小麦秸秆堆肥水溶性有机物的结构和组成演变

堆肥是小麦秸秆资源化利用重要的途径之一，然而目前关于秸秆单一物料堆肥的研究较少。水溶性有机物（DOM）被普遍认为是堆肥中最活跃的有机组分，因此探讨DOM的演变特征可有效评价秸秆的腐熟过程。以小麦秸秆好氧堆肥过程中的DOM为研究对象，利用总有机碳、紫外-可见光光谱（UV-Vis）、三维荧光光谱（EEM）结合平行因子（PARAFAC）分析方法，阐明小麦秸秆堆肥过程中DOM的含量、结构和组成的演变特征。结果表明：堆肥过程中DOM的有机碳含量降低了23%，说明DOM是堆肥中活跃的有机质组分。值得注意的是，堆肥前期DOM微生物降解最为剧烈。UV-Vis谱图显示DOM光谱随堆肥进行不断降低，表明堆肥过程芳香族物质不断降解。EEM光谱显示出显著的荧光峰演变趋势，由堆肥前期较强的类蛋白荧光峰（D，E）演变为堆肥后期较强的类腐殖质荧光峰（H），表明堆肥过程DOM的物质组成发生改变。通过光谱参数SUVA₂₅₄和HIX的观测，发现随着堆肥进行，DOM的芳香度和腐殖化程度呈现动态变化，整体呈增强趋势。由此可推测堆肥过程DOM降解的成分主要为非腐殖质，而腐殖质类物质的相对含量则不断提升、整体芳构化和腐殖化程度增加。EEM-PARAFAC进一步定量分析了DOM组分的演变特征。随着堆肥的进行，DOM中的类蛋白物质（C3）相对含量显著降低（~46%），而类富里酸（C1）和类腐殖酸（C2）物质相对含量分别提高了45%和80%。DOM中的组成由堆肥初期的C1∶C2∶C3=41∶17∶42演变成堆肥后期的53∶27∶20。结果揭示出堆肥过程中类蛋白物质发生显著的降解，而类腐殖质则由于分子聚合生成作用和微生物降解速率较慢等因素逐渐演变成堆肥DOM的主要组分。相关性分析结果显示HIX与C1和C2均呈现极显著正相关（r=0.806~0.853），表明腐殖化指数(HIX)可有效指示DOM的腐殖质物质组成。本研究结果可为进一步优化小麦秸秆堆肥条件，改善秸秆有机肥质量提供科学依据。

Compositional and Structural Evolutions of Dissolved Organic Compounds During Composting of Wheat Straw

Composting is one of the effective ways for wheat straw utilization.However,the relevant study on solewheat straw composting is still constrained.Dissolved organic matter(DOM)is widely believed to be the most activeorganic matters during composting,and then it can be seen as an indicator for investigating the composting process of straw materials.In this study,total organic carbon analysis,UV-Vis spectroscopy and EEM-PARAFAC were applied to study the evolutions of abundance,structure and composition of DOM during wheat straw compost.The dissolved organic carbon(DOC)of DOM were decreased by 23%,with a major decrease in an early stage of composting,suggesting DOM was an active portion of organic matters.UV-Vis spectra analysis showed that the absorbance of DOM was significantly decreased after composting,suggesting the degradation of aromatic compounds.DOM present obvious changes of fluorescence peaks in EEM during composting,where the strong protein-like peaks were transformed to the humic-like peaks.It indicated that the composition of DOM was changed.SUVA 254 and HIX values of DOM varied dynamically,but both were generally increased with composting.It implied that the aromaticity and humification degree of DOM were transformed to be stronger after composting.These results revealed that the non-humic matters were readly to be degraded,and the relative content of humic matters was elevated,resulting in an increase of aromaticity and humification of DOM during composting.EEM-PARAFAC analysis showed that the relative abundances of protein-like compounds(C3)were decreased by 46%,while the relative abundances of fulvic acid-like(C1)and humic acid-like(C2)substances were increased by 45%and 80%.The composition of DOM had been transformed from C1∶C2∶C3=41∶17∶42 to 53∶27∶20 during composting.The results revealed that the protein-like compounds were dominantly degraded,while humic-like matters were somewhat formed or slowly degraded and transformed to be the dominant one.The correlation analysis showed strong positive correlations between HIX,C1 and C2(r=0.806~0.853),suggesting that HIX could effective reflect the humic characteristics of compost DOM.The results obtained here are greatly help for better controlling wheat straw composting and improving the number of straw manures.