Variation saisonnière des paramètres abiotiques de la lagune Aghien (Côte d’Ivoire)

Objectifs: Les autorités dans la quête d’une source d’eau complémentaire pour alimenter en eau potable la population d’Abidjan (Côte d’Ivoire) sans cesse croissante ont envisagé exploiter la lagune Aghien. Ce présent travail a pour objectif d’améliorer les connaissances sur la variation spatiale et saisonnière des paramètres abiotiques de la lagune Aghien.Méthodologie et résultats: Pour atteindre ce but, quatre campagnes d’échantillonnages ont été menées. Ainsi, les échantillons d’eau ont été prélevés de manière saisonnière dans onze (11) stations reparties sur l’ensemble de la lagune. Les paramètres tels que la température, le pH, la conductivité, l’oxygène dissous, le potentiel redox ont été mesurés in situ. La matière en suspension, le phosphate, le nitrate, le nitrite, l’ammonium, la demande chimique en oxygène (DCO) et la demande biochimique en oxygène cinq jours (DBO5) ont été mesurés selon les méthodes conventionnelles ou au laboratoire. Les résultats ont montré que les eaux de la lagune Aghien présentent un pH en général proche du pH neutre (pH entre 6,94 et 7,85). Les teneurs en Plomb sont supérieures à la norme. Les concentrations élevées du plomb dans la lagune Aghien constituent donc un danger potentiel. L’analyse saisonnière a donné des valeurs élevées en ammonium, en phosphate, en nitrite, en DCO, en DBO5, en conductivité, en oxygène dissous respectivement en petite et grande saison des pluies ainsi que de faibles valeurs de potentiel redox pendant la petite saison pluvieuse. Les paramètres tels que les MES, la turbidité et le nitrate enregistrent des valeurs plus marquées en petite saison sèche.Conclusions et application des résultats: Les résultats de cette étude montrent que les eaux de la lagune Aghien sont menacées par les effluents domestiques à caractère biodégradable. Les concentrations en sels nutritifs sont encore dans la limite de l’acceptabilité. Cependant, les zones sous influence continentale ont enregistré les concentrations les plus élevées des paramètres de pollution. Il est nécessaire de mettre en place un mécanisme de surveillance chimique en respectant toutes les normes de protection de la lagune Aghien.Mots clés: Lagune Aghien-paramètres abiotiques- saison-pollutionEnglish Title: Seasonal variation of the abiotic parameters of the waters of the Aghien lagoon (Côte d’Ivoire)English AbstractObjectives: The government seeking to provide the population of Abidjan with clean water apply, envisioned to exploit the Aghien lagoon as a supplement source of water. The aim of this work is to improve the knowledge on the spatial and seasonal variation of the abiotic parameters of the Aghien lagoon.Methodology and results: Four sampling campaigns were conducted on a seasonal basis from February to November 2016 in eleven (11) stations spread over the lagoon. Parameters such as temperature, pH, conductivity, dissolved oxygen, redox potential were measured in situ and suspended solids, phosphate, nitrate, nitrite, ammonium, chemical oxygen demand (COD) and biochemical oxygen demand five days (BOD5) by conventional chemical methods. The results showed that the waters of the Aghien lagoon have a pH generally close to the neutral pH (pH between 6.94 and 7.85). The heavy metal studies are mainly absent in the water. The quantity of plumb is higher than normal. So the higher concentration of plumb in the Aghien lagoon constitutes a potential danger. Seasonal analysis yielded high values of ammonium, phosphate, nitrite, COD, BOD5 and conductivity, oxygen dissolved respectively in small and large rainy season as well as low values of redox potential during the short rainy season. Parameters such as suspended solids, turbidity and nitrate recorded higher values in the short dry season.Conclusion and applications of results: The results of this study also show that the waters of the Aghien lagoon are threatened by domestic biodegradable effluents. Concentrations of nutrient salts are still within the limits of acceptability. However, areas under continental influence have recorded the highest concentrations of pollution parameters. It is necessary to set up a chemical monitoring mechanism respecting all the protection standards of the Aghien lagoon.Keywords: Aghien lagoon, abiotic parameters, clean water, heavy meta

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 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 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

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

Effects of Water Stress on the Agromorphological Parameters of Two New Maize (Zea mays L.) Lines (L36 and L71) Obtained from the Variety EV8728

