PAHs in subtropical estuarine sediments of western Beibu Gulf, China: distribution, source apportionment, and ecological risk assessment

Polycyclic aromatic hydrocarbons (PAHs) in marine sediments pose potential ecological risks, and systematic investigations of their distribution, sources, and risks are critical for coastal environmental management.This study systematically investigates the distribution, source apportionment, and ecological risks of 16 polycyclic aromatic hydrocarbons (PAHs) in surface sediments of the western Beibu Gulf, Guangxi. The total PAH concentrations range from 27.65 to 94.96 ng·g⁻¹, with an average of 61.67 ng·g⁻¹, which indicates low-to-moderate pollution. Spatial variations are significant, influenced by riverine inputs and coastal development intensity, with 3-ring (60.35%) and 4-ring (17.84%) compounds dominating. Diagnostic ratio analysis and principal component analysis (PCA) reveal that PAHs primarily originate from coal and biomass combustion, with local petroleum contributions. Risk assessments show that all PAH concentrations are below the Effect Range Low (ERL) of sediment quality guidelines. The toxic equivalent quotient (TEQ BaP ) averages 0.991 ng·g⁻¹, and RQ ΣPAHs indicates low ecological risk, though potential accumulation of high-ring PAHs in industrial estuaries requires attention. These findings provide a scientific basis for PAH pollution control and sustainable marine management in the Beibu Gulf.