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The spatial and temporal distribution of aliphatic and polycyclic aromatic hydrocarbons (PAHs) and sulfur/oxygen derivatives in sediments from the NW Mediterranean basin were investigated. Along the Continental Shelf and slope, an unresolved complex mixture (UCM) of aliphatic hydrocarbons and alkylated PAHs, indicative of petrogenic inputs, were predominant. Long-chain n-alkanes derived from terrestrial plant waxes (n-C27, n-C29, and n-C31) and parent PAHs, which are typical of high-temperature combustion processes, were evenly distributed in the whole basin and largely prevailing in the deepest areas. Perylene, a geochemically derived PAH, was found highly abundant in the areas influenced by river discharges. The highest anthropogenic hydrocarbon inputs were found near the cities of Marseille and Barcelona, being the contribution of the Rhone River ca. 25 times higher than that of the Ebro. Fluxes of PAHs in the deep basin were consistent with a predominant atmospheric input. These results account for an accumulation rate in the NW Mediterranean sediments of 2700 t/year of petrogenic unresolved hydrocarbons (UCM) and 60 t/year of pyrolytic PAHs. Analyses of dated sediment cores from the Rhone and Ebro prodeltas exhibited maximum accumulation rates of PAHs in the 1920−1940 and the 1975−1990 periods, although with a steep decrease since 1985 in the Rhone area.

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Hydrocarbons and polychlorinated biphenyls (PCBs) were determined in tissues of marine organisms (mussels, crabs, benthic, and pelagic fishes) from six sites along the Catalan Coast (Western Mediterranean). Both aliphatic and aromatic hydrocarbons as well as seven PCB congeners (PCB-28, 52, 101, 118, 138, 153, 180) were quantified and differences in concentrations interpreted in terms of geographical distribution, trophic level, and biological cycle of the organisms. The bioaccumulation patterns of the different chemicals varied substantially. Hydrocarbons were metabolized along the food web, contrarily to PCBs, which exhibited a higher bioaccumulation in fishes. Considering 36 peaks of the GC-ECD profiles, encompassing 40 PCB congeners, from tri- to octa-chlorinated isomers, a relative enrichment was observed in the higher chlorinated ones from: mussels < mullets < tuna < crabs. The slopes of the correlation plots between the bioconcentration factor (log BCF) and the octanol-water partition coefficient (log K(ow)) for the different PCB congeners reflected the feeding behavior of the organisms, mussels exhibiting a preferential uptake by direct partitioning from water, and mullets and crabs with a certain uptake from sediments. Increasing metabolic degradation following a similar trend among species was also observed for aromatic hydrocarbons and PCB congeners containing meta and para vicinal H-atoms. Accordingly, mussels and benthic fishes were the best indicators of coastal pollution in the water column and sediments, respectively, although the above features should not be overlooked in the interpretation of biomonitoring data.