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Search Results: 1 - 10 of 50520 matches for " Y Hsissou "
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Groundwater nitrate pollution in Souss-Massa basin (south-west Morocco)
T Tagma, Y Hsissou, L Bouchaou, L Bouragba, S Boutaleb
African Journal of Environmental Science and Technology , 2009,
Abstract: The objective of our study was to determine the current status of alluvial aquifer in the Souss-Massa basin, where the nitrate pollution of groundwater is being increasing along the last decades. A multiapproach methodology using hydrogeology, nitrate concentrations, irrigation type and oxygen-18 and deuterium data, was carried out to identify the sources of this pollution. According to the spatial distribution of nitrate contents, nitrate pollution occurs mainly in Chtouka-Massa plain. More than 36% of the sampled wells exceed the value of 50 mg/L as NO3 -. Groundwater in Souss plain is less polluted comparing it to Chtouka-Massa; only 7% of wells exceed the permitted level. Agricultural practices in the study sites are the main cause of serious nitrate pollution given the uperimposition of high nitrate concentrations with the distribution of irrigated perimeters. High nitrate levels are associated with high 18O values, clearly indicating that significant quantities of evaporated irrigation waters infiltrate along with fertilizer nitrate to groundwater system. Different 18O-NO3 - trends suggest isotopically distinct, non-point source origins which vary spatially and temporally, due to different degrees of evaporation/recharge and amounts of fertilizer applied.
Characterization of groundwater in the Souss upstream basin: Hydrochemical and environmental isotopes approaches
L Bouragba, MJ Jacques, L Bouchaou, Y Hsissou, T Tagma
African Journal of Environmental Science and Technology , 2011,
Abstract: The hydrochemistry of major ions and environmental isotope compositions (18O, 2H) of water samples have been used to identify the chemical characteristics and the origin of groundwater in the Souss upstream basin. The total dissolved solids (TDS) did not exceed 1000 mg.L-1 with an average of 635 mg.L-1. Two chemical water types were observed: A calcium and magnesium bicarbonate type (Ca2+-Mg2+-HCO3-), forming the dominant water type generally observed in the plain along the Souss river and towards the piedmont of the Anti-Atlas Mountains; and a calcium sulphate type (Ca2+-SO42-), from the northwest of the study area, linked to the presence of phosphatic gypseous marls and limestone marls (Upper Cretaceous). The calculations of saturation indexes versus the main mineral phases have been carried out, using the PHREEQC program. The groundwater is saturated and slightly oversaturated with respect to carbonate minerals and under saturated with respect to evaporite minerals; surface waters show an oversaturation with respect to carbonate mineral phases, mainly dolomite. The groundwater composition is largely controlled by the dissolution of carbonate rocks known in this part of the basin. Stable isotope contents of groundwaters ranged from -7.96 to -6.26‰ for δ18O and from -49.47 to -39.28‰ for δD. The hydrogen (δD) and oxygen (δ18O) isotope signatures indicate a low evaporation of precipitations during infiltration and that the aquifer is highly influenced by the contribution of recharge water recharge from the High Atlas Mountains.
Determination of recharge modes of aquifers by use of chemical and isotopic tracers. Case study of the contact zone between Western High-Atlas Chain and Souss Plain (SW Morocco)
Boutaleb, S.,Bouchaou, L.,Hsissou, Y.,Tagma, T.
Estudios Geologicos , 2008, DOI: 10.3989/egeol.08641459
Abstract: Determination of the origin of recharge of the unconfined aquifer in the right side of the Souss wadi between Agadir and Taroudant (South-western of Morocco) was based on the use of hydrochemical and isotopic analysis of groundwater, surface water and springs of the contact zone between the High-Atlas Chain and the Souss plain. The correspondence in the space evolution of the various chemical elements of evaporitic origin (SO42-, Cl-, Sr2+) in groundwater, piedmont springs, and surface water reveals the existence of recharge water from the adjacent High-Atlas Chain. The various recharge modes of the different aquifers (High Atlas and Souss plain) determined by isotopic analysis, shows that the source of groundwater for the unconfined Souss aquifer seems to be composite between a direct infiltration on the High-Atlas tributaries and a remote recharge from the bordering High Atlas aquifers. La determinación del origen de los aportes de agua de la capa freática de la ribera derecha del rio Souss entre Agadir y Taroudant (Suroeste de Marruecos) se ha basado en la hidroquímica y el análisis isotópico de las aguas subterráneas, aguas superficiales y manantiales de la zona de contacto entre el Alto Atlas y la llanura de Souss. La correspondencia en la evolución espacial de los diferentes elementos químicos de origen evaporítico (SO42-, Cl-, Sr2+) en las aguas subterráneas, manantiales de pie de monte y aguas superficiales, revela la existencia de una recarga de agua procedente de la cadena del Alto Atlas. El análisis de los modos de recarga de los diferentes acuíferos (Alto Atlas y llanura de Souss) determinado por análisis isotópico, demuestra que la alimentación de la capa freática de Souss a partir del Alto Atlas parece ser mixta, compuesta por una infiltración directa de los afluentes del Alto Atlas y una alimentación lejana desde los acuiferos que limitan con el borde del Alto Atlas.
