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

地衣類へのCoの収着挙動に関するマイクロPIXEによる研究

大貫 敏彦; 坂本 文徳  ; 香西 直文   ; 酒井 卓郎; 神谷 富裕; 佐藤 隆博; 及川 将一*

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

葉状地衣類(Permotrema tinctorum)へのCoの収着機構をPIXEによる地衣類断面における元素の2次元分布測定に基づき検討した。Coの収着は24時間以内に平衡に達した。地衣類の断面におけるCoの分布から、Coは地衣類の表面及び地衣体部分に分布していた。中でも、地衣類の裏面に濃集していた。しかし、Coは葉緑体付近には濃集していなかった。また、Coは表面に捕捉された鉄鉱物には濃集していなかった。これの結果から、Coの地衣類への高い収着は地衣類の表面ばかりでなく地衣体部分への濃集に起因すると考えられる。

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.