Ono F B, Tappero R, Sparks D, Guilherme L R G
Department of Soil Science, Federal University of Lavras, CP 3037, Campus UFLA, 37200-000, Lavras, MG, Brazil.
Photon Sciences, Beamline X27A, National Synchrotron Light Source, Brookhaven National Laboratory, Upton, NY, 11973, USA.
Environ Sci Pollut Res Int. 2016 Jan;23(1):638-47. doi: 10.1007/s11356-015-5304-y. Epub 2015 Sep 2.
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.
研究表明，巴西一个金矿区的尾矿中存在高含量的砷（高达2666毫克砷/千克）。这是一个重要的关注点，引发了对人类健康影响的担忧。然而，最近的一项研究表明，同一地区的砷生物可利用性非常低（<4.4%）。因此，需要确定矿山尾矿和风沙扬尘中砷的直接固相形态，以解释这种低生物可利用性。从四个分区采集了矿山样品，从八个地点采集了风沙扬尘。应用基于同步加速器的体相X射线吸收近边结构（体相-XANES）光谱、微区X射线吸收近边结构（μ-XANES）和微区X射线荧光（μ-SXRF）光谱来确定砷的形态。体相-XANES光谱表明，砷以五价砷（As(V)）氧化态存在。微区-XANES和μ-SXRF分析表明，砷还以毒砂（FeAsS）及其风化产物的形式存在，但主要是呈 poorly crystalline ferric arsenate的五价砷。这支持了低生物可利用性砷的研究结果，并突出了铁氧化物在陆地环境中固定砷的重要性。所有空气颗粒物样品都显示出富含砷的颗粒（高达313毫克砷/千克）。空气颗粒物中固相砷的形态与矿山样品中发现的非常相似，这表明风沙扬尘中的砷不易被利用。 （注：“poorly crystalline ferric arsenate”可能是专业术语，这里保留英文未准确翻译，可根据具体专业知识进一步准确表述）
