Mineral composition characteristics of radiocesium sorbed and transported sediments within the Tomioka river basin in Fukushima Prefecture

Hagiwara, Hiroki; Konishi, Hiromi; Nakanishi, Takahiro; Fujiwara, Kenso; Iijima, Kazuki; Kitamura, Akihiro

doi:10.1016/j.jenvrad.2019.106042

Cited by 3 publications

(12 citation statements)

References 27 publications

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“…10,11 Feldspar has a small adsorption capacity, but due to its abundance in the coastal environment, it is considered that a large amount of radiocesium is incorporated into sandy sediments. 12,13 As a result, this exchangeable radiocesium increases the concentration in the pore water, followed by diffusion, and bioturbation in the sediment may control the transport of the dissolved radiocesium to the seawater overlying the seabed. It has been reported that radiocesium desorbs into the pore water by exchanging with cations such as ammonium and manganese ions generated in a reduced sediment even in a freshwater system in which the adsorption of cesium to sediments is stronger than that in seawater.…”

Section: ■ Introductionmentioning

confidence: 99%

“…Uptake of cesium in crystal lattices in clay minerals, especially illite, is basically irreversible in freshwater systems, but it is well established that some proportion of cesium is desorbed in high ionic strength media such as seawater. , Feldspar has a small adsorption capacity, but due to its abundance in the coastal environment, it is considered that a large amount of radiocesium is incorporated into sandy sediments. , As a result, this exchangeable radiocesium increases the concentration in the pore water, followed by diffusion, and bioturbation in the sediment may control the transport of the dissolved radiocesium to the seawater overlying the seabed. It has been reported that radiocesium desorbs into the pore water by exchanging with cations such as ammonium and manganese ions generated in a reduced sediment even in a freshwater system in which the adsorption of cesium to sediments is stronger than that in seawater. , In recent years, it has become clear that highly radioactive fine particles locally contribute to high radiation levels near the seabed .…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Behavior of Radiocesium in Sediments in Fukushima Coastal Waters: Verification of Desorption Potential through Pore Water

Otosaka

Kambayashi

Fukuda

et al. 2020

Environ. Sci. Technol.

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Concentrations of 137Cs in seawater, seabed sediment, and pore water collected from the area around Fukushima were investigated from 2015 to 2018, and the potential of coastal sediments to supply radiocesium to the bottom environment was evaluated. The 137Cs concentration in the pore water ranged from 33 to 1934 mBq L–1 and was 10–40 times higher than that in the overlying water (seawater overlying within 30 cm on the seabed). At most stations, the 137Cs concentrations in the overlying water and the pore water were approximately proportional to those in the sediment. The conditional partition coefficient between pore water and sediment was [0.9–14] × 102 L kg–1, independent of the year of sampling. These results indicated that an equilibrium of 137Cs between pore water and sediment has been established in a relatively short period, and 137Cs in the pore water is gradually exported to seawater near the seabed. A simple box model estimation based on these results showed that 137Cs in the sediment decreased by about 6% per year by desorption/diffusion of 137Cs from the seabed.

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Section: ■ Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Behavior of Radiocesium in Sediments in Fukushima Coastal Waters: Verification of Desorption Potential through Pore Water

Otosaka

Kambayashi

Fukuda

et al. 2020

Environ. Sci. Technol.

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“…Rain events during wet weather have been shown to enhance remediation in human-affected areas (paddy fields, farmland and urban areas) and road surface deposits containing 137 Cs 28,29 . The 137 Cs that was deposited in the Tomioka river basin near the FDNPS was transported downstream to the ocean after binding to soil particles in river runoff 30 . During the rainy season (May to July) and typhoon season (August to October) in Japan, large amounts of runoff erode unstable stream banks.…”

Section: Discussionmentioning

confidence: 99%

Radiocesium levels in contaminated forests has remained stable, even after heavy rains due to typhoons and localized downpours

