加强反硝化条件下地下水中常见有机污染物苯和甲苯微生物降解研究

利用实验室含水层物质微环境实验,对地下水中常见有机污染物苯和甲苯在厌氧反硝化条件下的微生物降解进行了研究。通过１０种方案实验结果的分析对比,所得重要结论如下：在加强了的反硝化条件下,微生物利用ＮＯ－３作为电子受体降解苯和甲苯;降解苯和甲苯的反硝化细菌来自于含水层物质;微生物所需的宏量营养由苯、甲苯和硝酸盐提供,痕量元素来自于含水层物质;环境的酸碱条件对微生物降解具有重要影响,ｐＨ值过高或过低均抑制微生物降解作用的产生。     

The geochemical effects of benzene,toluene, and xylene (BTX) biodegradation

The geochemical effects of microbially mediated degradation of aromatic hydrocarbons were observed as changes in solution composition of an artificial groundwater in packed-sand laboratory columns. Benzene, toluene, and xylene, both individually and in a combined fashion, were used as substrates in biodegradation experiments conducted under oxygenated and anoxic conditions in columns filled with quartz, calcite, or Fe³⁺-coated quartz sand. Typically, column effluent had increased concentrations of dissolved inorganic C, decreased pH, and decreased concentrations of NO₃ and dissolved O₂ relative to column influent. Efficiency of CO₂ generation was similar for the three different substrates, ranging from 22.5 to 26.6% organic C converted to CO₂. When all three substrates were combined, the percentage of CO₂ produced fell within the range observed in the single substrate experiments. Nitrate disappearance was more varied as a function of substrate identity, with greatest amounts lost when toluene was the substrate. Calcite dissolved as a result of CO₂ generated during the biodegradation reactions, and empirically calculated dissolution rates varied between 1.9 and 4.0 x 10⁻⁹ mmol cm⁻² s⁻¹. The calcite dissolution rate was slower than the biodegradation rate, as evidenced by excess generation of CO₂ relative to Ca²⁺ production. The decrease in pH was less in experiments with calcite present than in those with quartz sand present due to buffering by calcite dissolution. Dissolution of Fe oxyhydroxides was not observed under any experimental conditions.     

利用尾矿砂制备镁铁氢氧化物实验研究

以金川铜镍矿尾矿酸浸液为原料,根据矿物沉淀pH值区间的不同,分步分离Fe、Mg的沉淀物以及有价金属Al、Co、Ni、Cu的混合沉淀物,进而制备具有高附加值的Fe(OH)3和Mg(OH)2,同时富集Co、Ni、Cu等有价金属。结果表明,当溶液pH值为3.8时可沉淀分离出主要成分为施威特曼石(schwertmannite)的氢氧化铁前驱体,pH值达到9.8时沉淀富集出Al、Co、Ni、Cu的混合氢氧化物,随即得到只含有Mg离子的溶液。在60℃条件下,将施威特曼石在pH值为12的NaOH溶液中老化36h,可以得到Fe(OH)3。同时,以NaOH调节只含有Mg离子的溶液至pH值为12.4时可获得Mg(OH)2。本研究为金属矿山尾矿的资源化综合利用提供了新的思路与方法。     

Solubility of Fe2(OH)3Cl (pure-iron end-member of hibbingite) in NaCl and Na2SO4 brines

