[Quantitative fluorescence characterization of organic matter stability during chicken manure composting]

Due to its high sensitivity, good selectivity and nondestructive nature, fluorescence spectroscopy was widely applied to characterize the nature of dissolved organic matter (DOM) from different source since the last decade. In the present study, dissolved organic matter (DOM) extracted from chicken manure samples during composting progress was quantitatively characterized by fluorescence analysis techniques and mathematical analysis methods. The results showed that, the ratio between the fluorescence intensities at 330 nm (humic-like matter) and 280 nm(protein-like matter) (I330/I280) in synchronous-scan excitation mode spectra, the area of a fluorescence spectrum obtained by excitation at the blue wavelength of 465 nm(A470-640), and the ratio between the area of the last quarter (435-480 nm) and the area of the first quarter (300-345 nm) of the emission spectrum (A435-480 nm/A300-345 nm) by exciting the sample with ultraviolet radiation of 240 nm, all increased during composting, and the humification degree of compost increased as well. Three-dimensional excitation emission matrix fluorescence spectroscopy showed that the intensity of protein-like matter decreased during composting progress and diminished at the end, while that of fulvic-like matter increased all the time. The ratio between the intensity of the ultraviolet fulvic-like fluorescence (Peak A) and that of the visible fulvic-like fluorescence gamma (A, C) showed an overall significant downward trend during composting, but fluctuated in the progress. The correlation analysis showed that, I330/I280, A470-640 and A435-480 nm/A300-345 nm were all significant correlative, while gamma (A, C) was not correlative with the above-mentioned three parameters at 0. 05 level due to effect by other factors. The results show that, I330/I280, A470-640 and A435-480 nm/A300-345 nm can be effectively used in the process of the evaluation of humification degree during composting.