Study on the in-situ Measurement of Atmospheric CH4 and CO by GC-FID Method at the Shangdianzi GAW Regional Station
北京上甸子站气相色谱法大气CH4和CO在线观测方法研究

In-situ GC-FID system for atmospheric CH4 and CO mixing ratio measurements at the Shangdianzi (SDZ) GAW regional station in Beijing was designed and optimized in 2009 based on a comparable system at the Waliguan GAW global station in Qinhai. Results from this study indicate that the system's precisions for CH4 and CO are higher than 0.03% and 0.45% respectively, which can meet the quality target on background greenhouse gas observations by the World Meteorology Organization's Global Atmosphere Watch (WMO/GAW) program. The selection method of working standards for this system was established: two working standards(WH for the high concentration and WL for the low concentration) were selected, the concentrations of CH4 and CO in these two standards can cover the ambient mixing ratios of CH4 (2007.1×10-9 and 1809.5×10-9) and CO (405.6×10-9and 123.8×10-9), an injection sequence was programmed so that the two standards were analyzed alternatively for every three runs. The measurement accuracies are high, as shown by the standard deviations less than 1.7×10-9 and 1×10-9, for CH4 and CO, respectively. This method has been applied to in-situ measurement of atmospheric CH4 and CO in North China.