Airborne Measurements of High Pollutant Concentration Events in the Free Troposphere over the West Coast of South Korea between 1997 and 2011

Aircrafts enable the direct measurement of chemical components in the free troposphere (FT). This study employed airborne measurements to examine the occurrences of high concentrations of SO2 and NOx in the FT over the coastal region west of the Seoul metropolitan area, South Korea. The data from a long-term (1997-2011) airborne measurement campaign were used to determine the meteorological conditions favorable for carrying these pollutants into the Seoul area. The back trajectory analyses of 21 instances of high FT pollutant concentration events showed ascending patterns from the major pollutant sources, mainly the industrial complexes in eastern China, in 9 instances and passing patterns in 12 instances. In the ascending instances, developing low-pressure systems over the source regions provide favorable conditions to uplift air pollutants from the surface into the FT. In the passing instances, an anomalous low-pressure system near the surface prevented airflows from descending into the boundary layer and upper-level anticyclonic systems helped to keep the ascending airflows in the FT. This study proposes the basic mechanisms for predicting air quality in the Seoul area, considering that air pollutants in the FT often entrain into the boundary layer to increase local concentrationsopen0

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Volatile Organic Compounds (VOCs) are a major precursor generating ozone (O3) and Secondary Organic Aerosols (SOAs) by reacting with nitrogen oxides (NOX) and OH radicals in the atmosphere. In this study, the scenarios of VOC emission reduction in Ulsan were suggested based on two emission inventories: the Clean Air Policy Support System (CAPSS) and the Pollutant Release and Transfer Register (PRTR). Considering the characteristics of VOC emissions, three scenarios of VOC emission reduction were derived: (1) Scenario 1-1 reducing TVOC emissions by the type of emission sources, (2) Scenario 2-1 reducing BTEX emissions by areas and compounds, and (3) Scenario 3-1 reducing BTEX emissions by the type of industrial facilities. The concentrations of VOCs before and after the emission reduction were simulated using an air dispersion model. Then, their corresponding Secondary Organic Aerosol Formation Potential (SOAFP) was calculated, and reduction efficiencies in VOCs and SOAFP were compared among the three scenarios. Scenario 2-1 showed the most significant decrease in VOC concentrations. Scenarios 1-1 and 2-1 presented higher reduction efficiencies of VOCs and SOAFP than control scenarios that reduce the same emission amounts without considering emission characteristics (i.e., industrial facilities, areas, and compounds). The methodology and major results of this study can be a basis for establishing VOC and SOA management policies

Sensitivity analysis of volatile organic compounds to PM2.5 concentrations in a representative industrial city of Korea

Abstract This study aims to analyze the sensitivity of volatile organic compounds (VOCs) to ambient concentrations of fine particles (PM2.5) in the representative industrial city of Ulsan, Korea. For the calculation of sensitivity coefficients between VOCs and PM2.5 (SVOCs-PM2.5), PM2.5 data were obtained from an air quality monitoring station, and their corresponding 6-h average concentrations of VOCs (alkanes, alkenes, aromatics, and total VOCs) were measured at the Yeongnam intensive air monitoring station. The air monitoring period was divided into the warm-hot season (May–October 2020) and the cold season (November 2020–January 2021). The sensitivity coefficients in the low pollution period of PM2.5 (5  35 μg/m3, than other VOC groups. The result of this study can be a basis for establishing PM2.5 management plans in industrial cities with large VOC emissions