Effect of Seasonal Variation on Physicochemical Properties of Shallow Groundwater in a Typical Basement Complex Terrain of Nigeria

Abstract

Abstract
Analyses of Sixty-nine (69) groundwater samples have been carried out. This was aimed at evaluating major ions and
their origin; establishing hydro-chemical facies and determining the suitability of groundwater in a typical basement
complex terrain for drinking and irrigation purposes. Hydrochemical analyses revealed ionic dominance in the order
of Ca2+>Mg2+ during the wet season and Ca2+>Mg2+>Na++K+ in the dry season. The pattern of dominance of the
major anions is HCO3
->Cl->SO4
2- for both seasons which is an indication of change in seasonal effect. Physical
evaluation revealed that pH, turbidity and colour are higher in order of degree of pollution at the wet season than dry
season while other parameters are higher during dry season. The hydrochemical facies of groundwater during dry
season were found to be CaHCO3, (Ca+Mg)Cl, CaCl and NaCl while only CaHCO3 and (Ca+Mg)Cl are present
during wet season. The source of the ions in the waters were examined and classified accordingly as rock weathering
dominance. Correlation exists among major cations and Total Dissolved Solid with average positive correlation
coefficients of 0.71 and 0.49 for wet and dry seasons respectively, which is a clear indication of the contribution of
these ionic components to the overall mineralization. Results however showed that the water resources are suitable for
drinking and irrigation as at the time of study when compared with Standards.