直接/间接作用模式下一株短小芽孢杆菌对蒙脱石层间域特性的影响研究

为探讨直接/间接作用模式下土壤常驻菌对蒙脱石层间距、层电荷及层间介质的影响,从绵阳地区紫色土壤中分离选取1株短小芽孢杆菌,利用透析袋,建立土壤菌与蒙脱石"接触"与"非接触"体系进行相互作用实验。作用5 d后的结果表明,蒙脱石样品层间距变小,样品M-1和M-2的d001值从1.486 nm分别减小到1.246 nm和1.257 nm,单位半晶胞层电荷数减少,且ξMMTξM-2ξM-1,FTIR分析显示作用后蒙脱石样品出现来自蛋白质酰胺Ⅱ带及蛋白质分子甲基的新特征峰,层间水分子3434 cm-1、1637 cm-1处的峰发生偏移,此外阳离子交换容量也发生明显改变。土壤菌的生物作用能改变蒙脱石的层间距、层电荷及层间介质,使其结构和性质发生改变。对比2种作用方式与作用后蒙脱石层间域特性的改变分析可知,接触作用对蒙脱石层间域特性的改变效果强于非接触作用。     

土壤菌与蒙脱石相互作用特性研究

为了探讨土壤菌与蒙脱石相互作用体系的特性,本文选取了11株吸附Sr2+效果较好的土壤菌株与提纯好的蒙脱石进行相互作用。通过对土壤菌与蒙脱石相互作用1d后培养液的pH值、葡萄糖(GLU)、Ca2+、Mg2+、Na+等的变化测试,比较了土壤菌株与蒙脱石作用后的特性变化;利用XRD分析,对土壤菌作用后的蒙脱石层间距变化进行了初步研究。结果表明吸附Sr2+效果较好的菌株大多数消耗GLU,阴性菌占大多数;与蒙脱石作用1 d后,GLU消耗率提高。与蒙脱石作用后,溶液pH有所上升。离子溶出比例趋势:Ca2+>Mg2+>Na+。蒙脱石与土壤菌相互作用1d后,层间距都有所增大,层间距的扩增与GLU消耗呈现一定的关系。与革兰氏阴性菌相比较,革兰氏阳性菌与蒙脱石相互作用1d后,蒙脱石层间距的扩增较大。     

胶质芽孢杆菌3027对钙基蒙脱石的矿物结构影响

粘土矿物在地球表层分布广泛,与微生物的交互作用十分常见。微生物能否通过除还原Fe(Ⅲ)之外的其他途径影响贫铁蒙脱石的结构与物相,成为粘土矿物与微生物交互作用的新问题。本研究选取胶质芽孢杆菌Bacillus mucilaginosus 3027与钙基蒙脱石在35℃、常压条件下进行交互作用实验,考察胶质芽孢杆菌生命活动对蒙脱石晶体结构的影响。实验定期取样进行pH值与体系总蛋白含量测试,并利用显微傅里叶变换红外光谱(micro-FTIR)、同步辐射X射线近边吸收结构(XANES)、X射线衍射(XRD)和扫描电镜(SEM)对最终产物进行矿物学表征。实验结果显示,胶质芽孢杆菌在蒙脱石矿物悬浊液中生长,代谢分泌大量有机酸导致体系pH值降低,使蒙脱石中Si元素溶出,并造成蒙脱石晶体结构中硅氧四面体对称性、O—H振动等发生变化,Fe配位八面体对称性下降,矿物表面出现边缘卷曲现象。在微生物作用后的矿物样品中,探测到新形成的α-石英物相,可能与微生物的活动密切相关。     

蒙脱石作为尿素缓释基质的试验研究

采用一定的方法可使尿素进入蒙脱石层间,形成蒙脱石尿素夹层复合体。在一定范围内,随着尿素夹入量的增加,复合体的晶面间距（d001）逐渐增大。与钙基蒙脱石-尿素夹层复合体相比,钠基蒙脱石-尿素夹层复合体的尿素夹入量较大,并且置于土壤后尿素分子释放较快。蒙脱石-尿素夹层复合体在尿素的不断释放过程中,其出d001值逐渐减小并趋向于恢复到夹层作用前蒙脱石的d001值。蒙脱石可望在农业上作为尿素缓释基质。     

