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Sample records for clay minerals

  1. Clay Minerals

    SciTech Connect

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

    2014-03-14

    Clay minerals are important components of the environment and are involved or implicated in processes such as the uptake of pollutants and the release of nutrients and as potential platforms for a number of chemical reactions. Owing to their small particle sizes (typically, on the order of microns or smaller) and mixing with a variety of other minerals and soil components, advanced characterization methods are needed to study their structures, dynamics, and reactivities. In this article, we describe the use of solid-state NMR methods to characterize the structures and chemistries of clay minerals. Early one-pulse magic-angle spinning (MAS) NMR studies of 27Al and 29Si have now been enhanced and extended with new studies utilizing advanced methodologies (such as Multiple Quantum MAS) as well as studies of less-sensitive nuclei. In additional work, the issue of reactivity of clay minerals has been addressed, including studies of reactive surface area in the environment. Utilizations of NMR-sensitive nuclides within the clay minerals themselves, and in molecules that react with specific sites on the clay mineral surfaces, have aided in understanding the reactivity of these complex aluminosilicate systems.

  2. Clay Mineral: Radiological Characterization

    NASA Astrophysics Data System (ADS)

    Cotomácio, J. G.; Silva, P. S. C.; Mazzilli, B. P.

    2008-08-01

    Since the early days, clays have been used for therapeutic purposes. Nowadays, most minerals applied as anti-inflammatory, pharmaceutics and cosmetic are the clay minerals that are used as the active ingredient or, as the excipient, in formulations. Although their large use, few information is available in literature on the content of the radionuclide concentrations of uranium and thorium natural series and 40K in these clay minerals. The objective of this work is to determine the concentrations of 238U, 232Th, 226Ra, 228Ra, 210Pb and 40K in commercial samples of clay minerals used for pharmaceutical or cosmetic purposes. Two kinds of clays samples were obtained in pharmacies, named green clay and white clay. Measurement for the determination of 238U and 232Th activity concentration was made by alpha spectrometry and gamma spectrometry was used for 226Ra, 228Ra, 210Pb and 40K determination. Some physical-chemical parameters were also determined as organic carbon and pH. The average activity concentration obtained was 906±340 Bq kg-1 for 40K, 40±9 Bq kg-1 for 226Ra, 75±9 Bq kg-1 for 228Ra, 197±38 Bq kg-1 for 210Pb, 51±26 Bq kg-1 for 238U and 55±24 Bq kg-1 for 232Th, considering both kinds of clay.

  3. Clay Minerals: Adsorbophysical Properties

    NASA Astrophysics Data System (ADS)

    Kotova, O.

    2013-12-01

    The structure and features of surfaces of clay minerals (kaolin, montmorillonite, etc) have an important scientific and practical value. On the surface the interrelation of processes at electronic, atomic and molecular levels is realized. Availability of mineral surface to external influences opens wide scientific and technical opportunities of use of the surface phenomena, so the research of crystal-chemical and crystal-physical processes in near-surface area of clay minerals is important. After long term researches of gas-clay mineral system in physical fields the author has obtained experimental and theoretical material contributing to the creation of the surface theory of clays. A part of the researches is dedicated to studying the mechanism of crystal-chemical and crystal-physical processes in near surface area of clay mineral systems, selectivity of the surface centers to interact with gas phase molecules and adsorbophysical properties. The study of physical and chemical properties of fine clay minerals and their modification has a decisive importance for development of theory and practice of nanotechnologies: they are sorbents, membranes, ceramics and other materials with required electronic features.

  4. Killer clays! Natural antibacterial clay minerals

    USGS Publications Warehouse

    Williams, L.B.; Holland, M.; Eberl, D.D.; Brunet, T.; De Courrsou, L. B.

    2004-01-01

    The clay chemical properties that may be important in medicine were investigated. It was found that natural clay minerals can have striking and very specific effects on microbial populations. The effects can range from potentially enhanced microbial growth to complete sterilization. This paper presents evidence that natural clay minerals can be effective antimicrobial agents.

  5. Clay Mineral: Radiological Characterization

    SciTech Connect

    Cotomacio, J. G.; Silva, P. S. C.; Mazzilli, B. P

    2008-08-07

    Since the early days, clays have been used for therapeutic purposes. Nowadays, most minerals applied as anti-inflammatory, pharmaceutics and cosmetic are the clay minerals that are used as the active ingredient or, as the excipient, in formulations. Although their large use, few information is available in literature on the content of the radionuclide concentrations of uranium and thorium natural series and {sup 40}K in these clay minerals.The objective of this work is to determine the concentrations of {sup 238}U, {sup 232}Th, {sup 226}Ra, {sup 228}Ra, {sup 210}Pb and {sup 40}K in commercial samples of clay minerals used for pharmaceutical or cosmetic purposes. Two kinds of clays samples were obtained in pharmacies, named green clay and white clay.Measurement for the determination of {sup 238}U and {sup 232}Th activity concentration was made by alpha spectrometry and gamma spectrometry was used for {sup 226}Ra, {sup 228}Ra, {sup 210}Pb and {sup 40}K determination. Some physical-chemical parameters were also determined as organic carbon and pH. The average activity concentration obtained was 906{+-}340 Bq kg{sup -1} for {sup 40}K, 40{+-}9 Bq kg{sup -1} for {sup 226}Ra, 75{+-}9 Bq kg{sup -1} for {sup 228}Ra, 197{+-}38 Bq kg{sup -1} for {sup 210}Pb, 51{+-}26 Bq kg{sup -1} for {sup 238}U and 55{+-}24 Bq kg{sup -1} for {sup 232}Th, considering both kinds of clay.

  6. Green Clay Minerals

    NASA Astrophysics Data System (ADS)

    Velde, B.

    2003-12-01

    Color is a problem for scientific study. One aspect is the vocabulary one used to describe color. Mint green, bottle green, and Kelly green are nice names but not of great utility in that people's physical perception of color is not always the same. In some industries, such as colored fabric manufacture, current use is to send a set of standard colors which are matched by the producer. This is similar to the use of the Munsell color charts in geology. None of these processes makes use of physical optical spectral studies. The reason is that they are difficult to obtain and interpret. For a geologist, color is very important but we rarely have the possibility to standardize the method of our color perception. One reason is that color is both a reflective and transmission phenomenon. The thickness of the sample is critical to any transmission characteristics. Hence, a field color determination is different from one made by using a petrographic microscope. Green glauconite in a hand specimen is not the same color in 30 μm thick thin section seen with a microscope using transmitted light.A second problem is that color in a spectral identification is the result of several absorption emissions,with overlapping signal, forming a complicated spectrum. Interpretation depends very greatly on the spectrum of the light source and the conditions of transmission-reflection of the sample. As a result, for this text, we will not attempt to analyze the physical aspect of green in green clays. In the discussion which follows, reference is made concerning color, to thin section microscopic perception.Very briefly, green clay minerals are green, because they contain iron. This is perhaps not a great revelation to mineralogists, but it is the key to understanding the origin and stability of green clay minerals. In fact, iron can color minerals either red or green or in various shades of orange and brown. The color most likely depends upon the relative abundance of the iron ion valence

  7. Clay Mineral Preferred Orientation

    NASA Astrophysics Data System (ADS)

    Day-Stirrat, R. J.

    2014-12-01

    Anisotropy of the orientation of clay minerals, often referred to as texture, may be unique to sediments' deposition, composition, deformation or diagenetic history. The literature is rich with studies that include preferred orientation generation in fault gouge, low-grade metamorphic rocks, sediments with variable clay content and during the smectite-to-illite transformation. Untangling the interplay between many competing factors in any one geologic situation has proven a significant challenge over many years. Understanding how, where and when clay minerals develop a preferred orientation has significant implications for permeability anisotropy in shallow burial, the way mechanical properties are projected from shallower to deeper settings in basin modeling packages and the way velocity anisotropy is accounted for in seismic data processing. The assessment of the anisotropic properties of fine-grained siliciclastic rocks is gaining significant momentum in rock physics research. Therefore, a fundamental understanding of how clay minerals develop a preferred orientation in space and time is crucial to the understanding of anisotropy of physical properties. The current study brings together a wealth of data that may be used in a predictive sense to account for fabric anisotropy that may impact any number of rock properties.

  8. Mineral resource of the Month: Clay

    USGS Publications Warehouse

    Virta, Robert L.

    2010-01-01

    Clays were one of the first mineral commodities used by people. Clay pottery has been found in archeological sites that are 12,000 years old, and clay figurines have been found in sites that are even older.

  9. Dehydration-induced luminescence in clay minerals

    NASA Technical Reports Server (NTRS)

    Coyne, L. M.; Lahav, N.; Lawless, J. G.

    1981-01-01

    Reports of triboluminescent phenomena in organic crystalline materials prompted a search for related processes in clay minerals. The reported extensive mechanical distortion produced on freezing and drying of montmorillonite was particularly interesting because of studies of condensation reactions in a wet/dry cycled reaction sequence. The discovery of an unusual luminescent process in several clay minerals is reported and its characteristics are described.

  10. Scanning electron microscopy of clays and clay minerals

    USGS Publications Warehouse

    Bohor, B.F.; Hughes, R.E.

    1971-01-01

    The scanning electron microscope (SEM) proves to be ideally suited for studying the configuration, texture, and fabric of clay samples. Growth mechanics of crystalline units-interpenetration and interlocking of crystallites, crystal habits, twinning, helical growth, and topotaxis-also are uniquely revealed by the SEM. Authigenic kaolins make up the bulk of the examples because their larger crystallite size, better crystallinity, and open texture make them more suited to examination by the SEM than most other clay mineral types. ?? 1971.

