Effects of litter feeders on the transfer of (137)Cs to plants

The effects of the Japanese horned beetle larvae on the transfer of (137)Cs from a contaminated leaf litter to the leaf vegetable, komatsuna (Brassica rapa var. perviridis) was studied. Feces of the larvae which were fed (137)Cs-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 (137)Cs 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 (137)Cs for the presence and absence of feces. Interactions between clay minerals and exchangeable (137)Cs in the soil beneath the litter layer may diminish the root uptake of (137)Cs. From these results, it was concluded that the effect of exchangeable (137)Cs released from feces was limited for the transfer of (137)Cs to plants if plant roots were not present in litter layers.