Characterization and differentiation of humic acids and fulvic acids in soils from various regions of China by nuclear magnetic resonance spectroscopy Original Research Article

Four humic acids (HAs) and four fulvic acids (FAs) isolated from soils of various regions of China were characterized by using 1H NMR and cross-polarization magic angle spinning (CPMAS) 13C NMR spectra, the positions of the major spectral bands of these NMR spectra were similar to each other. It was found that there are definitive compositional and structural differences between HAs and FAs from the same soil and between HAs or FAs from different soils. In particular the lime concretion fluvioaquic soil HA and FA with highest aromaticity are obviously different from others.