Characterization of Ouémé River Quality in Upper Delta Using Water Evaluation Indices and Multivariate Analysis

Pollution represents a serious problem for the environment. The aim of this research was to assess the level of organic pollution of the Ouémé River and his physical quality. Nine physical and chemical parameters were measured in nine different stations between March and October 2016, during dry and rainy season. The methods used were those recommended by the French Association of Normalization (AFNOR). Data were subjected to descriptive statistical analysis and multivariate statistical technics, including principal component analysis (PCA) and variance analysis. The Leclercq Organic pollution index was used to assess the level of organic pollution. The values of the measured parameters suggest an organic pollution on all stations. The pollution degree varies according to the study area with contents that sometimes pass those recommended by the WHO standards. More advanced information about water quality for this study area were obtained. Therefore, this study will help stakeholders to better manage Ouémé River’s water

Quality of Drinking Water in the Town of Manta in Benin Republic

The current research was undertaken in the north of Benin Republic, to assess the pollution level of drinking water; with an emphasis on water sources (boreholes, wells, surface water, and fountain post) and water storage by households. To this end, five villages of the town of Manta were the target. The methodologywas based on chemical and bacteriological analyses of water samples collected in October 2015, from ten water sources and four households. The results of chemical analyzes, revealed that two out of five (5) boreholes sampled, had higher than normal nitrate concentrations. Two (2) wells out of three (3) had high ammonium concentrations. As far as the bacteriological aspect is concerned, water from the boreholes and wells are contaminated with fecal germs (Escherichia coli and fecal streptococcus). There is also a large presence of mesophilic aerobic germs and coliform flora in all samples. On the other hand, lithological data from drill holes, in the study area, indicate a preponderance of various schist and alterites that are depleted of fluorides and phosphate compounds. The geological cross-section shows that the aquifer in the town seems to be very homogeneous and does not indicate any tectonic structure that could explain contamination due to horizontal flow. This contamination reflects the lack of hygiene and sanitation near water storage points, the uncontrolled use of pesticides and fertilizers. The use of water protection equipment and hygiene awareness will considerably reduce pollution at the household level

Analyse Granulometrique et Cartographie des Sediments Superficiels de la Lagune Cotiere au Benin (Afrique de L’Ouest)

The current study is part of the wide-ranging issue related to the sedimentary dynamics of paralic hydro systems. This study aims to characterize the sedimentary cover of the coastal lagoon, one of Benin's four main water bodies, using the granulometric analysis procedure. Based on shallow sediment samples’, following 48 transects in the lagoon, a few laboratory processes have been undertaken, including granulometry, statistical calculus acting upon the Folk & Ward textural parameters through Excel and Origin 6.0 software, and also sandy feature mapping, while considering the ArcGIS 10.3 software performance. The grain size indexes of these facies indicate a second or poor-rate classification of medium sands, almost symmetrical, with mesokurtic acuity. The Passega diagram describes a saltation or rolling transport of these sands. The combination of Friedman’s, Moiola’s and Weiser’s diagrams reveals fluvial-origin sediments and remobilization from the coastal dune zones flanking the lagoon. At the level of the coastal lagoon, a hydrodynamic zoning is established, characterized by some insubstantial hydro dynamism of the eastern sector, impacted by the influence of the so-called Ouidah lagoon and a relatively strong hydro dynamism of the western sector corresponding to the Grand- Popo lagoon, with a speed ranging between 0.78 to 1.4 m / s towards the bottom and a flow rate of 429 m3 / s, at the Avlo beach station. Ultimately, this study made it possible to underscore the state of hydrodynamic variations observed in the lagoon, notably an opposition between eastern and western sectors, the diversity of sedimentary input sources and the design of the first lithological facies map of this paralic environment, which now stands as a vital tool for its follow-up and monitoring, in the current context of upcoming changes and unremitting alteration.Cette étude s’inscrit dans la problématique de la dynamique sédimentaire des hydrosystèmes paraliques. Elle se base sur les techniques granulométriques pour caractériser les sédiments de la lagune côtière, l’un des quatre principaux plans d’eau paraliques du Bénin. A partir des prélèvements de sédiments superficiels sur 48 transects, des travaux de laboratoire, des calculs de paramètres texturaux de Folk & Ward sur Excel et le logiciel Origin 6.0 ainsi que la cartographie des faciès via ArcGIS 10.3., ont été effectués. Les indices granulométriques de ces faciès indiquent un classement médiocre de sables moyens, presque symétrique, avec une acuité mésocurtique. Le diagramme de Passega décrit un transport par saltation ou roulement de ces sables. La combinaison des diagrammes de Friedman, Moiola et Weiser montre des sédiments d’origine fluviatile et ceux remobilisés à partir des dunes côtières adjacentes à la lagune. Un zonage hydrodynamique est également noté, caractérisé par un hydrodynamisme faible du secteur oriental ou lagune de Ouidah et un hydrodynamisme relativement fort du secteur occidental ou lagune de Grand-Popo, avec une vitesse de l’ordre de 0,78 à 1,4 m/s vers le fond et un débit de 429 m3 /s, à la station de Avlo Plage. En définitive, ce papier fait ressortir l’état de variations hydrodynamiques de la lagune, notamment une opposition entre secteurs oriental et occidental, la diversité des sources d’apports sédimentaires et la réalisation de la première carte des lithofaciès de cet environnement aquatique, outil indispensable à son suivi face à des changements futurs et à un contexte en mutation perpétuelle