  11. Desert varnish: the importance of clay minerals.

    PubMed

    Potter, R M; Rossman, G R

    1977-06-24

    Desert varnish has been characterized by infrared spectroscopy, x-ray diffraction, and electron microscopy. It is a distinct morphological entity having an abrupt boundary with the underlying rock. Clay minerals comprise more than 70 percent of the varnish. Iron and manganese oxides constitute the bulk of the remainder and are dispersed throughout the clay layer. PMID:17776923

  12. Desert varnish: the importance of clay minerals.

    PubMed

    Potter, R M; Rossman, G R

    1977-06-24

    Desert varnish has been characterized by infrared spectroscopy, x-ray diffraction, and electron microscopy. It is a distinct morphological entity having an abrupt boundary with the underlying rock. Clay minerals comprise more than 70 percent of the varnish. Iron and manganese oxides constitute the bulk of the remainder and are dispersed throughout the clay layer.

  13. Ostwald ripening of clays and metamorphic minerals

    USGS Publications Warehouse

    Eberl, D.D.; Srodon, J.; Kralik, M.; Taylor, B.E.; Peterman, Z.E.

    1990-01-01

    Analyses of particle size distributions indicate that clay minerals and other diagenetic and metamorphic minerals commonly undergo recrystallization by Ostwald ripening. The shapes of their particle size distributions can yield the rate law for this process. One consequence of Ostwald ripening is that a record of the recrystallization process is preserved in the various particle sizes. Therefore, one can determine the detailed geologic history of clays and other recrystallized minerals by separating, from a single sample, the various particle sizes for independent chemical, structural, and isotopic analyses.

  14. Clays and other minerals in prebiotic processes

    NASA Technical Reports Server (NTRS)

    Paecht-Horowitz, M.

    1984-01-01

    Clays and other minerals have been investigated in context with prebiotic processes, mainly in polymerization of amino acids. It was found that peptides adsorbed on the clay, prior to polymerization, influence the reaction. The ratio between the amount of the peptides adsorbed and that of the clay is important for the yield as well as for the degrees of polymerization obtained. Adsorption prior to reaction produces a certain order in the aggregates of the clay particles which might induce better reaction results. Excess of added peptides disturbs this order and causes lesser degrees of polymerization. In addition to adsorption, clays are also able to occlude between their layers substances out of the environment, up to very high concentrations.

  15. Mineral Acquisition from Clay by Budongo Forest Chimpanzees

    PubMed Central

    Reynolds, Vernon; Lloyd, Andrew W.; English, Christopher J.; Lyons, Peter; Dodd, Howard; Hobaiter, Catherine; Newton-Fisher, Nicholas; Mullins, Caroline; Lamon, Noemie; Schel, Anne Marijke; Fallon, Brittany

    2015-01-01

    Chimpanzees of the Sonso community, Budongo Forest, Uganda were observed eating clay and drinking clay-water from waterholes. We show that clay, clay-rich water, and clay obtained with leaf sponges, provide a range of minerals in different concentrations. The presence of aluminium in the clay consumed indicates that it takes the form of kaolinite. We discuss the contribution of clay geophagy to the mineral intake of the Sonso chimpanzees and show that clay eaten using leaf sponges is particularly rich in minerals. We show that termite mound soil, also regularly consumed, is rich in minerals. We discuss the frequency of clay and termite soil geophagy in the context of the disappearance from Budongo Forest of a formerly rich source of minerals, the decaying pith of Raphia farinifera palms. PMID:26218593

  16. Mineral Acquisition from Clay by Budongo Forest Chimpanzees.

    PubMed

    Reynolds, Vernon; Lloyd, Andrew W; English, Christopher J; Lyons, Peter; Dodd, Howard; Hobaiter, Catherine; Newton-Fisher, Nicholas; Mullins, Caroline; Lamon, Noemie; Schel, Anne Marijke; Fallon, Brittany

    2015-01-01

    Chimpanzees of the Sonso community, Budongo Forest, Uganda were observed eating clay and drinking clay-water from waterholes. We show that clay, clay-rich water, and clay obtained with leaf sponges, provide a range of minerals in different concentrations. The presence of aluminium in the clay consumed indicates that it takes the form of kaolinite. We discuss the contribution of clay geophagy to the mineral intake of the Sonso chimpanzees and show that clay eaten using leaf sponges is particularly rich in minerals. We show that termite mound soil, also regularly consumed, is rich in minerals. We discuss the frequency of clay and termite soil geophagy in the context of the disappearance from Budongo Forest of a formerly rich source of minerals, the decaying pith of Raphia farinifera palms.

  17. Clay mineral type effect on bacterial enteropathogen survival in soil.

    PubMed

    Brennan, Fiona P; Moynihan, Emma; Griffiths, Bryan S; Hillier, Stephen; Owen, Jason; Pendlowski, Helen; Avery, Lisa M

    2014-01-15

    Enteropathogens released into the environment can represent a serious risk to public health. Soil clay content has long been known to have an important effect on enteropathogen survival in soil, generally enhancing survival. However, clay mineral composition in soils varies, and different clay minerals have specific physiochemical properties that would be expected to impact differentially on survival. This work investigated the effect of clay materials, with a predominance of a particular mineral type (montmorillonite, kaolinite, or illite), on the survival in soil microcosms over 96 days of Listeria monocytogenes, Salmonella Dublin, and Escherichia coli O157. Clay mineral addition was found to alter a number of physicochemical parameters in soil, including cation exchange capacity and surface area, and this was specific to the mineral type. Clay mineral addition enhanced enteropathogen survival in soil. The type of clay mineral was found to differentially affect enteropathogen survival and the effect was enteropathogen-specific.

  18. Feasibility of classification of clay minerals by using PAS

    NASA Astrophysics Data System (ADS)

    Honda, Y.; Yoshida, Y.; Akiyama, Y.; Nishijima, S.

    2015-06-01

    After the nuclear power plant disaster, the evaluation of radioactive Cs kept in soil, especially in clay minerals and the elucidation of its movement are urgent subjects to promote decontamination. It is known that the extractable level of Cs depends on the sort of clay minerals. We tried to find the characteristics of clay minerals belonging to phillosilicate group using positron annihilation spectroscopy (PAS) and the relationship between the results of PAS and the amounts of substantially extracted Cs from the clay minerals. The results showed that each clay mineral was found to be distinguishable from other clay minerals by PAS and the extraction rate of Cs was different among those clay minerals, however the direct correlation between the results of PAS and the extraction rates of Cs was not found.

  19. Prolonged triboluminescence in clays and other minerals

    NASA Technical Reports Server (NTRS)

    Lahav, N.; Coyne, L. M.; Lawless, J. G.

    1982-01-01

    Samples of various clays and minerals were ground or fractured and monitored with a liquid scintillation spectrometer in order to obtain triboluminescent decay curves. Kaolinite samples displayed several million counts/min after grinding, with a surface area emission estimated at tens of billions of photons/sq cm of surface. The photon production rates varied with the origin of the sample, and kaolinite continually yielded higher production rates than bentonite. The addition of water to the samples slightly increased the count rate of emitted light, while the addition of the fluorescent molecule substance tryptofan significantly enhanced the count rate. Freezing smears of kaolinite and montmorillonite in liquid nitrogen and in a salt ice mixture also induced triboluminescence in the montmorillonite. A possible connection between powdery triboluminescent materials formed in mining industries and respiratory disorders among miners is suggested.

  20. Optimization method for quantitative calculation of clay minerals in soil

    NASA Astrophysics Data System (ADS)

    Hao, Libo; Wei, Qiaoqiao; Zhao, Yuyan; Lu, Jilong; Zhao, Xinyun

    2015-04-01

    Determination of types and amounts for clay minerals in soil are important in environmental, agricultural, and geological investigations. Many reliable methods have been established to identify clay mineral types. However, no reliable method for quantitative analysis of clay minerals has been established so far. In this study, an attempt was made to propose an optimization method for the quantitative determination of clay minerals in soil based on bulk chemical composition data. The fundamental principles and processes of the calculation are elucidated. Some samples were used for reliability verification of the method and the results prove the simplicity and efficacy of the approach.

  1. Recent advances in clay mineral-containing nanocomposite hydrogels.

    PubMed

    Zhao, Li Zhi; Zhou, Chun Hui; Wang, Jing; Tong, Dong Shen; Yu, Wei Hua; Wang, Hao

    2015-12-28

    Clay mineral-containing nanocomposite hydrogels have been proven to have exceptional composition, properties, and applications, and consequently have attracted a significant amount of research effort over the past few years. The objective of this paper is to summarize and evaluate scientific advances in clay mineral-containing nanocomposite hydrogels in terms of their specific preparation, formation mechanisms, properties, and applications, and to identify the prevailing challenges and future directions in the field. The state-of-the-art of existing technologies and insights into the exfoliation of layered clay minerals, in particular montmorillonite and LAPONITE®, are discussed first. The formation and structural characteristics of polymer/clay nanocomposite hydrogels made from in situ free radical polymerization, supramolecular assembly, and freezing-thawing cycles are then examined. Studies indicate that additional hydrogen bonding, electrostatic interactions, coordination bonds, hydrophobic interaction, and even covalent bonds could occur between the clay mineral nanoplatelets and polymer chains, thereby leading to the formation of unique three-dimensional networks. Accordingly, the hydrogels exhibit exceptional optical and mechanical properties, swelling-deswelling behavior, and stimuli-responsiveness, reflecting the remarkable effects of clay minerals. With the pivotal roles of clay minerals in clay mineral-containing nanocomposite hydrogels, the nanocomposite hydrogels possess great potential as superabsorbents, drug vehicles, tissue scaffolds, wound dressing, and biosensors. Future studies should lay emphasis on the formation mechanisms with in-depth insights into interfacial interactions, the tactical functionalization of clay minerals and polymers for desired properties, and expanding of their applications. PMID:26435008

  2. Recent advances in clay mineral-containing nanocomposite hydrogels.

    PubMed

    Zhao, Li Zhi; Zhou, Chun Hui; Wang, Jing; Tong, Dong Shen; Yu, Wei Hua; Wang, Hao

    2015-12-28

    Clay mineral-containing nanocomposite hydrogels have been proven to have exceptional composition, properties, and applications, and consequently have attracted a significant amount of research effort over the past few years. The objective of this paper is to summarize and evaluate scientific advances in clay mineral-containing nanocomposite hydrogels in terms of their specific preparation, formation mechanisms, properties, and applications, and to identify the prevailing challenges and future directions in the field. The state-of-the-art of existing technologies and insights into the exfoliation of layered clay minerals, in particular montmorillonite and LAPONITE®, are discussed first. The formation and structural characteristics of polymer/clay nanocomposite hydrogels made from in situ free radical polymerization, supramolecular assembly, and freezing-thawing cycles are then examined. Studies indicate that additional hydrogen bonding, electrostatic interactions, coordination bonds, hydrophobic interaction, and even covalent bonds could occur between the clay mineral nanoplatelets and polymer chains, thereby leading to the formation of unique three-dimensional networks. Accordingly, the hydrogels exhibit exceptional optical and mechanical properties, swelling-deswelling behavior, and stimuli-responsiveness, reflecting the remarkable effects of clay minerals. With the pivotal roles of clay minerals in clay mineral-containing nanocomposite hydrogels, the nanocomposite hydrogels possess great potential as superabsorbents, drug vehicles, tissue scaffolds, wound dressing, and biosensors. Future studies should lay emphasis on the formation mechanisms with in-depth insights into interfacial interactions, the tactical functionalization of clay minerals and polymers for desired properties, and expanding of their applications.

