Valentina Baravelli

Distribution of alternant and non-alternant polycyclic aromatic hydrocarbons in sediments and clams of the Pialassa Baiona Lagoon (Ravenna, Italy)

The distribution of polycyclic aromatic hydrocarbons (PAHs) in surface sediments and clams (Tapes philippinarum) in a Ramsar site (Pialassa Baiona Lagoon, Italy) was investigated by high-performance liquid chromatography (HPLC) with fluorescence detection and gas chromatography–mass spectrometry (GC–MS). Surface sediments exhibited a variable degree of PAH contamination, with high concentration values (>100 mg/kg) in the southern area, in the proximity of the industrial district, and much lower values (<1 mg/kg) in the northern area. The molecular distribution of PAHs was very similar throughout the Lagoon, confirming previous studies indicating a common source of contamination attributed to partial combustion of methane. With the exception of the northernmost site, the molecular distribution was characterized by high levels of non-alternant PAHs, among which the probable mutagenic cyclopenta[cd]pyrene was the predominant species. PAH levels in tissues of clams collected in the polluted area, where fishing is forbidden, and in the less-polluted permitted area were similar (∼0.1 mg/kg dry weight). In both sites, the PAH distribution in clams was different from that observed in sediments. In particular, the levels of non-alternant PAHs with an external cyclopenta ring (CP-PAHs), acenaphtylene and cyclopenta[cd]pyrene, were remarkably lowered in clams with respect to sediments, probably as a result of their chemical/biological reactivity.