Institut für Radioökologie und Strahlenschutz
Leibniz Universität Hannover
Iodine-129 and Iodine-127
in the European Environment
Rolf Michel
R. Michel, IRS, Leibniz Universität Hannover
Institut für Radioökologie und Strahlenschutz
Leibniz Universität Hannover
Th. Ernst, A. Daraoui, M. Gorny, K. Gückel, J. Handl,
D. Jakob, J. Korntheuer, R. Sachse, A. Schmidt,
Ch. Schnabel, S. Szidat, L. Tosch
Zentrum für Strahlenschutz und Radioökologie,
Leibniz Universität Hannover
V. Alfimov, H.-A. Synal
Ion Beam Physics, Paul Scherrer Institut und ETH Zürich
H. Nies, J. Herrmann, I. Goroncy
Bundesamt für Seeschifffahrt und Hydrographie, Hamburg
R. Michel, IRS, Leibniz Universität Hannover
1
Content
Sellafield




Iodine-129: characteristics and occurrence
Analytical techniques and state of knowledge
I-129 in the North Sea and elsewhere
I-129 and I-127 in Northern Germany: From
the sea to the continent
 I-129 and I-127 in animals and humans
 Retrospective dosimetry
 Conclusions and perspectives
La Hague
R. Michel,
IRS, Leibniz Universität Hannover
http://rapidfire.sci.gsfc.nasa.gov/gallery/
Relevant Iodine-Isotopes
R. Michel, IRS, Leibniz Universität Hannover
2
I-129 (T1/2 = 15.7 Ma )
129Xe
129I
E,max = 0.2 MeV, E = 39.58 keV, I = 7.52 %
Production in nature
 Cosmic ray induced spallation reactions on Xenon
 Spontaneous fission of Uranium
Natural equilibrium isotopic ratio



= (0.3 - 3.0)  10-12 model calculations
129I/127I =  1.5  10-12
marine hydrosphere
129I/127I = 0.2  10-12
terrestrial biosphere
129I/127I
R. Michel, IRS, Leibniz Universität Hannover
Fission Yields in
235U(n
th,f)
fission yield in %
Y(129I) = 0.74 %
129I/127I
131I/129I
= 6.06
= 3.82
239Pu(n ,f):
th
Y(129I) = 1.6 %
Mass number
R. Michel, IRS, Leibniz Universität Hannover
3
I-129 in the Environment
total natural I-129 inventory
of the Earth:
50 000 kg (327 TBq)
emissions from atmospheric
test explosions: 43 kg – 150 kg
Chernobyl: 2 kg – 6 kg
anthropogenic I-129 emissions
from European reprocessing
plants until 2005
liquid
total free natural I-129 inventory
of atmosphere, hydrosphere,
pedosphere, and biosphere
263 kg
129I/127I
aerial
4720 kg
251 kg
isotopic ratios in environmental compartments ?
~ 10-12 up to ?
~ 10-12
R. Michel, IRS, Leibniz Universität Hannover
World-wide nuclear reprocessing facilities
WAK
Karlsruhe
Nach Santschi (2005) Goldsmith Conference
R. Michel, IRS, Leibniz Universität Hannover
4
Annual 129I Emissions
from Sellafield and La Hague
Sellafield
I-129 Emissionen in Bq a-1
1E+13
1E+12
liquid
total emissions until 2005:
flüssig
liquid 31 TBq; gaseous 1,7 TBq
1E+11
gaseous
luftgetragen
1E+10
1950
1960
1970
1980
1990
2000
2010
Jahr
La Hague
R. Michel, IRS, Leibniz Universität Hannover
Liquid I-129 Discharges to the Sea
1E+13
Sellafield
emission in Bq a-1
1E+12
1E+11
1E+10
1E+09
1E+08
1950
1960
1970
1980
1990
2000
2010
year
total liquid
La Hague liquid
Sellafield liquid
La Hague
R. Michel, IRS, Leibniz Universität Hannover
5
Gaseous I-129 Discharges
Sellafield
emission in Bq a-1
1E+11
1E+10
1E+09
1E+08
1950
1960
1970
1980
1990
2000
2010
year
total gaseous
La Hague gaseous
Sellafield gaseous
La Hague
R. Michel, IRS, Leibniz Universität Hannover
Early Investigations of I-129
by RNAA
R. Michel, IRS, Leibniz Universität Hannover
6
I-129/I-127 Isotopic Ratios
in U.S. Environmental Materials
measured
by RNAA
10-3
10-6
10
10-9
Brauer, 1974
R. Michel, IRS, Leibniz Universität Hannover
Tandem accelerator at ETH Zürich
in the PSI/ETH-AMS-Laboratory
R. Michel, IRS, Leibniz Universität Hannover
7
(129I/127I = 4,7 · 10-10)
TOF-Spectrum
of a Standard
and of a Blank
in an AMS
measurement
(129I/127I = 5 · 10-14)
Wagner, 1995
R. Michel, IRS, Leibniz Universität Hannover
„Small“ AMS Maschine 500 kV – 1 MV
A universal AMS System for Be-10, C-14, Al-26, Ca-41, I-129, Actinides
Charge state +1
R. Michel, IRS, Leibniz Universität Hannover
8
I-129 in a soil column from Nemirovka/Ukraine,
zone III (137Cs: 185 - 555 kBq/m2)
R. Michel, IRS, Leibniz Universität Hannover
What is
normal?
