Peroxyacetyl nitrate observed in Beijing in August from 2005 to 2009

Tianyu Gao , Li Han , Bin Wang , Guang Yang , Zhenqiang Xu , Limin Zeng , Jianbo Zhang


Received November 30, 2013,Revised January 28, 2014, Accepted , Available online October 22, 2014

Volume 26,2014,Pages 2007-2017

Measurements of peroxyacetyl nitrate (PAN) weremade at a Beijing urban site each August from 2005 to 2009. Over this 5-year period, the average PAN concentration for August in each year increased from 3 (2005) to 11.7 μg/m3 (2007); however, it decreased rapidly in 2008 (4.1 μg/m3). Generally, the variation over the 5 years showed a rise in the first part of the study period, followed by a decline. We considered two categories of local and regional air masses in this study,which revealed that the PANconcentration in Beijingwas affectedmainly by southeastern airmasses. The August PAN variationwas influenced predominantlyby localairmasses in2005, but by 2009 regional air masses had become more important. This study showed the level and variationofPAN in themonthof August in5consecutive years for the first time, and proved that control measures are useful in decreasing photochemical pollution; hence, these measures are probably feasible for other megacities too. Furthermore, this method of analyzing regional and local impacts might be useful for other studies as well.

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