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Aluminum‐Binding Ability of Soluble Organics in Douglas Fir Litter and Soil

1991; Wiley; Volume: 55; Issue: 5 Linguagem: Inglês

10.2136/sssaj1991.03615995005500050037x

1435-0661

Shuk‐Ching Tam, J. G. McColl,

Soil and Unsaturated Flow

Abstract Organic matter from litter and soil are important metal‐mobilizing agents. This study was conducted to characterize the Al‐binding abilities of soluble organics from both Douglas fir litter and soil (fine‐loamy, mixed, mesic Ultic Haploxeralf). A modified ion‐pairing chromatographic technique was used to differentiate organics according to their Al‐binding abilities. Further identification with high‐performance liquid chromatography (HPLC) found gallic, catechol, salicylic, and phthalic as the most strongly Al‐binding ligands among the aromatic acids identified. Moderate binding ability was exhibited by 3,4‐dihydroxybenzoic acid; benzoic, vanillic and 4‐hydroxybenzoic acids were the least strongly binding. The identified aliphatic acids (shikimic, oxalic, succinic, fumaric, malic, and citric) were not differentiated, due to their weaker binding to Al and to the fractionation column. For the unidentified organics, suggestions are made on their functional structure that will be useful for more exhaustive studies. Greater amounts of Al‐binding ligands were found in litter than in soil. The effect of different litter types on Al solubilization in underlying mineral soils can be obtained by comparing their Al‐fractionation characteristics.