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GEOCHEMISTRY GEOPHYSICS GEOSYSTEMS,
VOL. 7,
Q08009,
6 PP., 2006
doi:10.1029/2006GC001243 [Citation]
Determination of temperature-dependent stable strontium isotope (88Sr/86Sr) fractionation via bracketing standard MC-ICP-MS
Leibniz-Institut für Meereswissenschaften (IfM-GEOMAR), FB2 Biogeochemie, Wischhofstr. 1-3, Kiel, D-24148 Germany
Leibniz-Institut für Meereswissenschaften (IfM-GEOMAR), FB2 Biogeochemie, Wischhofstr. 1-3, Kiel, D-24148 Germany
Stable strontium isotopes (here 88Sr/86Sr) are introduced as a new member of the nontraditional stable isotopes. We have developed a bracketing standard method for the determination of δ88/86Sr using an AXIOM MC-ICP-MS and normalizing to strontium SRM NBS987. For individual measurements the external reproducibility is better than about 25 ppm (1σ RSD). For the IAPSO seawater standard a δ88/86Sr value of 0. 381 ± 0.010‰ (2SEM) was determined. For the first time a temperature-dependent strontium isotope fractionation during calcium carbonate precipitation could be shown. Aragonite samples inorganically precipitated under temperature control between 10 and 50°C revealed a δ88/86Sr/temperature dependency of 0.0054(5)‰/°C (R2 = 0.987). In contrast, for natural coral samples (Pavona clavus) from a proxy calibration study (23 to 27°C) we did determine 0.033(5)‰/°C (R2 = 0.955). The processes causing this sixfold stronger temperature dependency for the natural coral samples have to be studied in more detail in future studies. In a first approach the different slopes can be interpreted as effects of kinetic fractionation of strontium ions with or without a hydrate shell of 22 to 29 water molecules.
Received 13 January 2006; accepted 16 May 2006; published 16 August 2006.
Citation: (2006), Determination of temperature-dependent stable strontium isotope (88Sr/86Sr) fractionation via bracketing standard MC-ICP-MS, Geochem. Geophys. Geosyst., 7, Q08009, doi:10.1029/2006GC001243.
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