黑土土壤剖面有机质周转及其控制机制的分子证据

发布时间：2017-12-28 20:12

本文关键词：黑土土壤剖面有机质周转及其控制机制的分子证据　出处：《中国农业大学》2016年博士论文　论文类型：学位论文

【摘要】：土地利用变化以及全球气候变化可以增加根系分泌物,提高深层土壤固碳潜力。根系分泌物投入增加可能激发土壤有机质(SOM)分解,但关于表层和深层土壤中激发效应的差异及其影响因素的研究很少。本文应用了先进的固体核磁共振技术,同时结合了同位素示踪技术以及室内培养实验。本文的研究内容有：1)测定添加葡萄糖对底层土壤产生的激发效应及土壤有机质化学结构变化；2)区分葡萄糖添加后SOM的分解与形成,明确土壤剖面激发效应差异的控制机制；3)研究土壤类型及其开垦年限对土壤剖面SOM分子结构及土壤有机质腐殖化过程的影响。通过以上研究来揭示土壤剖面SOM周转及其控制机制的分子证据,这将对明确土壤新老碳周转和全球碳循环具有重要的意义。主要研究结果如下：第一,添加13C标记葡萄糖(13C.G0.4)于黑土深层土壤(1.00.1.20 m)中诱导产生了正激发效应,并促进了原有SOM的分解；其中48%的葡萄糖完全矿化,而52%的葡萄糖转化为SOM,增加了SOM含量。从13 C CP/TOSS图谱可以看出,SOM中易分解和难分解的有机化合物在培养的过程中均发生了变化,但是G0与13C.Go.4处理变化不同。在培养过程中,G0处理下亚甲基相对比例没有变化,而13C.Go.4处理下亚甲基相对比例先降低后又增加,说明添加葡萄糖后土壤微生物群落的变化。培养后G0处理非极性烷基C和酮/醛相对比例增加,但是芳香C-C和带质子的烷氧基相对比例降低；13C.G0.4处理烷基N和带质子的烷氧基相对比例增加,但是芳香C-O和酮/醛相对比例降低。结果表明了添加葡萄糖很可能激发芳香C-O的分解并抑制酮/醛的形成。第二,由于13 C NMR技术只能检测13C核,而不能检测12C核,本实验为了更好地将葡萄糖和原有SOM信号分开,同时选用了13C富标和贫标(12C)的葡萄糖,并采用13 C multiCP技术研究培养后SOM分子结构的变化。添加13C富标和贫标(12C)的葡萄糖在0,0.05,0.5和2.0 gC kg-1土浓度下(Go,13C/12C-G0.05,13C/12C-G0.5,13C/12C-G2)于黑土土壤剖面A、B、C层土壤中诱导产生了正激发效应,并随着葡萄糖添加浓度的增加而增加。我们首次观察到添加葡萄糖于土壤剖面导致了原有SOM芳香C(A和B层)、亚甲基和羧基/酰胺基的损失(A层)。表层和深层SOM分解的激发效应差异主要受到底物利用效率,SOM可近性以及SOM惰性的影响。第三,典型黑土和黑钙土主导官能团的不同以及土壤剖面中表层(烷基N/甲氧基、烷氧基)和表层以下(芳香C)高比例官能团的差异,说明了土壤类型及深度相互作用于土壤有机质化学结构。随土壤深度增加,亚甲基、芳香C-C相对比例增加而烷基N、带质子烷氧基C、芳香C-H相对比例降低；随开垦时间延长,亚甲基相对比例在黑土所有土层降低,而在黑钙土深层增加；说明了土壤类型,深度和开垦时间相互作用于SOM某特定官能团。主成分结果表明土壤表层SOM由于新鲜有机物不断输入而多含氢,而深层SOM则体现为脱氢；农作时间显著影响了深层土壤SOM结构组成；土壤类型影响了深层SOM的腐殖化过程即典型黑土淋溶黑碳的氧化过程和黑钙土的脱氢氧化过程。本研究利用根系分泌物模拟物,首次研究发现激发效应过程SOM分子结构的变化,区分了新形成的SOM和原有SOM的分解,揭示了土壤微生物底物利用效率、SOM可近性和SOM惰性是不同层次SOM周转差异的主要控制机制,明确了随着黑土开垦时间延长,表层SOM变化较小,亚表层SOM分子结构氧化程度加强,且受输入有机物减少的影响,确定了增加底层根系分泌物数量可以提高土壤固碳效率。在今后的研究中我们需要模拟多种根系分泌物,为揭示根系分泌物输入对剖面有机质周转及其控制因素提供更多的科学依据。
[Abstract]:Land use changes and global climate change can increase root exudates and improve the carbon sequestration potential of deep soil. The increase of root exudates may stimulate the decomposition of soil organic matter (SOM), but there is little research on the difference of excitation effect and its influencing factors in surface and deep soil. In this paper, advanced solid state nuclear magnetic resonance (NMR) technology is applied, and isotope tracer technique and laboratory culture experiment are combined. The research contents of this paper are: 1) the determination of priming effect of soil organic matter and adding chemical structure changes of glucose to produce on the bottom of the soil; 2) to distinguish between decomposition and formation of glucose after the addition of SOM, the explicit control mechanism of soil profile excitation effect difference; 3) of soil types and influence of reclamation on soil profile and molecular structure of SOM soil organic matter humification process. Through the above research, we can reveal the molecular evidence of soil profile SOM turnover and its control mechanism, which will be of great significance for clear soil new and old carbon turnover and global carbon cycle. The main results are as follows: first, adding 13C labeled glucose (13C.G0.4) in the black soil of deep soil (1.00.1.20 m) in inducing the positive priming effect, and promote the decomposition of the original SOM; of which 48% glucose complete mineralization, while 52% conversion of glucose to SOM, SOM content increased. It can be seen from 13 C CP/TOSS diagram that the organic compounds which are easy to decompose and difficult to decompose in SOM all changed during the culture process, but G0 and 13C.Go.4 treatment changed differently. In training process, methylene relative proportion did not change after G0 treatment, while the relative proportion of methylene decreased at first and then increased