前体物与气象因子对珠江三角洲臭氧污染的影响

摘要

利用2012年中国气象局广州番禺大气成分站的O3、NOx逐时浓度数据,广州观象台逐时的温度、相对湿度以及风向风速数据,统计分析了2012年O3前体物(NOx)以及气象因子对珠江三角洲(以下简称珠三角)地区臭氧浓度的影响.研究发现:O3和NOx均表现出单峰结构的月变化特征,且分别于10月和3月达到峰值,为(104.9±68.0)μg/m3,(131.1±122.1)μg/m3.O3的日变化为单峰分布,午后的浓度较高,而NOx浓度于早晚高峰有增加,且夜间浓度高于白天.NOx对O3有显著的滴定作用,O3浓度随着NOx浓度的增加呈现指数形式下降.高温低湿条件有利于O3的形成.与NOx类似,O3浓度随着温度和相对湿度的增大以指数形式相应的增大和减小.当珠三角地区受偏西风控制时,下风向地区的O3浓度最高,而当珠三角地区盛行偏北风时,下风向地区的O3浓度最低,且该方向所对应的NOx浓度最高,表明广州城区的NOx对O3的滴定作用显著.珠三角地区发生光化学污染的关键性因子主要为20~40μg/m3的NOx浓度,高于27°C的气温,低于55%的相对湿度以及受偏西风控制.分析发现10月份O3的形成主要受VOCs控制,且烯烃的O3生成潜势贡献最大,为69%,而烷烃和芳香烃的贡献分别为15%、16%.%Based on the hourly data of O3, NOx, and VOCs concentration from China Meteorology Administration (CMA) Guangzhou Panyu Atmospheric Composition Observation Station, and the meteorological data, such as temperature, relatively humidity and wind data from Guangzhou meteorology observation station, the impacts of ozone precursors (NOx, VOCs) and meteorological factors on O3 pollution in the Pearl River Delta (PRD) have been researched. It was found that the monthly variations of O3 and NOx were single-peak distribution with the peak concentrations were (104.9±68.0)μg/m3, (131.1±122.1)μg/m3in October and March, respectively. And the diurnal variation of O3 also was unimodal distribution that the O3 concentration was highest in the afternoon. While NOx concentration had an obvious increase during rush time, and NOx concentration in the nighttime was much higher than daytime. The titration of NOx played an important role in O3 pollution that O3 concentration was exponentially suppressed with increasing NOx concentration. High temperature and low relatively humidity condition was in favor of O3 formation. Similar with NOx, O3 concentration was also exponentially suppressed with increasing relatively humidity, while the relationship between O3 and temperature was opposite that O3 concentration was exponentially increased with increasing temperature. When western wind was prevailed in the PRD region, O3 concentration of downward area was highest, while when PRD was controlled by northern wind, O3 concentration was lowest companied with the highest NOx concentration, it also suggests that the titration of NOx in O3 concentration. In general, the key factors for photochemical pollution occurred in PRD region were NOx concentration of 20~40μg/m3, temperature with higher than 27°C, relatively humidity with lower than 55% and western wind dominant, respectively. The formation of O3 in October was controlled by VOCs, and the contribution of alkenes to ozone production potential was highest, which was 69%. While the contributions of alkanes and aromatics were much lower, were only 15%, 16%, respectively.