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| Titel |
Boron isotope fractionation during brucite deposition from artificial seawater |
| VerfasserIn |
J. Xiao, Y. K. Xiao, C. Q. Liu, Z. D. Jin |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1814-9324
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| Digitales Dokument |
URL |
| Erschienen |
In: Climate of the Past ; 7, no. 3 ; Nr. 7, no. 3 (2011-07-06), S.693-706 |
| Datensatznummer |
250004605
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| Publikation (Nr.) |
 copernicus.org/cp-7-693-2011.pdf |
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| Zusammenfassung |
| Experiments involving boron incorporation into brucite (Mg(OH)2) from
magnesium-free artificial seawater with pH values ranging from 9.5 to 13.0
were carried out to better understand the incorporation behavior of boron
into brucite and the influence of it on Mg/Ca-SST proxy and δ11B-pH proxy.
The results show that both the concentration of boron in
deposited brucite ([B]d) and its boron partition coefficient
(Kd) between deposited brucite and final seawater are controlled by the pH
of the solution. The incorporation capacity of boron into brucite is almost
the same as that into corals, but much stronger than that into oxides and
clay minerals. The isotopic compositions of boron in deposited brucite
(δ11Bd) are higher than those in the associated artificial seawater
(δ11Bisw) with fractionation factors ranging between 1.0177 and
1.0569, resulting from the preferential incorporation of B(OH)3 into
brucite. Both boron adsorptions onto brucite and the precipitation reaction of
H3BO3 with brucite exist during deposition of brucite from
artificial seawater. The simultaneous occurrence of both processes
determines the boron concentration and isotopic fractionation of brucite.
The isotopic fractionation behaviors and mechanisms of boron incorporated
into brucite are different from those into corals. The existence of brucite
in corals can affect the δ11B and Mg/Ca in corals and influences the
Mg/Ca-SST proxy and δ11B-pH proxy negatively. The
relationship between δ11B and Mg/Ca in corals can be used to
judge the existence of brucite in corals, which should provide a reliable
method for better use of δ11B and Mg/Ca in corals to
reconstruct paleo-marine environment. |
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