Impacts of Environmental Management on the Quality of Traditional Well Water in the Soubre Region(South-West of Cote d’Ivoire)

Water supply is a global problem. A study was conducted on twelve (12) traditional wells water in Daba Dagnogo and Gnipi 2 to determine their physico-chemical quality. Two sampling campaigns (dry season and rainy season), were performed on 16 physical and chemical parameters. The results show that the water is acidic with an average pH of 6.41 ± 0.4;moderately mineralized with an average conductivity of 731.14 ± 611.98 μS·cm-1;moderately saline with an average rate of 1.56 ± 1.22. The average temperature of 28.07 ± 0.86°C is above the norm for all wells. All major ions are consistent with WHO standards except calcium and potassium. 41.67% of wells exceed the standard ammonium ion whose average was 1.43 ± 2.79 mg·L-1 nitrate and 100% with an average of 492.42 ± 434.02 mg·L-1. The ion concentrations are highest in the urban area and are higher in the dry season. The quality of the water sampled wells deteriorated. Several factors affect the degradation, namely the shallow wells, their proximity to toilet, the lack of sanitation and poor management of household waste. It will carry out a campaign to educate people to protect the immediate environment of the water points, avoiding the deposit of garbage and to provide the appropriate wells lids.

Spatial Availability of Nitrogen and Pesticides in the Surface Layers of Agricultural Soils of Tropical Hydrosystems in the Wet Season: Case of the BéréWatershed in Côte d’Ivoire (West Africa)

The objective of this study was to assess the contribution of the spatial organization of cropping systems and the physicochemical properties of surface layers of the agricultural zones soils in tropical hydrosystems to the spatial availability of nitrogen and pesticides during the wet season, such as the Béré watershed (BW) in C?te d’Ivoire. For this purpose, after mapping the spatial distribution of the BW cropping systems based on the likelihood classification methodology of satellite images of the study area, 27 samples from the 0 - 20 cm horizon of the soil surface layers of the agricultural areas were taken during the wet and agricultural season of the year 2016. The Kjeldahl method has been used to evaluate the total nitrogen concentration and high-performance liquid chromatography (HPLC) chain made it possible for the analysis of pesticide residues in the soil solutions. Geostatistical analysis and processing of spatial data and physicochemical and agrochemical soil parameters revealed that two major agricultural areas stand out in the BW, namely the Béré upstream watershed (BUW) dominated at 32.65% by annual croppings (maize, cotton, rainfed or lowland rice, market gardening, etc.) and the Béré downstream watershed (BDW) by large areas of perennial croppings (cashew nuts, cocoa, etc.), i.e. 21.47%. Agricultural soils in BW are usually of the moderately desaturated ferralitic type with a low acid pH and a quite strong temperature, such as those of tropical soils’ characteristics. However, agricultural soils in the BUW are characterized by higher proportions of sand and coarse sand. The parameters such as total porosity, cation exchange capacity, clay, organic matter, silt, fine silt, coarse silt, and potassium ions, are higher in the soils of the agricultural area of the BDW. Moreover, soils in the agricultural areas of the BUW are less rich in total nitrogen (0.84 g·kg-1) in contrast to those of the BDW (1.2 g·kg-1). On the other hand, the median concentrations of total pesticides remain very high in the BUW (193.80 μg·kg-1) in front of those of the BDW (94.81 μg·kg-1). In addition, the biological family of herbicides was the most notable in BW. The chemical families of triazines (100% detection;79.37 μg·kg-1) are the most important in the agricultural area of the BUW with the very significant presence of active molecules of pesticides such as simazine (92.86% detection;13.17 μg·kg-1). However, in the BDW, urea substitute (100% detection;44.02 μg·kg-1) dominate, including the active substance chlortoluron (84.62% detection;10.12 μg·kg-1). The presence and abundance of nitrogen and pesticides in the soils of the agricultural areas of BW are strongly linked to the intensive use of these agrochemicals in cropping systems in recent decades in West African countries, even though most of the active molecules found are forbidden in several countries, especially in European countries. These are applied to tropical agricultural soils with physicochemical characteristics favorable to their retention in wet weather, as confirmed by the case of BW’s agricultural soils. Therefore, the BW’s water resources present worrying risks of contamination during rainy events that deserve to be assessed and monitored. Hence the need to take mitigating measures to this effect in order to preserve the quality of the environment.

