Atmospheric polycyclic aromatic hydrocarbon concentrations in a semi-urban site: temporal variation, risk assessment, source identification, and estimation of levels in diverse environments

This study evaluates atmospheric polycyclic aromatic hydrocarbon (PAH) concentrations in a semi-urban area, Görükle, Turkey, from June 2021 to February 2022. The average concentration of ∑16 PAHs was 24.85 ± 19.16 ng/m3, ranging from 6.70 to 59.11 ng/m3. Seasonal variations were observed, with winter concentrations approximately five times higher than those in summer, driven by increased residential heating emissions and adverse meteorological effects. The results were compared to literature values, revealing lower PAH levels than those found in other urban and industrial areas. Meteorological factors were statistically analyzed. Polycyclic aromatic hydrocarbon concentrations exhibited an inverse relationship with temperature and mixing height, while relative humidity showed a positive linear correlation. The study also estimated PAH concentrations in various environmental media using gas-particle partitioning and equilibrium models. The concentrations of PAHs in the particulate phase were minimal, suggesting that most PAHs were present in the gas phase. Additionally, the equilibrium concentrations of PAHs in soil, leaves, bark, and water were modeled, emphasizing the accumulation of heavier PAHs in these media yet 2- and 3-ring PAHs were predominant in the ambient air samples. Source apportionment and principal component analysis studies identified vehicle emissions and combustion for heating purposes as the primary sources of pollution. However, air mass trajectory analysis indicated contributions from Kocaeli, an area with significant industrial activity. The cancer risk assessment yielded low risks for both adults and children.