Investigation of arsenic species in tailings and windblown dust from a gold mining area.
Research has shown the presence of high levels of arsenic (up to 2666 mg As kg(-1)) in tailings from a gold mining area of Brazil. This is an important point of attention, generating concerns about impacts on human health. Yet, a recent study showed that As bioaccessibility in the same area was very low (<4.4%). Thus, determination of the direct solid-phase speciation of As in the mine tailings and windblown dust is needed to explain this low bioaccessibility. Mine samples were collected from four subareas and windblown dust from eight sites. Synchrotron-based bulk-X-ray absorption near-edge structure (bulk-XANES) spectroscopy, micro-X-ray absorption near-edge structure (μ-XANES), and μ-X-ray fluorescence (μ-SXRF) spectroscopy were applied to determine As speciation. Bulk-XANES spectra indicated that As occurs as the As(V) oxidation state. Micro-XANES and μ-SXRF analyses revealed that As was also present as arsenopyrite (FeAsS) and its weathering products, but mostly it was As(V) as poorly crystalline ferric arsenate. This supports the findings of low bioaccessible As and highlights the importance of Fe oxides in immobilizing As in the terrestrial environment. All air particulate samples exhibited As-rich particles (up to 313 mg As kg(-1)). The air particulates exhibited solid-phase As species very similar to those found in the mine samples, which indicates that As in the windblown dust is not easily available.
Department of Soil Science, Federal University of Lavras, CP 3037, Campus UFLA, 37200-000, Lavras, MG, Brazil.
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Photon Sciences, Beamline X27A, National Synchrotron Light Source, Brookhaven National Laboratory, Upton, NY, 11973, USA.
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Tappero
University of Delaware, Delaware Environmental Institute, Interdisciplinary Science and Engineering Lab, Suite 250a, Newark, DE, 19716, USA.
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Sparks
Department of Soil Science, Federal University of Lavras, CP 3037, Campus UFLA, 37200-000, Lavras, MG, Brazil. guilherm@dcs.ufla.br.
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Guilherme
D000393:Air Pollutants / Q000737:chemistry*; D001152:Arsenicals / Q000737:chemistry*; D001938:Brazil; D004391:Dust / Q000032:analysis; D006046:Gold / Q000032:analysis; D006801:Humans; D008906:Mining; D013052:Spectrometry, X-Ray Emission; D056928:X-Ray Absorption Spectroscopy
D000393:Air Pollutants; D001152:Arsenicals; D004391:Dust; D006046:Gold
Air particulates; Arsenic speciation; Bioaccessibility; Environmental pollution; Micro-XANES; Trace elements