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1

The Clay Minerals Society  

NSDL National Science Digital Library

"The Clay Minerals Society (CMS) is an international community of scientists who promote research in and disseminate information on clay science and technology." The website provides downloads of materials dealing with various aspects of mineralogy, geochemistry, and petrology. Researchers can find out about annual meetings, awards and grants, and publications. Students and educators can find information on teaching materials, clay science workshops, and games. The website offers physical and chemical data for Source and Special Clays.

2

Elastic Properties of Clay Minerals  

NASA Astrophysics Data System (ADS)

We present ultrasonic P- and S-waves velocity measurements on pure clay samples using three different experiment setups. These experiments provided petrophysical and acoustic properties of clay minerals as a function both of mineralogy and compaction. In the first experiment, acoustic measurements were performed on cold-pressed clay aggregates at ambient and at hydrostatic pressure conditions. Porosity and grain density values of the different clay mineralogy aggregates ranged from 4 to 43% and 2.13 to 2.83 g cm-3, respectively. In the second experiment, we measured P-wave velocity and attenuation in a kaolinite-water suspension in which clay concentration was increased up to 60%. In the third experiment, P- and S- wave velocities were measured during uniaxial stress compaction of clay powders. Results from all three experiments revealed low bulk (K) and shear (? ) moduli for kaolinite, montmorillonite, and smectite; the values range between 6-12 GPa for K and 4-6 GPa for ? , respectively. Using these clay moduli values in effective medium and granular porous media models, velocity is predicted in saturated pure kaolinite samples, kaolinite suspension and shaly sandstones fairly well. Experimental results also showed that water interlayers play an important role in the compaction and strength of clay aggregates. Clay minerals carrying on water interlayers in their structure showed high compaction and strength. This study is relevant for a more reliable assessment of the seismic response in reservoirs and/or basins characterized by clay-bearing formations.

Vanorio, T.; Prasad, M.; Nur, A.

2001-12-01

3

Elastic Properties of Clay Minerals  

NASA Astrophysics Data System (ADS)

We present ultrasonic P- and S-waves velocity measurements on pure clay samples us- ing three different experiment setups. These experiments provided petrophysical and acoustic properties of clay minerals as a function both of mineralogy and compaction. In the first experiment, acoustic measurements were performed on cold-pressed clay aggregates at ambient and at hydrostatic pressure conditions. Porosity and grain den- sity values of the different clay mineralogy aggregates ranged from 4 to 43% and 2.13 to 2.83 g cm-3, respectively. In the second experiment, we measured P-wave velocity and attenuation in a kaolinite-water suspension in which clay concentration was in- creased up to 60%. In the third experiment, P- and S- wave velocities were measured during uniaxial stress compaction of clay powders. Results from all three experiments revealed low bulk (K) and shear (µ) moduli for kaolinite, montmorillonite, and smec- tite; the values range between 6-12 GPa for K and 4-6 GPa for µ, respectively. Using these clay moduli values in effective medium and granular porous media (theories) models, velocity is predicted in saturated pure kaolinite samples, kaolinite suspension and shaly sandstone fairly well. Experimental results also showed that water interlay- ers play an important role in the compaction and strength of clay aggregates. Clay minerals carrying on water interlayers in their structure showed high compaction and strength. This study is relevant for a more reliable assessment of the seismic response in reservoirs and/or basins characterized by clay-bearing formations.

Vanorio, T.; Prasad, M.; Nur, A.

4

Mineral Abundance Near Aristarchus Crater  

Microsoft Academic Search

Mineral Abundance Near Aristarchus Crater Alison Bradford and Alex Storrs Towson University We analyze Hubble Space Telescope (HST) images to determine the abundance of minerals near Aristarchus crater. Following the calibration of Robinson et al. (2007) we present ratio maps of images obtained in August of 2005 showing the abundance of TiO2 and other minerals in this interesting area in

Alison Bradford; A. Storrs

2007-01-01

5

Clays, Nanoclays, and Montmorillonite Minerals  

NASA Astrophysics Data System (ADS)

The recent introduction of nanoclays as fillers or additives in polymers for various desired effects is a subject of an increased interest for research and development to establish various applications. An increased consumption is indicated by the wider applications of clay nanocomposites approaching to almost one-quarter (24 pct) in 2005 of the total nanocomposites used. However, an interesting concern, along with the studies addressing how nanoclays change the behavior of polymeric materials, is to discover what are clays, nanoclays and montmorillonite minerals. The various structures of montmorillonite available in nature and their modification for application are discussed. An attempt is made to review the origin of using clays when nanotechnology did not exist, coupled with the effects of montmorillonite-based nanoclays on commercially known polymers.

Uddin, Faheem

2008-12-01

6

Clay mineralogy of weathering rinds and possible implications concerning the sources of clay minerals in soils.  

USGS Publications Warehouse

Weathering rinds on volcanic clasts in Quaternary deposits in the western US contain only very fine-grained and poorly crystalline clay minerals. Rinds were sampled from soils containing well-developed argillic B horizons in deposits approx 105 yr old or more. The clay-size fraction of the rinds is dominated by allophane and iron hydroxy-oxides, whereas the B horizons contain abundant well-crystallized clay minerals. The contrast between the clay mineralogy of the weathering rinds, in which weathering is isolated from other soil processes, and that of the associated soil matrices suggests a need to reassess assumptions concerning the rates at which clay minerals form and the sources of clay minerals in argillic B horizons. It seems that crystalline clay minerals form more slowly in weathering rinds than is generally assumed for soil environments and that the weathering of primary minerals may not be the dominant source of crystalline clay minerals in Middle to Late Pleistocene soil.-A.P.

Colman, S. M.

1982-01-01

7

Clay Mineralogy of Central Victorian (Creswick) Soils: Clay Mineral Contents as a Possible Tool of Environmental Indicator  

Microsoft Academic Search

The clay mineralogy and heavy metal\\/metalloid (As, Pb and Cu) contents of soils developed on the various rock units in a central highlands environment in Victoria (Creswick, Australia) have been investigated. The clay minerals identified showed an order of abundance as: kaolinite ? illite > smectite > mixed-layer (ML) ? vermiculite. The soil clay mineralogy did not change systematically with

Khawar Sultan

2006-01-01

8

Surface Geochemistry of the Clay Minerals  

NASA Astrophysics Data System (ADS)

Clay minerals are layer type aluminosilicates that figure in terrestrial biogeochemical cycles, in the buffering capacity of the oceans, and in the containment of toxic waste materials. They are also used as lubricants in petroleum extraction and as industrial catalysts for the synthesis of many organic compounds. These applications derive fundamentally from the colloidal size and permanent structural charge of clay mineral particles, which endow them with significant surface reactivity. Unraveling the surface geochemistry of hydrated clay minerals is an abiding, if difficult, topic in earth sciences research. Recent experimental and computational studies that take advantage of new methodologies and basic insights derived from the study of concentrated ionic solutions have begun to clarify the structure of electrical double layers formed on hydrated clay mineral surfaces, particularly those in the interlayer region of swelling 2:1 layer type clay minerals. One emerging trend is that the coordination of interlayer cations with water molecules and clay mineral surface oxygens is governed largely by cation size and charge, similarly to a concentrated ionic solution, but the location of structural charge within a clay layer and the existence of hydrophobic patches on its surface provide important modulations. The larger the interlayer cation, the greater the influence of clay mineral structure and hydrophobicity on the configurations of adsorbed water molecules. This picture extends readily to hydrophobic molecules adsorbed within an interlayer region, with important implications for clay-hydrocarbon interactions and the design of catalysts for organic synthesis.

Sposito, Garrison; Skipper, Neal T.; Sutton, Rebecca; Park, Sung-Ho; Soper, Alan K.; Greathouse, Jeffery A.

1999-03-01

9

Liquid crystal\\/clay mineral composites  

Microsoft Academic Search

Novel liquid crystalline composites composed of a nematic two-frequency addressing liquid crystal (TFALC) and a few percents of various types of organized clay minerals (LCC) have been prepared. The affinity of the organized clay minerals for the liquid crystal, which was evaluated by measuring their contact angles, was highly dependent on the kind of organic ammonium cations used for the

Masaya Kawasumi; Naoki Hasegawa; Arimitsu Usuki; Akane Okada

1999-01-01

10

Mineral Abundance Near Aristarchus Crater  

NASA Astrophysics Data System (ADS)

Mineral Abundance Near Aristarchus Crater Alison Bradford and Alex Storrs Towson University We analyze Hubble Space Telescope (HST) images to determine the abundance of minerals near Aristarchus crater. Following the calibration of Robinson et al. (2007) we present ratio maps of images obtained in August of 2005 showing the abundance of TiO2 and other minerals in this interesting area in the middle of Oceanus Procellarum. A prominent cleft (Schroter's Valley, presumably a collapsed lava tube) makes this region of special interest for analyzing the formation of mare basalts. Reference: Robinson, M.S., et al. (2007): "High resolution mapping of TiO2 abundances on the Moon using the Hubble Space Telescope", GRL 34, L13203

Bradford, Alison; Storrs, A.

2007-12-01

11

Thermal analysis of selected illite and smectite clay minerals. Part II. Smectite clay minerals  

NASA Astrophysics Data System (ADS)

In this paper, the application of the techniques of differential thermal analysis (DTA), thermogravimetry (TG) and derivative thermogravimetry (DTG) to the characterization of smectite clay minerals is presented. Several specimens including both dioctahedral and trioctahedral types of smectite clay mineral are included here. The use of DTA to separate the mineral montmorillonite into two subtypes is demonstrated. A unique industrial example of the use of TG to follow the cleaning of a raw bentonite clay and its subsequent conversion into an organo-clay product is demonstrated. The thermal analysis of both raw and processed hectorite clay specimens which was originally performed by the author is reviewed.

Earnest, C. M.

12

Clay minerals as photochemical reaction fields  

Microsoft Academic Search

This article surveys the intercalation characteristics of a number of clay minerals which can be utilized as host materials for photofunctional organic–inorganic hybrid systems as well as photochemical anisotropic reaction fields. The introduction of this review describes the chemical compositions and the structural features of various kinds of artificial as well as naturally produced clays. The chemical structures of these

Tetsuya Shichi; Katsuhiko Takagi

2000-01-01

13

Ultrathin hybrid films of clay minerals.  

PubMed

Smectites or swelling clay minerals are naturally occurring nanomaterials that can be fully delaminated to elementary clay mineral platelets in dilute aqueous dispersion. This review article gives an overview of the recent progress on how the elementary clay mineral platelets can be reorganized in monolayered or multilayered hybrid nanofilms by layer-by-layer assembly or the Langmuir-Blodgett technique. In the latter case one hybrid layer consists of one layer of elementary clay mineral platelets with a theoretical thickness of 0.96 nm, covered on one side by amphiphilic cations. The organization of the elementary clay mineral platelets and that of the adsorbed amphiphilic cations in the nanofilms has been studied in great detail by ATR-FTIR, UV-Vis and fluorescence spectroscopy, XRD and AFM. The nanofilms carry functional properties, such as chirality, optical nonlinearity and magnetism, which are due to the nature of the amphiphilic cations and to the organization of both the amphiphilic molecules and the elementary clay mineral platelets. PMID:17301882

Ras, Robin H A; Umemura, Yasushi; Johnston, Cliff T; Yamagishi, Akihiko; Schoonheydt, Robert A

2006-12-19

14

Elastic properties of dry clay mineral aggregates, suspensions and sandstones  

Microsoft Academic Search

The presence of clay minerals can alter the elastic behaviour of rocks significantly. Although clay minerals are common in sedimentary formations and seismic measurements are our main tools for studying subsurface lithologies, measurements of elastic properties of clay minerals have proven difficult. Theoretical values for the bulk modulus of clay are reported between 20 and 50 GPa. The only published

Tiziana Vanorio; Manika Prasad; Amos Nur

2003-01-01

15

Mineral Abundances in Martian Soils  

NASA Astrophysics Data System (ADS)

Using traditional geochemical calculations with in situ Martian cosmochemical data researchers Harry (Hap) McSween Jr. and Ian McGlynn (University of Tennessee) and Deanne Rogers (SUNY at Stony Brook) have developed a method for identifying the major and minor minerals in soils at the Mars Exploration Rovers (MER) landing sites. The team used information from the MER Athena instrument package operating on Mars since January, 2004. They created two models using MiniTES spectra, Alpha Particle X-ray Spectrometer (APXS) data, and Mossbauer spectrometer data to calculate the mineralogy of average dark soils on the Gusev crater plains and on Meridiani Planum, located on opposite sides of Mars. Soils at both locations are similarly composed of minerals derived from the comminution of basalts (about three quarters by weight) and other minerals derived from rocks altered by chemical weathering (about one quarter by weight). This mixture of possibly unrelated materials (primary and altered) might mean that the alteration of soil did not occur in place and that the basaltic and alteration suites of minerals came from different sources. The nearly identical modal mineralogy at two widely-separated locations on the planet supports a previous hypothesis based on comparable chemical compositions that soils have been homogenized, if not globally then at least over large areas of the Martian surface. Yet, global maps of orbital remote sensing data have not shown surface abundances of alteration minerals as high as those in the Martian soils.

Martel, L. M. V.

2011-01-01

16

Surface Geochemistry of the Clay Minerals  

Microsoft Academic Search

Clay minerals are layer type aluminosilicates that figure in terrestrial biogeochemical cycles, in the buffering capacity of the oceans, and in the containment of toxic waste materials. They are also used as lubricants in petroleum extraction and as industrial catalysts for the synthesis of many organic compounds. These applications derive fundamentally from the colloidal size and permanent structural charge of

Garrison Sposito; Neal T. Skipper; Rebecca Sutton; Sung-Ho Park; Alan K. Soper; Jeffery A. Greathouse

1999-01-01

17

Radiation-induced defects in clay minerals: A review  

NASA Astrophysics Data System (ADS)

Extensive information has been collected on radiation effects on clay minerals over the last 35 years, providing a wealth of information on environmental and geological processes. The fields of applications include the reconstruction of past radioelement migrations, the dating of clay minerals or the evolution of the physico-chemical properties under irradiation.The investigation of several clay minerals, namely kaolinite, dickite, montmorillonite, illite and sudoite, by Electron Paramagnetic Resonance Spectroscopy has shown the presence of defects produced by natural or artificial radiations. These defects consist mostly of electron holes located on oxygen atoms of the structure. The various radiation-induced defects are differentiated through their nature and their thermal stability. Most of them are associated with a ? orbital on a Si-O bond. The most abundant defect in clay minerals is oriented perpendicular to the silicate layer. Thermal annealing indicates this defect in kaolinite (A-center) to be stable over geological periods at ambient temperature. Besides, electron or heavy ion irradiation easily leads to an amorphization in smectites, depending on the type of interlayer cation. The amorphization dose exhibits a bell-shaped variation as a function of temperature, with a decreasing part that indicates the influence of thermal dehydroxylation. Two main applications of the knowledge of radiation-induced defects in clay minerals are derived: (i) The use of defects as tracers of past radioactivity. In geological systems where the age of the clay can be constrained, ancient migrations of radioelements can be reconstructed in natural analogues of high level nuclear waste repositories. When the dose rate may be assumed constant over time, the paleodose is used to date clay populations, an approach applied to fault gouges or laterites of the Amazon basin. (ii) The influence of irradiation over physico-chemical properties of clay minerals. An environmental application concerns the performance assessment of the engineered barrier of nuclear waste disposals. In case of a leakage of transuranic elements from the radioactive waste form, alpha recoil nuclei can amorphize smectite after periods of the order of 1000 years according to a worst case scenario, whereas amorphization from ionizing radiation is unlikely. As amorphization greatly enhances the dissolution kinetics of smectite, the sensitivity of the smectites must be taken into account in the prediction of the long term behavior of engineered barriers.

Allard, Th.; Balan, E.; Calas, G.; Fourdrin, C.; Morichon, E.; Sorieul, S.

2012-04-01

18

Lipid peroxidation induced by expandable clay minerals.  

PubMed

Small-sized environmental particles such as 2:1 phyllosilicates induce oxidative stress, a primary indicator of cell damage and toxicity. Herein, potential hazards of clay particle uptake are addressed. This paper reports that the content and distribution of structural Fe influence the ability of expandable clay minerals to induce lipid peroxidation (LP), a major indicator of oxidative stress, in biological matrices. Three smectite clays, hectorite (SHCa-1) and two nontronites (NAu-1) and (NAu-2) containing varying total content and coordination environment of structural Fe, were selected. Screening and monitoring of LP was conducted using a thiobarbituric acid reactive substances (TBARS) assay. The higher content of TBARS in nontronites than that in SHCa-1 suspensions was explained because structural Fe contributes to LP. The observed lack of correlation between TBARS content and the extent of Fe dissolution indicated that the formation of TBARS is surface controlled. Results showing a high TBARS content in SHCa-1 but not in nontronite supematant solutions was explained because the former contains distinct, soluble chemical component(s) that could (i) induce LP by its (their) own right and (ii) whose chemical affinity for organic ligands used as inhibitors is weak. Clays serve as stronger inductors than 2,2'-azobis(2-amidinopropane) dihydrochloride (AAPH) but are much weaker than FeSO4. The outcome of this work shows that LP is clay surface-controlled and dependent on clay structural composition. PMID:19848175

Kibanova, Daria; Nieto-Camacho, Antonio; Cervini-Silva, Javiera

2009-10-01

19

Identification of clay minerals by infrared spectroscopy and discriminant analysis.  

PubMed

Identification of clay minerals based on chemometric analysis of measured infrared (IR) spectra was suggested. IR spectra were collected using the diffuse reflection technique. Discriminant analysis and principal component analysis were used as chemometric methods. Four statistical models were created for separation and identification of clay minerals. More than 50 samples of various clay mineral standards from different localities were used for the creation of statistical models. The results of this study confirm that the discriminant analysis of IR spectra of clay minerals could provide a powerful tool for identification of clay minerals. Differentiation of muscovite from illite and identification of mixed structures of illite-smectite were achieved. PMID:21144156

Ritz, Michal; Vaculíková, Lenka; Plevová, Eva

2010-12-01

20

Clay Mineral Composition of Sediments in Some Desert Lakes in Nevada, California, and Oregon.  

PubMed

X-ray analyses of some Recent desert lacustrine sediments in Nevada, California, and Oregon show that illite and montmorillonite are the most abundant clay minerals and that chlorite and kaolinite are present in subordinate amounts in the sediments of many of the lakes. These clay suites are derived from source rocks. PMID:17738874

Droste, J B

1961-06-16

21

Growth of Iron(III)Reducing Bacteria on Clay Minerals as the Sole Electron Acceptor and Comparison of Growth Yields on a Variety of Oxidized Iron Forms  

Microsoft Academic Search

Smectite clay minerals are abundant in soils and sediments worldwide and are typically rich in Fe. While recent investigations have shown that the structural Fe(III) bound in clay minerals is reduced by microor- ganisms, previous studies have not tested growth with clay minerals as the sole electron acceptor. Here we have demonstrated that a pure culture of Shewanella oneidensis strain

Joel E. Kostka; Dava D. Dalton; Hayley Skelton; Sherry Dollhopf; Joseph W. Stucki

2002-01-01

22

Electrokinetics of pure clay minerals revisited  

SciTech Connect

Clay minerals have long attracted the attention of colloid scientists. This paper considers, specifically, their important role in the transport of various contaminants from land to sea, e.g., metal ions and organic detrital and man-made material in watercourses. Advance in experimental techniques have enabled precise characterization of clays and then electrokinetic experiments at high electrolyte concentrations, such as in seawater. Three of the most important clay minerals encountered in suspended matter in natural waters, montmorillonite, illite, and chlorite, were prepared in a very pure state. Electrokinetic experiments were done in pure aqueous single and complex electrolyte solutions and in solutions in which natural organic matter was simulated using a humic substance, fulvic acid, of defined provenance and properties, typical of riverine waters. An isoelectric point was found at pH 5.0 {+-} 0.2 for chlorite; none were found for illite and montmorillonite. Only Ca{sup 2+} showed a charging effect on chlorite, indeed a reversal of sign from negative to positive at 1 {times} 10{sup {minus}3} mol dm{sup {minus}3}. Addition of fulvic acid affected only chlorite, illite less, and Na montmorillonite not at all.

Sondi, I.; Biscan, J.; Pravdic, V. [Rudjer Boskovic Inst., Zagreb (Croatia). Center for Marine Research

1996-03-25

23

Organo clay mineral–melted polyolefin nanocomposites Effect of surfactant\\/CEC ratio  

Microsoft Academic Search

Clay mineral–polymer nanocomposites are prepared by dispersing solid organo clay minerals in two different melted polyolefin matrices, namely polyethylene (PE) and ethylene vinyl acetate (EVA). The organo clay minerals are prepared by adding different amounts of surfactant corresponding to the CEC of the pristine clay mineral. The characteristics of the organo clay minerals are obtained by XRD, IR spectroscopy, TGA,

Tushar Mandalia; Faïza Bergaya

2006-01-01

24

The effect of clay minerals on diasterane/sterane ratios  

NASA Astrophysics Data System (ADS)

To examine the effect of clay minerals on diasterane/sterane ratios, the mineral compositions of three sample sets of sedimentary rocks displaying a wide range of diasterane/sterane ratios were analysed quantitatively. Diasterane/sterane ratios do not to correlate with clay content but depend on the amount of clay relative to the amount of organic matter (clay/TOC ratios). This correlation may explain the high diasterane/sterane ratios in crude oils and extracts derived from certain carbonate source rocks. Based on the concentrations of regular and rearranged steroids in the sample sets, it is proposed that diasterenes are partly reduced to diasteranes and partly degraded during diagenesis in a ratio largely determined by the availability of clay minerals. It is suggested that the hydrogen atoms required for reduction of the diasterenes originate from the water in the interlayers of clay minerals.

van Kaam-Peters, Heidy M. E.; Köster, Jürgen; van der Gaast, Sjierk J.; Dekker, Marlèn; de Leeuw, Jan W.; Sinninghe Damsté, Jaap S.

1998-09-01

25

The systems containing clays and clay minerals from modified drug release: a review.  

PubMed

Clays are materials commonly used in the pharmaceutical industry, either as ingredients or as active ingredients. It was observed that when they are administered concurrently, they may interact with drugs reducing their absorption. Therefore, such interactions can be used to achieve technological and biopharmaceutical advantages, regarding the control of release. This review summarizes bibliographic (articles) and technological (patents) information on the use of systems containing clays and clay minerals in modified drug delivery. In this area, formulations such natural clay, commercial clay, synthetic clay, composites clay-polymers, nanocomposites clay-polymers, films and hidrogels composites clay-polymers are used to slow/extend or vectorize the release of drugs and consequently they increase their bioavailability. Finally, this review summarizes the fields of technology and biopharmaceutical applications, where clays are applied. PMID:23253474

Rodrigues, Luís Alberto de Sousa; Figueiras, Ana; Veiga, Francisco; de Freitas, Rivelilson Mendes; Nunes, Lívio César Cunha; da Silva Filho, Edson Cavalcanti; da Silva Leite, Cleide Maria

2012-11-20

26

Ammonium fixation by soil and pure clay minerals  

Microsoft Academic Search

Fixation of the ammonium ion (NH4 ) by clay minerals is an alternate way of building the nitrogen (N) pool in soil to optimize N crop recovery and minimize losses. Clay minerals (illite, montmorillonite, and vermiculite) and an illitic Portnoeuf soil were used to compare NH4 fixation abilities. Total N determination and X?ray diffraction analysis were performed on each of

Martha Mamo; Robert W. Taylor; James W. Shuford

1993-01-01

27

Clays and Clay Minerals and their environmental application in Food Technology  

NASA Astrophysics Data System (ADS)

The clay materials have led to numerous applications in the field of public health (del Hoyo, 2007; Volzone, 2007) having been demonstrated its effectiveness as adsorbents of all contaminants. Some biodegradable materials are used for for adsorption of chemical contaminants: lignins (Valderrabano et al., 2008) and also clays and clay minerals, whose colloidal properties, ease of generating structural changes, abundance in nature, and low cost make them very suitable for this kind of applications. Among the strategies used at present to preserve the quality of the water and this way to diminish the environmental risk that supposes the chemical pollution, stands out the use of adsorbents of under cost, already they are natural or modified, to immobilize these compounds and to avoid the pollution of the water with the consequent reduction of environmental and economic costs Thanks to the development of the science and the technology of the nourishment in the last 50 years, there have revealed itself several new substances that can fulfill beneficial functions in the food, and these substances, named food additives, are today within reach of all. The food additives recover a very important role in the complex nourishing supply. The additives fulfill several useful functions in the food, which often we give for sat. Nevertheless the widespread use of food additives in the food production also influences the public health. The food industries, which are very important for the economy, spill residues proved from its activity that they have to be controlled to evaluate the environmental impact and to offer the necessary information about the quantitative evaluation of the chemical risk of the use of food additives for the public health. We have studied the adsorption of several contaminants by natural or modified clays, searching their interaction mechanisms and the possible recycling of these materials for environmental purposes and prevention of the health. References -del Hoyo, C. (2007). Applied Clay Science. 36, 103-121.Layered Double Hydroxides and human health: An overview. -Valderrábano, M., Rodríguez-Cruz, S., del Hoyo, C., Sánchez-Martín, M.J. (2006). 4th International Workshop "Bioavalailability of pollutants and soil remediation". 1, 5-6. Physicochemical study of the adsorption of pesticides by lignins. -Volzone, C. (2007). Applied Clay Science. 36, 191-196. Retention of pollutant gases: Comparison between clay minerals and their modified products.

del Hoyo Martínez, Carmen; Cuéllar Antequera, Jorge; Sánchez Escribano, Vicente; Solange Lozano García, Marina; Cutillas Díez, Raul

2013-04-01

28

Desorption of ciprofloxacin from clay mineral surfaces.  

PubMed

Desorption from soil clay components may affect the transport and fate of antibiotics in the environment. In this study, ciprofloxacin (CIP) desorption from a kaolinite and a montmorillonite was investigated under different pHs, different concentrations of metal cations of various valencies (Na(+), Ca(2+) and Al(3+)) and a cationic surfactant hexadecyltrimethylammonium (HDTMA), and different desorption cycles. Desorption of CIP from kaolinite and montmorillonite was strongly pH-dependent and desorption isotherms were well fitted with the Langmuir equation. The percentage of CIP desorbed increased with increasing initial CIP loadings, desorbing cation concentrations, and desorption cycles. Comparatively, CIP was more readily desorbed from kaolinite than from montmorillonite. Moreover, the hysteresis index values were all negative, suggesting that the presence of metal cations and HDTMA in solution promoted CIP desorption from clay minerals, owing to cation exchange. The XRD analyses indicated that desorption of CIP occurred from both external and interlayer surfaces of montmorillonite. Formation of Al-CIP complex on solid surface and then detachment of Al-CIP from the solid surface may contribute to the higher CIP desorption by Al(3+) in comparison to Na(+) and Ca(2+). PMID:23123088

Wu, Qingfeng; Li, Zhaohui; Hong, Hanlie; Li, Rongbiao; Jiang, Wei-Teh

2012-10-13

29

Relationship between sediment clay minerals and total mercury.  

PubMed

A group of 262 sediment samples were collected from various lakes, rivers, reservoirs, and bayous of Louisiana. All samples were analyzed for total mercury. Twenty nine of the samples with total mercury content ranging from 11 to 401 ppb (?g/kg) were analyzed for clay minerals and other sediment physical and chemical properties. Clay content in sediments varied from 3 to 72%. Clay minerals were determined by X-ray diffraction (XRD) technique. Identification of clay minerals was determined by MacDiff software and quantification of clay minerals was obtained by Peak Height Percentage (PHP) calculation. The dominant clay mineral was Hydrated Interlayer Vermiculite (HIV), which represented 51-83% of the total clay mineral. Significant linear correlations were observed between Hg and total clay content (r=0.538**). However Smectite was the only individual clay type correlated (r=0.465**) with mercury in sediment. Cation exchange capacity (r=0.404*), organic matter (r=0.577**), and sulfur (r=0.676**) were also correlated significantly with mercury level in sediment. PMID:21469014

Kongchum, Manoch; Hudnall, Wayne H; DeLaune, R D

2011-01-01

30

Clay mineral formation and transformation in rocks and soils  

USGS Publications Warehouse

Three mechanisms for clay mineral formation (inheritance, neoformation, and transformation) operating in three geological environments (weathering, sedimentary, and diagenetic-hydrothermal) yield nine possibilities for the origin of clay minerals in nature. Several of these possibilities are discussed in terms of the rock cycle. The mineralogy of clays neoformed in the weathering environment is a function of solution chemistry, with the most dilute solutions favoring formation of the least soluble clays. After erosion and transportation, these clays may be deposited on the ocean floor in a lateral sequence that depends on floccule size. Clays undergo little reaction in the ocean, except for ion exchange and the neoformation of smectite; therefore, most clays found on the ocean floor are inherited from adjacent continents. Upon burial and heating, however, dioctahedral smectite reacts in the diagenetic environment to yield mixed-layer illite-smectite, and finally illite. With uplift and weathering, the cycle begins again. Refs.

Eberl, D. D.

1983-01-01

31

Elastic properties of dry clay mineral aggregates, suspensions and sandstones  

NASA Astrophysics Data System (ADS)

The presence of clay minerals can alter the elastic behaviour of rocks significantly. Although clay minerals are common in sedimentary formations and seismic measurements are our main tools for studying subsurface lithologies, measurements of elastic properties of clay minerals have proven difficult. Theoretical values for the bulk modulus of clay are reported between 20 and 50 GPa. The only published experimental measurement of Young's modulus in a clay mineral using atomic force acoustic microscopy (AFAM) gave a much lower value of 6.2 GPa. This study has concentrated on using independent experimental methods to measure the elastic moduli of clay minerals as functions of pressure and saturation. First, ultrasonic P- and S-wave velocities were measured as functions of hydrostatic pressure in cold-pressed clay aggregates with porosity and grain density ranging from 4 to 43 per cent and 2.13 to 2.83 g cm-3, respectively. In the second experiment, P- and S-wave velocities in clay powders were measured under uniaxial stresses compaction. In the third experiment, P-wave velocity and attenuation in a kaolinite-water suspension with clay concentrations between 0 and 60 per cent were measured at ambient conditions. Our elastic moduli measurements of kaolinite, montmorillonite and smectite are consistent for all experiments and with reported AFAM measurements on a nanometre scale. The bulk modulus values of the solid clay phase (Ks) lie between 6 and 12 GPa and shear (?s) modulus values vary between 4 and 6 GPa. A comparison is made between the accuracy of velocity prediction in shaley sandstones and clay-water and clay-sand mixtures using the values measured in this study and those from theoretical models. Using Ks= 12 GPa and ?s= 6 GPa from this study, the models give a much better prediction both of experimental velocity reduction due to increase in clay content in sandstones and velocity measurements in a kaolinite-water suspension.

Vanorio, Tiziana; Prasad, Manika; Nur, Amos

2003-10-01

32

Introduction to the properties of clay minerals  

NSDL National Science Digital Library

This activity explores how clay affects the permeability of sands, the effect of chemical differences of the clay (cation exchange), and how these results may be applied to low-level radioactive waste disposal sites.

Guggenheim, Stephen

33

Palaeoenvironmental significance of the clay mineral composition of Olduvai basin deposits, northern Tanzania  

NASA Astrophysics Data System (ADS)

Quaternary deposits in the southeastern part of the Olduvai basin, northern Tanzania, consist of lake margin deposits, followed by a series of fluvial sediments. The clay mineral fraction of the lake margin deposits (Bed I and lower part of Bed II) is composed of smectite and subordinate illite. All smectite is largely dioctahedral and shows indications for a limited degree of irregular interstratification by illite. In the overlying fluvial deposits (Beds II IV), illite is the most abundant clay mineral. Smectite only occurs in lower parts of the fluvial deposits (up to the middle of Bed III), where it generally shows a high degree of irregular interstratification. Differences in clay mineral composition between the lake margin deposits and the fluvial deposits record differences in sediment source area and degree of alteration. Dioctahedral smectite in the lake margin deposits and the oldest fluvial deposits is derived from a region with volcanic material extending to the east and south of the basin, which also supplies a certain amount of illite. Illite in the fluvial deposits of Bed IV originates from an area with a metamorphic bedrock to the west and north. Alteration of detrital clay minerals resulted in Mg-enrichment of dioctahedral smectite in part of the lake margin deposits and partial illitization of smectite in the older fluvial deposits. Formation of clay minerals during diagenesis or soil development is not documented by analysis of the total clay fraction.

Mees, Florias; Segers, Stijn; Ranst, Eric Van

2007-01-01

34

Flouride Content of Clay Minerals and Argillaceous Earth Materials  

Microsoft Academic Search

A reliable method, utilizing a fluoride ion-selective electrode, is described for the determina- tion of fluoride in clays and shales. Interference by aluminum and iron is minimal. The reproducibility of the method is about ___5~0 at different levels of fluoride concentration. Data are presented for various clay minerals and for the <2-\\/~m fractions of marine and nonmarine clays and shales.

Josephus Thomas; H. D. GLASS; W. A. WHITE; R. M. TRANDEL

1977-01-01

35

Adsorption coefficients for TNT on soil and clay minerals  

Microsoft Academic Search

To understand the fate and transport mechanisms of TNT from buried landmines is it essential to determine the adsorption process of TNT on soil and clay minerals. In this research, soil samples from horizons Ap and A from Jobos Series at Isabela, Puerto Rico were studied. The clay fractions were separated from the other soil components by centrifugation. Using the

Rosángela Rivera; Julissa Pabón; Omarie Pérez; Miguel A. Muñoz; Nairmen Mina

2007-01-01

36

Sources and sinks of clay minerals on Mars  

NASA Astrophysics Data System (ADS)

The recent identification of clay minerals on the Martian surface using visible-near infrared reflectance spectroscopy has had a profound effect on our view of aqueous alteration on Mars. Smectite, chlorite, kaolin group, and serpentine group minerals have been detected using the CRISM and OMEGA spectrometers, with Fe/Mg-smectite and chlorite varieties being the dominant types discovered throughout the ancient crust. Aqueous, eolian, and impact processes have transported and recycled some of these clays such that their current locations may not accurately reflect their formation environments. However, detrital clays could prove useful for constraining transport pathways and sediment provenance. Here we discuss the impact craters and channels that comprise the Uzboi-Ladon-Morava system, including Holden, Eberswalde, and Ladon craters, which represents a large-scale sediment sink for clay minerals derived from the surrounding Noachian crust. This system contains thick deposts of clay mineral-bearing strata that likely record a wide range of alluvial, fluvial, lacustrine, and eolian processes that provide direct insight into the Martian clay cycle. Broad concepts of sediment sources, sinks, and sediment transport paths can be outlined using orbital data, but future in situ exploration of the Martian sedimentary rock record will be necessary to distinguish fully between detrital and authigenic clay minerals, and thus to determine environmental conditions and transitions on ancient Mars.

Milliken, Ralph E.; Bish, David L.

2010-06-01

37

Thermal analysis of selected illite and smectite clay minerals. Part I. Illite clay specimens  

Microsoft Academic Search

The characterization of illite clay minerals by the use of the technique of differential thermal analysis (DTA), thermogravimetry (TG) and derivative thermogravimetry (DTG) is presented. This presentation is offered not only as a review of the thermal characteristics of this important group of clay materials but suggestions relative to the application of the thermal analysis techniques to contaminated illitic specimens;

C. M. Earnest

38

Thermal analysis of selected illite and smectite clay minerals. Part I. Illite clay specimens  

Microsoft Academic Search

The characterization of illite clay minerals by the use of the technique of differential thermal analysis (DTA), thermogravimetry (TG) and derivative thermogravimetry (DTG) is presented. This presentation is offered not only as a review of the thermal characteristics of this important group of clay materials but suggestions relative to the application of the thermal analysis techniques to contaminated illitic specimens;

C. M. Earnest

1991-01-01

39

Clay and non-clay minerals in the pharmaceutical industry  

Microsoft Academic Search

Minerals are widely used in the pharmaceutical industry as lubricants, desiccants, disintegrants, diluents, binders, pigments and opacifiers, as well as emulsifying, thickening, isotonic agents, and anticaking agents, and flavour correctors and carriers of active ingredients.A variety of minerals are used as excipients in pharmaceutical preparations because they have certain desirable physical and physico-chemical properties, such as high adsorption capacity, specific

M. Isabel Carretero; Manuel Pozo

2009-01-01

40

The Influences of Clay Minerals on Methane Hydrate Formation  

NASA Astrophysics Data System (ADS)

Natural gas hydrates exist in sediment, either filling sediment pores or locally aggregated as nodular or massive hydrate. The elucidation of the role of the sediment matrix on gas hydrate formation is crucial to understanding the formation mechanism and accumulation of methane hydrate in natural environments. Clay minerals are common constituents of natural sediments. From the results of field and laboratory investigations, as well as theoretical studies, clay minerals are likely to play an important role in controlling the occurrence of natural gas hydrate. However the mechanism of how clay minerals affect hydrate formation is still not well understood. Present research aims at elucidating the role of clay minerals in hydrate formation through experimental investigations. Three types of clays typical of natural sediments have been selected as the test materials: Na-montmorillonite, Ca-montmorillonite, and Kaolinite. Na-montmorillonite and Ca-montmorillonite are 2:1 types, among which interlayer distances (d-spacing) of Na-montmorillonite and Ca-montmorillonite can increase when soaked in water, while the former has much stronger swelling ability than the latter. Kaolinite is 1:1 type, not able to expand its interlayer distance. For the purpose of comparison, quartz was also tested. The results of the P-T stability conditions of methane hydrate in various water-saturated clay minerals, indicated that Ca-montmorillonite and kaolinite are thermodynamic inhibitors for gas hydrate formation, shifting the stability conditions to a regime of relatively lower temperature and higher pressure, while in situ observations on methane hydrate formation in clay minerals by MRI (Magnetic Resonance Imaging) found that clay minerals are kinetic promoters of gas hydrate formation, shortening the induction time greatly as compared to quartz sand.

Kawasaki, T.; Hailong, L.; Ripmeester, J.; Moudrakovski, I.; Zeng, H.; Lee, J.; Fujii, T.; Nakamizu, M.

2006-12-01

41

Geochemistry of clay minerals for uranium exploration in the Grants mineral belt, New Mexico  

NASA Astrophysics Data System (ADS)

Clay mineralogy studies of ore rocks versus barren rocks in the Grants mineral belt, New Mexico, show that some combination of chlorite (rosette form), illite, mixed-layer illite-montmorillonite, (±Mg-montmorillonite) are penecontemporaneous with uranium minerals in trend ore; these same clay minerals plus kaolinite are related to the roll-type ore near the main redox front of the Grants mineral belt. Clay minerals from barren rocks are characterized by a greater abundance of Na-montmorillonite, kaolinite, and face-to-edge form chlorite. Chlorites from ore zones contain much more vanadium than do chlorites from barren rocks. Trend orr probably formed from southeasterly flowing waters following paleochannels in the Late Jurassic. These deposits are found almost entirely in reduced rocks, and organic carbon may have been an important reductant to remove U-V-U-V-Se-Mo from solution as carbonate from ore zones contains some organic carbon based on stable isotope studies. Uplift, remobilization, and reprecipitation of some of the trend ore resulted in the formation of redistributed ore, some of which possesses a roll-type geometry. Mineralization for the roll-type ore was apparently controlled by sulfide-sulfate equilibria at or near the main redox front in the Grants mineral belt. Trend and roll-type ore possess different assemblages of clay minerals and different trace element abundances. Laramide-age faults cut both trend ore and some roll-type ores. Stack ore is found in Laramide-age fault zones. Limited oxygen isotopic data from clay minerals collected from two mines at Ambrosia Lake in reduced rocks indicate probable preservation of ancient, formational waters and show no evidence of infiltration by young meteoric waters. This information, plus the pre-Laramide-age faults, suggest, but do not unequivocally prove, that the main redox front has been relatively stable since its formation, probably some time in the Cretaceous. Younger encroachment of the redox front in post-Laramide time is proposed by others, however, and the problem is unresolved. Uranium for the deposits was most likely carried in solution as an oxyion, probably as (UO2(CO3)2·2H2O2- or (UO2(HPO4)2)2-, although organic transport cannot be entirely ruled out. Oxyions of vanadium, selenium, molybdenum and possible arsenic and antimony, are interpreted from Eh-pH diagrams to have been segregated and transported with U6+ soluble species and precipitated when a chemically reducing environment was reached. The rare-earth elements are also enriched in ore zones, but is it not clear if they were transported with the U-V-Se-Mo-(As)-(Sb) suite or derived from a more local source.

Brookins, D. G.

1982-03-01

42

Surface modification of clay minerals by organic polyions  

Microsoft Academic Search

Parallel studies were made of the solid\\/gas and solid\\/liquid interfacial properties and the colloidal behaviour of aqueous dispersions of two types of material: soil mineral grains which had been coated with natural organic matter (humus) and clay minerals (montmorillonite and kaolinite) whose surfaces had been modified synthetically with an organic polyacid, as models for organo-mineral complexes. Solid samples with and

E. Tombácz; M. Szekeres; L. Baranyi; E. Michéli

1998-01-01

43

Intercalation of trichloroethene by sediment-associated clay minerals.  

PubMed

The objective of this research was to examine the potential for intercalation of trichloroethene (TCE) by clay minerals associated with aquifer sediments. Sediment samples were collected from a field site in Tucson, AZ. Two widely used Montmorillonite specimen clays were employed as controls. X-ray diffraction, conducted with a controlled-environment chamber, was used to characterize smectite interlayer d-spacing for three treatments (bulk air-dry sample, sample mixed with synthetic groundwater, sample mixed with TCE-saturated synthetic groundwater). The results show that the d-spacing measured for the samples treated with TCE-saturated synthetic groundwater are larger (~26%) than those of the untreated samples for all field samples as well as the specimen clays. These results indicate that TCE was intercalated by the clay minerals, which may have contributed to the extensive elution tailing observed in prior miscible-displacement experiments conducted with this sediment. PMID:22921434

Matthieu, D E; Brusseau, M L; Johnson, G R; Artiola, J L; Bowden, M L; Curry, J E

2012-08-24

44

Intercalation of Trichloroethene by Sediment-Associated Clay Minerals  

SciTech Connect

The objective of this research was to examine the potential for intercalation of trichloroethene (TCE) by clay minerals associated with aquifer sediments. Sediment samples were collected from a field site inTucson, AZ. Two widely used Montmorillonite specimen clays were employed as controls. X-ray diffraction, conducted with a controlled-environment chamber, was used to characterize smectite interlayer dspacing for three treatments (bulk air-dry sample, sample mixed with synthetic groundwater, sample mixed with TCE-saturated synthetic groundwater). The results show that the d-spacing measured for the samples treated with TCE-saturated synthetic groundwater are larger (*26%) than those of the untreated samples for all field samples as well as the specimen clays. These results indicate that TCE was intercalated by the clay minerals, which may have contributed to the extensive elution tailing observed in prior miscible-displacement experiments conducted with this sediment.

Matthieu, Donald E.; Brusseau, Mark; Johnson, G. R.; Artiola, J. L.; Bowden, Mark E.; Curry, J. E.

2013-01-01

45

TRIAZINE ADSORPTION BY SAPONITE AND BEIDELLITE CLAY MINERALS  

Microsoft Academic Search

Abstract—We investigated the sorption of three triazine herbicides (atrazine, simazine, and metribuzin) by saponite and beidellite clay minerals saturated with K, reduces the swelling of clay interlayers, thus making sorption domains less hydrated and more receptive to hydrophobic molecules. The Cs-saponite manifested a sorption of more than 1% atrazine by weight above equilibrium concentrations of 6 mg\\/L, which to our

Vaneet Aggarwal; Hui Li; Brian J. Teppen

2006-01-01

46

Environmental applications of radiation-induced defects in clay minerals  

NASA Astrophysics Data System (ADS)

Radiation effects on clay minerals have been studied over the last 35 years, providing a wealth of information on environmental and geological processes. They have been applied to the reconstruction of past radioelement migrations in the geosphere, the dating of clay minerals from soils or the evolution of the physico-chemical properties under irradiation. All known radiation-induced point defects in clay minerals are detected using Electron Paramagnetic Resonance Spectroscopy. They mostly consist in electron holes located on oxygen atoms of the structure, and can be differentiated through their nature and their thermal stability. For instance, several are associated to a ? orbital on a Si-O bond. One defect, namely the A-center, is stable over geological periods at ambiant temperature. These point defects are produced mainly by ionizing radiations. By contrast to point defects, it was shown that electron or heavy ion irradiation easily produces amorphization in smectites. Two main applications of radiation-induced defects in clay minerals are derived : (i) the use of defects as tracers of past radioactivity. In geosystems where the age of the clay can be constrained, migrations of radioelements can be reconstructed in natural analogues of the far field of high level nuclear waste repositories. When the dose rate may be assumed constant over time, the paleodose is used to date clay populations, an approach applied to laterites of the Amazon basin. (ii) The influence of radiation on clay mineral properties that remains poorly documented, although it is an important issue in various domains such as the safety assessment of the high level nuclear waste repositories. In case of a leakage of transuranic elements from the radioactive wasteform, alpha recoil nuclei would amorphize smectite after a period much lower than the disposal lifetime. By contrast, amorphisation from ionizing radiation is unlikely over 1 million years. Furthermore, it was shown that amorphization greatly enhances the dissolution kinetics of smectite, a result that must be taken into account in the safety assessment of engineered barriers.

Allard, T.

2011-12-01

47

Organic Complexing in Smectite Clay Minerals Under Hydrothermal Vent Conditions  

NASA Astrophysics Data System (ADS)

A hydrothermal vent at the Juan de Fuca ridge was found to contain smectite-rich clay minerals. At vent fluid temperatures (300-350°C) smectite quickly reacts to form more stable minerals, such as illite or chlorite, by incorporating metal cations. While similar investigations have assigned the catalytic properties of clays strictly to the surfaces, it is our hypothesis that organic molecules are polymerized in the smectite interlayers during reaction. Upon incorporation of metal cations and primary organic molecules in the expandable interlayer of these clays, gradual changes in the electrochemical environment may catalyze bio-oligomers that are essential components of life. For comparison, we have examined both dioctahedral (montmorillonite; SWy-1) and trioctahedral (saponite) smectite clay minerals which react to illite and chlorite, respectively. An illite standard (IMt-1) has also been examined as a catalyst. Progressive steps in the reaction process have been monitored through hydrothermal experimentation simulating seafloor and subseafloor volcanic conditions in welded gold capsules. K-saturated smectite clays were reacted with aqueous 10 M methanol solutions up to six weeks. Reaction progress was monitored weekly. Results suggest that organic complexity increases as a function of mineralogical reaction. While producing some similar complex organic compounds, reactions starting with illite yielded significantly lower product concentrations than those with the smectites, suggesting the expandable interlayers play an important role in catalysis. Organic analyses were performed by GC-MS; clay analyses by x-ray diffraction.

Canfield, B. M.; Williams, L. B.; Holloway, J. R.

2002-12-01

48

Sorption of Metal Ions on Clay Minerals.  

PubMed

The mechanism of Co uptake from aqueous solution onto hectorite (a magnesian smectite) and its impact on the stability of this clay mineral were investigated as a function of Co concentration (TotCo = 20 to 200 µM, 0.3 M NaNO(3)) and ionic strength (0.3 and 0.01 M NaNO(3), TotCo = 100 µM) by combining kinetics measurements and Co K-edge extended X-ray absorption fine structure (EXAFS) spectroscopy. The morphology of the sorbent phase was characterized by atomic force microscopy (AFM) and consists of lath-type particles bounded by large basal planes and layer edges. At low ionic strength (0.01 M NaNO(3)), important Co uptake occurred within the first 5 min of reaction, consistent with Co adsorption on exchange sites of hectorite basal planes. Thereafter, the sorption rate dramatically decreased. In contrast, at high ionic strength (0.3 M NaNO(3)), Co uptake rate was much slower within the first 5 min and afterward higher than at 0.01 M NaNO(3), consistent with Co adsorption on specific surface sites located on the edges of hectorite. Time-dependent isotherms for Co uptake at high ionic strength indicated the existence of several sorption mechanisms having distinct equilibration times. The dissolution of hectorite was monitored before and after Co addition. A congruent dissolution regime was observed prior to Co addition. Just after Co addition, an excess release of Mg relatively to congruent dissolution rates occurred at both high and low ionic strengths. At high ionic strength, this excess release nearly equaled the amount of sorbed Co. The dissolution rate of hectorite then decreased at longer Co sorption times. EXAFS spectra of hectorite reacted with Co at high and low ionic strengths and for reaction times longer than 6 h, exhibited similar features, suggesting that the local structural environments of Co atoms are similar. Spectral simulations revealed the occurrence of approximately 2 Mg and approximately 2 Si neighboring cations at interatomic distances characteristic of edge-sharing linkages between Co and Mg octahedra and corner-sharing linkages between Co octahedra and Si tetrahedra, respectively. This local structure is characteristic of inner sphere mononuclear surface complexes at layer edges of hectorite platelets. The occurrence of these complexes even at low ionic strength apparently conflicts with kinetics results, as exchangeable divalent cations are known to form outer sphere surface complexes. To clarify this issue, the amount of Co adsorbed on exchange sites was calculated from the solute Co concentration, assuming that cation exchange was always at equilibrium. These calculations showed that sorbed Co was transferred within 48 h from exchange sites to edge sorption sites. Copyright 1999 Academic Press. PMID:10607458

Schlegel; Charlet; Manceau

1999-12-15

49

Enchanted Clays: 44th Annual Meeting of the Clay Minerals Society (June 2007)  

SciTech Connect

“Enchanted Clays: 44th Annual Meeting of the Clay Minerals Society” was held in early June 2007 in beautiful and historic Santa Fe, New Mexico, USA. Santa Fe provided an idyllic location in the southwestern United States for the attendees to enjoy technical and social sessions while soaking up the diverse culture and wonderful climate of New Mexico—The Land of Enchantment. The meeting included a large and varied group of scientists, sharing knowledge and ideas, benefitting from technical interactions, and enjoying the wonderful historic and enchanted environs of Santa Fe. Including significant number of international scientists, the meeting was attended by approximately two hundred participants. The meeting included three days of technical sessions (oral and poster presentations), three days of field trips to clay and geological sites of northern New Mexico, and a full day workshop on the stabilization of carbon by clays. Details can be found at the meeting web site: www.sandia.gov/clay.

Randall T. Cygan

2007-06-01

50

Geothermal Alteration of Clay Minerals and Shales: Diagenesis.  

National Technical Information Service (NTIS)

The objective of this report is to perform a critical review of the data on the mineral and chemical alterations that occur during diagenesis and low-grade metamorphism of shale and other clay-rich rocks - conditions similar to those expected from emplace...

C. E. Weaver

1979-01-01

51

Picloram and Aminopyralid Sorption to Soil and Clay Minerals  

Technology Transfer Automated Retrieval System (TEKTRAN)

Aminopyralid sorption data are lacking, and these data are needed to predict off-target transport and plant available herbicide in soil solution. The objective of this research was to determine the sorption of picloram and aminopyralid to five soils and three clay minerals and determine if the pote...

52

X-Ray Diffraction Identification of Clay Minerals by Microcomputer.  

National Technical Information Service (NTIS)

The identification of clay minerals by X-ray powder diffraction are done by searching an unknown pattern with a file of standard X-ray diffraction patterns. For this searching done by hand is necessary a long time. This paper shows a program in ''Basic'' ...

S. Rodrigues F. J. Imasava

1988-01-01

53

Clay minerals as selective and shape-selective sorbents  

Microsoft Academic Search

An account has been given of four modes of sorption based on clay minerals and their cation exchanged and pillared forms. non-polar molecules on outgassed layer s tructures containing only inorganic interlayer cations such as Na+ or Ca2+ is confined to external surfaces only. palygorskites. layer structures, but only after a threshold pressure is exceeded. thermodynamic basis of this behaviour

R. M. Barrer

1989-01-01

54

Effects of Clay Mineral Type and Organic Matter on the Uptake of Radiocesium by Pasture Plants.  

National Technical Information Service (NTIS)

Studies were undertaken to examine the influence of interaction of clay minerals and organic matter on the uptake of radiocesium by two pasture plants, namely, ryegrass (Lolium italicum L) and red clover (Trifolium pratense L). The clay minerals used were...

T. J. D'Souza E. Fagniart R. Kirchmann

1980-01-01

55

Oxygen and hydrogen isotope compositions in clay minerals: A potential single-mineral geothermometer  

Microsoft Academic Search

The opposite slopes of the isotopic fractionation of hydrogen and oxygen in the clay-water system and the well-known relationship between ?D and ?18O in meteoric waters allow the isotopic composition of clay minerals to be used as a “single-mineral” geothermometer. Equations can be derived which are valid for continental systems where meteoric waters are common. The following equation was derived

Antonio Delgado; Emilio Reyes

1996-01-01

56

Microbial dissolution of clay minerals as a source of iron and silica in marine sediments  

NASA Astrophysics Data System (ADS)

Interactions between microbes and minerals have the potential to contribute significantly to the global cycles of various elements, and serve as a link between the geosphere and life. In particular, the microbially mediated cycle of iron within marine sediments is closely tied to the carbon cycle. The dissolved iron that serves as a nutrient is thought to be primarily drawn from well-known pools of highly reactive, bioavailable iron and iron complexes. Iron contained within the crystal lattice of clay minerals, the most abundant materials found at the Earth's surface, is not thought to be part of this pool. Here we analyse the mineral composition of Middle-Cambrian-aged mudstones from the western United States. We find intergrown mineral aggregates of quartz, pyrite and calcite. On the basis of mineral phase relationships and temperatures of crystallization derived from stable isotopes of oxygen, we infer that mineral dissolution driven by microbes released iron and silica to the surrounding sediment pore waters, and led to the subsequent precipitation of the observed minerals. The microbial extraction of structurally coordinated Fe3+ from clay minerals after their deposition in marine sediments may liberate a fraction of iron previously considered unavailable, and may be important in iron and silica cycling in marine sediments.

Vorhies, John S.; Gaines, Robert R.

