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

Microbial Risk Assessment for Agricultural Production Cycle of On-site Resource Oriented Sanitation Systems: A Case of Burkina Faso

On-site resource oriented sanitation system is one of expectable concepts to address a protection of water resources in developing countries due to low installation cost and resource recovery from human excretes. The present study investigated fates of indicators and pathogens originated from greywater and compost in soil to assess microbial risks when the greywater and compost are reused. Compost and greywater obtained from pilots in Burkina Faso were amended in experimental field with lettuce cultivation and the fate of pathogens in the soil was measured. The results suggested that (i) bacterial fates in compost reuse were fitted to log normal linier and those in greywater were maintained in field soil (ii) the bacterial end-off kinetics in Soudano-Sahelian climate were more rapid than that of reference values. (iii) The reduction of E. coli and Salmonella in the present condition was significantly different but that of Salmonella and Enterococci had no difference. (iv) Effect of contaminated soil on annual risk probability was lower than direct handling of greywater and compost but not negligible. The present assessment also suggested that presented current model were required further technical improvement from the view of the biological risks

Impact of climate and land use/land cover change on Lobo reservoir inflow, West-Central of Côte d'Ivoire

Study region: Lobo River Catchment (Côte d’Ivoire) Study focus: In this study, four regional climate models (RCMs) (RC4; CCLM4–8–17; RACMO22T and REMO) for the 2030 and 2050 periods compared to the reference period (1986–2005), combined with a simulation of land use and land cover (LULC) with Land Change Modeler, are used to drive the CEQUEAU model to quantify their impact on inflows to the Lobo River reservoir. 1988–2006 is used as a calibration period, whereas 2007–2015 is used for the validation. Three scenarios were used. First, varying LULC and keeping climate parameters static over the baseline period (scenario 1); in scenario 2, varying RCMs and keeping LULC static over the baseline period and in scenario 3, simultaneous variation of LULC and RCMs. New hydrological insights for the region: CEQUEAU showed good performance during calibration and validation: NSE (0.7, 0.75); R² (0.83, 0.65); PBIAS (14.1%, 12%) and RMSE (0.83, 2.15). The results show that a decrease in precipitation by 2030 (−14.6%), by 2050 (−15.2%) under scenario 2 (RCP 4.5 and 8.5) and by − 6.1% under RCP 4. 5 (Scenario 3), we observe an increase in runoff of 10.8–18.87% (Scenario 1), 1.2–4.46% (RCP4.5), 3.35% and 2.7% (RCP8.5) (Scenario 2) and 6.58–11.83 (RCP 4.5), 14.83–17.72% (RCP 8.5) (scenario 3). Changes in LULC were identified as the main causes, rather than climate variability