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Ligand Concentration Effects on Aluminum Complexation by a Chestinut Leaf Litter Extract
Author(s) -
Shotyk William,
Sposito Garrison
Publication year - 1990
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1990.03615995005400030055x
Subject(s) - protonation , dissolved organic carbon , chemistry , quenching (fluorescence) , ligand (biochemistry) , litter , fluorescence , analytical chemistry (journal) , aluminium , environmental chemistry , ion , ecology , biology , organic chemistry , biochemistry , receptor , physics , quantum mechanics
The quenching of fluorescence at an emission wavelength dependent on the ligand concentration was used to measure organically complexed Al at pH 4.5 across a range of dissolved organic carbon (DOC) concentrations of chestnut (Castanea sativa L.) leaf‐litter extract. Simultaneous measurements of total inorganic Al were made by a 15‐s reaction with 8‐hydroxyquinoline. These data were combined to calculate quasiparticle model complex stability coefficients ( c K T ) for Al binding. For the range of DOC from 26 to 150 g m −3 , the variation in the value of log c K T was not statistically significant. A conditional stability constant for a 1:1 quasiparticle Al/leaf‐litter complex was calculated after correcting c K T for Al hydrolysis and ligand protonation. Its mean value varied from 10 8.9 to 10 8.3 across the range of DOC investigated, but was also not significantly dependent on DOC according to statistical criteria. It was concluded that fluorescence quenching can be used to determine organically bound Al for an environmentally important range of leaf‐litter DOC concentrations.