Estimation of origin of lignin in humic DOM by CuO-oxidation

Ligneous components of aquatic humic solutes were analysed by cupric oxide (CuO) oxidation. Vanillyl, syringyl, and cinnamyl phenols were applied as tracers to indicate the contribution of lignin to the aquatic humic matter. The lake aquatic humic solutes were isolated from the dissolved organic matter (DOM) by the XAD technique at pH 2 and by the DEAE cellulose at natural acidity. The characteristic lignin-derived phenols classified the humic-solute samples into clusters reflecting the surrounding area of the aquatic environments. No, or at most only traces of, ligneous phenols were found from the effluent of the XAD-8 column. The aquatic humic matter isolated by the DEAE cellulose produced practically the same amount of ligneous phenols than the combined amount obtained from the humic- and fulvic-acid fractions isolated by the XAD technique from the same water sample. (C) 1997 Elsevier Science Ltd.