A radioactive tracer was used to map the plume of the effluent of a municipal water treatment plant located on the Tunisian coast, close to the city of Sousse. A sampling campaign was programmed on the basis of the radioactivity distribution. The extent of sediment contamination was investigated to determine the impact of the plant effluent. Organic carbon and organic micropollutants (PCBs and chlorinated pesticides) were analysed on resuspendable particulate matter, on grab and core sediments. The area distributions of different compounds analysed were studied and relationships were investigated between radioactivity and organic carbon and micropollutant data. The study shows that sludge particles are deposited and accumulate in the zone south of the effluent outlet, contaminating sediments. Good correlations were found which demonstrate the efficiency of the technique used to plan the sampling and the link between organic carbon and organic micropollutants.

The effect of enzymes addition (glycosidase and protease) in rabbit diets on nutrients digestibility, nitrogen balance and energy utilization was studied.9 adult rabbits were fed a commercial diet containing 15.5% of crude protein and 23% of crude fibre (basal diet, diet A). Then, the same animals were fed the same diet, with the addition (per kg as fed) of 100 IU of cellulase (diet B), or 300 IU of cellulase (diet C), or 0.25 g of a pool of glycosidase and protease (diet D) or 0.75 g of the same pool (diet E) or with mean levels of cellulase and pool (diet F). From the obtained results, the digestibility increased significantly for NDF (+5%) and for ADF (+13%), with mean levels of cellulase and pool (diet F). The digestibility of the other nutrients was never improved by enzymes addition. Nitrogen balance was always lower in animals fed enzymes, with negative values for diets D, E and F; energy digestibility and metabolism activity in animals fed diets with the pool of enzymes were significantly lower than in the control group.The negative effect of enzymes addition could depend on the change in rabbit digestive physiology and particularly in caecotrophy, that allows the reutilization of the enteric fermentation products that supplies energy and proteins.

Vibrio fisheri test has been used to evaluate the toxicity of contaminated sediment of the Venice lagoon. The following classes of organic microcontaminants were considered in this study: aliphatic hydrocarbons (AHs), polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs) and chlorinated pesticides. Contaminants were extracted from samples with n‐hexane/dichloromethane in a sonication bath. Extracts were then purified and fractionated with column chromatography. A solvent exchange into ethanol was made before testing, to reduce toxicity. Preliminary tests were performed to set up the procedure to apply Vibrio fisheri to organic extracts. The application of the test with organic extracts was made at different steps of clean‐up and fractionation into classes of compounds. The purpose of the study was to set up a procedure to comparatively assess sediment contamination with chemical analyses and toxicity bioassays.

Rh/ZrO2 catalysts (1% w/w) with different amounts of iron as promoter (Fe/Rh atomic ratio in the range 0–2) were prepared from three precursors: carbonyl clusters, chloride salts, nitrate salts. The catalysts were characterized by H2 and O2 chemisorption, titration of chemisorbed oxygen with hydrogen, TPR, X-ray analysis and IR spectroscopy of chemisorbed CO in the range of 300–773 K. The activity has been tested in the CO hydrogenation reaction (H2/CO = 3/1) at 493 K under atmospheric pressure. The physico-chemical characterization of the catalysts evidenced that iron is present either as oxidized Feδ+ or in the reduced Fe0 form: IR analysis revealed that some reduced iron either decorates or is near the border of Rh particles. The metal precursors do not seem to influence significantly the behaviour of the catalysts. Two opposing effects of iron were evidenced: (i) a decrease of Rh sites available for carbon monoxide and hydrogen chemisorption; (ii) an increase of doubly bonded CO (RhCOFe) favoured by Fex+ sites, contiguous to Rh sites, that are reduced to Fe0 sites in reaction conditions. Depending on the surface environment, the bridged CO may dissociate to RhC and FeO or insert a hydrogen or an alkyl group with formation of an acyl species.

The research aimed to investigate, on the basis of the ingesta-excreta difference, the fatty acid digestibility of some diets for chickens supplemented with different fats.Nine groups, each of 4 male chickens, weighing about 3 kg, were fed a basal diet (Group A = control) or experimental diets consisting of the basal diet supplemented with tallow and pork fat (group B), glycerides containing fatty acids with different U/S ratio (groups C, D and E), calcium soaps (groups F, G, and H) and free fatty acids (group I) derived from the animal fat blending. The total lipids and the fatty acid compositions were determined, as well as the apparent and relative digestibility, on feed and droppings.Diets containing soaps with unsaturation rate decreasing from 80 to 70%, increased the digestibility of the fats. from 74.2 to 83% whereas glycerides with unsaturation rate decreasing from 80 to 50%, reduced digestibility from 94.6 to 83.9%. Unsaturated fatty acids were more digestible than saturated in all the diets.

Evaluation of the amount of uric acid in chickens’ excreta was examined in order to determine nitrogen catabolism and to estimate fiber correctly by the Van Soest method (ADF). Uric acid was determined by an enzymatic method with a colorimetric test employed in clinical chemistry, suitably modified. Gross fiber, determined by the Van Soest method, was washed with a .5% solution of Li2 CO3 and then uric acid was determined on the basis of weight loss. The mean values of uric acid were determined according to the two methods previously described, 2.643 g/100 g and 2.633 g/100 g of fresh excreta, respectively.