Chernobyl
fallout
studied by
Mössbauer
spectroscopy
V. Rusanov
V. Gushterov
Department of Atomic Physics,
University of Sofia, Bulgaria
H. Winkler
A. X. Trautwein
University of Lübeck, Germany
Computer simulation of the radioactive
contamination distribution over the
northern hemisphere shortly after the
accident.
“Gütlich, Bill, Trautwein: Mössbauer Spectroscopy and Transition Metal Chemistry@Springer-Verlag 2009”
V. Rusanov, V. Gushterov, H. Winkler and A. X. Trautwein, Chernobyl fallout studied by Mössbauer spectroscopy
Air photograph of the destroyed reactor block of the
nuclear plant in Tschernobyl, Ukraine. About
600000 people were exposed to heavy irradiation.
Among the rescue teams about 7000 people died.
According to information from WHO 125000 people
were severely falling sick. Because of danger due to
radioactivity 375000 people had to be resettled.
Even today inhabitants are suffering from the
remainders of the accident. Children in Belarus
experience the highest rate of cancer of the thyroid
gland world wide. Altogether in Ukraine, Belarus
and Russia an area as large as one third of the area
of Germany is contaminated.
Source and Photo: DPA
V. Rusanov, V. Gushterov, H. Winkler and A. X. Trautwein, Chernobyl fallout studied by Mössbauer spectroscopy
Gross beta radioactivity of the atmospheric aerosols
in Sofia (courtesy of Mrs. B. Veleva)
10.00
2001
1999
1997
1995
1993
1989
1987
1985
1981
1979
1977
1975
1971
3000 - 4000 mBq/m
3
100 - 1000 mBq/m
3
10 - 100 mBq/m
3
1 - 10 mBq/m - background values
1969
1967
3
1965
1.00
1991
0-1
100.00
1983
1-2
1000.00
1973
2-3
10000.00
1963
3-4
3
mBq/m
1961
Tests
3
1
3
1
17
11
15
7
17
27
46
83
3
31
77
1
1
8
5
6
1
9
6
5
6
8
2
1
2
1
1959
Year
1945
1946
1947
1948
1949
1950
1951
1952
1953
1954
1955
1956
1957
1958
1959
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
Mean value of gross beta radioactivity
of the atmospheric aer, Bq/m3
V. Rusanov, V. Gushterov, H. Winkler and A. X. Trautwein, Chernobyl fallout studied by Mössbauer spectroscopy
100
2.05.1986
10
1
0.1
0.01
0
5
10
15
20
25
Days after the "zero" day of the Chernobyl accident 26.04.1986
8.05.1986, Sofia
3.05.1986, Sofia
1994, Sofia
Top left - mean value of the beta radioactivity of atmospheric air based on 5 different sampling regions in Bulgaria;
top right and bottom left: autoradiography of air filters dated as shown, the bright spots are “hot particles” with very
high specific radioactivity; bottom right - autoradiography of a tree leaf grown on 90Sr contaminated soil near Sofia.
V. Rusanov, V. Gushterov, H. Winkler and A. X. Trautwein, Chernobyl fallout studied by Mössbauer spectroscopy
Transmission
1.001
A-sites
1.001
Fe3O4 B-sites
Fe3O4
2+
Fe in clay or
silicate minerals
3+
Fe magnetic
3+
Fe in oxyhydroxides
or superparamagnetic
2+
Fe
in clay or
silicate minerals
1.000
1.000
0.999
0.999
0.998
0.998
0.997
Fe2O3
0.997
a
293 K
0.996
3+
Fe in oxyhydroxides
or superparamagnetic
b
77 K
0.996
-8
-6
-4
-2
0
2
4
6
8
-8
-6
-4
-2
0
2
4
6
8
10
Velocity, mm/s
Mössbauer spectra of an air filter collected during 30.04.-05.05.1986 taken at 293 K and 77 K. This sampling time
coincides with the maximum contaminating fallout due to the Chernobyl accident detected in Bulgaria. Measurements
confirmed the presence of large quantities of magnetite Fe3O4, mixtures of various oxyhydroxides mainly γ-FeOOH, a
superparamagnetic component, and Fe3+ in clay and silicate minerals. The Mössbauer spectrum taken at liquid nitrogen
temperature shows that a considerable part of the ultra fine particles of α-Fe2O3 (particle size less than 20 nm) had been in
superparamagnetic state at room temperature. The iron concentration in air of 3.69 μg/m3 was high and typical for days
with large air pollutions.
