Persistent organic pollutants in sediments from the Lagoon of Venice-a possible hazard for sediment-dwelling organisms

Purpose The Lagoon of Venice is a well-known Italian environment characterized by heavy chemical pollution. Few studies have been carried out to evaluate the probable hazards of the chemical mixtures toward the biocoenosis. This is the first comprehensive study aimed at the evaluation of the possible adverse effects for benthic organisms from the Lagoon of Venice due to some persistent organic pollutants by using three different sediment quality guidelines (SQGs). Materials and methods We measured the concentrations of some priority industrial (PAHs and PCBs) and agricultural (DDTs, HCHs, and HCB) pollutants in surface sediments of eight sampling stations, chosen on the basis of their environmental features and probable pollution sources. Since the use of only the POP concentrations does not allow for an overall and correct environmental risk assessment, we followed an approach based on three different SQGs to identify a possible hazard for benthic invertebrates: the TEL/PEL approach, the consensus SQGs obtained by threshold effect concentration (TEC), probable effect concentration (PEC), and extreme effect concentration (EEC) proposed for several OCs and PAHs, and the ERL-ERM guidelines, which consider the role of a chemical mixture by using the m-ERM-Q (mean ERM quotient). Results and discussion Nonetheless the great amount of anthropogenic chemical sources as industries and intense road and ship traffic, PAHs (15.08-388.89 ng g(-1) d.w.) and PCBs (0.62-8.69 ng g(-1) d.w.) were detected in low to moderate concentrations. High levels were found for the organochlorine compounds (OCs), especially the DDT homologues (7.28-213.15 ng g(-1) d.w.), which were likely transported through some tributaries of the inland into the Lagoon. To evaluate the possible hazard for the biocoenosis, we evaluated the toxic effects that might be expected to the benthic organisms by using three different SQGs. They showed that the pollution of six stations can cause moderate to high adverse effects to sediment-dwelling organisms, mainly due to OCs, while the contribution of PAHs to the total toxicity seems to be negligible. Conclusions This study has demonstrated the presence of a widespread contamination caused by POPs in the Lagoon of Venice that is not always related to the localization of the expected emission sources. By using different SQGs, we highlighted a non-negligible environmental hazard for benthic invertebrates living in this environment, since the majority of the sampling sites studied present a possible moderate to high toxicity for the sediment-dwelling organisms.