Abstract: The dissolved organic matter (DOM) has complex biogeochemical characteristics that affect the carbon cycle, migration and transformation of pollutants. The sources and the key properties of DOM can be identified quickly by the spectral characteristics. Therefore, the DOM spectrum characteristics of biochar made from five kinds of typical biomass (apple branch, orange branch, peanut shell, rice straw and corn straw) prepared at the same pyrolysis temperature were explored by using ultraviolet-visible spectrum, three-dimensional fluorescence spectrum and fourier transform infrared spectrum. The results show that the dissolved organic carbon (DOC) of straw biochar is much higher than that of the other three biochars. Ultraviolet-visible spectrum analysis shows that the content of aromatic components in DOM of the five biochars was small, the humification degree was low, and hydrophilic components were dominant. Three-dimensional fluorescence spectrum analysis shows that the content of fluorescent components of straw biochar DOM was higher than those of wood biochar and shell biochar, and soluble microbial degradation products and humic acid were the highest in the proportion of fluorescent components. Fourier transform infrared spectroscopy shows that the DOM spectral characteristics of the five biochar species were similar.

Key words: biochar, biomass, dissolved organic matter, spectral property