Biology subjects

Kanao Koshikawa, M.

Publications and source records attributed to Kanao Koshikawa, M..

2 recordsLinked to original sources

bioRxiv2026

Radiocesium Uptake in Two Fungal Bed-cultivated Edible Mushroom Species in Forests in Fukushima, Japan

In Japan, mushrooms have long been valued as food resources, but the Fukushima nuclear accident disrupted production and shipment due to radiocesium contamination. Limited knowledge has particularly hindered outdoor fungal bed cultivation. To address this, we conducted cultivation experiments with Lyophyllum decastes and Lepista nuda across 14 broad-leaved deciduous forest sites in Fukushima Prefecture. Air dose rates at 1 m height ranged from 0.04 to 0.89 {micro}Sv/h. Radiocesium concentrations (combined 137Cs and 134Cs, expressed as Bq/kg at 90% water content) in fruit bodies were 0.4-12 (mean 2.3) for Ly. decastes and 0.2-43 (mean 8.1) for Le. nuda. Both species remained below Japans food safety threshold of 100 Bq/kg, indicating that safe cultivation is feasible across broad areas. Uptake patterns differed: concentrations in Ly. decastes correlated with contamination in litter and multiple soil layers, whereas in Le. nuda it correlated only with litter contamination. These findings suggest that clean soil fills for Ly. decastes and clean litter covers for Le. nuda could serve as mitigation strategies tailored to each species. Aggregated transfer factors (2.76 x 10-5 m2/kg for Ly. decastes and 6.60 x 10-5 m2/kg for Le. nuda) were lower than those reported for wild mushrooms. Overall, this study provides new insights into reducing radiocesium assimilation by cultivated mushrooms and supports the revival of outdoor fungal bed cultivation in contaminated landscapes.

ecology↗

bioRxiv2023

Simple ways to avoid collecting highly 137Cs-contaminated Aralia elata buds

Collection and cooking of wild vegetables have provided seasonal enjoyments for Japanese local people as provisioning and cultural ecosystem services. However, the Fukushima Daiichi Nuclear Power Plant accident in March 2011 caused extensive radiocesium contamination of wild vegetables. Restrictions on commercial shipments of wild vegetables have been in place for the last 10 years. Some species, including buds of Aralia elata, are currently showing radiocesium concentrations both above and below the Japanese reference level for food (100 Bq/kg), suggesting that there are factors decreasing and increasing the 137Cs concentration. Here, we evaluated easy-to-measure environmental variables (dose rate at the soil surface, organic soil layer thickness, slope steepness, and presence/absence of decontamination practices) and the 137Cs concentrations of 40 A. elata buds at 38 locations in Fukushima Prefecture to provide helpful information on avoiding collecting highly contaminated buds. The 137Cs concentrations in A. elata buds increased significantly with increases in the dose rate at the soil surface. Meanwhile, the 137Cs concentration in A. elata buds were not reduced by decontamination practices. These findings suggest that measuring the latest dose rate at the soil surface at the base of A. elata plants is a helpful way to avoid collecting buds with higher 137Cs concentrations and aid in the management of species in polluted regions.

ecology↗