Assessment of Wells Water Quality and their Suitability for Drinking in M'Bahiakro City (Côte d'Ivoire)

The present study was carried out to assess the quality and the suitability of the well waters for drinking in M’bahiakro city (centre-east of Côte d’Ivoire). The work was performed on 71 wells in February 2012 (dry season) and June 2012 (rainy season). Groundwater levels and physico-chemical parameters (pH, temperature, electrical conductivity, redox potential (Eh), Total Dissolved Solid (TDS) and Salinity) were measured to assess the water table fluctuation and the groundwater quality. Standardized Principal Component Analysis (SPCA) was calculated to group the well waters and to evaluate their suitability for drinking according to different classes. Water table varies between 125 and 135 m during the dry season and between 127 and 136 m during the rainy season with a West-Est flow direction. The recharge values ranged between 0.57 m and 5.57 m. Wells waters are generally acidic (pH<6.5), high mineralized with conductivities and Total Dissolved Solids (TDS) respectively above 600 µS/cm and 300 mg/l. Well water salinity values ranged between 0.30 and 0.5%. The Standardized Principal Component Analysis (SPCA) allowed distinguishing three important groups of water within M’bahiakro area: the first group of wells with high mineralized water, the second group of wells with high potential redox (Eh) and the third group of wells with pH closer to neutral. The first and second groups are not very suitable for drinking because they are suspected of being contaminated by anthropogenic sources such as septic tanks and wild dump. Waters of these wells need to be treated before any domestic use

Evaluation de la Contamination Chimique des Eaux Souterraines par les Activités Anthropiques : Cas de la Zone d'Ity-Floleu Sous-Préfecture de Zouan- Hounien, Ouest de la Côte d'Ivoire

L’objectif de cette étude vise à évaluer la qualité saisonnière des eaux souterraines afin d’expliquer l’origine de leur pollution dans le département Zouan-Hounien. Les paramètres physico-chimiques in situ (température, conductivité, total des sels dissous, salinité, pH, potentiel redox, turbidité et oxygène dissous), les concentrations en éléments nutritifs (NO3-, NO2-, NH4+, PO43-, SO42-), majeurs (Ca, Fe, K, Mg, Mn et Na) et traces (As, Cd, Cu, Ni, Pb et Zn) ont été mesurés sur deux années successives. Les analyses physico-chimiques faites avec un multiparamètre montrent que les eaux sont acides avec un pH moyen de 4,96 en saison sèche et de 4,14 en saison pluvieuse; la conductivité électrique moyenne est de 78,14 μS.cm-1 en saison sèche et 48,43 μS.cm-1 en saison pluvieuse. La turbidité avec une valeur moyenne de 4,14 NTU en saison sèche et de 29 NTU en saison pluvieuse affecte beaucoup la qualité de ces eaux de consommation surtout en saison pluvieuse. Les teneurs en nitrates dans toutes les stations ne respectent pas les normes OMS en toute saison et celles des phosphates pendant la saison sèche. Les concentrations de Fe et du Pb sont généralement supérieures aux normes OMS alors que celles des autres éléments le sont parfois. Le calcul de l’indice de qualité (WQI) a montré que pendant la saison sèche 85,7% des eaux étudiées sont impropre à la boisson et pendant la saison pluvieuse 28,6%. Les&nbsp;analyses en Classification Hiérarchique Ascendante (CHA) et en composante principale (ACP) montrent que la pollution est due aux activités anthropiques. The objective of this study is to assess the seasonal quality of groundwater in order to explain the origin of its pollution in the Zouan- Hounien department. In-situ physico-chemical parameters (temperature, conductivity, total dissolved salts, salinity, pH, redox potential, turbidity and dissolved oxygen), nutrient concentrations (NO3 - , NO2 -, NH4 +, PO4 3-, SO4 2-), major (Ca, Fe, K, Mg, Mn and Na) and traces (As, Cd, Cu, Ni, Pb and Zn) were measured over two successive years. The physico-chemical analyses made with a multiparameter show that the waters are acidic with an average pH of 4.96 in the dry season and 4.14 in the rainy season; the average electrical conductivity is 78.14 μS.cm-1 in the dry season and 48.43 μS.cm-1 in the rainy season. Turbidity with an average value of 4.14 NTU in the dry season and 29 NTU in the wet season greatly affects the quality of this drinking water, especially in the wet season. Nitrate levels in all stations do not meet WHO standards in all seasons and phosphate levels in the dry season. The&nbsp;concentrations of Fe and Pb are generally higher than WHO standards, while those of other elements are sometimes higher. Calculation of the quality index (WQI) showed that during the dry season 85.7% of the water studied is unfit for drinking and during the rainy season 28.6%. The analyses in Ascending Hierarchical Classification (AHC) and Principal Component Analysis (PCA) show that the pollution is due to anthropogenic activities

