地下水NH4+-15N同位素测试技术进展

摘要

本文根据铵离子的物理化学性质,建立了各种测试分析技术.传统的NH4+_-15N同位素测试过程包括样品中NH4+的收集、转化为适于质谱分析的气态N2以及用15N同位素质谱进行分析.其中NH:的收集方法较多,包括蒸馏法、扩散法、离子交换柱法和沸石萃取法等.适于质谱分析气态N2的转化方法可分为化学湿法和干燃烧法.笔者就同位素分析测试过程中NH4+的收集、转化及15N测试各个步骤加以总结,分析各自方法的优缺点和适用范围,寻求问题的解决途径.并评述了最近出现的色谱-质谱联合分析法和叠氮法.最后对地下水NH4+-15N同位素测试技术的发展进行了展望,以期能够更广泛地应用于环境和水文地质领域.%Various analytical techniques have been built based on physical and chemical properties of ammonium ion.The conventional NH4+-15N Isotopic analytical technique include the processes of NH4+-15N collection,transforming NH4+ to N2 and analyzing with 15N isotope mass spectrometric.The methods of NH4+ collection are various including distillation,diffusion,ion exchange column method,zeolite extraction and so on.The methods of transformation of gaseous N2 which are suitable for mass spectrometry analysis include chemical wet and dry combustion.The methods of ammonium collection,transformation,and the test of 15N were summarized in this article.The advantage,disadvantages and applicable ranges of each method were also introduced.The latest methods of chrom-mass spectrometry and azide were discussed.Finally,in order to make more widespread applications in the field of environment and hydrogeology,the development of testing techniques of NH4+-15N isotopes in the groundwater was prospected.