  3. Late Precambrian oxygenation; inception of the clay mineral factory.

    PubMed

    Kennedy, Martin; Droser, Mary; Mayer, Lawrence M; Pevear, David; Mrofka, David

    2006-03-10

    An enigmatic stepwise increase in oxygen in the late Precambrian is widely considered a prerequisite for the expansion of animal life. Accumulation of oxygen requires organic matter burial in sediments, which is largely controlled by the sheltering or preservational effects of detrital clay minerals in modern marine continental margin depocenters. Here, we show mineralogical and geochemical evidence for an increase in clay mineral deposition in the Neoproterozoic that immediately predated the first metazoans. Today most clay minerals originate in biologically active soils, so initial expansion of a primitive land biota would greatly enhance production of pedogenic clay minerals (the "clay mineral factory"), leading to increased marine burial of organic carbon via mineral surface preservation.

  4. Desorption of ciprofloxacin from clay mineral surfaces.

    PubMed

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

    2013-01-01

    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

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

    PubMed

    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

    2013-03-01

    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.

  6. [Mechanism of tritium persistence in porous media like clay minerals].

    PubMed

    Wu, Dong-Jie; Wang, Jin-Sheng; Teng, Yan-Guo; Zhang, Ke-Ni

    2011-03-01

    To investigate the mechanisms of tritium persistence in clay minerals, three types of clay soils (montmorillonite, kaolinite and illite) and tritiated water were used in this study to conduct the tritium sorption tests and the other related tests. Firstly, the ingredients, metal elements and heat properties of clay minerals were studied with some instrumental analysis methods, such as ICP and TG. Secondly, with a specially designed fractionation and condensation experiment, the adsorbed water, the interlayer water and the structural water in the clay minerals separated from the tritium sorption tests were fractionated for investigating the tritium distributions in the different types of adsorptive waters. Thirdly, the location and configuration of tritium adsorbed into the structure of clay minerals were studied with infrared spectrometry (IR) tests. And finally, the forces and mechanisms for driving tritium into the clay minerals were analyzed on the basis of the isotope effect of tritium and the above tests. Following conclusions have been reached: (1) The main reason for tritium persistence in clay minerals is the entrance of tritium into the adsorbed water, the interlayer water and the structural water in clay minerals. The percentage of tritium distributed in these three types of adsorptive water are in the range of 13.65% - 38.71%, 0.32% - 5.96%, 1.28% - 4.37% of the total tritium used in the corresponding test, respectively. The percentages are different for different types of clay minerals. (2) Tritium adsorbed onto clay minerals are existed in the forms of the tritiated hydroxyl radical (OT) and the tritiated water molecule (HTO). Tritium mainly exists in tritiated water molecule for adsorbed water and interlayer water, and in tritiated hydroxyl radical for structural water. (3) The forces and effects driving tritium into the clay minerals may include molecular dispersion, electric charge sorption, isotope exchange and tritium isotope effect.

  7. The effect of clay minerals on diasterane/sterane ratios

    NASA Astrophysics Data System (ADS)

    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

    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.

  8. Impact-Induced Clay Mineral Formation and Distribution on Mars

    NASA Technical Reports Server (NTRS)

    Rivera-Valentin, E. G.; Craig, P. I.

    2015-01-01

    Clay minerals have been identified in the central peaks and ejecta blankets of impact craters on Mars. Several studies have suggested these clay minerals formed as a result of impact induced hydrothermalism either during Mars' Noachian era or more recently by the melting of subsurface ice. Examples of post-impact clay formation is found in several locations on Earth such as the Mjolnir and Woodleigh Impact Structures. Additionally, a recent study has suggested the clay minerals observed on Ceres are the result of impact-induced hydrothermal processes. Such processes may have occurred on Mars, possibly during the Noachian. Distinguishing between clay minerals formed preor post-impact can be accomplished by studying their IR spectra. In fact, showed that the IR spectra of clay minerals is greatly affected at longer wavelengths (i.e. mid-IR, 5-25 micron) by impact-induced shock deformation while the near-IR spectra (1.0-2.5 micron) remains relatively unchanged. This explains the discrepancy between NIR and MIR observations of clay minerals in martian impact craters noted. Thus, it allows us to determine whether a clay mineral formed from impact-induced hydrothermalism or were pre-existing and were altered by the impact. Here we study the role of impacts on the formation and distribution of clay minerals on Mars via a fully 3-D Monte Carlo cratering model, including impact- melt production using results from modern hydrocode simulations. We identify regions that are conducive to clay formation and the location of clay minerals post-bombardment.

  9. Clay mineral formation and transformation in rocks and soils

    USGS Publications Warehouse

    Eberl, D.D.

    1983-01-01

    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.

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

    USGS Publications Warehouse

    Colman, Steven M.

    1982-01-01

    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.

  11. Elastic properties of dry clay mineral aggregates, suspensions and sandstones

    NASA Astrophysics Data System (ADS)

    Vanorio, Tiziana; Prasad, Manika; Nur, Amos

    2003-10-01

    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 (μs) 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 μs= 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.

  12. Toxicological evaluation of clay minerals and derived nanocomposites: a review.

    PubMed

    Maisanaba, Sara; Pichardo, Silvia; Puerto, María; Gutiérrez-Praena, Daniel; Cameán, Ana M; Jos, Angeles

    2015-04-01

    Clays and clay minerals are widely used in many facets of our society. This review addresses the main clays of each phyllosilicate groups, namely, kaolinite, montmorillonite (Mt) and sepiolite, placing special emphasis on Mt and kaolinite, which are the clays that are more frequently used in food packaging, one of the applications that are currently exhibiting higher development. The improvements in the composite materials obtained from clays and polymeric matrices are remarkable and well known, but the potential toxicological effects of unmodified or modified clay minerals and derived nanocomposites are currently being investigated with increased interest. In this sense, this work focused on a review of the published reports related to the analysis of the toxicological profile of commercial and novel modified clays and derived nanocomposites. An exhaustive review of the main in vitro and in vivo toxicological studies, antimicrobial activity assessments, and the human and environmental impacts of clays and derived nanocomposites was performed. From the analysis of the scientific literature different conclusions can be derived. Thus, in vitro studies suggest that clays in general induce cytotoxicity (with dependence on the clay, concentration, experimental system, etc.) with different underlying mechanisms such as necrosis/apoptosis, oxidative stress or genotoxicity. However, most of in vivo experiments performed in rodents showed no clear evidences of systemic toxicity even at doses of 5000mg/kg. Regarding to humans, pulmonary exposure is the most frequent, and although clays are usually mixed with other minerals, they have been reported to induce pneumoconiosis per se. Oral exposure is also common both intentionally and unintentionally. Although they do not show a high toxicity through this pathway, toxic effects could be induced due to the increased or reduced exposure to mineral elements. Finally, there are few studies about the effects of clay minerals on

  13. Sources and sinks of clay minerals on Mars

    NASA Astrophysics Data System (ADS)

    Milliken, Ralph E.; Bish, David L.

    2010-06-01

    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.

  14. Clays and clay minerals in Bikaner: Sources, environment pollution and management

    NASA Astrophysics Data System (ADS)

    Gayatri, Sharma; Anu, Sharma

    2016-05-01

    Environmental pollution can also be caused by minerals which include natural as well as human activities. Rapid urbanization, consumerist life style, anthropogenic deeds are increasing environmental pollution day by day. Fluctuation in our ecosystem or polluted environment leads to many diseases and shows adverse effects on living organisms. The main aim of this paper is to highlight the environmental pollution from clays and clay minerals and their mitigation..

  15. Layer Charge of Clay Minerals; Selected papers from the Symposium on Current Knowledge on the Layer Charge of Clay Minerals

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This Special issue contains papers based on the contributions presented during the workshop “Current Knowledge on the Layer Charge of Clay Minerals”, held on September 18 and 19, 2004, in the Smolenice Castle, Slovakia. Layer charge is one of the most important characteristics of clay minerals as it...

  16. Differentiation of pleistocene deposits in northeastern Kansas by clay minerals

    USGS Publications Warehouse

    Tien, P.-L.

    1968-01-01

    Seventy-four samples from eight stratigraphic sections of lower Pleistocene glacial and glaciofluvial deposits in Doniphan County, extreme northeastern Kansas, were analyzed using X-ray diffraction techniques. Clay-mineral assemblages of the <2 ?? fraction of these deposits are nearly identical, consisting of a mixed-layer clay mineral associated with minor amounts of kaolinite and illite. An attempt was made to differentiate units of till and nontill deposits by using the relative intensities of 001 reflections of "mixed-layer mineral," kaolinite, and illite. At least two tills were recognizable. Associated nontill deposits, could not be differentiated from one another, although the nontills are easily distinguished from tills. ?? 1968.