Caracterisation De La Dynamique D’occupation Du Sol Et De La Morphologie De La Lagune Aby Dans L’espace Du Parc National Des Îles Ehotile ; Sud-Est De La Cote d’Ivoire

Les aires protégées, qui regorgent la plupart du temps d’importantes valeurs naturelles et culturelles, subissent d’énormes pressions anthropiques qui fragilisent leur intégrité. Dans le réseau des aires protégées de Côte d'Ivoire, le Parc national des Îles Ehotilé (PNIE), archipel de six (06) îles, constitue un lieu de forte attraction à cause de la beauté de ses paysages. Cependant, malgré ses atouts naturels et culturels, ce parc est de plus en plus menacé par les pressions anthropiques. Ce travail a pour but d’étudier la dynamique d’occupation du sol et l’évolution de la morphologie de la lagune Aby dans l’espace du Parc national des Îles Ehotilé. Le traitement des images satellitaires a montré une disparition de la forêt de plus de 60% et l’augmentation des aires de cultures et jachères et des bâtis de 1989 à 2018. La carte bathymétrique de la lagune Aby dans l’espace du PNIE fait apparaître une morphologie irrégulière sur l’ensemble du secteur étudié, avec des hauts fonds par endroits. Les sédiments qui comblent le fond de la lagune sont constitués de vases, de sables fins et de sables moyens. Les sables présents dans les sédiments sont majoritairement fins à moyens avec la présence de quelques grains grossiers. La morphologie de la lagune marquée par des hauts fonds et la présence importante de vase et de sables fins révèlent des phénomènes d’envasement. La forme arrondie à subarrondie des grains de sable et leurs aspects luisants montrent que les sédiments dans l’espace des îles Ehotilé ont une origine éloignée des îles. Ils ont une origine continentale et une origine marine. Protected areas, which often comprises of very important natural and cultural values, are under enormous anthropogenic pressures that undermine their integrity. In the network of protected areas in Côte d'Ivoire, the Ehotilé Islands National Park (EINP), an archipelago of six (6) islands, is a place of great attraction because of the beauty of its landscapes. However, despite its natural and cultural assets, this park is increasingly threatened by anthropogenic pressures. This paper focuses on the study of the land use dynamics and morphological evolution of the Aby Lagoon within the Ehotilé Islands National Park area. The processing of satellite images has shown that the forest has disappeared by more than 60% and that the areas under cultivation, fallow land, and buildings have increased from 1989 to 2018. The bathymetric map of the Aby Lagoon in the EINP area shows an irregular morphology over the entire study area, with shallow water in some areas. The sediments that fill the bottom of the lagoon are made up of mud, fine sand, and medium sand. The sands present in the sediments are mostly fine to medium sands with some coarse grains. The morphology of the lagoon, marked by shallow waters and the significant presence of mud and fine sands, reveals siltation phenomena. The rounded and sub rounded shape of the grains of sand and their shiny appearance show that the sediments in the space of the Ehotilé Islands have an origin far from the islands. In addition, they both have a continental and a marine origin

Variabilite Des Extremes Pluviometriques Sur Le Bassin Versant De La Riviere Bia (Sud-Est, Cote d’Ivoire)

Climate change is a reality which affects many climatic variables, including precipitation. The objective of this article is to study the extreme rain variability from a historical database (1941 - 2000). For this purpose, eleven (11) rainfall indices were calculated at the Adiaké, Bianouan, Ayamé, and Agnibilekro rainfall stations in Côte d'Ivoire. Due to lack of data on daily rainfall on the Ghanaian section of watershed, nine (9) monthly precipitations indices were estimated from monthly rainfall at the Enshi and Buakuc stations. The trend analysis of the precipitations indices show that a generalized downward was most significant in Adiaké compared to other stations. Furthermore, indices extreme thresholding (P99, P99p, P99,5 and P99,5p) have experienced a stable trend and a stationary evolution. All steps were detected in the non-stationary indices mostly observed after 1980 (late break) and before 1960 (precocious break)

Validation of HPLC-UV Patulin Determination Method in Traditional Juices From Côte d’Ivoire