after 13C.Go.4 treatment, indicating the change of soil microbial community after adding glucose. After treatment, the relative proportions of nonpolar alkyl C and ketones / aldehydes increased after G0 treatment, but the relative proportions of aromatic C-C and proton alkoxy groups decreased. The relative proportions of alkyl N and proton alkoxy increased, but the relative proportions of aromatic C-O and ketones / aldehydes decreased with 13C.G0.4 treatment. The results showed that the addition of glucose could stimulate the decomposition of aromatic C-O and inhibit the formation of ketone / aldehyde. Second, since 13 C NMR technology can detect 13C core and not detect 12C core, we choose 13C rich and lean 12C (12C) glucose to separate the glucose from the original SOM signal better, and use 13 C multiCP technology to study the change of SOM molecule structure. The enrichment of 13C enriched and lean 12C (Go) at 0,0.05,0.5 and 2 gC kg-1 soil (Go, 13C/12C-G0.05,13C/12C-G0.5,13C/12C-G2) induced positive excitation effect in the soil profile A, B and C layer of black soil, and increased with the increase of glucose concentration. For the first time, we observed that the addition of glucose to the soil profile resulted in the loss of the original SOM aromatic C (A and B layers), methylene and carboxyl / amide groups (A layer). The difference in excitation effects of SOM decomposition in the surface and deep layer is mainly influenced by the efficiency of substrate utilization, SOM availability and the inertia of SOM. Third, the typical black soil and chernozem leading functional group and different soil profiles in the surface layer (N/ methoxy alkyl, alkoxy) and below the surface (aromatic C) between the high proportion of functional groups, the soil type and depth of interaction in the chemical structure of soil organic matter. With the increase of soil depth, methylene, relative proportion of aromatic C-C increased with proton N, alkyl alkoxy C, aromatic C-H ratio decreased; with the reclamation time, reduce the relative proportion of methylene in black soil increased in all soil, chernozem deep; shows the soil type, depth and reclamation time interactions in a particular SOM functional groups. The results show that principal component SOM of the soil due to fresh organic substances continue to enter and hydrogen, while the deep SOM of dehydrogenation; time significantly affected the composition of farming SOM deep soil structure; soil types affect the dehydrogenation oxidation process of oxygen and carbon black soil leaching chernozem the humification process is a typical deep SOM. The root exudates of mimics, the first study showed that the change of the molecular structure of SOM excitation effect, the distinction between the decomposition of the new formed SOM and the original SOM, reveals the soil microbial substrate utilization efficiency, SOM accessibility and SOM inertia is the main control mechanisms at different levels of SOM turnover differences, with clear tillage time extended SOM surface changes smaller sub surface molecular structure of SOM oxidation degree strengthen, and reduce the influence of organic matter input, the increase in the number of underlying root exudates can improve the efficiency of soil carbon sequestration. We need to simulate many root exudates in future research, so as to provide more scientific evidence for revealing the input of root exudates to the turnover of organic matter and its controlling factors.
【学位授予单位】：中国农业大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：S153.6

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