Factors affecting B/Ca ratios in synthetic aragonite
Factors affecting B/Ca ratios in synthetic aragonite
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DOI：
10.1016/j.chemgeo.2016.05.007
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发表时间：
2016-10-25
期刊：
影响因子：
3.9
通讯作者：
McCulloch, M.
中科院分区：
文献类型：
--
作者：
Holcomb, M.;DeCarlo, T. M.;McCulloch, M.
有人建议测量海洋碳酸盐中的 B/Ca 比率来记录海水碳酸盐化学，但是基于无机分配的此类替代物的实验校准仍然有限。在这里，我们进行了一系列合成文石沉淀实验，以评估影响文石和海水之间 B/Ca 分配的因素。我们的结果表明，合成文石的 B/Ca 比率主要取决于文石沉淀的溶液中硼酸根和碳酸根离子的相对浓度；不像之前建议的那样取决于碳酸氢盐浓度。在研究范围内（20-40 摄氏度），温度的影响并不显着，但是，分配可能会受到饱和状态（和/或生长速率）的影响。根据我们的实验结果，我们建议文石 B/Ca 比率可以用作 [CO32-] 的代表。硼同位素组成 (delta B-11) 是一种既定的 pH 代理，因此 B/Ca 和 delta B-11 一起可以计算文石沉淀的溶液的完整碳酸盐化学性质。就海洋生物的文石沉淀受海水化学影响而言，B/Ca 也可能在重建海水化学方面有用。还描述了基于 amberlite 树脂和有机缓冲液 TRIS 的简化硼纯化方案。 (C) 2016 Elsevier B.V. 保留所有权利。
Measurements of B/Ca ratios in marine carbonates have been suggested to record seawater carbonate chemistry, however experimental calibration of such proxies based on inorganic partitioning remains limited. Here we conducted a series of synthetic aragonite precipitation experiments to evaluate the factors influencing the partitioning of B/Ca between aragonite and seawater. Our results indicate that the B/Ca ratio of synthetic aragonites depends primarily on the relative concentrations of borate and carbonate ions in the solution from which the aragonite precipitates; not on bicarbonate concentration as has been previously suggested. The influence of temperature was not significant over the range investigated (20-40 degrees C), however, partitioning may be influenced by saturation state (and/or growth rate). Based on our experimental results, we suggest that aragonite B/Ca ratios can be utilized as a proxy of [CO32-]. Boron isotopic composition (delta B-11) is an established pH proxy, thus B/Ca and delta B-11 together allow the full carbonate chemistry of the solution from which the aragonite precipitated to be calculated. To the extent that aragonite precipitation by marine organisms is affected by seawater chemistry, B/Ca may also prove useful in reconstructing seawater chemistry. A simplified boron purification protocol based on amberlite resin and the organic buffer TRIS is also described. (C) 2016 Elsevier B.V. All rights reserved.