loading page

The absolute δ 18 O value for SLAP with respect to VSMOW reveals a much lower value.
  • +1
  • Anita Aerts-Bijma,
  • Albert C. van Buuren,
  • Dipayan Paul,
  • Harro Meijer
Anita Aerts-Bijma
Rijksuniversiteit Groningen Energy and Sustainability Research Institute Groningen

Corresponding Author:a.t.aerts-bijma@rug.nl

Author Profile
Albert C. van Buuren
Rijksuniversiteit Groningen Energy and Sustainability Research Institute Groningen
Author Profile
Dipayan Paul
Rijksuniversiteit Groningen Energy and Sustainability Research Institute Groningen
Author Profile
Harro Meijer
Rijksuniversiteit Groningen Energy and Sustainability Research Institute Groningen
Author Profile

Abstract

RATIONALE: SLAP is one of the two calibration materials for the isotopic water scale. By consensus the established δ 18O value is -55.5‰, although there are firm indications that δ 18O SLAP is significantly more negative. The real δ 18O SLAP value as such does not influence the isotopic water scale, however knowledge of the size of isotopic scale contraction in stable isotope measurements is vital for second order isotopes. In this study quantification of δ 18O SLAP with respect to δ 18O VSMOW is described. METHODS: SLAP-like water was quantitatively mixed with highly 18O enriched water to mimic VSMOW. The 18O concentration was determined using an electron ionization quadrupole mass spectrometer. The isotopic composition of the SLAP-like and VSMOW-like waters were measured with an optical spectrometer, alongside real VSMOW and SLAP. RESULTS: This study resulted in a much more depleted δ 18O value for SLAP than expected. The averaged outcome of 7 independent experiments is δ 18O SLAP -56.33 ± 0.03‰. There is a large discrepancy between the actual isotopic measurements of even the most carefully operating groups and the true δ 18O value. CONCLUSIONS: Although this finding as such does not influence the use of the VSMOW-SLAP scale, it raises the intriguing question what we actually measure with our instruments, and why even a fully corrected measurement can be so far off. Our result has consequences for issues like the transfer of δ 18O from and to the VPDB scale, various fractionation factors, and the Δ 17O. The absolute 18O abundance for SLAP was determined at 1.88798 (43) x 10 -3 based on the absolute 18O abundance of VSMOW and the presented δ 18O SLAP in this paper.
18 Jul 2023Submitted to Rapid Communications in Mass Spectrometry
18 Jul 2023Submission Checks Completed
18 Jul 2023Assigned to Editor
18 Jul 2023Review(s) Completed, Editorial Evaluation Pending
18 Jul 2023Reviewer(s) Assigned
19 Aug 2023Editorial Decision: Revise Major
16 Oct 20231st Revision Received
16 Oct 2023Submission Checks Completed
16 Oct 2023Assigned to Editor
16 Oct 2023Review(s) Completed, Editorial Evaluation Pending
22 Oct 2023Reviewer(s) Assigned
16 Nov 2023Editorial Decision: Accept