秸秆还田对旱田黄土可溶性有机质三维荧光光谱的影响

以西北旱田黄土为研究对象，分析玉米秸秆还田前后黄土可溶性有机质(DOM)的三维荧光光谱差异，探讨黄土腐殖化程度的变化情况及对Pb(Ⅱ)赋存形态的影响。实验结果表明：黄土DOM的荧光峰主要分布在λ_ex/em=240～270/280～340区域和λ_ex/em=325/450附近，分别归属为紫外区类富里酸以及可见光区类富里酸和腐殖酸类物质的荧光峰。秸秆还田60 d后，紫外区类富里酸荧光峰值增加，在λ_ex/em=250/440附近和λ_ex/em=320～350/350～400区域出现新的腐殖酸荧光峰。黄土腐殖化程度随秸秆还田时间的延长而增加，Pb(Ⅱ)的生物有效性随腐殖化程度的增加而降低。三维荧光光谱可以有效表征秸秆还田前后黄土DOM的变化特性。

Effect of Straw Incorporation on Three-Dimensional Fluorescence Spectrum of Dissolved Organic Matter in Arid Loess

The three-dimensional fluorescence spectrum was used to investigate the fluorescence characterization of dissolved organic matter (DOM) before and after straw incorporation in arid loess, and the variation of humification degree and Pb(Ⅱ) speciation were illustrated. The results showed that the fluorescence peaks of loess appears at the regions of λ_ex/em=240～270/280～340 and λ_ex/em=325/450, referred as UV fulvic-like fluorescence, and visible fulvic-like and humic-like fluorescence, respectively. After straw incorporation for 60 days, the intensity of UV fulvic-like fluorescence peaks increases, and novel humic-like fluorescence peaks appears around the region of λ_ex/em=250/440 and λ_ex/em=320～350/350～400. The longer time of straw incorporation would accelerate the humification degree of loess and decrease the bioactivity of Pb(Ⅱ). The three-dimensional fluorescence spectrum is appropriate for characterization identification of DOM in arid loess before and after straw incorporation.