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210Pb chronology and trace metal geochemistry at Los Tuxtlas, Mexico, as evidenced by a sedimentary record from the Lago Verde crater lake

210Pb chronology and trace metal geochemistry at Los Tuxtlas, Mexico, as evidenced by a... Vol. 25 (Suppl.) 2006 CHINESE JOURNAL GEOCHEMISTRY 17 larger value of 1.033 instead of 1.0194. Oi (2000, 2001) calculated a value of 1.0260 by using ab initio quantum chemistry calculations on gas-phase B(OH)3 and B(OH)4. Meanwhile, to explain these offsets, some other efforts also have been made on this issue, such as considering vital effects for different foraminifers or corals with different living microenvironments (e.g. Sanyal et al. 2001; Hrnisch et al. 2003, 2004; Zeebe et al. 2003). Many empirical curves were established for different samples. Hence, we feel that before flLrther application of this possible paleo-pH indicator, a careful recalculation of the basic K value is necessary. We use ab initio quantum chemistry calculations on the isotopic exchange reaction between B(OH)3 and B(OH)4. Several calculation methods have been carefully compared and evaluated. The "water-droplet" method is chosen to investigate this isotope exchange reaction using cluster models with up to 34 water molecules surrounding the solute. HF/6-31G* level calculations coupled with a 0.920 scaling factor are used for the frequency calculations. A larger K value (1.027) is obtained from this study compared to the commonly used 1.0194. The new theoretical curve ofpH vs. delta liB composition of B(OH)4 using http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Chinese Journal of Geochemistry Springer Journals

210Pb chronology and trace metal geochemistry at Los Tuxtlas, Mexico, as evidenced by a sedimentary record from the Lago Verde crater lake

210Pb chronology and trace metal geochemistry at Los Tuxtlas, Mexico, as evidenced by a sedimentary record from the Lago Verde crater lake

Abstract

Vol. 25 (Suppl.) 2006 CHINESE JOURNAL GEOCHEMISTRY 17 larger value of 1.033 instead of 1.0194. Oi (2000, 2001) calculated a value of 1.0260 by using ab initio quantum chemistry calculations on gas-phase B(OH)3 and B(OH)4. Meanwhile, to explain these offsets, some other efforts also have been made on this issue, such as considering vital effects for different foraminifers or corals with different living microenvironments (e.g. Sanyal et al. 2001; Hrnisch et al. 2003, 2004; Zeebe et al. 2003)....
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Publisher
Springer Journals
Copyright
Copyright © 2006 by Institute of Geochemistry, Chinese Academy of Sciences
Subject
Geosciences; Geochemistry
ISSN
1000-9426
eISSN
1993-0364
DOI
10.1007/BF02839765
Publisher site
See Article on Publisher Site

Abstract

Vol. 25 (Suppl.) 2006 CHINESE JOURNAL GEOCHEMISTRY 17 larger value of 1.033 instead of 1.0194. Oi (2000, 2001) calculated a value of 1.0260 by using ab initio quantum chemistry calculations on gas-phase B(OH)3 and B(OH)4. Meanwhile, to explain these offsets, some other efforts also have been made on this issue, such as considering vital effects for different foraminifers or corals with different living microenvironments (e.g. Sanyal et al. 2001; Hrnisch et al. 2003, 2004; Zeebe et al. 2003). Many empirical curves were established for different samples. Hence, we feel that before flLrther application of this possible paleo-pH indicator, a careful recalculation of the basic K value is necessary. We use ab initio quantum chemistry calculations on the isotopic exchange reaction between B(OH)3 and B(OH)4. Several calculation methods have been carefully compared and evaluated. The "water-droplet" method is chosen to investigate this isotope exchange reaction using cluster models with up to 34 water molecules surrounding the solute. HF/6-31G* level calculations coupled with a 0.920 scaling factor are used for the frequency calculations. A larger K value (1.027) is obtained from this study compared to the commonly used 1.0194. The new theoretical curve ofpH vs. delta liB composition of B(OH)4 using

Journal

Chinese Journal of GeochemistrySpringer Journals

Published: Feb 16, 2008

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