2009-02-01

57

Reactivity of clay minerals with acids and alkalies  

USGS Publications Warehouse

One-g samples of a montmorillonite, a metabentonite, an illite, two kaolinites, and three halloysites were treated with 50 ml of hydrochloric acid (6??45 N, 1:1), acetic acid (4??5 N, 1:3), sodium hydroxide (2??8 N), sodium chloride solution (pH 6??10; Na = 35???; Cl = 21??5???), and natural sea water (pH 7??85; Na = 35??5???; Cl = 21??5???) for a 10-day period in stoppered plastic vials. The supernatant solutions were removed from the clay minerals and analyzed for SiO2, Al2O3, CaO, MgO, Na2O, and K2O. All the solutions removed some SiO2, Al2O3, and Fe2O3 from the samples, but the quantities were small. Sodium hydroxide attacked the kaolin group minerals more strongly than it did montmorillonite, metabentonite, or illite. Halloysite was more strongly attacked by hydrochloric acid than was any of the other experimental minerals. Hydrochloric acid removed iron oxide coatings from soil clay minerals, but acetic acid did not remove them completely. The samples most strongly attacked by HCl and NaOH were examined by X-ray diffraction. Acid treatment did not destroy the structure of the clays, but the halloysite structure was partially destroyed. Sodium hydroxide attacked the halloysite structure, as shown by chemical analysis and X-ray diffraction. These experiments show that treatment in dilute acids has no harmful effect in the preparation of clays for X-ray diffraction. Acetic acid is preferred to hydrochloric acid for this purpose. Hydrochloric acid cleans clay minerals by removing free iron oxide from the surface; acetic acid is less effective. ?? 1971.

Carroll, D.; Starkey, H. C.

1971-01-01

58

Extracellular enzyme-clay mineral complexes: Enzyme adsorption, alteration of enzyme activity, and protection from photodegradation  

Microsoft Academic Search

Enzymes released extracellularly by micro-organisms have major functions in nutrient acquisition and organic matter degradation. Clay particles, common in many surface waters, can modify enzyme activity. Clay minerals are known to form aggregates with organic molecules, and the formation of enzyme-clay complexes could alter the level of activity. Montmorillonite clay and clay extracted from Elledge Lake (Tuscaloosa, Alabama) basin soil

Todd Tietjen; Robert G. Wetzel

2003-01-01

59

Heavy oil components sorbed onto clay minerals in Canadian oil sands  

Microsoft Academic Search

In siliciclastic reservoir rocks the surface-active clay minerals are presumed to be predominantly responsible for the sorption of polar oil components. In order to achieve a better insight into the nature of the oil components sorbed onto clay minerals, unconsolidated Canadian Oil Sands (Cold Lake, Athabasca) were exhaustively extracted with dichloromethane to remove the free oil. The clay minerals (grain

A. Fendel; K. Schwochau

1988-01-01

60

The Effect of Mechanochemical Treatments on Clay Minerals and the Mechanochemical Adsorption of Organic Materials onto Clay Minerals  

Microsoft Academic Search

The present paper reviews investigations on the mechanochemical reactions occurring during the grinding of kaolinite and the mechanochemical adsorption of polar organic compounds by expanding and nonexpanding clay minerals, carried out in our laboratory by IR spectroscopy, supplemented by XRD and TG-DTA techniques. Kaolinite was ground in the absence and presence of diluents (alkali halides) and IR spectra were recorded

S. Yariv; I. Lapides

2000-01-01

61

Sorption of Metal Ions on Clay Minerals.  

PubMed

The local structural environment of Co sorbed on hectorite (a magnesian smectite) has been investigated by polarized EXAFS (P-EXAFS) spectroscopy on a self-supporting film of Co-sorbed hectorite. This sorption sample was prepared by contacting Co and hectorite at pH 6.5 and at high ionic strength (0.3 M NaNO3) to favor pH-dependent sorption reaction over cation exchange. A self-supporting film was elaborated after 120 h of reacting time, when apparent quasi-equilibrium conditions were attained. The half-width at half maximum of the orientation distribution of c* axis of individual clay platelets off the film normal was determined by quantitative texture analysis, and found to be equal to 18.9 degrees. Co K-edge P-EXAFS spectra were recorded at angles between the incident beam and the film normal equal to 0 degrees, 35 degrees, 50 degrees, and 60 degrees; the 90 degrees spectrum was obtained by extrapolation. Spectral analysis led to the identification of the two nearest cationic subshells containing 1.6 +/- 0.4 Mg at 3.03 Å and 2.2 +/- 0.5 Si at 3.27 Å. These distances are respectively characteristic of edge-sharing linkages between Mg and Co octahedra and of corner-sharing linkages between Co octahedra and Si tetrahedra, as in clay structures. The angular dependence of the Co-Mg and Co-Si contributions indicates that Co-Mg pairs are oriented parallel to the film plane, whereas Co-Si pairs are not. These results are interpreted by the formation of Co inner-sphere mononuclear surface complexes located at the edges of hectorite platelets, in the continuity of the (Mg, Li) octahedral sheet. Copyright 1999 Academic Press. PMID:10362483

Schlegel; Manceau; Chateigner; Charlet

1999-07-01

62

Water molecules in clay minerals: Thermodynamic functions and hydration  

NASA Astrophysics Data System (ADS)

Thermodynamic functions and adsorption of water molecules are very important properties for clay minerals. Smectite MX-80 and mixed-layer illite-smectite ISCz-1 were selected. They were first carefully characterized (HRTEM with EDX analysis), revealing original results. Then, the thermodynamic properties of water in clay were obtained by (i) comparison of the thermodynamic properties of anhydrous and hydrated minerals, between 0 and 350 K (adiabatic calorimetry, solution isothermal calorimetry), and (ii) water vapor adsorption isotherms, between 300 and 380 K (magnetic suspension thermobalance). Solution isothermal calorimetry is used to determine the enthalpies of formation of the minerals (1 bar and 298 K). Comparison of the results, for the anhydrous and the hydrated minerals, leads to the enthalpies of hydration at 298 K. Adiabatic calorimetry measurements give the heat capacities of the minerals from 5 to 350 K. Entropies, enthalpies of formation and Gibbs free energies of formation, for the anhydrous and the hydrated minerals, and then, entropies of hydration, enthalpies of hydration and Gibbs free energies of hydration, between 0 and 350 K, are finally obtained. Comparison of two close hydration states leads to the entropy, the enthalpy and the Gibbs free energy of the adsorption reaction: H2O free - H2O adsorbed. The Cp(T) curve, for the heat capacity of water in clay - i.e., the difference between the heat capacities of the hydrated and the anhydrous minerals -, shows that water in clay is a glass at low temperature, undergoes one or two continuous glass transitions between 150 and 270 K, and behaves as free liquid water above 273 K. The two glass transitions might correspond to two types of water molecules: (i) first adsorbed water molecules, bound to the interlayer cations of the clay mineral; (ii) last adsorbed water molecules, not bound to the interlayer cations. In addition, water vapor adsorption isotherms are obtained from 298 to 378 K (magnetic suspension thermobalance) and well fitted with a BET type model (with three layers of adsorbed water molecules). The Gibbs free energy of the adsorption reaction and the Gibbs free energy of hydration, for any hydration state, can be determined. They are in agreement with the above calorimetric values. Gailhanou H., van Miltenburg J.C., Rogez J., Olives J., Amouric M., Gaucher E.C., Blanc P. (2007).Thermodynamic properties of anhydrous smectite, illite and illite-smectite. (Part 1) Geochim Cosmochim. Acta 71, 5463-5473.

Gailhanou, Helène; Amouric, Marc; Olives, Juan; Rogez, Jacques; van Miltenburg, J. C.; van der Berg, G. J. K.; de Weireld, G.; Gaucher, E.; Blanc, P.

2010-05-01

63

Sorption of tylosin on clay minerals.  

PubMed

The equilibrium sorption of tylosin (TYL) on kaolinite and montmorillonite was measured at different solution pH using batch reactor systems. The results showed that all the sorption isotherms were nonlinear and that the nonlinearity decreased as the solution pH increased for a given clay. At a specific aqueous concentration, the single-point sorption distribution coefficient (KD) of TYL decreased rapidly as the solution pH increased. A speciation-dependent sorption model that accounted for the contributions of the cationic and neutral forms of TYL fit the data well, suggesting that the sorption may be dominated by both ion exchange and hydrophobic interactions. The isotherm data also fit well to a dual mode model that quantifies the contributions of a site-limiting Langmuir component (ion exchange) and a non-specific linear partitioning component (hydrophobic interactions). X-ray diffraction analyses revealed that the interlayers of montmorillonite were expanded due to the uptake of TYL. TYL molecules likely form a monolayer surface coverage. PMID:24007614

Zhang, Qian; Yang, Chen; Huang, Weilin; Dang, Zhi; Shu, Xiaohua

2013-09-02

64

Ice nucleation efficiency of clay minerals in the immersion mode  

NASA Astrophysics Data System (ADS)

Emulsion and bulk freezing experiments were performed to investigate immersion ice nucleation on clay minerals in pure water, using various kaolinites, montmorillonites, illites as well as natural dust from the Hoggar Mountains in the Saharan region. Differential scanning calorimeter measurements were performed on three different kaolinites (KGa-1b, KGa-2 and K-SA), two illites (Illite NX and Illite SE) and four natural and acid-treated montmorillonites (SWy-2, STx-1b, KSF and K-10). The emulsion experiments provide information on the average freezing behaviour characterized by the average nucleation sites. These experiments revealed one to sometimes two distinct heterogeneous freezing peaks, which suggest the presence of a low number of qualitatively distinct average nucleation site classes. We refer to the peak at the lowest temperature as "standard peak" and to the one occurring in only some clay mineral types at higher temperatures as "special peak". Conversely, freezing in bulk samples is not initiated by the average nucleation sites, but by a very low number of "best sites". The kaolinites and montmorillonites showed quite narrow standard peaks with onset temperatures 238 Kclay minerals strongly depend on the amount of clay mineral present per droplet and on the exact type (location of collection and pre-treatment) of the clay mineral. We suggest that apparently contradictory results obtained by different groups with different setups are indeed in good agreement when only clay minerals of the same type and amount per droplet are compared. The natural sample from the Hoggar Mountains, a region whose dusts have been shown to be composed mainly of illite, showed very similar freezing characteristics (standard and best) to the illites. Relating the concentration of best IN to the dust concentration in the atmosphere suggested that the best IN in the Hoggar sample would be common enough downwind of their source region to account for ambient IN number densities in the temperature range of 250-260 K at least during dust events.

Pinti, V.; Marcolli, C.; Zobrist, B.; Hoyle, C. R.; Peter, T.

2012-07-01

65

Reactivity of Fe(II) species associated with clay minerals.  

PubMed

Mineral-bound Fe(II) species represent important natural reductants of pollutants in the anaerobic subsurface. At clay minerals, three types of Fe(II) species in fundamentally different chemical environments may be present simultaneously, i.e., structural Fe(II), Fe(II) complexed by surface hydroxyl groups, and Fe(II) bound by ion exchange. We investigated the accessibility and reactivity of these three types of Fe(II) species in suspensions of two different clay minerals containing either ferrous iron-bearing nontronite or iron-free hectorite. Nitroaromatic compounds (NACs) exhibiting different sorption behavior on clays were used to probe the reactivity of the various types of reduced iron species. The clay treatment allowed for a preparation of nontronite and hectorite surfaces with Fe(II) adsorbed by surface hydroxyl groups at the edge surfaces. Furthermore, hectorite suspensions with additional Fe(II) bound to the ion exchange sites at the basal siloxane surfaces were set up. We found that both structural Fe(II) and Fe(II) complexed by surface hydroxyl groups of nontronite reduced the NACs to anilines. An electron balance revealed that more than 10% of the total iron in nontronite was reactive Fe(II). Fe(II) bound by ion exchange did not contribute to the observed reduction of NACs. Reversible adsorption of the NACs at the basal siloxane surface of the clays strongly retarded NAC reduction, even in the presence of high concentrations of Fe(II) bound by ion exchange to the basal siloxane surfaces. Our work shows that in natural systems a fraction of the total Fe(II) present on clays may contribute to the pool of highly reactive Fe(II) species in the subsurface. Furthermore, this work may help to distinguish between Fe(II) species of different reactivity regarding pollutant reduction. Although structural iron in clays represents only a small fraction of the total iron pool in soils and aquifers, reactive Fe(II) species originating from the reduction of structural Fe(III) in clays may contribute significantly to the biogeochemical cycling of electrons in the subsurface since it is not subject to depletion by reductive dissolution. PMID:12630467

Hofstetter, Thomas B; Schwarzenbach, René P; Haderlein, Stefan B

2003-02-01

66

Modeling of Cation Binding in Hydrated 2:1 Clay Minerals  

SciTech Connect

The primary objective of our research is the development of molecular models of ion exchange on clay minerals with a view toward understanding the mechanisms of radionuclide transport through clay-rich soils. Specific scientific goals include using molecular computer simulations to calculate the thermodynamics of clay swelling and ion exchange, and to evaluate the dependence of clay properties upon interlayer ion identity and clay composition. These goals will, in general, facilitate the development structure function relationships in clays.

Smith, David E.

1999-06-01

67

Bioreduction of Fe-bearing clay minerals and their reactivity toward pertechnetate (Tc-99)  

NASA Astrophysics Data System (ADS)

99Technetium ( 99Tc) is a fission product of uranium-235 and plutonium-239 and poses a high environmental hazard due to its long half-life ( t1/2 = 2.13 × 10 5 y), abundance in nuclear wastes, and environmental mobility under oxidizing conditions [i.e., Tc(VII)]. Under reducing conditions, Tc(VII) can be reduced to insoluble Tc(IV). Ferrous iron, either in aqueous form (Fe 2+) or in mineral form [Fe(II)], has been used to reduce Tc(VII) to Tc(IV). However, the reactivity of Fe(II) from clay minerals, other than nontronite, toward immobilization of Tc(VII) and its role in retention of reduced Tc(IV) has not been investigated. In this study the reactivity of a suite of clay minerals toward Tc(VII) reduction and immobilization was evaluated. The clay minerals chosen for this study included five members in the smectite-illite (S-I) series, (montmorillonite, nontronite, rectorite, mixed layered I-S, and illite), chlorite, and palygorskite. Surface Fe-oxides were removed from these minerals with a modified dithionite-citrate-bicarbonate (DCB) procedure. The total structural Fe content of these clay minerals, after surface Fe-oxide removal, ranged from 0.7% to 30.4% by weight, and the structural Fe(III)/Fe(total) ratio ranged from 45% to 98%. X-ray diffraction (XRD) and Mössbauer spectroscopy results showed that after Fe oxide removal the clay minerals were free of Fe-oxides. Scanning electron microscopy (SEM) revealed that little dissolution occurred during the DCB treatment. Bioreduction experiments were performed in bicarbonate buffer (pH-7) with structural Fe(III) in the clay minerals as the sole electron acceptor, lactate as the sole electron donor, and Shewanella putrefaciens CN32 cells as a mediator. In select tubes, anthraquinone-2,6-disulfate (AQDS) was added as electron shuttle to facilitate electron transfer. In the S-I series, smectite (montmorillonite) was the most reducible (18% and 41% without and with AQDS, respectively) and illite the least (1% for both without and with AQDS). The extent and initial rate of bioreduction were positively correlated with the percent smectite in the S-I series (i.e., layer expandability). Fe(II) in the bioreduced clay minerals subsequently was used to reduce Tc(VII) to Tc(IV) in PIPES buffer. Similar to the trend of bioreduction, in the S-I series, reduced NAu-2 showed the highest reactivity toward Tc(VII), and reduced illite exhibited the least. The initial rate of Tc(VII) reduction, after normalization to clay and Fe(II) concentrations, was positively correlated with the percent smectite in the S-I series. Fe(II) in chlorite and palygorskite was also reactive toward Tc(VII) reduction. These data demonstrate that crystal chemical parameters (layer expandability, Fe and Fe(II) contents, and surface area, etc.) play important roles in controlling the extent and rate of bioreduction and the reactivity toward Tc(VII) reduction. Reduced Tc(IV) resides within clay mineral matrix, and this association could minimize any potential of reoxidation over long term.

Bishop, Michael E.; Dong, Hailiang; Kukkadapu, Ravi K.; Liu, Chongxuan; Edelmann, Richard E.

2011-09-01

68

Bioreduction of Fe-bearing clay minerals and their reactivity toward pertechnetate (Tc-99)  

SciTech Connect

99Technetium (99Tc) is a fission product of uranium-235 and plutonium-239 and poses a high environmental hazard due to its long half-life (t1/2 = 2.13 x 105 y), abundance in nuclear wastes, and environmental mobility under oxidizing conditions [i.e., Tc(VII)]. Under reducing conditions, Tc(VII) can be reduced to insoluble Tc(IV). Ferrous iron [Fe(II)], either in aqueous form or in mineral form, has been used to reduce Tc(VII) to Tc(IV). However, the reactivity of Fe(II) from clay minerals, other than nontronite, toward immobilization of Tc(VII) and its role in retention of reduced Tc(IV) have not been investigated. In this study the reactivity of a suite of clay minerals toward Tc(VII) reduction and immobilization was evaluated. The clay minerals chosen for this study included five members in the smectite-illite (S-I) series, (montmorillonite, nontronite, rectorite, mixed layered I-S, and illite), chlorite, and palygorskite. Fe-oxides were removed from these minerals with a modified dithionite-citrate-bicarbonate (DCB) procedure. The total Fe content of these clay minerals, after Fe-oxide removal, ranged from 0.7 to 30.4% by weight, and the Fe(III)/Fe(total) ratio ranged from 44.9 to 98.5%. X-ray diffraction (XRD) and Mössbauer spectroscopy results showed that after Fe oxide removal the clay minerals were free of Fe-oxides. Scanning electron microscopy (SEM) revealed that little dissolution occurred during the DCB treatment. Bioreduction experiments were performed in bicarbonate buffer (pH-7) with Fe(III) in the clay minerals as the sole electron acceptor, lactate as the sole electron donor, and Shewanella Putrifaciens CN32 cells as mediators. In select tubes, anthraquinone-2,6-disulfate (AQDS) was added as electron shuttle to facilitate electron transfer. The extent of Fe(III) bioreduction was the highest for chlorite (~43 wt%) and the lowest for palygorskite (~4.17 wt%). In the S-I series, NAu-2 was the most reducible (~31 %) and illite the least (~0.4 %). The extent and initial rate of bioreduction were positively correlated with the percent smectite in the S-I series (i.e., layer expandability). Fe(II) in the bioreduced clay minerals subsequently was used to reduce Tc(VII) to Tc(IV) in PIPES buffer. Similar to the trend of bioreduction, in the S-I series, reduced smectite showed the highest reactivity toward Tc(VII), and reduced illite exhibited the least. The initial rate of Tc(VII) reduction, after normalization to clay and Fe(II) concentrations, was positively correlated with the percent smectite in the S-I series. Fe(II) in chlorite and palygorskite was also reactive toward Tc(VII) reduction. These data demonstrate that crystal chemical parameters (layer expandability, Fe and Fe(II) contents, and surface area etc.) play important roles in controlling the extent and rate of bioreduction and the reactivity toward Tc(VII) reduction. Reduced Tc(IV) resides within clay mineral matrix, and this association could minimize any potential of reoxidation over long term.

Bishop, Michael E.; Dong, Hailiang; Kukkadapu, Ravi K.; Liu, Chongxuan; Edelmann, Richard E.

2011-07-01

69

Clay mineral distribution in surface sediments of the South Atlantic: sources, transport, and relation to oceanography  

Microsoft Academic Search

Surface samples, mostly from abyssal sediments of the South Atlantic, from parts of the equatorial Atlantic, and of the Antarctic Ocean, were investigated for clay content and clay mineral composition. Maps of relative clay mineral content were compiled, which improve previous maps by showing more details, especially at high latitudes. Large-scale relations regarding the origin and transport paths of detrital

Rainer Petschick; Gerhard Kuhn; Franz Gingele

1996-01-01

70

The impact of structural Fe(III) reduction by bacteria on the surface chemistry of smectite clay minerals  

SciTech Connect

Although clay mineral reduction is thought to occur primarily as a result of the activity of indigenous microorganisms in soil, most research has focused on chemical mechanisms of Fe reduction within clay minerals. Here the authors show that bacteria isolated from soils and sediments catalyze the rapid reduction of structural Fe(III) in the smectite clay minerals. The extent of Fe(III) reduction is large, from 46% to {gt}90%. Furthermore, the effects of structural Fe(III) reduction by bacteria on the surface chemistry of smectites are dramatic. Swelling pressure, as measured by water content, was shown to decrease by 40% to 44% in smectites reduced by bacteria as compared to unaltered or reoxidized smectites. particle surface area decreased by 26% to 46% in response to bacterial reduction, and the surface charge density as measured by the ratio of cation exchange capacity to specific surface area increased over the same scale. Measurements of swelling pressure in smectite saturated with the organic cation trimethylphenylammonium (TMPA) indicated that the hydrophilic character of the clay mineral surface was enhanced upon reduction. The valence state of Fe in the octahedral layer of smectite, as revealed through reflectance spectra, correlated to the amount of Fe(III) reduced in bacterial cultures, providing information on the mechanism of intervalence electron transfer in bacterially reduced clay minerals. The extent of reduction and surface chemical effects catalyzed by bacteria in this study are similar in magnitude to those observed previously for potent inorganic reductants. Given that clay minerals dominate the solid phase of porous media and that Fe(III)-reducing bacteria are abundant in solid and aquatic sediments, these data suggest that bacterial clay mineral reduction may play an important role in soil biogeochemistry, affecting processes such as nutrient cycles and the fate of organic contaminants.

Kostka, J.E.; Wu, J.; Nealson, K.H.; Stucki, J.W.

1999-11-01

71

Adsorption and separation of proteins by a smectitic clay mineral.  

PubMed

The adsorption of proteins by a smectitic clay mineral was investigated. The clay used in this study is a mixture of montmorillonite and amorphous SiO(2). Due to the high porosity the montmorillonite units are accessible for protein adsorption. The amorphous silica prevents the montmorillonite from swelling and allows column packing. Protein adsorption was performed at different pH under static conditions. Furthermore, static capacities were determined. The material reveals high adsorption capacities for proteins under static conditions (270-408 mg/g), whereby proteins are mainly adsorbed via electrostatic interactions. The Freundlich isotherm is suggested as an adsorption model. For desorption a pH shift was found to be most effective. Binding and elution of human serum albumin and ovalbumin were tested under dynamic conditions. Dynamic capacities of about 40 mg/g for ovalbumin at 764 cm/h were found. The clay mineral provides suitable properties for the application as cost-efficient, alternative separation material. PMID:20340034

Ralla, Kathrin; Sohling, Ulrich; Riechers, Daniel; Kasper, Cornelia; Ruf, Friedrich; Scheper, Thomas

2010-03-26

72

Report on "Methodologies for Investigating Microbial-Mineral Interactions: A Clay Minerals Society Short Course"  

SciTech Connect

A workshop entitled, “Methods of Investigating Microbial-Mineral Interactions,” was held at the Clay Minerals Society meeting at the Pacific Northwest National Laboratory in Richland, WA on June 19, 2004. The workshop was organized by Patricia A. Maurice (University of Notre Dame) and Lesley A. Warren (McMaster University, CA). Speakers included: Dr. P. Bennett, Dr. J. Fredrickson (PNNL), Dr. S. Lower (Ohio State University), Dr. P. Maurice, Dr. S. Myneni (Princeton University), Dr. E. Shock (Arizona State), Dr. M. Tien (Penn State), Dr. L. Warren, and Dr. J. Zachara (PNNL). There were approximately 75 attendees at the workshop, including more than 20 students. A workshop volume was published by the Clay Minerals Society [Methods for Study of Microbe-Mineral Interactions (2006), CMS Workshop Lectures, vol. 14?(Patricia A. Maurice and Leslie A. Warren, eds.) ISBN 978-1-881208-15-0, 166 pp.

Patricia A. Maurice

2010-02-08

73

Towards an understanding of the role of clay minerals in crude oil formation, migration and accumulation  

NASA Astrophysics Data System (ADS)

This article reviews progress in the understanding of the role of clay minerals in crude oil formation, migration and accumulation. Clay minerals are involved in the formation of kerogen, catalytic cracking of kerogen into petroleum hydrocarbon, the migration of crude oil, and the continued change to hydrocarbon composition in underground petroleum reservoirs. In kerogen formation, clay minerals act as catalysts and sorbents to immobilize organic matter through ligand exchange, hydrophobic interactions and cation bridges by the mechanisms of Maillard reactions, polyphenol theory, selective preservation and sorptive protection. Clay minerals also serve as catalysts in acid-catalyzed cracking of kerogen into petroleum hydrocarbon through Lewis and Brønsted acid sites on the clay surface. The amount and type of clay mineral affect the composition of the petroleum. Brønsted acidity of clay minerals is affected by the presence and state of interlayer water, and displacement of this water is a probable driver in crude oil migration from source rocks. During crude oil migration and accumulation in reservoirs, the composition of petroleum is continually modified by interaction with clay minerals. The clays continue to function as sorbents and catalysts even while they are being transformed by diagenetic processes. The detail of chemical interactions and reaction mechanisms between clay minerals and crude oil formation remains to be fully explained but promises to provide insights with broader application, including catalytic conversion of biomass as a source of sustainable energy into the future.

Wu, Lin Mei; Zhou, Chun Hui; Keeling, John; Tong, Dong Shen; Yu, Wei Hua

2012-12-01

74

The role of clay minerals and alumina-treated clay minerals in hydrogenation and pyrolysis of solvent-refined coal  

SciTech Connect

The hydrogenation and pyrolysis behaviour of solvent-refined coal (SRC) and base-free SRC have been investigated in the presence and absence of clay minerals and alumina-modified clay minerals. The yields of chloroform-soluble and insoluble products (coke) and aromaticities of chloroform-insoluble products have been measured to elucidate the mechanisms of these processes. The yield of chloroform-soluble products was greater after pyrolysis under molecular hydrogen than under molecular nitrogen, even though there was no decrease in the aromaticity of the products in either case. Hence hydrogen can assist in the formation of chloroform-soluble products without aryl ring hydrogenation. Higher yields of chloroform-soluble products were obtained with base-free SRC than with SRC but little or no effect of mineral matter was observed. It is suggested that SRC bases play an important and direct role in promoting in situ coking reactions apart from their well-established role in blocking acidic cracking sites.

Vassallo, A.M.; McCarthy, S.A.; Wilson, M.A.; Palmisano, A.J. (CSIRO Div. of Coal Technology, P.O. Box 136, North Ryde, N.S.W. 2113 (AU)); Campbell, A.S. (Dept. of Soil Science, Lincoln College, Canterbury (NZ))

1989-01-01

75

Li isotope compositions of clay minerals: what message?  

NASA Astrophysics Data System (ADS)

Alteration of the continental crust plays a major role in the transfer of elements to natural waters and the ocean. In particular, it is thought that alteration of Ca and Mg rich silicates participated to climate regulation through the Earth history. However, determining reliably the intensity and the rate of silicate weathering at the scale of an ecosystem, or at the scale of a watershed and of continents remains a challenge. Recently, lithium isotope composition of river dissolved and solid phases have shown great potential: delta7Li of natural waters are generally function of the weathering regime, as it has been shown for several watersheds. This is because Li uptake by secondary phases plays a key role (in contrast, simple dissolution does not significantly fractionate Li isotopes1). Consequently, Li isotope composition of clays could give quantitative information about their formation condition and contemporaneous environmental parameters. In this purpose, Li isotope signatures of clays were investigated in two ways: experimentally, by developing clay syntheses in various conditions (temperature, solution chemical composition)2,3, and by studying monitored natural ecosytems, for which primary and secondary minerals have been well-characterized, quantified and, when possible, separated. Results of these works show that (1) Li isotope fractionations display a coherent correlation as a function of temperature (from 25°C to 250°C). Recent work allowed us to improve the synthesis performed at low temperature (< 90°C). (2) In contrast, the exchangeable lithium, located mainly in the interfoliar sites, is not significantly fractionated (isotopically). (3) the type of clays or their chemical composition does not significantly influence the fractionation factors (4) In parallel, experimental investigations show that the Li partition coefficients between smectite and solution are a function of temperature and of Li content in waters3. (5) the relative amount of exchangeable Li is negligible for the studied natural clays (>1%) In this presentation, we will highlight the potential of clay Li contents and Li isotopic compositions to be used as geothermometers, or as tracers of rock-water interactions both on the continents at low temperature, and in the ocean under hydrothermal conditions. 1 Verney-Carron et al. (2011) GCA 7. 2 Vigier et al. (2008) GCA 72. 3 Decarreau et al., GCA, major revision.

Vigier, N.; Decarreau, A.; Petit, S.; Turpault, M.

2011-12-01

76

Cambrian burgess shale animals replicated in clay minerals  

PubMed

Although the evolutionary importance of the Burgess Shale is universally acknowledged, there is disagreement on the mode of preservation of the fossils after burial. Elemental mapping demonstrates that the relative abundance of elements varies between different anatomical features of the specimens. These differences reflect the compositions of the minerals that replicated the decaying organism, which were controlled by contrasts in tissue chemistry. Delicate morphological details are replicated in the elemental maps, showing that authigenic mineralization was fundamental to preserving these fossils, even though some organic remains are also present. PMID:9712577

Orr; Briggs; Kearns

1998-08-21

77

Which 2:1 clay minerals are involved in the soil potassium reservoir? Insights from potassium addition or removal experiments on three temperate grassland soil clay assemblages  

Microsoft Academic Search

Field and laboratory observations based on X-ray diffraction techniques suggest that 2:1 clay minerals behave as a K reservoir. However, 2:1 soil clay assemblages are most often composed of a mixture of different 2:1 clay mineral populations and the role of these different clay mineral populations in K absorption or K release are not fully understood. This present work addressed

Pierre Barré; Bruce Velde; Colin Fontaine; Nicole Catel; Luc Abbadie

2008-01-01

78

Metachromasy as an indicator of photostabilization of methylene blue adsorbed to clays and minerals.  

PubMed

The influence of methylene blue adsorption to different clays on its photodegradation was studied. Methylene blue in solution was decomposed by sunlight in a zero-order process. Adsorption to some clay minerals (sepiolite and vermiculite) and a zeolite (clinoptilolite) accelerated the degradation process, and converted it to a first-order reaction. On the other hand, adsorption to other clay minerals (palygorskite and montmorillonite) stabilized the dye and prevented its degradation. Interestingly, in the clay-dye complexes that exhibited stability, clear metachromasy of the adsorbed methylene blue occurred, whereas the effect was not observed in the clay-dye complexes that underwent photodegradation. PMID:23474529

Samuels, Maya; Mor, Omer; Rytwo, Giora

2013-02-16

79

Last glacial–Holocene sediment sequences in N. Aegean basins: structure, accumulation rates and clay mineral distribution  

Microsoft Academic Search

The vertical distribution patterns of grain-size parameters, carbonate and organic carbon contents, and clay mineral abundances were examined in ten sediment cores from basins of the northern Aegean Sea. Sedimentation rates for Holocene deposition were determined on the basis of 11 14C datings and indirectly from the age of the lower sapropel S1; they were estimated at 14.9, 18.9–21.8 and 34.7 cm 10

G. Roussakis; A. P. Karageorgis; N. Conispoliatis; V. Lykousis

2004-01-01

80

MINERAL CHARACTERIZATION IN GEOSYNTHETIC CLAY LINERS USING MICRO-XRAY DIFFRACTION  

Microsoft Academic Search

Until recently, characterization of geosynthetic clay liner (GCL) bentonite had been limited to conventional powder X-ray diffraction (XRD). In this case, clays minerals were determined based on homogenized bulk samples and this routinely involved physical or chemical separation methods which can destroy or contaminate the sample. In addition, the minor minerals that comprise less than approximately five percent of the

K. Lange; R. K Rowe; H. Jamieson; R. L. Flemming

81

Antimicrobial effects of quaternary phosphonium salt intercalated clay minerals on Escherichia coli and Staphylococci aureus.  

PubMed

The aim of this research was to determine the antimicrobial properties and influence factors of four clay minerals intercalated by quaternary phosphonium salt (tetradecyl tributyl phosphonium bromide, TDTB) on antimicrobial effects. Escherichia coli (E. coli) and Staphylococci aureus (S. aureus) were chosen for Minimal Inhibitory Concentration (MIC) tests to evaluate the antimicrobial activities of organ-clay minerals. The properties of organ-clay minerals were analyzed by FTIR, XRD, TEM, Z-Average and Zeta potential, and the releasing amount of TDTB into the broth was measured by ICP. The results showed that montmorillonites-TDTB inhibited the growth of E. coli and S. aureus, and the MICs were 200 ± 20 and 80 ± 15 mg/L, respectively. The amount of TDTB released into the broth was 3.42 ± 0.71%. According to the properties of organ-clay mineral, it was indicated that the antimicrobial activities of organ-clay mineral were the synergic effect of the releasing amount of TDTB, Zeta potential, particle size and distribution. The organ-clay mineral with the larger releasing amount of TDTB, the higher Zeta potential, the same particle size with bacterial size and the narrower size distribution exhibited better antimicrobial activity. The present study demonstrated the properties of organ-clay minerals effected their antimicrobial activities, provided theoretically guidance to promote the antimicrobial activity of clay minerals. PMID:21536418

Wu, Ting; Xie, A-Gui; Tan, Shao-Zao; Cai, Xiang

2011-04-14

82

Clay minerals affect the stability of surfactant-facilitated carbon nanotube suspensions.  

PubMed

Carbon nanotubes (CNTs), because of their wide application, will inevitably enter aquatic systems, but the fate and transport of their suspensions in the environment are largely unknown. Clay minerals are expected to interact with CNT suspensions, affecting their fate and bioavailability. This study investigated the influence of clay minerals (kaolinite and montmorillonite) on the stability of surfactant (SDBS, CTAB, and TX100) facilitated multiwalled CNT (MWCNT) suspensions. Adsorption of the surfactants by MWCNTs and clay minerals was also examined. This is a first study on the interaction between clay minerals and surfactant-CNT suspensions. Sorption of SDBS by clay minerals and MWCNTs followed the order MWCNTs > montmorillonite approximately kaolinite; but sorption of CTAB and TX100 followed the order montmorillonite > MWCNTs > kaolinite. For SDBS suspended MWCNTs, introduction of montmorillonite and kaolinite could not change their stability; for CTAB suspended MWCNTs, both montmorillonite and kaolinite greatly deposited the suspended MWCNTs; for TX100 suspended MWCNTs, montmorillonite could partially deposit the suspended MWCNTs, whereas kaolinite showed minimal effect. Two mechanisms of clay minerals affecting MWCNT suspensions are (1) removal of surfactants by clay minerals from solution and MWCNT surface and (2) bridging between clay mineral and MWCNTs by surfactant. PMID:18853802

Han, Zhantao; Zhang, Fawang; Lin, Daohui; Xing, Baoshan

2008-09-15

83

Reaction mechanisms of clay minerals and organic diagenesis: an HRTEM/AEM study  

SciTech Connect

This project was designed to lead to an improved understanding of clay organic matter and detrital minerals in diagenetic environments. The results provided information for determinations of reaction mechanisms and establishment of kinetic models that permit one to predict the extent to which the formation of certain clay minerals occur at various depths, temperatures, and times.

Peter R. Buseck

1999-10-20

84

Oxygen and hydrogen isotope compositions in clay minerals: A potential single-mineral geothermometer  

NASA Astrophysics Data System (ADS)

The opposite slopes of the isotopic fractionation of hydrogen and oxygen in the clay-water system and the well-known relationship between D and 18 O in meteoric waters allow the isotopic composition of clay minerals to be used as a "single-mineral" geothermometer. Equations can be derived which are valid for continental systems where meteoric waters are common. The following equation was derived for smectite: 3.54*10 6 T -2 = 18 O sm - 0.125 D sm + 8.95 (0-150°) . This equation was used to determine the isotopic composition and temperature of the waters involved in the transformation of volcanic rock to bentonite at the Cortijo de Archidona (Southeastern Spain) site. The values obtained (-6% < 18 O < -4%; 9°C > T < 21°C, i.e., environmental temperatures) confirm the reliability of this equation.

Delgado, Antonio; Reyes, Emilio

1996-11-01

85

Modeling of Cation Binding in Hydrated 2:1 Clay Minerals  

SciTech Connect

The primary objective of our research is the development of molecular models of swelling and ion exchange in clay minerals with a view toward understanding the mechanisms of radionuclide transport through clay-rich soils. Specific scientific goals include using molecular computer simulations to calculate the thermodynamics of clay swelling and ion exchange, and to evaluate the dependence of clay properties upon interlayer ion identity and clay composition. The realization of these goals will, in general, improve our understanding of structure-function relationships in clays.

Smith, David E.

2000-06-01

86

Modeling of cation binding in hydrated 2:1 clay minerals  

SciTech Connect

'The primary focus of the research is the development of molecular theories of ion exchange on clay minerals, with a view toward understanding the mechanism of radionuclide transport through soils. The specific scientific goals of the study involve using molecular simulation methods to correlate clay-ion binding strengths with interlayer structure and swelling properties. This should build upon the fundamental understanding of clay behavior and allow for improvement in transport modeling of radionuclides in clay-rich soils.'

Smith, D.E.

1998-06-01

87

Mining Environmental Target Investigation of Kaolin Clay Mining and Milling.  

National Technical Information Service (NTIS)

Kaolin, a white clay considered to be one of the earth's most abundant minerals, has been mined in the United States for a century. Commercial kaolins are composed primarily of the aluminum silicate clay mineral kaolinite. Published epidemiological report...

D. C. Pickup

1982-01-01

88

Review of XRD-based quantitative analyses of clay minerals in soils: the suitability of mineral intensity factors  

Microsoft Academic Search

The determination of the types and relative amounts of the minerals present in soil forms an essential component of most soil characterization efforts. This paper reviews protocols for XRD-based quantitative clay mineral analysis in soils, with emphasis on methods using mineral intensity factors in combination with the so-called 100% approach. We summarize methodological differences and characteristic features and give information

Maren Kahle; Markus Kleber; Reinhold Jahn

2002-01-01

89

The titration of clay minerals II. Structure-based model and implications for clay reactivity.  

PubMed

The potentiometric titration and CEC data presented in part I are modeled in this paper, part II. Two models are compared: the two pK, three complexation sites plus exchange sites nonelectrostatic model developed by Baeyens and Bradbury and a model based on the MUSIC approach developed by Hiemstra and Van Riemsdijk. Both morphological and structural information is used to develop this new model. Morphological information is taken from the literature, while structural information is taken from the literature and constrained by supporting FTIR experiments. The Baeyens and Bradbury model is found to reproduce the general tendency of the titration curve, whereas the model based on the Hiemstra and Van Riemsdijk MUSIC approach provides a better fit to the experimental data. The former uses only 3 edge reaction sites, whereas the latter uses at least 27 edge reaction sites. Five main reactive sites are sufficient to fit the MUSIC model curve, but the model allows us to derive the properties of 22 other reactive sites. Logically, the greater the number of sites, the better the fit. Nevertheless, fewer adjustable parameters are necessary for the Hiemstra and Van Riemsdijk MUSIC model than for the Baeyens and Bradbury model, thanks to structural and morphological constraints. The precision of the potentiometric titration curve is insufficient to verify that the properties of the 27 sites given by the MUSIC model are effective. Thus, we coupled some properties of clay minerals, such as dissolution, to the modeled acid-base properties of these sites to assess our model. We then questioned the ability of simplified models such as the Baeyens and Bradbury model to predict the interactions between clay minerals and solutions in natural environments. In addition, we derived the cation exchange selectivity coefficients for CaCl+ ionic pairs and H+ from our CEC data and gave an estimate for the CaOH+ selectivity coefficient. PMID:15051457

Tournassat, Christophe; Ferrage, Eric; Poinsignon, Christiane; Charlet, Laurent

2004-05-01

90

MAX--An Interactive Computer Program for Teaching Identification of Clay Minerals by X-ray Diffraction.  

ERIC Educational Resources Information Center

|Discusses MAX, an interactive computer program for teaching identification of clay minerals based on standard x-ray diffraction characteristics. The program provides tutorial-type exercises for identification of 16 clay standards, self-evaluation exercises, diffractograms of 28 soil clay minerals, and identification of nonclay minerals. (MDH)|

Kohut, Connie K.; And Others

1993-01-01

91

Sm-Nd dating of Fig Tree clay minerals of the Barberton greenstone belt, South Africa.  

PubMed

Sm-Nd isotopic data from carbonate-derived clay minerals of the 3.22-3.25 Ga Fig Tree Group, Barberton greenstone belt, South Africa, form a linear array corresponding to an age of 3102 +/- 64 Ma, making these minerals the oldest dated clays on Earth. The obtained age is 120-160 m.y. younger than the depositional age determined by zircon geochronology. Nd model ages for the clays range from approximately 3.39 to 3.44 Ga and almost cover the age variation of the Barberton greenstone belt rocks, consistent with independent evidence that the clay minerals are derived from material of the belt. The combined isotopic and mineralogical data provide evidence for a cryptic thermal overprint in the sediments of the belt. However, the highest temperature reached by the samples since the time of clay-mineral formation was <300 degrees C, lower than virtually any known early Archean supracrustal sequence. PMID:11540244

Toulkeridis, T; Goldstein, S L; Clauer, N; Kroner, A; Lowe, D R

1994-03-01

92

A laboratory effort to quantitatively address clay abundance on Mars  

NASA Astrophysics Data System (ADS)

Data obtained at visible and near-infrared wavelengths by OMEGA on MarsExpress and CRISM on MRO provide definitive evidence for the presence of phyllosilicates and other hydrated phases on Mars. A diverse range of both Fe/Mg-OH and Al-OH-bearing phyllosilicates were identified including the smectites, nontronite, saponite, and montmorillonite. In order to constrain the abundances of these phyllosilicates spectral analyses of mixtures are needed. We report on our effort to enable the quantitative evaluation of the abundance of hydrated-hydroxylated silicates when they are contained in mixtures. We include two component mixtures of hydrated/hydroxylated silicates with each other and with two analogs for other martian materials; pyroxene (enstatite) and palagonitic soil (an alteration product of basaltic glass). For the hydrated-hydroxylated silicates we include saponite and montmorillonite (Mg- and Al- rich smectites). We prepared three size separates of each end-member for study: 20-45, 63-90, and 125-150 ?m. As an initial phase of our effort we used scanning electron microscopy imaging and x-ray diffraction to characterize the grain size distribution, and structural nature, respectively, of the pure end-member materials. Visible and near-infrared reflectance spectra of the 63-90 ?m grain size of the end-member samples are shown in Figure 1. We discuss the results of our initial measurements of these samples.

Roush, T. L.; Bishop, J. L.; Brown, A. J.; Hunkins, L.; Blake, D. F.; Bristow, T. F.

2011-12-01

93

Geochemical Consequences of Widespread Clay Mineral Formation in Mars' Ancient Crust  

NASA Astrophysics Data System (ADS)

Clays form on Earth by near-surface weathering, precipitation in water bodies within basins, hydrothermal alteration (volcanic- or impact-induced), diagenesis, metamorphism, and magmatic precipitation. Diverse clay minerals have been detected from orbital investigation of terrains on Mars and are globally distributed, indicating geographically widespread aqueous alteration. Clay assemblages within deep stratigraphic units in the Martian crust include Fe/Mg smectites, chlorites and higher temperature hydrated silicates. Sedimentary clay mineral assemblages include Fe/Mg smectites, kaolinite, and sulfate, carbonate, and chloride salts. Stratigraphic sequences with multiple clay-bearing units have an upper unit with Al-clays and a lower unit with Fe/Mg-clays. The typical restriction of clay minerals to the oldest, Noachian terrains indicates a distinctive set of processes involving water-rock interaction that was prevalent early in Mars history and may have profoundly influenced the evolution of Martian geochemical systems. Current analyses of orbital data have led to the proposition of multiple clay-formation mechanisms, varying in space and time in their relative importance. These include near-surface weathering, formation in ice-dominated near-surface groundwaters, and formation by subsurface hydrothermal fluids. Near-surface, open system formation of clays would lead to fractionation of Mars' crustal reservoir into an altered crustal reservoir and a sedimentary reservoir, potentially involving changes in the composition of Mars' atmosphere. In contrast, formation of clays in the subsurface by either aqueous alteration or magmatic cooling would result in comparatively little geochemical fractionation or interaction of Mars' atmospheric, crustal, and magmatic reservoirs, with the exception of long-term sequestration of water. Formation of clays within ice would have geochemical consequences intermediate between these endmembers. We outline the future analyses of orbital data, in situ measurements acquired within clay-bearing terrains, and analyses of Mars samples that are needed to more fully elucidate the mechanisms of martian clay formation and to determine the consequences for the geochemical evolution of the planet.

Ehlmann, Bethany L.; Berger, Gilles; Mangold, Nicolas; Michalski, Joseph R.; Catling, David C.; Ruff, Steven W.; Chassefière, Eric; Niles, Paul B.; Chevrier, Vincent; Poulet, Francois

2013-01-01

94

Clays as mineral dust aerosol: An integrated approach to studying climate, atmospheric chemistry, and biogeochemical effects of atmospheric clay minerals in an undergraduate research laboratory  

NASA Astrophysics Data System (ADS)

Entrained mineral dust aerosol accounts for 45% of the global annual atmospheric aerosol load and can have a significant influence on important environmental issues, including climate, atmospheric chemistry, cloud formation, biogeochemical processes, visibility, and human health. 70% of all mineral aerosol mass originating from Africa consists of layered aluminosilicates, including illite, kaolinite, and montmorillonite clays. Clay minerals are a largely neglected component of mineral aerosol, yet they have unique physiochemical properties, including a high reactive surface area, large cation exchange capacities, small particle sizes, and a relatively large capacity to take up adsorbed water, resulting in expansion of clay layers (and a larger reactive surface area for heterogeneous interactions) in some cases. An integrated laboratory research approach has been implemented at Hendrix College, a Primarily Undergraduate Institution, in which undergraduate students are involved in independent and interdisciplinary research projects that relate the chemical aging processes (heterogeneous chemistry) of clay minerals as a major component of mineral aerosol to their effects on climate (water adsorption), atmospheric chemistry (trace gas uptake), and biogeochemistry (iron dissolution and phytoplankton biomarker studies). Preliminary results and future directions will be reported.

Hatch, C. D.; Crane, C. C.; Harris, K. J.; Thompson, C. E.; Miles, M. K.; Weingold, R. M.; Bucuti, T.

2011-12-01

95

Transport and selective uptake of radium into natural clay minerals  

NASA Astrophysics Data System (ADS)

Understanding of the environmental behavior of Ra is important from the viewpoint of the long-termed repository safety of radioactive waste, but investigation of Ra behavior in natural environment is difficult to detect. We found isotopic evidence of Ra transportation and its selective uptake into clay minerals from Pb isotopic analyses. Illite grains found in calcite veins included in sandstone near the Oklo uranium deposit, Republic of Gabon, show extremely low 207Pb/ 206Pb (˜ 0.0158) isotopic ratios. Although the Pb isotopic ratios of calcite and quartz coexisting with illite indicate the formation age of each component, those of illite do not. In addition, illite grains having low 207Pb/ 206Pb isotopic ratios contain a strongly large amount of Ba (1230 to 6010 ppm) in contrast with low contents of Ba in calcite and quartz (< 0.26 ppm). Considering the chemical similarity between Ba and Ra, the 207Pb/ 206Pb isotopic data suggest an excess of 206Pb due to selective adsorption of 226Ra (and also Ba) into illite grains. This is a very rare example to show evidence of the selective adsorption behavior of Ra from the isotopic excesses of 206Pb, although the adsorption ability of Ra itself in nature was largely reported.

Hidaka, Hiroshi; Horie, Kenji; Gauthier-Lafaye, Françoise

2007-12-01

96

Correlation of the Abundance of Betaproteobacteria on Mineral Surfaces with Mineral Weathering in Forest Soils  

PubMed Central

Pyrosequencing-based analysis of 16S rRNA gene sequences revealed a significant correlation between apatite dissolution and the abundance of betaproteobacteria on apatite surfaces, suggesting a role for the bacteria belonging to this phylum in mineral weathering. Notably, the cultivation-dependent approach demonstrated that the most efficient mineral-weathering bacteria belonged to the betaproteobacterial genus Burhkolderia.

Lepleux, C.; Turpault, M. P.; Oger, P.; Frey-Klett, P.

2012-01-01

97

Hydrothermal Reactions of Shales and Clay Minerals with Cesium Phases Representative of Spent Reactor Fuel.  

National Technical Information Service (NTIS)

The immobilization of cesium extracted from spent fuel (SF) by ion exchange and direct chemical reaction with clay minerals and shales was investigated under hydrothermal, closed-system conditions. The exact cesium phases in SF are not known with certaint...

S. Komarneni G. J. McCarthy W. B. White

1979-01-01

98

Selective Sorption and Fixation of Cations by Clay Minerals: A Review  

Microsoft Academic Search

Investigations concerning selective sorption and fixation of K and similar cations by clay minerals and soil clays and the mechanisms of these reactions are reviewed. In particular, recent observations on selective sorption of fhese ions in dilute solutions by weathered micas and vermiculite in relation to the interlayer structures are discussed in detail. Also, implications of the resistance to weathering

B. L. SAWI-INEY

1972-01-01

99

Use of clay minerals in reconstructing geological processes: recent advances and some perspectives  

Microsoft Academic Search

This article reviews that clay literature from the last ten years, which is devoted to the applications of clay minerals in the interpretation of geological processes in sedimentary basins. The results, selected by the author as being of particular interest, are presented, arranged according to the successive phases of the rock cycle. The research field defined in the title has

J. Srodon

1999-01-01

100

Subsurface water and clay mineral formation during the early history of Mars  

Microsoft Academic Search

Clay minerals, recently discovered to be widespread in Mars's Noachian terrains, indicate long-duration interaction between water and rock over 3.7 billion years ago. Analysis of how they formed should indicate what environmental conditions prevailed on early Mars. If clays formed near the surface by weathering, as is common on Earth, their presence would indicate past surface conditions warmer and wetter

Bethany L. Ehlmann; John F. Mustard; Scott L. Murchie; Jean-Pierre Bibring; Alain Meunier; Abigail A. Fraeman; Yves Langevin

2011-01-01

101

Neogene clays from Poland as mineral sealing barriers for landfills: experimental study  

Microsoft Academic Search

Mineralogical and chemical compositions, as well as the physical properties of the Polish Neogene clays, justify the usage of this soil for mineral liners of waste disposal sites. However, low values of the strength parameters of these clays make them inapplicable as a raw material, but rather as a component of a mixture with another soil with higher values of

Beata ?uczak-Wilamowska

2002-01-01

102

A Study of the Adsorption of Ni(II) and Cu(II) by Clay Minerals  

Microsoft Academic Search

The adsorption of Ni(II) and Cu(II) on to the clay minerMs kaolinite, chlorite, and illite has been investigated. The quantity of Ni(II) at pH 6 and Cu(II) at pH 5 adsorbed has been found to vary in the manner chlorite > illite > kaolinite. Examination of the mode of bonding of the metal ions to the clay minerals using X-ray

M. H. Koppelman; J. G. DILLARD

1977-01-01

103

Structure and thermal\\/mechanical properties of poly(ethylene oxide)-clay mineral blends  

Microsoft Academic Search

Montmorillonite was organically modified with distearyldimethyl-ammonium chloride. This organically modified clay mineral and poly(ethylene oxide), (PEO), were solvent-cast blended with chloroform, and the structure and properties of the resulting blends were investigated. The effects of the clay mineral content on the isothermal crystallization of PEO are discussed. From small and wide angle X-ray scattering measurements of the blends, it was

Nobuo Ogata; Sugio Kawakage; Takashi Ogihara

1997-01-01

104

Nature and genesis of clay minerals of the Rustler Formation in the vicinity of the Waste Isolation Pilot Plant in southeastern New Mexico  

SciTech Connect

Detailed mineralogical studies of the matrix and fracture-fill materials of a large number of samples from the Rustler Formation have been carried out using x-ray diffraction, high-resolution transmission electron microscopy, electron microprobe analysis, x-ray fluorescence, and atomic absorption spectrophotometry. These analyses indicate the presence of four clay minerals: interstratified chlorite/saponite, illite, chlorite, and serpentine. Corrensite (regularly stratified chlorite/saponite) is the dominant clay mineral in samples from the Culebra dolomite and two shale layers of the lower unnamed member of the Rustler Formation. Within other layers of the Rustler Formation, disordered mixed chlorite/saponite is usually the most abundant clay mineral. Studies of the morphology and composition of clay crystallites suggest that the corrensite was formed by the alteration of detrital dioctahedral smectite in magnesium-rich pore fluids during early diagenesis of the Rustler Formation. This study provides initial estimates of the abundance and nature of the clay minerals in the Culebra dolomite in the vicinity of the Waste Isolation Pilot Plant.

Sewards, T.; Brearley, A.; Glenn, R. (New Mexico Univ., Albuquerque, NM (United States)); MacKinnon, I.D.R. (Queensland Univ., St. Lucia (Australia)); Siegel, M.D. (Sandia National Labs., Albuquerque, NM (United States))

1992-08-01

105

Ice nucleation properties of the most abundant mineral dust phases  

NASA Astrophysics Data System (ADS)

The ice nucleation properties of the nine most abundant minerals occurring in desert aerosols (quartz, albite, microcline, kaolinite, montmorillonite, illite, calcite, gypsum, and hematite) were investigated by environmental scanning electron microscopy (ESEM). In this instrument, the pure minerals are exposed to water vapor at variable pressures and temperatures. The crystallization of ice on the mineral particles is observed by secondary electron imaging, and the supersaturation for an activated particle fraction of 1-3% is determined as function of temperature. In all experiments, condensation of water prior to ice formation was not observed within detectable limits, even at water supersaturation. The highest temperatures for 1-3% activation vary between -10°C and -16°C for the nine minerals investigated, and the corresponding onset relative humidities relative to ice RHi between 107 and 117%. Supersaturation temperature curves for initial ice formation (1-3% activation) in the temperature range typical for mixed-phase clouds were measured for all nine minerals. The temperature dependence of the onset relative humidity is strongly dependent on mineralogy. Kaolinite, montmorillonite, and hematite show a strong increase in RHi with decreasing temperature, whereas RHi is almost constant for illite, albite, quartz, and calcite. The highly variable ice nucleation properties of the various mineral dust components should be considered for parameterization schemes. Illite and kaolinite are the most important minerals to consider, as they have high ice nucleation efficiency and are common components of desert aerosols.

