Distribution, sources, and toxicity assessment of polycyclic aromatic hydrocarbons in surface soils of the Gwangju City, Korea

Twenty-three individual polycyclic aromatic hydrocarbons (PAHs) including sixteen US Environmental Protection Agency (EPA) priority pollutants were analyzed in soil samples collected from twenty sites in the metropolitan city of Gwangju, Korea to investigate the levels of concentration, profiles, possible sources of PAHs, and a probabilistic human health risk. Soil samples (0-15 cm top layer) were collected, and the sampling sites were classified into two groups, including a school area and a residential area. Regardless of the sampling site, the concentrations of ∑23 PAHs ranged from 120 to 273 ng/g with an average value of 164 ng/g. The molecular distribution of PAHs reflected the similarity between school and residential areas in soil PAHs profile, and the PAHs could be from the same emission sources. High molecular weight PAHs (5- and 6-ring) were predominant in the soil samples, followed by 4-ring PAHs, while the fraction of 2-ring PAHs was the lowest. The total concentration of carcinogenic PAHs accounted for 54% of ∑16-EPA PAHs. Considering the different diagnostic ratios of PAHs, such as Flt/(Flt + Pyr), BaA/(BaA + Chr), Ant/(Ant + Phe), and IcdP/(IcdP + BghiP) and the principal component analysis results, the soil samples were likely attributed to mixed pyrogenic sources (coal and fossil fuel combustion, regardless of fuel types). The cancer risks for two age groups were < 10− 4, indicating no potential cancer risk.