浙江膨润土资源的前景

膨润土是以蒙脱石为主要成分(一般大于50%)的粘土矿物.蒙脱石属二八面体含水的层状铝硅酸盐类矿物.由于蒙脱石结构单元层中的硅和铝离子,分别被铝和镁离子置换因而层间出现电荷有吸附阳离子的作用.根据层间阳离子的不同,可分为钠基膨润土、钙基膨润土、镁基膨润土以及钙     

阪崎克洛诺菌还原蒙脱石中Fe~(3+)实验研究

为研究阪崎克洛诺菌(Cronobacter Sakazakii)还原普通钙基蒙脱石中Fe3+的过程与机理,测定了体系中总蛋白与Fe2+含量变化,应用同步辐射XRD(SRXRD)与X射线吸收近边结构(XANES)研究反应产物。总蛋白与Fe2+数据表明在厌氧条件下Cronobacter sakazakii以乙酸作为电子供体,利用钙基蒙脱石中Fe3+作为电子受体进行生长代谢,还原蒙脱石中Fe3+形成Fe2+。反应中蒙脱石晶体结构部分破坏,原始的d001峰消失,出现一系列与新生矿物有关的衍射峰。XANES结果显示蒙脱石中Fe主吸收峰向低能量方向移动0.5 e V,边前峰峰位中心向低能量方向移动且峰面积减小,Fe氧化态降低,蒙脱石晶体结构发生变化。研究探讨了自然界中广泛分布的钙基蒙脱石可能受到的微生物还原作用。     

微生物降解蒙脱石层间吸附有机质的实验研究

近年来,国内外学者意识到,有机质在蒙脱石结构层间的吸附是有机质保存的重要机理之一,然而,目前关于微生物能否降解蒙脱石层间吸附有机质以及降解的程度等尚没有任何实验数据的支撑。本文试图通过人工合成含有层间吸附有机质的蒙脱石,利用海洋和湖泊沉积物中常见的降解有机质的微生物对其进行降解实验,据此探讨有机质的蒙脱石层间吸附在沉积物埋藏过程中对有机质保存的贡献。有机质选择半胱氨酸和甲苯,前者是生物生长所需的一种重要氨基酸,后者大量存在于土壤和沉积物中,多种细菌可以在有碳氢化合物的环境下将其降解。实验菌种选择恶臭假单胞杆菌(Pseudomonas putida)和腐败希瓦氏菌(Shewanella putrefaciens CN32)2种细菌,它们均为海洋和湖泊沉积物中的主导微生物,前者有较强的有机质降解能力,后者为铁的还原菌,厌氧代谢过程中能将蒙脱石结构中的Fe(III)还原为Fe(II)。通过上述不同菌种对蒙脱石层间吸附不同性质有机质的降解实验,结果显示,微生物对蒙脱石层间吸附的有机质的降解方式主要有分泌有机酸直接降解和破坏层间结构释放有机物从而进行降解。代表菌种假单胞菌和希瓦氏菌对半胱氨酸绿脱石及甲苯绿脱石的作用表明,微生物通过分泌有机酸的形式对蒙脱石层间吸附的有机质降解作用很有限,该结构在恒定的有氧和无氧条件下对保存有机质有利;希瓦氏菌在严格无氧条件下通过还原Fe(III)进行代谢,实验表明,无氧条件下,希瓦氏菌可以一定程度破坏矿物结构,释放并消耗有机物,因此,铁还原微生物对蒙脱石层间吸附有机质的保存有一定的影响,但由于微生物对矿物晶体结构的破坏能力有限,故其对层间吸附有机质降解的能力也有限;不同有机物对生物降解过程也有影响,这些影响取决于有机质的特性及有机质与细菌之间的相互作用。绿脱石层间吸附的半胱氨酸对生物生长有利,从而可能促进生物还原Fe(III)作用。相反,甲苯却很明显的抑制了Fe(III)的还原。由此可见,有机质的蒙脱石层间吸附是有机质保存的重要方式之一。     

