發(fā)布時(shí)間：2018-01-10 22:19

  本文關(guān)鍵詞：水稻土中微生物發(fā)酵過程對氧化鐵還原的貢獻(xiàn)　出處：《西北農(nóng)林科技大學(xué)》2017年博士論文　論文類型：學(xué)位論文

  更多相關(guān)文章： 氧化鐵還原 水稻土有機(jī)質(zhì) pH 微生物群落結(jié)構(gòu) 微生物發(fā)酵產(chǎn)氫 生物炭

【摘要】：水稻土中氧化鐵還原過程與稻田中碳、氮、硫、磷等元素的地球化學(xué)循環(huán)密切相關(guān),Fe(Ⅲ)還原過程同時(shí)偶聯(lián)有機(jī)污染物的降解及變價(jià)重金屬的氧化還原過程,對稻田產(chǎn)甲烷過程產(chǎn)生顯著的抑制作用,因此研究淹水稻田中Fe(Ⅲ)還原過程及其機(jī)理具有重要的地球化學(xué)和環(huán)境學(xué)意義。早先對Fe(Ⅲ)還原過程的認(rèn)知主要集中在沉積物環(huán)境中,大量的研究證實(shí)氧化鐵的異化還原過程是沉積物等厭氧環(huán)境中Fe(Ⅲ)還原的主要方式,而兼性共代謝還原過程往往與有機(jī)質(zhì)的厭氧分解相偶聯(lián),被認(rèn)為是Fe(Ⅲ)還原的次要途徑。然而與沉積物長期處于厭氧環(huán)境不同,稻田水旱輪作的耕作方式所形成的氧化還原環(huán)境交替,使得微生物代謝有機(jī)質(zhì)產(chǎn)氫過程成為電子傳遞鏈中的重要環(huán)節(jié)。因此有關(guān)淹水稻田中微生物發(fā)酵有機(jī)質(zhì)進(jìn)行兼性共代謝還原氧化鐵的機(jī)理還有待進(jìn)一步深入。本研究采用厭氧恒溫培養(yǎng)方法,采集我國不同植稻區(qū)的典型水稻土,比較不同水稻土理化性質(zhì)和Fe(Ⅲ)還原特征的差異,揭示影響淹水稻田中Fe(Ⅲ)還原過程的主要因素;通過外源添加不同的小分子有機(jī)碳源和調(diào)節(jié)土壤pH條件,研究有機(jī)質(zhì)厭氧發(fā)酵過程中微生物群落結(jié)構(gòu)、脫氫產(chǎn)氫過程和Fe(Ⅲ)還原過程之間的相互關(guān)系,揭示微生物發(fā)酵過程中產(chǎn)生小分子有機(jī)碳、產(chǎn)氫、產(chǎn)酸對Fe(Ⅲ)還原過程的作用;通過熒光激發(fā)-發(fā)射光譜掃描研究不同水稻土中水溶性有機(jī)碳的熒光特性及主要組分,揭示水溶性有機(jī)質(zhì)與Fe(Ⅲ)還原過程的關(guān)系;以生物炭為載體,利用其具有高含量的芳香結(jié)構(gòu)和較強(qiáng)的吸附能力這一特點(diǎn),采用低分子量有機(jī)碳修飾生物炭,研究其在促進(jìn)水稻土Fe(Ⅲ)還原過程方面的潛能,從而將水溶性有機(jī)碳的電子傳遞功能和微生物發(fā)酵有機(jī)物對Fe(Ⅲ)還原的貢獻(xiàn)這一理論應(yīng)用于實(shí)踐。主要的研究結(jié)果如下:(1)水稻土淹水后,Fe(Ⅱ)隨淹水時(shí)間延長而逐漸累積,不同水稻土間Fe(Ⅲ)還原特征存在顯著差異。在土壤理化性質(zhì)中,有機(jī)質(zhì)含量和無定形氧化鐵含量是決定Fe(Ⅲ)還原特征的最主要因素,二者均與Fe(Ⅲ)還原潛勢a和最大Fe(Ⅲ)還原速率Vmax間存在顯著的正相關(guān)關(guān)系,而pH是影響達(dá)到最大Fe(Ⅲ)還原速率所需時(shí)間的主要因素。(2)水稻土中Fe(Ⅲ)還原過程對不同種類碳源調(diào)控的響應(yīng)因土壤不同而存在明顯差異。微生物利用葡萄糖引起的土壤pH降低抑制了酸性水稻土中的Fe(Ⅲ)還原過程。水稻土中微生物利用不同種類碳源為底物的發(fā)酵脫氫產(chǎn)氫過程主要出現(xiàn)在培養(yǎng)初期,產(chǎn)氫能力從強(qiáng)到弱依次為葡萄糖丙酮酸鹽乳酸鹽,且脫氫酶活性最大值對應(yīng)的時(shí)間與微生物鐵Fe(Ⅲ)原反應(yīng)達(dá)到最大反應(yīng)速率的時(shí)間(TVmax)具有一致性。培養(yǎng)體系中pH的降低表明H+的產(chǎn)生是微生物發(fā)酵有機(jī)碳源的主要產(chǎn)物,以Fe(OH)3為電子受體的還原過程顯著消耗了微生物利用不同種類碳源發(fā)酵產(chǎn)生的的h2。培養(yǎng)體系ph與h2分壓和fe(ii)累積量存在極顯著負(fù)相關(guān)關(guān)系,說明微生物利用有機(jī)碳源發(fā)酵產(chǎn)生有機(jī)酸、進(jìn)而影響脫氫產(chǎn)氫特性并作用于微生物fe(iii)還原過程。(3)隨著可利用營養(yǎng)基質(zhì)和鐵受體的消耗,淹水水稻土中的微生物群落和潛在fe(iii)還原菌呈現(xiàn)出了顯著的演替。其中firmicutes是最為優(yōu)勢的類群,隨著淹水時(shí)間延長相對豐度逐漸降低;acidobacteria、bacteroidetes、chloroflexi、proteobacteria和ignavibacteriae是第二大類優(yōu)勢群,相對豐度均隨淹水時(shí)間延長而逐漸升高。外源添加不同濃度葡萄糖為微生物提供了充足的碳源,使微生物群落演替滯后,從而使firmicutes大量富集,尤其是具有發(fā)酵產(chǎn)氫功能的clostridium和bacillus,且該滯后效應(yīng)因碳源濃度的增加而增強(qiáng)。不同濃度葡萄糖富集下水稻土中形成以bacillus和clostridium為主、desulfitobacterium、solibacillus、anaeromyxobacter和paenibacillus等為輔的潛在fe(iii)還原菌群。結(jié)合添加不同濃度葡萄糖時(shí)微生物脫氫產(chǎn)氫特性和fe(iii)還原特征,驗(yàn)證了不同濃度葡萄糖調(diào)控下潛在fe(iii)還原菌群落結(jié)構(gòu)變化與脫氫產(chǎn)氫過程對bacillus和clostridium群落結(jié)構(gòu)變化的響應(yīng)共同作用而影響fe(iii)還原過程。(4)調(diào)控水稻土初始ph使脫氫產(chǎn)氫過程中微生物活性、相應(yīng)酶活性及fe(iii)溶解性發(fā)生改變而進(jìn)一步作用于fe(iii)還原過程。當(dāng)調(diào)節(jié)酸性和堿性性水稻土初始ph至強(qiáng)酸性或酸性時(shí),淹水培養(yǎng)過程中脫氫酶活性受到顯著抑制,在堿性水稻土中產(chǎn)氫過程受到抑制而酸性水稻土中得以促進(jìn)。雖然在此情況下酸溶性fe(iii)的濃度較未調(diào)節(jié)處理顯著提高,但fe(iii)還原過程仍然受初始ph降低的抑制,因此在低ph條件下鐵氧化物的溶解性并非是影響fe(iii)還原過程的主要因素。調(diào)節(jié)水稻土初始ph至中性、堿性及強(qiáng)堿性時(shí),微生物的脫氫反應(yīng)及fe(iii)溶解性不受ph調(diào)節(jié)影響,其中堿性水稻土調(diào)節(jié)至中性和酸性水稻土調(diào)節(jié)至中性、堿性及強(qiáng)堿性時(shí)氫氣分壓顯著降低,使fe(iii)還原提前達(dá)到最大反應(yīng)速率,體現(xiàn)出fe(iii)還原過程對氫氣的利用和消耗。