Studies on the Revitalization of Radioactive-Contaminated Mushroom Log Forests: Focus on Shoots

Abstract

It has been more than 10 years since the accident at TEPCO’s Fukushima Daiichi Nuclear Power Plant. The issue of halting the use of hardwood mushroom log forests is a serious matter that continues to this day among the damage caused by radioactive contamination of forests. Mushroom log farmers and producers strongly desire to resume the use of local logs. To this end, they wish to know the radiocesium activity concentration of the logs in future harvest times. The author has been involved in various studies since 2014, aiming to understand the actual situation and predict future radioactive contamination of mushroom log forests, such as Quercus serrata (Konara oak). This chapter explains the basics of radioactive contamination of trees and the mechanisms and determinants of radiocesium uptake by log forests, mentioning the latest research and commentary on mushroom log forests included in this book. It also describes the identification method of current-year shoots, which has been the focus as an indicator of radiocesium absorption by mushroom log forests in studies so far, and reviews the achievements of the research to date.

Variability in radiocesium activity concentration in growing hardwood shoots in Fukushima, Japan

“…Consequently, understanding the frequency distribution characteristics of the radioactivity concentration in forest products obtained under certain conditions is very important for the effective management and monitoring of these resources. In this study, we investigated the variability in radiocesium activity concentrations in growing shoots of hardwood species, which has been utilized to establish indices of radiocesium absorption [10,11], with a particular focus on the hardwood bed logs that are commonly used in mushroom cultivation. The radiocesium activity concentration in the forest products has been demonstrated to follow a log-normal distribution [15,19].…”

“…For example, Kanasashi et al [9] established a strong and negative correlation between the exchangeable potassium present in soil and the radiocesium ( 137 Cs) activity concentrations in the growing shoots of Q. serrata. The observation of a constant relationship between radiocesium activity concentration of growing shoots (new branches) and that in woody stem means that the concentration in growing shoots are well suited for use as a proxy for the concentration in woody stems [10,11]. Based on this assumption, coppices situated on the potassiumrich soils may be well suited for the production of bed logs with low radiocesium contamination even in areas that were experienced radioactive fallout.…”

Variability in radiocesium activity concentration in growing hardwood shoots in Fukushima, Japan

“…Consequently, understanding the frequency distribution characteristics of the radioactivity concentration in forest products obtained under certain conditions is very important for the effective management and monitoring of these resources. In this study, we investigated the variability in radiocesium activity concentrations in growing shoots of hardwood species, which has been utilized to establish indices of radiocesium absorption [10,11], with a particular focus on the hardwood bed logs that are commonly October 5, 2023 13/23…”

“…For example, Kanasashi et al [9] established a strong and negative correlation between the exchangeable potassium present in soil and the radiocesium ( 137 Cs) activity concentrations in the growing shoots of Q. serrata . The observation of a constant relationship between radiocesium activity concentration of growing shoots (new branches) and that in woody stem means that the concentration in growing shoots are well suited for use as a proxy for the concentration in woody stems [10, 11]. Based on this assumption, coppices situated on the potassium-rich soils may be well suited for the production of bed logs with low radiocesium contamination even in areas that were experienced radioactive fallout.…”