Correction to Transport and redistribution of radiocesium in Fukushima fallout through rivers

Taniguchi, Keisuke*; Onda, Yuichi*; Smith, H. G.*; Blake, W.*; Yoshimura, Kazuya; Yamashiki, Yosuke*; Kuramoto, Takayuki*; Saito, Kimiaki

Environmental Science & Technology, 55(13), P. 9394, 2021/07

https://doi.org/10.1021/acs.est.1c02491

no abstracts in English

Factors controlling dissolved Cs concentrations in east Japanese rivers

Tsuji, Hideki*; Ishii, Yumiko*; Shin, M.*; Taniguchi, Keisuke*; Arai, Hirotsugu*; Kurihara, Momo*; Yasutaka, Tetsuo*; Kuramoto, Takayuki*; Nakanishi, Takahiro; Lee, S*; et al.

Science of the Total Environment, 697, p.134093_1 - 134093_11, 2019/12

https://doi.org/10.1016/j.scitotenv.2019.134093

To investigate the main factors that control the dissolved radiocesium concentration in river water in the area affected by the Fukushima Daiichi Nuclear Power Plant accident, the correlations between the dissolved Cs concentrations at 66 sites normalized to the average Cs inventories for the watersheds with the land use, soil components, topography, and water quality factors were assessed. We found that the topographic wetness index is significantly and positively correlated with the normalized dissolved Cs concentration. Similar positive correlations have been found for European rivers because wetland areas with boggy organic soils that weakly retain Cs are mainly found on plains. However, for small Japanese river watersheds, the building area ratio in the watershed strongly affected the dissolved Cs concentration.

Effect of decontamination on the migrations of soil and radiocesium through river system

Taniguchi, Keisuke*; Kuramoto, Takayuki*; Onda, Yuichi*; Yoshimura, Kazuya; Arai, Hirotsugu*; Onuma, Saori*; Sato, Takayuki*

no journal, , 

no abstracts in English

Study on carbonized temperature estimation of charcoal remained in burnt area in Namie Town, Fukushima

Nomura, Naoki*; Arai, Hirotsugu*; Kuramoto, Takayuki*; Niizato, Tadafumi; Hayashi, Seiji*

no journal, , 

In 2017, a wildfire occurred in mountainous forest of Namie Town, Fukushima Prefecture, where is designated as a difficult-to-return zone due to high radiation dose after TEPCO's Fukushima Daiichi Nuclear Power Plant accident. With the wildfire, changes of dynamics of radionuclide, especially Cs-137 was concerned. In this study, we focused residual charcoal to estimate burning temperature of surface soil and litter because it affects the dissolution behavior of nutrients and radiocesium in soil and litter on the forest floor of the burnt area. As a result of the wildfire, Japanese cedar forest and mixed forest with predominance of Japanese red pine and Japanese oak were burned, so we set up three control sites at each forest and collected the residual charcoals from burnt sites nearby unburnt locations. To clarify the carbonized temperature of residual charcoal, thermal analysis by TG-DTA and infrared adsorption spectrum analysis by micro-FTIR were conducted for litters, artificially burnt litters, and residual charcoals.

Investigation of factors controlling dissolved Cs concentrations in Japanese rivers

Tsuji, Hideki*; Shin, M.*; Taniguchi, Keisuke*; Arai, Hirotsugu*; Kurihara, Momo*; Yasutaka, Tetsuo*; Kuramoto, Takayuki*; Nakanishi, Takahiro; Lee, S*; Shinano, Takuro*; et al.

no journal, , 

To predict the behavior of particulate and dissolved radiocesium (Cs) in river water, some soil and land use categories in the watershed should be considered because these may affect the dissolved Cs concentration. In this study, to investigate the factors that affect dissolved Cs concentrations in Japanese rivers, we measured dissolved Cs concentrations in 67 rivers under baseflow conditions 13-280 km from the Fukushima Daiichi Nuclear Power Plant in August and September 2017.

Effect of decontamination on the migration of radiocesium in the catchments

Taniguchi, Keisuke*; Kuramoto, Takayuki*; Onda, Yuichi*; Yoshimura, Kazuya

no journal, , 

no abstracts in English

Change of Rainfall-runoff event hysteresis in suspended sediments due to surface decontamination in the area affected by the Fukushima Daiichi Nuclear Power Plant accident

Onda, Yuichi*; Yoshimura, Kazuya; Taniguchi, Keisuke*; Kubo, Takaaki*; Smith, H.*; Blake, W.*; Kuramoto, Takayuki*; Sato, Takayuki*

no journal, , 

Radiocaesium dynamics in forested watersheds in Fukushima Prefecture

Taniguchi, Keisuke*; Takeuchi, Yukio*; Fujita, Kazuki*; Dohi, Terumi; Hayashi, Seiji*; Kuramoto, Takayuki*; Nomura, Naoki*; Aono, Tatsuo*

no journal, , 

In Fukushima Prefecture, although decontamination has been completed except for difficult-to-return areas, most of the forest has not been decontaminated yet. From the forest, radiocaesium may enter rivers and affect downstream areas. A survey was conducted in three forested watersheds of the Nanokazawa, Saruta, Nuno rivers located in Fukushima Prefecture to understand the amount and characteristics of radiocaesium flowing out. In each watershed, suspended solids (SS) were collected by a suspended sand sampler, water was collected every few months, and the water level and flow rate were measured. After freeze-drying the SS sample, the concentration of suspended Cs-137 was measured by a germanium semiconductor detector. The water sample was filtered through a membrane filter with a pore size of 0.45 m, then the dissolved Cs-137 was collected by the solid-phase extraction disk method or AMP coprecipitation method, and the dissolved Cs-137 concentration was measured by a germanium semiconductor detector. The ranges of dissolved Cs-137 concentration in FY2019 were 69-190 mBq/L in the Saruta River, 9.7-16 mBq/L in the Nanokazawa river, and ND-3.2 mBq/L in the Nuno River. In the poster, we will also present the results of SS measurements and flow observations.