The effects of sediment transport on temporal variation in radiocesium concentrations in very shallow water off the southern coast of Fukushima, Japan

Matsumoto, Akira; Myouse, Hiroshi; Arakawa, Hisayuki; Higuchi, Ken; Hirakawa, Naoto; Yoshiaki, Morioka; Mizuno, Takuji

doi:10.1016/j.jenvrad.2017.12.016

Cited by 9 publications

(10 citation statements)

References 47 publications

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“…It is interesting that the concentrations of suspended particles and the 137 Cs activities in the suspended particles at nearshore stations were comparable to the corresponding values measured in the downstream reaches of rivers (Figure 3C,D). The 137 Cs activities in the corresponding nearshore marine sediments (<100 Bq/kg-dry) 34 were approximately one order of magnitude lower than the 137 Cs activities of suspended particles in this study (mean value of 700 Bq/kg-dry, other than station S1). The sediments in the nearshore zone are characterized by coarse and fine sands that are rather different from the suspended particles in the overlying seawater.…”

Section: Resultscontrasting

confidence: 73%

“…The 137 Cs activities in the corresponding nearshore marine sediments (<100 Bq/kg-dry) were approximately one order of magnitude lower than the 137 Cs activities of suspended particles in this study (mean value of 700 Bq/kg-dry, other than station S1). The sediments in the nearshore zone are characterized by coarse and fine sands that are rather different from the suspended particles in the overlying seawater . Those two facts (i.e., the similarity of 137 Cs activities in suspended particles in the nearshore zone and river water and the higher 137 Cs activities in suspended particles than in the sediments) suggest that the suspended particles may have been derived from the small particles transported by rivers that stayed in suspension along the shoreline.…”

Section: Resultscontrasting

confidence: 72%

“…The sediments in the nearshore zone are characterized by coarse and fine sands that are rather different from the suspended particles in the overlying seawater. 34 Those two facts (i.e., the similarity of 137 Cs activities in suspended particles in the nearshore zone and river water and the higher 137 Cs activities in suspended particles than in the sediments) suggest that the suspended particles may have been 137 Cs in dissolved form (e.g., Cs + ) in water column, in all the rivers were in a range of 0.5−36.1 mBq/L (Figure 4A). The geometric means of each river were as follows: 14 mBq/L for the Tomioka River; 3.0 mBq/L for the Kido River; 0.86 mBq/L for the Natsui River; 5.2 mBq/L for the Fujiwara River; 1.0 mBq/L for the Same River; and 6.3 mBq/L for the Binda River (Table S2).…”

Section: Resultsmentioning

confidence: 99%

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Suspended Particle–Water Interactions Increase Dissolved ¹³⁷Cs Activities in the Nearshore Seawater during Typhoon Hagibis

Takata

Aono

Aoyama

et al. 2020

Environ. Sci. Technol.

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Distributions of 137 Cs in dissolved and particulate phases of the downstream reaches of seven rivers and adjacent nearshore and offshore waters as far as ∼60 km south of the Fukushima Dai-ichi nuclear power plant (FDNPP) were studied during the high-river-flow period (June−September 2019) and during the period of October 2019 after typhoon Hagibis. Dissolved 137 Cs activities in nearshore water were higher than those in rivers and offshore waters, and this distribution was more intensified after the typhoon, indicating the desorption of 137 Cs from riverine suspended particles in addition to the ongoing release of contaminated water from the FDNPP and re-entry of radiocesium via submarine groundwater discharge. This scenario is also supported by the reduction of distribution coefficient (K d ) from a geometric mean value of 5.5 × 10 5 L/kg in rivers to 9.8 × 10 4 L/kg in nearshore water. The occupation of desorbed 137 Cs to the dissolved activity of this nuclide in nearshore water was estimated to be 0.7%−20% (median: 9.7%) during the high-river-flow period, increasing to 1.4%−66% (32.3%) after the typhoon, suggesting that the desorption during the flood period such as typhoons further contributes to the increase in dissolved 137 Cs levels in nearshore water.

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Section: Resultscontrasting

confidence: 73%

Section: Resultscontrasting

confidence: 72%

Section: Resultsmentioning

confidence: 99%

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Suspended Particle–Water Interactions Increase Dissolved ¹³⁷Cs Activities in the Nearshore Seawater during Typhoon Hagibis

Takata

Aono

Aoyama

et al. 2020

Environ. Sci. Technol.

