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Intercomparison of trace metal in atmospheric aerosols collected in Kyoto and Vienna
J. Aerasol Scl., Vol. 23, Suppl. 1, pp. S1003--S1006, 1992 Printed in Great Britain.
0021-8502/92 $5.00 + 0.00 Persumu Press Ltd
INTERCOMPARISON OF TRACEMETAL IN ATMOSPHERIC AEROSOLS COLLECTED IN KYOTO AND VIENNA M. Kasahara, K. Takahashl, R. Hitzenberger* and O. Preining* Institute of Atomic Energy, Kyoto University UJi, Kyoto 611, Japan * Institute fur Experlmentalphysik, Universitat Wien Strudlhofgasse 4, A-1090 Wien, Austria ABSTRACT In Kyoto and Vienna, atmospheric aerosols were collected onto two stacked Nuclepore filters with pore-sizes of 8.0 and 0.4 ~m, respectively. The elemental concentrations of the aerosol samples were determined with the PIXE technique. It was confirmed in both cities that Ca, Ti, Mn, Fe and C1 were dominant in the coarse fraction and S, Pb and Zn were dominant in the fine fraction. The sulfur, especially in fine fraction, and lead content of the Vienna aerosol was about two times higher than those of the Kyoto aerosol. KEYWORDS Atmospheric Aerosols; PIXE Analysis; Elemental Concentration; Kyoto; Vienna. INTRODUCTION The chemical composition of aerosol particles is fundamental to understand the various phenomena and behaviors of aerosols in the atmosphere. PIXE analysis is one of the most powerful microanalyses, which can determine the elemental composition quantitatively in extremely small amounts of samples. The PIXE method has been applied in the research flelds of atmospheric aerosols by a large number of investigators as reviewed in detail by Koltay (1990). In this study, elemental concentrations of atmospheric aerosols collected in Kyoto and Vienna were determined with PIXE technique and the characteristics of atmospheric aerosols in both cities are discussed. SAMPLING AND ANALYSIS The Kyoto group c o l l e c t e d more than 3,000 a e r o s o l samples f o r PIXE a n a l y s i s under v a r i o u s m e t e o r o l o g i c a l and environmental c o n d i t i o n s i n c l u d i n g e p i s o d i c a i r p o l l u t i o n e v e n t s such as Kosa d u s t , photochemical smog, e t c . s i n c e 1986. The Vienna group sampled p e r i o d i c a l l y a t m o s p h e r i c a e r o s o l s i n both daytime and n i g h t t i m e once a month during October 1989 - August 1990. Aerosol p a r t i c l e s were c o l l e c t e d onto two s t a c k e d 47 mm ~ Nuclepore f i l t e r s w i t h d i f f e r e n t p o r e - s i z e s of 8 . 0 and 0 . 4 ~m t o c l a s s i f y t h e a e r o s o l p a r t i c l e s i n t o t h e c o a r s e and f i n e f r a c t i o n s . The flow r a t e was a b o u t 25 Z/rain. The 50Z c u t - o f f s i z e of t h e 8 ~m p o r e - s i z e f i l t e r was e s t i m a t e d a b o u t 1 - 1 . 2 ~m depending on p a r t i c l e d e n s i t y under such sampling c o n d i t i o n s . The sampling time was a d j u s t e d a c c o r d i n g t o t h e p a r t i c l e mass c o n c e n t r a t i o n between 1 t o 8 hours w i t h t y p i c a l sampling t i m e s of 2-4 h o u r s . S1003
S1004
M. KASAHARAet
al.
The PIXE analysis was performed with a 2.0 MeV proton beam from a Tandem accelerator at the Dept.of Nuclear Engineering, Kyoto University. For the calibrations using known concentrations of typical elements, single element standard samples were prepared by the vaccum deposition method (£asahara, et al. 1992). X-rays with 0.1-1.5 KeV energy induced in the sample were detected by a Si(Li) detector after passing through a 78.6 ~m thick Mylar absorber. The concentrations of 15 elements (Si, S, CI, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Br, Pb) were determined.
