Suspended particle-associated PAHs in the open eastern Mediterranean Sea: Occurrence, sources and processes affecting their distribution patterns

In this study, we report spatial and vertical profiles of suspended particle-associated polycyclic aromatic hydrocarbons (PAHs) collected from nine stations across the open eastern Mediterranean Sea (Ionian and northwestern Levantine Seas - EMS) corresponding to various water column depths (1008-4087 m). Concentrations of total determined PAHs (sum of 16 compounds) ranged between 90.6 and 918 pg L− 1 comparable to those reported for unpolluted open/deep-sea settings. Values recorded for particles in mesopelagic and bathypelagic waters were fairly comparable to those measured in surface particulate matter, implying that deep EMS waters constitute a pollutant depository. The occurrence of the studied PAHs is attributed to a mixed contribution from both fossil and pyrolytic compounds, while results are indicative of chronic petrogenic pollution in the study area, with a prominent fossil PAHs signal in deep waters. The residence time of suspended particle-associated PAHs in the water column (considering only particle settling) was estimated at approximately 30 y, while their spatial and vertical distribution patterns exhibited distinct characteristics amongst the studied sites with their overall occurrence and fate being controlled by both biogeochemical processes and water mass circulation patterns.