氧化还原敏感元素(Se,Cr,Mo)稳定同位素

由于同位素分析方法的改进及表面热离子质谱(TIMS)和多接收电感耦合等离子体质谱(MC-ICP-MS)的应用,近年来氧化还原敏感元素(Se、Cr、Mo)同位素地球化学得以快速发展,成为国际地学领域的一个前沿。Se同位素在自然界中的变化最大,δ82/76SeNIST为-12.77‰～3.04‰;Cr和Mo同位素变化较小,δ53/52CrNIST值为-0.07‰～0.37‰,δ97/95MoJMC值为-0.27‰～2.65‰。自然界中各种无机过程(氧化还原)和生物有机过程均能使Se、Cr、Mo产生同位素分馏。因此,这些氧化还原敏感元素同位素可以示踪环境污染源、矿床流体来源;解释古海洋与现代海洋中元素的自身循环,从而示踪古氧化还原环境的演化;解释地外撞击事件及宇宙行星演化;甚至在生物学等领域研究中取得了显著成效。虽然还存在一些问题但它们将可能成为地球科学中有巨大应用前景的一种新兴的地球化学工具。

Stable isotope of redox-sensitive elements (Se,Cr,Mo)

In recent years,the redox-sensitive elements(Se,Cr,Mo)isotope geochemistry has made great progress due to the improvement of analytical methods and the development of TIMS and MC-ICP-MS,which have provided a new frontier in Earth sciences.Se isotopes show the larger δ82/76SeNIST variations in nature from-12.77‰-3.04‰,whereas the variations of Cr,Mo isotopes are relatively smaller with δ53/52CrNIST values of-0.07‰-0.37‰ and δ97/95MoJMC values of-0.27‰-2.65‰.Se,Cr and Mo occur in rocks,minerals,hydrothermal fluids,and biological materials,where they may be transported and transformed via different chemical and physical pathways.Most studies suggest that Se,Cr and Mo isotopes can be readily fractionated during both abiotic chemical redox processes,and biological processes.The isotopic variations for these metals have been successfully applied to explain contamination sources in the environment,the evolution of ore fluids in mineral deposits,metals cycling in both modern and paleo-ocean,cosmochemistry,etc.These non-traditional stable isotopes are becoming powerful tracers in the Earth sciences.