Reduction of radiocesium in Shiitake (Lentinula edodes) bed logs and fruit bodies by culture with nanoparticle insoluble Prussian blue dispersion liquid and cesiumsorb filter sheet

Abstract

For the cultivation of Shiitake (Lentinula edodes) on log woods cultivated in laying yards contaminated by radioactive matter, we examined the movement of radiocesium in the log woods and the effectiveness of radiocesium remediation measures. Shiitake mushrooms grown on radiocesium-contaminated logs treated with nanoparticle insoluble Prussian blue (NPB) showed lower radioactivity than those grown on untreated radiocesium-contaminated logs. For log woods with radiocesium concentration of approximately 250 Bq/kg soaked in NPB dispersion liquid, the radiocesium concentration of harvested fruit bodies was 40 Bq/kg or less. In a second experiment, the use of a cesiumsorb filter (CSF) sheet as an overlay on a radioactive matter-contaminated laying yard (spatial dose rate, 0.19 mSv/h) produced a significant decrease in radiocesium in the fruit bodies after 15 to 18 months compared to placing bed logs directly on contaminated soil (with CSF sheet, 4.0 ± 1.8 Bq/kg; directly on contaminated soil, 7.8 ± 4.0 Bq/kg). Furthermore, CSF sheet was shown to specifically adsorb radiocesium from soil (soil, 764 Bq/kg; CSF sheet, 4,735 Bq/kg). Our findings will contribute to the promotion of good practices for Shiitake mushroom cultivation.