Evidence for a Phytotoxic Hydroxy-Aluminum Polymer in Organic Soil Horizons

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Science  01 Mar 1991:
Vol. 251, Issue 4997, pp. 1056-1058
DOI: 10.1126/science.251.4997.1056


The toxicity of A1 that has been mobilized in soil, streams, and lakes through acid deposition primarily has been attributed to mononuclear A1 species. Polynuclear A1 species are more toxic than mononuclear species, but they have not been considered to be significant in the environment. Aluminum-27 nuclear magnetic resonance (NMR) spectra of forested spodosol soil horizon samples show the presence of polynuclear A1O4A112(OH)24(H2O)127+. The AlO4A112(OH)24(H2O)127+ species accounted for 30 percent of the aqueous A1 observable by NMR, and this could make a significant contribution to the toxicity of the A1 in these soils.

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