Capillary rise quantifications based on in-situ artificial deuterium peak displacement and laboratory soil characterization
O. Grünberger, J. L. Michelot, L. Bouchaou, P. Macaigne, Y. Hsissou,C. Hammecker
Hydrology and Earth System Sciences (HESS) & Discussions (HESSD) , 2011,
Abstract: In arid environments, water rises from the saturated level of a shallow aquifer to the drying soil surface where evaporation occurs. This process plays important roles in terms of plant survival, salt balance and aquifer budget. A new field quantification method of this capillary rise flow is proposed using micro-injections (6 μL) of a deuterium-enriched solution (δ value of 63 000‰ vs. V-SMOW) into unsaturated soil at a 1 m depth. Evaluation of peak displacement from profile sampling 35 days later delivered an estimate that was compared with outputs of numerical simulation based on laboratory hydrodynamic measurements assuming a steady state regime. A rate of 3.7 cm y 1 was estimated at a Moroccan site, where the aquifer water depth was 2.44 m. This value was higher than that computed from the relationship between evaporation rates and water level depth based on natural isotopic profile estimates, but it was lower than every estimate established using integration of the van Genuchten closed-form functions for soil hydraulic conductivity and retention curve.
Nitrate Contamination of Groundwater in Irrigated Perimeters under Arid Climate (The Case of Souss-Massa Aquifer, Morocco)
Tarik Tagma,Youssef Hsissou,Lhoussaine Bouchaou,Latifa Bouragba,Said Boutaleb
Environmental Research Journal , 2012,
Abstract: The objective of this study was to clarify, the current status of alluvial aquifer in the Souss-Massa basin, where, the nitric pollution of groundwater is being increasing along the last decades. A multi-approach methodology using hydrogeology, nitrate concentrations, irrigation mode and Oxygen-18 and Deuterium isotopes data, was carried out to identify the sources of this pollution. According to the spatial distribution of nitrate contents, nitric pollution occurs mainly in the Chtouka-Massa plain. More than 36% of the sampled wells exceed the value of 50 mg L-1 which, constitutes the threshold value of nitrate concentrations for drinking water Moroccan standards. The groundwater in Souss plain is less polluted comparing to Chtouka-Massa. Only 7% of wells exceed the permitted level. The widespread distribution of high nitrate contents agrees with the distribution of irrigated areas, which can explain the major origin from agricultural fertilizers. High nitrate levels are associated with high δ18O values, clearly indicating that significant quantities of evaporated (isotopically enriched) irrigation water infiltrate along with fertilizer nitrate to the groundwater system. Different δ18O-NO3- trends suggest isotopically distinct, non-point source origins, which vary spatially and temporally, due to different degrees of evaporation/recharge and amounts of fertilizer applied.
A New Paradigm for Metallic Alloys in Materials Science  [PDF]
Y. Ustinovshikov
Advances in Materials Physics and Chemistry (AMPC) , 2015, DOI: 10.4236/ampc.2015.57025
Abstract: In the article, taking into account the phase transition “ordering-phase separation” discovered in alloys, new concepts about the diffusion phase transformations in alloys are formulated: chemical interaction between dissimilar atoms exists always in all alloys and at any temperature of heating; alloys offer a surprising and not previously known property of changing the sign of the chemical interaction between dissimilar atoms at a change of the temperature or composition of alloys; diffusion processes occurring in alloys at different temperatures depend on the sign and the absolute magnitude of the energy of the chemical interaction between dissimilar atoms. All these three concepts are analyzed in detail, by the example of Ni-based and Co-based binary alloys using experimental results obtained by transmission electron microscopy. It is shown, on these ideas, how to carry out heat treatment of alloys more rationally, what principles should underpinned in the base of the construction of phase diagrams, how the microstructures of ordering and phase separation affect some properties of alloys.
