Exploration of radioactive cesium distribution in forest soil using gamma-ray spectral survey

2016 Fiscal Year Final Research Report

• Project/Area Number: 26660133
• Research Category: Grant-in-Aid for Challenging Exploratory Research
• Allocation Type: Multi-year Fund
• Research Field: Forest science
• Research Institution: Forestry and Forest Products Research Institute
• Principal Investigator: YASUDA Yukio 国立研究開発法人森林総合研究所, 森林防災研究領域, 主任研究員 (50353892)
• Co-Investigator(Renkei-kenkyūsha): OHTANI Yoshikazu 国立研究開発法人森林総合研究所, 森林防災研究領域, 研究専門員 (90353614) ; TSUBOYAMA Yoshio 国立研究開発法人森林総合研究所, 研究ディレクター (10353773)
• Research Collaborator: HIRUTA Toshihide 福島県・農林水産部, 森林整備課, 主査
• Project Period (FY): 2014-04-01 – 2017-03-31
• Keywords: 放射性セシウム / 森林土壌 / ガンマ線

Outline of Final Research Achievements

We attempted to develop a new technique to measure radioactive cesium concentration and its depth distribution in forest soil using energy spectra of gamma ray on forest floor. This technique will not require soil samplings and permit simple and quick measurements.
Gamma ray spectra measured on forest floor clearly showed energy peaks from radioactive cesium (Cs-137, Cs-134). Peak counts of gamma-ray photon calculated around the detected peaks had significant correlation with the amounts of radioactive cesium contained in soil per unit area. This linear relationship was able to apply to estimate the actual cesium amounts in Fukushima forests. However, estimations of the depth distribution using gamma-ray spectra were difficult, since radioactive cesium still remained near the surface of forest soil.

Free Research Field

森林気象学