Cumulative history recorded in the depth distribution of radiocesium in sediments deposited on a sandbar

Tanaka, Kohei; Kondo, Hiroaki; Sakaguchi, Aya; Takahashi, Yoshio

doi:10.1016/j.jenvrad.2015.08.022

Cited by 5 publications

(2 citation statements)

References 43 publications

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“…The higher percentage of 137 Cs in a smaller size fraction of sand, soil and sediment has been reported. 14,[28][29][30] The desorption experiments using seawater were carried out for the sand samples >63 μm grain size separated by wet sieve method. The 137 Cs desorption was 3.1 -7.5% for the bulk sand and 8.5 -9.5% for larger grain size fraction of the sand.…”

Section: Factors Controlling Desorption Behavior Of Radiocesium By Sementioning

confidence: 99%

Desorption Behavior of Fukushima-derived Radiocesium in Sand Collected from Yotsukura Beach in Fukushima Prefecture

et al. 2020

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Beach sand samples were collected along a coastal area 32 km south of the Fukushima Daiichi Nuclear Power Plant (FDNPP) in Fukushima Prefecture, Japan, 5 years after the FDNPP accident. Desorption experiments were performed on the sand samples using seawater in a batch experimental system to understand the forms of existence of radiocesium in sand and their desorption behavior in a coastal environment. The percentage of radiocesium desorption decreased exponentially with an increase in the number of desorption experiments for the four sand samples, with 137 Cs radioactivity from 16 to 1077 Bq kg-1 at surface and deeper layers from three sites. Total desorption percentage ranged from 19 to 58% in 12 desorption experiments. The results indicate that the weak adsorption varies with the sampling sites and their depth layer. To understand the desorption behavior of radiocesium in the sand samples, the desorption experiments were performed for a sand sample by using natural and artificial seawater, and NaCl solution in the presence and absence of KCl. The 137 Cs desorption from the sand collected at a depth of 100-105 cm from the ground surface (137 Cs radioactivity 1052 ± 25 Bq kg-1) was 0.1% by ultrapure water, 3.7% by 1/4 seawater and 7.1% by 1/2 seawater, 2.2% by 470 mM NaCl solution (corresponding to a similar concentration of seawater) and 10-12% by seawater, artificial seawater and 470 mM NaCl + 8 mM KCl solution. These results indicate that about 10% of radiocesium adsorbed on the sand is mainly desorbed by ion exchange of potassium ion in seawater, though the concentration of major cation, or sodium ion, in seawater makes a small contribution on 137 Cs desorption from the sand samples.

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Section: Factors Controlling Desorption Behavior Of Radiocesium By Sementioning

confidence: 99%

Desorption Behavior of Fukushima-derived Radiocesium in Sand Collected from Yotsukura Beach in Fukushima Prefecture

et al. 2020

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“…As a result, the sediment particle size becomes coarser [29]. Research in Fukushima, Japan showed that the changes in the sediment grain size in the upper sediments of a seasonal submerged sandbank occurred because the sediment component transported by the runoff was changed [30]. The changes in river runoff processes have a direct impact on sedimentation processes in tidal flats in downstream estuaries.…”

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The Periodic Response of Tidal Flat Sediments to Runoff Variation of Upstream Main River: A Case Study in the Liaohe Estuary Wetland, China

et al. 2019

Water

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1) Background: To reveal the intrinsic relationship between the tidal flat sediments in an estuary wetland and the runoff from the upstream river. This research was conducted in the tidal flats of the Liaohe estuary wetland.(2) Methods: The 137 Cs and 210 Pb dating technique was used to reconstruct the time correspondence between tidal flat sediments and runoff, and the periodic response was explored between the changes in the tidal flat sediments and runoff based on the spectrum analysis method. (3) Results: The average sedimentation rate in the tidal flat was 2.24 cm·year −1 during the past 50 years. The amount of fine sediment particles deposited on the estuary tidal flat was directly related to the amount of sediments transported by the river and inversely proportional to the ability of rivers to transport fine matter. The high frequency reproduction cycle of 14-15 years in the flood season flow and 5-6 years in the annual sediment discharge of the Liaohe River correspond to the high and low frequency reproduction cycles of the median size of sediments in Liaohe estuarine wetland tidal flats. (4) Conclusions: The research clarified the hydrological constraints of the action law between Liaohe River runoff and the estuarine sediments. The periodic response between Liaohe River runoff and the sediment was established.A variety of measures have been used in sedimentary history research, including horizon markers, anchored tiles, rulers, sediment traps, optical backscatter sensors, short-lived radionuclides, biomarkers, and magnetic minerals [3][4][5]. The basis for the ability to record changes in sediment deposition time in all the methods depends on the availability of time markers in the sediment column [6]. Sediment fingerprinting is a well-established method that has proven its value in revealing the time dimension in sediment research [7,8]. Among the methods mentioned above, the molecular diffusion of 137 Cs in sediment may change the vertical profile of the sediment, but it is impossible to change the position of its accumulation peak [9,10]. Therefore, the application of 137 Cs provides an effective way to quantitatively study sedimentary history. 137 Cs is an artificial nuclide with two major peak fallouts in 1963 and 1986 as time markers in the northern hemisphere [11][12][13]. The 210 Pb dating technique can also be used to document changes in sedimentation rates though time and provide a basis for establishing changes in sedimentation process over the past ca. 100 years [14]. In the actual dating analysis, the 210 Pb ex (half-life 22.3a) specific activity in the sediment has been used to estimate the sedimentary age and deposition rate [15,16]. The 137 Cs and 210 Pb dating techniques have been successfully used in related areas for the historical information of sediments in China [17][18][19][20]. In addition, the use of radioactive isotopes 137 Cs and 210 Pb has provided historical sedimentary information for tidal flat sediments in estuaries, which has solved the problem of consistent time scales...

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Interannual changes in radiocesium concentrations in annually laminated tufa following the Fukushima Daiichi Nuclear Power Plant accident

Katsuta

Miyata

Murakami

et al. 2019

Applied Geochemistry

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Cumulative history recorded in the depth distribution of radiocesium in sediments deposited on a sandbar

Cited by 5 publications

References 43 publications

Desorption Behavior of Fukushima-derived Radiocesium in Sand Collected from Yotsukura Beach in Fukushima Prefecture

Desorption Behavior of Fukushima-derived Radiocesium in Sand Collected from Yotsukura Beach in Fukushima Prefecture

The Periodic Response of Tidal Flat Sediments to Runoff Variation of Upstream Main River: A Case Study in the Liaohe Estuary Wetland, China

Interannual changes in radiocesium concentrations in annually laminated tufa following the Fukushima Daiichi Nuclear Power Plant accident

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