| Literature DB >> 25917022 |
Sheng Xu1, Gordon T Cook2, Alan J Cresswell2, Elaine Dunbar2, Stewart P H T Freeman2, Helen Hastie2, Xiaolin Hou3, Piotr Jacobsson2, Philip Naysmith2, David C W Sanderson2.
Abstract
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.Entities:
Keywords: Cellulose (14)C; Cryptomeria japonica tree ring; Fossil fuel; Fukushima nuclear accident; Traffic effect
Mesh：
Substances：
Year: 2015 PMID： 25917022 DOI： 10.1016/j.jenvrad.2015.04.004
Source DB: PubMed Journal: J Environ Radioact ISSN： 0265-931X Impact factor: 2.674