Mg coordination in biogenic carbonates constrained by theoretical and experimental XANES
Mg coordination in biogenic carbonates constrained by theoretical and experimental XANES
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DOI：
10.1016/j.epsl.2015.03.048
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发表时间：
2015-07-01
影响因子：
5.3
通讯作者：
Kawahata, Hodaka
中科院分区：
文献类型：
--
作者：
Yoshimura, Toshihiro;Tamenori, Yusuke;Kawahata, Hodaka
生物碳酸钙中镁的掺入被广泛用于推断矿物生长的条件。然而，从矿物学的角度来看，镁的主导化学环境以及镁是否以理想的替代方式取代生物碳酸钙中的钙仍存在争议。在这里，我们表明，在实验和理论XANES光谱的能量位置和共振功能，可以用来确定占主导地位的分子主机网站。在所有的生物方解石，这是由有孔虫，珊瑚，双壳类，腕足类，镁的本地环境表明，它主要是作为钙的晶格中的结构替代品，但在文石珊瑚和双壳类的有机部分或无序相的显着效果进行了观察。碳酸钙多晶型体之间的这些差异表明，物理化学参数影响生物方解石的最终组成，但在文石分泌生物体，可能有生理控制镁浓度生物文石。(C)2015 Elsevier B.V.版权所有。
Incorporation of magnesium into biogenic calcium carbonate is widely used to infer the conditions of mineral growth. From a mineralogical perspective, the dominant chemical environment of Mg and whether Mg replaces calcium by ideal substitution in biogenic CaCO3 are still debated, however. Here we show that energy positions and resonance features in experimental and theoretical XANES spectra can be used to identify the dominant molecular host site. In all biogenic calcite, which is produced by foraminifera, corals, bivalves, and brachiopods, the local environment of Mg indicated that it is incorporated primarily as a structural substitute for calcium in the crystal lattice, but in aragonitic coral and bivalves a pronounced effect of the organic fraction or disordered phases was observed. These differences among CaCO3 polymorphs suggest that physicochemical parameters affect the final composition of biogenic calcite, but in aragonite-secreting organisms, there may be physiological controls on Mg concentrations in biogenic aragonite. (C) 2015 Elsevier B.V. All rights reserved.