The Geochemistry of some Ground and Surface water Systems in the East Gonja District of Northern Ghana

Abstract

East Gonja District is located at the South-eastern section of the Northern Region of Ghana and known to have the highest density of boreholes in the  country. A total of 38 water samples derived from 26 boreholes, 7 hand-dug wells, 2 dams and 3 rivers were studied by determining the physicochemical, trace elements and major ions compositions of these ground and surface water samples. Among the physicochemical parameters determined were  pH, EC, ORP, TDS and hardness while the trace elements included  F, Fe, Cu, Ni and Zn. Major ions determined were Mg, Ca Na, K, Cl, HCO₃ , NO₃ and SO_4. The values of the physicochemical parameters largely revealed the samples are fresh water. The major ions and their concentration distributions in the ground waters showed that the hydrochemistry of the waters is dominated by bicarbonates, calcium, magnesium and sodium ions. Saturation indexes (SI) with respect to carbonate (dolomite, calcite, fluorite and apatite) and evaporate (gypsum, anhydrite and halite) minerals, as well as activities of soluble species were also determined using the hydrochemical modelling from PHREEQC. This revealed that most of the considered ground waters are saturated with respect to calcite, dolomite, fluorite and hydroxyapatite   but   unsaturated with respect to gypsum, anhydrite and halite.

Keywords: Surface and ground water, geochemistry, major cations and anions, trace elements