Évaluation du risque pour l’environnement des métaux lourds [Fe(T)-Mn+2] issus du milieu Industriel : Cas de la plaine de la Meboudja, Nord-Est Algérien

L’Algérie a mis en place un réseau industriel dense, concentrant des secteurs polluants et gros consommateurs d’eau et d’énergie. Ce tissu industriel a été implanté à proximité des sources d’eau (barrages, mer), ou des fleuves qui sont devenus des décharges pour des rejets liquides non contrôlés. La Meboudja est un des oueds les plus anthropisés de la plaine d’El Hadjar qui abrite une des plus fortes densités industrielles, agricoles et urbaines (localité d’Hjar diss, Derradji Rdjam ; El Hadjar ; et Sidi Amar). Des concentrations excessives de métaux lourds peuvent être introduites dans l'environnement, par exemple, par les déchets industriels (complexe sidérurgique d’El Hadjar, la zone industrielle de Meboudja et la zone industrielle de pont Bouchet). Les apports en fer et en manganèse dans les eaux superficielles et souterraines de la plaine de Meboudja sont très variables en quantité mais aussi en qualité. Des teneurs élevées en fer « dissous » de 26.30 mg.l-1 et en Manganèse dissous, 3.40mg.l-1, ont été observées dans les eaux de l’oued Meboudja [1]. Ces teneurs ne peuvent être expliqués que par des émissions intenses en provenance des différents rejets situés dans la plaine.Mots-clés : métaux lourds, rejet liquide, déchets industriels, pollution, environnement, oued Meboudja, Nord-Est algérie

IMPACT DES REJETS URBAINS ET INDUSTRIELS SUR L'EAU SUPERFICIELLE ET SOUTERRAINE DANS LA PLAINE D’ANNABA (ALGERIE) IMPACT OF URBAN AND INDUSTRIAL WASTES ON SUPERFICIAL AND GROUNDWATER IN THE PLAIN OF ANNABA (ALGERIA)

Les rejets urbains au niveau de l’oued Meboudja, un des affluents de la Seybouse posent l’épineuse question de leur impact surles eaux superficielles et souterraines de la plaine de d’Annaba. Dans cette recherche, plusieurs campagnes de prélèvement àpas mensuel des eaux superficielles de l’oued et les eaux souterraines sur deux points témoins dont un en pompage ont étéréalisées pendant le cycle hydrologique annuel. La comparaison entre la composition chimique des eaux de l’oued et celles deseaux souterraines captées montre qu’au niveau de l’oued, on observe l’existence de deux polluants : le phosphate etl’ammonium, par contre, au niveau de la nappe on observe seulement les ions phosphate qui ont pu se déplacer sous la mêmeforme chimique entre l’oued et les deux puits.La diminution de la concentration des phosphates entre l’oued et les captages est due à l’effet de la dilution des concentrationspar les eaux de la nappe, la précipitation des phosphates sous la forme des phosphates de calcium et enfin l’adsorption par lesargiles. En revanche l’absence de l’ammonium dans les captages est due au changement de la forme azotée en nitrate au coursdu trajet entre les deux milieux sous l’effet des conditions oxydantes. Urban wastes in wadi of Meboudja, a tributary of the Seybouse raise the difficult question of their impact on surface andgroundwater in conjunction with the plain of Annaba. In this research, several sampling campaigns at no monthly surfacewater of the river and groundwater on two witnesses in which a pump were conducted during the annual hydrological cycle.The comparison between the chemical composition of the river’s water and those of groundwater collected shows that, weobserve the existence of two pollutants: phosphate and ammonium, for against, at the water there is only the phosphate ionsthat have been moving in the same chemical form between the river and the two wells.The decrease in the concentration of phosphate between river and catchments is due to the dilution effect by the groundwaterlevels, the precipitation of phosphate in the form of calcium phosphate and finally by the clays adsorption. Nonetheless, theabsence of ammonium in the catchments is due to the change in the form of nitrate nitrogen during the journey between thetwo communities as a result of oxidizing conditions

Mobility of Chromium and Tin Associated with Geochemical Dynamics in Groundwater in Meboudja Plain

AbstractIn the region of Sidi Amar Annaba South. Storage of industrial waste from the Arcelor-Mittal steel complex directly on the floor produced an infiltration of heavy metals to the under saturated and groundwater area. To know the exact origin of some pollutants and their evolution in time, monthly monitoring of water chemistry (potential hydrogen, potential of oxydo-reduction, temperature, conductivity, Oxygen, Calcium, Magnesium, Sodium, Potassium, Chlorine, sulfate, bicarbonate, Nitrate, Strontium, total Chrome, total Tin) was performed on wells for water cycle.Statistical analysis shows a common origin of chromium and tin that would be due to electroplating waste. The temporal evolution of these elements highlights the influence of several factors (potential hydrogen, potential of oxydo-reduction, rainfall and pumping) in the dissolution of these species and the evolution of the dominant aqueous species. There presentation of water points on the Eh-pH equilibrium diagram indicates that chromium may appear in the water table in two complex forms, trivalent and hexavalent by against the tin is in the hexavalent form

LAND MASTERY, MAJOR ISSUE FOR WETLANDS CONSERVATION IN RURAL AREAS: Case of Macta in northwestern Algerian.