  17. Adsorption coefficients for TNT on soil and clay minerals

    NASA Astrophysics Data System (ADS)

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

    2007-04-01

    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 hydrometer method the particle size distribution for the soil horizons was obtained. Physical and chemical characterization studies such as cation exchange capacity (CEC), surface area, percent of organic matter and pH were performed for the soil and clay samples. A complete mineralogical characterization of clay fractions using X-ray diffraction analysis reveals the presence of kaolinite, goethite, hematite, gibbsite and quartz. In order to obtain adsorption coefficients (K d values) for the TNT-soil and TNT-clay interactions high performance liquid chromatography (HPLC) was used. The adsorption process for TNT-soil was described by the Langmuir model. A higher adsorption was observed in the Ap horizon. The Freundlich model described the adsorption process for TNT-clay interactions. The affinity and relative adsorption capacity of the clay for TNT were higher in the A horizon. These results suggest that adsorption by soil organic matter predominates over adsorption on clay minerals when significant soil organic matter content is present. It was found that, properties like cation exchange capacity and surface area are important factors in the adsorption of clayey soils.

  18. Microbial Impacts on Clay Mineral Transformation and Reactivity

    NASA Astrophysics Data System (ADS)

    Dong, H.; Jaisi, D.; Fredrickson, J.; Plymale, A.

    2006-05-01

    Clays and clay minerals are ubiquitous in soils, sedimentary rocks, and pelagic oozes. They play important roles in environmental processes such as nutrient cycling, plant growth, contaminant migration, organic matter maturation, and petroleum production. Iron is a major constituent in clay minerals, and its mobility and stability in different environmental processes is, in part, controlled by the oxidation state. Recent studies have shown that biological reduction of structural Fe(III) in clay minerals can change the physical and chemical properties of clay minerals, such as swelling, cation exchange and fixation capacity, specific surface area, color, and magnetic exchange interactions. As a result of biological reduction of Fe(III), clay minerals also undergo mineral transformations, such as dissolution of smectite and precipitation of illite, siderite and vivianite. These chemical, structural and mineralogical changes of clay minerals have a profound effect on clay mineral reactivity, such as their reactivity with organic and inorganic (i.e., heavy metals and radionuclides) contaminants. Our latest data show that biologically reduced nontronite (a smectite variety) is much more effective in reducing soluble and mobile Tc(VII) to Tc(IV) than unreduced nontronite. The reduced Tc(IV) is insoluble in groundwater and soil and thus is immobile. Biologically reduced nontronite can be prepared by microbially reducing Fe(III) in nontronite by Shewanella putrefaciens in the absence of oxygen. Approximately 30% of structurally Fe(III) can be reduced in this manner. Biogenic Fe(II) can then serve as an electron donor to reduce Tc(VII). Nearly all Fe(II) is available to reduce Tc(VII), with the rate of reduction (typically within weeks) possibly depending on the speciation of Fe(II) (surface sorbed Fe(II) vs. structural Fe(II)). Further investigations are underway to further assess the reversibility of Tc reduction upon exposure to oxygen and to elucidate Tc reduction

  19. Black Carbon, The Pyrogenic Clay Mineral?

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Most soils contain significant amounts of black carbon, much of which is present as discrete particles admixed with the coarse clay fraction (0.2–2.0 µm e.s.d.) and can be physically separated from the more abundant diffuse biogenic humic materials. Recent evidence has shown that naturally occurring...

  20. Intercalation of trichloroethene by sediment-associated clay minerals.

    PubMed

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

    2013-01-01

    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.

  1. INTERCALATION OF TRICHLOROETHENE BY SEDIMENT-ASSOCIATED CLAY MINERALS

    PubMed Central

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

    2012-01-01

    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

  2. Intercalation of Trichloroethene by Sediment-Associated Clay Minerals

    SciTech Connect

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

    2013-01-01

    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.

  3. Clay minerals in a denudation-accumulative soil catena

    NASA Astrophysics Data System (ADS)

    Chizhikova, N. P.; Sorokina, N. P.; Khitrov, N. B.; Samsonova, A. A.

    2010-01-01

    Chernozems and agrochernozems of the Kamennaya Steppe agroforest landscape have a silty clay or clay texture and similar associations of clay minerals. The plow horizons of the agrochernozems on a slope of 2°-3° to the Talovaya Balka have an increased content of the smectite phase (50-70%) compared to the upper horizons of the chernozems on flat watersheds (30-50%) due to the lithological discontinuity of the soil-forming material and the possible total removal of material on the slope by denudation. On slightly eroded areas, the clay minerals display a more intense disturbance of their crystal lattice structures by pedogenetic processes, which increase the degree of disorder in their layers and the accumulation of fine quartz in the clay fraction. In the areas with more significant erosion of the humus horizon, the clay minerals are characterized by their perfect structure and clean reflections, which are indicative of the outcropping of less weathered material from the middle part of the chernozem profile less transformed by pedogenesis.

  4. Fluoride content of clay minerals and argillaceous earth materials

    USGS Publications Warehouse

    Thomas, J.; Glass, H.D.; White, W.A.; Trandel, R.M.

    1977-01-01

    A reliable method, utilizing a fluoride ion-selective electrode, is described for the determination of fluoride in clays and shales. Interference by aluminum and iron is minimal. The reproducibility of the method is about ??5% 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. Fluoride values range from 44 ppm (0.0044%) for nontronite from Colfax, WA, to 51,800 ppm (5.18%) for hectorite from Hector, CA. In general, clays formed under hydrothermal conditions are relatively high in fluoride content, provided the hydrothermal waters are high in fluoride content. Besides hectorite, dickite from Ouray, CO, was found to contain more than 50 times as much fluoride (6700 ppm) as highly crystalline geode kaolinite (125 ppm). The clay stratum immediately overlying a fluorite mineralized zone in southern Illinois was found to have a higher fluoride content than the same stratum in a nonmineralized zone approximately 1 mile away. Nonmarine shales in contact with Australian coals were found to be lower in fluoride content than were marine shales in contact with Illinois coals. It is believed that, in certain instances, peak shifts on DTA curves of similar clay minerals are the result of significant differences in their fluoride content. ?? 1977.

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

    SciTech Connect

    Randall T. Cygan

    2007-06-01

    “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.

  6. Immersion Freezing of Clay Minerals and its Time Dependence

    NASA Astrophysics Data System (ADS)

    Hiranuma, N.; Moehler, O.; Bundke, U.; Cziczo, D. J.; Danielczok, A.; Ebert, M.; Garimella, S.; Hoffmann, N.; Kanji, Z. A.; Kiselev, A. A.; Raddatz, M.; Stetzer, O.

    2012-12-01

    Immersion ice nucleation efficiency of clay minerals has been investigated using the AIDA (Aerosol Interaction and Dynamics in the Atmosphere) cloud chamber. Various clay dust samples, including two illite as well as three kaolinite standards, have been examined in the temperature range between 238 K and 255 K. We observed two trends in immersion ice nucleation properties as cloud expansion conditions in the AIDA are varied. First, as previously described in the literature, the supersaturation required for the immersion freezing of clay minerals decreased with decreasing temperature and increasing inferred ice-active surface site densities. Second, the ice nucleation activity of clay minerals strongly depended on the solo-parameter, which is the rate change in temperature (i.e., dNice/dT = ∂Nice/∂t ÷ ∂T/∂t). Further time dependence of ice formation is investigated and discussed as a function of cooling rates, ice nuclei (IN), and aerosol concentrations. Ice residuals collected through a pumped counterflow virtual impactor are examined by electron microprobe analyses to seek the true chemical and physical identity of IN in clay minerals. Brief comparisons of AIDA measurement to the measurements with other ice nucleation chambers (e.g., ETH-PINC, FINCH, and commercially available DMT-SPIN) are also presented.

  7. First Direct Detection of Clay Minerals on Mars

    NASA Technical Reports Server (NTRS)

    Singer, R. B.; Owensby, P. D.; Clark, R. N.

    1985-01-01

    Magnesian clays or clay-type minerals were conclusively detected in the martian regolith. Near-IR spectral observations of Mars using the Mauna Kea 2.2-m telescope show weak but definite absorption bands near microns. The absorption band positions and widths match those produced by combined OH stretch and Mg-OH lattice modes and are diagnostic of minerals with structural OH such as clays and amphiboles. Likely candidate minerals include serpentine, talc, hectorite, and sponite. There is no spectral evidence for aluminous hydroxylated minerals. No distinct band occurs at 2.55 microns, as would be expected if carbonates were responsible for the 2.35 micron absorption. High-albedo regions such as Elysium and Utopia have the strongest bands near 2.35 microns, as would be expected for heavily weathered soils. Low-albedo regions such as Iapygia show weaker but distinct bands, consistent with moderate coatings, streaks, and splotches of bright weathered material. In all areas observed, the 2.35-micron absorption is at least three times weaker than would be expected if well-crystallized clay minerals made up the bulk of bright soils on Mars.

  8. Heteroaggregation of Silver Nanoparticles with Clay Minerals in Aqueous System

    NASA Astrophysics Data System (ADS)

    Liu, J.; Burrow, E.; Hwang, Y.; Lenhart, J.

    2013-12-01

    Nanoparticles are increasingly being used in industrial processes and consumer products that exploit their beneficial properties and improve our daily lives. Nevertheless, they also attract attention when released into natural environment due to their potential for causing adverse effects. The fate and transport of nanoparticles in aqueous systems have been the focus of intense study. However, their interactions with other natural particles have received only limited attention. Clay minerals are ubiquitous in most aquatic systems and their variably charged surfaces can act as deposition sites that can alter the fate and transport of nanoparticles in natural aqueous environments. In this study, we investigated the homoaggregation of silver nanoparticles with different coating layers and their heteroaggregation behavior with clay minerals (illite, kaolinite, montmorillonite) in neutral pH solutions. Silver nanoparticles with a nominal diameter of 80 nm were synthesized with three different surface coating layers: uncoated, citrate-coated and Tween-coated. Illite (IMt-2), kaolinite (KGa-2), and montmorillonite (SWy-2) were purchased from the Clay Mineral Society (Indiana) and pretreated to obtain monocationic (Na-clay) and dicationic (Ca-clay) suspensions before the experiments. The change in hydrodynamic diameter as a function of time was monitored using dynamic light scattering (DLS) measurements in order to evaluate early stage aggregation as a function of electrolyte concentration in both the homo- and heteroaggregation scenarios. A shift in the critical coagulation concentration (CCC) values to lower electrolyte concentrations was observed in binary systems, compared to single silver nanoparticle and clay systems. The results also suggest more rapid aggregation in binary system during the early aggregation stage when compared to the single-particle systems. The behavior of citrate-coated silver nanoparticles was similar to that of the bare particles, while the

  9. [Occurrence relationship between iron minerals and clay minerals in net-like red soils: evidence from X-ray diffraction].

