STUDIES ON THE NATURE OF SULFUR IN PEAT HUMIC ACIDS FROM THE FRASER-RIVER DELTA, BRITISH-COLUMBIA

Humic acid (HA) fractions from four peats in the Fraser River Delta were isolated in bulk to allow studies of organic S forms present. Elemental analysis of C-bonded S (C-S) and HI-reducible S confirmed much higher S contents in HAs formed under the influence of brackish water, and a dominance of C-S forms in all HAs examined. Acid hydrolysis studies indicated the presence of five distinct pools of organic S, varying in stability and oxidation state. Amino acid S in high-S HAs accounted for less than 4% of the C-S fraction. S-enrichment of HAs by bisulphide ion reaction was demonstrated, with most of the added S resistant to hydrolysis. X-Ray photoelectron spectroscopy (ESCA) analysis of high-S HAs (> 1% S) indicated changes in both oxidized and reduced pools following S-enrichment and following hydrolysis. One HA was fractionated into molecular size fractions and exhibited increased S content with decreasing molecular size. Precise characterization of S in HAs remains a rather intractable problem.