在不同初始ph水稻土fe(iii)還原的快速時(shí)期,可以表征代謝有機(jī)質(zhì)微生物的活性的脫氫酶與fe(ii)累積密切相關(guān)。(5)水稻土中微生物對土壤有機(jī)質(zhì)發(fā)酵的脫氫產(chǎn)氫過程和潛在fe(iii)還原菌群落結(jié)構(gòu)對初始ph調(diào)節(jié)的響應(yīng)直接或間接地影響著水稻土中的fe(iii)還原過程。當(dāng)調(diào)節(jié)酸性水稻土至堿性后細(xì)菌群落結(jié)構(gòu)受ph調(diào)節(jié)影響較小,淹水初期firmicutes受初始ph調(diào)節(jié)相對豐度有所提高。堿性水稻土中proteobacteria占細(xì)菌的比例隨初始ph調(diào)節(jié)至酸性而升高,細(xì)菌群落結(jié)構(gòu)因ph調(diào)節(jié)而存在較大差異。酸性水稻土中潛在fe(iii)還原菌相對豐度較未調(diào)節(jié)處理有所提高,對應(yīng)于提高的fe(iii)還原對h2的消耗和提前達(dá)到的最大fe(iii)還原速率;堿性水稻土中潛在fe(iii)還原菌在淹水初期受ph調(diào)節(jié)抑制后,于淹水5d-20d相對豐度升高,對應(yīng)于淹水初期受抑制的fe(iii)還原過程和淹水中后期顯著的fe(ii)累積。(6)通過對不同水稻土水溶性有機(jī)碳三維熒光光譜掃描鑒定發(fā)現(xiàn)4個(gè)共有的類腐殖酸熒光組分,其來源以外源輸入為主,內(nèi)源輸入為輔。水溶性有機(jī)碳的腐殖化系數(shù)與Fe(Ⅲ)還原特征參數(shù)存在顯著的相關(guān)關(guān)系。其中以陸源的大分子量UVC類腐殖酸對Fe(Ⅲ)還原特征的貢獻(xiàn)最高,陸源的UVC+UVA類腐殖酸和海源的UVA海洋腐殖酸與Fe(Ⅲ)還原特征參數(shù)的相關(guān)關(guān)系也達(dá)到顯著或極顯著水平,而水溶性有機(jī)碳含量的貢獻(xiàn)最小。推測水稻土中水溶性有機(jī)碳的腐殖化程度及其中各類腐殖酸組分的含量與水稻土Fe(Ⅲ)還原能力正相關(guān)。(7)生物炭添加可以促進(jìn)水稻土中微生物Fe(Ⅲ)還原能力,且促進(jìn)作用隨著生物炭粒度減小而逐漸增強(qiáng)。究其原因,一方面生物炭的水溶性有機(jī)碳作為電子穿梭體加速了Fe(Ⅲ)還原過程;另一方面生物炭的添加促進(jìn)了游離氧化鐵和硝態(tài)氮含量對Fe(Ⅲ)還原過程的貢獻(xiàn)。采用葡萄糖修飾生物炭不僅可以促進(jìn)水稻土中氧化鐵的還原過程,也可以緩減生物炭的“堿性基團(tuán)”引起的pH升高,且生物炭粒度越小作用越顯著。通過本文的研究,對水稻土中微生物Fe(Ⅲ)還原過程相關(guān)的環(huán)境條件和Fe(Ⅲ)還原微生物的群落結(jié)構(gòu)與功能有了更深入的認(rèn)識,探討了水稻土淹水過程中微生物發(fā)酵有機(jī)質(zhì)對Fe(Ⅲ)還原具有重要貢獻(xiàn),使水稻土中Fe(Ⅲ)的兼性共代謝還原機(jī)理及其貢獻(xiàn)被重視,為進(jìn)一步揭示淹水稻田中Fe(Ⅲ)還原的機(jī)理及提高有機(jī)污染物的降解提供理論依據(jù)。
[Abstract]:The process of iron reduction in paddy field and paddy soil carbon, nitrogen, sulfur, phosphorus and other elements geochemical cycle is closely related to Fe (III) reduction process at the same time the oxidative coupling of the degradation of organic pollutants and heavy metals price reduction process, which significantly inhibited the production of methane in paddy field, so the study of paddy field in Fe (III) reduction process and its mechanism has important geochemical and environmental significance. Earlier on Fe (III) reduction process of cognition mainly concentrated in the sediment environment, a large number of studies have confirmed that the reduction process of iron oxide is the alienation of sediments such as anaerobic environment Fe (III) the main way to restore, and co metabolism the reduction process and often anaerobic organic matter decomposition phase coupling, known as Fe (III) secondary reduction pathway. However with sediment in long-term anaerobic environment, formed by the oxidation of paddy upland rotation tillage mode The microbial metabolic reduction environment alternately, organic hydrogen production process has become an important link in the chain of electron transfer. The paddy field in microbial fermentation of organic matter and co metabolism mechanism of the reduction of iron oxide remains to be further in-depth. This research adopts Heng Wenpei anaerobic cultivation methods, typical paddy soils of different planting in our collection, comparison the different soil physicochemical properties of Fe and (III) reduction of the different characteristics, reveal the effect of paddy field in Fe (III) the main factors of the reduction process; by adding different organic