Development of a high precision measurement system for atmospheric oxygen concentration

高精度大气氧浓度测量系统的研制

• 批准号: 10554021
• 负责人: AOKI Shuji
• 金额: $ 6.72万
• 依托单位: TOHOKU UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 1998
• 资助国家: 日本
• 起止时间: 1998 至 1999
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-10554021/
• 关键词: oxygen; high precision; measurement system; mass spectrometer; standard gases; 標準誤差; 炭素循環; Co_2濃度; 大気; 質量分析計

A high precision measurement system of atmospheric oxygen concentration has been developed by the research project. The system consisted mainly of a detector, double inlets made of pyrex glass, a high precision pressure adjuster and a computer. A mass spectrometer of the Nier-McKinney type was selected for the detector of the system. The fused-silica-capillaries of 25mm I.d. and 1.35m length were used for connection between the double inlets and the detector. Air samples could be introduced into the inlet at an atmospheric pressure by the capillary. We confirmed that fractionation of air components did not occurred in the capillary. We found that oxygen enrichment occurred at a part of lower temperature of airflow line. Therefore, the system was settled in our air-conditioned laboratory and the capillary with a very small heat capacity was covered by double insulation tubes. Isobaric interference for N2 due to the formation of CO from CO2 in the ion source of the mass spectrometer was a serious problem for the high precision measurements. An empirical formula for CO2 and O2 concentrations was established by an experiment for correction of the interference of air samples.Standard gases for O2 measurements were prepared by ourselves. Natural air was collected and stored in a high-pressure cylinder through water vapor traps. Such a collection of large amount of air was made several times in different seasons to prepare standard gases of different O2 concentrations. To confirm stability of O2 concentration of these standards, we made mutual calibration between these standards for more than 1 years. As a result, all the standard gases were stable within +-20 per meg and any drift of O2 concentration could not observable.The standard error of +-5.6 per meg for a sample analyzed in quadruplicate could be attained for the measurement system.

本课题研制了一套高精度的大气氧浓度测量系统。该系统主要由探测器、高温玻璃双进气口、高精度压力调节器和计算机组成。该系统的检测器选用Nier-McKinney型质谱仪。25 mm直径的熔融硅胶毛细血管。双进水口与探测器之间的连接长度为1.35m。空气样品可以通过毛细管在大气压下送入进气口。我们证实，毛细管内没有发生空气成分的分馏。我们发现，富氧发生在气流线较低温度的一部分。因此，该系统被安置在我们的空调实验室，用双绝缘管覆盖了热容很小的毛细管。在高精度测量中，质谱仪离子源中的CO生成CO对氮气的等压干扰是一个严重的问题。通过对空气样品干扰的校正实验，建立了二氧化碳和氧气浓度的经验公式，并自行配制了氧气测量的标准气体。自然空气通过水蒸气捕集器收集并储存在高压圆筒中。如此大量的空气收集是在不同的季节多次进行的，以制备不同氧气浓度的标准气体。为了确定这些标准的氧气浓度的稳定性，我们对这些标准进行了1年多的相互校准。结果表明，所有标准气体在+-20/Meg范围内稳定，氧气浓度不会有任何漂移。对于四份样品，该测量系统可以达到+-5.6/Meg的标准误差。

项目成果

Yokouchi Y.,Nojiri Y.,Barrie L.A.,Li H-J.,Fujinuma Y.and Aoki S.: "A strong source of methyl chioride to the atmosphere tropical coastal land"Nature. 403. 295-298 (2000)

Yokouchi Y.、Nojiri Y.、Barrie L.A.、Li H-J.、Fujinuma Y. 和 Aoki S.：“热带沿海地区大气中氯甲烷的强烈来源”《自然》。

Yokouchi,Y.,Li,H-J.,Machida,T.,Aoki,S.,Akimoto,H.: "Isoprene in the marine boundary layer (Southeast Asian Sea,eastern Indian Ocean,and Southern Ocean)"J.Geophys.Res.. 104. 8067-8076 (1999)

Yokouchi,Y.,Li,H-J.,Machida,T.,Aoki,S.,Akimoto,H.：“海洋边界层（东南亚海、东印度洋和南大洋）中的异戊二烯”J.Geophys。

Saeki T.,Nakazawa T.,Tanaka M and Higuchi K.: "Methane emissions from a two-dimensional atmospheric transport model and surface consentration data"J. Meteorol. Soc. Japan. 76. 307-324 (1998)

Saeki T.，Nakazawa T.，Tanaka M 和 Higuchi K.：“二维大气传输模型和表面同意数据的甲烷排放”J。

Aoki S., Nakazawa, T., Honda, H., Yajima, N., Machida, T., Sugawara, S., Kawamura, K., and Yoshimura, S.: "CO2, CH4 and N2O concentrations and δ13C in CO2 and CH4 in the stratosphere over Scandinavia and Japan"Proceedings of the 21st International Symposi

Aoki S.、Nakazawa, T.、Honda, H.、Yajima, N.、Machida, T.、Sukawara, S.、Kawamura, K. 和 Yoshimura, S.：“CO2、CH4 和 N2O 浓度以及 δ13C斯堪的纳维亚半岛和日本平流层中的CO2和CH4《第21届国际研讨会论文集》

Murayama,S.,Yamazaki,K.,Nakazawa,T.and Aoki,S.: "Interpretation of high concentrations of O3 observed in the upper troposphere over Syowa Station,Antarctica using a trajectory analysis" Geophys.Res.Lett.25. 1177-1180 (1998)

Murayama,S.、Yamazaki,K.、Nakazawa,T. 和 Aoki,S.：“使用轨迹分析解释在南极洲昭和站上空对流层上层观测到的高浓度 O3”Geophys.Res.Lett.25。