Environ Monit Assess (2011) 174:445–459 DOI 10.1007/s10661-010-1469-5 Polycyclic aromatic hydrocarbons and polychlorinated biphenyls in the harbour of Naples (Southern Italy): time and spatial distribution patterns Maria Luisa Feo · Mario Sprovieri · Serena Gherardi · Simone Sammartino · Ennio Marsella Received: 19 June 2009 / Accepted: 7 April 2010 / Published online: 4 May 2010 © Springer Science+Business Media B.V. 2010 Abstract Seventeen parent polycyclic aromatic hydrocarbons (PAHs) and 38 congeners of poly- chlorinated biphenyls were measured at five different sediment depths (between the surface and ∼300 cm below the seafloor) at 160 sites in Naples harbour. Total PAH (PAH) and PCB (PCB) concentrations ranged between 0.012–21.73 − nd 0.001–0.222 mg kg −1 , respec- tively. For PAHs, an evident and progressive decrease in concentration with depth documents the effects of a more intense anthropic impact of this group of pollutants in the recent pe- riod. A selected number of PAH isomer pairs (phenanthrene/anthracene, fluoranthene/pyrene and benzo(a)anthracene/crysene) were used to distinguish between contaminants of pyrolitic and petrogenic origin. More than 90% of PAHs present at the different depths of the studied sediments indicate pyrolitic industrial origins. On the other hand, relatively high concentrations of three- and four-ring PAHs suggest a limited con- tribution of vehicular emissions to the contami- M. L. Feo (B ) · S. Gherardi · S. Sammartino · E. Marsella IAMC–CNR, Calata Porta di Massa, Interno Porto di Napoli, 80133, Naples, Italy e-mail: mlfqam@cid.csic.es M. Sprovieri IAMC–CNR, Campobello di Mazara (Tp), Italy nation of sediments. An unexpected and system- atic increase of PCB concentration, exceeding values approved by international regulations, was found in the studied sediments, testifying to the uncontrolled discharge to the studied area from industrial and commercial activity on nearby land. Ecotoxicological risk levels calculated for PAHs suggests a relatively elevated level of toxicity in surface sediments decreasing with depth and very low toxicity values associated to PCB toxicity. Keywords PAH analysis · PCB analysis · Marine sediments · PAH isomer ratio · Ecotoxicological risk Introduction Polycyclic aromatic hydrocarbons (PAHs), iden- tified by the US Environmental Protection Agency (US EPA) as priority pollutants (Keith and Telliard 1979), are a group of organic com- pounds which include the largest known class of chemical carcinogens and mutagens. PAHs occur in the environment as a result of natural events such as forest fires and/or in relation to anthro- pogenic impact mainly associated to urban and industrial activities. The incomplete combustion of organic matter at high temperature is the main source of PAHs. The adverse biological effects of PAHs include acute toxicity, developmental and