CAREER: Quantifying the Isotopic Signature of Nitrogen Oxides Emissions Sources

这个项目的重点是更好地了解向大气排放氮氧化物的来源。样本将从几个主要来源收集，如车辆、生物质燃烧和土壤产生的排放物。将在每个样品中测量同位素氮（15N）的分数。这将启用指纹？为每一种重要的大气源开发。能够确定氮氧化物的主要来源对大气的贡献，对于解决环境问题具有广泛的意义，例如烟雾和酸雨的形成，以及与减少来源战略相关的空气质量建模和决策制定。这项研究将与多方面的教育计划相结合，以增加少数民族对科学研究的参与。已经开发出一种新的方法，可以测量氮氧化物（NOx），而无需在收集时对样品进行分馏。该方法使用含有KMnO4的NaOH溶液，KMnO4在气相中与NO和NO2反应，在溶液中产生硝酸盐。该方法已在PI中进行了测试？通过对标准品和样品的反复测量，发现该方法具有良好的可重复性。通过将该技术与确定NOx同位素15N分数的方法相结合，正在开发一种可现场部署的系统。由此产生的氮氧化物来源特征将使从城市污染到生态系统氮肥的研究能够追踪氮氧化物的来源。

This project focuses on developing a better understanding of the sources of nitrogen oxide emissions to the atmosphere. Samples will be collected from several key sources such as vehicles, biomass burning, and emissions generated from soils. The fraction of isotopic nitrogen (15N) will be measured in each sample. This will enable ?fingerprints? to be developed for each of the important sources to the atmosphere. Being able to identify the contribution of major sources of nitrogen oxides to the atmosphere has broad implications for addressing environmental issues, such as the formation of smog and acid rain, and for air quality modeling and decision making associated with source reduction strategies. This research will be integrated with a multi-faceted education program to increase the participation of minorities in science research.A new method has been developed to enable the measurement of nitrogen oxides (NOx) without having the samples subject to fractionation upon collection. The method uses a solution of NaOH with KMnO4 that reacts with both NO and NO2 in the gas phase yielding nitrate in solution. The method has been tested in the PI?s laboratory and found to have a good level of reproducibility based upon repeated measures of standards and samples. A field deployable system is being developed by pairing this technique with a method to determine the fraction of isotopic 15N of the NOx. The resulting characterization of NOx sources will enable tracing the sources of NOx for studies ranging from urban pollution to nitrogen fertilization in ecosystems.