Zimmermann, Frank; Weinbruch, Stephan; Schütz, Lothar; Hofmann, Heiko; Ebert, Martin; Kandler, Konrad; Worringen, Annette

2008-12-01

106

Evaluation of the medicinal use of clay minerals as antibacterial agents  

PubMed Central

Natural clays have been used to heal skin infections since the earliest recorded history. Recently our attention was drawn to a clinical use of French green clay (rich in Fe-smectite) for healing Buruli ulcer, a necrotizing fasciitis (‘flesh-eating’ infection) caused by Mycobacterium ulcerans. These clays and others like them are interesting as they may reveal an antibacterial mechanism that could provide an inexpensive treatment for this and other skin infections, especially in global areas with limited hospitals and medical resources. Microbiological testing of two French green clays, and other clays used traditionally for healing, identified three samples that were effective at killing a broad-spectrum of human pathogens. A clear distinction must be made between ‘healing clays’ and those we have identified as antibacterial clays. The highly adsorptive properties of many clays may contribute to healing a variety of ailments, although they are not antibacterial. The antibacterial process displayed by the three identified clays is unknown. Therefore, we have investigated the mineralogical and chemical compositions of the antibacterial clays for comparison with non-antibacterial clays in an attempt to elucidate differences that may lead to identification of the antibacterial mechanism(s). The two French green clays used to treat Buruli ulcer, while similar in mineralogy, crystal size, and major element chemistry, have opposite effects on the bacterial populations tested. One clay deposit promoted bacterial growth whereas another killed the bacteria. The reasons for the difference in antibacterial properties thus far show that the bactericidal mechanism is not physical (e.g., an attraction between clay and bacteria), but by a chemical transfer or reaction. The chemical variables are still under investigation. Cation exchange experiments showed that the antibacterial component of the clay can be removed, implicating exchangeable cations in the antibacterial process. Furthermore, aqueous leachates of the antibacterial clays effectively kill the bacteria. Progressively heating the clay leads first to dehydration (200°C), then dehydroxylation (550°C or more), and finally to destruction of the clay mineral structure by (~900°C). By identifying the elements lost after each heating step, and testing the bactericidal effect of the heated product, we eliminated many toxins from consideration (e.g., microbes, organic compounds, volatile elements) and identified several redox-sensitive refractory metals that are common among antibacterial clays. We conclude that the pH and oxidation state buffered by the clay mineral surfaces is key to controlling the solution chemistry and redox related reactions occurring at the bacterial cell wall.

Williams, Lynda B.; Haydel, Shelley E.

2010-01-01

107

Interactions of DNA with clay minerals and soil colloidal particles and protection against degradation by DNase.  

PubMed

Adsorption, desorption, and degradation by nucleases of DNA on four different colloidal fractions from a Brown soil and clay minerals were studied. The adsorption of DNase I and the structures of native DNA, adsorbed and desorbed, were also investigated by Fourier Transform Infrared (FTIR), circular dichroism (CD), and fluorescence spectroscopy, to determine the protection mechanism of DNA molecules by soil colloids and minerals against enzymatic degradation. Kaolinite exhibited the highest adsorption affinity for DNA among the examined soil colloids and clay minerals. In comparison with organomineral complexes (organic clays), DNA was tightly adsorbed by H2O2-treated clays (inorganic clays). FTIR spectra showed that the binding of DNA on kaolinite and inorganic clays changed its conformation from the B-form to the Z-form, whereas montmorillonite and organic clays retained the original B-form of DNA. A structural change from the B- to the C-form in DNA molecules desorbed from kaolinite was observed by CD spectroscopy and confirmed by fluorescence spectroscopy. The presence of soil colloids and minerals provided protection to DNA against degradation by DNase I. The higher level of protection was found with montmorillonite and organic clays compared to kaolinite and inorganic clays. The protection of DNA against nuclease degradation by soil colloids and minerals is apparently not controlled by the adsorption affinity of DNA molecules for the colloids and the conformational change of bound DNA. The higher stability of DNA seemed to be attributed mainly to the presence of organic matter in the system and the adsorption of nucleases on soil colloids and minerals. The information obtained in this study is of fundamental significance for the understanding of the behavior of extracellular DNA in soil environment. PMID:16719099

Cai, Peng; Huang, Qiao-Yun; Zhang, Xue-Wen

2006-05-01

108

The possible role of nannobacteria (dwarf bacteria) in clay-mineral diagenesis and the importance of careful sample preparation in high-magnification SEM study  

SciTech Connect

Bacterial textures are present on clay minerals in Oligocene Frio Formation sandstones from the subsurface of the Corpus Christi area, Texas. In shallower samples, beads 0.05--0.1 {micro}m in diameter rim the clay flakes; at greater depth these beads become more abundant and eventually are perched on the ends of clay filaments of the same diameter. The authors believe that the beads are nannobacteria (dwarf forms) that have precipitated or transformed the clay minerals during burial of the sediments. Rosettes of chlorite also contain, after HCl etching, rows of 0.1 {micro}m bodies. In contrast, kaolinite shows no evidence of bacterial precipitation. The authors review other examples of bacterially precipitated clay minerals. A danger present in interpretation of earlier work (and much work of others) is the development of nannobacteria-looking artifacts caused by gold coating times in excess of one minute; the authors strongly recommend a 30-second coating time. Bacterial growth of clay minerals may be a very important process both in the surface and subsurface.

Folk, R.L.; Lynch, F.L. [Univ. of Texas, Austin, TX (United States)

1997-05-01

109

Clay Minerals as Solid Acids and Their Catalytic Properties.  

ERIC Educational Resources Information Center

|Discusses catalytic properties of clays, attributed to acidity of the clay surface. The formation of carbonium ions on montmorillonite is used as a demonstration of the presence of surface acidity, the enhanced dissociation of water molecules when polarized by cations, and the way the surface can interact with organic substances. (Author/JN)|

Helsen, J.

1982-01-01

110

The interaction of biological molecules with clay minerals: a scanning force microscopy study.  

PubMed

We have used the technique of scanning force microscopy (SFM) to investigate the reaction of both amino acids and activated nucleotides in the presence of the clay mineral Cu(II)-exchanged hectorite. Using simulated prebiotic heating and wetting cycles, we have shown that the clay mineral acts to adsorb, concentrate, and subsequently catalyze the polymerization of these biological monomers into short peptides and oligonucleotides. The presence of the Cu(II) cations within the clay intergallery regions, and at surface step edges and cracks, is crucial for the observed reactions to occur. Clay minerals such as hectorite may have thus played an important role in the evolution of biologically viable molecules on the prebiotic earth. PMID:10768382

Porter, T L; Eastman, M P; Whitehorse, R; Bain, E; Manygoats, K

111

Measurement of clay surface areas by polyvinylpyrrolidone (PVP) sorption and its use for quantifying illite and smectite abundance  

USGS Publications Warehouse

A new method has been developed for quantifying smectite abundance by sorbing polyvinylpyrrolidone (PVP) on smectite particles dispersed in aqueous solution. The sorption density of PVP-55K on a wide range of smectites, illites and kaolinites is ???0.99 mg/m2, which corresponds to ???0.72 g of PVP-55K per gram of montmorillonite. Polyvinylpyrrolidone sorption on smectites is independent of layer charge and solution pH. PVP sorption on Si02, Fe 2O3 and ZnO normalized to the BET surface area is similar to the sorption densities on smectites. ??-Al 2O3, amorphous Al(OH)3 and gibbsite have no PVP sorption over a wide range of pH, and sorption of PVP by organics is minimal. The insensitivity of PVP sorption densities to mineral layer charge, solution pH and mineral surface charge indicates that PVP sorption is not localized at charged sites, but is controlled by more broadly distributed sorption mechanisms such as Van der Waals' interactions and/or hydrogen bonding. Smectites have very large surface areas when dispersed as single unit-cell-thick particles (???725 m2/g) and usually dominate the total surface areas of natural samples in which smectites are present. In this case, smectite abundance is directly proportional to PVP sorption. In some cases, however, the accurate quantification of smectite abundance by PVP sorption may require minor corrections for PVP uptake by other phases, principally illite and kaolinite. Quantitative XRD can be combined with PVP uptake measurements to uniquely determine the smectite concentration in such sample. ?? 2004, The Clay Minerals Society.

Blum, A. E.; Eberl, D. D.

2004-01-01

112

MODELING OF CATION BINDING IN HYDRATED 2:1 CLAY MINERALS  

EPA Science Inventory

Hydrated 2:1 clay minerals are high-surface area, layered silicates that play a unique role in determining the fate of ionic pollutants in the environment. These minerals, including smectites and vermiculites, make up a major component of many soils. Ionic pollutants, including r...

113

Synthesis and characterization of carbon nanotubes on clay minerals and its application to a hydrogen peroxide biosensor  

Microsoft Academic Search

In this study, we demonstrate the synthesis of carbon nanotubes (CNTs) on clay minerals, and the development of biosensors based on Nafion–CNT\\/Clay–Au and Nafion–CNT\\/Clay–Au–Glucose oxidase (GOD) composite films for the detection of hydrogen peroxide (H2O2) and glucose, respectively. The CNTs are synthesized on nickel cation exchanged clay mineral platelets. From field-emission scanning electron microscope images, X-ray diffraction, Fourier transfer infrared

Hao-Lin Hsu; Jih-Mirn Jehng

2009-01-01

114

Iron-rich clay minerals on Mars - Potential sources or sinks for hydrogen and indicators of hydrogen loss over time  

Microsoft Academic Search

Although direct evidence is lacking, indirect evidence suggests that iron-rich clay minerals or poorly-ordered chemical equivalents are widespread on the Martian surface. Such clays can act as sources or sinks for hydrogen ('hydrogen sponges'). Ferrous clays can lose hydrogen and ferric clays gain it by the coupled substitution Fe(3+)O(Fe(2+)OH)-1, equivalent to minus atomic H. This 'oxy-clay' substitution involves only proton

D. M. Burt

1989-01-01

115

Enhanced carbon dioxide release and other possible effects of clay minerals during thermal evaluation of sediments  

SciTech Connect

Thermal evaluation of potential source rocks (PSR) include measurements of CO{sub 2} evolved (> 400{degree}C) designated as IO (Oxygen Index). For whole rock analysis this index frequently exceeds the value derived from organically bonded oxygen. The surplus of OC{sub 2} stems mainly from the reaction of carbonates with active acidic volatiles released from the associated clays. The magnitude of this effect is specific for every clay mineral, but for any particular mineral assemblage it correlates directly with the clay/carbonate ratio. The largest discrepancy between IO values and organically bonded oxygen occurs when O.M. is low ({approximately} 0.5-1%), clays dominate and sufficient carbonates are present to react. Clay minerals and kerogen probably do not react, as such. However, the inactive volatiles released upon heating attack even before depolymerization. The liquid monomers produced then can react with both clay minerals and their volatiles. These interactions could result in changes of the IH factor (Hydrogen Index) as well as the distribution of products.

Aizenshtat, Z.; Miloslavsky, I.; Kallai, L.H. (Hebrew Univ. of Jerusalem (Israel))

1989-03-01

116

Effect of pH on adsorption of arsenic and selenium from landfill leachate by clay minerals  

Microsoft Academic Search

Adsorption of As(V), As(III), and Se(IV) anions from municipal landfill leachate solutions by the clay minerals kaolinite and montmorillonite is strongly dependent upon solution pH. The HâAsOâ⁻ and HSeOâ⁻ ions are the apparent primary As(V) and Se(IV) species being adsorbed by the clay minerals. Activation of the anion adsorption sites on the clay minerals by H\\/sup +\\/ ions is important

R. R. Frost; R. A. Griffin

1977-01-01

117

Modeling of Cation Binding in Hydrated 2:1 Clay Minerals - Final Report  

SciTech Connect

Hydrated 2:1 clay minerals are high surface area, layered silicates that play a unique role in determining the fate of radionuclides in the environment. This project consisted of developing and implementing computer simulation methods for molecular characterization of the swelling and ion exchange properties of Hydrated 2:1 clay minerals, and the subsequent analysis and theoretical modeling with a view toward improving contaminant transport modeling as well as soil remediation and radionuclide containment strategies. Project results included the (a) development of simulation methods to treat clays under environmentally relevant conditions of variable water vapor pressure; (b) calculation of clay swelling thermodynamics as a function of interlayer ion size and charge (calculated quantities include immersion energies, free energies, and entropies of swelling); and (c) calculation of ion exchange free energies, including contributions from changing interlayer water contents and layer spacing.

Smith, David E.

2000-09-14

118

Antarctic subtropical humid episode at the Paleocene-Eocene boundary: Clay-mineral evidence  

Microsoft Academic Search

Clay-mineral assemblages from East Antarctica have been analyzed at high stratigraphic resolution (20 to 1 ka) throughout the interval from 55.6 to 55.0 Ma, which includes the terminal Paleocene isotopic excursion in Ocean Drilling Program Site 690B on Maud Rise (lat 65°S) in the Weddell Sea region. Changes in the clay associations reflect a major increase in chemical weathering caused

Christian Robert; James P. Kennett

1994-01-01

119

Adsorption, desorption and oxidation of arsenic affected by clay minerals and aging process  

Microsoft Academic Search

Adsorption\\/desorption and oxidation\\/reduction of arsenic at clay surfaces are very important to the natural attenuation of\\u000a arsenic in the subsurface environment. Although numerous studies have concluded that iron oxides have high affinities for\\u000a the adsorption of As(V), very little experimental work has addressed the arsenic attenuation capacities of different clay\\u000a minerals and aging process affecting the transformation of arsenic. The

Z. Lin; R. W. Puls

2000-01-01

120

Alkali Cation Selectivity and Fixation by Clay Minerals  

Microsoft Academic Search

Two variables must be considered when calculating exchange free energies (AG~ for 2:1 clays: (1) anionic field strength, as expressed by equivalent anionic radius (ra), and (2) interlayer water content, as expressed by interlayer molality. For smectites that are in a state of high hydration, interlayer molality is determined by the cations undergoing exchange. Thus AG~ for an exchanging cation

Dennis D. Eberl

1980-01-01

121

In vitro biological effects of clay minerals advised as substitutes for asbestos.  

PubMed

We studied one sample of commercial sepiolite and two samples of commercial vermiculite--clay minerals proposed as replacements for asbestos--and tested in vitro their abilities to activate complement, to lyse erythrocytes, and to elicit the production of reactive oxygen species (ROS) with human polymorphonuclear leukocytes (PMN) or bovine alveolar macrophages (AM); their behavior was compared with that of asbestos fibers obtained from the Union International Contra Cancer (UICC) as reference standards, as well as with kaolinite and illite, main members of the clay mineral family. Since in short-term in vitro tests the biological activity of mineral particles seems especially related to the active sites on their surface, we first measured the specific surface area of each mineral. Sepiolite was unreactive in two of the three tests we used (complement activation and ROS production) and able to lyse a minimal percentage of red blood cells. Vermiculite was shown to be incapable of activating complement, to have a moderate hemolytic activity and a high ability to elicite ROS production, although lower than that of chrysotile. Sepiolite, therefore, might be of more interest than vermiculite, given the low level of biological effects detected during the tests used to compare both clay minerals with asbestos fibres. The ROS production does not seem to require phagocytosis. A high ROS production was observed with kaolinite: this result casts doubt on the ability of pathogenic mineral dusts in vitro to induce a greater release of ROS than nonpathogenic mineral dusts. PMID:8608405

Governa, M; Valentino, M; Visonà, I; Monaco, F; Amati, M; Scancarello, G; Scansetti, G

1995-10-01

122

Rare earth distributions in clay minerals and in the clay-sized fraction of the Lower Permian Havensville and Eskridge shales of Kansas and Oklahoma  

Microsoft Academic Search

The REE (rare earth element) content of a wide variety of clay mineral groups have been analyzed using radiochemical neutron activation and have been found to be quite variable in absolute REE content (range of REE = 5.4-1732) and less variable in relative REE content (range of chondritenormalized La \\/ Lu = 0.9-16.5). The variable REE content of the clay

Robert L. Cullers; Sambhudas Chaudhuri; Bill Arnold; Moon Lee; Carlton W. Wolf Jr.

1975-01-01

123

Atomic-level studies of the depletion in reactive sites during clay mineral dissolution  

NASA Astrophysics Data System (ADS)

Clay mineral dissolution rates can continuously decrease over time as reactive sites located on edges are preferentially depleted under certain pH conditions. Changes in reactive surface area and the difficulties in quantifying this elusive variable have been cited as one key reason for the complexity in developing accurate rate equations for the dissolution of clay minerals. Recently, a solid-state nuclear magnetic resonance (NMR) method has been proposed for counting the number of reactive surface sites on a defined quantity of a clay mineral. Using this solid-state NMR proxy, changes in reactive surface area were monitored for a series of batch dissolution experiments of low-defect kaolinite KGa-1b and Ca-rich bentonite STx-1b, a montmorillonite-rich clay containing an opal-CT impurity, at 21 °C and initial pH 3. Kaolinite specific surface area as determined from BET gas isotherm data did not change within error during 80 days of dissolution whereas bentonite specific surface area decreased rapidly to about 50% of the original value as interlayer cation concentrations changed. The solid-state NMR proxy revealed decreases in the number of reactive surface sites per gram of kaolinite and bentonite as a function of dissolution time, presumed to be from the preferential dissolution of reactive sites on edges at initial pH 3. This depletion of reactive edge sites can be tied to a concomitant decrease in the rates of release of Si and Al into solution. The quantity of reactive sites can be used to estimate the dissolution rates of kaolinite and bentonite as well as estimate trends in dissolution rates of other clay minerals. These results further highlight the need to quantify the number of reactive sites present on a per gram basis as well as characterize their depletion with time to develop and use dissolution rate models for clay minerals and other heterogeneous materials in the environment.

Sanders, Rebecca L.; Washton, Nancy M.; Mueller, Karl T.

2012-09-01

124

Atomic-level studies of the depletion in reactive sites during clay mineral dissolution.  

SciTech Connect

Clay mineral dissolution rates can continuously decrease over time as reactive sites located on edges are preferentially depleted under certain pH conditions. Changes in reactive surface area and the difficulties in quantifying this elusive variable have been cited as one key reason for the complexity in developing accurate rate equations for the dissolution of clay minerals. Recently, a solid-state nuclear magnetic resonance (NMR) method has been proposed for counting the number of reactive surface sites on a defined quantity of a clay mineral. Using this solid-state NMR proxy, changes in reactive surface area were monitored for a series of batch dissolution experiments of low-defect kaolinite KGa-1b and Ca-rich bentonite STx-1b, a montmorillonite-rich clay containing an opal-CT impurity, at 21 ºC and initial pH 3. Kaolinite specific surface area as determined from BET gas isotherm data did not change within error during 80 days of dissolution whereas bentonite specific surface area decreased rapidly to about 50% of the original value as interlayer cation concentrations changed. The solid-state NMR proxy revealed decreases in the number of reactive surface sites per gram of kaolinite and bentonite as a function of dissolution time, presumed to be from the preferential dissolution of reactive sites on edges at initial pH 3. This depletion of reactive edge sites can be tied to a concomitant decrease in the rates of release of Si and Al into solution. The quantity of reactive sites can be used to estimate the dissolution rates of kaolinite and montmorillonite as well as estimate trends in dissolution rates of other clay minerals. These results further highlight the need to quantify the number of reactive sites present on a per gram basis as well as characterize their depletion with time to develop and use dissolution rate models for clay minerals and other heterogeneous materials in the environment.

Sanders, Rebecca L.; Washton, Nancy M.; Mueller, Karl T.

2012-09-01

125

Crystallization and textural porosity of synthetic clay minerals.  

SciTech Connect

The crystallization of synthetic layered magnesium silicate hectorite clays from both silica sol and organosilane sources is compared. For the silica sol-derived clays, a templating method is employed wherein organic or polymeric molecules are included during clay crystallization that are then removed from the composites via calcination. The mechanism of silane-derived hectorite formation is followed by XRD, TGA, 29Si MAS NMR, and small angle X-ray scattering (SAXS), and results are compared to those obtained for the sol-derived hectorite. The mechanism appears to be similar but the rate is approximately doubled when the silane is used rather than silica sol. Analytical transmission electron microscopy (TEM) is exploited to glean structural morphology information towards resolving the nature of the resulting pore network structures. Results are compared with nitrogen adsorption-desorption isotherm behavior; dominant hysteresis loops are present in the type IV isotherms. Pore size distributions based on both the adsorption and desorption isotherms are compared. Small angle neutron scattering (SANS) experiments reveal that the average particle size increases as synthetic laponite < sol-derived hectorite < silane-derived hectorite < natural hectorite. Contrast matching SANS studies in aqueous and organic solvents are carried out to extract information about pore accessibility.

Carrado, K. A.; Csencsits, R.; Thiyagarajan, P.; Seifert, S.; Macha, S. M.; Harwood, J.; Univ. of Illinois at Chicago; IIT

2002-12-01

126

Catalytic activity of an iron-pillared montmorillonitic clay mineral in heterogeneous photo-Fenton process  

Microsoft Academic Search

Two catalysts prepared separately by iron pillaring of two different-sized particle fractions of a dried, ground and sieved clay mineral were tested for catalytic performance in photo-Fenton discoloration of methylene blue aqueous solutions.Two different-sized particle fractions of the mineral were selected prior to pillaring, ranging below 250?m and within the range of 250–450?m, respectively. The resulting solids were characterized by

María A. De León; Jorge Castiglioni; Juan Bussi; Marta Sergio

2008-01-01

127

Networking and rheology of concentrated clay suspensions "matured" in mineral medicinal water.  

PubMed

This work studied the influence of "maturation" conditions (time and agitation) on aggregation states, gel structure and rheological behaviour of a special kind of pharmaceutical semisolid products made of concentrated clay suspensions in mineral medicinal water. Maturation of the samples was carried out in distilled and sulphated mineral medicinal water, both in static conditions (without agitation) and with manual stirring once a week, during a maximum period of three months. At the measured pH interval (7.5-8.0), three-dimensional band-type networks resulting from face/face contacts were predominant in the laminar (disc-like) clay suspensions, whereas the fibrous (rod-like) particles formed micro-aggregates by van der Waals attractions. The high concentration of solids in the studied systems greatly determined their behaviour. Rod-like sepiolite particles tend to align the major axis in aggregates promoted by low shearing maturation, whereas aggregates of disc-like smectite particles did not have a preferential orientation and their complete swelling required long maturation time, being independent of stirring. Maturation of both kinds of suspensions resulted in improved rheological properties. Laminar clay suspensions became more structured with time, independently from static or dynamic maturation conditions, whereas for fibrous clay periodic agitation was also required. Rheological properties of the studied systems have been related to aggregation states and networking mechanisms, depending on the type of clay minerals constituents. Physical stability of the suspensions was not impaired by the specific composition of the Graena medicinal water. PMID:23764616

Aguzzi, Carola; Sánchez-Espejo, Rita; Cerezo, Pilar; Machado, José; Bonferoni, Cristina; Rossi, Silvia; Salcedo, Inmaculada; Viseras, César

2013-06-10

128

An investigation of water uptake on clays minerals using ATR-FTIR spectroscopy coupled with quartz crystal microbalance measurements  

Microsoft Academic Search

It is becoming increasingly clear that the heterogeneous chemistry of mineral dust aerosol is a function of relative humidity (f(RH)) as water on the surface of the mineral dust particles can enhance or inhibit its reactivity depending on the reaction. Since clay minerals make up a significant component of the mineral dust aerosol, it is important to understand water uptake

Jennifer D. Schuttlefield; David Cox; Vicki H. Grassian

2007-01-01

129

Hydrothermal reactions of clay minerals and shales with cesium phases from spent fuel elements  

Microsoft Academic Search

The research described in this paper is part of a continuing program aimed at understanding the chemical reactions between nuclear waste materials and shale repositories in the presence of hot, pressurized ground water. This paper treats the immobilization of Cs released from spent fuel elements by simulated hydrothermal fluids when this fission product interacts with clay minerals in the repository

Sridhar Komarneni; WILLIAM B. WHITE

1981-01-01

130

Clay minerals used in sanitary landfills for the retention of organic and inorganic pollutants  

Microsoft Academic Search

Samples from a waste operating facility in western Greece were collected in order to determine the composition of the clay minerals present and assess their efficacy in organic and inorganic pollutants retention. For this purpose a number of analytical techniques were employed. 1H NMR revealed that some of the organic components which are present in the samples are aliphatics, polysaccharides,

Eleni Koutsopoulou; Dimitris Papoulis; Panagiota Tsolis-Katagas; Michael Kornaros

2010-01-01

131

Competitive Adsorption of Arsenate and Arsenite on Oxides and Clay Minerals  

Microsoft Academic Search

effect of the presence of equimolar arsenite on arsenate adsorption. including oxides, clay minerals, and whole soils. In- The competitive effect of equimolar arsenate on arsenite adsorption was small and apparent only on kaolinite and illite in the pH range organic constituents of soils that adsorb significant 6.5 to 9. The constant capacitance model was able to fit the arsenate

Sabine Goldberg

2002-01-01

132

FINAL REPORT. MODELING OF CATION BINDING IN HYDRATED 2:1 CLAY MINERALS  

EPA Science Inventory

Hydrated 2:1 clay minerals are high surface area, layered silicates that play a unique role in determining the fate of radionuclides in the environment. This project consisted of developing and implementing computer simulation methods for molecular characterization of the swellin...

133

Subtitution of Pentane by a Mineral Clay as a Blowing Agent for Phenolic Foam  

Microsoft Academic Search

The main drawback of using pentane as a blowing agent for rigid phenolic foam is its flammability. It presents a real risk of explosion and therefore requires specific conditions for handling and storage. In this article its replacement by a mineral clay composed mainly of calcium carbonate as the major component in addition to some other metal oxides, was investigated

F. Riahi; R. Doufnoune; C. Bouremel

2007-01-01

134

Modern and late Quaternary clay mineral distribution in the area of the SE Mediterranean Sea  

Microsoft Academic Search

The present-day clay mineral distribution in the southeastern Levantine Sea and its borderlands reveals a complex pattern of different sources and distribution paths. Smectite dominates the suspended load of the Nile River and of rivers in the Near East. Illite sources are dust-bearing winds from the Sahara and southwestern Europe. Kaolinite is prevalent in rivers of the Sinai, in Egyptian

Yvonne Hamann; Werner Ehrmann; Gerhard Schmiedl; Tanja Kuhnt

2009-01-01

135

Clay minerals in nonaqueous extraction of bitumen from Alberta oil sands  

Microsoft Academic Search

Although not used commercially, a nonaqueous extraction process is of great interest to extract bitumen from the Alberta oil sands due to its potential advantages, such as high bitumen recovery even from low grade oil sand ores and the elimination of slow settling, sludge tailings ponds with stable suspensions. While clay minerals have been characterized in water-based bitumen extraction from

Ali Hooshiar; Peter Uhlik; Douglas G. Ivey; Qi Liu; Thomas H. Etsell

136

Laboratory studies on the heterogeneous chemistry of clay minerals in the Earth's atmosphere  

Microsoft Academic Search

Atmospheric mineral aerosol is a potentially important reactive surface that may provide a heterogeneous sink for gas phase species such as nitric acid and oxygenated organic compounds in the Earth's troposphere. Smectite clays, such as montmorillonite, are particularly interesting reactive surfaces because they are commonly found in the atmosphere and have a unique ability to swell. The swelling properties of

Courtney Dyan Mashburn

2006-01-01

137

Iron-rich clay minerals on Mars - Potential sources or sinks for hydrogen and indicators of hydrogen loss over time  

NASA Astrophysics Data System (ADS)

Although direct evidence is lacking, indirect evidence suggests that iron-rich clay minerals or poorly-ordered chemical equivalents are widespread on the Martian surface. Such clays can act as sources or sinks for hydrogen ('hydrogen sponges'). Ferrous clays can lose hydrogen and ferric clays gain it by the coupled substitution Fe(3+)O(Fe(2+)OH)-1, equivalent to minus atomic H. This 'oxy-clay' substitution involves only proton and electron migration through the crystal structure, and therefore occurs nondestructively and reversibly, at relatively low temperatures. The reversible, low-temperature nature of this reaction contrasts with the irreversible nature of destructive dehydroxylation (H2O loss) suffered by clays heated to high temperatures. In theory, metastable ferric oxy-clays formed by dehydrogenation of ferrous clays over geologic time could, if exposed to water vapor, extract the hydrogen from it, releasing oxygen.

Burt, D. M.

138

Clay mineral variations in Four-Point Bayou, Terrebonne Parish, Louisiana  

SciTech Connect

Cores of unconsolidated sediments from the Four-Point Bayou area, representing an interdistributary basin deposit less than 1000 years old, were examined for variations in clay mineralogy. Two specific environments of deposition, interpreted from grain-size analyses and sedimentary structures, were compared: a sand-rich natural levee deposit and an overlying clay-rich interdistributary bay. Analyses of the < 2 ..mu..m clay fraction using Schultz's method show smectite to be the predominant clay in both environments. The relative abundance of kaolinite:illite:smectite in the natural levee, near-channel deposits is 1:3:6. In bay deposits, it is 2:3:5. Hydraulic fractionation of clays during deposition should result in a high K/I ratio in natural levees and a low ratio in bay deposits, the reverse of what was observed. Kaolinite should have been enriched in natural levees at the expense of illite. Other processes must have been operative either at the time of deposition or during early diagenesis of these deposits. Possible mechanisms include localized redistribution and sorting or chemical equilibration with early pore fluids associated with saltwater intrusion. The mixing of clays from different sources could also account for the observed differences.

Baxter, P.; Ferrell, R.E.

1987-05-01

139

Leaching of clay minerals in a limestone environment  

USGS Publications Warehouse

Water saturated with CO2 at about 25??C was percolated through mixed beds of limestone or marble fragments and montmorillonite, "illite" and kaolinite in polyethylene tubes for six and fortyfive complete runs. The leachates were analysed for SiO2, A12O3 and Fe2O3, but only SiO2 was found. The minerals lost SiO2 in this order: montmorillonite > kaolinite > "illite". The differential removal of SiO2 during the short period of these experiments suggests a mechanism for the accumulation of bauxite deposits associated with limestones. ?? 1959.

Carroll, D.; Starkey, H. C.

1959-01-01

140

Clay mineral continental amplifier for marine carbon sequestration in a greenhouse ocean.  

PubMed

The majority of carbon sequestration at the Earth's surface occurs in marine continental margin settings within fine-grained sediments whose mineral properties are a function of continental climatic conditions. We report very high mineral surface area (MSA) values of 300 and 570 m(2) g in Late Cretaceous black shales from Ocean Drilling Program site 959 of the Deep Ivorian Basin that vary on subcentennial time scales corresponding with abrupt increases from approximately 3 to approximately 18% total organic carbon (TOC). The observed MSA changes with TOC across multiple scales of variability and on a sample-by-sample basis (centimeter scale), provides a rigorous test of a hypothesized influence on organic carbon burial by detrital clay mineral controlled MSA. Changes in TOC also correspond with geochemical and sedimentological evidence for water column anoxia. Bioturbated intervals show a lower organic carbon loading on mineral surface area of 0.1 mg-OC m(-2) when compared to 0.4 mg-OC m(-2) for laminated and sulfidic sediments. Although either anoxia or mineral surface protection may be capable of producing TOC of < 5%, when brought together they produced the very high TOC (10-18%) apparent in these sediments. This nonlinear response in carbon burial resulted from minor precession-driven changes of continental climate influencing clay mineral properties and runoff from the African continent. This study identifies a previously unrecognized land-sea connection among continental weathering, clay mineral production, and anoxia and a nonlinear effect on marine carbon sequestration during the Coniacian-Santonian Oceanic Anoxic Event 3 in the tropical eastern Atlantic. PMID:21576498

Kennedy, Martin J; Wagner, Thomas

2011-05-16

141

Clay mineral continental amplifier for marine carbon sequestration in a greenhouse ocean  

PubMed Central

The majority of carbon sequestration at the Earth’s surface occurs in marine continental margin settings within fine-grained sediments whose mineral properties are a function of continental climatic conditions. We report very high mineral surface area (MSA) values of 300 and 570 m2 g in Late Cretaceous black shales from Ocean Drilling Program site 959 of the Deep Ivorian Basin that vary on subcentennial time scales corresponding with abrupt increases from approximately 3 to approximately 18% total organic carbon (TOC). The observed MSA changes with TOC across multiple scales of variability and on a sample-by-sample basis (centimeter scale), provides a rigorous test of a hypothesized influence on organic carbon burial by detrital clay mineral controlled MSA. Changes in TOC also correspond with geochemical and sedimentological evidence for water column anoxia. Bioturbated intervals show a lower organic carbon loading on mineral surface area of 0.1 mg-OC m-2 when compared to 0.4 mg-OC m-2 for laminated and sulfidic sediments. Although either anoxia or mineral surface protection may be capable of producing TOC of < 5%, when brought together they produced the very high TOC (10–18%) apparent in these sediments. This nonlinear response in carbon burial resulted from minor precession-driven changes of continental climate influencing clay mineral properties and runoff from the African continent. This study identifies a previously unrecognized land–sea connection among continental weathering, clay mineral production, and anoxia and a nonlinear effect on marine carbon sequestration during the Coniacian-Santonian Oceanic Anoxic Event 3 in the tropical eastern Atlantic.

Kennedy, Martin J.; Wagner, Thomas

2011-01-01

142

Iron reduction in nontronite-type clay minerals: Modelling a complex system  

NASA Astrophysics Data System (ADS)

Reduction-oxidation or redox processes constitute a class of important reactions in a wide range of mineral environments. The specific focus in this investigation is on iron-bearing (ferruginous) clay minerals, where the redox reaction has important consequences for their structural and chemical integrity. Although this process has been studied experimentally, it is not yet fully understood where and how this occurs within clay mineral layers. The investigation presented here addresses this question from first principles using density functional theory (DFT), planewaves, pseudopotentials and periodic cells. The first issue addressed is that of simulating a dynamic reduction process using static models. Careful consideration is paid to the introduction of artificial electrostatic interactions, their subsequent identification and the effect these may have on the results. As a consequence of these considerations, three sets of models based on nontronite (Fe2(Si,Al)4O10(OH)2) are presented. The electronic structures of these clay mineral models are allowed to relax, to attain their own state of redox. By extensively analysing the Mulliken charges, magnetic states and orbital occupancy of iron, aluminium, silicon and oxygen, we have been able to draw firm conclusions about the relative reduction of iron within the tetrahedral and octahedral sheets of three varieties of nontronite. Reduction occurs to the greatest extent in the octahedral sheet iron and oxidation in the tetrahedral sheet iron. As these results reflect general, local environments within a clay mineral, they are therefore applicable to similar local environments and thus provide the foundations for further studies into more complex, geochemical systems.

Geatches, D. L.; Clark, S. J.; Greenwell, H. C.

2012-03-01

143

Aqueous dissolution, solubilities and thermodynamic stabilities of common aluminosilicate clay minerals: Kaolinite and smectites  

USGS Publications Warehouse

Determinations of the aqueous solubilities of kaolinite at pH 4, and of five smectite minerals in suspensions set between pH 5 and 8, were undertaken with mineral suspensions adjusted to approach equilibrium from over- and undersaturation. After 1,237 days, Dry Branch, Georgia kaolinite suspensions attained equilibrium solubility with respect to the kaolinite, for which Keq = (2.72 ?? 0.35) ?? 107. The experimentally determined Gibbs free energy of formation (??Gf,2980) for the kaolinite is -3,789.51 ?? 6.60 kj mol-1. Equilibrium solubilities could not be determined for the smectites because the composition of the solution phase in the smectite suspensions appeared to be controlled by the formation of gibbsite or amorphous aluminum hydroxide and not by the smectites, preventing attempts to determine valid ??Gf0 values for these complex aluminosilicate clay minerals. Reported solubility-based ??Gf0 determinations for smectites and other variable composition aluminosilicate clay minerals are shown to be invalid because of experimental deficiencies and of conceptual flaws arising from the nature of the minerals themselves. Because of the variable composition of smectites and similar minerals, it is concluded that reliable equilibrium solubilities and solubility-derived ??Gf0 values can neither be rigorously determined by conventional experimental procedures, nor applied in equilibriabased models of smectite-water interactions. ?? 1986.

May, H. M.; Klnniburgh, D. G.; Helmke, P. A.; Jackson, M. L.

1986-01-01

144

Reductions in the toxicity of cadmium to microorganisms by clay minerals.  

PubMed

The clay minerals montmorillonite and kaolinite protected bacteria, including actinomycetes, and filamentous fungi from the inhibitory effects of cadmium (Cd). Montmorillonite provided greater protection than did equivalent concentrations of kaolinite. The protective ability of the clays was correlated with their cation exchange capacity (CEC). The greater the CEC, the greater the absorbancy of exogenous Cd by the exchange complex and the greater the protection. The greater protection afforded by montmorillonite, as compared to kaolinite, was correlated with its higher CEC. Clays homoionic to Cd did not protect against exogenous Cd, as the exchange complex was already saturated with Cd. Montmorillonite homoionic to Cd was more detrimental to microbial growth than was kaolinite homoionic to Cd, as more Cd was present on and apparently desorbed from the montmorillonite. PMID:16345228

Babich, H; Stotzky, G

1977-03-01

145

Pedogenic formation of montmorillonite from a 2:1-2:2 intergrade clay mineral  

USGS Publications Warehouse

Montmorillonite was found to be the dominant clay mineral in surface horizons of certain soils of the North Carolina Coastal Plain whereas a 2:1-2:2 intergrade clay mineral was dominant in subjacent horizons. In all soils where this clay mineral sequence was found, the surface horizon was low in pH (below 4??5) and high in organic matter content. In contrast, data from studies of other soils of this region (Weed and Nelson, 1962) show that: (1) montmorillonite occurs infrequently; (2) maximum accumulation of the 2:1-2:2 intergrade normally occurs in the surface horizon and decreases with depth in the profile; (3) organic matter contents are low; and (4) pH values are only moderately acid (pH 5-6). It is theorized that the montmorillonite in the surface horizon of the soils studied originated by pedogenic weathering of the 2:1-2:2 intergrade clay mineral. The combined effects of low pH (below 4??5) and high organic matter content in surface horizons are believed to be the agents responsible for this mineral transformation. The protonation and solubilization (reverse of hydrolysis) of Al-polymers in the interlayer of expansible clay minerals will occur at or below pH 4??5 depending on the charge and steric effects of the interlayer. A low pH alone may cause this solubilization and thus mineral transformation, but in the soils studied the organic matter is believed to facilitate and accelerage the transformation. The intermediates of organic matter decomposition provide an acid environment, a source of protons, and a source of watersoluble mobile organic substances (principally fulvic acids) which have the ability to complex the solubilized aluminum and move it down the profile. This continuous removal of solubilized aluminum would provide for a favorable gradient for aluminum solubilization. The drainage class or position in a catena is believed to be less important than the chemical factors in formation of montmorillonite from 2:1-2:2 intergrade, because montmorillonite is present in all drainage classes if the surface horizon is low in pH and high in organic matter. ?? 1969.

Malcolm, R. L.; Nettleton, W. D.; McCracken, R. J.

1969-01-01

146

Indication of Cesium Adsorption Into Angstrom-Scale Open Spaces in Saponite Clay Mineral  

NASA Astrophysics Data System (ADS)

Adsorption behavior of cesium (Cs) into angstrom-scale open spaces for the saponite clay mineral is investigated by making use of positronium (Ps) annihilation spectroscopy together with thermogravimetry and differential thermal analysis (TG-DTA). Ps annihilation spectroscopy reveals two kinds of open spaces with their sizes of 3 Å and 10 Å, respectively, after baking at 423 K for 8 h under the vacuum condition at 10-5 Torr. The large open space is found to survive for the Cs-type saponite due to less hydration of the Cs cations even after the exposure to the air for 200 h. It is thus inferred that Cs is locally adsorbed in the angstrom-scale open spaces in the saponite clay minerals.

Numata, Kazuomi; Sato, Kiminori; Fujimoto, Koichiro

2012-12-01

147

Use of natural gamma ray spectral logging in evaluation of clay minerals  

SciTech Connect

Gamma ray spectral logging can be used for qualitative and quantitative evaluations of argillaceous sediments, in both cased and open boreholes. Well-logging devices record the gamma rays emitted by potassium (K/sup 40/) at 1.46 MeV, the uranium series nuclide bismuth (Bi/sup 214/) emanating gamma rays at 1.76 MeV, and the thorium series nuclide thallium (Tl/sup 208/) emanating gamma rays at 2.61 MeV. The information obtained can be used in stratigraphic correlations, recognition of rock types, determining the amount and type of clay minerals present in clastic formations, establishing rock potential of shales, evaluating diagenetic and catagenetic changes in clay minerals, CEC estimates and so on.

Fertl, W.H.; Chilingarian, G.V.; Yen, T.F.

1982-10-01

148

Mineral Surface Control of Organic Carbon Burial: Secular Rise of Clay Mineral Deposition in the Precambrian and the Rise of Oxygen  

Microsoft Academic Search

Accumulation of oxygen in the earth's atmosphere requires burial of organic matter in marine sediments. Today, the major mode of organic carbon burial is in association with detrital pedogenic clay minerals which serve to protect organic matter against biological oxidation during burial in marine sediments. The bulk of detrital clays that are ultimately deposited in marine sediments are formed in

M. J. Kennedy; M. L. Droser; L. Mayer; D. Pevear

2004-01-01

149

Significance of saturation index of certain clay minerals in shallow coastal groundwater, in and around Kalpakkam, Tamil Nadu, India  

NASA Astrophysics Data System (ADS)

The saturation index of clay minerals like Gibbsite, Kaolinite, Illite, Montmorillonite and Chlorite in groundwater were studied in detail by collecting 29 groundwater samples from the shallow coastal aquifers in and around Kalpakkam. The samples collected were analysed for major cations, anions and trace elements by using standard procedures. The study reveals that pH has a significant role in the saturation index (SI) of minerals. It also shows that the relationship of electrical conductivity to the SI of these minerals is not significant than that of the ionic strength, log pCO2 values, and alumina silica ratio have significant relation to the SI of these clay minerals. The SI of these clay minerals was spatially distributed to identify the areas of higher SI. Silica has good correlation to SI of Kaolinite, Gibbsite and Montmorillonite and Al has good correlation to SI of all the minerals except to that of Chlorite.

Chidambaram, S.; Karmegam, U.; Sasidhar, P.; Prasanna, M. V.; Manivannan, R.; Arunachalam, S.; Manikandan, S.; Anandhan, P.

2011-10-01

150

Late Quaternary sedimentation on the Mid-Atlantic Reykjanes Ridge: clay mineral assemblages and depositional environment  

Microsoft Academic Search

Sediment samples from the Mid-Atlantic Reykjanes Ridge (59°N) were taken to get information about sediment genesis and to\\u000a identify different sources during the late Quaternary. Samples were investigated by X-ray diffraction and grain-size analyses.\\u000a The clay mineral assemblages in sediments of the Reykjanes Ridge reflect paleoceanographic changes during the late Quaternary.\\u000a Holocene sediments are characterized by high contents of smectite,

B. Gehrke; K. S. Lackschewitz; H.-J. Wallrabe-Adams

1996-01-01

151

Adsorption and photooxidation of pharmaceuticals and personal care products on clay minerals  

Microsoft Academic Search

The adsorption and photodegradation behavior of tetracycline (TC), chloramphenicol (CAP) and sulfamethoxazole (SMX) in clay\\u000a mineral dispersion was investigated in this work. Only TC showed significant adsorption to natural montmorillonite and rectorite,\\u000a whereas CAP and SMX adsorbed to natural montmorillonite, kaolinite and rectorite to a much lower extent. The adsorption equilibrium\\u000a constants (L\\/kg) of TC to natural montmorillonite were 332

Yanxiang LiuXujie; Xujie Lu; Feng Wu; Nansheng Deng

152

Phosphate fixation by ando soils different in their clay mineral composition  

Microsoft Academic Search

The phosphate fixation capacity at pH 4.5 and an equilibrium concentration of 250 mM phosphate was measured. The soil samples were divided into five groups according to their clay mineralogical composition. The first group soils contain opaline silica and allophanelike constituents, and some unidentified minerals, the second opaline silica and crystalline layer .i1icates, the third opaline silica and crystalline layer

Chitoshi Mizota

1977-01-01

153

The link between clay mineral weathering and the stabilization of Ni surface precipitates  

SciTech Connect

The formation of transition-metal surface precipitates may occur during sorption to clay minerals under ambient soil conditions. This process may lead to significant long-term stabilization of the metal within the soil profile. However, the rates and mechanisms controlling surface precipitate formation are poorly understood. The authors monitored changes in the reversibility of Ni sorbed to a clay mineral, pyrophyllite, in model batch experiments maintained at pH 7.5 for up to 1 year. The macroscopic sorption and dissolution study was complemented by a time-resolved characterization of the sorbed phase via spectroscopic and thermal methods. They found that nickel became increasingly resistant, over time, to extraction with EDTA. Initially, the sorbed phase consisted of a Ni-Al layered double hydroxide (LDH). With time, the anionic species in the interlayer space of the LDH changed from nitrate to silica polymers transforming the LDH gradually into a precursor Ni-Al phyllosilicate. The authors believe that this phase transformation is responsible for a substantial part of the observed increase in dissolution resistance. Thus, clay mineral weathering and the time-dependent release of Al and Si ions controlled Ni precipitate nucleation and transformation. The results suggest a potential pathway for long-term Ni stabilization in soil.

Ford, R.G.; Scheinost, A.C.; Scheckel, K.G.; Sparks, D.L. [Univ. of Delaware, Newark, DE (United States). Dept. of Plant and Soil Sciences

1999-09-15

154

Aggregation of Clay Minerals and Marine Microalgal cells: Physicochemical Theory and Implications for Controlling Harmful Algal Blooms.  

National Technical Information Service (NTIS)

Clay dispersal is one of the most promising strategies for controlling harmful algal blooms. It is based on the mutual aggregation of algal cells with mineral particles, leading to aggregate settling. This research demonstrated the effectiveness of domest...

M. R. Sengco

2001-01-01

155

Clay mineral, geochemical and Sr-Nd isotopic fingerprinting of sediments in the Murray-Darling fluvial system, southeast Australia  

Microsoft Academic Search

Clay minerals, trace elements and isotopic signatures ( 87 Sr\\/ 86 Sr; 143 Nd\\/ 144 Nd) were investigated to fingerprint fine-grained sediments (52mm) from the major tributaries of the Murray-Darling fluvial system. Mineralogical, chemical and isotopic signatures in the river clays are clearly inherited from the assemblage of source rocks and soils in the upper catchments of each river. As

F. X. Gingele; P. de Deckker

2005-01-01

156

Comparison of clay mineral stratigraphy to other proxy palaeoclimate indicators in the Mesozoic of NW Europe.  

PubMed

This paper reviews the opportunities and pitfalls associated with using clay mineralogical analysis in palaeoclimatic reconstructions. Following this, conjunctive methods of improving the reliability of clay mineralogical analysis are reviewed. The Mesozoic succession of NW Europe is employed as a case study. This demonstrates the relationship between clay mineralogy and palaeoclimate. Proxy analyses may be integrated with clay mineralogical analysis to provide an assessment of aridity-humidity contrasts in the hinterland climate. As an example, the abundance of kaolinite through the Mesozoic shows that, while interpretations may be difficult, the Mesozoic climate of NW Europe was subject to great changes in rates of continental precipitation. We may compare sedimentological (facies, mineralogy, geochemistry) indicators of palaeoprecipitation with palaeotemperature estimates. The integration of clay mineralogical analyses with other sedimentological proxy indicators of palaeoclimate allows differentiation of palaeoclimatic effects from those of sea-level and tectonic change. We may also observe how widespread palaeoclimate changes were; whether they were diachronous or synchronous; how climate, sea level and tectonics interact to control sedimentary facies and what palaeoclimate indicators are reliable. PMID:12804299

Ruffell, Alastair; McKinley, Jennifer M; Worden, Richard H

2002-04-15

157

Synthesis of Smectite Clay Minerals: A Critical Review  

SciTech Connect

Smectites are one of the most important groups of phyllosilicates found in soils and sediments, and certainly one of the most difficult to study. New information about the formation mechanisms, impact of structural features on surface properties, and long-term stability of smectites can best be gained from the systematic study of single-phase specimens. In most instances, these specimens can only be obtained through synthesis under controlled conditions. Syntheses of smectites have been attempted (1) at ambient pressure and low-temperature (< 100 C), (2) under moderate hydrothermal conditions (100-1000 C, pressures to several kbars), (3) under extreme hydrothermal conditions (>1000 C or pressures> 10 kbars), and (4) in the presence of fluoride. Of these approaches, syntheses performed under moderate hydrothermal conditions are the most numerous and the most successful in terms of smectite yield and phase- purity. Using hydrothermal techniques, high phase-purity can be obtained for beidellites and several transition-metal smectites. However, synthesis of montmorillonite in high purity remains difficult. Starting materials for hydrothermal syntheses include gels, glasses, and other aluminosilicate minerals. The presence of Mg2+ seems to be essential for the formation of smectites, even for phases such as montmorillonite which contain low amounts of Mg. Highly crystalline smectites can be obtained when extreme temperatures or pressures are used, but other crystalline impurities are always present. Although the correlation between synthesis stability fields and thermodynamic stability fields is good in many instances, metastable phases are often formed. Few studies, however, include the additional experiments (approach from under- and over-saturation, reversal experiments) needed to ascertain the conditions for formation of thermodynamically stable phases. Thorough characterization of synthetic products by modern instrumental and molecular-scale techniques is also needed to better understand the processes leading to smectite formation.

Kloprogge, J T. (unknown); Komarneni, S (Pennsylvania State University); Amonette, James E. (BATTELLE (PACIFIC NW LAB))

1999-01-01

158

INFLUENCE OF STABLE Cs AND K ON THE REACTIONS OF Cs137 AND K42 IN SOILS AND CLAY MINERALS  

Microsoft Academic Search

Experiments were conducted to study the influence of stable Cs and K on ; the reactions of tracer quantities of Cs¹³⁷ and K⁴² in soils and clay ; minerals, using an equilibrium batch method. Tracer quantities of both Cs\\/sup ; 137\\/ and K⁴² were strongly sorbed in soils and clay minerals. Cesium was ; more strongly sorbed than K. Since

H. Nishita; P. Taylor; G. V. Alexander; K. H. Larson

1962-01-01

159

DE-FG02-06ER15364: Final Technical Report Nanoscale Reactivity of Clays, Clay Analogues (Micas), and Clay Minerals  

SciTech Connect

The project objectives were to determine the nanoscale to molecular scale structure of the interface between muscovite mica and aqueous solutions containing various sorbates and to explore systematics that control the incorporation of inorganic and organic chemical components during aging of nanoparticles of iron-oxides and aluminosilicate clays. The basal surface of phyllosilicates is a primary sorbent of environmental contaminants, natural organic matter, and nutrients. Micas are also superb atomically-flat substrates used in materials science and surface physics applications. We applied X-ray scattering techniques using high brilliance synchrotron radiation to investigate molecular-scale details of mica’s interface structure in solutions containing common and toxic cations, anions, and natural organic molecules. Nanoparticles are ubiquitous in the environment and have a high capacity for sorbing contaminants through the combined effects of their high surface areas and pH-dependent surface charge. Aging of nanoparticles from metastable to stable phases can be inhibited by sorption of nonstructural components, but exact mechanisms are unknown. We synthesized Fe-oxides and aluminosilicate clay minerals from aqueous solutions in the presence of selected anions, and organic molecules, and quantified the uptake of these additives during aging and some implications for nanoparticle formation.

Nagy, Kathryn L.

2008-07-03

160

Theoretical study of adsorption of methyl tert-butyl ether on broken clay minerals surfaces  

NASA Astrophysics Data System (ADS)

The interactions between methyl tert-butyl ether (MTBE) and differently defected tetrahedral and octahedral fragments of clay minerals containing Si4+, Al3+, and Mg2+ central cations have been studied at the B3LYP and MP2 levels of theory in conjunction with the 6-31G(d) basis set. MTBE interacts with defect clay structures due to the formation of multiple C?H...O and O?H...O hydrogen bonds. Interactions of MTBE with systems containing different types of defected mineral fragments were found to vary. Systems containing the same type of defected mineral fragment with different central cation interact almost the same way with MTBE. The formation of hydrogen bonds leads to changes in the geometrical parameters and to the polarization of MTBE. The values of the interaction energies depend on the charge of the mineral fragment. They amount to 5 kcal/mol-35 kcal/mol. MTBE interacts more preferably with octahedral fragments than with tetrahedral fragments that contain an Al3+ central cation.

Michalkova, A.; Johnson, L. D.; Gorb, L.; Zhikol, O. A.; Shishkin, O. V.; Leszczynski, J.

161

Ball clay  

USGS Publications Warehouse

Part of the 2000 annual review of the industrial minerals sector. A general overview of the ball clay industry is provided. In 2000, sales of ball clay reached record levels, with sanitary ware and tile applications accounting for the largest sales. Ball clay production, consumption, prices, foreign trade, and industry news are summarized. The outlook for the ball clay industry is also outlined.

Virta, R. L.

2001-01-01

162

Quantitative determination of mineral types and abundances from reflectance spectra using principal components analysis  

NASA Astrophysics Data System (ADS)

A procedure was developed for analyzing remote reflectance spectra, including multispectral images, that quantifies parameters such as types of mineral mixtures, the abundances of mixed minerals, and particle sizes. Principal components analysis reduced the spectral dimensionality and allowed testing the uniqueness and validity of spectral mixing models. By analyzing variations in the overall spectral reflectance curves, the type of spectral mixture was identified, mineral abundances quantified and the effects of particle size identified. The results demonstrate an advantage in classification accuracy over classical forms of analysis that ignore effects of particle-size or mineral-mixture systematics on spectra. The approach is applicable to remote sensing data of planetary surfaces for quantitative determinations of mineral abundances.

Smith, M. O.; Johnson, P. E.; Adams, J. B.

1985-02-01

163

Fluorescence X-ray microscopy on hydrated tributyltin-clay mineral suspensions  

NASA Astrophysics Data System (ADS)

Using the scanning transmission X-ray microscope at ID21 beamline of the ESRF in fluorescence mode, we mapped tin at a bulk concentration of 1000 ?g(Sn)/ml within hydrated tributyltin (TBT)-clay mineral (Kaolinite) dispersion with sub-300 nm spatial resolution. Using the L absorption edges of tin at 3929, 4156 and 4465 eV fluorescence radiation was excited in tin atoms with incident photon energies of 4 and 4.5 keV. When using 4 keV radiation, only tin fluorescence is excited. For 4.5 keV X rays, both the fluorescence of tin and calcium (which is present in the solid phase) can be measured. Methodologically, we were interested in assessing and proving the possibilities and limitations of fluorescence mapping using the L absorption edges of tin, where the fluorescence yield is significantly lower compared to other elements with their K edges in the same energy range. Scientifically, organotin-clay mineral interactions are of environmental concern because this factor influences significantly the distribution of toxic TBT in the aquatic System. On one hand, the half-life of TBT deposited to the sediment phase increases, and consequently the time of its bioavailability. On the other hand, the adsorption process is reversible, which means that contaminated sediments can act as a source of pollution. The adsorption and desorption effects can be studied directly with high spatial resolution and brought into connection to the surface properties of the clay mineral under study as well as to other experimental parameters, like pH or salinity.