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“…In addition, the radiocesium concentration of seabed sediments has been shown to be somewhat high in Ena. 27 These findings indicate that differences in the T eco of P. iwatensis might have been caused by the influence of metabolism and newly recruited plants.…”

Section: Concentrations Of Radioactive Nuclides In Marinementioning

confidence: 91%

Temporal Variation of Radionuclide Contamination of Marine Plants on the Fukushima Coast after the East Japan Nuclear Disaster

Shigeoka

Myose

Akiyama

et al. 2019

Environ. Sci. Technol.

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As a result of the Great East Japan Earthquake and associated tsunami in March 2011, the Fukushima Daiichi Nuclear Power Plant (FDNPP) released a large amount of radioactive material into the environment, resulting in contamination of many marine organisms. In this study, 15 marine algal species and a seagrass species were collected from the sublittoral zone of the Iwaki Coast of Fukushima Prefecture from May 2012 to June 2015 and analyzed for variations in 110mAg, 134Cs, and 137Cs over time. The results indicated that (1) 110mAg, 134Cs, and 137Cs were present in all marine plants collected in May 2012, (2) the concentration of 110mAg in the seagrass Phyllospadix iwatensis decreased significantly over time while the ecological half-life of 110mAg in P. iwatensis was longer at locations closer to the FDNPP, and (3) the 110mAg/137Cs radioactivity ratio of P. iwatensis was remarkably high until 2015, indicating that detectable 110mAg was present in the coastal environment 4 years after the accident. The concentration of 110mAg in P. iwatensis was higher than those in other marine algae, demonstrating a species-specific mechanism of accumulation.

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“…2 is the Noshima sea area where the kelp communities exist. In October 2018, sediment particles on reefs for kelp 39 installed on the sea floor in both sea areas (6 m depth) were collected by the airlift method 40 . The sampling area for one sample was 25 cm 2 in a quadrat.…”

Section: Methodsmentioning

confidence: 99%

Impacts of sub-micrometer sediment particles on early-stage growth and survival of the kelp Ecklonia bicyclis

Matsumoto

Sato

Arakawa

2020

Sci Rep

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Marine forests have declined in many urbanized regions in recent years. One cause is the inflow of fine particles into coastal rocky shores. We examined the influence of sub-micrometre (sub-micro) particles on the early growth stages of the large brown macrophyte Ecklonia bicyclis. The percentage of substrate attachment of zoospores decreased with an increase in sub-micro sediments. As the size of the particles decreased, the negative effect became greater. There was an increase in poor levels of gametophyte survival and growth as more and smaller sediment was deposited. We consider that the causes of these phenomena owing to increasing amounts of sediment is a decrease in availability of substrate for zoospore attachment and that of area for substance exchange on the gametophytes. We also evaluated the effects in sea areas, based on the amount and size distribution of seabed sediment in the algal communities deforested by particles, and found that the inhibition of zoospore attachment and gametophyte growth by sub-micro particles was remarkably large. The sub-micro sediment on the substrate has seriously negative effects on the early stages of macrophytes. Inflow of very fine particles to natural marine forests may result in severe degradation of rocky reef ecosystems.

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The effects of sediment transport on temporal variation in radiocesium concentrations in very shallow water off the southern coast of Fukushima, Japan

Cited by 9 publications

References 47 publications

Suspended Particle–Water Interactions Increase Dissolved ¹³⁷Cs Activities in the Nearshore Seawater during Typhoon Hagibis

Suspended Particle–Water Interactions Increase Dissolved ¹³⁷Cs Activities in the Nearshore Seawater during Typhoon Hagibis

Temporal Variation of Radionuclide Contamination of Marine Plants on the Fukushima Coast after the East Japan Nuclear Disaster

Impacts of sub-micrometer sediment particles on early-stage growth and survival of the kelp Ecklonia bicyclis

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The effects of sediment transport on temporal variation in radiocesium concentrations in very shallow water off the southern coast of Fukushima, Japan

Cited by 9 publications

References 47 publications

Suspended Particle–Water Interactions Increase Dissolved 137Cs Activities in the Nearshore Seawater during Typhoon Hagibis

Suspended Particle–Water Interactions Increase Dissolved 137Cs Activities in the Nearshore Seawater during Typhoon Hagibis

Temporal Variation of Radionuclide Contamination of Marine Plants on the Fukushima Coast after the East Japan Nuclear Disaster

Impacts of sub-micrometer sediment particles on early-stage growth and survival of the kelp Ecklonia bicyclis

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Product

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Suspended Particle–Water Interactions Increase Dissolved ¹³⁷Cs Activities in the Nearshore Seawater during Typhoon Hagibis

Suspended Particle–Water Interactions Increase Dissolved ¹³⁷Cs Activities in the Nearshore Seawater during Typhoon Hagibis