Depth-Profile of the
129I/127I ratio for two
sediment cores from
the continental slope
NE of Cape Hatteras
Fehn et al., 1986
R. Michel, IRS, Leibniz Universität Hannover
9
Pre-nuclear
129I/127I isotopic ratios
129I/127I
isotopic ratios in 10-13
Iodid/Iodat-Sublimat 1918 a+b
2,23 ± 0,22
Iodtinktur 1918 a
2,38 ± 0,19
Iodtinktur 1918 b
1,28 ± 0,311)
Diiodtryosin 1935
2,09 ± 0,75
Geometric mean
2,00 · 1,39 ±1
R. Michel, IRS, Leibniz Universität Hannover
I-129/I-127 in soil profiles from Bavaria and Chile
1E+06
I/
129 127
I in 10-12
1E+05
1E+04
1E+03
1E+02
1E+01
1E+00
1E-01
0
Wald-Kraiburg
Lado Pinguinera
Costal Cordillera
10
20
Untereichet 1
Lado Base
Easter Island 1
30
40
50
depth in cm
Untereichet 2
Curinanco Alto
Easter Island 2
60
Salzburghofer
Curinanco Bajo 1
70
80
Petting
Curinanco Bajo 2
R. Michel, IRS, Leibniz Universität Hannover
10
Annual Fall-Out of
Cl-36 and I-129 in Switzerland
Iodine-129 in mBq m-2 a-1
1E+01
Chlorine-36 in mBq m-2 a-1
1E-02
Cl-36
1E-03
1E-04
Fiescherhorn/Ch
1E+00
I-129
1E-01
1E-02
1940
1E-05
Zurich/Ch
1950
1960
1970
1980
1990
2000
Year
1E-06
1940
1950
1960
1970
1980
1990
Fiescherhorn Glacier / Ch
Year
Synal et al., 1990; Wagner et al., 1996; Schnabel et al., 2001
R. Michel, IRS, Leibniz Universität Hannover
I-129/I-127
isotopic iatios
(in units of 10-10)
in water and
seaweed sampled
between 1984
and 1992
Yiou et al., 1994
our work, 1999-2000:
129/127 = 16 500 · 10-10
R. Michel, IRS, Leibniz Universität Hannover
11
Project StSch 4481
Mapping of Tc-99, I-129 and
I-127 in surface water of the
North Sea
Sellafield
La Hague
R. Michel, IRS, Leibniz Universität Hannover
Bailly du Bois and Dumas (2005)
R. Michel, IRS, Leibniz Universität Hannover
12
Sampling from the North Atlantic by the Polarstern and AWI:
Sampling with FS „Gauss“
Spitzbergen
CTD St. 280
Seawater pump
CTD St. 339
Seawater pump
Seawater pump
Seawater pump
Seawater pump
Seawater pump
78°56.87'N 11°51.64'E
78°49.74'N 5°01.44'E
78°22.50'N 8°02.84'E
78°49.98'N 4°20.04'W
76°49.13'N 8°49.15'W
74°48.39'N 1°58.84'E
69°39.71'N 11°37.09'E
64°57.73'N 6°15.82'E
59°50.52'N 4°13.40'E
05.09.2005; ~9m, 13m
26.08.2005 12:04; 2m, 200m
28.08.2005 13:11; 11m
06.09.2005 19:45; 10m, 200m
10.09.2005 18:14; 11m
11.09.2005 12:20; 11m
13.09.2005 11:20; 11m
14.09.2005 19:11; 11m
16.09.2005 03:42; 11m
Sampling from the Irish Sea by the Endeavour and by ZSR:
Oban
Maror
Ullapool
Stn. 32
Stn. 41
Stn. 33
Stn. 43
56o25’21’’N
56o58’03’’N
57o54’18’’N
54o15’00’’N
54o35’07’’N
54o25’00’’N
54o38’00’’N
05o29’06’'W
05o50’42’’W
05o10’40’’W
03o30’00’’W
03o43’06’’W
03o34’00’’W
03o50’00’’W
1. cruise: German Bight
2. cruise: North Sea
3. cruise: German Bight
4. cruise: German Bight
30.07.2006 13:20
01.08.2006 13:29
06.08.2006 15:15
23.06.2006 16:22
24.06.2006 22:00
24.06.2006 08:10
25.06.2006 10:00
25.05. – 05.06.2005
10.08. – 28.08.2005
29.08. – 05.09.2005
18.11.
