Seasonal characteristics of particulate polycyclic aromatic hydrocarbons (PAHs) in a petrochemical and oil refinery industrial area on the west coast of South Korea

Abstract

The Daesan industrial complex is one of the largest petrochemical and oil refinery industrial complexes in South Korea, which is believed to be a major source of polycyclic aromatic hydrocarbons (PAHs). Total suspended particle (TSP) samples (n = 84) were seasonally collected at two industrial sites and one residential site, and 19 PAHs were analyzed. Concentrations of individual PAHs ranged from 0.01 to 2.52 ng/m3, and annual mean concentrations of Σ19 PAHs at Sites 1, 2, and 3 were 5.88, 4.52, and 5.08 ng/m3, respectively. The concentrations of Σ19 PAHs in warm seasons (spring and summer) were lower than those in cold seasons (autumn and winter). Annual fractions of low molecular weight (LMW)-PAHs (2–3 rings, 12.1%) and high molecular weight (HMW)-PAHs (4–7 rings, 87.9%) indicated a strong contribution of thermal processes. Significant correlations between Σ19 PAHs and TSP (p < 0.01) at all the sampling sites were observed, implying that increased TSP levels were responsible for elevated levels of PAHs. There were strong seasonal variations in the profiles of PAHs, and they were clearly reflected in the results of the principal component analysis. Diagnostic ratios and backward air trajectories suggested seasonal variations in the contribution of local emissions and long-range transport. The diagnostic ratios suggested that mixed sources were dominant in cold seasons, while coal/biomass burning and non-traffic sources were prevailing in warm seasons. BeP/BaP ratios indicated that local emissions were major sources compared with long-range transport except for summer. Backward air trajectories in winter suggested the influence of long-range transport, but local emissions were more important in this study area.