title: Radiocarbon Releases from the 2011 Fukushima Nuclear Accident.
abstract: Radiocarbon activities were measured in annual tree rings for the years 2009 to 2015 from Japanese cedar trees (Cryptomeria japonica) collected at six sites ranging from 2.5-38 km northwest and north of the Fukushima Dai-ichi nuclear power plant. The14C specific activity varied from 280.4 Bq kg-1C in 2010 to 226.0 Bq kg-1C in 2015. The elevated14C activities in the 2009 and 2010 rings confirmed14C discharges during routine reactor operations, whereas those activities that were indistinguishable from background in 2012-2015 coincided with the permanent shutdown of the reactors after the accident in 2011. High-resolution14C analysis of the 2011 ring indicated14C releases during the Fukushima accident. The resulted14C activity decreased with increasing distance from the plant. The maximum14C activity released during the period of the accident was measured 42.4 Bq kg-1C above the natural ambient14C background. Our findings indicate that, unlike other Fukushima-derived radionuclides, the14C released during the accident is indistinguishable from ambient background beyond the local environment (~30 km from the plant). Furthermore, the resulting dose to the local population from the excess14C activities is negligible compared to the dose from natural/nuclear weapons sources.
authors.affiliation: Scottish Universities Environmental Research Centre, East Kilbride, G75 0QF, UK.|Institute of Environmental Radioactivity, Fukushima University, Fukushima 960-1296, Japan.
authors.forename: Sheng
authors.initials: S
authors.lastname: Xu
authors.affiliation: Scottish Universities Environmental Research Centre, East Kilbride, G75 0QF, UK.
authors.forename: Gordon T
authors.initials: GT
authors.lastname: Cook
authors.affiliation: Scottish Universities Environmental Research Centre, East Kilbride, G75 0QF, UK.|Institute of Environmental Radioactivity, Fukushima University, Fukushima 960-1296, Japan.
authors.forename: Alan J
authors.initials: AJ
authors.lastname: Cresswell
authors.affiliation: Scottish Universities Environmental Research Centre, East Kilbride, G75 0QF, UK.
authors.forename: Elaine
authors.initials: E
authors.lastname: Dunbar
authors.affiliation: Scottish Universities Environmental Research Centre, East Kilbride, G75 0QF, UK.
authors.forename: Stewart P H T
authors.initials: SPHT
authors.lastname: Freeman
authors.affiliation: Center for Nuclear Technologies, Technical University of Denmark, 4000 Roskilde, Denmark.
authors.forename: Xiaolin
authors.initials: X
authors.lastname: Hou
authors.affiliation: Scottish Universities Environmental Research Centre, East Kilbride, G75 0QF, UK.
authors.forename: Piotr
authors.initials: P
authors.lastname: Jacobsson
authors.affiliation: Scottish Universities Environmental Research Centre, East Kilbride, G75 0QF, UK.
authors.forename: Helen R
authors.initials: HR
authors.lastname: Kinch
authors.affiliation: Scottish Universities Environmental Research Centre, East Kilbride, G75 0QF, UK.
authors.forename: Philip
authors.initials: P
authors.lastname: Naysmith
authors.affiliation: Scottish Universities Environmental Research Centre, East Kilbride, G75 0QF, UK.
authors.forename: David C W
authors.initials: DCW
authors.lastname: Sanderson
authors.affiliation: Scottish Universities Environmental Research Centre, East Kilbride, G75 0QF, UK.
authors.forename: Brian G
authors.initials: BG
authors.lastname: Tripney
mesh_terms: D002250:Carbon Radioisotopes / Q000032:analysis*; D062406:Fukushima Nuclear Accident; D007564:Japan; D011834:Radiation Monitoring / Q000379:methods; D012990:Soil Pollutants, Radioactive / Q000032:analysis*; D014934:Wood / Q000737:chemistry*
chemical_list: D002250:Carbon Radioisotopes; D012990:Soil Pollutants, Radioactive