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

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,more » 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.« less
Authors:
; ; ;  [1]
  1. University of California, Davis, CA (United States). Department of Land, Air, and Water Resources
Publication Date:
OSTI Identifier:
20939474
Resource Type:
Journal Article
Resource Relation:
Journal Name: Environmental Science and Technology; Journal Volume: 41; Journal Issue: 140; Other Information: canastasio@ucdavis.edu
Country of Publication:
United States
Language:
English
Subject:
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