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柳澤 華代; 松枝 誠; 古川 真*; 石庭 寛子*; 和田 敏裕*; 平田 岳史*; 高貝 慶隆*
Analyst, 148(18), p.4291 - 4299, 2023/09
被引用回数：0 パーセンタイル：0(Chemistry, Analytical)固体表面の定量マッピングが可能なオンライン同位体希釈レーザーアブレーション誘導結合プラズマ質量分析法(オンラインLA-ICP-IDMS)を開発した。LAで生成された試料エアロゾルは、独自開発したサイクロン式スプレーチャンバーを介して、同位体濃縮液のミストとオンラインで混合され、ICP-MSへと導入される。その後、同位体比の計算などを通じて各スポットにおける定量イメージング像を作成した。モデル元素としてFeとSrを選択し、オンライン同位体希釈に基づく定量によって認証標準物質を定量したところ、認証値と定量値の結果は良好であった。本法を生体硬組織に適用し、電子プローブマイクロアナライザーのデータと比較した結果、鉄とSrのような微量元素の定量に有効であることを確認した。
辰野 宇大*; 脇 嘉理*; 角間 海七渡*; 二瓶 直登*; 高瀬 つぎ子*; 和田 敏裕*; 吉村 和也; 中西 貴宏; 大手 信人*
Journal of Environmental Management, 329, p.116983_1 - 116983_13, 2023/03
被引用回数：1 パーセンタイル：14.8(Environmental Sciences)This study investigated the effect of radioactive cesium-rich microparticles (CsMPs) on the radiocesium (RCs) concentration and distribution coefficient (Kd) in two rivers, Takase River and Kami-Oguni River, flowing in the watersheds with different radioactive contaminated conditions in Fukushima Prefecture. Unlike RCs adsorbed on to the suspended solids (SS), there was no correlation between the RCs concentration derived from CsMPs and the SS concentration in both rivers. Inflow of CsMPs to the targeted rivers was contingent. CsMPs were detected only in some samples during rainfall. Furthermore, the proportion of RCs concentration derived from CsMPs in the average RCs concentrations per unit mass of SS in both rivers during rainfall were not large, which were 10% or less. As a results, CsMPs did not significantly increase particulate RCs concentration and had little effect on Kd in both river water flowing the watershed with different RCs contaminated condition.
辰野 宇大*; 脇 嘉理*; 角間 海七渡*; 二瓶 直登*; 和田 敏裕*; 吉村 和也; 中西 貴宏; 大手 信人*
Radiation Protection Dosimetry, 198(13-15), p.1052 - 1057, 2022/09
被引用回数：1 パーセンタイル：31.61(Environmental Sciences)Cesium-rich microparticles (CsMPs) with high cesium-137 (
Cs) concentrations were released and deposited in surface soil after the Fukushima Daiichi Nuclear Power Plant accident. Radioactive materials on the soil surface layer enter rivers owing to soil erosion during rainfall. In this study, we investigated CsMPs runoff through the river via soil erosion during rainfall in the Takase River watershed in Namie Town, Fukushima Prefecture, Japan. CsMPs were rarely detected in suspended solids (SS) in water samples collected during four rainfalls between February and July 2021. Furthermore, the proportion of Cs concentration derived from CsMPs to Cs concentration in the form of SS (particulate Cs) in the water was 
6% on average, which suggests that Cs runoff in the form of CsMPs from the forest to the Takase River was not large.
Cs concentrations in coastal sediments off Fukushima鈴木 翔太郎*; 天野 洋典*; 榎本 昌宏*; 松本 陽*; 守岡 良晃*; 佐久間 一幸; 鶴田 忠彦; 帰山 秀樹*; 三浦 輝*; 津旨 大輔*; et al.
Science of the Total Environment, 831, p.154670_1 - 154670_15, 2022/07
被引用回数：2 パーセンタイル：29.93(Environmental Sciences)The monthly monitoring data (total 3647 samples) between May. 2011 and Mar. 2020 were analyzed to describe temporal variability of Cs concentration in coastal sediments off Fukushima. Cs concentration of sediment had decreasing trend, but non-linear model fitting suggested that this decreasing trend showed slower. Additionally, Cs concentration were up to 4.08 times greater in shallow sampling sites (7, 10, 20 m depth) following heavy rainfall events (before five months vs. after five months), such as typhoons. These were consistent with increasing particulate Cs (P-Cs) fluxes from river and increasing dissolved Cs (D-Cs) concentration in seawater. Finally, the numerical experiment was conducted and revealed that riverine Cs input could preserve Cs concentration in coastal sediment. These results indicate that riverine Cs input via heavy rainfall events is one of the main factors for preserving Cs concentration in coastal sediment off Fukushima.
Cs activity concentration in the aquatic insect 
(Tricoptera: Stenopsychidae) in the Ota River, Fukushima, Japan石井 弓美子*; 三浦 輝*; Jo, J.*; 辻 英樹*; 斎藤 梨絵; 小荒井 一真; 萩原 大樹; 漆舘 理之*; 錦織 達啓*; 和田 敏裕*; et al.
