Microbiological and Physicochemical Quality Assessment of Groundwater in Mining Locations in Ikwo, Ebonyi State, South East Nigeria

Objective: This study assessed the microbiological and physicochemical quality of groundwater surrounding mining sites in Ikwo, Nigeria.Materials and Methods: Eight groundwater samples (boreholes and wells) were collected from mining sites in the Enyigba and Agalegu communities of Ikwo, while two samples from Abakaliki metropolis served as controls. Standard microbiological methods were used to determine total heterotrophic bacteria, fungi, and hydrocarbon-utilising bacteria. Bacterial isolates were identified using the computerized Enterotube system, while sulphate-reducing and acid-producing bacteria were detected using API RP 38 broth and ZPRA-5 media, respectively. Fungal isolates were identified by morphological and microscopic examination. Physicochemical parameters, macro- and micro-elements, and inorganic compounds were analysed using standard methods.Results: Total heterotrophic bacterial counts ranged from 1.5×10³ to 21.6×10³ CFU/mL, hydrocarbon-utilising bacteria from 0.1×10³ to 0.7×10³ CFU/mL, and fungal counts from 0.2×10³ to 2.4×10³ CFU/mL. Microbial diversity included Candida spp., filamentous fungi, yeast-like organisms, and bacterial genera such as Enterobacter, Klebsiella, Escherichia, Salmonella, and Serratia. Acid-producing bacteria were more prevalent than sulphate-reducing bacteria. Physicochemical analyses showed significant differences between mining and control sites (p<0.05). Elevated concentrations of nutrients, ions, and trace metals, including Zn, Pb, Cr, and Cd, were detected, particularly in the Alibaruhu Agalegu borehole.Conclusion: Mining activities significantly influenced groundwater quality. Although contaminant levels were generally moderate, the elevated mineral content and diverse microbial communities indicate that local geochemical conditions support microbial growth and affect water quality.