低温环境下Zn同位素分馏的若干重要过程

Some important processes of Zn isotope fractionation in low temperature environments

锌同位素是一种新的地球化学示踪剂,详细了解锌同位素分馏过程与机理是运用其解决科学问题的关键。本文对前人研究的吸附、沉淀、扩散、还原、生物过程中的锌同位素分馏研究结果进行了系统总结。在沉淀过程中,沉淀富集轻同位素;随着扩散距离增加,溶液Zn同位素组成变轻;还原生成的金属Zn富集轻同位素;在生物参与的Zn地球化学循环过程中,硅藻表面吸附重同位素,但生物本身优先利用轻同位素。

Zn isotopes is a new geochemical tracer, and a prerequisite for using them to constrain some important geochemical processes lies in the adequate understanding of the processes and mechanism of Zn isotope fractionation. This paper presents a review of current understanding of mass fractionation processes in low temperature environments, which include adsorption, precipitation, diffusion, reduction and biological processes. During the process of carbonate Precipitation, the precipitates are depleted in heavy Zn isotopes; the mass fractionation increases with the increasing of diffusion distance; metallic Zn reduced from Zn（Ⅱ）aq is enriched in light Zn isotopes; during biologically related processes, the heavier Zn isotopes are preferentially adsorbed on the surface of diatoms, whereas lighter Zn isotopes are preferentially utilized for biological metabolism.