Seasonal characteristics of submicron aerosols in the coastal atmosphere of southeastern Korea: Influence of urban-port outflow

The impacts of emissions from major urban-port complexes on the coastal marine atmosphere remain insufficiently constrained. Seasonal measurements of submicron aerosol mass concentrations, chemical composition, and particle size distributions were conducted at Geoje Island, a coastal receptor site southwest of Busan, South Korea, from winter 2021 to fall 2022 using a high-resolution time-of-flight aerosol mass spectrometer. PM 1 concentrations varied from 4.23 to 10.0 μg·m −3 , reflecting seasonal transport patterns. Positive matrix factorization resolved five organic aerosol sources, including hydrocarbon-like, oxidized primary organic aerosol (OPOA), two oxygenated, and biomass-burning factors. Frequent ultrafine particle growth events occurred, particularly in fall, when OPOA contributed up to 36%, coinciding with elevated black carbon and northeasterly transport from the Busan Port region. These results indicate that port-influenced air masses were associated with changes in aerosol compositions and enhanced ultrafine particle occurrence and growth at downwind coastal receptor sites.