Seasonal variation, source identification, and health risk assessment of atmospheric polycyclic aromatic hydrocarbons (PAHs) in Ulsan, South Korea

Abstract

however, other more toxic PAHs have been also found in ambient air (i.e., dibenz[a,i]pyrene (DbaiP), dibenz[a,h]pyrene (DbahP), and dibenz[a,l]pyrene (DbalP)). In this study, gaseous and particulate phases of 21 atmospheric PAHs were collected in three seasons (December 2013–August 2014) at a residential site in Ulsan, South Korea. The samples (n=64) were extracted by Soxhlet extractors, cleaned up using silica gel columns, and then analyzed using a gas chromatograph/mass spectrometer (GC/MS). The mean Σ21 PAH concentrations were 13.06 ng/m3, 7.67 ng/m3, and 6.03 ng/m3 in winter, spring, and summer, respectively. The gaseous concentrations of Σ21 PAHs (mean: 7.39 ng/m3) were higher than the particulate ones (mean: 2.70 ng/m3). The contribution of the Σ8 PAHs which are not listed as the US EPA priority PAHs to the Σ21 PAH were 5.21%, and they were mostly partitioned in the particulate phase. The particulate PAHs (4-, 5-, and 6-ring species) were dominant in winter, whereas the gaseous PAHs (3- and 4-ring species) were dominant in summer. In order to identify the emission sources of PAHs, diagnostic ratios, principle component analysis, and a hybrid receptor model (i.e., concentration weighted trajectory) were used. As a result, pyrogenic sources (e.g., wood/coal and natural gas combustion) were the primary sources in winter. Petrogenic sources and petrogenic combustion were dominant in summer, reflecting that PAHs could be transported from industrial areas by seasonal winds. In spring, PAHs were emitted by both petrogenic and pyrogenic sources. In addition, PAHs could be affected by vehicle emission in all seasons. Moreover, the concentration weighted trajectory revealed that PAHs in winter and spring could be contributed by PAHs emitted from regional areas (i.e., China and North Korea). The exposure-risk probability distribution calculated using Monte Carlo simulation suggested that the cancer risks of Σ21 PAHs and Σ13 PAHs did not exceed the guideline of the US EPA (10-6). However, high TEFs of DbaiP and DbahP contributed to the increased cancer risk of Σ21 PAHs than that of Σ13 PAHs although they showed low concentrations in the ambient air. Therefore, it is necessary to investigate for various kinds of PAHs and evaluate their health impact. This is a preliminary study for monitoring and health risk assessment of 21 PAHs in South Korea.

Polycyclic aromatic hydrocarbons (PAHs) are well-known contaminants due to their toxicity and high emission from incomplete combustion of organic materials. Previous studies mostly focused on the United States Environment Protection Agency priority 16 PAHs