Oxygen isotope exchange between dissolved phosphate and water at temperatures ≤135°C; inorganic versus biological fractionations

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doi: 10.1016/S0016-7037(99)00096-4
Authors:Lécuyer, Christophe; Grandjean, Patricia; Sheppard, Simon M. F.
Author Affiliations:Primary:
Ecole Normale Superieure de Lyon, Laboratoire de Sciences de la Terre, Lyons, France
Volume Title:Geochimica et Cosmochimica Acta
Source:Geochimica et Cosmochimica Acta, 63(6), p.855-862. Publisher: Pergamon, Oxford, International. ISSN: 0016-7037
Publication Date:1999
Note:In English. 37 refs.; illus., incl. 2 tables
Summary:The first experimental results are presented for the kinetic and equilibrium dissolved inorganic phosphate-H2O fractionation factor as a function of T. O isotope fractionations were measured between orthophosphate ions and water at 50-135°C. Biogenic apatites are systematically depleted in δ 18O by 80/00 at 20°C compared to dissolved phosphate. The activation energy is 134 kJ/mol and the kinetics of the homogeneous inorganic exchange reaction are slow at 10-13 to 10-11/sec when extrapolated to surface T. The results show that the isotopic composition of phosphates may be applied to identify the presence or absence of biogenic or microbial processes during the formation of phosphates. [R.K.H.]
Sections:Experimental mineralogy
Subjects:Apatite; Biogenic processes; Chemical fractionation; Experimental studies; Geochemical cycle; Geochemistry; Hydrology; Inorganic materials; Isotope fractionation; Isotope ratios; Isotopes; Kinetics; Laboratory studies; Nutrients; O-18/O-16; Oxygen; Phase equilibria; Phosphate ion; Phosphates; Rivers and streams; Solutes; Stable isotopes; Surface water; Temperature; Water
Abstract Numbers:00M/491
Record ID:1999046913
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United Kingdom, Twickenham, United Kingdom
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