Concentrations, Source and Risk Assessment of Polycyclic Aromatic Hydrocarbons in Soils from Midway Atoll, North Pacific Ocean

This study was designed to determine concentrations of polycyclic aromatic hydrocarbons (PAHs) in soil samples collected from Midway Atoll and evaluate their potential risks to human health. The total concentrations of 16 PAHs ranged from 3.55 to 3200 µg kg(−1) with a mean concentration of 198 µg kg(−1). Higher molecular weight PAHs (4–6 ring PAHs) dominated the PAH profiles, accounting for 83.3% of total PAH mass. PAH diagnostic ratio analysis indicated that primary sources of PAHs in Midway Atoll could be combustion. The benzo[a]pyrene equivalent concentration (BaP(eq)) in most of the study area (86.5%) was less than 40 µg kg(−1) BaP(eq) and total incremental lifetime cancer risks of PAHs ranged from 1.00×10(−10) to 9.20×10(−6) with a median value of 1.24×10(−7), indicating a minor carcinogenic risk of PAHs in Midway Atoll.