THE INFLUENCE OF PULP AND PAPER-MILL EFFLUENTS ON THE COMPOSITION OF THE HUMIC FRACTION OF AQUATIC ORGANIC-MATTER

The humic fraction of dissolved organic matter was isolated from three sites of River Vouga (Portugal) and its lagoon, corresponding to unpo lluted water and water contaminated with pulp mill effluent. Humic sub stances were characterized by elemental analysis, Fourier transform in frared spectroscopy, CPMAS-C-13-NMR spectroscopy and potentiometric ti tration. The fulvic acids isolated from the most contaminated site exh ibit several structural features characteristic of lignosulphonic acid s, such as a high sulphur content, the presence of sulphonic groups, h igher phenol and methoxyl contents, higher aromaticity and lower carbo xyl content than the fulvic acids upstream of the discharge from the p ulp mill effluent. The humic substances further downstream still show some of those structural characteristics but they are preferentially s hown in the humic acids than in the fulvic acids. These results highli ght the importance of the contribution of anthropogenic sources of org anic matter to the composition of humic substances from surface waters . (C) 1998 Elsevier Science Ltd. All rights reserved.