Evaluation of heavy metals pollution of Nokoue Lake

Toxic metals (cadmium, lead, copper and arsenic) assessment was carried out in water and sediments samples of Nokoue Lake. Except for water, a group of sediment samples was mineralized before the analysis with atomic absorption spectrophotometer. The second group of sediment samples was processed for texture analysis. The results revealed that for the physico-chemical characteristics, the pH is from 6.5 to 8.5. Four kinds of textures were identified: mud, sand, sandy mud and muddy sand. Heavy metals mean concentrations in water rose from 0.01 to 10.1 mg/L for lead and 5.84 to 8.47 for arsenic. In water, copper showed low concentrations in all sites and the values of cadmium were below the detectable limits. The mean concentrations in the sediments were: Cd (0.56 to 22.07 mg/L); Pb (3.2 to 13.94 mg/L); Cu (11.51 to 54.39 mg/L) and As (ND to 436.81 mg/L). Besides, the pattern of trace elements accumulation according to textures revealed that sandy mud and sand sediments recorded high concentrations of arsenic, mud registered high concentrations of cadmium and the sediment combining sand and mud registered high concentrations of copper. Besides, the correlation between heavy metal concentrations and pH except for arsenic.Key words: Nokoue Lake, pollution, heavy metal, texture

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

Flux des polluants liés aux activités anthropiques, risques sur les ressources en eau de surface et la chaine trophique à travers le monde : synthèse bibliographique

Cette synthèse bibliographique fait le point des différentes activités anthropiques et de leurs impacts sur la qualité des eaux de surface et la chaîne trophique. Elle a été faite à partir de la recherche bibliographique. Les activités anthropiques interfèrent sur les eaux de surface en créant des problèmes environnementaux et sanitaires. Les activités domestiques, agricoles, industrielles, hospitalières, et les activités de pêche artisanale et de tourisme, sont les plus incriminées. La pollution des eaux de surface par les métaux lourds, les pesticides, les engrais, les hydrocarbures et les organismes pathogènes, constitue un véritable problème environnemental et sanitaire. La présence des matières organiques polluantes rend difficile le traitement des eaux brutes destinées à la consommation humaine. L’utilisation accrue des pesticides en agriculture explique la présence des résidus de pesticides dans les eaux de surface en Afrique et dans le monde. Les industries et hôpitaux, de par leurs rejets d’effluents et de déchets solides dans l’environnement, sans traitement adéquat constituent une source de pollution des écosystèmes aquatiques. La présence des macropolluants et micropolluants dans les eaux de surface dégrade leur qualité, puis celle des ressources et compromet la santé de la population utilisatrice des eaux et produits halieutiques.Mots clés : Pollution, eaux de surface, écosystèmes aquatiques, espèces aquacoles, santé humaine

Contribution des Systèmes d’Information Géographique (SIG) à l’analyse de l’approvisionnement en Eau Potable dans la Commune de Kétou au Sud du Benin

Cette étude aborde le problème de l’approvisionnement en eau potable dans la Commune de Kétou au Sud du Bénin. L’objectif poursuivi était d’évaluer la distribution spatiale des ouvrages d’approvisionnement en eau potable et la satisfaction des populations de la Commune de Kétou par rapport à la demande en eau potable. La distribution spatiale, l’accessibilité et la surexploitation des ouvrages d’approvisionnement en eau potable fonctionnels ont été évalués grâce à la cartographie thématique et l’analyse spatiale. Les résultats obtenus indiquent que les infrastructures sont inégalement réparties sur le territoire de la Commune. L’arrondissement d’Adakplamè est le moins desservi en ouvrages hydrauliques tandis que l’arrondissement de Kpankou présente le plus grand nombre d’ouvrages. Plus de 30% des ouvrages disponibles sont en panne, ce qui crée une surexploitation des points d’eau fonctionnels. L’accessibilité aux différents ouvrages est acceptable seulement dans les arrondissements au Sud de la Commune. Les ouvrages fonctionnels sont surchargés par rapport aux normes de desserte en fonction du type d’ouvrage. Au vu de ces constats, il s’avèrenécessaire de prévoir la réalisation de nouveaux ouvrages et de procéder à la réparation de certaines infrastructures en panne afin de faire face aux demandes croissantes en eau potable dans la Commune.Mots clés : Distribution spatiale, ouvrages hydrauliques, inégale répartition, Kétou, département du plateau.   English Title: Contribution of GIS in the diagnosis of the drinking water supply system in the town of Kétou in south BeninThis study addresses the problem of drinking water supply in the Municipality of Kétou in southern Benin. The objective was to assess the spatial distribution of drinking water supply structures and the satisfaction of the populations of the Municipality of Kétou in relation to the demand for drinking water. The spatial distribution, accessibility and overload of the functional drinking water supply structures were assessed using an approach based on thematic mapping and spatial analysis. The results obtained indicate that theinfrastructures are unevenly distributed over the territory of the Municipality of Kétou. The district of Adakplamè is the least  concentrated in hydraulic works while the district of Kpankou presents the greatest number of works. Accessibility as a function of the time required to reach the various structures is acceptable only in the districts to the south of the Commune. Functional structures are overloaded compared to service standards depending on the type of structure. In view of these findings, it is necessary to plan for theconstruction of new structures and to repair certain broken down infrastructures in order to cope with the increasing demands for drinking water in the Municipality. Keywords: Spatial distribution, hydraulic works, unequal distribution, Kétou, plateau department

