Sediment erosion revealed by study of Cs isotopes derived from the Fukushima Dai-ichi nuclear power plant accident

Kanai, Yutaka; Saito, Yoshiki; Tamura, Takeshi; Nguyen, Van Lap; Ta, Thi Kim Oanh; Satô, Akio

doi:10.2343/geochemj.2.0234

Cited by 11 publications

(6 citation statements)

References 10 publications

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“…As for the active‐channel fill, the sand−mud proportions, sedimentary structures and general context suggest a combination of river and tidal processes. The higher concentrations of sand and its increase towards the most basinward core (BL3a) may be due to the wave processes that resuspended mud and increased sand concentrations in these deposits (Tamura et al ., 2010; Kanai et al ., 2013a,b; Fricke et al ., 2017; Stephens et al ., 2017). The trace‐fossil assemblage is not as diverse as for the active channel fill, perhaps because of the higher sedimentation rates and the additional stress generated by wave processes in the river‐mouth area.…”

Section: Resultsmentioning

confidence: 99%

Late Holocene stratigraphic evolution and sedimentary facies of an active to abandoned tide‐dominated distributary channel and its mouth bar

Gugliotta

Saito

Ta³

et al. 2021

Sedimentology

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To better understand the sedimentary facies of tide-dominated deltas, a core dataset from the Ba Lai palaeochannel in the Mekong River Delta was obtained and studied. Nine sedimentary facies were identified and interpreted as representing the Late Holocene evolution of the Ba Lai palaeochannel, including its pre-abandonment and post-abandonment phases, as well as pre-channel phases. The channel formed at 2.6 ka as a distributary channel connected to the deltaic network and was abruptly abandoned and rapidly infilled with sediment at 0.7 ka. The channel deposits are up to ca 11 m thick and overlie shelfal shell layers, which, in turn, overlie Mid-Holocene and Pleistocene deposits. The active-channel fill and mouth-bar deposits consist of sand and mud with cyclical patterns, bidirectional lenses and abundant mud layers, suggesting deposition mainly driven by river and tidal processes. The abandoned-channel fill consists entirely of organic-rich mud, suggesting a predominance of tidal processes. Other sedimentary facies include tidal-flat and marsh deposits; they mostly consist of mud and formed in shallow to subaerial areas near the channel margins or on barforms. Depending on the exact location of the core in this depositional setting, three possible stratigraphic successions and facies models are presented herein. Near channel margins, the deposits show an upward gradual change from heterolithic to mud with a well-developed fining-upward trend. Away from the channel margins, the deposits show an upward sharp change from heterolithic to mud due to the channel abandonment. The mouth-bar-area facies model shows an upward gradual change from heterolithic to heterolithic/ sand to mud deposits with a coarsening-upward to fining-upward trend. Although differences among systems likely exist, the authors suggest that the sedimentary facies described in this study and the resulting facies models should be used to better understand tide-dominated deltaic systems and to improve their interpretation in the geological record.

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Section: Resultsmentioning

confidence: 99%

Late Holocene stratigraphic evolution and sedimentary facies of an active to abandoned tide‐dominated distributary channel and its mouth bar

Gugliotta

Saito

Ta³

et al. 2021

Sedimentology

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“…The migration of the Cs-137 radionuclide through soil was observed in the Goiâ nia accident (IAEA, 1988), and also surrounding the Hanford plant (Flury et al, 2004) where high levels of Cs-137 caused by seepage were detected in sediments and in other studies (McKinley et al, 2001;Bostick et al, 2002;Flury et al, 2002;McKinley et al, 2004;Todorović et al, 1992;Chowdhury et al, 2004). Several studies have assessed the factors that cause adsorption of Cs-137, and the type and location of Cs + ion adsorption in the inner layers and the frayed edge sites (FES) of phyllosilicate minerals, such as vermiculite, illite, kaolinite, muscovite, and others (Figueira & Cunha, 1998;Flury et al, 2004;McKinley et al, 2001;Nyarko et al, 2011;Dion et al, 2005;Bostick et al, 2002;Flury et al, 2002;Lujanienė et al, 2005;McKinley et al, 2004;Todorović et al, 1992;Chowdhury et al, 2004;Komarneni, 1985;Kanai et al, 2013;Rajec et al, 1999;Sawhney, 1970;EPA, 1999;Wahlberg & Fishman, 1962). McKinley et al (2004) reported that the absorption of Cs + ions by phyllosilicate minerals, such as illite and kaolinite, is favorable.…”