Neuhäusler, U.; Schmidt, C.; Hoch, M.; Susini, J.

2003-03-01

164

Predictive diagenetic clay-mineral distribution in siliciclastic rocks as a tool for identifying sequence boundaries in non-marine successions: the Coalspur Formation, west-central Alberta  

NASA Astrophysics Data System (ADS)

The study of upper Cretaceous-lower Tertiary fluvial deposits of the Coalspur Formation in the Foothills region of west-central Alberta reveals that the distribution of early authigenic kaolinite has a well-defined relation to the sequence stratigraphic framework. In this context, it has been observed that the kaolin mineral content increases in sandstones lying below subaerial unconformities, which mark the most significant stratigraphic hiatuses and hence the sequence boundaries in fully fluvial successions. The increased abundance of authigenic kaolinite immediately below sequence boundaries may have been caused by the infiltration of meteoric water during times of subaerial erosion, resulting in the dissolution of unstable minerals (e.g., micas and feldspar) and the formation of kaolinite and secondary porosity. It is therefore suggested that the change in clay mineral assemblages in the stratigraphic section depends in part on the position of the analyzed sandstone samples relative to the sequence boundaries. In a larger context, the method of using authigenic clays to delineate depositional sequences in non-marine successions needs to be evaluated on a case-by-case basis, as the diagnostic early diagenetic minerals underlying the sequence boundary may change as a function of palaeoclimate and also as a function of late diagenetic processes.

Khidir, Ahmed; Catuneanu, Octavian

2009-12-01

165

Geostatistical Analysis of Spatial Variability of Mineral Abundance and Kd in Frenchman Flat, NTS, Alluvium  

Microsoft Academic Search

LLNL hydrologic source term modeling at the Cambric site (Pawloski et al., 2000) showed that retardation of radionuclide transport is sensitive to the distribution and amount of radionuclide sorbing minerals. While all mineralogic information available near the Cambric site was used in these early simulations (11 mineral abundance analyses from UE-5n and 9 from RNM-l), these older data sets were

S F Carle; M Zavarin; G A Pawloski

2002-01-01

166

An investigation of water uptake on clays minerals using ATR-FTIR spectroscopy coupled with quartz crystal microbalance measurements  

NASA Astrophysics Data System (ADS)

It is becoming increasingly clear that the heterogeneous chemistry of mineral dust aerosol is a function of relative humidity (f(RH)) as water on the surface of the mineral dust particles can enhance or inhibit its reactivity depending on the reaction. Since clay minerals make up a significant component of the mineral dust aerosol, it is important to understand water uptake on this large fraction of dust present in the Earth's atmosphere. In this study, bulk and surface properties of several types and sources of clay minerals are characterized using a variety of techniques, including surface area measurements, attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy, scanning electron microscopy coupled with energy dispersive X-ray (SEM-EDX) analysis, X-Ray diffraction (XRD), Mössbauer spectroscopy, and X-ray photoelectron spectroscopy (XPS). For these well-characterized clays, ATR-FTIR spectroscopy is combined with quartz crystal microbalance (QCM) mass measurements to investigate water uptake as a f(RH). Similar measurements were also done for ?-Al2O3 and synthetic NaY zeolite for comparison. Water uptake on the clay minerals, although variable and dependent on both the type and source of the clay, is greater than that found for ?-Al2O3, a metal oxide, and in many cases similar or greater than NaY zeolite, a crystalline porous material. The presence of cations with large hydration energies significantly increases the water uptake capacity for the clay minerals. The atmospheric implications of these results are discussed.

Schuttlefield, Jennifer D.; Cox, David; Grassian, Vicki H.

2007-11-01

167

Mineral Surface Control of Organic Carbon Burial: Secular Rise of Clay Mineral Deposition in the Precambrian and the Rise of Oxygen  

NASA Astrophysics Data System (ADS)

Accumulation of oxygen in the earth's atmosphere requires burial of organic matter in marine sediments. Today, the major mode of organic carbon burial is in association with detrital pedogenic clay minerals which serve to protect organic matter against biological oxidation during burial in marine sediments. The bulk of detrital clays that are ultimately deposited in marine sediments are formed in biologically active soils that require plant processes to retain water, concentrate weathering produced solutes, stablize soils, and provide an adsorptive media. At some point in Earth history before the colonization of land surfaces by plants and the formation of biotic soils, clay mineral surface limitation may have severely reduced the preservation potential of organic carbon during burial. An important consequence of this would have also been a reduced flux of oxygen to the atmosphere because organic carbon and oxygen release are coupled. Multiple independent lines of evidence indicate a significant change in continental weathering and pedogenic clay mineral formation and establishment of the `clay factory' that coincides with colonization of land surfaces by primitive plant like organisms in the late Precambrian. The enhanced burial efficiency that would have accompanied the shift to the modern mode of detrital pedogenic clay hosted carbon burial would have driven an increase in oxygen levels toward present values. Evidence suggests that this rise in oxygen occurred just prior to the advent of the first complex animals in the Ediacaran.

Kennedy, M. J.; Droser, M. L.; Mayer, L.; Pevear, D.

2004-12-01

168

Clay minerals as indicators for depositional environment in the south Hallettsville Field, Lavaca County, Texas  

SciTech Connect

The South Hallettsville Field, Lavaca County, Texas, produces gas and condensate from Lower Wilcox sandstones and shales which have been interpreted as either channel turbidite deposits in outer-shelf to slope locations or as delta to pro-delta sands and muds. Thirteen core samples were analyzed by X-ray diffraction methods to determine whether a semiquantitative estimate of clay mineral content would aid in determining the depositional environment. Discrete illite, kaolinite, and chlorite are of particular interest because the presence of these minerals is interpreted as being due to original deposition. If a turbidity-type event occurred, the weight percents of nondiagenetic clays in this sequence should: (1) decrease significantly as the boundary is crossed between the shale and the overlying sandstone; and (2) gradually increase in progressively shallower samples within the sandstone. However, the weight percents for kaolinite and chlorite do not vary significantly; the illite content gradually decreases with shallower depths. This sequence is more compatible with a deltaic environment of deposition. 10 references.

Freed, R.L.

1980-01-01

169

Clay mineral weathering and contaminant dynamics in a caustic aqueous system. II. Mineral transformation and microscale partitioning  

NASA Astrophysics Data System (ADS)

Microscopic and spectroscopic studies were conducted to assess mineral transformation processes in aqueous suspensions of illite (Il), vermiculite (Vm) and montmorillonite (Mt) that were subjected to weathering in a simulated high-level radioactive tank waste leachate (0.05 m Al T, 2 m Na +, 1 m NO 3-, pH ˜14, Cs + and Sr 2+ present as co-contaminants). Time series (0 to 369 d) experiments were conducted at 298 K, with initial [Cs] 0 and [Sr] 0 concentrations from 10 -5 to 10 - mol kg -. Incongruent clay dissolution resulted in an accumulation of secondary aluminosilicate precipitates identified as nitrate-sodalite, nitrate-cancrinite and zeolite X, by molecular spectroscopy and electron microscopy (XRD, IR, NMR, SEM-EDS and TEM-EDS). Contaminant fate was dependent on competing uptake to parent clays and weathering products. TEM-EDS results indicated that high Il affinity for Cs was due to adsorption at frayed edge sites. The Il system also comprised Sr-rich aluminous precipitates after 369 d reaction time. In Mt systems, Cs and Sr were co-precipitated into increasingly recalcitrant spheroidal precipitates over the course of the experiment, whereas contaminant association with montmorillonite platelets was less prevalent. In contrast, Cs and Sr were found in association with weathered Vm particles despite the formation of spheroidal aluminosilicate precipitates that were comparable to those formed from Mt dissolution.

Choi, Sunkyung; Crosson, Garry; Mueller, Karl T.; Seraphin, Supapan; Chorover, Jon

2005-09-01

170

Patterns of mineral transformations in clay gouge, with examples from low-angle normal fault rocks in the western USA  

NASA Astrophysics Data System (ADS)

Neoformed minerals in shallow fault rocks are increasingly recognized as key to the behavior of faults in the elasto-frictional regime, but neither the conditions nor the processes which wall-rock is transformed into clay minerals are well understood. Yet, understanding of these mineral transformations is required to predict the mechanical and seismogenic behavior of faults. We therefore present a systematic study of clay gouge mineralogy from 30 outcrops of 17 low-angle normal faults (LANF's) in the American Cordillera to demonstrate the range and type of clay transformations in natural fault gouges. The sampled faults juxtapose a wide and representative range of wall rock types, including sedimentary, metamorphic and igneous rocks under shallow-crustal conditions. Clay mineral transformations were observed in all but one of 28 faults; one fault contains only mechanically derived clay-rich gouge, which formed entirely by cataclasis.Clay mineral transformations observed in gouges show four general patterns: 1) growth of authigenic 1Md illite, either by transformation of fragmental 2M1 illite or muscovite, or growth after the dissolution of K-feldspar. Illitization of fragmental illite-smectite is observed in LANF gouges, but is less common than reported from faults with sedimentary wall rocks; 2) 'retrograde diagenesis' of an early mechanically derived chlorite-rich gouge to authigenic chlorite-smectite and saponite (Mg-rich tri-octahedral smectite); 3) reaction of mechanically derived chlorite-rich gouges with Mg-rich fluids at low temperatures (50-150 °C) to produce localized lenses of one of two assemblages: sepiolite + saponite + talc + lizardite or palygorskite +/- chlorite +/- quartz; and 4) growth of authigenic di-octahedral smectite from alteration of acidic volcanic wall rocks. These transformation groups are consistent with patterns observed in fault rocks elsewhere. The main controls for the type of neoformed clay in gouge appear to be wall-rock chemistry and fluid chemistry, and temperatures in the range of 60-180 °C.

Haines, Samuel H.; van der Pluijm, Ben A.

2012-10-01

171

Effects of heavy metals on the electrokinetic properties of bacteria, yeast, and clay minerals  

SciTech Connect

The electrokinetic patterns of four bacteria (Bacillus subtilis, Bacillus megaterium, Pseudomonas aeruginosa, Agrobacterium radiobacter), two yeasts (Saccharomyces cerevisiae, Canida albicans), and two clay minerals (montmorillonite, kaolinite) in the presence of the chloride salts of heavy metals (Cd, Cr, Cu, Hg, Ni, Pb, Zn) and of Na and Mg were determined by microelectrophoresis. The cells and clays were net negatively charged at pH values above their isoelectric point (pI) in solutions of Na, Mg, Hg, and Pb with an ionic strength (..mu..) of 3 x 10/sup -4/. However, at pH values above pH 5.0, the charge of some bacteria, S. cerevisiae, and kaolinite changed to a net positive charge (charge reversal) in the presence of Cd, Cr, Cu, Ni, and Zn. The charge of the bacteria and S. cerevisiae also reversed in solution of Ni and Cu with a ..mu.. > 3 x 10/sup -4/, whereas there was no reversal in solutions with a ..mu.. < 3 x 10/sup -4/. The clays became net positively charged when the ..mu.. of Cu was > 3 x 10/sup -4/ and that of Ni was > 1.5 x 10/sup -4/. The charge of the cells and clays also reversed in solutions containing both Mg and Ni or both Cu and Ni (except montmorillonite) but not in solutions containing both Mg and Cu (except kaolinite) (..mu.. = 3 x 10/sup -4/). The pI of the cells in the presence of some heavy metals, especially Ni and Cr, was at higher pH values than in the presence of Na and Mg.

Collins, Y.E.

1987-01-01

172

Ball clay  

USGS Publications Warehouse

The article offers information on ball clay. Among the companies that mine ball clay in the U.S. are H.C. Spinks Clay, Kentucky-Tennessee Clay and Old Hickory Clay. In 2006, an estimated 1.2 million tons of the mineral was sold or used domestically and exported. Forty-percent of the total sales is accounted for ceramic floor and wall tile followed by sanitaryware and miscellaneous ceramics. Its average value was $ 45 per ton in 2006.

Virta, R. L.

2007-01-01

173

[A spectral unmixing method of estimating main minerals abundance of lunar soils].  

PubMed

Estimating minerals abundance from reflectance spectra is one of the fundamental goals of remote sensing lunar exploration, and the main difficulties are the complicated mixing law of minerals spectrum and spectral features being sensitive to several kinds of factors such as topography, particle size and roughness etc. A method based on spectral unmixing was put forward and tested in the present paper. Before spectra are unmixed the spectral continuum is removed for clarifying and strengthening spectral features. The absorption features and reflectance features (the upward curving parts of spectra between absorption features) are integrated for unmixing to improve the unmixing performance. The Hapke model was used to correct unmixing error due to nonlinear mixing of minerals spectra. Forty three mixed spectra of olivine, clinopyroxene, hypersthene and plagioclase were used to validate the above method. The four minerals abundance was estimated under the conditions of being unaware of endmember spectra used to mix, granularity and chemical composition of minerals. Residual error, abundance error and correlation coefficient between retrieved and true abundance were 5.0 Vol%, 14.4 Vol% and 0.92 respectively. The method and result of this paper could be referred in the lunar minerals mapping of imaging spectrometer data such as M3. PMID:23427563

Yan, Bo-Kun; Li, Jian-Zhong; Gan, Fu-Ping; Yang, Su-Ming; Wang, Run-Sheng

2012-12-01

174

Carbon abundances in mantle minerals determined by nuclear reaction analysis  

NASA Astrophysics Data System (ADS)

Profiles of C concentration versus depth were determined in a spinel megacryst and two olivine crystals of a mantle xenolith from Kilbourne Hole, New Mexico, using the 12C(d,p)13C nuclear reaction technique. The 0-1400 Å layers of all crystals are characterized by C concentrations of ˜1000 wt. ppm. This C is interpreted to be a contaminant acquired during sample preparation or ion bombardment. Below the surface, measurable C concentrations were not found in the spinel and one of the olivine crystals, but a bulk C content of 425 ppm was measured for a second crystal. The latter is interpreted to be due to the presence of discrete C-rich phase(s) in submicroscopic inclusions or microcracks rather than C dissolved in the crystal lattice. The detection limit potentially obtainable by the (d,p) reaction technique for bulk C in minerals is several 10's of ppm.

Mathez, E. A.; Blacic, J. D.; Beery, J.; Maggiore, C.; Hollander, M.

1984-10-01

175

Carbon abundances in mantle minerals determined by nuclear reaction analysis  

SciTech Connect

Profiles of C concentration versus depth were determined in a spinel megacryst and two olivine crystals of a mantle xenolith from Kilbourne Hole, New Mexico, using the /sup 12/C(d,p)/sup 13/C nuclear reaction technique. The 0-1400 A layers of all crystals are characterized by C concentrations of approx.1000 wt. ppm. This C is interpreted to be a contaminant acquired during sample preparation or ion bombardment. Below the surface, measurable C concentrations were not found in the spinel and one of the olivine crystals, but a bulk C content of 425 ppm was measured for a second crystal. The latter is interpreted to be due to the presence of discrete C-rich phase(s) in submicroscopic inclusions or microcracks rather than C dissolved in the crystal lattice. The detection limit potentially obtainable by the (d,p) reaction technique for bulk C in minerals in several 10's of ppm.

Mathez, E.A.; Blacic, J.D.; Beery, J.; Maggiore, C.; Hollander, M.

1984-10-01

176

CLAY MINERALOGY OF INSOLUBLE RESIDUES IN MARINE EVAPORITES.  

USGS Publications Warehouse

Insoluble residues from three sequences of Paleozoic marine evaporites (Retsof salt bed in western New York, Salado Formation in south-eastern New Mexico, and Paradox Member of the Hermosa Formation in southeastern Utah) are rich in trioctahedral clays. Chlorite (clinochlore), corrensite (mixed-layer chlorite-trioctahedral smectite), talc, and illite (the only dioctahedral clay) are the dominant clay minerals; serpentine, discrete trioctahedral smectite (saponite), and interstratified talc-trioctahedral smectite are sporadically abundant. These clay-mineral assemblages differ chemically and mineralogically from those observed in most continental and normal marine rocks, which commonly contain kaolinite, dioctahedral smectite (beidellite-montmorillonite), illite, mixed-layer illite-dioctahedral smectite, and, in most cases, no more than minor quantities of trioctahedral clay minerals. The distinctive clay mineralogy in these evaporite sequences suggests a largely authigenic origin. These clay minerals are thought to have formed during deposition and early diagenesis through interaction between argillaceous detritus and Mg-rich marine evaporite brines.

Bodine, Jr. , Marc, W.

1985-01-01

177

Separation of patatins and protease inhibitors from potato fruit juice with clay minerals as cation exchangers.  

PubMed

Potato fruit juice as a by-product of the starch industry contains proteins with interesting functionalities such as protease inhibitors or patatin with its high nutritional value. Due to their functional properties, these proteins are principally of industrial interest. A drawback for the application of these potato proteins is the separation and isolation under maintenance of the biological activity. So far, there are no methods in literature, which are satisfying concerning the costs or the separation performance. In this study, we show a chromatographic approach using natural clay minerals as cation exchangers to separate two protein fractions in potato fruit juice. Additionally, the content of glycoalkaloids naturally occurring in potatoes is significantly reduced in a single step together with the separation of the patatins and the protease inhibitors. PMID:22761137

Ralla, Kathrin; Sohling, Ulrich; Suck, Kirstin; Kasper, Cornelia; Ruf, Friedrich; Scheper, Thomas

2012-07-01

178

NMR spectroscopic investigations of surface and interlayer species on minerals, clays and other oxides  

SciTech Connect

The behavior of chemical species adsorbed on solid surfaces and exchanged into clay interlayers plays a significant role in controlling many natural and technologically important processes, including rheological behavior, catalysis, plant growth, transport in natural pore fluids and those near anthropogenic hazardous waste sites, and water-mineral interaction. Adsorption and exchange reactions have been the focus of intense study for many decades. Only more recently, however, have there been extensive spectroscopic studies of surface species. Among the spectroscopic methods useful for studying surface and exchanged species (e.g., infrared, X-ray photoelectron spectroscopy [XPS] and X-ray absorption spectroscopy [XAS]), nuclear magnetic resonance spectroscopy (NMR) has the considerable advantage of providing not only structural information via the chemical shift and quadrupole coupling constant but dynamical information in the Hz-mHz range via lineshape analysis and relaxation rate measurements. It is also possible to obtain data in the presence of a separate fluid phase, which is essential for many applications. This paper illustrates the range of applications of NMR methods to surface and exchanged species through review of recent work from our laboratory on Cs in clay interlayers and Cs, Na and phosphate adsorbed on oxide surfaces. The substrate materials used for these experiments and our long-term objectives are related to problems of geochemical interest, but the principals and techniques are of fundamental interest and applicable to a wide range of technological problems.

Kirkpatrick, R.J.; Yeongkyoo Kim [Univ. of Illinois, Urbana, IL (United States). Department of Geology; Weiss, C.A. [Army Engineer Waterways Experiment Station, Vicksburg, MS (United States). Structures Laboratory; Cygan, R.T. [Sandia National Laboratories, Albuquerque, NM (United States)

1996-07-01

179

Anisotropy on the collective dynamics of water confined in swelling clay minerals.  

PubMed

Collective excitations of water confined in the interlayer space of swelling clay minerals were studied by means of inelastic neutron scattering. The effect of bidimensional confinement on the dynamics of the interlayer water was investigated by using a synthetic Na-saponite sample with a general formula of Si(7.3)Al(0.7)Mg(6)O(20)(OH)(4)Na(0.7) in a bilayer hydration state. Experimental results reveal two inelastic signals, different from those described for bulk water with a clear anisotropy on the low-energy excitation of the collective dynamics of interlayer water, this difference being stronger in the perpendicular direction. Results obtained for the parallel direction follow the same trend as bulk water, and the effect of the confinement is mainly manifested from the fact that clay interlayer water is more structured than bulk water. Data obtained in the perpendicular direction display a nondispersive behavior below a cutoff wavenumber value, Q(c), indicating a nonpropagative excitation below that value. Molecular dynamics simulations results agree qualitatively with the experimental results. PMID:22324768

Jiménez-Ruiz, M; Ferrage, E; Delville, A; Michot, L J

2012-03-01

180

Efficient nonlinear optical properties of dyes confined in interlayer nanospaces of clay minerals.  

PubMed

Nonlinear optical (NLO) responses from organic dyes can be maximized when the dyes are aligned in appropriate manners in bulk materials. The use of restricted nanospaces provided by interlayer spacing of inorganic layered materials is a promising strategy for imposing suitable molecular alignments for NLO materials on dyes. The hybrid materials thus obtained exhibit salient NLO responses owing to the improved molecular orientation. In some cases, extension of the ?-electron system as a consequence of improved molecular planarity, obtained by the intercalation of a dye into the 2-dimensional interlayer space of an inorganic layered material, is also observed as a factor that enhances NLO responses of chromophores at the molecular level. This review focuses on recent progress in the strategies for controlling the molecular orientation of NLO-phores by employing clay minerals, which are one of the typical inorganic layered materials. In addition, development of a means for fabricating composites that satisfy the properties of an optical material, such as a sufficient size and thickness, a flat surface, and low light-scattering characteristics is required to utilize the superior NLO properties observed for clay/dye hybrid materials for practical applications. A novel means for obtaining such a hybrid material is also outlined. PMID:22539109

Suzuki, Yasutaka; Tenma, Yuta; Nishioka, Yukihiro; Kawamata, Jun

2012-04-26

181

The origin of the pozzolanic activity of calcined clay minerals: A comparison between kaolinite, illite and montmorillonite  

SciTech Connect

This paper investigates the decomposition of three clayey structures (kaolinite, illite and montmorillonite) when thermally treated at 600 {sup o}C and 800 {sup o}C and the effect of this treatment on their pozzolanic activity in cementitious materials. Raw and calcined clay minerals were characterized by the XRF, XRD, {sup 27}Al NMR, DTG and BET techniques. Cement pastes and mortars were produced with a 30% substitution by calcined clay minerals. The pozzolanic activity and the degree of hydration of the clinker component were monitored on pastes using DTG and BSE-IA, respectively. Compressive strength and sorptivity properties were assessed on standard mortars. It was shown that kaolinite, due to the amount and location of OH groups in its structure, has a different decomposition process than illite or montmorillonite, which results in an important loss of crystallinity. This explains its enhanced pozzolanic activity compared to other calcined clay-cement blends.

Fernandez, Rodrigo, E-mail: fernandezrod@gmail.co [Laboratory of Construction Materials, IMX, Ecole Polytechnique Federale de Lausanne, 1015 Lausanne (Switzerland); Martirena, Fernando [Centro de Investigacion y Desarrollo de Estructuras y Materiales (CIDEM), Universidad Central 'Marta Abreu' de Las Villas, 54830 Santa Clara (Cuba); Scrivener, Karen L. [Laboratory of Construction Materials, IMX, Ecole Polytechnique Federale de Lausanne, 1015 Lausanne (Switzerland)

2011-01-15

182

Clay minerals and its influence on soil respiration in southern Brazil  

NASA Astrophysics Data System (ADS)

Carbon dioxide is the greenhouse gas with the highest concentration increases in the last century caused by human activities. Despite all the efforts, new investigations should be conducted in order to understand how agricultural management and its variations would impact on soil respiration and consequently in soils potential for carbon sequestration. Soil iron content is an important aspect of tropical soils, especially in sugarcane fields, that are located in regions where iron content in soil is among the highest concentrations in world. In this work we show that as iron content increases and changes its constitution FCO2 decreases monotonically. A transect was established on an acid oxisol in a direction where soil color changed from a yellow (10 YR), passing to a red (5 YR) and finishing with a dark red latosol (2.5 YR), in just 420 meters. Soil respiration was taken each 10 meters (42 points) while soil samples were extracted (0-20 cm) in each point for further soil property analysis. X-ray analysis shows that the goethite per hematite ratio and kaolinite per gibbsite ratio are directly related to soil respiration rates, and this is confirmed by spectroreflectance analysis performed in the same samples. Also, soils with iron clay minerals having lower degree of cristalinity were the ones having the higher soil respirations. Our study suggests a more complex relationship between clay minerals and biological activity, including soil iron level as an important factor in order to infer the ecological impact of tropical soil management in the biosphere. Due to the distinguishable characteristics of the Brazilian soils in terms of iron level, new experiments are needed to elucidate the relationship of iron content and CO2 loss in different classes of soils.

Marques, José, Jr.; Tadeu Pereira, Gener; La Scala, Newton, Jr.

2010-05-01

183

Reconstruction of late Quaternary monsoon oscillations based on clay mineral proxies using sediment cores from the western margin of India  

Microsoft Academic Search

In order to reconstruct the variations in the intensity of summer monsoon precipitation during the late Quaternary, two sediment cores from the southwestern continental margin of India were studied for their clay mineral composition and grain size parameters. Kaolinite, illite and gibbsite were dominant in a core off Cochin. Illite with increasing kaolinite content towards the core top was found

M Thamban; V Purnachandra Rao; R. R Schneider

2002-01-01

184

Clay minerals as palaeomonsoon proxies: Evaluation and relevance to the late Quaternary records from SE Arabian Sea  

Microsoft Academic Search

Palaeoclimatic studies are largely dependant on the quality of records and a prudent use of environmental proxy indicators. In this study, the factors affecting the detrital clay minerals in marine environment and their utility and reliability as palaeoclimatic proxies are evaluated and discussed Systematic investigations using several sediment cores from the SE Arabian Sea reveal that despite the influence of

M. THAMBAN; V PURNACHANDRA RAO

185

Chemical and structural analysis of enhanced biochars: thermally treated mixtures of biochar, chicken litter, clay and minerals.  

PubMed

In this study biochar mixtures comprising a Jarrah-based biochar, chicken litter (CL), clay and other minerals were thermally treated, via torrefaction, at moderate temperatures (180 and 220 °C). The objectives of this treatment were to reduce N losses from CL during processing and to determine the effect of both the type of added clay and the torrefaction temperature on the structural and chemical properties of the final product, termed as an enhanced biochar (EB). Detailed characterisation indicated that the EBs contained high concentrations of plant available nutrients. Both the nutrient content and plant availability were affected by torrefaction temperature. The higher temperature (220 °C) promoted the greater decomposition of organic matter in the CL and dissociated labile carbon from the Jarrah-based biochar, which produced a higher concentration of dissolved organic carbon (DOC). This DOC may assist to solubilise mineral P, and may also react with both clay and minerals to block active sites for P adsorption. This subsequently resulted in higher concentrations of plant available P. Nitrogen loss was minimised, with up to 73% of the initial total N contained in the feedstock remaining in the final EB. However, N availability was affected by both torrefaction temperature and the nature of the clay minerals added. PMID:23270707

Lin, Y; Munroe, P; Joseph, S; Ziolkowski, A; van Zwieten, L; Kimber, S; Rust, J

2012-12-25

186

Rapid Determination of Mineral Abundance by X-ray Microfluorescence Mapping and Multispectral Image Analysis  

Microsoft Academic Search

X-ray microfluorescence (XRMF) spectrometry is a rapid, accurate technique to map element abundances of rock surfaces (such as thin-section billets, the block remaining when a thin section is prepared). Scanning a specimen with a collimated primary X-ray beam (100 mum diameter) generates characteristic secondary X-rays that yield the relative chemical abundances for the major rock-\\/mineral-forming analytes (such as Si, Al,

R. J. Moscati; B. D. Marshall

2005-01-01

187

Rapid Determination of Mineral Abundance by X-ray Microfluorescence Mapping and Multispectral Image Analysis  

NASA Astrophysics Data System (ADS)

X-ray microfluorescence (XRMF) spectrometry is a rapid, accurate technique to map element abundances of rock surfaces (such as thin-section billets, the block remaining when a thin section is prepared). Scanning a specimen with a collimated primary X-ray beam (100 ?m diameter) generates characteristic secondary X-rays that yield the relative chemical abundances for the major rock-/mineral-forming analytes (such as Si, Al, K, Ca, and Fe). When Cu-rich epoxy is used to impregnate billets, XRMF also can determine porosity from the Cu abundance. Common billet scan size is 30 x 15 mm and the typical mapping time rarely exceeds 2.5 hrs (much faster than traditional point-counting). No polishing or coating is required for the billets, although removing coarse striations or gross irregularities on billet surfaces should improve the spatial accuracy of the maps. Background counts, spectral artifacts, and diffraction peaks typically are inconsequential for maps of major elements. An operational check is performed after every 10 analyses on a standard that contains precisely measured areas of Mn and Mo. Reproducibility of the calculated area ratio of Mn:Mo is consistently within 5% of the known value. For each billet, the single element maps (TIFF files) generated by XRMF are imported into MultiSpec© (a program developed at Purdue University for analysis of multispectral image data, available from http://dynamo.ecn.purdue.edu/~biehl/MultiSpec/) where mineral phases can be spectrally identified and their relative abundances quantified. The element maps for each billet are layered to produce a multi-element file for mineral classification and statistical processing, including modal estimates of mineral abundance. Although mineral identification is possible even if the mineralogy is unknown, prior petrographic examination of the corresponding thin section yields more accurate maps because the software can be set to identify all similar pixels. Caution is needed when using MultiSpec© to distinguish mineral phases with similar chemistry (for example, opal and quartz) and minerals that occupy very small surface areas (<10 pixels). In either case, careful petrography and informed use of the software will allow rapid use of MultiSpec© to create accurate mineral maps of rock and thin-section billet surfaces. This technique, for example, has allowed quantitative estimates of calcite and silica abundances to be determined on about 200 samples of secondary mineral coatings from the unsaturated zone at Yucca Mountain, Nevada.

Moscati, R. J.; Marshall, B. D.

2005-12-01

188

Radiation sensitivity of natural organic matter: Clay mineral association effects in the Callovo-Oxfordian argillite  

Microsoft Academic Search

Clay-rich low-organic carbon formations (e.g., Callovo-Oxfordian argillite in France and Opalinus Clay in Switzerland) are considered as host rocks for radioactive waste disposal. The clay-organic carbon has a strong impact on the chemical stability of the clays. For this reason, the nature of the clay-organic carbon, the release of hydrophilic organic compounds, namely, humic (HA) and fulvic acids (FA) and

T. Schäfer; P. Michel; F. Claret; T. Beetz; S. Wirick; C. Jacobsen

2009-01-01

189

Effect of Clay Minerals on Immobilization of Heavy Metals and Microbial Activity in a Sewage Sludge-Contaminated Soil (8 pp)  

Microsoft Academic Search

Conclusions. Our results clearly show that the addition of clay minerals, especially of Na-bentonite and Ca-bentonite, decreased the extractability of four metals during incubation. The decreased metal extractability was accompanied by an increase of soil respi- ration, Corg mineralization, microbial biomass C, and inorganic N and a decrease of metabolic quotient (qCO 2 ), showing positive effect of clay mineral

Adel Usman; Yakov Kuzyakov; Karl Stahr

2005-01-01

190

Clay Minerals of Suspended Matter and Surficial Sediments of Khor Al-Zubair Estuary, NW Arabian Gulf  

NASA Astrophysics Data System (ADS)

Distribution of clay minerals in the suspended matter and surficial sediments of 36 samples collected from Khor Al-Zubair estuary revealed the presence of montimorillonite, kaolinite, chlorite, illite and palygorskite in wide variations. These variations are interpreted to be due to: different source areas of these minerals, the complex hydrodynamic conditions in the Khor and to flocculation. No regular distribution of clay minerals (except for montimorillonite) was found in the water samples. In the sediments samples montimorillonite and palygorskite showed a trend of increasing values toward the Arabian Gulf, which interpreted to be brought by Shatt Al-Arab River and/or formed diagenetically. Kaolinite and chlorite increased landward due to eolian effect. Illite values showed an increment near Shatt Al-Basrah Canal caused by the sediments brought by the Euphrates River from Hor Al-Hammar Lake.

Al-Mussawy, Sabah N.; Basi, Muzahim A.

1993-02-01

191

Environmental Weathering of Aluminosilicate Clay Minerals: Solid-State NMR Studies of Transformations Leading to Radionuclide Sequestration  

SciTech Connect

Mobilities of radionuclides (such as 137Cs and 90Sr) are governed by their interactions with natural soil particles in the saturated and unsaturated zones at Department of Energy sites. High surface area aluminosilicate clay minerals are a component of the natural soils beneath the leaking waste tanks at these sites and serve as possible radionuclide sorbents. However, due to the characteristics of the contaminant medium (high pH, high Al and high ionic strength), clay minerals are susceptible to transformations during exposure to tank waste leachates. We are currently studying the transformation of clays under specific chemical conditions that mimic the composition of known contaminant solutions. In these studies, specimen clay samples are reacted for varying time periods (up to one year) with simulated tank waste leachate solutions. Mineral dissolution and transformation are followed with solution analysis, x-ray diffraction and a number of other analytical methods. We report here results from 27Al MAS NMR at variable magnetic field strengths (up to 18.8 T), 29Si MAS NMR and 1H/29Si CPMAS NMR and evaluate these results along with those of other parallel analytic studies.

Mueller, Karl T.; Crosson, Garry; Chorover, Jon; Choi, Sunkyung

2004-03-28

192

Metal oxides, clay minerals and charcoal determine the composition of microbial communities in matured artificial soils and their response to phenanthrene.  

PubMed

Microbial communities in soil reside in a highly heterogeneous habitat where diverse mineral surfaces, complex organic matter and microorganisms interact with each other. This study aimed to elucidate the long-term effect of the soil mineral composition and charcoal on the microbial community composition established in matured artificial soils and their response to phenanthrene. One year after adding sterile manure to different artificial soils and inoculating microorganisms from a Cambisol, the matured soils were spiked with phenanthrene or not and incubated for another 70 days. 16S rRNA gene and internal transcribed spacer fragments amplified from total community DNA were analyzed by denaturing gradient gel electrophoresis. Metal oxides and clay minerals and to a lesser extent charcoal influenced the microbial community composition. Changes in the bacterial community composition in response to phenanthrene differed depending on the mineral composition and presence of charcoal, while no shifts in the fungal community composition were observed. The abundance of ring-hydroxylating dioxygenase genes was increased in phenanthrene-spiked soils except for charcoal-containing soils. Here we show that the formation of biogeochemical interfaces in soil is an ongoing process and that different properties present in artificial soils influenced the bacterial response to the phenanthrene spike. PMID:23336569

Babin, Doreen; Ding, Guo-Chun; Pronk, Geertje Johanna; Heister, Katja; Kögel-Knabner, Ingrid; Smalla, Kornelia

2013-01-21

193

Orientation and optical properties of methylene blue crystal for better understanding of interactions with clay mineral surface  

NASA Astrophysics Data System (ADS)

The properties of cationic dye Methylene blue (MB) adsorbed on diferent surfaces have been investigated intensively over the years and various models for the orientation of its cations have been proposed (Hang and Brindley, 1970; Bujdak et al., 2003; Li and Zare, 2004; Marr III et al., 1973; Bujdak, 2006).The main objective of this work is to investigate and determine orientation and optical properties of metylene blue crystal upon its crystallization on a glass slate and to use those findings in better understanding of interactions with clay minerals. Cationic dyes have very high affinity for clay surfaces and those interactions are easily detected, therefore these dyes are used to determine several properties of clay surfaces (morphology, layer charge, CEC). For this study, we have selected a group of MB crystal and carried out XRD analysis, polarized absorption spectra measurement (400 - 900 nm) and determination of optical properties (pleochroism, determination of twining and extinction angle) using polarizing microscope. Methylene blue crystals are exhibiting mostly needle like habitus with huge difference in width - length ratio. According to X-ray diffraction it is quite obvious that the y (b) axis is perpendicular to the crystal surface. The x (a) and z (c) axis lie in the crystal plane (010). Crystals exhibit prominent dichroism: from blue (E || elong.) to colorless. In accordance with current interpretation of MB spectra peaks at 647 and 570 nm can be assigned as dimer aggregation and peaks at 475 and 406 nm as higher level of aggregation. All of them exhibit pronounced polarization dependence. The group of peaks at lower energy (700 to 900 nm) do not show significant polarization dependence and they correspond to the J - aggregates. Peak at around 800 nm have been noticed as fluorescence active. In dependence with thickness of the crystals and vibration direction we have observed presence of polysynthetic twinning which can be compared with polysynthetic twinning of feldspar minerals. Final result of molecular polymerization is represented as crystal framework of methylene blue. Model of the MB molecular aggregation in the crystal structure could be used as a way for the interpretation of the thin layer structure and the molecular aggregation on the clay surface. References - Hang P.T. & Brindley G.W., (1970), Clays and Clay Minerals, 18, 203-212. - Bujdak J., Iyi N., Kaneko Y. and Sasai R., (2003), Clay Minerals (2003), 38, 561-572. - Li F. and Zare R.N., (2005), J. Phys. Chem. B 2005, 109, 3330-3333. - Marr III, H.E., Stewart, J.M. and Chiu, M.F., (1973), Acta Cryst. (1973), B29, 847. - Bujdak J., (2006), Applied Clay Science 34 (2006) 58 - 73

Miloševi?, Maja; Logar, Mihovil

2013-04-01

194

Heavy metals alter the electrokinetic properties of bacteria, yeasts, and clay minerals  

SciTech Connect

The electrokinetic patterns of four bacterial species (Bacillus subtilis, Bacillus megaterium, Pseudomonas aeruginosa, and Agrobacterium radiobacter), two yeasts (Saccharomyces cerevisiae and Candida albicans), and two clay minerals (montmorillonite and kaolinite) in the presence of the chloride salts of the heavy metals, Cd, Cr, Cu, Hg, Ni, Pb, and Zn, and of Na and Mg were determined by microelectrophoresis. The cells and kaolinite were net negatively charged at pH values above their isoelectric points (pI) in the presence of Na, Mg, Hg, and Pb at an ionic strength ([mu]) of 3 [times] 10[sup [minus]4]; montmorillonite has no pI and was net negatively charged at all pH values in the presence of these metals. However, the charge of some bacteria, S. cerevisiae, and kaolinite changed to a net positive charge (charge reversal) in the presence of Cd, Cr, Cu, Ni, and Zn at pH values above 5.0 and then at higher pH values, again became negative. The charge of the bacteria and S. cerevisiae also reversed in solutions of Cu and Ni with a [mu] of >3 [times] 10[sup [minus]4], whereas there was no reversal in solutions with a [mu] of <3 [times] 10[sup [minus]4]. The clays became net positively charged when the [mu] of Cu was >3 [times] 10[sup [minus]4] and that of Ni was >1.5 [times] 10[sup [minus]4]. The charge of the cells and clays also reversed in solutions containing both Mg and Ni or both Cu and Ni (except montmorillonite) but not in solutions containing both Mg and Cu (except kaolinite). The pIs of the cells in the presence of the heavy metals were at either higher or lower pH values than in the presence of Na and Mg. Exposure of the cells to the various metals at pH values from 2 to 9 for the short times (ca. 10 min) required to measured the electrophoretic mobility did not affect their viability.

Collins, Y.E.; Stotzky, G. (New York Univ., NY (United States))

1992-05-01

195

Lead exchange into zeolite and clay minerals: A 29Si, 27Al, 23Na solid-state NMR study  

NASA Astrophysics Data System (ADS)

Chabazite, vermiculite, montmorillonite, hectorite, and kaolinite were used to remove Pb, through ion exchange, from 0.01 M aqueous Pb(NO 3) 2 solutions. These minerals contained 27 (Nachabazite), 16, 9, 9, and 0.4 wt% of Pb, respectively, after equilibration with the solutions. Ion exchange reached equilibrium within 24 h for Na-chabazite and vermiculite, but in less than 5 min for montmorillonite and hectorite. Na-chabazite took up more Pb than natural (Ca, Na)-chabazite (7 wt% Pb), whereas no such difference was observed in different cation forms of the clay minerals. Calcite impurities, associated with the clay minerals, effectively removed Pb from the aqueous solutions by the precipitation of cerussite (PbCO 3). 29Si, 27Al, and 23Na magic angle spinning (MAS) nuclear magnetic resonance (NMR), 23Na double rotation (DOR) NMR, and 23Na variable-temperature MAS NMR were used to study the ion exchange mechanisms. In Na-chabazite, cations in all three possible sites take part in the fast chemical exchange. The chemical exchange passes from the fast exchange regime to the slow regime at -80 to -100°C. One site contains a relatively low population of exchangeable cations. The other two more shielded sites contain most of the exchangeable cation. The exchangeable cations in chabazite and vermiculite were found to be close to the SiO 4 and AlO 4 tetrahedra, while those in the other clay minerals were more distant. Two sites (or groups of sites) for exchangeable cations were observed in hectorite. Lead tended to occupy the one which corresponds to the -8 ppm peak on the 23Na MAS NMR spectrum. The behaviour of the exchangeable cations in the interlayer sites was similar in all the clay minerals studied.

Liang, Jian-Jie; Sherriff, Barbara L.

196

Evaluation of the medicinal use of clay minerals as antibacterial agents  

Microsoft Academic Search

Natural clays have been used to heal skin infections since the earliest recorded history. Recently, our attention was drawn to a clinical use of French green clay (rich in Fe?smectite) for healing Buruli ulcer, a necrotizing fasciitis (‘flesh-eating’ infection) caused by Mycobacterium ulcerans. These clays and others like them are interesting as they may reveal an antibacterial mechanism that could

Lynda B. Williams; Shelley E. Haydel

2010-01-01

197

Binding of organic matter into an oxidation-resistant form during the interaction of clay minerals with plant residues  

NASA Astrophysics Data System (ADS)

The binding of organic matter by clay minerals was studied in experiments simulating the transformation of clay rock with a high content of dioctahedral 2: 1 phases in the soil during its interaction with decomposing plant residues. Using modern methods (X-ray phase analysis, thermal analysis and Fouriertransform IR spectroscopy, and adsorption-luminescence analysis), it was shown that the binding of organic matter into a form resistant to treatment with 30% H2O2 entailed changes in the actual structure of the clay aggregates. Peculiar organic-silicate compositions with their structure disordered along the c* axis were formed, in which organic matter was localized both on the surface of the particles and in the interlayer spaces.

Giniyatullin, K. G.; Shinkarev, A. A.; Shinkarev, A. A.; Krinari, G. A.; Lygina, T. Z.; Gubaidullina, A. M.; Suchkova, G. G.

2010-10-01

198

Simulation of the nucleation and growth of clay minerals coupled with cation exchange  

NASA Astrophysics Data System (ADS)

We present a treatment of the cation exchange capacity (CEC) of clays in contact with an aqueous solution, during precipitation, using an ideal solid solution approach. It combines in a single calculation short term processes such as cation exchange and long term reactions like precipitation. This approach has been implemented and optimized in a new version of the NANOKIN code, which is thus now able to provide the time dependence of all particle sizes, composition and precipitated amount, as well as aqueous solution activities, pH and saturation states. It has been applied to the description of montmorillonite and illite precipitation from aqueous solutions at different temperatures and initial conditions: (1) an initial supersaturation with an aqueous solution composition which mimics a fresh water at T = 25 °C, a sea water at the same temperature, and an hydrothermal fluid at T = 150 °C; (2) a progressive supersaturation resulting from the kinetic dissolution of granitic rock-forming minerals, under weathering or hydrothermal conditions. The competition between illites and montmorillonites known in these various environments is well reproduced, as well as their dominant cation composition and typical particle sizes.

Noguera, C.; Fritz, B.; Clément, A.

2011-06-01

199

Mineral-produced high-pressure striae and clay polish: Key evidence for nonballistic transport of ejecta from Ries crater  

USGS Publications Warehouse

Recently discovered mineral-produced, deeply incised striae and mirror-like polish on broken surfaces of limestone fragments from the sedimentary ejecta of the Ries impact crater of southern Germany are described. The striae and polish were produced under high confining pressures during high-velocity nonballistic transport of the ejecta mass within the time span of the cratering event (measured in terms of seconds). The striae on these fragments were produced by scouring by small mineral grains embedded in the surrounding clay matrix, and the polish was formed under the same condition, by movements of relatively fragment-free clay against the fragment surfaces. The occurrence of these striae and polish is key evidence for estimating the distribution and determining the relative importance of nonballistic and ballistic transport of ejecta from the shallow Ries stony meteorite impact crater.

Chao, E. C. T.

1976-01-01

200

Mineral-fixed ammonium in clay- and silt-size fractions of soils incubated with 15 N-ammonium sulphate for five years  

Microsoft Academic Search

Four soils with 6, 12, 23, and 47% of clay were incubated for 5 years with 15N-labeled (NH42SO4 and hemicellulose. The incubations took place at 20°C and 55% water-holding capacity. Samples of whole soils, and clay- (r2 = 0.997). After 5 years of incubation, the content of mineral-fixed ammonium in the clay fraction was 255–430 µg N g-1, corresponding to

E. S. Jensen; B. T. Christensen; L. H. Sørensen

1989-01-01

201

Reduction and long-term immobilization of technetium by Fe(II) associated with clay mineral nontronite  

Microsoft Academic Search

99Tc is formed mostly during nuclear reactions and is released into the environment during weapons testing and inadvertent waste disposal. The long half-life, high environmental mobility (as Tc(VII)O4?) and its possible uptake into the food chain cause 99Tc to be a significant environmental contaminant. In this study, we evaluated the role of Fe(II) in biologically reduced clay mineral, nontronite (NAu-2),

Deb P. Jaisi; Hailiang Dong; Andrew E. Plymale; James K. Fredrickson; John M. Zachara; Steve Heald; Chongxuan Liu

2009-01-01

202

Clay minerals in SW Indian continental shelf sediment cores as indicators of provenance and palaeomonsoonal conditions: a statistical approach  

Microsoft Academic Search

Two sediment cores from the inner continental shelf of SW India, SK?148\\/13 (4.66 m long; from 50 m water depth) and SK?148\\/14 (5.37 m long; from 22 m water depth), were studied for provenance and palaeomonsoonal implications. Sediment layers at different depth intervals in these cores were estimated for clay minerals and organic matter content. Five surface sediment samples from the nearby Kali River

K. Pandarinath

2009-01-01

203

Redox properties of structural Fe in clay minerals. 1. Electrochemical quantification of electron-donating and -accepting capacities of smectites.  

PubMed

Clay minerals often contain redox-active structural iron that participates in electron transfer reactions with environmental pollutants, bacteria, and biological nutrients. Measuring the redox properties of structural Fe in clay minerals using electrochemical approaches, however, has proven to be difficult due to a lack of reactivity between clay minerals and electrodes. Here, we overcome this limitation by using one-electron-transfer mediating compounds to facilitate electron transfer between structural Fe in clay minerals and a vitreous carbon working electrode in an electrochemical cell. Using this approach, the electron-accepting and -donating capacities (Q(EAC) and Q(EDC)) were quantified at applied potentials (E(H)) of -0.60 V and +0.61 V (vs SHE), respectively, for four natural Fe-bearing smectites (i.e., SWa-1, SWy-2, NAu-1, and NAu-2) having different total Fe contents (Fe(total) = 2.3 to 21.2 wt % Fe) and varied initial Fe(2+)/Fe(total) states. For every SWa-1 and SWy-2 sample, all the structural Fe was redox-active over the tested E(H) range, demonstrating reliable quantification of Fe content and redox state. Yet for NAu-1 and NAu-2, a significant fraction of the structural Fe was redox-inactive, which was attributed to Fe-rich smectites requiring more extreme E(H)-values to achieve complete Fe reduction and/or oxidation. The Q(EAC) and Q(EDC) values provided here can be used as benchmarks in future studies examining the extent of reduction and oxidation of Fe-bearing smectites. PMID:22827605

Gorski, Christopher A; Aeschbacher, Michael; Soltermann, Daniela; Voegelin, Andreas; Baeyens, Bart; Marques Fernandes, Maria; Hofstetter, Thomas B; Sander, Michael

2012-08-23

204

Geoscientific Applications of Particle Detection and Imaging Techniques withSpecial Focus on the Monitoring Clay Mineral Reactions  

NASA Astrophysics Data System (ADS)

The combined use of focused X-ray, electron, and ion beams offers a diverse range of analytical capabilities for characterizing nanoscale mineral reactions that occur in hydrous environments. Improved image and microanalytical techniques (e.g., electron diffraction and energy-dispersive X-ray spectroscopy), in combination with controlled sample environments, are currently leading to new advances in the understanding of fluid-mineral reactions in the Earth Sciences. One group of minerals playing a key role in the containment of radioactive waste and the underground storage of CO2 is the clay minerals: these small, expandable, and highly adsorbent hydrous phyllosilicates form important low-permeable geological barriers by which waste can be safely deposited. In this article we summarize some of the state-of-the-art particle and imaging techniques employed to predict the behavior of both engineered and natural clay mineral seals in proposed storage sites. Particular attention is given to two types of low-permeability geomaterials: engineered bentonite backfill and natural shale in the subsurface. These materials have contrasting swelling properties and degrees of chemical stability that require detailed analytical study for developing suitable disposal or storage solutions.

Warr, Laurence N.; Grathoff, Georg H.

205

Structural characterization of the montmorillonite clay nanometric particles  

Microsoft Academic Search

In this work we characterize the clays of a place named “Las Pulgas”, in the Charo Canyon, State of Michoacan, Mexico. It is found that these mineral species are mainly montmorillonite, cristobalite, tridimite and albite, including quartz. Montmorillonite is the most abundant clay in this region, and has a nanometric twinned small particle habit. All this opens a potential technical

G. Carbajal De la Torre; I. Israde Alcántara; M. A. Espinosa Medina; J. Serrato; A. Negron-Mendoza; S. Ramos; G. Albarrán; J. Reyes-Gasga

1997-01-01

206

Effects of mineral distribution at mesoscopic scale on solute diffusion in a clay-rich rock: Example of the Callovo-Oxfordian mudstone (Bure, France)  

NASA Astrophysics Data System (ADS)

The mesostructure (millimeter to micrometer scale) of clay-rich sedimentary rocks is generally characterized by a connected fine-grained clay matrix embedding coarser nonclay minerals. We use the Callovo-Oxfordian clay-rich rock formation (France) to illustrate how mesostructure influences solute transfer in clay-rich rocks at larger scales. Using micrometer resolution imaging techniques (SEM and micro-CT) major mineral phases (clay matrix, carbonates, tectosilicates, and heavy minerals) were mapped both in two dimensional (2-D) and three dimensional (3-D) at the mesoscale. Orientation and elongation distributions of carbonate and tectosilicate grains measured on mineral maps reveal an anisotropic mesostructure relative to the bedding plane, in agreement with the geological history of the sedimentary rock. Diffusion simulations were performed based on the 3-D mineral maps using a random walk method thus allowing direct computation of mesoscopic scale-related diffusion anisotropy and tortuosity. Considering an isotropic clay matrix, simulated diffusion anisotropy (1.11-1.26) was found lower than the one experimentally measured on macroscopic samples (1.5 to 2), due to the anisotropy feature of pores within the clay matrix. The effects of the mineral content variations on diffusion properties were then investigated by numerical modifications of a mineral map combined with diffusion simulations. Evolution of the tortuosity and diffusion anisotropy with the clay matrix content were successfully interpreted by the Koponen percolation/diffusion model, whereas the Archie approach fails to reproduce diffusion properties at low clay contents. A comparison of fitting parameters with those obtained experimentally indicates that diffusion coefficient variations observed at a large scale could be mainly controlled by the mesostructure.

Robinet, Jean-Charles; Sardini, Paul; Coelho, Daniel; Parneix, Jean-Claude; Prêt, Dimitri; Sammartino, StéPhane; Boller, Elodie; Altmann, Scott

2012-05-01

207

Mineralogy, crystallinity and stable isotopic composition of illitic clays within the Polish Zechstein basin: implications for the genesis of Kupferschiefer mineralization  

Microsoft Academic Search

The Permian siliciclastic Kupferschiefer of Poland is the host for economically important Cu-Ag deposits. Within the Kupferschiefer of the Polish Zechstein basin, mineralogical and detailed stable isotopic analyses of clay minerals, quartz and calcite show that the metal enrichment processes are associated with significant changes in oxygen and hydrogen isotope composition of the illitic clays, with a decrease in illite

A. Bechtel; Y.-N. Shieh; W. C. Elliott; S. Oszczepalski; S. Hoernes

2000-01-01

208

Deformation characteristics and associated clay-mineral variation in 2-3 km buried Hota accretionary complex, central Japan  

NASA Astrophysics Data System (ADS)

Although deformation and physical/chemical properties variation in aseismic-seismic transition zone were essential to examine critical changes in environmental parameters that result in earthquake, they are poorly understood because the appropriate samples buried 2-4 km have not been collected yet (scientific drilling has never reached there and most of ancient examples experienced the deeper burial depth and suffered thermal and physical overprinting). The lower to middle Miocene Hota accretionary complex is a unique example of on land accretionary complex, representing deformation and its physical/chemical properties of sediments just prior to entering the seismogenic realm. The maximum paleotemperature was estimated approximately 55-70°C (based on vitrinite reflectance) indicative of a maximum burial depth about 2-3 km assuming a paleo-geothermal gradient as 25-35°C/km. Accretionary complex in this temperature/depth range corresponds with an intermediate range between the core samples collected from the modern accretionary prism (e.g. Nankai, Barbados, and so on) and rocks in the ancient accretionary complexes on land. This presentation will treat the detailed structural and chemical analyses of the Hota accretionary complex to construct deformation properties of décollement zone and accretionary complex in its 2-3 km depth range and to discuss the interrelation between the early diagenesis (hydrocarbon/cations generation and sediment dewatering, etc.) and transition of the deformation properties. The deformation in this accretionary complex is characterized by two deformation styles: one is a few centimeter-scale phacoidal deformation representing clay minerals preferred orientation in the outer rim, whereas random fabric in the core, quite similar texture to the rocks in the present-Nankai décollement. The other is S-C style deformation (similar deformation to the mélanges in ancient accretionary complex on land) exhibiting block-in-matrix texture and quite intense clay minerals preferred orientation in the matrix, cutting the phacoidal deformation. The host and faulted (S-C structure) rocks composed of hemipelagic siltstone containing 70-80% of clay minerals. Considerable-smectite reduction and positive anomaly of illite/smectite ratio were clearly identified inside the latter S-C structure, which would cause remarkable increase in friction coefficient. Such strain hardening associated with dynamic clay-mineral variation would be the primary mechanism in décollement -zone and/or mélange-zone thickening and fundamental mechanical transition just prior to entering the seismogenic zone. Positive anomaly of the vitrinite reflectance data (Ro) inside infers frictional heating during the deformation plausibly caused the clay mineral variation.

