Étude de la qualité des eaux d’une retenue située sous climat aride : cas du barrage Hassan II (Province de Midelt, Maroc)

Les ressources hydriques dont dispose le Maroc sont limitées. Elles sont, par ailleurs, soumises à des variations cycliques extrêmes traduites par la succession des cycles de sécheresse aigue. Celle-ci est devenue un phénomène très fréquent au Maroc, qui contribue à la dégradation des zones humides nationales. Pour subvenir aux besoins en eau de plus en plus croissants, le Maroc s'est doté d'une importante infrastructure de grands barrages. Toutefois, la faisabilité et la gestion de ces ouvrages aménagés se trouvent confrontées à deux problèmes: l'envasement et l'eutrophisation. Ces deux phénomènes sont principalement favorisés par la nature du climat et les caractéristiques intrinsèques des bassins versants. Le bassin versant de la Moulouya est parmi les bassins  hydrographiques les plus importants au Maroc, il abrite jusqu'à nos jours cinq grands barrages, dont le barrage Hassan II qui fut mise en eau en 2005.Ce barrage constitue l’une des plus grandes retenues marocaines avec une capacité de stockage maximale de 400 millions de mètres cubes. Il contrôle un bassin versant de 3 300 km2. Il a comme vocations principales la production d’eau potable, l’irrigation, et la protection des zones aval contre les inondations. Or la prolifération des activités anthropiques, en amont, associées aux caractéristiques du climat de la région d’implantation du barrage, pourront être à l’origine de la dégradation de la qualité de ce plan d’eau. Notre travail étalé sur la période allant de septembre 2011 à août 2012 avait pour objectifs d'étudier la qualité des eaux du réservoir Hassan II et d’en déterminer l’état trophique. Il en ressort qu’il s’agit d’un lac oligotrophe avec une qualité de l’eau allant du bonne à excellente.Mots-clés : barrage Hassan II, Maroc, climat, eau, qualité, eutrophisation

Impact environnemental et évaluation de la qualité des eaux par des méthodes chimiques et biologiques « Diatomées »

Le but de cette étude est de surveiller la qualité des eaux de la Merja Fouarat par l’utilisation des diatomées benthiques comme bio-indicateurs et des variables chimiques telles que DBO5, ammoniums, nitrites et phosphates. L’évolution spatio-temporelle des valeurs de l’Indice de pollution organique (IPO) et de l’indice diatomique Leclercq (IDL), montrent que l’eau de la Merja Fouarat est fortement polluée à cause des rejets non traités des eaux usées domestiques et industrielles. L’IDL et L’IPO se classent dans le même niveau de pollution avec un écart faible (0,27-0,3-0,5-0,2-0,3), témoin que les diatomées intègrent les variations des facteurs polluants. Par ailleurs, les espèces rencontrées possèdent un caractère alcaliphyle prononcé avec uneabondance des espèces résistantes à la pollution organique.Mots clés : Diatomées, qualité de l’eau, bio-indicateur, IDL, IPO, Merja Fouarat

CONTRIBUTION A L’ETUDE DE LA QUALITE BACTERIOLOGIQUE DES EAUX DU BARRAGE HASSAN II (PROVINCE DE MIDELT, MAROC)

The watershed of Moulouya is among the most important basins in Morocco, it contains to the present five major dams, among them the Hassan II dam, which became operational in 2005. This dam is one of the largest Moroccan reservoirs with a maximum storage capacity of 400 million cubic meters. However, increased human activities upstream of the dam associated with the phenomenon of erosion could lead to pollution of the water mass. The aim of our study was to assess the bacteriological water quality of the reservoir through a monthly monitoring during the study period from September 2011 until August 2012. Detection of Escherichia coli and intestinal enterococci in water of dam was a presumption of its contamination by feces. With the exception of bottom waters that were loaded with spores of sulphite-reducing anaerobes, the waters of the other stations in the water column did not contain these spores. However, water levels in total coliforms, fecal coliforms and fecal streptococci were qualified water quality of the dam as good to excellent, this according to the Moroccan standards of quality of surface waters.Le bassin versant de la Moulouya est parmi les bassins hydrographiques les plus importants au Maroc, il abrite jusqu'à nos jours cinq grands barrages, dont le barrage Hassan II qui fut mis en eau en 2005. Ce barrage constitue l’une des plus grandes retenues marocaines avec une capacité de stockage maximale de 400 millions de mètres cubes. Or, l’accroissement des activités anthropiques en amont de ce barrage associé au phénomène de l’érosion pourraient induire une pollution de ce plan d’eau. L’objectif de notre travail était d’apprécier la qualité bactériologique des eaux de la retenue par le biais d’un suivi mensuel durant la période d’étude allant du mois de septembre 2011 au mois d’août 2012. La détection des Escherichia coli et des entérocoques intestinaux dans les eaux du barrage constituait une présomption de la contamination de celles-ci par les matières fécales. À l’exception des eaux du fond qu’étaient chargées en spores des micro-organismes anaérobies sulfito-réducteurs, les eaux des autres stations de la colonne d’eau en étaient indemnes. Toutefois, les teneurs des eaux en coliformes totaux, en coliformes fécaux et en streptocoques fécaux faisaient qualifier la qualité des eaux du barrage de bonne à excellente, ceci selon les normes marocaines de la qualité des eaux de surface

Improvement of the mechanical and thermal properties of concrete based on lightened aggregates

The objective of this work revolves around the search for a new lightweight concrete formula based on new natural raw materials and waste building materials. This concrete must have acceptable thermal properties while maintaining the mechanical properties used in buildings. In this work, experimental studies were carried out in order to characterize the mechanical and thermal properties of several concrete dosages. The results of this study highlight the possibility of manufacturing a light concrete mixture with a density ranging from 1600 to 1950 Kg/m3. This new concrete has insulating properties equivalent to those of silico-limestone bricks, hollow cement agglomerates and cavernous concretes, the thermal conductivity relative to the formulas of light concretes with the desired mechanical strengths ranges from 0.82 to 1.05 W/mK. It should be noted that concrete commonly used in building work is characterized by a thermal conductivity of 1.65 to 2.00 W/mK depending on the density of the concrete [1]. The compressive strength on cylinder of -all concrete formulas-, is endowed with a low quality with a value ≥ 12 MPa to correct with 32MPa depending on the type and the dosage of cement used, either CPJ 45 or CPJ55 without exceeding 500 kg/m3.

