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Preliminary treatment with glutaraldehyde increased the stability of chitosan in acidic solution and the sorption of palladium from HCl solutions at high loading. A reduction procedure was used to partially reduce the palladium. The resulting chitosan-supported palladium catalyst was efficiently used for the hydrodehalogenation and partial dehydrodearomatization of 2-chlorophenol (2-CP). The reaction proceeds via hydrogen transfer using sodium formate. The optimum pH for the degradation of 2-CP was close to pH 3. The effects of catalyst dosage, formate concentration, 2-CP concentration, and temperature were studied to define the optimum conditions for the conversion of 2-chlorophenol into phenol and cyclohexanone. A limit on the formate/2-CP molar ratio was found to be required to achieve the complete dehalogenation of 2-CP: The formate excess needed to be higher than 50 times the 2-CP concentration. Increasing the temperature from 20 to 60 °C continuously increased the degradation rate, and the activation energy ranged between 20 and 25 kJ mol -1 under nonlimiting experimental conditions (formate excess at the required level and pH 2.7).

The potential of remobilization of pollutants is a major problem for anthropogenic ecosystems, because even when the anthropogenic source of pollution is identified and removed, pollutants stored in sediments can be released into the water column and impact pelagic communities during sediment resuspension provoked by dredging, storms or bottom trawling. The objectives of the present study were to assess the changes observed in the chemical composition of the water column following resuspension of a polluted marine sediment and the consequences for the chemical composition of adjacent marine waters according to season. For that purpose, an experimental sediment resuspension protocol was performed on four distinct occasions, spring, summer, fall and winter, and the changes in nutrients, organic contaminants and inorganic contaminants were measured after mixing sediment elutriate with lagoon waters and offshore waters sampled nearby. Significant seasonal variations in the chemical composition of the contaminated sediments were observed, with a strong accumulation of PAHs in fall, whereas minimum PAH concentrations were observed during winter. In all seasons, sediment resuspension provoked a significant enrichment in nutrients, dissolved organic carbon, and trace metal elements like Ni, Cu, and Zn in offshore waters and lagoon waters, with enrichment factors that were season and site dependent. The most pronounced changes were observed for offshore waters, especially in spring and winter, whereas the chemical composition of lagoon waters was weakly impacted by the compounds supplied by sediment resuspension.

A study of pesticides in the Bizerte lagoon watershed on the Mediterranean coast of Tunisia 16 showed that herbicides and fungicides are the most commonly used compounds. A survey 17 was made of selected farmers. Pesticide contamination was monitored in the water column 18 and sediments at four selected sampling sites (lagoon (A) and in three oueds: Chegui (B), 19 Garaa (C) and Tinja (D)). Polar organic chemical integrative samplers (POCIS) were used to 20 assess pesticide contamination. Thirty-two pesticides were investigated; the total