微生物多糖／葡聚糖体系氢氧化铁生物矿化的实验研究

本文通过观察在尿素和Stoke培养基中生长的球衣菌细胞壁内及其周围氢氧化铁凝胶的矿化过程,研究球衣菌分泌的多糖和蛋白质对氢氧化铁凝胶矿化结晶行为的调控作用。采用TEM、UV和FTIR对两种矿化体系微生物矿化产物进行了观察和分析,同时对比以纯葡聚糖为有机基质作用下氢氧化铁凝胶的矿化过程,结果表明微生物多糖和葡聚糖均能控制水溶液中铁离子及氢氧化铁凝胶的成核机制、结晶相和晶体的生长速度,主要矿化产物为纳米级四方纤铁矿(β-FeOOH)。     

企鹅贝珍珠层生物表界面ACC析出与相变及多级自组装生长

<正>珠母贝珍珠层生物矿化作用区别于一般无机矿物矿化的显著特征是,通过生物表界面处生物大分子(蛋白质、核酸、多糖等)基因的表达与诱导,从分子水平调控生物矿物前驱体(ACC)纳米球粒的析出与相变,从而使生物矿物具有特殊的生物矿化生长结构单元和高度有序的多级微观自组装生长结构和自组装方式。迄今,就发生在企鹅贝(Pteria penguin)珍珠层生物表界面处生物大分子的调控和生物矿物前驱体的相变规律,生物矿物多级微观自组装生长行为等生物矿化问题有待深化。     

从生物矿化作用衍生出的有机矿化作用：地球生物学框架下重要的研究主题

早期"生物矿化作用"的概念,被定义为生物形成矿物的作用,并进一步分为生物控制和生物诱导两大类型。这个宽泛的概念,被修订为生物以生命活型(living form)影响矿物物质的沉淀作用;相应地,"生物矿物"是在严格的生物控制下、从局部环境中选择性地吸收元素并融合成具有生物功能构造的矿物。"有机矿化作用",则被定义为"与那些无生命活力的有机物质相关联的矿物形成作用"。与生物矿化作用相对应,有机矿化作用的产物被定义为"有机矿物",用来指那些通过有机聚合物、生物的和(或)非生物的有机化合物所导致的矿物沉淀作用,但是,有机矿物并非活着的细胞所直接形成。有机矿物与生物矿物的重要区别是,有机矿物没有被融合成受到生物严格控制的功能性构造。生物学家和化学家将生物矿化作用作为关注"生命体系中复杂的化学过程"的研究主题,超越了地质学范畴并使生物矿化作用的研究成为多学科关注的迷人领域,也大大促进了有机矿化作用的研究;考虑到有机矿物是沉积岩的重要组成,而且与生物的出现同步,还是潜在性的地外生命的遗迹,因此,从生物矿化作用衍生出的有机矿化作用的研究,自然就成为与生物矿化作用存在紧密关联的、地球生物学框架下又一个重要的研究主题     

水库渗漏水中氢氧化铁的矿化特征

对富水水库大坝渗漏水和析出物进行了分析和研究。析出物的主要成分为Fe2O3，并含少量Al2O3和SiO2，铁质析出物的XRD、IR、SEM和TEM分析表明，氢氧化铁的结晶程度较低，主要结晶相为针铁矿，其次为少量伊利石、蒙脱石和石英。电子显微分析观察到在非晶质氢氧化铁凝胶团和亚微米级微粒聚集体中存在特殊的显微管状和螺旋状针铁矿，显示出明显的生物矿化特征。     

铁细菌胞外多聚物对铁矿物的调控形成及其环境意义

环境介质溶液中铁的水解作用和稳定化作用主要受铁细菌及其代谢有机物质的影响。铁细菌普遍存在于自然环境中,可利用低价铁源为自身生长所需能量。铁细菌胞外有机物的主要组分如多糖和蛋白质等可与铁结合,并通过氧化或沉淀作用使铁稳定、沉积而形成铁矿物;此外铁细菌胞外多聚物可催化铁的氧化或促进铁的聚集。这些生物成因铁矿物因具有良好的表面吸附与氧化还原等化学活性,及有效固定环境中的重金属、放射性核素和催化降解有机污染物的良好环境属性,在环境生物矿物材料和环境治理研究领域被日益重视。故本文基于铁细菌及其胞外多聚物对铁矿物矿化形成的重要调控作用,介绍了环境中存在的铁细菌及其生物矿化特征,重点阐述了铁细菌胞外多聚物(组分、结构及特性)及其在铁矿物矿化过程中的作用,同时对铁细菌胞外多聚物及生物成因铁矿物的环境意义进行了概述。     

