BACKGROUND CONCENTRATION OF ATMOSPHERIC CO₂, CH₄ AND N₂O AT MT.WALIGUAN AND XINGLONG IN CHINA

In order to study the characteristics of regional distribution and variation of greenhouse gases, including CO₂, CH₄ and N₂O on the China continent and their relationships with human activities, the variations of atmospheric concentrations of CO₂, CH₄ and N₂O were measured at China Atmosphere Watch Baseline Observatory at Mt. Waliguan (36°18′N, 100°54′E, 3810 m) and at Astronomical Observatory at Xinglong (40°24′N, 117°30′E, 940 m) during the period of 1995 to 2000 with stainless steel sampling canisters by means of the gas chromatographic method. The results show that the average atmospheric concentrations of CO₂, CH₄ and N₂O at both Xinglong and Mt. Waliguan are 376.7×10^-6 and 373.5×10^-6, 1886×10^-9 and 1831×10^-9, 316.7×10^-9 and 314.9×10^-9, respectively. From 1995 to 2000, the average annual increments of CO₂, CH₄ and N₂O at Xinglong are 1.95×10^-6 mol/mol, 9.02×10^-9 mol/mol, and 0.75×10^-9 mol/mol, respectively. The average annual increments of CO₂, CH₄ and N₂O at Mt. Waliguan are 1.41×10^-6 mol/mol, 9.95×10^-9 mol/mol and 0.82×10^-9 mol/mol respectively. The atmospheric concentrations of CO₂, CH₄ and N₂O and the average annual growth rates are closed to the monitoring results from the similar global observatories. On the other hand, the results reveal the difference of the environmental background between Xinglong and Mt. Waliguan to some extent.