Preliminary Numerical Experiments on Oceanic Dispersion of 131I and 137Cs Discharged into the Ocean because of the Fukushima Daiichi Nuclear Power Plant Disaster

Kawamura, Hideyuki; Kobayashi, Takuya; Furuno, Akiko; In, Teiji; Ishikawa, Yoichi; Nakayama, Tomoharu; Shima, Shigeki; Awaji, Toshiyuki

doi:10.3327/jnst.48.1349

Cited by 31 publications

(42 citation statements)

References 8 publications

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“…Approximately 80% of the release was transported over the Pacific Ocean with the remainder predominantly deposited on Fukushima Prefecture soils as a result of wet atmospheric fallout (Kawamura et al, 2011). Estimations of 137 Cs total activity in the Fukushima Prefecture soils range between 10 PBq and 50 PBq, with deposition characterized by strong spatial heterogeneities (Koo et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

Depth distribution of cesium-137 in paddy fields across the Fukushima pollution plume in 2013

Lepage

Evrard

Onda

et al. 2015

Journal of Environmental Radioactivity

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Large quantities of radiocesium were deposited across a 3000 km(2) area northwest of the Fukushima Dai-ichi nuclear power plant after the March 2011 accident. Although many studies have investigated the fate of (137)Cs in soil in the months following the accident, the depth distribution of this radioactive contaminant in rice paddy fields requires further examination after the typhoons that occurred in this region. Such investigations will help minimize potential human exposure in rice paddy fields. Radionuclide activity concentrations, organic content and particle size were analysed in 10 soil cores sampled from paddy fields in November 2013, 20 km north of the Fukushima power plant. Our results demonstrate limited depth migration of (137)Cs with the majority concentrated in the uppermost layers of soils (<5 cm). More than 30 months after the accident, between 46.8 and 98.7% of the total (137)Cs inventories was found within the top 5 cm of the soil surface, despite cumulative rainfall totalling 3300 mm. Furthermore, there were no significant correlations between (137)Cs depth distribution and the other parameters. We attributed the maximum depth penetration of (137)Cs to grass cutting (73.6-98.5% of (137)Cs in the upper 5 cm) and farming operations (tillage - 46.8-51.6% of (137)Cs in the upper 5 cm). As this area is exposed to erosive events, ongoing decontamination works may increase soil erodibility. We therefore recommend the rapid removal of the uppermost - contaminated - layer of the soil after removing the vegetation to avoid erosion of contaminated material during the subsequent rainfall events. Further analysis is required to thoroughly understand the impacts of erosion on the redistribution of radiocesium throughout the Fukushima Prefecture.

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Section: Introductionmentioning

confidence: 99%

Depth distribution of cesium-137 in paddy fields across the Fukushima pollution plume in 2013

Lepage

Evrard

Onda

et al. 2015

Journal of Environmental Radioactivity

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“…These high-frequency measurements have facilitated an evaluation of the total amount of radiocesium derived from the directly discharged radioactive water. The values estimated in several studies were in the range 4–6 PBq1910111213, although one study calculated the value to be 27 PBq (12–41 PBq)14. The total direct release of 27 PBq was somewhat of an overestimate1115 and resulted in activities in a model ocean that were unrealistically high compared to activities measured in the real ocean16.…”

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confidence: 98%

Southward spreading of the Fukushima-derived radiocesium across the Kuroshio Extension in the North Pacific

Kumamoto

Aoyama

Hamajima

et al. 2014

Sci Rep

104

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The accident of the Fukushima Dai-ichi nuclear power plant in March 2011 released a large amount of radiocesium into the North Pacific Ocean. Vertical distributions of Fukushima-derived radiocesium were measured at stations along the 149°E meridian in the western North Pacific during the winter of 2012. In the subtropical region, to the south of the Kuroshio Extension, we found a subsurface radiocesium maximum at a depth of about 300 m. It is concluded that atmospheric-deposited radiocesium south of the Kuroshio Extension just after the accident had been transported not only eastward along with surface currents but also southward due to formation/subduction of subtropical mode waters within about 10 months after the accident. The total amount of decay-corrected 134Cs in the mode water was an estimated about 6 PBq corresponding to 10–60% of the total inventory of Fukushima-derived 134Cs in the North Pacific Ocean.

