Elucidation of radiocesium-bearing particles in mountain lake sediments based on microscopic material science

2022 Fiscal Year Final Research Report

• Project/Area Number: 20K15215
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 31020:Earth resource engineering, Energy sciences-related
• Research Institution: Hokkaido University
• Principal Investigator: Kikuchi Ryosuke 北海道大学, 工学研究院, 助教 (50832854)
• Project Period (FY): 2020-04-01 – 2023-03-31
• Keywords: 放射性セシウム / 粘土鉱物 / 土壌 / 湖底堆積物 / 放射能 / 汚染土壌 / XRD / TEM

Outline of Final Research Achievements

In order to understand the migration behavior of radionuclides at the ground surface after the accident of Fukushima Daiichi Nuclear Power Plant, it is necessary to examine the characteristics of radiocesium (RCs) bearing particles and their regional dependences on local geology. In this study, host minerals of RCs in soil and lake sediments collected from several sites of Fukushima Prefecture and an isolated mountain lake were examined by using nano & micro analytical techniques (IP-autoradiography, SEM, FIB-TEM). Furthermore, by quantitatively evaluating both the sediments and the radioactive particles contained in them, the regional dependence of the RCs host materials was elucidated.

Free Research Field

鉱物学

Academic Significance and Societal Importance of the Research Achievements

原発事故後の継続的なモニタリング調査によって水や土壌中、湖底堆積物、水棲生物の放射線量の変遷は明らかになっているものの、どうしてそのような値になっているのかは十分に説明できていない。これは反応に関与する微小な物質の正体が不明確であることに由来しており、本研究は、土壌中や湖底堆積物中で放射性Csを固定しているミクロな物質を直接的に検出・分析を行ったことで、土壌中あるいは湖底での堆積物と水、あるいは周辺の生物との間での反応過程をより明確化することが出来る。