北京大气中CFC-11的浓度观测与变化趋势

近几年大气中CFC的浓度在人类活动的影响下发生了迅速变化,考虑到CFC浓度变化对平流层臭氧和全球变暖的影响,采用两步深冷冻浓缩自动进样系统,配以气相色谱/质谱联机对北京大气中的CFC-11进行了连续观测.结果表明,1999～2003年CFC-11的浓度季节变化均呈单峰形态,峰值出现在7～8月,月平均浓度最高值为1149.5±531.9×10^-12(体积分数);谷值出现在春季的3～5月份,月平均浓度最低值为487.5±131.5×10^-12(体积分数);北京大气中CF-11年平均浓度在观测时间段内呈先上升后下降的趋势,其中1995～1998年增长较快,平均增长率为17.9%,1999年后呈缓慢下降趋势,平均下降率为10.7%,平均浓度是Mauna Loa全球基准观测站观测到大气本底CFC-11浓度的3～5倍.

Trends and Variation of CFC-11 in the Atmosphere of Beijing

In recent years, concentration of CFC in the atmosphere has undergone rapid changes especially in association with human activities. For the influence of CFC on climate changes and environment changes, the concentration of atmospheric CFC-11 in Beijing is continuously observed and analyzed by a gas chromatography-mass spectrometry. The seasonal variation concentration and trends of CFC-11 are reported. The results show that the seasonal variation of CFC-11 was basically similar from 1999 to 2003. There was one peak value in the seasonal variation of CFC-11 in 1999-2003. The highest monthly average concentration of CFC-11 was 1149.5 +/- 531.9 x 10(12) ( V x V(-1)) in summer and the lowest monthly average concentration of CFC-11 was 487.5 +/- 131.5 x 10(-12) (V x V(-1)) in spring. The annual average concentration of CFC-11 was increasing in Beijing atmosphere from 1995 to 1998, and the average increasing ratio was 17.9%. The annual average concentration of CFC-11 was slowly decreasing from 1999, and the average decreasing ratio was 10.7%. The average concentration of CFC-11 in the atmosphere of Beijing was 3 to approximately 5 times of the average concentration of CFC-11 in the atmosphere of Mauna Loa Station of U.S.A.