玉米秸秆溶解性有机质分级组分的分子光谱

Molecular Spectra of Dissolved Organic Matter Fractions from Corn Straw

掌握秸秆源溶解性有机质(DOM)分级组分的光谱特性,并解析其在不同腐解阶段的荧光组分,是系统理解秸秆还田腐解的重要基础。采用DAX-8树脂对不同腐解阶段的玉米秸秆DOM进行分级分离,并通过紫外光谱、三维荧光光谱和同步荧光光谱法,对DOM分级组分进行光谱分析和荧光组分识别。结果表明:通过DAX-8树脂技术共获得疏水酸性组分(HOA)、疏水碱性组分(HOB)、亲水性组分(HIM)、酸不溶组分(AIM)和疏水中性组分(HON)5种组分。5种DOM组分的紫外吸收值几乎均随波长的增加而降低,HOA、HON和AIM组分逐渐在280nm附近形成吸收峰,HIM和HOB组分则无明显的特征性吸收峰。HOA、AIM和HIM组分中芳环被氧化程度逐渐占优,HON组分中芳环被还原程度逐渐占优;HOA组分的芳香性先降低后趋于稳定,AIM和HIM组分则与之相反,HOB和HON组分的芳香性则处于动态变化。HOA、AIM、HIM组分的团聚化和腐殖化程度均表现为先增加后趋于稳定,HOB和HON组分的团聚化和腐殖化程度呈波动趋势。HOA、HON和AIM组分主要向类胡敏酸物质转化,HOB组分则无明显的变化规律。综上,玉米秸秆腐解过程可不同程度地改变5种DOM组分的光谱特性和荧光组分组成,并最终使其趋向于形成更加稳定的类胡敏酸物质。

Mastering the spectral characteristics of dissolved organic matter(DOM)fractions from straw sources and analyzing their fluorescence components at different stages of decomposition is an important foundation for a systematic understanding of straw return decomposition.DAX-8 resin was used to classify and separate DOM from corn straw at different stages of decomposition,and spectral analysis and fluorescence component identification were performed on DOM graded components through UV spectroscopy,three-dimensional fluorescence spectroscopy,and synchronous fluorescence spectroscopy.The results showed that five components,namely hydrophobic acidic component(HOA),hydrophobic alkaline component(HOB),hydrophilic component(HIM),acid insoluble component(AIM),and hydrophobic neutral component(HON),were obtained through DAX-8 resin technology.The UV absorption values of the five DOM components almost all decreased with the increase of wavelength.The HOA,HON and AIM components gradually formed absorption peaks near 280 nm,while the HIM and HOB components had no obvious characteristic absorption peaks.The degree of oxidation of aromatic rings in HOA,AIM and HIM components gradually dominated,while the degree of reduction of aromatic rings in HON components gradually dominated.The aromaticity of HOA component decreased first and then tended to be stable.On the contrary,the aromaticity of AIM and HIM components changed dynamically.The degree of aggregation and humification of HOA,AIM and HIM components all increased first and then stabilized,while the degree of aggregation and humification of HOB and HON components showed a fluctuating trend.The HOA,HON and AIM components mainly converted to humic acid like substances,while the HOB components had no obvious change pattern.In summary,the decomposition process of corn straw can alter the spectral characteristics and fluorescence composition of the five DOM components to varying degrees,ultimately leading to the formation of more stable humic acid like substances.