Taira

Matsuo

Yamaguchi

et al. 2020

Sci Rep

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In recent years, Japan has suffered serious damage due to natural disasters such as earthquakes, heavy rains due to tropical storms (typhoons) and localized downpours. To assess the chronological changes in the attenuation of external exposure doses and environmental radiation contamination due to the rainfall associated with typhoons and heavy rains during October to December 2019 in Fukushima, we measured environmental radiation levels in forest areas along the Mt Okura hiking trail in Tomioka Town, Fukushima Prefecture, near the Fukushima Daiichi Nuclear Power Station. We confirmed that (1) current ambient dose rates of 0.38–0.95 μSv/h in most forest areas were 79.9–84.7% higher than in residential areas; (2) the number of sites along the hiking trail where 137Cs was detected was limited (1.1–4.7%); and (3) individual dose rates of 0.21–0.34 μSv/h were lower than ambient dose rates. These findings suggest that radiocesium has remained stable in natural forests that have not been decontaminated even though current levels are low, despite the occurrence of heavy rainfall associated with Super Typhoon Hagibis in 2019 and localized downpours. Hiking while managing exposure to environmental contamination using a personal dosimeter may be the safest model for spending time of leisure activities.

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“…Therefore, studying the particle transport processes and the properties of sediments may be the key to understanding the behavior of radiocesium in freshwater ecosystems (Fan et al 2014). However, it should also be noted that the relation between the distribution of radiocesium and the grain size of sediment particles still remains unclear (Hagiwara et al 2020). It was observed, for example, that the silt-size (2-63 μm) particle fraction of bottom sediments at the midstream Kuchibuto, Kuroiwa, and Fushiguro sites contains more 137 Cs than the clay-size (< 2 μm) particle fraction (Tanaka et al 2015).…”

Section: Introductionmentioning

confidence: 99%

“…Another important factor that could influence the accumulation of 137 Cs in lake sediments is their mineralogical composition (Ashraf et al 2014;Tanaka et al 2015;Huon et al 2018;Hagiwara et al 2020). This influence is due to the sorption and fixation of Cs is particularly determined by the type and amount of phyllosilicate minerals (Sawhney 1972;Zachara et al 2002;Tachi et al 2020a;Park et al 2021).…”

Section: Introductionmentioning

confidence: 99%

Factors controlling 137Cs distribution in bottom sediments of Koronowo Reservoir (Poland)

et al. 2022

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Purpose The main aim of this study was to investigate factors influencing the long-term distribution of 137Cs activity concentrations in the bottom sediments of the dam lake, Koronowo Reservoir, 32 years after the Chernobyl nuclear power plant accident. For this purpose, selected properties of the collected sediment samples, such as grain size, mineralogical composition, and organic matter (OM) content, were investigated. Materials and methods The samples of lake sediments were collected with a Kayak-type gravity corer. The spatial and vertical distributions of 137Cs and 40K activity concentrations in the bottom sediments were investigated based on gamma spectrometry measurements. The particle size distribution of surface lake sediments was determined using a laser particle size analyzer. SEM and XRD were used for the mineralogical analysis of the collected sediment samples. Additionally, the content of organic matter was examined in all samples using an elemental analyzer. Results The 137Cs content was significantly elevated in the case of fine-grained (< 63 µm) surface lake sediments (classified as silts, which are deposited in the profundal zone of Koronowo Lake) and ranged from 12.5 ± 4.1 to 29.2 ± 4.0 Bq kg−1. It was found that the increased concentration of 137Cs activity is more closely related to the content of the silt fraction (2–63 µm) than to the clay fraction (< 2 µm) in the collected surface lake sediments. The content of clay minerals also showed a significant positive correlation with 137Cs activity concentration in the surface lake sediments of Koronowo Lake. A similar relationship was noticed for the OM content, but it may be suspected that it is the result of radiocesium-bearing particle accumulation in OM-rich sediments. Conclusion The most important factor influencing the spatial distribution of 137Cs activity concentrations in the surface lake sediments of Koronowo Lake, apart from the bottom morphology and grain size of sediments, is the content of clay minerals. Moreover, the increased detrital inflow to the lake after the construction of the dam could have probably affected the vertical distribution of 137Cs activity concentrations in the bottom sediments, as evidenced by, e.g., the measurements of 40K activity concentration.

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Mineral composition characteristics of radiocesium sorbed and transported sediments within the Tomioka river basin in Fukushima Prefecture

Cited by 3 publications

References 27 publications

Behavior of Radiocesium in Sediments in Fukushima Coastal Waters: Verification of Desorption Potential through Pore Water

Behavior of Radiocesium in Sediments in Fukushima Coastal Waters: Verification of Desorption Potential through Pore Water

Radiocesium levels in contaminated forests has remained stable, even after heavy rains due to typhoons and localized downpours

Factors controlling 137Cs distribution in bottom sediments of Koronowo Reservoir (Poland)

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