Seasonal variation and emission sources of polycyclic aromatic hydrocarbons at a rural site in Ulsan

Abstract

Polycyclic aromatic hydrocarbons (PAHs) in gaseous and particulate phases (n = 188) were collected in Ulsan for four seasons (June 2013–May 2014) to understand the PAH seasonal variation and emission sources. The target compounds were 16 US-EPA PAHs, except for napthelane, acenapthylene, and acenapthene. Diagnostic ratios, principal component analysis, and positive matrix factorization were applied to identify seasonal emission sources of PAHs. The highest and lowest PAH concentrations were observed in winter and spring, respectively. In addition, concentration of the gaseous phase (4.11 ng/m3) was approximately two times higher than that of the particulate phase (2.55ng/m3). Contributions of the gaseous or 3-4 ring PAHs (i.e., Flu, Phe, and Ant) were dominant in summer, whereas those of the particulate or 5-6 ring PAHs (i.e., BkF, BaP, Ind, DahA, BghiP) were higher in winter. For source identification, the main PAH source in winter was coal combustion. Autumn and spring shared the similar PAH emission sources, including exhaust from transportation activities and biomass burning. Summer also had mixed PAH sources, including engine emissions and pyrogenic or coke ovens, originated from the industrial areas of Ulsan and affected the sampling site by the primary seasonal wind.