Yamamoto, Y.; Kameda, J.; Yamaguchi, H.

2009-12-01

209

Intercalation of TCE by Sediment-Associated Clay Minerals and Implications for Low-Concentration Elution Tailing and Back Diffusion  

NASA Astrophysics Data System (ADS)

Pump-and-treat systems are widely used to remediate hazardous waste sites wherein groundwater is contaminated by compounds such as TCE (trichloroethene). It is well known that removal of contaminant mass by pump and treat becomes less effective over time, with a persistent mass discharge causing greatly extended operational periods. One mechanism potentially responsible for this persistent mass discharge is "back diffusion", wherein dissolved contaminant stored in lower-permeability layers diffuses into the higher-permeability zones that are more readily swept via pump and treat. Because the lower-permeability layers typically contain high fractions of clay minerals, a question of great interest is whether contaminant-clay interactions may influence the back-diffusion process. For example, intercalation of TCE into the interlayer spaces of clay minerals could potentially exacerbate diffusive mass-transfer limitations. The primary objectives of this research were to evaluate the long-term elution of TCE from aquifer sediments, and to examine the potential for TCE intercalation. Sediment samples were collected from a TCE-contaminated field site in Tucson, AZ. A widely used Na- Montmorillonite specimen clay was used as a control. Miscible-displacement experiments were conducted to characterize TCE elution behavior. X-ray diffraction, conducted with a controlled environment chamber, was used to characterize smectite interlayer d-spacing for three treatments (bulk dry sample, sample mixed with synthetic groundwater, sample mixed with TCE-saturated synthetic groundwater). Extensive elution tailing was observed for the column experiments. Results of the XRD analysis indicate a greater d-spacing for the samples treated with TCE-saturated synthetic groundwater for all field samples as well as the specimen clay.

Matthieu, D. E.; Brusseau, M. L.; Bowden, M. E.; Johnson, G. R.; Artiola, J. F.; Curry, J. E.

2011-12-01

210

Carbonation of Clay Minerals Exposed to scCO2/Water at 200 degrees and 250 degrees C  

SciTech Connect

To clarify the mechanisms of carbonation of clay minerals, such as bentonite, kaolinite, and soft clay, we exposed them to supercritical carbon dioxide (scCO2)/water at temperatures of 200 and 250 C and pressures of 1500 and 2000 psi for 72- and 107-hours. Bentonite, comprising three crystalline phases, montmorillonite (MMT), anorthoclase-type albite, and quartz was susceptible to reactions with ionic carbonic acid yielded by the interactions between scCO2 and water, particularly MMT and anorthoclase-type albite phases. For MMT, the cation-exchangeable ions, such as Na+ and Ca2+, present in its basal interplanar space, were replaced by proton, H+, from ionic carbonic acid; thereafter, the cations leaching from MMT directly reacted with CO32- as a counter ion of H+ to form carbonate compounds. Such in-situ carbonation process in basal space caused the shrinkage and breakage of the spacing structure within MMT. In contrast, the wet carbonation of anorthoclase-type albite, categorized as rock minerals, entailed the formation of three amorphous by-products, such as carbonates, kaolinite-like compounds, and silicon dioxide. Together, these two different carbonations caused the disintegration and corruption of bentonite. Kaolinite clay containing the amorphous carbonates and silicon dioxide was inert to wet carbonation. We noted only a gain in weight due to its water uptake, suggesting that kaolinite-like by-products generated by the wet carbonation of rock minerals might remain unchanged even during extended exposure. Soft clay consisting of two crystalline phases, dolomite and silicon dioxide, also was unaltered by wet carbonation, despite the uptake of water.

Sugama, T.; Ecker, L.; Gill, S.; Butcher, T. (BNL); Bour, D. (AltaRock Energy, Inc.)

2010-11-01

211

Interaction of water with clay minerals as studied by 2H nuclear magnetic resonance spectroscopy  

NASA Astrophysics Data System (ADS)

The interaction of water with a series of Ca 2+/Na + , Ca 2+/NH 4+, and NH 4+/Na +-exchanged hectorite and saponite clays in water- and clay-dominated systems was studied using 2H NMR. Variabletemperature Nuclear Magnetic Resonance (NMR) (in the range of 189-299 K) was also used to determine the frequency of exchange and the rotation activation energy between water molecules hydrating the cations and the free water of the tactoid. The 2H quadrupolar splitting and spin-lattice relaxation time ( T1) are related to the ratio of clay to adsorbed water in these systems. In water-dominated systems (where clay/water ratio ? 1), motional averaging occurs between water hydrating the cations and the "free" or bulk water of the tactoid. In these systems, the spin-lattice relaxation time ( T1) is dominated by the relaxation of the "free" water on the external surface of the tactoids and has a value close to that for D 2O (0.436 s), with the rotational correlation time ( ?c) approaching 2.93 × 10 -12 s. A more recent article places ?c at 1.95 × 10 -12 s. The clay systems in this study have clay/ water ratios (=0.0238 g-clay/mL-D 2O), and the quadrupolar splittings are of the order of 100 Hz or less. Splittings of <100 Hz indicate that approximately 1 water molecule is bound to the clay for every 1.7 × 10 3 "free" water molecules. In clay-dominated systems with extremely low water contents (clay/water ratio > 1 g-clay/mL-D 2O), less motional averaging occurs. Rotational correlation times are slower and greater residual quadrupolar splittings are also observed. Increased residual quadrupolar splittings are observed with increasing clay/ water ratios. For a Na-exchanged hectorite sample (5.31 g-clay/mL-D 2O), the quadrupolar splittings are of the order of 12 kHz, and for a Na-exchanged saponite (4.05 g-clay/mL-D 2O), the quadrupolar splittings are of the order of 11 kHz. Rotational activation energies (E a) of 37.8 kJ-mole -1 (9.0 kcal · mole -1) for adsorbed water molecules on Na-exchanged hectorite and 27.2 kJ · mole -1 (6.5 kcal · mole" -1) for Na-exchanged saponite were calculated from spin-lattice relaxation ( T1) measurements. These values compare with calculated activation energies of rotation (8.5 kcal · mole -1) for water of hydration adsorbed to a Na-exchanged vermiculite.

Weiss, Charles A.; Gerasimowicz, Walter V.

1996-01-01

212

[Mineralogy and genesis of mixed-layer clay minerals in the Jiujiang net-like red soil].  

PubMed

Mineralogy and genesis were investigated using X-ray diffraction (XRD), Fourier infrared absorption spectroscopy (FTIR) and high resolution transmission electron microscopy (HRTEM) to understand the mineralogy and its genesis significance of mixed-layer clay minerals in Jiujiang red soil section. XRD and FTIR results show that the net-like red soil sediments are composed of illite, kaolinite, minor smectite and mixed-layer illite-smectite and minor mixed-layer kaolinite-smectite. HRTEM observation indicates that some smectite layers have transformed into kaolinite layers in net-like red soil. Mixed-layer illite-smectite is a transition phase of illite transforming into smectite, and mixed-layer kaolinite-smectite is a transitional product relative to kaolinite and smectite. The occurrence of two mixed-layer clay species suggests that the weathering sequence of clay minerals in net-like red soil traversed from illite to mixed-layer illite-smectite to smectite to mixed-layer kaolinite-smectite to kaolinite, which indicates that net-like red soil formed under a warm and humid climate with strengthening of weathering. PMID:23285883

Yin, Ke; Hong, Han-Lie; Li, Rong-Biao; Han, Wen; Wu, Yu; Gao, Wen-Peng; Jia, Jin-Sheng

2012-10-01

213

Vesta and the HED meteorites: Mid-infrared modeling of minerals and their abundances  

NASA Astrophysics Data System (ADS)

We demonstrate that the use of an established spectral deconvolution algorithm with midinfrared spectral libraries of mineral separates of varying grain sizes is capable of identifying the known mineral compositions and abundances of a selection of howardite, eucrite, and diogenite (HED) meteorite samples. In addition, we apply the same technique to mid-infrared spectral emissivity measurements of Vesta that have been obtained from Cornell’s Mid-Infrared Asteroid Spectroscopy (MIDAS) Survey and the Infrared Space Observatory (ISO). Each Vesta measurement was made over a different range of longitudes. Our spectral deconvolution results to the Vesta spectra corroborate that Vesta’s surface is howardite or eucrite-like in composition and heterogeneous across its surface. The spectral fits produced by the linear deconvolution algorithm yields good results for the HED samples of known composition, thus giving us a high degree of confidence that our results for Vesta are valid.

Donaldson Hanna, K.; Sprague, A. L.

2009-12-01

214

Vesta and HED Meteorites: Determining Minerals and their Abundances with Mid-IR Spectral Deconvolution I  

NASA Astrophysics Data System (ADS)

We identify the known mineral compositions and abundances of laboratory samples of Howardite, Eucrite and Diogenite (HED) meteorites (Salisbury et al. 1991, Icarus 9, 280-297) using an established spectral deconvolution algorithm (Ramsey, 1996 Ph.D. Dissertation, ASU; Ramsey and Christiansen 1998, JGR 103, 577-596) for mid-infrared spectral libraries of mineral separates of varying grain sizes. Most notably, the spectral deconvolution algorithm fit the known plagioclase and pyroxene compositions for all of the HED meteorite spectra determined by laboratory analysis. Our results for the HED samples, give us a high degree of confidence that our results are valid and that the spectral deconvolution algorithm is viable. Mineral compositions and abundances are also determined using the same technique for one possible HED parent body, Vesta, using mid-infrared spectra that were obtained from ground-based telescopes (Sprague et al. 1993, A.S.P. 41 Lim et al. 2005, Icarus 173, 385-408) and the Infrared Space Observatory (ISO) (Dotto et al. 2000, A&A 358, 1133-1141). Mid-infrared spectra of Vesta come from different areas on its surface. The ISO Vesta spectral deconvolution is suggestive of triolite, olivine, augite, chromite, wollastonite, and sodalite at one location. Modeling of other locations is underway. We also were successful in modeling spectra from locations on the Moon where no Apollo samples are available and for several locations on Mercury's surface using the same techniques (see lunar and mercurian abstracts this meeting). These results demonstrate promise for the spectral deconvolution method to correctly make mineral identifications on remotely observed objects, in particular main-belt asteroids, the Moon, and Mercury. This work was funded by NSF AST0406796.

Hanna, Kerri D.; Sprague, A. L.

2007-10-01

215

Ball clay  

USGS Publications Warehouse

Part of the 1999 Industrial Minerals Review. The state of the ball clay industry in 1999 is presented. Record highs in the sales and use of ball clay were attained in 1999 due to the continued strength of the U.S. economy. U.S. production was estimated at 1.25 million st for the year, with more than half of that amount mined in Tennessee. Details of the consumption, price, imports, and exports of ball clay in 1999 and the outlook for ball clay over the next few years are provided.

Virta, R. L.

2000-01-01

216

[Rapid determination of major and trace elements in the salt lake clay minerals by X-ray fluorescence spectrometry].  

PubMed

A rapid multi-element analysis method for clay mineral samples was described. This method utilized a polarized wave-length dispersive X-ray fluorescence spectrometer--Axios PW4400, which had a maximum tube power of 4 000 watts. The method was developed for the determination of As, Mn, Co, Cu, Cr, Dy, Ga, Mo, P, Pb, Rb, S, Sr, Ni, ,Cs, Ta, Th, Ti, U, V, Y, Zn, Zr, MgO, K2O, Na2O, CaO, Fe2O3, Al2O3, SiO2 and so on. Thirty elements in clay mineral species were measured by X-ray fluorescence spectrometry with pressed powder pellets. Spectral interferences, in particular the indirect interferences of each element, were studied. A method to distinguish the interference between each other periodic elements in element periodic table was put forward. The measuring conditions and existence were mainly investigated, and the selected background position as well as corrected spectral overlap for the trace elements were also discussed. It was found that the indirect spectral overlap line was the same important as direct spectral overlap line. Due to inducing the effect of indirect spectral overlap, some elements jlike Bi, Sn, W which do not need analysis were also added to the elements channel. The relative standard deviation (RSD) was in the range of 0.01% to 5.45% except three elements Mo, Cs and Ta. The detection limits, precisions and accuracies for most elements using this method can meet the requirements of sample analysis in clay mineral species. PMID:20496720

Wang, Xiao-Huan; Meng, Qing-Fen; Dong, Ya-Ping; Chen, Mei-Da; Li, Wu

2010-03-01

217

Enhancing effects during the interaction of cationic surfactants and organic pollutants with clay minerals  

Microsoft Academic Search

The adsorption of aromatic compounds (2-chlorophenol 2-naphthol) in the presence of cationic C16-surfactants by different clays (kaolin, illite, and bentonite (montmorillonite)) from water was studied. — The cationic surfactants\\u000a alter the adsorption properties of clays by means of surface hydrophobing, which leads to a drastic increase and acceleration\\u000a of the adsorption of these aromatic pollutants. If the surface is densely

E. Klumpp; H. Heitmann; H. Lewandowski; M. J. Schwuger

218

The role of clay minerals in the reduction of nitrate in groundwater by zero-valent iron.  

PubMed

Bench-scale batch experiments were performed to investigate the feasibility of using different types of clay minerals (bentonite, fuller's earth, and biotite) with zero-valent iron for their potential utility in enhancing nitrate reduction and ammonium control. Kinetics experiments performed with deionized water (DW) and groundwater (GW) revealed nitrate reduction by Fe(0) proceeded at significantly faster rate in GW than in DW, and such a difference was attributed to the formation of green rust in GW. The amendment of the minerals at the dose of 25 g L(-1) in Fe(0) reaction in GW resulted in approximately 41%, 43%, and 33% more removal of nitrate in 64 h reaction for bentonite, fuller's earth, and biotite, respectively, compared to Fe(0) alone reaction. The presumed role of the minerals in the rate enhancement was to provide sites for the formation of surface bound green rust. Bentonite and fuller's earth also effectively removed ammonium produced from nitrate reduction by adsorption, with the removal efficiencies significantly increased with the increase in mineral dose above 5:1 Fe(0) to mineral mass ratio. Such a removal of ammonium was not observed for biotite, presumably due to its lack of swelling property. Equilibrium adsorption experiments indicated bentonite and fuller's earth had maximum ammonium adsorption capacity of 5.6 and 2.1 mg g(-1), respectively. PMID:20797759

Cho, Dong-Wan; Chon, Chul-Min; Jeon, Byong-Hun; Kim, Yongje; Khan, Moonis Ali; Song, Hocheol

2010-08-24

219

Adhesion of the clay minerals montmorillonite, kaolinite, and attapulgite reduces respiration of Histoplasma capsulatum.  

PubMed

The respiration of three phenotypes of Histoplasma capsulatum, the causal agent of histoplasmosis in humans, was markedly reduced by low concentrations of montmorillonite but was reduced less by even higher concentrations of kaolinite or attapulgite (palygorskite). The reduction in respiration followed a pattern that suggested saturation-type kinetics: an initial sharp reduction that occurred with low concentrations of clay (0.01 to 0.5% [wt/vol]), followed by a more gradual reduction with higher concentrations (1 to 8%). Increases in viscosity (which could impair the movement of O2) caused by the clays were not responsible for the reduction in respiration, and the clays did not interfere with the availability of nutrients. Scanning electron microscopy after extensive washing showed that the clay particles were tightly bound to the hyphae, suggesting that the clays reduced the rate of respiration of H. capsulatum by adhering to the mycelial surface and, thereby, interfered with the movement of nutrients, metabolites, and gases across the mycelial wall. PMID:3954340

Lavie, S; Stotzky, G

1986-01-01

220

Anomalous small angle x-ray scattering studies of heavy metal ion solvation behavior in clay minerals  

SciTech Connect

The authors have exploited anomalous small angle x-ray scattering (ASAXS) to monitor the solvation behavior of Cu(II), Er(III) and Yb(III) ions within the interlayers of the natural aluminosilicate clay mineral montmorillonite. The ASAXS technique can reveal the distribution of specific metallic species within a heterogeneous and disordered matrix. The variations of signal intensity as a function of absorption energy were monitored for all of the metal-clays as a function of hydration. Two different hydration levels were probed: as prepared at ambient conditions, or so-called {open_quotes}dry{close_quotes} powders, and {open_quotes}wet{close_quotes} pastes. ASAXS intensities should increase with absorption energy if the metal ion is associated with the interlayer solvent (water in this case), and decrease if the metal ion is associated with the solid matrix. The results show that: (1) Cu(II) is solvated within the interlayers of the wet sample, as expected, and (2) Er(III) and Yb(III) decrease in ASAXS intensity with increased hydration. This latter result was not expected and there is speculation that these ions have associated as hydrolyzed products with the clay surface. The basic principles underlying SAXS and ASAXS will also be presented in this paper.

Carrado, K.A.; Thiyagarajan, P.; Winans, R.E.; Song, Kang [Argonne National Lab., IL (United States)

1997-09-01

221

Post-Fire Spatial Patterns of Soil Nitrogen Mineralization and Microbial Abundance  

PubMed Central

Stand-replacing fires influence soil nitrogen availability and microbial community composition, which may in turn mediate post-fire successional dynamics and nutrient cycling. However, fires create patchiness at both local and landscape scales and do not result in consistent patterns of ecological dynamics. The objectives of this study were to (1) quantify the spatial structure of microbial communities in forest stands recently affected by stand-replacing fire and (2) determine whether microbial variables aid predictions of in situ net nitrogen mineralization rates in recently burned stands. The study was conducted in lodgepole pine (Pinus contorta var. latifolia) and Engelmann spruce/subalpine fir (Picea engelmannii/Abies lasiocarpa) forest stands that burned during summer 2000 in Greater Yellowstone (Wyoming, USA). Using a fully probabilistic spatial process model and Bayesian kriging, the spatial structure of microbial lipid abundance and fungi-to-bacteria ratios were found to be spatially structured within plots two years following fire (for most plots, autocorrelation range varied from 1.5 to 10.5 m). Congruence of spatial patterns among microbial variables, in situ net N mineralization, and cover variables was evident. Stepwise regression resulted in significant models of in situ net N mineralization and included variables describing fungal and bacterial abundance, although explained variance was low (R2<0.29). Unraveling complex spatial patterns of nutrient cycling and the biotic factors that regulate it remains challenging but is critical for explaining post-fire ecosystem function, especially in Greater Yellowstone, which is projected to experience increased fire frequencies by mid 21st Century.

Smithwick, Erica A. H.; Naithani, Kusum J.; Balser, Teri C.; Romme, William H.; Turner, Monica G.

2012-01-01

222

Post-fire spatial patterns of soil nitrogen mineralization and microbial abundance.  

PubMed

Stand-replacing fires influence soil nitrogen availability and microbial community composition, which may in turn mediate post-fire successional dynamics and nutrient cycling. However, fires create patchiness at both local and landscape scales and do not result in consistent patterns of ecological dynamics. The objectives of this study were to (1) quantify the spatial structure of microbial communities in forest stands recently affected by stand-replacing fire and (2) determine whether microbial variables aid predictions of in situ net nitrogen mineralization rates in recently burned stands. The study was conducted in lodgepole pine (Pinus contorta var. latifolia) and Engelmann spruce/subalpine fir (Picea engelmannii/Abies lasiocarpa) forest stands that burned during summer 2000 in Greater Yellowstone (Wyoming, USA). Using a fully probabilistic spatial process model and Bayesian kriging, the spatial structure of microbial lipid abundance and fungi-to-bacteria ratios were found to be spatially structured within plots two years following fire (for most plots, autocorrelation range varied from 1.5 to 10.5 m). Congruence of spatial patterns among microbial variables, in situ net N mineralization, and cover variables was evident. Stepwise regression resulted in significant models of in situ net N mineralization and included variables describing fungal and bacterial abundance, although explained variance was low (R²<0.29). Unraveling complex spatial patterns of nutrient cycling and the biotic factors that regulate it remains challenging but is critical for explaining post-fire ecosystem function, especially in Greater Yellowstone, which is projected to experience increased fire frequencies by mid 21(st) Century. PMID:23226324

Smithwick, Erica A H; Naithani, Kusum J; Balser, Teri C; Romme, William H; Turner, Monica G

2012-11-30

223

The titration of clay minerals I. Discontinuous backtitration technique combined with CEC measurements.  

PubMed

Previous experimental studies on clay potentiometric titration have been unable to distinguish inorganic cation exchange in the interlayer and on basal plane surfaces from specific pH-dependent sorption of cations and anions on the edges. In this study, we refined a titration technique, combining discontinuous backtitration and cation exchange capacity (CEC) measurements, and applied it to the potentiometric titration of Na- and Ca-conditioned montmorillonites. This technique can be used to accurately measure cation exchange, edge surface proton charge, dissolution of clay, and precipitation of new phases. Thus, a precise measurement of the variations of net proton surface charge is possible. This has important implications for clay surface modeling (see part II of this article) and for processes that depend on the clay surface charge, e.g., alteration, rheological processes, and contamination retention applications. In addition, this study confirms the adsorption of ionic pairs such as CaCl+ in exchange site positions and shows that CaOH+ could behave like CaCl+. This result, together with the evidence of precipitation of a Ca?Si phase over a short time-scale (1 week) at high pH and low temperature, can be used to model clay-concrete interactions more accurately. We confirmed and quantified the H+/Na+ exchange reaction at low pH. Finally, we demonstrate that both the edge surface charge and the permanent structural charge are compensated for by the nonspecific sorption of cations from solution across the entire pH range from 4 to 11. Under these conditions, the surface potential is fully screened and does not need to be invoked in modeling sorption processes on clay particles in dilute suspensions. PMID:15051456

Tournassat, Christophe; Greneche, Jean-Marc; Tisserand, Delphine; Charlet, Laurent

2004-05-01

224

Sediment sources and their contribution along northern coast of the South China Sea: Evidence from clay minerals of surface sediments  

NASA Astrophysics Data System (ADS)

Clay minerals of surface sediment samples from nine bays/harbors along northern coast of the South China Sea (SCS) are used for sediment sources and contribution estimation in the study areas. Results reveal that sediments in the study bays/harbors seem to be a mixture of sediments from the Pearl, Hanjiang River and local islands/rivers, but their clay mineral assemblage is distinct from that of Luzon and Taiwan sediments, indicating that sediments are derived mainly from the neighboring sources through riverine input and partly from localized sediments. Due to input of local sediments in the northern SCS, sediments from both east of the Leizhou Peninsula (Area IV) and next to the Pearl River estuary (PRE, Area II) have high smectite percent. Affected by riverine input of the Pearl and Hanjiang Rivers, sediments in west of the PRE (Area III) and east of the PRE (Area I) have high illite (average 47%) and kaolinite (54%) percents, respectively. Sediment contributions of various major sources to the study areas are estimated as the following: (1) the Hanjiang River provide 95% and 84% sediments in Areas I and II, respectively, (2) the Pearl River supply 79% and 29% sediments in Areas III and IV, respectively and (3) local sediments contribute the rest and reach the maximum (?71%) in Area IV.

Liu, Jianguo; Yan, Wen; Chen, Zhong; Lu, Jun

2012-09-01

225

Clay mineral distribution in surface sediments of the South China Sea and its significance for in sediment sources and transport  

NASA Astrophysics Data System (ADS)

Clay minerals of surface sediments in the South China Sea (SCS) are analyzed with X-ray diffraction, and their transport is explored with a grain size trend analysis (GSTA) model. Results show that clay mineral types in various sedimentary environments have different sediment sources and transport routes. Sediments in the northern SCS (north of 20°N) between the southwest of Taiwan Island and the outer mouth of the Pearl River have high contents of illite and chlorite, which are derived mainly from sediments on Taiwan Island and/or the Yangtze River. Sediments from the Pearl River are characterized by high kaolinite and low smectite content, and most are distributed in the area between the mouth of the Pearl River and northeast of Hainan Island and transported vertically from the continental shelf to the slope. Characterized by high illite content, sediments from Kalimantan Island are transported toward the Nansha Trough. Sediments from Luzon Island are related with volcanic materials, and are transported westwards according to smectite distribution. On the Sunda Shelf, sediments from the Mekong River are transported southeast in the north while sediments from the Indonesian islands are transported northward in the south. Ascertaining surface sediment sources and their transport routes will not only improve understanding of modern transportation and depositional processes, but also aid paleoenvironmental and paleoclimatic analysis of the SCS.

Liu, Jianguo; Chen, Muhong; Chen, Zhong; Yan, Wen

2010-03-01

226

Clay minerals in chernozem-like soils of mesodepressions in the northern forest-steppe of European Russia  

NASA Astrophysics Data System (ADS)

In the northern forest-steppe of European Russia, under the conditions of surface waterlogging (freshwater) and a stagnant-percolative regime, gleyic podzolic chernozem-like soils with thick light-colored eluvial horizons are formed. These horizons are close or similar to the podzolic horizons of bog-podzolic soils in many properties of their solid phase. They are bleached in color and characterized by the removal of Ca, Mg, Fe, Al, and Mn and the relative accumulation of quartz SiO2. These soils differ from leached chernozems in their acid reaction and very low CEC, the presence of Fe-Mn concretions and coatings, and the significant decrease in the clay content in the A2 horizon as compared to the parent rock. The soils studied differ significantly from loamy podzolic and bog-podzolic soils by the composition of the clay minerals in the A2 horizons: (1) no essential loss of smectite minerals from this horizon was found as compared to the rest of the solum, (2) pedogenic chlorites (HIV and HIS) are absent, and (3) the distinct accumulation of illites is observed as compared to the subsoil and parent material, probably, due to the process of illitization.

Sokolova, T. A.; Zaidel'Man, F. R.; Ginzburg, T. M.

2010-01-01

227

Influence of Environmental Factors on Antagonism of Fungi by Bacteria in Soil: Clay Minerals and pH  

PubMed Central

The soil replica plating technique was used to evaluate the influence of clay minerals and pH on antagonistic interactions between fungi and bacteria in soil. In general, the antagonistic activity of bacteria towards filamentous fungi was greater in soil than on agar. The spread of Aspergillus niger through soil was inhibited by Serratia marcescens when the organisms were inoculated into separate sites in soil, and this antagonistic effect was maintained when the soil was amended with 3, 6, 9, or 12% (vol/vol) montmorillonite, whereas the addition of kaolinite at a concentration of 3% reduced the antagonism and at 6, 9, or 12% totally eliminated it. Similar results were obtained with the inhibition of A. niger by Agrobacterium radiobacter and of Penicillium vermiculatum by either S. marcescens or Nocardia paraffinae. When A. niger and S. marcescens were inoculated into the same soil site, A. niger was inhibited in all soils, regardless of clay content, although the extent of inhibition was greater as the concentration of montmorillonite, but not of kaolinite, increased. A. niger was inhibited more when inoculated as spores than as mycelial fragments and when inoculated 96 h after S. marcescens, but a 1% glucose solution reduced the amount of inhibition when the fungus was inoculated 96 h after the bacterium. When the pH of the soil-clay mixtures was altered, the amount of antagonism usually increased as the pH increased. Antagonism appeared to be related to the cation-exchange capacity and the pH of the soil-clay mixtures. Bacillus cereus and another species of Bacillus showed no activity in soil towards A. niger under any of the environmental conditions tested, even though the Bacillus sp. significantly inhibited A. niger and seven other fungi on agar.

Rosenzweig, William D.; Stotzky, G.

1979-01-01

228

Deposition and survival of Escherichia coli O157:H7 on clay minerals in a parallel plate flow system.  

PubMed

Understanding bacterial pathogens deposition and survival processes in the soil-groundwater system is crucial to protect public health from soilborne and waterborne diseases. However, mechanisms of bacterial pathogen-clay interactions are not well studied, particularly in dynamic systems. Also, little is known about the viability of bacterial pathogens when attached to clays. In this study, a parallel plate flow system was used to determine the deposition kinetics and survival of Escherichia coli O157:H7 on montmorillonite, kaolinite, and goethite over a wide range of ionic strengths (IS) (0.1-100 mM KCl). E. coli O157:H7 deposition on the positively charged goethite is greater than that on the negatively charged kaolinite and montmorillonite. Although the zeta potential of kaolinite was more negative than that of montmorillonite, kaolinite showed a greater deposition for E. coli O157:H7 than montmorillonite, which is attributed to the chemical heterogeneity of clay minerals. Overall, increasing IS resulted in an increase of E. coli O157:H7 deposition on montmorillonite and kaolinite, and a decrease on goethite. Interaction energy calculations suggest that E. coli O157:H7 deposition on clays was largely governed by DLVO (Derjaguin-Landau-Verwey-Overbeek) forces. The loss of bacterial membrane integrity was investigated as a function of time using the Live/Dead BacLight viability assay. During the examined period of 6 h, E. coli O157:H7 retained its viability in suspension and when attached to montmorillonite and kaolinite; however, interaction with the goethite was detrimental. The information obtained in this study is of fundamental significance for the understanding of the fate of bacterial pathogens in soil environments. PMID:23346967

Cai, Peng; Huang, Qiaoyun; Walker, Sharon L

2013-02-08

229

Equilibrium, kinetic and thermodynamic studies on the adsorption of the toxins of Bacillus thuringiensis subsp. kurstaki by clay minerals  

NASA Astrophysics Data System (ADS)

The persistence of Bacillus thuringiensis ( Bt) toxins in soil is further enhanced through association with soil particles. Such persistence may improve the effectiveness of controlling target pests, but impose a hazard to non-target organisms in soil ecosystems. In this study, the equilibrium adsorption of the Bt toxin by four clay minerals (montmorillonite, kaolinite, goethite, and silicon dioxide) was investigated, and the kinetic and thermodynamic parameters were calculated. The results showed that Bt toxin could be adsorbed easily by minerals, and the adsorption was much easier at low temperature than at high temperature at the initial concentration varying from 0 to 1000 mg L -1. The adsorption fitted well to both Langmuir and Freundlich isotherm models, but the Freundlich equation was more suitable. The pseudo-second-order (PSO) was the best application model to describe the adsorption kinetic. The adsorption process appeared to be controlled by chemical process, and the intra-particle diffusion was not the only rate-controlling step. The negative standard free energy ( ?Gm?r) values of the adsorption indicated that the adsorption of the Bt toxin by the minerals was spontaneous, and the changes of the standard enthalpy ( ?Hm?r) showed that the adsorption of the Bt toxin by montmorillonite was endothermic while the adsorption by the other three minerals was exothermic.

Fu, Qingling; Deng, Yali; Li, Huishu; Liu, Jie; Hu, Hongqing; Chen, Shouwen; Sa, Tongmin

2009-02-01

230

Stability in a high radiation field of nucleic acid bases and their nucleosides adsorbed in a clay mineral. Implications to chemical evolution studies  

NASA Astrophysics Data System (ADS)

Chemical evolution is a physical and chemical preamble prior to the appearance of life. Today, there is a large variety of experimental data to support the hypothesis for the abiotic formation of organic compounds. Although much knowledge has been gain, still many questions remain. Clay minerals might have played an important role on the early Earth. They are considered the most likely inorganic material to promote organic reactions at the interface of the hydrosphere and lithosphere. The relevance of clay minerals in the emergency of the origin of life is due to their ancient origin, wide distribution and especially for their physico-chemical properties. Clays are known to have a high affinity for organic compounds. John D. Bernal (1951) suggested several roles for the clays: as concentrators of biological precursor molecules, as catalysis and may be clays may protect these molecules from high-energy radiation. On the other hand, nucleic acid bases and their derivatives are important compounds in biological systems. Their synthesis and stability in environmental conditions is of paramount importance in chemical evolution. To ensure that organic compounds endured in the primitive Earth there are several possibilities: a) their synthesis was continuous and they reach steady state concentration. b) The compounds present a long half-life in the environmental conditions of the primitive Earth. c) Solid surfaces protect the organic compound adsorbed in the clay, as Bernal suggested (1951). Our aim is to extent the knowledge of the of role of clays in the prebiotic epoch, related to the adsorption and co-adsorption of nucleic acid bases and nucleotides in clays, their site of binding and their behavior under gamma irradiation adsorbed in the clays. To this end, we determine the survival of bases and their corresponding nucleosides exposed to a high radiation field in an aqueous solution and adsorbed in a clay mineral. The results showed the protection role of the clay toward ionizing radiation. Bases and nucleotides are able to resist radiation if they are adsorbed in a clay mineral. This is a distinct advantage, since the molecules that were formed by ultraviolet light, ionizing radiation, or electric discharges had to survive in order to interact with each other to form more complex molecules. Bernal, J.D.: 1951, he Physical Basis of Life, Routledge and Kegan Paul, London

Aguilar-Ovando, Ellen; Negron-Mendoza, Alicia; Ramirez-Navarro, Leonardo; Chacon-Baca, Elizabeth; Ramos-Bernal, Sergio

231

Clay-mineral and grain-size distributions in surface sediments of the White Sea (Arctic Ocean): indicators of sediment sources and transport processes  

NASA Astrophysics Data System (ADS)

In this study, the grain-size and clay-mineral compositions of 73 surface sediment samples collected in a variety of environmental settings in the White Sea are presented to characterize recent sedimentation processes, reconstruct transport pathways, and identify potential source areas of the terrigenous components. Areas >100 m deep are invariably characterized by silty clay, whereas areas <100 m deep exhibit more heterogeneous grain-size compositions plausibly explained by coastal erosion and (re-)distribution mechanisms, particularly tidal currents. The dominance of sand in the estuarine areas of the Onega and Dvina rivers as well as toward the Gorlo Strait connecting the White Sea with the Barents Sea is attributed to increased current speeds. Illite and smectite are the dominant clay minerals in recent sediments of the southwestern and eastern White Sea sectors, respectively. Their distribution patterns largely depend on the geology of the source areas, and mirror surface circulation patterns, especially in Dvina Bay. Smectite is a key clay mineral in White Sea surface sediments, as it reveals the dominating influence of the Northern Dvina's runoff on sedimentation and water circulation throughout the basin. In comparison to other Eurasian shelf seas, the White Sea is characterized by a greater diversity of clay-mineral assemblages, which range from illite- to smectite-dominated sectors containing variable amounts of chlorite and kaolinite.

Saukel, Cornelia; Stein, Rüdiger; Vogt, Christoph; Shevchenko, Vladimir P.

2010-12-01

232

ADSORPTION, DESORPTION AND OXIDATION OF ARSENIC AFFECTED BY CLAY MINERALS AND AGING PROCESS  

EPA Science Inventory

Adsorption/desorption and oxidation/reduction of arsenic at clay surfaces are very important to the natural attenuation of arsenic in the subsurface environment. Although numerous studies have concluded that iron oxides have high affinities for the adsorption of As(V), very litt...

233

Enhanced carbon dioxide release and other possible effects of clay minerals during thermal evaluation of sediments  

Microsoft Academic Search

Thermal evaluation of potential source rocks (PSR) include measurements of COâ evolved (> 400°C) designated as IO (Oxygen Index). For whole rock analysis this index frequently exceeds the value derived from organically bonded oxygen. The surplus of OCâ stems mainly from the reaction of carbonates with active acidic volatiles released from the associated clays. The magnitude of this effect is

Z. Aizenshtat; I. Miloslavsky; L. H. Kallai

1989-01-01

234

Alkaline treatment of clay minerals from the Alhambra Formation: Implications for the conservation of earthen architecture  

Microsoft Academic Search

Clay–water interactions result in damage and loss of earthen architecture. Natural and artificial additives were traditionally added to earth in order to increase its water resistance and mechanical strength. More recently, portland cement, ethyl silicates and synthetic resins have been applied to consolidate earthen structures, however often with limited success. Here, in an effort to design a more effective procedure

K. Elert; E. Sebastián; I. Valverde; C. Rodriguez-Navarro

2008-01-01

235

Diagenetic clays as pore-lining minerals in coalbed methane reservoirs  

Microsoft Academic Search

Cleat surfaces from Mary Lee and Black Creek coal seams in the Black Warrior Basin and Fruitland coal from the San Juan Basin show significant amounts of diagenetic quartz, illite, kaolinite, carbonate minerals, barite, gypsum and iron sulfides and sulfates. SEM, XRD, thin section and reflected light microscopy analyses were used to identify and describe diagenetic minerals and surface textures

K. S. Fowler; K. E. Nick

1996-01-01

236

Gram-negative Biomass in Clay Minerals Analogs: Testing Habitability Potential for the 2011 Mars Science Laboratory Mission  

NASA Astrophysics Data System (ADS)

Landing sites of next missions to Mars i.e., the US 2011 Mars Science Laboratory (MSL11) and the ESA2016 Pasteur ExoMars, will include phyllosilicate outcrops as targets for investigating the geological and biological history of that planet. In this context, we present a study assessing the living biomass and habitability potential in mineralogical Mars analogs such as phyllosilicates and hematite-rich deposits encompassing a broad arid-hyper-arid climate range (annual rainfall <0.2 to ~700mm/y). Samples from the Atacama Desert (Chile), the Death Valley (CA), and the California Coast (USA) were analyzed for microbial lipopolysaccharide (LPS) as proxy for Gram-negatives biomass with the Limulus-Amebocite-Lysate (LAL) assay. Mineral phases were identified using X-Ray-Diffraction (XRD). These samples resulted to contain phyllosilicate phases similar to those identified, or inferred [1], on the surface of Mars by the OMEGA-Mars/Express [e.g., 2], the Mars Reconnaissance Orbiter (MRO) instruments (HiRISE and CRISM) [3]. Basic observations were: 1) there is no systematic pattern in biomass content of clays vs. non-clays (oxidized) materials from the study sites; 2) Atacama desiccation polygons (muscovite and kaolinite) and contiguous hematite-rich hyper-arid deposits contain the lowest biomass, i.e., ~104to-105 cells/g, respectively; 3) the hyper-arid clays contain three-order magnitude lower Gram-negative biomass than those (montmorillonite, illite, and chlorite) from the arid Death Valley site (~107cells/g); and 4) finally, the Gram-negative (~107cells/g) of clay minerals-rich materials from the arid site is about the same than that (~1.5 to ~3.0 x 107cells/g) of water-saturated massive deposits (kaolinite, illite, and vermiculite) from the wetter California coast. Results from this investigation will help testing for the habitability potential of phyllosilicate deposits sampled by the MSL11 Mission. REFERENCES:[1] Bibring et al., 2006, Science 312:400-404; [2] Wang et al., 2006 JGR E02S16 Vol.111; [3] Bishop et al., 2008. Science, 321,830-833.

Bonaccorsi, R.; McKay, C. P.

2009-12-01

237

Interactions between clay minerals and siderophores affect the respiration of Histoplasma capsulatum.  

PubMed

The reduction in the respiration of Histoplasma capsulatum in broth culture caused by montmorillonite appeared to be the result, in part, of the interference by the clay with the iron nutrition of the fungus. This interference was apparently the result of the adsorption by the clay of the iron-transporting siderophore (deferricoprogen B) produced by the fungus, as the reduction in respiration was partially alleviated by the addition of foreign siderophores. Neither kaolinite nor attapulgite (palygorskite) appeared to adsorb significant amounts of the siderophores, probably because of the low cation exchange capacity and specific surface area of kaolinite and the inaccessibility of adsorption sites in the fibrous attapulgite. These observations, in addition to the adhesion of montmorillonite to the hyphae, suggest mechanisms that may explain the discrete geographic distribution of this fungus, which is pathogenic to humans and which has been isolated essentially only from soils that do not contain montmorillonite. PMID:2937365

Lavie, S; Stotzky, G

1986-01-01

238

Contribution of organic matter and clay minerals to the cation exchange capacity of soils  

Microsoft Academic Search

The cation exchange capacity (CEC) at pH 7 was measured for samples of 347 A horizons and 696 B horizons of New Zealand soils. The mean CEC was 22.1 cmolc\\/kg for the A horizons and 15.2 cmolc\\/kg for the B horizons. Multiple regressions were carried out for CEC against organic carbon (C), clay content, and the content of seven groups

R. L. Parfitt; D. J. Giltrap; J. S. Whitton

1995-01-01

239

Clay Diagenesis in the Sandstone Reservoir of the Ellon Field (Alwyn, North Sea)  

Microsoft Academic Search

The nature, composition, and relative abundance of clay minerals in the sandstones of the Brent Group reservoir were studied between 3200-3300 m in a well of the Ellon Field (Alwyn area, North Sea). The sandstones have a heterogeneous calcite cement which occurred during early-diagenesis. Clay diagenesis of the cemented and uncemented sandstones was investigated using optical microscopy, scanning electron microscopy

Lhoussain Hassouta; MARTINE D. BUATIER; JEAN-Luc POTDEVIN; NICOLE LIEWIG

1999-01-01

240

Clay Minerals in Primitive Meteorites and Interplanetary Dust 1 (Abstract Only).  

National Technical Information Service (NTIS)

Many meteorites and interplanetary dust particles (IDPs) with primitive compositions contain significant amounts of phyllosilicate minerals, which are generally interpreted as evidence of protoplanetary aqueous alteration at an early period of the solar s...

M. E. Zolensky L. P. Keller

1991-01-01

241

Microtomographic quantification of hydraulic clay mineral displacement effects during a CO2 sequestration experiment with saline aquifer sandstone.  

PubMed

We combined a noninvasive tomographic imaging technique with an invasive open-system core-flooding experiment and compared the results of the pre- and postflooded states of an experimental sandstone core sample from an ongoing field trial for carbon dioxide geosequestration. For the experiment, a rock core sample of 80 mL volume was taken from the 629 m Stuttgart Formation storage domain of a saline sandstone aquifer at the CCS research pilot plant Ketzin, Germany. Supercritical carbon dioxide and synthetical brine were injected under in situ reservoir p/T-conditions at an average flow rate of 0.1 mL/min for 256 h. X-ray computed microtomographic imaging was carried out before and after the core-flooding experiment at a spatial voxel resolution of 27 ?m. No significant changes in microstructure were found at the tomographic imaging resolution including porosity and pore size distribution, except of an increase of depositional heterogeneous distribution of clay minerals in the pores. The digitized rock data were used as direct real microstructure input to the GeoDict software package, to simulate Navier-Stokes flow by a lattice Boltzmann equation solver. This procedure yielded 3D pressure and flow velocity fields, and revealed that the migration of clay particles decreased the permeability tensor probably due to clogging of pore openings. PMID:22924476

Sell, Kathleen; Enzmann, Frieder; Kersten, Michael; Spangenberg, Erik

2012-09-05

242

Weathering and clay mineral formation in two Holocene soils and in buried paleosols in Tadjikistan: towards a Quaternary paleoclimatic record in Central Asia  

Microsoft Academic Search

The upper part of the Karamaydan section, Tadjikistan, shows the most detailed loess–paleosol sequence yet known for the Brunhes chron, and the central and lower parts of the Chashmanigar section provide similar detail for most of the Matuyama chron. To enable paleoclimates to be deduced, the primary and secondary minerals in the silt and clay fractions must be determined separately

A. Bronger; R. Winter; S. Sedov

1998-01-01

243

Evolution of clay mineral assemblages and organic matter in the late glacial-Holocene sedimentary infill of Lake Annecy, (northwestern Alps): paleoenvironmental implications  

Microsoft Academic Search

The basin fill of Lake Annecy was investigated from a 44 m core which reached down to glacial sediments of the last glaciation (called Würm in the alpine areas). We analyzed three main parameters: sediment texture (optical microscopy and laser microgranulometry), clay mineral assemblages (CMA by XRD), and organic matter (OM by Rock-Eval pyrolysis). Settling of suspended load, under variable

F. Manalt; C. Beck; J.-R. Disnar; J.-F. Deconinck; P. Recourt

2001-01-01

244

Clay mineral assemblages and analcime formation in a Palaeogene fluvial lacustrine sequence (Maíz Gordo Formation Palaeogen) from northwestern Argentina  

NASA Astrophysics Data System (ADS)

The Palaeogene Maíz Gordo Formation is one of the main lacustrine events recorded in northwestern Argentina. It consists of sandstone, mudstone, and limestone beds 200 m thick, deposited in a brackish alkaline lake and braided alluvial systems. The Maíz Gordo Lake evolved mainly as a closed system, with brief periods as an open one. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to study samples from seven sites, corresponding respectively to proximal, intermediate, and transitional positions of the fluvial environment and marginal and inner-lake environment, focusing on the clay mineralogy and analcime formation. The basinward zonation of diagenetic minerals identified in the Maíz Gordo Lake was: mordenite ? analcime ? K-feldspar. Although not a typical zonation of saline alkaline lakes, it does indicate an increase in salinity and alkalinity towards the centre. In proximal fluvial settings, smectite predominates at the base of the sequence, with scarce kaolinite. Towards the top, a striking increase in kaolinite content suggests a change from a relatively arid climate with alternating humid and dry seasons, towards a warm and humid climate. Kaolinite content clearly decreases in a basinward direction. Such a variation is attributable to changes in hydro-geochemistry, denoting the progressive influence of the brackish and alkaline lake water on interstitial pores. SEM images of intermediate fluvial samples reveal authigenesis of illite at the expense of kaolinite booklets. In littoral and inner-lake settings the clay fraction is composed of muscovite, sometimes with subordinate smectite. Analcime occurs in variable amounts in all sedimentary facies, in rock pores or filling veins. It forms subhedral square to hexagonal, or anhedral rounded crystals, denoting that they coarsened at low to moderate degrees of supersaturation. Although the mordenite identified in a fluvial level would have been the precursor of analcime in the Maíz Gordo Basin, no textural evidence of analcime formation through replacement of mordenite or other precursor zeolite was found. Hence it is more probable that analcime formation took place by direct authigenic precipitation or through the reaction between interstitial brines and clay minerals or plagioclase.

Do Campo, M.; Del Papa, C.; Jiménez-Millán, J.; Nieto, F.

2007-09-01

245

Use of general purpose adsorption isotherms for heavy metal-clay mineral interactions  

SciTech Connect

General purpose adsorption isotherm equations were fitted to the sorption data of lead and cadmium on both unmodified and Ca-saturated kaolinite and montmorillonite. Langmuir-Freundlich, Redlich-Petersen, Toth, Dubinin-Radushkevich, competitive Langmuir, and some modified forms of these isotherms were fitted to experimental data, and their goodnesses of fit are compared. The adjustable parameters of the Langmuir- and Freundlich-based isotherms were estimated by nonlinear least-squares analysis. The application of these two isotherms which allow for the effect of surface heterogeneity for both multiple and single desorbing ions during the sorption process was also studied. It was concluded that Redlich-Petersen, Toth, and original and modified forms of Dubinin-Radushkevich isotherms perform superior to the others both in high and low concentration regions for both unmodified and Ca-saturated clays. Competitive Langmuir adsorption isotherm for Ca-saturated clays fitted well for Pb adsorption, while a change of slope was observed for Cd adsorption.

Altin, O.; Oezbelge, H.O.; Dogu, T. [Middle East Technical Univ., Ankara (Turkey). Dept. of Chemical Engineering

1998-02-01

246

Microbial dissolution of clay minerals as a source of iron and silica in marine sediments  

Microsoft Academic Search

Interactions between microbes and minerals have the potential to contribute significantly to the global cycles of various elements, and serve as a link between the geosphere and life. In particular, the microbially mediated cycle of iron within marine sediments is closely tied to the carbon cycle. The dissolved iron that serves as a nutrient is thought to be primarily drawn

John S. Vorhies; Robert R. Gaines

2009-01-01

247

Clay mineral weathering and contaminant dynamics in a caustic aqueous system I. Wet chemistry and aging effects  

SciTech Connect

Caustic high level radioactive waste induces mineral weathering reactions that can influence the fate of radionuclides released in the vicinity of leaking storage tanks. The uptake and release of CsI and SrII were studied in batch reactors of 2:1 layer-type silicates?illite (Il), vermiculite (Vm) and montmorillonite (Mt)?under geochemical conditions characteristic of leaking tank waste at the Hanford Site in WA (0.05 mAlT, 2 m Na*, 1 m NO3 *, pH *14, Cs and Sr present as co-contaminants). Time series (0 to 369 d) experiments were conducted at 298 K, with initial [Cs]0 and [Sr]0 concentrations from 10*5 to 10*3 mol kg*1. Clay mineral type affected the rates of (1) hydroxide promoted dissolution of Si, Al and Fe, (2) precipitation of secondary solids and (3) uptake of Cs and Sr. Initial Si release to solution followed the order Mt * Vm * Il. An abrupt decrease in soluble Si and/or Al after 33 d for Mt and Vm systems, and after 190 d for Il suspensions was concurrent with accumulation of secondary aluminosilicate precipitates. Strontium uptake exceeded that of Cs in both rate and extent, although sorbed Cs was generally more recalcitrant to subsequent desorption and dissolution. After 369 d reaction time, reacted Il, Vm and Mt solids retained up to 17, 47 and 14 mmol kg*1 (0.18, 0.24 and 0.02 *mol m*2) of Cs, and 0, 27 and 22 mmol kg*1 (0, 0.14 and 0.03 *molm*2) Sr, respectively, which were not removed in subsequent Mg exchange or oxalic acid dissolution reactions. Solubility of Al and Si decreased with initial Cs and Sr concentration in Mt and Il, but not in Vm. High co-contaminant sorption to the Vm clay, therefore, appears to diminish the influence of those ions on mineral transformation rates.

Choi, Sunkyung; Amistadi, Mary K.; Chorover, Jon

2005-04-08

248

Adsorption of thymine and uracil on 1:1 clay mineral surfaces: comprehensive ab initio study on influence of sodium cation and water.  

PubMed

This computational study performed using the density functional theory shows that hydrated and non-hydrated tetrahedral and octahedral kaolinite mineral surfaces in the presence of a cation adsorb the nucleic acid bases thymine and uracil well. Differences in the structure and chemistry of specific clay mineral surfaces led to a variety of DNA bases adsorption mechanisms. The energetically most predisposed positions for an adsorbate molecule on the mineral surface were revealed. The target molecule binding with the surface can be characterized as physisorption, which occurs mainly due to a cation-molecular oxygen interaction, with hydrogen bonds providing an additional stabilization. The adsorption strength is proportional to the number of intermolecular interactions formed between the target molecule and the surface. From the Atoms in Molecules analysis and comparison of binding energy values of studied systems it is concluded that the sorption activity of kaolinite minerals for thymine and uracil depends on various factors, among which are the structure and accessibility of the organic compounds. The adsorption is governed mostly by the surface type, its properties and presence of cation, which cause a selective binding of the nucleobase. Adsorbate stabilization on the mineral surface increases only slightly with explicit addition of water. Comparison of activity of different studied kaolinite mineral models reveals the following order for stabilization: octahedral-Na-water > octahedral-Na > tetrahedral-Na > tetrahedral-Na-water. Further investigation of the electrostatic potentials helps understanding of the adsorption process and confirmation of the active sites on the kaolinite mineral surfaces. Based on the conclusions that clay mineral affinity for DNA and RNA bases can vary due to different structural and chemical properties of the surface, a hypothesis on possible role of clays in the origin of life was made. PMID:21437301

Michalkova, A; Robinson, T L; Leszczynski, J

2011-03-24

249

Clay mineral and zeolite diagenesis in the Toa Baja well, Puerto Rico  

SciTech Connect

Several diagenetic reactions typical of volcaniclastic sediments have been identified in the Toa Baja well. The zeolites heulandite and (less commonly) analcite, present in the upper half of the drilled section, give way to laumontite at depth. A decrease with depth in the expandability of mixed layer chlorite/smectite was observed. Corrensite was detected over the depth range 1,676-2,286 m. Temperatures implied by the depth ranges of diagenetic and indicator minerals are consistent with a paleothermal gradient of about 30-50C/km, assuming little or no erosion of section.

Tribble, J.S. (Univ. of Hawaii, Honolulu (United States))

1991-03-01

250

Reduction and long-term immobilization of technetium by Fe(II) associated with clay mineral nontronite  

SciTech Connect

99Tc is formed mostly during nuclear reactions and is released into the environment during weapons testing and inadvertent waste disposal. The long half-life, high environmental mobility (as Tc(VII)O4-) and its possible uptake into the food chain cause 99Tc to be a significant environmental contaminant. In this study, we evaluated the role of Fe(II) in biologically reduced clay mineral, nontronite (NAu-2), in reducing Tc(VII)O4- to poorly soluble Tc(IV) species as a function of pH and Fe(II) concentration. The rate of Tc(VII) reduction by Fe(II) in NAu-2 was higher at neutral pH (pH 7.0) than at acidic and basic pHs when Fe(II) concentration was low (< 1 mmol/g). The effect of pH, however, was insignificant at higher Fe(II) concentrations. The reduction of Tc(VII) by Fe(II) associated with NAu-2 was also studied in the presence of common subsurface oxidants including iron and manganese oxides, nitrate, and oxygen, to evaluate the effect of the oxidants on the enhancement and inhibition of Tc(VII) reduction, and reoxidation of Tc(IV). Addition of iron oxides (goethite and hematite) to the Tc(VII)-NAu-2 system, where Tc(VII) reduction was ongoing, enhanced reduction of Tc(VII), apparently as a result of re-distribution of reactive Fe(II) from NAu-2 to more reactive goethite/hematite surfaces. Addition of manganese oxides stopped further Tc(VII) reduction, and in case of K+-birnessite, it reoxidized previously reduced Tc(IV). Nitrate neither enhanced reduction of Tc(VII) nor promoted reoxidation of Tc(IV). Approximately 11% of Tc(IV) was oxidized by oxygen. The rate and extent of Tc(IV) reoxidation was found to strongly depend on the nature of the oxidants and concentration of Fe(II). When the same oxidants were added to aged Tc reduction products (mainly NAu-2 and TcO2•nH2O), the extent of Tc(IV) reoxidation decreased significantly relative to fresh Tc(IV) products. Increasing NAu-2 concentration also resulted in the decreased extent of Tc(IV) reoxidation. The results were attributed to the effect of NAu-2 aggregation that effectively retained Tc(IV) in the solid and decreased its vulnerability to reoxidation. Overall, our results implied that bioreduced clay minerals could play an important role in reducing Tc(VII) and in maintaining the long-term stability of reduced Tc(IV).

