本文選題：土壤有機(jī)質(zhì) + 礦化�。� 參考：《華中農(nóng)業(yè)大學(xué)》2016年博士論文

【摘要】：土壤有機(jī)質(zhì)作為最大的陸地碳庫,與土壤肥力、全球碳循環(huán)等密切相關(guān),其穩(wěn)定性對于土壤生態(tài)系統(tǒng)抵抗外界環(huán)境變化具有重要意義。有機(jī)質(zhì)可與土壤中其它組分相互作用,其穩(wěn)定性受各種生物及非生物因素的制約。本研究采集九宮山不同海拔土壤,通過分子熒光光譜、碳庫分級等技術(shù),分析土壤培養(yǎng)前后有機(jī)組分性質(zhì)和礦化特征。同時(shí)借助元素分析、傅里葉紅外光譜(FTIR)、核磁共振波譜(NMR)等技術(shù)分析不同土壤中胡敏酸(HA)的結(jié)構(gòu)特征;通過粒徑分級、X射線衍射(XRD)及紅外光譜等手段,研究了影響土壤有機(jī)質(zhì)穩(wěn)定性的物理、化學(xué)及生物學(xué)機(jī)制�；谏鲜鼋Y(jié)果,合成了復(fù)合鐵鋁氧化物,并純化培養(yǎng)了革蘭氏陰性和陽性細(xì)菌,通過不同反應(yīng)條件下HA吸附實(shí)驗(yàn)、ζ電位測試、紅外光譜等技術(shù),研究了鐵鋁氧化物吸附HA的微觀機(jī)制,初步探討了鐵氧化物、細(xì)菌及其復(fù)合體的HA吸附特性,得到如下主要結(jié)論:1)隨海拔降低,生物活性碳庫有機(jī)碳(SOC)含量降低,有機(jī)碳礦化總量及速率減小。同時(shí),隨土壤深度增加,WEOC平均分子量增加,腐殖化程度和芳香縮合度增加,分子結(jié)構(gòu)趨于復(fù)雜,導(dǎo)致深層土壤中SOC礦化率明顯低于表層。供試土壤礦化前后惰性氮在全氮中的比例(RN)均隨土壤深度增加而增加,但惰性碳在有機(jī)碳中的比例(RC)隨深度變化不明顯。RN與SOC礦化呈顯著負(fù)相關(guān)(P0.05),但RC與SOC礦化的相關(guān)性不顯著,深層土壤中氮的有效性對有機(jī)質(zhì)礦化比碳有效性更為重要。SOC礦化總量取決于有機(jī)質(zhì)數(shù)量,但其礦化率主要取決于有機(jī)組分的生物有效性。土壤經(jīng)短期礦化培養(yǎng)后,WEOC平均分子量和共軛結(jié)構(gòu)減少,芳化度和腐殖化程度降低,分子結(jié)構(gòu)趨于簡單。2)九宮山不同海拔土壤中HA含量及結(jié)構(gòu)特征差異顯著。隨海拔增加,HA總量及相對含量均增加,且酸性土壤中HA易于在土壤表層富集。供試HA主要來源于植物殘?bào)w,也含有微生物代謝物質(zhì);其結(jié)構(gòu)中以烷基碳(25-40%)和烷氧碳(21-44%)為主,1500 m處二者含量相當(dāng),1200 m處烷基碳較多,600 m處烷氧碳較多。隨海拔上升,HA芳化度增加;隨土壤深度增加,HA芳化度顯著降低。HA腐殖化程度為1500 m處最高,600 m處最低,與有機(jī)碳礦化總量的變化一致。此外,HA分子的芳香縮合度、結(jié)構(gòu)復(fù)雜度及其疏水性隨海拔的變化均為1200 m1500 m600 m,與SOC礦化率變化相反。3)600和1500 m處礦物穩(wěn)定有機(jī)碳(MOC)含量主要與有機(jī)碳形態(tài)和鐵氧化物有關(guān),1200 m處鋁氧化物促進(jìn)了MOC的積累。鐵鋁氧化物比層狀礦物對有機(jī)質(zhì)的保護(hù)能力更強(qiáng),且非晶質(zhì)礦物比晶質(zhì)礦物的影響更大。鐵氧化物比鋁氧化物對有機(jī)質(zhì)穩(wěn)定性的影響弱。土壤有機(jī)碳主要存在于微團(tuán)聚體;酚類、多糖及芳香類物質(zhì)易在小顆粒中積累,而烷烴、醇類物質(zhì)在大顆粒土壤中含量相對豐富。大團(tuán)聚體對易氧化碳的保護(hù)能力強(qiáng)于微團(tuán)聚體,但后者對芳香物質(zhì)的保護(hù)更顯著。芳香類物質(zhì)通過與礦物結(jié)合增強(qiáng)其穩(wěn)定性;烷烴、酚類及多糖的穩(wěn)定受其結(jié)構(gòu)的影響更大。礦物穩(wěn)定有機(jī)碳是土壤穩(wěn)定有機(jī)碳的重要組成,HA也是穩(wěn)定有機(jī)組分的物質(zhì)來源。土壤有機(jī)質(zhì)穩(wěn)定性可通過與礦物結(jié)合成有機(jī)-礦物復(fù)合體、團(tuán)聚體的空間位阻效應(yīng)及有機(jī)質(zhì)自身結(jié)構(gòu)的穩(wěn)定三種方式實(shí)現(xiàn)。4)復(fù)合鐵鋁氫氧化物與HA的相互作用受礦物表面性質(zhì)、溶液pH及離子強(qiáng)度的影響。pH 5.0時(shí),HA最大吸附量為FeAl,在復(fù)合Fe-Al氧化物中其吸附量隨Fe含量增加而增加;HA吸附親和力隨Al含量增加而增大;酸性條件下,鋁氧化物的配位能力強(qiáng)于鐵氧化物。鐵鋁氧化物優(yōu)先吸附HA中芳香組分,且與Fe相比,Al吸附態(tài)HA的芳香度較高。HA分子中羧基、酚羥基及脂肪碳均參與吸附反應(yīng),且Fe比Al更易與氨基結(jié)合。隨溶液離子強(qiáng)度增加,各礦物的HA吸附量均增加;純礦物中HA吸附量為AlFe,復(fù)合Fe-Al氧化物的HA吸附量與Al含量成反比。隨體系pH增加HA吸附量降低,除Al的吸附親和力與pH變化趨勢相反,其余各礦物的吸附親和力在pH 7.0時(shí)最大,pH 5.0時(shí)最小。高pH條件下鐵鋁氧化物優(yōu)先吸附HA中脂肪族物質(zhì)。5)水鐵礦的HA吸附量高于赤鐵礦,枯草芽孢桿菌的HA吸附量高于惡臭假單胞菌。鐵氧化物與細(xì)菌共存抑制對HA吸附,且水鐵礦-細(xì)菌復(fù)合體的HA吸附抑制率高于赤鐵礦-細(xì)菌復(fù)合體,惡臭假單胞菌-氧化物復(fù)合體的HA吸附抑制率高于枯草芽孢桿菌-氧化物復(fù)合體。低濃度磷酸鹽抑制鐵氧化物及鐵氧化物-細(xì)菌復(fù)合體對HA的吸附,高濃度磷酸鹽對復(fù)合體中HA吸附的抑制率降低,甚至促進(jìn)HA吸附。本研究分析了團(tuán)聚、吸附及有機(jī)質(zhì)結(jié)構(gòu)特征對有機(jī)質(zhì)穩(wěn)定性的相對貢獻(xiàn),可為自然環(huán)境中土壤有機(jī)質(zhì)的轉(zhuǎn)化與積累研究提供理論參考。
[Abstract]:As the largest terrestrial carbon pool, soil organic matter is closely related to soil fertility and global carbon cycle. Its stability is of great significance to soil ecosystem resistance to the change of the external environment. Organic matter can interact with other components in the soil, and its stability is restricted by various biological and abiotic factors. At different altitudes, the characteristics of the unit and mineralization of soil were analyzed by molecular fluorescence spectrum and carbon pool classification. At the same time, the structure characteristics of Hu Min acid (HA) in different soils were