Pure-iron end-member hibbingite, Fe₂(OH)₃Cl(s), may be important to geological repositories in salt formations, as it may be a dominant corrosion product of steel waste canisters in an anoxic environment in Na–Cl- and Na–Mg–Cl-dominated brines. In this study, the solubility of Fe₂(OH)₃Cl(s), the pure-iron end-member of hibbingite (Fe^II, Mg)₂(OH)₃Cl(s), and Fe(OH)₂(s) in 0.04 m to 6 m NaCl brines has been determined. For the reactionFe₂(OH)₃Cl(s) + 3H⁺ ? 3 H₂O + 2 Fe²⁺ + Cl^?,the solubility constant of Fe₂(OH)₃Cl(s) at infinite dilution and 25 °C has been found to be log₁₀ K = 17.12 ± 0.15 (95% confidence interval using F statistics for 36 data points and 3 parameters). For the reactionFe(OH)₂(s) + 2H⁺ ? 2 H₂O + Fe²⁺,the solubility constant of Fe(OH)₂ at infinite dilution and 25 °C has been found to be log₁₀ K = 12.95 ± 0.13 (95 % confidence interval using F statistics for 36 data points and 3 parameters). For the combined set of solubility data for Fe₂(OH)₃Cl(s) and Fe(OH)₂(s), the Na⁺–Fe²⁺ pair Pitzer interaction parameter θ_{Na⁺/Fe²⁺} has been found to be 0.08 ± 0.03 (95% confidence interval using F statistics for 36 data points and 3 parameters). In nearly saturated NaCl brine we observed evidence for the conversion of Fe(OH)₂(s) to Fe₂(OH)₃Cl(s). Additionally, when Fe₂(OH)₃Cl(s) was added to sodium sulfate brines, the formation of green rust(II) sulfate was observed, along with the generation of hydrogen gas. The results presented here provide insight into understanding and modeling the geochemistry and performance assessment of nuclear waste repositories in salt formations.     

Accurate determination of Fe(II) concentrations in the presence of a very high soluble Fe(III) background

Analytical methods used for determining dissolved Fe(II) often yield inaccurate results in the presence of high Fe(III) concentrations. Accurate analysis of Fe(II) in solution when it is less than 1% of the total dissolved Fe concentration (Fe_T) is sometimes required in both geochemical and environmental studies. For example, such analysis is imperative for obtaining the ratio Fe(II)/Fe(III) in rocks, soils and sediments, for determining the kinetic constants of Fe(II) oxidation in chemical or biochemical systems operating at low pH, and is also important in environmental engineering projects, e.g. for proper control of the regeneration step (oxidation of Fe(II) into Fe(III)) applied in ferric-based gas desulphurization processes. In this work a method capable of yielding accurate Fe(II) concentrations at Fe(II) to Fe_T ratios as low as 0.05% is presented. The method is based on a pretreatment procedure designed to separate Fe(II) species from Fe(III) species in solution without changing the original Fe(II) concentration. Once separated, a modified phenanthroline method is used to determine the Fe(II) concentration, in the virtual absence of Fe(III) species. The pretreatment procedure consists of pH elevation to pH 4.2–4.65 using NaHCO₃ under N₂(g) environment, followed by filtration of the solid ferric oxides formed, and subsequent acidification of the Fe(II)-containing filtrate. Accuracy of Fe(II) analyses obtained for samples (Fe(II)/Fe_T ratios between 2% and 0.05%) to which the described pretreatment was applied was >95%. Elevating pH to above 4.65 during pretreatment was shown to result in a higher error in Fe(II) determination, likely resulting from adsorption of Fe(II) species and their removal from solution with the ferric oxide precipitate.     

苯和甲苯在土壤中的吸附行为研究

选取某采油厂不同有机碳含量的表层土壤作为吸附剂,采用批实验方法对原油中代表性组分苯和甲苯的单组分吸附和双组分竞争吸附行为进行了研究。研究表明,单组分溶液中,苯和甲苯在土壤中的吸附符合线性规律,吸附能力与土壤有机碳含量成正比;双组分溶液中,苯和甲苯共存时存在竞争吸附,土壤对它们的吸附小于单组分时的情况。竞争吸附的结果说明,除分配吸附以外,介质表面点位对苯和甲苯的吸附也起着重要的作用。     

