Polycyclic aromatic hydrocarbons pollution in sediments: distribution and sources in a lagoon system (Orbetello, Central Italy)

The presence, distribution and origin of 16 US EPA polycyclic aromatic hydrocarbons (PAHs) in the surface sediments of Orbetello lagoon (Tuscany, Italy) were investigated by high pressure liquid chromatography (HPLC). PAH concentrations in the sediments (Σ16PAHs) ranged from 0.92 to 279.38 ng/g of dry matrix, indicating low PAHs pollution. A prevalence of high molecular weight PAHs was observed (>90% of Σ16PAHs) with a considerable predominance of 4-rings PAHs; fluoranthene was the dominant compound. A comparison with other studies of total PAHs suggests that the levels are within the concentration ranges already reported by the other authors. Total PAH concentrations measured in the studied area indicate a relatively clean environment when compared to values reported by the literature for Mediterranean lagoons. Molecular ratios were calculated in order to estimate PAH origin and transport from sources. As indicated by the Phen/Ant and Flu/Pyr molar ratio, the main source of PAHs is pyrolityc