Polycyclic Aromatic Hydrocarbon Degradation and Sorption Parameters in Coastal and Open-Sea Sediment

This work describes the experimental determination of the major degradation and sorption parameters of polycyclic aromatic hydrocarbons (PAHs) in a sensitive marine environment, the Northern Adriatic Sea (Mediterranean Sea). The persistence and sorption of complex PAH mixtures were analysed in the laboratory in conditions mimicking open-sea and coastal sediments, which differ in grain size and organic carbon content and are characterized by different oceanographic conditions including abiotic influences. The study investigated how sediment type and texture and salinity, temperature and solar irradiation conditions affect the partitioning of low molecular weight (LMW) and high molecular weight (HMW) PAHs into aqueous and solid phase, which critically influence their behaviour. With regard to the change from offshore to coastal conditions, HMW PAHs were found to be more sensitive to the increased salinity (from 21 to <?37 parts per thousand), whereas LMW PHAs were more sensitive to the temperature increase (from 11 to 22°C). HMW PAHs were more affected by sediment type changes in terms of distribution coefficient (K <inf>d</inf>). Since the physicochemical properties of organic pollutants affect their distribution, transport, bioavailability and toxicity, analysing the accumulation and persistence of dissolved pollutants can provide useful information for environmental risk assessment and management.