Cosmo and Geochemical studies of chlorine isotopes

氢和氧等稳定同位素已被用作宇宙和地球化学中的重要工具，并为解决各种地球化学问题作出了重大贡献。然而，由于难以进行精确的同位素分析，氯同位素很少用于这些目的。特别是，几乎没有关于陨石的同位素数据的报道。本项目的目的是建立高精度的行星物质(包括陨石)的氯同位素分析技术。第一年，成功地开发了C&lt；S2&gt；Cl2+离子分子物种的质谱学技术，并用试剂标准建立了^&lt；37&gt；Cl/^&lt；35&gt；Cl比值的0.1permil(‰)精度。我们对许多有机和无机氯化合物中的氯进行了分析，发现商品氯化合物的δ^&lt；37&gt；Cl_&lt；Smoc&gt；‰从-5到+3…变化很大更多的声音。第二年，对厌氧菌还原脱氯过程中的质量鉴别过程进行了研究，发现了依赖于S位的同位素鉴别。氯浓度用离子色谱法测定。对标准平均海洋氯(Smoc)和试剂标准(Cscl)进行重复分析，建立了标准平均海洋氯(Smoc)和试剂标准(Cscl)的比值；0.319790±60，定义为参考值(δ^&lt；37&gt；Cl_&lt；Smoc&gt；=0.00‰)，其中一种试剂(CsCl)作为实验室标准，其比例为δ^&lt；37&gt；Cl_&lt；Smoc&gt；=-2.56±0.21‰。氢氟酸浸取法已成功地从岩石样品中高效地提取氯(回收率为85-90%)。在过去的3年里，我们进行了陨石和地面标准的分析。结果为：JR-1的δ^&lt；37&gt；Cl_&lt；Smoc&gt；=-0.74±0.24(‰)；Allende球粒陨石的δ^&lt；37&gt；值得注意的是，包括两个球粒陨石在内的这些行星物质的同位素组成区域是明显可分辨的，尽管同位素数据区仍然是初步的。因此，我们建议该项目中建立的高精度技术现在适用于包括陨石在内的各种行星材料的分析。较少

Stable isotopes such as hydrogen and oxygen have been used as an important tool in Cosmic and geochemistry and have significantly contributed to the solution of a wide variety of geochemical problems. Chlorine isotopes, however, have rarely been used for these purposes due to difficulties in precise isotopic analyses. Particularly, almost no isotopic data have been reported for meteorites. The purpose of this project is to establish high precision analytical technique of chlorine isotopes for planetary materials (including meteorites) by a thermal ionization mass spectrometry.In the first year, the mass spectrometric technique using molecular species of C_<s2>Cl^+ ions have been developed successfully and the precision of 0.1 permil (‰) for ^<37>Cl/^<35>Cl ratio was established using reagent standard (CsCl). We have carried out analyses of chlorine in many organic and inorganic chloride compounds and found large variations of δ^<37>Cl_<SMOC> from -5 to +3 ‰ for commercial chloride comp … More ounds. In the second year, mass discrimination processes during reductive dechlorination of chlorinated ethenes by anaerobic bacteria have been investigated and found ssite-dependent isotopic discrimination. Chlorine concentrations were determined using an ion chromatography. Replicate analyses have been carried for standard mean ocean chloride (SMOC) and reagent standard (CsCl) and then established ^<37>Cl/^<35>Cl ratio ; 0.319790±60, which was defined as reference (δ^<37>Cl_<SMOC> = 0.00 ‰) and one of reagents (CsCl) was employed as laboratory standard with the ratio of δ^<37>Cl_<SMOC> = -2.56±0.21 ‰. The HF-leaching method has been successfully developed for efficient extraction of chlorine from rock samples (recovery : 85-90%).In the 3^<rd> year, we have carried out analyses of meteorites and terrestrial standards. The results are ; δ^<37>Cl_<SMOC> = -0.74±0.24 (‰) for JR-1 ; δ^<37>Cl_<SMOC> = -2.87±0.32 (‰) for Allende chondrite ; ^<37>Cl_<SMOC> = +0.47±0.52 (‰) for Allegan ordinary chondrites. It is remarkable that isotopic compositions area clearly resolvable among these planetary materials including two chondrites, although the isotopic data area still preliminary. We, therefore, suggest that the high precision technique established in this project is now applicable to analyses for a wide variety of planetary materials including meteorites. Less