The crystal structure of sonoraite,Fe3+Te4+O3(OH)·H2O

Summary Sonoraite, FeTeO₃(OH)·H₂O, is monoclinic,P 2₁/c, witha=10.984(2),b=10.268(2),c=7.917(2) Å, =108.49(2)°. For 8 formula units per cell the calculated density is 4.179(2) g/cm³; the observed value is 3.95(1) g/cm³. The Supper-Pace automated diffractometer was used to collect 1884 independent reflections which were corrected for absorption. The structure was determined by an automated symbolic addition procedure. It was refined to a residualR of 6.2% using anisotropic temperature factors for the cations and isotropic temperature factors for the oxygen atoms. Chains of octahedra about Fe extend along [101]; edge-sharing pairs of these octahedra are joined by corner sharing. The Fe–Fe distances across the shared edges are 3.05 and 3.20 Å, short enough to suggest magnetic interactions. All but one H₂O are involved in the chains. The Te⁴⁺ ions have a pseudotetrahedral coordination, with three oxygen ions forming one face of the tetrahedron and the lone electron pair of Te occupying the fourth corner. The O–Te–O average bond angle is 95°. The Fe chains are tied together by Te–O bonds in all three dimensions.

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Die Kristallstruktur von Sonorait, Fe³⁺Te⁴⁺O₃(OH).H₂O

Zusammenfassung Sonorait, FeTeO₃(OH)·H₂O, ist monoklin, P 2₁/c, mit den folgenden Zelldimensionen:a=10,984(2),b=10,268(2),c=7,917(2) Å, =108,49(2)°. Mit 8 Formel-Einheiten errechnet man eine Dichte von 4,179(2) g/cm³; die gemessene Dichte beträgt 3,95(1) g/cm³. Das Supper-Pace automatische Diffraktometer wurde zur Sammlung von 1884 unabhängigen Reflexen benutzt, welche für Absorption korrigiert wurden. Die Struktur wurde mit Hilfe eines vollständig automatischen Programms für symbolische Addition bestimmt. Mit anisotropen Temperaturfaktoren für die Kationen und mit isotropen Temperaturfaktoren für die Sauerstoff-Atome wurde ein Residuum von 6,2% erreicht. Ketten von Eisen-Oktaedern erstrecken sich entlang [101]; Oktaeder-Paare mit gemeinsamen Kanten sind über Eckenverknüpfung verbunden. Die Fe–Fe-Abstände über die gemeinsamen Kanten betragen 3,05 und 3,20 Å, kurz genug, um zu magnetischer Wechselwirkung führen zu können. Nur ein H₂O-Molekül ist nicht Teil einer Kette. Die Te⁴⁺-Ionen befinden sich in pseudotetraedrischer Koordination; drei Sauerstoff-Ionen bilden eine Fläche des Tetraeders, die vierte Ecke wird durch das einsame Elektronenpaar von Te besetzt. Der Mittelwert des O–Te–O-Bindungswinkels beträgt 95° Die Fe-Ketten werden durch Te–O-Bindungen dreidimensional verbunden.

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Fibroferrite: A mineral with a {Fe(OH) (H2O)2SO4} spiral chain and its relationship to Fe(OH)SO4, butlerite and parabutlerite

Summary The mineral fibroferrite has the chemical formula Fe(OH)SO₄·xH₂O; the value forx has not been definitely settled, but as a rule it is found to be near five. Several symmetries are given in the literature.A sample from Saint Felix de Paillères, France, proved to be rhombohedral with space group R3; lattice constants for the hexagonal cell area=24.176,c=7.656 Å. As calculated from the experimental density (=1.95 g·cm^–3)Z=18 for this cell. Intensities were collected on an automated X-ray diffractometer from a thin fiber extended along [00.1]. The structure was determined by Patterson and Fourier methods. Least squares refinement with 818 observed reflections resulted inR=0.076.The structure contains hydroxo-bridged {Fe(OH)(H₂O)₂SO₄} spiral chains built of [Fe(OH)₂(H₂O)₂O₂] octahedra and SO₄ tetrahedra. Hydrogen bonds provide connections between these chains. The spiral chains are a stereoisomer variant of the hydroxo-bridged linear chains of Fe(OH)SO₄, butlerite and parabutlerite. A comparison of these compounds is givenm to understand the relationship between the structure and their water content.

