Distribution, source and ecological risk assessment of polycyclic aromatic hydrocarbons in cultivated land of Liuxin area, Xuzhou, China
Abstract
The spatial distribution, sources and ecological risk of 16 US EPA priority polycyclic aromatic hydrocarbons (PAHs) in surface soil from Liuxin area, Xuzhou, China was investigated in this study. Gas chromatography-mass spectrometry analysis revealed ΣPAH concentrations ranging from 115.66 to 373.53 ng ⋅g−1 (mean: 196.26 ng ⋅ g−1), with phenanthrene (Phe) exhibiting the highest mean concentration (51.18 ng ⋅ g−1). Spatial analysis demonstrated a southeast-to-northwest concentration gradient, with maximum PAH levels observed in southeastern zones. PAH composition showed dominance of low-molecular-weight species (2, 3 rings: 46.7%), followed by 5, 6 ring PAHs (28.3%), and 4-ring compounds (24.9%). Source apportionment using molecular diagnostic ratios and positive matrix factorization identified four primary contributors: coal-fired power generation & metallurgical emissions (34%), biomass combustion (31%), diesel fuel combustion/leakage (29%), traffic emissions (6%). Ecological risk assessment employing Dutch soil quality standards revealed localized exceedances in southeastern areas, particularly for fluoranthene (Fla) and Phe. However, toxic equivalency quotients remained low, with incremental lifetime cancer risks below 10−6 for all exposure pathways. These findings indicate that while PAH contamination warrants monitoring, current levels pose negligible carcinogenic risk to the local population.