Crude vs. condensate: Contrasting pollution trajectories and management implications from two major oil spills in China's marine ecosystems.

Oil spills increasingly imperil China's marine ecosystems, with the Sanchi (condensate oil) and Dalian (crude oil) incidents exhibiting distinct pollution dynamics. This study integrates spatial analysis, chemometric source apportionment (HCA-PCA), and ecological risk assessment to compare polycyclic aromatic hydrocarbons (PAHs) contamination in surface sediments. Results reveal Dalian's PAHs cluster in industrial zones, likely from historical combustion sources, while Sanchi shows radial declines from the wreck, reflecting condensate oil volatilization. Source analysis identifies uniform combustion origins for Dalian and mixed inputs from heavy fuel oil weathering and combustion for Sanchi. Despite overall PAHs levels below ER-L thresholds, Sanchi's heavy fuel oil-derived 5-6 ring PAHs require continuous monitoring. Toxic equivalent (TEQ_BaP) analysis highlights site-specific risks, underscoring the need to prioritize TEQ metrics over total PAHs concentrations for accurate risk assessment and targeted marine environmental management. The complex interplay between the spill - derived PAHs and pre - existing industrial pollution implies that remediation efforts must consider both acute and chronic contamination sources.