Radiocesium Contamination in Forests and the Current Situation of Growing Oak Trees for Mushroom Logs

Abstract

The radiocesium contamination in mushrooms and in mushroom logs is a matter of concern for the forestry industry. To know the contamination situation precisely and the future for mushroom log production, the 137Cs distribution in six fields cultivating oak trees in Tamura city, Fukushima, was investigated in 2015. The 137Cs concentration in new branches was found to correlate with that in the wood. This result suggests that the 137Cs concentration in tree trunks could be estimated without felling based on the 137Cs concentration in new branches. In addition, trees grown in one of the six fields was found to have very low 137Cs concentration even though the concentration of 137Cs in the soil was high. The impact of the nutritional conditions on the 137Cs absorption in the oak seedlings grown hydroponically was also investigated by a radiotracer experiment.