PLOS ONE (Internet), 17(5), p.e0268629_1 - e0268629_17, 2022/05
被引用回数：3 パーセンタイル：43.07(Multidisciplinary Sciences)本研究では、福島県太田川で採集した解虫性トビケラ(Stenopsyche marmorata)および肉食性ヘビトンボ(Protohermes grandis)幼虫の水生昆虫個体におけるCs放射能濃度のばらつきを調査した。トビケラ幼虫は散発的に高い放射能を示したが、ヘビトンボ幼虫ではばらつきは見られなかった。オートラジオグラフィーと走査型電子顕微鏡による分析から、これらのトビケラ幼虫試料には、不溶性のCs含有ケイ酸塩ガラス粒子である放射性Cs含有微粒子(CsMPs)が含まれていることが確認された。また、CsMPsはトビケラ幼虫の餌となりうるペリフィトンや漂流粒子状有機物にも含まれており、幼虫はCsMPsを同サイズの餌粒子とともに摂取している可能性が示唆された。淡水生態系におけるCsMPsの分布や生物による取り込みは比較的知られていないが、本研究はCsMPsが水生昆虫に取り込まれることを実証している。
Chaboche, P.-A.*; 脇山 義史*; 高田 兵衛*; 和田 敏裕*; Evrard, O.*; 御園生 敏治; 尻引 武彦; 舟木 泰智
no journal, ,
Following the Fukushima-Daiichi Nuclear Power Plant (FDNPP) accident in March 2011, large quantities of radionuclides in general, and radiocaesium (
Cs) in particular, were emitted in terrestrial and marine environments of Fukushima Prefecture. Although Cs activity in these environments has decreased since the accident, the secondary inputs via the rivers draining and eroding the main terrestrial radioactive plume were shown to sustain high level of Cs in riverine and coastal sediments, which are likely deposited off the coasts of the Prefecture. Accordingly, quantifying the riverine sources of sediment deposited along the coast and characterizing its spatial and depth distribution, as well as its physico-chemical properties, is of the utmost importance to ensure the safety of fishery products and anticipate the environmental fate of radiocaesium. To conduct this project, coastal sediment cores (n=6) from 26 to 60cm depth were collected during cruise campaigns between July and September 2022 at the Ota, Niida and Ukedo river mouths. In this presentation, we report preliminary results regarding the spatial and depth distribution of radiocaesium activities in these sediment cores. Finally, we will discuss the main challenges identified so far to design and implement a sediment tracing method along the coast of the Fukushima Prefecture.
Chaboche, P.-A.*; 脇山 義史*; 高田 兵衛*; 和田 敏裕*; Evrard, O.*; 御園生 敏治; 尻引 武彦; 舟木 泰智
no journal, ,
The Fukushima-Daiichi Nuclear Power Plant (FDNPP) accident trigged by the Great East Japan Earthquake and subsequent tsunami in March 2011 released large quantities of radionuclides in terrestrial and marine environments of Fukushima Prefecture. Although radiocaesium activity in these environments has decreased since the accident, the secondary inputs via the rivers draining and eroding the main terrestrial radioactive plume were shown to sustain high levels of Cs in riverine and coastal sediments, which are likely deposited off the coast of the Prefecture. Accordingly, identifying the sources of sediment is required to elucidate the links between terrestrial and marine radiocaesium dynamics and to anticipate the fate of these persistent radionuclides in the environment.
柳澤 華代; 松枝 誠; 古川 真*; 石庭 寛子*; 和田 敏裕*; 平田 岳史*; 高貝 慶隆*
no journal, ,
レーザーアブレーション誘導結合プラズマ質量分析法(LA-ICP-MS)は、他のイメージング分析に比べて高感度だが、目的元素の定量には、マトリックスに適合した認証標準物質(CRMs)が必要である。しかし、生体試料に適したCRMsはほとんど市販されておらず、従来のLA-ICP-MS法では定量が難しい。本研究では、同位体希釈法を組み合わせたデュアルガスフローシステムを利用した。本システムは、アブレーションサンプルとネブライザーで噴霧したスパイク液の2つのエアロゾルが、独自開発のデュアルポートチャンバーを介して混合される。開発した手法を使用して、CRMs中のFeとSrを定量し、認証値と一致した。さらに、定量マッピングへの応用の可能性を示すために、生体試料(歯と耳石)を分析し、従来の化学分析で得られた値と比較した。
Cs in a river-sea system boundary area高田 兵衛*; 和田 敏裕*; 脇山 義史*; 平尾 茂一*; 佐藤 俊*; 青野 辰雄*; 中西 貴宏; 御園生 敏治; 尻引 武彦
no journal, ,
The Cs sorption behavior on suspended particles was studied in river and coastal seawater, Fukushima Prefecture from June 2019 to October 2021. Although the suspended particle concentration was lower in the river than in seawater, the Cs activity on suspended particles in the river lager than that in seawater. Proportions of ion-exchangeable, organically bound, and refractory fractions of Cs on suspended particles were also determined by conducting sequential extraction method. The ion-exchangeable fraction was less than 1% at both areas. The organically bound fraction was a few %, resulting in that the refractory fraction accounted for 
90%. Thus, it is indicated that the mobility of Cs to marine biota is low in the studied areas.
Chaboche, P.-A.*; 脇山 義史*; 高田 兵衛*; 和田 敏裕*; 御園生 敏治; 尻引 武彦; 舟木 泰智
no journal, ,
2011年3月の東日本大震災とそれに続く津波に端を発した福島第一原子力発電所(FDNPP)事故は、福島県の陸域および海域環境に大量の放射性核種を放出する結果となった。これらの環境中の放射性セシウム(すなわち
CsとCs)の放射能濃度は事故以来低下しているが、主な陸上放射性プルームを流出・浸食している河川からの継続的な流入が測定されており、福島県の沿岸沖に堆積した河川堆積物や沿岸堆積物中のCsの濃度が高いまま維持されている。したがって、陸域と海域の放射性セシウム動態の関連性を解明し、環境中の残留性放射性核種の運命を予測するためには、堆積物の発生源を特定することが必要である。
