北京城市大气CO2浓度变化特征及影响因素

北京大气CO₂浓度日变化强烈,全年北京时间15:00时前后为全天最低值,最高值则出现在夜间,日变化幅度为23.2～39.0μmol·mol^-1,夏季和秋季日变化幅度比冬季和春季大.北京城区大气CO₂浓度季节变化明显,最大值出现在冬季,月平均浓度为421.5～441.0μmol·mol^-1;最小值则在夏季,月平均浓度367.4～371.6μmol·mol北京CO₂浓度的季节变化幅度明显高于附近的华北兴隆区域站和瓦里关山大陆本底站等的相应值,其原因是北京CO2浓度季节变化主要受人为取暖活动控制,同时植被的季节变化也起一定作用.1993～1995年北京大气CO₂浓度上升较快,平均增长率为3.7%·a^-1,1995年平均浓度达到最高,为409.7±25.9μmol·mol,随后缓慢下降.

Characteristics of Atmospheric CO2 Variations and Some Affecting Factors in Urban Area of Beijing

The diurnal variation of the atmospheric CO2 at the urban area in Beijing displayed a very clear cycle, generally with the lowest value being recorded at about 15:00 local time and the highest in the nighttime. The differences between the maximums and the minimums ranged from 23.2 to 39.0 mumol.mol-1 in the four seasons and the ones of summer and fall were bigger than that of winter and spring. It showed a large seasonal cycle with a maximum in winter, from 421.5 to 441.0 mumol.mol-1, and a minimum in summer, between 367.4 and 371.6 mumol.mol-1. The peak-to-peak amplitude of atmospheric CO2 in Beijing, controlled mostly by the anthropogenic activities and seasonal variation of vegetation, was higher than that in Xinglong Station, Hebei Province and China Global Atmosphere Watch Baseline Observatory (Waliguan). The concentration of atmospheric CO2 in Beijing increased rapidly at a mean growth rate of 3.7%.a-1 from 1993 to 1995. After displaying a peak of 409.7 +/- 25.9 mumol.mol-1 in 1995, it decreased slowly.