Identification et évaluation de pollutions dans les zones urbaines et péri-urbaines de l'Afrique de l'Ouest (exemple de l'agglomération de Cotonou, domaine margino-littoral du Sud-Bénin)

Dans la ville de Cotonou, en République du Bénin, la concentration de la quasi-totalité des activités économiques et de l'administration pose de graves problèmes de gestion urbaine. Ces activités contribuent à divers types de pollutions. Au cours de ce travail, nous avons testé un nouvel indicateur de la pollution atmosphérique par le CO2, utilisant la valeur 13C d'une graminée annuelle de type C4, Eleusine indica. Cette méthode nous a permis de définir des zones de concentration du CO2 entre 2001 et 2004. La distribution de ces zones dépend des vents dominants provenant du littoral : SW-NE. Les résultats de mesures directes de CO2 réalisées sur différents sites dans la ville et le long des transects traversant la ville d'Ouest en Est, valident bien les observations faite sur la plante bio-indicatrice. Nous avons par la suite identifié et évalué les pollutions du sol de surface. Le sable jaune, largement utilisé comme remblaie, montre une contamination tant organique qu'inorganique à l'intérieur de la ville. Cette contamination est liée à de la déficience et de l'absence d'un réseau d'assainissement et de système de collecte des déchets mais aussi à l'usage multiple et variable des sols.Cotonou, the main city, is the hub of almost all the economic and administrative activity in the Republic of Benin, which creates serious urban management problems. These activities contribute to various types of pollution. This study focuses on two types of pollution. To study air pollution, from 2001 to 2004, we tested a new atmospheric CO2 pollution indicator, using the carbon isotopic composition of a C4 grass (Eleusine indica). This new method allowed us to define the emission zones of CO2 from road traffic and industrial activities. The distribution of pollution zones follows dominant wind directions (SW-NE). The results obtained through direct measurement of CO2, carried out at various sites in the city and along transects throughout the town, validate those obtained with the isotopic method on the biomarker Eleusine indica. We also identified and evaluated surface soil pollution in the town of Cotonou. Yellow sand, largely used as landfill, shows organic and metal contamination linked to the deficiency and the absence of a cleaning network and of waste collection system but also to the multiple and variable use of the soil.DIJON-BU Sciences Economie (212312102) / SudocSudocFranceF