硅酸盐中铁、锰、钛、钙、钾、磷、硅、铝、镁、钠、锶、铷、钡的X-射线荧光光谱定量测定

本文介绍样品经四硼酸锂熔融制成玻璃小饼。采用Lachance模式和理论a系数来校正元素间的效应,由3080E型X-射线荧光谱仪和DF-350B数据处理系统完成硅酸盐中十三个项目的测定。     

砂金中金、银、硅、铁、铜、铋、砷的测定

金含量较高，采用高铈盐容量法。铁、铜、银采有原子吸收，硅采用等离子光谱，铋和砷采用氩化物原子荧光法测定。     

形变、畸变、应变、变形

形变、畸变、应变和变形等词汇是连续介质力学中描述物体变形的、最基本的术语,它们包含着不同的概念,我国力学家们对这些力学中最基本的概念都有着明确的含义。物体在外力的作用下要发生两种运动,一种运动是物体在空间位置的变化,我们叫刚性运动,另一种运动是物体自身形状和大小的变化,称力变形。     

吨、公吨、短吨、长吨

吨(ton),重量单位,与公吨(tonne)同,其通用符号为t。1公吨=1t=1000kg。欧洲大陆及不用英语的各国常用。短吨(short ton),美国常用,其符号为shton,1sh ton=2000磅(pound)=907.18486kg。磅为英制重量单位,其符号为1b,1b=0.45359237kg。长吨(1ong ton),英国常用,1长吨=2240 1b=1016.047kg。     

ICP-OES法测定煤样中磷、铜、铅、锌、镉、铬、镍、钴等元素

采用硝酸—氢氟酸—高氟酸混合体系,微波消解样品,用ICP-OES法测定煤样中微量元素P、Cu、Pb、Zn、Cr、Dd、Ni、Co,快速简便、准确度高。     

中国气象局兰州干旱气象研究所开放、流动、竞争、协作

实行开放式的办所策略，加强对外学术交流和科技合作，广泛吸纳国内外最新研究成果，瞄准世界前沿领域，不断拓宽研究领域，提升科技竞争力。干旱所设立了“干旱气象科学研究基金”，面向国内外相关科研机构开放。以甘肃省干旱气候变化与减灾重点实验室为合作平台，初步实现了产学研的结合，实现了科技资源的优化配置。积极参加各类高水平的国际国内学术会议，邀请国外专家学者来所开展学术交流和访问，与澳大利亚气象局等国外机构签署了国际合作协议。     

深孔电极发射光谱法测定地质样品中Be、B、Pb、Mo、Sn、Cu、Ag、Zn

本法是在样品中加入适量的缓冲剂,使难发挥元素Be形成易挥发的氟化物,与B、Pb、Mo、Sn、Cu、Ag、Zn等元素在同一时间内蒸发,利用深电孔极的分馏效应,有效地降低光谱背景以及被测元素的检出限。加入内标元素,提高了方法的准确度和精密度。采用深孔电极,取样量大,代表性好。一次摄谱,同时检测多个元素,大大提高了工作效率,又减少了测试费用。方法操作简便,适合于大批量样品的测试。检出限ω(B)/10-6分别达到:Be:0.50、B:0.91、Sn:0.50、Ag:0.02等,均满足《覆盖区多目标地球化学调查样品测试及质量监控暂行规定》规定。     

中、哈、俄、乌、土、阿、吉、塔8国合作编图计划继续进行

2001年10月25日至11月30日,中欧亚岩相—古地理、构造、复原及地质生态图集编辑委员会和执行负责人会议分别在阿拉木图、比什凯克和莫斯科举行.来自中国、哈萨克斯坦、俄罗斯、乌孜别克斯坦、阿塞拜疆和吉尔吉斯斯坦的24位专家到会.中国新疆地质矿产勘查开发局专家董连慧、宋志齐和侯启尧参加了阿拉木图会议,会议由哈萨克斯坦南哈地质公司自然资源研究所主持,召集人为该所地质学家O.A.费多连科. 会议最终校定了已编辑完成的《中欧亚岩相—古地理、构造、复原及地质生态图集》,对提出的问题共同作出了修改方案,该图集2000年曾在巴西召开的第…     

应用发射光谱法测定银、硼、铅、钼、锡

介绍了采用以电弧为光源的发射光谱法测定银、硼、铅、钼、锡的应用过程;认为通过对仪器的适当改造,应用现代的研究成果,可以快速提升实验室检测能力。     

攀西裂谷内陆盆地自由热对流应力分析及盆地沉降

康滇地区裂谷作用已得到证实,但形成这种地堑地垒的格局有多种解释,以传统的地质力学分析为主。笔者借以热力学的自由热对流原理来加以论述：攀西巨厚的火山岩体在下覆异常地幔热作用下,发生自由热对流,引起热量散失,使地壳沉降与隆起不均衡,生成地堑地垒的格局。自由对流单元的侧向迁移,使盆地形成非对称性。     