西成矿田泥盆系铅锌矿床中的有机成矿作用

西成矿田是秦岭多金属成矿带最重要的铅锌矿田之一.从有机地球化学特征、有机质和有机分子与金属元素的关系、矿石、围岩及与矿石共生的炭沥青的元素分析及有机流体萃取金属元素的模拟实验方面出发, 探讨了有机质在西成铅锌矿田形成过程中的作用.结果表明: (1) 与矿化有关的岩石(硅质岩和灰岩), 主峰碳数均为nC₁₈, 中间支链烷烃、伽玛蜡烷、胡萝卜烷系列含量比非矿化岩石高; (2) 与矿化有关岩石(硅质岩和大理岩) 的生物母源以菌藻类低等生物为主, 并有陆源母质混入, 矿床形成于还原环境, 矿床中存在来源相同或相似的异源有机质; (3) Pb、Zn元素与芳烃、氯芳沥青“A”、非烃+沥青呈显著的负相关; 与非烃、有机硫、有机硫/(有机碳× 1.22) 比值呈正相关关系; Pb、Zn元素与正构烷烃、甾萜烷、胡萝卜烷等有机分子丰度具正相关关系, 而与w(∑C₂₂-)/w(∑C₂₂+)、w(三环萜烷)/w(四环萜烷)、w(C₂₀+C₂₁)/w(C₂₃+C₂₄)及w(萜烷)/w(甾烷) 等有机分子比值具负相关关系; (4) 炭沥青与围岩、矿石中子活化分析结果表明, 在后期改造成矿作用中, 炭沥青与矿石有紧密联系, 有机质和成矿元素一起在改造成矿期抵达成矿部位并参与了成矿; (5) 模拟实验表明, 在热水流体中, 有机水的加入增大了对Pb、Zn元素的溶解能力, 增加了岩样释放成矿元素的能力, 有机质在热水流体运移过程中确实对成矿元素发生了作用.在此基础上, 提出生物有机质在西成地区铅锌矿床的形成过程中发挥了重要作用.      

几种氢氧化铁对亚砷酸根的吸附及预处理方法的影响

笔者研究了3种铁氧化物(氢氧化物)对亚砷酸根阴离子的吸附作用。三种吸附剂分别是Fe(OH)3凝胶,其真空微波干燥和80℃常规干燥产物。实验结果表明,将氢氧化铁凝胶与亚砷酸钠溶液混合后,六分钟内溶液的pH值从9.71升高至10.36,说明亚砷酸根取代了氢氧化铁中的氢氧根。反应40分钟后,pH值下降,原因很可能是被吸附的亚砷酸根表面络合体从单齿络合转变成为单核—双齿络合体并释放质子。pH值降低并不意味着吸附作用的结束,而是表明了反应类型的转变。温度和溶解空气对这两种反应的影响很小。将吸附剂超声波处理后,亚砷酸根的吸附总量增加了,不过…     

硅藻细胞壁硅化过程中有机质-矿物的相互作用

生物成因二氧化硅,更为确切地说是无定形水合二氧化硅,是第二大类生物成因矿物,在丰度和分布上仅次于生物 成因碳酸盐矿物。硅藻是海洋生物成因二氧化硅的主要贡献者,其复杂和多级结构的硅质细胞壁已经引起多学科研究的兴趣。 生物化学研究表明,硅藻生物成因的二氧化硅是一种复合材料,除了无机的非晶质二氧化硅以外,还含有生物矿化过程中 普遍存在的有机组分,例如多糖、蛋白质和长链聚胺等。对这些组分的功能研究显示,它们在诱导二氧化硅沉淀以及形成 物种特异性纳米图案方面起着至关重要的作用。本文简要介绍硅藻和硅藻细胞壁组成和结构,同时着重介绍了硅化过程中 的有机和生物分子的生物功能、提取于生物二氧化硅中矿化相关的有机分子参与的体外（in vitro）实验以及模型有机添加 剂存在下的仿生矿化等研究的最新进展。对硅藻调控的生物成因二氧化硅形成机制的深入了解,将可能从机理上把全球硅 循环和碳循环联系起来;而对硅藻体内成分的鉴定和分类将有助于我们深入理解石油的物质来源和硅藻的进化历程。     

几种不同类型的FeOOH吸附水溶液中铬离子研究

采用两种显微结构不同的螺旋状和管状构造的天然铁细菌矿化针铁矿和化学合成的α—FeOOH及两种有机高分子模板矿化结晶的β-FeOOH作为吸附材料，分别在pH=5和6时对含Cr^3 和Cr(Ⅵ)废水进行了吸附实验研究，结果表明，天然生物矿化针铁矿对金属阳离子和阴离子均有明显的吸附作用，其显微结构、大小和形态影响其吸附能力；纯化学合成的针铁矿对铬离子的吸附能力较低；通过有机模板合成的纳米微晶β-FeOOH对Cr^3 和Cr(Ⅵ)均有极高的去除率，这与其表面存在与有机分子络合作用、增大了其表面对金属离子和铬酸根的化学亲合力有关。     

