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。     

微生物对绿脱石中有机质利用的研究

为了探索黏土矿物中含有的有机质能否被微生物利用以及微生物利用的效率,本文选取富三价铁的黏土矿物绿脱石NAu-2为还原对象,嗜热菌Thermus scotoductus SA-01,以及常温菌Shewanella putrefaciens CN-32为异化铁还原菌,分别在没有外加碳源的情况下对NAu-2结构铁进行还原。实验选取化学方法来测试Fe3+还原程度与还原速率,利用X射线粉晶衍射(XRD)、傅里叶转换红外光谱分析仪(FTIR)、扫描电镜(SEM)对黏土矿物还原产物进行矿物学表征,利用总碳/氮分析仪测试黏土矿物释放出来的溶解碳总量以及高效液相色谱仪来分析不同有机组分的含量。实验结果表明相对于常温菌CN-32,嗜热菌SA-01可以有效利用绿脱石中含有的微量有机质作为碳源。由此可知,黏土矿物经微生物作用后发生还原溶解,其吸附的有机质会随着溶解程度的升高不断释放到周围环境中;黏土矿物含有的有机质组分成分复杂,在不同温度环境下释放出来的有机质速率与种类有所不同。     

微生物铁还原作用对蒙脱石保存有机物的影响:以硫酸盐还原菌为例

本文研究了微生物的铁还原作用对黏土矿物有机质保存的影响。将一种有机化合物(十二氨基十二酸)插层到一种富铁的蒙脱石(绿脱石)中,利用硫酸盐还原菌(Desulfovibrio vulgaris)分别对插层前后的绿脱石进行作用,以研究该菌对绿脱石结构中Fe3+的还原作用以及层间有机物的影响。结果发现,1Desulfovibrio vulgaris能够还原这2种绿脱石结构中的Fe3+,且电子穿梭体AQDS(蒽醌-2,6-二磺酸)能够增强还原速率和程度;2硫酸盐的存在能够增加还原速率和程度,表明还原过程中生成的硫化物与绿脱石结构中的Fe3+发生了化学还原作用;3通过X射线衍射、红外光谱、总有机碳分析表明,还原后的绿脱石,其结构层内仍有大量有机物,具有一定的稳定性和保存层间有机质的能力。     

柱撑粘土矿物层间域的性质及其环境意义

柱撑粘土矿物是近年来胺国内外矿物学广泛关注的矿物材料之一。柱撑粘土矿物层间域是一个特殊的化学反应场所。本系统评述了氮氧化物、重金属离子、阴离子、肥料养分及有机污染物等环境污染物在柱撑粘土矿物层间域中的催化还原、吸附、脱附、控释及光催化反应机理，着重阐述了柱撑粘土矿物的层间域性质，讨论了它们的环境化学行为对环境的影响和意义。     

海水中钢铁锈层的微生物成因及其环境效应

研究了海水环境中钢铁腐蚀产物即锈层中的厌氧微生物群落和锈层矿物特征及其相关性。微生物富集培养和初步的分子生物学分析结果表明,海水钢铁锈层中至少生存有硫酸盐还原细菌和铁还原细菌两种厌氧细菌。使用扫描电子显微镜和电子能谱、X-射线衍射仪等对锈层样品进行了矿物学观察和分析。在外锈层和中间锈层,主要是α,β,γ-FeOOH等铁(水合)氧化物。铁水合硫酸盐即绿锈则主要出现在内锈层。初步讨论了厌氧细菌作用下的铁腐蚀矿物生成和转化过程,并提出钢铁锈层微生物和矿物在海洋环境的微生物修复中可能具有重要作用。     

腐殖酸对微生物还原绿脱石结构Fe(Ⅲ)的促进作用

微生物介导的铁循环是调控地表有害物质迁移转化等地球化学反应的关键因子之一。为了探明腐殖酸对微生物还原含铁黏土矿物的影响,选取了富铁黏土矿物绿脱石和不同土壤中提取到的腐殖酸为研究对象进行了实验,在有、无腐殖酸2种条件下对比了典型异化铁还原菌Shewanella putrefaciens CN32对绿脱石结构Fe(Ⅲ)的还原效率,同时分析了微生物作用后绿脱石的晶体结构差异。实验采用化学方法检测Fe(Ⅲ)的还原程度,利用X射线粉晶衍射(XRD)及傅里叶转换红外光谱(FT-IR)对微生物作用前后的绿脱石进行了矿物学表征,利用扫描电镜(SEM)研究了反应前后绿脱石的形貌差异。实验结果表明不同来源的腐殖酸均具有促进微生物还原绿脱石结构Fe(Ⅲ)的能力,但其促进效率存在差异。绿脱石中的结构Fe(Ⅲ)经微生物还原后,其矿物结构被破坏,结晶程度逐渐降低,矿物形貌由不规则片状变为松散疏松的网絮状。本研究对深入理解自然环境中铁的生物地球化学循环及其环境效应具有启示意义。     

