Development of gas microanalysis method in ice cores

冰芯中过去20万年的大气成分信息储存在气泡和笼形水合物中，它们的尺寸小至1毫米或更小。为了准确地解释大气成分信息，对分析方法有很高的可靠性要求。在本研究中，考虑到气泡向笼形空气水合物转变过程中引起的气体分馏，我们旨在建立测量局部N_2和O_2组成的方法。我们将微拉曼散射法应用于测量，并建立了一种校正笼形水合物晶体各向异性数据的方法。因此，我们成功地阐明了冰盖中的气体分馏过程。我们证明了微拉曼散射法是一种非常可靠的方法来揭示单个笼形水合物中N_2/O_2比的分布。然而，为了确定气体成分的绝对精度，必须将所得数据与化学分析所得数据进行比较。我们还开发了一套气体定量分析系统，使用气相色谱质谱仪。

Information of the atmospheric composition over the past 200,000 years in ice cores is stored in air bubbles and clathrate hydrates, of which sizes are as small as 1mm or less. In order to interpret information of the atmospheric composition precisely, high reliability is required in the analysis method. In this study, considering gas fractionations caused by the transition process of the air bubble to the clathrate air-hydrates, we aimed at development of the method to measure the local composition of N_2 and O_2.We have applied a micro-Raman scattering method to the measurements, and we have established the method to correct the data for crystal anisotropy of the clathrate hydrates. As a result, we have successfully clarified the gas fractionation process in ice sheets. We proved that the micro-Raman scattering method is a highly reliable method to reveal the distribution of N_2/O_2 ratio in the individual clathrate hydrates. For the absolute precision of the gas compositions, however, the data should be compared with those obtained by the chemical analysis. We also developed a system of the quantitative analysis of gases using the gas chromatography I mass spectrometer.