Of course, in SRFA this should predominantly come from fulvic acid. However, the presence of lignin cannot be ruled out as the aromatic window is broad and covers the signature peak for lignin at 6.57 ppm. The second important piece of information is that the ratios of the A, B and C regions remain almost identical between spectra of SRFA and TRM-0522 samples, suggesting that the relative amounts of MDLT, CRAM, and complex polysaccharides remains consistent between the two samples. For 13 C NMR comparison, data was used from the U.S. geological survey . The most obvious difference between the C NMR spectra of the materials is a significant aromatic peak spanning 110-145 ppm in the SRFA spectra, a region in which only relatively minor resonances can be observed in the TRM-0522 spectra. This reinforces the lack of the relatively photolabile humic, fulvic, and lignin substances in TRM-0522, and suggests the material is unlikely to be photoreactive. While other regions in the C NMR spectra of the two samples are relatively similar, differences are noted with the increased peak height in regions attributable to sugars in TRM-0522 (when compared to aliphatic signals), and an increased peak height indicative of substances attributable to carbonyl functionalities in SRFA (when compared to aliphatic signals).