Jaisi, Deb P.; Dong, Hailiang; Plymale, Andrew E.; Fredrickson, Jim K.; Zachara, John M.; Heald, S.; Liu, Chongxuan

2009-06-20

251

Electron transfer at the mineral/water interface: Selenium reduction by ferrous iron sorbed on clay  

NASA Astrophysics Data System (ADS)

The mobility and availability of the toxic metalloid selenium in the environment are largely controlled by sorption and redox reactions, which may proceed at temporal scales similar to that of subsurface water movement under saturated or unsaturated conditions. Since such waters are often anaerobic and rich in Fe 2+, we investigated the long-term (?1 month) kinetics of selenite (Se(IV)O3-) sorption to montmorillonite in the presence of Fe 2+ under anoxic conditions. A synthetic montmorillonite was used to eliminate the influence of structural Fe. In the absence of aqueous Fe 2+, selenite was sorbed as outer-sphere sorption complex, covering only part of the positive edge sites, as verified by a structure-based MUSIC model and Se K-edge XAS (X-ray absorption spectroscopy). When selenite was added to montmorillonite previously equilibrated with Fe 2+ solution however, slow reduction of Se and formation of a solid phase was observed with Se K-edge XANES (X-ray absorption near-edge spectroscopy) and EXAFS (extended X-ray absorption fine-structure) spectroscopy. Iterative transformation factor analysis of XANES and EXAFS spectra suggested that only one Se reaction product formed, which was identified as nano-particulate Se(0). Even after one month, only 75% of the initially sorbed Se(IV) was reduced to this solid species. Mössbauer spectrometry revealed that before and after addition and reduction of Se, 5% of total sorbed Fe occurred as Fe(III) species on edge sites of montmorillonite (?2 mmol kg -1). The only change observed after addition of Se was the formation of a new Fe(II) species (15%) attributed to the formation of an outer-sphere Fe(II)-Se sorption complex. The combined Mössbauer and XAS results hence clearly suggest that the Se and Fe redox reactions are not directly coupled. Based on the results of a companion paper, we hypothesize that the electrons produced in the absence of Se by oxidation of sorbed Fe(II) are stored, for example by formation of surface H 2 species, and are then available for the later Se(IV) reduction. The slow reaction rate indicates a diffusion controlled process. Homogeneous precipitation of an iron selenite was thermodynamically predicted and experimentally observed only in the absence of clay. Interestingly, half of Fe was oxidized in this precipitate (Mössbauer). Since DFT calculations predicted the oxidation of Fe at the water-FeSe solid interface only and not in the bulk phase, we derived an average particle size of this precipitate which does not exceed 2 nm. A comparison with the Mössbauer and XAS spectra of the clay samples demonstrates that such homogenous precipitation can be excluded as a mechanism for the observed slow Se reduction, emphasizing the role of abiotic, heterogeneous precipitation and reduction for the removal of Se from subsurface waters.

Charlet, L.; Scheinost, A. C.; Tournassat, C.; Greneche, J. M.; Géhin, A.; Fernández-Mart?´nez, A.; Coudert, S.; Tisserand, D.; Brendle, J.

2007-12-01

252

Net mineralization and nitrification rates in a clay soil measured and predicted in permanent grassland from soil temperature and moisture content  

Microsoft Academic Search

Summary Net mineralization of N and net nitrification in field-moist clay soils (Evesham-Kingston series) from arable and grassland sites were measured in laboratory incubation experiments at 4, 10 and 20°C. Three depth fractions to 30 cm were used. Nitrate accumulated at all temperatures except when the soil was very dry (?=0.13 cm3 cm?3). Exchangeable NH4-ions declined during the first 24

J. H. Macduff; R. E. White

1985-01-01

253

The Effects of Microbial Fe(III) reduction on Clay Sediment Flocculation and Mineral Transformation  

NASA Astrophysics Data System (ADS)

This study was undertaken to investigate physicochemical properties of smectite associated with microbial reduction of structural Fe(III). Iron reducing bacterium, Shewanella oneidensis were inoculated with formate as the electron donor and smectite as the sole electron acceptor for the intervals of 3, 12, 24, and 48 hours in anaerobic chamber. The extent of Fe(III) reduction was observed to reach up to 9%. The control, containing microwave radiation heat-killed bacterial cells and M1 media plus formate, was prepared from the same smectite sample. Settling experiments were performed in anaerobic chamber for 1) the bioreduced nontronite samples which contain viable cells and biopolymers secreted by bacteria, with variable incubation time points, and 2) abiotic nonreduced controls having dead cells (no biopolymers). Furthermore, the separate set of incubation was prepared in aerobic condition where the microbial Fe-respiration does not prevail, but viable bacteria produced the biopolymers, and then suspended in a settling column in aerobic condition. Compared with abiotic nonreduced control, Micromeritics Sedigraph measured 2.3-m increase of mean aggregate size and a 30-times faster average settling velocity in the bioreduced nontronite suspensions. In addition, the aerobically inoculated nontronite (no Fe-respiration) shows a similar aggregate size distribution to that of an abiotic nonreduced control. Significant changes in physical properties of smectite induced by microbial Fe(III) reduction were directly observed using Environmental Cell Transmission Electron Microscope (EC-TEM). Particularly, neoformation of minerals in bioreduced smectite sample indicate that environmental factor such as bacterial activity should be considered as a geological variable for the mineral transformation studies. Neoformed Illite phase was identified in bioreduced smectite sample that challenge the conventional concept of smectite-to-illite transformation with far-reaching implications. In floc architecture, several domains of smectite packets are glued by biopolymers secreted by bacteria, and the aspect ratio (thickness/length) of individual smectite particle increases from 0.11 to 0.18. We suggest that surface chemistry changes (more negatively charged on smectite surface) induced by microbial Fe(III) reduction more likely to promote the flocculation by absorbing the cations which bridge the smectite particles and the biopolymers resulting in the increase of mean aggregate size.

Kim, J.; Furukawa, Y.; Newell, S.; Daulton, T.; Dong, H.

2003-12-01

254

CLAYFORM: a FORTRAN 77 computer program apportioning the constituents in the chemical analysis of a clay or other silicate mineral into a structural formula  

USGS Publications Warehouse

The FORTRAN 77 computer program CLAYFORM apportions the constituents of a conventional chemical analysis of a silicate mineral into a user-selected structure formula. If requested, such as for a clay mineral or other phyllosilicate, the program distributes the structural formula components into appropriate default or user-specified structural sites (tetrahedral, octahedral, interlayer, hydroxyl, and molecular water sites), and for phyllosilicates calculates the layer (tetrahedral, octahedral, and interlayer) charge distribution. The program also creates data files of entered analyses for subsequent reuse. ?? 1987.

Bodine, Jr. , M. W.

1987-01-01

255

Clay technology and well stimulation  

Microsoft Academic Search

Pores in sedimentary rocks may be lined or filled with a variety of different clay minerals. These clays can greatly reduce permeability, increase acid or fresh water sensitivity, totally alter the electric log response, and increase irreducible water saturation. The composition of the clays is of great importance in reservoir management. Different clays have different composition, and thus will react

W. R. Almon; D. K. Davies

1978-01-01

256

Clay technology and well stimulation  

Microsoft Academic Search

Pores in sedimentary rocks may be lined or filled with a variety of different clay minerals. These clays can greatly reduce permeability, increase acid or freshwater sensitivity, totally alter the electric log response, and increase irreducible water saturations. The composition of the clay is of great importance in reservoir management. Different clays have different compositions, and thus will react differently

1978-01-01

257

How clays weaken faults.  

NASA Astrophysics Data System (ADS)

The weakness of upper crustal faults has been variably attributed to (i) low values of normal stress, (ii) elevated pore-fluid pressure, and (iii) low frictional strength. Direct observations on natural faults rocks provide new evidence for the role of frictional properties on fault strength, as illustrated by our recent work on samples from the San Andreas Fault Observatory at Depth (SAFOD) drillhole at Parkfield, California. Mudrock samples from fault zones at ~3066 m and ~3296 m measured depth show variably spaced and interconnected networks of displacement surfaces that consist of host rock particles that are abundantly coated by polished films with occasional striations. Transmission electron microscopy and X-ray diffraction study of the surfaces reveal the occurrence of neocrystallized thin-film clay coatings containing illite-smectite (I-S) and chlorite-smectite (C-S) phases. X-ray texture goniometry shows that the crystallographic fabric of these faults rocks is characteristically low, in spite of an abundance of clay phases. 40Ar/39Ar dating of the illitic mix-layered coatings demonstrate recent crystallization and reveal the initiation of an "older" fault strand (~8 Ma) at 3066 m measured depth, and a "younger" fault strand (~4 Ma) at 3296 m measured depth. Today, the younger strand is the site of active creep behavior, reflecting continued activation of these clay-weakened zones. We propose that the majority of slow fault creep is controlled by the high density of thin (< 100nm thick) nano-coatings on fracture surfaces, which become sufficiently smectite-rich and interconnected at low angles to allow slip with minimal breakage of stronger matrix clasts. Displacements are accommodated by localized frictional slip along coated particle surfaces and hydrated smectitic phases, in combination with intracrystalline deformation of the clay lattice, associated with extensive mineral dissolution, mass transfer and continued growth of expandable layers. The localized concentration of smectite in both I-S and C-S minerals, which probably extends to greater depths (<10 km) is responsible for fault weakening, with cataclasis and fluid infiltration creating nucleation sites for neomineralization on displacement surfaces during continued faulting. The role of newly grown, ultrathin, hydrous clay coatings on displacement surfaces in the San Andreas Fault contrasts with previously proposed scenarios of reworked talc/serpentine phases as an explanation for weak faults and creep behavior at these depths.

van der Pluijm, Ben A.; Schleicher, Anja M.; Warr, Laurence N.

2010-05-01

258

Geotechnical evaluation of Turkish clay deposits: a case study in Northern Turkey  

NASA Astrophysics Data System (ADS)

Clay deposits in Oltu-Narman basins (Erzurum, northern Turkey) have been studied to determine their engineering properties and to evaluate their uses for geotechnical applications. These deposits are concentrated in two different stratigraphic horizons namely the Late Oligocene and the Early Miocene sequences. Clay-rich fine-grained sedimentary units are deposited in shallow marine and lagoonar mixed environments. Their clay minerals originated by the alteration of Eocene calc-alkaline island-arc volcanics, preferably from pyroclastics (trachite and andesite flow), which form the basement for the Oltu depression. Smectite group clay minerals are found abundant in clay deposits. The experimental results show that the clay soils have high plasticity behaviors and low hydraulic conductivity properties. The optimum water content, the free swell, and the swelling pressure of clay samples decreased and the maximum dry unit weight of clay samples increased under high temperature. Consequently, it is concluded that the expanding of clay soils is an important soil problem that cannot be avoided in the significant parts of Oltu city and its villages. However, the soils of clay-rich layers in the outcrops-section of clay deposits can be successfully used to build compacted clay liners for landfill systems and to construct vertical and horizontal barriers for protection of ground water and for preventing soil pollution in geotechnical applications.

Kalkan, Ekrem; Bayraktutan, M. Salih

2008-09-01

259

Mineral catalysis of the formation of the phosphodiester bond in aqueous solution: The possible role of montmorillonite clays  

Microsoft Academic Search

The binding of adenosine to Na+-montmorillonite 22A is greater than 5'-AMP, at neutral pH. Adenine derivatives bind more strongly to the clay than the corresponding uracil derivatives. These data are consistent with the protonation of the adenine by the acidic clay surface and a cationic binding of the protonated ring to the anionic clay surface. Other forces must be operative

James P. Ferris; Gözen Ertem; Kamaluddin; Vipin Agarwal; Lu Lin Hua

1989-01-01

260

Analysis of ordinary chondrites using powder X-ray diffraction: 1. Modal mineral abundances  

NASA Astrophysics Data System (ADS)

Powder X-ray diffraction (XRD) is used to quantify the modal abundances (in wt%) of 18 H, 17 L, and 13 LL unbrecciated ordinary chondrite falls, which represents the complete petrologic range of equilibrated ordinary chondrites (types 4-6). The XRD technique presents an effective alternative to traditional methods for determining modal abundances, such as optical point counting and electron microprobe phase (EMP) mapping. The majority of chondrite powders in this study were previously prepared for chemical characterization from 8 to 20g of material, which is consistent with the suggested mass (10g) necessary to provide representative sampling of ordinary chondrites. Olivine and low-Ca pyroxene are the most abundant phases present, comprising one-half to three-fourths of total abundances, while plagioclase, high-Ca pyroxene, troilite, and metal comprise the remaining XRD-measured mineralogy. Pigeonite may also be present in some samples, but it is fitted using a high-Ca pyroxene standard, so exact abundances cannot be measured directly using XRD. Comparison of XRD-measured abundances with calculated Cross, Iddings, Pirsson, Washington (CIPW) normative abundances indicates that systematic discrepancies exist between these two data sets, particularly in olivine and high-Ca pyroxene. This discrepancy is attributed to the absence of pigeonite as a possible phase in the CIPW normative mineralogy. Oxides associated with pigeonite are improperly allocated, resulting in overestimated normative olivine abundances and underestimated normative high-Ca pyroxene abundances. This suggests that the CIPW norm is poorly suited for determining mineralogical modal abundances of ordinary chondrites.

Dunn, Tasha L.; Cressey, Gordon; McSween, Harry Y. _jr., Jr.; McCoy, Timothy J.

2010-01-01

261

Influence of sodium chloride, carbonates, and iron hydroxides on the viscosity of aqueous suspensions of clay minerals  

Microsoft Academic Search

The influence of sodium chloride solutions containing carbon dioxide on the viscosity of a maximally destroyed structure of suspensions of hydromica, kaolinite, natural iron-containing polymineral carbonate clay, iron oxides, and freshly prepared and dried montmorillonite is studied. The effect of physicochemical transformations of finely dispersed carbonates on the surface structure of a dispersed phase in suspensions of clay and iron

I. G. Kovzun; I. M. Kovalenko; I. T. Protsenko

2005-01-01

262

Minerals  

MedlinePLUS

Minerals are important for your body to stay healthy. Your body uses minerals for many different jobs, including building bones, making ... regulating your heartbeat. There are two kinds of minerals: macrominerals and trace minerals. Macrominerals are minerals your ...

263

The role of clay minerals and fulvic acid to the complexation of Na, Mg, and Ca in stream flows from adjacent forested head watersheds composed of different vegetation  

NASA Astrophysics Data System (ADS)

In order to understand the complexation and flow process in metal elements under a fresh water environment, discharges of Na, Mg, and Ca were measured in streams of adjacent forested head watersheds composed of coniferous evergreen- and deciduous broad leaf- trees. Total elements (T-Na, T-Mg, and T-Ca) and ions (Na+, Mg2+, and Ca2+) in stream flows which passed through 0.45 ?m filters were measured with an ICP and Ion-chromatograph. The remainders of total elements and ions were equated with complex compounds. Then the discharges of Si and fulvic acid, which respectively are the representatives of ligands by clay minerals and humic substances, provided the relationship between the compound discharges and the complexation process of the above metal elements. Even if Na, Mg, and Ca are believed to be mostly free ions in fresh water environments, the rates of the compounds to the total elements ranged 10 to 40 % in the coniferous watershed and 20 to 60 % in the deciduous watersheds. The compounds sometimes occupied more than half of the total elements; this was predominant in the deciduous watershed. These mean that the discharge of compounds is not negligible in watershed hydrology. Possible complexation processes in metal elements are #1) Hydration, #2) Adsorption or substitution with clay minerals, #3) Mineral complex, #4) Adsorption with humic substances as represented by fulvic acid, and #5) Chelate with organic acids as oxalate, formic acid, and pyrrole. Under fresh water environments, #2 and #4 must be the most potential processes of the complexation in metal elements. The relationship between the compounds, Si, and fulvic acid, therefore, supplies useful information to presume the status of the compounds. The compounds-Si relations in both watersheds showed linear correlations (r=0.79 to 0.99) for a stream base flow and stream flow in a small rainstorm. The linear correlations, however, occurred only for the stream flow in the compounds-Si relations at a big rain storm in the deciduous watershed (r=0.89 to 1.00) and also for the storm flow in the compound-fulvic acid relations (r=0.95 to 0.99). These things mean that the metal elements possibly flowed out as organic and/or inorganic complexes and the complexation could have been promoted in the deciduous watershed during rain storms. Thick organic soil, broadly distributing in the deciduous watershed, seems to be reasonable for promoting such complexation due to subsurface water movement in the soil through the contact of the metal elements with clay minerals and fulvic acid. In contrast, the much rainwater flows down below the surface within the loose litter and root-permeated zone developing predominantly in the coniferous watershed, where small clay minerals and humic substances occurs; which represents the rare contact of the metal elements with the clay minerals and fulvic acid in such flow paths. This would be the reason for the small and restrained complexation in the coniferous watershed at the big rain storm. The hydrochemical process in slope-stream systems can be controlled by the complexation affected by both the flow path of rainwater and the distribution of clay minerals and humic substances in soils.

Terajima, Tomomi; Moriizumi, Mihoko; Nakamura, Tomohiro

2010-05-01

264

CO2-Brine-Iron-bearing Clay Mineral Interactions: Surface Area Changes and Fracture-Filling Potentials in Geologic CO2 Sequestration  

NASA Astrophysics Data System (ADS)

Geologic carbon dioxide sequestration (GCS) is a promising option to reduce anthropogenic CO2 emission from coal-fired power plants. The injected CO2 in GCS sites can induce dissolution of rocks and secondary mineral formation, potentially change the physical properties of the geological formations, and thus influence the transport and injectivity of CO2. However, most of the relevant studies are based on hydrological transport, using simulation models rather than studying actual interfacial chemical reactions. The mechanisms and kinetics of interfacial reactions among supercritical CO2 (scCO2)-saline water-rock surfaces at the molecular scale and their impacts on CO2 leakage have not been well understood. This research investigated the effects of various environmental factors (such as temperature, pressure, salinity, and different metal ion and organic-containing brine) on the dissolution and surface morphological changes of clay minerals. In this work, iron-bearing clay mineral, biotite [K(Mg,Fe)3AlSi3O10(OH,F)2], was used for model clay minerals in potential GCS sites. Both fluid/solid chemistry analysis and interfacial topographic studies were conducted to investigate the dissolution/precipitation on clay mineral surfaces under GCS conditions in high salinity systems. Using atomic force microscopy (AFM) and scanning electron microscopy (SEM), the interfacial surface morphology changes were observed. Shortly after a CO2 pressure of 102 atm is applied at 95oC, in situ pH of solutions was 3.15 ± 0.10. The early intrinsic dissolution rates of biotite were 8.4 ± 2.8 × 10-13 and 11.2 ± 3.0 × 10-13 mol Si m-2s-1 in water and NaCl solution, respectively. At the early stage of reaction, fast growth of fibrous illite on biotite basal planes was observed. After 22-70 h reaction, the biotite basal surface cracked, resulting in illite detaching from the surfaced. Later, the cracked surface layer was released into solution, thus the inner layer was exposed as a renewed flat basal surface (96-120 h). The cracking and detachment of the biotite surface layer increased the surface area in contact with solution and accelerated biotite dissolution. In control experiments with water under the same temperature and pressure, neither macroscopic fibrous illite nor cracks were observed. On the other hand, on the edge surfaces or fractured surfaces of biotite, significant amounts of Al-substituted goethite and kaolinite were formed, which can be further investigated as caprock self-healing potentials of iron-bearing clay minerals. This study provides important fundamental information for a better understanding of porosity and permeability changes owing to the clay mineral's surface morphological evolution by geochemical reactions, and this also helps designing a more accurate reactive transport models under GCS conditions.

Jun, Y.; Hu, Y.

2011-12-01

265

On the origin of mixed-layered clay minerals from the San Andreas Fault at 2.5-3 km vertical depth (SAFOD drillhole at Parkfield, California)  

NASA Astrophysics Data System (ADS)

A detailed mineralogical study is presented of the matrix of mudrocks sampled from spot coring at three key locations along the San Andreas Fault Observatory at depth (SAFOD) drill hole. The characteristics of authigenic illite-smectite (I-S) and chlorite-smectite (C-S) mixed-layer mineral clays indicate a deep diagenetic origin. A randomly ordered I-S mineral with ca. 20-25% smectite layers is one of the dominant authigenic clay species across the San Andreas Fault zone (sampled at 3,066 and 3,436 m measured depths/MD), whereas an authigenic illite with ca. 2-5% smectite layers is the dominant phase beneath the fault (sampled at 3,992 m MD). The most smectite-rich mixed-layered assemblage with the highest water content occurs in the actively deforming creep zone at ca. 3,300-3,353 m (true vertical depth of ca. 2.7 km), with I-S (70:30) and C-S (50:50). The matrix of all mudrock samples show extensive quartz and feldspar (both plagioclase and K-feldspar) dissolution associated with the crystallization of pore-filling clay minerals. However, the effect of rock deformation in the matrix appears only minor, with weak flattening fabrics defined largely by kinked and fractured mica grains. Adopting available kinetic models for the crystallization of I-S in burial sedimentary environments and the current borehole depths and thermal structure, the conditions and timing of I-S growth can be evaluated. Assuming a typical K+ concentration of 100-200 ppm for sedimentary brines, a present-day geothermal gradient of 35°C/km and a borehole temperature of ca. 112°C for the sampled depths, most of the I-S minerals can be predicted to have formed over the last 4-11 Ma and are probably still in equilibrium with circulating fluids. The exception to this simple burial pattern is the occurrence of the mixed layered phases with higher smectite content than predicted by the burial model. These minerals, which characterize the actively creeping section of the fault and local thin film clay coating on polished brittle slip surfaces, can be explained by the influence of either cooler fluids circulating along this segment of the fault or the flow of K+-depleted brines.

Schleicher, A. M.; Warr, L. N.; van der Pluijm, B. A.

2009-02-01

266

Mineral resource abundance and regional growth in Spain, 1860-2000  

Microsoft Academic Search

The natural resource curse hypothesis predicts that natural resource windfalls can reduce the long run level of income per capita by crowding out manufacturing, slowing down the accumulation of human capital, damaging institutions and increasing inequality. This paper explores some of the central tenets of the natural resource curse literature by exploiting variation in mineral resources in Spain from 1860

Jordi Domenech

2008-01-01

267

Quantifying mineral abundances of complex mixtures by coupling spectral deconvolution of SWIR spectra (2.1-2.4 ?m) and regression tree analysis  

USGS Publications Warehouse

This paper presents a methodology for assessing mineral abundances of mixtures having more than two constituents using absorption features in the 2.1-2.4 ?m wavelength region. In the first step, the absorption behaviour of mineral mixtures is parameterised by exponential Gaussian optimisation. Next, mineral abundances are predicted by regression tree analysis using these parameters as inputs. The approach is demonstrated on a range of prepared samples with known abundances of kaolinite, dioctahedral mica, smectite, calcite and quartz and on a set of field samples from Morocco. The latter contained varying quantities of other minerals, some of which did not have diagnostic absorption features in the 2.1-2.4 ?m region. Cross validation showed that the prepared samples of kaolinite, dioctahedral mica, smectite and calcite were predicted with a root mean square error (RMSE) less than 9 wt.%. For the field samples, the RMSE was less than 8 wt.% for calcite, dioctahedral mica and kaolinite abundances. Smectite could not be well predicted, which was attributed to spectral variation of the cations within the dioctahedral layered smectites. Substitution of part of the quartz by chlorite at the prediction phase hardly affected the accuracy of the predicted mineral content; this suggests that the method is robust in handling the omission of minerals during the training phase. The degree of expression of absorption components was different between the field sample and the laboratory mixtures. This demonstrates that the method should be calibrated and trained on local samples. Our method allows the simultaneous quantification of more than two minerals within a complex mixture and thereby enhances the perspectives of spectral analysis for mineral abundances.

Mulder, V.L.; Plotze, Michael; de Bruin, Sytze; Schaepman, Michael E.; Mavris, C.; Kokaly, Raymond F.; Egli, Markus

2013-01-01

268

Redox properties of structural Fe in clay minerals. 2. Electrochemical and spectroscopic characterization of electron transfer irreversibility in ferruginous smectite, SWa-1.  

PubMed

Structural Fe in clay minerals is an important, albeit poorly characterized, redox-active phase found in many natural and engineered environments. This work develops an experimental approach to directly assess the redox properties of a natural Fe-bearing smectite (ferruginous smectite, SWa-1, 12.6 wt % Fe) with mediated electrochemical reduction (MER) and oxidation (MEO). By utilizing a suite of one-electron-transfer mediating compounds to facilitate electron transfer between structural Fe in SWa-1 and a working electrode, we show that the Fe2+/Fe3+ couple in SWa-1 is redox-active over a large range of potentials (from E(H) = -0.63 V to +0.61 V vs SHE). Electrochemical and spectroscopic analyses of SWa-1 samples that were subject to reduction and re-oxidation cycling revealed both reversible and irreversible structural Fe rearrangements that altered the observed apparent standard reduction potential (E(H)(ø)) of structural Fe. E(H)(ø)-values vary by as much as 0.56 V between SWa-1 samples with different redox histories. The wide range of E(H)-values over which SWa-1 is redox-active and redox history-dependent E(H)(ø)-values underscore the importance of Fe-bearing clay minerals as redox-active phases in a wide range of redox regimes. PMID:22827558

Gorski, Christopher A; Klüpfel, Laura; Voegelin, Andreas; Sander, Michael; Hofstetter, Thomas B

2012-08-23

269

Clay minerals in sediments of Portuguese reservoirs and their significance as weathering products from over-eroded soils: a comparative study of the Maranhão, Monte Novo and Divor Reservoirs (South Portugal)  

NASA Astrophysics Data System (ADS)

The Southern region of Portugal is subjected to several forms of over-erosion. Most leached products, mainly composed of fine particles containing nutrients, metals or pesticides, are easily transported by river flows. When these are hindered by a physical barrier such as a dam, the particulate load accumulates on the bottom of the reservoirs, often leading to a pronounced decrease of water quality. Bottom sediments from three reservoirs were subjected to grain-size analysis and a study of clay minerals by X-ray diffraction. Most sediments contain a diverse set of clay minerals, mostly illites, smectites, chlorites and kaolinites. The nature of the clay minerals reflects the nature of the parent rocks. During the cycles of transport and temporary deposition, they may undergo significant chemical and physical transformations, which lead to an increase of expandable properties and therefore, to a higher cationic exchange capacity, determining its important role as vehicles of environmental pollutants.

Fonseca, Rita M. F.; Barriga, Fernando J. A. S.; Conceição, Patrícia I. S. T.

2010-12-01

270

Comment on "Evaluation of X-ray diffraction methods for determining the crystal growth mechanisms of clay minerals in mudstones, shales and slates," by L. N. Warr and D. R. Peacor  

USGS Publications Warehouse

A recent paper by Warr and Peacor (2002) suggested that our use of the Bertaut-Warren-Averbach technique (MudMaster computer program) for studying changes in crystallite thickness distributions (CTDs) of clay minerals during diagenesis and very low-grade metamorphism is not reliable because it is dependent on many variables which can not be fully controlled. Furthermore, the authors implied that the measured shapes of CTDs cannot be used with confidence to deduce crystal growth mechanisms and histories for clays, based on our CTD simulation approach (using the Galoper computer program). We disagree with both points, and show that the techniques are powerful, reliable and useful for studying clay mineral alteration in rocks. ?? 2003 Schweiz. Mineral. Petrogr. Ges.

Eberl, D. D.; Srodon, J.; Drits, V. A.

2003-01-01

271

Sorption of metal ions on clay minerals. III. Nucleation and epitaxial growth of Zn phyllosilicate on the edges of hectorite  

NASA Astrophysics Data System (ADS)

The impact of dissolved Si ([Si] aq) on Zn uptake in dilute suspensions (0.65 g/L) of hectorite was investigated at pH 7.30, a total Zn concentration (TotZn) of 520 ?M, and ionic strength of 0.3 M (NaNO 3 salt) by kinetics experiments and polarized extended X-ray absorption fine structure (P-EXAFS) spectroscopy. At low [Si] aq (˜30 to 60 ?M), 5.8% of TotZn was adsorbed within the first 3 h of reaction. The sorption rate was lower afterwards, and Zn uptake amounted to 14.6% of TotZn after 168 h of reaction. These rates are consistent with Zn sorption on pH-dependent edge sites of hectorite platelets. At high [Si] aq (˜530 ?M), a higher initial sorption rate was observed, the fraction of Zn removed amounting to 15.2% of TotZn at t = 3 h and 90.7% at t = 120 h. After 9 h of reaction time, Si uptake also occurred; the Si/Zn uptake ratio (1.09 ± 0.08) was between those of TO (˜0.67) and TOT (˜1.33) trioctahedral phyllosilicates, which suggests the neoformation of a Zn phyllosilicate. In the absence of hectorite, neither Zn nor Si were removed from solution, even at high [Si] aq, indicating that Zn uptake occurred by sorption on hectorite surface. Comparison of spectra for sorption samples and Zn references indicated that sorbed Zn was located in a clay-like structural environment. The angular dependence observed for all P-EXAFS spectra demonstrated that Zn cations are structurally attached to the edges of hectorite platelets. The size and structure of these Zn surface complexes varied with [Si] aq and reaction time. At low [Si] aq and after a long reaction time (t = 96 h), Zn was surrounded by in-plane 1.7 ± 0.6 Zn and 1.4 ± 0.3 Mg at 3.08 Å, and by out-of-plane 0.6 ± 1.1 Si at 3.28 Å. These results point to predominant formation of small polymers containing on average two to three Zn cations and located in structural continuity with the hectorite octahedral sheet. At high [Si] aq, higher numbers of Zn and Si and lower numbers of Mg neighbors were detected at t = 9 h; at t = 120 h, Zn was surrounded by in-plane 6.0 ± 0.4 Zn at 3.10 Å and by out-of-plane 3.6 ± 0.4 Si at 3.27 Å as in a Zn phyllosilicate. These results document for the first time the nucleation and epitaxial growth at ambient temperature of Zn phyllosilicate at the edges of smectite minerals under controlled laboratory conditions.

Schlegel, Michel L.; Manceau, Alain; Charlet, Laurent; Chateigner, Daniel; Hazemann, Jean-Louis

2001-11-01

272

Study on the characteristics of granular clay minerals for the adsorption and recovery of metal ions (3).  

National Technical Information Service (NTIS)

Granular pillared clay (GPILC) as new adsorbent prepared successfully from powder-typed Na-bentonite using pillaring agents such as AlCl(sub 3) and ZrOCl(sub 2) was investigated to study the adsorption and recovery of metal ions in aqueous solution. The a...

C. H. Eum B. I. Choi S. Y. Kim K. S. Jung

1996-01-01

273

Minerals  

MedlinePLUS

... commercials for breakfast cereal always mention vitamins and minerals ? But when you think of minerals, food isn't the first thing that comes to mind. Aren't minerals something you find in the earth, like iron ...

274

Tracing the Southwest African climate development during the Miocene - changes in elemental distribution and clay mineral composition at DSDP Site 530A (southeastern Angola Basin)  

NASA Astrophysics Data System (ADS)

During the middle and late Miocene the climatic system in Southwest Africa was reorganized leading to generally drier conditions as known from today. The reason for this was the cooling of the coastal-near ocean by the initialization of the Benguela Current. Thus the temperature difference between the continent and the sea increased and a system of seaward blowing winds developed. This lead to (1) the development of the Benguela Upwelling System in front of the Namibian coast and (2) it prevented the landward flow of humid air masses. The Mid-Miocene climate change in SW-Africa has been shown by data-sets from the Cape Basin and the Walvis Ridge (Kastanja et al., 2006; Westerhold et al., 2005; Diester-Haass et al., 2002; Roters & Henrich, in press). The DSDP Site 530A is situated in the SE corner of the Walvis Basin at the toe of the Walvis Ridge in a water depth of 4629 m. Today the distance to the coast is about 285 km. The idea is to trace the climatic development between 19 and 9 Myr with the help of (1) a clay mineral record and (2) the results of XRF-scanning of the core. The sediment is carbonate-depleted, which, inversely, enriches the terrigenous components. On the other hand mass accumulation rates are low and the age control of the sediments is difficult. XRF scanning was done on the archive cores at the MARUM, Bremen in a resolution of about 10 kyr, while the clay mineral contents were measured in the isolated clay fraction (< 2µm) on a XRD machine at the AWI, Bremerhaven in a 100 kyr resolution. By grain size analysis it was found that the content of clays (fraction < 2µm) of the sediments averages out to about 75%. The most prominent clays found in the samples are Illites. The remaining material is nearly completely composed of silt. The sediments could have been transported to site 530A by three different processes: (1) in the sediment load of the Kunene River and onwards by surface ocean currents, (2) with the dust load from the African continent and (3) by deeper ocean and bottom currents. In a previous grain size study of these sediments no indications for bottom currents were found. Material, which was suspicious to be transported by mass wasting events, has been excluded from this study. The grain size analysis showed a general coarsening of sediment after 11.5 Myr, when the Benguela Current system began to work. Also peaks of coarser material have been found before that general change. The scope of the here presented work is to trace these developments with chemical data and clay mineral contribution changes. First results show enrichment in Iron and Titanium contents after 11.5 Myr that is explained with higher dust input to the ocean. Literature: Diester-Haass, L., Meyers, P.A., Vidal, L. (2002): The late Miocene onset of high productivity in the Benguela Current upwelling system as part of a global pattern. - Mar. Geol., 180(1-4):87-103. Kastanja, M.M., Diekmann, B., Henrich, R. (2006): Controls on carbonate and terrigenous deposition in the incipient Benguela upwelling system during the middle to the late Miocene (ODP Sites 1085 and 1087).- P3, 241 (3-4):515-530. Roters, B., Henrich, R. (in press): The Middle to Late Miocene climatic development of Southwest Africa derived from the sedimentological record of ODP Site 1085A.- Intl. Jour. Earth Sci., DOI: 10.1007/s00531-008-0398-9. Westerhold, T., Bickert, T., Röhl, U. (2005): Middle to late Miocene oxygen isotope stratigraphy of ODP site 1085 (SE Atlantic): new constrains on Miocene climate variability and sea-level fluctuations.- P3, 217 (3-4):205-222.

Roters, B.

2009-04-01

275

Trace element abundance determinations by Synchrotron X Ray Fluorescence (SXRF) on returned comet nucleus mineral grains  

NASA Astrophysics Data System (ADS)

Trace element analyses were performed on bulk cosmic dust particles by Proton Induced X Ray Emission (PIXE) and Synchrotron X Ray Fluorescence (SXRF). When present at or near chondritic abundances the trace elements K, Ti, Cr, Mn, Cu, Zn, Ga, Ge, Se, and Br are presently detectable by SXRF in particles of 20 micron diameter. Improvements to the SXRF analysis facility at the National Synchrotron Light Source presently underway should increase the range of detectable elements and permit the analysis of smaller samples. In addition the Advanced Photon Source will be commissioned at Argonne National Laboratory in 1995. This 7 to 8 GeV positron storage ring, specifically designed for high-energy undulator and wiggler insertion devices, will be an ideal source for an x ray microprobe with one micron spatial resolution and better than 100 ppb elemental sensitivity for most elements. Thus trace element analysis of individual micron-sized grains should be possible by the time of the comet nucleus sample return mission.

Flynn, G. J.; Sutton, S. R.

276

Clay complexes support HDS catalyst.  

SciTech Connect

Hydroprocessing represents a crucial component of petroleum refining operations both in terms of environmental and economic considerations. Regulations concerning maximum amount of sulfur content of gasoline and emissions of sulfur-oxide compounds upon combustion are becoming more and more stringent. One 1994-2000 focus of Argonne National Laboratory (ANL) has been the development of catalysts for hydrodesulfurization (HDS). Typical HDS catalysts are comprised of Co-Mo sulfides or Ni-Mo sulfides on an alumina support. Modification of the pore structure of the support has generated great attention among researchers. Most desulfurization test reactions have used dibenzothiophene (DBT) as the model compound to test various configurations of support material with Co-Mo-S and Ni-Mo-S catalysts. In this testing, the desired product would be biphenyl and hydrogen sulfide (H{sub 2}S). A competing reaction creates cyclohexylbenzene by saturating one aromatic ring prior to desulfurization. Ring saturation requires more costly hydrogen and is not desirable. Fortunately, a more effective catalyst for adding hydrogen at the sulfur site with hydrogenating the aromatic rings has been found. However, this has only been tested on DBT. HDS uses various types of catalysts to add hydrogen to reduce unwanted sulfur compounds. Typically this requires expensive, high-pressure, high-temperature equipment to produce the environmentally friendly low-sulfur fuels. ANL scientists identified several new desulfurization catalysts with improved HDS activity and selectivity. From these new catalysts, it may be possible to achieve HDS processing at lower temperature and pressure. The catalysts used for HDS at ANL are various clay complexes. Natural clays have a history of use in the hydroprocessing industry since they are abundant and inexpensive. ANL's approach is to create synthetic organo-clay complexes (SOCC). An advantage of SOCCs is that the pore size and distribution can be controlled by the synthesis method, and the purity of the synthetic clays is high compared to naturally occurring clay minerals.

Marshall, C. L.; Carrado, K.; Chemical Engineering

2000-01-01

277

Minerals  

NSDL National Science Digital Library

This interactive lesson on minerals starts with a definition of minerals and compares crystalline and amorphous minerals. The composition is discussed and a chart shows the relative amounts of elements in minerals. Next, there is a discussion of the characteristics by which minerals are identified including luster, color, streak, hardness, and cleavage and fracture along with special properties such as magnetism. The characteristics of calcite, talc, hematite, magnetite, and galena are then observed.

278

Arsenic mineralization, source, distribution, and abundance in the Kutahya region of the western Anatolia, Turkey.  

PubMed

Environmental exposure to arsenic (As) in the Kutahya region of the western Anatolia, Turkey has been reported to cause various types of arsenic-associated skin disorders (Dogan, Dogan, Celebi, & Baris, 2005). A geological and mineralogical study was conducted to find the sources and distribution of the As. Geogenic (background) levels were measured in samples collected from various sources in the Gediz, Simav, Tavsanli, Emet, Yoncali, Yenicekoy, and Muratdagi areas of the Kutahya region. Based on this analysis, we determined that natural sources are a domineering factor affecting the distribution of As, which was found: (1) mainly in evaporitic minerals, including colemanite (269-3900 ppm) and gypsum (11-99,999 ppm), but also in alunite (7-10 ppm) and chert (54-219 ppm); (2) in secondary epithermal gypsum, which has a high concentration of As in the form of realgar and orpiment along fracture zones of Mesozoic and Cenozoic carbonate aquifers; (3) in rocks, including limestone/dolomite (3-699 ppm) and travertine (5-4736 ppm), which are relatively more enriched in As than volcanics (2-14 ppm), probably because of secondary enrichment through hydrological systems; (4) in coal (1.9-46.5 ppm) in the sedimentary successions of the Tertiary basins; (5) in thermal waters, where As is unevenly distributed at concentrations varying from 0.0-0.9 mg/l. The highest As concentrations in thermal water (Gediz and Simav) correlate to the higher pH (7-9.3) and T (60-83 degrees C) conditions and to the type of water (Na-HCO3-SO4 with high concentration of Ca, Mg, K, SiO2, and Cl in the water). Changes in pH can be related to some redox reactions, such as the cation exchange reactions driving the dissolution of carbonates and silicates. Fe-oxidation, high pH values (7-9.3), presence of other trace metals (Ni, Co, Pb, Zn, Al), increased salinity (Na, Cl), high B, Li, F, and SiO, high Fe, SO4 (magnetite, specularite-hematite, gypsum), and graphite, and the presence of U, Fe, Cu, Pb, Zn, and B, especially in the Emet, Gediz, and Simav areas, are the typical indicators for the geothermally affected water with high As content. A sixth source of As in this region is the ground (0.0-10.7 mg/l) and the surface waters (0.0022-0.01 mg/l), which are controlled by water-rock interaction, fracture system, and mixing/dilution of thermal waters. The high As concentration in groundwater corresponds to the areas where pathological changes are greatest in the habitants. Arsenic in ground water also effects ecology. For example, only Juriperus oxycedrus and J. varioxycedrus types of vegetation are observed in locations with the highest concentration of As in the region. Branches and roots of these plants are enriched in As. PMID:17288006

Dogan, Meral; Dogan, A Umran

2007-04-01

279

Reflectance Spectroscopy of Clay-Sulfate Mixtures: Implications for Quantifying Hydrated Minerals and Determining Depositional Environments on Mars  

NASA Astrophysics Data System (ADS)

We examine the spectral properties of a suite of binary mixtures containing hydrated magnesium sulfate mixed with varying proportions of Fe, Mg, or Al-smectite. Our results will aid in interpreting CRISM and OMEGA spectra of hydrated mineral deposits.

Stack, K. M.; Milliken, R. E.

2011-03-01

280

Reflectance Spectroscopy of Clay-Sulfate Mixtures: Implications for Quantifying Hydrated Minerals and Determining Depositional Environments on Mars  

Microsoft Academic Search

We examine the spectral properties of a suite of binary mixtures containing hydrated magnesium sulfate mixed with varying proportions of Fe, Mg, or Al-smectite. Our results will aid in interpreting CRISM and OMEGA spectra of hydrated mineral deposits.

K. M. Stack; R. E. Milliken

2011-01-01

281

Variability of fluvial sediment supply to the Laptev Sea continental margin during Late Weichselian to Holocene times: implications from clay-mineral records  

NASA Astrophysics Data System (ADS)

Three sediment cores from the Laptev Sea continental margin were investigated for their clay mineralogy by X-ray diffraction to study the fluvial sediment supply since the late Weichselian. In the study area, the clay-mineral composition of surface sediments is characterized by distinct regional variations. The source area for smectite in the eastern Eurasian Basin is the Putoran Plateau drained by the Khatanga and Yenisei rivers. Currents caused by river discharge and the inflow of Atlantic water masses along the Eurasian continental margin are responsible for sediment distribution. In the sediment cores, smectite and illite contents show an opposite trend which mainly results from variable smectite supply. During MIS 2 the amount of smectite on the Laptev Sea continental margin never exceeds 10 rel.%. Probably, reduced river discharge and the lowered sea level during MIS 2 caused a decreased sediment supply to the Laptev Sea. Additionally, the Putoran Plateau was covered by an ice sheet during the Late Weichselian preventing the erosion of smectite-rich soils. In contrast, maximum smectite contents (up to 30 rel.%) in Holocene sediments result from increased sediment input by the Khatanga River and from the Kara Sea through the Vilkitsky Strait and via St. Anna Trough into the western Laptev Sea.

Müller, Claudia; Stein, Ruediger

2000-08-01

282

Ball clay  

USGS Publications Warehouse

The article reports on the global market performance of ball clay in 2009 and presents an outlook for its 2010 performance. Several companies mined ball call in the country including Old Hickey Clay Co., Kentucky-Tennessee Clay Co., and H.C. Spinks Clay Co. Information on the decline in ball clay imports and exports is also presented.

Robert L Virta

2010-01-01

283

Clay mineral analysis of the Hirabayashi NIED drill core on the Nojima fault that ruptured in the 1995 Kobe Earthquake, southwest Japan  

NASA Astrophysics Data System (ADS)

A 1800-m-deep borehole was drilled at Nojima Hirabayashi and penetrated the Nojima fault that was activated at the time of the 1995 Hyogo-ken Nanbu Earthquake (Kobe Earthquake) in Japan. Three possible fracture zones were detected at depths of about 1140 m, 1300 m, and 1800 m. At first, we analyzed the mode of distribution of rocks, minerals and chemical elements in them. There is a foliated blue-gray gouge at a depth of 1140 m. So we infer that this is the central fault plane, and began our fracture zone analysis there, as follows. The degree of fracturing is evidently greater in the hanging wall than in the footwall. We estimated the relative amounts of minerals qualitatively, and we detected not only quartz, orthoclase, plagioclase, biotite and hornblende in the parent rock (granodiorite), but also kaolinite, smectite, laumontite, stilbite, calcite, ankerite and siderite, which are related to hydrothermal alteration. Biotite notably disappears in both the hanging wall and footwall across the central fault plane, although it disappears over a significantly greater distance in the hanging wall than in the footwall. Equally, we estimated the amounts of major chemical elements quantitatively. Al2O3, Fe2O3, MnO, TiO2, and P2O5 all decrease throughout this interval, except at a few points. H2O_{ and CO2 increase throughout the interval. Na2O increases in the region adjacent to the central fault plane, while MgO and CaO increase in the hanging wall and decrease in the footwall. SiO2 and K2O decrease in the hanging wall and increase in the footwall. Next, we particularly investigated about the clay minerals such as smectite. From the drill core, we separated the clay-size fraction and analyzed it by X-Ray Diffractometer (XRD). Incidentally, particle-size separations are based on Stokes_fs law. We prepared oriented samples for XRD and to make it, we used the glass slide method. We measured it both in the air-dried and ethylene glycol-solvated conditions. We analyzed the other fracture zones along this fault in the same way. As a result, about the mode of distribution of rocks minerals and chemical elements, the fracture zone at 1140 m depth is very similar to the fracture zone at 1800 m depth and differs significantly from the fracture zone at 1300 m depth. But, the results of the clay minerals are different among each fracture zone. In air-dried condition, d (001) of smectite are 15 angstrom (at 1140 m depth), 14 angstrom (at 1300 m depth), 14~12 angstrom (at 1800 m depth), respectively (In ethylene glycol-solvated conditions, they are all 17 angstrom). It may suggest the existence of different fluid circulation between shallower and deeper fracture zones.

Matsuda, T.; Omura, K.; Ikeda, R.; Awaji, D.

2002-12-01

284

Minerals  

NSDL National Science Digital Library

This page is from James Madison University's Department of Geology and Environmental Science. It provides an introduction to minerals, an alphabetical list of minerals and dichotomous keys to identifying minerals in PDF. There are also links to other department pages on igneous, sedimentary, and metamorphic rocks.

Fichter, Lynn S.

2000-09-13

285

Minerals  

NSDL National Science Digital Library

Create a poster about minerals! Directions: Make a poster about minerals. (20 points) Include at least (1) large picture (15 points) on your poster complete with labels of every part (10 points). (15 points) Include at least three (3) facts about minerals. (5 points each) (15 points) Write at ...

Walls, Mrs.

2011-01-30

286

Modelling of the physico-chemical behaviour of clay minerals with a thermo-kinetic model taking into account particles morphology in compacted material.  

NASA Astrophysics Data System (ADS)

Modelling of fluid-mineral interactions is largely used in Earth Sciences studies to better understand the involved physicochemical processes and their long-term effect on the materials behaviour. Numerical models simplify the processes but try to preserve their main characteristics. Therefore the modelling results strongly depend on the data quality describing initial physicochemical conditions for rock materials, fluids and gases, and on the realistic way of processes representations. The current geo-chemical models do not well take into account rock porosity and permeability and the particle morphology of clay minerals. In compacted materials like those considered as barriers in waste repositories, low permeability rocks like mudstones or compacted powders will be used : they contain mainly fine particles and the geochemical models used for predicting their interactions with fluids tend to misjudge their surface areas, which are fundamental parameters in kinetic modelling. The purpose of this study was to improve how to take into account the particles morphology in the thermo-kinetic code KINDIS and the reactive transport code KIRMAT. A new function was integrated in these codes, considering the reaction surface area as a volume depending parameter and the calculated evolution of the mass balance in the system was coupled with the evolution of reactive surface areas. We made application exercises for numerical validation of these new versions of the codes and the results were compared with those of the pre-existing thermo-kinetic code KINDIS. Several points are highlighted. Taking into account reactive surface area evolution during simulation modifies the predicted mass transfers related to fluid-minerals interactions. Different secondary mineral phases are also observed during modelling. The evolution of the reactive surface parameter helps to solve the competition effects between different phases present in the system which are all able to fix the chemical elements mobilised by the water-minerals interaction processes. To validate our model we simulated the compacted bentonite (MX80) studied for engineered barriers for radioactive waste confinement and mainly composed of Na-Ca-montmorillonite. The study of particles morphology and reactive surfaces evolutions reveals that aqueous ions have a complex behaviour, especially when competitions between various mineral phases occur. In that case, our model predicts a preferential precipitation of finest particles, favouring smectites instead of zeolites. This work is a part of a PhD Thesis supported by Andra, the French Radioactive Waste Management Agency.

Sali, D.; Fritz, B.; Clément, C.; Michau, N.

2003-04-01

287

Ball clay  

USGS Publications Warehouse

In 2005, four companies including H.C. Spinks Clay, Kentucky-Tennessee Clay, Old Hickory Clay and Unimin mined ball clay in four states. Based on a preliminary survey of the ball clay industry, production reached 1.32 Mt valued at $53.3 million. Tennessee was the leading ball clay producer state with 61% of domestic production, followed by Texas, Mississippi and Kentucky.

Virta, R. L.

2006-01-01

288

Clay Exploration  

NSDL National Science Digital Library

In this activity, learners explore the possibilities of clay as a natural material. At three stations, learners create sculptures, use natural items such as small pebbles, twigs, and pinecones to embellish clay structures, and paint with clay. These activities help learners discover the sensory qualities of clay as a medium.

Museum, Chicago C.

2008-01-01

289

Clay Play  

ERIC Educational Resources Information Center

This article describes how to use clay as a potential material for young children to explore. As teachers, the authors find that their dialogue about the potential of clay as a learning medium raises many questions: (1) What makes clay so enticing? (2) Why are teachers noticing different play and conversation around the clay table as compared to…

Rogers, Liz; Steffan, Dana

2009-01-01

290

Magnetic composites from minerals: study of the iron phases in clay and diatomite using Mössbauer spectroscopy, magnetic measurements and XRD  

NASA Astrophysics Data System (ADS)

Magnetic particles as matrix for enzyme immobilization have been used and due to the enzymatic derivative can be easily removed from the reaction mixture by a magnetic field. This work presents a study about the synthesis and characterization of iron phases into magnetic montmorillonite clay (mMMT) and magnetic diatomaceous earth (mDE) by 57Fe Mössbauer spectroscopy (MS), magnetic measurements and X-ray diffraction (XRD). Also these magnetic materials were assessed as matrices for the immobilization of invertase via covalent binding. Mössbauer spectra of the magnetic composites performed at 4.2 K showed a mixture of magnetite and maghemite about equal proportion in the mMMT, and a pure magnetite phase in the sample mDE. These results were verified using XRD. The residual specific activity of the immobilized invertase on mMMT and mDE were 83 % and 92.5 %, respectively. Thus, both magnetic composites showed to be promising matrices for covalent immobilization of invertase.

Cabrera, M.; Maciel, J. C.; Quispe-Marcatoma, J.; Pandey, B.; Neri, D. F. M.; Soria, F.; Baggio-Saitovitch, E.; de Carvalho, L. B.

2013-03-01

291

Ball clay  

USGS Publications Warehouse

The article discusses the latest developments in the global ball clay mining industry, particularly in the U.S., as of June 2011. It cites several firms that are involved in ball clay mining in the U.S., including HC Spins Clay Co. Inc., the Imerys Group and Old Hickory Clay Co. Among the products made from ball clay are ceramic tiles, sanitaryware, as well as fillers, extenders and binders.

Virta, R. L.

2011-01-01

292

Composition of Clay Minerals from Mudstones in the Nankai Accretionary Prism, Tenryu and Shiono-misaki Canyons  

NASA Astrophysics Data System (ADS)

Recent submersible surveys using KAIKO and Shinkai 6500 resulted in the successful extraction of lithified rock samples from the sidewalls of Tenyru and Shiono-misaki Canyons. Both canyons are deeply incised into the accretionary prism of eastern Nankai Trough, offshore Omaezaki and Kii Peninsula, respectively. The relative heights between adjacent terrace plains and the present canyon bottoms range from 100 to 1200 m. Thus, canyon incision has exposed stratigraphic thicknesses within the accretionary prism comparable to those cored during drilling legs of the Ocean Drilling Program. Quantitative X-ray diffraction analyses show that the suite of mudstone samples contains highly variable proportions of smectite in the clay-size fraction. Percentages of smectite range from 15% to 100% (relative to illite + chlorite + quartz). Twenty-three out of the 43 specimens analyzed contain between 35% and 84% smectite. This discovery has important implications for the forthcoming IODP drilling expeditions associated with the Nankai Trough Seismogenic Zone Experiment. It seems likely that inputs to the subduction zone within the NanTroSEIZE transect area (Kii-Kumano) contain high proportions of detrital smectite, similar to what has been documented in Miocene strata along the Ashizuri transect. Smectite-rich mudstones are particularly important and commonplace within the lower Shikoku Basin facies, which is the interval through which the decollement propagates. Consequently, the subduction zone's fluid-production budgets, as well as pore pressure distributions within and beneath the plate boundary fault, are modulated by the release of interlayer water as the smectite-to-illite reaction progresses in the down-dip direction.

Underwood, M. B.; Guo, J.; Kawamura, K.; Ogawa, Y.; Moore, G. F.

2006-12-01

293

Enzyme-clay interactions and their impact on transformations of natural and anthropogenic organic compounds in soil  

SciTech Connect

Soil is a living system in which enzymes are present either free in solution or bound to clay and clay-humus complexes. Enzyme-clay interactions play a key role in transforming organic compounds in soil environments where the decomposition and synthetic processes are largely catalyzed by enzymes. Scientific evidence indicates that mineral colloids take part in the catalysis of degradative and synthetic reactions of organic compounds. Such information is essential to understanding the role of mineral colloids, the hidden half of the enzyme-mineral colloid complexes, in catalytic reactions. Despite the abundant literature on the enzyme interactions with pure crystalline aluminosilicates, the nature of enzyme association with soil constituents, including both clean and coated clay minerals and other mineral colloids, and the effect on soil processes still remain unclear. This study integrates the existing information, including recent findings on enzyme-mineral colloid interactions and their effect on natural and anthropogenic organic compound transformation in soil. Further, the study focuses on the catalytic role of enzyme-clay complex surfaces in toxic industrial and agricultural compound bioremediation in soil and water environments.

Naidja, A.; Huang, P.M.; Bollag, J.M.

2000-06-01

294

21 CFR 186.1256 - Clay (kaolin).  

Code of Federal Regulations, 2013 CFR

...powder. There are at least three different minerals, kaolinite, dickite, and nacrite, classified as kaolin. Kaolinite or china clay is whiter, less contaminated with extraneous minerals, and less plastic in water. (b) In accordance...

2013-04-01

295

Ball clay  

USGS Publications Warehouse

Four companies — H.C. Spinks Clay Co., Inc., Imerys, Old Hickory Clay Co. and Unimin Corp. — mined ball clay in five U.S. states in 2012. Production, on the basis of preliminary data, was 900 kt (992,000 st), with an estimated value of $42.3 million. This was a slight increase in tonnage from 886 kt (977,000 st), with a value of $40.9 million in 2011. Tennessee was the leading ball clay producing state, with 63 percent of domestic production, followed by Texas, Mississippi, Kentucky and Indiana. Reported ball clay production from Indiana probably was fire clay rather than ball clay. About 69 percent of total ball clay production was airfloat, 20 percent was crude and 11 percent was water-slurried.

Virta, R. L.

2013-01-01

296

Clay Houses  

ERIC Educational Resources Information Center

|In this article, the author describes a project designed for fourth-graders that involves making clay relief sculptures of houses. Knowing the clay houses will become a family heirloom makes this lesson even more worth the time. It takes three classes to plan and form the clay, and another two to underglaze and glaze the final products.|

Pedro, Cathy

2011-01-01

297

Minerals Yearbook: Cuba, 2006.  

