Presentation on theme: "14 C from atmospheric nuclear weapons testing – a versatile tracer still sticking around Kristina Stenström Lund University, Sweden SSAMS at Lund University."— Presentation transcript:
14 C from atmospheric nuclear weapons testing – a versatile tracer still sticking around Kristina Stenström Lund University, Sweden SSAMS at Lund University
14 C in atmospheric CO 2 until today… Something drastic happened in the 1900s! n + 14 N 14 C + p 14 C+O 2 14 CO 2
14 C in atmospheric CO 2 (clean air) year Combustion of fossil fuels Bomb-effect 14 C-specific activity Absorption in biosphere and oceans 226 Bq/kg 300 Bq/kg 400 Bq/kg
14 C in atmospheric CO 2 (clean air) year C-specific activity 226 Bq/kg 300 Bq/kg 400 Bq/kg Bomb-pulse dating
Bomb- 14 C – 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
Checking vintages of wine Burchuladze et al, 1989 Zoppi et al, 2004 Tracking narcotics Zoppi, 2004 Bomb- 14 C – some applications Identification of furs of illegaly hunted animals Geyh, 2001
Growth rate of gallstones Druffel & Mok, 1983 Bomb- 14 C – some applications… … in man Age of senile plaques in Alzheimers 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- 14 C – 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 14 C levels in man?
Ingestion (main pathway) Inhalation Dermal absorption How does 14 C reach man? 14 C-level of the diet is crucial! Some factors influencing bomb- 14 C from atmospheric CO 2 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
Different reservoirs From D.D. Harkness, A. Walton, Nature 302 (1972) 302: 14 C specific activity in the late 1960ies: Beef: 360 Bq/kg CFish: 240 Bq/kg C Beef Fish The percentage of sea foods is significant for 14 C specific activity in the diet!
CO 2 MAN Different routes from atmospheric CO 2 to man Varying time lag in the different routes different 14 C-specific activity in different dietary components
Can we date by the year? What influences the contemporary 14 C specific activity??? Natural 14 C Bomb- 14 C How do local variations of 14 C in the environment affect the 14 C levels in man? Volcanos Coal fired power plants Traffic Fossil carbon
Nuclear power generates 14 C! Reactor water Fuel rods Steam Turbine Condensor Generator Sea water
Nuclear power- 14 C 14 C is produced in the fuel reactor water construction materials Waste 14 CO 2 14 C Waste disposal facility SFR
How much 14 C is released to air, land and water? In what chemical form is 14 C released? How is 14 C distributed in the environment? Nuclear power- 14 C Reactor water Fuel rods Steam Turbine Condensor Generator Sea water
Nuclear power- 14 C indeed gives local 14 C-varations… in the vicinity of a reprocessing plant for spent nuclear fuel 447 Bq/kg C 226 Bq/kg C
268 Bq/kg C 511 Bq/kg C Bq/kg C Bq/kg C NOTE! The bomb pulse! Nuclear power- 14 C indeed gives local 14 C-varations… in the vicinity of a Canadian nuclear power plant
Murmansk, 2004 The ship LISA, used for temporary storage of spent nuclear fuel. 448 Bq/kg C Tree leaves grown close to LISA 226 Bq/kg C
Man also produces 14 C 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 14 C Risks for personnel? Man also produces 14 C on purpose… …to use as a tracer e.g. in: Pharmaceutical industry (e.g. microdosing) Ecology, chemistry, biology…
Research centre Rossendorf, Germany At least two potential sources of 14 C release to the environment: 1)a research reactor, which was in operation year , and 2)a radioisotope laboratory, in operation until year NOTE! The bomb pulse! Bq/kg C 226 Bq/kg C
Research centre, Jülich Potential sources of 14 C: 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
14 C in personnel Hair: Indicator of integrated exposure Urine: Indicator of recent exposure Research departments e.g. at Universities Hospitals Pharmaceutical industry Nuclear power industry
14 C in personnel, hair samples, 2007 Note the bombpulse max in 1963!
Summary and conclusions Large variations in 14 C 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 14 C How is bomb-pulse dating affected?