Predicting sediment and cesium-137 discharge from catchments in eastern Fukushima

Kitamura, Akihiro; Yamaguchi, Masatoshi; Kurikami, Hiroshi; Yui, Mikazu; Onishi, Yasuo

doi:10.1016/j.ancene.2014.07.001

Cited by 64 publications

(44 citation statements)

References 22 publications

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“…These results were similar to that of Kitamura et al (2014) who modelled that forest sources account for 24% of the soil loss in the region. The forests in the Fukushima region are not only a reservoir of radiocesium contaminated particulate matter; they are also a potential source of contaminated matter that may be transferred downstream during erosive rainfall events.…”

Section: Management Implicationssupporting

confidence: 80%

“…Of these radionuclides, radiocesium represents the most serious threat for the foreseeable future (Kitamura et al, 2014;Saito and Onda, 2015). Radiocesium is quickly and almost irreversibly bound to fine soil particles (Saito et al, 2014;Sawhiney, 1972) and predominantly stored within the top five centimetres of undisturbed soil profiles Matsuda et al, 2015).…”

Section: Introductionmentioning

confidence: 99%

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Do forests represent a long-term source of contaminated particulate matter in the Fukushima Prefecture?

Laceby

Huon

Onda

et al. 2016

Journal of Environmental Management

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a b s t r a c tThe Fukushima Daiichi Nuclear Power Plant (FDNPP) accident resulted in radiocesium fallout contaminating coastal catchments of the Fukushima Prefecture. As the decontamination effort progresses, the potential downstream migration of radiocesium contaminated particulate matter from forests, which cover over 65% of the most contaminated region, requires investigation. Carbon and nitrogen elemental concentrations and stable isotope ratios are thus used to model the relative contributions of forest, cultivated and subsoil sources to deposited particulate matter in three contaminated coastal catchments. Samples were taken from the main identified sources: cultivated (n ¼ 28), forest (n ¼ 46), and subsoils (n ¼ 25). Deposited particulate matter (n ¼ 82) was sampled during four fieldwork campaigns from November 2012 to November 2014. A distribution modelling approach quantified relative source contributions with multiple combinations of element parameters (carbon only, nitrogen only, and four parameters) for two particle size fractions (<63 mm and <2 mm). Although there was significant particle size enrichment for the particulate matter parameters, these differences only resulted in a 6% (SD 3%) mean difference in relative source contributions. Further, the three different modelling approaches only resulted in a 4% (SD 3%) difference between relative source contributions. For each particulate matter sample, six models (i.e. <63 mm and <2 mm from the three modelling approaches) were used to incorporate a broader definition of potential uncertainty into model results. Forest sources were modelled to contribute 17% (SD 10%) of particulate matter indicating they present a long term potential source of radiocesium contaminated material in fallout impacted catchments. Subsoils contributed 45% (SD 26%) of particulate matter and cultivated sources contributed 38% (SD 19%). The reservoir of radiocesium in forested landscapes in the Fukushima region represents a potential long-term source of particulate contaminated matter that will require diligent management for the foreseeable future.

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Section: Management Implicationssupporting

confidence: 80%

Section: Introductionmentioning

confidence: 99%

Do forests represent a long-term source of contaminated particulate matter in the Fukushima Prefecture?

Laceby

Huon

Onda

et al. 2016

Journal of Environmental Management

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“…1). Because the upper part of the Ukedo River Basin has high levels of radiological contamination, several studies and analyses have been conducted in this basin to examine the features of 137 Cs transport from upstream to downstream (e.g., Kitamura et al 2014;Kurikami et al 2014;Yamada et al 2015). The annual 137 Cs discharge from the Ukedo River into the Pacific Ocean in the first few years after the FDNPP accident was approximately 2.0 TBq, the highest among rivers in the region (Oota River: 0.27vTBq, Odaka River: 0.13 TBq, Maeda River: 0.4 TBq, Kuma River: 0.28 TBq, and Tomioka River: 0.11 TBq) .…”

