New Methods for Measuring Atmospheric Heavy Noble Gas Isotope and Elemental Ratios in Ice Core Samples ...

• Main Authors: Bereiter, Bernhard, Kawamura, Kenji, Severinghaus, Jeffrey P.
• Format: Text
• Language: English
• Published: Wiley 2018
• Subjects: 530 Physics; ice core
• Online Access: https://dx.doi.org/10.7892/boris.113870; https://boris.unibe.ch/113870/

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 ...