gas Isotope and Elemental Ratios in Ice Core Samples |
title_full |
New Methods for Measuring Atmospheric Heavy Noble Gas Isotope and Elemental Ratios in Ice Core Samples |
title_fullStr |
New Methods for Measuring Atmospheric Heavy Noble Gas Isotope and Elemental Ratios in Ice Core Samples |
title_full_unstemmed |
New Methods for Measuring Atmospheric Heavy Noble Gas Isotope and Elemental Ratios in Ice Core Samples |
title_sort |
new methods for measuring atmospheric heavy noble gas isotope and elemental ratios in ice core samples |
publisher |
Wiley |
publishDate |
2018 |
url |
https://boris.unibe.ch/113870/1/Bereiter_et_al-2018-Rapid_Communications_in_Mass_Spectrometry.pdf https://boris.unibe.ch/113870/7/Bereiter_et_al-2018-Rapid_Communications_in_Mass_Spectrometry.pdf https://boris.unibe.ch/113870/ |
genre |
ice core |
genre_facet |
ice core |
op_source |
Bereiter, Bernhard; Kawamura, Kenji; Severinghaus, Jeffrey P. (2018). New Methods for Measuring Atmospheric Heavy Noble Gas Isotope and Elemental Ratios in Ice Core Samples. Rapid communications in mass spectrometry, 32(10), pp. 801-814. Wiley 10.1002/rcm.8099 <http://dx.doi.org/10.1002/rcm.8099> |
op_relation |
https://boris.unibe.ch/113870/ |
op_rights |
info:eu-repo/semantics/openAccess info:eu-repo/semantics/restrictedAccess |
op_doi |
https://doi.org/10.1002/rcm.8099 |
container_title |
Rapid Communications in Mass Spectrometry |
container_volume |
32 |
container_issue |
10 |
container_start_page |
801 |
op_container_end_page |
814 |
_version_ |
1774718686458806272 |