“…In the forest the fruit-bodies of edible and inedible mushrooms tend to grow after rain events. The rain water dissolves radioactive Cs in the litter zone 19 . Some portion of the dissolved radioactive Cs is transported directly to the fruit-body, causing excess accumulation of radioactive Cs in the fruit-body rather than through hyphae.…”
This paper presents the accumulation process of radioactive Cs in edible mushrooms. We here first report the direct accumulation pathway of radioactive Cs from contaminated wood logs to the fruit-bodies of shiitake mushrooms through the basal portion of the stipe. In this pathway, radioactive Cs is not transported through the hyphae. This pathway results in a high accumulation of radioactive Cs in the fruit-body, more by the excess accumulation of radioactive Cs from the wood logs than that through the hyphae. We grew the fruit-bodies of Shiitake mushroom from radioactive-Cs-contaminated wood logs. The spatial distributions of radioactive Cs and Prussian blue as a tracer of interstitial water in the cross section of the wood log measured after the harvest of the fruit-body from the inoculated sawdust spawn area indicated that some fraction of the radioactive Cs and Prussian blue were transported directly to the basal portion of the stipe during the growth of the fruit-bodies.
“…In the forest the fruit-bodies of edible and inedible mushrooms tend to grow after rain events. The rain water dissolves radioactive Cs in the litter zone 19 . Some portion of the dissolved radioactive Cs is transported directly to the fruit-body, causing excess accumulation of radioactive Cs in the fruit-body rather than through hyphae.…”
This paper presents the accumulation process of radioactive Cs in edible mushrooms. We here first report the direct accumulation pathway of radioactive Cs from contaminated wood logs to the fruit-bodies of shiitake mushrooms through the basal portion of the stipe. In this pathway, radioactive Cs is not transported through the hyphae. This pathway results in a high accumulation of radioactive Cs in the fruit-body, more by the excess accumulation of radioactive Cs from the wood logs than that through the hyphae. We grew the fruit-bodies of Shiitake mushroom from radioactive-Cs-contaminated wood logs. The spatial distributions of radioactive Cs and Prussian blue as a tracer of interstitial water in the cross section of the wood log measured after the harvest of the fruit-body from the inoculated sawdust spawn area indicated that some fraction of the radioactive Cs and Prussian blue were transported directly to the basal portion of the stipe during the growth of the fruit-bodies.
“…Regarding the first possibility, the generation of soluble 137 Cs in the litter layer would be a predominant factor. Several studies have shown that dissolved 137 Cs in soil was highest at the surface litter layer [ Kliashtorin et al ., ; Nakanishi et al ., ] and that more than half of the radiocesium adhered to the litter could be solubilized by soaking in water [ Clint et al ., ; Sakai et al ., ]. Based on these reports, considerable 137 Cs _dis could be desorbed from litter in flooding areas.…”
Dissolved radiocesium concentrations in river water in a high‐dose‐rate forest watershed in Fukushima Prefecture were investigated under base flow and storm flow conditions. Under base flow conditions, dissolved 137Cs concentrations in water (Bq/L) were relatively high in summer, and these levels were higher than particulate 137Cs concentrations (Bq/L). Under storm flow, particulate 137Cs concentration became dominant as the suspended solid concentration increased. Throughout the monitoring period, dissolved 137Cs concentrations in water (Bq/L) were higher under storm flow than base flow conditions and were positively correlated with runoff intensity. Factors influencing changes in dissolved 137Cs concentrations were investigated by measuring the 137Cs concentration of suspended solid (Bq/kg) and dissolved 137Cs of unsaturated soil water, throughfall, and rainfall, together with other main solute concentrations. The 137Cs concentration per unit weight of suspended solids in river water was not strongly correlated with runoff intensity. Additionally, dissolved 137Cs concentrations of soil water, groundwater, and rainfall were not detected, while higher dissolved 137Cs concentrations were detected in throughfall than river water. K+ concentrations were higher under storm flow than base flow, and dissolved organic carbon increased toward the peak flow rate. These findings suggested that one main factor influencing generation of dissolved 137Cs in the river water was leaching from organic material in flooded areas. However, further investigation is needed to clarify the dominant source of dissolved 137Cs in river water.
“…The increase in the yield could be caused by the release of nutrients resulting from the decomposition of the 137 Cs-intact-litter by the beetle larvae; such release of nutrients like nitrogen, phosphorus, and potassium from leaf litter through decomposition has been demonstrated 8 , 9 . It was also possible that release of 137 Cs occurred, as leaching of 137 Cs from leaf litter after being submerged in water has been reported 10 , 11 . Figure 2 The amounts of harvested komatsuna from the PM (a base potting mix), PM-L (PM with the 137 Cs-intact-litter) and PM-F (PM with the decomposed-litter-mixture) potting mixes.…”
The effects of the Japanese horned beetle larvae on the transfer of 137Cs from a contaminated leaf litter to the leaf vegetable, komatsuna (Brassica rapa var. perviridis) was studied. Feces of the larvae which were fed 137Cs-contaminated leaf litter were added to a potting mix in which komatsuna plants were cultivated. The presence of feces increased the harvest yield of komatsuna, suggesting that feces provided nutrients for the plant growth. In addition, the amount of exchangeable 137Cs in leaf litter was experimentally confirmed to be enhanced by the presence of feces which were excreted by larvae feeding. However, there was no difference in the soil-to-plant transfer factor of 137Cs for the presence and absence of feces. Interactions between clay minerals and exchangeable 137Cs in the soil beneath the litter layer may diminish the root uptake of 137Cs. From these results, it was concluded that the effect of exchangeable 137Cs released from feces was limited for the transfer of 137Cs to plants if plant roots were not present in litter layers.
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