RESULTS AND DISCUSSION
Comparison of Kyoto and Vienna Aerosols Twenty data sets of the fine and coarse particles were obtained in Vienna excluding the February data. The average elemental concentra- tlons of Kyoto and Vienna aerosols are tabulated in Table I. The values of Kyoto were obtained by averageing 20 data sets selected at random from the large Kyoto data base. Data from all four seasons were included. Sulfur, especlally in the fine fraction, and Pb contents of the Vienna aerosol are about twice those of the Kyoto aerosol. The maximum concentration of sulfur was amounted to 4900 ng/m s in Vienna, which is equivalent to 14.7 ~g/m s as S042-. In Japan, leaded gasoline is prohibited, while in Vienna older vehicles still use it. The large amount of sulfur disturbed the determination of C1 because the small peak of C1 in the PIXE spectrum was overlapped by the large sulfur peak. The detection limit of Cl became worse (about 20 ng/m s ) under our analytical conditions. The concentration of CI in the fine fraction was lower than detectable limit of 20 ng/m 3. The concentration ratios of the fine to the coarse particles of all the elements are shown in FIE.1. It was confirmed in both cities that the elements originating mainly from natural sources such as Ca, Ti, Fe and C1 were dominant in the coarse fraction and that the elements released mainly from anthropogenlc sources or formed secondarily in the atmosphere llke Pb, S and Zn were dominant in the fine fraction. These tendencies correspond to the chemical characteristics of atmospheric aerosols reported by e large number of investigators (e.g. Hldy et al., 1975).
Table 1
Average elemental concentrations of atmospheric aerosols classified into coarse and fine fractions s a m p l e d i n K y o t o and Vienna (in ng/m s) Kyoto
Fine Mass S C1 K Ca Ti
770 <20 130 64 10
V
3.9
Cr
2.9
Mn Fe
8.4 100 3.3 7.2 53
NI
Cu Zn Br
Pb
5,7
33
Coarse 320 260 230 560 57
5.5
Total 1090 260+ 360 620 67
9.4
12
15
17 460 5.9 8.0 35
26 560 9.1 15 88
3.0
11
8,7
44
Fine 26900 1580 <20 160 130 7.2
Vienna Coarse 37730 290 35 120 840 23
5.4
5.3
2.3
4.2
6.7 150 4.5 8.4 33
12 370 6.3 12 17
8.5
60
7.9
23
Total 61330 1870 35+ 280 970 30.0
Ii 6.5
19 520 11 20 50 16
83
Intercompanson o f t r a ~ m e t a l i n atmospheric ~rosols
SI005
C o n c e n t r a t i o n Change of Vienna A e r o s o l s The c o n c e n t r a t i o n s of some e l e m e n t s a r e p l o t t e d t o g e t h e r with t h e t o t a l ( f i n e + c o a r s e ) =ass c o n c e n t r a t i o n i n F i g . 2 f o r t h e Vienna a e r o s o l . The p o i n t s do not mean average or r e p r e s e n t a t i v e c o n c e n t r a t i o n s of t h e c o r r e s p o n d i n g month,
0.8 A
0 0.0 a 0.4 o.z w o o -0.2 Q)-0.4 "~ -0.6
~Vienna
I ~,Kyoto
M ~_~ -0.8 -1
~buB m
s
cl
K
Ca Ti
V
Cr
v~
I~
Ni
Cu
7.n ~
Pb
Element Fig.l
F i n e / c o a r s e r a t i o s o f some e l e m e n t s i n atmospheric a e r o s o l s measured i n Kyoto and Vienna.
~g/m3 150 -
~
~ c
100
= Daytime ~ Nisht tlme
Mass 50 4.0 S
2.0 0.10
Ti 0.05
1.5 Fe 1.0 0.5
Zn 0.05
t-._
0.2 Pb 0.1 0 '89/10
Fig.2
11 12 '90/1 2
3
4
5
6
7
8
Time v a r i a t i o n o f e l e m e n t a l c o n c e n t r a t i o n of a t m o s p h e r i c a e r o s o l s i n Vienna.
SI006
M. K~AR~,
Table 2
et al.
