硝酸盐氮氧同位素在不同生态系统中的研究进展

硝酸盐作为氮循环中的重要物质之一，已成为地下水污染的主要形式。硝酸盐的来源分为自然源和人为源。不同来源的硝酸盐具有不同的同位素特征，因此可以利用N、O同位素来识别硝酸盐的来源、迁移和转化。本文通过综述硝酸盐的主要来源及其同位素特征，简要介绍了硝酸盐同位素检测技术的发展历程，影响同位素分馏的相关作用过程；同时简述了硝酸盐同位素在农业、沙漠、森林、城市生态系统中开展的相关研究，概述了研究中存在的问题，并展望了今后的发展方向。

An overview on application of dual isotope compositions of nitrate in different ecosystems

Nitrate，as one of the significant compositions of the nitrogen cycling，has become the main contamination of groundwater. The sources of nitrate include natural and anthropogenic sources. Different sources of nitrate have the different isotopic characteristics，hence the dual isotopic compositions of nitrate can be used to differentiate the sources of nitrate，and trace the migration and transformation processes. The paper reviews the main sources of nitrate and their characteristics. And with the analytical advances，the isotope techniques of δ¹⁵N-NO₃^-，δ¹⁸O-NO₃^- are adopted in different ecosystems over the world，for instance in agriculture，desert，forest，and megacities. However，complex fractionation processes and admixture of multiple sources of nitrate always make it difficult to identify the sources，which can be minimized or eliminated by multi-isotope and multi-tracer with the developed analysis methods and models.