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Fibroferrit: Ein Mineral mit einer {Fe(OH)(H₂O)₂SO₄} Spiralkette und seine Beziehung zu Fe(OH)SO₄, Butlerit und Parabutlerit

Zusammenfassung Das Mineral Fibroferrit hat die chemische Formel Fe(OH)SO₄·xH₂O; der Wert furx scheint nicht endgültig geklärt zu sein, liegt aber meist nahe 5. Verschiedene Symmetrien werden in der Literatur angegeben.Eine Probe von Saint Felix de Paillères, Frankreich, erwies sich als rhomboedrisch mit der Raumgruppe R3; die Gitterkonstanten der hexagonalen Zelle sinda=24,176,c=7,656 Å. Die experimentelle Bestimmung der Dichte (=1,95 g·cm^–3) führt für diese Zelle zuZ=18. Von einer nach [00.1] gestreckten dünnen Faser wurden die Intensitäten auf einem automatischen Röntgendiffraktometer gesammelt. Die Struktur wurde mit Patterson-und Fouriersynthesen gelöst. Eine Verfeinerung nach der Methode der kleinsten Quadrate führte für 818 beobachtete Reflexe aufR=0,076.Die Struktur enthält durch Hydroxil-Gruppen verknüpfte {Fe(OH)(H₂O)₂SO₄}-Spiralketten, die aus [Fe(OH)₂(H₂O)₂O₂]-Oktaedern und SO₄-Tetraedern aufgebaut sind. Die Spiralketten von Fibroferrit sind eine stereoisomere Variante der annähernd linearen Fe–O–S-Ketten von Fe(OH)SO₄, Butlerit und Parabutlerit. Diese Verbindungen werden mit Fibroferrit verglichen, um Beziehungen zwischen Struktur und Wassergehalt zu verstehen.

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Paper presented at the Fifth European Crystallography Meeting, Copenhagen, Denmark 1979.     

Nikmelnikovite,Ca 12 Fe 2+ Fe $$_{3}^{{3 + }}$$ Al 3 (SiO 4 ) 6 (OH) 20 : A New Mineral from the Kovdor Massif (Kola Peninsula,Russia)

Doklady Earth Sciences - Nikmelnikovite, Ca12Fe2+Fe$$_{3}^{{3 + }}$$Al3(SiO4)6(OH)20, a new mineral from the Kovdor massif (Kola Peninsula, Russia), is described. It is the first trigonal...     

碱熔共沉淀-电感耦合等离子体质谱法测定橄榄岩中的稀土元素

橄榄岩的稀土元素特征对研究岩石成因、岩浆作用过程具有重要的意义。橄榄岩中的稀土元素含量低(∑REEs=0.1~1μg/g),且存在镁、铁等基体元素的干扰,难以准确测定。前人通常利用高压密闭酸溶-离子交换法处理样品,将稀土元素与镁、铁等基体元素分离,达到了预富集的效果,但耗时长(消解时间接近7天)、操作步骤繁多,不利于大批量样品的分析。本文建立了过氧化钠碱熔、Fe(OH)_3和Mg(OH)_2共沉淀的样品前处理方法,通过离心使溶液与沉淀分离,从而实现了稀土元素与镁、铁等基体元素的快速分离,再采用电感耦合等离子体质谱法测定稀土元素含量。方法检出限为0.17~2.18 ng/g,加标回收率为95%~101%,国家标准物质(GBW07101和GBW07102)的测定值与标准值的相对误差小于20%,相对标准偏差(RSD,n=11)小于10%。该方法既减少了分步沉淀过程中带来的损失,也缩短了分析周期(消解时间仅需一天),操作简便,分析效率高。