G.E. Maciel L.W. Dennis Patrick G. Hatcher 1981 <p><span>Nuclear magnetic resonance spectra (both&nbsp;</span>¹<span>H and&nbsp;</span>¹³<span>C) of humic acids from diverse depositional environments indicate the presence of aromatic chemical structures, most likely derived from lignin of vascular plants, and complex, paraffinic structures, most likely derived from algal or microbial sources. The latter components account for a major fraction of humic acid structures in both terrestrial and aquatic environments, suggesting that algae or microbes play a large role in humification of organic remains from both systems.</span></p> application/pdf 10.1016/0146-6380(81)90012-7 en Elsevier Aliphatic structure of humic acids; a clue to their origin article