14 C from atmospheric nuclear weapons testing – a versatile tracer still sticking around

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… Somethingdrastichappened in the 1900’s! n + 14N→ 14C + p  14C+O2→ 14CO2

Absorption in biosphere and oceans 14C in atmospheric CO2(clean air)year 1900-2007 14C-specific activity 400 Bq/kg Bomb-effect 300 Bq/kg Combustion of fossil fuels 226 Bq/kg

14C in atmospheric CO2(clean air)year 1900-2007 14C-specific activity 400 Bq/kg Bomb-pulse dating 300 Bq/kg 226 Bq/kg

Bomb-14C – some applications Uptake in biosphere and oceans • Studies of • the carbon cycle • turnover times in biological tissues Dating - forensic science - retrospective cell dating in man

Bomb-14C – some applications Checking vintages of wine Burchuladze et al, 1989 Zoppi et al, 2004 Tracking narcotics Zoppi, 2004 Identification of furs of illegaly hunted animals Geyh, 2001

Bomb-14C – someapplications… … in man Growth rate of gallstones Druffel & Mok, 1983 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 variousgeographicalzones representative for the 14C levels in man?

How does 14C reach man? 14C-level of the diet is crucial! • Ingestion (main pathway) • Inhalation • Dermal absorption • Somefactorsinfluencing bomb-14C from atmospheric CO2 in variousfoodcomponents of the diet: • Age (storage time) • Reservoir (terrestrialversusaquatic) • Route through the foodchain • Turnover time of cells in animals

Different reservoirs From 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 The percentage of sea foods is significant for 14C specific activity in the diet! Beef Fish

Different routes from atmospheric CO2 to man MAN Varying time lag in the different routes ⇒ different 14C-specific activity in different dietary components CO2

Natural 14C Bomb-14C Fossil carbon Can we date by the year? What influences the contemporary 14C specific activity??? Howdolocal variations of 14C in the environmentaffect the 14C levels in man? Coal fired power plants Volcanos Traffic

Nuclear power generates 14C! Generator Turbine Steam Condensor Fuel rods Sea water Reactor water

14CO2 Waste 14C Nuclear power-14C • 14C is produced in • the fuel • reactor water • construction materials SFR Waste disposal facility 14C

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 Generator Turbine Steam Condensor Fuel rods Sea water Reactor water

Nuclear power-14C indeed gives local14C-varations…in the vicinity of a reprocessing plant for spent nuclear fuel 447 Bq/kg C 226 Bq/kg C

Nuclear power-14C indeed gives local14C-varations…in the vicinity of a Canadian nuclear power plant 4 820 Bq/kg C NOTE! The bomb pulse! 1 530 Bq/kg C 511 Bq/kg C 268 Bq/kg C 226 Bq/kg C

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 produces14C on purpose… …to use as a tracer e.g. in: • Pharmaceutical industry • Ecology, chemistry, biology…

Man also produces14C on purpose… …to use as a tracer e.g. in: • Pharmaceutical industry (e.g. microdosing) • Ecology, chemistry, biology… Release to environment Incorporation into workers using 14C Risks for personnel? How are bomb-peakapplicationsaffected?

Research centreRossendorf, Germany • At least two potential sources of 14C release to the environment: • a research reactor, which was in operation year 1957-1985, and • a radioisotope laboratory, in operation until year 1990. 2 370 Bq/kg C NOTE! The bomb pulse! 226 Bq/kg C

Research centre, Jülich • Potential 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 Nuclear power industry Research departments e.g. at Universities Pharmaceutical industry Hospitals

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? Thanks for your attention! • More work needs to be done! • Modelling • Measurements

14 C from atmospheric nuclear weapons testing – a versatile tracer still sticking around