Radiocaesium accumulation capacity of epiphytic lichens and adjacent barks collected at the perimeter boundary site of the Fukushima Dai-ichi Nuclear Power Station

Dohi, Terumi   ; Omura, Yoshihito*; Yoshimura, Kazuya  ; Sasaki, Takayuki*; Fujiwara, Kenso ; Kanaizuka, Seiichi*; Nakama, Shigeo ; Iijima, Kazuki  

We investigated the radiocaesium content of nine epiphytic foliose lichens species and the adjacent barks at the boundary of the FDNPS six years after the accident in 2011. The Cs-inventory were determined to compare Cs retentions of lichens and barks under the same growth conditions. The Cs -inventory of lichens were respectively 7.9- and 3.8-times greater than the adjacent barks. Furthermore, we examined the Cs distribution within these samples using autoradiography (AR) and on the surfaces with an EPMA. AR results showed strong local spotting and heterogeneous distributions of radioactivity in both the lichen and bark samples, although the intensities were lower in the barks. In addition, radioactivity was distributed more towards the inwards of the lichen samples than the peripheries. This suggests that lichen can retain Cs that is chemically immobilized in particulates intracellularly, unlike bark.