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In this study, descriptive statistics, correlation matrix, multiple regression model, and geostatistical models were used to assess the contamination of groundwater with respect to trace elements in the Lower Tano river basin, Ghana, West Africa. A total number of 48 boreholes drilled across the basin with depths ranging from 18 to 60 m were used as data sources in this study. The results of the descriptive statistics showed that the average lead, iron, and aluminium concentrations exceeded the WHO permissible limits of 0.3 mg/L, 0.01 mg/L, and 0.2 mg/L respectively. Furthermore, copper, chromium, aluminium, zinc, manganese, nickel, iron, arsenic, electrical conductivity, and total dissolved solids were found to be extreme and highly positively skewed. Even though significant correlations exist among some variables, the statistical results showed that the quality of the boreholes drilled across the basin was mainly originating from geogenic and anthropogenic sources. In addition, each pair of correlated physical parameters and trace elements in the drilled boreholes were predicted using multiple regression models. Likewise, geostatistical modelling was used to assess the spatial analysis of each pair of correlated physical parameters and trace elements in the drilled boreholes. The cross-validation results revealed kriging model, as the most precise model for the spatial distribution maps for the correlated physical parameters, and correlated trace elements concentration in the boreholes drilled across the study region. The semivariogram models showed that most of the correlated physical parameters and correlated trace elements were weak moderately and strongly spatially dependent, suggesting fewer agronomic influences. The results of the spatial analysis were consistent with the multiple regression model and the Pearson correlation matrix.

The chemistry of surface water and groundwater in some communities of the Lower Tano river basin, which is a coastal region of Ghana, has been characterized. Based on the obtained analytical results, 80% of the surface water (rivers), 100% of the hand dug wells and 96% of the boreholes in the study area are generally fresh and soft. Silicate weathering is the main hydrogeochemical processes contributing to the Na+ ions and HCO3− ions in the groundwater of the basin. Gibbs diagram used to identify the mechanisms controlling the water chemistry of the basin reveals that rock weathering resulting from silicate and carbonate minerals controls majority of the surface water and groundwater chemistry in the basin. Piper trilinear plots and Chadha’s diagram, used in this study, indicate that ion exchange processes, reverse ion exchange and rock weathering are the main hydrogeochemical processes controlling the groundwater resources in the basin. Stable isotopic (δ2H and δ18O) composition measurements obtained from the study indicate that 30% of the surface water (rivers and lagoon) are less depleted and subjected to evaporation, while the remaining 70% is highly depleted with negligible to no evaporation. Also, the groundwater in the basin is likely recharged by direct infiltration of rainfall from the local rains of the basin together with other sources.