Rotated factor loading matrix for Kyoto and Vienna aerosols
Factor
1
Variance Si S K Ca Ti V Cr
Kyoto 2
1
Vienna 2 3
4
7.05 4.37 1.42
4.28 3.48 2.02 1.67
0.90 0.85 0.91 0.94 0.81 0.54 0.53 0.80 0.63
0.76
Mn
0.78
Fe Ni
O.85 O.52 0.52
Cu Zn
0.83 O. 84
Br Pb
3
0.88 0.79 0.86
0.93 0.52 0.59 0.78 0.56 0.67 0.65
0.59
0.88 0.93
0.82
O.57 0.92
0.79 0.54 0.84 0.79
because only I sample of 3-4 hours sampling time was obtained per month. All elements showed roughly similar changes as the total mass concentration. Therefore, it was supposed that the contribution of local specific sources affecting the sampling point dlrectly was minor. However, Zn concentration had a peak in November in both daytime and nlght-time samples and varied over a wide range. Ni and V had similar tendencies as Zn, Br as Pb, and bin as Ft.
Principal Component Analysis of Kyoto and Vienna Aerosols To examine the sources of the Kyoto and Vienna atmospheric aerosols, the principal component analysis was adopted for each elemental concentration data set. The resulting component patterns are shown in Table 2. All components which had elgenvalues of 1.0 or greater were retained. The first component represents soll dust in both cities. Component 2 in Kyoto and component 2 and 3 in Vienna contains anthropogenic sources such as oil burning or refuse incineration. The fourth component in Vienna represents secondary sulfate aerosols. ACKNOWLEDGEMENTS We greatly appreciate the help of the Zentralanstalt fur Meteorologle und Geodynamik, Nien, Hohe Narte. This study was carried out as a joint research between Kyoto University, Japan and University of Vienna, Austria, which was supported by funds from the Monbusho (Ministry of Education, Culture and Science, Japan) International Scientific Research Program. REFERENCES Hidy, G.M. et a1.(1975). S u m r y of the Callfornla aerosol characterization experiment, J. Air Poll. Control Assoc., 25, 1106-1114. Kasehara, M., K. Takahashi, M. Saklmakaand N. Tomlta (1992). Standard samples and calibration of PIXE analysis, Nucl. Instr. Meth., in printing. Koltay, E.(1990). Elemental analysis of atmospheric aerosols: Results and perspectives of the PIXE technique. Int. J. PIXE, ~, 93-112.
0021-8502/92 $5.00 + 0.00 Persumu Press Ltd
INTERCOMPARISON OF TRACEMETAL IN ATMOSPHERIC AEROSOLS COLLECTED IN KYOTO AND VIENNA M. Kasahara, K. Takahashl, R. Hitzenberger* and O. Preining* Institute of Atomic Energy, Kyoto University UJi, Kyoto 611, Japan * Institute fur Experlmentalphysik, Universitat Wien Strudlhofgasse 4, A-1090 Wien, Austria ABSTRACT In Kyoto and Vienna, atmospheric aerosols were collected onto two stacked Nuclepore filters with pore-sizes of 8.0 and 0.4 ~m, respectively. The elemental concentrations of the aerosol samples were determined with the PIXE technique. It was confirmed in both cities that Ca, Ti, Mn, Fe and C1 were dominant in the coarse fraction and S, Pb and Zn were dominant in the fine fraction. The sulfur, especially in fine fraction, and lead content of the Vienna aerosol was about two times higher than those of the Kyoto aerosol. KEYWORDS Atmospheric Aerosols; PIXE Analysis; Elemental Concentration; Kyoto; Vienna. INTRODUCTION The chemical composition of aerosol particles is fundamental to understand the various phenomena and behaviors of aerosols in the atmosphere. PIXE analysis is one of the most powerful microanalyses, which can determine the elemental composition quantitatively in extremely small amounts of samples. The PIXE method has been applied in the research flelds of atmospheric aerosols by a large number of investigators as reviewed in detail by Koltay (1990). In this study, elemental