From Wed, February 28 to Thu, February 29, 2024

はじめに
今回の成果報告会のテーマは「福島の森と海はどうなっているか」です。原発事故から10年以上を経て長期的なフェーズの研究対象として、福島大学環境放射能研究所では福島の森と海について重点的に取り組んできました。大部分の森林は除染が行われず、原発事故で放出された放射性物質がこの先も継続して存在し続ける可能性があります。帰還困難区域の避難指示解除が進んでいますが、森林と隣接する地域の避難指示解除も進むでしょう。里の豊かさを支えてきた森林からの恩恵の享受を回復できるかが大きな課題だと考えています。そのためには森林内での放射能の分布が時間経過とともにどのように変化してきたのかについて、従来からの研究を継続するとともに、将来的な変化についての仮説を視野に入れながら、研究を通じて見極めることが重要です。
もう一方の海については、2023年夏から開始された処理水放出により、関心が集まりました。ヒトや生態系への安全性には問題のない放出を行う計画ですが、中国への水産物輸出が滞るという問題が発生しています。東日本大震災からの復興の歩みを妨げることのないよう、科学的研究の観点からも新たな知見や情報の開示を進めていかねばなりません。処理水には除去ができないトリチウムが含まれていることから、トリチウムについての安全性や生態系内での挙動等についても関心が高まっています。トリチウムは宇宙線により生成され、天然にも存在しています。福島での人工的な放出の影響を評価するためには天然トリチウムの環境動態も継続的に観測し、バックグラウンドを把握する必要があります。
さて、森林と海とが河川を通じて栄養塩や有機物を輸送することなど、生物地球化学的な観点でさ
まざまなことが語られています。森林生態系では土壌生成や窒素固定によって生物が利用可能な栄養が生成されています。これらの一部が河川を通じて森林の外に運ばれ、下流地域や海洋にも恩恵をもたらします。約５億年前、原始の海から陸地に進出したカビと植物の連携が現在の豊かな大地のもととなっており、そしてそれらパイオニアの活動が今もなお続いているようです。放射性セシウムの動きを理解することは重要ですが、反対に放射能の動きから推定されるそもそもの自然のプロセスを理解することが今後一層重要性を増すと考えられます。例えば、トリチウム濃度は地下水の年代推定にも用いられ、地下水資源量の推定にも役立つ水文学的解析のツールとしても活用されています。これは、放射能が自然のプロセス理解に用いられる一つの例です。
成果報告会第10回の節目にこれまでの研究を振り返りながら、自然の理解や損傷した原子炉の廃炉など長期的課題を視野に今後の方向性についてご意見を賜りたいと思います。
福島大学環境放射能研究所
所長

1

難波

謙二

The 10th Annual Symposium of the IER, Fukushima University / 福島大学環境放射能研究所 第 10 回成果報告会

FOREWORD
The theme of this 10th Annual Symposium is "Forest and Marine Environments in Fukushimanow." After more than 10 years since the incident, the Institute of Environmental Radioactivity,
Fukushima University（IER）has been focusing on the forests and oceans of Fukushima as subjectsof long-term phase research. Most of the forests have not undergone decontamination, and there isa possibility that radioactive materials released by the nuclear accident may continue to persist in
the future. Evacuation orders are being lifted in the difficult-to-return zones, and it is likely that
evacuation orders in areas adjacent to forests will also be lifted. We believe that recovering thebenefits from the forests that have supported the richness of the villages is a significant challenge.
Therefore, it is important to continue our existing research on how the distribution of radioactivity
in the forests has changed over time, and to determine this through research while considering
hypotheses about future changes.
Regarding the marine environment, there has been a growing concern due to the release of treatedwater initiated in the summer of 2023. The plan is to release treated water with no safety issues
for human health and ecosystems; however, an issue has arisen concerning disruptions in theexport of marine products to China. To ensure the progress of reconstruction after the Great East
Japan Earthquake is not hindered, it is necessary to continue to advance new findings and disclose
information from a scientific research perspective. The treated water contains tritium, whichcannot be removed, leading to increased interest in the safety of tritium and its behavior in theecosystem. Tritium is naturally produced by cosmic rays and exists in the environment. To detect
the impact of artificial tritium releases in Fukushima, it is necessary to regularly monitor theenvironmental dynamics of natural tritium and understand the background.
Now, various aspects are discussed from a biogeochemical perspective, such as the transportationof nutrients and organic matter between forests and the ocean through rivers. In forest ecosystems,
nutrients available to organisms are generated through processes like soil formation and nitrogen
fixation. Some of these nutrients are transported beyond the forests through rivers, benefiting
downstream areas and the ocean. Approximately 500 million years ago, the collaboration between
fungi and plants that advanced from the primordial sea to the land laid the foundation for thecurrent fertile land, and the activities of these pioneers seem to persist to this day. While it isimportant to understand the movement of radiocesium, it is also considered increasingly important
to comprehend the fundamental natural processes inferred from the movement of radioactivity. For
instance, tritium concentration is utilized in estimating the age of groundwater and serves as ahydrological analysis tool contributing to the estimation of groundwater resources. This is one
example that illustrates how radioactivity is employed as a tool to understand natural processes.
At the 10th anniversary of the annual symposium, we would like to look back on our research todate and ask for your opinions on future directions with a view to long-term issues such as
understanding nature and decommissioning damaged nuclear reactors.

NANBA Kenji
Director, Institute of Environmental Radioactivity, Fukushima University

2

The 10th Annual Symposium of the IER, Fukushima University / 福島大学環境放射能研究所 第 10 回成果報告会

Working Group for
The 10th Annual Symposium of the IER, Fukushima University
Aleksei KONOPLEV			
Ismail Md. Mofizur RAHMAN		WADA Toshihiro			
TAKATA Hyoe			
Maksym GUSYEV			ISHINIWA Hiroko			
IGARASHI Yasunori			
KIMURA Airu				NAGATA Hiroko			
MIZUNO Shinobu			ITO Osamu				
CHIBA Mariko				（Project Professor）（Associate Professor）（Associate Professor）（Associate Professor）（Project Associate Professor）（Project Lecturer）（Project Lecturer）（Staff of the Support Unit）（Research Associate/Coordinator for International Affairs）（Coordinator for International Affairs）（Research Coordinator）（Research Coordinator）

Institute of Environmental Radioactivity, Fukushima University
1 Kanayagawa, Fukushima City, Fukushima 960-1296, JAPAN
Phone +81-24-504-2114 Fax +81-24-503-2921
E-mail ier@adb.fukushima-u.ac.jp
https://www.ier.fukushima-u.ac.jp/en/

第10回成果報告会

ワーキンググループ

アレクセイ コノプリョフ				イスマイル モハマド モフィズル ラハマン
和田 敏裕						高田 兵衛						マキシム グシエフ					石庭 寛子						五十嵐康記						木村 会瑠						永田 広子						水野忍						伊藤修						千葉真理子						福島大学環境放射能研究所〒960-1296 福島県福島市金谷川１番地
電話 024-504-2114 Fax 024-503-2921
E-mail ier@adb.fukushima-u.ac.jp
https://www.ier.fukushima-u.ac.jp

3

特任教授
准教授
准教授
准教授
特任准教授
特任講師
特任講師
主事
研究員/国際コーディネーター
国際コーディネーター
研究コーディネーター
研究コーディネーター

The 10th Annual Symposium of the IER, Fukushima University / 福島大学環境放射能研究所 第 10 回成果報告会

Venue Guide Map / 会場案内
Venue Guide Map / 会場案内
CORASSE Fukushima

コラッセふくしま

CORASSE Fukushima			

コラッセふくしま

1-20 Mikawaminamimachi, Fukushima City,
1-20 Mikawaminamimachi, Fukushima City,
Fukushima
Prefecture,Japan
Fukushima
Prefecture,Japan

福島県福島市三河南町 1 番 20 号
福島県福島市三河南町１番20号

Floor Guide / フロアガイドFloor Guide / フロアガイド
Poster Presentation
ポスター発表会場

Oral Presentation
for Experts &Symposium for the
General Public
専門家向け口頭発表・
市民向けシンポジウム
会場

4th Floor / 4 階

4The 10th Annual Symposium of the IER, Fukushima University / 福島大学環境放射能研究所 第 10 回成果報告会

２月29日 February 29, 2024
市民向けシンポジウム / Symposium for the General Public
13：00

開会挨拶 / Opening Remarks
福島大学 学長 三浦浩喜 / MIURA Hiroki, President, Fukushima University

13：05

趣旨説明 / Overview
福島大学環境放射能研究所 所長 難波謙二
NANBA Kenji, Director, Institute of Environmental Radioactivity, Fukushima University

13：10

S-01

ALPS処理水放出前後の海のトリチウム
高田兵衛、佐藤俊、三浦輝、西野圭佑、大槻哲、和田敏裕
Tritium in the marine environment before and after the ALPS treated water
discharge
TAKATA Hyoe, SATOH Shun, MIURA Hikaru, NISHINO Keisuke, OHTSUKI Satoru,
WADA Toshihiro ������������������������������ 11

13：35

S-02

森林生態系における放射性核種循環の理解に向けてヴァシル・ヨシェンコ、難波謙二
Toward understanding radionuclide cycling in forest ecosystems
Vasyl YOSCHENKO, NANBA Kenji ���������������������� 12
休憩 / Break

14：00
14：10

S-03

自然ベースの福島の農業と林業の「再生」
金子信博
Nature-based regeneration of agriculture and forestry in Fukushima
KANEKO Nobuhiro ����������������������������� 13

14：35

S-04

魚類の移動生態の解明と福島県の漁業復興
和田敏裕
Elucidation of fish migration ecology and fisheries restoration in Fukushima
Prefecture
WADA Toshihiro ������������������������������ 14
休憩 / Break

15：00
15：10

S-05

小動物に蓄積したわずかな量の放射性ストロンチウムを追いかける
高貝慶隆
Small amounts of radioactive strontium accumulated in small animals
TAKAGAI Yoshitaka����������������������������� 15

15：35

S-06

人為起源および天然トリチウム放射性核種による陸水滞留時間の数値モデリング
マキシム・グシエフ、アレクサンドル・コクヮン、五十嵐康記、高田兵衛、平尾茂一、
赤田尚史、柴崎直明
Anthropogenic and natural tritium radionuclide for numerical modeling ofterrestrial water transit times
Maksym GUSYEV, Alexandre CAUQUOIN, IGARASHI Yasunori, TAKATA Hyoe,HIRAO Shigekazu, AKATA Naofumi, SHIBASAKI Naoaki������������ 16

16：00

総合討論 / Discussion

16：25

閉会挨拶 / Closing Remarks
福島大学環境放射能研究所 副所長/長崎大学 教授 高村昇
TAKAMURA Noboru, Vice Director, Institute of Environmental Radioactivity,
Fukushima University / Professor, Nagasaki University

5The 10th Annual Symposium of the IER, Fukushima University / 福島大学環境放射能研究所 第 10 回成果報告会

２月28日 Feburary 28, 2024
Oral Presentation for Experts / 専門家向け口頭発表
Opening Remarks
NANBA Kenji, Director, Institute of Environmental Radioactivity, Fukushima University

14：30
14：35

O-01

Tritium in the marine environment before and after the ALPS treated water
discharge
TAKATA Hyoe, SATOH Shun, MIURA Hikaru, NISHINO Keisuke, OHTSUKI Satoru,
WADA Toshihiro
ALPS処理水放出前後の海のトリチウム
高田兵衛、佐藤俊、三浦輝、西野圭佑、大槻哲、和田敏裕������������ 19

15：00

O-02

Evaluating terrestrial water cycle using numerical modeling with tritiumradioisotope in Fukushima, Japan
Maksym GUSYEV, Alexandre CAUQUOIN, IGARASHI Yasunori, TAKATA Hyoe,HIRAO Shigekazu, AKATA Naofumi���������������������� 20
Break

15：25
15：35

O-03

Investigation of atmospheric tritiated water vapor in Fukushima
HIRAO Shigekazu, KAKIUCHI Hideki
福島での大気水蒸気中トリチウム調査
平尾茂一、柿内秀樹����������������������������� 21

16：00

O-04

Evaluation of molecular tritium deposition onto farmland soil
KAKIUCHI Hideki, NAGAI Masaru
分子状トリチウムの耕作地土壌への沈着の評価
柿内秀樹、永井勝������������������������������ 22
Break

16：25
16：35

O-05

Radiological impact assessment for the ocean discharge of ALPS treated water
TSUMUNE Daisuke, TSUBONO Takaki, MISUMI Kazuhiro
ALPS処理水の海洋放出に対する放射線影響評価
津旨大輔、坪野考樹、三角和弘������������������������ 23

17：00

O-06

Independent evaluation by an advisory board of ten years of research by Instituteof Environmental Radioactivity on the consequences of the Fukushima Daiichi
accident
Brenda HOWARD, Wolfgang RASKOB, Sergey FESENKO, YOSHIDA Satoshi��� 24

17：25

Discussion

17：55

Closing Remarks
Aleksei KONOPLEV, Vice Director, Institute of Environmental Radioactivity,
Fukushima University

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The 10th Annual Symposium of the IER, Fukushima University / 福島大学環境放射能研究所 第 10 回成果報告会

Poster Presentation for Experts / 専門家向けポスター発表
Ocean / 海洋
P-01

P-02

Spatial and vertical distribution of radiocesium in marine sediment cores of Fukushima
Prefecture
Pierre-Alexis CHABOCHE, WAKIYAMA Yoshifumi, TAKATA Hyoe, WADA Toshihiro,
MISONOU Toshiharu, SHIRIBIKI Takehiko, FUNAKI Hironori ��������������� 27
Estimation of Cs-137 fluxes into the ocean: comparison of direct release and river discharge
SATOH Shun, TAKATA Hyoe, WAKIYAMA Yoshifumi, OHTSUKI Satoru
事故後のメタデータを用いた福島沿岸海域への放射性セシウムの流入量の推定
佐藤俊、高田兵衛、脇山義史、大槻哲 �������������������������� 28

Rivers and Lakes/河川･湖沼
P-03

P-04

P-05
P-06

P-07

P-08

P-09

P-10

Field experimental study of basic mechanisms of dissolved 137Cs concentration seasonality inponds nearby the Fukushima Daiichi Nuclear Power Plant
Alexei KONOPLEV, KUROSAWA Honoka, WAKIYAMA Yoshifumi, IGARASHI Yasunori,
NANBA Kenji ������������������������������������ 29
Using 137Cs re-sampling and depth-incremental technique to investigate the fate of Chernobylderived particulate 137Cs transferred with sediment fluxes
Maksim M. IVANOV, Valentin GOLOSOV, Nadezhda IVANOVA, Anna USACHEVA,
Nikolai LUGOVOI, Nikita DIMCHUK, Nikita KVASOV, Polina FOMINIKH, Yulia POLETAYEVA
������������������������������������������ 30
Tritium and aquatic living organisms: influence, transformation, and accumulation
Lidiia BONDAREVA ��������������������������������� 31
Variations in 137Cs concentrations in river and coastal seawater during high-flow events
WAKIYAMA Yoshifumi, SATOH Shun, TAKATA Hyoe, Pierre-Alexis CHABOCHE,KUROSAWA Honoka
出水時における河川と沿岸海水の137Cs濃度変動
脇山義史、佐藤俊、高田兵衛、ピエール−アレクシス・シャボシュ、黒澤萌香 ���������� 32
Long-term 137Cs dynamics after the decontamination at an urban pond
KUROSAWA Honoka, NANBA Kenji, WADA Toshihiro, WAKIYAMA Yoshifumi
都市域ため池における除染後の長期的な137Cs動態
黒澤萌香、難波謙二、和田敏裕、脇山義史������������������������� 33
Distribution of 137Cs concentrations in the urban hydrosphereSUZUKI Nobuhiro, WAKIYAMA Yoshifumi, TAKATA Hyoe, TAKASE Tsugiko,
KUROSAWA Honoka
都市域の水圏における137Cs濃度分布
鈴木信弘、脇山義史、高田兵衛、高瀬つぎ子、黒澤萌香������������������� 34
Spatial pattern of water chemistry including radiocesium concentration in Arakawa River,
Fukushima Prefecture
IGARASHI Yasunori, FUKUSHIMA Keitaro, SAITO Asuka
福島市内を流れる荒川の水質形成機構と137Cs流出の実態
五十嵐康記、福島慶太郎、斎藤あすか �������������������������� 35
Relationship between 137Cs concentration in water and Japanese dace（Pseudaspius hakonensis）inlakes in Fukushima Prefecture
INOMATA Ayame, TAKASAKI Kazuyoshi, TOMIYA Atsushi, ENOMOTO Masahiro,
FUNAKI Yuto, SHIMAMURA Shinya, WADA Toshihiro
福島県内湖沼における湖水とウグイの137Cs濃度の関係
猪俣絢女、鷹﨑和義、冨谷敦、榎本昌宏、舟木優斗、島村信也、和田敏裕 ����������� 36

Ecosystem and Effects/生態系･影響
P-11

P-12

Voluntary inspection results of radioactive Cs concentration of marine products in Fukushima
and examples of voluntary shipping restrictions
TAKASAKI Kazuyoshi
福島県産水産物の放射性Cs濃度の自主検査結果及び出荷自粛事例
鷹﨑和義��������������������������������������� 37
Impacts of wildfire on desorption of radionuclide and subsequent wash-offs in the Chornobyl
Exclusion Zone
IGARASHI Yasunori, Valentyn PROTSAK, Gennady LAPTEV, Igor MALOSHTAN,
Dmitry SAMOILOV, Serhii KIRIEIEV, ONDA Yuichi, Alexei KONOPLEV
チョルノービリにおける山火事は放射性核種の溶出とその後の流出にどのような影響を与えるのか？
五十嵐康記、バレンティン・プロサック、ゲナディー・ラプテフ、イーゴリ・マロシュタン、
ドミトリー・サモイロフ、セルヒー・キリエフ、恩田裕一、アレクセイ・コノプリョフ �������� 38

7

The 10th Annual Symposium of the IER, Fukushima University / 福島大学環境放射能研究所 第 10 回成果報告会

P-13

Consecutive sexual maturation observed in a rock shell population in the vicinity of the
Fukushima Daiichi Nuclear Power Plant, Japan
HORIGUCHI Toshihiro, ARAMAKI Takafumi, NAKAJIMA Daisuke, KODAMA Keita,
KINTSU Hiroyuki, MORISHITA Fumihiro
福島第一原子力発電所近傍の肉食性巻貝イボニシにみられる生殖異常：通年成熟現象
堀口敏宏、荒巻能史、中島大介、児玉圭太、近都浩之、森下文浩 ��������������� 39
P-14 Testing new methods to reduce 137Cs and 90Sr contamination of freshwater fish
Polina PAVLENKO, WADA Toshihiro, Vasyl YOSCHENKO, Valery KASHPAROV ������ 40
P-15 Combined remote sensing and modelling of the state of Chornobyl forests in terms of
productivity, radioactive contamination, and economic use
Dmytrii HOLIAKA, Valeriia MOROZOVA, Roman ZADOROZHNIUK, Vasyl YOSCHENKO,
Sviatoslav LEVCHUK, Jim T. SMITH, Nicholas A. BERESFORD, Oleksii KIVA,
Hans Christoffer TYLDUM, Deborah H. OUGHTON, Maryna HOLIAKA, IGARASHI Yasunori,
Oleksandr-Ralf CHERNIAIEV, Oleksandr LESNIK, Ihor CHYZHEVSKYI, KATO Hiroaki,
Petro DIACHUK, NANBA Kenji, ONDA Yuichi, Valery KASHPAROV������������ 41
P-16 Assessment of the effects of ionizing radiation in bees – BEERAD
Béatrice GAGNAIRE, NANBA Kenji, Jean-Marc BONZOM, Jean-Luc BRUNET, Margot CREVET,
Nicolas DUBOURG, ISHINIWA Hiroko, NAGATA Hiroko, Michel PELISSIER, Luc BELZUNCES������������������������������������������ 42
P-17 Soil biodiversity and functional processes in radio-contaminated forests（Fukushima
Prefecture, Japan）
Quentin LAMBERT, Olivier ARMANT, Anne-Sophie BENOISTON, Yvan CAPOWIEZ,
Stephan HÄTTENSCHWILER, Amaia IRIBAR-PELOZUELO, KANEKO Nobuhiro,
Sylvain LAMOTHE, NANBA Kenji, Vasyl YOSCHENKO, WADA Toshihiro, Jean-Marc BONZOM,Franck GILBERT����������������������������������� 43
P-18 Long-term transfer of radiocesium by hydrological processes within forest following
Fukushima Dai-ichi Nuclear Power Plant accident
KATO Hiroaki, NIWANO Yuma, ONDA Yuichi
福島第一原子力発電所事故後の森林内における水文学的過程による放射性セシウムの長期移行
加藤弘亮、庭野佑真、恩田裕一 ����������������������������� 44
P-19 Effects of downward migration of Cs-137 on its concentration in fine roots of Japanesecedar in Fukushima
TAKAHASHI Junko, SASAKI Takuya, IGUCHI Satoshi, ONDA Yuichi
スギ林細根中のCs-137濃度に対するCs-137下方移行の影響
高橋純子、佐々木拓哉、井口啓、恩田裕一������������������������� 45
P-20 Evaluation of radiocesium uptake from food and water by starry flounder, an euryhaline
fish, under different salinity conditions
MANOME Yuuki, WADA Toshihiro
広塩性魚ヌマガレイを用いた異なる塩分条件下における餌および水からの放射性セシウム取込評価
馬目由季、和田敏裕 ���������������������������������� 46
P-21 Distribution of radioactive cesium-rich microparticles in forest soils at difficult-to-return zone
WAKI Hiromichi, TATSUNO Takahiro, NIHEI Naoto, KAKUMA Minato, NAGASAWA Waka,
SAYAMA Yo, WADA Toshihiro, MURAKAMI Masashi, OHTE Nobuhito
帰還困難区域内の森林土壌における高濃度放射性セシウム含有粒子の分布
脇嘉理、辰野宇大、二瓶直登、角間海七渡、長澤和佳、佐山葉、和田敏裕、村上正志、大手信人�� 47
P-22 Radiocesium concentrations in fish from a dam reservoir and forest rivers in Ukedo Riversystem
KODAMA Fuya, KANASASHI Tsutomu, WADA Toshihiro
請戸川水系のダムと渓流河川に生息する魚類の放射性セシウム濃度
児玉楓弥、金指努、和田敏裕 ������������������������������ 48
P-23 Relationships in radiocesium concentration among dead leaves, aquatic insects（Lepidostomatidae）, and their excretion
KANASASHI Tsutomu, WADA Toshihiro
カクツツトビケラ科幼虫の摂食・排泄による枯死葉の放射性セシウム濃度変化とその要因
金指努、和田敏裕����������������������������������� 49
P-24 BEECONECT: A connected flower to measure the effects of radioactive contamination on the
cognitive health of pollinators
Kristine ABENIS, Loïc GOULEFERT, Christian LUBAT, NANBA Kenji, MIZUSAWA Leiko,
Béatrice GAGNAIRE, Margot CREVET, Olivier ARMANT, Jean-Marc BONZOM,
Mathieu LIHOREAU ��������������������������������� 50
P-25 Study of the effects of environmental radiocontamination on the metabolism of an amphibian,the tree frog
Léa DASQUE, Damien ROUSSEL, Jean-Marc BONZOM, Olivier ARMANT, Clément CAR,
André GILLES, NANBA Kenji, ISHINIWA Hiroko, WADA Toshihiro, Sandrine FRELON,
Nathalie MONDY����������������������������������� 51

