Iodine-129 concentration in seawater near Fukushima before and after the accident at the Fukushima Daiichi Nuclear Power Plant 1Japan Atomic Energy Agency, Ibaraki, Japan
14 Jun 2013
2Japan Atomic Energy Agency, Aomori, Japan
Received: 26 Nov 2012 – Published in Biogeosciences Discuss.: 29 Jan 2013 Abstract. Anthropogenic radionuclides were released into the environment in large
quantities by the Fukushima Daiichi Nuclear Power Plant (1FNPP) accident. To
evaluate accident-derived 129I, the 129I concentrations in
seawater before and after the accident were compared.
Revised: 08 May 2013 – Accepted: 14 May 2013 – Published: 14 Jun 2013
Before the accident (2008–2009), the 129I concentrations in the
western margin of the North Pacific between 32° N and 44° N
showed a latitudinal gradient that was expressed as a linear
function of latitude. The highest and average 129I concentrations after
the accident were 73 times and approximately 8 times, respectively, higher
than those before the accident in this study area. Considering the
distribution of 129I in surface seawater, the accident-derived
129I in the southern and northern stations of the 1FNPP was
predominantly supplied by seawater advection and atmospheric deposition
(including microbial volatilization), respectively.
As of October 2011, depth profiles of 129I revealed that 129I
originating from the 1FNPP existed mainly in the upper 100 m depth. From the
depth profiles, the cumulative inventories of accident-derived 129I
were estimated to be (1.6–9.6) × 1012 atoms m−2 in this
On the basis of the 129I data in the seawater near Fukushima, the
effective dose of 129I from seafood ingestion was much smaller than the
annual dose limit.
Citation: Suzuki, T., Otosaka, S., Kuwabara, J., Kawamura, H., and Kobayashi, T.: Iodine-129 concentration in seawater near Fukushima before and after the accident at the Fukushima Daiichi Nuclear Power Plant, Biogeosciences, 10, 3839-3847, doi:10.5194/bg-10-3839-2013, 2013.