Based on observed atmospheric CO₂ concentrations at 10 background stations in East Asia,temporal and spatial variations in atmospheric CO₂ are analyzed,and impacts of the underlying surface,source and sink upon atmospheric CO₂ levels are also discussed.Analysis results reveal that the monthly averaged CO₂ concentrations at the observation stations exhibit strong seasonal variations.The higher values appear in cold seasons such as winter and spring,while the lower values present from July to September,i.e.,summer in northern hemisphere.Diurnal variations in CO₂ concentrations are approximately same at these stations.The concentration reaches its lowest at about 15:00 LST (Local Standard Time),and then goes up constantly during night and reaches its highest at 7:00 LST,and after that it decreases subsequently with the radiation strengthens.There are inverse relationships between the mean CO₂ concentration and the vegetable amount of underlying surface,and between the range of the daily concentration variation and the vegetable amount,respectively.The annually averaged CO₂ concentration rose constantly from 2004 to 2008 at Mt.Waliguan,one of global background stations,with an increase rate of 2.28×10^-6/a.