8

The 10th Annual Symposium of the IER, Fukushima University / 福島大学環境放射能研究所 第 10 回成果報告会

P-26

P-27

P-28

Repeated DNA sequences of the centromere region in three species of the genus Myodes:
Establishment of FISH probes for dicentric chromosomal analysis
ISHINIWA Hiroko, Olena BURDO, NAKATA Akifumi, Donovan ANDERSON, MIURA Tomisato
Myodes属３種におけるセントロメア領域の反復DNA配列：二動原体染色体解析に向けたFISHプ
ローブの作成石庭寛子、オレナ・ブルドー、中田章史、ドノヴァン・アンダーソン、三浦富智���������� 52
Distribution and seasonality of 137Cs activity in terrestrial and aquatic ecosystems in the
difficult-to-return zone
YAMAGUCHI Daisuke, KANASASHI Tsutomu, ISHINIWA Hiroko, WADA Toshihiro
帰還困難区域の陸域・水域生態系における137Cs濃度分布と季節性
山口大輔、金指努、石庭寛子、和田敏裕 ������������������������� 53
Polychaete（Perinereis aibuhitensis）rearing experiment in seawater containing radiocesium
URYU Junya, ITO Takayuki, YAMANOBE Takahiro
放射性Csを含む海水でのアオゴカイ飼育試験
瓜生純也、伊藤貴之、山野辺貴寛 ���������������������������� 54

Measurement and Analysis / 計測･分析
P-29

P-30

Development of a highly sensitive analytical method for ultra-trace 99Tc in environmental water
TAKAMI Kei, NABEYAMA Yuki, HATSUKAWA Yuichi, TSUKADA Kazuaki, ASAI Masato,
SUEKI Keisuke, YAMASAKI Shinya, TAKAKU Yuichi, SAKAGUCHI Aya
環境水中の極微量99Tc高感度分析法の開発
高見佳、鍋山雄樹、初川雄一、塚田和明、浅井雅人、末木啓介、山崎信哉、高久雄一、坂口綾��� 55
Kinetic study of electrochemically formed silver iodide for the rapid and selective recoveryof iodide ion in environmental water
YAMASAKI Shinya, TAKEDA Ryoji
環境水中ヨウ化物イオンの迅速かつ選択的回収に向けた電気化学的手法の速度論的検討
山崎信哉、武田凌治��������������������������������� 56

Speciation Radiochemistry/存在形態
P-31

P-32

P-33

P-34
P-35

Variation of Cs activity concentration in flooded and pore water in paddy fields and its
transfer to rice
TSUKADA Hirofumi, SAITO Takashi, HIRAYAMA Takashi, MATSUOKA Hiroaki,
NAKAO Atsushi
田面水および間隙水中137Cs濃度の変化とイネへの移行
塚田祥文、齋藤隆、平山孝、松岡宏明、中尾淳��������������������� 57
Environmental transfer parameter values for internal dose assessment obtained by QSTNIRS in 2011-2022
TAGAMI Keiko, UCHIDA Shigeo
量研−放医研によって2011-2022年に収集された内部被ばく線量評価のための環境移行パラメータ値について
田上恵子、内田滋夫��������������������������������� 58
Cesium separation from aqueous waste matrices using crown ether functionalized mesoporous
silicaRashedul Islam RIPON, Zinnat A. BEGUM, Bashir Ahmmad ARIMA, OGATA Makoto,
TAKAGAI Yoshitaka, Ismail M. M. RAHMAN ��������������������� 59
Physical and chemical traits of cesium and strontium tolerance in velvet grass（Holcus
lanatus L.）
Bayezid M. KHAN, M. Ferdous ALAM, Zinnat A. BEGUM, Ismail M. M. RAHMAN����� 60
Temporal change of 137Cs fractions in archived soil samples collected from Fukushima
Prefecture in 2011YANAGIGAWA Kento, TATSUNO Takahiro, TSUKADA Hirofumi
2011年に福島県から採取した土壌アーカイブ試料の137Cs存在形態の経時変化に関する研究栁川賢斗、辰野宇大、塚田祥文���������������������������� 61
137

Modeling/モデリング
P-36
P-37

Modeling the impact of forest fires in the Chornobyl Exclusion Zone on radionuclide
contamination of surface waters
Oleksandr PYLYPENKO, Mykola TALERKO, Mark ZHELEZNYAK ����������� 62
Simulation of tritium releases into the atmosphere during the Fukushima accident and into
the ocean due to planned discharge of treated water
Alexandre CAUQUOIN, Maksym GUSYEV, KOMURO Yoshiki, Hayoung BONG,
OKAZAKI Atsushi, YOSHIMURA Kei ������������������������� 63

9

The 10th Annual Symposium of the IER, Fukushima University / 福島大学環境放射能研究所 第 10 回成果報告会

市民向けシンポジウム
Symposium for the General Public

10The 10th Annual Symposium of the IER, Fukushima University / 福島大学環境放射能研究所 第 10 回成果報告会

S-01
Tritium in the marine environment before and after the ALPS
treated water discharge
TAKATA Hyoe*1, SATOH Shun2, MIURA Hikaru3, NISHINO Keisuke3, OHTSUKI Satoru2,
WADA Toshihiro1
Institute of Environmental Radioactivity, Fukushima University, 2Graduate School of Symbiotic Systems Science

1and Technology, Fukushima University, 3Sustainable System Research Laboratory, Central Research Institute ofElectric Power Industry*Corresponding author： h.takata@ier.fukushima-u.ac.jp

This presentation focuses on spatiotemporal distributions of tritium（H-3）in coastal seawater and marineorganisms collected near the Fukushima Daiichi Nuclear Power Plant（FDNPP）from 2021. Activities of
H-3 in coastal seawater were about 0.1 Bq/L from 2021 to the early 2023 just before the discharge of
ALPS treated water, with no significant change over time. Distribution of H-3 in marine organisms was
similar to that in corresponding seawater. Relatively high values were observed within 5 km radius fromthe outlet on 5 September 2023 during the first discharge（24 August to 11 September）. However, it was
not similar on 11 October during the second discharge（5 October to 23 October）. Distribution of tritiumin coastal region around the FDNPP could be affected by the coastal currents. We will also present thedata after the second discharge.
Keywords： coastal region, tritium level, seawater, marine organism

ALPS処理水放出前後の海のトリチウム
高田兵衛*1、佐藤俊2、三浦輝3、西野圭佑3、大槻哲2、和田敏裕1
福島大学環境放射能研究所、2福島大学大学院共生システム理工学研究科、3電力中央研究所サステナブルシステム

1

研究本部*責任著者：h.takata@ier.fukushima-u.ac.jp

本成果報告会では、福島第一原子力発電所（FDNPP）近傍の沿岸海域において2021年から採取された沿岸海
水および海洋生物中のトリチウム（H-3）の時空間分布について速報する。沿岸海水中のH-3濃度は、2021年からALPS処理水放出直前の2023年初頭まで約0.1 Bq/Lであり大きな変化は見られなかった。海洋生物中のH-3も同様であった。2023年の夏に最初のALPS処理水が放出され、放出期間中（８月24日～９月11日）の2023年９月５日に採取した結果、放出口から半径５km以内において、比較的高いトリチウムが観測された。
一方、２回目の放出期間中（10月５日～10月23日）の10月11日に採取した結果は必ずしも１回目と同様の分布ではなかった。FDNPP周辺の沿岸域におけるトリチウムの分布は、主に沿岸の海流などに依存していることが示唆される。本報告会では、２回目以降に得られた結果も加えつつ発表する。
キーワード：沿岸海域、トリチウムレベル、海水、海産生物

11

The 10th Annual Symposium of the IER, Fukushima University / 福島大学環境放射能研究所 第 10 回成果報告会

S-02
Toward understanding radionuclide cycling in forest ecosystems
Vasyl YOSCHENKO*1, NANBA Kenji1
Institute of Environmental Radioactivity, Fukushima University

1*Corresponding author： r705@ipc.fukushima-u.ac.jp

The forest ecosystems contaminated by the Fukushima accident are and will remain the largest depot ofradiocesium in the terrestrial environment in the long term. Due to the high levels of radioactive
contamination, forests in the evacuation areas have been excluded from economic use. The possibility ofresuming commercial forestry in severe contaminated areas will depend on the compliance of radiocesium
concentrations in forest products, primarily in wood, with the relevant national standards. Accordingly,
assessment of the perspectives of forestry revitalization and development of the adequate forestry
strategies require knowledge of radiocesium dynamics in forest ecosystems. In this review, we analyze
the principal dynamics trends observed in the early and later stages after the deposition in Fukushima
forests and in the late stage in Chornobyl forests. We investigate local factors that may be associatedwith the observed trends, identify knowledge gaps, and discuss perspective researches aimed at
improving the understanding of biogeochemical cycles of radionuclides and elements in forest ecosystems.
Keywords： forest ecosystems, radiocesium, radionuclide cycling, Fukushima, Chornobyl

12

The 10th Annual Symposium of the IER, Fukushima University / 福島大学環境放射能研究所 第 10 回成果報告会

S-03
Nature-based regeneration of agriculture and forestry inFukushima
KANEKO Nobuhiro*1
Faculty of Food and Agricultural Sciences, Fukushima University

1*Corresponding author： kaneko-nobuhirro@agri.fukushima-u.ac.jp

Considering farmland and forests as part of the ecosystem, we would like to consider the revitalization ofagriculture and forestry in Fukushima on a natural basis. Twelve years after the earthquake, only 38% of
the farmers in the formerly evacuated areas have resumed farming. This has not been addressed byfacility development, smart farming, and larger-scale management alone. No-tillage cultivation is a basic
technology for regenerative agriculture, which improves soil physicochemical properties by ensuringbiodiversity in the soil ecosystem. It can keep farmland soil healthy while saving costs, fix carbon dioxidein the soil as a climate change countermeasure, and increase the resilience of agriculture to extreme
weather conditions. In forests, the Fukushima Reforestation Project was implemented mainly in planted
forests to maintain forestry production, and the Satoyama Reforestation Project in natural forests.
However, as with agriculture, there is a lack of supporters and a high degree of dependence on subsidies.
Instead of focusing on the limited use of coniferous timber and shiitake mushroom logs, the multifaceted
function of forests should be utilized. In mid-mountainous areas, it is effective to cut down and utilize
forests around agricultural lands that are obstructing sunlight. Forest can be regenerated at low cost by
renewing the forests through sprouting and renewal, and by using the heat as small-scale distributed
bioenergy, it can become a self-sufficient resource that can replace fossil fuels. In addition to securing
sunlight, the forests can be expected to have a multifaceted effect in preventing animal damage andcreating employment. The use of these nature-based resources is important for the reconstruction of
Fukushima.
Keywords： soil ecology, regenerative agriculture, coppice forest

自然ベースの福島の農業と林業の「再生」
金子信博*1
福島大学食農学類

1*責任著者：kaneko-nobuhirro@agri.fukushima-u.ac.jp

農地と森林を生態系の一部と考え、自然ベースでの福島の農林業再生について考えてみたい。震災から12年がたったが、旧避難地域では38％程度しか営農再開されていない。施設整備やスマート農業、そして経営の大型化だけでは対処できていない。不耕起草生栽培は、環境再生型農業の基礎技術であり、土壌生態系の生物多様性を確保することで土壌の理化学性を向上させ，省コストながら農地土壌を健康に保ち、気候変動対策としての土壌への二酸化炭素の固定や、異常気象への栽培のレジリエンスを高めることができる。森林では人工林を中心にふくしま森林再生事業が行われ、天然生林では里山再生事業が行われた。しかし、農業と同様担い手不足であり、補助金への依存度が高い。針葉樹の用材利用としいたけ原木という限られた利用にこだわることなく、森林の多面的機能を活かすべきである。中山間地では、日照を阻害している農地周りの
旧薪炭林の森林の伐採利用が有効である。萌芽更新により省コストで森林の再生利用が可能であり、小規模分散型のバイオエネルギーとして熱利用を行うことで、化石燃料を代替できる自給資源となる。日照確保だ
けでなく、獣害対策、そして雇用の創出といった多面的な効果が期待できる。これら自然ベースの資源利用
が福島の復興にとって重要である。
キーワード：土壌生態学、環境再生型農業、萌芽再生林
13

The 10th Annual Symposium of the IER, Fukushima University / 福島大学環境放射能研究所 第 10 回成果報告会

S-04
Elucidation of fish migration ecology and fisheries restoration in
Fukushima Prefecture
WADA Toshihiro*1
Institute of Environmental Radioactivity, Fukushima University

1*Corresponding author： t-wada@ipc.fukushima-u.ac.jp

Approximately 13 years after the Fukushima Daiichi Nuclear Power Plant （FDNPP） accident,
radiocesium（134Cs and 137Cs, hereafter Cs）contamination of marine products has almost been settled.
However, some fish in the FDNPP port still exceeded the Japanese regulatory limit of 100 Bq/kg, raisinga concern about the potential risk of their migration to fishing grounds（outside the 10 km radius fromthe FDNPP）. Black rockfish Sebastes schlegelii, for which shipment restrictions have been implemented by
the government, is considered as an example. In recent years, the proportion of individuals exceeding theregulatory limit has tended to increase within the FDNPP port, indicating the necessity to elucidate thecontamination mechanism and migration ecology of fish with higher Cs concentrations. In thispresentation, first, the relationship between Cs concentrations and the distribution and/or migration offish observed after the FDNPP accident will be presented based on some examples to show that Cs canbe used as a tracer of fish migration. Then, based on the recent bio-logging research using electronic tags
（water temperature and depth loggers）attached to fish, the potential applicability of the research toassess the risk of migration of fish from the FDNPP port and its contribution to the fisheries restorationin Fukushima Prefecture will be introduced. The species introduced will be spotted halibut, a high-priced
rare flatfish, and tiger puffer fish, the catch of which has been increasing remarkably in Fukushima.
Where and how do Fukushima's tiger puffer fish migrate to? I will introduce a part of the mystery.
Keywords： fisheries restoration, radioactive contamination, bio-logging, spotted halibut, tigger puffer fish

魚類の移動生態の解明と福島県の漁業復興
和田敏裕*1
福島大学環境放射能研究所

1*責任著者：t-wada@ipc.fukushima-u.ac.jp

原発事故からおよそ13年が経過し、海産物の放射性セシウム（134Cs及び137Cs、以下Cs）汚染は収束しつつある。
ただし、依然として福島第一原発港内の一部の魚類で基準値100 Bq/kgを超過しており、それらの漁場（原発から10km圏外）への移動が潜在的なリスクとして懸念されている。現在、国の出荷制限措置が取られているクロソイは、原発港内からの移動によるリスクが顕在化した例と考えられている。近年、原発港内では、基準値を超過する個体の割合が増加する傾向にあり、Cs濃度の高い魚類の出現メカニズムや移動生態の解明が強く求められる。本講演では、まず、原発事故以降に認められた魚類の分布や移動とCs濃度の関係性について、特徴的な事例をもとに示し、Csが魚類の移動のトレーサーとして有効であることを示す。また、魚体に装着する電子タグ（水温・深度ロガー）を用いた最新の研究（バイオロギング調査）をもとに、魚類の移動生態研究が、原発港内等からの移動のリスク評価だけでなく、福島県の漁業復興にも寄与する可能性について紹介する。紹介する魚種は幻の高級魚ホシガレイと漁獲量の増加が著しいトラフグである。福島のトラ
フグはどこにどのように移動するのか？謎の一端を紹介する。
キーワード：漁業復興、放射能汚染、バイオロギング、ホシガレイ、トラフグ

14The 10th Annual Symposium of the IER, Fukushima University / 福島大学環境放射能研究所 第 10 回成果報告会

S-05
Small amounts of radioactive strontium accumulated in small
animals
TAKAGAI Yoshitaka* １
Fukushima University

１*Corresponding author： s015@ipc.fukushima-u.ac.jp

Radioactive strontium 90（90Sr）is one of the most difficult radioactive materials to measure. As far, it has
been still challenging to measure extremely small amounts of 90Sr in samples that can be collected in only
small quantities（e.g., teeth, bones of small animals, etc.）. In 2023, Fukushima University first reported in
the world to be able to measure extremely small levels of 90Sr contained in a small amount of sample
using thermal ionization mass spectrometry （TIMS）. While conventional analysis requires the
preparation of gram-level samples（１ to 100 g）, this technique requires only １ milligram（mg）of sample
and can accurately measure radioactive strontium levels（0.98 ag（5.0 µBq））that have never beenmeasured before in the world. This technique enables precise measurement of amount of 90Sr
accumulation in the teeth and bones in small animals and fish, which has been unknown until now. In thispresentation, I would like to introduce a piece of hot results from this research.
Keywords： strontium 90, 90Sr, thermal ionization mass-spectrometry, small animal, teeth, bone

小動物に蓄積したわずかな量の放射性ストロンチウムを追いかける
高貝慶隆*1
福島大学

1*責任著者：s015@ipc.fukushima-u.ac.jp

放射性ストロンチウム90（90Sr）は、放射性物質の中でも特に分析することが難しいものの一つである。現在
まで、サンプル量が現実的に少量しか採取できないもの（例えば、歯、小動物の骨など）については、極微量
な90Srを測定することすらできなかった。2023年、福島大学は、表面電離型質量分析によって、世界で初めてわずかな量の試料に含まれる90Srを測定できることを報告した。
従来、分析する際はグラムレベル（１～100g）の試料を準備する必要があったが、この技術は１ミリグラム（mg）程度の試料で測定でき、世界で誰もなし遂げたことのないレベルの放射性ストロンチウム量（0.98 ag（5.0 µBq））
を正確に測ることができる[ag：アトグラム＝10-18 g]。この技術によって、これまで未解明であった小動物や魚類の歯や骨への放射性ストロンチウムの蓄積を正確に測定できるようになる。今回はその研究成果の一端を紹介する。
キーワード：ストロンチウム90、90Sr、表面電離型質量分析、小動物、歯牙、骨15

The 10th Annual Symposium of the IER, Fukushima University / 福島大学環境放射能研究所 第 10 回成果報告会

S-06
Anthropogenic and natural tritium radionuclide for numericalmodeling of terrestrial water transit times
Maksym GUSYEV*1, Alexandre CAUQUOIN2, IGARASHI Yasunori1, TAKATA Hyoe1,
HIRAO Shigekazu1, AKATA Naofumi3, SHIBASAKI Naoaki1,4
Institute of Environmental Radioactivity, Fukushima University, 2Institute of Industrial Science, The University

1of Tokyo, 3Institute of Radiation Emergency Medicine, Hirosaki University, 4Faculty of Symbiotic Systems
Science, Fukushima University*Corresponding author： r891@ipc.fukushima-u.ac.jp; maksymgusyev@gmail.com