– 28.11.2005
R.
Michel, IRS,
Leibniz Universität Hannover
I-129/I-127
in 10-8
129I/127I
in 10-8
R. Michel, IRS, Leibniz Universität Hannover
13
I-129
in mBq m-3
129I
in mBq m-3
R. Michel, IRS, Leibniz Universität Hannover
I-129/I-127
in 10-9
129I/127I
in 10-9
R. Michel, IRS, Leibniz Universität Hannover
14
I-129
in mBq m-3
129I
in mBq m-3
R. Michel, IRS, Leibniz Universität Hannover
1E-05
tideland,
German coast
I-129 / I-127
1E-06
1E-07
1E-08
Baltic Sea &
Elbe estuary
Le Gurp/France
Garonne estuary
1E-09
1E-10
1E-10
1E-09
1E-08
1E-07
1E-06
1E-05
1E-04
I-127 in g/g
sea w ater,R1
Pacific Maui
Indian Ocean
German Bight V/2005
North Sea VIII/2005
North Atlantic VIII/2005
Baltic Sea
German Bight IX/2005
German Bight XI/2005
Irish Sea 2005
Le Gurp, France, 2001
R. Michel, IRS, Leibniz Universität Hannover
15
1E-05
I-129 / I-127
1E-06
tideland,
German coast
1E-07
Baltic Sea &
Elbe estuary
1E-08
Le Gurp/France
Garonne estuary
1E-09
1E-10
1E-18
1E-17
1E-16
1E-15
1E-14
1E-13
1E-12
I-129 in g/g
sea w ater,R1
Pacific Maui
Indian Ocean
German Bight V/2005
North Sea VIII/2005
North Atlantic VIII/2005
Baltic Sea
German Bight IX/2005
German Bight XI/2005
Irish Sea 2005
Le Gurp, France, 2001
R. Michel, IRS, Leibniz Universität Hannover
From sea
to land
R. Michel, IRS, Leibniz Universität Hannover
16
selective filters
lmpactor
Sampled mass in g
Iodine isotopes in air
at Föhr
local aerosol
(maritime)
global
aerosol
mean particle diameter in m
R. Michel, IRS, Leibniz Universität Hannover
Speciation of air-borne iodine at Föhr
127I
127I
129I
129I
129I
129I/127I-ratio
in ng m-3
in %
fg m-3
nBq m-3
in %
10-7
Bound to
particles
> 0,1 m
1,9 ± 0,4
15
1,7 ± 0,2 11,1 ± 1,3
18
8,4 ± 1,8
Organic
5,1 ± 0,8
40
1,6 ± 0,2 10,5 ± 1,3
40
3,1 ± 0,4
Inorganic
< 0,1 m
5,8 ± 0,9
45
0,7 ± 0,1
4,6 ± 0,7
43
1,2 ± 0,2
Sum
12,8 ± 1,2
100
4,0 ± 0,3 26,1 ± 2,0
100
-
R. Michel, IRS, Leibniz Universität Hannover
17
129I
in European
Natural Waters
R. Michel, IRS, Leibniz Universität Hannover
129I/127I
isotopic ratios in quarterly
precipitation in Northern Germany
I-129/I-127 in 10
-8
1000
100
10
Norderney (Freiland)
Buer (Freiland)
