三维荧光光谱荧光峰位置和荧光强度可表征荧光物质的类型和浓度, 被广泛应用于溶解性有机质(DOM)性质的研究中。 为探讨退耕还湿后不同植物群系条件下的土壤特征, 指导退耕还湿工作, 本研究通过采集榆树、 松江柳、 猪毛蒿、 芦苇、 灰脉薹草、 香蒲6种典型植物群系的表层土壤, 应用三维荧光光谱-平行因子分析法, 测定土壤DOM的荧光光谱, 分析6种植物群系土壤中DOM的来源和组成。 结合土壤理化指标, 进一步分析土壤DOM有机组分的影响因素。 结果表明: 6种植被类型土壤的腐殖化指数(HIX)差异不大, 其中湿生芦苇群系土壤腐殖化程度显著高于旱生猪毛蒿群系。 土壤DOM的荧光指数(FI₃₇₀)均介于陆生源特征值(1.4)和自生源特征值(1.9)之间, 说明其来源既由微生物活动产生, 也有植物凋落物及根系分泌物的输入。 灰脉薹草群系和香蒲群系土壤的FI₃₇₀和生物指数(BIX)相对较高, 表明两者具有相对较强的自生源特征, 而芦苇群系和猪毛蒿群系的陆生源特征相对较高。 6种植物群系土壤DOM中共识别出3个有机组分: 类富里酸组分(C1)、 类胡敏酸组分(C2)和类蛋白组分(C3)。 芦苇群系土壤DOM相对浓度较高, 其次为香蒲群系, 灰脉薹草群系相对较低。 除芦苇群系外, C3组分在各植物群系土壤中均占有相对较高的比例, 其次为C1, C2相对较低, 反映出表层土壤DOM中小分子物质相对丰富, 腐殖化程度不高。 不同植物群系土壤pH值差异不显著, 旱生环境具有较高的土壤容重, 而湿生环境土壤含水量和阳离子交换量较高。 木本植物群系土壤总有机碳、 总氮、 总磷、 总钾含量均高于草本植物群系。 土壤容重、 含水量及阳离子交换量可显著影响土壤DOM有机组分结构。 因此, 退耕还湿过程中增加湿生草本植物面积可在一定程度上提高土壤腐殖化程度。

The peak position and intensity of three-dimensional fluorescence spectroscopy can be used to characterize the type and concentration of fluorescent substances, which is widely used in the study on dissolved organic matter (DOM) properties. In order to study the soil characteristics of different plant formations and guide the work of reverting farmland to wetland, the surface soil of six typical plant formations of Ulmus pumila, Salix sungkianica, Artemisia scoparia, Phragmites australis, Carex appendiculata, and Typha Orientalis were collected in this study, and the fluorescence spectroscopy of soil DOM was determined, the source and composition of soil DOM of the six plant formations were analyzed by three-dimensional fluorescence spectroscopy with parallel factor analysis method. Combined with physiochemical soil indexes, the influencing factors of soil DOM organic components were further analyzed. The results showed that there was no significant difference in the humification index of the six plant formations, the humification degree of the hygrophyte Phragmites australis formation was significantly higher than that of the xerophyte Artemisia scoparia formation. The fluorescence index of soil DOM was between the terrestrial eigenvalue (1.4) and the autochthonous eigenvalue (1.9), indicating that the source of soil DOM was not only generated by microbial activities, but also by the input of plant litter and root exudates. The fluorescence index and biological index of the soil in the Carex appendiculata formation and the Typha orientalis formation were relatively high, which indicated that the two formations had relatively strong autochthonous characteristics, while the terrestrial characteristics of the Phragmites australis formation and the Artemisia scoparia formation were relatively high. Three organic components, fulvic-acid-like component (C1), humic-acid-like component (C2) and protein-like component (C3), were identified from soil DOM of the six plant formations. The soil DOM relative concentration of Phragmites australis formation was higher than that of Typha orientalis formation, and that of Carex appendiculata formation was lower. Excepting for the Phragmites australis formation, C3 accounted for a relatively high proportion in the soil of each plant formation, followed by C1 and C2, which reflected that the surface soil DOM was relatively rich in small molecular substances, and indicated that the degree of humification was not high. There was no significant difference in soil pH value among different plant formations. The dry environment had higher soil bulk density, while the wet environment had higher soil water content and cation exchange capacity. The contents of soil total organic carbon, total N, total P and total K in woody plant formation were higher than those in herbaceous plant formation. Soil bulk density, water content and cation exchange capacity could significantly affect the soil DOM organic component structure. Therefore, increasing the area of hygrophyte herbage in the process of reverting farmland to a wetland can improve the degree of soil humification to a certain extent.