National Technical Information Service (NTIS)

Nickel was the most important mineral commodity to the Cuban economy followed by cobalt, which was produced as a byproduct of nickel mining. Other minerals produced in the country included cement, clays, crushed stone, feldspar, salt, and silica sand. Cub...

O. Bermudez-Lugo

2008-01-01

298

Quality Improvement of Lampang Clay for Porcelain Bodies  

Microsoft Academic Search

Lampang clay from Kao Pangka, Thailand was graded into three fractions: particles sizes < 63 microns, < 40 microns, and < 10 microns. Chemical composition, mineral composition, plasticity of moist clay, and rheological properties of clay slip were determined. After firing to various temperatures, fired shrinkage, bending strength, and whiteness were measured. Lampang clay with particles less than 40 microns

Wolfgang Schulle; Kanchana Kaew-kam-nerd; Prasak Thavornyutikarn; Sukon Phanichphant

2002-01-01

299

Clay and man: clay raw materials in the service of man  

Microsoft Academic Search

Clay has always played a major role in human life. Clay raw materials are used and their value recognized in many economic branches, agriculture, civil engineering and environmental studies. This is largely because of their wide-ranging properties, high resistance to atmospheric conditions, geochemical purity, easy access to their deposits near the earth's surface and low price.Clay minerals, the essential constituents

Ji Konta

1995-01-01

300

Evaluating the geochemically induced swelling/shrinkage of the near-field host clay rock using a THC model and the diffuse double layer theory  

NASA Astrophysics Data System (ADS)

One advantage of emplacing nuclear waste in a clay formation is the potential self-sealing capability due to clay swelling. The swelling properties of the near-field host clay rock can be altered due to geochemical factors, including changes in groundwater geochemistry, proportions of exchangeable cations, and swelling clay mineral abundances. The clay host rock can also undergo geochemical changes due to the interaction with the engineered barrier system (EBS) materials. In this paper, coupled thermal, hydrological, and chemical (THC) models are linked with a swelling model based on diffuse double layer (DDL) theory and changes in the swelling properties of clay host rocks in the near field area are evaluated. Findings based on THC simulations using the reaction-transport code TOUGHREACT include: 1) Significant changes in the swelling pressure could be expected depending on various hydrogeologic and geochemical conditions. The change of hydration rate of the EBS (via the adjustment of tortuosity) could have significant effect on the swelling pressure. 2) Geochemically-induced swelling/shrinkage only occurs in the near-field area, within a few meters from the EBS interface. 3) Swelling/shrinkage induced porosity change is generally much smaller than that caused by mineral precipitation/dissolution. 4) The geochemically-induced swelling/shrinkage of host clay rock is the combined effect of variation in the pore water geochemistry, exchangeable cations, and smectite abundance. Neglecting any of these three latter factors might lead to a miscalculation of the geochemically-induced swelling pressure.

Zheng, L.; Liu, H.; Birkholzer, J. T.; Houseworth, J. E.; Sonnenthal, E. L.

2011-12-01

301

MSL at Gale Crater: What do the clays tell?  

NASA Astrophysics Data System (ADS)

One of the key reasons of the selection of Gale crater as the MSL landing site is the presence of clay minerals in several thin beds of its lower member (Milliken et al. 2010). The presence of sulfate-bearing beds below and above the clay-bearings beds however makes the origin of clay minerals at Gale ambiguous. Previous and ongoing analyses of CRISM and OMEGA show that the Martian clay minerals have very diverse compositions and geological settings. We will present new evidences of clay mineral formation cycles during early Mars, which have similarities with the present Earth clay cycles. We will thus connect the aqueous-related characteristics of Gale to the Martian global clay cycle in order to better constrain the formation processes of clays at Gale and to relate the future MSL observations to planetary scale processes relevant to past habitability.

Poulet, F.; Carter, J.; Bibring, J.; Murchie, S. L.

2011-12-01

302

Joint clay-heavy-light mineral analysis: a tool to investigate the hydrographic-hydraulic regime of Late Cenozoic deltaic inland fans under changing climatic conditions (Cuvelai-Etosha Basin, Namibia)  

NASA Astrophysics Data System (ADS)

An interdisciplinary study (major and minor elements, C and O isotopes, heavy and light minerals, phyllosilicates, wireline logs) in northern Namibia unraveled the hydrographic and hydraulic evolution of alluvial-fluvial sediments of the Kunene and Cubango megafans (Etosha-Cuvelai Basin). Three principal aquatic regimes were operative within the megafan complex: (1) the hydrographic regime, (2) the proximal hydraulic regime, (3) the distal hydraulic regime. The allogenic mineral assemblages mirror the hydrographic variation or drainage system and the lithological evolution of the fan sediments (alluvial-fluvial fan, lacustrine environment with evaporites, fan delta progradation). Authigenic heavy minerals are markers of the physical-chemical condition (Eh and pH values) of the hydraulic regime within the proximal fan at the basin margin. Authigenic heavy, light and clay minerals equally contribute to the determination of the fluid chemistry and temperature, as well as the source of chemical constituents of the former pore fluids percolating through the distal fan. Carbonatization was the most pronounced event in the distal hydraulic system and controlled by the presence of biogenic as well as atmospheric carbon. The isotope-based determination of the temperatures, albeit strongly fluctuating, do not exceed 40 °C. The overall pH values determined for the hydraulic regime within the distal fan range from slightly acidic to alkaline. The presence of zeolites attests to some short-lasting but strong deviations from the pH range, mainly towards more alkaline conditions. Heavy, light and clay mineral analyses proved to be a useful tool to determine the (paleo)hydrology of alluvial-fluvial fan systems in tropical arid to semiarid climates.

Dill, Harald G.; Kaufhold, S.; Lindenmaier, F.; Dohrmann, R.; Ludwig, R.; Botz, R.

2013-01-01

303

Chemical and Clay Mineral Properties of a Highly Weathered Soil from the Colombian Llanos Orientales. R(CO-631-42-W363).  

National Technical Information Service (NTIS)

The author presents the results of quantitative clay mineralogical investigations on a soil from the Llanos Orientales (Eastern Savannas) region of Columbia, South America and discusses some possible agronomic effects of Al-chlorite presence in highly wea...

R. M. Weaver

1972-01-01

304

Pb isotopic ratios and elemental abundances for selective leachates from near-surface till: implications for mineral exploration  

Microsoft Academic Search

Pb isotope ratios obtained from fine-grained fractions ( In this study, Pb isotopic measurements, and selective leaching of 6 near-surface till samples down-ice from the Chisel Lake (Manitoba) and Manitouwadge (Ontario) VMS deposits were carried out in order to determine the location and nature of the Pb within till. Elemental abundances from selective leachates for all 6 samples display similar

G. E. M. Hall; K. Bell

1996-01-01

305

Adsorption of Metal Ions and Metal Complexes on Clay Minerals: A Study of the Nature of Bonding by X-Ray Photoelectron Spectroscopy.  

National Technical Information Service (NTIS)

Results are reported of an investigation of the interaction of metal ions, metal ion complexes, and organic ligands with mineral and metal ion-saturated surfaces. Minerals studied include those with oxidizing and nonoxidizing surfaces (for example, lead, ...

J. G. Dillard A. B. Emerson M. H. Koppelman D. L. Crowther C. V. Schenck

1982-01-01

306

Effects of Temperature, pH and Salt Concentrations on the Adsorption of Bacillus subtilis on Soil Clay Minerals Investigated by Microcalorimetry  

Microsoft Academic Search

Adsorption of microorganisms on minerals is a ubiquitous interfacial phenomenon in soil. Knowledge of the extent and mechanisms of bacterial adsorption on minerals is of great agronomic and environmental importance. This study examined adsorption of Bacillus subtilis on three common minerals in soils such as kaolinite, montmorillonite and goethite under various environmental conditions. Isothermal titration calorimetry (ITC) was used to

Zhineng Hong; Xingmin Rong; Peng Cai; Wei Liang; Qiaoyun Huang

2011-01-01

307

Coating of silica sand with aluminosilicate clay.  

PubMed

The objective of this work was to coat aluminosilicate clays on an inert silica support, and to characterize the properties and stability of the clay-silica coating. Two polymers, polyacrylamide (PAM) and polyvinyl alcohol (PVA), were used to bind kaolinite, illite, and smectite onto silica grains. The clay-polymer composites were studied by X-ray diffraction, FTIR, and electrophoretic mobility. Clay coatings on silica grains were characterized by mass coverage, scanning electron microscopy, specific surface area, and pH stability. Silica sand was successfully coated with clays by using the two polymers, but with PVA, the clay coating had a greater mass coverage and was more stable against pH variations. Less polymer was needed for the clay coating using PVA as compared to using PAM. Clay-polymer complexes and pure clay minerals had similar cation exchange capacities and electrophoretic mobilities, indicating that overall surface charge of the clays was little affected by the polymers. Some decrease in hydrophilicity was observed for illite and smectite when clays where coated with the polymers. The methodology reported here allows the generation of a clay-based porous matrix, with hydraulic properties that can be varied by adjusting the grain size of the inert silica support. PMID:16085082

Jerez, Jorge; Flury, Markus; Shang, Jianying; Deng, Youjun

2005-08-08

308

Physical Alteration of Martian Dust Grains, Its Influence on Detection of Clays and Identification of Aqueous Processes on Mars  

Microsoft Academic Search

This study involves detailed characterization of changes in clay mineral grains resulting from grinding and assesses the influence of physical processes on clays and how to detect them on Mars. Clays may provide links to aqueous processes on Mars.

J. Bishop; A. Drief; M. D. Dyar

2003-01-01

309

Relationships between clay mineralogy, hydrothermal metamorphism, and topography in a Western Cascades watershed, Oregon, USA  

NASA Astrophysics Data System (ADS)

This study investigates variation in clay mineralogy and its relation to hydrothermal metamorphism, hillslope processes, and topography in the western Cascade Mountains. The study area is the drainage basin of Dorena Lake, a medium-sized (686 km 2) watershed located near Cottage Grove, OR. The Bohemia Mining District is on the southeastern rim of the watershed in a hydrothermally metamorphosed region associated with a set of granodiorite plutons. To characterize large-scale patterns of clay mineral distribution within the watershed, suspended sediments were collected from 43 stream locations. Samples of several metamorphosed and unaffected volcanic and volcaniclastic rocks were collected to help clarify metamorphic reaction processes. One active earthflow was also sampled. X-ray diffraction methods were used to determine the mineralogy of the clay-sized (<2 ?m) fraction of the samples. Clay mineralogy varies systematically across the watershed, and the three major stream tributaries carry sediment with distinct mineralogical signatures. Discrete minerals include kaolinite, smectite, chlorite, and illite. Interstratified kaolinite-smectite and chlorite-vermiculite (CV) are also present. The active earthflow and unmetamorphosed rock samples primarily contain smectite. In contrast, metamorphosed rock samples are composed of some combination of illite, interstratified illite-smectite, CV, and chlorite. Examination of clay mineral distribution reveals the effects of hydrothermal metamorphism in the mining district on clay mineralogy, hillslope processes, and landscape development. Compared with most of the watershed, the mining district has steeper slopes and higher elevations and lacks smectite almost entirely. Analyses of metamorphosed bedrock units indicate that smectite originally present in the rocks was converted to nonexpandable clay minerals during metamorphism. Induration of bedrock and loss of expandable clays resulted in thin soils and steep topography. Debris slides and flows are the dominant mass movement processes in this area; earthflows are noticeably absent, probably because thick, smectitic soils are lacking. Elsewhere in the watershed where smectite is abundant, slopes are more gentle; and both shallow and deep-seated mass movements are common. The clay mineralogy of bedrock and soils is thus integrally tied to the hillslope processes operating within the watershed and therefore affects the geomorphology of the landscape. High-relief, hydrothermally metamorphosed volcanic centers surrounded by weaker rocks in adjacent lowlands are common features in the western Cascade Mountains. These massifs were likely formed by differential erosion processes similar to those operating in the Dorena Lake watershed.

Ambers, Rebecca K. R.

2001-05-01

310

Ball clay  

USGS Publications Warehouse

Four companies — H.C. Spinks Clay Co., Inc., Imerys Group, Old Hickory Clay Co., and Unimin Corp. — mined ball clay in four states in 2011. Production, on the basis of preliminary data, was 940 kt (1.04 million st) with an estimated value of $44.2 million. This is a 3-percent increase in tonnage from 912 kt (1.01 million st) with a value of $41.3 million that was produced in 2010. Tennessee was the leading producing state with 63 percent of domestic production, followed by Texas, Mississippi and Kentucky. About 69 percent of production was airfloat, 20 percent was crude and 11 percent was water-slurried.

Virta, R. L.

2012-01-01

311

Mechanism of Strong Affinity of Clay Minerals to Radioactive Cesium: First-Principles Calculation Study for Adsorption of Cesium at Frayed Edge Sites in Muscovite  

NASA Astrophysics Data System (ADS)

The present first-principles study based on density-functional theory confirms that frayed edge sites (FESs) formed in micaceous clays have a crucial role in the long-term stability of radioisotopes of Cs on the topsoil surface. An FES is modeled according to the weathering scenario of muscovite, and the substitution of originally occupied K with Cs is virtually simulated. The calculation results clearly demonstrate that such a replacement is strongly promoted only when the stack structure is loosely expanded at the clay edges. This is the first atomic-scale confirmation of the strong affinity of FESs to Cs, which may shed new light on the decontamination engineering of soil materials.

Okumura, Masahiko; Nakamura, Hiroki; Machida, Masahiko

2013-03-01

312

Compositional variation in clay mineral fraction of fine and coarse-grained units in Westwater Canyon Member (Morrison Formation, San Juan basin, New Mexico)  

Microsoft Academic Search

Smectites and mixed-layer illite\\/smectite clays from a suite of core samples drawn from the Westwater Canyon Member of the Morrison Formation (USGS borehole S6) have been examined using analytical electron microscopy (AEM) and x-ray diffraction. Samples from 784 and 808 m deep are fine and coarse-grained, respectively. An intermediate sample (806-m depth) is a sandy siltstone with conspicuous shale intraclasts.

P. O. Eberly; L. J. Crossey

1989-01-01

313

Minerals in our Environment  

NSDL National Science Digital Library

This downloadable poster (36 in. by 60 in.) describes how minerals are used in household substances and objects, listed by name, with numbers corresponding to locations in a typical house. For example, in the kitchen, appliances contain steel and copper, clay minerals are found in china, and table salt contains the mineral halite.

314

Methylene Blue Adsorption on Natural and Modified Clays  

Microsoft Academic Search

Toxic methylene blue dye is removed from water by accumulating them on the surface of clay minerals. Clay adsorbents are obtained from kaolinite, montmorillonite and their acid activated forms. The adsorption experiments are carried out in a batch process in environments of different pH, initial dye concentration, amount of clay, interaction time and temperature. Adsorption of dye is best described

Gautam Kumar Sarma; Susmita SenGupta; Krishna G. Bhattacharyya

2011-01-01

315

Constraints on Mineral-Phase Abundances and Compositions in the Low-Albedo Northern Plains of Mars using MGS-TES, OMEGA, and Laboratory Spectral Data.  

NASA Astrophysics Data System (ADS)

The abundances and compositions of mineral-phases in the low-albedo northern plains of Mars have been a focus of considerable study and debate in recent years. Large expanses of Acidalia Planitia surface materials are characterized by the MGS-TES Surface Type 2 (ST2) spectral endmember [1]. The ST2 spectrum is distinguished by a rounded, slightly V-shaped 800 to 1200 wavenumber region of absorption and uniform absorption at low wavenumbers. The same areas are also characterized by an OMEGA spectral signature that is relatively featureless, but with a strong blue slope (decreasing reflectance as a function of wavelength) from 0.9 to 2.6 microns [2]. A central question with both observations is whether they represent the spectral signature of a high-silica primary volcanic lithology (andesite) or the effects of chemical alteration on basaltic surface materials. Ambiguity in classifying the ST2 lithology arises because a spectral component of this unit (20-30 vol %) can be interpreted as volcanic siliceous glass [1, 3] (an abundant phase in andesite) or a combination of secondary phases found in altered basalt (amorphous silica-rich coatings, palagonite, smectite, and zeolite) [4-8]. Similarly, the OMEGA spectrum lacks evidence of distinct mafic mineral bands (found in andesite) as well as molecular vibration absorptions due to H2O and/or OH-, which might indicate the presence of well- crystalline alteration products and phyllosilicates [2]. Constraining these compositions is significant for understanding the petrogenesis of the Martian crust and its subsequent alteration. Identification of widespread andesite may imply an early episode of plate tectonics on Mars while altered basalt would indicate extensive surface-volatile interactions. The objective of this study is to combine TES and OMEGA observations of the low-albedo northern plains for comparison to laboratory thermal infrared and visible/near-infrared measurements of primary volcanic lithologies (basalt to dacite) and chemically weathered basalts from different terrestrial environments. Thermal infrared emission and visible/near-infrared reflectance measurements will be performed on rock chips, sorted particle sizes, and soil samples. Emission spectra have been acquired at Arizona State University using a Nicolet Nexus 670 FTIR spectrometer that has been modified to measure emitted energy over the range of 5 to 50 microns at 2 wavenumber spectral sampling. Bidirectional reflectance measurements from 0.32 to 2.55 microns at 0.05 micron sampling will be collected at the Brown University RELAB facility. Work by [5] on palagonitic alteration rinds developed on basaltic rocks demonstrates the effectiveness of combining wavelength regions in laboratory studies and applying results to orbital observations. In our study, we further this type of work by examining both unaltered volcanics and chemically altered basalts in an effort to constrain interpretations of the igneous lithology and the degree of secondary mineral-phase production in Acidalia Planitia. [1] Bandfield et al. (2000) Science, 287, 1626 1630. [2] Mustard et al. (2005) Science, 1594-1597. [3] Hamilton et al. (2001) JGR, 106, 14,733-14,746. [4] Wyatt and McSween (2002) Nature, 417, 263-266. [5] Morris et al. (2003) 6 Int. Mars. Conf, Abstract 3111. [6] Kraft et al. (2003) GRL, 30, 24, 2288, doi 10.1029.2003GL018848. [7] Ruff (2004) Icarus, 108, 131-143. [8] Michalski et al. (2005) Icarus, 174, 161-177.

Wyatt, M. B.; Mustard, J. F.

2006-12-01

316

Chemical reactions of organic compounds on clay surfaces  

SciTech Connect

Chemical reactions of organic compounds including pesticides at the interlayer and exterior surfaces of clay minerals and with soil organic matter are reviewed. Representative reactions under moderate conditions possibly occurring in natural soils are described. Attempts have been made to clarify the importance of the chemical nature of molecules, their structures and their functional groups, and the Broensted or Lewis acidity of clay minerals.

Soma, Yuko; Soma, Mitsuyuki (National Institute for Environmental Studies, Ibaraki (Japan))

1989-11-01

317

Clay Mineralogy of Pennsylvanian Sediments in Southern Illinois1  

Microsoft Academic Search

Controversy over the origin of clay minerals in ancient sediments arises because it is difficult to segregate the factors that cause differences in clay mineral composition. A plan of sampling based on four contrasts was used to evaluate some of these factors. Contrasts studied were: (1) permeability contrasts (sandstone vs. shales); (2) environmental con- trasts (cyclic sedimentation); (3) weathering contrasts

Herbert D. Glass

1956-01-01

318

Chemical reactions of organic compounds on clay surfaces.  

PubMed Central

Chemical reactions of organic compounds including pesticides at the interlayer and exterior surfaces of clay minerals and with soil organic matter are reviewed. Representative reactions under moderate conditions possibly occurring in natural soils are described. Attempts have been made to clarify the importance of the chemical nature of molecules, their structures and their functional groups, and the Brönsted or Lewis acidity of clay minerals.

Soma, Y; Soma, M

1989-01-01

319

REMOVAL OF PESTICIDES FROM WATER BY BIOMOLECULE-EXCHANGED CLAYS  

Technology Transfer Automated Retrieval System (TEKTRAN)

Replacement of natural inorganic cations of clay minerals with organic cations through ion exchange reactions has been proposed as an strategy to improve the adsorptive capacity of clay minerals for organic compounds, including pesticides. The organic cations most commonly used for this purpose have...

320

Clay for Little Fingers.  

ERIC Educational Resources Information Center

Discusses the renewed interest in clay as a modeling compound in early childhood programs; describes the nature of clay and presents a working vocabulary. Suggests methods of working with clay, including introducing clay to children, discovering its uses, clean up, firing clay, and finishing baked clay. Includes activity suggestions and…

Koster, Joan Bouza

1999-01-01

321

Evaluation of Phosphatic Clay Disposal and Reclamation Methods. Volume 2. Mineralogy of Phosphatic Clays.  

National Technical Information Service (NTIS)

Twelve phosphatic clays and three sand tailings from Florida phosphate mining areas were examined by X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and chemical analysis. Quantitative estimates of mineral species were made using sample XRD da...

A. E. Z. Wissa N. F. Fuleihan T. S. Ingra

1982-01-01

322

Chemo–mechanical interactions in clay: a correlation between clay mineralogy and Atterberg limits  

Microsoft Academic Search

Among some few others tests, the evaluation of the Atterberg limits is a very basic soil mechanical test allowing a first insight into the chemical reactivity of clays. Basically, the liquid limit and the plasticity index are highly and mainly influenced by the ability of clay minerals to interact with liquids. In this contribution, a correlation between the Atterberg limits

Robrecht M Schmitz; Christian Schroeder; Robert Charlier

2004-01-01

323

Soil clay content underlies prion infection odds  

PubMed Central

Environmental factors—especially soil properties—have been suggested as potentially important in the transmission of infectious prion diseases. Because binding to montmorillonite (an aluminosilicate clay mineral) or clay-enriched soils had been shown to enhance experimental prion transmissibility, we hypothesized that prion transmission among mule deer might also be enhanced in ranges with relatively high soil clay content. In this study, we report apparent influences of soil clay content on the odds of prion infection in free-ranging deer. Analysis of data from prion-infected deer herds in northern Colorado, USA, revealed that a 1% increase in the clay-sized particle content in soils within the approximate home range of an individual deer increased its odds of infection by up to 8.9%. Our findings suggest that soil clay content and related environmental properties deserve greater attention in assessing risks of prion disease outbreaks and prospects for their control in both natural and production settings.

David Walter, W.; Walsh, Daniel P.; Farnsworth, Matthew L.; Winkelman, Dana L.; Miller, Michael W.

2011-01-01

324

The role of reaction affinity and secondary minerals in regulating chemical weathering rates at the Santa Cruz Soil Chronosequence, California  

SciTech Connect

In order to explore the reasons for the apparent discrepancy between laboratory and field weathering rates and to determine the extent to which weathering rates are controlled by the approach to thermodynamic equilibrium, secondary mineral precipitation and flow rates, a multicomponent reactive transport model (CrunchFlow) was used to interpret soil profile development and mineral precipitation and dissolution rates at the 226 ka marine terrace chronosequence near Santa Cruz, CA. Aqueous compositions, fluid chemistry, transport, and mineral abundances are well characterized (White et al., 2008, GCA) and were used to constrain the reaction rates for the weathering and precipitating minerals in the reactive transport modeling. When primary mineral weathering rates are calculated with either of two experimentally determined rate constants, the nonlinear, parallel rate law formulation of Hellmann and Tisser and [2006] or the aluminum inhibition model proposed by Oelkers et al. [1994], modeling results are consistent with field-scale observations when independently constrained clay precipitation rates are accounted for. Experimental and field rates, therefore, can be reconciled at the Santa Cruz site. Observed maximum clay abundances in the argillic horizons occur at the depth and time where the reaction fronts of the primary minerals overlap. The modeling indicates that the argillic horizon at Santa Cruz can be explained almost entirely by weathering of primary minerals and in situ clay precipitation accompanied by undersaturation of kaolinite at the top of the profile. The rate constant for kaolinite precipitation was also determined based on model simulations of mineral abundances and dissolved Al, SiO{sub 2}(aq) and pH in pore waters. Changes in the rate of kaolinite precipitation or the flow rate do not affect the gradient of the primary mineral weathering profiles, but instead control the rate of propagation of the primary mineral weathering fronts and thus total mass removed from the weathering profile. Our analysis suggests that secondary clay precipitation is as important as aqueous transport in governing the amount of dissolution that occurs within a profile because clay minerals exert a strong control over the reaction affinity of the dissolving primary minerals. The modeling also indicates that the weathering advance rate and the total mass of mineral dissolved is controlled by the thermodynamic saturation of the primary dissolving phases plagioclase and K-feldspar, as is evident from the difference in propagation rates of the reaction fronts for the two minerals despite their very similar kinetic rate laws.

Maher, K.; Steefel, C. I.; White, A.F.; Stonestrom, D.A.

2009-02-25

325

Characterizing regional soil mineral composition using spectroscopyand geostatistics  

USGS Publications Warehouse

This work aims at improving the mapping of major mineral variability at regional scale using scale-dependent spatial variability observed in remote sensing data. Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) data and statistical methods were combined with laboratory-based mineral characterization of field samples to create maps of the distributions of clay, mica and carbonate minerals and their abundances. The Material Identification and Characterization Algorithm (MICA) was used to identify the spectrally-dominant minerals in field samples; these results were combined with ASTER data using multinomial logistic regression to map mineral distributions. X-ray diffraction (XRD)was used to quantify mineral composition in field samples. XRD results were combined with ASTER data using multiple linear regression to map mineral abundances. We testedwhether smoothing of the ASTER data to match the scale of variability of the target sample would improve model correlations. Smoothing was donewith Fixed Rank Kriging (FRK) to represent the mediumand long-range spatial variability in the ASTER data. Stronger correlations resulted using the smoothed data compared to results obtained with the original data. Highest model accuracies came from using both medium and long-range scaled ASTER data as input to the statistical models. High correlation coefficients were obtained for the abundances of calcite and mica (R2 = 0.71 and 0.70, respectively). Moderately-high correlation coefficients were found for smectite and kaolinite (R2 = 0.57 and 0.45, respectively). Maps of mineral distributions, obtained by relating ASTER data to MICA analysis of field samples, were found to characterize major soil mineral variability (overall accuracies for mica, smectite and kaolinite were 76%, 89% and 86% respectively). The results of this study suggest that the distributions of minerals and their abundances derived using FRK-smoothed ASTER data more closely match the spatial variability of soil and environmental properties at regional scale.

Mulder, V.L.; de Bruin, S.; Weyermann, J.; Kokaly, Raymond F.; Schaepman, M.E.

2013-01-01

326

Modelling of the physico-chemical behaviour of clay minerals with a thermo-kinetic model taking into account particles morphology in compacted material  

Microsoft Academic Search

Modelling of fluid-mineral interactions is largely used in Earth Sciences studies to better understand the involved physicochemical processes and their long-term effect on the materials behaviour. Numerical models simplify the processes but try to preserve their main characteristics. Therefore the modelling results strongly depend on the data quality describing initial physicochemical conditions for rock materials, fluids and gases, and on

D. Sali; B. Fritz; C. Clément; N. Michau

2003-01-01

327

Sedimentary and Related Minerals  

NSDL National Science Digital Library

In this three-part exercise, students study hand samples and thin sections of sedimentary minerals and rocks. Part one - Box of Rocks: Students examine a tray of Halides, Carbonates, Borates, and Clays and record their physical properties, composition, habit, and occurence. They note chemical and physical similarities and differences of the minerals. Part two - Definitions: Define a list of terms relevent to the lab. Part three - Minerals in Thin Section: Observe sedimentary minerals in thin section and answer questions about them.

Perkins, Dexter

328

Desorption of arsenic from clay and humic acid-coated clay by dissolved phosphate and silicate  

NASA Astrophysics Data System (ADS)

Arsenic (As) contaminated aquifers contain iron minerals and clays that strongly bind As at their surfaces. It was suggested that As mobilization is driven by natural organic matter (including fulvic acids (FA) and humic acids (HA)) present in the aquifers either via providing reducing equivalents for reductive dissolution of Fe(III) (hydr)oxides or via competitive desorption of As from the mineral surfaces. In the present study we quantified sorption of As(III) and As(V) to Ca2+-homoionized illite (IL) and to kaolinite (Kao) as well as to HA-coated clays, i.e., illite-HA (IL-HA) and kaolinite-HA (Kao-HA) at neutral pH. Clay-HA complexes sorbed 28-50% more As than clay-only systems upon addition of 100 ?M As(III)/As(V) to 0.5 g of clay or HA-clay with Ca2+ probably playing an important role for HA binding to the clay surface and As binding to the HA. When comparing sorption of As(V) and As(III) to clay and HA-clay complexes, As(V) sorption was generally higher by 15-32% than sorption of As(III) to the same complexes. IL and IL-HA sorbed 11-28% and 6-11% more As compared to Kao and Kao-HA, respectively. In a second step, we then followed desorption of As from Kao, Kao-HA, IL and IL-HA by 100 and 500 ?M phosphate or silicate both at high (0.41-0.77 ?mol As/g clay), and low (0.04 to 0.05 ?mol As/g clay) As loadings. Phosphate desorbed As to a larger extent than silicate regardless of the amount of As loaded to clay minerals, both in the presence and absence of HA, and both for illite and kaolinite. At high loadings of As, the desorption of both redox species of As from clay-HA complexes by phosphate/silicate ranged from 32 to 72% compared to 2-54% in clay only systems meaning that As was desorbed to a larger extent from HA-coated clays compared to clay only systems. When comparing As(III) desorption by phosphate/silicate to As(V) desorption in high As-loading systems, there was no clear trend for which As species is desorbed to a higher extent in the four clay systems meaning that both As species behave similarly regarding desorption from clay surfaces by phosphate/silicate. Similarly, no significant differences were found in high As-loading systems in the amount of As desorbed by phosphate/silicate when comparing Kao vs. IL and Kao-HA vs IL-HA systems meaning that both clay types behave similarly regarding desorption of As by phosphate/silicate. At low As loadings, up to 80% of As was desorbed by phosphate and silicate with no noticeable differences being observed between different As species, different types of clay, clay vs clay-HA or the type of desorbant (phosphate and silicate). The results of this study showed that HA sorption to Ca2+-homoionized clay minerals can increase As binding to the clay although the As sorbed to the clay-HA is also released to a greater extent by competing ions such as phosphate and silicate. Desorption of As depended on the initial loadings of As onto the clay/clay-HA. Based on our results, the effect of humic substances on sorption of As and on desorption of As by phosphate and silicate has to be considered in order to fully understand and evaluate the environmental behavior of As in natural environments.

Sharma, Prasesh; Kappler, Andreas

2011-11-01

329

Coupled infrared extinction spectra and size distribution measurements for several non-clay components of mineral dust aerosol (quartz, calcite, and dolomite)  

Microsoft Academic Search

Simultaneous size distributions and Fourier transform infrared (FTIR) extinction spectra have been measured for several representative components of mineral dust aerosol (quartz, calcite, and dolomite) in the fine particle size mode (D=0.1–1?m). Optical constants drawn from the published literature have been used in combination with the experimentally determined size distributions to simulate the extinction spectra. In general, Mie theory does

Paula K. Hudson; Mark A. Young; Paul D. Kleiber; Vicki H. Grassian

2008-01-01

330

Clay mineral analysis of the Hirabayashi NIED drill core on the Nojima fault that ruptured in the 1995 Kobe Earthquake, southwest Japan  

Microsoft Academic Search

A 1800-m-deep borehole was drilled at Nojima Hirabayashi and penetrated the Nojima fault that was activated at the time of the 1995 Hyogo-ken Nanbu Earthquake (Kobe Earthquake) in Japan. Three possible fracture zones were detected at depths of about 1140 m, 1300 m, and 1800 m. At first, we analyzed the mode of distribution of rocks, minerals and chemical elements

T. Matsuda; K. Omura; R. Ikeda; D. Awaji

2002-01-01

331

How clays affect fault strength and slip behavior: Lessons from SAFOD  

NASA Astrophysics Data System (ADS)

The strength and slip behavior of upper crustal faults has been attributed to (i) values of normal stress, (ii) pore-fluid pressure, and (iii) frictional properties. Direct observations on natural fault rocks provide compelling evidence for the role of localized neomineralization, as demonstrated by our work on samples from the San Andreas Fault Observatory at Depth (SAFOD) drillhole at Parkfield, California. Mudrock samples from fault zones at ~3066 m and ~3296 m measured depth (MD) show variably spaced and interconnected networks of displacement surfaces that consist of host rock particles that are abundantly coated by polished films with occasional striations. Transmission electron microscopy and X-ray diffraction study of the surfaces reveal the occurrence of neocrystallized thin-film clay coatings containing illite-smectite (I-S) and chlorite-smectite (C-S) phases. X-ray texture goniometry shows that the clay crystallographic fabric of these faults rocks is characteristically low, in spite of an abundance of clay phases. 40Ar/39Ar dating of the illitic coatings demonstrate recent crystallization and reveals the initiation of an “older” fault strand (~8 Ma) at 3066 m MD, and a “younger” fault strand (~4 Ma) at 3296 m MD. Today, the younger strand is the site of active creep behavior, reflecting continued activation of clay-weakened zones. We propose that fault creep is controlled by the localization of thin (< 100nm thick) nanocoatings on fracture surfaces that are sufficiently smectite-rich and interconnected to allow slip with minimal breakage of stronger matrix clasts. Displacements are accommodated by frictional slip along coated particle surfaces, in combination with intracrystalline deformation of the mineral lattice, resulting from crystal dissolution, mass transfer and growth of expandable clays. The highly localized concentration of both I-S and C-S minerals does not require volumetrically large mass transfer. A scenario is proposed where initial cataclasis (seismic behavior) and associated fluid infiltration create nucleation sites for neomineralization on displacement surfaces, which eventually creates a sufficiently connected framework that dominates subsequent fault slip behavior (creep). The role of newly grown, ultrathin, hydrous clay coatings on displacement surfaces in the San Andreas Fault emphasizes the importance of clay neomineralization in fault zones and contrasts with scenarios of reworked talc/serpentine phases as an explanation for weak faults and creep behavior at these depths. The occurrence of C-S phases to temperatures above the stability of I-S indicates that smectitic clay phases can affect fault behavior to depths well below the SAFOD borehole penetration, possibly to the base of the brittle zone.

van der Pluijm, B. A.; Schleicher, A. M.; Warr, L.

2010-12-01

332

INFLUENCE OF AQUEOUS IONIC STRENGTH ON PESTICIDE SORPTION BY SMECTITE CLAY  

Technology Transfer Automated Retrieval System (TEKTRAN)

Our recent studies indicated that many agrochemicals demonstrated a great affinity with smectite clays. Exchangeable cations associated with clay minerals significantly influence pesticide sorption by controlling interlayer distance, the size of sorptive domains, and the ability of sorbate functiona...

333

Magnetic theoretical and experimental study of clays for petroleum reservoir clay typing  

NASA Astrophysics Data System (ADS)

This study describes theoretical and experimental magnetic analysis of different clay types for petroleum reservoir characterisation by using low and high field magnetic susceptibility. Most clays for example, saponite, clay loam and bentonite are paramagnetic, whereas some clays (kaolinite) and matrix minerals such as quartz and calcite are diamagnetic. Model magnetic susceptibility and magnetic hysteresis plots for various concentrations of different clays in quartz matrix were initially calculated. Experimental magnetic measurements were undertaken for comparison on a series of synthetic reservoir samples comprising various concentrations of dispersed clays in a quartz matrix. The experimental magnetic measurements showed substantial agreement with the model magnetic values, and with estimates of the magnetic susceptibility based on low and high field magnetic susceptibility for derived mineral contents. Importantly different magnetic parameters, including IRM (isothermal remnant magnetisation) were determined for the different clay types and their mixtures with the sandstone rock matrix, together with given permeability variations in the samples. Results demonstrate that these magnetic measurements potentially provide a sensitive, rapid, quantitative technique which can be used for petrophysical analysis of clay-rich rocks and clay typing.

Ivakhnenko, Aleksandr; Makarova, Maria; Telman, Meruert

2013-04-01

334

Diagenesis and fluid flow in the San Juan Basin, New Mexico - regional zonation in the mineralogy and stable isotope composition of clay minerals in sandstone.  

USGS Publications Warehouse

The Westwater Canyon Member of the Upper Jurassic Morrison Formation is a relatively homogeneous, hydrologically continuous 100-m-thick sequence of massive fluvial sandstone, bounded above and below by relatively heterogeneous, hydrologically discontinuous units and has served as a primary conduit for fluids within this stratigraphic interval. Patterns of mineral-fluid reactions suggest a basinwide hydrologic regime in which warm, evolved fluids migrated up-dip from the center of the basin under the influence of a regional hydraulic head. -from Authors

Whitney, G.; Northrop; H. R.

1987-01-01

335

Mineral Composition and Abundance of the Rocks and Soils at Gusev and Meridiani from the Mars Exploration Rover Mini-TES Instruments  

NASA Astrophysics Data System (ADS)

The miniature Thermal Emission Spectrometer (Mini-TES) has provided remote measurements of the mineralogy and thermophysical properties of outcrops, rocks, spherules, and soils surrounding the Spirit and Opportunity Rovers [1, 2]. The composition of surface materials provides insight into the origin and evolution of the martian crust and the nature of igneous and sedimentary processes. At Gusev, undisturbed soil spectra closely match MGS TES bright-regions dust spectra, with features interpreted to be due to minor carbonates and bound water. Dark-toned soils observed on rover-disturbed surfaces are likely derived from rocks and have a derived mineralogy, with uncertainties of 5-10 vol.%, of 45% pyroxene (20% high-Ca pyroxene, 25% pigeonite), 40% sodic/intermediate plagioclase, and 15% olivine (Fo35-Fo55). Aeolian drift material has a unique spectral character with higher oxide abundances than disturbed soil. Along the rover's traverse from the lander into the Columbia Hills, at least three distinct rock types have been recognized: olivine rich basalt, a volcaniclastic rock dominated by an amorphous component (possibly basaltic glass and/or shocked plagioclase), and a second volcaniclastic rock dominated by plagioclase of intermediate composition with lesser pyroxene and olivine components. One (or possibly two) spectrally distinct coatings are observed on rocks, a possible indicator of the interaction of water, rock, and airfall dust. At Meridiani, the Mini-TES has identified coarse crystalline hematite and olivine basaltic sands as predicted from orbital TES spectroscopy [3, 4]. Basaltic materials have more plagioclase than pyroxene, contain olivine, and are similar in inferred mineral composition to basalt mapped by TES from orbit. Light-toned outcrops of aqueous origin exposed in crater walls are composed of 20 to 40% Mg and Ca sulfates, a high-silica component that is modeled as glass/feldspar/sheet silicates (~20-30%), and hematite. The Fe-bearing sulfate, jarosite, that was identified by the Mossbauer spectrometer [5], is detected in deconvolutions of several Mini-TES outcrop spectra, but never in concentrations >5%. The dominance of Mg and Ca sulfates in Mini-TES spectra is consistent with the Alpha Particle X-ray Spectrometer (APXS) results, which show that Mg and Ca are present, and that there is significantly more S and too little Fe for the sulfates to be jarosite alone [6]. Two unique surface rocks have been identified during the rover's traverse. Bounce Rock is dominated by clinopyroxene relative to basaltic sands and is closer in inferred mineral composition to the basaltic SNC meteorites. Heat-Shield Rock has a Mini-TES spectral signature that closely resembles a typical spectrum of the sky. The initial Mini-TES interpretation that Heat-Shield Rock was a metallic object with a near reflective surface, and possibly an iron bearing meteorite, was confirmed by APXS and MB observations. The occurrence of waterlain rocks covered by olivine, pyroxene, and feldspar in basaltic sands suggests a significant change from an aqueous environment at the time the rocks were deposited to one dominated by physical weathering. 1)Christensen, P.R., et al., Science, 2004. 305: p. 837-842. 2)Christensen, P.R., et al., Science, 2004. 306: p. 1733-1739. 3)Christensen, P.R., et al., J. Geophys. Res., 2000. 105: p. 9623-9642. 4)Christensen, P.R., et al., J. Geophys. Res., 2001. 106: p. 23873-23885. 5)Klingelhofer, G., et al., Science, 2004. 306: p. 1740-1745. 6)Rieder, R., et al., Science, 2004. 306: p. 1746-1749.

Christensen, P. R.

2005-05-01

336

Ural clays for building brick production  

Microsoft Academic Search

The chemical-mineral composition and technological properties of two varieties of low-melting clays used in production of\\u000a building brick are investigated. It is found that based on the blend of these types of clay and using metallurgical slag as\\u000a an additive, it is possible to obtain a ceramic mixture with minimum drying sensitivity and mechanical strength after firing\\u000a at a temperature

A. A. Mikhailova; A. V. Ivanova; E. G. Vovkotrub; V. Yu. Gorodnyanskaya

1998-01-01

337

A granulometry and secondary mineral fingerprint of chemical weathering in periglacial landscapes and its application to blockfield origins  

NASA Astrophysics Data System (ADS)

A review of published literature was undertaken to determine if there was a fingerprint of chemical weathering in regoliths subjected to periglacial conditions during their formation. If present, this fingerprint would be applied to the question of when blockfields in periglacial landscapes were initiated. These blocky diamicts are usually considered to represent remnants of regoliths that were chemically weathered under a warm, Neogene climate and therefore indicate surfaces that have undergone only a few metres to a few 10s of metres of erosion during the Quaternary. Based on a comparison of clay and silt abundances and secondary mineral assemblages from blockfields, other regoliths in periglacial settings, and regoliths from non-periglacial settings, a fingerprint of chemical weathering in periglacial landscapes was identified. A mobile regolith origin under, at least seasonal, periglacial conditions is indicated where clay(%) ? 0.5*silt(%) + 8 across a sample batch. This contrasts with a mobile regolith origin under non-periglacial conditions, which is indicated where clay(%) ? 0.5*silt(%) ? 6 across a sample batch with clay(%) ? 0.5*silt(%) + 8 in at least one sample. A range of secondary minerals, which frequently includes interstratified minerals and indicates high local variability in leaching conditions, is also commonly present in regoliths exposed to periglacial conditions during their formation. Clay/silt ratios display a threshold response to temperature, related to the freezing point of water, but there is little response to precipitation or regolith residence time. Lithology controls clay and silt abundances, which increase from felsic, through intermediate, to mafic compositions, but does not control clay/silt ratios. Use of a sedigraph or Coulter Counter to determine regolith granulometry systematically indicates lower clay abundances and intra-site variability than use of a pipette or hydrometer. In contrast to clay/silt ratios, secondary mineral assemblages vary according to regolith residence time, temperature, and/or precipitation. A microsystems model is invoked as a conceptual framework in which to interpret the concurrent formation of the observed secondary mineral ranges. According to the fingerprint of chemical weathering in periglacial landscapes, there is generally no evidence of blockfield origins under warm Neogene climates. Nearly all blockfields appear to be a product of Quaternary physical and chemical weathering. A more dominant role for periglacial processes in further bevelling elevated, low relief, non-glacial surface remnants in otherwise glacially eroded landscapes is therefore indicated.

Goodfellow, Bradley W.

2012-12-01

338

A possible energetic role of mineral surfaces in chemical evolution  

NASA Astrophysics Data System (ADS)

The postulated roles of clays and other minerals in chemical evolution and the origin of life are reconsidered in terms of the interaction of these minerals with penetrating sources of energy such as ionizing radiation and mechanical stress. This interaction, including such facets as excitation, degradation, storage, and transfer, is considered here with regard to its profound potential for altering the capabilities of minerals to serve both as substrates for prebiological chemistry and as inorganic prototypic life forms. The interaction of minerals and energy in relationship to surface chemistry is discussed in terms of the spectroscopic properties of minerals, the interaction of energy with condensed phases, some commonly accepted concepts of heterogeneous catalysis in the absence of electronic energy inputs, and some commonly accepted and novel means by which surface activity might be enhanced in the presence of energy inputs. An estimation is made of the potential contribution of two poorly characterized prebiotic energy sources, natural radioactive decay and triboelectric energy. These estimates place a conservative lower limit on their prebiotic abundance. Also some special properties of these energy sources, relative to solar energy, are pointed out which might give them particular suitability for driving reactions occurring under geological conditions. Skeletal support for this broadly defined framework of demonstrated and potential relationships between minerals, electronic excitation, and surface reactivity, as applied to chemical evolution, is provided from the results of our studies on 1/1 clays. We have discovered and partially characterized a number of novel luminescent properties of these clays, that indicate energy storage and transfer processes in clays. These luminescent properties are interpreted in relationship to the electron spin resonance phenomena, to provide a basis for estimating the potential significance of energy storage and transduction in monitoring or driving clay surface chemistry. Consideration of the electronic structure of abundant minerals in terms of band theory and localized defect centers provides a predictive theoretical framework from which to rationalize the capacity of these materials to store and transduce energy. The bulk crystal is seen as a collecting antenna for electronic energy, with the defect centers serving as storage sites. The clay properties produced by isomorphic substitution appear to be intimately associated with all of the life-mimetic chemical processes that have been attributed to clays. It appears sensible to postulate that the energetic properties of these substitutional defect centers may also be influential in these biomimetic processes: the promotion of surface reactions, storage of information, replication with transfer of information, and asymmetric separation of electrical charges, as well as their more recently hypothesized roles in energy storage and transduction. The identity of the sites implicated in all of the biomimetic functions of clays as well as their capacity for energy storage is seen to offer significant potential for coupling these functions to an environmental energy source. A yet more specific and experimentally testable hypothesis is offered for a new biomimetic process performed by clays. This hypothesis is that energy stored near isomorphically substituted sites provides the energetic basis for the coupled transport of electrical charge and/or electronic energy through the clay layer, which operates via environmental activation of electron/hole mobility. This is to say that mobility of charge/electronic excitation between defect centers serves as the basis for a primordial inorganic electron transport chain.

Coyne, Lelia M.

1985-09-01

339

CLAY AND CLAY-SUPPORTED REAGENTS IN ORGANIC SYNTHESES  

EPA Science Inventory

CLAY AND CLAY-SUPPORTED REAGENTS HAVE BEEN USED EXTENSIVELY FOR SYNTHETIC ORGANIC TRANSFORMATIONS. THIS OVERVIEW DESCRIBES THE SALIENT STRUCTURAL PROPERTIES OF VARIOUS CLAY MATERIALS AND EXTENDS THE DISCUSSION TO PILLARED CLAYS AND REAGENTS SUPPORTED ON CLAY MATERIALS. A VARIET...

340

Low-temperature, mineral-catalyzed air oxidation: a possible new pathway for PAH stabilization in sediments and soils.  

PubMed

Reactivity of polycyclic aromatic hydrocarbons (PAHs) in the subsurface is of importance to environmental assessment, as they constitute a highly toxic hazard. Understanding their reactivity in the long term in natural recovering systems is thus a key issue. This article describes an experimental investigation on the air oxidation of fluoranthene (a PAH abundant in natural systems polluted by industrial coal use) at 100°C on different mineral substrates commonly found in soils and sediments (quartz sand, limestone, and clay). Results demonstrate that fluoranthene is readily oxidized in the presence of limestone and clay, leading to the formation of high molecular weight compounds and a carbonaceous residue as end product especially for clay experiments. As demonstrated elsewhere, the experimental conditions used permitted the reproduction of the geochemical pathway of organic matter observed under natural conditions. It is therefore suggested that low-temperature, mineral-catalyzed air oxidation is a mechanism relevant to the stabilization of PAHs in sediments and soils. PMID:20964431

Ghislain, Thierry; Faure, Pierre; Biache, Coralie; Michels, Raymond

2010-10-22

341

Uranium in clays of crystalline rocks  

SciTech Connect

Uraniferous clay aggregates in several granites have been examined in detail with a scanning electron microscope (SEM) equipped with a high resolution backscattered electron detector (BSE) and an energy dispersive x-ray system (EDS). The same polished sections used for the microscope observations were irradiated with thermal neutrons and the etched lexan detectors were then used to determine the location of uranium with a spatial resolution of a few microns. A set of 100 samples of the following granites were used for this study: Carnmenellis granite of southwestern England, Conway and Mount Osceola granites of central New Hampshire, Sherman granite of Wyoming and Colorado, Granite Mountains granite of Wyoming, several granites from central Maine, and the Graniteville granite of Missouri. These samples contain clay rich regions as large as a few millimeters that appear to consist entirely of clay when examined with the petrographic microscope. The clays are smectite, nontronite, or vermiculite. The fission track detectors show uranium to be present within the regions. Close examination with the BSE and EDS, however, shows in every instance that the host for the uranium is not clay but clay-sized grains of the following minerals: bastnesite group, hematite, siderite, secondary monazite, secondary thorite, and several different Y-bearing niobates. This finding may have severe implications for the long-term retention of uranium and transuranic elements adsorbed on clay. Perhaps the presence of clay is not significant for the long-term retention of radioisotopes. 22 refs., 7 figs.

Simmons, G.; Caruso, L.

1985-03-10

342

Experimental determination of scattering matrices of randomly oriented fly ash and clay particles at 442 and 633 nm  

Microsoft Academic Search

We present measurements of the scattering angle distribution of the whole scattering matrix for randomly oriented particles of three mineral samples: fly ash, green clay, and red clay at 442 and 633 nm. Fly ash consists of aggregates of nearly spherical particles while green clay and red clay particles represent irregular compact particles. We compare the measured results for fly

O. Muñoz; H. Volten; J. F. de Haan; W. Vassen; J. W. Hovenier

2001-01-01

343

Alterations in the non-clay-mineral fraction of pelitic rocks the diagenetic to low-grade metamorphic transition, Ouachita Mountains, Oklahoma and Arkansas  

SciTech Connect

The transformation of smectite to illite has been cited by many authors as a source of silica during diagenesis of mudrocks. Illites themselves, however, undergo chemical changes as they recrystallize into micas during high-grade diagenesis/low-grade metamorphism. Average compositions of phyllosilicates from the literature suggest that an equivalent amount of silica is available from transformation of illite to muscovite as from illitization of smectites. The fate of silica released by this process has not been reported, but could be a major contributor to the silt-size quartz population. The quartz and feldspar fraction of pelites from the Stanley Shale (Mississippian) in the Ouachita Mountains of Oklahoma and Arkansas was separated using sodium bisulfate fusions. The mineralogy and the grain-size distribution of this fraction were determined using standard petro-graphic and X-ray diffraction (XRD) techniques. Bulk rock samples were analyzed using X-ray fluorescence (XRF) and instrumental neutron activation analysis (INAA) methods. The data obtained were related to illite crystallinity and vitrinite reflectance as reported by Guthrie el al. (1986) and Houseknecht and Matthews (1985). The authors results are consistent with reported differences between quartz in schists and their shale precursors, and suggest that release of silica during diagenesis of phyllosilicates continues after the smectite-illite transformation. This silica precipitates as quartz within the pelite, consistent with the suggestion by Blatt (1987) that metapelites are the source of abundant silt-size quartz. The lack of whole-rock chemical variation with thermal maturity implies closed-system behavior across much of the pelite-to-metapelite transition.

Totten, M.W.; Blatt, H. (Univ. of Oklahoma, Norman, OK (United States). School of Geology and Geophysics)

1993-09-01

344

Water Remediation by Adsorption of Phenol onto Hydrophobic Modified Clay  

Microsoft Academic Search

In this work we studied the phenol sorption from contaminated water onto modified clay mineral vermiculite and bentonite by\\u000a insertion of hexadecyltrimethylammonium in the interlayer of clays. The non modified clays showed negligible interaction with\\u000a phenol. The experimental data were treated using the Freunlich equation which had a good fit. The removal percentages were\\u000a higher than 35% for modified vermiculite

Sandro Froehner; Raquel Fernandes Martins; Willian Furukawa; Marcelo Risso Errera

2009-01-01

345

Clay Water Interactions. An Experimental Study of Interface Phenomena.  

National Technical Information Service (NTIS)

The structural properties of water adsorbed on hydrophilic intercrystalline clay mineral surfaces have been investigated by way of NMR and dielectric measuring techniques. It is shown that structural ordering of the adsorbed water layers occurs, that the ...

E. Forslind A. Jacobsson

1970-01-01

346

Use of clays as drug delivery systems: Possibilities and limitations  

Microsoft Academic Search

The need for safe, therapeutically effective and patient-compliant drug delivery systems continuously leads researchers to design novel tools and strategies. Clay minerals are widely used materials in drug products both as excipients and active agents. When administered simultaneously, drug–clay interactions have been observed and studied, but until recently were not considered as a possible mechanism to modify drug release. In

C. Aguzzi; P. Cerezo; C. Viseras; C. Caramella

2007-01-01

347

Rock Maker: an MS Excel™ spreadsheet for the calculation of rock compositions from proportional whole rock analyses, mineral compositions, and modal abundance  

NASA Astrophysics Data System (ADS)

Rock Maker is a simple software tool that computes bulk rock compositions resulting from mixing or unmixing of rocks or minerals. The calculations describe the chemical expression of processes such as magma mixing, fractional crystallization, assimilation, residual melt extraction, or formation of solid solutions. Rock Maker can also be used for the elimination of thermodynamically inactive or unwanted chemical components from the whole rock composition, such as cores of porphyroblasts that are considered not to be in equilibrium with the matrix. The calculation of the resulting rock composition is essentially based on modal proportions and compositions of different components in rocks, which may include specific portions of the rock or individual mineral phases. Compositional data, obtained using XRF, ICPMS, EDS, or EPMA, may include major and trace element concentrations. Depending upon the nature of the problem to be solved, the concentrations of oxidic and elemental components can be added to, or subtracted from, each other, producing the calculated normalized whole rock composition after completion of the investigated process (mixing, unmixing, depletion, enrichment, etc.). Furthermore, the software allows the calculation of whole rock compositions from ideal mineral compositions, for which modal proportions can be chosen from pre-defined mineral compositions. The data set includes the most common rock forming minerals and allows the addition of further phases. This section can be used to calculate the approximate whole rock compositions from petrographic modal analysis. This part of Rock Maker is specifically suitable as a teaching tool that illustrates the interrelationship between mineral compositions, modes, and the corresponding whole rock compositions.

Büttner, Steffen H.

