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Oxygenated polycyclic aromatic hydrocarbons (OPAHs) are of increasing interest due to their high toxicity. Thirteen particulate PAHs and ten particulate OPAHs were analyzed by Gas Chromatography/Mass Spectrometry (GC/MS) in atmospheric particulate matter with aerodynamic diameters less than or equal to a nominal 2.5 μm (PM 2.5) for the period between May 2020 and January 2021 in Seoul, Republic of Korea. The mean concentration ten OPAHs (5.49 ± 2.40 ng/m3) was higher than that of thirteen PAHs (3.96 ± 3.36 ng/m3), respectively. The concentration of total OPAHs was high in winter (9.40 ± 2.50 ng/m3) and low in summer (3.58 ± 0.78 ng/m3), showing the same trend with PAHs (9.16 ± 3.30 ng/m3 in winter and 0.62 ± 0.15 ng/m3 in summer). When comparing this study results with the measurement results on 2006 in Seoul, PAHs concentration dropped by 68% while only 22% was reduced for OPAHs. It suggests either improvement of combustion technology, i.e., high temperature combustion process in the region or higher ambient oxidation reaction rates on 2020 than 2006. Major sources and their contributions of PAHs and OPAHs were identified based on correlation analysis and Positive Matrix Factorization (PMF) modeling. Two cases were carried. Case 1 is for source apportionment for PM 2.5 and case 2 is for OPAHs and PAHs. The number of factors or sources in the two cases was determined as 7 and 4, respectively. The results of the PMF modeling using diagnostic ratios (DRs) in case 1 identified 7 factors; secondary nitrate (23%), secondary sulfate (21%), vehicles (20%), biomass burning (16%), coal combustion (12%), waste incineration (5%), and OPAHs (5,12-NAQ) emission-related (3%). The PMF modeling results in case 2 revealed 4 factors; vehicles (36%), coal combustion (30%), biomass burning (25%), and OPAHs (5,12-NAQ) emission related (9%). Significant correlation between OPAHs and indicators of primary emission sources, and high contribution from sources with emission characteristics implied that most sources of OPAHs were heavily influenced by primary emissions rather than secondary formation. • 13 particulate PAHs and 10 OPAHs were analyzed in Seoul, Korea for four seasons. • The mean concentration of 10 OPAHs was higher than that of 13 PAHs. • OPAHs were heavily influenced by primary emissions rather than secondary formation. • OPAHs reduction ratios were lower than PAHs from 2006 to 2020. [ABSTRACT FROM AUTHOR]

Polycyclic aromatic hydrocarbons (PAHs) are primarily emitted into the atmosphere through anthropogenic activities and can be transported to receptor sites at varying distances. In this study, the atmospheric PAH deposition was investigated using a dry deposition plate (DDP) with Mylar, a dry deposition disk (DDD) with Velcro, a resin bulk deposition sampler (Resin-BDS), and a water bulk deposition sampler (Water-BDS) in Ulsan, South Korea, during May–October 2013. Additionally, ambient PAH concentrations were monitored using high-volume air samplers. The mean deposition fluxes of Σ 13 PAHs were 8.62 ± 1.44, 36.9 ± 6.81, 56.9 ± 9.74, and 63.8 ± 8.04 μg/m2/d for the DDP, DDD, Resin-BDS, and Water-BDS, respectively. The DDD was more effective than the DDP because it could collect high molecular weight (HMW) PAHs from dry deposition, which are more toxic than low molecular weight PAHs. The Water-BDS had the highest fluxes of Σ 13 PAHs; however, the Resin-BDS may be more suitable for collecting HMW PAHs from both dry and wet deposition due to relatively constant values for the deposition velocity of PAHs. Furthermore, the PAH fluxes in the Resin-BDS samples were significantly positively correlated with the gaseous and total (gaseous + particulate) concentrations of ambient PAHs. Hence, the fluxes obtained by the Resin-BDS were further used to apply principal component analysis, multiple linear regression, and backward air trajectory simultaneously to identify the emission sources of the deposited PAHs. The results indicate that the combustion of fossil fuels and biomass was the major source. In particular, the industrial complexes using petroleum and coal on the city's east coast and vehicular exhausts were the main local sources. Meanwhile, long-range sources may be forest fires, harbors, and industrial activities in nearby countries. Our study suggests that BDS, considering both dry and wet deposition, can be selectively used for research on PAH deposition. [Display omitted] • The performance of four deposition samplers for ambient PAHs was evaluated. • Dry samplers using Mylar and Velcro collected mostly coarse particle-bound PAHs. • The water and resin bulk samplers were suitable to study both dry and wet deposition. • The resin bulk sampler collected more toxic PAHs with a constant deposition velocity. • The burning of fossil fuels and biomass was a major source of the deposited PAHs. [ABSTRACT FROM AUTHOR]