Influence of hydrology on heavy metal speciation and mobility in a Pb–Zn mine tailing

• Published in: Environmental pollution (1987) 2006-05, Vol.141 (2), p.310-320
• Main Authors: Kovács, Elza, Dubbin, William E., Tamás, János
• Format: Article
• Language: English
• Subjects: Applied sciences; bioavailability; Biological and physicochemical properties of pollutants. Interaction in the soil; Biological Availability; cadmium; Cadmium - analysis; Calcium Carbonate - analysis; chemical speciation; copper; Copper - analysis; Earth sciences; Earth, ocean, space; Electric Conductivity; electrical conductivity; Engineering and environment geology. Geothermics; Environmental Pollutants - analysis; Exact sciences and technology; Freshwater; Geologic Sediments - analysis; Heavy metal; heavy metals; Hydrogen-Ion Concentration; Hydrology; iron; Iron - analysis; Iron Compounds - analysis; lead; Lead - analysis; Metals, Heavy - analysis; Mine tailing; Minerals; Mining; Other industrial wastes. Sewage sludge; Oxidation; Oxidation-Reduction; Particle Size; Pollution; Pollution, environment geology; sediment contamination; Soil and sediments pollution; Solubility; Speciation; Sulfides; Wastes; Water - chemistry; water pollution; zinc; Zinc - analysis
• ISSN: 0269-7491; 1873-6424
• DOI: 10.1016/j.envpol.2005.08.043

Among the inorganic toxicants of greatest concern in mine tailings, Pb, Zn, Cu, Cd and As figure prominently due to their abundance and potential toxicity. Here we report on their biolability and solid-phase speciation in two sediment cores subject to variable hydrological regimes at an abandoned pyritic mine tailing. The oxic conditions of well-drained sediments induced pyrite oxidation and the subsequent liberation of H +, SO 4 2− and considerable quantities of Fe(III), which precipitated as goethite. Solubility of Pb, Zn, Cu and Cd was closely coupled to pH and goethite presence. Metal lability was particularly low in zones of neutralization, formed by the accumulation of calcite, first carried then deposited by percolating waters in both saturated and unsaturated cores. We conclude that differential hydrology induces variable heavy metal speciation and biolability in Pb–Zn mine tailings, and suggest that site-specific risk assessments must account for past and present hydrological regimes. Variable hydrology influences heavy metal speciation and mobility, and the formation of neutralization zones, in a Pb–Zn mine tailing.