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黑土、潮土和红壤DOM的光谱特征及其结构差异分析
缪闯和, 吕贻忠
中国农业大学土地科学与技术学院,100193
摘要:
可溶性有机质(DOM,Dissolved Organic Matter)是土壤有机质中对环境变化较为敏感的组分,在碳氮循环、养分转化及污染物迁移等土壤生物化学过程中具有重要作用。为探究不同类型土壤DOM含量和结构的差异性,本研究选取黑土、潮土和红壤等三种土壤的表层土壤(0-20 cm),提取其中的可溶性有机质,应用紫外-可见光谱、荧光光谱等技术,分析土壤中DOM的数量和光谱特征。结果显示,三种不同类型土壤中可溶性有机碳(DOC)含量、SOC/DOC值大小为:红壤>黑土>潮土(P<0.05)。 A254值大小为黑土>潮土>红壤,但SUVA254值大小为:潮土>黑土>红壤(P<0.05),表明潮土DOM的芳香化程度最高,但芳香性结构物质含量低于黑土,红壤DOM的芳香性结构物质含量和芳香性构化程度均低于黑土和潮土。荧光发射光谱腐殖化指数(HIXem)和荧光效率 (Feff )值大小为:红壤>黑土>潮土(P<0.05),说明红壤DOM的腐殖化程度和π电子共轭基团含量比潮土和黑土DOM高。荧光指数(FI)大小为:红壤>潮土>黑土(P<0.05),表明红壤DOM比潮土和黑土DOM中含有更多的微生物源组分。荧光同步光谱显示,黑土和潮土DOM以类蛋白质基团为主,红壤DOM以木质素类基团为主。土壤有机质含量、黏粒含量和粘土矿物种类不同的情况下,土壤对DOM的吸附能力不同,使土壤DOM的提取比例也存在显著差异。总体上,红壤DOM腐殖化程度最高,但芳香性物质含量和芳香性构化程度比黑土和潮土DOM低,红壤DOM成分主要是相对分子质量较大的木质素类基团物质。本研究促进了对不同土壤中DOM结构特征的理解,为提高土壤DOM含量,制定合理的土壤培肥方案提供了理论依据。
关键词:  土壤  DOM  紫外-可见光谱  荧光光谱
DOI:
分类号:S153.6+2
基金项目:“十三五”国家重点研发计划(NO.2018YFD0500202);国家自然科学基金面上项目(NO.4157317)
The Spectral Characteristics and Structural Difference of DOM in Black Soil , Fluvo-aquic Soil and Red Soil
MIAO Chuanghe, LV Yizhong
College of Resources and Enviroment,China Agriculture University
Abstract:
Dissolved organic Matter (DOM) is a component of soil organic matter that is sensitive to environmental changes and plays an important role in soil biochemical processes such as carbon and nitrogen cycles, nutrient conversion and pollutant transport. The contents and structure of DOM in soils were explored by extracting DOM of the topsoil (0-20 cm) of three soils including black soil, fluvo-aquic soil and red soil. UV-visible spectroscopy and fluorescence spectroscopy were also applied to analyze the spectral characteristics of DOM. The results showed that, the value of SOC/DOC in three types of soil exhibited an order of red soil > black soil > fluvo-aquic soil (P<0.05), indicating that soil organic matter contents, soil minerals have impact on the extraction ratio of soil DOM. The A254 value was in an order of black soil > fluvo-aquic soil > red soil, but the SUVA254 value was in an order of fluvo-aquic soil > black soil > red soil (P<0.05), suggesting that the DOM of fluvo-aquic soil has the highest aromatization degree , but the contents of aromatics is lower than that of black soil. The fluorescence emission spectral humification index (HIXem) and fluorescence efficiency (Feff) were in the decreasing order of red soil > black soil > fluvo-aquic soil (P<0.05), demonstrated that DOM humification degree and π-electron conjugate group contents in red soil were higher than those of fluvo-aquic soil and black soil.For The fluorescence index (FI), the order of red soil > fluvo-aquic soil>black soil (P<0.05) was observed, which showed that the DOM of red soil contained more microbial components than those of fluvo-aquic soil and black soil.Fluorescence synchronous?spectroscopy showed that the DOM of fluvo-aquic soil and black soil mainly contained protein-like groups, and the DOM of red soil mainly contained lignin-like groups. The extraction ratio of soil DOM have a significant difference due to the different potential DOM adsorption capacity of three types of soil.In short,the humification degree of DOM of red soil is higher than those of black soil and fluvo-aquic soil, but the contents of aromatics and the aromatization degree are lower than those of black soil and fluvo-aquic soil.The main components of DOM extracted from red soil are lignin groups with large molecular weight. The aromatics in DOM extracted from black soil and fluvo-aquic soil are mainly containing protein-like groups. Therefore,this study not only promoted the understanding of DOM change in soils,but also provided a theoretical basis for improving the contents of soil DOM,and formulating a reasonable program of soil fertilzation.
Key words:  Soil  DOM  Ultraviolet-visible spectrum  Fluorescence spectroscopy

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