Polycyclic aromatic hydrocarbons in surficial coastal sediments of the Ligurian Sea R.M. Bertolotto a , F. Ghioni b , M. Frignani c, * , D. Alvarado-Aguilar c , L.G. Bellucci c , C. Cuneo a , M.R. Picca a , E. Gollo b a Agenzia Regionale Protezione Ambiente Ligure (ARPAL), Direzione Scientifica, P.za Vittoria 15, 16121 Genova, Italy b Agenzia Regionale Protezione Ambiente Ligure (ARPAL), Dipartimento di Genova, V. Montesano 5, 16121 Genova, Italy c Istituto di Scienze Marine, Sezione di Geologia Marina, CNR, Via Gobetti 101, 40129 Bologna, Italy Keywords: Polycyclic aromatic hydrocarbons; Sediments; Sources; Ligurian Sea Polycyclic aromatic hydrocarbons (PAHs) are a class of ubiquitous organic compounds with two to seven condensed aromatic rings. Common characteristics of PAHs are very low solubility in water, good affinity for manyorganicsolvents,lowvolatility,exceptforthevery low molecular weight congeners, and a tendency to ad- sorb onto sediment particles. Sixteen PAHs are consi- dered by the US EPA as priority micropollutants because of their carcinogenic and mutagenic properties (Arcos and Argus, 1975). PAHs have numerous sources, both natural and an- thropogenic. They are naturally present in tar, bitumen and oil. Furthermore, certain compounds such as per- ylene and retene are thought to be produced diageneti- cally (Wakeham et al., 1980b). Anthropogenic sources include combustion of fossil fuels, waste incineration and production of coke, carbon black, coal tar pitch, asphalt and petroleum cracking (Hallet and Brecher, 1984; and references therein; McCready et al., 2000). Spillageoffossilfuelsisanothercommonanthropogenic source of PAHs. Pyrolytic and petrogenic sources are known to generate substantially different PAH assem- blages. In general, combustion products are dominated byrelativelyhighmolecularweight(HMW)compounds with four condensed rings or more. In contrast, mono-, bi- and tricyclic aromatic compounds (LMW) are most abundantinfossilfuels(PrahlandCarpenter,1983)and these PAH mixtures contain high levels of alkylated congeners. Much work has been dedicated to the as- sessment of PAH contamination levels coupled to the identification of the sources through study of sediments (e.g. Youngblood and Blumer, 1975; Wakeham et al., 1980a; Canton and Grimalt, 1992; Soclo et al., 2000; McCreadyetal.,2000).Thepurposeofthisstudywasto determinedistribution,degreeofcontamination,sources and potential toxicological significance of PAHs in surficial sediments along the coast of the Ligurian Sea. The Ligurian Sea belongs to the northern part of the western Mediterranean. The coastal morphology of the Liguria Region is variable, and frequently cliffs drop sheer to the sea. The limited width of the coastal zone determines a gathering of the urban areas with a conse- quentconcentrationofbothcivilandindustrialpresence inanarrowbuthighlypopulatedterritory.Inparticular Genova, but also other cities, have a long history of in- dustrialandharbouractivities,whereaslongtractsofthe coast are dedicated to tourism. The circulation of the Ligurian Sea is dominated by surface and intermediate currents that follow a cyclonic circulation. However, local circulation is responsible for the dispersion of sediment material along the coast, and these longshore currents often cause an eastward oriented transport. Samplingwascarriedoutin1998at75stationsinthe 25 localities shown in Fig. 1. Three sediment samples were collected along transects at 500, 700 and 1000 m from the shoreline using a Van Veen grab, whose pen- etration was typically 10–20 cm. The topmost sediment (2cm)wascarefullyremovedwithastainlesssteelspoon and transferred to glass screw cap jars with aluminium foil lid liners. The sediment samples were stored at )18 °C before analysis. PAHs determined included naphthalene (Na), 1-methylnaphthalene (1mNa), 2-methylnaphthalene (2mNa), fluorene (Fl), phenanthrene (Phe), anthracene (An), fluoranthene (Flt), pyrene (Py), chrysene (Ch), benzo(a)anthracene(BaA),benzo(b)fluoranthene(BbF), benzo(k)fluoranthene (BkF), benzo(a)pyrene (BaP), indeno(1,2,3-cd)pyrene (IPy), dibenzo(a,h)anthracene (DBA), and benzo(g,h,i)perylene (Per). Results are thus presentedfor14USEPApriorityPAHcongeners(allbut acenaphthene and acenaphthylene) together with 1- and 2-methylnaphthalene. Analyses were carried using a flu- orimetricmethodmodifiedfromKootstraetal.(1995). Approximately 15 g of homogenised wet sedi- ment was extracted twice with 20 ml of acetone in an * Corresponding author. Tel.: +39-51-6398906; fax: +39-51- 6398940. E-mail address: frignani@igm.bo.cnr.it (M. Frignani). Baseline / Marine Pollution Bulletin 46 (2003) 903–917 907