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dc.contributor.authorRoot, Robert A
dc.contributor.authorHayes, Sarah M
dc.contributor.authorHammond, Corin M
dc.contributor.authorMaier, Raina M
dc.contributor.authorChorover, Jon
dc.date.accessioned2019-07-03T21:38:22Z
dc.date.available2019-07-03T21:38:22Z
dc.date.issued2015-11-01
dc.identifier.citationRoot, R. A., Hayes, S. M., Hammond, C. M., Maier, R. M., & Chorover, J. (2015). Toxic metal (loid) speciation during weathering of iron sulfide mine tailings under semi-arid climate. Applied Geochemistry, 62, 131-149.en_US
dc.identifier.issn0883-2927
dc.identifier.pmid26549929
dc.identifier.urihttp://hdl.handle.net/10150/633292
dc.description.abstractToxic metalliferous mine-tailings pose a significant health risk to ecosystems and neighboring communities from wind and water dispersion of particulates containing high concentrations of toxic metal(loid)s (e.g., Pb, As, Zn). Tailings are particularly vulnerable to erosion before vegetative cover can be reestablished, i.e., decades or longer in semi-arid environments without intervention. Metal(loid) speciation, linked directly to bioaccessibility and lability, is controlled by mineral weathering and is a key consideration when assessing human and environmental health risks associated with mine sites. At the semi-arid Iron King Mine and Humboldt Smelter Superfund site in central Arizona, the mineral assemblage of the top 2 m of tailings has been previously characterized. A distinct redox gradient was observed in the top 0.5 m of the tailings and the mineral assemblage indicates progressive transformation of ferrous iron sulfides to ferrihydrite and gypsum, which, in turn weather to form schwertmannite and then jarosite accompanied by a progressive decrease in pH (7.3 to 2.3). Within the geochemical context of this reaction front, we examined enriched toxic metal(loid)s As, Pb, and Zn with surficial concentrations 41.1, 10.7, 39.3 mM kg-1 (3080, 2200, and 2570 mg kg-1), respectively. The highest bulk concentrations of As and Zn occur at the redox boundary representing a 1.7 and 4.2 fold enrichment relative to surficial concentrations, respectively, indicating the translocation of toxic elements from the gossan zone to either the underlying redox boundary or the surface crust. Metal speciation was also examined as a function of depth using X-ray absorption spectroscopy (XAS). The deepest sample (180 cm) contains sulfides (e.g., pyrite, arsenopyrite, galena, and sphalerite). Samples from the redox transition zone (25-54 cm) contain a mixture of sulfides, carbonates (siderite, ankerite, cerrusite, and smithsonite) and metal(loid)s sorbed to neoformed secondary Fe phases, principally ferrihydrite. In surface samples (0-35 cm), metal(loid)s are found as sorbed species or incorporated into secondary Fe hydroxysulfate phases, such as schwertmannite and jarosites. Metal-bearing efflorescent salts (e.g., ZnSO4·nH2O) were detected in the surficial sample. Taken together, these data suggest the bioaccessibility and lability of metal(loid)s are altered by mineral weathering, which results in both the downward migration of metal(loid)s to the redox boundary, as well as the precipitation of metal salts at the surface.en_US
dc.language.isoenen_US
dc.publisherPERGAMON-ELSEVIER SCIENCE LTDen_US
dc.relation.urlhttps://www.sciencedirect.com/science/article/pii/S0883292715000128en_US
dc.rightsPublished by Elsevier Ltd.en_US
dc.subjectXASen_US
dc.subjectarsenicen_US
dc.subjectleaden_US
dc.subjectmine tailingen_US
dc.subjectsemi-ariden_US
dc.subjectzincen_US
dc.titleToxic metal(loid) speciation during weathering of iron sulfide mine tailings under semi-arid climateen_US
dc.typeArticleen_US
dc.contributor.departmentUniv Arizona, Dept Soil Water & Environm Scien_US
dc.identifier.journalAPPLIED GEOCHEMISTRYen_US
dc.description.note24 month embargo; published online: 7 February 2015en_US
dc.description.collectioninformationThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at repository@u.library.arizona.edu.en_US
dc.eprint.versionFinal published versionen_US
dc.source.journaltitleApplied geochemistry : journal of the International Association of Geochemistry and Cosmochemistry
refterms.dateFOA2017-02-07T00:00:00Z


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