Assessment of Metallic Contamination in Soils and Sediments in the Bétaré-Oya Gold Artisanal Mine District, East-Cameroon

Abstract

Mining is an activity that involves the use of chemicals and results in unsustainable and dangerous conditions for the miners, their families, the community and the surrounding ecosystem. This study was done to assess metallic contamination of soils and sediments in the Bétaré-Oya gold artisanal mine district, East-Cameroon. A total of thirty (30) samples of exploited soils, control soils and sediments were taken from the mining sites of Lom, Mbal and Mali. The concentrations of heavy metals and metalloids (Fe, Sr, Cu, As, Pb and Zn) were determined by Inductive Plasma Ionisation Source Atomic Emission Spectrometry. The results show that in the sediments metals such as: As (1.82), Cu (24.22), Pb (18.04) and Zn (65.69) have average concentrations slightly higher than the UCC and Average Shale reference values. In the exploited soil As (1.93), Cu (16.86) and Zn (96.22) have average concentrations slightly higher than the UCC and Average Shale reference values.While in the cotrol soils only As (1.62) and Zn (59.72) shows an average concentration slightly above the UCC reference values. The average concentrations of the different heavy metals and metalloids were then used to calculate the intensity of contamination in soils and sediments.  The results of this calculation indicate that the Enrichment Factor (EF) of As, Sr, Zn and Pb indicate an extremely high enrichment in these elements. The geo-accumulation Index (Igeo) (22.85-25), the Contamination (CF) (1.47), the low values of the ecological risk indices suggest a low potential ecological risk and Pollution load index (PLI) (0.67) indicates extreme contamination with these elements in the soils and sediments. However, only As indicates a slight contamination (class 1) in soils and sediments. Gold panning activities and untreated mine tailings discharges would be considered as the main sources of sediment and soil pollution in Bétaré-Oya.