PAH bioaccumulation in two polluted sites along the eastern coast of the Red Sea, Saudi Arabia

Significant amounts of polycyclic aromatic hydrocarbons (PAHs) accumulate in specific habitats and organisms, such as mangroves and benthic organisms, due to the PAHs' direct attachment to sediments in the environment or the feeding activity of the organisms, especially in contaminated coastal areas. The present study investigates the effect of sewage effluents on the bioaccumulation of PAHs in two polluted sites along the coastal area of Jeddah city. PAH levels in the mangrove sediments, roots, and leaves ranged between 230.09 and 17.94, 32.79 and 409.86, and 111.14 and 795.2 ng/g, respectively, following the general trend of sediments < roots < leaves. Though all mangrove roots showed bioaccumulation factors (BAF(roots)) higher than 1, the leaves bioaccumulation factors (BAF(leaves)) exceeded 26, clearly indicating PAHs accumulated not only via a translocation pathway but also from the surrounding atmosphere. These results suggest that mangroves could serve as an in situ eco-friendly resource for the dissipation of PAHs in marine sediments and the atmosphere. Although higher levels of PAHs were detected in Al-Arbaeen Lagoon sediments (ranging between 89.18 and 1056.46 ng/g), lower levels of PAHs were observed in the gastropodLittorina Littorea(range 113.21-265.96 ng/g) in this area, with biota-sediment accumulation factors (BSAF) ranging from 0.23 to 2.10. Only one Al-Arbaeen site presented sediments with a petrogenic origin, with a BSAF value higher than 1 in the gastropod. Based on sediment quality guidelines, adverse biological effects should rarely occur at the studied sites under the present PAH levels.