Boron incorporation in the foraminifer Amphistegina lessonii under a decoupled carbonate chemistry
Boron incorporation in the foraminifer Amphistegina lessonii under a decoupled carbonate chemistry
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DOI：
10.5194/bg-12-1753-2015
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发表时间：
2014-12
期刊：
影响因子：
4.9
通讯作者：
K. Kaczmarek;G. Langer;G. Nehrke;I. Horn;S. Misra;M. Janse;J. Bijma
中科院分区：
文献类型：
--
作者：
K. Kaczmarek;G. Langer;G. Nehrke;I. Horn;S. Misra;M. Janse;J. Bijma
抽象。一些研究表明，生物碳酸盐（主要是有孔虫）的硼同位素组成（δ 11 B）和B / Ca比值可以作为海洋碳酸盐化学的两个参数的替代物，从而有可能计算整个碳酸盐系统。然而，B纳入海洋碳酸盐岩的机制仍然没有完全理解和现场样品的分析表明，物种特异性和水文影响的B代理复杂的应用。由于pH、CO 32-和B（OH）4-的共同变化，识别影响硼掺入的碳酸盐体系参数是困难的。为了阐明碳酸盐系统的参数与硼掺入有关的问题，我们进行了底栖共生有孔虫Amphistegina lessonii使用解耦的pH-CO 32-化学培养实验。用发射光谱和激光烧蚀MC-ICP-MS技术同时测定了δ 11 B和B / Ca比值。结果表明，硼同位素组成随培养液pH值的增加而增加，B / Ca随培养液B（OH）4- /HCO 3-的增加而增加。后者表明，A. lessonii的特点是B（OH）4-与HCO 3-竞争。此外，在单个样本上同时测定B / Ca和δ 11 B允许评估这些参数的相对变异性。在不同处理间，B / Ca随硼浓度的增加而变化，而同位素分布的变化是恒定的。
Abstract. A number of studies have shown that the boron isotopic composition (δ11B) and the B / Ca ratio of biogenic carbonates (mostly foraminifers) can serve as proxies for two parameters of the ocean's carbonate chemistry, rendering it possible to calculate the entire carbonate system. However, the B incorporation mechanism into marine carbonates is still not fully understood and analyses of field samples show species-specific and hydrographic effects on the B proxies complicating their application. Identifying the carbonate system parameter influencing boron incorporation is difficult due to the co-variation of pH, CO32- and B(OH)4-. To shed light on the question which parameter of the carbonate system is related to the boron incorporation, we performed culture experiments with the benthic symbiont-bearing foraminifer Amphistegina lessonii using a decoupled pH–CO32- chemistry. The determination of the δ11B and B / Ca ratios was performed simultaneously by means of a new in situ technique combining optical emission spectroscopy and laser ablation MC-ICP-MS. The boron isotopic composition in the tests gets heavier with increasing pH and B / Ca increases with increasing B(OH)4- / HCO3- of the culture media. The latter indicates that boron uptake of A. lessonii features a competition between B(OH)4- and HCO3-. Furthermore, the simultaneous determination of B / Ca and δ11B on single specimens allows for assessing the relative variability of these parameters. Among different treatments the B / Ca shows an increasing variability with increasing boron concentration in the test whereas the variability in the isotope distribution is constant.