Polycyclic aromatic hydrocarbons (PAHs) are environmental contaminants that continue to attract researchers' attention until these days due to their toxicity and their multisource emission. In this study, levels of 17 active molecules of PAHs were investigated in marine and continental Lebanese aquatic systems. The results showed that Lebanese seawater is more contaminated than several other sites on the Mediterranean Sea. On the marine side, the total concentration of PAHs ranges from 55.7 to 2683.8 ng L−1 in water and from 19.09 to 2025.03 ng g−1 in sediments. On the continental side, the total concentration ranges from 465.7 to 1399.9 ng L−1 in water and from 72.6 to 1074.7 ng g−1 in sediments presenting higher contamination and detection frequency than the marine sites. Pearson test was applied to determine the preference of PAHs toward one of the phases and showed that when the number of rings, the molecular mass and the log Ko/w increase, PAHs accumulate in sediments, and when the water solubility and the vapor pressure of PAHs increase, they tend to remain in the aqueous phase. Moreover, PAHs in Lebanese sediments were combustion-originated and resulted mainly from industrial sites set next to aquatic systems and heavy traffic especially along the Lebanese coastline. Regarding the toxicity effect, the use of the ERL/ERM approach revealed that few sites have individual PAHs levels that may occasionally cause biological adverse effects to benthic organisms; nevertheless, the ecosystem risk of PAHs in Lebanese sediments is low.< Leer menos