Dispersion of Cs-134 and Cs-137 in river waters from Fukushima and Gunma prefectures at nine months after the Fukushima Daiichi NPP accident

Nagao, Seiya; Kanamori, Masaki; Ochiai, Shinya; Suzuki, Kyuma; Yamamoto, Masayoshi

doi:10.15669/pnst.4.9

Cited by 19 publications

(7 citation statements)

References 12 publications

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“…This relationship could be the signature of riverine inputs to the coastal areas because the Ukedo River flows through a highly contaminated watershed. However, several authors have emphasized that rivers discharge small amounts of dissolved radiocaesium (Sakuma et al, 2019;Nagao et al, 2014). As mentioned in the Introduction, during the period of our sampling, typhoons #18 (Phanfone) and #19 (Vongfong) made landfall on Japan on 6 and 13 October, respectively.…”

Section: An Estimation Of Initial Activity Concentration Of Freshwater From Landmentioning

confidence: 89%

“…The result was the transfer of up to 10-12 TBq of radiocaesium from the land to the ocean during the first year after the accident (Evrard et al, 2015). (Nagao et al, 2014) found that about 50% of the radiocaesium in the Niida River was in dissolved form in the first few months after the accident, whereas after September 2011 more than 70% of the radiocaesium was associated with particles, and that percentage was even higher after storms.…”

Section: Introductionmentioning

confidence: 99%

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Impact of typhoons on particulate and dissolved <sup>137</sup>Cs activities in seawater off the Fukushima Prefecture: results from the SOSO 5 Rivers cruise (October 2014)

Aoyama

Charmasson

Hamajima

et al. 2021

Preprint

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Abstract. Cruise SoSo 5 Rivers took place during October 2014 off the coast of Fukushima Prefecture shortly after the passage of two typhoons. Detection of dissolved 134Cs and 137Cs in all samples reflected contamination caused by accidental releases of radiocaesium from the Fukushima Dai-ichi Nuclear power plant (FNPP1) accident. The dissolved activities were generally higher at coastal sites and decreased with distance from shore, and they were higher in the surface than in the bottom water. The tendency of 137Cs activities to decrease with distance from the coast reflected mixing of coastal water and open-ocean water of which 137Cs activity concentration was ~1.5 Bq m−3. At stations very close to the coast, we observed high particulate 137Cs activity concentration that exceeded dissolved 137Cs activity concentration. 137Cs activities were generally 1–2 orders of magnitudes lower in organic particles than in dissolved form, and the ratios of 137Cs activity concentration in organic particles to 137Cs activity concentration in dissolved form ranged from 0.01 ± 0.00 to 0.12 ± 0.01. The ratio of 137Cs to 134Cs activity concentrations in organic particles did not change with distance from shore or with 137Cs activity concentration and generally remained around 1, even in samples collected far from the coast. This pattern indicated that the organic particles had come from rivers or a source very close to the coast. The 137Cs / 134Cs activity ratio in dissolved form north of FNPP1 region was estimated to be 1.074 ± 0.015, a ratio that is in good agreement with the 137Cs / 134Cs activity ratio in the core of Unit 1 of the FNPP1 while the 137Cs / 134Cs activity ratio at Tomioka port which located south of FNPP1 was 0.998 ± 0.017. Therefore we can conclude the source of radiocaesium in seawater in the coastal region north of FNPP1 was deposited radiocaesium released from the core of Unit 1 of FNPP1, while the source of radiocaesium observed in the coastal region south of FNPP1 was a mixture of deposited radiocaesium released from the core of Unit 2 and the core of Unit 1 of FNPP1. During September–October of each year, the typhoon season in Japan, the 137Cs activity concentration generally increased at Ukedo port, Tomioka port, FNPP1, and Iwasawa beach, and showed a good relationship with the 7-day modified antecedent precipitation index (API) while there is less correlation between the modified API and 137Cs activity concentration near the outlet of canal from unit 5 and 6 of FNPP1 to the sea.

