Peroxyacetyl nitrate (PAN) at the urban core site of Seoul during 2015 MAPS / KORUS - AQ

A few measurements of atmospheric PAN were made in Seoul for the last decade. One study showed the average and maximum PAN concentration in summer of 2004 and 2005 with 0.8 ppb and 10.4 ppb and another study specified 0.64 ppb and 5.03 ppb, respectively in 2011. In this study, the measurements of peroxyacetyl nitrate (PAN) have been conducted at an urban site situated in KIST campus (Korea Institute of Science and Technology, Seoul, 127° 2'E, 37° 36'N) from May 18 to June 12, 2015. PAN was measured every 2 minutes by a fast chromatography with luminol-based chemiluminescence detection. Concentration of PAN ranged from 0.15ppbv to 4.37ppbv, with the average of 0.57 ppbv. PAN revealed its peak between 2 and 4 pm matching with the photochemical activities and precursor emission. When comparing with historic data of PAN in urban Seoul during the past decade, it has decreased about 50%. The rather rapid decrease of summertime PAN level for last ten years in Seoul will be discussed further with the behaviors of its precursor species.