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<p>Former mining activities in the Bétaré-Oya region of eastern Cameroon have generated long-lasting environmental impacts due to the accumulation of unrehabilitated mine residues. This study provides an integrated assessment of the mineralogical, geochemical, spectroscopic, and microtextural characteristics of mine tailings, contaminated soils, and downstream sediments to evaluate their contamination potential. X-ray Diffraction (XRD) analyses show that tailings are dominated by quartz (up to 55%), kaolinite, muscovite, and metallic sulfides including chalcopyrite, arsenopyrite, and galena, while soils and sediments exhibit more heterogeneous silicate–clay assemblages. Fourier-Transform Infrared Spectroscopy (FTIR) identifies strong absorption bands associated with carbonates (1430–875&#xa0;cm<sup>−1</sup>), sulfates (1120–980&#xa0;cm<sup>−1</sup>), and clay-related hydroxyl groups. Geochemically, total carbon (C) ranges from 1.0 to 6.9% in tailings and 1.2–6.4% in soils, whereas sulfur (S) reaches up to 6.5% in some tailings and sediments. Calcium carbonate (CaCO<sub>3</sub>) is highly variable, with maximum values of 16% in tailings, reflecting processing residues. Major oxides indicate strong iron enrichment in tailings (Fe<sub>2</sub>O<sub>3</sub> up to 13.4&#xa0;wt%), coupled with elevated Al<sub>2</sub>O<sub>3</sub> (up to 35.2&#xa0;wt%) and SiO<sub>2</sub> variability (25–60&#xa0;wt%). Silver (Ag) displays anomalous enrichment, reaching up to 8&#xa0;g/t in tailings, 5&#xa0;g/t in soils, and 11&#xa0;g/t in sediments, exceeding typical natural background levels (&lt; 0.1&#xa0;g/t). Scanning Electron Microscopy with Energy-Dispersive X-ray Spectroscopy (SEM–EDX) reveals porous and fractured microtextures, dissolution fronts, and micron-scale hotspots of Pb, Zn, Ag, and As within altered sulfides and secondary Fe-oxides. Collectively, these mineralogical and geochemical signatures indicate a high potential for contaminant release and downstream transfer, particularly during intense tropical weathering and seasonal flooding. The findings underscore the urgent need for site rehabilitation, improved tailings management, and sustained environmental monitoring to mitigate long-term risks to local ecosystems and agricultural zones.</p>

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Integrative mineralogical, geochemical, and spectroscopic assessment of mining-impacted environments in a post-extractive area of East Cameroon (SW-Africa) in a humid tropical climate

  • 期刊论文

  • 发表日期：

    2026年2月1日

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  • Armel Zacharie Ekoa Bessa,
  • Elvine Paternie Edjengté Doumo . ,
  • Nadia Rhoujjati

摘要

Former mining activities in the Bétaré-Oya region of eastern Cameroon have generated long-lasting environmental impacts due to the accumulation of unrehabilitated mine residues. This study provides an integrated assessment of the mineralogical, geochemical, spectroscopic, and microtextural characteristics of mine tailings, contaminated soils, and downstream sediments to evaluate their contamination potential. X-ray Diffraction (XRD) analyses show that tailings are dominated by quartz (up to 55%), kaolinite, muscovite, and metallic sulfides including chalcopyrite, arsenopyrite, and galena, while soils and sediments exhibit more heterogeneous silicate–clay assemblages. Fourier-Transform Infrared Spectroscopy (FTIR) identifies strong absorption bands associated with carbonates (1430–875 cm−1), sulfates (1120–980 cm−1), and clay-related hydroxyl groups. Geochemically, total carbon (C) ranges from 1.0 to 6.9% in tailings and 1.2–6.4% in soils, whereas sulfur (S) reaches up to 6.5% in some tailings and sediments. Calcium carbonate (CaCO3) is highly variable, with maximum values of 16% in tailings, reflecting processing residues. Major oxides indicate strong iron enrichment in tailings (Fe2O3 up to 13.4 wt%), coupled with elevated Al2O3 (up to 35.2 wt%) and SiO2 variability (25–60 wt%). Silver (Ag) displays anomalous enrichment, reaching up to 8 g/t in tailings, 5 g/t in soils, and 11 g/t in sediments, exceeding typical natural background levels (< 0.1 g/t). Scanning Electron Microscopy with Energy-Dispersive X-ray Spectroscopy (SEM–EDX) reveals porous and fractured microtextures, dissolution fronts, and micron-scale hotspots of Pb, Zn, Ag, and As within altered sulfides and secondary Fe-oxides. Collectively, these mineralogical and geochemical signatures indicate a high potential for contaminant release and downstream transfer, particularly during intense tropical weathering and seasonal flooding. The findings underscore the urgent need for site rehabilitation, improved tailings management, and sustained environmental monitoring to mitigate long-term risks to local ecosystems and agricultural zones.