During the Yellow Sea–Air Quality (YES-AQ) campaign from 2020 to 2023 and the Airborne and Satellite Investigation of Asian Air Quality (ASIA-AQ) campaign in 2024, PM10 and PM2.5 samples were collected over the Yellow Sea using the research vessel Gisang 1. Thirteen water-soluble ions (NH4+ + + 2+, Mg2+, SO42-, NO3-, , Na , K , Ca Cl , F , HCOO , CH COO , CH SO -- - 3 - 3 3 -, C2O42-) were analyzed, and Principal Component Analysis (PCA) combined with backward trajectory analysis was applied to evaluate size-resolved chemical composition and source contributions. The coarse fraction (PM10–2.5) was dominated by soil-derived species (nss-Ca2+, CO32-) and sea salt (Na , Cl ), while +- the fine fraction (PM2.5) was characterized by secondary inorganic aerosols such as NO3-, nss-SO42-, and NH4+. In March 2021, an intense Asian dust event was observed, with PM10 mass concentrations exceeding the dust warning threshold of 900 µg/m³. This episode featured a simultaneous increase in soil components and NO3- in the coarse mode, indicating a strong influence of natural sources. In contrast, in March 2023, both submicron particles (<1.0 µm) and coarse particles (>2.0 µm) increased, with fine particles showing higher concentrations, representing a mixed pollution event involving dust and anthropogenic aerosols. PCA results identified seven major source types: soil, sea salt, secondary inorganic aerosols, biomass burning, plant growth, marine phytoplankton, and secondary organic aerosols. On average, coarse particles were largely influenced by soil–biomass burning mixtures (45.6%) and sea salt (26.8%), whereas fine particles were dominated by secondary inorganic aerosols (24.2%) and biomass burning (9.9%). Cluster analysis of backward trajectories indicated that air masses from eastern and northern China, Mongolia, Central Asia, Russia, and the Korean Peninsula affected the Yellow Sea, with eastern China air masses accounting for the largest fraction (28.7%). Among them, Central Asian air masses exhibited the highest total ion concentration (24.7 µg/m³), enriched in NO3-, Cl , nss-SO - 4 2-, and Na+, suggesting the combined influence of dust, sea salt, and secondary aerosols during long-range transport.