Buer (durchfallend)
Siemen (Freiland)
1
Jan. 97 Jan. 98 Jan. 99 Jan. 00 Jan. 01 Jan. 02 Jan. 03 Jan. 04 Jan. 05 Jan. 06
Mitte des vierteljährlichen Probenahmeintervalls
R. Michel, IRS, Leibniz Universität Hannover
18
Quarterly 129I Deposition Rates
in Northern Germany
100,0
Norderney (Freiland)
Buer (Freiland)
Buer (durchfallend)
Siemen (Freiland)
I-129 in mBq m
-2
through-fall precipitation
10,0
1,0
open-field precipitation
0,1
Jan. 97 Jan. 98 Jan. 99 Jan. 00 Jan. 01 Jan. 02 Jan. 03 Jan. 04 Jan. 05 Jan. 06
Mitte des vierteljährlichen Probenhameintervalls
R. Michel, IRS, Leibniz Universität Hannover
Quarterly 127I Deposition Rates
in Northern Germany
10,00
I-127 vierteljährliche Deposition in mg m
-2
through-fall precipitation
1,00
0,10
open-field precipitation
Norderney (Freiland)
Buer (Freiland)
Buer (durchfallend)
Siemen (Freiland)
0,01
Jan. 97 Jan. 98 Jan. 99 Jan. 00 Jan. 01 Jan. 02 Jan. 03 Jan. 04 Jan. 05 Jan. 06
Mitte des vierteljährlichen Probenahmeintervalls
R. Michel, IRS, Leibniz Universität Hannover
19
Annual deposition densities of 129I
in Switzerland (1950–1986) and Germany (1988–2009)
1E+01
-2
I-129 Fallout in mBq m a
-1
1E+02
1E+00
1E-01
Fiescherhorn/Ch
Deutschland
Siemen (Freiland)
Buer (durchfallend)
1E-02
Mappenberg
Norderney (Freiland)
Buer (Freiland)
1E-03
1950
1960
1970
1980
1990
2000
2010
Jahr
R. Michel, IRS, Leibniz Universität Hannover
1E+03
1E+01
1E+02
1E+00
1E-01
1E+01
total annual release in kg
-2
I-129 deposition rate in mBq m a
-1
1E+02
1E-02
1E-03
1950
1960
1970
1980
1990
2000
1E+00
2010
year
Fiescherhorn/Ch
Norderney (open-field)
Buer (through-falling)
Mappenberg
Siemen (open-field)
gaseous releases
Hannover
Buer (open-field)
liquid releases
R. Michel, IRS, Leibniz Universität Hannover
20
129I
and 127I
in soils
R. Michel, IRS, Leibniz Universität Hannover
129I, 127I,
and 129I/127I Ratios in a Soil Profile
from Groß Lobke/Lower Saxony/Germany
I-129 in mBq/m² ; I-127 in g/m²
I-129/I-127 in 1E-10
1000,0
I-129
I-127
I-129/I-127
100,0
10,0
1,0
0,1
0
20
40
60
80
100
120
140
160
180
200
220
depth in cm
Ernst et al., Kerntechnik 68, 155-167 (2003).
