Chemical and mineralogical analyses of contaminated soils at the Anaconda Smelter Site, Montana



Journal Title

Journal ISSN

Volume Title



The Anaconda Copper Smelter site in Montana, USA was deemed a superfund site by the U.S. Environment Protect Agency (USEPA) in 1983. Disposal of large quantities of tailing material caused toxic heavy metal contamination of the surrounding environments. Toxic metals included As, Cd, Cu, Pb, and Zn. In this study, samples from a tailing impoundment, "opportunity pond", and surrounding physically undisturbed soils were analyzed. Geochemical analysis following the Tessier Sequential extraction procedure (Tessier et al., 1979) and EPA digestion method 3050B (USEPA, 1996) were performed. Select samples were examined further by optical microscope and scanning electron microscopy. Results indicate that sampled weathered tailing material contain lower concentration of metals than the surrounding contaminated soils. Results also show that metal content in the samples varied as function of depth. For contaminated soils, the maximum metal concentrations occur in samples from 15 – 30 cm depth. Results from optical and electron microscope observation indicate that there is a positive correlation between metal content and the presence of opaque mineral phases. Most opaque mineral phases are secondary phases. The secondary mineral phases were predominantly iron oxides (goethite and hematite) and copper oxides. Geochemical process controls the formation of secondary minerals, and the migration of toxic heavy metals. Hydrological processes such as infiltration and evaporation of surface precipitation facilitates the migration of metals.



Heavy metal, Contamination, Soil, mine tailings, Anaconda, Chemical extraction, Mineralogy, Scanning electron microscopy (SEM)