Study of the "Weekend Effect" of O_3,NO_x and Other Pollutants in Summer of Beijing
北京市夏季O3、 NOx等污染物“周末效应”研究

The data of O_3,NO_x(NO and N0_2),CO and SO_2 observed at Beijing 325m meteorological tower from June 25 to July 7,2000 and from July 26 to August 22,2000 are used to analyze the difference of pollutant concentrations on weekends and weekdays, and its causes. Results show that except SO_2,the correlations of O_3,NO_x,NO,NO_2 and CO concentrations between weekends and weekdays are very significant, since they all pass the t-test significance level at α=0.05.The correlation coefficients(R)are 0.99,0.61,0.56,0.80 and 0.61 for O_3,NO_x,NO,N0_2 and CO, respectively. Weekend NO_x and CO concentrations are lower than weekday concentrations in rush hours(06:00～08:00),and the mean deviations for NO_x and CO concentrations are -28% and -9%,respectively.The regression coefficient of O_3 concentrations between weekends and weekdays is 1.25±0.02.Furthermore,the maximum 1-h average O_3 concentration and maximum 8-haverage O_3 concentration on weekends are 23% and 26% higher than those on weekdays, respectively, indicating an obvious O_3"weekend effect".