14C from atmospheric nuclear weapons testing – a versatile tracer still sticking around
Kristina Stenström
Lund University, Sweden
SSAMS at Lund University
14C in atmospheric CO2 until today…
Something drastic happened in the 1900’s!
-25000 -20000 -15000 -10000 -5000 0 5000
0
200
400
600
800
14 C
(‰
)
Calendar year
n + 14N→ 14C + p
14C+O2→ 14CO2
1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000 2010
0
200
400
600
800 INTCAL98 Vermunt, CO
2
Schauinsland, CO2
Måryd, Juncus
14 C
(‰
)
Calendar year
14C in atmospheric CO2 (clean air)year 1900-2007
Combustion of fossil fuels
Bomb-effect
14C-specific
activity
Absorption in biosphere and
oceans
226 Bq/kg
300 Bq/kg
400 Bq/kg
1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000 2010
0
200
400
600
800 INTCAL98 Vermunt, CO
2
Schauinsland, CO2
Måryd, Juncus
14 C
(‰
)
Calendar year
14C in atmospheric CO2 (clean air)year 1900-2007
14C-specific
activity
226 Bq/kg
300 Bq/kg
400 Bq/kgBomb-pulse
dating
Bomb-14C – some applications
Dating - forensic science
- retrospective cell dating in man
Studies of • the carbon cycle
• turnover times in biological tissues
Uptake in biosphere and oceans
1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000 2010
0
200
400
600
800 INTCAL98 Vermunt, CO
2
Schauinsland, CO2
Måryd, Juncus
14C
(‰
)
Calendar year
Checking vintages of wineBurchuladze et al, 1989
Zoppi et al, 2004
Tracking narcoticsZoppi, 2004
Bomb-14C – some applications
Identification of furs of illegaly hunted animals
Geyh, 2001
Growth rate of gallstonesDruffel & Mok, 1983
Bomb-14C – some applications…… in man
Age of senile plaques in Alzheimer’s disease
Lovell et al, 2002
Retrospecive cell dating in the brain
Spalding et al, 2005
Dynamics of fat cell turnover
Spalding et al, 2008
Carbon turnover in the human eye lens crystallines
Lynnerup et al, 2008
Bomb-14C – can it tell the history of atherosclerotic placks causing
heart attacks and strokes?
Retrospective cell dating can…
• Provide fundamental insight on the rate of formation of new cells in the human body
• Help to develop new therapies to cure diseases
What is the precision???
Is clean air data from various geographical zones representative for the 14C levels in
man?
• Ingestion (main pathway)• Inhalation• Dermal absorption
How does 14C reach man?14C-level of the diet is
crucial!
Some factors influencing bomb-14C from atmospheric CO2 in various food components of the diet:
• Age (storage time)• Reservoir (terrestrial versus aquatic)• Route through the food chain• Turnover time of cells in animals
1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000 2010
0
200
400
600
800 INTCAL98 Vermunt, CO
2
Schauinsland, CO2
Måryd, Juncus
14C
(‰)
Calendar year
Different reservoirsFrom D.D. Harkness, A. Walton, Nature 302 (1972) 302:
14C specific activity in the late 1960ies: Beef: 360 Bq/kg C Fish: 240 Bq/kg C
1940 1950 1960 1970 1980 1990 2000
0
200
400
600
800
14C
(p
erm
ille
)
Calender year
Beef
Fish
The percentage of sea foods is significant for 14C specific activity in
the diet!
CO2
MAN
Different routes from atmospheric CO2 to man
Varying time lag in the different routes ⇒
different 14C-specific activity in different
dietary components
1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000 2010
0
200
400
600
800 INTCAL98 Vermunt, CO
2
Schauinsland, CO2
Måryd, Juncus
14C
(‰)
Calendar year
Can we date by the year?
What influences the contemporary 14C specific
activity???
Natural 14C Bomb-14C
How do local variations of 14C in the environment
affect the 14C levels in man?
