成都市夏季臭氧污染特征及影响因素

Characteristics and influencing factors of ozone pollution in summer in Chengdu

利用2014年夏季成都市3个国控环境监测站(金泉两河,君平街和梁家巷)O3、NO2及PM2.5逐时观测数据,结合国家基准站温江站的气温、湿度、风速、风向、太阳辐照度、降雨等地面气象要素观测资料,分析O3的日、月变化及空间分布特征;探究前体物及气象因子对O3浓度的影响。结果表明:成都市O3-8h平均浓度为104.4μg·m^-3,O3超标率为2.8%—15.3%。O3浓度6月最高,8月最低;呈现明显的“单峰型”日变化特征,午后15:00达到峰值。O3与NO2呈现负相关,相关系数为-0.5;与PM2.5无显著相关性。高温、低湿、强太阳辐射有利于O3的形成;风速为2.5—3.0m·s^-1,风向为南风时,O3浓度相对较高。

Based on the hourly O3,NO2,and PM2.5 concentrations at three national environmental monitoring sites(Jinquanhe,Junpingjie,and Liangjiaxiang)and surface meteorological parameters including temperature,relative humidity,wind speed and direction,solar radiation,and precipitation at the Wenjiang national weather station in Chengdu during summer of 2014,we analyzed the diurnal and monthly variations and spatial distributions of O3 concentrations and explored the effects of precursors and meteorological parameters on O3 concentration.The results showed that the averaged concentration of O3-8 h is 104.4μg·m^-3,and the proportion of days with O3 concentration exceeding the Chinese National Air Quality Standard ranges from 2.8%to 15.3%at different sites.The highest and lowest O 3 concentration occur in June and August,respectively.The diurnal variation of O3 concentration exhibits a single peak at 15:00.O3 concentration has a negative correlation with NO 2 concentration,with a correlation coefficient of-0.5,and has no significant correlation with PM2.5 concentration.High temperature,low relative humidity,and strong solar radiation are beneficial to the O 3 formation.The higher O3 concentration usually occurs in the presence of southerly flows with wind speed between 2.5-3.0 m·s&-1.