Application of radiocaesium microscale observation methodology to parmelioid lichen and ultrastructural analyses using STEM-EDS

Dohi, Terumi   ; Iijima, Kazuki  ; Machida, Masahiko  ; Suno, Hiroya*; Omura, Yoshihito*; Fujiwara, Kenso ; Kimura, Shigeru*; Kanno, Futoshi*

Lichens are well known for their ability to accumulate radiocaesium discharged into atmosphere in the thallus via wet and dry deposition over long periods of time. Therefore, lichens are often used as biomonitors for radiocaesium contamination levels. However, the exact location and chemical form of radiocaesium (ionic and/or particulate) in the thalli of lichen, are still unknown. By combining autoradiography, electron microscopy and quantum chemical calculation, we demonstrate the microscale localisation of radiocaesium within lichen thallus tissues.