    PubMed

    Yin, Ke; Hong, Han-Lie; Han, Weni; Ma, Yu-Bo; Li, Rong-Biao

    2013-04-01

    The high purity of clay minerals is a key factor to reconstruct the palaeoclimate in clay mineralogy, however, the existence of iron minerals (such as goethite and hematite) and organics lead to the intergrowth of clay minerals and other minerals, producing other mineral impurities in enriched clay minerals. Although the removal of organics in soil sediments has been fully investigated, the occurrence state of iron minerals remains controversial, hindering the preparation of high-purity clay minerals. Therefore, the occurrence relationship of iron minerals and clay minerals in Jiujiang net-like red soils of the middle to lower reaches of the Yangtze River was investigated using the sequential separation method, which provided some implications for the removal of iron minerals in soil sediments. The results indicated that goethite and hematite were mostly absorbed on the surface of hydroxy-interlayered smectite and illite in the form of films, and the rest were absorbed by kaolinite.

  10. Fluxes of clay minerals in the South China Sea

    NASA Astrophysics Data System (ADS)

    Schroeder, Annette; Wiesner, Martin G.; Liu, Zhifei

    2015-11-01

    In order to assess dominant settling processes that change the composition of the detrital clay fraction during transport from neighboring estuaries to a deep sea basin, we studied relative clay mineral abundances and absolute clay mineral fluxes of clay-sized sinking particulate matter collected by eight sediment trap systems deployed from shallow to deep water depth in the South China Sea. This is the first basin-wide study on recent sedimentation processes in the western Pacific marginal seas. Annual averages of relative clay mineral abundances at the shallow traps are temporally more variable and regionally more diverse, resembling those of surrounding drainage basins. In contrast, higher fluxes of material reach the deeper traps. Their characteristics trend temporally and spatially towards uniformity and are enriched with smectite in the entire deep basin. Sinking particulate matter that reaches the shallow traps spends less time in pelagic transport and is affected by monsoonal current reversals. The enrichment in smectite in the deeper traps is a result of longer duration in transport at low velocities, which may increase the effect of differential settling during transport. The trend is caused by lateral advection driven by the cyclonic deep circulation, and this is considered as the main transport process in the northern and central deep basin. The high fluxes in the south-western deep basin could be the result of laterally advected re-suspended sediments from the neighboring shelves. The effects on the composition of the detrital clay fraction caused by oceanographic control, which indirectly include those by differential settling, mask the climatic signal from surrounding drainage basins in the deep basin sediments. This strongly affects the interpretation of the clay mineralogical record in sediments deposited under recent conditions in the South China Sea deep basin.

  11. 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...

  12. Reactivity of clay minerals with acids and alkalies

    USGS Publications Warehouse

    Carroll, D.; Starkey, H.C.

    1971-01-01

    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.

  13. Sorption of tylosin on clay minerals.

    PubMed

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

    2013-11-01

    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.

  14. Adsorption of diethyl phthalate ester to clay minerals.

    PubMed

    Wu, Yanhua; Si, Youbin; Zhou, Dongmei; Gao, Juan

    2015-01-01

    Phthalate esters are a group of plasticizers, which have been widely detected in China's agricultural and industrial soils. In this study, batch adsorption experiments were conducted to investigate the environmental effects on the adsorption of diethyl phthalate ester (DEP) to clay minerals. The results showed that DEP adsorption isotherms were well fitted with the Freundlich model; the interlayer spacing of K(+) saturated montmorillonite (K-mont) was the most important adsorption area for DEP, and di-n-butyl ester (DnBP) was limited to intercalate into the interlayer of K-mont due to the bigger molecular size; there was no significant effect of pH and ionic strength on DEP adsorption to K-mont/Ca-mont, but to Na-mont clay. The adsorption to kaolinite was very limited. Data of X-ray diffraction and FTIR spectra further proved that DEP molecules could intercalate into K-/Ca-mont interlayer, and might interact with clay through H-bonding between carbonyl groups and clay adsorbed water. Coated humic acid on clay surface would enhance DEP adsorption at low concentration, but not at high concentration (eg. Ce>0.26 mM). The calculated adsorption enthalpy (ΔHobs) and adsorption isotherms at varied temperatures showed that DEP could be adsorbed easier as more adsorbed. This study implied that clay type, compound structure, exchangeable cation, soil organic matter and temperature played important roles in phthalate ester's transport in soil.

  15. Ice nucleation efficiency of clay minerals in the immersion mode

    NASA Astrophysics Data System (ADS)

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

    2012-07-01

    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

  16. CO2 adsorption isotherm on clay minerals and the CO2 accessibility into the clay interlayer

    NASA Astrophysics Data System (ADS)

    Gensterblum, Yves; Bertier, Pieter; Busch, Andreas; Rother, Gernot; Krooß, Bernhard

    2013-04-01

    Large-scale CO2 storage in porous rock formations at 1-3 km depth is seen as a global warming mitigation strategy. In this process, CO2 is separated from the flue gas of coal or gas power plants, compressed, and pumped into porous subsurface reservoirs with overlying caprocks (seals). Good seals are mechanically and chemically stable caprocks with low porosity and permeability. They prevent leakage of buoyant CO2 from the reservoir. Caprocks are generally comprised of thick layers of shale, and thus mainly consist of clay minerals. These clays can be affected by CO2-induced processes, such as swelling or dissolution. The interactions of CO2 with clay minerals in shales are at present poorly understood. Sorption measurements in combination scattering techniques could provide fundamental insight into the mechanisms governing CO2-clay interaction. Volumetric sorption techniques have assessed the sorption of supercritical CO2 onto coal (Gensterblum et al., 2010; Gensterblum et al., 2009), porous silica (Rother et al., 2012a) and clays as a means of exploring the potential of large-scale storage of anthropogenic CO2 in geological reservoirs (Busch et al., 2008). On different clay minerals and shales, positive values of excess sorption were measured at gas pressures up to 6 MPa, where the interfacial fluid is assumed to be denser than the bulk fluid. However, zero and negative values were obtained at higher densities, which suggests the adsorbed fluid becomes equal to and eventually less dense than the corresponding bulk fluid, or that the clay minerals expand on CO2 charging. Using a combination of neutron diffraction and excess sorption measurements, we recently deduced the interlayer density of scCO2 in Na-montmorillonite clay in its single-layer hydration state (Rother et al., 2012b), and confirmed its low density, as well as the expansion of the basal spacings. We performed neutron diffraction experiments at the FRMII diffractometer on smectite, kaolinite and illite

  17. The Origin and Fate of Clay Minerals on Mars

    NASA Astrophysics Data System (ADS)

    Milliken, R.; Bish, D. L.; Hurowitz, J. A.; Fischer, W. W.

    2009-12-01

    The detection of clay minerals (phyllosilicates) in ancient Noachian-aged terrains on Mars and their relative paucity in younger Hesperian terrains has led to the hypothesis that the planet transitioned to a drier and more acidic environment. Converting a largely basaltic planet, which will naturally tend to buffer acidic solutions, to an acid-dominated system is dependent on competition between acid production and the available volume of water. Clay-bearing strata associated with deltas (e.g., Eberswalde, Jezero) and other fluvial features are strong evidence for sediment transport of previously altered basaltic material, whereas some clay-bearing units may represent neoformation of smectites and other clay minerals. In either of these cases, the presence of 2:1 clays suggests that water was present for fluvial transport and pH levels were moderate to alkaline. Interestingly, most of the clay deposits detected thus far host primarily Fe/Mg-rich 2:1 clay minerals, suggesting alteration of a basaltic crust at relatively low water-to-rock ratios (or short-lived water-rock interaction) and minimal leaching. With a few exceptions, large exposures of late-stage Al-rich weathering products such as kaolinite or gibbsite are rare. It has also recently been noted that the production of smectite via dissolution of basalt leads to an excess of cations that implies the formation of coeval sedimentary salts (carbonates, sulfates, chlorides, etc.). However, sulfates are found primarily in Hesperian terrains and such salts are rarely observed in older clay-bearing units. Coupled with in situ observations by rovers, the orbital detection of these younger sulfate deposits has been used to suggest that Mars transitioned to an acidic planet during the Hesperian. Acid can be produced on Mars by the oxidation of Fe(II) in fluids in contact with the atmosphere, where UV photons or atmospheric O2 are likely sources of oxidant. Such processes would occur throughout Mars’ history, but

  18. Reversibility of soil forming clay mineral reactions induced by plant - clay interactions

    NASA Astrophysics Data System (ADS)

    Barré, P.; Velde, B.

