Status: this preprint was under review for the journal ACP. A revision for further review has not been submitted.
Source analysis of peroxyacetyl nitrate (PAN) in Guangzhou, China: a yearlong observation study
B. G. Wang,D. Zhu,Y. Zou,H. Wang,L. Zhou,X. Ouyang,H. F. Shao,and X. J. Deng
Abstract. In recent years, photochemical smog has been a major cause of air pollution in the metropolitan area of Guangzhou, China, with a continuing increase in the concentrations of photochemical pollutants. The concentration of peroxyacetyl nitrate (PAN) has often been found to reach very high levels, posing a potential threat to the public health. To better understand the changes in PAN concentration and its sources, a study was carried from January to December of 2012 at the Guangzhou Panyu Atmospheric Composition Station (GPACS) to measure the atmospheric concentrations of PAN as well as those of ozone (O3), nitrogen oxides (NOx), and non-methane hydrocarbon (NMHC). These data were analyzed to investigate the quantitative relationships between PAN and its precursors. In the study period, the hourly concentrations of PAN varied from below instrument detection limit to 12.0 ppbv. The yearly mean concentration of PAN was 0.84 ppbv, with the daily mean concentration exceeding 5 ppbv in 32 of the total observation days. Calculations indicate that among the measured NMHC species, alkenes accounted for 53 % of the total NMHC contribution to the PAN production, with aromatics and alkanes accounting for about 11 and 7 % of the total, respectively. During the period of our observation only a modest correlation was found between the concentrations of PAN and O3 for daytime hours, and observed PAN concentrations were relatively high even though the observed NMHCs/NOx ratio was low. This suggests regional air mass transport of pollutants had a major impact on the PAN concentrations in Guangzhou area.
Received: 24 Apr 2015 – Discussion started: 23 Jun 2015
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Photochemical smog has been a major cause of air pollution in Guangzhou, one of megacities in China. This study firstly examined the source of peroxyacetyl nitrate in Guangzhou based on a yearlong data set including PAN, ozone, nitrogen oxides and non-methane hydrocarbons. The results suggest regional air mass transport of pollutants had a major impact on the PAN concentrations in Guangzhou area, which will provide useful information for more effectively managing the air quality of Guangzhou.
Photochemical smog has been a major cause of air pollution in Guangzhou, one of megacities in...
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