Micro-pixe study on sorption behaviors of cobalt by lichen biomass

Onuki, Toshihiko; Sakamoto, Fuminori  ; Kozai, Naofumi   ; Sakai, Takuro; Kamiya, Tomihiro; Sato, Takahiro; Oikawa, Masakazu*

Sorption behavior of Co by lichen biomass has been studied in the foliose lichen Permotrema tinctorum in solution between pH 3 and 5. Sorption of Co by P. tinctorum reached equilibrium within 24 hours. Co uptake was independent of solution pHs between 3 and 5. Two-dimensional distribution of Co indicates that the sorbed Co is distributed in upper and lower surfaces, and medullary layers at 1 day after contact with P. tinctorum. Highest density in the two-dimensional distribution of Co is obtained in the lower surface suggesting that Co is sorbed by melanin-like pigment contained in the lower surface. Interestingly, the density of Co in algal layer is lower than those in medullary layer. Two-dimensional distribution of Co does not correspond to Fe indicating that Co is not adsorbed on the Fe-containing minerals trapped on P. tinctorum. It is concluded that high accumulation of Co by P. tinctorum is caused by the sorption on not only both surfaces, but medullary layer.