Characterization of iron speciation in urban and rural single particles using XANES spectroscopy and micro X-ray fluorescence measurements: investigating the relationship between speciation and fractional iron solubility
Characterization of iron speciation in urban and rural single particles using XANES spectroscopy and micro X-ray fluorescence measurements: investigating the relationship between speciation and fractional iron solubility
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DOI：
10.5194/acp-12-745-2012
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发表时间：
2012-01-01
影响因子：
6.3
通讯作者：
Ingall, E. D.
中科院分区：
文献类型：
--
作者：
Oakes, M.;Weber, R. J.;Ingall, E. D.
大气细颗粒物中的可溶性铁通过参与产生活性氧（ROS）的反应而被确定为公共健康问题。铁的矿物学和氧化态（形态）已被证明会影响部分铁溶解度（可溶性铁/总铁）。在这项研究中，铁形态确定在城市和农村网站在美国格鲁吉亚使用同步加速器为基础的技术，如X射线吸收近边结构（XANES）光谱和显微镜X射线荧光测量的单颗粒。分别使用分光光度法和基于同步加速器的技术测量这些样品的可溶性铁和总铁含量（可溶性+不溶性铁）。这些散装测量相结合的同步加速器为基础的测量，研究铁形态和分数铁溶解度在环境气溶胶之间的关系。XANES测量表明，单个颗粒中的铁作为Fe（II）和Fe（III）的混合物存在，其中Fe（II）含量通常在5%和35%之间（平均值：类似于25%）。XANES和元素分析（e. G.基于显微X射线荧光测量的单个颗粒的元素摩尔比）表明，大多数（74%）含铁颗粒最好表征为Al取代的Fe氧化物，Fe/Al摩尔比为4.9。下一个最丰富的颗粒组（12%）是Fe-铝硅酸盐，Si/Al摩尔比为1.4。分数铁溶解度（可溶性铁/总铁）和铝取代的铁氧化物和铁铝硅酸盐的丰度之间没有相关性，在不同的季节，在任何网站的单一颗粒存在，这表明溶解度在很大程度上取决于其他因素的差异，在主要的铁相。
Soluble iron in fine atmospheric particles has been identified as a public health concern by participating in reactions that generate reactive oxygen species (ROS). The mineralogy and oxidation state (speciation) of iron have been shown to influence fractional iron solubility (soluble iron/total iron). In this study, iron speciation was determined in single particles at urban and rural sites in Georgia USA using synchrotron-based techniques, such as X-ray Absorption Near-Edge Structure (XANES) spectroscopy and microscopic X-ray fluorescence measurements. Soluble and total iron content (soluble + insoluble iron) of these samples was measured using spectrophotometry and synchrotron-based techniques, respectively. These bulk measurements were combined with synchrotron-based measurements to investigate the relationship between iron speciation and fractional iron solubility in ambient aerosols. XANES measurements indicate that iron in the single particles was present as a mixture of Fe(II) and Fe(III), with Fe(II) content generally between 5 and 35% (mean: similar to 25 %). XANES and elemental analyses (e. g. elemental molar ratios of single particles based on microscopic X-ray fluorescence measurements) indicate that a majority (74 %) of iron-containing particles are best characterized as Al-substituted Fe-oxides, with a Fe/Al molar ratio of 4.9. The next most abundant group of particles (12 %) was Fe-aluminosilicates, with Si/Al molar ratio of 1.4. No correlation was found between fractional iron solubility (soluble iron/total iron) and the abundance of Al-substituted Fe-oxides and Fe-aluminosilicates present in single particles at any of the sites during different seasons, suggesting solubility largely depended on factors other than differences in major iron phases.