carbon source and adjusting soil pH conditions, microbial community structure of organic matter in the process of anaerobic fermentation, dehydrogenation and hydrogen production process Fe (III) the relationship between the reduction process, production of small molecular organic carbon, microbial fermentation process of hydrogen production, acid production of Fe (III) reduction process; by fluorescence excitation. Study on the spectral scanning shoot different paddy soil water fluorescence characteristic of dissolved organic carbon and the main components, reveal the dissolved organic matter and Fe (III) reduction process; biological carbon as the carrier, the use of the characteristics of its high content of aromatic structure and strong adsorption ability, using low molecular weight organic carbon modified biochar, on the promotion of Fe in paddy soils (III) reduction process of the potential, and water soluble organic carbon electron transfer function and microbial fermentation of organic compounds on Fe (III) by reduction of the contribution of this theory to practice. The main results are as follows: (1) in paddy soil after Fe, (II) with the flooding time and the gradual accumulation of different rice soil between Fe (III) there were significant differences in the reduction characteristics. The physicochemical properties of soil, organic matter content and the content of amorphous iron oxides of Fe (III) is the main factor reducing characteristics, both of the two With Fe (III) reduction potential of a and Fe (III) reduction rate of Vmax had a significant positive correlation, and pH is the maximum Fe (III) the main factors of time required for the reduction rate. (2) in paddy soil Fe (III) response regulation of different carbon reduction process because of the different soil vary greatly. The soil microbial pH using glucose induced decrease in the acid paddy soil Fe (III) reduction process. The use of microorganisms in paddy soils of different carbon substrates for fermentation hydrogen production process of dehydrogenation occurred mainly in the initial stage of culture, the hydrogen producing ability from strong to weak glucose pyruvate and lactate dehydrogenase activity, corresponding to the maximum time of microbial iron (III) and Fe reaction time reached the maximum reaction rate (TVmax) is consistent with the training system of pH decreased. It showed that the production of H+ microbial fermentation is the main source of organic carbon To product, Fe (OH) 3 as electron acceptor was consumed by microbial reduction process using different types of carbon source fermentation culture system of h2. pH and H2 and the partial pressure of Fe (II) accumulation had significant negative correlation, indicating that microbial utilization of organic carbon source fermentation to produce organic acid, then influence dehydrogenation of hydrogen production characteristics and effects on the microbial Fe (III) reduction process. (3) can be used as nutrients and iron receptor consumption, flooding microbial communities in paddy soil and potential Fe (III) reduction bacteria showed significant succession. Firmicutes is the most dominant