Maize (Zea mays L.) or Indian wheat is the most cultivated cereal in the world and the first in terms of quantity before wheat. Its cultivation is confronted with the climate change which causes drought, and this last one reduces considerably its production. The objective of this experiment is to select maize (Zea mays L.) varieties resistant to water stress using gamma irradiation. Its aim is to characterize agromorphologically two maize lines derived from the gamma irradiated variety EV8728. This study took place in Daloa (Ivory Coast). The plant material consisted of maize plants obtained by self-fertilization after five cycles from seeds of the variety EV8728 irradiated with gamma rays at a dose of 300 grays. Observations and measurements were made on the number and area of leaves, height and diameter of maize plants, male and female flowering parameters (date of panicle appearance, pollen grains, cob and silks) and number of spikelets, cob insertion height (CIE), panicle height and internode length. At the 58th das, the highest number of leaves (18.76) was observed in the plants of line 36 watered at capacity in field S0. On the other hand, the number of leaves (16.04) was lowest on the plants of the same line under severe stress (S2). Regardless of the type of stress applied, the plants of the control EV8728 always dominate, while the most stunted are those of the line L36. The date of panicle appearance (DAP) was early with the EV8728 control compared to the tested lines (L36 and L71), while the date of pollen appearance (DAGP) was about 4 d after the panicle was visible. Under moderate stress, a delay in flowering (anthesis) is observed in EV8728 and line L71 while there is no change in date for line L36

Ultra-fast and highly efficient hybrid material removes Cu(II) from wastewater: Kinetic study and mechanism

Water pollution by toxic elements represents a significant risk to the environment and human ecosystem, and a number of efforts are developed to find a suitable solution. In this work, a new adsorbent based on silica gel as an inert material modified on surface by a pincer ligand was prepared. The hybrid material has been synthesized via a simple Schiff base reaction and characterized by several relevant physical methods. The adsorbent shows an extremely rapid efficiency in removal of copper (less than 8 min) with maximum sorption capacity of 1.90 mmol g−1 and a rapid efficiency for zinc, cadmium and lead (less than 20 min) with adsorption capacities 0.52, 0.49 and 0.43 mmol g−1, respectively. A kinetic study shows that the sorption can be described by a pseudo second-order model, and that the process is thermodynamically spontaneous and endothermic. The adsorbent shows a high selectivity to Cu(II) and a great reusability after five adsorption-desorption cycles. Theoretical, energy dispersive X-ray fluorescence (EDX) and Fourier transform-infrared spectroscopy studies demonstrate that the uptake occurs by a coordination reaction between metal ions and the pincer ligand on the surface of the adsorbent. The efficiency of this new hybrid material was confirmed in removal of Cu(II) from real water samples originating from Abidjan Atlantic sea bay, one of the most polluted region in West Africa, as well as from rivers located near Oujda, Morocco

Phytoplankton Composition and trophic state of Guessabo lake (Upstream in Buyo lake, Ivory Coast)

Objectives: The trophic quality of Guessabo Lake (Ivory Coast) under the influence of fishing and agriculture was analysed starting according from the phytoplankton composition. Methodology and results: Sampling spatio-temporal in pelagic zone were made from a plankton net and supplemented with an integrated sampler. A total of three hundred and forty six species were identified. The groups, by orders of prevalence are, Chlorophyta with 164 species (48 %), Euglenophyta with 64 species (19 %), Cyanobacteria represented by 53 species (16 %), Bacillariophyta with 50 species (15 %) and, the other groups (Pyrrophyta, Chrysophyta and Xanthophyta) represented by 15 species (4 %). On the level of sampling stations of Guessabo Lake, 239 species were identified in Guemon sector against 231 and 257 species respectively in bed of the lake and Haut Sassandra sector. Concerning Guemon sector, 181 species were recorded at station G1 and 192 at station G5. In bed of lake (Channel), 154 species were listed at station G2, whereas 157 and 168 species were observed respectively at stations G4 and G6. For Haut Sassandra, stations G3 and G7 respectively presents 208 and 211 species. During this study, 103 species constant were listed against 66 species additional and 170 species accidental. In the floristic list, 73 species are common to all sampling stations. Sorensen index showed a similarity between the sectors and sampling stations. Trophic index based on Phytoplankton composition indicated that lake is from mesotrophy to eutrophy state. Key words: Phytoplankton, lake, mesotrophy, eutrophy; Ivory Coast

Abstracts of the 1st International Colloquium in Mine & Society

This book presents the abstracts of the selected contributions to the First International Colloquium on Mines and Society (CIMS) organized by The Higher Institute of Mining and Geology of Boke. The theme of this colloquium was "Mining and Sustainable Development, a major challenge for an Emerging Africa" which aims to bring together teachers, researchers, and Professionals from different backgrounds in order to exchange the results of their research work, share their points of view on the issue of mining and sustainable development. It also aims to define, in a collaborative and inclusive manner, research prospects or future projects between all the actors involved in this field. Colloquium Title: 1st International Colloquium in Mine &amp; SocietyTheme: Mining and Sustainable Development, A Major Challenge for an Emerging AfricaColloquium Date: 20-22 May 2022Colloquium Location: A L’Hôtel Rio Nunez de BokeColloquium Organizer: The Higher Institute of Mining and Geology of Bok