Chemical species of Al in a gypsum-treated Kitakami Andosol

Abstract

Abstract To examine the possibility that the Al13 polymer ([A104Al12(OH)24(H20)12]7+) could be formed in soils after gypsum application, an analytical method using a cation exchange resin and 27Al nuclear magnetic resonance (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-AI, showed two broad peaks at 0 and 63 ppm. These results indicated that monomer and/or dimer Al and Al13 polymers adsorbed on the cation exchange resin could be detected with 27Al NMR. The amount of polymer Al increased by gypsum application in the Kitakami soil. The NMR spectrum of this resin showed only one peak at 0 ppm indicating that the polymer Al formed in the gypsum treated Kitakami soil was not the Al13 polymer.