Tritium（3H）radioisotope with a half-life of 12.32 years has been generated due to anthropogenic
activities of thermonuclear atmospheric testing in 1960s and nuclear facilities worldwide while 3H isnaturally generated in the upper atmosphere by cosmic rays entering the water cycle in the troposphereas the water molecule（HTO）. In 2011, the atmospheric release of the Fukushima Daiichi Nuclear Power
Plant（FDNPP）accident contributed anthropogenic 3H to the water cycle, especially for coastal
groundwater systems nearby the FDNPP, and the recent international attention has been focused on the
Advanced Liquid Processing System（ALPS）treated water discharge from the FDNPP site to the Pacific
Ocean. From 1960 to present, 3H measurements in precipitation have been conducted by the Global
Network of Isotopes in Precipitation（GNIP）of the International Atomic Energy Agency（IAEA）and
World Meteorological Organization（WMO）worldwide and by the Government and Universities acrossJapan. In Fukushima Prefecture, 3H measurements in monthly precipitation are available at several sites
such as Fukushima city, Namie Town, and Institute of Environmental Radioactivity and many surface
and coastal water sites have been sampled twice per year accumulating a decade-long record of 3H
measurements. For Fukushima surface water sites, measured 3H concentrations indicate low 3H levels
and could be utilized to estimate terrestrial water cycle transit times. To utilize 3H-tracer in Fukushima,
we combine simulated anthropogenic 3H released by the FDNPP in 2011 with the long-term time-series of3
H in precipitation from 1950 to present in the Tokyo area, which was scaled to Fukushima area between
1.30 and 1.61. In addition, we estimated 3H-tracer mean transit time and subsurface water storage volume
after the ALPS-treated water discharge at several headwater catchments near Fukushima city as well as
3
H contribution of the ALPS-treated water discharge to the Pacific Ocean. Therefore, we demonstratethat environmental 3H radioisotope is a useful tracer with developed 3H time-series in precipitation andsurface water measurements to evaluate terrestrial water cycle in Fukushima Prefecture.
Keywords： tritium radioisotope, numerical modeling, stream water, mean transit times

16The 10th Annual Symposium of the IER, Fukushima University / 福島大学環境放射能研究所 第 10 回成果報告会

Oral Presentation for Experts

専門家向け口頭発表

18

The 10th Annual Symposium of the IER, Fukushima University / 福島大学環境放射能研究所 第 10 回成果報告会

O-01
Tritium in the marine environment before and after the ALPS
treated water discharge
TAKATA Hyoe*1, SATOH Shun2, MIURA Hikaru3, NISHINO Keisuke3, OHTSUKI Satoru2,
WADA Toshihiro1
Institute of Environmental Radioactivity, Fukushima University, 2Graduate School of Symbiotic Systems Science

1and Technology, Fukushima University, 3Sustainable System Research Laboratory, Central Research Institute ofElectric Power Industry*Corresponding author： h.takata@ier.fukushima-u.ac.jp

This presentation focuses on spatiotemporal distributions of tritium（H-3）in coastal seawater and marineorganisms collected near the Fukushima Daiichi Nuclear Power Plant（FDNPP）from 2021. Activities of
H-3 in coastal seawater were about 0.1 Bq/L from 2021 to the early 2023 just before the discharge of
ALPS treated water, with no significant change over time. Distribution of H-3 in marine organisms was
similar to that in corresponding seawater. Relatively high values were observed within 5 km radius fromthe outlet on 5 September 2023 during the first discharge（24 August to 11 September）. However, it was
not similar on 11 October during the second discharge（5 October to 23 October）. Distribution of tritiumin coastal region around the FDNPP could be affected by the coastal currents. We will also present thedata after the second discharge.
Keywords： coastal region, tritium level, seawater, marine organism

ALPS処理水放出前後の海のトリチウム
高田兵衛*1、佐藤俊2、三浦輝3、西野圭佑3、大槻哲2、和田敏裕1
福島大学環境放射能研究所、2福島大学大学院共生システム理工学研究科、3電力中央研究所サステナブルシステム

1

研究本部*責任著者：h.takata@ier.fukushima-u.ac.jp

本成果報告会では、福島第一原子力発電所（FDNPP）近傍の沿岸海域において2021年から採取された沿岸海
水および海洋生物中のトリチウム（H-3）の時空間分布について速報する。沿岸海水中のH-3濃度は、2021年からALPS処理水放出直前の2023年初頭まで約0.1 Bq/Lであり大きな変化は見られなかった。海洋生物中のH-3も同様であった。2023年の夏に最初のALPS処理水が放出され、放出期間中（８月24日～９月11日）の2023年９月５日に採取した結果、放出口から半径５km以内において、比較的高いトリチウムが観測された。
一方、２回目の放出期間中（10月５日～10月23日）の10月11日に採取した結果は必ずしも１回目と同様の分布ではなかった。FDNPP周辺の沿岸域におけるトリチウムの分布は、主に沿岸の海流などに依存していることが示唆される。本報告会では、２回目以降に得られた結果も加えつつ発表する。
キーワード：沿岸海域、トリチウムレベル、海水、海産生物

19

The 10th Annual Symposium of the IER, Fukushima University / 福島大学環境放射能研究所 第 10 回成果報告会

O-02
Evaluating terrestrial water cycle using numerical modeling withtritium radioisotope in Fukushima, Japan
Maksym GUSYEV*1, Alexandre CAUQUOIN2, IGARASHI Yasunori1, TAKATA Hyoe1,
HIRAO Shigekazu1, AKATA Naofumi3
1

Institute of Environmental Radioactivity, Fukushima University, 2Institute of Industrial Science, The Universityof Tokyo, 3Institute of Radiation Emergency Medicine, Hirosaki University*Corresponding author： r891@ipc.fukushima-u.ac.jp; maksymgusyev@gmail.com

Environmental tritium（3H）radioisotope with a half-life of 12.32 years is naturally generated in the upper
atmosphere by cosmic rays and enters the water cycle in the troposphere as the water molecule（HTO）
to become a useful terrestrial water cycle tracer. In 2011, anthropogenic 3H entered the terrestrial water
cycle due to the Fukushima Daiichi Nuclear Power Plant（FDNPP）atmospheric release and discharged
in Advanced Liquid Processing System（ALPS）treated water from the FDNPP site to the Pacific Ocean
in 2023 raising concerns internationally. In Japan, 3H measurements in monthly precipitation have been
conducted by the Government and Universities while many surface water sites were sampled twice per
year across Fukushima Prefecture accumulating a decade-long record of 3H measurements. However,there are no 3H measurements in precipitation during the FDNPP accident requiring atmosphericnumerical modeling to quantify anthropogenic 3H in Fukushima. To utilize 3H-tracer in Fukushima, we
combine simulated anthropogenic 3H released by the FDNPP in 2011 with the long-term time-series of 3H
in precipitation from 1950 to present in the Tokyo area, which was scaled to Fukushima area. Usingannual 3H in precipitation is 2.86 TU-3.70 TU with an average of 3.37 TU from 2016 to 2021 lead to thescaling factor from Tokyo area to Fukushima city between 1.30 and 1.61. For Fukushima surface watersites, measured 3H concentrations indicate low 3H levels and are utilized to estimate terrestrial water
cycle transit times. In addition, we sampled several headwater catchments near Fukushima city formeasuring 3H in October 2023 and estimated tritium-tracer mean transit time and subsurface water
storage volume after the ALPS-treated water discharge. Therefore, we demonstrate that environmental
3
H radioisotope is a useful tracer with developed 3H time-series in precipitation and surface watermeasurements to evaluate terrestrial water cycle in Fukushima.
Keywords： tritium radioisotope, numerical modeling, stream water, mean transit times

20

The 10th Annual Symposium of the IER, Fukushima University / 福島大学環境放射能研究所 第 10 回成果報告会

O-03
Investigation of atmospheric tritiated water vapor in Fukushima
HIRAO Shigekazu*1, KAKIUCHI Hideki2
Institute of Environmental Radioactivity, Fukushima University, 2Institute for Environmental Sciences

1*Corresponding author： r786@ipc.fukushima-u.ac.jp

There is a need for scientific knowledge to evaluate the environmental impact associated with the releaseof ALPS-treated water stored at the TEPCO's Fukushima Daiichi Nuclear Power Station（FDNPS）into
the ocean. Since an atmospheric transport of radionuclides is the fastest pathway to organisms living onland, it is necessary to first obtain actual measurements of atmospheric concentrations. However, thenumber of atmospheric monitoring is small compared to the substantial expansion of ocean monitoring. In
this study, tritium concentrations in atmospheric water vapor in the vicinity of FDNPS were measured
and the relationship between the concentration fluctuations and the source and meteorological conditions
were examined. It is revealed that the tritium concentration in atmospheric water vapor was ranged
within the variation in the past observation although the tritium concentration obtained was slightly
higher than that of the recent background level in Japan. These results would be used for assessment of
the environmental impact of tritium near the source.
Keywords： tritiated water vapor, atmospheric concentration, LB7

福島での大気水蒸気中トリチウム調査
平尾茂一*1、柿内秀樹2
福島大学環境放射能研究所、2公益財団法人環境科学技術研究所

1*責任著者：s-hirao@ipc.fukushima-u.ac.jp

ALPS処理水の海洋放出前後の環境トリチウムの実態解明は喫緊の課題である。大気拡散過程は陸上に住む生物に至る最も速い経路となるため、まずは大気中濃度の実測値を得る必要がある。しかし、海洋モニタリ
ングが大幅に拡充されたことに比べると、大気モニタリングの数は少ない。本研究では、福島第一原子力発
電所の近傍のトリチウムの大気水蒸気中濃度を実測し、濃度変動と発生源および気象状況との関連を検討した。その結果、過去の変動幅の範囲内ではあるが、ごく近傍では近年の日本の一般環境よりもやや高いトリ
チウム濃度であることが示された。これら結果は発生源付近の環境トリチウム影響評価のための基本的な情報として重要である。
キーワード：大気水蒸気トリチウム、大気濃度、LB7

21

The 10th Annual Symposium of the IER, Fukushima University / 福島大学環境放射能研究所 第 10 回成果報告会

O-04
Evaluation of molecular tritium deposition onto farmland soil
KAKIUCHI Hideki*1, NAGAI Masaru1
Institute for Environmental Sciences

1*Corresponding author： ckhsd@ies.or.jp

Tritium（3H）existed in the atmosphere is as main chemical forms of molecular hydrogen（HT）and
water molecule（HTO）. In general, the oxidation rate of hydrogen depends on the activity of soil
microorganisms, and is affected by the environment conditions such as soil temperature, soil moistureand porosity. HT is thought to be radiologically less toxic compared to HTO, but HT would be potentially
toxic for the public by rapid oxidation of HT to HTO on soil surface. Thus, we evaluated the hydrogen
deposition velocity of soils in Rokkasho village, Aomori, Japan. For determination of the hydrogen
deposition velocity, the closed chambers with a fan were set on the soils of farmlands where Japaneseradish was grown, and changes of HT concentration in the chambers were measured. There wereseveral reports evaluated hydrogen oxidation or deposition on soil surface. The reported deposition
velocities were from 1.0 x10-5 to 3.6 x10-3, and the data in our experiments were within this range.
Keywords： molecular hydrogen, tritium, deposition

分子状トリチウムの耕作地土壌への沈着の評価
柿内秀樹*1、永井勝1
公益財団法人環境科学技術研究所

1*責任著者：ckhsd@ies.or.jp

大気中のトリチウムは主に分子状水素及び水蒸気として存在している。一般的に分子状水素は土壌表面で微生物により酸化されるが、その速度は環境要因により大きく変化することが知られている。分子状トリチウ
ムは水蒸気状トリチウムと比較して放射線影響は小さいとされているが、環境中で速やかに酸化されるため潜在的にその影響は無視できない。そこで耕作地土壌に実験用チャンバーを設置し、チャンバー内HT濃度変化から沈着速度を評価した。その結果得られた値は、これまでに報告されたものと同レベルであった。
キーワード：分子状水素、トリチウム、沈着22

The 10th Annual Symposium of the IER, Fukushima University / 福島大学環境放射能研究所 第 10 回成果報告会

O-05
Radiological impact assessment for the ocean discharge of ALPS
treated water
TSUMUNE Daisuke*1, TSUBONO Takaki2, MISUMI Kazuhiro2
Center for Research in Radiation, Isotopes, and Earth System Sciences, University of Tsukuba, 2Central Research

1Institute of Electric Power Industry*Corresponding author： tsumune.daisuke.gw@u.tsukuba.ac.jp

A radiological impact assessment from the oceanic discharge of ALPS-treated water from the Fukushima
Daiichi Nuclear Power Plant was conducted. In this evaluation, a regional ocean model used for
replicating 137Cs originating from the Fukushima Daiichi Nuclear Power Plant accident was employed toestimate the spatiotemporal average concentration of released radioactive substances in the maritime
area. Due to the substantial spatiotemporal variations caused by mesoscale eddies and the Kuroshio
Current, direct comparisons between simulation results and observed data, which exhibit significant
fluctuations, are challenging. However, simulated 137Cs concentrations attributable to the direct release
contributing to the annual average radioactive concentration distribution were found to align well withthe annual averaged observed results. Furthermore, it was confirmed that the annual averaged 137Csconcentration distribution from 2013 to 2016 normalized by the direct release rate exhibited a nearly
identical pattern. In other words, knowing the release rate allows the prediction of the annual averaged
radioactive concentration distribution. Using this model, the concentration distribution of radioactive
substances in the ocean resulting from the oceanic discharge of ALPS-treated water was forecasted. In
the assessment of the annual dose using the nearby yearly average concentration, the dominant factor
was the ingestion of seafood, and the value was at a level that could be disregarded, approximately 10-5
mSv/year.
Keywords： ALPS treated water, regional ocean model, radiological impact assessment

ALPS処理水の海洋放出に対する放射線影響評価
津旨大輔*1、坪野考樹2、三角和弘2
筑波大学放射線・アイソトープ地球システム研究センター、2電力中央研究所

1*責任著者：tsumune.daisuke.gw@u.tsukuba.ac.jp

福島第一原子力発電所からのALPS処理水の海洋放出に対する放射線影響評価が実施された。この評価では、
放射性物質の海域における時空間の平均濃度を推定する必要があり、福島第一原子力発電所事故起源の放射性セシウムの再現計算には海洋モデルが使用された。海洋中の137Cs濃度分布は、中規模渦や黒潮の影響により大きな時空間変動を示すため、シミュレーション結果と観測結果の直接的な比較は難しかった。しかし年平均の137Cs濃度分布のシミュレーション結果は、年平均観測結果とよく一致した。また2013年から2016年までの年平均137Cs濃度分布は、直接漏洩率で正規化するとほぼ同様の分布になった。言い換えれば、放出率が分かれば、年平均の放射性物質濃度分布を予測できることが分かった。このモデルを用いて、ALPS処理水の海洋放出による海洋中の放射性物質濃度分布を予測した。近傍の年間平均放射性物質濃度を用いた被ばく
線量評価では、海産物の摂取が支配的であり、その値は10-5 mSv/yearのオーダーで無視できるレベルであった。
キーワード：ALPS処理水、領域海洋モデル、放射線影響評価

23

The 10th Annual Symposium of the IER, Fukushima University / 福島大学環境放射能研究所 第 10 回成果報告会

O-06
Independent evaluation by an advisory board of ten years of
research by Institute of Environmental Radioactivity on theconsequences of the Fukushima Daiichi accident
Brenda HOWARD*1, Wolfgang RASKOB2, Sergey FESENKO3, YOSHIDA Satoshi4
UK Centre for Ecology and Hydrology, United Kingdom, 2Karlsruhe Institute of Technology, Germany, 3Russian

1

Academy of Sciences, Russian Institute of Radiology and Agroecology, Russian Federation, 4Institute forEnvironmental Sciences, Japan*Corresponding author： bjho@live.com

The Institute of Environmental Radioactivity was rapidly set up as a research centre at Fukushima
University after the Fukushima Daichi accident in 2011. It successfully incorporated several
internationally renowned scientists from both Japan and other countries with a range of different relevant
expertise. A number of staff at the university also participated in addressing the wide range of challenges
that Fukushima Prefecture faced after the accident.
The staff at IER faced various challenges related to:•
the need for local scientific expertise regarding the environmental behaviour of the various
radioactive releases in terrestrial forested and agricultural areas, and in freshwater and marine systems
in Fukushima Prefecture•
active engagement with, and support to, Fukushima Prefecture•interaction with affected communities to address local concerns and provide a local source of
information about the contamination, its impact on agriculture, forested areas and communities.
The IER set up an Advisory Board from several countries to provide an independent annual evaluationof the approaches adopted by IER and the quality and quantity of ongoing research efforts of the IER.
From March 2018 onwards the advisory board attended annual meetings in Fukushima to review theactivities of IER with online engagement when covid prevented personal attendance.
The quality and quantity of the various outputs of IER research activities was evaluated by the Advisory
Board. The research groups in IER included: Rivers and Lakes, Ocean, Ecosystems, Measurement andAnalysis, Speciation Radiochemistry, and Modelling. The Board listened to lectures on the various
activities, attended poster sessions, reviewed annual reports, refereed papers and conference
contributions through engagement with each topic area leader. The advisory board critically evaluatedeach subsequent annual report provided by IER and suggested possible improvements that might bemade. It also evaluated the quantity and quality of research output of IER including refereed scientificpublications, scientific conference papers and the interaction with local organizations and communities.

24

The 10th Annual Symposium of the IER, Fukushima University / 福島大学環境放射能研究所 第 10 回成果報告会

Poster Presentation for Experts

専門家向けポスター発表

26

The 10th Annual Symposium of the IER, Fukushima University / 福島大学環境放射能研究所 第 10 回成果報告会

P-01
Spatial and vertical distribution of radiocesium in marine sedimentcores of Fukushima Prefecture
Pierre-Alexis CHABOCHE*1,2, WAKIYAMA Yoshifumi2, TAKATA Hyoe2, WADA Toshihiro2,
MISONOU Toshiharu3, SHIRIBIKI Takehiko3, FUNAKI Hironori3
International Research Fellow of Japan Society for the Promotion of Science（Postdoctoral Fellowships for

1

Research in Japan（Standard））, 2Institute of Environmental Radioactivity, Fukushima University, 3Sector of
Fukushima Research and Development, Japan Atomic Energy Agency*Corresponding author： p.chaboche@protonmail.com

The Fukushima Dai-ichi Nuclear Power Plant（FDNPP）incident, triggered by the Great East Japan
Earthquake and subsequent tsunami in March 2011, resulted in the release of significant quantities ofradionuclides into the terrestrial and marine environments of Fukushima Prefecture. While the activity ofradiocesium（i.e., 134Cs and 137Cs）in these environments has decreased since the accident, continuous
inputs through rivers draining and eroding the main terrestrial radioactive plume have been measured,maintaining elevated levels of 137Cs in riverine and coastal sediment deposited off the Prefecture’s coast.
Consequently, identifying the sources of sediment is required to elucidate the links between terrestrial
and marine radiocesium dynamics and to anticipate the fate of persistent radionuclides in theenvironment. Our study aims to implement the fingerprinting technique for quantifying catchment
source contributions to coastal sediment and the associated radionuclides deposited off the coast of
Fukushima Prefecture. Six targeted coastal sediment cores, ranging from 20 to 60 cm in depth, werecollected during cruise campaigns between July and September 2022 at the Ota（n=2）, Niida（n=1）, andUkedo（n=3）river mouths. Before gamma spectrometry measurements, sediment cores were opened, cut
into 2 cm increments, oven-dried at 50 ℃ for at least 48 h, ground, and passed through a 2-mm sieve.
Preliminary findings concerning the spatial and depth distribution of radiocesium in these samples reveala strong heterogeneity, with the highest radiocesium levels（up to 134 ± 2 and 4882 ± 11 Bq kg-1 for134
Cs and 137Cs, respectively）observed in coastal sediment cores situated at the Ukedo river mouth. A
strong relationship is observed between the particle size measured in these sediment cores andradiocesium activities, with higher levels observed in finer sediment. Conversely, no traces or low levelsof Fukushima-derived radiocesium were detected in the Niida and one sediment core of the Ota Rivermouths. Importantly, features of the seafloor topography were shown to be significant factors controllingthe spatial and depth distribution of radiocesium off Fukushima’s coast. Additional measurements are
currently conducted to determine the physico-chemical properties of this sediment（XRF core scanner,
X-ray CT scanner, elemental geochemical concentration）to identify the optimal combination of tracers.
These selected tracers will be incorporated into widely used un-mixing models to quantify source
contributions to coastal sediment and develop an original approach for marine environments. This
increased knowledge will undoubtedly be useful to understand 137Cs transfer processes between
continental and marine environments, as well as for watershed and coastal management in the postaccidental context of the FDNPP.
Keywords： North Pacific Ocean, sediment tracing, heavy rainfall event

27

The 10th Annual Symposium of the IER, Fukushima University / 福島大学環境放射能研究所 第 10 回成果報告会

P-02
Estimation of Cs-137 fluxes into the ocean: comparison of direct
release and river discharge
SATOH Shun*1, TAKATA Hyoe2, WAKIYAMA Yoshifumi2, OHTSUKI Satoru1
Graduate School of Symbiotic Systems Science and Technology, Fukushima University, 2Institute of1

Environmental Radioactivity, Fukushima University*Corresponding author： s2270054@ipc.fukushima-u.ac.jp

It has been 12 years since the Fukushima Daiichi Nuclear Power Plant（FDNPP）accident in March 2011,
and the Cs-137 concentrations in the coastal waters of Fukushima continues to be elevated compared topre-accident levels. This study focuses on the factors that maintain Cs-137 concentrations in coastal areas,
with particular attention to the direct release from the FDNPP and the introduction of Cs-137 depositedon land through rivers. We estimated an annual flux for each source. The flux through rivers wascalculated separately for dissolved and particulate phases. The estimated value for direct releasedecreased after the construction of the seaside impermeable wall at the FDNPP. Furthermore, fluxes
may have been affected by other factors such as typhoons and an increase in the production ofcontaminated water. The flux through rivers exhibited a decreasing trend for dissolved Cs-137, however,flux for particulate Cs-137 almost did not change until 2018. Furthermore, total fluxes of dissolved andparticulate Cs-137 during high-flow events may have probably overwhelmed the direct release.
Comparison of the Cs-137 concentration between monitoring data in the coastal seawater and estimatedvalues calculated from the fluxes will be discussed in the presentation.
Keywords： Fukushima Daiichi Nuclear Power Plant, direct release, river, flux

