Radiocarbon concentration in modern tree rings from Fukushima, Japan.
A 30-year-old Japanese cedar (Cryptomeria japonica), collected from Iwaki, Fukushima in 2014, was analyzed for the long-lived radionuclide (14)C. Values of Δ(14)C varied from 211.7‰ in 1984 to 16.9‰ in 2013. The temporal Δ(14)C variation can be described as an exponential decline, indistinguishable from the general Northern Hemisphere Zone 2 (NH Zone 2) values in the atmosphere, until at least 1994. Values of Δ(14)C for 1999 and 2004 are slightly depleted compared with NH Zone 2 values, while from 1999 to 2013 the data suggest a clear depletion with a 2-8 ppmV additional CO2 contribution from a (14)C-free (i.e. fossil carbon) source. This change coincides with local traffic increases since two nearby expressways were opened in the 1990's. In addition, the small but visible (14)C pulse observed in the 2011 tree-ring might be caused by release from the damaged reactors during the Fukushima nuclear accident.
Scottish Universities Environmental Research Center (SUERC), East Kilbride, G75 0QF, UK. Electronic address: s.xu@suerc.gla.ac.uk.
Sheng
S
Xu
Scottish Universities Environmental Research Center (SUERC), East Kilbride, G75 0QF, UK.
Gordon T
GT
Cook
Scottish Universities Environmental Research Center (SUERC), East Kilbride, G75 0QF, UK.
Alan J
AJ
Cresswell
Scottish Universities Environmental Research Center (SUERC), East Kilbride, G75 0QF, UK.
Elaine
E
Dunbar
Scottish Universities Environmental Research Center (SUERC), East Kilbride, G75 0QF, UK.
Stewart P H T
SP
Freeman
Scottish Universities Environmental Research Center (SUERC), East Kilbride, G75 0QF, UK.
Helen
H
Hastie
Center for Nuclear Technologies, Technical University of Denmark, 4000 Roskilde, Denmark.
Xiaolin
X
Hou
Scottish Universities Environmental Research Center (SUERC), East Kilbride, G75 0QF, UK.
Piotr
P
Jacobsson
Scottish Universities Environmental Research Center (SUERC), East Kilbride, G75 0QF, UK.
Philip
P
Naysmith
Scottish Universities Environmental Research Center (SUERC), East Kilbride, G75 0QF, UK.
David C W
DC
Sanderson
D002245:Carbon Dioxide; D002250:Carbon Radioisotopes / Q000032:analysis / Q000378:metabolism*; D032485:Cryptomeria / Q000737:chemistry / Q000378:metabolism*; D062406:Fukushima Nuclear Accident; D007564:Japan; D018547:Plant Stems / Q000737:chemistry*; D011834:Radiation Monitoring; D014197:Trees / Q000737:chemistry / Q000378:metabolism*; D014934:Wood / Q000737:chemistry*
D002250:Carbon Radioisotopes; D002245:Carbon Dioxide
Cellulose (14)C; Cryptomeria japonica tree ring; Fossil fuel; Fukushima nuclear accident; Traffic effect