Context and backgroundThe Macta wetland is a coveted and fragile area with a biodiversity hot-spot on the Algerian western coast and the southern shore of the Mediterranean. This rural area is affected by the increase of human activity linking, mainly, agricultural and pastoral practices. In the context of put into nature reserve for this wetland, the land mastery has become a major issue that currently represents a determining factor in the relationship between man and nature, on the one hand, and in the competition between interest groups for the exploitation of land and natural resources, on the other.Goal and Objectives:This study aims to analyze the influence of agricultural development policies and those of land on the implications of the actor’s active in the field and their interference with the initiatives to protect the Macta wetland.The objective was to identify the land and ecological issues at stake in putting into reserve this fragile rural space in order to establish a territorial development more adapted to the socio-economic and environmental conditions.Methodology:The working method adopted is based on the mapping of land using Geographic Information Systems with a diachronic approach covering the different stages of agrarian reform from the colonial period until today. The work was completed by field observations and interviews with actors active in the areaResults:Frequent changes in the policy of the agricultural sector have led to the appearance of over 9400 ha of surplus land,  or 50% of the area studied (municipality of Moctadouz), in which the interventions of the management authorities for the setting in nature reserve overlap with an agricultural development action by the locals. This has led to a number of problems represented by difficulties in the mastery of land use and land management, as well as conflicts between actors. These constraints have impacted all attempts to make the wetland a heritage site

Hydrochemical and isotopic characterization of a complex aquifer system

A methodology was developed and applied to the Tindouf basin (south-western Algeria) to understand the hydrogeology of a complex aquifer system with a limited number of data, to identify the favorable areas for the design and building of new wells, and to know whether there is still current recharge of these aquifers. The principal components analysis (PCA), diagram of deuterium versus oxygen-18, and equilibrium diagrams Mg/Na and Ca/Na were the techniques used to combine different datasets in order to identify chemical and isotopic groups, which were in turn used to define the groundwater flow paths. In addition, on the basis of thermodynamic equilibrium, it is possible to define the chemical evolution of the Tindouf basin aquifer. The results of this study are consistent with the generally accepted hydrogeological conceptual model. The combination of the different methods made possible to define and and to characterise the main groundwater flow paths from their sources to the discharge zones. These flow paths are defined by water categories, which are represented by salinity and groundwater origin. This approach can be used to analyze aquifers characterized by a lack of data and can also be useful for studying other complex groundwater basins

Investigation of the phenomena of self-organization of dislocations in a dynamically strain ageing alloy

Durant ces dernières années la déformation plastique est de plus en plus souvent étudiée du point de vue de la dynamique des systèmes complexes, caractérisée par l'auto-organisation et impliquant plusieurs échelles. Le présent travail est une étude multi-échelles de la dynamique collective de dislocations dans un alliage AlMg sujetà l'effet Portevin-Le Chatelier (PLC). Pour atteindre cet objectif nous avons réalisé l'enregistrement simultané des courbes de traction, de l'émission acoustique (EA) et du champ de déformations locales, ainsi que la caractérisation quantitative de la complexité grâce aux analyses statistique et multifractale. Le travail de thèse a permis de montrer que la manifestation apparente des processus de déformation plastique dépend de l'échelle d'observation. L'analyse de l'EA a révélé un comportement intrinsèquement intermittent et invariant d'échelles dans toutes les conditions expérimentales. Ces résultats suggèrent qu'aux échelles associées à l'EA, la plasticité peut être gouvernée par une dynamique universelle, qu'elle soit liée à l'instabilité PLC ou à un écoulement macroscopiquement homogène. Malgré le caractère ubiquitaire de cette observation, le champ de déformations locales montre des processus de déformation ondulatoires, et l'analyse statistique des chutes de contrainte révèle des échelles caractéristiques. Une hypothèse de synchronisation des avalanches des dislocations est avancée afin d'expliquer dans certaines conditions expérimentales le passage de l'échelle mésoscopique à l'échelle macroscopiqueIn recent years, the plastic deformation more and more often studied in terms of the dynamics of complex systems, which is characterized by self-organization and involves various scales. This work presents a multi-scale investigation of the collective behavior of dislocations in an AlMg alloy prone to the Portevin-Le Chatelier (PLC) effect. To achieve this goal we have performed simultaneous recording of tensile curves, acoustic emission (AE), and local strain field, as well as quantitative characterization of the complexity through statistical and multifractal analyses. The results obtained proved that the apparent manifestations of the plastic deformation processes depend on the scale of observation. The analysis of the AE data revealed an inherently intermittent and scale-invariant behavior in all experimental conditions. These results suggest that at the scales pertaining to the AE, the plasticity may be governed by a universal dynamics, be it related to the PLC instability or macroscopically homogeneous flow. Despite the ubiquitous nature of this observation, the local strain field uncovers wave-like deformation processes, and the statistical analysis of stress serrations reveals characteristic scales. Synchronization of dislocation avalanches is conjectured to explain (under some experimental conditions) the transition from the mesoscopic to the macroscopic scal

