Hydrochemical Characterization of Groundwater in the Sub-Prefecture of Kokumbo (Ivory Coast)

In the Kokumbo sub-prefecture, groundwater extraction related to gold panning remains a major concern, not to mention the deterioration of its quality. Among the work carried out on water resources, no scientific interest has been shown in groundwater to characterise it. The objective of this study is to contribute to the knowledge of its physico-chemical quality. In situ measurements and physico-chemical analyses using an inductively coupled plasma optical emission spectrometer (ICP-OES) were carried out on five (5) human-powered pump (HPP) water samples and six (6) well water samples collected during low and high water seasons. The results show that the physico-chemical quality of the water, which is sometimes turbid, is satisfactory in terms of the mineralization of the borehole and well water, and the pH of the boreholes, while the temperatures of the two waters and the pH of the wells do not comply with WHO standards. The levels of major ions are recommended for consumption. The waters are classified as predominantly bicarbonate-calcium and magnesium (73%) in the dry season and in the flood season, with an equal split between bicarbonate-calcium and magnesium (45.5%) and chloride-calcium and magnesium (45.5%). The elimination of materials responsible for the turbidity of certain waters by managers or populations is essential for drinking water use. The risk linked to this element means that these turbid waters are not recommended for drinking water.

Groundwater Geochemistry and Saltwater Intrusion in the Dakar Coastal Area, Senegal

Groundwater levels and water samples were collected from 20 drinking water pumping and piezometer wells in the urban area of Dakar coastal region in the year 2019. The pH-value, electrical conductivity, as well as calcium, magnesium, sodium, potassium, chloride, sulfate, bicarbonate, and nitrate concentrations were measured to assess the hydrochemical quality of the infrabasaltic aquifer in the area. The present work carried out a hydrochemical analysis to interpret the groundwater chemistry of the aquifer. The results of this chemical analysis indicate that Na+ > Mg2+ > Ca2+ > K+ was the most dominant cation sequence in the groundwater, while Cl- > HCO3- > SO42- > NO3- was the most dominant one for anions. The chemical analysis of our samples showed, that the Cl-Ca-Mg facies was dominant in the aquifer, while Cl-Na-K and HCO3-Na-K facies represent 20% and 10% of the groundwater sampled, respectively. A comparison of the measured groundwater quality in relation to WHO drinking water quality standards revealed that 80% of the water samples are suitable for drinking purposes. Ca enrichment, Simpson ratio, ratio of sodium chloride, and calculating Base Exchange (BEX) indices for the samples revealed that the groundwater is mainly affected by three factors: seawater intrusion due to aquifer overexploitation on one hand, and freshening processes and nitrate pollution, on the other, mainly caused by the groundwater flow from the unconfined aquifer.