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Measurement of the Trends, Behaviors, and Emissions of Trace Gases in the Atmosphere, and its Application to the Analysis in Atmospheric Sciences.

大气中痕量气体的趋势、行为和排放的测量及其在大气科学分析中的应用。

基本信息

批准号：
13308028
负责人：
MAKIDE Yoshihiro
金额：
$ 27.37万
依托单位：
The University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (A)
财政年份：
2001
资助国家：
日本
起止时间：
2001 至 2003
项目状态：
已结题

项目摘要

Distribution and trend of atmospheric carbon tetrafluoride (CF4) concentration by its precise and accurate measurement adopting atmospheric stable Krypton(Kr) as an internal standard was mainly developed. While CF4 is the strongest global warming gas, the measurement of its atmospheric concentration reported so far contains much larger uncertainties than the annual increment or the distribution gradient due to the worse trapping efficiency or unstable collection factor during the preconcentration process prior to GC/MS analysis because of its close properties to the major components of the air. An efficient and reproducible preconcentration method was developed and combined with the newly adopted atmospheric Kr as an internal standard because of their close physical properties and similar behaviors during the preconcentration and the GC/MS measurement. Since Kr exists uniformly and constantly in the global atmosphere with no variation or trend, extraordinarily improvement of the precision of CF4 determination (from several per cents to less than one per cent) was attained by normalizing the CF4 peak with a Kr isotope peak in the GC/MS measurement. The sample volume necessary was also extremely reduced. The precise and accurate distributions and trends of CF4 in the troposphere and stratosphere were obtained from the samples newly collected and those stored in our laboratory for more than 20 years. During our attempt of the precise determination of trace gases in the atmosphere by using atmospheric Kr as the internal standard, we noticed that the atmospheric Kr concentration of 1.14±0.01 ppmv which had been quoted through half a century was different from the observation. The Kr concentration we obtained with three step concentration followed by precise GC/MS measurement was 1.099±0.004 ppmv, about 4% lower than the currently accepted value.

主要研究了以大气中稳定态氪（Kr）为内标，通过精密、准确的测量方法，研究大气中四氟化碳（CF 4）浓度的分布和变化趋势。虽然CF 4是最强的全球变暖气体，但由于其与空气中主要成分的性质接近，在GC/MS分析之前的预浓缩过程中，由于捕获效率较差或收集因子不稳定，迄今报道的其大气浓度测量包含比年增量或分布梯度更大的不确定性。建立了一种高效、重现性好的预富集方法，并将其与新采用的大气Kr作为内标物结合，因为它们在预富集和GC/MS测量过程中具有相似的物理性质和行为。由于Kr在全球大气中均匀稳定地存在，没有变化或趋势，通过在GC/MS测量中用Kr同位素峰归一化CF 4峰，实现了CF 4测定精度的显著提高（从几个百分点到小于1%）。所需的样品体积也大大减少。利用新采集的样品和实验室保存20多年的样品，获得了对流层和平流层中CF_4的精确分布和变化趋势。我们在尝试用大气氪作内标精确测定大气中痕量气体时，发现半个世纪来引用的大气氪浓度1.14± 0.01ppmv与观测值有出入。经三步浓缩和GC/MS测定，Kr浓度为1.099± 0.004ppmv，比目前公认的Kr浓度低4%。