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Article Type

Research Article

Subject Area

Marine Hazards

Abstract

Data on polycyclic aromatic hydrocarbon (PAH) concentrations in the Bay of Tobruk, Libya, remain scarce. The present study establishes a baseline for monitoring PAH levels, identifying their sources, and evaluating associated ecological risks. Seawater samples were collected from nine sites during the summer and winter seasons. The total concentrations of 16 priority PAHs ranged from 62.33 to 454.70 μg/L in summer (mean: 235.23 ± 152.37 μg/L) and from 79.26 to 473.36 μg/L in winter (mean: 253.85 ± 151.49 μg/L), reflecting substantial pollution. Seasonal trends suggest slightly reduced PAH levels in summer, potentially due to changes in industrial output, runoff patterns, and hydrodynamics. Diagnostic ratio analysis and principal component analysis (PCA) pointed to both petrogenic and pyrogenic origins. The ecological risk assessment categorized the bay as a medium to high-risk zone for marine life. These results highlight the urgent need for continuous environmental monitoring and targeted pollution mitigation strategies. This study assesses the ecological and human health risks posed by polycyclic aromatic hydrocarbons (PAHs) in the seawater of the Gulf of Tobruk using the Toxic Equivalency (TEQ) and Risk Quotient (RQ) approaches. TEQ values, calculated based on Toxic Equivalency Factors (TEFs) with benzo[a]pyrene (BaP) as the reference compound, exceeded international guideline thresholds at all sites, with the highest levels recorded during winter—suggesting increased contamination from industrial and port-related activities. The RQ analysis revealed that most individual PAHs, particularly high molecular weight compounds such as benzo[a]anthracene (BaA) and benzo[b]Fluoranthene (BbF), exhibited RQNCs values greater than 1.0, indicating a high ecological risk. Although RQMPCs values were generally below 1.0, the cumulative risk from ΣPAHs remained significantly elevated. These findings highlight serious ecological threats and potential risks to human health, especially in areas where seawater is used for desalination, emphasizing the need for strict environmental regulations, pollution source control, and ongoing monitoring efforts.

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