Section: Cs-137 In Beach Sandmentioning

confidence: 99%

“…In comparing with the studies of Cs-137 in soils (Dion, Romanek, Hinton, & Bertsch, 2005;Bostick, Vairavamurthy, Karthikeyan, & Chorover, 2002;Flury, Mathison, & Harsh, 2002;Lujanienė, Vilimaitė-Šilobritienė, & Jokšas, 2005;McKinley et al, 2004;Todorović, Milonjić, & Čomor, 1992;Chowdhury, Kamal, Alam, Aftabuddin, & Zafar, 2004;Komarneni, 1985;Kanai et al, 2013;Rajec, Šucha, Eberl, Środoń, & Elsass, 1999;Sawhney, 1970;Environmental Protection Agency [EPA], 1999;Wahlberg & Fishman, 1962), the adsorption of the Cs-137 radionuclide in beach sand has not yet been well explored (Flury, Czigá ny, Chen, & Harsh, 2004;McKinley et al, 2001;Nyarko et al, 2011). The migration of the Cs-137 radionuclide through soil was observed in the Goiâ nia accident (IAEA, 1988), and also surrounding the Hanford plant (Flury et al, 2004) where high levels of Cs-137 caused by seepage were detected in sediments and in other studies (McKinley et al, 2001;Bostick et al, 2002;Flury et al, 2002;McKinley et al, 2004;Todorović et al, 1992;Chowdhury et al, 2004).…”

Section: Cs-137 In Beach Sandmentioning

confidence: 99%

Cs-137 in Sand and Seawater Samples from Piraquara Beach, Brazil: Discharge site of effluents from the Angra dos Reis Nuclear Power Plants

Menezes¹,

Turci²,

Medeiros³

2014

IJC

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This study presents the Cs-137 radionuclide concentration and activity in sand profile and seawater samples from Piraquara Beach (PB) and from an adjacent small stretch of sand used as a beach. Both sites are located near the discharge point for cooling water and liquid effluents from the Almirante Álvaro Alberto Nuclear Power Station (CNAAA) in Brazil. The chemical composition of the sand samples was determined by granulometric analysis, elemental chemical characterization, and X-ray diffraction (XRD). Mineral sorbents for the Cs-137 radionuclide were found close to the discharge point. The presence of Cs-137 radionuclides in sand and seawater samples was determined by gamma spectrometry analysis, which was also used for seawater samples after absorption by ammonium phosphomolybdate (APM). The Cs-137 radionuclide activity measurements were lower than the minimum detectable activity (MDA): sand < 0.31 Bq•kg-1 , direct analysis of seawater < 0.42 Bq•L-1 , and seawater with APM < 0.004 Bq•L-1. The aim of this study was to measure the amount of the Cs-137 radionuclide in the deeper layers of PB. A determination of radioactive exposure to individuals was not performed because the result values were lower than the MDA values. Our results indicate that the study site shows no contamination by the Cs-137 radionuclide.

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“…In the delta-front area, sediment is deposited during the wet season by a combination of fluvial and tidal processes, but during the dry season, a large part of it is removed and transported towards the south-west by the longshore current generated by the stronger waves of the winter monsoon ( Fig. 2B; Tamura et al, 2010;Xue et al, 2012;Kanai et al, 2013).…”

Section: Fluvial Processesmentioning

confidence: 99%

Sediment distribution and depositional processes along the fluvial to marine transition zone of the Mekong River delta, Vietnam

Gugliotta

Saito

Nguyen³

et al. 2018

Sedimentology

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The area of coastal rivers with a combination of fluvial, tidal and wave processes is defined as the fluvial to marine transition zone and can extend up to several hundreds of kilometres upstream of the river mouth. The aim of this study is to improve the understanding of sediment distribution and depositional processes along the fluvial to marine transition zone using a comprehensive dataset of channel bed sediment samples collected from the Mekong River delta. Six sediment types were identified and were interpreted to reflect the combined action of fluvial and marine processes. Based on sediment‐type associations, the Mekong fluvial to marine transition zone could be subdivided into an upstream tract and a downstream tract; the boundary between these two tracts is identified 80 to 100 km upstream of the river mouth. The upstream tract is characterized by gravelly sand and sand and occasional heterolithic rhythmites, suggesting bed‐load supply and deposition mainly controlled by fluvial processes with subordinate tidal influence. The downstream tract is characterized by heterolithic rhythmites with subordinate sand and mud, suggesting suspended‐load supply and deposition mainly controlled by tidal processes with subordinate fluvial influence. Sediment distributions during wet and dry seasons suggest significant seasonal changes in sediment dynamic and depositional processes along the fluvial to marine transition zone. The upstream tract shows strong fluvial depositional processes with subordinate tidal influence during the wet season and no deposition with weak fluvial and tidal processes during the dry season. The downstream tract shows strong coexisting fluvial and tidal depositional processes during the wet season and strong tidal depositional processes with negligible fluvial influence during the dry season. Turbidity maxima are present along the downstream tract of the fluvial to marine transition zone during both wet and dry seasons and are driven by a combination of fluvial, tidal and wave processes.

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Sediment erosion revealed by study of Cs isotopes derived from the Fukushima Dai-ichi nuclear power plant accident

Cited by 11 publications

References 10 publications

Late Holocene stratigraphic evolution and sedimentary facies of an active to abandoned tide‐dominated distributary channel and its mouth bar

Late Holocene stratigraphic evolution and sedimentary facies of an active to abandoned tide‐dominated distributary channel and its mouth bar

Cs-137 in Sand and Seawater Samples from Piraquara Beach, Brazil: Discharge site of effluents from the Angra dos Reis Nuclear Power Plants

Sediment distribution and depositional processes along the fluvial to marine transition zone of the Mekong River delta, Vietnam

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