Insight into the composition and evolution of compost-derived dissolved organic matter using high-performance liquid chromatography combined with Fourier transform infrared and nuclear magnetic resonance spectra

Size exclusion chromatography and reversed-phase high-performance liquid chromatography (RP-HPLC) were combined with Fourier transform infrared spectra (FTIR) and nuclear magnetic resonance (NMR) based on two dimensional (2D) hetero-spectral correlation spectra techniques to fractionate compost-derived dissolved organic matter (DOM) and determine how size- and hydrophobicity-distinguished fractions differ in the composition and evolution. The results showed that the compost-derived DOM was comprised of protein- and humic-like species. The low apparent molecule weight (AMW) protein-like components were enriched in CCH3 and NCO, and showed more bioreactivity compared with the high AMW counterpart. The hydrophobic and hydrophilic protein-like components both consisted of CCH3 and NCO. However, the relatively hydrophilic protein-like components were more easily consumed. As to the humic-like species, the relatively hydrophilic components were slightly larger than the relatively hydrophobic ones. The high AMW and relatively hydrophilic humic-like components were high in CH, OCH3, NCO, NH, COO, OH and aromatic C. The low AMW and relatively hydrophobic humic-like components were enriched in CCH3 and NCO, and were easily biodegraded during composting. 2D hetero-spectral correlation spectra techniques enhance the characterization of DOM and provide a promising way to elucidate the environmental behaviors of DOM.