高精度观测大气O2/N2变化可以精确地区分全球陆地和海洋碳汇相对比例、估算海洋生物产率和海-气交换速率，并为验证大气传输模型和海洋碳循环模型提供理论依据，进而有效地补充全球生物地球化学循环和全球变化的研究框架。由于O2在大气中的浓度高达20.946%，因此测定其ppm级的浓度变化难度较大，国内尚未开展相关研究。本项目拟依托现有的工作基础和色谱调试经验，利用热传导检测器-气相色谱法搭建大气O2/N2实验室分析系统，从压力、温度控制和材质选择等方面优化系统，并通过开展系统工作性能、实验室O2/N2标气和工作气以及玻璃瓶采样和储存方法等研究，建立一套高精度大气O2/N2实验室分析标校方法，并在乌当科研合作站开展初步的外场观测研究，通过与日本国立环境研究所(NIES)同步观测结果的分析比较，进一步验证该方法的可靠性。

Measuring changes in the atmospheric O2/N2 ratio with high precision can be used to accurately partition the land biotic and oceanic carbon sinks, estimate the marine biotic productivity and air-sea gas exchange rates, provide theoretical basis on assessing the performance of the atmospheric transport patterns and ocean carbon cycle models, and thus augment the framework for studying global biogeochemical cycles and global change. Due to the high atmospheric O2 concentration level of 20.946 %, it's very difficult to detect such minute change at ppm level. By far, there is no related report in China. Based on the original work and previous experience on adjusting gas chromatograph, this study will focus on setting up a laboratorial measurement and calibration method on detecting the changes in the ratios of atmospheric O2/N2 with high precision. It will be jointly achieved through these sections as follows: the buildup of analytical system for detecting atmospheric O2/N2 changes by GC-TCD in the laboratory, the system optimization by controlling the pressure and temperature and selecting materials, the studies on the instrument performance, the reference and working gases of O2/N2 in the laboratory, and the sampling and store methods using glass flasks. Additionally, the preliminary field measurement will be conducted in Wudang partner station in this study, which is aimed to examine the reliability of this method by comparing the present results with those simultaneously observed by National Institute of Environmental Sciences (NIES) in Japan.