TITLE
Preliminary investigation and extent of hydrogeochemical concentration for groundwater exploration using electromagnetic method of terrain conductivity variation and analytical technique in Papalanto, South-West Nigeria
AUTHOR(S)
Ishola, S.A.
ABSTRACT
Ground conductivity measurements were undertaken with Geonics EM 34-3 along 5 traverses with profile lengths varying between 160 and 200m while 50 water samples (25 each from boreholes and hand-dug wells) were collected and analyzed from existing water sources using standard techniques in Papalanto District within Dahomey basin South-West Nigeria. Comprehensive geophysical fieldworks were done adopting Frequency Domain Electromagnetic Method (FDEM) to ascertain both the vertical and lateral variations of subsurface conductivity probing depths of 20 m, 40 m and 60 m seeking different investigated depth. The EM data were acquired at 500 m intervals along 10 profiles. The Vertical Dipole Moment (VDM) in the first layer exhibited the highest and lowest true conductivity of 134.31 and 78.9 mmho/m for EMIPAP1 and EMPAP6 respectively and the corresponding Horizontal Dipole Moment (HDM) exhibited the highest and lowest true conductivity values of 1141.92 and 118.0 mmho/m for EMPAP5 (2nd layer) with depth of 9m in HDM and 14m in VDM and EMPAP1 (1st layer) respectively. Lowest true conductivity values of 84.55 and 122.0 mmho/m were recorded in the second layer for VDM and HDM respectively. The highest recorded true conductivity values in the first layer were 133.33 mmho/m (EMPAP1) and 167.48 mmho/m in EMPAP7 (depth 7.8m in HDM and 9.2m in VDM) respectively. The highest depth of penetration respectively recorded for HDM and VDM in the first layer were 33m in EMPAP10 and 14m in EMPAP1 and EMPAP2 while the lowest depth of penetration respectively recorded for HDM and VDM in the first layer were 2m in EMPAP3 alongside EMPAP6 and 6.5m in EMPAP8 as the depths of penetration remained indeterminate in the second layer due to current termination. The output of water quality analyses revealed that Cl− concentrations were found to be generally much more prominent in both water sources Cu2+, Pb2+, Mn2+ and Al3+ sometimes Ni concentrations were prominent as potential Toxic Elements and were found to be higher in hand-dug wells than in Boreholes. The observed high concentration Pb2+ and Cu2+ in the groundwater sources could be attributed to the activities in the study area. The qualitative interpretation of EM results identified areas of hydrogeological importance and forms a predictive and suggestive basis for Vertical Electrical Sounding (VES) investigation; points of positive EM anomalies were considered as priority area for prospective groundwater development necessitating more advanced groundwater exploration techniques and water quality treatment like nanofiltration and reverse osmosis to be undertaken in the study area.
DOI
https://doi.org/10.62252/NSS.2025.1036
PAGES: 623-661
How to cite this article:
Ishola, S.A. 2025. Preliminary investigation and extent of hydrogeochemical concentration for groundwater exploration using electromagnetic method of terrain conductivity variation and analytical technique in Papalanto, South-West Nigeria. Naturalis Scientias, 2 (2): 623-661. DOI: https://doi.org/10.62252/NSS.2025.1036. www.naturalisscientias.com.