铁还原细菌矿化产物及其对铁建造沉积的指示意义

铁还原细菌是微生物诱导矿化的典范之一, 它可以利用有机质或氢气作为电子供体还原三价铁, 并在细胞外矿化形成多种含铁矿物, 比如磁铁矿、菱铁矿、蓝铁矿和绿锈等矿物, 从而广泛参与自然界中铁元素的生物地球化学循环过程。本文主要介绍铁还原细菌矿化产物的矿物特征、形成条件和影响因素。此外, 通过实验室内建立严格厌氧的环境体系, 以与微量元素共沉淀的水合氧化铁为底物, 本研究分别利用Fe_aq²⁺和铁还原细菌Shewanella oneidensis MR-4合成非生物成因和生物成因的磁铁矿, 结果发现微量元素的存在会改变磁铁矿的形貌和粒径。结合前人提出的微生物可能参与铁建造沉积的过程, 本文评估了微量元素作为识别矿物成因指标的有效性, 探讨铁还原细菌矿化产物对铁建造沉积的潜在贡献。

     

柴西地区第三系发育平行层面缝岩石的粘土矿物特征

柴西地区第三系地层中多发育平行层面缝,通过岩心及荧光显微镜观察并借助扫描电子显微镜(SEM)和X射线衍射仪(XRD),确定了柴西地区第三系发育平行层面缝岩石自上而下存在2种粘土矿物组合:伊/蒙间层+伊利石+绿泥石+(高岭石)→伊利石+绿泥石+伊/蒙间层+绿/蒙间层+(高岭石),粘土矿物占全岩矿物比例介于7%～27%之间,粘土矿物吸附并保存了有机质,这是异常高压、强还原环境、有机质及平行层面缝优势输导体系和强水动力作用多种因素叠加影响的结果。     

矿物-微生物相互作用在环境治理中的应用

随着国民经济的高速发展,环境污染问题日益突出。工业生产及矿山开采大量排放重金属铀与铬,造成了水体与土壤的污染。重金属治理有多种方法,微生物还原法成本低、见效快,但其缺点是随着环境条件的改变,它们会重新进入环境造成二次污染。我们课题组提出用矿物-重金属-微生物相结合的方法降低二次污染。首先用细菌将黏土矿物结构中的铁还原成Fe(II),再用Fe(II)还原U(VI)、Tc(VI)与Cr(VI)以降低它们在水体中的溶解度而从环境介质去除。因为还原以后的重金属被包裹在渗透性差的黏土矿物结构或集合体内,与外界隔离,降低二次污染的发生。但是该方案是否可行决定于粘土矿物的氧化还原电位、矿物理化性质、反应条件、重金属与粘土矿物的显微共生关系等。本报告将回顾总结我们十多年来的工作,重点介绍典型黏土矿物蒙脱石还原U(VI)与Cr(VI)的速率与程度和黏土矿物物理化学性质的关系,还原以后的产物以及造成二次污染的可能性,最后对这一方法在野外污染区的应用前景提出一些展望。     

蒙脱石层间域的性质及其环境意义

蒙脱石矿物是土壤中比表面积大、分布很广的一种粘土矿物,也是土壤中主要的活性组分之一。蒙脱石层间域是一个特殊的化学反应场所。系统地评述了无机、有机阳离子、农药分子在蒙脱石层间域中的吸附、脱附、氧化还原、催化降解等反应机理,并指出它们的环境化学行为对环境的影响和意义。     

The terrestrial fauna of the Late Triassic Pant-y-ffynnon Quarry fissures,South Wales,UK and a new species of Clevosaurus (Lepidosauria: Rhynchocephalia)

Pant-y-ffynnon Quarry in South Wales yielded a rich cache of fossils in the early 1950s, including articulated specimens of new species (the small sauropodomorph dinosaur Pantydraco caducus and the crocodylomorph Terrestrisuchus gracilis), but no substantial study of the wider fauna of the Pant-y-ffynnon fissure systems has been published. Here, our overview of existing specimens, a few described but mostly undescribed, as well as freshly processed material, provides a comprehensive picture of the Pant-y-ffynnon palaeo-island of the Late Triassic. This was an island with a relatively impoverished fauna dominated by small clevosaurs (rhynchocephalians), including a new species, Clevosaurus cambrica, described here from a partially articulated specimen and isolated bones. The new species has a dental morphology that is intermediate between the Late Triassic Clevosaurus hudsoni, from Cromhall Quarry to the east, and the younger C. convallis from Pant Quarry to the west, suggesting adaptive radiation of clevosaurs in the palaeo-archipelago. The larger reptiles on the palaeo-island do not exceed 1.5?m in length, including a small carnivorous crocodylomorph, Terrestrisuchus, and a possible example of insular dwarfism in the basal dinosaur Pantydraco.     

