Trace metal contamination status in soils of the abandoned gold mining district of Bindiba (East Cameroon): Pollution indices assessment, multivariate analysis and; geostatistical approach

In this study, contamination by trace metals (TMs) such as Cr, Ni, Cu, As, Pb and Sb in the soils of the Bindiba mining district was assessed. This study aims to reveal the current status of the soil quality of the abandoned gold mining district of Bindiba and provide a scientific basis for its future remediation and overall management. 89 soil samples were systematically collected and characterized in order to determine the concentration of TMs (Cr, Ni, Cu, As, Pb and Sb). To assess the degree of metallic contamination, pollution indices were employed. Both multivariate statistical analysis (MSA) and geostatistical modelling (GM) were used to identify the potential sources of TMs elements and to determine the values of the modified contamination degree (mCd), the Nemerow Pollution Index (NPI) and the potential ecological risk index (RI) at un-sampled points. The results of trace metals (TMEs) characterization showed that the concentration of Cr, Ni, Cu, As, Pb and Sb ranged from 22.15-442.44 mg/kg, 9.25-360.37 mg/kg, 1.28-320.86 mg/kg, 0-46.58 mg/kg, 0-53.27 mg/kg and 0-6.33 mg/kg, respectively. The mean concentration of Cr, Cu and Ni exceeds the continental geochemical background values. The Enrichment Factor (EF) assessment indicates two categories of enrichment: moderately to extremely enrichment for Cr, Ni, and Cu and deficiency to minimal enrichment of Pb, As and Sb. Multivariate statistical analysis shows weak linear correlations between the studied heavy metals and suggests that these metals could not come from the same origins. The geostatistical modelling based on the values of mCd, NI and RI suggests a potential high pollution risk existed in the study area. The mCd, NPI and RI interpolation maps showed that the Northern part of the gold mining district was characterized by a high degree of contamination, heavy pollution, and considerable ecological risk. The dispersion of TMs in soils could mainly be attributed to anthropogenic activities and natural phenomena (chemical weathering or erosion). Appropriate measures should be taken to manage and remediate the TMs pollution in this abandoned gold mining district in order to reduce its negative effects on the environment and health of the local population.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40201-023-00849-y.

Impact of gold mining on the water quality of the lom river, Gankombol, Cameroon

The aim of this paper is to assess the impact of gold mining on the water quality of the Lom River at Gankombol (Adamawa Cameroon). Forty-eight (48) water samples are systematically collected during the dry and the rainy season. These water samples are characterized to determine the physico-chemical parameters, major ions and metals. A local geological study is conducted to determine the relationship between the geological units encountered and water contamination. Hydrochemical assessment, multivariate statistical analysis (MSA) and geostatistical modeling (GM) are used to assess contamination. The results indicate that the waters of the Lom River draining the gold mining site are acidic to neutral (5.3-6.9), very turbid (117-510 NTU) with high concentrations of suspended solids (22.89-471 mg/L). The mean concentrations of Fe, Pb, and As exceed the limits set by the World Health Organization (WHO) standards. Pb, As, Cd and Hg concentrations decrease in the rainy season mainly due to dilution by rainwater. The predominant water type is Ca-Mg-HCO₃. This surface water is unsuitable for drinking purpose (997.5, Water Quality Index >300) with high level of metal pollution. MSA reveal strong linear correlations between EC-TDS, EC-Na⁺, TDS-Na⁺, Pb-As, Cl^- -SO₄ ^2- and TSS-Cd suggesting that the correlated parameters can have common origin. Finally, GM reveal that the lowest values of metals and pollution indices are found upstream of the gold mining site. The weathering of geological units encountered, mining activities and seasons have a major influence on the water quality. Therefore, it appears that decision-makers must take immediate action to decrease pollution and adopt suitable and sustainable remedial solutions.