[A-AS11] Atmospheric Chemistry

[AAS11-P08] Analysis of Behavior for Primary and Secondary Organic Carbon in PM2.5 at Industrial/Urban Site in Korea

*Sujung Lee¹, Giyeol Lee¹, Yongjoo Choi¹, Kwangyul Lee², Pilho Kim², Su-Hyun Shin², Saehee Lim³ (1.Department of Environmental Sciences, Hankuk University of Foreign Studies, Yongin, South Korea, 2.Air Quality Environment Research Division, Climate and Air Quality Research Department, National Institute of Environmental Research, Incheon, Republic of Korea, 3.Department of Environmental Engineering, Chungnam National University)

Keywords:Carbonaceous aerosols, POC, SOC, OC/EC ratio

Carbonaceous aerosols are composed of organic carbon (OC) and elemental carbon (EC). OC can be directly emitted from combustion sources (primary organic carbon, POC) or formed through photochemical processes (secondary organic carbon, SOC). Despite it is important to identify the emission source and chemical process for OC according to atmospheric conditions, there is still insufficient information for concentrations and contribution of POC and SOC by accurate assessment. In this study, hourly OC and EC in PM_2.5 concentrations were measured from 2021 to 2023 at Gyeonggi Air Quality Research Center (37.31°N, 126.80°E) located in Ansan, Korea to investigate the temporal variations of POC and SOC. OC and EC were determined using a Sunset OC/EC thermal optical transmittance (TOT) analyzer (Sunset Laboratory Inc., USA) based on National Institute for Occupational Safety and Health (NIOSH) protocol. SOC and POC were estimated using the EC tracer method (Turpin and Huntzicker et al., 1991) and the minimum R² method (MRS; Wu and Yu, 2016). POC peaked at 08:00 while SOC showed the lowest concentration indicating the effect of rush hour and low PBL height. The seasonal SOC/OC ratio was the highest in summer resulting in the activation of photochemical process along with the increase solar radiation. We will conduct a more detailed analysis of the temporal variations in SOC and POC.