Theoretical and experimental studies of new synthetic quinoxaline derivatives as corrosion inhibitors for mild steel in a 1.0 M HCl environment

The study involved the synthesis and characterization of two hydrazinylidene-based quinoxaline derivatives, namely (2E,3E)-2,3-dihydrazono-6,7-dimethyl-1,2,3,4-tetrahydroquinoxaline (QN-CH3) and (2E,3E)-6-chloro-2,3-dihydrazono-1,2,3,4-tetrahydroquinoxaline (QN-Cl). These derivatives were tested for their effectiveness as inhibitors for mild steel in a 1.0 M hydrochloric acid solution at 363 K using various methods such as electrochemical tests, surface analysis techniques like scanning electron microscopy (SEM), as well as density functional theory (DFT) and molecular dynamics (MD) simulation. It was observed from the current-potential (I-E) curves that both QN-CH3 and QN-Cl acted as cathodic-type inhibitors, with their inhibition efficiencies increasing with concentration. At a concentration of 10-3 M, the inhibition efficiencies reached a maximum of 89.07% for QN-CH3 and 87.64% for QN-Cl. Electrochemical impedance spectroscopy (EIS) tests pointed towards the corrosion process being controlled by charge transfer. The superior performance of QN-CH3 compared to QN-Cl was attributed to the nature of its molecular structure. Furthermore, it was found that the hydrazinylidene-based quinoxaline derivatives adhered to the mild steel surface according to the Langmuir isotherm and maintained their anticorrosion performance at high temperatures, as confirmed by SEM analysis. DFT calculations and MD simulations provided further insight into the corrosion inhibition mechanism

The ocean sampling day consortium.

Ocean Sampling Day was initiated by the EU-funded Micro B3 (Marine Microbial Biodiversity, Bioinformatics, Biotechnology) project to obtain a snapshot of the marine microbial biodiversity and function of the world's oceans. It is a simultaneous global mega-sequencing campaign aiming to generate the largest standardized microbial data set in a single day. This will be achievable only through the coordinated efforts of an Ocean Sampling Day Consortium, supportive partnerships and networks between sites. This commentary outlines the establishment, function and aims of the Consortium and describes our vision for a sustainable study of marine microbial communities and their embedded functional traits

The ocean sampling day consortium

Ocean Sampling Day was initiated by the EU-funded Micro B3 (Marine Microbial Biodiversity, Bioinformatics, Biotechnology) project to obtain a snapshot of the marine microbial biodiversity and function of the world’s oceans. It is a simultaneous global mega-sequencing campaign aiming to generate the largest standardized microbial data set in a single day. This will be achievable only through the coordinated efforts of an Ocean Sampling Day Consortium, supportive partnerships and networks between sites. This commentary outlines the establishment, function and aims of the Consortium and describes our vision for a sustainable study of marine microbial communities and their embedded functional traits

Revealing a brain network endophenotype in families with idiopathic generalised epilepsy

Idiopathic generalised epilepsy (IGE) has a genetic basis. The mechanism of seizure expression is not fully known, but is assumed to involve large-scale brain networks. We hypothesised that abnormal brain network properties would be detected using EEG in patients with IGE, and would be manifest as a familial endophenotype in their unaffected first-degree relatives. We studied 117 participants: 35 patients with IGE, 42 unaffected first-degree relatives, and 40 normal controls, using scalp EEG. Graph theory was used to describe brain network topology in five frequency bands for each subject. Frequency bands were chosen based on a published Spectral Factor Analysis study which demonstrated these bands to be optimally robust and independent. Groups were compared, using Bonferroni correction to account for nonindependent measures and multiple groups. Degree distribution variance was greater in patients and relatives than controls in the 6-9 Hz band (p = 0.0005, p = 0.0009 respectively). Mean degree was greater in patients than healthy controls in the 6-9 Hz band (p = 0.0064). Clustering coefficient was higher in patients and relatives than controls in the 6-9 Hz band (p = 0.0025, p = 0.0013). Characteristic path length did not differ between groups. No differences were found between patients and unaffected relatives. These findings suggest brain network topology differs between patients with IGE and normal controls, and that some of these network measures show similar deviations in patients and in unaffected relatives who do not have epilepsy. This suggests brain network topology may be an inherited endophenotype of IGE, present in unaffected relatives who do not have epilepsy, as well as in affected patients. We propose that abnormal brain network topology may be an endophenotype of IGE, though not in itself sufficient to cause epilepsy

The Ocean Sampling Day Consortium

Ocean Sampling Day was initiated by the EU-funded Micro B3 (Marine Microbial Biodiversity, Bioinformatics, Biotechnology) project to obtain a snapshot of the marine microbial biodiversity and function of the world’s oceans. It is a simultaneous global mega-sequencing campaign aiming to generate the largest standardized microbial data set in a single day. This will be achievable only through the coordinated efforts of an Ocean Sampling Day Consortium, supportive partnerships and networks between sites. This commentary outlines the establishment, function and aims of the Consortium and describes our vision for a sustainable study of marine microbial communities and their embedded functional traits