Mining Exploration and Exploitation Department, Escuela de Ingeniería de Minas, Energía Y Materiales, University of Oviedo, 13th Independencia St., 33004 Oviedo, Spain.
Int J Environ Res Public Health. 2022 Aug 4;19(15):9609. doi: 10.3390/ijerph19159609.
Sequential extraction procedures (SEPs) are widely used in environmental studies to infer the chemical and/or mineralogical forms of pollutants of concern in soils and sediments. Although there is no general agreement among the scientific community, these methods have shown some limitations, especially those with a lack of objectivity in their interpretation. In this work, a soil sampling campaign was carried out in an area affected by an abandoned Sb mine. Samples (0-15 cm) were carefully prepared and analyzed by an SEP. They were also studied by conventional mineralogical methods (optical and electronic microscopy, both scanning and transmission, with a coupled energy dispersive X-ray (EDX) spectrometer). When comparing the results obtained from both techniques, some discrepancies are highlighted, with As, Cu, Pb, Sb and Zn as elements of concern. For Sb, Cu, Pb and As the predominant fraction (excluding the residual one) is that associated with organic matter (from 8.54 for Sb to 18.90% for Cu). The fractions of pollutants linked to Fe and/or Mn oxides are quantitatively important for As, Pb and Zn (6.46%, 12.05% and 7.43%, respectively) and almost negligible for Cu and Sb. On the contrary, analyses carried out by EDX at a grain scale pointed out that no detectable quantities of the elements of concern were present on the surface of the organic particles. Sb and Pb were always detectable in Fe oxides (up to 1.84 and 5.76%, respectively). Regarding the role of the clayey fraction, the only disagreement between the employed SEP and the microanalysis is in relation to As. Arsenic bound to clay minerals was found to be an order of magnitude lower than As associated with Fe oxides (0.56% and 6.46%, respectively); in contrast, EDX microanalyses showed similar As contents in both groups. Given the objectiveness of EDX microanalysis, these differences should be considered inaccuracies in the interpretation of the sequential extraction results.
顺序提取程序（SEPs）广泛应用于环境研究中，以推断土壤和沉积物中关注污染物的化学和/或矿物形态。尽管科学界没有达成普遍共识，但这些方法存在一些局限性，特别是在解释方面缺乏客观性。在这项工作中，在一个受废弃 Sb 矿影响的地区进行了土壤采样活动。对样品（0-15cm）进行了仔细准备并通过 SEP 进行了分析。还使用常规矿物学方法（光学和电子显微镜，包括扫描和透射，以及耦合的能量色散 X 射线（EDX）光谱仪）对其进行了研究。当比较这两种技术的结果时，突出显示了一些差异，其中 As、Cu、Pb、Sb 和 Zn 是关注的元素。对于 Sb、Cu、Pb 和 As，主要的部分（不包括残余部分）是与有机物结合的部分（从 8.54%的 Sb 到 18.90%的 Cu）。与 Fe 和/或 Mn 氧化物结合的污染物部分对于 As、Pb 和 Zn 是定量重要的（分别为 6.46%、12.05%和 7.43%），而对于 Cu 和 Sb 则几乎可以忽略不计。相反，通过 EDX 在颗粒尺度上进行的分析表明，在有机物颗粒的表面不存在可检测数量的关注元素。Sb 和 Pb 总是可以在 Fe 氧化物中检测到（分别高达 1.84%和 5.76%）。关于粘土层的作用，所采用的 SEP 与微观分析之间唯一的分歧与 As 有关。发现与粘土矿物结合的砷比与 Fe 氧化物结合的砷低一个数量级（分别为 0.56%和 6.46%）；相比之下，EDX 微观分析显示这两组的 As 含量相似。鉴于 EDX 微观分析的客观性，这些差异应被视为顺序提取结果解释中的不准确之处。
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