事故後のメタデータを用いた福島沿岸海域への放射性セシウムの流入量の推定
佐藤俊*1、高田兵衛2、脇山義史2、大槻哲1
福島大学大学院共生システム理工学研究科、2福島大学環境放射能研究所

1*責任著者：s2270054@ipc.fukushima-u.ac.jp

2011年３月の福島第一原子力発電所（FDNPP）事故から12年経過した現在も、福島沿岸海域で海水中のCs137濃度が事故前に比べて高い状態が継続している。本研究では沿岸域のCs-137濃度の高止まりの要因として、FDNPPからの直接流入、陸上に沈着したCs-137の河川経由での流入に注目した。それらの経年的な流入量を推定し、福島沿岸海域に与える影響を考察した。河川を経由したCs-137の流入量は溶存態Csと粒子態
Csに分けて算出した。直接流入量の推定値は、FDNPPで汚染水対策として設置された海側遮水壁の設置後、減少した。また、台風などの環境要因や、汚染水発生量の増加などに伴い流入量は変化している可能性が考えられる。河川を経由した流入量は、減少傾向がみられた溶存態に対し、粒子態では2018年前後で下げ止まりの傾向があった。また、両者の流入量の比較から、洪水時の河川からの流入量が直接流入量を上回っていた可能性が示された。さらには、沿岸でのCs-137濃度の推定値と実測値との比較をしながら、両流出量の沿岸域への影響についても考察する。
キーワード：福島第一原子力発電所、直接流入、河川、流入量28

The 10th Annual Symposium of the IER, Fukushima University / 福島大学環境放射能研究所 第 10 回成果報告会

P-03
Field experimental study of basic mechanisms of dissolved 137Csconcentration seasonality in ponds nearby the Fukushima Daiichi
Nuclear Power Plant
Alexei KONOPLEV*1, KUROSAWA Honoka2, WAKIYAMA Yoshifumi1, IGARASHI Yasunori1,
NANBA Kenji1,3
Institute of Environmental Radioactivity, Fukushima University, 2Graduate School of Symbiotic Systems Science

1and Technology, Fukushima University, 3Faculty of Symbiotic Systems Science, Fukushima University*Corresponding author： r701@ipc.fukushima-u.ac.jp

Analysis of available monitoring data for freshwaters of accidentally contaminated areas has revealed two
basic mechanisms responsible for regular seasonal variations of dissolved 137Cs concentrations in water
bodies（increase in summer and decrease in winter）: 1）temperature dependence of radiocesium
desorption from sediments to solution, and 2）ion-exchange remobilization of radiocesium by cations ofammonium generated as a result of organic matter decomposition in anoxic conditions. An equation has
been derived describing seasonal variations of dissolved radiocesium in water bodies considering two key
parameters: water temperature and combined concentration of basic competitive cations. In Fukushima
rivers, which are mostly shallow and fast flowing, ammonium concentration is usually negligible. Forthem the predominant factor of dissolved 137Cs seasonality is temperature dependence of 137Cs desorption.
For stagnated stratified waters of ponds, lakes and dam reservoirs in anoxic conditions, the role ofammonium in 137Cs mobilization can be comparable with that of water temperature or even be prevalent.
Results of a field experimental study of dissolved 137Cs seasonality in three ponds of Okuma town, locatedin difficult-to-return zone of the Fukushima Daiichi Nuclear Power Plant, are presented. Filtration of one
water sample was carried out in situ（at water temperature corresponding to the current temperature ofwater body）, while the other water sample was filtered in laboratory at room temperature（about 20℃）
with a view to investigate influence of temperature and storage on solid-liquid distribution of 137Cs in thecollected water samples. Water temperature was measured during sampling using a hydro-chemicalprobe. Ammonium was measured in the laboratory immediately on return to IER after sampling in a
separate sample kept in a cooler during transportation. Potassium was measured in the same sample byion chromatography. Particulate and dissolved 137Cs in water samples were measured by gammaspectrometry separately after filtration. Comparison of in situ and laboratory filtration results has shown
the validity of laboratory filtration for dissolved 137Cs monitoring in water bodies. The proposed modeland derived equation describe reasonably well the seasonality of dissolved 137Cs in the investigated ponds.
This research was supported by Environmental Radioactivity Research Center（ERAN）Projects I-23-11
and I-23-12.
Keywords： Fukushima, ponds, 137Cs, dissolved, seasonality, sorption-desorption, water temperature,ammonium29

The 10th Annual Symposium of the IER, Fukushima University / 福島大学環境放射能研究所 第 10 回成果報告会

P-04
Using 137Cs re-sampling and depth-incremental technique toinvestigate the fate of Chernobyl-derived particulate 137Cs
transferred with sediment fluxes
Maksim M. IVANOV*1, Valentin GOLOSOV1,2, Nadezhda IVANOVA1, Anna USACHEVA2,3,
Nikolai LUGOVOI1,2, Nikita DIMCHUK2,4, Nikita KVASOV2,4, Polina FOMINIKH2, Yulia POLETAYEVA2Laboratory of Soil Erosion and River Channel Processes, Faculty of Geography, Lomonosov Moscow State

1

University, 2Institute of Geography, Russian Academy of Science, 3Institute of Geology of Ore Deposits,
Petrography, Mineralogy and Geochemistry, Russian Academy of Sciences, 4Moscow Timiryazev Agricultural
Academy*Corresponding author: ivanovm@bk.ru

Decades after the Chernobyl accident, accelerated erosion of arable land within contaminated rurallandscapes is believed to be the dominant source of particulate 137Cs in riverine systems. Recently the
major part of sediments eroded from arable lands re-deposited either within cultivated slopes or in theupper reaches of the fluvial network（slope hollows and dry valleys）due to serious decreasing of erosion
during snow-melting in European part of Russia. Re-sampling applied to global 137Cs fallout is widely usedmethod to assess soil redistribution rates within cultivated fields, but it requires decades to be
successfully implemented. The given approach hasn’t been used in areas with high level of Chernobylderived 137Cs initial fallout. The results of the first experience of re-sampling study within the small
agricultural catchment in Plavsk district of Tula region are presented. Statistically reliable changes in the137
Cs inventories for time window 1997 - 2023 were identified for the studied cultivated catchment. The
mean decrease in 137Cs inventories is about 11% for 26 years. The soil erosion rates determined based on
application of conversion models are in a good agreement with results of soil loss calculation using both
USLE and WATEM/SEDEM erosion models. The concentration of 137Cs in sediments re-deposited in dry
valley bottoms during the post-Chernobyl period experienced a sharp decrease in the first years after
Chernobyl-derived 137Cs initial fallout and then remains relatively stable with a smooth downward trend.
On average, the concentration decreased by at least more than two times.
Keywords： Chernobyl contamination, 137 Cs re-sampling technique, soil erosion, accumulation,
fluvial geomorphology

30

The 10th Annual Symposium of the IER, Fukushima University / 福島大学環境放射能研究所 第 10 回成果報告会

P-05
Tritium and aquatic living organisms: influence, transformation,
and accumulation
Lidiia BONDAREVA*1
Federal Scientific Center of Hygiene named after F.F. Erisman, Moscow region, Russia

1*Corresponding author： lydiabondareva@gmail.com

Tritium is a by-product of many radiochemical reactions in the nuclear industry, and its effects on waterorganisms, particularly low-dose effects, are worthy of special attention. In the past few decades, the lowdose effects of tritium on aquatic biota have been studied in detail using luminous marine bacteria asmodel microorganisms as well as during the transformation of fresh tritium water to organically boundtritium. Briefly, despite the low energy of tritium decay, its influence on living organisms in the water
environment may be considerable. The activation of aquatic plants’ functions in natural reservoirs, due tothe low tritium content, may result in unpredictable changes in food chains and an imbalance of naturalequilibria. These results confirm that during chronic interaction of tritium with aquatic plants, processes
occur associated with the intensive accumulation and retention of tritium in the biological structures ofliving organisms. The accumulation of tritium in the liver of fish occurs mainly due to the formation oforganically bound tritium, and, for the most part, these compounds are non-exchangeable. This leads tothe fact that the half-life of tritium in the liver is the longest and reaches 550 days.
Keywords： tritium, living organisms, water environments, organically bound tritium

31

The 10th Annual Symposium of the IER, Fukushima University / 福島大学環境放射能研究所 第 10 回成果報告会

P-06
Variations in 137Cs concentrations in river and coastal seawater
during high-flow events
WAKIYAMA Yoshifumi*1, SATOH Shun2, TAKATA Hyoe1, Pierre-Alexis CHABOCHE1,3,
KUROSAWA Honoka2
Institute of Environmental Radioactivity, Fukushima University, 2Graduate School of Symbiotic Systems Science

1and Technology, Fukushima University, 3Japan Society for the Promotion of Science*Corresponding author： wakiyama@ipc.fukushima-u.ac.jp

High-flow events can result in substantial 137Cs exportation via river to the ocean and increase 137Csconcentrations in coastal seawater. Assessing the linkage of 137Cs dynamics in river-coastal seawater will
help to better understand 137Cs transfer processes in terrestrial and marine environments. This study
discusses the detailed processes based on results of sample collections under various flow conditions on ariver system and its coastal seawater. During September 3-19（2023）, water samples were collected for 13
times at two downstream points of the Ukedo river system（Ukedo and Takase rivers）and 8 times onseashore around its river mouth. During the monitoring period, three high-flow events were observed due
to intensive rainfall. 137Cs concentrations in suspended solids at Ukedo and Takase rivers ranged from 7.0
to 67 kBq/kg and from 2.4 to 15 kBq/kg, respectively. The concentrations at peak water discharge phases
in Takase river were shown to be higher when ratio of rainfall amount on downstream parts to that onwhole catchments were high, but vice versa in the Ukedo river. Ａ high-flow event, associated with Senjokousuitai on September 8, exported substantial 137Cs to the ocean. In the seawater sample collected 5
hours after the peak water discharge, 137Cs concentrations reached 2.2 Bq/L of particulate, 0.4 Bq/L of
dissolved and 95 kBq/kg in suspended solids. All three concentrations decreased with time to reach thebackground levels in 10 days after the event. Updated results including analyses of unmeasured samples
will be presented in the symposium.
Keywords： coastal seawater, river, Senjo-kousuitai, suspended solids

出水時における河川と沿岸海水の137Cs濃度変動
脇山義史*1、佐藤俊2、高田兵衛1、ピエール−アレクシス・シャボシュ1,3、黒澤萌香2
福島大学環境放射能研究所、2福島大学大学院共生システム理工学研究科、3日本学術振興会

1*責任著者：wakiyama@ipc.fukushima-u.ac.jp

出水時には、河川から海洋に多量の137Csが流出し、沿岸海水の137Cs濃度を上昇させうることが知られている。
河川と沿岸海域における137Csの連動を明らかにすることで、陸域−海洋間の137Cs移行に関する理解の深化が期待される。本研究では、出水時を含む河川水および沿岸海水の分析結果を基に137Cs移行プロセスを検討する。2023年９月３日から19日にかけて、請戸川水系の２地点（請戸川および高瀬川）で各13回、河口周辺の海岸で８回の採水を行った。この期間には３回の出水イベントが観測された。懸濁物質の137Cs濃度は、請戸川で7.0〜67 kBq/kg、高瀬川で2.4〜15 kBq/kgであった。出水ピーク時の懸濁物質の137Cs濃度をみると、流域平均雨量に対して下流地点の雨量が相対的に多いときに高瀬川では高く、請戸川では低くなる傾向がみられた。９月８日の線状降水帯にともなう出水により多量の137Csが流出した。この出水ピークから５時間後に採取した沿岸海水試料では、懸濁態137Cs濃度が2.2 Bq/L、溶存態137Cs濃度が0.4 Bq/L、懸濁物質の137Cs濃度が95 kBq/kgに達した。いずれの濃度も時間経過とともに低下し、出水から10日後にはバックグラウンドレ
ベルとなった。成果報告会では、未測定試料の分析結果を含めて報告を行う。
キーワード：沿岸海水、河川、懸濁物質、線状降水帯

32

The 10th Annual Symposium of the IER, Fukushima University / 福島大学環境放射能研究所 第 10 回成果報告会

P-07
Long-term 137Cs dynamics after the decontamination at an urban
pond
KUROSAWA Honoka*1, NANBA Kenji2,3, WADA Toshihiro3, WAKIYAMA Yoshifumi3
Graduate School of Symbiotic Systems Science and Technology, Fukushima University, 2Faculty of Symbiotic

1

Systems Science, Fukushima University, 3Institute of Environmental Radioactivity, Fukushima University*Corresponding author： s2271004@ipc.fukushima-u.ac.jp

Relatively-high 137Cs concentrations in water bodies in urban pond and river were suggested, but only afew studies investigated 137Cs dynamics in urban area. This study presents long-term trends of 137Cs
dynamics in an urban pond after its decontamination and discussed the urban-specific processes. The
study site is an urban pond（surface area: 32,800 m2）in center of Koriyama City, Fukushima Prefecture,and it was decontaminated by bottom sediment removal in 2017. Bottom sediment, pond water, inflow
water and outflow water were collected from 2018 to 2022 and analyzed for 137Cs concentration, particle
size distribution and carbon-nitrogen stable isotope ratios. Annual mean values of total 137Cs concentrationin pond water decreased from 0.95 Bq/L in 2018 to 0.16 Bq/L in 2019 and comparable in following years.
The mean 137Cs concentration in SS in the inflow water was 5.7 kBq/kg, which was about three times
higher than those in the Abukuma River in corresponding years. After decontamination, the mean 137Cs
inventory in bottom sediment did not change（0.27-0.34 MBq/m2）, but its spatial variability got greater.
137
Cs concentration in bottom sediment showed a significant positive correlation with specific surface areaand δ15N. These results suggest that inflowed fine particles of urban origin with high 137Cs concentration
resulted in the greater spatial variability.
Keywords： 137Cs, pond, urban area, specific surface area, δ15N

都市域ため池における除染後の長期的な137Cs動態
黒澤萌香*1、難波謙二2,3、和田敏裕3、脇山義史3
福島大学大学院共生システム理工学研究科、2福島大学共生システム理工学類、3福島大学環境放射能研究所

1*責任著者：s2271004@ipc.fukushima-u.ac.jp

都市域では水圏の137Cs濃度が相対的に高いことが報告されているが、その137Cs動態を調べた研究は少ない。
本研究では、除染された都市域ため池において、長期的な137Cs動態を調べ、都市域の影響を検討した。調査地は福島県郡山市の市街地にある、2017年度に底質除去による除染が行われたため池（水面積32,800 m2）である。2018年から2022年にかけて、池水、流入水、流出水および底質を採集し、137Cs濃度、粒度分布、炭素
窒素安定同位体比を分析した。池水の全137Cs濃度の年平均値は、2018年には0.95 Bq/Lと高い値を示したが、2019年に0.16 Bq/Lまで低下し、以降同様の値を示した。流入水の懸濁物質の平均137Cs濃度は5.7 kBq/kgと、同時期における阿武隈川本流の値の約３倍の値であった。底質の平均137Csインベントリは0.27-0.34 MBq/m2の範囲で推移したが、時間経過とともに地点間差が大きくなった。また、底質の137Cs濃度は、比表面積、δ
15Nとの間に有意な正の相関を示しており、除染後に流入した細粒成分の沈降により137Csインベントリの空
間的ばらつきが大きくなったと考えられた。
キーワード：137Cs、ため池、都市域、比表面積、δ15N

33

The 10th Annual Symposium of the IER, Fukushima University / 福島大学環境放射能研究所 第 10 回成果報告会

P-08
Distribution of 137Cs concentrations in the urban hydrosphereSUZUKI Nobuhiro*1, WAKIYAMA Yoshifumi2, TAKATA Hyoe2, TAKASE Tsugiko3,
KUROSAWA Honoka1
Graduate School of Symbiotic Systems Science and Technology, Fukushima University, 2Institute of1

Environmental Radioactivity, Fukushima University, 3Faculty of Symbiotic Systems Science, Fukushima
University*Corresponding author： s2371007＠ipc.fukushima-u.ac.jp

The 137Cs concentrations of suspended solids and dissolved form in urban areas are higher than those inforests and agricultural lands, and it is possible that water quality conditions and causative agents uniqueto urban areas contribute to maintaining high137Cs concentrations. However, few studies have investigatedthe distribution of 137Cs concentrations in urban areas. In this study, water samples of 40 L each werecollected at 17 locations in Koriyama on August 30 and 31, 2023. Water samples were collected at sevenlocations along the Sakabutaike/Araike/Hagaike pathway, which is a small flow path across the central
area of the city, two locations along the Ouse River, four locations along the Minami River, two locations
along the Abukuma River, a major river, and two locations in the urban area. The 137Cs concentrations insuspended solids ranged from 0.5 to 5.4 kBg/kg and tended to be higher downstream than upstream in
all watersheds, ranging from 1.5 to 3.9 kBg/kg in the upper and lower reaches of the Ouse River. The
positive correlation between the 137Cs concentration in suspended solids and δ15N suggests that the 137Csconcentration increases as it passes through urban areas. In order to analyze the causative agent, image
analysis using imaging plates of suspended solids and elemental analysis of heavy metals and othersubstances are being conducted. The results of these analyses will be included in the report.
Keywords： irrigation pond, river, suspended solids, imaging plate

都市域の水圏における137Cs濃度分布
鈴木信弘*1、脇山義史2、高田兵衛2、高瀬つぎ子3、黒澤萌香1
福島大学大学院共生システム理工学研究科、2福島大学環境放射能研究所、3福島大学共生システム理工学類

1*責任著者：s2371007＠ipc.fukushima-u.ac.jp

都市域における懸濁態及び溶存態137Cs濃度は、森林・農地などに比べて高いという報告があり、都市に特有の水質条件や原因物質が137Cs濃度を高く維持させる要因になっている可能性がある。しかしながら、都市における137Cs濃度分布を調査した事例は少ない。本研究では、2023年８月30、31日に郡山の17か所で各40Lの採水を行った。採水個所は、市街地中心域を横断する少量流動経路である酒蓋池/荒池/芳賀池経路７か所、ため池がない河川である逢瀬川２か所、流域にため池がある南川４か所、主要河川の阿武隈川２か所、及び市街地内２か所で行った。懸濁態137Cs濃度は、0.004～0.5 Bq/L、溶存態137Cs濃度は、0.003～0.03 Bq/Lであった。懸濁物質の137Cs濃度は、0.5～5.4 kBg/kgの範囲を示し、阿武隈川上下流で0.5から1.1 kBg/kg、逢瀬川
上下流で1.5から3.9 kBg/kgとなるなどいずれの流域でも上流より下流の方が137Cs濃度が高くなる傾向が見られた。また、懸濁物質の137Cs濃度とδ15Nが正の相関を示すことから、都市域を通過することで、137Cs濃度が高くなることが示唆された。原因物質の解析のため、懸濁物質のイメージングプレートによる画像解析、及び重金属等物質の元素分析を行っている。報告会ではこれらの分析結果を含めて報告する。
キーワード：ため池、河川、懸濁物質、イメージングプレート

34

The 10th Annual Symposium of the IER, Fukushima University / 福島大学環境放射能研究所 第 10 回成果報告会

P-09
Spatial pattern of water chemistry including radiocesium
concentration in Arakawa River, Fukushima Prefecture
IGARASHI Yasunori*1, FUKUSHIMA Keitaro*2,3, SAITO Asuka3
Institute of Environmental Radioactivity, Fukushima University, 2Graduate School of Food and Agricultural

1

Sciences, Fukushima University, 3Faculty of Food and Agricultural Sciences, Fukushima University*Corresponding author： y-igarashi@ipc.fukushima-u.ac.jp, fmktaro@agri.fukushima-u.ac.jp

The Arakawa River, which is one of the major tributaries of the Abukuma River, flows throughFukushima City, Fukushima Prefecture, and has been selected as the “river with the best water quality
in Japan” by Ministry of Land, Infrastructure, Transport, and Tourism（MLIT）for 13 consecutive years.
However, it is unknown why the water chemistry meets the standard value（COD）in this river. Our aimof this study is to clarify the spatial pattern and determining factors of river water chemistry. We
investigated spatial variations of river water chemistry including pH, concentrations of major cations andanions including ammonium, nitrate and phosphate, and suspended sediments as well as dissolved andparticulate 137Cs concentrations in June and October 2023. We found（1）pH decreased considerably inthe middle reaches of Arakawa River because of the mixing of strongly acidic tributary originating fromthe volcano,（2）precipitation of some heavy metals on the riverbed due to neutralizing strongly acidic
tributary river by neutral main river. This process forms an environment unfavorable for aquatic livings,
which is one of the possible factors in meeting the water standard by MLIT. We will report the spatial
variations of dissolved and particulate 137Cs in this river system, and discuss the factors determining thevariations of river water chemistry.
Keywords： spatial pattern, water chemistry, 137Cs in river

福島市内を流れる荒川の水質形成機構と137Cs流出の実態
五十嵐康記*1、福島慶太郎*2,3、斎藤あすか3
福島大学環境放射能研究所、2福島大学食農学研究科、3福島大学食農学類

