Shipping-related air pollution at Busan Port: The unceasing threat of black carbon

Busan Port ranks among the top ten most air-polluted ports globally, yet the chemical characteristics of its air pollution, specifically the compositions and sources of aerosols, including black carbon (BC) have not been thoroughly studied. To assess the emission characteristics, four comprehensive air monitoring campaigns were conducted seasonally from fall 2020 to summer 2021. While mass concentrations of aerosol chemical species analyzed using the high-resolution time-of-flight aerosol mass spectrometer showed significant seasonal variations (3.6-11.4 µg·m^-3), BC exhibited persistent concentrations throughout all seasons (1.9-2.2 µg·m^-3). On average, BC constituted a staggering 26.5 % of the total non-refractory sub-micron aerosol mass concentrations. A positive matrix factorization model used to identify organic aerosol (OA) sources revealed six sources: two hydrocarbon-like OA, three oxygenated OA, and one biomass burning OA. Most of these sources were associated with shipping-related emissions at Busan Port. Spatial analysis of the elemental carbon revealed higher concentrations in port areas (1.2-1.5 µg·m^-3) and surrounding areas (0.6-1.0 µg·m^-3), compared to other urban cities (0.5-0.6 µg·m^-3). This observation suggests that carbonaceous particles, along with persistent shipping-related OA emissions, are likely to disperse and impact air quality in adjacent urban areas, potentially posing health hazards.