Transmission
V. Rusanov, V. Gushterov, H. Winkler and A. X. Trautwein, Chernobyl fallout studied by Mössbauer spectroscopy
1.001
Fe2O3
2+
Fe in clay or
silicate minerals
2+
Fe in clay or
silicate minerals
3+
Fe in oxyhydroxides
or superparamagnetic
1.000
1.000
0.999
0.999
0.998
0.998
0.997
0.997
0.996
0.996
a
293 K
0.995
Fe2O3
1.001
Fe in oxyhydroxides
or superparamagnetic
b
77 K
0.995
0.994
FeOOH
3+
0.994
-8
-6
-4
-2
0
2
4
6
8
-8
-6
-4
-2
0
2
4
6
8
10
Velocity, mm/s
Mössbauer spectra of an air filter collected during 06.05-07.05.1986 taken at 293 K and 77 K. Change in the chemical
composition including the presence of α-Fe2O3 and oxyhydroxides, as well as absence of magnetite, were detected. The
iron concentration remained high – 3.61 μg/m3.
V. Rusanov, V. Gushterov, H. Winkler and A. X. Trautwein, Chernobyl fallout studied by Mössbauer spectroscopy
1.001
1.001
Transmission
2+
Fe in clay or
silicate minerals
FeOOH
2+
Fe in clay or
silicate minerals
3+
Fe
in oxyhydroxides
3+
or superparamagnetic
Fe
in oxyhydroxides
or superparamagnetic
1.000
1.000
0.999
0.999
a
293 K
b
77 K
0.998
0.998
-8
-6
-4
-2
0
2
4
6
8
-8
-6
-4
-2
0
2
4
6
8
10
Velocity, mm/s
Mössbauer spectra of an air filter collected during 09.05-10.05.1986 taken at 293 K and 77 K. In the Mössbauer
spectra a magnetically split component was not detected at room temperature. Small quantities of α-FeOOH and γFeOOH were measured in the liquid nitrogen temperature spectrum. The measured iron concentration was extremely
low, 0.79 μg/m3, which is typical for days of small air pollution.
Transmission
V. Rusanov, V. Gushterov, H. Winkler and A. X. Trautwein, Chernobyl fallout studied by Mössbauer spectroscopy
1.001
Fe3O4
Fe2O3
3+
Fe magnetic
Fe3O4
2+
Fe in clay or silicate
3+
minerals
Fe in oxyhydroxides
or superparamagnetic
1.000
1.001
Fe2O3
2+
Fe in clay or silicate
3+
minerals
Fe in oxyhydroxides
or superparamagnetic
FeOOH
1.000
0.999
0.999
0.998
0.998
30.04.-05.05.1986
0.997
30.04.-05.05.1986
0.997
06.05.-07.05.1986
0.996
09.05.-10.05.1986
a
293 K
0.995
-8
-6
-4
06.05.-07.05.1986
0.996
09.05.-10.05.1986
b
77 K
0.995
-2
0
2
4
6
8
-8
-6
-4
-2
0
2
4
6
8
10
Velocity, mm/s
Fit results from the sum of three Mössbauer spectra of air filters collected between 30.04. and 10.05.1986. The
consecutive measurements showed clearly that after the first wave of radioactive contaminations from May 1st to May
5th the concentration of iron in the air dropped considerably. The overall pollution was not caused by a single
radioactive wave. New contaminations and redistribution of the radioactive fallout had been detected.