1*責任著者：y-igarashi@ipc.fukushima-u.ac.jp、fmktaro@agri.fukushima-u.ac.jp

福島県福島市を流れる阿武隈川水系の一級河川・荒川は、国土交通省による「水質が最も良好な河川」に13年連続選出されている。しかしながら、その水質形成プロセスについて明らかではない。そこで本研究では、
荒川の水質の空間パターンと、水質を決定する要因を明らかにすることを目的とした。目的の達成のため、2023年６月と10月に荒川・松川・油井川を対象に広域的な採水と化学分析を行った。松川・油井川を対象に含めた意図は、酸性が強いと考えられた荒川との比較のためである。本研究では、溶存態及び懸濁態137Csについても調査を行い、福島第一原発事故から12年経過した現在の実態について、水質形成プロセスと関連付けることも本研究の狙いの一つとした。広域採水の結果，荒川中流付近で火山に由来する強酸性の支流河川・須川が合流することで荒川のpHが低下すること、一方で須川のpHが上昇することで溶存していた一部の重金属イオンが荒川河床に沈殿することが観察された。このことから、生物が生息しにくい環境が形成され、国土交通省の水質基準を満たしていることが推察された。本発表では，溶存態及び懸濁態137Csの広域調査の結果を合わせて、荒川の水質形成について考察する。
キーワード：空間パターン、水質、河川中の137Cs

35

The 10th Annual Symposium of the IER, Fukushima University / 福島大学環境放射能研究所 第 10 回成果報告会

P-10
Relationship between 137Cs concentration in water and Japanesedace（Pseudaspius hakonensis）in lakes in Fukushima Prefecture
INOMATA Ayame*1, TAKASAKI Kazuyoshi2, TOMIYA Atsushi3, ENOMOTO Masahiro2,
FUNAKI Yuto4, SHIMAMURA Shinya1, WADA Toshihiro5
Fukushima Prefectural Inland Water Fisheries Experiment Station, 2Fukushima Prefectural Fisheries and Marine

1

Science Research Centre, 3Fukushima Prefectural Fisheries Office, 4Fukushima Prefectural Fisheries Resources
Research Institute, 5Institute of Environmental Radioactivity, Fukushima University*Corresponding author： inomata_ayame_01@pref.fukushima.lg.jp

After the Fukushima Daiichi Nuclear Power Plant accident, some fish species that exceeded theregulatory limit of radiocesium（100 Bq/kg-wet）have still been found in some rivers and lakes inFukushima Prefecture. In order to obtain a forecast of future 137Cs contamination, it is necessary to
elucidate the transfer and accumulation mechanisms of 137Cs within the inland water ecosystem. In thisstudy, in order to understand the transfer and accumulation status of 137Cs from lake water to fish, we
compared the ecological half-lives of Japanese dace（< 20 cm total length）and concentration ratios of137
Cs from water（dissolved form）to fish in 5 lakes in Fukushima Prefecture. The results showed thatthe ecological half-lives and concentration ratios differed depending on the lakes, and it was considerednecessary to examine the transfer and accumulation process of 137Cs from lake water to Japanese dacefor each lake.
Keywords： Japanese dace, lake water, ¹³⁷Cs, ecological half-life, concentration ratio

福島県内湖沼における湖水とウグイの137Cs濃度の関係
猪俣絢女*1、鷹﨑和義2、冨谷敦3、榎本昌宏2、舟木優斗4、島村信也1、和田敏裕5
福島県内水面水産試験場、2福島県水産海洋研究センター、3福島県水産事務所、4福島県水産資源研究所、

1

福島大学環境放射能研究所

5*責任著者：inomata_ayame_01@pref.fukushima.lg.jp

福島第一原発の事故後、本県の一部の河川・湖沼では未だ137Cs濃度が国の基準値を超える魚種が確認されている。今後の137Csによる汚染の見通しを得るためには、内水面生態系内での137Csの移行・蓄積状況を把握することが必要である。本研究では、湖水から魚類への137Csの移行・蓄積状況を把握するため、県内５湖沼を対象に、全長20cm未満のウグイの生態学的半減期及び湖水溶存態と魚体の137Cs濃度の濃度比を比較した。
その結果、生態学的半減期・濃縮係数は湖沼によって異なることが示され、湖水からウグイへの137Csの移行・蓄積状況は湖沼ごとに検討することが必要であると考えられた。
キーワード：ウグイ、湖水、137Cs、生態学的半減期、濃縮係数

36The 10th Annual Symposium of the IER, Fukushima University / 福島大学環境放射能研究所 第 10 回成果報告会

P-11
Voluntary inspection results of radioactive Cs concentration ofmarine products in Fukushima and examples of voluntary shipping
restrictions
TAKASAKI Kazuyoshi*1
Fukushima Prefectural Fisheries and Marine Science Research Centre

1*Corresponding author： takasaki_kazuyoshi_01@pref.fukushima.lg.jp

Fukushima Prefectural Fisheries Cooperative Association（FPFCA）has been conducting screening forradioactive Cs concentration on all fish species before shipping the catch since June 2012. If the screeningshows that the fish exceeds 25 Bq/kg, the shipment of the relevant fish species will be temporarilysuspended and undergo a detailed inspection by Fukushima Prefecture, and if the test exceeds 50 Bq/kg,
the shipment and operation will be suspended until safety is confirmed. The number of samples forvoluntary testing was 104,599, which was higher than the number of samples for emergency monitoring
by Fukushima Prefecture（77,079, for seafood）until September 2023. In addition, there were 20 cases of
temporary suspension of shipments and 13 cases of voluntary restraint of shipments and operation. Fiveof the cases of voluntary restraint on shipments and operation were taken based on measurements
exceeding 50 Bq/kg other than screening inspections. Based on the above, it can be said that FPFCA isextremely careful in handling shipments of marine products while confirming safety using a huge amountof data.
Keywords： radioactive Cs, self-inspection（screening）,self-restraint in shipping

福島県産水産物の放射性Cs濃度の自主検査結果及び出荷自粛事例
鷹﨑和義*1
福島県水産海洋研究センター

1*責任著者：takasaki_kazuyoshi_01@pref.fukushima.lg.jp

福島県漁業協同組合連合会（県漁連）は、2012年６月から、漁獲物を出荷する前に全魚種を対象として放射性
Cs濃度のスクリーニングを自主的に実施している。自主検査で25 Bq/kgを超過した場合は当該魚種の出荷を一時停止して福島県の精密検査を受け、精密検査で50 Bq/kgを超過した場合は安全性が確認されるまで
出荷・操業を自粛することとしている。2023年２月の自主検査及び精密検査で50 Bq/kgを超過するスズキが確認され、県漁連は３月末までスズキの出荷・操業を自粛した。本研究では、2023年９月までの自主検査
結果及び出荷自粛事例を整理して、これまでの取組の評価と今後の課題の抽出を目的とした。
自主検査の検体数は104,599で、福島県の緊急時モニタリングの検体数（77,079、水産物対象）よりも多かった。
また、出荷自粛事例は、出荷一時停止が20件、出荷・操業自粛が13件の合計33件であり、後者のうち５件は、自主検査以外（福島県のモニタリング結果等）における50 Bq/kg超過を踏まえた措置であった。以上のこと
から、県漁連は、膨大な量のデータを用いて安全性を確認しながら、水産物を極めて慎重に出荷していると言える。また、出荷自粛事例が多かった魚種はスズキ（５回）、クロソイ（３回）であり、今後、これらの魚種で25 Bq/kgを超える個体が出現する原因を解明する必要がある。
キーワード：放射性Cs、自主検査（スクリーニング）、出荷自粛

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The 10th Annual Symposium of the IER, Fukushima University / 福島大学環境放射能研究所 第 10 回成果報告会

P-12
Impacts of wildfire on desorption of radionuclide and subsequentwash-offs in the Chornobyl Exclusion Zone
IGARASHI Yasunori*1, Valentyn PROTSAK2, Gennady LAPTEV2, Igor MALOSHTAN2,
Dmitry SAMOILOV3, Serhii KIRIEIEV3, ONDA Yuichi4, Alexei KONOPLEV1
Institute of Environmental Radioactivity, Fukushima University, 2Ukrainian Hydrometeorological Institute,

1

National Academy of Sciences of Ukraine, 3Chernobyl Ecocentre, State Agency of Ukraine on Exclusion Zone
Management, 4Center for Research in Radiation, Isotopes, and Earth System Sciences, University of Tsukuba*Corresponding author： y-igarashi@ipc.fukushima-u.ac.jp

The objective of this study is to determine the speciation of 137Cs and 90Sr in the ash and soil. And toreveal the impact of the wildfires on concentrations of 137Cs and 90Sr in river water in Chornobyl. To
accomplish this objective, extraction tests were conducted using ash and soil samples collected
immediately after the 2020 fires to determine the water-soluble and exchangeable fractions of 137Cs and90
Sr in the ash and soil. Long-term river-water radionuclide concentration records were also analyzed.
The results showed that the solid–liquid distribution coefficient（Kd）of ash was significantly lower thanthat of soil for 137Cs, while for 90Sr there was no significant difference in Kd between ash and soil. Analysis
of river water data indicated that 90Sr concentrations higher than the Ukrainian drinking water standard（> 2 Bq/L）were observed more frequently following wildfires in the Sakhan River. The fires increased90
Sr concentrations over the following two years, particularly in the spring, when snowmelt causes
substantial releases, and in the summer and autumn, when surface flows occurred. High 90 Srconcentrations were observed only within the Chornobyl Exclusion Zone, so additional human uptake ofor dose exposure to 90Sr from river water is not expected.
Keywords： wildfire, desorption, radionuclide, wash-offs, Chornobyl

チョルノービリにおける山火事は放射性核種の溶出とその後の流出にどのような影響を与えるのか？
五十嵐康記*1、バレンティン・プロサック2、ゲナディー・ラプテフ2、イーゴリ・マロシュタン2、
ドミトリー・サモイロフ3、セルヒー・キリエフ3、恩田裕一4、アレクセイ・コノプリョフ1
福島大学環境放射能研究所、2ウクライナ水文気象研究所、3チョルノービリエコセンター、4筑波大学放射線・アイ

1

ソトープ地球システム研究センター*責任著者：y-igarashi@ipc.fukushima-u.ac.jp

本研究の目的は、灰と土壌中に含まれる137Csと90Srの存在形態を明らかにし、チョルノービリの河川水中の137
Csと90Sr濃度に対する森林火災の影響を明らかにすることである。この目的を達成するため、2020年の火災直後に採取された灰と土壌試料を用いて抽出試験を行い、灰と土壌中の137Csと90Srの水溶性画分と交換性
画分を測定した。また、長期にわたる河川水の放射性核種濃度の記録も分析した。その結果、137Csについて
は、灰の固液分配係数（Kd）が土壌のそれよりも有意に低かったが、90Srについては、灰と土壌の間でKdに有意差はなかった。河川水データの分析から、サハン川流域での森林火災の後、ウクライナの飲料水基準（>
２ Bq/L）より高い90Sr濃度がより頻繁に観測されることが示された。この火災は、その後の２年間、特に雪解け水が大量に放出される春と、地表流が発生する夏と秋に90Sr濃度を上昇さることがわかった。しかしながら、高濃度の90Srが観測されたのはチョルノービリ規制区域内だけであり、河川水からの90Srの人体への取り込みや被曝は予想されなかった。
キーワード：山火事、溶出、放射性核種、流出、チョルノービリ

38

The 10th Annual Symposium of the IER, Fukushima University / 福島大学環境放射能研究所 第 10 回成果報告会

P-13
Consecutive sexual maturation observed in a rock shell populationin the vicinity of the Fukushima Daiichi Nuclear Power Plant,
Japan
HORIGUCHI Toshihiro*1, ARAMAKI Takafumi1, NAKAJIMA Daisuke1, KODAMA Keita1,
KINTSU Hiroyuki1, MORISHITA Fumihiro2
National Institute for Environmental Studies, 2Graduate School of Integrated Sciences for Life, Hiroshima

1

University*Corresponding author： thorigu@nies.go.jp

In 2012, after the accident at the Fukushima Daiichi Nuclear Power Plant（FDNPP）that followed the
Tohoku earthquake and tsunami in March 2011, no rock shell（Reishia clavigera; Gastropoda）specimens
were found near the plant from Hirono to Futaba Beach（a distance of approximately 30 km）. In July
2016, however, rock shells were again found to inhabit the area. From April 2017 to May 2019, wecollected rock shell specimens monthly at a site near the FDNPP（Okuma）and at a reference site ~ 120
km south of the FDNPP（Hiraiso）. We examined the gonads of the specimens histologically to evaluate
their reproductive cycle and sexual maturation. The gonads of the rock shells collected at Okuma, ~ 1 km
south of the FDNPP, exhibited consecutive sexual maturation（CSM）during the 2 years from April 2017
to May 2019, whereas sexual maturation of the gonads of specimens collected at Hiraiso was observed
only in summer. The CSM of the gonads of the specimens collected at Okuma might not represent a
temporary phenomenon but rather a site-specific phenotype, possibly caused by specific environmental
factors near the FDNPP. Here, we will show results from the following field surveys, regarding durationand geographical range when and where CSM has been observed, possible recovery from CSM if therock shells are kept in the laboratory（under different circumstances from the site near FDNPP）,
concentrations of tritium and other chemical substances in seawater close to FDNPP, to discuss about thecausal factor（s）and induction mechanism for CSM in the rock shell.
Keywords：Fukushima Daiichi Nuclear Power Plant, rock shell, ecological effects, consecutive sexual maturation

福島第一原子力発電所近傍の肉食性巻貝イボニシにみられる生殖異常：通年成熟現象
堀口敏宏*1、荒巻能史1、中島大介1、児玉圭太1、近都浩之1、森下文浩2
国立環境研究所、2広島大学大学院統合生命科学研究科

1*責任著者：thorigu@nies.go.jp

演者らは、2011年12月14日以降、福島第一原子力発電所（1F）近傍で潮間帯調査を継続してきた。震災・原発事故後に姿を消したイボニシが2016年７月に大熊町夫沢（1Fの南側約１km）で初めて観察され、イボニシの“空白地帯”が消失したため、2017年４月以降、大熊町夫沢でイボニシの性成熟や産卵行動等に関する調査を毎月進めてきた。その結果、大熊町夫沢のイボニシは2019年５月まで２年以上に亘って性的に成熟した状態が継続していること（通年成熟現象）が明らかになった。イボニシは、本来、年１回、夏季に性成熟することが知られており、通年成熟現象は異常である。ここでは、その後、現在までの調査によって明らかになった、通年成熟現象の継続期間、通年成熟現象が観察される地理的範囲、棲息環境が変われば通年成熟は停止
もしくは軽減するか、通年成熟個体に何らかの生理学的変化が生じているか、などの知見を現地の海水の化学分析結果も交えながら紹介し、通年成熟現象の原因とメカニズムを考察する。
キーワード：福島第一原子力発電所、イボニシ Reishia clavigera、生態影響、通年成熟
39

The 10th Annual Symposium of the IER, Fukushima University / 福島大学環境放射能研究所 第 10 回成果報告会

P-14
Testing new methods to reduce 137Cs and 90Sr contamination of
freshwater fish
Polina PAVLENKO*1,4, WADA Toshihiro3, Vasyl YOSCHENKO3, Valery KASHPAROV1,2
Ukrainian Institute of Agricultural Radiology of National University of Life and Environmental Sciences of1

Ukraine, 2Norwegian University of Life Sciences, Norway, 3Institute of Environmental Radioactivity, Fukushima
University, 4Graduate School of Symbiotic Systems Science and Technology, Fukushima University*Corresponding author： polina.pavlenko97@gmail.com

Recently, series of experiments testing new methods to reduce radioactive contamination of freshwater
fish with 137Cs and 90Sr were conducted in natural conditions of Chornobyl exclusion zone along withexperiments in laboratory conditions. The methods tested included feeding fish diets supplemented with
Prussian blue in the form of potassium ferric hexacyanoferrate（KFCF）KFe[Fe（ CN）6], keeping
radioactively contaminated fish in "clean" water, and culinary treatment（boiling）of bones and flesh
tissues of radioactively contaminated fish.
The experiments carried out in Chornobyl Exclusion Zone showed a significant difference in the activity
concentration of 137Cs in the muscle tissue of fish fed with KFCF compared to fish without clean feeding.
Depending on the level of KFCF in the feed, the activity concentration of 137Cs in muscle tissue was
reduced by a factor of 7-27. On the contrary, keeping fish in "clean" water did not show the expected
decrease of 90Sr in muscle and bone tissues of fish. Further research is needed to investigate the longterm behavior of strontium in fish tissues. A culinary treatment experiment showed that it is appropriate
to establish permissible levels of 90Sr only in the flesh of the fish, as the processing retention factors of90
Sr during cooking of broth from bone tissue of fish from the contaminated lake within Chornobyl
Exclusion Zone were less than 0.01.
Keywords： 137Cs, 90Sr, countermeasures, Chornobyl Exclusion Zone

40

The 10th Annual Symposium of the IER, Fukushima University / 福島大学環境放射能研究所 第 10 回成果報告会

P-15
Combined remote sensing and modelling of the state of Chornobyl
forests in terms of productivity, radioactive contamination, andeconomic use
Dmytrii HOLIAKA*1, Valeriia MOROZOVA1, Roman ZADOROZHNIUK1, Vasyl YOSCHENKO2,
Sviatoslav LEVCHUK1, Jim T. SMITH3, Nicholas A. BERESFORD4, Oleksii KIVA5,
Hans Christoffer TYLDUM6, Deborah H. OUGHTON6, Maryna HOLIAKA1, IGARASHI Yasunori2,
Oleksandr-Ralf CHERNIAIEV1, Oleksandr LESNIK1, Ihor CHYZHEVSKYI7, KATO Hiroaki8,
Petro DIACHUK9, NANBA Kenji2, ONDA Yuichi8, Valery KASHPAROV1National University of Life and Environmental Sciences of Ukraine, 2Institute of Environmental Radioactivity,

1

Fukushima University, 3University of Portsmouth, 4UK Centre for Ecology and Hydrology Lancaster, 5Kyiv
Academic University, 6Norwegian University of Life Sciences, 7State Specialized Enterprise "Ecocentre", 8Center
for Research in Radiation, Isotopes, and Earth System Sciences, University of Tsukuba, 9Polissia National
University*Corresponding author： holiaka@nubip.edu.ua

The Chornobyl Exclusion Zone has not only a highly radioactive contamination, but, since 2022, it has also
become one of the areas in the world with the highest density of land mines. Therefore, forestry activities
are often impossible within this area, making development of remote sensing methods of forestry
resources essential. This study presents a comprehensive assessment of the economic value（growing
stock）, ecosystem services（biomass）, and radioecological parameters（90Sr and 137Cs contents in wood）of
the Chornobyl forests. Different approaches using data from terrestrial field measurements, Unmanned
Aerial Vehicle（UAV）aerial photography, and satellite images（Sentinel-1 and 2）, were implemented
with further comparison of their output results. The XGBoost algorithm was carried out to simulate thelisted parameters. Although remote methods of estimating the studied parameters were significantly lessaccurate than those based on terrestrial field measurements, estimating growing stock and biomass basedon the UAV surveys demonstrated a high explanatory ability（confidence interval for R2 was［0.87;
0.95］）. However, the models created for determining the 90Sr and 137Cs concentrations in wood based on
UAV data were unreliable. Satellite data enabled the generation of statistically significant predictions forall studied parameters： growing stock（R2［0.50–0.69］）, aboveground biomass of tree stand（R2［0.45–
0.71］）, and aggregated transfer factor coefficients for 90Sr（R2［0.17–0.37］）and 137Cs（R2［0.23–0.39］）from
soil into trunk wood.
Keywords： Chornobyl forest, XGBoost, UAV, satellite data, radionuclides, biomass

41

The 10th Annual Symposium of the IER, Fukushima University / 福島大学環境放射能研究所 第 10 回成果報告会

P-16
Assessment of the effects of ionizing radiation in bees – BEERAD
Béatrice GAGNAIRE*1, NANBA Kenji2, Jean-Marc BONZOM1, Jean-Luc BRUNET3, Margot CREVET1,
Nicolas DUBOURG1, ISHINIWA Hiroko2, NAGATA Hiroko2, Michel PELISSIER3, Luc BELZUNCES3
Institute for Radiation Protection and Nuclear Safety, France, 2Institute of Environmental Radioactivity,

1

Fukushima University, 3National Research Institute for Agriculture, Food and the Environment, France*Corresponding author： beatrice.gagnaire@irsn.fr

The risk assessment linked to the radiocontamination of the environment after a nuclear accident is amajor ecological issue. However, it is still surrounded by controversial results and conclusions on the real
impact of such events on flora and fauna inhabiting the targeted zones. Moreover, the potential
underlying mechanisms of the action of ionizing radiation（IR）are poorly known. Therefore, it isimportant to acquire data on the potential effects of IR on ecosystems both in experimental and realistic
conditions. The objective of the BEERAD project is, using a pluri-disciplinary approach, to increase theknowledge of effects and mechanisms of action of IR on physiology and populations of honeybees in thecontext of chronic exposure（i.e., exposure of a significant period of time relative to the lifespan of
exposed organisms）and at low dose rates（sublethal ecotoxicity）in realistic conditions, i.e., on the field
and in the laboratory. However, very few data exist on this subject, and it seems important to conduct
studies that will serve as a basis to better evaluate the impacts of IR on animal health using honeybees.
The presentation will focus on the experiment of implantation of hives realized around the Fukushima
Nuclear Power Plant from April to October 2023.
Keywords： ionizing radiation, honeybee Apis mellifera, physiology, biomarkers, Fukushima NPP

42

The 10th Annual Symposium of the IER, Fukushima University / 福島大学環境放射能研究所 第 10 回成果報告会

