Distribution and Evolution of Fukushima Dai-ichi derived ¹³⁷Cs, ⁹⁰Sr, and ¹²⁹I in Surface Seawater off the Coast of Japan

Abstract

The Fukushima Dai-ichi Nuclear Power Plants (FDNPPs) accident in 2011 led to an unprecedented release of radionuclides into the environment. Particularly important are 90 Sr and 137 Cs due to their known health detriments and long half-lives (T 1/2 ≈ 30 y) relative to ecological systems. These radionuclides can be combined with the longer-lived 129 I (T 1/2 = 15.7 My) to trace hydrologic, atmospheric, oceanic, and geochemical processes. This study seeks to evaluate 137 Cs, 90 Sr, and 129 I concentrations in seawater off the coast of Japan, reconcile the sources of contaminated waters, and assess the application of 137 Cs/ 90 Sr, 129 I/ 137 Cs, and 129 I/ 90 Sr as oceanic tracers. We present new data from October 2015 and November 2016 off the coast of Japan, with observed concentrations reaching up to 198 ± 4 Bq•m −3 for 137 Cs, 9.1 ± 0.7 Bq•m −3 for 90 Sr, and (114 ± 2) × 10 −5 Bq•m −3 for 129 I. The utilization of activity ratios suggests a variety of sources, including sporadic and independent releases of radiocontaminants. Though overall concentrations are decreasing, concentrations are still elevated compared to pre-accident levels. In addition, Japan's Environment Minister has suggested that stored water from the FDNPPs may be released into the environment and thus continued efforts to understand the fate and distribution of these radionuclides is warranted.

Iodate Reduction by Shewanella oneidensis Requires Genes Encoding an Extracellular Dimethylsulfoxide Reductase

“…129 I is found in contaminated groundwater at the U.S. Department of Energy Savannah River and Hanford Superfund sites from a long history of nuclear weapons testing ( Emerson et al, 2014 ; Timar et al, 2014 ; Bagwell et al, 2019 ). Following the 2011 Fukushima nuclear reactor catastrophe, westerly winds deposited a large portion of 129 I in the Pacific Ocean, where radioactive IO 3 – and I – are the predominant 129 I forms ( Hou et al, 2007 , 2013 ; Bluhm et al, 2011 ; Kenyon et al, 2020 ). IO 3 – is more thermodynamically stable in seawater than I – ; however, significant quantities of I – are detected in anaerobic environments such as anaerobic basins and oxygen minimum zones in marine environments, which potentially indicates that microbial IO 3 – reduction is a major component of the iodine biogeochemical reaction network ( Whitehead, 1984 ; Councell et al, 1997 ; Farrenkopf et al, 1997 ; Wong et al, 2002 ; Chance et al, 2007 ; Bluhm et al, 2010 ; Amachi, 2013 ; Kaplan et al, 2014 ; Fuge and Johnson, 2015 ; Guido-Garcia et al, 2015 ).…”

Influence of Increased Radiation Background on Antioxidative Responses of Helianthus tuberosus L.

“…As a result of anthropogenic impact (accidents at nuclear facilities, nuclear weapons testing), radionuclides such as 131 I, 137 Cs, and 134 Cs and others enter the environment. Among the radionuclides accumulated in the environment, primarily in soils, the most dangerous и prevalent is 137 Cs, since it has a relatively long half-life compared to other radioactive substances [ 37 ]. In the territories affected by the Chornobyl accident, the main dose-forming radionuclide is 137 Cs, according to the report presented at the Chornobyl Forum [ 23 ].…”

Voxelized scomber japonicus phantom and its application for internal dose evaluation by Monte Carlo calculations

“…The Monte Carlo toolkit Geant4 was utilized to conduct radiation transport calculations of AF values with the voxelized scomber japonicus phantom for monoenergetic photons and electrons, resulting in a database that can be utilized for dose calculations of any radioactive contaminations. Moreover, considering the enormous emissions of artificial radionuclides ( 134 Cs, 137 Cs, 131 I and 90 Sr) after the Fukushima Daiichi Nuclear Power Plant accident [26,27], the S-factor values for these radionuclides were calculated using AF values, and compared with that directly calculated through simulation of the whole emission spectra.…”