species, with prolonged flooding the relative abundance decreased; acidobacteria, Bacteroidetes, Chloroflexi, Proteobacteria and ignavibacteriae are second kinds of advantages, relative abundance were gradually increased with the flooding time prolonged. Exogenous addition of different concentration of glucose for microbial extract For the abundant carbon source, the microbial community succession lags behind, so that a large number of Firmicutes enrichment, especially with hydrogen fermentation function of Clostridium and bacillus, and the hysteresis effect by increasing the carbon source concentration increased. Different concentrations of glucose to Bacillus and Clostridium enrichment water, formation of paddy soil in Desulfitobacterium, solibacillus, potential Fe anaeromyxobacter and Paenibacillus (III) by reducing bacteria. With addition of different concentrations of glucose when microbial dehydrogenation characteristics of hydrogen production and Fe (III) reduction characteristics, verify the different concentrations of glucose regulated Fe (III) potential reducing bacteria community structure and the dehydrogenation process of hydrogen production of Bacillus and Clostridium in response to changes in community structure the interaction effect of Fe (III) reduction process. (4) the initial pH regulation of paddy soil microbial activity in the dehydrogenation of hydrogen production, the corresponding enzyme activity and Fe (III) Change of solubility and further influence on Fe (III) reduction process. When the regulation of acidic and alkaline paddy soil initial pH Xeon acid or acidic, dehydrogenase activity during incubation was significantly inhibited, which inhibited the acidic paddy soil in alkaline paddy soil can promote the hydrogen production process. Although in this case the acid soluble Fe (III) concentrations were not conditioning significantly increased, but Fe (III) reduction process is still inhibited by lowering the initial pH, so the solubility is not under the condition of low pH iron oxide is Fe (III) reduction process. The main factors regulating paddy soil initial pH to neutral and alkaline. Strong alkaline, dehydrogenation and Fe microorganisms (III) solubility is regulated by pH, the alkaline soil is adjusted to neutral and acidic paddy soil was adjusted to neutral, alkaline and alkaline hydrogen partial pressure decreased significantly, the Fe (III) reduction. Before reaching the maximum reaction rate of Fe (III), reflecting the use and consumption of the hydrogen reduction process. In different initial pH paddy soil Fe (III) during the period of rapid reduction, can with Fe dehydrogenase activity characterization of microbial metabolism of organic matter (II) accumulation is closely related. (5) microbial hydrogen production in paddy soil the dehydrogenation process of soil organic matter fermentation and potential Fe (III) reduction response regulating bacterial community structure on the initial pH directly or indirectly affect the Fe in paddy soil (III) reduction process. When the regulation of acid paddy soil to alkaline after bacterial community structure by adjusting the pH effect and waterlogging