Object: The need to reduce dietary mycotoxins exposure, requires development of efficient analytical methods to assess mycotoxins level in food. The purpose of this study was to validate HPLC-UV method for patulin determination in traditional juices made of dry Guinea sorrel flowers or ginger rhizomes. Material and Methods: Patulin was extracted with ethyl acetate and purified with sodium bicarbonate solution (14 g/L). Elution of patulin was realised in isocratic mode with mobile phase consisting of acetonitrile-water (10/90 : v/v). Patulin was detected at 276 nm (UV). An amount of patulin was added to neutral portions of juices and the recovery rates were estimated after extraction. Results: The retention time was 5.03 min and the coefficient of determination of the calibration range (100 - 1500 μg/L) was 0.9994. Detection and quantification limits were respectively 1.4 μg/L and 4.6 μg/L for the two matrices. The recovery rates were 75.09 ± 0.27% and 75.27 ± 0.64% respectively for ginger and Guinea sorrel juices. Patulin was detected in 55% of ginger juice and 70% of Guinea sorrel juice. Patulin contents of&nbsp;15% of ginger juice and 40% of Guinea sorrel juice were above the maximum level of patulin (50 μg/L) allowed in juices. Conclusion: This method may be used for patulin detection in these traditional juices because its recovery rates were acceptable and limit of quantification (4.6 μg/L) was largely bellow the maximum level of patulin (50 μg/L) allowed in juices. &nbsp

Adsorption du benzo(a)pyrène sur du charbon activé à base de coques de coco provenant de Côte d’Ivoire

L’accumulation des Hydrocarbures Aromatiques Polycycliques (HAP) dans l’environnement est une préoccupation mondiale du fait de leur persistance et de leur toxicité. l’Union Européenne a ainsi jugé seize HAP comme « préoccupants », parmi lesquels le benzo(a)pyrène est l’un des plus toxiques. La dépollution du benzo(a)pyrène contenu dans les eaux a ainsi été étudiée par adsorption sur charbon activé préparé à partir de coques de noix de coco. La concentration résiduelle en benzo(a)pyrène et l’influence de la masse de charbon activé étudiées par Chromatographie Liquide à Haute Performance (CLHP) ont montré que la quantité de benzo(a)pyrène adsorbée dans l’eau croissait avec la masse de charbon activé introduite. L'adsorption du benzo(a)pyrène a suivi les modèles de Freundlich et de Langmuir et a obéit à la cinétique d’ordre 2; avec une constante thermodynamique (Kad2) de 0,0706 g.μg-1.min-1. Aussi, le paramètre d'équilibre k inférieur à 1 et le facteur d'hétérogénéité n compris entre 0,5 et 1 ont indiqué que l'adsorption du benzo(a)pyrène dans l'eau était favorable, cependant le charbon étudié a présenté un pouvoir adsorbant faible pour l’adsorption du benzo(a)pyrène. Ainsi, Le charbon activé à base de coques de coco est donc un moyen limité de dépollution du benzo(a)pyrène.© 2015 International Formulae Group. All rights reserved.Mots clés: Adsorption, charbon activé, benzo(a)pyrène, isotherme, cinétiqueEnglish Title: Benzo(a)pyrene adsorption on activated coal based on coconut shells from Côte d'IvoireEnglish AbstractPolycyclic Aromatic Hydrocarbons (PAHs) accumulation in environment is a world preoccupation, due to their persistence, toxicity and carcinogenic character for the food chain. The European union judged sixteen thus among them " preoccupying ", among which the benzo(a)pyrene is one of the most toxic. Thus, removal of benzo(a)pyrene from waters has been studied by adsorption on activated carbon prepared from raw coconut cockles. The vestigial concentration in benzo(a)pyrène and the influence of activated carbon mass studied by a High Performance Liquid Chromatography (HPLC), showed that the quantity of benzo(a)pyrene adsorbed in  water grows with carbon mass introduced. Benzo(a)pyrene adsorption follows the Freundlich and Langmuir models and it obeys the kinetics of order 2; with a thermodynamic constant (Kad2) of 0,0706 g.μg-1.min-1. Also, the balance parameter k lower to 1 and the heterogeneity factor n comprise between 0,5 and 1 indicate that benzo(a)pyrene adsorption in water is favorable, however the studied carbon presents a weak adsorption power for benzo(a)pyrène. So, activated carbon prepared from coconut cockles is therefore a limited method of benzo(a)pyrene removal from waters.© 2015 International Formulae Group. All rights reserved.Keywords: Adsorption, activated carbon, benzo(a)pyrene, isotherm, kinetic

