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In this article, we discuss the academic performance and impact of distance teaching of mathematics in the Moroccan education system. This educational science research, based on exploratory thinking, aimed to show the impact and challenges of distance teaching of mathematics within the Moroccan education system through examining this fundamental question: How could school programs, pedagogical organization, and the performance of pupils and teachers in Morocco best address the challenges of distance teaching of mathematics? The answer is based on a qualitative analysis of the content of the documentation that frames the teaching-learning process and the evaluation of mathematics in Morocco and, on the other hand, on the projection of research hypotheses in the field through various strategies inspired by our research objectives.

Keywords: curriculum, education system, e-learning, evaluation, technology, Morocco

Keywords: Kilito, Abdelfattah, Archéologie, Intertextualité mythique, Réécriture, Mythèmes

The aim of this study was to investigate the potential of a helophytic plant, Phragmites australis (Cav.) Steudel, to remove chromium from concentrated tannery effluent in comparison to unplanted soil, under arid climate conditions. The experiment was conducted from August 2002 to August 2003. Six plots (capacity: 120 L, diameter: 50 cm) were filled to depths of 15 cm and 60 cm with gravel and soil respectively (texture: 3.5% clay, 8.5% silt, and 88% sand). Three plots were planted with Phragmites australis (Cav.) Steudel. Young shoots of plants (36 stems/m2) were taken from local and natural reed stands. Three unplanted plots were used as controls. The soil for the study was from the Tensift River (Marrakech). The experimental plots were supplied exclusively with diluted tannery wastewater, 3 times a week (approximately 10 L each time). The water flowed vertically through the substratum.To investigate the capacity of the systems to increase pH, to decrease conductivity chemical oxygen demand (COD), and to remove total chromium, concentrations in the inflow and outflow of each plot were determined during the experiment. System hydrology indicated that for planted systems, the mean flow varied from 18 mL/min (in winter) to 49 mL/min (in summer), with an average value of 35 mL/min. For the unplanted system, the mean flow varied from 5 mL/min (in winter) to 15 mL/min (in summer) with an average value of 12 mL/min. Water recovery at the outflow of the planted system (PP) and unplanted system (NPP) was 40% and 60% respectively. This may be related to the phenomenon of evapotranspiration from the PP system, which was more significant than simple evaporation from the NPP system. No sign of clogging was observed in the planted systems due to the plant rhizomes that ensure a better aeration of the soil. The study of the hydrological operation showed that mean flow in the planted system was three times higher than that in the unplanted soil, which makes it possible to treat a larger volume of wastewater and to reduce the required per capita surface for treatment. The presence of Phragmites australis ensured a sufficient porosity for the percolation of water for treatment.The pH of the effluent at the outlets of the planted and unplanted systems increased by two to three units in comparison with the raw wastewater at the inlet. The average inflow pH was 5.5; at the outflow of the two systems, the pH was 7.30 and 8.20 respectively for the planted and unplanted soil. The electrical conductivity (EC) of the treated wastewater increased for the two systems. The average inflow conductivity was 54±5.5ms/cm. At the outflow of the two systems, the EC was about 75±14 ms/cm and 68±11 ms/cm respectively for the planted and unplanted systems. The EC removal for all systems varied significantly from season to another (p< 0.05).The planted system was more efficient in removing total COD (74%) than the unplanted one (61%). There were significant differences (ANOVA) between the PP and NPP systems (p<0.05). Total chromium concentrations at the inflow varied from 534 mg/L to 1000 mg/L with an average content of 780±196 mg/L. At the outflow, total chromium concentrations varied from 2.2 mg/L to 3 mg/L with an average content of 2±0.5 mg/L for the PP system and from 2.5 mg/L to 4 mg/L with an average value of 2.4±1.3 mg/L for the NPP system. Total chromium removal of 99% occurred for the two pilots, which provides limpid purified water. Despite the shorter retention time for the planted system, which was three times less than in the unplanted one, total chromium was almost completely removed.The aquatic macrophyte plant seemed to play a physical role by enhancing the hydrological conductivity of the substratum and consequently the operation and management of these systems. Phragmites australis (Cav.) Steudel has the ability to transfer oxygen from the rhizome towards the roots through an internal lacunar system, which offers the creation of an aerobic zone around the roots. This aerobic zone allows the proliferation of micro-organisms, which are the principal decomposers of the organic matter in the root zone.The treatment of tannery effluent by reed beds is a clean approach from an ecological point of view and constitutes a viable economic alternative in comparison to purely chemical approaches and is thus better adapted to the complexity of the systems used in the leather industry.

Keywords: Phragmites australis (Cav.) Steudel, climat aride, tannerie, rejet industriel, chrome, lits à roseaux, Phragmites australis (Cav.) Steudel, arid climate, chromium, tannery, industrial wastewater, reed beds

Bioaccumulation of cadmium, lead and arsenic in fish and bivalves commonly caught in Togo lagoon system was evaluated in order to estimate the health risks associated with their use. The results showed that all analyzed fish are contaminated. The mean levels of cadmium (0.33 mg/kg for Caranx hippos to 0.98 mg/kg for Hemichromis fasciatus), lead (1.17 mg/kg for Liza falcipinnis to 2.89 mg/kg for Lutjanus goreensis ) and arsenic (9.41 mg/kg for C. hippos to 22.54 mg/kg for Pomadasys jubelini) are higher than the standards set by the WHO. Bioconcentration Factors (BCF) ranged from 6.94 to 20, 36 for Cd, 9.58 to 23.67 for Pb and 2.30 to 5.52 for As. As far as bivalves are concern, average grades indicate a high concentration of arsenic (56.06 mg/kg for Senilia senilis and 47.76 mg/kg for Crassostrea gasar) followed by lead (2.83 mg/kg for S. senilis and 2.95 mg/kg for C.gasar) and finally cadmium (0.97 mg/kg for S. senilis and 0.83 mg/kg for C.gasar). BCF ranged from 16.6 to 19.14 for Cd, 39.86 to 41.55 for Pb and 19.10 to 34.42 for As. In addition,

Keywords: Bioaccumulation, métaux lourds, poissons, bivalves, risques sanitaires, système lagunaire, Togo