<Original>Distribution of Metal Elements in Wood Impregnated with Aqueous Solutions of Metal Salts as Determined by SEM-EDXA

Abstract

Distribution and concentration of salts in the wood of three species, all treated with aqueous salt solutions of Cr, Cu or Zn to the longitudinal direction of the airdried wood by capillary pressure, were determined using the SEM-EDXA technique. In the line analysis the X-ray intensities varied widely with positions analysed since the rough surface structure of wood caused incomplete detection of X-rays. However, when the scanning line was put along the intercellular layer between the regularly oriented radial files of tracheids, a smooth curve was obtained. In this case overall trends of curves obtained were coincident with the results of the point analysis. The line-scan curve took a peak on the initiatively penetrated cell and gradually lowered at its surrounding region. Deposition of the salt could be seen frequently on the inner surface of the cell wall of the penetrated cell. From the gentle gradient of metal concentration in the surrounding region it was shown that the metal-distribution in this region was attributed to the ionic diffusion through the cell wall, not to the lateral liquid-flow through the lumen-pit system. The smooth curves were drawn across the different cell types, the multiseriate rays and across the annual ring boundary. Hence, it was concluded that the ionic diffusion through the cell wall proceeded uniformly from the penetrated cells to their surrounding regions.