Assessment of Spatio-Temporal Changes of Land Use and Land Cover over South-Western African Basins and Their Relations with Variations of Discharges

West African basins play a vital role in the socio-economic development of the region. They are mostly trans-boundary and sources of different land use practices. This work attempts to assess the spatio-temporal land use and land cover changes over three South Western African basins (Volta, Mono and Sassandra basins) and their influence on discharge. The land use and land cover maps of each basin were developed for 1988, 2002 and 2016. The results show that all the studied basins present an increase in water bodies, built-up, agricultural land and a decline in vegetative areas. These increases in water bodies and land use are as a result of an increase in small reservoirs, of dugouts and of dam constructions. However, the decline in some vegetative clusters could be attributed to the demographic and socio-economic growth as expressed by the expansion of agriculture and urbanization. The basic statistical analysis of precipitation and discharge data reveals that the mean annual discharge varies much more than the total annual precipitation at the three basins. For instance, in the entire Volta basin, the annual precipitation coefficient of variation (CV) is 10% while the annual discharge CV of Nawuni, Saboba and Bui are 43.6%, 36.51% and 47.43%, respectively. In Mono basin, the annual precipitation CV is 11.5% while the Nangbeto and Athieme annual discharge CV are 37.15% and 46.60%, respectively. The annual precipitation CV in Sassandra basin is 7.64% while the annual discharge CV of Soubre and Dakpadou are 29.41% and 37%, respectively. The discharge varies at least three times much more than the precipitation in the studied basins. The same conclusion was found for all months except the driest months (December and January). We showed that this great variation in discharge is mainly due to land use and land cover changes. Beside the hydrological modification of the land use and land cover changes, the climate of the region as well as the water quality and availability and the hydropower generation may be impacted by these changes in land surfaces conditions. Therefore, these impacts should be further assessed to implement appropriate climate services and measures for a sustainable land use and water management

Impact of Meteorological Drought on Streamflows in the Lobo River Catchment at Nibéhibé, Côte d’Ivoire

International audienceThe management of water resources in watersheds has become increasingly difficult in recent years due to the frequency and intensity of drought sequences. The Lobo River catchment, like most tropical regions, has experienced alternating wet and dry periods. These drought periods have a significant impact on the availability of water resources in the basin. The objective of this study is to analyse the impact of meteorological drought on flows in the Lobo River catchment. Therefore, using the Normalized Precipitation and Evapotranspiration Index (SPEI) and the Drought Flow Index (SDI), the characteristics of droughts were studied. The results of this study show that meteorological droughts were more frequent than hydrological droughts in the Lobo River watershed. However, the hydrological drought was longer and more intense than the meteorological drought. The greater relationship between meteorological and hydrological drought was observed at the Daloa and Vavoua station (0.43 < r < 0.50) compared to the Zuenoula station (r < 0.5). In addition, there was a resumption of precipitation and runoff between 2007 and 2013 in the basin. The study of these climatic trends would be very useful in the choice of management and adaptation policies for water resources management

Caractérisation des occurrences de sécheresse dans le bassin hydrologique de la Bia transfrontalier entre la Côte d’Ivoire et le Ghana : contribution des chaînes de Markov

Cette étude analyse l’occurrence au cours de la période 1901-2009 des sécheresses dans le bassin de la Bia en utilisant des modèles de chaînes de Markov. À partir des données pluviométriques annuelles de six stations (Ayamé, Bianouan, Agnibilékro, Enchi, Buakuc et Sunyani), le test sur les tendances séquentielles avec l’indice standardisé de sécheresse pluviométrique a confirmé l’existence de trois grandes tendances durant le dernier siècle. On observe une période humide de 1901 à 1945, suivie d’une période normale de 1946 à 1970, et une période sèche de 1971 à 2009. Une comparaison de matrices de Markov 1 et 2, entre les trois sous-périodes (1901-1945 ; 1946-1970 ; 1971-2009) et la période totale considérée (1901-2009) montre une modification profonde de la répartition des sécheresses dans les différentes stations. L’étude de la persistance de la sécheresse, en utilisant les chaînes de Markov, a montré que la probabilité d’avoir une année sèche après une année sèche est plus importante à partir de 1970 et est accentuée au centre du bassin. La probabilité d’avoir deux années sèches successives est plus importante au nord qu’au centre du bassin. La probabilité d’avoir trois années sèches successives est sensiblement élevée (entre 0, 54 et 0, 70) sur tout le bassin. La période de retour d’une sécheresse aussi longue est comprise entre 10 et 30 ans