锂同位素高精度测定进展、应用与发展趋势

Advances in Lithium Isotope Geochemistry Research

中文关键词:  锂同位素  进展  高精度

英文关键词:Lithium isotopes  Progress  High precision

中文摘要:

      锂(Li)有两个稳定同位素6Li和7Li,二者之间相对质量差较大,在自然界存在显著的同位素分馏,其同位素组成变化可为认识地球大气、海洋和上层地壳之间的过程和相互作用提供重要线索,因此Li同位素作为灵敏的地球化学示踪剂广泛应用于化学、地质、海洋、生物和医学等研究领域。其同位素组成的高精度测定是一切研究的基础,近年来,由于Li同位素测定技术突破性改进和创新,大大提高了同位素测定的精度,推动和扩展了锂同位素的应用领域。本文对Li同位素组成测定主流方法、主要应用领域和未来挑战进行综述。测试方法主要包括：热电离质谱法(TIMS)、电感耦合等离子体质谱法(ICP-MS)、多接收电感耦合等离子质谱法(MC-ICP-MS)、二次离子质谱法(SIMS)、激光剥蚀多接收电感耦合等离子体质谱法(LA-MC-ICP-MS)和离子探针(SIMS)。这些测试方法分别面临有不同的挑战：TIMS在分析过程中因蒸发引起的锂同位素分馏,MC-ICP-MS难以降低的质量歧视效应,而SIMS和LA-MC-ICP-MS分析过程中存在缺少标准样品和低含量样品精度有限及高含量样品重现性差等问题。同时对Li同位素在大陆风化、水环境、矿床学、碳酸盐pH计和行星科学领域应用进行介绍,最后对锂同位素测定中存在问题和未来发展方向进行了综述。固体样品原位和单矿物的锂同位素研究将是未来锂同位素应用发展方向。

英文摘要:

      Lithium (Li) has two stable isotopes, 6Li and 7Li, which exhibit large relative masses. As a result, there is notable isotopic fractionation in nature, and variations in isotopic composition provide important clues for understanding processes and interactions between Earth"s atmosphere, oceans, and upper crust. Lithium isotopes, as sensitive geochemical tracers, are widely applied in various research fields, including chemistry, geology, oceanography, biology, and medicine, and accurate measurement of their isotopic composition forms the foundation for all such studies. In recent years, significant advancements and innovations in lithium isotope measurement techniques have greatly improved measurement precision. In this review, we discuss the mainstream methods for determining lithium isotopic composition, their major application areas, and future challenges. The testing methods include thermal ionization mass spectrometry (TIMS), inductively coupled plasma mass spectrometry (ICP-MS), multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS), laser ablation multi-collector inductively coupled plasma mass spectrometry (LA-MC-ICP-MS) and secondary ion mass spectrometry (SIMS). Each of these methods faces its own challenges: TIMS encounters difficulties in avoiding lithium isotope fractionation during the analysis process, MC-ICP-MS struggles with minimizing mass discrimination effects, while SIMS and LA-MC-ICP-MS encounter issues such as the lack of standard samples, limited precision for low-abundance samples, and poor reproducibility for high-abundance samples. This review introduce the applications of lithium isotopes in various fields, including continental weathering, water environment, mineralogy, carbonate pH and planetary. Finally, this review provide an overview of the challenges and future directions in lithium isotope measurement. Future developments in lithium isotope applications will focus on studying the isotopic composition of solid samples in situ measurements, and single mineral studies.