Polycyclic aromatic hydrocarbons, polychlorinated biphenyls and trace metals in sediments from a coastal lagoon (northern Adriatic, Italy)

Surface sediments (0 - 5 cm) were analysed to provide information on levels, spatial trends, and sources of the 16 USEPA polycyclic aromatic hydrocarbons (PAH), 15 polychlorinated biphenyls (PCBs), and trace metals (copper, chromium, mercury, nickel and zinc) in channel and wetland habitats of Pialassa Baiona lagoon (Italy). The highest levels of PAHs , PCBs and Hg (3,032 - 87,150, n.d. – 3,908 ug/kg, and 1.3 - 191 mg kg-1) were mainly found at channel habitats close to industrial sources. Pyrogenic PAH inputs were significant, with a predominance of four-ring PAHs and combustion-related PAHs in both channel and wetland habitats. Among PCB congeners, chlorination class profiles shows that penta- and hexa-chlorinated PCBs are the most prevalent homologues accounting for approximately 33 and 47 % of the total PCB concentrations in channel sediments. Total TEQs of potentially carcinogenic PAHs varied from 348 to 7879 ug kg-1 and from 4.3 to 235 ug kg-1 in channel and wetland sediments; calculated TEQs for dioxin.like PCB congeners at channel habitats ranged from n.d. to 86.7 ug kg-1. Comparison of PAHs, PCBs, and metal levels with Sediments Quality Guidelines (SQGs) suggests that more concern should be given to the southern area of the lagoon for potential risks of carcinogenic PAHs, dioxin-like PCBs and mercury.