R. Michel, IRS, Leibniz Universität Hannover
21
Depth dependence of I-129/I-127 isotopic ratios in soil
profiles from Christinowka, Dowigij-Lis and Schurba
(Ukraine, Zone II)
1E-06
isotopic ratio I-129/I-127
Dowgij-Lis
Shurba
Christinowka
1E-07
1E-08
1E-09
1E-10
0
50
100
150
200
250
depth in cm
R. Michel, IRS, Leibniz Universität Hannover
I-127 in g m-2
1E+01
127I
inventories and
129I/127I Isotope
Ratios in Soils from
Lower Saxony/Germany
1E+00
1E-01
1E-02
0
50
100
150
200
127I
mean annual deposition rate:
4.0  1.21 mg m-2 a-1
mean total inventory:
3,500  1.6±1 mg m-2
I-129/ I-127 isotopic ratio in 10 -10
Surface of individual depth increment in cm
1E+03
1E+02
1E+01
1E+00
1E-01
0
50
100
150
Average depth in cm
200
250
R. Michel, IRS, Leibniz Universität Hannover
22
Balance of 129I and 127I in Region III
of Lower Saxony / Germany
Surface-projected
concentrations
Geometric mean and
standard deviation
127I
129I
in mg m–2
in mBq m–2
3.500 × 1,61
168 × 1,51
Pre-nuclear
< 0,08
Annual deposition densities
through-falling precipitation
Geometric mean and
standard deviation
127I
129I
in mg m-2 a-1 in mBq m-2 a-1
4,0 × 1,21
11 × 1,31
R. Michel, IRS, Leibniz Universität Hannover
1E-05
seawater
1E-06
I-129 / I-127
Rain
1E-07
Surface soils
Surface
water
1E-08
1E-09
Groundwater
1E-10
1E-10
1E-09
235U(n,f): 129I/127I
1E-08
1E-07
I-127 in g/g
1E-06
= 6.06
1E-05
1E-04
updated 23.06.2007
R. Michel, IRS, Leibniz Universität Hannover
23
1E-05
Seawater
1E-06
I-129 / I-127
Rain
1E-07
1E-08
1E-09
Surface
soils
Surface
water
Ground
-water
235U(n,f): 129I/127I
= 6.06
1E-10
1E-19
1E-18
1E-17
1E-16
1E-15
1E-14
I-129 in g/g
1E-13
1E-12
updated 23.06.2007
R. Michel, IRS, Leibniz Universität Hannover
A first conclusion
 I-129 and I-127 in precipitation in Lower
Saxony (Germany) can be completely
explained by the liquid releases into the
sea from Sellafield and La Hague.
 There is no evidence for a significant
influence of the atmospheric releases of
the reprocessing plants on the iodine in
precipitation in Lower Saxony.
R. Michel, IRS, Leibniz Universität Hannover
24
Transfer through
the food chain
and the biospheric
response
R. Michel, IRS, Leibniz Universität Hannover
1E-05
I-129/I-127
1E-06
1E-07
1E-08
1E-09
1975
Animal thyroid glands
1980
1985
1990
1995
2000
2005
year
ren- und Roedeer Sweden
sheep Danmark
bovine Germany
bovine Netherlands
bovine Austria
bovine Belgium
bovine Italy
deer Germany
bovine Germany
sheep Germany
pig Germany
precipitation
deer Germany
R. Hou
Michel,
IRS,
Leibniz Universität Hannover
Data for Danmark:
et al.
(2003)
25
1E-05
129I/127I
I-129/I-127
1E-06
in European human
thyroid
glands
Human thyroid
glands
remote from reprocessing plants
1E-07
Hthyroid = 6 nSv a-1 for adults
1E-08
1E-09
1975
1980
1985
1990
1995
2000
2005
year
Data for Belarus: Hou et al. (2003)
human Hannover
human Hamburg
human Germany
human Belarus
precipitation
R. Michel, IRS, Leibniz Universität Hannover
Institut für Radioökologie und Strahlenschutz
Leibniz Universität Hannover
Retrospective dosimetry of the I-131 exposure in Northern
Ukraine after the Chernobyl accident via AMS-measurements
of I-129 in soils
R. Michel, IRS, Leibniz Universität Hannover
26
Thryroid Cancer in Children under 15 Years Old
until 1998
100
total: 1036 cases
90
number of cases
80
70
Belarus
60
Russ. Fed.
50
Ukraine
40
30
20
10
0
1986
1988
1990
1992
1994
1996
1998
year
UNSCEAR (2000)
R. Michel, IRS, Leibniz Universität Hannover
Mean thyroid doses (Sv) of
children and adolescents
in April/May 1986 in 1034
villages contaminated by
the Chernobyl accident in
Belarus and Ukraine.
Shown are villages with 10
measurements of the 131I
activity in the human
thyroid
(Jacob et al. 2006).
