高灵敏激光吸收光谱仪监测北京城区甲烷浓度变化

Continue Monitoring of Methane in Urban Area of Beijing with Laser Absorption Spectroscopy

利用可调谐半导体激光吸收光谱(TDLAS)对环境空气中的甲烷进行了测量。选择不受干扰的1．65μm处的吸收线对甲烷进行浓度监测。在2005年秋季对北京城区的甲烷气体以1min的时间分辨率进行了近1个月的连续监测。甲烷的浓度在19:00左右开始上升,在凌晨01:00左右开始下降,具有明显的周期性。浓度最低值出现在白天,而最大值出现在夜里,给出了甲烷的日变化和连续监测结果。

Ambient methane was measured by tunable diode laser absorption spectroscopy （TDLAS）. The absorption line of methane at 1.65 μm was found to be free of interference and suitable for ambient methane measurements. Methane was continuously measured for nearly 270 hours with one minute temporal resolution at an urban site in Beijing during the autumn of 2005. The concentration of methane increased after 19：00 and fell after 01：00 at night. The variation of CH4 concentration has an obvious periodicity. The lowest concentration obtained in the daytime while the highest at night. The diurnal variations of atmospheric CH4 and continue monitoring results were presented.