The Chemical Characteristics and Formation of Potential Secondary Aerosol (PSA) using an Oxidation Flow Reactor (OFR) in the Summer: Focus on the Residential Area, Suwon

Secondary aerosol (SA) is an important component of atmospheric fine particle (PM2.5) and one of the main cause of the air pollution. However, the estimation of production of SA in ambient remain poorly understood. In this work, the SA formation was investigated using an oxidation flow reactor (OFR) with various concentration of OH radicals in Suwon downtown area during 6 similar to 21 July 2018. Inside the OFR, the OH radicals were equivalent to 0.9 similar to 5 days of integrated OH exposure at typical atmospheric conditions. The SA formation was observed to increase the potential production when compared with the concentration of primary aerosol (PA) in atmosphere. The average mass enhancement of OA, nitrate, sulfate, and ammonium upon aging inside OFR was 8.7 +/- 6.2, 6.6 +/- 4, 0.7 +/- 0.5, 2.7 +/- 1.6 mu g/m(3), respectively. The SA enhancement was decreased after production increases until similar to 1.8 days in this study and this trend was similar to other researches using OFR. The evolution of OA chemical composition in the ambient and OFR data was evolved f(44) increases and f(43) decreased with aging. After oxidation of OA with OH radical in OFR, the OA increased with increasing elemental O : C ratio up to similar to 1.5 (avg. 1.1 +/- 0.12). With increasing age, H : C ratio was decreased up to similar to 1.16 (avg. 1.32 +/- 0.08). the slope of O : C and H : C with all data of ambient and OFR was -0.54, and similar to trend observed in the atmosphere. The average carbon oxidation state (OSC) in OFR increased up to similar to 1.76 (avg. 0.89 +/- 0.28) with aging. The ratio of OA enhancement to Delta CO (background corrected) vs. predicted photochemical age was similar trend to previous studies and decreased to higher aging time. This study provide scientific research that can be used as establishing policies to reduce production of SA in the atmosphere.