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Experimental calibration and field investigation of the oxygen isotopic fractionation between biogenic aragonite and water
Author(s) -
White R. M. P.,
Dennis P. F.,
Atkinson T. C.
Publication year - 1999
Publication title -
rapid communications in mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.528
H-Index - 136
eISSN - 1097-0231
pISSN - 0951-4198
DOI - 10.1002/(sici)1097-0231(19990715)13:13<1242::aid-rcm627>3.0.co;2-f
Subject(s) - aragonite , fractionation , calcite , chemistry , equilibrium fractionation , isotopes of oxygen , carbonate , seawater , environmental chemistry , mineralogy , analytical chemistry (journal) , isotope fractionation , geology , oceanography , chromatography , nuclear chemistry , organic chemistry
Marine molluscs have long been recognised as potential records of palaeoclimate change using the patterns and differences in the stable isotopic composition of the carbonate shells. The aim of this study is to improve the robustness of this approach for aragonitic molluscs by completing the first experimental calibration of the fractionation between water and biogenic aragonite. Fractionation factors were calibrated by growing specimens of the freshwater mollusc Lymnaea peregra under controlled conditions of water temperature and isotopic composition. Fifteen populations of L. peregra were maintained at constant temperature and isotopic conditions for five months (at five different temperatures and using three different water compositions). Water samples and temperature measurements were taken regularly throughout the experiment. The temperature dependence of the fractionation factor, between 8 and 24 °C, is given by: 1000 ln α=16.74×(1000T −1 )−26.39 (T in Kelvin) and the relationship between temperature ( T ), δ 18 O carb and δ 18 O wat is given by: T =21.36−4.83×δ +° O carb −δ +° O wat( T is in °C, δ 18 O carb is with respect to Vienna Pee Dee Belemnite (PDB), the International Atomic Energy Agency (IAEA) replacement standard for PDB, and δ 18 O wat is with respect to Vienna standard mean ocean water (VSMOW)) The outcome of the controlled experiment is compared with previous studies on synthetic, and biogenic, calcite and aragonite from field and laboratory investigations. These comparisons suggest that although a vital offset exists between the fractionation of isotopes in synthetic and biogenic aragonite for molluscs in general, there is no vital effect that is specific either to freshwater, or to individual, genera. Therefore, the calibrated relationship may be used for any freshwater or marine mollusc to derive palaeotemperatures providing the isotopic composition of the environmental water can be reliably constrained. Copyright © 1999 John Wiley & Sons, Ltd.