發(fā)布時間：2018-03-30 00:12

  本文選題：水鈉錳礦　切入點：Shewanella　出處：《南京大學(xué)》2017年碩士論文

【摘要】：水鈉錳礦是地表環(huán)境中最為常見的錳礦物,也是深海沉積物中常見的自生礦物,業(yè)已發(fā)現(xiàn)水鈉錳礦的形成和轉(zhuǎn)變與多種元素的地球化學(xué)循環(huán)有著密切的關(guān)系。錳結(jié)核的礦物組成決定了錳結(jié)核開發(fā)利用的工藝設(shè)計,其主要礦物水鈉錳礦易隨環(huán)境變化發(fā)生礦物相轉(zhuǎn)變,微生物活動和熱流體作用是引發(fā)物相轉(zhuǎn)變的重要因素。本文在分析深海錳結(jié)核礦物組成和微觀結(jié)構(gòu)的基礎(chǔ)上,以水鈉錳礦還原轉(zhuǎn)化為選題,設(shè)計開展了微生物還原和熱液反應(yīng)兩個系列的模擬實驗,使用多種譜學(xué)和微區(qū)分析技術(shù),初步探究了兩種條件下水鈉錳礦發(fā)生還原轉(zhuǎn)變的路徑和機制�；谀M實驗,研究了水鈉錳礦亞種水羥錳礦被異養(yǎng)金屬還原細菌Schewanella oneidensis MR-1還原的現(xiàn)象。利用場發(fā)射掃描電鏡(FESEM)、場發(fā)射透射電鏡(FETEM)、X-射線衍射光譜(XRD)和激光拉曼分析礦物物相,發(fā)現(xiàn)Schewanella oneidensisMR-1還原水羥錳礦可形成纖維狀鋇鎂錳礦、錳的磷酸鹽礦物、片狀水錳礦和菱猛礦等多種錳價態(tài)的礦物,Schewanella oneidensis MR-1細胞與水羥錳礦的直接接觸或通過納米導(dǎo)線的連接的現(xiàn)象較為普遍;死菌組中則以鋇鎂錳礦和水錳礦為主;而在未接種細菌的培養(yǎng)基條件下,生成三斜水鈉錳礦和少量鋇鎂錳礦等。物相分析和微區(qū)觀察表明:實驗體系的還原程度是決定礦物組成的關(guān)鍵因素。通過模擬實驗,對比研究了熱液回流條件下六方和三斜水鈉錳礦的物相變化。實驗結(jié)果表明:在熱液回流條件下三斜水鈉錳礦比六方水鈉錳礦更易于發(fā)生相變,并且除生成更為平直的纖維狀鋇鎂錳礦外,還觀察到板片狀的鋇鎂錳礦纖維聚集體。這一差別與二者礦物晶體結(jié)構(gòu)的差異有關(guān),三斜水鈉c姑炭蟮拿萄醢嗣嫣迤閿蒑n(Ⅳ)-O八面體和Mn(Ⅲ)-O八面體按2:1的比例交互排列,其結(jié)構(gòu)與鋇鎂錳礦的錳氧八面體排布更為相似,因此更易于轉(zhuǎn)化為鋇鎂錳礦;而六方水鈉錳礦結(jié)構(gòu)中往往存在更多的空穴和缺陷,初始粒徑更小,形態(tài)不規(guī)則,在熱液回流作用下,六方水鈉錳礦優(yōu)先發(fā)生重結(jié)晶作用,然后再進行還原轉(zhuǎn)化,因此表現(xiàn)出還原滯后的表觀現(xiàn)象�；谏鲜鰞山M模擬實驗揭示的水鈉錳礦的還原轉(zhuǎn)化現(xiàn)象,微生物還原作用可將水羥錳礦還原形成多種低價錳礦物,而熱液回流處理僅能得到不同形態(tài)的鋇鎂錳礦;不同結(jié)構(gòu)水鈉錳礦在熱液回流過程中表現(xiàn)出不同的動力學(xué)特征,三斜水鈉錳礦更易于相變形成結(jié)晶形態(tài)更好的鋇鎂錳礦。上述認識不僅有助于理解多種環(huán)境條件下水鈉錳礦的物相轉(zhuǎn)化行為,還為判識水鈉錳礦的微生物轉(zhuǎn)化作用提出了礦物學(xué)依據(jù)。
[Abstract]:Sodium manganite is the most common manganese mineral in the surface environment, and it is also a common authigenic mineral in deep-sea sediments. It has been found that the formation and transformation of sodium manganese ore is closely related to the geochemical cycle of many elements. The mineral composition of manganese nodules determines the technological design for the development and utilization of manganese nodules. The main mineral, sodium manganite, is prone to change with the change of environment, and microbial activity and thermal fluid action are important factors in the phase transition of the initiator. In this paper, the mineral composition and microstructure of deep-sea manganese nodules are analyzed. Two series of simulation experiments, microbial reduction and hydrothermal reaction, were designed and carried out by using a variety of spectroscopic and microanalysis techniques. The path and mechanism of the reduction transition of sodium manganese ore in water under two conditions are preliminarily explored. The reduction of ferromanganese ore subspecies by heterotrophic metal reductive bacteria Schewanella oneidensis MR-1 was studied. Field emission scanning electron microscopy (SEM), field emission transmission electron microscopy (TEM), field emission transmission electron microscopy (TEM) and laser Raman spectroscopy (LRS) were used to analyze the mineral phases. It is found that Schewanella oneidensisMR-1 can form fibrous barium manganite, manganese phosphate mineral. The phenomena of direct contact with or connection by nanoscale conductors of many kinds of manganese valence minerals Schewanella oneidensis MR-1 cells, such as lamellar manganite and rhombotite, are common, while barium magnesium manganese and manganite are dominant in the dead bacteria group. But under the condition of no bacteria inoculation, the sodium manganite and a small amount of barium manganese ore were formed. The results of phase analysis and microregional observation show that the reduction degree of the experimental system is the key factor to determine the mineral composition. The phase changes of hexagonal and triclinic sodium manganese ores under hydrothermal reflux conditions are compared. The experimental results show that the phase transition of hexagonal sodium manganese ores is easier than that of hexagonal sodium manganese ores under hydrothermal reflux conditions. In addition to the more flat fibrous barium magnesium manganese ore, the lamellar barium magnesium manganese fiber aggregates were observed. This difference is related to the difference of mineral crystal structure between them. The octahedron (鈪，

本文編號：1683494