2013~2014年北京市NO_2时空分布研究

Spatial and temporal distribution of NO_2 during 2013~2014 in Beijing

根据2013~2014年北京市NO2监测数据,对比分析了全年及重污染日NO2时空分布特征.结果表明：2013年NO2平均浓度为56μg/m3,2014年北京市NO2年均浓度为56.7μg/m3.年均及重污染日NO2月均浓度均呈波浪型分布,日变化呈双峰型分布;空间分布上北部及西部山区NO2浓度明显低于中心城区及南部地区.NO2浓度与PM2.5、CO、NO呈正相关关系,与O3、OX无明显相关性;全年NO2光解速率峰值平均在0.105/min左右,重污染日光解速率峰值平均在0.026/min左右;全年及重污染期间,氮氧化速率分别为0.142±0.061、0.190±0.036;高浓度NO2既有利于O3生成,又对重污染的形成起到了促进作用;重污染日特定条件下北京市NO2的两种转化机制以转化为NO3-过程为主导.经计算2000~2014年北京市机动车的保有量与NO2浓度的相关系数R为-0.84,机动车NOx排放量对北京市NO2浓度的变化有显著的影响.

The Spatial and temporal distribution characteristics of NO2 during 2013~2014 were analyzed based on the NO2 monitoring data released by Beijing Municipal Environmental Monitoring Center. The analytical results showed that the annual average concentration of NO2 in Beijing was 56.7μg/m3 in 2014and increased 1.3% compared to that of NO2（56μg/m3） in 2013. The monthly average concentration of NO2 changed in a wave-shape curve and the diurnal variation of NO2 showed bimodal distribution. The annual average concentration of NO2 was lower in the northern and western regions while higher in the six city area and southern area; NO2 and PM2.5, CO, NO showed a positive correlation while NO2 and OX, O3 had no significant correlation relationship. Calculated photolysis rate of NO2 in the whole year and heavy pollution days was 0.105/min, 0.026/min, respectively. The values of NOR was 0.142±0.061, 0.190±0.036 in the whole year and heavy pollution days, respectively. High concentration of NO2 was conducive to the formation of O3 and also played a promoting role of heavy air pollution formation. Correlation coefficient between vehicle number and the annuanl concentration of NO2 during 2000~2014 in Beijing was-0.84 and the NOx emissions of vehicle had a significant effect on the change of the annual concentration of NO2 in the area of Beijing city.