Boron isotopes in marine carbonates are increasingly used to reconstruct seawater pH and atmospheric pCO₂ through Earth’s history. While isotope ratio measurements from individual laboratories are often of high quality, it is important that records generated in different laboratories can equally be compared. Within this Boron Isotope Intercomparison Project (BIIP), we characterised the boron isotopic composition (commonly expressed in δ¹¹B) of two marine carbonates: Geological Survey of Japan carbonate reference materials JCp‐1 (coral Porites) and JCt‐1 (giant clam Tridacna gigas). Our study has three foci: (a) to assess the extent to which oxidative pre‐treatment, aimed at removing organic material from carbonate, can influence the resulting δ¹¹B; (b) to determine to what degree the chosen analytical approach may affect the resultant δ¹¹B; and (c) to provide well‐constrained consensus δ¹¹B values for JCp‐1 and JCt‐1. The resultant robust mean and associated robust standard deviation (s*) for un‐oxidised JCp‐1 is 24.36 ± 0.45‰ (2s*), compared with 24.25 ± 0.22‰ (2s*) for the same oxidised material. For un‐oxidised JCt‐1, respective compositions are 16.39 ± 0.60‰ (2s*; un‐oxidised) and 16.24 ± 0.38‰ (2s*; oxidised). The consistency between laboratories is generally better if carbonate powders were oxidatively cleaned prior to purification and measurement.

中文翻译：

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溶液中基于硼同位素的海洋碳酸盐分析的亚珀米尔实验室间一致性

海洋碳酸盐中的硼同位素越来越多地用于通过地球的历史来重建海水的pH值和大气中的pCO ₂。尽管各个实验室的同位素比测量通常是高质量的，但重要的是，可以将不同实验室中产生的记录进行同等比较。在该硼同位素比较计划（BIIP），我们表征了硼同位素组成（δ通常表示¹¹两种海洋碳酸盐B）：日本碳酸参考资料地质调查JCP-1（珊瑚滨）和JCT-1（巨蛤藜）。我们的研究中有三个焦点：（a）评估，其氧化预处理的程度，目的是从碳酸盐去除有机材料，可以影响δ所得的¹¹ B; （b）确定在何种程度上选择的分析方法可以影响所得到的δ ¹¹ B; 和（c），以提供良好约束共识δ ^11个B值为JCP-1和JCT-1。未氧化的JCp-1的最终鲁棒平均值和相关的鲁棒标准偏差（s *）为24.36±0.45‰（2 s *），而同一氧化材料为24.25±0.22‰（2 s *）。对于未氧化的JCt-1，各自的成分为16.39±0.60‰（2 s * ;未氧化）和16.24±0.38‰（2 s *; 氧化）。如果将碳酸盐粉末在纯化和测量之前进行氧化清洁，则实验室之间的一致性通常会更好。