FRACTIONATION OF FULVIC-ACIDS - CHARACTERISTICS AND COMPLEXATION WITHCOPPER

Two fulvic acid samples isolated from Suwannee river (International Hu mic Substance Society) and Feeitsuey reservoir were subjected to gelfi ltration chromatography (GFC) for molecular size fractionation. The GF C-eluted samples were separated into three groups corresponding to the molecular weight ranges: < 220, 220-1000, and 1000-4000. Fluorescence quenching techniques were employed for determining the conditional st ability coefficient and kinetic parameters of copper complexation with the three fractions of fulvic acids. Experimental conditions were pH 6, 5 x 10(-5) M total copper and 5 mg C litre(-1) of fulvic acids. The conditional stability coefficients of the fulvic acid fractions were in the order of 0.9-3.3 X 10(5) M(-1), and the forward and reverse rat e constants were in the order of 6.9-12.4 X 10(3) M(-1) s(-1) and 3.5- 8.0 X 10(-2) s(-1). Information could be useful in modelling copper tr ansport in the hydrosphere.