R. Michel, IRS, Leibniz Universität Hannover
27
One of those towns …
Narodici, 75 km away from
the Chernobyl
NPP
R. Michel, IRS, Leibniz
Universität Hannover
Ambient dose
rates measured
in Narodici
27.4. – 2.5.1986
3 R/h = 30 mSv/h
1,7 R/h = 17 mSv/h
0,6 R/h = 6 mSv/h
R. Michel, IRS, Leibniz Universität Hannover
28
Retrospective dosimetry of I-131 via I-129 (T1/2 = 15,7 Ma)
R. Michel, IRS, Leibniz Universität Hannover
Retrospective Dosimetry of I-131 Exposures Using I-129
H thyr  D (129 I )  Dpre  Ch. (129 I )  
A131
 DF (131 I)  f ( t )
A129
Hthyr:
thyroid equivalent dose due to 131I in Sv
D(129I):
measured 129I deposition density in Bq m-2
Dpre-Ch.(129I) = 44  24 mBq m-2 pre-Chernobyl deposition
density in Bq m-2
129I/131I:
isotopic ratio in the Chernobyl fall-out 12 ± 3
 A(131I)/A(129I) = 5,9  107 activity ratio
DF(131I): aggregated dose coefficient for 131I in Sv per Bq m-2
f(t):
correction factor for the time of arrival etc.
R. Michel, IRS, Leibniz Universität Hannover
29
1E+04
D(129I) in mBq m-2
Survey on al measurements
in Belarus and Ukraine as of 2005
1E+03
Lower Saxony
Decision threshold
1E+02
Pre-Chernobyl
deposition
555 kBq m-2
Zone II
185 kBq m-2
1E+01
1E+00
1E+01
1E+02
1E+03
1E+04
1E+05
D(137Cs) in kBq m-2
Straume et al. (1996), Mironov et al. (2002), Michel et al. (2005)
R. Michel, IRS, Leibniz Universität Hannover
129I/131I
atomic ratios for the Chernobyl accident
as of 26.4.1986
material
origin
sampling date
129I/131I
atomic
ratio
26.4.1986
reference
sewage sludge
Berlin/D
May 1986
34.3 ± 2.8
this work
bovine and deer
thyroid glands
Ulm/D, Bad
Hall/A
May - June
1986
27 ± 10
VanMiddlesworth
and Handl (1997)
rain
Munich/D
end of April
1986
19 ± 5
Kutschera et al.
(1988)
rain
Israel
5. May 1986
15 ± 3
Paul et al. (1987)
soil
Belarus
May - June
1986
15 ± 5
Mironov et al. (2002)
soil
Belarus
May 1986
12 ± 3
Straume et al. (1996)
theoretical
estimate
-
-
11 - 15
Ermilov (1993)
theoretical
estimate
-
-
22.8
Kirchner and Noack
(1988)
R. Michel, IRS, Leibniz Universität Hannover
30
131I
Aggregated Dose Coefficients
in Sv per Bq m-2
Pietrzak-Flis et al. (2003)
with CLRP (Krajewski, 1996)
5-years-old
2,5  10-7
children
10-years-old
1,7  10-7
children
5,9  10-8
adults
R. Michel, IRS, Leibniz Universität Hannover


E D (129 I)  exp(    2 2)
Ort
Expectations of deposition densities
and committed thyroid doses
E(Dcorr(I-129))
E(D(I-131))
in Bq m-2
in 106 Bq m-2
Thyroid dose Hthyroid in Gy
5-years-old
10-years-old
adults
Medium contaminated area (Zone III) near Korosten
Nemirovka
0.122
6.41
1.6
1.1
0.38
Woronewo
0.124
6.50
1.6
1.1
0.38
Kupetsch
0.119
6.25
1.5
1.0
0.37
Tschigiri
0.078
4.10
1.0
0.7
0.24
Highly contaminated area (Zone II) near Narodici
Nosdrischtsche
1.060
55.7
14
9.3
3.3
Novo Scharno
0.962
50.5
13
8.4
3.0
Christinovka
0.824
43.3
11
7.2
2.6
R. Michel, IRS, Leibniz Universität Hannover
31
A second investigation:
Validation of the Retrospective Dosimetry
R. Michel, IRS, Leibniz Universität Hannover
Mean thyroid doses (0,1 mGy) of children and adolescents
R. Michel, IRS, Leibniz Universität Hannover
32
Sampling Locations: 2nd campaign
75 km
Sampling in 62 villages,
Mixed soils 40 cm deep,
5 samples per village
Plus three 2 m deep depth profiles.