P-17
Soil biodiversity and functional processes in radio-contaminatedforests（Fukushima Prefecture, Japan）
Quentin LAMBERT1, Olivier ARMANT1, Anne-Sophie BENOISTON2, Yvan CAPOWIEZ3,Stephan HÄTTENSCHWILER4, Amaia IRIBAR-PELOZUELO2, KANEKO Nobuhiro5, Sylvain LAMOTHE2,
NANBA Kenji6, Vasyl YOSCHENKO6, WADA Toshihiro6, Jean-Marc BONZOM1, Franck GILBERT*2
Institute for Radiation Protection and Nuclear Safety, France, 2Centre de Recherche sur la Biodiversité et1

l'Environnement, France, 3National Research Institute for Agriculture, Food and the Environment, France,
Centre d'Ecologie Fonctionnelle et Evolutive, France, 5Faculty of Food and Agricultural Sciences, Fukushima

4

University, 6Institute of Environmental Radioactivity, Fukushima University*Corresponding author： franck.gilbert@univ-tlse3.fr

The objectives of the collaborative French-Japanese RINSHŌ project are to study the in situ effects ofradio-contamination on both soil biodiversity（microorganisms and eukaryotes）and two associatedfunctional processes: leaf litter decomposition and soil bioturbation, in forests of Fukushima Prefecture（representing approximately 70% of the total radio-contaminated land area）. Indeed, those two
integrative processes are specifically investigated because they are related to the transfer and thetransformation of organic matter and are carried out by interacting organisms belonging to various soil
biological compartments and ecological niches（from bacteria to macrofauna, epifauna and endofauna）.
Our hypotheses are:（i）radio-contamination has an impact on soil biodiversity,（ii）radio-contamination
has an impact on the activity of soil organisms and the processes they drive,（iii）the impact of radiocontamination is dose-dependent.
In the November-December 2023 period, 6 Cryptomeria japonica forest sites of Fukushima Prefecture
positioned along a radio-contamination gradient were equipped with experimental units（5 units per site）.
These units were composed, among other devices, of: fine and large mesh C. japonica litter bags; deposition
zones of fluorescent tracers（luminophores）; TMS-4 TMOS dataloggers; dosimeter columns. Samplings
for both eDNA（bacteria and eukaryotes compartments）and physico-chemical analyses of soils and litter
were also realized.
Collection of experimental devices and complementary samplings will be carried out after 6 and 12
months of experimentation.
Keywords： Fukushima Prefecture, ionizing radiation, forest, soil communities, functional processes

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The 10th Annual Symposium of the IER, Fukushima University / 福島大学環境放射能研究所 第 10 回成果報告会

P-18
Long-term transfer of radiocesium by hydrological processes
within forest following Fukushima Dai-ichi Nuclear Power Plant
accident
KATO Hiroaki*1, NIWANO Yuma1, ONDA Yuichi1
Center for Research in Radiation, Isotopes, and Earth System Sciences, University of Tsukuba

1*Corresponding author： kato.hiroaki.ka@u.tsukuba.ac.jp

Over 12 years of rigorous field data collection following the Fukushima Daiichi Nuclear Power Plant
accident, we provide insights into the distribution and migration of radiocesium in Japanese forests. Ourfindings highlight the intricate mechanisms governing radiocesium transfer between the atmosphere,
canopy, and soil, driven by hydrological processes and forest headwater catchment discharge. Based on
extensive field monitoring in experimental forest regions and watersheds in Fukushima Prefecture's
Kawamata and Namie towns, we uncover key differences in radionuclide transfer rates between
Fukushima and Chornobyl, synthesizing previous research. Our study sheds light on transfer phenomena
within forests with potential long-term implications for radionuclide distribution, offering critical insights
for environmental management and future research.
Keywords： Fukushima Dai-ichi NPP accident, radiocesium, forest, distribution, transfer mechanisms

福島第一原子力発電所事故後の森林内における水文学的過程による放射性セシウムの長期移行
加藤弘亮*1、庭野佑真1、恩田裕一1
筑波大学放射線・アイソトープ地球システム研究センター

1*責任著者：kato.hiroaki.ka@u.tsukuba.ac.jp

東京電力福島第一原子力発電所の事故後、12年にわたる厳密なフィールドデータ収集の結果、日本の森林における放射性セシウムの分布と移動に関する知見が得られた。その結果、水文学的プロセスと森林源流域から流出プロセスにともなう、大気、樹冠、土壌間の放射性セシウム移行を支配する複雑なメカニズムが明らかになった。福島県川俣町と浪江町の調査林分と試験流域における広範なフィールドモニタリングに基づき、福島とチョルノービリにおける放射性核種の移行率の重要な違いを明らかにし、これまでの研究を総合した。
本研究は、放射性核種の分布に長期的な影響を及ぼす可能性のある森林内の移行現象に光を当て、環境管理と今後の研究に重要な洞察を提供する。
キーワード：福島第一原子力発電所事故、放射性セシウム、森林、分布、移行メカニズム

44

The 10th Annual Symposium of the IER, Fukushima University / 福島大学環境放射能研究所 第 10 回成果報告会

P-19
Effects of downward migration of Cs-137 on its concentration infine roots of Japanese cedar in Fukushima
TAKAHASHI Junko*1, SASAKI Takuya1, IGUCHI Satoshi1, ONDA Yuichi1
Center for Research in Radiation, Isotopes, and Earth System Sciences, University of Tsukuba

1*Corresponding author： takahashi.junko.ka@u.tsukuba.ac.jp

Radiocesium（Cs-137）deposited on forests was intercepted by the canopy, then migrated to the litter
layer and eventually to the soil layer, where some of it has been absorbed by roots and circulated
through the forest ecosystem for a long time. In other words, the amount of Cs-137 uptake by roots willcontrol the long-term dynamics in the forest ecosystem in the future, temporal changes in Cs-137 in treeroots have rarely been reported. In this study, we investigated the Cs-137 concentration and inventory inthe soil and very fine（VF）roots（< 0.5 mm）of Japanese cedar from 2011 to 2020.
The Cs-137 inventory in the soil increased over time due to the migration from the forest canopy andlitter layers, whereas that in the VF roots decreased in 2020. Especially, the Cs-137 inventory in the VFroots in the 0-2 cm of soil reached 89% in 2012; however, it decreased with time to approximately 43% in
2020. It was concluded that the downward migration of Cs-137 in the litter and soil layers caused a shift
in the peak of depth distribution of Cs-137 in the soil from the peak of depth distribution of VF root
biomass and reduced root uptake. This natural downward migration process can be regarded as a “selfcleaning” of the forest ecosystem, resulting in a decrease in the air dose rate and the amount of Cs-137
absorbed by roots.
Keywords： tree root, forest soil, Cs-137, downward migration, self-cleaning

スギ林細根中のCs-137濃度に対するCs-137下方移行の影響
高橋純子*1、佐々木拓哉1、井口啓1、恩田裕一1
筑波大学放射線・アイソトープ地球システム研究センター

1*責任著者： takahashi.junko.ka@u.tsukuba.ac.jp

森林に沈着した放射性セシウム（Cs-137）は、樹冠によって遮断され、降雨やリターフォールを通じて徐々にリター層、そして最終的には土壌層へと移行し、その一部は根に吸収され、長期間にわたって森林生態系を循環する。言い換えれば、根によるCs-137の吸収量が今後の森林生態系の長期的な動態を支配することにな
るが、樹木の根におけるCs-137の時間的な変化はほとんど報告されていない。本研究では、2011年から2020
年にかけて、スギの土壌およびVery Fine（VF）根（< 0.5 mm）中のCs-137濃度とインベントリーを調査した。
土壌中のCs-137インベントリーは、樹冠やリター層からの下方移行により時間とともに増加したが、VF根
中のCs-137インベントリーは2020年には減少した。特に、土壌0-2 cmのVF根中のCs-137インベントリーは2012年に89%に達したが、時間とともに減少し、2020年には約43%になった。リター層および土壌中のCs137の下方移行により、土壌中のCs-137深度分布のピークがVF根のバイオマスの深度分布のピークからずれることで根による吸収量が減少したと考えられた。すなわち、除染によってCs-137を除去せずとも、下方移行の促進によって空間線量率の低下と吸収量の減少というself-cleaningが期待できる。
キーワード：樹木根、森林土壌、Cs-137、下方移行、セルフクリーニング

45

The 10th Annual Symposium of the IER, Fukushima University / 福島大学環境放射能研究所 第 10 回成果報告会

P-20
Evaluation of radiocesium uptake from food and water by starry
flounder, an euryhaline fish, under different salinity conditions
MANOME Yuuki*1, WADA Toshihiro1,2
Graduate School of Symbiotic Systems Science and Technology, Fukushima University, 2Institute of1

Environmental Radioactivity, Fukushima University*Corresponding author： s2270055@ipc.fukushima-u.ac.jp

Fish uptake radiocesium from two routes: food and water. Freshwater fish have been contaminated by137
Cs for a longer period than marine fish after the Fukushima Daiichi Nuclear Powar Plant accident.
Based on the above, we first conducted rearing experiments that evaluated 137Cs uptake from food bystarry flounder, an euryhaline fish, under different salinity conditions（freshwater, brackish water, andseawater）. Results reported at the IER Annual Symposium last year showed that the 137Cs uptake fromfood was faster in freshwater or brackish water than in seawater. Then, we conducted a rearing
experiment that can evaluate 137Cs uptake from water under different salinity conditions using the same
species. The obtained results revealed that the 137Cs uptake in seawater is faster than that in freshwateror brackish water: the opposite results of 137Cs uptake from food. Factors influencing these results may
include（1）large differences in K concentrations between freshwater and seawater and（2）thedifferences in osmoregulatory physiology in fish. These findings clearly represent a fundamental andimportant physiological mechanism that can explain the different radiocesium decreasing trends infreshwater and marine fish after the Fukushima accident.
Keywords： fish, radiocesium, salinity, ecological half-life, bioaccumulation, rearing experiment

広塩性魚ヌマガレイを用いた異なる塩分条件下における餌および水からの放射性セシウム取込評価
馬目由季*1、和田敏裕1,2
福島大学共生システム理工学研究科、2福島大学環境放射能研究所

1*責任著者：s2270055@ipc.fukushima-u.ac.jp

魚類は、餌生物と環境水の２つの経路から放射性Csを取込む。魚類の生体内において、Csは同じアルカリ金属元素のKと同じような挙動を示すため、K濃度が大きく異なる淡水と海水では、餌と水でCsの取込や排出に関わるメカニズムが異なると予想される。実際、福島原発事故後、淡水魚は海水魚に比べ放射性Csによる汚染が長期化している。以上を踏まえ、まず、広塩性魚ヌマガレイを対象に、異なる塩分条件下（淡水、汽水、海水）での餌からの放射性Cs取込試験を行った。その結果、餌からの取込は海水よりも淡水で早いことが明らかとなった（第９回IER成果報告会で報告）。そこで次に、同種を対象に、異なる塩分濃度条件下での水からの放射性Csの取込試験を行った。その結果、海水における放射性Csの取込が、淡水・汽水よりも早いことを同一魚種の飼育試験により初めて解明した。今回得られた水からの放射性Csの取込結果は、昨年報告した餌からの放射性Csの取込結果と真逆であった。これらに影響を及ぼす要因として、（１）淡水と海水におけるK濃度の大きな違いや（２）魚類の浸透圧調節に関わる生理的機能の違いが考えられる。本知見は、福島第一原発事故後の淡水魚と海水魚の放射性セシウム汚染の推移を説明する上で、根本的かつ重要な生理的メカニズムを示していると考えられる。
キーワード：魚類、放射性Cs、塩分濃度、生物学的半減期、生物蓄積、飼育46

The 10th Annual Symposium of the IER, Fukushima University / 福島大学環境放射能研究所 第 10 回成果報告会

P-21
Distribution of radioactive cesium-rich microparticles in forest
soils at difficult-to-return zone
WAKI Hiromichi*1, TATSUNO Takahiro2,3, NIHEI Naoto4, KAKUMA Minato1, NAGASAWA Waka5,
SAYAMA Yo6, WADA Toshihiro2, MURAKAMI Masashi5, OHTE Nobuhito1
Graduate School of Informatics, Kyoto University, 2Institute of Environmental Radioactivity, Fukushima

1

University, 3Research Faculty of Agriculture, Hokkaido University, 4Faculty of Food and Agricultural Sciences,
Fukushima University, 5Graduate School of Science, Chiba University, 6Faculty of Agriculture, Kyoto University*Corresponding author： waki.hiromichi.54s@st.kyoto-u.ac.jp

A large amount of radionuclides was released into the environment due to the Fukushima Daiichi
Nuclear Power Plant accident in March 2011. In the accident, radioactive cesium-rich microparticles（CsMPs）were also released. However, little is known about the behavior of CsMPs in forests wherelarge amounts of radionuclide remain. This study aimed to obtain fundamental insights into the discharge
processes of CsMPs. Soil samples were collected along the topography of small forested catchments andanalyzed. The topographic distribution patterns of 137Cs demonstrate that the discharge of 137Cs from theforested catchments can be explained by the sedimentation of eroded soils from the upper part to thebottom of the slope and bank erosion. Furthermore, similar topographic distribution patterns wereobserved between 137Cs and CsMPs. This indicates that the discharge of CsMPs can be driven by
sedimentation of eroded soils on the slope and bank erosion. Additionally, CsMPs were found in the
deeper soil parts in areas where the soil was unaffected by erosion and sedimentation, although 137Cs
generally exhibit limited downward movement. This result indicates that the downward migration of
CsMPs could potentially alter the depth profile of 137Cs in the future.
Keywords：radioactive cesium-rich microparticles, small forested catchment, soil erosion, downward migration

帰還困難区域内の森林土壌における高濃度放射性セシウム含有粒子の分布
脇嘉理*1、辰野宇大2,3、二瓶直登4、角間海七渡1、長澤和佳5、佐山葉6、和田敏裕2、村上正志5、大手信人1
京都大学大学院情報学研究科、2福島大学環境放射能研究所、3北海道大学大学院農学研究院、

1

福島大学食農学類、5千葉大学大学院理学研究院、6京都大学農学部

4*責任著者：waki.hiromichi.54s@st.kyoto-u.ac.jp

2011年３月に発生した福島第一原子力発電所の事故により、多量の放射性物質が環境中に放出された。この事故では、高濃度放射性セシウム粒子（CsMPs）が放出されたことが知られている。しかし、放射性物質を多量に蓄積している森林において、CsMPsの挙動はこれまで明らかにされていない。本研究では、河川上流の森林小流域において、CsMPsの流出過程に関する基礎的知見を得ることを目的とした。地形に沿って土壌を採取して分析したところ、137Csの地形的な分布パターンから、森林小流域からの137Csの流出が、斜面上部で侵食された土砂の堆積と渓岸侵食で説明されることが示された。また、137CsとCsMPsの地形的な分布パターンは類似していた。この結果は、森林小流域におけるCsMPsの流出挙動が、斜面上の土砂の侵食と堆積、および渓岸侵食によって駆動されることを示している。また、一般に137Csは土壌中を下方移動しにくいが、侵食や堆積に影響されていない土壌において、深層にもCsMPsが存在した。この結果は、CsMPsが土壌中を下方移動することで、将来的に137Csの深度分布が変化する可能性を示している。
キーワード：高濃度放射性セシウム含有粒子、森林小流域、土壌侵食、下方移動

47

The 10th Annual Symposium of the IER, Fukushima University / 福島大学環境放射能研究所 第 10 回成果報告会

P-22
Radiocesium concentrations in fish from a dam reservoir andforest rivers in Ukedo River system
KODAMA Fuya*1, KANASASHI Tsutomu2, WADA Toshihiro2
Graduate School of Symbiotic Systems Science and Technology, Fukushima University, 2Institute of1

Environmental Radioactivity, Fukushima University*Corresponding author： s2370050@ipc.fukushima-u.ac.jp

The watershed of Ukedo River system has been heavily contaminated by radiocesium after the
Fukushima Daiichi Nuclear Power Plant accident. Even in 2023, some freshwater fish in the river systemstill exceeded the Japanese regulatory limit of radiocesium for general foodstuff（100 Bq/kg）. To
understand the radiocesium contamination levels, we measured 137Cs concentration in fish in the river
system. In summer 2023, we collected masu salmon and charr from Kayatsuka and Kodeya rivers, andfrom Ogaki Dam Reservoir. Japanese dace and pond smelt were also collected from the reservoir. In
addition, water, aquatic insects, bottom sediments, and plankton were collected to measure their 137Cs.
Masu salmon showed positive “size effect” in all the sites, and the individuals collected from rivers had
higher 137Cs concentrations than those from the reservoir. Size effect was also observed for charr andJapanese dace. Most of individuals collected in the river system exceeded 100 Bq/kg（98.0-3,340 Bq/kg）.
Our data will become a basis for evaluating seasonal changes of 137Cs concentrations in fish andsurrounding environments in the future.
Keywords： 137Cs, freshwater fish, charr, masu salmon, Japanese dace

請戸川水系のダムと渓流河川に生息する魚類の放射性セシウム濃度
児玉楓弥*1、金指努2、和田敏裕2
福島大学大学院共生システム理工学研究科、2福島大学環境放射能研究所

1*責任著者：s2370050@ipc.fukushima-u.ac.jp

請戸川水系は原発事故により最も放射性セシウムに汚染された水系であり、一般食品の出荷基準値である
100 Bq/kgを超える渓流魚が2023年の調査でも確認されている。将来的な請戸川水系における魚類の出荷制
限解除や漁業活動の再開に向け、放射性セシウムの汚染状況を詳しく知る必要がある。福島県浜通り浪江町に位置する請戸川水系のダムである大柿ダム、ダム上流の小出谷川、ダム下流の萱塚川（大柿下）の三か所で調査を行った。河川ではイワナ、ヤマメ、ダムではヤマメ、ウグイ、ワカサギを対象魚類として採取を行い、137
Cs濃度を測定した。また、環境水、底質、水生昆虫、植物などの採取、深度ごとの水温、空間線量などの環境データの記録も行った。2023年夏季の調査においてヤマメの137Cs濃度について注目すると、すべての調
査地点でサイズ効果（全長が大きいほど137Cs濃度が高くなる傾向）が確認できた。その他、本研究では次の４つの結果が得られた；①ダムと比べて渓流域に生息するヤマメのほうが高い137Cs濃度が検出された、②同河川に生息するイワナとヤマメの137Cs濃度を比較すると、ヤマメのほうが高い傾向を示した、③イワナ、ウグ
イにもサイズ効果が確認された、④測定した個体のほぼすべてが100 Bq/kgを超えた（最大約3,340 Bq/kg、最低98 Bq/kg）。本結果は、魚類や環境試料の137Cs濃度の季節変化を明らかにする上での基礎データを示した。
キーワード：137Cs、淡水魚、ヤマメ、イワナ、ウグイ

48The 10th Annual Symposium of the IER, Fukushima University / 福島大学環境放射能研究所 第 10 回成果報告会

P-23
Relationships in radiocesium concentration among dead leaves,aquatic insects（Lepidostomatidae）, and their excretion
KANASASHI Tsutomu*1, WADA Toshihiro1
Institute of Environmental Radioactivity, Fukushima University

1*Corresponding author： t.kanasashi@ier.fukushima-u.ac.jp

Since most of the forests contaminated by radioactive cesium（r-Cs）due to the Fukushima Daiichi
Nuclear Power Plant accident have not been decontaminated, headwater stream ecosystems that dependon organic matters such as dead leaves from forests as primary products were also contaminated by r-Cs.
We believe that clarification of r-Cs transferring from dead leaves to aquatic insects that feed on themwill clear the process of r-Cs transferring to predatorial fish in the headwater stream ecosystems. Aquatic
insects feeding on dead leaves excrete particulate organic matters（FPOM）, which is a source ofnutrients for organisms in upstream rivers. Therefore, if dead leaves are contaminated with r-Cs, it isexpected that FPOM will also contain r-Cs and spread contamination in the upstream ecosystems, but noinformation on r-Cs in FPOM excreted by aquatic insects is available. In this study, larvae of aquatic
insects（Lepidostomatidae）,which mainly feed on dead leaves in streams, were fed with those of Magnolia
obovata, with high r-Cs concentrations, and then, we compared and analyzed relationships of 137Csconcentrations among the dead leaves, larvae and FPOM. Throughout the experimental periods（4-120
hours）, the order of 137Cs concentrations was FPOM > dead leaves > larvae, and linear relationships wereobserved among these three groups.
Keywords： riparian forest, aquatic insect, FPOM, FDNPP accident

カクツツトビケラ科幼虫の摂食・排泄による枯死葉の放射性セシウム
濃度変化とその要因
金指努*1、和田敏裕1
福島大学環境放射能研究所

1*責任著者：t.kanasashi@ier.fukushima-u.ac.jp

福島第一原子力発電所事故により放射性Csに汚染された森林のほとんどが除染されていないため、森林からの枯死葉等の有機物を一次生産者として依存している渓流生態系も放射性Csに汚染されている。枯死葉から、それを摂食する水生昆虫への放射性Cs移行解明は、渓流生態系の魚類等、上位の捕食者への放射性Cs移行解明につながると考える。また、枯死葉を摂食する水生昆虫は、粒子状有機物（FPOM）を排泄し、渓流もしくは下流側の生物の養分源になる。そのため、枯死葉が放射性Csで汚染されていると、このFPOMにも放射性Csが含まれ、汚染が拡散されることが予想されるが、水生昆虫が排泄したFPOMの放射性Csに関する情報は認められない。上記のことから、本研究では、渓流に堆積した枯死葉を主に摂食する
カクツツトビケラ科（Lepidostomatidae）水生昆虫の幼虫（以下、幼虫）に、放射性Cs濃度が高いホオノキ（Magnolia obovata）の枯死葉を与え、枯死葉―幼虫―FPOMの放射性Cs濃度を比較・解析した。ホオノキ枯死
葉を2022年の落葉期以降に採取し、幼虫を2023年４～10月の実験開始前日に採取し、一定水温の環境下で飼育し、120時間までの任意の期間、摂食実験を行った。実験期間を通して、Cs-137濃度の高さはFPOM＞枯死葉＞幼虫になり、これら三者の間には、実験期間に影響されず、線形関係を示した。
キーワード：渓畔林、水生昆虫、FPOM、福島第一原子力発電所事故

