北京近交通主干线地区的臭氧生成效率

Ozone production efficiency in Beijing area with high NO_x emissions

2004年9月27日至10月4日一冷锋系统途径北京并带来了大风和降水天气，为了解冷锋过境前后北京近交通主干线地区臭氧生成效率的变化，利用此期间北京外场观测资料和箱模式计算了臭氧生成率及生成效率．结果表明，臭氧生成率可由观测结果进行求算，表达式为Q·∑Zi·Ki·[VOCi]／KOH＋NO2·[NO2],臭氧生成效率（OPE）变化范围为1．5～6．0，均值约为3．0，冷锋系统过境前、后OPE变化不显著．削减近交通主干线地区的VOCs排放量能有效降低该地的臭氧浓度．

A cold frontal system passed Beijing with strong wind and much rainfall within the period of Sep. 27 to Oct. 4, 2004. The ozone production rate （Po3） and ozone production efficiency （OPE） were calculated before and after the frontal system by a photochemical box model, constrained with observed concentrations of long - lived chemical species taken from the field experiment in the heavily NOx polluted area of Beijing. The results indicated that Po3 could be estimated from observations. The expression was Q·∑ Zi·Ki [ VOCi ]/KOH·NO2· [ NO2 ] , where [ VOCi ] , [ NO2 ] , Ki, KOH ＋ NO2 , Zi, Q denoted concentrations of specific volatile organic compound （ VOCi ） , NO2 concentrations, rate constants of reactions between OH and VOCi , rate constant of the reaction between OH and NO2 , an O3 yield resulted from the production of peroxy radicals in reactions between OH and VOCi , and total production rates of radicals, respectively. Ozone production efficiency （OPE） was within the range of 1.5 ～ 6. 0, with the average of 3.0, and it just caused minor changes in the OPE before and after the frontal system. Beijing area with high NOx emission sources was VOC sensitive.