Groundwater pollution and risk assessment using indexed-based models: a case study of Igbo-Etiti area, eastern Nigeria.

Water is one of the most abundant resources on earth not evenly distributed. Due to the high shortage of water sources in Igbo-Etiti and intensive agricultural practices in the area, assessment of groundwater pollution and its potential risk to contamination is imperative, as its remediation when contaminated is extremely challenging. Vertical electrical sounding (VES) and physicochemical analysis were carried out in twenty (20) locations and five groundwater samples, respectively, with the aim to evaluate the groundwater pollution indices and the ecological and human health risk associated with its pollution. The VES results delineated five geologic layers and ten characteristic curve types. The fourth layer with the aid of the VES results constrained by the borehole lithologic information on the water bearing geologic unit was delineated as the major exploitable aquifer layer. Results of groundwater vulnerability to pollution classified the area into low (15%), moderate (60%), and high (20%) vulnerability. Physicochemical analysis results on the studied groundwater revealed acidic (pH 4.6) to alkaline (pH 7.2) groundwater conditions. Pollution index of groundwater results delineated a moderate to very high pollution index, with cadmium and arsenic consistently identified as the heavy metals contaminating the groundwater. Ecological risk assessment revealed a moderate to very high integrated potential ecological risk, while human health risk results delineated a target hazard index greater than one in all the studied groundwater samples. This study will serve as a guide to the residents and society in sustainable development decision-making that will preserve the quality of the study area groundwater.

Geoelectric Evaluation of Aquifer Potential and Vulnerability of Northern Paiko, Niger State, Nigeria.

This study was carried out using vertical electrical sounding (VES) to evaluate the groundwater potential and the aquifer protective capacity of Northern Paiko. Sixty vertical electrical soundings were obtained across the study area using Schlumberger electrode configuration. Three to four geoelectric layers were delineated from the interpreted results. The stratigraphy of the subsurface shows: topsoil (62.8-3082 Ωm), weathered layer (15.2-80 368 Ωm), fractured layer (191-236 672 Ωm), and the fresh basement (79.9-308 865 Ωm). The weathered layer was delineated as the major aquiferous horizon. From the results, the resistivity, thickness, and longitudinal conductance maps were drawn. It was observed that groundwater potential is low in about 76.7% of the study area. This study has also shown that the aquifer protective capacity of most parts of the study area is poor (83.3%), thus rendering the aquifer vulnerable to contamination.