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Nitrogen and oxygen isotope-ratio analysis of nitrate by the denitrifier method using continuous flow isotope-ratio mass spectrometry.

机译：使用连续流同位素比质谱法，通过反硝化方法分析硝酸盐的氮，氧同位素比。

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摘要

The total isotopic composition of nitrate is used for identifying the origin and fate of nitrate in atmospheric, terrestrial and aquatic systems. The analysis of delta18O and delta15N values each give important and unique information about the sources and sinks of nitrate in these systems. This denitrifier method is based on the isotope ratio analysis of nitrous oxide generated through reduction of nitrate by cultured denitrifying bacteria. Here, preliminary data is presented on delta 15N and delta18O generated by the bacterial production of N2O from NO3-.;During the process of denitrification, nitrates are converted to nitrogen gas via a series of intermediate gaseous nitrogen oxide compounds. Denitrification occurs due to the presence of heterotrophic bacteria or autotrophic denitrifier pathways in select bacteria. Thus, we have chosen a distinct bacterium for the investigation of nitrate reduction for this study. Pseudomonas aureofaciens contains the copper-containing nitrite reductase necessary for the reduction of nitrate. Our efforts focus on the conversion of NO 3 to N2O using techniques adapted from Cascotti22 . In this study, a customized headspace extraction system was built in order to analyze delta18O and delta15N of N2O from NO3-. Successful purification of Pseudomonas aureofaciens, conversion of NO3 - to N2O, and the standardization of nitrate was the result of many experiments. Tests of the impact on isotopic composition by pre-concentration methods have been performed including freeze-drying/evaporation and ion chromatography. The denitrifier method has been implemented in the Michalski Stable Isotope Lab in order to simultaneously detect the stable isotope composition of oxygen and nitrogen in nitrate samples.
机译：硝酸盐的总同位素组成用于确定大气，陆地和水生系统中硝酸盐的来源和命运。对delta18O和delta15N值的分析各自提供了有关这些系统中硝酸盐的来源和吸收的重要且独特的信息。该反硝化方法基于通过培养的反硝化细菌还原硝酸盐而产生的一氧化二氮的同位素比分析。在此，提供了有关由细菌从NO3-生成N2O产生的δ15N和δ18O的初步数据。在反硝化过程中，硝酸盐通过一系列中间气态氮氧化物转化为氮气。由于选择细菌中存在异养细菌或自养反硝化途径，因此会发生反硝化作用。因此，我们选择了一种独特的细菌进行本研究的硝酸盐还原研究。金黄色假单胞菌含有还原硝酸盐所必需的含铜亚硝酸盐还原酶。我们的工作重点是使用Cascotti22改编的技术将NO 3转化为N2O。在这项研究中，建立了定制的顶空萃取系统，以分析NO3-中N2O的delta18O和delta15N。许多实验的结果是成功纯化了金黄色假单胞菌，将NO3-转化为N2O，并将硝酸盐标准化。已经通过预浓缩方法对同位素组成的影响进行了测试，包括冷冻干燥/蒸发和离子色谱法。为了同时检测硝酸盐样品中氧和氮的稳定同位素组成，已在Michalski稳定同位素实验室中实施了反硝化方法。

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  • 作者

    Crawley, Lindsey R.;

  • 作者单位

    Purdue University.;

  • 授予单位 Purdue University.;
  • 学科 Chemistry Analytical.
  • 学位 M.S.
  • 年度 2010
  • 页码 107 p.
  • 总页数 107
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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