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International audience; Scaling process is the main problem encountered in industrial plants using water. Several factors, (pH, temperature, hydrodynamic conditions, metal surface, and especially, water composition),can affect the scaling kinetics of calcium carbonate (CaCO3), one of the main component of scaling. In addition, some foreign ions added can considerably modified the scaling rates. In thiswork, the inhibiting effects of Zn2+ and Cu2+ cations on CaCO3 precipitation were studied in a 50°F synthetic carbonic solution by using fast controlled precipitation (FCP) and scaling quartz crystal microbalance (SQCM) methods, for homogeneous and heterogeneous scaling deposition, respectively. Results showed that Zn2+ and Cu2+ ions are efficient, at high concentrations (≥ 1mg/L), to delay or even to prevent nucleation/growth of CaCO3. FCP measurements showed a complete inhibition of the homogeneous CaCO3 precipitation after 120 min in synthetic solutioncontaining 5 mg/L and 4 mg/L of Cu2+ and Zn2+, respectively. SQCM measurements showed that the surface coverage of the metallic substrate by a layer of CaCO3 is reduced when the amount of these cations increased. Zn2+ cations inhibited the heterogeneous CaCO3 precipitation moree fficiently than Cu2+. SEM and XRD results indicated that both cations affect calcium carbonatenucleation by changing the morphology of CaCO3 crystals

International audience; The contamination of the marine environment by organic pollutants is a matter of great concern. Bizerte Lagoon is the second largest lagoon in Tunisia, and is known for different industry and fishing activities. The objective of this work is to investigate the distribution of seven polychlorinated biphenyls (PCBs) and nine organochlorine (OCPs) pesticides in water samples collected from the Lagoon of Bizerte. Extraction of water samples was performed by liquid–liquid extraction with hexane. Gas chromatography with 63Ni electron capture detector was used to perform qualitative and quantitative determinations. The average concentrations of OCPs were 0.42 and 14.92 ng L−1. For PCBs the concentrations range between 3 and 10.4 ng L−1. The predominant PCB congeners in the surface water were PCB 28 (0.2–1.4 ng L−1) and PCB 52 (0.8–3.5 ng L−1). The most widespread OCPs were DDTs with a concentration varied between ND and 8.51 ng L−1, heptachlor (ND and 7.83 ng L−1), and endrin (ND and 1.51 ng L−1). These concentrations are generally similar to the background levels from the Mediterranean Sea.