Abstract A combination of theoretical predictions and isotopic equilibration experiments using the three-isotope method have been performed to assess Si isotope fractionation among minerals, and aqueous species in the presence of dissolved catechol. Aqueous Si in abiotic ambient temperature aqueous solutions is dominated by the IV-coordinated H4SiO 4 0 species, but the presence of aqueous catechol provokes the formation of a VI-fold Si-catechol complex. Results show an equilibrium Si fractionation factor of ∼19‰ between the VI-fold coordinated Si-catechol complex and the IV-fold coordinated aqueous silicic acid, an amplitude never previously observed for silicon. The fractionation between V-fold Si-organo complexes (with diolate, glyconate or methyllactate groups) and silicic acid has also been estimated through theoretical predictions to be about −10‰. These extreme fractionations can be used to improve our ability to interpret the Si isotope compositions of natural solids, and in particular those associated with marine silica biomineralization processes (e.g. sponge spicules).

中文翻译：

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由于 Si 有机络合导致的极端硅同位素分馏：对二氧化硅生物矿化的影响

摘要 理论预测和使用三同位素方法的同位素平衡实验相结合，已用于评估在溶解的邻苯二酚存在下矿物和含水物质之间的 Si 同位素分馏。非生物环境温度水溶液中的水性 Si 主要是 IV 配位的 H4SiO 4 0 物种，但水性邻苯二酚的存在会引发 VI 倍 Si-邻苯二酚复合物的形成。结果表明，VI 倍配位的 Si-邻苯二酚配合物和 IV 倍配位的硅酸水溶液之间的平衡 Si 分馏因子约为 19‰，这是硅之前从未观察到的振幅。V-fold Si-有机配合物之间的分馏（与二醇，乙醇酸或乳酸甲酯基团）和硅酸也已通过理论预测估计为约 -10‰。这些极端的分馏可用于提高我们解释天然固体的 Si 同位素组成的能力，特别是与海洋二氧化硅生物矿化过程（例如海绵针状体）相关的那些。