Transmission
V. Rusanov, V. Gushterov, H. Winkler and A. X. Trautwein, Chernobyl fallout studied by Mössbauer spectroscopy
1.001
Fe3O4
Fe2O3
3+
Fe magnetic
1.001
2+
Fe in clay or silicate
3+
minerals
Fe in oxyhydroxides
or superparamagnetic
1.000
1.000
0.999
0.998
0.998
16.02.-19.02.1992
2+
Fe in clay or silicate
3+
minerals
Fe in oxyhydroxides
or superparamagnetic
FeOOH
0.999
0.997
Fe3O4
Fe2O3
0.997
16.02.-19.02.1992
30.04.-05.05.1986
0.996
30.04.-05.05.1986
0.996
a
293 K
0.995
-8
-6
-4
11.07.-25.07.1990
0.995
-2
0
2
4
6
8
b
77 K
-8
-6
11.07.-25.07.1990
-4
-2
0
2
4
6
8
10
Velocity, mm/s
The results from the first air filter of Chernobyl fallout (black) were compared to results from air filters collected long after
the accident on days of high (red) pollution (windy summer days) and low (blue) pollution (winter days after snowfall). The
comparison confirms the major conclusion that the aerosols collected right after the Chernobyl accident contain magnetite,
Fe3O4. Magnetite is, as usual, nonstoichiometric and partially oxidized to maghemite, γ-Fe2O3. Such contamination of the
air over Sofia is not unusual. In days of high air pollution we detect magnetite, which most probably originates from the
steel production plant near Sofia. Nevertheless, the magnetite concentration in the filter from right after the accident is 2-3
times higher and, therefore, is mainly a result of the polution due to the accident.
V. Rusanov, V. Gushterov, H. Winkler and A. X. Trautwein, Chernobyl fallout studied by Mössbauer spectroscopy
Conclusion
The increase of iron-containing material in the air pollution as a result of the Chernobyl reactor
accident was expected. B. and M. Kopcewiczs were the first to use Mössbauer spectroscopy for such
studies of air filters from Warsaw [1]. Our own results obtained with the filters from Sofia [2] confirm
that for the initial filters, collected during the contaminating fallout (30.04-05.05.1986), the iron
concentration was highest and magnetite Fe3O4 was present. This is most likely due to the fact that
during the accident large amounts of iron-construction materials were destroyed, evaporated and
transported together with the radioactive fallout. The presence of magnetite particles of industrial
origin in air pollutions in Sofia is not exceptional and originates mostly from the steel plant situated
nearby. Nevertheless, the major Chernobyl fallout in Bulgaria happened during four consecutive
holidays after May 1st, and we could assume that on these days the industrial plants had worked on
minimal power. During these days the magnetite concentration in the air filter was 2-3 times higher
compared to that from days with high air pollution in Sofia. This finding confirms that the large part
of the iron-containing contaminations was caused by release from the reactor accident. A definite
conclusion about an increase of the isotope abundance of 57Fe in the Chernobyl fallout cannot be
based on Mössbauer spectroscopy only. Additional mass-spectroscopic measurements are needed.
[1] B. Kopcewicz and M. Kopcewicz, Hyperfine Interactions, Mössbauer study of iron-containing atmospheric
aerosol collected during the Chernobyl accident, 139/140, 657-665 (2002).
[2] V. Rusanov, V. Gushterov, H. Winkler and A. X. Trautwein, Iron-containing atmospheric aerosols in the
Chernobyl fallout, Hyperfine Interactions, 166, 625-630 (2005).
Acknowledgements
The authors are indebted to Mr. V. Mavrodiev for providing the filters. Thanks are due to the Alexander von
Humboldt Foundation, special program Stability Pact for South Eastern Europe (V. R. and A. X. T.).