Concentrations of Al, Fe, Cr, Cu, Ni, Pb and Zn in soils, sediments and water samples collected along the Oued Boufekrane river (Meknes, central Morocco) were determined. In soils, a homogeneous distribution of metal concentrations was observed throughout the study area except for Pb, which presents high enrichment at sites located at the vicinity of a main highway. In sediments, high enrichment, with respect to upstream sites, were observed downstream of the city of Meknes for Al, Cr, Fe and Ni and inside the city for Cu, Zn and Pb. In water samples, the metal contents showed to correlate with their homologues in sediments suggesting that the metal contents in water and sediments have identical origins. Descriptive statistics and multivariate analysis (principal factor method, PFM) were used to assist the interpretation of elemental data. This allowed the determination of the correlations between the metals and the identification of three main factor loadings controlling the metal variability in soils and sediments.

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The seasonal and spatial variations of particulate matter (PM2.5-10 and PM2.5) and its chemical composition have been studied over a one-year period in Kenitra city (2007-2008). The samples were collected using Gent stacked filters and dichotomous samplers in two size fractions: below 2.5 μm (fine) and 2.5 to 10 μm (coarse). The chemical compositions of the collected filters were evaluated by using Total X-ray Fluorescence and Atomic Absorption Spectroscopy. The influence of atmospheric transport scenarios on the levels of PM was elaborated by means of air mass back-trajectories, using the HYSPLIT™ model. This study allowed identifying four main transport patterns: short local flows over the Kenitra region, Northwesterly flows over the Atlantic Ocean, Northerly flows, and Southern flows. The highest PM2.5-10 concentrations were observed in the summer and the lowest in the winter. However, no significant seasonal variations were discerned for PM2.5 particles. The enrichment factor and risk assessment code were calculated to distinguish between anthropogenic influences and the natural background levels and assess the environmental risks of metals in PM2.5-10 and PM2.5 particles. A comparison of PM and metal concentrations in Kenitra city and other African cities (reported in the literature) revealed that that the values obtained in Kenitra city are significantly higher than those recorded for the other African cities (that are the subject of the comparison).

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The epitaxial realignment of undoped and As doped polysilicon films onto crystalline silicon substrates induced by high-temperature rapid-thermal annealing has been investigated. It is shown that the realignment mode and the kinetics of the process are intimately related to the microcrystalline structure of the layers under investigation, to the morphology of the native oxide film present at the interface, and to the presence of As atoms dispersed in the deposited layers. For layers having fine grain dimensions, compared to the film thickness, the realignment takes place via the motion of the crystal-polysilicon interface towards the surface. This is observed in undoped layers and in layers which have been subjected to a high-temperature anneal before As doping. The preimplant anneal disrupts the interfacial oxide film and reduces the thermal cycle needed to complete the realignment of the polysilicon layers. In layers which have not experienced any thermal treatment before As doping, it is seen that the grain size first increases to dimensions on the order of the film thickness, and the realignment transformation then proceeds by lateral growth of epitaxial columns in a manner similar to secondary grain growth. The kinetics of both realignment modes are thermally activated and the atomic limiting processes have been tentatively identified to be As diffusion in bulk Si for As doped layers and Si self diffusion for undoped films. The effect of the microcrystalline structure on the realignment kinetics is attributed to its relationship with the driving force governing the realignment transformation.

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