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“…In particular, 134 Cs and 137 Cs concentrations at the nuclear power plant ocean discharge channels peaked in early April at levels that reached several millions times higher compared with the preexisting levels in this area (Buesseler et al, 2011), thus representing the most important accidental artificial radioactive release into the sea (Bailly du Bois et al, 2011). Simulations of regional ocean models using 137 Cs concentrations in the ocean off Fukushima allowed estimating the total amount of 137 Cs directly discharged to the ocean, ranging from 1 to more than 20 PBq (Kawamura et al, 2011;Tsumune et al, 2012;Bailly du Bois et al, 2011).…”

Section: Introductionmentioning

confidence: 99%

<sup>90</sup>Sr and <sup>89</sup>Sr in seawater off Japan as a consequence of the Fukushima Dai-ichi nuclear accident

Masqué²,

et al. 2013

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Abstract. The impact of the earthquake and tsunami on the east coast of Japan on 11 March 2011 caused a loss of power at the Fukushima Dai-ichi nuclear power plant (NPP) that resulted in one of the most important releases of artificial radioactivity into the environment. Although several works were devoted to evaluating the atmospheric dispersion of radionuclides, the impact of the discharges to the ocean has been less investigated. Here we evaluate the distribution of Fukushima-derived 90Sr (n = 57) and 89Sr (n = 19) throughout waters 30–600 km offshore in June 2011. Concentrations of 90Sr and 89Sr in both surface waters and shallow profiles ranged from 0.8 ± 0.2 to 85 ± 3 Bq m−3 and from 19 ± 6 to 265 ± 74 Bq m−3, respectively. Because of its short half-life, all measured 89Sr was due to the accident, while the 90Sr concentrations can be compared to the background levels in the Pacific Ocean of about 1.2 Bq m−3. Fukushima-derived radiostrontium was mainly detected north of Kuroshio Current, as this was acting as a southern boundary for transport. The highest activities were associated with near-shore eddies, and larger inventories were found in the closest stations to Fukushima NPP. The data evidence a major influence of direct liquid discharges of radiostrontium compared to the atmospheric deposition. Existing 137Cs data reported from the same samples allowed us to establish a 90Sr / 137Cs ratio of 0.0256 ± 0.0006 in seawater off Fukushima, being significantly different than that of the global atmospheric fallout (i.e., 0.63) and may be used in future studies to track waters coming from the east coast of Japan. Liquid discharges of 90Sr to the ocean were estimated, resulting in an inventory of 53 ± 1 TBq of 90Sr in the inshore study area in June 2011 and total releases of 90Sr ranging from 90 to 900 TBq, depending upon the reported estimates of 137Cs releases that are considered.

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Preliminary Numerical Experiments on Oceanic Dispersion of 131I and 137Cs Discharged into the Ocean because of the Fukushima Daiichi Nuclear Power Plant Disaster

Cited by 31 publications

References 8 publications

Depth distribution of cesium-137 in paddy fields across the Fukushima pollution plume in 2013

Depth distribution of cesium-137 in paddy fields across the Fukushima pollution plume in 2013

Southward spreading of the Fukushima-derived radiocesium across the Kuroshio Extension in the North Pacific

<sup>90</sup>Sr and <sup>89</sup>Sr in seawater off Japan as a consequence of the Fukushima Dai-ichi nuclear accident

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Preliminary Numerical Experiments on Oceanic Dispersion of 131I and 137Cs Discharged into the Ocean because of the Fukushima Daiichi Nuclear Power Plant Disaster

Cited by 31 publications

References 8 publications

Depth distribution of cesium-137 in paddy fields across the Fukushima pollution plume in 2013

Depth distribution of cesium-137 in paddy fields across the Fukushima pollution plume in 2013

Southward spreading of the Fukushima-derived radiocesium across the Kuroshio Extension in the North Pacific

&lt;sup&gt;90&lt;/sup&gt;Sr and &lt;sup&gt;89&lt;/sup&gt;Sr in seawater off Japan as a consequence of the Fukushima Dai-ichi nuclear accident

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<sup>90</sup>Sr and <sup>89</sup>Sr in seawater off Japan as a consequence of the Fukushima Dai-ichi nuclear accident