MULTISITE ALUMINUM SPECIATION WITH NATURAL ORGANIC-MATTER USING MULTIRESPONSE FLUORESCENCE DATA

A revised method for determining conditional binding constants and sit e concentrations for Al and natural organic matter (NOM) is presented. By using total luminescence spectroscopy and multiresponse parameter estimation, the method is capable of resolving Al complexation at disc rete sites within NOM. The method is tested on a mixed model ligand sy stem of salicylic acid and 2-hydroxy-3-napthoic acid and recovers know n values for stability constants and ligand concentrations. The method is also applied to a sample of filtered river water at pH 4.02 and re veals three sites with conditional stability constants with log values of 5.77, 5.56 and 5.81 and standard deviation of 0.09. In addition, f or the same three sites the densities are determined to be 0.427, 0.44 8 and 0.354 mu mol mg(-1) of dissolved organic carbon (DOC), with a st andard deviation of 0. 14 mu mol mg(-1) of DOC. (C) 1998 Elsevier Scie nce B.V.