本文關鍵詞：黑土土壤剖面有機質周轉及其控制機制的分子證據(jù)　出處：《中國農(nóng)業(yè)大學》2016年博士論文　論文類型：學位論文

  更多相關文章： 激發(fā)效應 土壤有機質 穩(wěn)定同位素 深層土壤 ~(13)C固體核磁技術

【摘要】：土地利用變化以及全球氣候變化可以增加根系分泌物,提高深層土壤固碳潛力。根系分泌物投入增加可能激發(fā)土壤有機質(SOM)分解,但關于表層和深層土壤中激發(fā)效應的差異及其影響因素的研究很少。本文應用了先進的固體核磁共振技術,同時結合了同位素示蹤技術以及室內培養(yǎng)實驗。本文的研究內容有：1)測定添加葡萄糖對底層土壤產(chǎn)生的激發(fā)效應及土壤有機質化學結構變化；2)區(qū)分葡萄糖添加后SOM的分解與形成,明確土壤剖面激發(fā)效應差異的控制機制；3)研究土壤類型及其開墾年限對土壤剖面SOM分子結構及土壤有機質腐殖化過程的影響。通過以上研究來揭示土壤剖面SOM周轉及其控制機制的分子證據(jù),這將對明確土壤新老碳周轉和全球碳循環(huán)具有重要的意義。主要研究結果如下：第一,添加13C標記葡萄糖(13C.G0.4)于黑土深層土壤(1.00.1.20 m)中誘導產(chǎn)生了正激發(fā)效應,并促進了原有SOM的分解；其中48%的葡萄糖完全礦化,而52%的葡萄糖轉化為SOM,增加了SOM含量。從13 C CP/TOSS圖譜可以看出,SOM中易分解和難分解的有機化合物在培養(yǎng)的過程中均發(fā)生了變化,但是G0與13C.Go.4處理變化不同。在培養(yǎng)過程中,G0處理下亞甲基相對比例沒有變化,而13C.Go.4處理下亞甲基相對比例先降低后又增加,說明添加葡萄糖后土壤微生物群落的變化。培養(yǎng)后G0處理非極性烷基C和酮/醛相對比例增加,但是芳香C-C和帶質子的烷氧基相對比例降低；13C.G0.4處理烷基N和帶質子的烷氧基相對比例增加,但是芳香C-O和酮/醛相對比例降低。結果表明了添加葡萄糖很可能激發(fā)芳香C-O的分解并抑制酮/醛的形成。第二,由于13 C NMR技術只能檢測13C核,而不能檢測12C核,本實驗為了更好地將葡萄糖和原有SOM信號分開,同時選用了13C富標和貧標(12C)的葡萄糖,并采用13 C multiCP技術研究培養(yǎng)后SOM分子結構的變化。添加13C富標和貧標(12C)的葡萄糖在0,0.05,0.5和2.0 gC kg-1土濃度下(Go,13C/12C-G0.05,13C/12C-G0.5,13C/12C-G2)于黑土土壤剖面A、B、C層土壤中誘導產(chǎn)生了正激發(fā)效應,并隨著葡萄糖添加濃度的增加而增加。我們首次觀察到添加葡萄糖于土壤剖面導致了原有SOM芳香C(A和B層)、亞甲基和羧基/酰胺基的損失(A層)。表層和深層SOM分解的激發(fā)效應差異主要受到底物利用效率,SOM可近性以及SOM惰性的影響。第三,典型黑土和黑鈣土主導官能團的不同以及土壤剖面中表層(烷基N/甲氧基、烷氧基)和表層以下(芳香C)高比例官能團的差異,說明了土壤類型及深度相互作用于土壤有機質化學結構。隨土壤深度增加,亞甲基、芳香C-C相對比例增加而烷基N、帶質子烷氧基C、芳香C-H相對比例降低；隨開墾時間延長,亞甲基相對比例在黑土所有土層降低,而在黑鈣土深層增加；說明了土壤類型,深度和開墾時間相互作用于SOM某特定官能團。主成分結果表明土壤表層SOM由于新鮮有機物不斷輸入而多含氫,而深層SOM則體現(xiàn)為脫氫；農(nóng)作時間顯著影響了深層土壤SOM結構組成；土壤類型影響了深層SOM的腐殖化過程即典型黑土淋溶黑碳的氧化過程和黑鈣土的脫氫氧化過程。本研究利用根系分泌物模擬物,首次研究發(fā)現(xiàn)激發(fā)效應過程SOM分子結構的變化,區(qū)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惰性是不同層次SOM周轉差異的主要控制機制,明確了隨著黑土開墾時間延長,表層SOM變化較小,亞表層SOM分子結構氧化程度加強,且受輸入有機物減少的影響,確定了增加底層根系分泌物數(shù)量可以提高土壤固碳效率。在今后的研究中我們需要模擬多種根系分泌物,為揭示根系分泌物輸入對剖面有機質周轉及其控制因素提供更多的科學依據(jù)。
[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.
【學位授予單位】：中國農(nóng)業(yè)大學
【學位級別】：博士
【學位授予年份】：2016
【分類號】：S153.6

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