R. Michel, IRS, Leibniz Universität Hannover
98
290
129I
in mBq m-2
120
62
236
67
48
100
88
96
92
74
123
131
144
258
67
135
110
144
146
153
105
98
2060
418
1281
108
748
524
323
182
578
126
225
407
124
94
380
120
184 421
90
Geometric
means of the
5 soil samples
taken in the
individual
villages in
Ukraine for
I-129 analysis
33
111
70
151
80
62
54
107
149
69
83
82
66
47
129
R. Michel, IRS, Leibniz Universität Hannover
33
Geometric means and standard deviations for all 62 villages
10000
100
129I
in mBq m-2
1000
10
10
100
1000
137Cs
10000
100000
in kBq m-2
R. Michel, IRS, Leibniz Universität Hannover
Individual doses
acc. to measurements of
I-131 activities in thyroid
glands and calculated mean
doses (histogram) for the
Ukrainian village Rudka
Likhtarev et al., Rad. Envir. Biophys. 33 (1994) 149
R. Michel, IRS, Leibniz Universität Hannover
34
1,4
4,3
Hthyr in Gy
Hthyroid in Sv
3,5
1,1
0,10
1,5
1,2
1,8
1,9
2,1
3,8
1,0
2,0
1,6
2,1
2,1
2,3
1,5
1,1
30,3
6,2
18,9
1,3
1,4
1,4
1,3
0,9
0,8
1,0
0,7
1,0
1,2
1,2
1,0
11,0
7,7
1,1
2,7
1,9
1,9
3,3
6,0
2,2
2,7
4,8
8,5
2,3
1,4
5,6
1,8
6,2
Thyroid doses
due to I-131
calculated
from I-129
deposition
densities for
5-years-old
children
0,5
1,6
1,0
2,2
0,7
1,6
R. Michel, IRS, Leibniz Universität Hannover
Thyroid doses derived from I-129 versus doses
derived from direct measurements of I-131 in
thyroid glands for 5-years-old children
thyroid dose in Gy from I-129
100,0
10,0
1,0
Corrected for
pre-Chernobyl
I-129
0,1
0,1
1,0
10,0
100,0
thyroid dose in Gy directly measured
Corrected for pre-Chernobyl background
R. Michel, IRS, Leibniz Universität Hannover
35
Thyroid doses derived from I-129 versus doses
derived from direct measurements of I-131 in
thyroid glands for 10-years-old children
thyroid dose in Gy from I-129
100,0
10,0
Corrected for
pre-Chernobyl
I-129
1,0
0,1
0,1
1,0
10,0
100,0
thyroid dose in Gy directly measured
Corrected for pre-Chernobyl background
R. Michel, IRS, Leibniz Universität Hannover
Retrospective dosimetry

The feasibility of retrospective dosimetry of I-131 exposures via
I-129 has been demonstrated.

The method was validated by comparison with measured thyroid
doses.

The retrospective dosimetry is applicable only in the highly
contamination zones depending on the pre-accident background.

Our retrospective dosimetry in the Northern Ukraine tends to
underestimate the thyroid doses.

The aggregated dose coefficients appear to be too low. This needs
further investigations.

The reasons could be
 individual local situations (pasture and watering conditions of
cattle and others conditions),
 conditions of I-131 deposition (dry or wet), and
 time of arrival of the I-131.
R. Michel, IRS, Leibniz Universität Hannover
36
Conclusions
 The natural abundances of 129I in the environment were
changed by man in a sustainable manner.
 In Europa these changes are going on.
 The releases from reprocessing plants are predominantely
into the sea.
 The 129I/127I system is in an extreme disequilibrium.
 Though 129I is presently not of radiological relevance, the
development of ist environmental abundances should be
closely monitored.

is a radioactive tracer for enviromental processes and
its potential should be used.

129I
129I
is an indicator for the long term human impact on the
environment.
R. Michel, IRS, Leibniz Universität Hannover
Prospects
In order to understand the natural iodine cycle and the
development of man-made changes, we need:
 A systematic description of the ecological pathways of 129I
from sources to sinks including a continuous surveillance
of key release points in Europe and worldwide.
 A detailed bookkeeping of the stable iodine cycle in all
relevant environmental compartments.
 Further investigations of the physical, chemical and
biochemical behavior of the iodine isotopes in atmosphere,
hydrosphere and pedosphere.
 A complete (radio)ecology of 129I and 127I .
R. Michel, IRS, Leibniz Universität Hannover
37
The End
R. Michel, IRS, Leibniz Universität Hannover
38