Monitoring and analysis of SO_2, NO_2 and O_3 in Winter of Beijing

Based on the differential optical absorption spectroscopy (DOAS) technology, measurements of SO2, NO2 and O3 were carried out continuously in Feb. 2006 in Fengtai District of Beijing and their diurnal variation characteristics and sources are analyzed. Results indicated that automobile exhaust is the main source of NO2. The concentration of NO2 is high in the morning and evening during heavy traffic and low at dawn and afternoon. The diurnal variation of SO2 concentration has the same shape as letter N. In morning and midnight SO2 concentration is high, which results from variation of the meteorology and sources. From the analysis of correlation of O3 and NO2, It can be found that NO2 contributes to the O3 formation and there are some other important precursors for O3.