    2012-04-01

    Recent data based upon observations of field experiments and laboratory experiments suggest that changes in phyllosilicate mineralogy, as seen by X-ray diffraction analysis, which is induced by plant action can be reversed in relatively short periods of time. Changes from diagenetic or metamorphic mineral structures (illite and chlorite) to those found in soils (mixed layered minerals in the smectite, hydroxy-interlayer mineral and illites) observed in Delaware Bay salt marsh sediments in periods of tens of years and observed under different biologic (mycorhize) actions in coniferous forests in the soil environment can be found to be reversed under other natural conditions. Reversal of this process (chloritisation of smectitic minerals in soils) has been observed in natural situations over a period of just 14 years under sequoia gigantia. Formation of smectite minerals from illite (potassic mica-like minerals) has been observed to occur under intensive agriculture conditions over periods of 80 years or so under intensive zea mais production. Laboratory experiments using rye grass show that this same process can be accomplished to a somewhat lesser extent after one growing season. However experiments using alfalfa for 30 year growing periods show that much of the illite content of a soil can be reconstituted or even increased. Observations on experiments using zea mais under various fertilizer and mycorhize treatments indicate that within a single growing season potassium can be extracted from the clay (illite layers) but at the end of the season the potassium can be restored to the clay structures and more replaced that extracted. Hence it is clear that the change in clay mineralogy normally considered to be irreversible, illite to smectite or chlorite to smectite observed in soils, is a reversible process where plant systems control the soil chemistry and the soil mineralogy. The changes in clay mineralogy concern mostly the chemical composition of the interlayer

  19. Ice nucleation efficiency of clay minerals in the immersion mode

    NASA Astrophysics Data System (ADS)

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

    2012-01-01

    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. DSC (differential scanning calorimeter) measurements were performed on the kaolinites KGa-1b and KGa-2 from the Clay Mineral Society and kaolinite from Sigma-Aldrich; the montmorillonites SWy-2 and STx-1b from the Clay Mineral Society and the acid treated montmorillonites KSF and K-10 from Sigma Aldrich; the illites NX and SE from Arginotec. The emulsion experiments provide information on the average freezing behaviour characterized by the average nucleation sites. These experiments revealed one to 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 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 showed quite narrow standard peaks with onset temperatures 239 K < Tonstd < 242 K and best sites with averaged median freezing temperature Tmedbest = 257 K. Only the kaolinite from Sigma Aldrich featured a special peak with freezing onset at 248 K. The illites showed broad standard peaks with freezing onsets at 244 K < Tonstd < 246 K and best sites with averaged median freezing temperature Tmedbest = 262 K. Montmorillonites had standard peaks with onsets 238 K < Tonstd < 240 K and best sites with Tmedbest=257 K. SWy-2, M K10, and KSF featured special peaks with onsets at Tonspcl=247, 240, and 242 K, respectively. M K10 and KSF both from Sigma Aldrich had less intense standard peaks compared to the ones from the Clay Mineral Society suggesting that a fraction of the standard sites are lost by the acid treatment. The acid

  20. Deposition kinetics of MS2 bacteriophages on clay mineral surfaces.

    PubMed

    Tong, Meiping; Shen, Yun; Yang, Haiyan; Kim, Hyunjung

    2012-04-01

    The deposition of bacteriophage MS2 on bare and clay-coated silica surfaces was examined in both monovalent (NaCl) and divalent (CaCl(2) and MgCl(2)) solutions under a wide range of environmentally relevant ionic strength and pH conditions by utilizing a quartz crystal microbalance with dissipation (QCM-D). Two types of clay, bentonite and kaolinite, were concerned in this study. To better understand MS2 deposition mechanisms, QCM-D data were complemented by zeta potentials measurements and Derjaguin-Landau-Verwey-Overbeek (DLVO) interaction forces calculation. In both monovalent and divalent solutions, deposition efficiencies of MS2 increased with increasing ionic strength both on bare and clay-coated surfaces, which agreed with the trends of interaction forces between MS2 and solid surface and thus was consistent with DLVO theory. The presence of divalent ions (Ca(2+) and Mg(2+)) in solutions greatly increased virus deposition on both silica and clay deposited surfaces. Coating silica surfaces with clay minerals, either kaolinite or bentonite, could significantly increase MS2 deposition.

  1. Diagenesis and clay mineral formation at Gale Crater, Mars

    NASA Astrophysics Data System (ADS)

    Bridges, J. C.; Schwenzer, S. P.; Leveille, R.; Westall, F.; Wiens, R. C.; Mangold, N.; Bristow, T.; Edwards, P.; Berger, G.

    2015-01-01

    Mars Science Laboratory rover Curiosity found host rocks of basaltic composition and alteration assemblages containing clay minerals at Yellowknife Bay, Gale Crater. On the basis of the observed host rock and alteration minerals, we present results of equilibrium thermochemical modeling of the Sheepbed mudstones of Yellowknife Bay in order to constrain the formation conditions of its secondary mineral assemblage. Building on conclusions from sedimentary observations by the Mars Science Laboratory team, we assume diagenetic, in situ alteration. The modeling shows that the mineral assemblage formed by the reaction of a CO2-poor and oxidizing, dilute aqueous solution (Gale Portage Water) in an open system with the Fe-rich basaltic-composition sedimentary rocks at 10-50°C and water/rock ratio (mass of rock reacted with the starting fluid) of 100-1000, pH of ~7.5-12. Model alteration assemblages predominantly contain phyllosilicates (Fe-smectite, chlorite), the bulk composition of a mixture of which is close to that of saponite inferred from Chemistry and Mineralogy data and to that of saponite observed in the nakhlite Martian meteorites and terrestrial analogues. To match the observed clay mineral chemistry, inhomogeneous dissolution dominated by the amorphous phase and olivine is required. We therefore deduce a dissolving composition of approximately 70% amorphous material, with 20% olivine, and 10% whole rock component.

  2. Diagenesis and clay mineral formation at Gale Crater, Mars

    PubMed Central

    Bridges, J C; Schwenzer, S P; Leveille, R; Westall, F; Wiens, R C; Mangold, N; Bristow, T; Edwards, P; Berger, G

    2015-01-01

    The Mars Science Laboratory rover Curiosity found host rocks of basaltic composition and alteration assemblages containing clay minerals at Yellowknife Bay, Gale Crater. On the basis of the observed host rock and alteration minerals, we present results of equilibrium thermochemical modeling of the Sheepbed mudstones of Yellowknife Bay in order to constrain the formation conditions of its secondary mineral assemblage. Building on conclusions from sedimentary observations by the Mars Science Laboratory team, we assume diagenetic, in situ alteration. The modeling shows that the mineral assemblage formed by the reaction of a CO2-poor and oxidizing, dilute aqueous solution (Gale Portage Water) in an open system with the Fe-rich basaltic-composition sedimentary rocks at 10–50°C and water/rock ratio (mass of rock reacted with the starting fluid) of 100–1000, pH of ∽7.5–12. Model alteration assemblages predominantly contain phyllosilicates (Fe-smectite, chlorite), the bulk composition of a mixture of which is close to that of saponite inferred from Chemistry and Mineralogy data and to that of saponite observed in the nakhlite Martian meteorites and terrestrial analogues. To match the observed clay mineral chemistry, inhomogeneous dissolution dominated by the amorphous phase and olivine is required. We therefore deduce a dissolving composition of approximately 70% amorphous material, with 20% olivine, and 10% whole rock component. PMID:26213668

  3. Diagenesis and clay mineral formation at Gale Crater, Mars

    DOE PAGESBeta

    Bridges, J. C.; Schwenzer, S. P.; Leveille, R.; Westall, F.; Wiens, R. C.; Mangold, N.; Bristow, T.; Edwards, P.; Berger, G.

    2015-01-18

    The Mars Science Laboratory rover Curiosity found host rocks of basaltic composition and alteration assemblages containing clay minerals at Yellowknife Bay, Gale Crater. On the basis of the observed host rock and alteration minerals, we present results of equilibrium thermochemical modeling of the Sheepbed mudstones of Yellowknife Bay in order to constrain the formation conditions of its secondary mineral assemblage. Building on conclusions from sedimentary observations by the Mars Science Laboratory team, we assume diagenetic, in situ alteration. The modeling shows that the mineral assemblage formed by the reaction of a CO₂-poor and oxidizing, dilute aqueous solution (Gale Portage Water)more » in an open system with the Fe-rich basaltic-composition sedimentary rocks at 10–50°C and water/rock ratio (mass of rock reacted with the starting fluid) of 100–1000, pH of ~7.5–12. Model alteration assemblages predominantly contain phyllosilicates (Fe-smectite, chlorite), the bulk composition of a mixture of which is close to that of saponite inferred from Chemistry and Mineralogy data and to that of saponite observed in the nakhlite Martian meteorites and terrestrial analogues. To match the observed clay mineral chemistry, inhomogeneous dissolution dominated by the amorphous phase and olivine is required. We therefore deduce a dissolving composition of approximately 70% amorphous material, with 20% olivine, and 10% whole rock component.« less

  4. Diagenesis and clay mineral formation at Gale Crater, Mars

    SciTech Connect

    Bridges, J. C.; Schwenzer, S. P.; Leveille, R.; Westall, F.; Wiens, R. C.; Mangold, N.; Bristow, T.; Edwards, P.; Berger, G.

    2015-01-18

    The Mars Science Laboratory rover Curiosity found host rocks of basaltic composition and alteration assemblages containing clay minerals at Yellowknife Bay, Gale Crater. On the basis of the observed host rock and alteration minerals, we present results of equilibrium thermochemical modeling of the Sheepbed mudstones of Yellowknife Bay in order to constrain the formation conditions of its secondary mineral assemblage. Building on conclusions from sedimentary observations by the Mars Science Laboratory team, we assume diagenetic, in situ alteration. The modeling shows that the mineral assemblage formed by the reaction of a CO₂-poor and oxidizing, dilute aqueous solution (Gale Portage Water) in an open system with the Fe-rich basaltic-composition sedimentary rocks at 10–50°C and water/rock ratio (mass of rock reacted with the starting fluid) of 100–1000, pH of ~7.5–12. Model alteration assemblages predominantly contain phyllosilicates (Fe-smectite, chlorite), the bulk composition of a mixture of which is close to that of saponite inferred from Chemistry and Mineralogy data and to that of saponite observed in the nakhlite Martian meteorites and terrestrial analogues. To match the observed clay mineral chemistry, inhomogeneous dissolution dominated by the amorphous phase and olivine is required. We therefore deduce a dissolving composition of approximately 70% amorphous material, with 20% olivine, and 10% whole rock component.

  5. [Interaction of clay minerals with microorganisms: a review of experimental data].

