Fluorescence Spectral Characteristics of Soil Dissolved Organic Matter in the River Wetland of Northern Cold Region, China
SHI Chuan-qi1, LI Yan2, HU Yu3, YU Shao-peng1*, JIN Liang2, CHEN Mei-ru1
1. Heilongjiang Province Key Laboratory of Cold Region Wetland Ecology and Environment Research, Harbin University, Harbin 150086, China
2. Institute of Plant Nutrition, Resources and Environment, Beijing Academy of Agriculture and Forestry Sciences, Beijing 100097, China
3. College of Resource and Environment, Northeast Agricultural University, Harbin 150038, China
摘要： 溶解性有机质（DOM）是土壤中活跃的有机成分，其来源和组成可指示土壤腐殖化程度及与外部环境间的相关关系。为科学地监测与评价湿地土壤环境质量，采集黑龙江省碾子山雅鲁河国家湿地公园内不同植被条件下的表层（0~20 cm）土壤，应用三维荧光光谱-平行因子分析法，测定DOM荧光光谱，并进一步分析土壤理化指标对DOM组成的影响。结果表明：5种植被类型（包括9种群系）条件下土壤DOM腐殖化指数在2.562~9.052之间，落叶阔叶林和落叶阔叶灌丛土壤腐殖化程度高于草甸，其次为沼泽，水生植被最低；荧光指数介于1.407~1.586，土壤DOM来源兼具外生源和自生源特征，落叶阔叶林和芦苇[Phragmites australis (Cav.) Trin. ex Steud.]沼泽表现为明显的外生源特征，而水生植被及稗[Echinochloa crus-galli (L.) P. Beauv.]沼泽具有明显的自生源特征；生物指数在0.482~0.662范围内，新近自生源贡献率均较低。土壤DOM中识别出3类5种有机组分，类腐殖质（紫外类富里酸和可见类富里酸）相对比重最大，外生源特征明显的土壤样品中含量多；其次为类蛋白质（类酪氨酸和类色氨酸），自生源特征较强的土壤样品中含量多；类腐殖酸（胡敏酸）最低，多存在于旱生-中生环境中。土壤含水量、pH值、总有机碳含量对DOM组成具有显著或极显著的影响，3项理化指标与类蛋白质含量成正相关，与类腐殖质含量成负相关，含水量、总有机碳含量与类腐殖酸含量成负相关。总体上看，在该湿地公园内，落叶阔叶林、落叶阔叶灌丛土壤偏弱酸性，含水量、总有机碳含量低，腐殖化程度高，外生源特征明显，类腐殖质和类腐殖酸含量高，其次为草甸及沼泽植被，而水生植被条件下土壤近中性，含水量、总有机碳含量高，腐殖化程度低，自生源特征明显，类蛋白质含量高。本研究结果可为以该湿地公园为代表的北方寒区永久性河流湿地土壤环境质量监测与评价提供基础数据。
关键词：三维荧光光谱；溶解性有机质；湿地土壤；植被
Abstract：Dissolved organic matter (DOM) is an active organic component in soil, and its source and composition can indicate the degree of soil humification and its relationship with the external environment. In this study, in order to scientifically monitor and evaluate wetland soil environmental quality, we collected the surface (0～20 cm) soil under different vegetation types of the Nianzishan Yalu River National Wetland Park in Heilongjiang Province, and applied three-dimensional fluorescence spectroscopy-parallel factor analysis method to measure the DOM fluorescence spectrum, and further analyzed the effects of soil physicochemical indexes on DOM composition. The results showed that the soil DOM humification index was between 2.562 and 9.052 under five vegetation types (including nine formations). The soil humification degrees of the deciduous broad-leaved forest and the deciduous broad-leaved shrub were higher than that of the meadow, followed by the marsh, and the soil humification degrees of the aquatic vegetation were the lowest. The fluorescence index was between 1.407 and 1.586. The soil DOM source had both exogenous and autogenic characteristics. The deciduous broad-leaved forest and the Phragmites australis (Cav.) Trin. ex Steud. marsh had obvious exogenous characteristics, but the aquatic vegetation and the Echinochloa crus-galli (L.) P. Beauv. Marsh had obvious autogenic characteristics. The biological index ranged from 0.482 to 0.662, and the contribution rate of recent autogenic characteristicwas low. Three types of five kinds of organic components were identified fromthe soil DOM. Humus-like substance (ultraviolet fulvic-like acid componentand visible fulvic-like acid component) had the largest relative proportion, and the soil samples with obvious exogenous characteristics had high content. Followed by protein-like substance (tyrosine-like componentand tryptophan-likecomponent), its content was higher in the soil sample with strong autogenic characteristics. Humic-like acid substance (humic acid component) was the lowest, and mostly existed in the xerophyte-mesophyte environment. Soil moisture content, pH value, and total organic carbon content had significant or significant effects on DOM composition. The three physicochemical indexes were positively correlated with the protein-like substance content and negatively correlated with the humus-like substance content. The correlation of moisture content, total organic carbon content with humic-like acid substancecontent were negative, respectively. Overall, in this wetland park, the soil samples of deciduous broad-leaved forest and shrubs are weakly acidic, with low moisture content and total organic carbon content, high degree of humification, obvious exogenous characteristic, high humus-like substance and humic-like acid substance content. However, under aquatic vegetation, the soil is nearly neutral, with high water content and total organic carbon content, a low degree of humification, obvious autogenic characteristic, and high protein-like substance content. The results of this study can provide basic data for the monitoring and evaluating soil environmental quality in permanent river wetlands in the cold northern region represented by this wetland park.
史传奇，李 艳，胡 钰，于少鹏，金 梁，陈美茹. 北方寒区河流湿地土壤溶解性有机质荧光光谱特征[J]. 光谱学与光谱分析, 2023, 43(05): 1517-1523.
SHI Chuan-qi, LI Yan, HU Yu, YU Shao-peng, JIN Liang, CHEN Mei-ru. Fluorescence Spectral Characteristics of Soil Dissolved Organic Matter in the River Wetland of Northern Cold Region, China. SPECTROSCOPY AND SPECTRAL ANALYSIS, 2023, 43(05): 1517-1523.
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