The silent drift of PAHs in the East China Sea: Sources, ecological risks, and remediation

This review synthesizes two decades (2004–2024) of research on polycyclic aromatic hydrocarbons (PAHs) in the East China Sea (ECS), focusing on their occurrence, sources, risks, and remediation. Using a PICO-guided systematic approach, we compiled data across seawater, sediments, biota, and food webs. PAH concentrations in seawater range from non-detectable to 816.9 ng/L, while sediments span 1.7–3047.1 ng/g, with ecological risk quotients generally indicating low to moderate risk (RQ ≤ 1). Biota exhibit PAH levels up to 3500 ng/g, revealing notable bio-accumulation, and benzo[ a ]pyrene Toxicity Equivalency Quotient (TEQ BaP ) values from 1960 to 2020 sediment cores (0.34–5.4 ng/g) remain far below the 600 ng/g toxicity threshold, suggesting limited carcinogenic pressure at the sediment level. Nevertheless, seafood-based excess cancer risk (ECR) values between 1.10E-7 and 5.08E-5, with some exceeding 1.0E-6, point to potential long-term human health concerns. Source apportionment indicates that oil spills, petroleum and coal combustion, steel production, and other industrial emissions are the dominant contributors, with spatial hotspots linked to high population density and GDP. The review also evaluates remediation options—including bio-remediation, adsorption, advanced oxidation processes, sediment capping, and photo-degradation—and discusses their feasibility under ECS-specific hydrodynamic and ecological conditions. Overall, the ECS currently exhibits low to moderate PAH pollution on both regional and global scales; however, strengthened monitoring, locally adapted risk assessment frameworks, and targeted remediation strategies remain essential.