Volcanos
Coal fired power plants
TrafficFossil carbon
Nuclear power generates 14C!
Reactor water
Fuel rods
Steam
Turbine
Condensor
Generator
Sea water
Nuclear power-14C14C is produced in• the fuel• reactor water• construction materials
Waste
14CO2
14C
14CWaste disposal facility
SFR
How much 14C is released to air, land and water?
In what chemical form is 14C released?
How is 14C distributed in the environment?
Nuclear power-14C
Reactor water
Fuel rods
Steam
Turbine
Condensor
Generator
Sea water
Nuclear power-14C indeed gives local14C-varations…
in the vicinity of a reprocessing plant for
spent nuclear fuel
1940 1950 1960 1970 1980 1990 2000 2010
0
200
400
600
800
1000
1200
Grass 1,5 km from Sellafield,UK
14 C
(pe
rmill
e)
Calender year
447 Bq/kg C
226 Bq/kg C
1950 1960 1970 1980 1990 2000 2010 2020 2030
0
5000
10000
15000
20000
Grass 100 km
Grass 2 km NE
Grass 0,8 km NE
Grass 0,7 km E
Grass 1,5 km from Sellafield, UK
14 C
(pe
rmill
e)
Calendar year 226 Bq/kg C
268 Bq/kg C511 Bq/kg C
1 530 Bq/kg C
4 820 Bq/kg C
NOTE! The bomb pulse!
Nuclear power-14C indeed gives local 14C-varations…
in the vicinity of a Canadian nuclear power plant
Murmansk, 2004The ship LISA, used for
temporary storage of spent nuclear fuel.
1950 1960 1970 1980 1990 2000 2010
0
200
400
600
800
1000
1200
14 C
(p
erm
ille
)
Calender year
448 Bq/kg C Tree leaves grown close to
LISA
226 Bq/kg C
Man also produces14C on purpose…
…to use as a tracer e.g. in:• Pharmaceutical industry• Ecology, chemistry, biology…
Release to environment
How are bomb-peak applications affected?
Incorporation into workers using 14C
Risks for personnel?
Man also produces14C on purpose…
…to use as a tracer e.g. in:• Pharmaceutical industry (e.g. microdosing)• Ecology, chemistry, biology…
Research centre Rossendorf, GermanyAt least two potential sources of 14C release to the environment:
1) a research reactor, which was in operation year 1957-1985, and 2) a radioisotope laboratory, in operation until year 1990.
NOTE! The bomb pulse!
1960 1970 1980 1990 20000
2000
4000
6000
8000
10000
Tree 1) Located just outside the radioisotope laboratory and about 400 m west of the reactor
Tree 2) Located about 350 m south of the reactor and 750 south-east of the radioisotope laboratory
14C
(pe
rmill
e)
Calender year
2 370 Bq/kg C
226 Bq/kg C
Research centre, JülichPotential sources of 14C:• several research reactors• laboratories handling radioactive materials
Results:Large local variations•Max 29 % excess for one grass sample (309±4 Bq/kg C),•Max 35 % excess for a moss/soil sample (324±4 Bq/kg C).
Måryd clean air 2004: 240 Bq/kg C
14C in personnel Hair: Indicator of integrated exposure
Urine: Indicator of recent exposure
Research departments e.g. at Universities
HospitalsPharmaceutical industry
Nuclear power industry
0
2000
4000
6000
8000
10000
12000
14000
16000
18000
20000 University Laboratory (national) Pharmaceutical industry Nuclear power industry Bomb peak max in 1963 Background hair (16 persons)
14C
sp
eci
fic a
ctiv
ity (
Bq
/kg
C)
Subject
14C in personnel, hair samples, 2007
Note the bombpulse max
in 1963!
Summary and conclusions
Large variations in 14C specific activity can be seen in:
• Diet of terrestrial origin versus sea food in the late 1960ies• Environment (e.g. close to nuclear installations) • Workers handling 14C
How is bomb-pulse dating affected?