Caractérisation Physico-Chimique Et Étude De La Toxicité De La Lagune Côtière, De Togbin À GrandPopo (Sud-Ouest Bénin)

This work deals with the physicochemical characterization and the toxicity study of the coastal lagoon of Benin (from Togbin to Grand-Popo). In particular, it has to do with the study of copper and zinc. The sampling campaign was carried out by motorized boat on the 20th of December 2016. Samples were taken a few centimeters below the surface of the water. The analysis of the metals was carried out with a HACH LANGE DR2800 spectrophotometer. Copper is determined by the method of Bicinchroninate, while zinc is determined by the method of Zincover. The method used for the toxicity study is natural and is based on the inoculation of onions in the waters sampled at various proportions. The results revealed that physically and chemically, the lagoon is highly mineralized. This mineralization is due not only to the contribution of the sea to high tide, but also to salt production in Djègbadji. Concerning the concentrations of trace metallic elements, copper and zinc do not pose a risk to humans, but pose a high risk to the aquatic organisms present in the lagoon. Potentially suspected sources of copper and zinc are Ahémé Lake and the Mono River. As for the ecotoxicological study with the Allium cepa test, this test is not only influenced by metals, but also by the salinity of the water. The test revealed that the waters of the lagoon are acutely toxic, particularly at Djondji. Strategies for the protection and rehabilitation of the coastal lagoon must be undertaken by decision-makers at all levels. This, therefore, will help to prevent not only the different populations from the risks of diseases, but also increase the economy of the country through marketing and the edibility of the fish and even offer a framework of tourist scale

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

Fractionnement Géochimique Des Eléments Traces Métalliques (Etm) Dans Les Sédiments Du Delta De L’ouémé Au Bénin

Due to the inherent damages of trace elements to living organisms, the amount of bio available metal is considered to be a quantity that conditions the becoming of aquatic ecosystems. The aim of this work is to evaluate the proportion of Pb, Cu and Cd that are biologically available in the superficial sediments of the Ouémé estuary as well as the influence of environmental factors on the becoming of these metals. Fractionation of the metals was performed according to the sequential extraction method and their measurement was done by inductively coupled plasma mass spectrometer (ICP-MS). Physicochemical parameters evaluated are: granulometry, pH, cation exchange capacity (CEC), organic carbon (Corg), iron, aluminum and calcium oxides (Fe2O3, Al2O3 and CaO). Risk indices related to metal fractionation were evaluated followed by statistical processing in R 3.3.2. It appears that: 39.44% of the Cd are preferentially bound to the exchangeable fraction, 37.25% of the Pb are for the reducible fraction and 47.47% of the Cu for the oxidizable fraction. Risk levels are in the low to very high range. The richness of materials is revealed as a factor limiting the bioavailability of metals while CaO facilitates the bioavailability in high risk sites. Liquid and solid wastes from the Dantokpa market are the potential sources of metals

Viscosity solutions of second order equations in a separable Hilbert space and applications to stochastic optimal control

Ph.D.Andrzej Świȩc