    PubMed

    Naĭmark, E B; Eroshchev-Shak, V A; Chizhikova, N P; Kompantseva, E I

    2009-01-01

    A review of publications containing results of experiments on the interaction of microorganisms with clay minerals is presented. Bacteria are shown to be involved in all processes related to the transformation of clay minerals: formation of clays from metamorphic and sedimentary rocks, formation of clays from solutions, reversible transitions of different types of clay minerals, and consolidation of clay minerals into sedimentary rocks. Integration of these results allows to conclude that bacteria reproduced all possible abiotic reactions associated with the clay minerals, these reactions proceed much faster with the bacteria being involved. Thus, bacteria act as a living catalyst in the geochemical cycle of clay minerals. The ecological role of bacteria can be considered as a repetition of a chemical process of the abiotic world, but with the use of organic catalytic innovation.

  6. Studies of clays and clay minerals using x-ray powder diffraction and the Rietveld method

    SciTech Connect

    Bish, D.L.

    1993-09-01

    The Rietveld method was originally developed (Rietveld, 1967, 1969) to refine crystal structures using neutron powder diffraction data. Since then, the method has been increasingly used with X-ray powder diffraction data, and today it is safe to say that this is the most common application of the method. The method has been applied to numerous natural and synthetic materials, most of which do not usually form crystals large enough for study with single-crystal techniques. It is the ability to study the structures of materials for which sufficiently large single crystals do not exist that makes the method so powerful and popular. It would thus appear that the method is ideal for studying clays and clay minerals. In many cases this is true, but the assumptions implicit in the method and the disordered nature of many clay minerals can limit titsapplicability. This chapter will describe the Rietveld method, emphasizing the assumptions important for the study of disordered materials, and it will outline the potential applications of the method to these minerals. These applications include, in addition to the refinement of crystal structures, quantitative analysis of multicomponent mixtures, analysis of peak broadening, partial structure solution, and refinement of unit-cell parameters.

  7. New techniques for clay mineral identification by remote sensing

    SciTech Connect

    Abrams, M.J.; Goetz, A.F.H.; Lang, H.

    1983-03-01

    In the past three years there have been major advancements in our ability to identify clay minerals by remote sensing. Multispectral scanners, including NASA's Thematic Mapper Simulator (analog for Landsat-D Thematic Mapper) have had several broad-band channels in the wavelength region of 1.0 to 2.5 ..mu..m. In particular, the wavelength region 2.0 to 2.5 ..mu..m contains diagnostic spectral-absorption features for most layered silicates. Computer processing of image data obtained with these scanners has allowed the identification of the presence of clay minerals, without, however, being able to identify specific mineralogies. Studies of areas with known hydrocarbon deposits and porphyry copper deposits have demonstrated the value of this information for rock-type discrimination and recognition of hydrothermal alteration zones. Non-imaging, narrow-band radiometers and spectrometers have been used in the field, from aircraft, and from space to identify individual mineralogical constituents. This can be done because of diagnostic spectral absorption features in the 2.0 to 2.5 ..mu..m region characteristic of different clay types. Preliminary analysis of SMIRR data over Egypt showed that kaolinite, carbonate rocks, and possibly montmorillonite, could be identified directly. Plans are currently under way for development of narrow-band imaging systems which will be capable of producing maps showing the surface distribution of individual clay types. This will represent a major step in remote sensing, by allowing unique identification of minerals rather than the current ability only to discriminate among materials. Applications of this technology will provide geologists with a powerful new tool for resource exploration and general geologic mapping problems.

  8. Transformation of anthracene on various cation-modified clay minerals.

    PubMed

    Li, Li; Jia, Hanzhong; Li, Xiyou; Wang, Chuanyi

    2015-01-01

    In this study, anthracene was employed as a probe to explore the potential catalytic effect of clay minerals in soil environment. Clay minerals saturated with various exchangeable cations were tested. The rate of anthracene transformation follows the order: Fe-smectite > Cu-smectite > Al-smectite ≈ Ca-smectite ≈ Mg-smectite ≈ Na-smectite. This suggests that transition-metal ions such as Fe(III) play an important role in anthracene transformation. Among Fe(III)-saturated clays, Fe(III)-smectite exhibits the highest catalytic activity followed by Fe(III)-illite, Fe(III)-pyrophyllite, and Fe(III)-kaolinite, which is in agreement with the interlayer Fe(III) content. Moreover, effects by two common environmental factors, pH and relative humidity (RH), were evaluated. With an increase in pH or RH, the rate of anthracene transformation decreases rapidly at first and then is leveled off. GC-MS analysis identifies that the final product of anthracene transformation is 9,10-anthraquinone, a more bioavailable molecule compared to anthracene. The transformation process mainly involves cation-π bonding, electron transfer leading to cation radical, and further oxidation by chemisorbed O2. The present work provides valuable insights into the abiotic transformation and the fate of PAHs in the soil environment and the development of contaminated land remediation technologies.

  9. Adsorption of nucleic Acid bases, ribose, and phosphate by some clay minerals.

    PubMed

    Hashizume, Hideo

    2015-01-01

    Besides having a large capacity for taking up organic molecules, clay minerals can catalyze a variety of organic reactions. Derived from rock weathering, clay minerals would have been abundant in the early Earth. As such, they might be expected to play a role in chemical evolution. The interactions of clay minerals with biopolymers, including RNA, have been the subject of many investigations. The behavior of RNA components at clay mineral surfaces needs to be assessed if we are to appreciate how clays might catalyze the formation of nucleosides, nucleotides and polynucleotides in the "RNA world". The adsorption of purines, pyrimidines and nucleosides from aqueous solution to clay minerals is affected by suspension pH. With montmorillonite, adsorption is also influenced by the nature of the exchangeable cations. Here, we review the interactions of some clay minerals with RNA components.

  10. Clays and Clay Minerals and their environmental application in Food Technology

    NASA Astrophysics Data System (ADS)

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

    2013-04-01

    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

  11. Program and Abstracts for Clay Minerals Society 28th Annual Meeting

    NASA Technical Reports Server (NTRS)

    1991-01-01

    This volume contains abstracts that were accepted for presentation at the annual meeting. Some of the main topics covered include: (1) fundamental properties of minerals and methods of mineral analysis; (2) surface chemistry; (3) extraterrestrial clay minerals; (4) geothermometers and geochronometers; (5) smectite, vermiculite, illite, and related reactions; (6) soils and clays in environmental research; (7) kaolinite, halloysite, iron oxides, and mineral transformations; and (8) clays in lakes, basins, and reservoirs.

  12. Iron(III)-bearing clay minerals enhance bioreduction of nitrobenzene by Shewanella putrefaciens CN32.

    PubMed

    Luan, Fubo; Liu, Yan; Griffin, Aron M; Gorski, Christopher A; Burgos, William D

    2015-02-01

    Iron-bearing clay minerals are ubiquitous in the environment, and the clay-Fe(II)/Fe(III) redox couple plays important roles in abiotic reduction of several classes of environmental contaminants. We investigated the role of Fe-bearing clay minerals on the bioreduction of nitrobenzene. In experiments with Shewanella putrefaciens CN32 and excess electron donor, we found that the Fe-bearing clay minerals montmorillonite SWy-2 and nontronite NAu-2 enhanced nitrobenzene bioreduction. On short time scales (<50 h), nitrobenzene reduction was primarily biologically driven, but at later time points, nitrobenzene reduction by biologically formed structural Fe(II) in the clay minerals became increasingly important. We found that chemically reduced (dithionite) iron-bearing clay minerals reduced nitrobenzene more rapidly than biologically reduced iron-bearing clay minerals despite the minerals having similar structural Fe(II) concentrations. We also found that chemically reduced NAu-2 reduced nitrobenzene faster as compared to chemically reduced SWy-2. The different reactivity of SWy-2 versus NAu-2 toward nitrobenzene was caused by different forms of structural clay-Fe(II) in the clay minerals and different reduction potentials (Eh) of the clay minerals. Because most contaminated aquifers become reduced via biological activity, the reactivity of biogenic clay-Fe(II) toward reducible contaminants is particularly important.

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

    SciTech Connect

    Maurice, Patricia A.

    2010-02-08

    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.

  14. Radiolysis of alanine adsorbed in a clay mineral

    SciTech Connect

    Aguilar-Ovando, Ellen Y.; Negron-Mendoza, Alicia

    2013-07-03

    Optical activity in molecules is a chemical characteristic of living beings. In this work, we examine the hypothesis of the influence of different mineral surfaces on the development of a specific chirality in organic molecules when subjected to conditions simulating the primitive Earth during the period of chemical evolution. By using X-ray diffraction techniques and HPLC/ELSD to analyze aqueous suspensions of amino acids adsorbed on minerals irradiated in different doses with a cobalt-60 gamma source, the experiments attempt to prove the hypothesis that some solid surfaces (like clays and meteorite rocks) may have a concentration capacity and protective role against external sources of ionizing radiation (specifically {gamma}-ray) for some organic compounds (like some amino acids) adsorbed on them. Preliminary results show a slight difference in the adsorption and radiolysis of the D-and L-alanine.

  15. Analysis of mixed-layer clay mineral structures

    USGS Publications Warehouse

    Bradley, W.F.

    1953-01-01

    Among the enormously abundant natural occurrences of clay minerals, many examples are encountered in which no single specific crystallization scheme extends through a single ultimate grain. The characterization of such assemblages becomes an analysis of the distribution of matter within such grains, rather than the simple identification of mineral species. It having become established that the particular coordination complex typified by mica is a common component of many natural subcrystalline assemblages, the opportunity is afforded to analyze scattering from random associations of these complexes with other structural units. Successful analyses have been made of mixed hydration states of montmorillonite, of montmorillonite with mica, of vermiculite with mica, and of montmorillonite with chlorite, all of which are variants of the mica complex, and of halloysite with hydrated halloysite.

  16. Role of clay minerals in the transportation of iron

    USGS Publications Warehouse

    Carroll, D.

