Water quality characterization in some Birimian aquifers of the Birim Basin, Ghana

Abstract

The objective of this study was to determine the main controls on the hydrochemistry of groundwater in the study area. Mass balance modeling was used simultaneously with multivariate R-mode hierarchical cluster analysis to determine the significant sources of variation in the hydrochemistry. Two water types have been revealed in this area: (1) waters influenced more significantly by the weathering of silicate minerals from the underlying geology, and are rich in silica, sodium, calcium, bicarbonate, and magnesium ions, and (2) waters that have been influenced by the effects of fertilizers and other anthropogenic activities in the area. Mineral speciation and silicate mineral stability diagrams generated from the data suggest that montmorillonite, probably derived from the incongruent dissolution of feldspars and micas, is the most stable silicate phase in the groundwater. The apparent incongruent weathering of silicate minerals in the groundwater system has led to the enrichment of sodium, calcium, magnesium and bicarbonate ions as well as silica, leading to the supersaturation of calcite, aragonite, dolomite and quartz. Stability in the montmorillonite field suggests restricted flow conditions whereby groundwater residence time is relatively high, leading to greater contact of groundwater with the rock to enhance weathering. Cation exchange processes have also been determined to play minor roles in the hydrochemistry.

Incipient devitrification of impact melt particles at Bosumtwi crater, Ghana: Implications for suevite cooling history and melt dispersion

“…The present‐day thickness of the weathering zone varies depending upon basement lithology but reaches in average only to about 30–50 m in the Birimian metasediments (Banoeng‐Yakubo et al. ; Yidana et al. ).…”

“…), has significantly facilitated extensive and deep weathering of the rocks (Banoeng‐Yakubo et al. ). Although the true depth of the fracturing and its water‐bearing capacity is unknown (Gyau‐Boakye et al.…”

“…Most of the groundwater is hosted by fractures in the bedrock, and most importantly in the weathered zone. The present-day thickness of the weathering zone varies depending upon basement lithology but reaches in average only to about 30-50 m in the Birimian metasediments (Banoeng-Yakubo et al 2009;Yidana et al 2014). The porosity and waterbearing capacity of the unweathered basement rocks below the regolith is typically low; however, the mean porosity of unweathered Birimian phyllite-greywacke and granite lithologies found at Bosumtwi is about 8% (Plado et al 2000).…”

“…A porosity of 8%-being in saturated groundwater zone-would have provided sufficient amount of volatiles for the melt dispersion. In addition, dense fracturing-jointing developed during the Eburnean orogenic event in Paleoproterozoic, particularly in slip and shearing zones along the Birimian metavolcanic and metasedimentary sequences (Eisenlohr and Hirdes 1992;Feybesse et al 2006), has significantly facilitated extensive and deep weathering of the rocks (Banoeng-Yakubo et al 2009). Although the true depth of the fracturing and its water-bearing capacity is unknown (Gyau-Boakye et al 2008), it is nevertheless plausible to assume that the fracturing extended at the time of the impact to several km in depth to the depth of brittleductile deformation and at least the open fractures/ pores were water saturated, and provided a potential source of volatiles.…”

Groundwater Flow Patterns and Hydrochemical Facies Distribution Using Geographical Information System (GIS) in Damaturu, Northeast Nigeria

“…The Statistical Package for Social Sciences (SPSS) [22] was used for the statistical analysis. The standardized z-scores was applied for R-mode hierarchical cluster analysis (HCA) to classify the data into groups based on similarity or dissimilarity [23]. In the HCA, Squared Euclidean distance was employed as a measure of similarity/ dissimilarity among the chemical parameters.…”