Use of micro-XANES to speciate chromium in airborne fine particles in the Sacramento Valley

Journal Article · Sun Jul 15 00:00:00 EDT 2007 · Environmental Science and Technology

DOI:https://doi.org/10.1021/es070430q· OSTI ID:20939474

Werner, Michelle L; Nico, Peter S; Marcus, Matthew A; Anastasio, Cort ^[1]

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1. University of California, Davis, CA (United States). Department of Land, Air, and Water Resources

While particulate matter (PM) in the atmosphere can lead to a wide array of negative health effects, the cause of toxicity is largely unknown. One aspect of PM that likely affects health is the chemical composition, in particular the transition metals within the particles. Chromium is one transition metal of interest due to its two major oxidation states, with Cr(III) being much less toxic compared to Cr(VI). Using microfocused X-ray absorption near edge structure (micro-XANES), we analyzed the Cr speciation in fine particles (diameters {le} 2.5 {mu}m) collected at three sites in the Sacramento Valley of northern California: Sacramento, a large urban area, Davis, a small city, and Placerville, a rural area. These are several major stationary sources of Cr within 24 km of the site including chrome-plating plants, power plants and incinerators. The microfocused X-ray beam enables us to look at very small areas on the filter with a resolution of typically 5-7 micrometers. With XANES we are able to not only distinguish between Cr(VI) and Cr(III), but also to identify different types of Cr(III) and more reduced Cr species. At all of our sampling sites the main Cr species were Cr(III), with Cr(OH){sub 3} or a Cr-Fe, chromite-like, phase being the dominant species. Cr(VI)-containing particles were found only in the most urban site. All three sites contained some reduced Cr species, either Cr(0) or Cr{sub 3}C{sub 2}, although these were minor components. This work demonstrates that micro-XANES can be used as a minimally invasive analytical tool to investigate the composition of ambient PM. 32 refs., 6 figs.

• OSTI ID: 20939474
• Journal Information: Environmental Science and Technology, Vol. 41, Issue 140; Other Information: [e-mail]; ISSN 0013-936X
• Country of Publication: United States
• Language: English

Related Subjects

01 COAL, LIGNITE, AND PEAT
54 ENVIRONMENTAL SCIENCES
20 FOSSIL-FUELED POWER PLANTS
CHROMIUM
USA
CALIFORNIA
PARTICULATES
URBAN AREAS
X-RAY SPECTROSCOPY
RURAL AREAS
VALLEYS
ABSORPTION SPECTRA
CHEMICAL STATE
QUANTITATIVE CHEMICAL ANALYSIS
ELEMENT ABUNDANCE
SULFUR
CHEMICAL COMPOSITION
TOXICITY
ABSORPTION SPECTROSCOPY
TRANSITION ELEMENTS
SAMPLING
FLUORESCENCE
STATIONARY POLLUTANT SOURCES