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硫酸氧的定量转换用于高精度的三重氧同位素分析

Yu Wei^1,2, Hao Yan^1,2, Yongbo Peng^1,2

¹International Center for Isotope Effects Research, School of Earth Sciences and Engineering, Nanjing University, Nanjing 210023, China.

Analytical chemistry

|November 25, 2024

概括

一种新的R-D-E方法实现了100%的硫酸氧转化,用于精确的三氧同位素分析 (Δ'¹⁷O). 这种方法提高了准确性,需要更少的样本,影响了地质和大气研究.

科学领域:

地质化学地质化学
同位素地球化学同位素地球化学
大气化学大气化学

背景情况:

硫酸盐中的三氧同位素组成 (Δ'¹⁷O) 提供了对地球硫循环和过去大气条件 (O₂,O₃,H₂O) 的见解.
现有的分析方法遭受不完整的氧气转换,导致分化和阻碍准确的Δ'¹⁷O VSMOW-SLAP尺度上的比较.

研究的目的:

开发一种新的分析方法,用于从硫酸盐到CO2的完全氧化转化,用于精确的三氧同位素测量.
建立一种可靠的方法,在VSMOW-SLAP尺度上同时确定硫酸盐Δ'¹⁷O和 δ¹⁸O.

主要方法:

介绍了R-D-E方法,利用高温石墨减少,CO排放和Pt催化CO2 - O2同位素交换.
实现了近100%的硫酸氧转化为CO2,克服了以前技术的局限性.
分析了国际和国内的硫酸盐参考材料.

主要成果:

R-D-E方法提供了改进的 Δ'¹⁷O 精度 (9 per meg),并且需要最小的样本 (4 μmol硫酸盐).
对参考材料 (NBS-127,IAEA-SO-5,IAEA-SO-6) 的测量使用VSMOW-SLAP尺度进行.
发表的硫酸盐 Δ'¹⁷O 数据来源于部分氧产率技术的数据,与R-D-E结果相比,可能被高估了10-200 per meg.

结论:

R-D-E 方法提供了对硫酸盐三氧同位素的更准确的确定,这对于理解地质和大气过程至关重要.
旧的方法中不完整的氧气转换导致 Δ'¹⁷O 值的显著偏差,需要重新校准和重新解释过去的数据.
这一进步对于古气候学和生物地球化学中的小 Δ'¹⁷O 值研究至关重要.

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