49

The 10th Annual Symposium of the IER, Fukushima University / 福島大学環境放射能研究所 第 10 回成果報告会

P-24
BEECONECT: A connected flower to measure the effects ofradioactive contamination on the cognitive health of pollinators
Kristine ABENIS1, Loïc GOULEFERT1, Christian LUBAT2, NANBA Kenji3, MIZUSAWA Leiko4,
Béatrice GAGNAIRE5, Margot CREVET5, Olivier ARMANT5, Jean-Marc BONZOM5,
Mathieu LIHOREAU*1
Research Center on Animal Cognition（CRCA-CBI）,French National Centre for Scientific Research（CNRS）,

1

University of Toulouse, France, 2BeeGuard, Labège, France, 3Institute of Environmental Radioactivity, Fukushima
University, 4Faculty of Human Development and Culture, Fukushima University, 5Institute for Radioprotection
and Nuclear Safety（IRSN）, Radionuclide Ecology and Ecotoxicology Laboratory, PSE-ENV/SERPEN, Cadarache,France*Corresponding author： mathieu.lihoreau@univ-tlse3.fr

Insect pollinators are vital to the maintenance of terrestrial ecosystems and global food security. Bees,
wasps, flies, and butterflies heavily rely on learning and memory to forage on flowers. However, these
cognitive abilities can be disrupted by environmental stressors, which can have dramatic consequenceson populations if food supply is compromised. Our aim in BEECONECT is to study the effects ofradioactive contamination on the cognitive health of pollinators in Fukushima Prefecture. To mass
phenotype the cognitive health of pollinators, we developed an automated and non-invasive “flower”, i.e.,Y-maze device in which individual insects must learn to find a sucrose reward, that operate continuously
without the need of experimenters. Our system uses on-board artificial intelligence, enabling recognitionof individual insects and species. Our preliminary analysis indicates reduced learning abilities in wild
Japanese yellow hornets exposed to high radiation levels. Our plan for 2024 is to run a more extensive
analysis of the cognitive health of honey bees and some wild pollinators using six flowers placed in sites
characterized by different levels of radio-contamination. Our flower is the first automated cognitive test
ever deployed to measure cognition in insects. Once validated, it will provide an extremely powerful tool
to accurately quantify the risks of radioactive contamination（and many other stress factors）for
pollinator populations and their associated ecosystem services.
Keywords： pollinators, cognition, learning and memory, mass phenotyping, radioactive contamination,
resilience

50

The 10th Annual Symposium of the IER, Fukushima University / 福島大学環境放射能研究所 第 10 回成果報告会

P-25
Study of the effects of environmental radiocontamination on themetabolism of an amphibian, the tree frog
Léa DASQUE*1,2, Damien ROUSSEL2, Jean-Marc BONZOM1, Olivier ARMANT1, Clément CAR1,
André GILLES3, NANBA Kenji4, ISHINIWA Hiroko4, WADA Toshihiro4, Sandrine FRELON1,
Nathalie MONDY2Institute for Radioprotection and Nuclear Safety（IRSN）,Radionuclide Ecology and Ecotoxicology Laboratory,

1

PSE-ENV/SERPEN, 2Université Claude Bernard Lyon, 3Université Aix Marseille, 4Institute of Environmental
Radioactivity, Fukushima University*Corresponding author： lea.dasque@irsn.fr

The Fukushima nuclear accident（2011）led to radioactive releases into the environment, resulting inchronic exposure to ionizing radiation（IR）for wildlife living in these areas. Several studies havedemonstrated that chronic and low-dose exposure to IR can impact the energy metabolism of various
species. In this context, we measured the activity of two enzymes involved in energy metabolism in thethoracic muscles and liver of male Japanese tree frogs（Dryophytes japonicus）collected during the
reproductive period in 2022 in Fukushima Prefecture along a gradient of exposure to ionizing radiation.
In the trunk muscles, which are very active for calling during the breeding period, the activity of citratesynthase and lactate dehydrogenase increases with the dose of ionizing radiation absorbed by the treefrogs. This could suggest a response of aerobic and anaerobic metabolisms adjusted to cope with theincreased energetic demands of the breeding period and compensate for the energetic costs associatedwith the dose received. In the liver, the organ of detoxification, we observed no effect of radioactivity
dose on enzymatic activities, suggesting no dose-related increase in maintenance energy. To further
investigate these results, we will evaluate the relationship between these modifications and the
production of energy-intensive sexual signals, i.e., male tree frog’s call during the breeding season.
Keywords： ecophysiology, energy metabolism, tree frog, ionizing radiation, Fukushima

51

The 10th Annual Symposium of the IER, Fukushima University / 福島大学環境放射能研究所 第 10 回成果報告会

P-26
Repeated DNA sequences of the centromere region in three speciesof the genus Myodes： Establishment of FISH probes for dicentricchromosomal analysis
ISHINIWA Hiroko*1, Olena BURDO2, NAKATA Akifumi3, Donovan ANDERSON4, MIURA Tomisato4
Institute of Environmental Radioactivity, Fukushima University, 2Institute for Nuclear Research National

1

Academy of Sciences of Ukraine, 3Faculty of Pharmaceutical Sciences, Hokkaido University of Science, 4Instituteof Radiation Emergency Medicine, Hirosaki University*Corresponding author： ishiniwa@ier.fukushima-u.ac.jp

Dicentric chromosomes（Dic）are chromosome aberrations caused by radiation exposure. As theiroccurrence correlates with radiation dose, Dic analysis serves as a biodosimetry method. However,accurately identifying Dic requires a high level of expertise and skill, presenting a challenge for prompt
analysis. In this study, we aimed to improve the efficiency of chromosome analysis in rodents – organisms
with numerous acrocentric chromosomes that are particularly difficult to identify Dic. Our approach
involved the development of fluorescence in situ hybridization（FISH）probes to visualize the centromere
region by fluorescent staining. We utilized the repeated sequence motif found in the centromere region ofvoles（genus Microtus）and applied it to three species of voles belonging to genus Myodes. Our findings
indicate that the repeated sequence motif could be identified in all chromosomes except the Y
chromosome, of the Grey red-backed vole（Myodes rufocanus）and Northern red-backed vole（M. rutilus）. In
the bank vole（M. glareolus）,not all chromosomes showed the motifs. The presence or absence of repeatedsequences motif in the centromere region among phylogenetically related species is also observed inother taxa such as humans. This observation suggests that these sequences may have been acquired orlost during evolution in voles.
Keywords： dicentric chromosome, centromere, Msat-160, Myodes, vole

Myodes属３種におけるセントロメア領域の反復DNA配列：二動原体
染色体解析に向けたFISHプローブの作成
石庭寛子*1、オレナ・ブルドー2、中田章史3、ドノヴァン・アンダーソン4、三浦富智4
福島大学環境放射能研究所、2ウクライナ国立科学アカデミー原子力研究所、3北海道科学大学薬学部、4弘前大学被1

ばく医療総合研究所*責任著者：ishiniwa@ier.fukushima-u.ac.jp

二動原体染色体とは放射線被ばくによって起こる染色体異常である。その発生頻度は被ばく線量に比例する
ことからバイオドシメトリ（生物学的線量測定）として評価手法が確立されている。しかしながら、二動原体
染色体の特定は高度な専門知識と技術が必要とされ、識別の難解さが解析を妨げる要因となっている。本研
究では、特に識別が難しい末端動原体型染色体を多く持つ齧歯類の染色体解析の効率化を目指し、セントロ
メア領域を蛍光染色して視覚化するFISHプローブの作成を行なった。ハタネズミ類のセントロメア領域で発見されている反復配列をヤチネズミ類（Myodes属）３種に適用したところ、エゾヤチネズミ（Myodes
rufocanus）とヒメヤチネズミ（M. rutilus）ではY染色体を除くすべての染色体で反復配列を確認できたが、ヨーロッパヤチネズミ（M. glareolus）では一部の染色体で確認されなかった。系統的に近縁な種内におけるセント
ロメア領域の反復配列の在・不在は、ヒトなど他の分類群にも見られることから、ヤチネズミ類でも同様に進化の過程で獲得・欠失した可能性が示唆された。
キーワード：二動原体染色体、セントロメア、Msat-160、Myodes、ハタネズミ類

52

The 10th Annual Symposium of the IER, Fukushima University / 福島大学環境放射能研究所 第 10 回成果報告会

P-27
Distribution and seasonality of 137Cs activity in terrestrial andaquatic ecosystems in the difficult-to-return zone
YAMAGUCHI Daisuke*1, KANASASHI Tsutomu2, ISHINIWA Hiroko2, WADA Toshihiro2
Graduate School of Symbiotic Science and Technology, Fukushima University, 2Institute of Environmental

1

Radioactivity, Fukushima University*Corresponding author： s2270057@ipc.fukushima-u.ac.jp

Radiocesium released by the Fukushima Daiichi Nuclear Power Plant accident remains in theenvironment and is taken up by wild animals and plants through food webs. Since 137Cs in forests is
circulated through trees, the 137Cs concentrations in forests tends to be higher than that in human living
areas. In addition, fallen leaves and other materials migrate into rivers, and pond, and thereby transfer
137
Cs to aquatic ecosystems. But few studies have analyzed the dynamics of 137Cs in multiple ecosystems,
and clarified the transfer of 137Cs of plants and animals living in the transition zone. In this study, wemeasured 137Cs concentrations in the environmental samples and multiple species collected at
Shimofukazawa Pond and the surrounding terrestrial area in the difficult-to-return zone in Futaba Town,
and compared the concentrations and examined seasonal changes. As a result, 137Cs concentrations in soil
and sediments were higher than in organisms. Among plants and animals, leaves of Chengiopanax
sciadophylloides showed extremely high values（34,200Bq/kg）, but excluding some species, the values of
Cs concentrations in biota in terrestrial and aquatic areas were relatively similar. In largemouth bass,
individuals in the summer 2023 showed higher 137Cs concentrations than those at other seasons. These
results demonstrated that, approximately 13 years after the FDNPP accident, most of the 137Cs in the
difficult-to-return zone has transferred to soil and sediments, while the 137Cs concentrations of animals andplants in terrestrial and aquatic areas showed high variability depending on their species and seasons.
137

Keywords： wild plants and animals, forest ecosystem, aquatic ecosystem, 137Cs concentrations

帰還困難区域の陸域・水域生態系における137Cs濃度分布と季節性
山口大輔*1、金指努2、石庭寛子2、和田敏裕2
福島大学大学院共生システム理工学研究科、2福島大学環境放射能研究所

1*責任著者：s2270057@ipc.fukushima-u.ac.jp

福島第一原子力発電所事故により放出された137Csは現在でも環境中に留まり、食物網などを介して野生動植
物に取り込まれている。森林内137Cs濃度は人の生活圏内に比べて高く、森林内の137Csは樹木などを通して循環することが原因の一つである。さらに落ち葉などが河川・湖沼などに移行することで森林内の137Csが水域生態系に移行する。これまで、137Csの動態について、森林や河川・湖沼など、各生態系を対象とした研究
事例は多数報告されているものの、陸域・水域を含めた複数の生態系を対象とした研究事例は少ない。本研
究では、双葉町の帰還困難区域内の下深沢ため池（水域）及びその周辺（陸域）に生息する複数の生物種や環境中の137Cs濃度測定を行い、濃度の比較や季節変化の検討を行った。結果として土壌や堆積物の137Cs濃度は生物よりも高かった。動植物の中では、一部の種で極めて高い値（例：コシアブラ最大34,200 Bq/kg）を示す
一方、それらの種を除くと陸域・水域の動植物137Cs濃度の値は比較的近い値を示した。オオクチバスでは
2023年の夏季の個体は他の時期の個体に比べて高い137Cs濃度を示した。原発事故から約13年が経過した現
在、帰還困難区域内の137Csの多くは、森林土壌や池底堆積物に移行する一方で、陸域・水域に生息する動植
物の種や季節によって、137Cs濃度に大きな偏りが生じることが示された。
キーワード：野生動植物、137Cs濃度、水域生態系、陸域生態系

53

The 10th Annual Symposium of the IER, Fukushima University / 福島大学環境放射能研究所 第 10 回成果報告会

P-28
Polychaete（Perinereis aibuhitensis）rearing experiment in seawatercontaining radiocesium
URYU Junya*1, ITO Takayuki1, YAMANOBE Takahiro1
Fukushima Prefectural Research Institute of Fisheries Resources

1*Corresponding author： uryu_junya_01@pref.fukushima.lg.jp

In general, marine organisms are known to uptake radiocesium primarily from seawater and preyorganisms. In order to investigate the uptake of radiocesium from seawater, we conducted a rearing
experiment with polychaetes using seawater containing radiocesium. Approximately 500 g of polychaetes
housed in a 45 L glass tank at a water temperature of 12℃ and the experiment was conducted without
feeding. Rearing seawater was prepared using radiocesium extracted from forest soil, with the salinity
adjusted to 25‰ and the radiocesium concentration set at 1 Bq/L. Polychaetes were taken up 7, 14, and28 days after the start of the rearing experiment and measured for radiocesium concentrations. The
radiocesium concentrations in polychaetes were 6.6-9.6 Bq/kg-wet, 10.1-12.4 Bq/kg-wet, and 10.2-15.8 Bq/
kg-wet at 7, 14, and 28 days, respectively. Considering that the rearing seawater was at 1 Bq/L, theinternal radiocesium concentrations in the polychaetes exceeded 10 times that of the rearing water. The
initial radiocesium concentration in the polychaete at the beginning of the experiment was non-detectable（ND）. This suggests that the internal radiocesium in the polychaete was uptake from the rearing
seawater, reaching concentrations up to approximately 15 times higher.
Keywords： radiocesium, polychaete（Perinereis aibuhitensis）,prey organisms

放射性Csを含む海水でのアオゴカイ飼育試験
瓜生純也*1、伊藤貴之1、山野辺貴寛1
福島県水産資源研究所

1*責任著者：uryu_junya_01@pref.fukushima.lg.jp

一般に、海産生物は放射性Csを主に海水や餌生物から取り込むと言われている。海水からの放射性Csの取り込み量を調査するため、放射性Csを含む海水でアオゴカイの飼育試験を行った。アオゴカイ500gを60cm
水槽（45L）に収容し、水温12℃、無給餌で飼育試験を行った。飼育海水は、森林土壌から抽出した放射性Csを用いて、塩分濃度25‰、放射性Cs濃度を１Bq/Lに調整した。アオゴカイは実験開始から７日後、14日後、28日後に取り上げ、放射性Cs濃度を測定した。測定の結果、７日後の放射性Csは6.6～9.6 Bq/kg-wet、14日
後は10.1～12.4 Bq/kg-wet、28日後は10.2～15.8 Bq/kg-wetであった。
飼育海水は１Bq/Lであることから、アオゴカイ体内の放射性Csは飼育海水の10倍以上の濃度に上昇していた。実験開始時におけるアオゴカイの放射性Cs濃度はNDであったことから、アオゴカイ体内の放射性Csは飼育海水から放射性Csを取り込み、最大で15倍程度まで上昇していた。
キーワード：放射性Cs、アオゴカイ、餌生物

54

The 10th Annual Symposium of the IER, Fukushima University / 福島大学環境放射能研究所 第 10 回成果報告会

P-29
Development of a highly sensitive analytical method for ultratrace 99Tc in environmental water
TAKAMI Kei1, NABEYAMA Yuki1, HATSUKAWA Yuichi2, TSUKADA Kazuaki3, ASAI Masato3,
SUEKI Keisuke4, YAMASAKI Shinya4, TAKAKU Yuichi4, SAKAGUCHI Aya*4
School of Science and Engineering, University of Tsukuba, 2National Institutes for Quantum and Radiological1

Science and Technology, 3Japan Atomic Energy Agency, 4Institute of Pure and Applied Sciences, University ofTsukuba*Corresponding author： ayaskgc@ied.tsukuba.ac.jp

The monitoring of 99Tc in environmental waters, especially for seawater, is essential due to the physicochemical properties of 99Tc. However, the determination of ultra-trace levels of 99Tc in environmental
water is quite difficult, because of the use of large amounts of seawater and the requirement forcomplicated chemical separation for both radiometric analysis and mass spectrometry. In this study, we
attempt to construct a trace level of 99Tc measurement method by improving the sensitivity of ICP-MSand developing of a simple Tc separation method from seawater. In addition, the production of 95mTc
tracer by the nuclear reaction of 95Mo（p, n）95mTc is also conducted.
Keywords： technetium, anthropogenic radionuclides, mass spectrometry

環境水中の極微量99Tc高感度分析法の開発
高見佳1、鍋山雄樹1、初川雄一2、塚田和明3、浅井雅人3、末木啓介4、山崎信哉4、高久雄一4、坂口綾*4
筑波大学理工学群化学類、2量子科学技術研究開発機構、3日本原子力研究開発機構、4筑波大学数理物質系

1*責任著者：ayaskgc@ied.tsukuba.ac.jp

Tcはその物理化学的特性から、環境特に海洋におけるモニタリングが必須である。しかし、海水中極微量
Tc分析には大量の海水から煩雑な化学分離により濃縮・精製が必要であり放射線分析や質量分析ともに困難である。そこで、ICP-MSの高感度化、海水からの簡便なTc分離法について検討し、極微量99Tcの迅速・簡便な定量を試みた。また、95Mo（p, n）反応による95mTcトレーサー製造も試みた。
99
99

キーワード：テクネチウム、人工放射性核種、質量分析

55

The 10th Annual Symposium of the IER, Fukushima University / 福島大学環境放射能研究所 第 10 回成果報告会

P-30
Kinetic study of electrochemically formed silver iodide for the
rapid and selective recovery of iodide ion in environmental water
YAMASAKI Shinya*1, TAKEDA Ryoji1
Center for Research in Radiation, Isotopes, and Earth System Sciences, University of Tsukuba

1*Corresponding author： s-yamasaki@ied.tsukuba.ac.jp

It is important to quantify the concentration of iodine in each chemical form because the transfer
behavior and biological effects of iodine in the environment differ depending on the chemical form. In thisstudy, we investigated the kinetic contribution of the electrochemical recovery method for iodide ionsthat we have developed previously. A silver wire electrode（~200mm2）was used as the working
electrode, an Ag/AgCl electrode（3M NaCl）as the reference electrode, and a platinum electrode as thecounter electrode. The surface area of the working electrode and the amount of solution were varied to
examine the concentration behavior of I- on the electrode surface. A constant potential electrolysis was
performed by adding 3 kBq of 125I to the reaction solution. The concentration of I- in the solution before
and after the reaction was determined using an NaI scintillator, and the recovery rate was obtained. Asan environmental sample, water collected from Matsumi Pond in the University of Tsukuba was used byfiltered through a 0.45 µm filter. For comparison, the I- concentration in the environmental sample wasdetermined by HPLC-ICP-MS and compared with the results of this electrochemical method. The
experimental results showed that the reaction reached a steady state more quickly as the ratio ofelectrode area to solution volume increased. The recovery rate increased as the total concentration of Iincreased. Analysis of the actual sample yielded values on the same order of magnitude as those obtainedby HPLC-ICP-MS.
Keywords： speciation, constant potential electrolysis, iodine-125

環境水中ヨウ化物イオンの迅速かつ選択的回収に向けた電気化学的手法の速度論的検討
山崎信哉*1、武田凌治1
筑波大学放射線・アイソトープ地球システム研究センター

1*責任著者：s-yamasaki@ied.tsukuba.ac.jp

放射性ヨウ素の環境中における移行挙動や生体影響はその化学形態ごとに異なるため、化学形態別に濃度定量することが重要である。本研究では、これまでに構築してきたヨウ化物イオンを電気化学的に回収する方法について、その速度論的な寄与について検討を行った。作用電極には銀ワイヤー電極（~200mm2）、参照
電極はAg/AgCl電極（3M NaCl）、対極は白金電極を用いた。電極の面積及び溶液量を変化させて、電極表
面へのI-の濃集挙動を調べた。反応溶液には125Iを3 kBq加え、定電位電解を行った。反応前後の溶液中のI濃度をNaIシンチレーターにより求め、回収率を得た。実試料として、
筑波大学内の松美池で採取した水を0.45µmのフィルターでろ過して用いた。また、比較のため、HPLC-ICP-MSにより試料中のI-濃度を求め、本電気化学的手法の結果と比較した。実験の結果、電極面積と溶液量の比が大きくなるほど反応が速やかに定常状態に達した。また、回収率はI-の全濃度が高くなるにつれて上昇した。実試料を分析した結果、HPLCICP-MSにより求めた値と同オーダーの値が得られた。
キーワード：スペシエーション、定電位電解、ヨウ素-125

56

The 10th Annual Symposium of the IER, Fukushima University / 福島大学環境放射能研究所 第 10 回成果報告会

P-31
Variation of 137Cs activity concentration in flooded and pore waterin paddy fields and its transfer to rice
TSUKADA Hirofumi*1, SAITO Takashi2, HIRAYAMA Takashi3, MATSUOKA Hiroaki3, NAKAO Atsushi4
Institute of Environmental Radioactivity, Fukushima University, 2Department of Agriculture, Forestry and

