An analysis of chemical and meteorological characteristics of haze events in the Seoul metropolitan area during January 12–18, 2013

Abstract

The chemical characteristics of secondary inorganic and carbonaceous aerosols as well as their formation mechanisms during the haze event of January 12–18, 2013, in the Seoul Metropolitan Area (SMA) were investigated using measurements at the Baengnyeong and Seoul supersites with data available from LIDAR, meteorology, and modeling. An extraordinary haze event that occurred in northern China during that period extended to the Korean Peninsula and initiated the haze event in the SMA. Local emissions of primary aerosol and gaseous precursors in the SMA then made the situation worse under adverse meteorological conditions.OM (Organic Matter) and SO42− were the major long-range transport (LRT) aerosols from the Beijing, Tianjin and Hebei province (BTH) area to the SMA during the initial stage of the haze event. The LRT of SO42− from the BTH area, which was detected at Baengnyeong Island, was mostly acidic, while in Seoul, it was fully neutralized to (NH4)2SO4.The SIAs (Secondary Inorganic Aerosols) consisting of 56.5% PM2.5 during the haze period were the major chemical species causing haze problems in the SMA. NO3− was the most dominant chemical species among the SIAs and was locally formed by a heavy burden of NOx emissions from mobile sources in the SMA. Carbonaceous aerosols of OM and EC (Elemental Carbon) in the SMA during the haze period consisted of 18.9% PM2.5, but secondary organic carbon (SOC) was not the key species inducing the haze event during the January episode in the SMA.