地-气系统活性氮来源与转化的同位素示踪研究进展

Research progress on isotope tracing on the sources and transformations of reactive nitrogen in the earth-atmosphere system

工业革命以来,人为活动导致活性氮的产生快速持续增加,造成了地表氮富集,诱发了一系列生态环境问题。稳定同位素是示踪物质来源和环境过程机制的有效手段之一。地表环境中活性氮化合物的氮同位素值整合了不同来源氮的同位素值和转化过程中的同位素分馏效应。因此,氮同位素组成可用于示踪地表氮素来源和循环过程,进而服务于地表活性氮减排策略的制定和地表氮富集的生态环境效应的评估。本文总结了氮同位素在大气系统活性氮来源、植物氮利用以及森林生态系统氮过程示踪中的研究进展,并对如何更加系统和准确地理解地表各圈层内以及圈层间的氮循环进行了展望。

Since the Industrial Revolution,human activities have led to a rapid and sustained increase in reactive nitrogen production,resulting in nitrogen enrichment at the Earth’s surface and triggering many ecological and en-vironmental issues.Stable isotopes are effective tools for tracing the sources and mechanisms of environmental processes.The nitrogen isotope values in surface environments integrate the isotope signatures of different nitrogen sources and the isotope fractionation effects of transformation processes.The composition of nitrogen isotopes can thus be utilized to trace the sources and cycling of nitrogen at the surface,aiding the development of strategies to reduce reactive nitrogen emissions,and assess the ecological effects of nitrogen enrichment.We reviewed the research progress on nitrogen isotope in the sources of reactive nitrogen in atmospheric systems,plant nitrogen utili-zation,and tracking of nitrogen processes in forest ecosystems.We further discussed how to gain a more systematic and accurate understanding of nitrogen cycle within and between the various spheres of the surface environment.