2006 Volume 55 Issue 10 Pages 743-748
Pteris vittata L. has come into use as a technology of phytoremediation due to its hyperaccumulation ability of As. The distributions of arsenic and potassium in roots were examined by synchrotron radiation (SR)-XRF imaging; and the valence change from the top to the base of roots was revealed for the first time by As K-edge XANES. Freeze-drying technique was adopted as an effective preparation method for the handling of roots. The vertical beam size was set to 300 μm by a spherical focusing mirror and the horizontal beam size was adjusted to 2800 μm by the slits. By adopting this wide X-ray beam, the elemental distribution along the roots can be appropriately evaluated despite their winding shapes. It was found that the concentration of arsenic became higher from the top to the base of the roots, while that of potassium remained almost constant. Furthermore, the oxidation state of arsenic at the top of the roots was dominantly As(III), while that at the base was As(V).
