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Is Classical Acid-Alkali-Acid Treatment Responsible for Contamination? An Alternative Proposition

Published online by Cambridge University Press:  18 July 2016

Christine Hatté ,
Jean Morvan ,
Claude Noury  and
Martine Paterne
Christine Hatté
Affiliation:
Laboratoire des Sciences du Climat et de l'Environnement, UMR1572 CEA/CNRS, F-91198 Gif-sur-Yvette cedex, France. E-mail: hatte@lsce.cnrs-gif.fr.
Jean Morvan
Affiliation:
École Nationale Supérieure de Chimie de Rennes, Avenue du Général Leclerc, F-35700 Rennes, France
Claude Noury
Affiliation:
Laboratoire des Sciences du Climat et de l'Environnement, UMR1572 CEA/CNRS, F-91198 Gif-sur-Yvette cedex, France. E-mail: hatte@lsce.cnrs-gif.fr.
Martine Paterne
Affiliation:
Laboratoire des Sciences du Climat et de l'Environnement, UMR1572 CEA/CNRS, F-91198 Gif-sur-Yvette cedex, France. E-mail: hatte@lsce.cnrs-gif.fr.
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Abstract

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It is well known that, during the widely used AAA pretreatment (de Vries and Barendsen 1954), alkali treatment is responsible for the incorporation of modern carbon due to the precipitation of atmospheric CO2 as carbonate. Until now, the last step of the experiment, consisting in acid treatment (most of the time with hydrochloric acid) was considered to be sufficient to eliminate all of lab contamination. But wood, peat and sediment present a complex molecular structure. During radiocarbon chemical treatments, functional groups still present in the molecules are likely to form ionic bonds with “modern” carbonates. These new chemical bonds resist a “classical” acid treatment and are responsible for rejuvenation. This short paper presents preliminary results for two common 14C cases: rejuvenation of a 0.4 pMC wood and of an Oxygen Isotope Stage 3 (OIS3) paleosol. For both cases, contamination due to incorporation of modern carbon during chemical treatment is evaluated and an alternative protocol is proposed.

Type
I. Becoming Better
Information
Radiocarbon , Volume 43 , Issue 2A: Proceedings of the 17th International Radiocarbon Conference (Part 1 of 3) , 2001 , pp. 177 - 182
Copyright
Copyright © The Arizona Board of Regents on behalf of the University of Arizona 

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