affected by initial Firmicutes pH regulates the relative abundance increased. The proportion of Proteobacteria accounted for the alkaline bacteria in paddy soil with initial pH adjusted to acid increased, the bacterial community structure by regulating pH and there is a big difference. The potential of Fe in acid paddy soil (III) reducing bacteria abundance Is not the adjustment increase, corresponding to the increase of Fe (III) Fe to H2 reduction in advance consumption and achieve reduction rate (III); potential Fe alkaline paddy soil (III) reducing bacteria is regulated by the pH inhibition of waterlogging, flooding in the relative abundance of 5d-20d increased, corresponding to waterlogging inhibition of Fe (III) Fe post process and significant reduction in cumulative flooding (II). (6) dissolved organic carbon by scanning and identification of three-dimensional fluorescence spectra of different paddy soil water found 4 common humic like fluorescence components, its main source with exogenous input, the input of endogenous water-soluble supplement. The humification coefficient of organic carbon and Fe (III) there is a significant correlation between the reduction parameters. With large molecular weight UVC terrestrial humic acid on Fe (III) reduction characteristics of the contribution of the highest class UVC+UVA terrestrial humic acid and marine UVA marine humic acid and Fe (III) reduction characteristic parameters Correlation between the number has reached a significant level, while the water soluble organic carbon content. The minimum contribution that paddy soil water soluble organic carbon humification degree and including all kinds of humic acid composition and the content of Fe in paddy soils (III) reduction ability is related. (7) biochar can add promotion of microbial Fe in paddy soil (III) reduction ability, and the effect increases with biochar particle size. The reason for a biological carbon water soluble organic carbon as an electron shuttle acceleration of Fe (III) reduction process; on the other hand, biochar promoted free iron oxide and nitrate the nitrogen content of Fe (III) reduction process. The modified biochar with glucose can not only promote the reduction process of iron oxides in paddy soil, can also reduce the biochar "alkaline group" caused by the increase of pH, and the smaller the particle size effect of biochar more . through this study, the microbial Fe in paddy soil (III) reduction process related to the environmental conditions and Fe (III) to restore the structure and function of microorganisms have more in-depth understanding, discusses the flooded paddy soils in microbial fermentation of organic matter to Fe (III) reduction has an important contribution to rice the soil Fe (III) and co metabolism reduction mechanism and its contribution is emphasized, in order to further reveal the paddy field in Fe (III) provides a theoretical basis for the reduction of the mechanism and improve the degradation of organic pollutants.

【學(xué)位授予單位】：西北農(nóng)林科技大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2017
【分類號】：TQ920.1;S154.3
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本文編號：1407033