深圳西部城区大气O3污染特征及超标成因

Study on the characteristics and the cause of atmospheric O3 pollution in western urban of Shenzhen

利用近5a深圳西部城区(大学城)大气臭氧(O3)在线监测数据,结合深圳大学城超级站大气复合污染综合观测,获取了大气O3演变趋势,并探究O3超标日气象条件及其前体物的组成变化以期掌握大气O3超标成因.结果表明,深圳大学城大气O3日最大8h平均体积分数上升速度达1.1×10^-9/a,超标率达到6%以上.高温低湿的气象条件更容易促进大气O3生成,高温时光化学反应强烈有利于O3的本地生成,而低湿可能不利于O3的湿去除从而导致污染积累.挥发性有机物(VOCs)不同组分在O3超标日上升幅度(70%~95%)明显高于NOx(28%),且O3高值浓度分布在高VOCs低NOx区域,说明深圳大学城大气O3生成主要受VOCs控制.O3超标日的甲苯与苯比值(T/B)在夜间超过10表明可能存在大量工业排放;而含氧挥发性有机物(OVOCs)在午间(12:00~14:00)的消耗相较于非超标日高出了1倍左右,表明工业活动排放的OVOCs对白天O3生成可能贡献显著.

Based on the online monitoring data of atmospheric O3 at University Town that located in the western Shenzhen in the past 5years,combined with the comprehensive observation of atmospheric pollutants,the evolution trend of atmospheric O3 was obtained.In addition,the variations of meteorological conditions and the precursor’s composition of O3 during the exceeding standard periods were deeply explored in order to grasp the causes.The resultsshow that the increase rate of the maximum 8-hour average mixing ratio of atmospheric O3 was 1.1×10^-9/a,and the exceed-standard rate was over 6%.High temperature and low humidity meteorological conditions were more likely to promote atmospheric O3 formation.The increase of VOCs in the O3 exceeding standard periods(70%~95%)was significantly higher than that of NOx(28%),and the O3 high concentration was distributed in the high VOCs and low NOx region,indicating that the O3 formation was mainly controlled by VOCs in University Town of Shenzhen.The toluene to benzene ratio(T/B)over 10at night during the O3 exceeding standard periods suggesting that there may be a large amount of industrial emissions,while the consumption of OVOCs doubled at noon,indicating that OVOCs emitted by industrial activities may contribute significantly to daytime O3 production.