analyzed by elemental analysis, Fourier infrared spectroscopy (FTIR) and nuclear magnetic resonance spectroscopy (NMR), and X ray diffraction (XRD) by particle size classification. The physical, chemical and biological mechanisms affecting the stability of soil organic matter were studied by means of infrared spectroscopy. Based on the above results, the composite iron and aluminum oxides were synthesized and the Gram-negative and positive bacteria were purified and cultured. The iron and aluminum oxides were studied by HA adsorption experiments under different reaction conditions, Zeta potential test and infrared spectroscopy. The adsorption properties of HA were preliminarily discussed. The HA adsorption characteristics of iron oxides, bacteria and their complexes were preliminarily discussed. 1) the contents of organic carbon (SOC) decreased with the decrease of altitude, and the total amount and rate of organic carbon mineralization decreased. At the same time, the average molecular weight of WEOC increased with the increase of soil depth, the degree of humification and aromatic contraction. The percentage of SOC mineralization in deep soil was obviously lower than that in surface layer. The proportion of inert nitrogen in total nitrogen (RN) increased with soil depth before and after mineralization, but the proportion of inert carbon in organic carbon (RC) had no significant negative correlation with SOC mineralization with the depth of.RN (P0.05), but RC and SOC The correlation of mineralization is not significant. The availability of nitrogen in deep soil is more important for the mineralization of organic matter than carbon. The total amount of.SOC mineralization depends on the quantity of organic matter, but the mineralization rate depends mainly on the bioavailability of the organic matter. After the short-term mineralization of the soil, the average fraction of WEOC and the conjugated structure of the soil are reduced, the degree of aromatization and humification of the soil are reduced. The content and structural characteristics of HA in the soils of different altitudes of the nine palace mountains were significantly different. The total and relative content of HA increased with the elevation of the altitude, and the HA in the acid soil was easy to be enriched in the soil surface. The experimental HA was mainly derived from the plant residues and also contained microbial metabolites; in its structure, the structure of alkyl carbon (25-4) 0%) and alkoxy carbon (21-44%), the content of two people at 1500 m is equal, 1200 m is more alkyl carbon and more alkoxy carbon at 600 m. With the increase of altitude, the degree of HA aromatization is increased; the degree of HA aromatization is the highest with the depth of soil increasing, the degree of.HA humification is highest, 600 m is the lowest, and the change of organic carbon mineralization is the same. In addition, HA molecule aromatic The variation of aroma and shrinkage, structure complexity and its hydrophobicity are 1200 m1500 M600 m with the elevation of altitude, which is opposite to SOC mineralization rate.3. The content of mineral stable organic carbon (MOC) at 600 and 1500 m is mainly related to organic carbon morphology and iron oxide, and aluminum oxide at 1200 m promotes the accumulation of MOC. The soil organic carbon is mainly in the micro aggregates; the phenols, polysaccharides and aromatic substances are easily