Interlaboratory comparison study of Mg/Ca and Sr/Ca measurements in planktonic foraminifera for paleoceanographic research

Yair Rosenthal, Suzanne Perron-Cashman, Caroline H. Lear, Edouard Bard, Stephen Barker, Katharina Billups, Martha Bryan, Margaret L. Delaney, Peter B. DeMenocal, Gary S. Dwyer, Henry Elderfield, Chris R. German, Mervyn Greaves, David W. Lea, Thomas M. Marchitto, Dorothy K. Pak, Georges L. Paradis, Ann D. Russell, Ralph R. Schneider, Kathleen ScheiderichLowell Stott, Kazuyo Tachikawa, Eric Tappa, Robert Thunell, Michael Wara, Syee Weldeab, Paul A. Wilson

Research output: Contribution to journalArticlepeer-review

144 Scopus citations

Abstract

Thirteen laboratories from the USA and Europe participated in an intercomparison study of Mg/Ca and Sr/Ca measurements in foraminifera. The study included five planktonic species from surface sediments from different geographical regions and water depths. Each of the laboratories followed their own cleaning and analytical procedures and had no specific information about the samples. Analysis of solutions of known Mg/Ca and Sr/Ca ratios showed that the intralaboratory instrumental precision is better than 0.5% for both Mg/Ca and Sr/Ca measurements, regardless whether ICP-OES or ICP-MS is used. The interlaboratory precision on the analysis of standard solutions was about 1.5% and 0.9% for Mg/Ca and Sr/Ca measurements, respectively. These are equivalent to Mg/Ca-based temperature repeatability and reproducibility on the analysis of solutions of ±0.2°C and ±0.5°C, respectively. The analysis of foraminifera suggests an interlaboratory variance of about ±8% (%RSD) for Mg/Ca measurements, which translates to reproducibility of about ±2-3°C. The relatively large range in the reproducibility of foraminiferal analysis is primarily due to relatively poor intralaboratory repeatability (about ±1-2°C) and a bias (about 1°C) due to the application of different cleaning methods by different laboratories. Improving the consistency of cleaning methods among laboratories will, therefore, likely lead to better reproducibility. Even more importantly, the results of this study highlight the need for standards calibration among laboratories as a first step toward improving interlaboratory compatibility.

Original languageEnglish (US)
Article numberQ04D09
JournalGeochemistry, Geophysics, Geosystems
Volume5
Issue number4
DOIs
StatePublished - Apr 2004

All Science Journal Classification (ASJC) codes

  • Geochemistry and Petrology
  • Geophysics

Keywords

  • Intercalibration
  • Mg/Ca thermometry
  • Paleoceanography

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