安徽宣城红土剖面中粘土矿物过渡相及其意义

为研究长江中下游红土剖面中粘土矿物的特征及其成因意义, 对安徽宣城红土剖面中粘土矿物进行深入、系统的X射线衍射分析.结果表明, 宣城剖面各土壤层中粘土矿物成分基本一致, 主要为蛭石、伊利石、高岭石, 以及粘土矿物过渡相. 由采自剖面上部样品的X射线衍射图可知, 经乙二醇饱和后7 ?衍射峰可分解为7.15、7.60和7.92 ?三部分, 表明除了高岭石(7.15 ?)外, 还存在高岭晶层含量分别为~80%和~95%的2种高岭-蒙脱石过渡相, 并以前者为主; 剖面下部样品在乙二醇饱和后, 7 ?衍射峰可分解为7.16、7.79和8.35 ?等3个衍射峰, 其中8.35 ?峰衍射强度很小, 表明除了高岭石外, 样品中存在高岭晶层含量为~90%和~43%的高岭-蒙脱石过渡相, 后者含量甚少.甲酰胺饱和结果表明, 高岭-蒙脱石混层粘土矿物相中高岭晶层为埃洛石相.加热试验的衍射图中10 ?衍射峰强度明显增强, 证实高岭相中含有一定数量的来源于绿泥石风化的蒙脱石间层; 而10 ?衍射峰的低角度一侧没有出现拖尾现象, 则指示高岭-蒙脱石混层矿物中的蒙脱石不是简单的羟基间层蒙脱石.此外, 红土剖面中还普遍出现过渡性粘土矿物伊利石-蒙脱石混层和伊利石-蛭石混层粘土矿物.大量过渡性粘土矿物相的出现, 从成土作用的角度上说明红土沉积物经历了沉积-风化、以及多期风化作用叠加, 而且在沉积-风化成土过程中, 气候环境变化于强烈化学风化的温暖、季节性干旱和强烈风化淋滤的温暖而更加潮湿的条件.蛭石-伊利石混层粘土矿物仅发育于红土剖面上部, 表明总体上剖面上部的化学风化程度低于剖面下部.      

蒙脱石红移、蓝移及水化特征的谱学分析

对提纯蒙脱石、钠化蒙脱石、有机插层蒙脱石进行紫外-可见光学吸收谱分析、红外光谱分析,发现蒙脱石随着粒度的变化产生红移和蓝移现象。1631插层样品较钠化样品红移20 nm以上,而提纯的胶体粒子样品较1631插层样品SM G-1631红移80 nm;由于提纯蒙脱石样品粒度变细羟基伸缩振动吸收峰向高波数移动了1.69 cm-1,即蓝移了1.69cm-1。蒙脱石水化性能的XRD分析表明,蒙脱石吸水后晶层发生膨胀、剥离,脱水时分散后的晶层发生凝聚作用,即面-面结合作用,形成蒙脱石“定向性层状集合体”衍射峰的d值产生了相应的变化,这种凝聚作用是蒙脱石分散剥离的逆作用,但凝聚后形成的凝聚蒙脱石的衍射谱特征与原始蒙脱石的大不相同。蒙脱石红移、蓝移及水化特征的谱学分析研究丰富了天然纳米蒙脱石矿物材料晶体化学研究的内容,具有重要的理论意义。     

蒙脱石晶体结构和水结构的矿物物理特征

本文利用矿物物理研究方法对我国内蒙、浙江、甘肃等地的钙基、钠基、镁基蒙脱石的物质成分、晶体结构和层间OH,H_2O的排布结构进行了研究,并获得下列结论: 1.由X衍射和拉曼分子光谱分析深入研究了蒙脱石阳离子配位体结构特征,提出其空间群为C_(2/m) 型。 2.建立了蒙脱石水结构模式,有3种主要类型:①层间大阳离子附近的束缚态水分子;②层间无大阳离子位置上的非束缚态水分子;③颗粒表面依靠氢键相连的水分子集合体。 3.利用群理沦,提出了蒙脱石OH～-的振动模式,由振动分析指出蒙脱石中OH～-具有12个振动模式。     

矿物-腐植酸-微生物体系对重金属吸附研究

设施农业中土壤重金属污染问题日趋严重.由于土壤中矿物、腐植酸、微生物等多相组分之间存在交互作用,重金属与土壤单组分体系中所获得的结合机制并不能真实有效地评价其在自然条件下的转化与归趋.本研究以蒙脱石(Mont)和高岭石(Kao)为辽宁蔬菜大棚及农田土壤层状硅酸盐代表矿物,选取胡敏酸(HA)为有机质代表,土著微生物革兰氏...     

