Characterization of Dissolved Organic Matter Derived from Rice Straw at Different Decay Stages

摘要

This study characterized chemical and structural properties of dissolved organic matter (DOM) derived from different stages of rice straw decay under laboratory conditions. Ten different DOM samples were obtained and characterized using element composition analysis, Fourier-transform infrared spectroscopy, and 1H, 13C-nuclear magnetic resonance spectroscopy. The results showed that at the early stage of straw decay, lowweight-molecular components were dominant, such as carbohydrates, amino acids, and amino sugars. At the second stage, the contents of mono-, oligo-, and polysaccharides increased. At the later stage, aromatic products were dominant because of their strong recalcitrance for microorganisms. As straw decay proceeded, some small molecular chemicals (such as carbohydrates and acid amides) polymerized around the aromatic rings, suggesting that the DOM became more stable with decay time.