Application of Geophysical and Geochemical Approach to Environmental Impact Assessment around Cassava Mills in Western Niger Delta, Nigeria

Abstract

Cassava mill effluent (CME) contains a significant concentration of different hazardous inorganic components, especially cyanide (CN), which can result in environmental problems. This study seeks to evaluate the impacts of CME on groundwater around Eku. A 2D electrical resistivity survey, geochemical analysis and groundwater modelling were adopted for this study. The Zones impacted by CME imaged by the inverted resistivity structure were distinguished by low resistivity ranging between 0.46 – 21.05 Ωm. Geochemical analysis of CME indicated high concentrations of Total Dissolved Solids (TDS), Electrical Conductivity (EC), CN, and heavy metal components and have the capability to contaminate surrounding groundwater. The groundwater model showed flow in the Southeast – Northwest (SE – NW) direction with a velocity of 54.24 m/year. The pH value, the concentration of CN, TDS, EC, and heavy metals in groundwater samples, when compared with the WHO drinking standard, revealed that groundwater in only one hand dug well about 20 m away from a cassava mill indicated a significant degree of contamination. A pattern of decreasing CN concentration with distance from the mill was observed in groundwater; areas with CN concentration greater than 0.2 mg/l after 1 year was 30 m away from the cassava mill but extended to about 75 m after 5 years.