海洋粘土矿物与颗石藻Emiliania huxleyi共培养的实验研究

颗石藻是海洋中广泛分布的超微型浮游藻,经生物矿化作用形成的碳酸钙质颗石,在古海洋学研究中具有重要意义。海洋粘土矿物与有机质的有机-无机相互作用在全球碳循环中扮演着重要角色。本文选取广泛分布于海洋的赫氏颗石藻Emiliania huxleyi与海洋粘土矿物中具有代表性的伊利石和蒙脱石共培养。通过对颗石藻生长曲线和Sr/Ca、Mg/Ca元素比值、颗石藻与粘土矿物样品的紫外可见光吸收光谱、红外吸收光谱和矿物物相等分析,研究海洋粘土矿物与颗石藻的相互作用规律。通过研究表明伊利石对颗石藻的影响较小,蒙脱石因对营养元素的吸附和颗石藻的絮凝作用对颗石藻的生长和Sr/Ca、Mg/Ca元素比值影响较大。颗石藻代谢分泌的生物分子未能通过层间插层作用进入伊利石层间,颗石藻分泌的生物分子可通过插层作用进入并储存于蒙脱石层间,海洋粘土矿物中的蒙脱石与海洋微生物的相互作用值得地球微生物家关注,可能有助于对古海洋环境的认识。     

Functional groups in a single pteridosperm species: Variability and circumscription (Pennsylvanian, Nova Scotia, Canada)

Multiple foliar specimens of the Late Pennsylvanian fossil pteridosperm [gymnosperm] Alethopteris zeilleri (Ragot) Wagner were collected from one restricted stratigraphical horizon in the Canadian Sydney Coalfield. Variability of functional-group distribution using FTIR technique was studied in compressions, adaxial versus abaxial cuticles, and in unseparated cuticles as a function of maceration time from 48 to 168 h. The results obtained document spectral variability that could be expected within specimens of one species. For example, CH₂/CH₃ and Al/ox ratios can differ by as much as 20% of the values. Moreover, the experiments performed confirm that by using a previously established maceration protocol, long maceration periods do not bias FTIR spectra in terms of oxygenation overprinting. The inference that this cuticle is robust, under the given diagenetic level, probably reflects a reassuring degree of chemical fidelity of the Pennsylvanian plant to support Carboniferous chemotaxonomic observations.     

Interactions between <Emphasis Type="Italic">Bacillus mucilaginosus</Emphasis> and silicate minerals (weathered adamellite and feldspar): Weathering rate,products, and reaction mechanisms

Bacillus mucilaginosus is a common soil bacterium,and usually used as a model bacterium in studying microbe-mineral interactions.Several reaction mechanisms of B.mucilaginosus weathering silicate minerals were proposed.However,the molecule mechanisms and detailed processes were still unclear.In this paper,bacterium-mineral interactions were studied in terms of variations in pH value over the experimental period,variations in mineral composition,weathering rates of silicate minerals and volatile metabolites in the culture medium,etc.,to further explore the bacterium-mineral interaction mechanisms.The results showed that B.mucilaginosus could enhance silicate mineral weathering obviously.The weathering rates were quite different for various kinds of silicate minerals,and the weathering rate of weathered adamellite could reach 150 mg/m2/d.Although B.mucilaginosus produced little acidic substance,pH in the microenvironment of bacterium-mineral complex might be far lower than that of the circumjacent environment;a large amount of acetic acid was found in the metabolites,and was likely to play an important role as a ligand.These results appear to suggest that acidolysis and ligand degradation are the main mechanisms of B.mucilaginosus dissolving silicate minerals,the formation of bacterium-mineral complexes is the necessary condition for the bacteria weathering silicate minerals,and extracelluar polysaccharides played important roles in bacterium-mineral interaction processes by forming bacterium-mineral complexes and maintaining the spe-cial physicochemical properties of microenvironment.     

