交替冻融对黑土可溶性有机质荧光特征的影响

土壤可溶性有机质(DOM)是土壤有机质研究中最有意义的量化指标,交替冻融作用能够影响土壤DOM的荧光特征.文章利用三维荧光分析交替冻融对黑土DOM光谱特征的影响,并基于光谱特征的改变,评价交替冻融对黑土活性腐殖质和腐殖程度的影响.研究表明,与未冻融样品相比,冻融样品DOM的紫外区类富里酸荧光峰发生红移,说明土壤中有机物分子芳香化程度增高,腐殖程度上升;部分冻融样品产生了类蛋白荧光峰,说明冻融过程中微生物降解活动增强;冻融样品的活性腐殖质含量和腐殖程度均较未冻融高,说明交替冻融作用增加了土壤肥力;紫外区类富里酸荧光峰值与可见区类富里酸荧光峰值的比值(r(a,c))与活性腐殖质含量之间、r(a,c)与腐殖程度之间,都存在显著的正相关关系(相关系数分别为0.88,0.77),说明r(a,c)可以评价黑土冻融后土壤活性腐殖质含量和腐殖程度的变化.

Effect freezing and thawing cycles on fluorescence characterization of black soil dissolved organic matter

Fluorescence characterization of soil dissolved organic matter (DOM), which is one of the most important indexes concerning study on soil organic matter, can be effected by freezing and thawing cycles. In this paper, the fluorescence characterization of black soil DOM under the effect of freezing and thawing cycles was studied, using three-dimensional excitation-emission-matrix fluorescence spectroscopic (EEM). Based on the transformation of fluorescence characterization, the influences of humification degree and active humus in black soil were analysed. The result showed, compared with untreated by freezing and thawing cycles, (1) The phenomena red-shift of UV fulvic-like was found in soil DOM. It meant that the aromatization and humification degree increased. (2) Protein-like fluorescence peak was observed in some soil samples, which meant microbial activity was enhanced. (3) Active humus and humification degree are the indexs of soil fertility. The content of TOC in the active humus rose, just the same as the value of humification degree. It meant that soil fertility was improved. (4) Compared with the ratio of UV: visible humic-like fluorescence (r(a,c)), there were positive correlations with the active humus and humification degree. It meant that r(a, c) of soil DOM was one of the indexs on active humus, humification degree and soil fertility effected by freezing and thawing cycles.