Ed C. Hathorne, University of Bremen
Alex Gagnon, University of Washington
Thomas Felis, University of Bremen
Jess Adkins, California Institute of Technology
Ryuji Asami, University of the Ryukyus
Wim Boer, Royal Netherlands Institute for Sea Research
Nicolas Caillon, LSCE/IPSL
David Case, Washington University
Kim M. Cobb, Georgia Institute of Technology
Eric Douville, LSCE/IPSL
Peter deMenocal, Columbia University
Anton Eisenhauer, Geomar Helmholtz Centre For Ocean Research
Dieter Garbe-Schonberg, Christian-Albrechts University Kiel
Walter Geibert, University of Edinburgh
Steven Goldstein, Columbia University
Konrad Hughen, Woods Hole Oceanographic Institution
Mayuri Inoue, National Insitute for Environmental Studies, Japan
Hodaka Kawahata, University of Tokyo
Martin Kolling, University of Bremen
Florence L. Cornec, Ipsl/Upmc/Cnrs/Ird/Mnhn Centre IRD France Nord
Braddock K. Linsley, University at Albany-State University of New York
Helen V. McGregor, University of WollongongFollow
Paolo Montagna, Columbia University
Intan S. Nurhati, Georgia Institute of Technology
Terrence M. Quinn, University of Texas at Austin
Jacek Raddatz, Geomar Helmholtz Centre for Ocean Research
Helene Rebaubier, LSCE/IPSL
Laura Robinson, Woods Hole Oceanographic Institution
Aleksey Sadekov, University of Edinburgh
Robert Sherrell, Rutgers University
Dan Sinclair, Rutgers University
Alexander W. Tudhope, University of Edinburgh
Gangjian Wei, Chinese Academy of Sciences
Henri Wong, ANSTO
Henry C. Wu, University of Bremen
Chen-Feng You, National Cheng Kung University



Publication Details

Hathorne, E. C., Gagnon, A., Felis, T., Adkins, J., Asami, R., Boer, W., Caillon, N., Case, D., Cobb, K. M., Douville, E., deMenocal, P., Eisenhauer, A., Garbe-Schonberg, D., Geibert, W., Goldstein, S., Hughen, K., Inoue, M., Kawahata, H., Kolling, M., Cornec, F. L., Linsley, B. K., McGregor, H. V., Montagna, P., Nurhati, I. S., Quinn, T. M., Raddatz, J., Rebaubier, H., Robinson, L., Sadekov, A., Sherrell, R., Sinclair, D., Tudhope, A. W., Wei, G., Wong, H., Wu, H. C. & You, C. (2013). Interlaboratory study for coral Sr/Ca and other element/Ca ratio measurements. G3: Geochemistry, Geophysics, Geosystems: an electronic journal of the earth sciences, 14 (9), 3730-3750.


The Sr/Ca ratio of coral aragonite is used to reconstruct past sea surface temperature (SST). Twenty-one laboratories took part in an interlaboratory study of coral Sr/Ca measurements. Results show interlaboratory bias can be significant, and in the extreme case could result in a range in SST estimates of 7°C. However, most of the data fall within a narrower range and the Porites coral reference material JCp-1 is now characterized well enough to have a certified Sr/Ca value of 8.838 mmol/mol with an expanded uncertainty of 0.089 mmol/mol following International Association of Geoanalysts (IAG) guidelines. This uncertainty, at the 95% confidence level, equates to 1.5°C for SST estimates using Porites, so is approaching fitness for purpose. The comparable median within laboratory error is <0.5°C. This difference in uncertainties illustrates the interlaboratory bias component that should be reduced through the use of reference materials like the JCp-1. There are many potential sources contributing to biases in comparative methods but traces of Sr in Ca standards and uncertainties in reference solution composition can account for half of the combined uncertainty. Consensus values that fulfil the requirements to be certified values were also obtained for Mg/Ca in JCp-1 and for Sr/Ca and Mg/Ca ratios in the JCt-1 giant clam reference material. Reference values with variable fitness for purpose have also been obtained for Li/Ca, B/Ca, Ba/Ca, and U/Ca in both reference materials. In future, studies reporting coral element/Ca data should also report the average value obtained for a reference material such as the JCp-1.



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