concentrations of atmospheric aerosols collected in Kyoto and Vienna were determined with PIXE technique and the characteristics of atmospheric aerosols in both cities are discussed. SAMPLING AND ANALYSIS The Kyoto group c o l l e c t e d more than 3,000 a e r o s o l samples f o r PIXE a n a l y s i s under v a r i o u s m e t e o r o l o g i c a l and environmental c o n d i t i o n s i n c l u d i n g e p i s o d i c a i r p o l l u t i o n e v e n t s such as Kosa d u s t , photochemical smog, e t c . s i n c e 1986. The Vienna group sampled p e r i o d i c a l l y a t m o s p h e r i c a e r o s o l s i n both daytime and n i g h t t i m e once a month during October 1989 - August 1990. Aerosol p a r t i c l e s were c o l l e c t e d onto two s t a c k e d 47 mm ~ Nuclepore f i l t e r s w i t h d i f f e r e n t p o r e - s i z e s of 8 . 0 and 0 . 4 ~m t o c l a s s i f y t h e a e r o s o l p a r t i c l e s i n t o t h e c o a r s e and f i n e f r a c t i o n s . The flow r a t e was a b o u t 25 Z/rain. The 50Z c u t - o f f s i z e of t h e 8 ~m p o r e - s i z e f i l t e r was e s t i m a t e d a b o u t 1 - 1 . 2 ~m depending on p a r t i c l e d e n s i t y under such sampling c o n d i t i o n s . The sampling time was a d j u s t e d a c c o r d i n g t o t h e p a r t i c l e mass c o n c e n t r a t i o n between 1 t o 8 hours w i t h t y p i c a l sampling t i m e s of 2-4 h o u r s . S1003
S1004
M. KASAHARAet
al.
The PIXE analysis was performed with a 2.0 MeV proton beam from a Tandem accelerator at the Dept.of Nuclear Engineering, Kyoto University. For the calibrations using known concentrations of typical elements, single element standard samples were prepared by the vaccum deposition method (£asahara, et al. 1992). X-rays with 0.1-1.5 KeV energy induced in the sample were detected by a Si(Li) detector after passing through a 78.6 ~m thick Mylar absorber. The concentrations of 15 elements (Si, S, CI, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Br, Pb) were determined.
RESULTS AND DISCUSSION
Comparison of Kyoto and Vienna Aerosols Twenty data sets of the fine and coarse particles were obtained in Vienna excluding the February data. The average elemental concentra- tlons of Kyoto and Vienna aerosols are tabulated in Table I. The values of Kyoto were obtained by averageing 20 data sets selected at random from the large Kyoto data base. Data from all four seasons were included. Sulfur, especlally in the fine fraction, and Pb contents of the Vienna aerosol are about twice those of the Kyoto aerosol. The maximum concentration of sulfur was amounted to 4900 ng/m s in Vienna, which is equivalent to 14.7 ~g/m s as S042-. In Japan, leaded gasoline is prohibited, while in Vienna older vehicles still use it. The large amount of sulfur disturbed the determination of C1 because the small peak of C1 in the PIXE spectrum was overlapped by the large sulfur peak. The detection limit of Cl became worse (about 20 ng/m s ) under our analytical conditions. The concentration of CI in the fine fraction was lower than detectable limit of 20 ng/m 3. The concentration ratios of the fine to the coarse particles of all the elements are shown in FIE.1. It was confirmed in both cities that the elements originating mainly from natural sources such as Ca, Ti, Fe and C1 were dominant in the coarse fraction and that the elements released mainly from anthropogenlc sources or formed secondarily in the atmosphere llke Pb, S and Zn were dominant in the fine fraction. These tendencies correspond to the chemical characteristics of atmospheric aerosols reported by e large number of investigators (e.g. Hldy et al., 1975).
