广州番禺大气成分站一次典型光化学污染过程PAN和O_3分析

Analysis of Peroxyacetyl Nitrate and Ozone During a Typical Photochemical Pollution Process at the Panyu Atmospheric Composition Station

通过对广州番禺大气成分站(GPACS)的光化学相关污染物(O_3、PAN、VOCs、NO_2、NO)以及气象要素进行观测,分析2010～2016年期间发生在广州地区一次典型光化学污染过程.结果表明,该光化学污染过程期间,O_3和PAN总体体积分数比较高,最大O_3小时体积分数为140. 6×10^(-9),而最大PAN小时体积分数为4. 7×10^(-9). NO整体体积分数较低,对O_3的化学滴定和PAN的去除影响较小. NO_2整体体积分数较高、辐射较强和风速较低则有利于O_3和PAN的形成和积累. PAN和O_3具有一定的线性关系(R^2=0. 55),而形成PAN和O_3前体物VOCs物种不完全相同影响着它们的线性关系,在生成PAN的VOCs物种中,乙烯、丙烷、异戊二烯和甲苯所占的比例较大,而对臭氧生成潜势较大的物种有异戊二烯、1,3,5-三甲苯、丙烯、间,对-二甲苯以及甲苯.对PA自由基体积分数进行估算,发现它的日均值体积分数在0. 11×10^(-12)～0. 16×10^(-12)范围变化,远高于其它地区,表明此次发生的光化学反应较为强烈.

The typical photochemical pollution process in Guangzhou was analyzed from 2010 to 2016 by observing photochemical pollutants (ozone (O3), peroxyacetyl nitrate (PAN), volatile organic compounds (VOCs), nitrogen dioxide (NO2), and nitric oxide (NO)) and meteorological factors at the Guangzhou Panyu Atmospheric Composition Station (GPACS). The results showed that during this photochemical pollution process, the average O3 and PAN concentrations were relatively high:O3,max 1 h concentration was 140.6×10-9 and PANmax 1 h concentration was 4.7×10-9. The average concentration of NO was low, which had little effect on O3 titration and PAN elimination. The high NO2 concentration, strong radiation, and low wind speed all led to the formulation and accumulation of O3 and PAN. The linear relationship between O3 and PAN (R2=0.55) was affected by the fact that their precursor VOCs were not similar. Ethene, propane, isoprene, and toluene had a large influence in PAN formation, while isoprene, 1,3,5-trimethylbenzene, propene, m,p-xylene, and toluene had a large influence on O3 formation potential. When evaluating PA concentration, we found that its daily average concentration ranged from 0.11×10^-12 to 0.16×10^-12, which were higher than many places around the world, indicating that this photochemical process was relatively intensive.