Kenneth S Okiongbo and Peter A Gede
Keywords: Yenagoa, Niger Delta, aquifer, sediment colour, redox potential, iron, vertical electrical sounding, groundwater
Abstract: This study investigates the potentiality of aquifer sediment colour as a broad indicator of Fe concentration in the shallow alluvial aquifer in parts of the Niger Delta. Using Vertical Electrical Sounding (VES) curve types obtained from geoelectrical sounding, three boreholes were drilled in HA curve type locations, two in HK locations and seven in K locations. Aquifer sediment colours at the screen depths in these boreholes were either grey, off-white or brown. Correlation of the aquifer sediment colour and chemical characteristics of groundwater samples from the boreholes shows that the groundwater derived from the grey and off-white aquifer sediments is characterised by relatively higher concentration of dissolved Fe (> 0.3 to 12.3mg/L) and occur in a reducing environment (redox potential Eh ~107 – 128mV). The groundwater abstracted from the brown aquifer sands is characterised by low concentration of dissolved iron (Fe < 0.3mg/l) and occur in a mildly oxidizing environment (Eh ~134 – 164mV). The study shows that aquifer sediment colour is a reliable indicator of high and low iron concentration and can be used to locate low iron groundwater in the study area.
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