1Fisheries, Fukushima Prefecture, 3Hama Agricultural Regeneration Research Centre, Fukushima Prefectural
Agricultural Technology Centre, 4Department of Life and Environmental Sciences, Kyoto Prefectural University*Corresponding author： hirot@ipc.fukushima-u.ac.jp

Caesium-137（137Cs）is a major anthropogenic radionuclide released into the environment as a result of
the 2011 TEPCO’s Fukushima Daiichi Nuclear Reactor Station accident, and parts of Hamadori inFukushima are still in a difficult return zone. In the specified reconstruction and revitalization bases
where air dose rates have been reduced due to decontamination, evacuation orders were lifted by 2023
and residents began returning home. In anticipation of the resumption of farming after their return, rice
is being cultivated in experimental rice paddies. In this study, we investigated 137Cs in inlet water, flooded
water, and pore water, and discussed the transfer of 137Cs to rice. Water samples were collected biweekly
over six times from five sites in Hamadori（Okuma, Minamisoma and Katsurao）over the 2018–2022
cultivation periods to measure dissolved 137Cs activity concentration, potassium（K）, and ammonium（NH4）concentrations. The activity concentrations of 137Cs in the inlet water and flooded water were
uniform below 0.1 Bq L -1, and significant differences were observed at some sites. The activity
concentration of 137Cs in pore water under anaerobic condition increased with increasing NH4
concentration, markedly to reach a value 20-fold higher than that in flooded water. However, the 137Cs/K
ratio in flooded water and pore water remained uniform throughout waterlogging period, and even if the137
Cs activity concentration in pore water increases, the K concentration increases at the same time. And
there was no change in the competitive absorption relationship between the two absorbed by rice plants.
Therefore, even if the 137Cs activity concentration in the porewater is elevated, it is considered that riceuptake of 137Cs is not necessarily enhanced during the waterlogging period due to appropriate K
application.
Keywords： 137Cs/K ratio, NH4, waterlogging period, competitive absorption

田面水および間隙水中137Cs濃度の変化とイネへの移行
塚田祥文*1、齋藤隆2、平山孝3、松岡宏明3、中尾淳4
福島大学環境放射能研究所、2福島県農業振興課、3福島県農業総合センター浜地域農業再生研究センター、4京都府

1

立大学生命環境科学研究科*責任著者： hirot@ipc.fukushima-u.ac.jp

セシウム-137（137Cs）は、2011年の東京電力福島第一原子力発電所事故によって環境中に放出された主要な人
工放射性核種であり、未だに浜通りの一部は帰還困難区域となっている。除染等による空間線量率の低減化が行われた特定復興再生拠点では、2023年までに避難指示が解除され、住民の帰還が始まった。そこで帰還
後の営農再開を見据え、試験水田によるイネの栽培を行っている。ここでは、水田に供給される灌漑水、田面水および間隙水の137Csについて調査し、イネへの137Cs移行について考察した。2018年から2022年に浜通
りの５地点（大熊町・南相馬市・葛尾村）で６回に亘り、イネ栽培期間に水口水・田面水・間隙水を２週間毎に採取し、溶存態137Cs、アンモニウム（NH4）、カリウム（K）濃度を測定した。水口水と田面水中137Cs濃度は、0.1
Bq L-1以下で一様な濃度にあり、両者で有意差の見られる地点があった。還元的な環境にある間隙水中137Cs
濃度は、NH4濃度の上昇に伴い増加し、田面水の20倍にも達した。しかしながら、田面水と間隙水の137Cs/
K濃度比は栽培期間を通して一様にあり、間隙水中137Cs濃度が増加したとしても同時にK濃度も増加した。
よって、イネに吸収される両者の競合的な吸収関係に変化はなかった。従って、間隙水137Cs濃度が増加しても、適正なK施用によりイネへの吸収抑制が働いていると考えられる。
キーワード：137Cs/K比、NH4、湛水期、競合的な吸収57

The 10th Annual Symposium of the IER, Fukushima University / 福島大学環境放射能研究所 第 10 回成果報告会

P-32
Environmental transfer parameter values for internal dose
assessment obtained by QST-NIRS in 2011-2022
TAGAMI Keiko*1, UCHIDA Shigeo1
National Institute of Radiological Sciences, National Institutes for Quantum Science and Technology, Institute for1

Radiological Science*Corresponding author： tagami.keiko@qst.go.jp

The IAEA has published Tecdoc-1927（2020）,which collates environmental transfer parameters reported
after the Fukushima Daiichi Nuclear Power Plant accident. Various organizations cooperated to publish
this tecdoc including data over several years since the accident. However, the geometric mean values aremainly shown in tables, and thus little individual data are listed. To make the data available, we compiled
parameter data collected by QST-NIRS in 2011-2022（QST-R-27, https://repo.qst.go.jp/records/86615）,
and here, some important results were reported.
Shortly after the accident occurred, we started to collect plant samples thus the data were used. We also
used open available food monitoring data to calculate parameter values. It was found that lower retentionof radioiodine than radiocaesium in plants. Once retained in plants, both radionuclides decreased withsimilar environmental half-lives, with a geometric mean value of 6-8 d. The translocation fromcontaminated parts to non-contaminated parts was greater for radiocaesium than for radioiodine. In thelong term, we investigated radiocaesium concentrations in trees and herbaceous plants and found that
decreasing rates of radiocaesium from both types of plants can be described by using two components,
fast and slow half-life fractions. Other parameter values are also available in the report.
Keywords： radioiodine, radiocaesium, environmental half-lives, food monitoring data

量研−放医研によって2011-2022年に収集された内部被ばく線量評価のための環境移行パラメータ値について
田上恵子*1、内田滋夫1
量子科学技術研究開発機構

1

放射線医学研究所*責任著者：tagami.keiko@qst.go.jp

近年IAEAから福島第一原発事故後の環境移行パラメータを集めたTecdoc-1927（2020）が発行され、多様な機関からの報告値が、事故後から数年間程度の経時変化も含め記載されている。しかし主に幾何平均値が表として示され、個別データは少ない。そこで貴重なパラメータデータを個別に扱えるようにすることを目的とし、事故後から2022年まで、内部被ばくに着目しつつ量研−放医研において収集したデータをまとめた（QST-R-27, https://repo.qst.go.jp/records/86615）。今回はその成果について報告する。
我々は主に植物試料の収集を進めると共に、食品モニタリングデータ等も活用しつつパラメータデータを導出した。その結果、降下した放射性物質の植物による保持（遮断係数）は、放射性Iの方が放射性Csよりも低いことがわかった。ただし、一旦植物に保持された放射性IとCsは、どちらも同程度の環境半減期で減少し、その幾何平均値は6-8日であった。なお、汚染した部位から非汚染部位への転流は、放射性Csの方がIよりも大きかった。長期的には木本および草本植物の放射性Csを調査し、どちらの植物のタイプでも環境半減期が早い成分と遅い成分の２つに分けられることを明らかにした。その他、土壌-土壌溶液間分配係数、土壌農作物移行係数、家畜への移行、野生の食品への面移行係数、環境水から魚介類への濃縮係数等も公開している。
キーワード：放射性ヨウ素、放射性セシウム、環境半減期、食品モニタリングデータ

58The 10th Annual Symposium of the IER, Fukushima University / 福島大学環境放射能研究所 第 10 回成果報告会

P-33
Cesium separation from aqueous waste matrices using crownether functionalized mesoporous silica
Rashedul Islam RIPON*1,2, Zinnat A. BEGUM3,7, Bashir Ahmmad ARIMA4, OGATA Makoto5,
TAKAGAI Yoshitaka6, Ismail M. M. RAHMAN*7
Graduate School of Symbiotic Systems Science and Technology, Fukushima University, 2Department of1

Chemistry, Mawlana Bhashani Science and Technology University, Bangladesh, 3Department of Civil Engineering,Southern University Bangladesh, Bangladesh, 4Graduate School of Science and Engineering, Yamagata University,
Faculty of Food and Agricultural Sciences, Fukushima University, 6Faculty of Symbiotic Systems Science,5

Cluster of Science and Technology, Fukushima University, 7Institute of Environmental Radioactivity, Fukushima
University*Corresponding author: ripon.chemmbstu@gmail.com, immrahman@ipc.fukushima-u.ac.jp

Radiocesium（r-Cs: 137Cs; t1/2, 30.2 yrs; chemical analog of K）separation from environmental wastewater
has become an emerging issue for protecting public health in the aftermath of the Chornobyl and
Fukushima accidents. The current work focuses on the development of an efficient solid-phase adsorbent
material, DFDB18C6@SBA-NH2, encompassing a macrocyclic ligand（diformyl dibenzo-18-crown-6-ether,
DFDB18C6）covalently attached to mesoporous Santa Barbara Amorphous-15（SBA-15）,for r-Cs removalfrom environmental wastewater. The batch adsorption technique was utilized to investigate theadsorbent’s behavior towards Cs. Various operating variables were systematically optimized, including
solution pH, reaction time, initial ion concentration, and presence of competing ions. The adsorbent
FDDB18C6@SBA-NH2 has considerable Cs adsorption capacity at pH 6. The FDDB18C6@SBA-NH2
exhibits rapid Cs adsorption, and the adsorption kinetic is governed by the pseudo-second-order model.
The Langmuir adsorption isotherm model fits the experimental adsorption data well, indicating that theCs adsorption is probably a monolayer adsorption process. Hence, the crown ether functionalized
mesoporous silica adsorbent can be used to separate r-Cs from aqueous waste matrices.
Keywords： radiocesium, separation, crown ether, solid phase adsorbent, adsorption

59

The 10th Annual Symposium of the IER, Fukushima University / 福島大学環境放射能研究所 第 10 回成果報告会

P-34
Physical and chemical traits of cesium and strontium tolerance invelvet grass（Holcus lanatus L.）
Bayezid M. KHAN1,2, M. Ferdous ALAM1,3, Zinnat A. BEGUM1,4, Ismail M. M. RAHMAN*1
Institute of Environmental Radioactivity, Fukushima University, 2University of Chittagong, Bangladesh, 3Atomic

1

Energy Research Establishment, Bangladesh, 4Southern University Bangladesh*Corresponding author： immrahman@ipc.fukushima-u.ac.jp

Unusual environmental intrusion of radiocesium（r-Cs）and radiostrontium（r-Sr）from nuclear reactors
and fuel reprocessing plants, as well as nuclear power plant accidents like those in Chornobyl and
Fukushima, has raised concerns regarding potential health risks through soil-to-crop transfer andsubsequent human exposure. The enrichment of soil with potassium（K）and calcium（Ca）has been
identified as a strategy to reduce the plant uptake of r-Cs or r-Sr. However, the impact of these changes
in uptake on plant growth remains insufficiently understood. This study aims to investigate the effects ofr-Cs and r-Sr on the growth of seedlings of the wild grass Holcus lanatus L. cultivated in hydroponicsolutions, using stable Cs or Sr isotopes as the corresponding analogs of r-Cs and r-Sr. The findings revealthat higher concentrations of Cs and Sr（≥ 4 mg L–1）inhibit seedling growth, while lower concentrations（≤ 1 mg L–1）exhibit no significant effect. The H. lanatus demonstrates moderate tolerance to Cs and strong
tolerance to Sr. The supplementation of K and Ca in soils amended with Cs or Sr isotopes further reduces
the uptake of these elements in the H. lanatus. In addition, introducing Cs or Sr to the soil alters the influx
rates of various nutrient elements into H. lanatus. These results suggest that H. lanatus may represent a
viable option for cultivation in r-Cs and r-Sr contaminated grasslands.
Keywords： wild grass, cesium, strontium, tolerance, growth traits

60

The 10th Annual Symposium of the IER, Fukushima University / 福島大学環境放射能研究所 第 10 回成果報告会

P-35
Temporal change of 137Cs fractions in archived soil samples
collected from Fukushima Prefecture in 2011YANAGIGAWA Kento1, TATSUNO Takahiro2,3, TSUKADA Hirofumi*2
Graduate School of Symbiotic Systems Science and Technology, Fukushima University, 2Institute of1

Environmental Radioactivity, Fukushima University, 3Research Faculty of Agriculture, Hokkaido University*Corresponding author： hirot@ipc.fukushima-u.ac.jp

Huge amounts of radionuclides were released into the environment by the Fukushima Daiichi Nuclear
Power Station（FDNPS）accident and deposited onto the surrounding and the northwest direction fromthe FDNPS. Ceasium-137 is a relatively long half-life and present in the soil for a long time and is known
to exist in several fractions. In this study, 55 archived soil samples（1,080-196,000 Bq kg-1 DW）collectedfrom June-July 2011 from within a 20 km zone of the FDNPS were analysed for 137Cs in the soils using asequential extraction method, and the soils were repeatedly wetted and dried to accelerate changes overtime. The mean values of the fractions of exchangeable, bound-to-organic and strongly bounded 137Cs
were 11.8, 10.2 and 79.8%, respectively. Three fractions in the soils after ageing were 8.33, 9.64 and 81.3%,
with significantly decreasing in the exchangeable fraction and with increasing in the strongly boundfraction, while 137Cs in the bound-to-organic fraction did not change with aging. The study utilised thearchived soil samples provided by the Nuclear Regulation Authority and managed by the Institute ofEnvironmental Radioactivity, Fukushima University.
Keywords： archived soil sample, sequential extraction methods, exchangeable fraction

2011年に福島県から採取した土壌アーカイブ試料の137Cs存在形態の経時変化に関する研究栁川賢斗1、辰野宇大2,3、塚田祥文*2
福島大学共生システム理工学研究科、2福島大学環境放射能研究所、3北海道大学農学研究院

1*責任著者：hirot@ipc.fukushima-u.ac.jp

2011年の東京電力福島第一原子力発電所（FDNPS）事故により、主に原発周辺と北西方向の広い範囲に放射性核種が拡散、土壌を汚染した。そのうち137Csは半減期が比較的長く、長期間土壌中に残留する。土壌中
137
Csは、幾つかの存在形態にあることが知られている。本研究では、2011年６月～７月にかけてFDNPSから半径20km圏内から採取された55試料の土壌アーカイブ試料（1,080～196,000 Bq kg-1 DW）について逐次抽出法で、土壌中137Csの交換態・有機物結合態・強固結合態の存在形態分析を行った。また、湿潤－乾燥を繰り返すエイジング処理を行い、存在形態の経時的変化を求め、エイジングによる存在形態割合の変化を求めた。エイジング前の交換態、有機物結合態、強固結合態137Csの存在割合の平均値は、それぞれ11.8、10.2および79.8%、エイジング後に8.33、9.64および81.3%となり、交換態割合が有意に減少し、一方で強固結合態割合が増加した。また、有機物結合態割合はエイジングによる有意な変化が見られなかった。本研究は、原子力規制庁が提供し、福島大学環境放射能研究所が管理する土壌アーカイブ試料を活用しました。
キーワード：土壌アーカイブ試料、逐次抽出、交換態、有機物結合態、強固結合態

61

The 10th Annual Symposium of the IER, Fukushima University / 福島大学環境放射能研究所 第 10 回成果報告会

P-36
Modeling the impact of forest fires in the Chornobyl Exclusion
Zone on radionuclide contamination of surface waters
Oleksandr PYLYPENKO1, Mykola TALERKO2, Mark ZHELEZNYAK*3
Institute Mathematical Machines and System Problems NAS Ukraine, 2Institute for Safety Problems of Nuclear

1

Power Plants NASU, 3Institute of Environmental Radioactivity, Fukushima University*Corresponding author： zheleznyak.m@gmail.com

The problem of secondary radioactive contamination due to forest fires in the Chernobyl Exclusion Zone
（CEZ）became especially important after the beginning of the military invasion of Russian Federation
into Ukraine across the Belarus-Ukrainian border through the CEZ. The temporary occupation of CEZ
and the military activities during its liberation caused a number of forest fires. The problem is still acutedue to the risk of new military invasions into the CEZ and natural wildfires. Taking into account that the
Pripyat River and Kyiv Reservoir of the Dnipro River are the main pathways of radionuclide transport
from CEZ to the Kyiv city agglomeration, the task is to assess the impact of the maximum potential
wildfires in the CEZ on the contamination of Dnipro River at Kyiv. This task is solved by the
implementation of the Lagrangian atmospheric dispersion model LEDI for simulating the fallout of 137Cs
and 90Sr on water surface and watershed in CEZ and on Kyiv reservoir, watershed wash-off model
RETRACE and one -dimensional river / reservoir model RIVTOX. The models have been retested andcalibrated using the data that were collected and systematized during the JST-JICA SATREPS project.
The comparative role of the fallout on the watershed and on the water surface is analyzed. We conclude
that the wildfires in CEZ could not cause a notable increase in the water concentration of 137Cs and 90Sr
outside the CEZ.
Keywords： Chornobyl Exclusion Zone, forest fires, 90Sr, 137Cs, modeling, atmospheric dispersion, rivers

62

The 10th Annual Symposium of the IER, Fukushima University / 福島大学環境放射能研究所 第 10 回成果報告会

P-37
Simulation of tritium releases into the atmosphere during the
Fukushima accident and into the ocean due to planned dischargeof treated water
Alexandre CAUQUOIN*1, Maksym GUSYEV2, KOMURO Yoshiki3, Hayoung BONG1, OKAZAKI Atsushi4,
YOSHIMURA Kei1
Institute of Industrial Science, The University of Tokyo, 2Institute of Environmental Radioactivity, Fukushima

1

University, 3Japan Agency for Marine-Earth Science and Technology, 4Institute for Advanced Academic
Research/Center for Environmental Remote Sensing, Chiba University*Corresponding author： cauquoin@iis.u-tokyo.ac.jp

Following the accident at the Fukushima Daiichi Nuclear Power Plant（FDNPP）in March 2011, large
quantities of radioactive materials were released into the atmosphere and ocean. Since the FDNPP
nuclear accident, Tokyo Electric Power Company（TEPCO）operators have been implementing measures
to reduce groundwater inflow into the FDNPP damaged reactor buildings while pumping water to coolthe nuclear reactors and fuel debris. The resulting huge water volume began the discharge into theocean from August 2023, after being treated by an Advanced Liquid Processing System（ALPS）toremove radionuclides for acceptable discharge levels except tritium. Tritium releases from the FDNPP
accident and the ALPS treated water raise questions about the impact on tritium in precipitation in
Japan, the removal time of anthropogenic tritium in groundwater and the oceanic transport of tritiumfrom released ALPS treated water.
In this two-part study, we present:（1）The modeling of tritium in precipitation during the FDNPP accident using an atmosphere global
climate model. We found good agreement with the tritium in precipitation observations in Japan for 2011
and subsequent years.
（2）A sensitivity simulation of tritium concentration in the ocean due to planned ALPS treated water
release in the next decades by TEPCO using an ocean global climate model. Simulated tritium
concentrations in the North Pacific Ocean vary between 0.01 and 3 Bq/m3, well below the natural tritium.
level（approximately 50 Bq/m3）
Keywords： tritium, global climate models, Fukushima nuclear power plant, atmosphere, ocean

63

はじめに
今回の成果報告会のテーマは「福島の森と海はどうなっているか」です。原発事故から10年以上を経て長期的なフェーズの研究対象として、福島大学環境放射能研究所では福島の森と海について重点的に取り組んできました。大部分の森林は除染が行われず、原発事故で放出された放射性物質がこの先も継続して存在し続ける可能性があります。帰還困難区域の避難指示解除が進んでいますが、森林と隣接する地域の避難指示解除も進むでしょう。里の豊かさを支えてきた森林からの恩恵の享受を回復できるかが大きな課題だと考えています。そのためには森林内での放射能の分布が時間経過とともにどのように変化してきたのかについて、従来からの研究を継続するとともに、将来的な変化についての仮説を視野に入れながら、研究を通じて見極めることが重要です。
もう一方の海については、2023年夏から開始された処理水放出により、関心が集まりました。ヒトや生態系への安全性には問題のない放出を行う計画ですが、中国への水産物輸出が滞るという問題が発生しています。東日本大震災からの復興の歩みを妨げることのないよう、科学的研究の観点からも新たな知見や情報の開示を進めていかねばなりません。処理水には除去ができないトリチウムが含まれていることから、トリチウムについての安全性や生態系内での挙動等についても関心が高まっています。トリチウムは宇宙線により生成され、天然にも存在しています。福島での人工的な放出の影響を評価するためには天然トリチウムの環境動態も継続的に観測し、バックグラウンドを把握する必要があります。
さて、森林と海とが河川を通じて栄養塩や有機物を輸送することなど、生物地球化学的な観点でさ
まざまなことが語られています。森林生態系では土壌生成や窒素固定によって生物が利用可能な栄養が生成されています。これらの一部が河川を通じて森林の外に運ばれ、下流地域や海洋にも恩恵をもたらします。約５億年前、原始の海から陸地に進出したカビと植物の連携が現在の豊かな大地のもととなっており、そしてそれらパイオニアの活動が今もなお続いているようです。放射性セシウムの動きを理解することは重要ですが、反対に放射能の動きから推定されるそもそもの自然のプロセスを理解することが今後一層重要性を増すと考えられます。例えば、トリチウム濃度は地下水の年代推定にも用いられ、地下水資源量の推定にも役立つ水文学的解析のツールとしても活用されています。これは、放射能が自然のプロセス理解に用いられる一つの例です。
成果報告会第10回の節目にこれまでの研究を振り返りながら、自然の理解や損傷した原子炉の廃炉など長期的課題を視野に今後の方向性についてご意見を賜りたいと思います。
福島大学環境放射能研究所
所長

1

難波

謙二

From Wed, February 28 to Thu, February 29, 2024