accumulated in the small particles, and the alkanes and alcohols are relatively rich in the large granular soil. Large aggregate aggregates. The protection of oxidizable carbon is stronger than that of the micro aggregate, but the latter is more significant for the protection of aromatic substances. The stability of aromatics is enhanced by combining with minerals; the stability of alkanes, phenols and polysaccharides is more affected by its structure. Mineral stable organic carbon is an important component of soil stable organic carbon, and HA is also a stable unit. The stability of soil organic matter can be stabilized by combining with minerals into organic mineral complex, the spatial hindrance effect of the aggregate and the stability of the organic matter's self structure in the three ways of.4) the interaction of the compound iron aluminum hydroxide with HA is affected by the mineral surface properties. The maximum adsorption capacity of HA is Fe when the solution pH and the intensity of the ionization of the HA are.PH 5. The adsorption capacity of Al increased with the increase of Fe content in the compound Fe-Al oxide, and the adsorption affinity of HA increased with the increase of Al content. Under the acid condition, the coordination ability of aluminum oxide was stronger than that of the iron oxide. The iron and aluminum oxides first adsorbed the aromatic component of HA, and the aromatic degree of Al adsorbed HA was higher than that of the Fe, and the carboxyl group, phenol hydroxyl group and lipid in.HA molecules were higher than that of Fe. The fatty carbon all participates in the adsorption reaction, and Fe is more easily bound to the amino group than the Al. With the increase of the ionic strength of the solution, the HA adsorption amount of each mineral increases; the adsorption amount of HA in the pure mineral is AlFe, the HA adsorption amount of the compound Fe-Al oxide is inversely proportional to the Al content. With the pH increase of the HA, the adsorption capacity of HA decreases, except the Al adsorption affinity is the opposite to pH variation trend. The adsorption affinity of minerals is maximum at pH 7 and minimum at pH 5. Under high pH conditions, iron and aluminum oxides first adsorb aliphatic.5 in HA). The adsorption amount of HA in pyrite is higher than that of hematite, and the HA adsorption capacity of Bacillus subtilis is higher than that of Pseudomonas stinsii. The coexistence of iron oxides and bacteria to HA adsorption, and HA of the pyrite bacterial complex The inhibition rate of adsorption was higher than that of hematite bacterial complex, and the inhibition rate of HA adsorption in Pseudomonas aeruginosa complex complex was higher than that of Bacillus subtilis oxide complex. Low concentration phosphate inhibited the adsorption of iron oxide and iron oxide bacterial complex on HA, and the inhibition rate of HA adsorption in the complex of high concentration phosphate decreased and even promoted. This study analyzed the relative contribution of aggregation, adsorption and organic matter structure characteristics to the stability of organic matter, which could provide a theoretical reference for the study of the transformation and accumulation of soil organic matter in natural environment.
【學(xué)位授予單位】：華中農(nóng)業(yè)大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2016
【分類號】：S153.6

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