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Section: An Estimation Of Initial Activity Concentration Of Freshwater From Landmentioning

confidence: 89%

Section: Introductionmentioning

confidence: 99%

Impact of typhoons on particulate and dissolved <sup>137</sup>Cs activities in seawater off the Fukushima Prefecture: results from the SOSO 5 Rivers cruise (October 2014)

Aoyama

Charmasson

Hamajima

et al. 2021

Preprint

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“…It has been necessary to measure dissolved radiocesium ( 134 Cs and 137 Cs) concentrations in freshwater near the Fukushima Daiichi Nuclear Power Plant (FDNPP) since the FDNPP accident to provide information to allow root uptake by crops and accumulation in aquatic organisms to be assessed. Many institutions have therefore monitored dissolved radiocesium concentrations in freshwater in northeastern Japan since the FDNPP accident [1][2][3][4][5][6][7][8][9][10][11][12].…”

Section: Introductionmentioning

confidence: 99%

Repeatability and reproducibility of measurements of low dissolved radiocesium concentrations in freshwater using different pre-concentration methods

Kurihara

Yasutaka

Aono

et al. 2019

J Radioanal Nucl Chem

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We assessed the repeatability and reproducibility of methods for determining low dissolved radiocesium concentrations in freshwater in Fukushima. Twenty-one laboratories pre-concentrated three of 10 L samples by five different pre-concentration methods (Prussian-blue-impregnated filter cartridges, coprecipitation with ammonium phosphomolybdate, evaporation, solid-phase extraction disks, and ion-exchange resin columns), and activity of radiocesium was measured. The z-scores for all of the 137 Cs results were within ± 2, indicating that the methods were a good degree of precision. The relative standard deviations (RSDs) indicating the reproducibility among different laboratories were larger than the RSDs indicating the repeatability in each separate laboratory.

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“…Radionuclide transport processes have been studied in the Abukuma River system [5][6][7] and small rivers in eastern Fukushima Prefecture [8,9]. Ueda et al [10] reported that the radiocesium concentrations depend on the water discharge rates.…”

Section: Introductionmentioning

confidence: 99%

Migration behavior of 134Cs and 137Cs in the Niida River water in Fukushima Prefecture, Japan during 2011–2012

Nagao

Kanamori

Ochiai

et al. 2014

J Radioanal Nucl Chem

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Total radioactivity of 137 Cs in water samples from the Niida River was 0.025-4.18 Bq/L during May 2011-November 2012. Higher radioactivity was found during May-September 2011 and after a high flow condition caused by a rain event in 2012. The particulate phase of 134 Cs and 137 Cs was 47-48 % for May-September 2011, 75-93 % in normal flow conditions and 86-91 % in high flow conditions after December 2011. These results indicate that the supply of 134 Cs and 137 Cs from the watershed differs from the early stage up to September 2011 and from the last stage.

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Dispersion of Cs-134 and Cs-137 in river waters from Fukushima and Gunma prefectures at nine months after the Fukushima Daiichi NPP accident

Abstract: Cs from the watershed to the river waters occurred mainly as particulate forms and that their radioactivity depends on the levels of radioactivity at the watersheds of the respective river systems.

Cited by 19 publications

References 12 publications

Impact of typhoons on particulate and dissolved <sup>137</sup>Cs activities in seawater off the Fukushima Prefecture: results from the SOSO 5 Rivers cruise (October 2014)

Impact of typhoons on particulate and dissolved <sup>137</sup>Cs activities in seawater off the Fukushima Prefecture: results from the SOSO 5 Rivers cruise (October 2014)

Repeatability and reproducibility of measurements of low dissolved radiocesium concentrations in freshwater using different pre-concentration methods

Migration behavior of 134Cs and 137Cs in the Niida River water in Fukushima Prefecture, Japan during 2011–2012

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Dispersion of Cs-134 and Cs-137 in river waters from Fukushima and Gunma prefectures at nine months after the Fukushima Daiichi NPP accident

Abstract: Cs from the watershed to the river waters occurred mainly as particulate forms and that their radioactivity depends on the levels of radioactivity at the watersheds of the respective river systems.

Cited by 19 publications

References 12 publications

Impact of typhoons on particulate and dissolved &lt;sup&gt;137&lt;/sup&gt;Cs activities in seawater off the Fukushima Prefecture: results from the SOSO 5 Rivers cruise (October 2014)

Impact of typhoons on particulate and dissolved &lt;sup&gt;137&lt;/sup&gt;Cs activities in seawater off the Fukushima Prefecture: results from the SOSO 5 Rivers cruise (October 2014)

Repeatability and reproducibility of measurements of low dissolved radiocesium concentrations in freshwater using different pre-concentration methods

Migration behavior of 134Cs and 137Cs in the Niida River water in Fukushima Prefecture, Japan during 2011–2012

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Impact of typhoons on particulate and dissolved <sup>137</sup>Cs activities in seawater off the Fukushima Prefecture: results from the SOSO 5 Rivers cruise (October 2014)

Impact of typhoons on particulate and dissolved <sup>137</sup>Cs activities in seawater off the Fukushima Prefecture: results from the SOSO 5 Rivers cruise (October 2014)