Speleothems from Mawsmai and Krem Phyllut caves,Meghalaya, India: some evidences on biogenic activities

The Mawsmai cave and Krem Phyllut caves, East Khasi hills, Meghalaya, India has so far not yet attracted the attention of geomicrobiologists. Observations and hypotheses on the possible influence of identified microorganisms for speleothem formations in Meghalaya are reported for the first time. XRD studies identified calcite in speleothems and gypsum in cave wall deposits as the dominant minerals. SEM-EDAX showed interesting microfabric features showing strong resemblance with fossilised bacteria, calcified filaments, needle calcite and numerous nano scale calcite crystals, highly weathered and disintegrated crystals of calcite, that point towards a significant microbial influence in its genesis. Thin section petrography showed laminated stromatolitic features. The microorganisms identified by conventional isolation and further evaluation of isolates by molecular techniques include Bacillus cereus, Bacillus mycoides, Bacillus licheniformis, Micrococcus luteus, and Actinomycetes. Microscopic observations also showed unidentifiable cocci and four unidentifiable strains of CaSO₄ (gypsum) precipitating bacteria. Experimental studies confirmed that these bacteria are able to precipitate calcium minerals (calcite, gypsum, minor amounts of dolomite) in the laboratory. These results allow us to postulate that species like these may contribute to active biogenic influence in the cave formations at Meghalaya.     

Potential protonation sites in the Al<Subscript>2</Subscript>SiO<Subscript>5</Subscript> polymorphs based on polarized FTIR spectroscopy and properties of the electron density distribution

Potential protonation sites for, kyanite, sillimanite, and andalusite, located in a mapping of the (3, −3) critical points displayed by their L(r) = −∇²ρ(r) distributions, are compared with polarized single-crystal FTIR spectra of kyanite and sillimanite determined earlier and with andalusite measured in this study. For andalusite, seven peaks were observed when the electric vector, E, is parallel to [100]: four intense ones at 3,440, 3,460, 3,526, and 3,597 cm⁻¹ and three weaker ones at 3,480, 3,520, and 3,653 cm⁻¹. Six peaks, three intense ones at 3,440, 3,460, and 3,526 cm⁻¹ and three weaker ones at 3,480, 3,520, and 3,653 cm⁻¹ when E parallels [010]. No peaks were observed when E is parallel to [001]. The concentration of water in andalusite varies between 110 and 168 ppm by weight % H₂O. Polarized FTIR spectra indicate that the OH vector is parallel to (001) in andalusite and sillimanite and in kyanite. Examination of the L(r) (3, −3) critical points in comparison with the polarized FTIR indicates that H prefers to bond to the oxygen atoms O1 and O2 in andalusite and O2 and O4 in sillimanite which correspond to the underbonded oxygen atoms and those with the largest L(r) maxima. In kyanite, comparison of the FTIR spectrum and the critical points indicates that H will preferentially bond to the two 4-coordinated O2 and O6 atoms.     

铁细菌培养过程中低分子有机酸钠盐对含硫酸根铁矿物形成的影响

普遍存在环境中的低分子有机酸盐对氧化亚铁硫杆菌的矿化产物(施氏矿和黄钾铁矾等铁矿物)会产生影响,从而导致环境中有毒重金属迁移转化发生变化.本文探讨了低分子有机酸钠盐对铁细菌HX3成长过程中代谢产物铁矿物的影响,并利用XRD、FTIR、FESEM和EDS对形成的铁矿物进行了表征与分析.研究结果表明,低浓度低分子有机酸钠盐...     

Effect on physico-chemical and structural properties of soil amended with distillery effluent and ameliorated by cropping two cereal plant spp.

