Photon Factory Activity Report 2004 #22 Part B (2005)
Chemistry

12C/2003G086

Chemical speciation of iron in airborne particulate matter by XANES techniqueMotohiro HIRABAYASHI*1,2, Motoyuki MATSUO3, Kiyoshi TANABE2, Shinji KOBAYASHI4,
Masaharu NOMURA5
1

Department of Chemistry, Graduate School of Science, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan
2
Environmental Chemistry Division, National Institute for Environmental Studies, Tsukuba, Ibaraki 305-8506, Japan3
Department of Chemistry, Graduate School of Arts and Sciences, The University of Tokyo,
Meguro-ku, Tokyo 153-8902, Japan
4
PM2.5 & DEP Research Project, National Institute for Environmental Studies, Tsukuba, Ibaraki 305-8506, Japan
5Photon Factory, Institute of Materials Structure Science, KEK, Tsukuba, Ibaraki 305-0801, Japan

Experimental
The following samples were measured as the typicalparticles of which source is different. As vehicle exhaustparticulates, the environmental standard referencematerial #8 “vehicle exhaust particulates” from National
Institute for Environmental Studies was used. The sample
was collected in a traffic tunnel. As city waste
incineration ashes, BCR reference materials #176 “citywaste incineration ash” from Institute for Reference
Materials and Measurements was used. European Coaland Steel Community standard sample, Euro-Standard#877-1 “Furnace Dust” were used as particles about ironmanufacturing industry. The rock standard sample JB-2
“basalt” from Geological Survey of Japan was used as
particles of soil system. In addition, the reagents such asiron nitrate, oxide, sulfate and so on were measured as thepossible chemical species in airborne particles.
The XAFS measurement was performed at BL-12C,
Photon Factory, KEK, Japan[2]. The iron K-edge XANES
spectra of the samples were measured in fluorescencemode using a multi-element solid state detector[3].

42Users' Report

Results and Discussion
Iron K-edge XANES spectra of various particulate
samples were shown in Figure 1. From comparison withthe spectrum of various iron compounds used as referencematerials, it was found that main component of NIES #8
is Fe2(SO4)3, in addition iron (II) silicate minerals andFe2O3 are contained. It is considered that Fe2(SO4)3 andFe2O3 originate from engine combustion or abrasion of an
automobile material. It is considered that iron (II) is therock origin contained in a road pavement. About BCR#176, it is considered that main component is Fe2O3.
About Euro #877-1, the spectrum differed from thespectra of other sources. Moreover, it differed from thespectrum of series of the reference samples of iron greatly,
the identification about the chemical species of thesample was difficult. From comparison with spectrum ofother sources’ samples, the position of absorption edge ofthe spectrum of JB-2 shifted to low energy side. It was
found that JB-2 contains many compounds of iron (II).
In this study, it became clear that chemical species ofiron contained in aerosol changes with sources. That is,chemical species of iron contained in aerosol have been
explained in terms of mixture of particles from various
sources.
Normalized absorption coefficientIntroduction
As the useful research technique which observes thechange and presumes source of airborne particulatematter (aerosol), receptor models, such as a Chemical
Mass Balance (CMB) method, are often used. However,when a characteristic component is not contained, thesource apportionment is difficult. Therefore, developmentof a new index and analyzing method has been requiredfor elucidation of contribution of airborne particulatematter.
XAFS spectroscopy is one of the powerful methods forchemical speciation of samples with low elementalconcentration. The abundance ratio of every chemicalspecies can be calculated by XAFS spectroscopy
combining the PLS method[1]. That is, the amount of
every chemical species can be calculated from PLS resultand elemental concentration. If the chemical specieschange with sources, the amount of chemical species canbe used for a new index of receptor models.
In this study, in order to elucidate whether the XANES
spectrum changes with source, the chemical species of theiron contained in airborne particulate matter withdifferent sources were analyzed.

NIES#8
BCR#176
EURO#877-1
JB-2
7.10

7.12
7.14
Energy / keV

7.16

Figure 1. Iron K-edge XANES spectra of various airborneparticles.
References[1] M. Hirabayashi et al., Anal. Sci., 17, i1581 (2001).
[2] M. Nomura ea al., KEK Report 95-15 (1996).
[3] M. Nomura, KEK Report 98-4 (1998).
* hirabayashi.motohiro@nies.go.jp