Selenium speciation in framboidal and euhedral pyrites in shales.
Selenium speciation in framboidal and euhedral pyrites in shales.
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DOI：
10.1021/es405686q
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发表时间：
2014-07
影响因子：
11.4
通讯作者：
Adriana Matamoros-Veloza;C. Peacock;L. Benning
中科院分区：
文献类型：
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作者：
Adriana Matamoros-Veloza;C. Peacock;L. Benning
硒从页岩中的释放是知之甚少，因为它的发生，分布和形态的页岩的各种成分是未知的。为了解决这一差距，我们结合体表征，连续提取，和空间分辨μ焦点光谱分析，并研究了Se和其他伴生元素（Fe，As，Cr，Ni和Zn）的存在和分布，并确定了典型的低体积含Se页岩中μ尺度的Se形态。我们的研究结果表明，硒主要与黄铁矿级与确切的硒形态高度依赖于黄铁矿形态。在自形黄铁矿中，我们发现Se（-II）的矿物结构中的S的替代品。然而，我们也表明，硒与framboidal黄铁矿颗粒作为一个离散的，独立的FeSex相。这种FeSex物种的存在有重大影响硒的释放，因为FeSex物种氧化快得多的自形黄铁矿晶格中取代硒。因此，这种FeSex物种将增强和控制Se风化和释放到水环境中的动态。
The release of Se from shales is poorly understood because its occurrence, distribution, and speciation in the various components of shale are unknown. To address this gap we combined bulk characterization, sequential extractions, and spatially resolved μ-focus spectroscopic analyses and investigated the occurrence and distribution of Se and other associated elements (Fe, As, Cr, Ni, and Zn) and determined the Se speciation at the μ-scale in typical, low bulk Se containing shales. Our results revealed Se primarily correlated with the pyrite fraction with exact Se speciation highly dependent on pyrite morphology. In euhedral pyrites, we found Se(-II) substitutes for S in the mineral structure. However, we also demonstrate that Se is associated with framboidal pyrite grains as a discrete, independent FeSex phase. The presence of this FeSex species has major implications for Se release, because FeSex species oxidize much faster than Se substituted in the euhedral pyrite lattice. Thus, such an FeSex species will enhance and control the dynamics of Se weathering and release into the aqueous environment.