CaCO3生物矿化的研究进展——有机质的控制作用

生物CaCO₃是自然界分布最广泛的一类生物矿物,其组成除了无机相的CaCO₃外,还含有少量的有机质,包括水可溶(SM)和水不可溶有机质(IM),SM富含阴离子基团,是控制CaCO₃结晶的重要因素之一。通过有机—无机界面分子识别,有机质选择性地与CaCO₃晶体特定方向的面网相互作用,从而对CaCO₃的生长、形貌、多型及结晶学定向等产生明显的控制作用。有机—无机界面的分子识别机制包括静电、晶格几何匹配和立体化学互补等。仿生矿化的研究为进一步深入了解生物矿化的机理及制造高级复合材料提供了新的方法。     

Study on the modulating effect of polysaccharide upon the mineralization of iron hydroxide

To investigate the modulating effect of polysaccharide upon the mineralization of iron hydroxide, a series of simulative biomineralization experiments using dextran and chitosan as organic substrates were conducted in this paper. The results showed that iron hydroxide gel nucleated and grew in polysaccharide molecules, with the self-assemble effect of dextran or chitosan, the nanometer-sized akaganeite was formed. The shape, size and crystal structural type of iron oxyhydroxide formed from iron hydroxide gel depend on the type of polysaccharide and its concentrations.     

硅胶／壳聚糖吸附材料的制备及表征

利用γ-氨基丙基-三乙氧基硅烷偶联剂与活化硅胶表面的羟基反应,制备了硅烷化硅胶,所得产物与壳聚糖反应合成了硅胶／壳聚糖复合吸附材料。通过红外光谱分析（IR）,扫描电镜（SEM）及能谱分析对复合材料进行表征,并测试了硅胶／壳聚糖复合材料对Zn^2＋、Cd^2＋的吸附能力。结果表明：复合吸附材料对Zn^2＋、Cd^2＋具有很好的吸附能力,最大吸附率为96．01％及90．65％。     

葡聚糖对酸性矿山废水中次生铁矿物形成的影响

采用H2O2氧化Fe2＋并供应4种不同浓度葡聚糖的方法,探讨在H2O2氧化体系中葡聚糖对次生铁矿物形成的影响。结果表明：葡聚糖对次生矿物的形成具有明显的抑制作用;随着葡聚糖浓度的提高,次生矿物内的Fe含量降低,而S含量没有显著变化,且所有处理的K含量均较低;没有葡聚糖处理的次生矿物XRD特征峰与黄钾铁矾吻合,而添加葡聚糖后形成的次生矿物的特征峰与施氏矿物吻合,但是所有处理的次生矿物的结晶度都不高;随着葡聚糖浓度的提高,次生矿物的颗粒尺寸降低,比表面积增加。因此,葡聚糖能够抑制次生矿物的合成,并且阻止次生矿物由施氏矿物向黄钾铁矾的转变。     

Comparative data on the volatile component composition of magma

Ferrihydrite (2.5 Fe₂O₂-4.5 H₂O) is an unstable colloidal mineral. It dissolves in highly alkaline solutions and is precipitated from them in the form of goethite. Jarosite is stable at very low pH but is decomposed at higher values of pH with separation of iron oxides. Experiments show that in rapid decomposition of jarosite a protohematite substance, ferrihydrite, is formed. This transformation occurs at moderate pH values when solutions percolate through the aggregates of jarosite. Ferrihydrite, an unstable colloidal hydrated oxide of ferric iron, changes spontaneously to stable hematite with time. Very slow decomposition of jarosite results in its replacement by iron hydroxide, goethite. Under laboratory conditions in alkaline solutions lepidocrocite may be obtained from jarosite. The synthesis of this iron hydroxide passes through a stage of intermediate products: ferrihydrite and hydrated ferric oxide - ferriprotolepidocrocite, formed by solution of ferrihydrite in strongly alkaline solutions. The transformation of ferriprotolepidocrocite into lepidocrocite may be regarded as a topotactic reaction. —Authors.     

Origin of red beds in the Ringerike Group (Silurian) of Norway

The Ringerike Group is a meandering fluviatile succession which is about 60% red. Most of the red zones are formed of mudrocks and siltstones and correspond to the fine members of fining-upwards cyclothems. The majority of coarse members are drab coloured.Textural studies of thin and polished sections show that the red colour is caused by finely crystalline hematite as matrix and grain-coatings. This hematite apparently crystallized post-depositionally. Hematite also occurs in other textural sites: within altered phyllosilicates, as detrital grains and as totally pseudomorphed phyllosilicates. This, and the lack of consistency between colour and clay mineralogy, suggests that the red beds have had a long and complex diagenetic history.Iron analyses indicate that the red beds are enriched in Fe³⁺ and total iron (FeO) by about 1%. This is thought to have been derived from the pre-depositional weathering of iron minerals and introduced into the sediments as amorphous iron hydroxide or iron-bearing clays. Crystallization of iron hydroxide under oxidizing conditions and the post-depositional alteration of iron-silicates and oxides is thought to be responsible for the formation of the red beds.     

