中文摘要：

铁是生物必需的营养元素,并且生物圈与岩石圈、水圈、大气圈密切联系。因此,了解生物过程的铁同位素地球化学行为,对于示踪铁元素在生物圈内部体系的迁移和循环,以及运用铁同位素示踪生物圈和岩石圈、水圈之间的相互作用都具有重要意义。本文对不同生物体的铁同位素组成特征以及不同生物过程的铁同位素地球化学行为进行了总结。结果表明,生物倾向于优先吸收铁的轻同位素,而且在食物链中随着级别的升高,这种情况越明显。生物诱发过程（包括异化铁还原作用和细菌氧化作用）中,铁只是提供或接受电子,并没有真正进入生物细胞体内,这些过程所产生的铁同位素分馏值和无生物参与氧化还原过程产生的铁同位素分馏值相同。生物（包括微生物、植物、动物和人）吸收过程中,铁进入生物体细胞内,这些过程的铁同位素分馏主要受氧化还原作用所控制。铁同位素在生物学、医学等领域具有很大的应用潜力,有可能会成为这些领域新的示踪工具。

英文摘要：

It is known that Fe is essential for life. Moreover, that the biosphere interacts with the lithosphere, hydrosphere and atmosphere, and biological action plays critical roles in the evolution of the Earth. Therefore, it is of significance to understand Fe isotope behavior during biological processes. In this paper, the authors sum- marize the Fe isotope compositions of various types of organism, and Fe isotope fractionation during biological activities. It is shown that organism takes up light isotopes preferentially, and the isotope fractionation occurs stepwise along the biological pathways. During the biologically induced processes （including Dissimilatory Iron Reduction and bacterial Fe oxidation）, Fe actually does not enter the cell. The values of Fe isotope fractionation of these processes are consistent with those for non-biological reduction-oxidation. During biologically controlled processes （including microorganism, plants, animals and human beings）, Fe does enter the cell. The Fe isotope fractionation during these processes is mainly controlled by the redox state of Fe. Fe isotopes have great potential applications in biology and medical science, and are likely to be a new tracer in these research fields.