Microbial reduction of iron(III)-rich nontronite and uranium(VI)

To assess the dynamics of microbially mediated U-clay redox reactions, we examined the reduction of iron(III)-rich nontronite NAu-2 and uranium(VI) by Shewanella oneidensis MR-1. Bioreduction experiments were conducted with combinations and varied concentrations of MR-1, nontronite, U(VI) and the electron shuttle anthraquinone-2,6-disulfonate (AQDS). Abiotic experiments were conducted to quantify U(VI) sorption to NAu-2, the reduction of U(VI) by chemically-reduced nontronite-Fe(II), and the oxidation of uraninite, U^(IV)O_2(s), by nontronite-Fe(III). When we incubated S. oneidensis MR-1 at lower concentration (0.5 × 10⁸ cell mL⁻¹) with nontronite (5.0 g L⁻¹) and U(VI) (1.0 mM), little U(VI) reduction occurred compared to nontronite-free incubations, despite the production of abundant Fe(II). The addition of AQDS to U(VI)- and nontronite-containing incubations enhanced both U(VI) and nontronite-Fe(III) reduction. While U(VI) was completely reduced by S. oneidensis MR-1 at higher concentration (1.0 × 10⁸ cell mL⁻¹) in the presence of nontronite, increasing concentrations of nontronite led to progressively slower rates of U(VI) reduction. U(VI) enhanced nontronite-Fe(III) reduction and uraninite was oxidized by nontronite-Fe(III), demonstrating that U served as an effective electron shuttle from S. oneidensis MR-1 to nontronite-Fe(III). The electron-shuttling activity of U can explain the lack or delay of U(VI) reduction observed in the bulk solution. Little U(VI) reduction was observed in incubations that contained chemically-reduced nontronite-Fe(II), suggesting that biologic U(VI) reduction drove U valence cycling in these systems. Under the conditions used in these experiments, we demonstrate that iron-rich smectite may inhibit or delay U(VI) bioreduction.     

Geochemistry of bauxites of Belgaum (Karnataka) and Yercaud (Tamil Nadu) areas

The major chemical components of bauxite deposits of Belgaum (76° 24′E : 15° 54′N) and Yercaud (78° 14′E : 11° 48′N) areas have been determined. A chemical continuity between parent rocks (zone I) to bauxites (zone IV) via clay (zone II) and laterites (zone III) clearly indicates that bauxites have been derived byin situ weathering of the respective parent rocks.     

Arsenite adsorption on galena (PbS) and sphalerite (ZnS)

Arsenite, As(III), sorption on galena (PbS) and sphalerite (ZnS) was investigated as a function of solution composition and characterized using X-ray absorption spectroscopy (XAS). Adsorption conformed to a Langmuir isotherm except at the highest surface loadings, and it was not strongly affected by changes in ionic strength. Arsenite sorbed appreciably only at pH > ∼5 for PbS and pH ∼4.5 for ZnS, behavior distinct from its adsorption on other substrates. Arsenite adsorption on PbS and ZnS resulted in the conversion from As-O to As-S coordination. Arsenite does not adsorb through ligand-exchange of surface hydroxyl or sulfhydryl groups. Rather, it forms a polynuclear arsenic sulfide complex on ZnS and PbS consistent with the As₃S₃(SH)₃ trimer postulated by Helz et al. (1995) for sulfidic solutions. This complex was unstable in the presence of oxidizing agents and synchrotron light—it quickly converted to As(V), which was largely retained by the surface. These data illustrate the complexity of As(III) adsorption to even simple sulfide minerals.     

独居石和磷钇矿晶体结构的精确测定

本文用强功率四圆单晶衍射仪精确地修正了独居石和磷钇矿的晶体结构。独居石［Ｍｏｎａｚｉｔｅ－（Ｃｅ），ＣｅＰＯ４］属单斜晶系，ａ＝６．７８４３（１７），ｂ＝６．９８９１（１２），ｃ＝６．４５９２（１０），β＝１０３．６２６（１６）°，Ｚ＝４，空间群为Ｐ２１／ｎ。使用１１０６个［Ｆ≥３σ（Ｆ）］的独立衍射点，经多轮最小二乘法修正后，最终获得偏离因子Ｒ＝０．０６０。独居石的结构由孤立的［ＰＯ４］四面体构成，Ｃｅ位于［ＰＯ４］四面体包围之中，Ｃｅ的配位数为９，独居石的Ｃｅ—Ｏ平均键长为２．５５２，Ｐ—Ｏ平均键长为１．５２８。磷钇矿（Ｘｅｎｏｔｉｍｅ，ＹＰＯ４）属四方晶系，其晶格常数为：ａ＝６．８７９１（２４），ｃ＝６．０１４７（１９），Ｚ＝４，空间群为Ｉ４Ｉ／ａｍｄ（Ｎｏ．１４１）。使用１４２个［Ｆ≥３σ（Ｆ）］的独立衍射点，经多轮最小二乘法修正后，最终获得偏离因子Ｒ为０．０４８３。磷和氧形成四面体配位，其Ｐ—Ｏ平均键长为１．５４３；稀土钇与氧原子相连构成八次配位，其Ｙ—Ｏ平均键长为２．３３３。     

