PCDD/Fs OCCURRENCE IN A MEDITERRANEAN COASTAL LAGOON (ETANG DE THAU, FRANCE): CONCENTRATIONS AND PATTERNS IN DIFFERENT ENVIRONMENTAL COMPARTMENTS

Introduction Thau lagoon is one of the largest Mediterranean lagoons. Located on the French Mediterranean coast along the Gulf of Lion (Figure 1), it covers a surface of 75 km with an average depth of 4.5 m and is isolated from the Mediterranean Sea by an offshore bar. The lagoon receives inputs from different human activities: urban activities, industries, agriculture and shell farming. The biggest town (Sete) and most of urban activities, like incineration, are located in the Eastern part of the lagoon. Thus, Thau lagoon appears to be under an intense anthropogenic pressure. For instance, the results of the French Monitoring Network (RNO Reseau National d’Observation) shows high contamination of the Thau lagoon sediments by hydrophobic organic compounds such as, polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) . However, only few data in relevant environmental compartments from Thau lagoon on other important groups of persistent organic pollutants (POPs), like polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), have been reported to date. Moreover, the dynamics, long term impacts and ultimate fate of the contamination induced by these chemicals in the lagoon is not well known. The aim of this work was to investigate the PCDD/Fs concentrations and patterns in air (where no data are available yet), sediments and mussels from Thau Lagoon. The influence of the atmosphere in the accumulation of these POPs in the aquatic system was studied. Two land air sampling sites were set up in the lagoon and sediments and mussels samples were collected from selected stations.