Origin and Bioavailability of PAHs in the Mediterranean Sea from Mussel and Sediment Records

The distribution of selected polycyclic aromatic hydrocarbons (PAHs) in surface sediments and in mussels (Mytilus galloprovincialis) of the western Mediterranean Sea (French, Spanish and Balearic coasts) has been investigated by gas chromatography–mass spectrometry (GC–MS). The sediment PAH concentrations ranged from less than 1 to 8500 ng g−1. The most contaminated sediments have been sampled in harbours while the mean concentration of the Balearic Island sediments, far away from contamination sources, is low (≈30 ng g−1). The main pollution source is pyrolytic with an overimposition of petrogenic/diagenetic PAHs in a few sediments. The mussels are contaminated at very low levels (25–80 ng g−1) with the exception of those collected in two harbours (Port Vendres and Barcelona) and whose tissue PAH content is medium. In the Mediterranean Sea, the bioavailability from sediment of adsorbed hydrophobic organic compounds such as PAHs seems to be mainly governed by the origin of the contaminants. Pyrolytic compounds (penta- and hexa-aromatics) are not readily available. In contrast, petroleum hydrocarbons (some tetra-aromatics, methylated PAHs) are accumulated by mussels to a great extent.