Adsorption and surface oxidation of Fe(II) on metal (hydr)oxides

The Fe(II) adsorption by non-ferric and ferric (hydr)oxides has been analyzed with surface complexation modeling. The CD model has been used to derive the interfacial distribution of charge. The fitted CD coefficients have been linked to the mechanism of adsorption. The Fe(II) adsorption is discussed for TiO₂, γ-AlOOH (boehmite), γ-FeOOH (lepidocrocite), α-FeOOH (goethite) and HFO (ferrihydrite) in relation to the surface structure and surface sites. One type of surface complex is formed at TiO₂ and γ-AlOOH, i.e. a surface-coordinated Fe²⁺ ion. At the TiO₂ (Degussa) surface, the Fe²⁺ ion is probably bound as a quattro-dentate surface complex. The CD value of Fe²⁺ adsorbed to γ-AlOOH points to the formation of a tridentate complex, which might be a double edge surface complex. The adsorption of Fe(II) to ferric (hydr)oxides differs. The charge distribution points to the transfer of electron charge from the adsorbed Fe(II) to the solid and the subsequent hydrolysis of the ligands that coordinate to the adsorbed ion, formerly present as Fe(II). Analysis shows that the hydrolysis corresponds to the hydrolysis of adsorbed Al(III) for γ-FeOOH and α-FeOOH. In both cases, an adsorbed M(III) is found in agreement with structural considerations. For lepidocrocite, the experimental data point to a process with a complete surface oxidation while for goethite and also HFO, data can be explained assuming a combination of Fe(II) adsorption with and without electron transfer. Surface oxidation (electron transfer), leading to adsorbed Fe(III)(OH)₂, is favored at high pH (pH > ∼7.5) promoting the deprotonation of two Fe_III-OH₂ ligands. For goethite, the interaction of Fe(II) with As(III) and vice versa has been modeled too. To explain Fe(II)-As(III) dual-sorbate systems, formation of a ternary type of surface complex is included, which is supposed to be a monodentate As(III) surface complex that interacts with an Fe(II) ion, resulting in a binuclear bidentate As(III) surface complex.     

Thermal and Collision History of Jilin（H5） and Qingzhen（EH3） Chondrites

This paper deals with the effects of thermal and collision events which had been experienced by the Jilin(H5) and Qingzhen(EH3) chondrites before they fell to the earth .The HRTEM and opti-cal microscopic investigations show that the Jilin chondrite has undergone more extensive thermal heating and two stages of collision,while the Qingzhen chondrite has experienced weak thermal events after the accretion of its parent body and one stage of moderate collision.The schematic dia-grams of the process of formation and evolution of these two meteorites are given in the present pa-per.     

Cathodoluminescence (CL) and electron paramagnetic resonance (EPR) studies of clay minerals

Summary ?Sheet silicates of the serpentine–kaolin-group (serpentine, kaolinite, dickite, nacrite, halloysite), the talc–pyrophyllite-group (talc, pyrophyllite), the smectite-group (montmorillonite), and illite (as a mineral of the mica-group) were investigated to obtain information concerning their cathodoluminescence behaviour. The study included analyses by cathodoluminescence (CL microscopy and spectroscopy), electron paramagnetic resonance (EPR), X-Ray diffraction (XRD), scanning electron microscopy (SEM) and trace element analysis. In general, all dioctahedral clay minerals exhibit a visible CL. Kaolinite, dickite, nacrite and pyrophyllite have a characteristic deep blue CL, whereas halloysite emission is in the greenish-blue region. On the contrary, the trioctahedral minerals (serpentine, talc) and illite do not show visible CL. The characteristic blue CL is caused by an intense emission band around 400 nm (double peak with two maxima at 375 and 410 nm). EPR measurements indicate that this blue emission can be related to radiation induced defect centres (RID), which occur as electron holes trapped on apical oxygens (Si–O centre) or located at the Al–O–Al group (Al substituting Si in the tetrahedron). Additional CL emission bands were detected at 580 nm in halloysite and kaolinite, and between 700 and 800 nm in kaolinite, dickite, nacrite and pyrophyllite. Time-resolved spectral CL measurements show typical luminescence kinetics for the different clay minerals, which enable differentiation between the various dioctahedral minerals (e.g. kaolinite and dickite), even in thin section. Received December 3, 2001; revised version accepted February 27, 2002