Assessment of groundwater contamination by trace metals in the Chami gold area (Mauritania)

Abstract

Artisanal gold mining in Chami is an important lever in the country economy, owing to the benefits it brings, but it is also likely to have a negative impact on various environmental compartments. Contamination of surface and ground water by trace metals elements (ETMs) was studied in the vicinity of the Chami gold processing center. The aim of the study was to assess the water contamination by trace metals (ETMs) in the town of Chami. Nine water samples (process and boreholes) were analyzed for (Co, Cr, Cu, Ni, Pb, Zn and Hg). The analysis was carried out by the DMA 80 technique for Hg at the ONISPA laboratory in Nouakchott and the other ETM at the Kenitra geosciences laboratory by the ICP-MS technique. The results of the analyses show that the ETM concentrations are high in process water samples and low in drilling water samples. Pollution indices and coefficients of variation indicate no contamination or anthropogenic traces in the borehole samples, but high levels of Hg and Ni in the process water. These results show the accumulation of metals in significant quantities in the process waters, especially Hg, proving that the waters of the mining waste basins at the Chami processing site are becoming sources of environmental pollution by mercury, which can be released into the environment by several pathways.