Etude des phénomènes d'auto-organisation des ensembles de dislocations dans un alliage au vieillissement dynamique

In recent years, the plastic deformation more and more often studied in terms of the dynamics of complex systems, which is characterized by self-organization and involves various scales. This work presents a multi-scale investigation of the collective behavior of dislocations in an AlMg alloy prone to the Portevin-Le Chatelier (PLC) effect. To achieve this goal we have performed simultaneous recording of tensile curves, acoustic emission (AE), and local strain field, as well as quantitative characterization of the complexity through statistical and multifractal analyses. The results obtained proved that the apparent manifestations of the plastic deformation processes depend on the scale of observation. The analysis of the AE data revealed an inherently intermittent and scale-invariant behavior in all experimental conditions. These results suggest that at the scales pertaining to the AE, the plasticity may be governed by a universal dynamics, be it related to the PLC instability or macroscopically homogeneous flow. Despite the ubiquitous nature of this observation, the local strain field uncovers wave-like deformation processes, and the statistical analysis of stress serrations reveals characteristic scales. Synchronization of dislocation avalanches is conjectured to explain (under some experimental conditions) the transition from the mesoscopic to the macroscopic scaleDurant ces dernières années la déformation plastique est de plus en plus souvent étudiée du point de vue de la dynamique des systèmes complexes, caractérisée par l'auto-organisation et impliquant plusieurs échelles. Le présent travail est une étude multi-échelles de la dynamique collective de dislocations dans un alliage AlMg sujet à l'effet Portevin-Le Chatelier (PLC). Pour atteindre cet objectif nous avons réalisé l'enregistrement simultané des courbes de traction, de l'émission acoustique (EA) et du champ de déformations locales, ainsi que la caractérisation quantitative de la complexité grâce aux analyses statistique et multifractale. Le travail de thèse a permis de montrer que la manifestation apparente des processus de déformation plastique dépend de l'échelle d'observation. L'analyse de l'EA a révélé un comportement intrinsèquement intermittent et invariant d'échelles dans toutes les conditions expérimentales. Ces résultats suggèrent qu'aux échelles associées à l'EA, la plasticité peut être gouvernée par une dynamique universelle, qu'elle soit liée à l'instabilité PLC ou à un écoulement macroscopiquement homogène. Malgré le caractère ubiquitaire de cette observation, le champ de déformations locales montre des processus de déformation ondulatoires, et l'analyse statistique des chutes de contrainte révèle des échelles caractéristiques. Une hypothèse de synchronisation des avalanches des dislocations est avancée afin d'expliquer dans certaines conditions expérimentales le passage de l'échelle mésoscopique à l'échelle macroscopiqu

Algeria's foreign policy 1979-1992 : continuity and/or change

This study analyses Algeria's foreign policy under the leadership of President Chadli Bendjadid from February 1979 until January 1992. Its aim is to investigate the extent of continuity and/or change in Algeria's foreign policy during this period. The central finding of this thesis is that "change within continuity" best describes what characterised Algeria's foreign policy under the post-1979 leadership.This thesis is divided into two parts. The First Part is composed of four chapters. Chapter One relates theoretical approaches. It examines whether or not there is a satisfactory approach that can be applied for our case study. In the same chapter, the making of Algeria's foreign policy is scrutinised through the identification and topological analysis of the key factors in the conceptualisation and implementation of Algeria's foreign policy. It also uncovers who makes Algerian foreign policy. Chapter Two identifies the guiding principles behind the formulation of Algerian foreign policy. In this chapter, reference to the FLN's past diplomatic activities is reviewed as it serves to provide a significant understanding of the context within which the fundamental principles of the policy pursued by contemporary Algeria were shaped, defined and set as the official framework for Algeria's foreign policy. Chapter Three deals with Algeria's foreign policy behaviour from 1962 to the end of 1978. A clear understanding of post-1979 Algerian foreign policy needs to rest on a review of how Algeria's foreign policy was determined and implemented in the years preceding this period and what were the dominant issues of the country's foreign policy at the time of Bendjadid's appointment.The Second Part comprises three chapters. It considers Bendjadid's leadership by exploring a number of issues/areas that came to be the focus of his government's external policy. Chapter Four relates to Algeria's policy towards it proximate neighbouring countries -Morocco-Tunisia-Libya-and the more distant Mashreq. This chapter suggests that the Western Sahara remained the central thrust of Algeria's Maghreb policy, just as it had been in the last years of Houari Boumediene's tenure (1975-1978)