2012-01-01

348

Mineral Composition and Abundance of the Rocks and Soils at Gusev and Meridiani from the Mars Exploration Rover Mini-TES Instruments  

NASA Astrophysics Data System (ADS)

Mini-TES has identified Mg and Ca sulfates and high-silica minerals in the Meridiani outcrops. Spherules are dominantly hematite. Plagioclase/pyroxene/olivine sands occur at both sites. Bounce Rock is a pyroxene-dominated basalt similar to EET79001

Christensen, P. R.; Wyatt, M. B.; Glotch, T. D.; Rogers, A. D.; Anwar, S.; Arvidson, R. E.; Bandfield, J. L.; Blaney, D. L.; Budney, C.; Calvin, W. M.; Fallacaro, A.; Fergason, R. L.; Gorelick, N.; Graff, T.; Hamilton, V. E.; Hayes, A. G.; Johnson, J. R.; Knudson, A. T.; McSween, H. Y., Jr.; Mehall, G. L.; Mehall, L. K.; Moersch, J. E.; Morris, R. V.; Smith, M. D.; Squyres, S. W.; Ruff, S. W.; Wolff, M. J.

2005-03-01

349

Natural Radioactivity of Boron Added Clay Samples  

NASA Astrophysics Data System (ADS)

Clay, consisting fine-grained minerals, is an interesting materials and can be used in a variety of diferent fields especially in dermatology application. Using clay such a field it is important to measure its natural radioacitivty. Thus the purpose of this study is to measure 226Ra, 232Th and 40K concentration in clay samples enriched with boron. Three different types of clay samples were prepared where boron is used in different rate. The measurements have been determined using a gamma-ray spectrometry consists of a 3''×3'' NaI(Tl) detector. From the measured activity the radium equivalent activities (Raeq), external hazard index (Hex), absorbed dose rate in air (D) and annual effective dose (AED) have also been obtained.

Akkurt, I.; Çanakci?, H.; Mavi, B.; Güno?lu, K.

2011-12-01

350

Natural Radioactivity of Boron Added Clay Samples  

SciTech Connect

Clay, consisting fine-grained minerals, is an interesting materials and can be used in a variety of different fields especially in dermatology application. Using clay such a field it is important to measure its natural radioactivity. Thus the purpose of this study is to measure {sup 226}Ra, {sup 232}Th and {sup 40}K concentration in clay samples enriched with boron. Three different types of clay samples were prepared where boron is used in different rate. The measurements have been determined using a gamma-ray spectrometry consists of a 3''x3'' NaI(Tl) detector. From the measured activity the radium equivalent activities (Ra{sub eq}), external hazard index (H{sub ex}), absorbed dose rate in air (D) and annual effective dose (AED) have also been obtained.

Akkurt, I.; Guenoglu, K. [Sueleyman Demirel University, Faculty of Arts and Sciences, Dept. of Physics, Isparta (Turkey); Canakcii, H. [Gaziantep University, Engineering Faculty, Civil Engineering Dept., Gaziantep (Turkey); Mavi, B. [Amasya University, Faculty of Arts and Sciences, Dept. of Physics, Amasya (Turkey)

2011-12-26

351

The abundance of nahAc genes correlates with the 14C-naphthalene mineralization potential in petroleum hydrocarbon-contaminated oxic soil layers  

Microsoft Academic Search

In this study, we evaluated whether the abundance of the functional gene nahAc reflects aerobic naphthalene degradation potential in subsurface and surface samples taken from three petroleum hydrocarbon contaminated sites in southern Finland. The type of the contamination at the sites varied from lightweight diesel oil to high molecular weight residuals of crude oil. Samples were collected from both oxic

Pirjo M. Tuomi; Jani M. Salminen; Kirsten S. Jørgensen

2004-01-01

352

Sulphate attack and ettringite formation in the lime and cement stabilized marine clays  

Microsoft Academic Search

Swelling and shrinkage behaviour of marine clays impose foundation problems that may sometimes results in excessive settlements. Improving the behaviour of soft clays using lime or cement is not new. Recent studies reported the occurrence of high swelling and pavement failures in lime and cement stabilized clays containing sulphates. The above phenomena resulted in the formation of swelling minerals such

G. Rajasekaran

2005-01-01

353

Seaweed minerals as nutraceuticals.  

PubMed

Seaweed is known as an abundant source of minerals. Mineral composition of seaweed is very changeable because of many exogenous and endogenous factors and differs also within the same species. Principally, seaweed is an excellent source of some essential elements. Mainly, iron and iodine are in high concentration. Seaweeds could be prospective as functional foods and also producers of mineral nutraceuticals. PMID:22054962

Mišurcová, Ladislava; Mach?, Ludmila; Orsavová, Jana

2011-01-01

354

Seaweed Minerals as Nutraceuticals  

Microsoft Academic Search

Seaweed is known as an abundant source of minerals. Mineral composition of seaweed is very changeable because of many exogenous and endogenous factors and differs also within the same species. Principally, seaweed is an excellent source of some essential elements. Mainly, iron and iodine are in high concentration. Seaweeds could be prospective as functional foods and also producers of mineral

Ladislava Mišurcová; Ludmila Mach?; Jana Orsavová

2011-01-01

355

High Temperature Clay Chemistry.  

National Technical Information Service (NTIS)

Hydrothermal experiments with clays such as sepiolite, attapulgite, saponite, and bentonite are described briefly. Rheological and minerological changes were studied in the clays subjected to hydrothermal treatments with and without the addition of the sa...

L. L. Carney N. Guven

1979-01-01

356

Communicating with Clay.  

ERIC Educational Resources Information Center

Presents a unit on clay that is centered around sign language in which students explore the slab method of working with clay. States that each student picks a letter of the sign language alphabet and fashions a clay hand to depict the letter. (CMK)

Skophammer, Karen

2000-01-01

357

Herbivore trampling as an alternative pathway for explaining differences in nitrogen mineralization in moist grasslands.  

PubMed

Studies addressing the role of large herbivores on nitrogen cycling in grasslands have suggested that the direction of effects depends on soil fertility. Via selection for high quality plant species and input of dung and urine, large herbivores have been shown to speed up nitrogen cycling in fertile grassland soils while slowing down nitrogen cycling in unfertile soils. However, recent studies show that large herbivores can reduce nitrogen mineralization in some temperate fertile soils, but not in others. To explain this, we hypothesize that large herbivores can reduce nitrogen mineralization in loamy or clay soils through soil compaction, but not in sandy soils. Especially under wet conditions, strong compaction in clay soils can lead to periods of soil anoxia, which reduces decomposition of soil organic matter and, hence, N mineralization. In this study, we use a long-term (37-year) field experiment on a salt marsh to investigate the hypothesis that the effect of large herbivores on nitrogen mineralization depends on soil texture. Our results confirm that the presence of large herbivores decreased nitrogen mineralization rate in a clay soil, but not in a sandy soil. By comparing a hand-mown treatment with a herbivore-grazed treatment, we show that these differences can be attributed to herbivore-induced changes in soil physical properties rather than to above-ground biomass removal. On clay soil, we find that large herbivores increase the soil water-filled porosity, induce more negative soil redox potentials, reduce soil macrofauna abundance, and reduce decomposition activity. On sandy soil, we observe no changes in these variables in response to grazing. We conclude that effects of large herbivores on nitrogen mineralization cannot be understood without taking soil texture, soil moisture, and feedbacks through soil macrofauna into account. PMID:23271034

Schrama, Maarten; Heijning, Pieter; Bakker, Jan P; van Wijnen, Harm J; Berg, Matty P; Olff, Han

2012-12-28

358

Bioleaching of iron from highly contaminated Kaolin clay by Aspergillus niger  

Microsoft Academic Search

Kaolin is a clay mineral that has a wide application in the industry specially, in paper, ceramic, and porcelain manufacturing. One of the most important factors that affects the value of this raw material is its brightness. Unfortunately, with the iron oxides deposit on mineral particles during kaolin formation, much of this clay has become unusable for industries. So, several

M. R. Hosseini; M. Pazouki; M. Ranjbar; M. Habibian

2007-01-01

359

Clay mineralogy of the malmian source rock of the Vienna Basin: Effects on shale gas exploration?  

Microsoft Academic Search

In an unique opportunity the diagenetic changes of clay minerals of a marlstone formation with only minor differences in provenance and depositional environment was studied from shallow (1400 m) to very deep (8550 m) burial. The clay mineralogy of 46 core samples from ten wells was quantified with X-ray diffraction in applying the mineral intensity factor (MIF)-method of Moore and

Andrea Schicker; Susanne Gier; Ulrich Herzog

2010-01-01

360

Frictional strength and the effective pressure law of montmorillonite and illite clays  

Microsoft Academic Search

Abstract Low-strength clay minerals are a common constituent of fault gouges, and are often cited as a possible explanation for the low ambient shear stresses along the San Andreas fault inferred from heat flow constraints and in situ stress measurements. Montmorillonite, the weakest of the clay minerals, undergoes a gradual phase transition to illite with depth. In order to compare

C. Morrow; B. Radney; J. D. Byerlee

1992-01-01

361

Iron oxide modified minerals  

Microsoft Academic Search

Composites of iron oxide nanoparticles immobilized on the surface of various clay mineral matrices (muscovite, montmorillonite\\u000a and vermiculite) have been prepared by the alkaline oxidative hydrolysis of iron sulphate in the presence of mineral matrices.\\u000a The composites have been studied by Mössbauer spectroscopy, XRD, TEM and SQUID. Correspondence between the hyperfine parameters\\u000a and the iron oxide particle size and magnetic

M. Mashlan; H. Bartonkova; D. Jancik; J. Tucek; P. Martinec

362

Iron oxide modified minerals  

Microsoft Academic Search

Composites of iron oxide nanoparticles immobilized on the surface of various clay mineral matrices (muscovite, montmorillonite\\u000a and vermiculite) have been prepared by the alkaline oxidative hydrolysis of iron sulphate in the presence of mineral matrices.\\u000a The composites have been studied by Mössbauer spectroscopy, XRD, TEM and SQUID. Correspondence between the hyperfine parameters\\u000a and the iron oxide particle size and magnetic

M. Mashlan; H. Bartonkova; D. Jancik; J. Tucek; P. Martinec

2009-01-01

363

Holocene debris flows on the Colorado Plateau: The influence of clay mineralogy and chemistry  

USGS Publications Warehouse

Holocene debris flows do not occur uniformly on the Colorado Plateau province of North America. Debris flows occur in specific areas of the plateau, resulting in general from the combination of steep topography, intense convective precipitation, abundant poorly sorted material not stabilized by vegetation, and the exposure of certain fine-grained bedrock units in cliffs or in colluvium beneath those cliffs. In Grand and Cataract Canyons, fine-grained bedrock that produces debris flows contains primarily single-layer clays - notably illite and kaolinite - and has low multilayer clay content. This clay-mineral suite also occurs in the colluvium that produces debris flows as well as in debris-flow deposits, although unconsolidated deposits have less illite than the source bedrock. We investigate the relation between the clay mineralogy and major-cation chemistry of fine-grained bedrock units and the occurrence of debris flows on the entire Colorado Plateau. We determined that 85 mapped fine-grained bedrock units potentially could produce debris flows, and we analyzed clay mineralogy and major-cation concentration of 52 of the most widely distributed units, particularly those exposed in steep topography. Fine-grained bedrock units that produce debris flows contained an average of 71% kaolinite and illite and 5% montmorillonite and have a higher concentration of potassium and magnesium than nonproducing units, which have an average of 51% montmorillonite and a higher concentration of sodium. We used multivariate statistics to discriminate fine-grained bedrock units with the potential to produce debris flows, and we used digital-elevation models and mapped distribution of debris-flow producing units to derive a map that predicts potential occurrence of Holocene debris flows on the Colorado Plateau. ?? 2008 Geological Society of America.

Webb, R. H.; Griffiths, P. G.; Rudd, L. P.

2008-01-01

364

Li, Be, and B abundances in minerals of peridotite xenoliths from Marsabit (Kenya): Disequilibrium processes and implications for subduction zone signatures  

NASA Astrophysics Data System (ADS)

The light elements Li, Be, and B have been analyzed in situ in minerals from three groups of peridotite xenoliths hosted in Quaternary basanites from the Marsabit volcanic field (northern Kenya). Group I and II are fertile lherzolites that experienced deformation, decompression, and cooling in the context of Mesozoic rifting (Group I), followed by heating, static recrystallization, and associated cryptic metasomatism (Group II) as a result of Tertiary-Quaternary rifting and magmatism. Group III xenoliths are spinel harzburgites and dunites that experienced strong cryptic and modal metasomatism. The Li-Be-B systematics in minerals of Group I and II are similar to unmetasomatized subcontinental lithospheric mantle. In contrast, Group III samples are characterized by significant enrichment in all light elements and disequilibrium partitioning between different phases. Light element concentrations levels are similar to that expected for mantle rocks metasomatized by melts and fluids released from subducting slabs, while light element/rare earth element ratios (especially Li/Yb) approach those of typical Island Arc basalts. However, detailed investigation of textures and chemical zoning shows that at least Li concentrations in primary minerals were modified (i.e., decoupled from Yb) during late-stage melting and/or fluid percolation related to Tertiary-Quaternary alkaline magmatism in Marsabit (formation of melt pockets consisting of silicate glass, clinopyroxene, olivine, and chromite), ultimately followed by xenolith entrapment and transport to the surface. Mass balance calculations show that the melt pockets formed at the expense of earlier metasomatic phases. During this process the melt pockets mostly preserved the B, Be, and rare earth element budget of the precursor phase assemblage, whereas Li was added. Elevated B/Be and low Ce/B of metasomatic phases prior to late melting could result from metasomatism by a slab fluid. However, similar characteristics are expected for evolved Si- and CO2-rich fluids derived from basanite melt-peridotite interaction, not related to any subduction zone process. The results of this study imply that the inference of a "slab signature" exclusively based on trace element data of metasomatized peridotite is ambiguous.

Kaeser, Benjamin; Kalt, Angelika; Ludwig, Thomas

2007-09-01

365

What Makes a Natural Clay Antibacterial?  

PubMed Central

Natural clays have been used in ancient and modern medicine, but the mechanism(s) that make certain clays lethal against bacterial pathogens has not been identified. We have compared the depositional environments, mineralogies, and chemistries of clays that exhibit antibacterial effects on a broad spectrum of human pathogens including antibiotic resistant strains. Natural antibacterial clays contain nanoscale (<200 nm), illite-smectite and reduced iron phases. The role of clay minerals in the bactericidal process is to buffer the aqueous pH and oxidation state to conditions that promote Fe2+ solubility. Chemical analyses of E. coli killed by aqueous leachates of an antibacterial clay show that intracellular concentrations of Fe and P are elevated relative to controls. Phosphorus uptake by the cells supports a regulatory role of polyphosphate or phospholipids in controlling Fe2+. Fenton reaction products can degrade critical cell components, but we deduce that extracellular processes do not cause cell death. Rather, Fe2+ overwhelms outer membrane regulatory proteins and is oxidized when it enters the cell, precipitating Fe3+ and producing lethal hydroxyl radicals.

Williams, Lynda B.; Metge, David W.; Eberl, Dennis D.; Harvey, Ronald W.; Turner, Amanda G.; Prapaipong, Panjai; Poret-Peterson, Amisha T.

2011-01-01

366

Quantitative x-ray powder diffraction analyses of clays using an orienting internal standard and pressed disks of bulk shale samples  

Microsoft Academic Search

Quantitative analysis of clay minerals by x-ray diffraction requires oriented clays in order to increase detection limits of the analyses. This is achieved commonly either by smear or sedimentation techniques; however, these techniques can lead to poor analytical precision when used with an internal standard because they often produce nonhomogeneous internal standard-clay mineral mixtures. Compaction of bulk shale material at

R. D. Cody; G. L. Thompson

1975-01-01

367

Influence of improved subsurface drainage on phosphorus losses and nitrogen leaching from a heavy clay soil  

Microsoft Academic Search

Without proper subsurface drainage of heavy clay soil, water logging due to low hydraulic conductivity of the surface soil and especially the subsoil will lead to abundant surface runoff. The abundant runoff will induce soil erosion and phosphorus losses. To determine the influence of improved subsurface drainage (IMP) on soil erosion, phosphorus losses and nitrogen leaching, a heavy clay soil

E. Turtola; A. Paajanen

1995-01-01

368

Mineral Commodities  

NSDL National Science Digital Library

This exercise introduces mineral commodities (elements). Students consider the elements aluminum, iron, copper, nickel, zinc, uranium, lead, gold, mercury and tin and match them with their definintions in a table. Then they use minable grade (minable weight percent) and normal crustal abundance (crustal weight percent) to calculate the concentration factor for several commodities to determine their economic minability. Students then graph their calculations and explain their trend.

Perkins, Dexter

369

Yangtze River sediments from source to sink traced with clay mineralogy  

NASA Astrophysics Data System (ADS)

River bed sediments were collected from the main stream and major tributaries of the Yangtze River for clay mineralogy study. Surface sediments from the Yarlung Zangbo River on the Tibetan Plateau were also examined for comparison. The results show that the clay mineral compositions of the Yangtze River display a similar pattern through the whole truck stream, with illite being dominant, kaolinite and chlorite being lesser abundant, and smectite being minor component. Clay mineralogy shows distinct differences in the tributaries, which correspond to the heterogeneous source rocks and weathering intensity of the drainage. The illite crystallity and the illite chemical weathering index (5 Å/10 Å peak ratio) both increase downstream, indicating a increasing trend of hydrolysis along the river. It also indicates that the upperstream of the drainage is characterized with physical weathering while the middle- and lower reaches are controlled by chemical weathering process. In accordance with the result derived by the illite indexes, sediment input from upperstream including Yalong Jiang, Dadu He, Min Jiang and Jialing Jiang accounts for the major sediment load, whereas Wu Jiang, Xiang Jiang, Gan Jiang and Dongting Lake provide relatively less sediments.

He, Mengying; Zheng, Hongbo; Huang, Xiangtong; Jia, Juntao; Li, Ling

2013-06-01

370

Geochemical modulation of pesticide sorption on smectite clay.  

PubMed

Pesticide adsorption by soil clays can be dramatically influenced by the exchangeable cations present. Among the common exchangeable base cations in soils (Ca2+, Mg2+, K+, and Na+), K+-saturated clays frequently demonstrate the strongest affinity for pesticides. In the presence of multiple exchangeable cations in the system, we hypothesize that the magnitude of pesticide sorption to soil minerals is proportional to the fraction of clay interlayers saturated with K+ ions. To test this hypothesis, we measured sorption of three pesticides with different polarities (dichlobenil, monuron, and biphenyl) by homoionic K- and Ca-smectite (SWy-2) in KCl/CaCl2 aqueous solutions. The presence of different amounts of KCl and CaCl2 resulted in varying populations of K+ and Ca2+ on the clay exchange sites. The sorption of dichlobenil and, to a lesser extent monuron, increased with the fraction of K+ on clay mineral exchange sites. Ca- and K-SWy-2 displayed the same sorption capacities for nonpolar biphenyl. X-ray diffraction patterns indicated that at lower fractions of K+-saturation, exchangeable K+ ions were randomly distributed in clay interlayers and did not enhance pesticide sorption. At higher populations of K+ (vs Ca2+), demixing occurred causing some clay interlayers, regions, or tactoids to become fully saturated by K+, manifesting greatly enhanced pesticide sorption. The forward and reverse cation exchange reactions influenced not only K+ and Ca2+ populations on clays but also the nanostructures of clay quasicrystals in aqueous solution which plays an important, if not dominant, role in controlling the extent of pesticide sorption. Modulating the cation type and composition on clay mineral surfaces through cation exchange processes provides an environmental-safe protocol to manipulate the mobility and availability of polar pesticides, which could have applications for pesticide formulation and in environmental remediation. PMID:15543742

Li, Hui; Teppen, Brian J; Laird, David A; Johnston, Cliff T; Boyd, Stephen A

2004-10-15

371

Modified clay sorbents  

DOEpatents

A novel modified clay sorbent and method of treating industrial effluents to remove trace pollutants, such as dioxins, biphenyls, and polyaromatics such as benzo(a)pyrene and pentachlorophenol. The novel clay sorbent has a composite structure in which the interlayer space of an expandable clay, such as smectite, is filled with polyvalent or multivalent inorganic cations which forces weaker surfactant cations to locate on the surface of the clay in such an orientation that the resulting composite is hydrophilic in nature. A specific example is cetylpyridinium-hydroxy aluminum-montmorillonite. In certain embodiments, a non-expanding clay, such as kaolinite, is used and surfactant cations are necessarily located on an external surface of the clay. A specific example is cetylpyridinium-kaolinite.

Fogler, H. Scott (Ann Arbor, MI); Srinivasan, Keeran R. (Livonia, MI)

1990-01-01

372

Polymer-Clay Nanocomposites  

Microsoft Academic Search

The development of polymer-clay nanocomposite materials, in which nanometer-thick layers of clay are dispersed in polymers, was first achieved about 15 years ago. Since then, the materials have gradually become more widely used in applications such as automotive production. The first practical nylon-clay nanocomposite was synthesized by a monomer intercalation technique; however, the production process has been further developed and a compound

Arimitsu Usuki; Naoki Hasegawa; Makoto Kato; Shiro Kobayashi

373

Flow of clays  

NASA Astrophysics Data System (ADS)

Recent experimental and theoretical research into physical phenomena in clays is reviewed. Clays' present place in the context of modern materials science is briefly discussed, and illustrated through the rich behavior recently displayed in this physical model system. We will show that in order to understand macroscopic flow behaviors in these systems, it is crucial to know the underlying nanostructures in detail. With the clay nanostructural basis at hand, we will review recent advances in clay systems from the geological example of quick clay flows and avalanches, to materials science and the stability, strength and flow of smart electrorheological clay structures. In the case of natural quick clay, there is now hope of establishing a protocol for avalanche preditction based on rheological sample data. In materials science, the use of electric fields together with flow in order to improve the processing of clay composite materials may open new unexplored avenues. We will finally discuss that due to the interplay of van der Waals and electrostatic forces screened by ions at the nanoscale, clays may either form a glass, or a gel and thus give fundamental insights into the elusive questions related to materials universal aging flow dynamics.

Fossum, J. O.

2012-04-01

374

Thermoluminescence of minerals useful for identification of irradiated seafood  

NASA Astrophysics Data System (ADS)

Irradiated seafood can be identified by determining thermoluminescence of minerals isolated from the intestines. In this study the suitability of different minerals was investigated. The main mineral fractions isolated from the intestines of seafood were single silicate grains, shell pieces and clays. Silicate minerals are best suited for the detection of irradiation because of their stable and strong TL signal. However, shell pieces, mostly carbonates, and clays, also allowed a reliable detection.

Pinnioja, S.; Pajo, L.

1995-02-01

375

Adsorption of nucleotides onto Fe-Mg-Al rich swelling clays  

NASA Astrophysics Data System (ADS)

Mineral surfaces may have played a role in the origin of the first biopolymers, by concentrating organic monomers from a dilute ocean. Swelling clays provide a high surface area for the concentration of prebiotic monomers, and have therefore been the subject of numerous investigations. In that context, montmorillonite, the most abundant swelling clay in modern environments, has been extensively studied with regard to adsorption and polymerization of nucleic acids. However, montmorillonite was probably rather marginal on the primitive ocean floor compared to iron-magnesium rich phyllosilicates such as nontronite that results from the hydrothermal alteration of a mafic or ultramafic oceanic crust. In the present paper, we study the adsorption of nucleotides on montmorillonite and nontronite, at various pH and ionic strength conditions plausible for Archean sea-water. A thorough characterization of the mineral surfaces shows that nucleotide adsorb mainly on the edge faces of the smectites by ligand exchange between the phosphate groups of the nucleotides and the -OH groups from the edge sites over a wide pH range (4-10). Nontronite is more reactive than montmorillonite. At low pH, additional ion exchange may play a role as the nucleotides become positively charged.

Feuillie, Cécile; Daniel, Isabelle; Michot, Laurent J.; Pedreira-Segade, Ulysse

2013-11-01

376

Carboxylate clays: A model study for polypropylene\\/clay nanocomposites  

Microsoft Academic Search

Sodium-montmorillonite was intercalated by carboxylate salts to prepare carboxylate clays. The intercalation of sodium acetate doubles the clay basal spacing and no degradation of the carboxylate clay is noticed in the extrusion temperature range. These carboxylate clays were used to synthesize polypropylene-graft-maleic anhydride (PP-g-MA)\\/clay nanocomposites. Nanocomposites were also produced by a one-pot process using in situ prepared carboxylate clay. The

Dimitri D. J. Rousseaux; Michel Sclavons; Pierre Godard; Jacqueline Marchand-Brynaert

2010-01-01

377

Enzyme-clay interactions and their impact on transformations of natural and anthropogenic organic compounds in soil  

Microsoft Academic Search

Soil is a living system in which enzymes are present either free in solution or bound to clay and clay-humus complexes. Enzyme-clay interactions play a key role in transforming organic compounds in soil environments where the decomposition and synthetic processes are largely catalyzed by enzymes. Scientific evidence indicates that mineral colloids take part in the catalysis of degradative and synthetic

A. Naidja; P. M. Huang; J.-M. Bollag

2000-01-01

378

Pedogenesis and clay mineralogical investigation of soils formed on gypsiferous and calcareous materials, on a transect, southwestern Iran  

Microsoft Academic Search

This study examined pedogenesis, as well as the clay mineralogy of soil and rock samples obtained from a transect of gypsiferous and calcareous materials. The main objectives of this research were to study the relationship between clay minerals and physiographic units as well as the relative importance of key pedogenic processes in controlling clay mineralogy. Palygorskite, chlorite, illite, smectite, quartz

H. R. Owliaie; A. Abtahi; R. J. Heck

2006-01-01

379

Effects of Forest Clearing on Soil Organic Carbon Dynamics in Central Panama: Evidence from Natural 13C Abundance, Physical Soil Fractionation and Carbon Mineralization  

NASA Astrophysics Data System (ADS)

Tropical ecosystems play an important role in the global carbon budget. About 44% of global soil organic carbon (SOC) is located in tropical areas. Forest clearing in tropical regions is estimated to contribute about 23% to human-induced CO2 emissions. We use natural 13C abundance coupled with soil fractionation techniques and incubation studies to evaluate SOC dynamics following forest clearing in Central Panama. Soil samples were taken at 0-5, 5-10, 10-15, 15-20, 20-30, 30-40 and 40-50 cm depths from an undisturbed forest site and an adjacent clearing where the forest was cut approximately 80 years ago. Carbon concentration throughout both profiles is highest in the macro-aggregate fraction (250-2000? m). 13C values of the macro-aggregate fraction of the undisturbed forest ranged form -25.9‰ in the topsoil to -21.1‰ in the subsoil. Carbon in the topsoil of the clearing was more enriched in 13C (-18.3‰ ), reflecting the input of C4 vegetation with 13C values of -16.8‰ . The macro-aggregate fraction at both sites showed comparatively high 13C values in the subsoil, suggesting that microbial fractionation enriched the older/deeper soil organic carbon. Particle-size and density fractionation will help elucidate this pattern. Mineralizable carbon from bulk soil was measured in an incubation experiment. The CO2 flux and 13CO2 signal of respired carbon were determined over time. On the first days of incubation the amount of CO2 evolved did not differ between sites. However, 13CO2 values from the clearing were more enriched compared to those from the forest site, indicating that the initial respiration is dominated by the actual, labile carbon pool. The values of 13C for soil organic carbon and 13CO2 will be used to determine the soil carbon pool sizes and to calculate the turnover time of soil organic carbon in this moist humid ecosystem. These experiments will contribute to parameterization of carbon cycle models for tropical ecosystems.

Schwendenmann, L. C.; Pendall, E. G.

2004-05-01

380

Rocks and Minerals  

NSDL National Science Digital Library

This unit provides younger students with an introduction to rocks and minerals. Topics include the definition of a mineral, the physical properties of minerals and how they are measured, and a discussion of quartz, the most basic silicate mineral and one of the most abundant minerals in the Earth's crust. The discussion on rocks includes the rock cycle, the three rock types (igneous, sedimentary, metamorphic), and how they are formed. There is also a vocabulary list and downloadable, printable worksheets for each major topic.

Medina, Philip

2010-09-08

381

Rocks and Minerals  

NSDL National Science Digital Library

This unit provides younger students with an introduction to rocks and minerals. Topics include the definition of a mineral, the physical properties of minerals and how they are measured, and a discussion of quartz, the most basic silicate mineral and one of the most abundant minerals in the Earth's crust. The discussion on rocks includes the rock cycle, the three rock types (igneous, sedimentary, metamorphic), and how they are formed. There is also a vocabulary list and downloadable, printable worksheets for each major topic.

Medina, Philip

382

CHEMICAL AND MINERALOGICAL CHARACTERISTICS OF FRENCH GREEN CLAYS USED FOR HEALING  

PubMed Central

The worldwide emergence of infectious diseases, together with the increasing incidence of antibiotic-resistant bacteria, elevate the need to properly detect, prevent, and effectively treat these infections. The overuse and misuse of common antibiotics in recent decades stimulates the need to identify new inhibitory agents. Therefore, natural products like clays, that display antibacterial properties, are of particular interest. The absorptive properties of clay minerals are well documented for healing skin and gastrointestinal ailments. However, the antibacterial properties of clays have received less scientific attention. French green clays have recently been shown to heal Buruli ulcer, a necrotic or ‘flesh-eating’ infection caused by Mycobacterium ulcerans. Assessing the antibacterial properties of these clays could provide an inexpensive treatment for Buruli ulcer and other skin infections. Antimicrobial testing of the two clays on a broad-spectrum of bacterial pathogens showed that one clay promotes bacterial growth (possibly provoking a response from the natural immune system), while another kills bacteria or significantly inhibits bacterial growth. This paper compares the mineralogy and chemical composition of the two French green clays used in the treatment of Buruli ulcer. Mineralogically, the two clays are dominated by 1Md illite and Fe-smectite. Comparing the chemistry of the clay minerals and exchangeable ions, we conclude that the chemistry of the clay, and the surface properties that affect pH and oxidation state, control the chemistry of the water used to moisten the clay poultices and contribute the critical antibacterial agent(s) that ultimately debilitate the bacteria.

Williams, Lynda B.; Haydel, Shelley E.; Giese, Rossman F.; Eberl, Dennis D.

2008-01-01

383

Columns in Clay  

ERIC Educational Resources Information Center

|This article describes a clay project for students studying Greece and Rome. It provides a wonderful way to learn slab construction techniques by making small clay column capitols. With this lesson, students learn architectural vocabulary and history, understand the importance of classical architectural forms and their influence on today's…

Leenhouts, Robin

2010-01-01

384

Columns in Clay  

ERIC Educational Resources Information Center

This article describes a clay project for students studying Greece and Rome. It provides a wonderful way to learn slab construction techniques by making small clay column capitols. With this lesson, students learn architectural vocabulary and history, understand the importance of classical architectural forms and their influence on today's…

Leenhouts, Robin

2010-01-01

385

The Science of Clay  

ERIC Educational Resources Information Center

Students' natural curiosity provides a rich opportunity for teachers to make meaningful scientific connections between art and ceramics that will enhance the understanding of both natural forces and scientific aspects at work in the creation of clay artworks. This article discusses the scientific areas of study related to clay, which include…

Warwick, Sharon

2005-01-01

386

Application of Hyperspectral Methods in Hydrothermal Mineral System Studies  

NASA Astrophysics Data System (ADS)

Hyperspectral infrared reflectance spectra are used to identify abundances and compositional differences of mineral groups and single mineral phases. 3D mineral maps are derived from surface (airborne and satellite sensed) and sub-surface (drill core) mineralogical data and integrated with geological, geochemical and geophysical datasets, enabling a quantitative mineral systems analysis. The Western Australian Centre of Excellence for 3D Mineral Mapping is working on a variety of mineral deposits to showcase the emerging applications of hyperspectral techniques in mineral system studies. Applied remote sensing technologies comprise hyperspectral airborne surveys (HyMap) covering 126 bands in the visible and shortwave infrared, as well as satellite-based multispectral surveys (ASTER) featuring 14 bands from the visible to thermal infrared. Drill cores were scanned with CSIRO's HyLoggingTM systems, which allow a fast acquisition of mineralogical data in cm-spacing and thereby providing statistically significant datasets. Building on procedures developed for public Australian geosurvey data releases for north Queensland, Broken Hill and Kalgoorlie (http://c3dmm.csiro.au), the ultimate goal is to develop sensor-independent scalars based on the position, depth and shape of selected absorption features in the visible-near (VNIR), shortwave (SWIR) and thermal infrared (TIR), which can be applied to a wide range of mineral deposit types. In the Rocklea Dome Channel Iron Ore deposits of the Pilbara (Western Australia) for example, hyperspectral drill core data were processed into 3D mineral maps to delineate major ore zones by identifying various ore types and possible contaminants. Vitreous (silica-rich) iron ore was successfully separated from ochreous goethitic ore, with both of them requiring different metallurgical processing. The silicified vitreous iron ore as well as outlined carbonate-rich zones are presumably related to overprinting groundwater effects. The hyperspectral mineral mapping of contaminating, carbonate- or clay-rich zones helped to better constrain the ore zones and the genesis of the mineral system. Airborne hyperspectral data covering about 2500 km2 were obtained from the Eastern Goldfields Superterrane (Yilgarn Craton, Western Australia), which is highly prospective for Archean Au as well as komatiite associated Fe-Ni sulphide mineralisation. In this project hyperspectral airborne data allowed not only the remote mapping of mafic and ultramafic rocks, which are among the main host rocks for Archean Au deposits in the study area, but also the remote mapping of hydrothermal alteration patterns and various geochemical signatures related to the structurally controlled Au mineralisation down to a 4.5 m pixel size. We can reconstruct fluid pathways and their intersections with steep physicochemical gradients, where Au deposition presumably took place, by combining hyperspectral remote sensing with hyperspectral drill core data in 3D mineral maps. White mica mineral maps as well as mineral maps based on the abundance and composition of MgOH and FeOH bearing silicates are the main products for a semi-quantitative assessment of the key alteration minerals in this project. In the southern Selwyn Range, Mount Isa Inlier, Queensland, hyperspectral mineral maps, such as "ferric oxide abundance", "white mica abundance" and "white mica composition", were integrated with geophysical datasets (total magnetic intensity, ternary radiometric imagery). The integration of the datasets enabled us to construct a comprehensive fluid flow model contributing to our understanding of iron-oxide Cu-Au deposits in this region, identifying the source, pathway and depositional sites, which are in good accordance with known deposits. 3D mineral maps derived from hyperspectral methods can distinctly improve our understanding of mineral systems. The advantages of hyperspectral techniques over conventional exploration methods include: (1) the fast and cost efficient acquisition of both surface and sub-surface mi

Laukamp, Carsten; Cudahy, Thomas; Gessner, Klaus; Haest, Maarten; Cacetta, Mike; Rodger, Andrew; Jones, Mal; Thomas, Matilda

2010-05-01

387

Seismic Properties of Opalinus Clay During Triaxial Deformation  

Microsoft Academic Search

Argillaceous formations are being considered as potential host rocks for repositories of radioactive waste. For analysing hydrogeological, geochemical and rock mechani- cal properties an underground rock laboratory has been established in the reconnais- sance gallery of the Mont Terri situated in the Opalinus Clay formation. This host rock consists mainly of 40-70% clay minerals, 10-30% quartz and 5-20% calcite with

T. Popp; G. Braun

2002-01-01

388

The role of reaction affinity and secondary minerals in regulating chemical weathering rates at the Santa Cruz Soil Chronosequence, California  

USGS Publications Warehouse

In order to explore the reasons for the apparent discrepancy between laboratory and field weathering rates and to determine the extent to which weathering rates are controlled by the approach to thermodynamic equilibrium, secondary mineral precipitation, and flow rates, a multicomponent reactive transport model (CrunchFlow) was used to interpret soil profile development and mineral precipitation and dissolution rates at the 226 ka Marine Terrace Chronosequence near Santa Cruz, CA. Aqueous compositions, fluid chemistry, transport, and mineral abundances are well characterized [White A. F., Schulz M. S., Vivit D. V., Blum A., Stonestrom D. A. and Anderson S. P. (2008) Chemical weathering of a Marine Terrace Chronosequence, Santa Cruz, California. I: interpreting the long-term controls on chemical weathering based on spatial and temporal element and mineral distributions. Geochim. Cosmochim. Acta 72 (1), 36-68] and were used to constrain the reaction rates for the weathering and precipitating minerals in the reactive transport modeling. When primary mineral weathering rates are calculated with either of two experimentally determined rate constants, the nonlinear, parallel rate law formulation of Hellmann and Tisserand [Hellmann R. and Tisserand D. (2006) Dissolution kinetics as a function of the Gibbs free energy of reaction: An experimental study based on albite feldspar. Geochim. Cosmochim. Acta 70 (2), 364-383] or the aluminum inhibition model proposed by Oelkers et al. [Oelkers E. H., Schott J. and Devidal J. L. (1994) The effect of aluminum, pH, and chemical affinity on the rates of aluminosilicate dissolution reactions. Geochim. Cosmochim. Acta 58 (9), 2011-2024], modeling results are consistent with field-scale observations when independently constrained clay precipitation rates are accounted for. Experimental and field rates, therefore, can be reconciled at the Santa Cruz site. Additionally, observed maximum clay abundances in the argillic horizons occur at the depth and time where the reaction fronts of the primary minerals overlap. The modeling indicates that the argillic horizon at Santa Cruz can be explained almost entirely by weathering of primary minerals and in situ clay precipitation accompanied by undersaturation of kaolinite at the top of the profile. The rate constant for kaolinite precipitation was also determined based on model simulations of mineral abundances and dissolved Al, SiO2(aq) and pH in pore waters. Changes in the rate of kaolinite precipitation or the flow rate do not affect the gradient of the primary mineral weathering profiles, but instead control the rate of propagation of the primary mineral weathering fronts and thus total mass removed from the weathering profile. Our analysis suggests that secondary clay precipitation is as important as aqueous transport in governing the amount of dissolution that occurs within a profile because clay minerals exert a strong control over the reaction affinity of the dissolving primary minerals. The modeling also indicates that the weathering advance rate and the total mass of mineral dissolved is controlled by the thermodynamic saturation of the primary dissolving phases plagioclase and K-feldspar, as is evident from the difference in propagation rates of the reaction fronts for the two minerals despite their very similar kinetic rate laws. ?? 2009 Elsevier Ltd.

Maher, K.; Steefel, C. I.; White, A. F.; Stonestrom, D. A.

2009-01-01

389

Biodegradation of crude oil saturated fraction supported on clays.  

PubMed

The role of clay minerals in crude oil saturated hydrocarbon removal during biodegradation was investigated in aqueous clay/saturated hydrocarbon microcosm experiments with a hydrocarbon degrading microorganism community. The clay minerals used for this study were montmorillonite, palygorskite, saponite and kaolinite. The clay mineral samples were treated with hydrochloric acid and didecyldimethylammonium bromide to produce acid activated- and organoclays respectively which were used in this study. The production of organoclay was restricted to only montmorillonite and saponite because of their relative high CEC. The study indicated that acid activated clays, organoclays and unmodified kaolinite, were inhibitory to biodegradation of the hydrocarbon saturates. Unmodified saponite was neutral to biodegradation of the hydrocarbon saturates. However, unmodified palygorskite and montmorillonite were stimulatory to biodegradation of the hydrocarbon saturated fraction and appears to do so as a result of the clays' ability to provide high surface area for the accumulation of microbes and nutrients such that the nutrients were within the 'vicinity' of the microbes. Adsorption of the saturated hydrocarbons was not significant during biodegradation. PMID:23670057

Ugochukwu, Uzochukwu C; Jones, Martin D; Head, Ian M; Manning, David A C; Fialips, Claire I

2013-05-14

390

Molecular-level analysis of organic matter structure and composition from different soil mineral fractions  

NASA Astrophysics Data System (ADS)

The formation and turnover of soil organic matter (SOM) depends on the inherent chemical characteristics of biomolecular inputs (lignin, proteins, carbohydrates, macromolecular lipids, etc.) as well as the interactions between biomolecules and soil mineral fractions. The objective of this study is to characterize organic matter associated with the light, sand, silt and clay fractions of a Canadian agricultural soil. And, because lignin is believed to be a major contributor in SOM formation and preservation, the oxidation state of lignin in the different mineral fractions was measured using mild alkaline copper oxidation and gas chromatography - mass spectrometery which releases lignin phenols that are indicative of lignin sources and stage of degradation. For example, an increase in the acid/aldehyde (Ad/Al) ratio of lignin phenols has been observed with increased lignin degradation (and oxidation). In this study, lignin phenols from organic matter associated with the clay fraction had higher Ad/Al ratios for both syringyl and vanillyl lignin monomers when compared to that associated with silt, sand and the whole soil. These results suggest that either lignin degradation is enhanced by SOM association with clay surfaces or that oxidized lignin is preserved on clay mineral surfaces via sorption after partial degradation has occurred. The structural characteristics of organic matter from the soil fractions will also be examined by solid-state 13C nuclear magnetic resonance (NMR) spectroscopy. Organic matter associated with each mineral fraction will be extracted with NaOH for high resolution solution-state NMR spectroscopy. Results from NMR analysis will determine the relative abundance of functional groups (alkane, aromatic, carbonyl, alkoxy) in each of the soil fractions. Relative intensities of the functional groups are indicative of relative contributions of biomolecular classes such as lipids, lignin, fatty acids, and sugars to the organic matter associated with each fraction. The study comprises our initial steps in characterizing protection mechanisms responsible for the long-term retention and stability of biomolecules and their degradation intermediates in soil.

Clemente, J. S.; Gregorich, E. G.; Simpson, A. J.; Simpson, M. J.

2009-04-01

391

Molecular-Level Analysis of Organic Matter Structure and Composition from Different Soil Mineral Fractions  

NASA Astrophysics Data System (ADS)

The formation and turnover of soil organic matter (SOM) depends on the inherent chemical characteristics of biomolecular inputs (lignin, proteins, carbohydrates, macromolecular lipids, etc.) as well as the interactions between biomolecules and soil mineral fractions. The objective of this study is to characterize organic matter associated with the light, sand, silt and clay fractions of a Canadian agricultural soil. And, because lignin is believed to be a major contributor in SOM formation and preservation, the oxidation state of lignin in the different mineral fractions was measured using mild alkaline copper oxidation and gas chromatography - mass spectrometery which releases lignin phenols that are indicative of lignin sources and stage of degradation. For example, an increase in the acid/aldehyde (Ad/Al) ratio of lignin phenols has been observed with increased lignin degradation (and oxidation). In this study, lignin phenols from organic matter associated with the clay fraction had higher Ad/Al ratios for both syringyl and vanillyl lignin monomers when compared to that associated with silt, sand and the whole soil. These results suggest that either lignin degradation is enhanced by SOM association with clay surfaces or that oxidized lignin is preserved on clay mineral surfaces via sorption after partial degradation has occurred. The structural characteristics of organic matter from the soil fractions will also be examined by solid-state 13C nuclear magnetic resonance (NMR) spectroscopy. Organic matter associated with each mineral fraction will be extracted with NaOH for high resolution solution-state NMR spectroscopy. Results from NMR analysis will determine the relative abundance of functional groups (alkane, aromatic, carbonyl, alkoxy) in each of the soil fractions. Relative intensities of the functional groups are indicative of relative contributions of biomolecular classes such as lipids, lignin, fatty acids, and sugars to the organic matter associated with each fraction. The study comprises our initial steps in characterizing protection mechanisms responsible for the long-term retention and stability of biomolecules and their degradation intermediates in soil.

Clemente, J. S.; Gregorich, E. G.; Simpson, A. J.; Simpson, M. J.

2009-05-01

392

Clay fraction mineralogy of a Cambisol in Brazil  

NASA Astrophysics Data System (ADS)

Clay minerals having a 2:1 (tetrahedral:octahedral sheet) structure may be found in strongly weathering soils only if the local pedo-climatic environment prevents them from further weathering to other minerals such as iron oxides. The clay minerals impart important chemical properties to soils, in part by virtue of changes in the redox state of iron in their crystal structures. Knowing the chemical nature of soil clays is a first step in evaluating their potential reactivity with other soil constituents and processes, such as the chemical decomposition of organic substrates to be potentially used in environmental remediation. The purpose of this work was to characterize the iron oxides and iron-bearing clay minerals from a B horizon of a Cambisol developed on tuffite in the State of Minas Gerais, Brazil, using chemical analysis, powder X-ray diffraction, Mössbauer spectroscopy, and thermal analysis. The iron oxides of this NaOH-treated clay-fraction were found to contain mainly maghemite (?Fe2O3) and superparamagnetic goethite (?FeOOH). Kaolinite (Al2Si2O5(OH)4), smectite, and minor portions of anatase (TiO2) were identified in the CBD-treated sample.

Anastacio, A. S.; Fabris, J. D.; Stucki, J. W.; Coelho, F. S.; Pinto, I. V.; Viana, J. H. M.

2005-11-01

393

Sb(III) and Sb(V) sorption onto Al-rich phases: hydrous Al oxide and the clay minerals kaolinite KGa-1b and oxidized and reduced nontronite NAu-1.  

PubMed

We have studied the immobilization of Sb(III) and Sb(V) by Al-rich phases - hydrous Al oxide (HAO), kaolinite (KGa-1b), and oxidized and reduced nontronite (NAu-1) - using batch experiments to determine the uptake capacity and the kinetics of adsorption and Extended X-ray Absorption Fine Structure (EXAFS) Spectroscopy to characterize the molecular environment of adsorbed Sb. Both Sb(III) and Sb(V) are adsorbed in an inner-sphere mode on the surfaces of the studied substrates. The observed adsorption geometry is mostly bidentate corner-sharing, with some monodentate complexes. The kinetics of adsorption is relatively slow (on the order of days), and equilibrium adsorption isotherms are best fit using the Freundlich model. The oxidation state of the structural Fe within nontronite affects the adsorption capacity: if the clay is reduced, the adsorption capacity of Sb(III) is slightly decreased, while Sb(V) uptake is increased significantly. This may be a result of the presence of dissolved Fe(II) in the reduced nontronite suspensions or associated with the structural rearrangements in nontronite due to reduction. These research findings indicate that Sb can be effectively immobilized by Al-rich phases. The increase in Sb(V) uptake in response to reducing structural Fe in clay can be important in natural settings since Fe-rich clays commonly go through oxidation-reduction cycles in response to changing redox conditions. PMID:22136137

Ilgen, Anastasia G; Trainor, Thomas P

2011-12-21

394

Sb(III) and Sb(V) Sorption onto Al-Rich Phases: Hydrous Al Oxide and the Clay Minerals Kaolinite KGa-1b and Oxidized and Reduced Nontronite NAu-1  

SciTech Connect

We have studied the immobilization of Sb(III) and Sb(V) by Al-rich phases - hydrous Al oxide (HAO), kaolinite (KGa-1b), and oxidized and reduced nontronite (NAu-1) - using batch experiments to determine the uptake capacity and the kinetics of adsorption and Extended X-ray Absorption Fine Structure (EXAFS) Spectroscopy to characterize the molecular environment of adsorbed Sb. Both Sb(III) and Sb(V) are adsorbed in an inner-sphere mode on the surfaces of the studied substrates. The observed adsorption geometry is mostly bidentate corner-sharing, with some monodentate complexes. The kinetics of adsorption is relatively slow (on the order of days), and equilibrium adsorption isotherms are best fit using the Freundlich model. The oxidation state of the structural Fe within nontronite affects the adsorption capacity: if the clay is reduced, the adsorption capacity of Sb(III) is slightly decreased, while Sb(V) uptake is increased significantly. This may be a result of the presence of dissolved Fe(II) in the reduced nontronite suspensions or associated with the structural rearrangements in nontronite due to reduction. These research findings indicate that Sb can be effectively immobilized by Al-rich phases. The increase in Sb(V) uptake in response to reducing structural Fe in clay can be important in natural settings since Fe-rich clays commonly go through oxidation-reduction cycles in response to changing redox conditions.

Ilgen, Anastasia G.; Trainor, Thomas P. (Alaska Fairbanks)

2012-11-13

395

Minerals yearbook, 1991: Massachusetts. Annual report  

SciTech Connect

The value of nonfuel mineral production in 1991 was $111.6 million, a decrease of $16 million compared with the 1990 value. The decrease in 1991 was largely attributable to lower sales of construction sand and gravel and crushed stone, the State's two leading mineral commodities. Other mineral commodities produced included common clay, industrial sand, dimension stone, lime, and peat. Nationally, the State ranked 41st in the production of nonfuel minerals. It ranked fifth of 34 States that produced dimension stone.

Harrison, D.K.; Sinnott, J.A.

1993-05-01

396

CEC-normalized clay-water sorption isotherm  

NASA Astrophysics Data System (ADS)

A normalized clay-water isotherm model based on BET theory and describing the sorption and desorption of the bound water in clays, sand-clay mixtures, and shales is presented. Clay-water sorption isotherms (sorption and desorption) of clayey materials are normalized by their cation exchange capacity (CEC) accounting for a correction factor depending on the type of counterion sorbed on the mineral surface in the so-called Stern layer. With such normalizations, all the data collapse into two master curves, one for sorption and one for desorption, independent of the clay mineralogy, crystallographic considerations, and bound cation type; therefore, neglecting the true heterogeneity of water sorption/desorption in smectite. The two master curves show the general hysteretic behavior of the capillary pressure curve at low relative humidity (below 70%). The model is validated against several data sets obtained from the literature comprising a broad range of clay types and clay mineralogies. The CEC values, derived by inverting the sorption/adsorption curves using a Markov chain Monte Carlo approach, are consistent with the CEC associated with the clay mineralogy.

Woodruff, W. F.; Revil, A.

2011-11-01

397

Sorption Charecterization of Radonuclides on Clays in Yucca Mountain Alluvium  

SciTech Connect

Sorption of {sup 237}Np(V) and {sup 233}U(VI) was measured on clays separated from Yucca Mountain alluvium as a function of solution pH and aqueous actinide concentrations. The results indicate that sorption of U and Np on the separated clay fraction depends strongly on solution pH. Np sorption on clays increases slowly with increasing pH from 3 to 7. Above pH 7, Np sorption on clays increases rapidly up to a pH of about 10. On the other hand, U sorption on clays reaches it maximum at a pH of about 6, with sorption decreasing as pH increases from 6 to 8 and then increasing again as pH increases further from 8 to about 10. The results suggest that a Freundlich isotherm can be used to describe U and Np sorption on clays at pH above 5.5. The results of this study indicate that clay minerals play a very important role in the sorption of U and Np on Yucca Mountain alluvium. Indeed, the clay content of the alluvium is probably considerably more important than water chemistry in predicting the ability of the alluvium to attenuate the transport of these radionuclides.

M. Ding; P.W. Reimus; S. Chipera; C. Scism

2006-03-17

398

The direct synthesis of organic-containing clays and thermal analysis of porphyrin-clay complexes  

SciTech Connect

Synthetic TMA-montmorillonites have now been made in conjunction with synthetic porphyrin-hectorites reported earlier. In order to help progress towards preparation of porphyrin-containing aluminosilicate clays, the thermal stability of porphyrin-clay systems has been examined in detail. Results from TGA and Py-GC-MS indicate that the porphyrin nucleus is extremely stable in the present of clay minerals. Substituents on the nucleus such as pyridinium or anilinium are, on the other hand, slightly destabilized. In addition, the presence of transition metals like Fe(III) in metalloporphyrins appears to catalyze decomposition of the porphyrin nucleus to some degree. The use of Py-GC-MS in conjunction with TGA results greatly clarified the assignment of weight loss peaks. 18 refs., 3 figs.

Carrado, K.A.; Anderson, K.B.; Grutkoski, P.S.

1991-01-01

399

Organophilic clay suspension medium  

SciTech Connect

This patent describes an improved liquid suspension medium for particulate solids. The suspension medium having been formed by admixing an organophilic clay wherein the clay is selected from the group consisting of bentonite, attapulgite, sepiolite and hectorite and admixtures thereof present in the quantity of about 0.5-8 weight percent with a liquid hydrocarbon present in the quantity of about 99-70 weight percent and at least one activator selected from the group consisting of phenyl hydroxyalkyl ethers.

Dixon, G.G.; Parlman, R.M.; Stewart, W.

1989-10-24

400

Weathering of olivine and pyroxene on Mars: Evidence from missions, meteorites, and terrestrial mineral analogs  

NASA Astrophysics Data System (ADS)

Mineral-water interactions modify primary minerals, produce new minerals as alteration products, and modify the solute loads of the solutions. Except for situations in which the solutions still coexist with reactant and product minerals, properties of the solutions (e.g., the abundances of various solutes; the duration of their contact with the minerals) must be inferred from the mineral assemblages left behind. Abundant literature exists on identifying and interpreting the paleoenvironmental significance of mineral products of such reactions on Mars (e.g., clay minerals and other phyllosilicates; sulfates; carbonates). Less literature exists on interpreting the paleoenvironmental significance of primary minerals and their properties in altered Mars materials. Since the arrival of the Mars Exploration Rovers in 2004 and the Phoenix Mars Lander in 2008, a number of new observations of primary-mineral destruction have been enabled by deployment of microscopic imagers on Mars and continued microscopic investigation of Mars meteorites in terrestrial laboratories. These include examples of alteration of both of the major minerals of Mars’ igneous rocks, olivine and pyroxene. Olivine alteration is indicated by selective removal of euhedral olivine from weathered rinds on basalt at Gusev crater, and elongate cavities of non-uniform width in olivine in the Mars meteorite Nakhla; the latter exhibit some similarities to and some differences from common arrays of corrosion pits on weathered terrestrial olivine. Pyroxene dissolution and corrosion are indicated by sharp pointed alteration features on clinopyroxene in the Mars meteorite Nakhla, scaly features on orthopyroxene at the orthopyroxene-carbonate interface in the Allan Hills 84001 Mars meteorite, and angular sawtooth features on soil grains from the Phoenix landing site, all of which are similar or identical to common corrosion textures on weathered terrestrial pyroxene and related chain-silicate minerals. Primary-mineral corrosion occurs in Mars meteorites of a range of alteration ages, from ~3.9 Ga (~ Mid-Noachian; orthopyroxene corrosion and associated carbonate formation in ALH 84001), through ~670 Ma (~ Mid-Late Amazonian; clinopyroxene corrosion and diverse alteration minerals in nakhlites), and possibly quite recently (Late Amazonian; pre-terrestrial carbonate and sulfate in the ~170 Ma-old shergottite EET 79001). Primary-mineral removal of indeterminate but possibly quite recent age is also recorded from Mars-surface microscopic imagery, including euhedral olivine molds in weathered rinds on basaltic boulders at Gusev crater and possible pyroxene corrosion in unconsolidated granular material at the Phoenix landing site, preserved despite possible physical transport and abrasion processes. These occurrences of primary-mineral modification and destruction record aqueous alteration processes over a broad range of times in the paleoenvironmental history of Mars’ surface.

Velbel, M. A.

2010-12-01