Mapping of Soil Contamination Extent Around a Textile Effluent Discharge Zone in Abakaliki Using Geophysical Techniques

Industrial effluent discharge from textile facilities in peri-urban Abakaliki has created significant soil contamination concerns that remain inadequately quantified using geophysical approaches. This study applies electrical resistivity tomography and electromagnetic profiling to map the extent of soil contamination around a primary textile effluent discharge zone in Abakaliki. Fifteen ERT traverses were acquired using Syscal Pro equipment with a 72-electrode Wenner-Schlumberger configuration, providing depth penetration to approximately 30 m. Electromagnetic EM31 profiling was additionally conducted along parallel grids to provide rapid lateral coverage of the contaminated terrain. ERT data were processed using RES2DINV, and joint interpretation with EM31 apparent conductivity maps provided a comprehensive picture of contaminant distribution. Anomalously low resistivity zones (less than 5 ohm-m) within the shallow 0 to 5 m horizon are interpreted as zones of dissolved dye and chemical infiltration from surface effluent ponding. The contamination plume extends to an estimated 250 m in the direction of groundwater flow and is confined to depths shallower than 18 m by a clay aquitard. Electromagnetic conductivity highs spatially coincide with reported vegetation stress zones, confirming the phytotoxic extent of the contamination. The study delineates priority remediation zones and provides a baseline dataset for ongoing environmental monitoring. These results highlight the practical value of integrating resistivity and electromagnetic methods for environmental geophysical assessments in industrial zones of developing cities.

Keywords: electrical resistivity tomography, EM profiling, soil contamination, textile effluent, Abakaliki