Polychlorinated biphenyls in sediments of the Venice Lagoon Mauro Frignani a, * , L.G. Bellucci a , C. Carraro b , S. Raccanelli c a Consiglio Nazionale delle Ricerche, Istituto di Geologia Marina, Via Gobetti 101, I-40129 Bologna, Italy b EniChem, Stabilimento di P.to Marghera, Via della Chimica, P.to Marghera, Venezia, Italy c Consorzio Interuniversitario Nazionale la Chimica per l'Ambiente, Via della Libert  a 5/12, 30175 Marghera, Venezia, Italy Abstract Twenty-four sur®cial sediment samples, representing dierent environments within the Venice Lagoon, were ana- lyzed for polychlorinated biphenyls PCBs) in order to assess degrees of pollution, sources, areal distribution, and potential risk for the environment. Concentrations in sur®cial sediments range from 2 to more than 2049 lgkg 1 dw. ThemaximumisprobablyduetothedischargeofindustrialwastesintotheBrentellaCanal,withinthe®rstIndustrial Area. Lagoon samples are 11±205 times less contaminated, being in¯uenced by pollutants stored in the canals only occasionally. Congener pro®les distinguish PCBs in two main categories. The baseline pollution is probably due to a variety of sources within the lagoon system, whereas less chlorinated PCBs were discharged into the Brentella Canal. Our estimates suggest that, due to high concentrations, toxic equivalents TEQs) of PCBs are comparable to those relative to PCDD/Fs for the least contaminated samples, whereas they are lower in case of heavy PCDD/F contami- nation. Ó 2001 Elsevier Science Ltd. All rights reserved. Keywords: Industrial area; Lagoon sediments; Salt marshes; Industrial and urban pollution 1. Introduction The ®rst data regarding the presence of polychlori- nated biphenyls PCBs) in sediments of the Venice La- goon were provided by Orio and Donazzolo 1987). They found that PCBs showed the highest concentra- tions in sediments taken from locations close to the in- dustrial area of Porto Marghera, and that values increased constantly from the beginning of the 1950s up to a maximum at the surface approximately in 1982. Since then, other authors have discussed the presence of PCBsinsedimentsoftheVeniceLagoonandothertoxic micropollutants have been taken into consideration Marcomini et al., 1997, and references therein). Re- cently, Di Domenico et al. 1998) presented a summary of the results they obtained since 1992 studying heavy metal and organic micropollutant contamination. Ac- cording to these authors, PCB concentrations show a more uniform distribution with respect to other con- taminants, thus suggesting a generic anthropogenic im- pact. They found high concentrations inside both the industrial and the urban areas, with maximum values in the Ovest Industrial Canal and the Malamocco±Mar- ghera Canal: 5.5 and 2.7 lgg 1 , respectively. We ad- dressed similar problems on the basis of a more complete sampling and a greater attention to the reso- lutionofthesedimentrecordintermsofthethicknessof thesur®ciallayer.ThispaperdiscussesPCBdistribution and composition in order to assess the principal sources andpatterns.TheproblemofPCBtoxicity,withrespect toothercontaminantssuchasdioxinsandfurans,isalso taken into consideration. 2. Study area and sampling strategy The study area is shown in Figs. 1 and 2. The in- dustrialdistricthasbeenreportedasthemajorsourceof Chemosphere 43 2001) 567±575 * Corresponding author. Tel.: +39-051-639-8906; fax: +39- 051-639-8940. E-mail address: frignani@igm.bo.cnr.it M. Frignani). 0045-6535/01/$ - see front matter Ó 2001 Elsevier Science Ltd. All rights reserved. PII:S0045-653500)00408-2