The effect of water on accessory phase solubility in subaluminous and peralkaline granitic melts

The solubilities of columbite, tantalite, wolframite, rutile, zircon and hafnon were determined as a function of the water contents in peralkaline and subaluminous granite melts. All experiments were conducted at 1035 °C and 2 kbar and the water contents of the melts ranged from nominally dry to approximately 6 wt.% H₂O. Accessory phase solubilities are not affected by the water content of the peralkaline melt. By contrast, solubilities are affected by the water content of the subaluminous melt, where the solubilities of all the accessory phases examined increase with the water content of the melt, up to 2 wt.% H₂O. At higher water contents, solubilities are nearly constant. It can be concluded that water is not an important control of accessory phase solubility, although the water content will affect diffusivities of components in the melt, thus whether or not accessory phases will be present as restite material. The solubility behaviour in the subaluminous and peralkaline melts supports previous spectroscopic studies, which have observed differences in the coordination of high field strength elements in dry vs. wet subaluminous granitic glasses, but not for peralkaline granitic glasses. Lastly, the fact that wolframite solubility increases with increasing water content in the subaluminous melt suggests that tungsten dissolved as a hexavalent species.     

Quaternary stresses revealed by calcite twinning inversion: insights from observations in the Savonnières underground quarry (eastern France)

Calcite samples were extracted both from the rock matrix and the superficial coating of a karstified fault plane of an underground quarry, located in the eastern border of the Paris basin. The karstification is dated as Quaternary. Analysis of mechanical calcite twinning reveals that only the calcite matrix has also undergone a compression trending WNW that can be attributed to the Mio-Pliocene alpine collision. Both coating and matrix have undergone a strike-slip regime with σ₁ roughly trending north–south, that could correspond to the regional present-day state of stress, a strike-slip compression rather trending NNW, modified by local phenomena. To cite this article: M. Rocher et al., C. R. Geoscience 335 (2003).     

HYDROGEOLOGY

正20141756 Chen Ruige(Mathematical College,China University of Geosciences,Beijing100083,China);Zhou Xun Numerical Simulation of Groundwater Level Fluctuation in a Coastal Confined Aquifer with Sloping Initial Groundwater Level Induced by the Tide(Geological Bulletin of China,ISSN1671-2552,CN11-4648/P,32(7),2013,p.1099-1104,6 illus.,16 refs.) Key words:confined water,groundwater level     

METAMORPHIC PETROLOGY

正20141408 Cai Jia(Institute of Geology,Chinese Academy of Geological Sciences,Beijing100037,China);Liu Fulai Petrogenesis and Metamorphic P-T Conditions of Garnet-Spinel-Biotitebearing Paragneiss in Danangou Area,Daqingshan-Wulashan Metamorphic Complex Belt(Acta Petrologica Sinica,ISSN1000-0569,CN11-1922/P,29(7),     

SERIALS

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GEOPHYSICAL EXPLORATION

正20142386An Guoying(China Aero Geophysical Survey and Remote Sensing Center for Land and Resources,Beijing 100083,China)Application of Satellite Remote Sensing in Regional Hydrogeological Investigation:Taking Cenozoic Strata in Wenquan Sheet(1∶250 000)of Karakoram Range as an Example(Geosci-     

QUATERNARY GEOLOGY & GEOMORPHOLOGY

正20141016An Chengbang(Key Laboratory of Western China’s Environmental Systems,Ministry of Education,Lanzhou University,Lanzhou 730000,China);Zhao Yongtao Lake Records during the Last Glacial Maximum from Xinjiang,NW China and Their Climatic Impli-     

PETROLEUM GEOLOGY

正20141538 Cao Qing(School of Earth Sciences and Engineering,Xi’an Petroleum University,Xi’an 710065,China);Zhao Jingzhou Characteristics and Significance of Fluid Inclusions from Majiagou Formation,Yichuan Huangling Area,Ordos Basin(Advances in Earth Science,ISSN1001-8166,CN62-1091/P,28(7),2013,p.819-828,7 illus.,3 tables,43 refs.)     

GEOCHEMISTRY

正20142002 Wei Hualing(Institute of Geophysical and Geochemical Exploration,Chinese Academy of Geological Sciences,Langfang065000,China);Zhou Guohua Element Content and Mineral Compositions in Different Sizes of Soil in Tongling Area,Anhui Province(Geological Bulletin of China,ISSN1671-2552,CN11-4648/P,32(11),2013,p.1861