Chemical species of Al in a gypsum-treated Kitakami andosol

To examine the possibility that the Al-13 polymer ( [AIO(4)Al(12)(OH)(24)(H 2O)(12)](7+)) could be formed in soils after gypsum application, an analyti cal method using a cation exchange resin and Al-27 nuclear magnetic resonan ce (NMR) spectroscopy was applied to gypsum-treated Kitakami Andosol (fine, mixed, mesic, Andic Dystrochrept), The NMR spectra of the cation exchange resins which retained artificially synthesized hydroxy-Al, showed two broad peaks at 0 and 63 ppm, These results indicated that monomer and/or dimer A l and Al-13 polymers adsorbed on the cation exchange resin could be detecte d with Al-27 NMR, The amount of polymer Al increased by gypsum application in the Kitakami soil. The NMR spectrum of this resin showed only one peak a t 0 ppm indicating that the polymer Al formed in the gypsum treated Kitakam i soil was not the Al-13 polymer.