title: (14)C levels in the vicinity of the Fukushima Dai-ichi Nuclear Power Plant prior to the 2011 accident.
abstract: A 50-year-old Japanese cedar (Cryptomeria japonica) from Okuma, ∼1 km southwest of the Fukushima Dai-ichi Nuclear Power Plant, was cored and each annual ring was analysed for (14)C. The (14)C specific activity values varied from 330.4 Bq kg(-1) C in the tree ring formed in 1971 to 231.2 Bq kg(-1) C in the 2014 ring. During the periods 1971-1976 and 2011-2014, the (14)C specific activities are indistinguishable from the ambient background values. However, compared with the ambient atmospheric levels, the (14)C specific activities between 1977 and 2010 are significantly elevated, clearly indicating (14)C discharges from the reactors during their normal operations. In addition, the specific activities are positively correlated with the annual electricity generation values. The excess (14)C specific activities were <36 Bq kg(-1) C, corresponding to an additional annual effective dose of <2 μSv via the food ingestion pathway in the study location. The primary wind direction is east-southeast/southeast with a frequency of ∼30%, in comparison to ∼20% frequency for the direction of the site under study (north-northeast/northeast). This would tend to indicate a similar magnitude of additional effective dose and consequently no significant radiological impact of atmospheric (14)C discharges from the FDNPP during the entire period of normal operations. Additionally, no (14)C pulse in activity can be observed in the year 2011 ring. This might be caused by a limited (14)C release from the damaged reactors during the accident or that the prevailing wind during the short period of release (11th-25th March 2011) was not in the direction of Okuma.
authors.affiliation: Scottish Universities Environmental Research Center (SUERC), East Kilbride G75 0QF, UK; Fukushiam University, Fukushima 960-1296, Japan. Electronic address: sheng.xu@glasgow.ac.uk.
authors.forename: Sheng
authors.initials: S
authors.lastname: Xu
authors.affiliation: Scottish Universities Environmental Research Center (SUERC), East Kilbride G75 0QF, UK.
authors.forename: Gordon T
authors.initials: GT
authors.lastname: Cook
authors.affiliation: Scottish Universities Environmental Research Center (SUERC), East Kilbride G75 0QF, UK; Fukushiam University, Fukushima 960-1296, Japan.
authors.forename: Alan J
authors.initials: AJ
authors.lastname: Cresswell
authors.affiliation: Scottish Universities Environmental Research Center (SUERC), East Kilbride G75 0QF, UK.
authors.forename: Elaine
authors.initials: E
authors.lastname: Dunbar
authors.affiliation: Scottish Universities Environmental Research Center (SUERC), East Kilbride G75 0QF, UK.
authors.forename: Stewart P H T
authors.initials: SP
authors.lastname: Freeman
authors.affiliation: Scottish Universities Environmental Research Center (SUERC), East Kilbride G75 0QF, UK.
authors.forename: Helen
authors.initials: H
authors.lastname: Hastie
authors.affiliation: Center for Nuclear Technologies, Technical University of Denmark, Roskilde 4000, Denmark.
authors.forename: Xiaolin
authors.initials: X
authors.lastname: Hou
authors.affiliation: Scottish Universities Environmental Research Center (SUERC), East Kilbride G75 0QF, UK.
authors.forename: Piotr
authors.initials: P
authors.lastname: Jacobsson
authors.affiliation: Scottish Universities Environmental Research Center (SUERC), East Kilbride G75 0QF, UK.
authors.forename: Philip
authors.initials: P
authors.lastname: Naysmith
authors.affiliation: Scottish Universities Environmental Research Center (SUERC), East Kilbride G75 0QF, UK.
authors.forename: David C W
authors.initials: DC
authors.lastname: Sanderson
authors.affiliation: Scottish Universities Environmental Research Center (SUERC), East Kilbride G75 0QF, UK.
authors.forename: Brian G
authors.initials: BG
authors.lastname: Tripney
authors.affiliation: Fukushiam University, Fukushima 960-1296, Japan.
authors.forename: Katsuhiko
authors.initials: K
authors.lastname: Yamaguchi
mesh_terms: D002250:Carbon Radioisotopes / Q000032:analysis*; D032485:Cryptomeria / Q000737:chemistry*; D062406:Fukushima Nuclear Accident; D007564:Japan; D055848:Nuclear Power Plants; D011834:Radiation Monitoring; D012990:Soil Pollutants, Radioactive / Q000032:analysis*
chemical_list: D002250:Carbon Radioisotopes; D012990:Soil Pollutants, Radioactive
keywords: Anthropogenic (14)C; Cellulose; Cryptomeria japonica tree ring; Fukushima nuclear reactors