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| Titel |
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 |
| VerfasserIn |
M. Oakes, R. J. Weber, B. Lai, A. Russell, E. D. Ingall |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 12, no. 2 ; Nr. 12, no. 2 (2012-01-16), S.745-756 |
| Datensatznummer |
250010527
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| Publikation (Nr.) |
 copernicus.org/acp-12-745-2012.pdf |
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| Zusammenfassung |
| 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: ~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. |
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