Supporting Information for
“Seasonal changes in Fe species and soluble Fe concentration in the
atmosphere in the Northwest Pacific region based on the analysis of
aerosols collected in Tsukuba, Japan”
by Yoshio Takahashi, Takema Furukawa, Yutaka Kanai,
Mitsuo Uematsu, Guodong Zheng, and Matthew A. Marcus
Normalized absorption
2013 April
2006 Dec
7110
7120
7130
7140
Energy (eV)
7150
7160
Figure S1. Iron K-edge XANES for the aerosol sample (February) in Dec. 2006 and May 2013.
Normalized Absorption
hornblende
hematite (-Fe2O3)
ferrihydrite
goethite (-FeOOH)
Fe(III) oxalate
Fe(III) citrate
Fe(III) sulfate
smectite (SWy-2)
illite (IMt-1
magnetite (Fe3O4)
Fe (II) oxide
(b)
August sample
fitting result
Normalized absorption
(a)
chlorite (20%) + smectite (80%)
R (%) = 0.045
7100
7110
7120
7130
7140
7150
7160
Energy (eV)
pyrrhotite (Fe7S8)
pyrite (FeS2)
illite (75%) + magnetite (25%)
R (%) = 0.037
7100 7110 7120
7140 7150 7160
7.10
7.12 7130 7.14
7.16 7170 7180
7.18
Energy (eV)
(c)
August sample
fitting result
Normalized absorption
chlorite (CCa-2)
Fe(II) sulfate
fayalite (Fe2SiO4)
siderite (FeCO3)
7100
7110
7120
7130
7140
7150
7160
Energy (eV)
Figure S2. (a) Iron K-edge XANES for various reference materials. Fitting results of the spectrum of
August sample by the LCF of (b) chlorite and smectite and (c) illite and magnetite are also shown.
hornblende
hematite (-Fe2O3)
ferrihydrite
goethite (-FeOOH)
Fe(III) oxalate
Fe(III) citrate
k (k)
Fe(III) sulfate
3
smectite (SWy-2)
illite (IMt-1)
magnetite (Fe3O4)
chlorite (CCa-2)
fayalite (Fe2SiO4)
siderite (FeCO3)
pyrite (FeS2).
2
4
6o
-1
k (A )
8
10
Figure S3. Iron K-edge EXAFS spectra of various reference materials.
(a)
0.2
3
0.1
2
0
Component 1
Component 2
Component 3
Component 4
1
0
7100 7110 7120 7130 7140 7150 7160 7170 7180
Component
Eigenvalues
Variance
Cumulative
variance
1
8.995467
0.999496
0.999496
2
0.003051
0.000339
0.999835
3
0.000950
0.000106
0.999941
4
0.000407
0.000045
0.999986
Component 1
Component 2
Component 3
Component 4
-0.1
-0.2
7100 7110 7120 7130 7140 7150 7160 7170 7180
Energy (eV)
Energy (eV)
(b)
Normalized absorption
PCA component
4
Sample
Component 1
7100 7110 7120 7130 7140 7150 7160 7170
Energy (eV)
Sample
Component 1+2+3
7110 7120 7130 7140 7150 7160 7170
Energy (eV)
Sample
Component 1+2+3+4
7110 7120 7130 7140 7150 7160 7170 7180
Energy (eV)
Figure S4. (a) Results of PCA analysis for Fe K-edge XANES for various months and (b) fitting
of the spectrum in July by component 1, component 1+2+3, and component 1+2+3+4.
July sample after water extraction
July sample before water extraction
Fe (III) sulfate
Ferrihydrite
(b)
First derivations
(a)
(b)
7100
7110
7120
7130
7140
Energy (eV)
7150
7130
7135
7140
7145
Energy (eV)
Figure S5. Variation of first derivative spectra of the sample in July before and after the
water extraction treatment . Spectra of Fe(III) sulfate and ferrihydrite are also shown.
7150
Ferrihydrite (90%) + Fe (III) sulfate (10%)
Ferrihydrite (80%) + Fe (III) sulfate (20%)
Ferrihydrite (70%) + Fe (III) sulfate (30%)
Fe (III) sulfate (100%)
Ferihydrite (100%)
100
(a)
95
A
90
85
First derivations
Ferrihydrite (%)
(b)
XANES fitting results
Mixed fraction
B
80
C
75
70
0
5
10
15
20
25
30
Fe (III) sulfate (%)
7120
7130
7140
7150
Energy (eV)
7160
Figure S6. Variation of XANES spectra and first derivative spectra for the mixtures of ferrihydrite and Fe(III)
sulfate with their calculated fractions determined by the LCF of the spectra to explain the variation of the
spectra in Fig. S3. (a) Comparison of fitting results with the mixing ratio to prepare the samples; (b) variation
of the first derivative spectra.
Oxalate / FeMQ
Oxalate / FeTotal
2
1.5
10
1
5
0.5
Oxalate / FeTotal (mole ratio)
Oxalate / FeMQ (mole ratio)
15
0
October
September
August
July
June
May
March
February
December
0
Figure S7. Oxalate/FeMQ and oxalate/FeTotal ratios in various months.
4
12
Oxalate (×20)
Sulfate
pH
4.2
8
4.4
pH
Sulfate or Oxalate (g/m3)
10
6
4.6
May, June, and July
4
4.8
2
0
0
20
40
60
80
5
100
FeMQ (ng/m3)
Figure S8. Relationship between sulfate, oxalate, and pH
against FeMQ.
Feb.
Mar.
May
June
July
Aug.
Sep.
Oct.
Dec.
(a) [FeTotal] for the year, by month
(b) [FeSW] for the year, by month
Figure S9. Contributions of Fe in each month relative to total Fe in
all the months examined for (a) [FeTotal] and (b) [FeSW].