Table 1
Average elemental concentrations of atmospheric aerosols classified into coarse and fine fractions s a m p l e d i n K y o t o and Vienna (in ng/m s) Kyoto
Fine Mass S C1 K Ca Ti
770 <20 130 64 10
V
3.9
Cr
2.9
Mn Fe
8.4 100 3.3 7.2 53
NI
Cu Zn Br
Pb
5,7
33
Coarse 320 260 230 560 57
5.5
Total 1090 260+ 360 620 67
9.4
12
15
17 460 5.9 8.0 35
26 560 9.1 15 88
3.0
11
8,7
44
Fine 26900 1580 <20 160 130 7.2
Vienna Coarse 37730 290 35 120 840 23
5.4
5.3
2.3
4.2
6.7 150 4.5 8.4 33
12 370 6.3 12 17
8.5
60
7.9
23
Total 61330 1870 35+ 280 970 30.0
Ii 6.5
19 520 11 20 50 16
83
Intercompanson o f t r a ~ m e t a l i n atmospheric ~rosols
SI005
C o n c e n t r a t i o n Change of Vienna A e r o s o l s The c o n c e n t r a t i o n s of some e l e m e n t s a r e p l o t t e d t o g e t h e r with t h e t o t a l ( f i n e + c o a r s e ) =ass c o n c e n t r a t i o n i n F i g . 2 f o r t h e Vienna a e r o s o l . The p o i n t s do not mean average or r e p r e s e n t a t i v e c o n c e n t r a t i o n s of t h e c o r r e s p o n d i n g month,
0.8 A
0 0.0 a 0.4 o.z w o o -0.2 Q)-0.4 "~ -0.6
~Vienna
I ~,Kyoto
M ~_~ -0.8 -1
~buB m
s
cl
K
Ca Ti
V
Cr
v~
I~
Ni
Cu
7.n ~
Pb
Element Fig.l
F i n e / c o a r s e r a t i o s o f some e l e m e n t s i n atmospheric a e r o s o l s measured i n Kyoto and Vienna.
~g/m3 150 -
~
~ c
100
= Daytime ~ Nisht tlme
Mass 50 4.0 S
2.0 0.10
Ti 0.05
1.5 Fe 1.0 0.5
Zn 0.05
t-._
0.2 Pb 0.1 0 '89/10
Fig.2
11 12 '90/1 2
3
4
5
6
7
8
Time v a r i a t i o n o f e l e m e n t a l c o n c e n t r a t i o n of a t m o s p h e r i c a e r o s o l s i n Vienna.
SI006
M. K~AR~,
Table 2
et al.
Rotated factor loading matrix for Kyoto and Vienna aerosols
Factor
1
Variance Si S K Ca Ti V Cr
Kyoto 2
1
Vienna 2 3
4
7.05 4.37 1.42
4.28 3.48 2.02 1.67
0.90 0.85 0.91 0.94 0.81 0.54 0.53 0.80 0.63
0.76
Mn
0.78
Fe Ni
O.85 O.52 0.52
Cu Zn
0.83 O. 84
Br Pb
3
0.88 0.79 0.86
0.93 0.52 0.59 0.78 0.56 0.67 0.65
0.59
0.88 0.93
0.82
O.57 0.92
0.79 0.54 0.84 0.79
because only I sample of 3-4 hours sampling time was obtained per month. All elements showed roughly similar changes as the total mass concentration. Therefore, it was supposed that the contribution of local specific sources affecting the sampling point dlrectly was minor. However, Zn concentration had a peak in November in both daytime and nlght-time samples and varied over a wide range. Ni and V had similar tendencies as Zn, Br as Pb, and bin as Ft.
Principal Component Analysis of Kyoto and Vienna Aerosols To examine the sources of the Kyoto and Vienna atmospheric aerosols, the principal component analysis was adopted for each elemental concentration data set. The resulting component patterns are shown in Table 2. All components which had elgenvalues of 1.0 or greater were retained. The first component represents soll dust in both cities. Component 2 in Kyoto and component 2 and 3 in Vienna contains anthropogenic sources such as oil burning or refuse incineration. The fourth component in Vienna represents secondary sulfate aerosols. ACKNOWLEDGEMENTS We greatly appreciate the help of the Zentralanstalt fur Meteorologle und Geodynamik, Nien, Hohe Narte. This study was carried out as a joint research between Kyoto University, Japan and University of Vienna, Austria, which was supported by funds from the Monbusho (Ministry of Education, Culture and Science, Japan) International Scientific Research Program. REFERENCES Hidy, G.M. et a1.(1975). S u m r y of the Callfornla aerosol characterization experiment, J. Air Poll. Control Assoc., 25, 1106-1114. Kasehara, M., K. Takahashi, M. Saklmakaand N. Tomlta (1992). Standard samples and calibration of PIXE analysis, Nucl. Instr. Meth., in printing. Koltay, E.(1990). Elemental analysis of atmospheric aerosols: Results and perspectives of the PIXE technique. Int. J. PIXE, ~, 93-112.