Hydrochemical Characteristics of Groundwater in the Mutoshi Deposit Environment, Kolwezi (Lualaba, DR Congo)

Abstract

This study examines the hydrochemical characteristics of groundwater in the Mutoshi mining environment in Kolwezi, Democratic Republic of Congo, addressing gaps in understanding the impact of mining on water quality. Despite the DRC's vast water resources, only 26% of the urban population has access to safe drinking water, with the Mutoshi aquifer, providing over a quarter of Kolwezi's drinking water, facing deterioration due to underlying copper and cobalt-rich geological formations. Groundwater and geological samples were analyzed for major and trace elements using X-ray fluorescence and inductively coupled plasma mass spectrometry (ICP-MS). Results showed high concentrations of copper (Cu) at 9.930 ppm, cobalt (Co) at 3.560 ppm, manganese (Mn) at 2.182 ppm, and iron (Fe) at 41.500 ppm, significantly exceeding reference values. Groundwater samples revealed Cu levels up to 32 mg/L and Mn at 9.5 mg/L, surpassing WHO standards. Hydrochemical classification of the waters, performed using the Piper diagram, revealed two distinct hydrofacies. Calciummagnesium bicarbonate waters dominate most samples, while sodium-potassium bicarbonate waters are also present. Processes influencing groundwater mineralization include the dissolution of carbonate, clay, and evaporite minerals. These findings underscore the importance of effective mining waste management and ongoing groundwater quality monitoring to safeguard public health.