Contribution of 137Cs-enriched particles to radiocesium concentrations in seafloor sediment: Reconnaissance experiment

Ikenoue, Takahito; Ishii, Nobuyoshi; Kusakabe, Masashi; Takata, Hyoe

doi:10.1371/journal.pone.0204289

Cited by 12 publications

(3 citation statements)

References 20 publications

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“…Autoradiography images on the IP were scanned by a Fluor Image Analyzer (FLA-5100, Fuji Photo Film Co., Ltd.) using a 635 nm laser. The activity of the CsMPs was determined according to Ikenoue et al…”

Section: Methodsmentioning

confidence: 99%

Factors of the slow decline in the activity concentration of ¹³⁷Cs in eutrophic lake water

Ishii,

Furota,

Tagami

et al. 2024

ACS EST Water

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We investigated the activity concentrations of dissolved 137Cs, particulate 137Cs, and total 137Cs (the sum of dissolved and particulate 137Cs) in Lake Inba, Japan, from 2019 to 2022 to predict the long-term decline in the 137Cs contamination. The effective half-lives of dissolved and total 137Cs were 2.9 and 18.1 years, respectively. We also observed no decreasing trend of particulate 137Cs. These results suggested that the more gradual decrease in the total 137Cs is caused by the small decline in particulate 137Cs. To decrease the total 137Cs, particulate 137Cs must be decreased. We found that the particulate 137Cs concentrations were correlated with the suspended solid (SS) and volatile suspended solid (VSS) concentrations and that the SS concentrations were positively correlated with the chlorophyll a concentrations. Phytoplankton, which are the chlorophyll a host, are classified into the particulate fraction, and thus, particulate 137Cs were contained in phytoplankton that had accumulated 137Cs. We think that phytoplankton is also an important component of particulate 137Cs in eutrophic lakes although the main factor determining particulate 137Cs concentration is inorganic SS. Since phytoplankton is a food resource for fish, it is necessary to examine in detail the relationship of 137Cs contamination of fish with particulate 137Cs and phytoplankton.

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Section: Methodsmentioning

confidence: 99%

Factors of the slow decline in the activity concentration of ¹³⁷Cs in eutrophic lake water

Ishii,

Furota,

Tagami

et al. 2024

ACS EST Water

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“…The amount of these particles is relatively large, and their distribution can be approximated as locally uniform. In fact, the radioactivity concentration did not change even when the samples were measured after dividing them into five pieces of 15 g each [21]. Therefore, type A particles are not a concern in this study because it does not directly affect the results of the wide-area surveys using the towed spectrometer.…”

Section: Introductionmentioning

confidence: 91%

“…Type A has a small size (1,10 μm) with a large 134 Cs/ 137 Cs ratio (,1.04), and Type B is large (70,400 μm) with a small 134 Cs/ 137 Cs ratio (,0.93). The previous experiments suggested that type A particles are distributed widely in marine sediment, and 9,64% of cesium is composed of this type of particle [21].…”

Section: Introductionmentioning

confidence: 93%

Analysis of radioactive cesium-enriched particles and measurement of their distribution in marine sediment near Fukushima Daiichi nuclear power plant

Ohnishi

Thornton

Koike

et al. 2021

Journal of Nuclear Science and Technology

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Cesium-enriched particles released from the Fukushima Daiich Nuclear Power Plant (NPP1) exist in the Fukushima coastal waters and offshore, and they possibly affect the wide-area distribution of the radioactive cesium measured by the towed spectrometer. Therefore, the distribution of them in marine sediment was measured near NPP1 in November, 2016. We scanned the seafloor using a remotely operated vehicle (ROV) equipped with a NaI(Tl) scintillation detector. The sediment samples were obtained on the survey line by the ROV's suction-type sampler. Five cesium particles, with diameters of approximately 400 μm, were isolated from the samples. The radioactivity of 137 Cs was less than 360 Bq, and no nuclides other than 134 Cs, 137 Cs, and natural radioactive ones were found from gamma-ray spectroscopy. In the particles, titanium and calcium were commonly detected by energy-dispersive X-ray spectrometry. We also estimated the particles' presence from the change in the total counting rate of the scintillation detector. The average particle density is found to be 3.45 � 10 À 2 m À 1 at most. The average increase in the counting rate directly above the cesium-enriched particles in the sediment was less than double. Therefore, the effect of such particles on the distribution of radioactive cesium is limited.

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Spatiotemporal Variation of Radiocesium in Coastal Marine Sediment

Kusakabe

2022

Behavior of Radionuclides in the Environment III

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Contribution of 137Cs-enriched particles to radiocesium concentrations in seafloor sediment: Reconnaissance experiment

Cited by 12 publications

References 20 publications

Factors of the slow decline in the activity concentration of ¹³⁷Cs in eutrophic lake water

Factors of the slow decline in the activity concentration of ¹³⁷Cs in eutrophic lake water

Analysis of radioactive cesium-enriched particles and measurement of their distribution in marine sediment near Fukushima Daiichi nuclear power plant

Spatiotemporal Variation of Radiocesium in Coastal Marine Sediment

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Contribution of 137Cs-enriched particles to radiocesium concentrations in seafloor sediment: Reconnaissance experiment

Cited by 12 publications

References 20 publications

Factors of the slow decline in the activity concentration of 137Cs in eutrophic lake water

Factors of the slow decline in the activity concentration of 137Cs in eutrophic lake water

Analysis of radioactive cesium-enriched particles and measurement of their distribution in marine sediment near Fukushima Daiichi nuclear power plant

Spatiotemporal Variation of Radiocesium in Coastal Marine Sediment

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Factors of the slow decline in the activity concentration of ¹³⁷Cs in eutrophic lake water

Factors of the slow decline in the activity concentration of ¹³⁷Cs in eutrophic lake water