江苏省臭氧时空分布及其前体物影响特征研究

Pollution Characteristics of Ozone and Impacts of Its Precursors in Jiangsu Province

为研究江苏省13市O_3污染时空分布特征,对江苏省72个国控站点2013-2015年监测数据进行了统计分析,并以南通为典型城市开展强化观测,研究其前体物对O_3的影响特征。结果表明:2013-2015年江苏省O_3日最大8 h平均值第90百分位数平均为139~167μg/m^3,是长三角O_3浓度最高、上升最快的区域。2015年O_3对空气质量不能达到优良的贡献为33%,比2013年上升23.5%。4-10月O_3污染最为严重,且近3 a出现高值的时间逐年拉长。南京市O_3浓度存在周末比工作日高的"周末效应",各点位周末O_3日最大1 h浓度比工作日平均高2.6~4.6μg/m^3,而周末NOx浓度相对较低。江苏省O_3最大8 h浓度呈现较为明显的片状分布特征,高值区分布在苏中、苏南内陆地区,低值出现在徐州、宿迁。O_3与NO_2、CO的日变化浓度呈显著的负相关,南通城区O_3的形成主要受VOCs控制,对O_3贡献最大的物种包括丙烯、二甲苯、乙炔、乙烷等。

To investigate the pollution characteristics and influence factors of ozone, the environmental data at 72 national monitoring stations were analyzed. Correlations with precursors of ozone was analysed on the basis of intensified observation in Nantong. Results showed that the average percentile 90 of maximum daily ozone 8 hour average concentrations of 13 cities in 2013-2015 were 139-167 μg/m-3 in Jiangsu, which has become the most severely ozone polluted area in Yangtze River Delta. The contribution of O3 to the days that exceeded the Grade Ⅱ of Ambient Air Quality Standard was 33%, rising 23.5% compared to 2013. O3 pollution was the most serious from April to October, and the time of high value appeared in recent three years was lengthened year by year. There was an obvious＂weekend effect＂of atmospheric O3 in Nanjing. The maximum daily ozone 8 hour average concentrations on weekends were 2.6-4.6 μg/m-3, higher than those on weekdays. The decrease of NOx emission at the weekend is the most likely chemical cause. From the special distribution, the maximum daily ozone 8 hour average concentration showed continuous distribution, O3 concentrations in inland regions of south and mid Jiangsu were much higher than those in north Jiangsu（Xuzhou, Suqian）. Regional transport from the east of Yangtze River Delta made significant contribution to O3 pollution in spring and autumn days. The O3 concentrations were significantly negatively related to the concentrations of NO2 and CO. The concentration of ozone was mainly affected by VOCs in urban area of Nantong. The largest O3 contributing VOCs species were propene, ethane, xylene, acetylene.