Section: Investigation Areamentioning

confidence: 99%

“…The numbers of data locations of 137 Cs distribution in seabed sediments in regions shallower than 50 m, as described in Kusakabe et al (2013), Otosaka and Kato (2014), and Black and Buesseler (2014), are 4, 3, and 4, respectively. Moreover, these sampling locations were situated in river mouths that had highly contaminated river basins (e.g., Ukedo River Basin; Kitamura et al 2014;Kurikami et al 2014;Yamada et al 2015). Thornton et al (2013) and NRA (2016) used a towed gamma ray spectrometer along with a depth sensor and a bathymetric survey, which indicated a relationship between the 137 Cs concentrations in seabed sediments and the features of seafloor topography.…”

Section: Introductionmentioning

confidence: 99%

“…Understanding the features of 137 Cs transport from contaminated mountain forests to coastal sinks is key to the revitalization of marine industries. Therefore, evaluations of forest ecosystems and fluvial and lacustrine environments have been conducted (e.g., Funaki et al 2014;Yamaguchi et al 2014;Kitamura et al 2014;Kurikami et al 2014;Yamada et al 2015;Dohi et al 2015;Niizato et al 2016). 137 Cs distribution in shallow seas, which are major settlement areas for particle-sorbed 137 Cs, is a very important factor when studying 137 Cs transport from contaminated mountain forests to coastal sinks.…”

Section: Introductionmentioning

confidence: 99%

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Horizontal and vertical distributions of 137Cs in seabed sediments around the river mouth near Fukushima Daiichi Nuclear Power Plant

Tsuruta

Harada²,

Misonou

et al. 2017

J Oceanogr

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profile of the 137 Cs distributions suggest that they are related to pulse input caused by heavy-rain events. Change in the 137 Cs inventories with depth in this study are larger than those reported in previous studies, indicating earlier results of 137 Cs inventories per unit in seabed sediments in shallow seas, especially near the river mouth, which drains a radiologically highly-contaminated basin, were underestimated.

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Redistribution and export of contaminated sediment within eastern Fukushima Prefecture due to typhoon flooding

Kitamura

Kurikami

Sakuma

et al. 2016

Earth Surf Processes Landf

Self Cite

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Tropical cyclones expose river basins to heavy rainfall and flooding, and cause substantial soil erosion and sediment transport. There is heightened interest in the effects of typhoon floods on river basins in northeast Japan, as the migration of radiocaesium-bearing soils contaminated by the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident will affect future radiation levels. The five main catchments surrounding FDNPP are the Odaka, Ukedo, Maeda, Kuma and Tomioka basins, but little quantitative modelling has been undertaken to identify the sediment redistribution patterns and controlling processes across these basins. Here we address this issue and report catchment-scale modelling of the five basins using the GETFLOWS simulation code. The three-dimensional (3D) models of the basins incorporated details of the geology, soil type, land cover, and used data from meteorological records as inputs. The simulation results were checked against field monitoring data for water flow rates, suspended sediment concentrations and accumulated sediment erosion and deposition. The results show that the majority of annual sediment migration in the basins occurs over storm periods, thus making typhoons the main vectors for redistribution. The Ukedo and Tomioka basins are the most important basins in the region in terms of overall sediment transport, followed by the other three basins each with similar discharge amounts. Erosion is strongly correlated with the underlying geology and the surface topography in the study area. A low permeability Pliocene Dainenji formation in the coastal area causes high surface water flow rates and soil erosion. Conversely, erosion is lower in an area with high permeability granite basement rocks between the Hatagawa and Futaba faults in the centre of the study area. Land cover is also a factor controlling differences in erosion and transport rates between forested areas in the west of the study area and predominantly agricultural areas towards the east. The largest sediment depositions occur in the Ogaki and Takigawa Dams, at the confluence of the Takase and Ukedo Rivers, and at the Ukedo River mouth. Having clarified the sediment redistribution patterns and controlling processes, these results can assist the ongoing task of monitoring radioactive caesium redistribution within Fukushima Prefecture, and contribute to the design and implementation of measures to protect health and the environment.

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Predicting sediment and cesium-137 discharge from catchments in eastern Fukushima

Cited by 64 publications

References 22 publications

Do forests represent a long-term source of contaminated particulate matter in the Fukushima Prefecture?

Do forests represent a long-term source of contaminated particulate matter in the Fukushima Prefecture?

Horizontal and vertical distributions of 137Cs in seabed sediments around the river mouth near Fukushima Daiichi Nuclear Power Plant

Redistribution and export of contaminated sediment within eastern Fukushima Prefecture due to typhoon flooding

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