Quasi-Square Wave Mode Phase-Shifted PWM LCC Resonant Converter for Regulated Power Supply  [PDF]
S. PADMANABHAN, Y. SUKHI, Y. JEYASHREE
Engineering (ENG) , 2009, DOI: 10.4236/eng.2009.13024
Abstract: This paper presents an improved self sustained oscillating controller circuit using LCC components for improving the overall efficiency of the system. It has a micro controller based active controller, which controls the performance from no-load up to full-load. The steady state characteristics are developed and a design example is given in detail. The proposed controller allows zero current switching at any loading condition which results in a reasonable reduction of power loss during switching with a promising efficiency. Analytical and experimental results verify the achievement the design specifications.
After the Treatment Phase of Colorectal Cancer Care: Survivorship and Follow-Up  [PDF]
Maria Y. Ho, Winson Y. Cheung
Journal of Cancer Therapy (JCT) , 2012, DOI: 10.4236/jct.2012.326125
Abstract: The number of long-term colorectal cancer (CRC) survivors has increased substantially over the past three decades due to both ongoing advances in early detection and improvements in cancer therapies. Adult survivors of CRC experience chronic health conditions due to normal issues associated with aging, which is further compounded by the long-term adverse effects of having had cancer and anti-cancer therapies. In addition, they are at a higher risk for CRC recurrences, new primary cancers, and other co-morbidities. This article will provide an overview of the clinical care of adult survivors of CRC. Epidemiologic data will be presented followed by a discussion of the approach to the care of long-term adult survivors of CRC, including surveillance of recurrences and new primary cancers, interventions to manage both physical and psychological consequences of cancer and its treatments, and strategies to address concerns related to unemployment and disability. Finally, we will explore the challenges of healthcare delivery, especially with respect to the coordination of follow-up between cancer specialists and primary care physicians, so as to ensure that all of the survivor’s health needs are met promptly and appropriately.
Electronic states and pairing symmetry in the two-dimensional 16 band d-p model for iron-based superconductor
Y. Yanagi,Y. Yamakawa,Y. ōno
Physics , 2008, DOI: 10.1143/JPSJS.77SC.149
Abstract: The electronic states of the FeAs plane in iron-based superconductors are investigated on the basis of the two-dimensional 16-band d-p model, where the tight-binding parameters are determined so as to fit the band structure obtained by the density functional calculation for LaFeAsO. The model includes the Coulomb interaction on a Fe site: the intra- and inter-orbital direct terms U and U', the exchange coupling J and the pair-transfer J'. Within the random phase approximation (RPA), we discuss the pairing symmetry of possible superconducting states including s-wave and d-wave pairing on the U'-J plane.
Detecting the light of the night sky in Mars  [PDF]
Nebil Y. Misconi
Natural Science (NS) , 2011, DOI: 10.4236/ns.2011.34036
Abstract: In this paper a new methodology is outlined to detect the dust content in the Martian atmosphere during nighttime. In the previous Lander missions to Mars, scientists were able to determine the dust load in the Martian atmosphere during daylight using spectral lines of the Sun. Since the dynamics of Martian dust storms had been determined to be very rapid changing over times of hours and not days, it is imperative to determine the dust load during nighttime, so future astronauts to Mars can take protective measures for their equipment. They can also factor this effect for their planned activities during daytime. The new methodology greatly improves on the classical method for determining the extinction in the Earth’s atmosphere. The classical method uses observations of bright stars from which the optical depth, ?total, can then be deduced from the classical brightness equation. The classical method succeeds reasonably well at high elevation angles from the horizon but fails dramatically at low elevation angles. It also determines ?total from the slope of a plot of observed brightness of a bright star vs. air mass at all elevations. The plot shows a straight line at high elevations angles, which then curves and becomes uncertain at low elevation angles. The new methodology bypasses this severe difficulty by simply eliminating this plot, and by acquiring the brightness of a bright star above the atmosphere (no extinction) and compares it to the observed bright- ness of the same star below the atmosphere at all elevations.
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