Geological and geochemical features of the auriferous Butarny deposit

The Butarny deposit is characterized by the development of mineralization of gold-quartz and gold-rare metal mineral associations related to Late Cretaceous granitoid magmatism and metasomatism imposed during the Late Jurassic tectonomagmatic epoch. Ores on the Butarnoe site were formed during the vein quartz-sulphide stage and partially oxidized in a zone of hypergenesis. The gold found there is fine-grained and is also related to arsenopyrite and scorodite and, to a lower degree, to quartz and iron hydroxide     

Characterisation of sphalerite and pyrite flotation samples by XPS and ToF-SIMS

The surface analytical techniques of X-ray Photoelectron Spectroscopy (XPS) and Time of Flight Secondary Ion Mass Spectroscopy (ToF-SIMS) have provided information on the type and concentration of species on the surface of sphalerite and pyrite particles in flotation concentrate and tail samples, but also on their distribution on each particle and across particles of different sizes. From this surface analytical study, a more accurate interpretation of the flotation results of sphalerite and pyrite minerals in a mixed mineral system could be made as a function of the concentrations of copper sulphate activator and xanthate collector, and particle size. In particular, it was found that sphalerite particles reporting to the concentrate are larger in size and contain less iron hydroxide on their surface than particles reporting to the tail. As for the pyrite particles, their lower recovery than the sphalerite particles is the result of a larger proportion of iron hydroxide on their surface inhibiting copper and collector adsorption.     

尾矿酸浸液制备氢氧化铁过程中施威特曼石的形成与转变

尾矿酸浸液在制备氢氧化铁的过程中,由于逐渐滴加碱液正好形成了pH值为2.8～3.8的高SO2-4、高Fe环境,因而生成了施威特曼石.施威特曼石是一种亚稳定矿物,随着时间的延长和体系状态改变,它可以转变为更稳定的针铁矿(氢氧化铁).考查了pH值、温度及时间对施威特曼石相转变的影响.结果表明,在60℃条件下,在pH值为12的碱溶液中转化36 h,施威特曼石可完全转变为Fe(OH)3.     

Microbial and hydrothermal aspects of ferric oxyhydroxides and ferrosic hydroxides: the example of Franklin Seamount, Western Woodlark Basin, Papua New Guinea

Deposits of Fe-Si-Mn oxyhydroxides are commonly found on the seafloor on seamounts and mid-ocean spreading centers. At Franklin Seamount located near the western extremity of Woodlark Basin, Papua New Guinea, Fe-Si-Mn oxyhydroxides are being precipitated as chimneys and mounds upon a substrate of mafic lava. Previous studies have shown that the vent fluids have a low temperature (20–30°C) and are characterized by a total dissolved iron concentration of 0.038 mM kg^-1, neutral pH (6.26) and no measurable H₂S. The chimneys have a yellowish appearance with mottled red–orange patches when observed in situ from a submersible, but collected samples become redder within a few hours of being removed from the sea. The amorphous iron oxyhydroxides, obtained from active and inactive vents, commonly possess filamentous textures similar in appearance to sheaths and stalks excreted by the iron-oxidizing bacteria Leptothrix and Gallionella; however, formless agglomerates are also common. Textural relationships between apparent bacterial and non-bacterial iron suggest that the filaments are coeval with and/or growing outwards from the agglomerates. The amorphous iron oxyhydroxides are suggested to precipitate hydrothermally as ferrosic hydroxide, a mixed-valence (Fe²⁺-Fe³⁺) green–yellow iron hydroxide compound. Consideration of the thermodynamics and kinetics of iron in the vent fluid, suggest that the precipitation is largely pH controlled and that large amounts of amorphous iron oxyhydroxides are capable of being precipitated by a combination of abiotic hydrothermal processes. Some biologically induced precipitation of primary ferric oxyhydroxides (two-XRD-line ferrihydrite) may have occurred directly from the fluid, but most of the filamentous iron micro-textures in the samples appear to have a diagenetic origin. They may have formed as a result of the interaction between the iron-oxidizing bacteria and the initially precipitated ferrosic hydroxide that provided a source of ferrous iron needed for their growth. The processes described at Franklin Seamount provide insight into the formation of other seafloor oxyhydroxide deposits and ancient oxide-facies iron formation.