Physico-Chemical Characterization of Industrial Liquid Discharges of Soap Factories in Abidjan, Côte D’Ivoire

This work deals with the efficient management of industrial liquid discharges from soap factories (ILDS) in the region of Abidjan. The aim of this work is to evaluate the physico-chemical quality of these discharges as well as the different types of pollution generated. Seventeen (17) industrial soap sources were studied through fourteen (14) global pollution parameters (T, pH, electrical conductivity EC, redox potential EH, suspended matter SM, COD, BOD5, biodegradability factor BF, , , , , total iron and ). A liquid waste collection campaign was done during six weeks from February to March 2016, corresponding to a period of intensive activity of these industries. The samples were analyzed according to the norms of the French Standardization Agency (AFNOR). Results were compared with the Ivorian guide values recommended by the Classified Installations Inspection Service (CIIS). Principal Component Analysis (PCA) is allowed to evaluate the pollution induced by these factories’ rejection. In addition, Ascending Hierarchical Classification (AHC) method leads to classify soap factories into three groups according to the physico-chemical quality of their releases. Moreover, the estimation of the biodegradability factor is permitted to know the state of the biodegradability of these effluents.

Anionic Surfactants Levels in M’Koa Lake Water (Jacqueville, Cote d’Ivoire)

In this study, anionic surfactants concentrations and other physico-chemical parameters of surface water quality were assessed in the water of M’Koa Lake in the city of Jacqueville (C?te d’Ivoire). Three sampling campaigns were conducted at different seasons at six (6) sampling stations, identified in M’koa Lake by taking into account potential sources of pollution. The analyses of physico-chemical parameters were carried out using both the French AFNOR standard and the methods described by Rodier. The anionic surfactants concentrations were performed by using the methylene blue colorimetric method. The average concentrations of anionic surfactants in the water of M’koa Lake ranged from 0.23 ± 0.04 mg·L-1 to 1.43 ± 0.68 mg·L-1. They are high compared to both population density and socio-economic activities of Jacqueville’s town. These values can be explained by the characteristics of the studied Lake that do not allow enough dilution of the discharged effluent. The results indicate that M’koa Lake is subjected to harmful pollution by anionic surfactants. And among the physicochemical parameters studied, only turbidity and transparency values show water quality deterioration, favoured by wastewater discharge and direct human activities around the Lake.

N-doping offering higher photodegradation performance of dissolved black carbon for organic pollutants: experimental and theoretical studies

We investigated the influence mechanism of N-doping for dissolved black carbon(DBC)photodegradation of organic pollutants.The degradation performance of N-doped dissolved black carbon(NDBC)for tetracycline(TC)(71%)is better than that for methylene blue(MB)(28%)under irradiation.These levels are both better than DBC degradation performances for TC(68%)and MB(18%)under irradiation.Reactive species quenching experiments suggest that h and-O,are the main reactive species for NDBC photodegraded TC,while-OH and h*are the main reactive species for NDBC photodegraded MB.-OH is not observed during DBC photodegradation of MB.This is likely because N-doping increases valence-band(VB)energy from 1.55 eV in DBC to 2.04 eV in NDBC;the latter is strong enough to oxidize water to form-OH.Additionally,N-doping increases the DBC band gap of 2.29 to 2.62 eV in NDBC,resulting in a higher separation efficiency of photo-generated electrons-holes in NDBC than in DBC.AIl these factors give NDBC stronger photodegradation performance for TC and MB than DBC.High-performance liquid chromatography-mass spectrometry(HPLC-MS)characterization and toxicity evaluation with the quantitative structure-activity relationship(QSAR)method suggest that TC photodegradation intermediates produced by NDBC have less aromatic structure and are less toxic than those produced by DBC.We adopted a theoretical approach to clarify the relationship between the surface groups of NDBC and the photoactive species produced.Our results add to the understanding of the photochemical behavior of NDBC.