Source indicators of humic substances: an elemental composition, solid state C-13 CP/MAS NMR and Py-GC/MS study

Humic substances (HS) isolated from swamp water, surface soil, peat and bro wn coal were characterized using elemental composition, solid state C-13 CP /MAS NMR and Py-GC/MS analysis. A substantial amount of information with re gard to the source, maturity, depositional environment and degree of degrad ation of humic substances was obtained. The elemental composition, atomic r atio, C-13 NMR spectra and Py-GC/MS results indicated that vascular plant m atter is the main contributor to humic substances. Humic substances from sw amp water and from soil in the surrounding area of the swamp were found to be identical, suggesting that the swamp humic substances are derived from s urrounding soils. Humic substances from brown Coal were characterized by a higher degree of humification, including loss of polysaccharides, degradati on in lignin content and increase in aromaticity. Compared with humic subst ances from brown coal, the humic substances from peat showed a lower degree of humification and were considerably more aliphatic in nature. (C) 2000 E lsevier Science Ltd. All rights reserved.