Combined oxygen and silicon isotope analysis of biogenic silica
Combined oxygen and silicon isotope analysis of biogenic silica
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DOI：
10.1002/jqs.1177
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发表时间：
2008-05-01
影响因子：
2.3
通讯作者：
Sloane, Hilary J.
中科院分区：
文献类型：
--
作者：
Leng, Melanie J.;Sloane, Hilary J.
利用生物硅氧和硅同位素比值来了解气候和环境过程的兴趣越来越大。几乎所有相当大量的文献都涉及氧或硅。这部分是因为氧同位素组成的测量是使用真空脱水，同位素交换或分步质谱技术完成的，而越来越多的研究人员正在转向多接收器电感耦合等离子体质谱（MC-ICP-MS）用于Si同位素分析，即使Si同位素分析可以使用用于氧同位素测量的质谱方法进行。在这里，我们描述了一个程序，同时测定同位素丰度的氧和硅从同一等分试样的生物硅。纯二氧化硅使用氟化技术分解成O和Si化合物，其中与五氟化溴（BrF 5）反应产生氧（O-2，随后转化为CO2）、四氟化硅（SiF 4）和其他氟副产物（例如BrF 3）。这些化合物使用冷阱低温分离。氧和硅的回收率对于生物硅是70-80%，取决于含水层的性质，对于纯石英是97-99%。氧同位素组成的重现性为ca。0.3 0.06-0.12份的硅。(c)自然环境研究理事会（NERC）版权所有2008年。经NERC许可转载。出版社：John Wiley & Sons，Ltd
There is increasing interest in the use of biogenic silica O and Si isotope ratios to understand climate and environmental processes. Virtually all of the fairly substantial body of literature deals with either oxygen or silicon. This is partly because measurement of oxygen isotope composition is done using either vacuum dehydration, isotope exchange or stepped fluorination techniques, while increasingly researchers are turning to multicollector inductively coupled plasma mass spectrometry (MC-ICP-MS) for Si isotope analysis, even though Si isotope analysis can be done using fluorination methods used for the oxygen isotope measurements. Here we describe a procedure for simultaneous determination of isotopic abundances of oxygen and silicon from the same aliquot of biogenic silica. Pure silica is dissociated into O and Si compounds using a fluorination technique, in which reaction with bromine pentafluoride (BrF5) produces oxygen (O-2, subsequently converted to CO2), silicon tetrafluoride (SiF4) and other fluorine by-products (e.g. BrF3). These compounds are cryogenically separated using cold traps. Yields for oxygen and silicon recovery are 70-80% for biogenic silica depending on the nature of the hydrous layer and 97-99% for pure quartz. Reproducibility of the oxygen isotopic composition is ca. 0.3 parts per thousand and silicon between 0.06-0.12 parts per thousand. (c) Natural Environment Research Council (NERC) copyright 2008. Reproduced with the permission of NERC. Published by John Wiley & Sons, Ltd.