title: Evaluation of metal partitioning and mobility in a sulfidic mine tailing pile under oxic and anoxic conditions.
abstract: Mining-influenced water emanating from mine tailings and potentially contaminating surface water and groundwater is one of the most important environmental issues linked to the mining industry. In this study, two subsets of Callahan Mine tailings (mainly comprised of silicates, sulfides, and carbonates) were collected using sealed containers, which allowed keeping the samples under anoxic conditions during transportation and storage. Among the potential contaminants, in spite of high concentrations of Cu, Mn, Pb, and Zn present in the solid mine tailings, only small amounts of Mn and Zn were found in the overlying pore water. The samples were subjected to leaching tests at different reduction-oxidation (redox) conditions to compare metal and S mobilization under oxic and anoxic conditions. It was observed that Cd, Cu, Mn, Pb, S, and Zn were mobilized at higher rates under oxic conditions, while Fe was mobilized at a higher rate under anoxic conditions in comparable constant pH experiments. These results suggest that metal mobilization is significantly impacted by redox conditions. When anoxic metal mobilization assessment is required, it is recommended to always maintain anoxic conditions because oxygen exposure may affect metal mobilization. A sequential extraction performed under oxic conditions revealed that most of the metals in the samples were associated with the sulfidic fraction and that the labile fraction was associated with Mn and moderate amounts of Pb and Zn.
authors.affiliation: Pegasus Technical Services, Inc., 46 E. Hollister St., Cincinnati, OH 45219, United States.
authors.forename: Patricio X
authors.initials: PX
authors.lastname: Pinto
authors.affiliation: National Risk Management Research Laboratory U.S. Environmental Protection Agency, 26 W. Martin Luther King Dr., Cincinnati, OH 45268, United States. Electronic address: al-abed.souhail@epa.gov.
authors.forename: Souhail R
authors.initials: SR
authors.lastname: Al-Abed
authors.affiliation: Pegasus Technical Services, Inc., 46 E. Hollister St., Cincinnati, OH 45219, United States.
authors.forename: Christopher
authors.initials: C
authors.lastname: Holder
authors.affiliation: CDM Smith, 8805 Governor's Hill Drive Suite 305, Cincinnati, OH 45249, United States.
authors.forename: David J
authors.initials: DJ
authors.lastname: Reisman
mesh_terms: D002254:Carbonates; D004784:Environmental Monitoring; D007220:Industrial Waste / Q000032:analysis*; D008281:Maine; D008670:Metals / Q000032:analysis*; D008906:Mining; D010100:Oxygen / Q000737:chemistry; D017640:Silicates; D013440:Sulfides; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D002254:Carbonates; D007220:Industrial Waste; D008670:Metals; D017640:Silicates; D013440:Sulfides; D014874:Water Pollutants, Chemical; D010100:Oxygen
keywords: Metal mobilization; Mine tailings leaching; Mine waste; Mn; Zn