Heavy Metals (Pb, Zn, Cd) and Metalloids (Sb, As) in Carbonated Soils Contaminated by Mine Tailings (North Tunisia)
Résumé
Mining and smelting of metal ores activities have increased the dispersion of potential toxic elements (PTE) such as As, Cd, Pb, Sb, Zn and Pb, metal(loid)s in agricultural soils. These elements can be absorbed into the food chain, causing severe threats to human health. This study explores the mobility of these contaminants in agricultural soils developed on carbonated source rocks in the vicinity of two farmer mining sites in North Tunisia (Jebel Hallouf-Sidi Bouaouane and Jebel Ressas). Besides, it aims to assess the potential hazards of these contaminants on soil eco-dynamics and human health. Calcite and quartz are the abundant mineralogical fraction of these soils. Minor amounts of carbonates (cerussite), sulphates (Gypsum), silicates (hemimorphite), sulphides (sphalerite: (ZnS), pyrite: (FeS2)), as well as clay minerals, are also present in these soils. Pb, concentrations can reach 22,925 mg/kg; 17,350 mg/kg; 10,321 mg/kg in the soils of Jebel Ressas (JR), Sidi Bouaouane (B) and Jebel Hallouf (JH), respectively. Zn contents reached 69,567 mg/kg; 8,620 mg/kg; 7,951 mg/kg in these soils, respectively. Cd concentrations were much lower than Pb and Zn and did not exceed 20 mg/kg in Jebel Ressas soils and 64 mg/kg in the area of Sidi Bouaouane. The highest concentrations of metalloids are recorded for Sidi Bouaouane samples, approaching 669 mg/kg for As and 145 mg/kg for Sb.