Microbial leaching of zinc concentrate in fresh#x2010;water microcosms: Comparison between aerobic and oxygen#x2010;limited conditions

摘要

Microbially mediated leaching and solubilization of zinc ore concentrate by native aquatic microbial communities incubated under aerobic and oxygen#x2010;limited conditions were examined in static microcosms consisting of stream sediment and water. Sterile controls provided information on abiotic sulfide oxidation and leaching of zinc, lead, cadmium, and copper. The flux of these heavy metals from the sediments to the water column was greatest under biotic oxygen#x2010;limited conditions. When calculated as the percentage of total metal available in zinc concentrate#x2010;amended microcosms, the order of metal solubilization under oxygen#x2010;limited conditions was lead, copper, zinc, and cadmium. Under biotic aerobic conditions, the order of solubilization was zinc, lead, cadmium, and copper. This study indicates that aquatic heterotrophs are capable of leaching and solubilizing metallic sulfides under conditions of neutral to slightly acidic pH and are effective in releasing heavy metals to the water column under oxygen#x2010;limited conditions.