稳定同位素质谱技术在生态系统氮素循环中的应用

自然界中,氮的放射性同位素半衰期短,因此15 N是唯一适用的天然示踪物。采用15 N稀释或者富集技术,通过检测不同形态15 N的丰度,能够较真实地了解陆地生态系统中氮素的固定、矿化、硝化和反硝化等过程。本工作简述了陆地生态系统中氮素循环的各个过程及15 N同位素分馏机制,简要介绍了稳定氮同位素的测定方法,系统论述了稳定氮同位素技术在生物固氮及土壤氮素转化过程中的研究现状,并在此基础上预测了该方法在国内氮素循环研究中的应用前景。

Application of Stable Isotope Mass Spectrometry in the Ecology of Nitrogen Cycle

In nature, radioactive isotope of nitrogen has a very short half-life, so ¹⁵N which is the only suitable natural tracer for ecological nitrogen cycle. Detecting the stable nitrogen isotope natural abundance or using the stable nitrogen isotope-labeled tracer, contributes to our understanding of nitrogen fixation, organic nitrogen mineralization, nitrification and denitrification processes in terrestrial ecosystems. In this paper, the nitrogen cycling processes in ecosystems and the related ¹⁵N isotopic fractionation during every processes were introduced. The theory and methods about the stable nitrogen isotope analysis and its application in the research of nitrogen cycling in recent years were reviewed. Finally, comprehensive summations of the problem existing in current research and in conjunction with the prospects of the future research on nitrogen cycling were proposed.