Molasses-based distilleries are one of the most polluting industries generating large volume of wastewater. Distillery effluent (DE) on its discharge alters the physical and chemical properties of the soil. This study has been conducted to assess the distribution of heavy metals and its effect on physiochemical and structural changes of soil which has been treated with diluted and undiluted effluents. The soil has been assayed both before and after crop plantation. Out of the crop plants studied, Cicer arietinum was least effected and more effective than Pisum sativum in diminishing the heavy metals from soil. However, only at higher concentration DE has some adverse impact on the nutrient contents of the soil. Fourier transform infrared spectrum (FTIR) study of the soil indicated the presence of –OH, –NH, –COOH groups. It was also noted that the soil amended with different concentration of DE and on which Cicer and Pisum were grown has varied IR spectrum. These variations show the presence of different functional groups of soil before and after plants were grown. The presence of inorganic carbonate was found in soil planted with Cicer from 10 to 50% of DE, whereas aliphatic primary amides were observed up to 25 and 100% concentrations of DE in soil planted with Pisum. The appearance of inorganic nitrates, carbonates, aliphatic hydrocarbons and aliphatic primary amides at various concentrations of DE showed a change in functional groups probably because of the differential breakdown of parent component present in the effluent. Besides our main finding that Cicer is a very useful crop species in remediating the soil which has inflicted with even undiluted DE, it is also validated through FTIR spectra that IR technique is an efficient tool in studying the structural changes of soil and with some degree of caution may be summed up that FTIR may be used to correlate the relative efficacy of plants to transform organic contaminants.     

The single-crystal,polarized-light,FTIR spectrum of stoppaniite,the Fe analogue of beryl

We report here a single-crystal polarized-light study of stoppaniite, ideally (Fe,Al,Mg)₄(Be₆Si₁₂O₃₆)(H₂O)₂(Na,□), from Capranica (Viterbo). Polarized-light FTIR spectra were collected on an oriented (hk0) section, doubly polished to 15 μm. The spectrum shows two main bands at 3,660 and 3,595 cm⁻¹; the former is strongly polarized for E ⊥c, while the latter is polarized for E //c. A sharp and very intense band at 1,620 cm⁻¹, plus minor features at 4,000 and 3,228 cm⁻¹ are also polarized for E //c. On the basis of literature data and considering the pleochroic behavior of the absorptions, the 3,660 cm⁻¹ band is assigned to the ν₃ stretching mode and the 1,620 cm⁻¹ (associated with an overtone 2*ν₂ at 3,230 cm⁻¹) band to the ν₂ bending mode of “type II” water molecules within the structural channels of the studied beryl. The sharp band at 3,595 cm⁻¹ is not associated with a corresponding ν₂ bending mode; thus it is assigned to the stretching vibration of O–H groups in the sample. The minor 4,000 cm⁻¹ feature can be assigned to the combination of the O–H bond parallel to c with a low-frequency metal-oxygen mode such as the Na–O stretching mode. The present results suggest that the interpretation of the FTIR spectrum of Na-rich beryl needs to be carefully reconsidered.     

Molecular simulation of humic substance-Ca-montmorillonite complexes

An understanding of the processes that lead to long-term stabilization of organic matter in soils is essential to the effective implementation of strategies designed to mitigate CO₂ loss from the soil carbon reservoir in temperate climatic zones. Decomposition studies indicate that montmorillonite, a smectite that often forms with interlayers rich in Ca²⁺, greatly retards the microbial mineralization of soil organic matter. We performed a series of atomistic simulations designed to identify favorable molecular-scale organo-mineral interactions within nanoscale, hydrated complexes consisting of a humic substance and Ca-montmorillonite. Both protonated and Ca-saturated forms of the model humic molecule, representing acidic and circumneutral solution conditions, respectively, were studied within the hydrated interlayer region of a rigid-atom model of Ca-montmorillonite. The protonated humic substance formed direct hydrophobic and hydrogen bonding (H-bonding) interactions with the clay mineral. A few polar organic groups adsorbed via water bridging interactions. The Ca-saturated humic substance adsorbed via numerous cation bridges, less numerous water bridges, and indirect H-bonding interactions mediated by water molecules. Application of molecular modeling techniques to this complex organo-mineral system thus allowed identification of interactions favorable to carbon sequestration under both acidic and circumneutral conditions.