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

Abstract

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.