Characterization of Elemental Composition and Valence State of Cyclone-collected Aerosol Particles Using EDXRF and XAFS at Three Sites in Japan

Abstract

The valence state and concentration of metallic pollutants are important factors contributing to the health effects of respirable particulate matter (PM); however, they have not been well studied. In this study, coarse and fine powder samples of atmospheric PM were collected using a cyclone system at Kanagawa (KO), Saitama (SA), and Fukuoka (FU) in Japan in 2017. Energy dispersive X-ray fluorescence spectroscopy (EDXRF) was used to measure the concentrations of nine metallic elements (Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, and Pb), and X-ray absorption fine structure (XAFS) spectroscopy was used to analyze the valence states of target elements (Cr, Mn, Fe, Cu, and Zn). The EDXRF results indicated that the average contents of Fe, Ti, and Zn were much higher than those of the other six elements in all samples. The XAFS results showed that the major valence states of the elements were Cr(III), Mn(II), Fe(III), Cu(II), and Zn(II). The percentages of Mn(IV), Fe(II), and Cu(0) were higher in KO and SA samples than in FU samples. Mn(0) and Zn(0) were detected in some samples only, and Cu(I) was not detected in any samples. Correlation analysis, principal component analysis, and cluster analysis were performed on the EDXRF and XAFS data of the target elements. The source identification results showed that the sources of metal contaminants in the samples varied considerably between sampling sites and depended on the industrial structure and geographical location of the sampling area. Our findings on the different valence states of the elements may be important for determining the toxicity of PM at different locations.

Iron Oxide and Hydroxide Speciation in Emissions of Brake Wear Particles from Different Friction Materials Using an X-ray Absorption Fine Structure

“…To identify the iron speciation in the brake wear particles and to quantify their contribution, we mainly used the X-ray absorption near edge structure (XANES) to study the valence state of absorbed atoms measured at the Kyushu Synchrotron Radiation Research Center (SAGA-LS) using beamlines 11 and 15 [15,16]. We ensured the quality of the continuous spectra through XAFS measurements using synchrotron radiation [16].…”

“…0.9.26) [25]. The detailed procedures have been described in a previous study [15,16]. The R factors, which are generally used for the evaluation of fitting results, fell in the range of 0.002-0.06 for iron speciation in the linear combination fitting analysis.…”

“…The goal of this study was therefore to characterize the possible contribution of iron oxides and hydroxides to airborne brake wear particles under realistic vehicle driving and braking conditions with different friction materials. Chemical forms of iron were identified using the X-ray absorption fine structure (XAFS) method [15,16] in order to allow bulk measurements in any solid or liquid state, regardless of the sample phase, to avoid the influence of iron magnetism [7] and to reduce the cumbersome analytical operations that contribute to measurement errors.…”

Iron Oxide and Hydroxide Speciation in Emissions of Brake-Wear Particles from Different Friction Materials using X-ray Absorption Fine Structure

“…To identify the iron speciation in the brake-wear particles and to quantify their contribution, we used mainly X-ray absorption near edge structure (XANES) to study the valence state of absorbed atoms measured at the Kyushu Synchrotron Radiation Research Center (SAGA-LS) using beamlines 11 and 15 [15,16]. We ensured the quality of the continuous spectra through XAFS measurements using synchrotron radiation [16].…”

“…The goal of this study was therefore to characterize the possible contribution of iron oxides and hydroxides to airborne brake-wear particles under realistic vehicle driving and braking conditions with different friction materials. Iron chemical forms were identified using the X-ray absorption fine structure (XAFS) method [15,16] in order to allow bulk measurements in any solid or liquid state regardless of the sample phase, to avoid the influence of iron magnetism [7] and to reduce the cumbersome analytical operations that contribute to measurement errors.…”