    1958-01-01

    The clay minerals have iron associated with them in several ways: 1. (1) as an essential constituent 2. (2) as a minor constituent within the crystal lattice where it is in isomorphous substitution and 3. (3) as iron oxide on the surface of the mineral platelets. Nontronite, "hydromica," some chlorites, vermiculite, glauconite and chamosite contain iron as an essential constituent. Kaolinite and halloysite have no site within the lattice for iron, but in certain environments iron oxide (goethite or hematite) is intimately associated as a coating on the micelles. Analyses of clay minerals show that the content of Fe2O3 varies: 29 per cent (nontronite), 7??3 per cent (griffithite), 4.5 per cent ("hydromica"), 5.5 per cent (chlorite), 4 per cent (vermiculite) and 18 per cent (glauconite). The FeO content is: 40 per cent (chamosite), 7.8 per cent (griffithite), 1-2 per cent ("hydromica"), 3 per cent (glauconite) and 2 per cent (chlorite). The iron associated with the clay minerals remains stable in the environment in which the minerals occur, but if either pH or Eh or both are changed the iron may be affected. Change of environment will cause: 1. (1) removal of iron by reduction of Fe3+ to Fe2+; 2. (2) ion-exchange reactions; 3. (3) instability of the crystal lattice. Experiments using bacterial activity to produce reducing conditions with kaolinite and halloysite coated with iron oxides and with nontronite in which ferric iron is in the octahedral position within the lattice showed that ferric oxide is removed at Eh +0??215 in fresh water and at Eh +0.098 in sea water. Hematite, goethite, and indefinite iron oxides were removed at different rates. Red ferric oxides were changed to black indefinite noncrystalline ferrous sulphide at Eh -0.020 but reverted to ferric oxide under oxidizing conditions. Nontronite turned bright green under reducing conditions and some of the ferrous iron remained within the lattice on a return to oxidizing conditions. Bacterial activity

  17. The formation of goethite and hydrated clay minerals on Mars

    NASA Technical Reports Server (NTRS)

    Huguenin, R. L.

    1974-01-01

    Laboratory studies reported by Huguenin (1973) on the kinetics and mechanism of the photostimulated oxidation of magnetic and preliminary laboratory data on the weathering of silicates, reported herein, are applied to Mars. Basalts in the Martian dark areas are predicted to alter to hydrated Fe(2 plus or minus) depleted clay minerals, minor goethite, and minor to trace amounts of transition metal oxides such as TiO2, MnO2, and Cr2O3 at a rate of 10 to the minus 1.5 plus or minus 1.5 micron/yr. Some Ca-Mg carbonates are also expected to be formed. The clay minerals are predicted to be more silica-rich than the silicate source material, SiO2 contents of 60% or higher being expected, and strongly depleted in Fe(2+). The oxygen, OH, and H2O contents of the bulk weathering product are predicted to be significantly greater than those of the dark-area source materials, whereas the relative bulk metal abundances should be the same.

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

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

    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.

  19. Kinetic Study of Denatonium Sorption to Smectite Clay Minerals.

    PubMed

    Crosson, Garry S; Sandmann, Emily

    2013-06-01

    The denatonium cation, as a benzoate salt, is the most bitter cation known to modern society and is frequently added to consumer products to reduce accidental and intentional consumption by humans and animals. Denatonium can enter the environment by accidental discharges, potentially rendering water supplies undrinkable. Interactions of denatonium with soil components (i.e., smectite minerals) ultimately control the environmental fate of denatonium, but the current literature is devoid of studies that evaluate denatonium sorption to smectite minerals. This study investigated the mechanism and kinetics of denatonium sorption to smectite clay minerals as a function of smectite type, temperature, pH and ionic strength. Uptake by synthetic mica montmorillonite (Syn-1), Wyoming montmorillonite (SWy-2), and Texas montmorillonite (STx-1b) at 305K was rapid, with equilibrium being reached within 2 min for all clays. Complete removal of denatonium was observed for STx-1b at pH 6.9, while partial removal was observed for Syn-1 and SWy-2. Kinetic behavior of SWy-2 and Syn-1 is consistent with a pseudo-second-order model at 305K. An activation energy of +25.9 kJ/mol was obtained for sorption to Syn-1 and was independent of temperature between 286K and 338K. Activation-free energy (ΔG*), activation enthalpy (ΔH*), and activation entropy (ΔS*) for Syn-1 were found to be +62.91 kJ/mol, +23.36 kJ/mol, and -0.130 kJ/(K·mol), respectively. Sorption capacities at pH 3.6, 6.9, and 8.2 were constant at 1.3×10(-2) g denatonium/g clay; however, the kinetic rate constant increased by 56%, going from acidic to basic solution conditions. Distribution coefficients were negatively correlated with ionic strength, suggesting cation exchange. Collectively, results suggested that smectite minerals can serve as efficient sinks for denatonium cations. This is much-needed information for agencies developing regulations regarding denatonium usage and for water treatment professionals who may

  20. Kinetic Study of Denatonium Sorption to Smectite Clay Minerals

    PubMed Central

    Crosson, Garry S.; Sandmann, Emily

    2013-01-01

    Abstract The denatonium cation, as a benzoate salt, is the most bitter cation known to modern society and is frequently added to consumer products to reduce accidental and intentional consumption by humans and animals. Denatonium can enter the environment by accidental discharges, potentially rendering water supplies undrinkable. Interactions of denatonium with soil components (i.e., smectite minerals) ultimately control the environmental fate of denatonium, but the current literature is devoid of studies that evaluate denatonium sorption to smectite minerals. This study investigated the mechanism and kinetics of denatonium sorption to smectite clay minerals as a function of smectite type, temperature, pH and ionic strength. Uptake by synthetic mica montmorillonite (Syn-1), Wyoming montmorillonite (SWy-2), and Texas montmorillonite (STx-1b) at 305K was rapid, with equilibrium being reached within 2 min for all clays. Complete removal of denatonium was observed for STx-1b at pH 6.9, while partial removal was observed for Syn-1 and SWy-2. Kinetic behavior of SWy-2 and Syn-1 is consistent with a pseudo–second-order model at 305K. An activation energy of +25.9 kJ/mol was obtained for sorption to Syn-1 and was independent of temperature between 286K and 338K. Activation-free energy (ΔG*), activation enthalpy (ΔH*), and activation entropy (ΔS*) for Syn-1 were found to be +62.91 kJ/mol, +23.36 kJ/mol, and −0.130 kJ/(K·mol), respectively. Sorption capacities at pH 3.6, 6.9, and 8.2 were constant at 1.3×10−2 g denatonium/g clay; however, the kinetic rate constant increased by 56%, going from acidic to basic solution conditions. Distribution coefficients were negatively correlated with ionic strength, suggesting cation exchange. Collectively, results suggested that smectite minerals can serve as efficient sinks for denatonium cations. This is much-needed information for agencies developing regulations regarding denatonium usage and for water treatment

  1. DFT theoretical and FT-IR spectroscopic investigations of the plasticity of clay minerals dispersions

    NASA Astrophysics Data System (ADS)

    Kasprzhitskii, A.; Lazorenko, G.; Yavna, V.; Daniel, Ph.

    2016-04-01

    Plasticity is the most important property of dispersions of clay minerals that determine the character of participation of these systems in many natural and technological processes. We report on the results of studies of hydration mechanism in typical clay minerals making part of natural dispersions of sedimentation masses by means of IR spectroscopy and theoretical density functional theory (DFT) methods. X-ray diffraction analysis of clay minerals of Millerovo mineral deposit (Russian Federation) is carried out. Regularities and peculiarities of interaction of water molecules with kaolinite basal planes (001) and (00 1 bar) are analyzed. The role of water in the formation of plasticity of clay minerals dispersions is revealed. The modes of water molecules placement and their state and structure in the system "clay mineral-water" is defined. Phase transition processes of clay minerals dispersion into plastic and liquid state and their influence on spectral characteristics of the systems are investigated. The interpretation of clay minerals phase transitions into plastic and fluid state based on the results of DFT simulation is given. The relation is established between specific variation of spectral characteristics and phase transitions of clay minerals dispersions into plastic and liquid state.

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

    PubMed

    Samuels, Maya; Mor, Omer; Rytwo, Giora

    2013-04-01

    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.

  3. Origin of clay-mineral variation in Wisconsinan age sediments from the Lake Michigan basin

    SciTech Connect

    Monaghan, G.W. ); Larson, G.J. . Dept. of Geological Sciences)

    1994-04-01

    Drift samples collected in Wisconsin and Michigan from exposures representative of the Wisconsinan stratigraphy of the Lake Michigan Lobe indicate that clay mineral and shale lithology systematically vary between successive till sheets as a result of differential erosion of two unique source beds: shale bedrock, rich in 10[angstrom] clay (illite) and pre-existing drift (particularly lacustrine clay), depleted in 10[angstrom] clay. A general increase in relative amounts of 10[angstrom] clay and shale clasts begins with early or middle Wisconsinan (Altonian) Glenn Shores till and continues through late Wisconsinan (Woodfordian) Ganges-New Berlin till and Saugatuck-Oak Creek till. Both 10[angstrom] clay and shale decrease in post Mackinaw (late Woodfordian) Interstade Ozaukee-Haven and Two Rivers tills. Clay minerals in till rich in 10[angstrom] clay (Saugatuck-Oak Creek) were derived mainly from extensive erosion and comminution of shale whereas those in tills depleted in 10[angstrom] clay (Ganges-New Berlin, Ozaukee-Haven, and Two Rivers) were eroded mainly from lacustrine clay. Because it is compositionally dissimilar to either the shale or lake clay source and relatively rich in kaolinite, clay minerals in early-middle Wisconsinan Glenn Shores till may have been derived from Sangamon saprolite eroded during an early post-Sangamon ice advance. Variations in source bed erosion and subsequent changes in till lithology result either from depletion of the source bed (Glenn Shores till) or from progressively eroding drift mantling shale outcrops (unroofing) during successive late Wisconsinan ice advances.

  4. Clay Minerals in Mawrth Vallis Region of Mars

    NASA Technical Reports Server (NTRS)

    2008-01-01

    This map showing the location of some clay minerals in of a portion of the Mawrth Vallis region of Mars covers an area about 10 kilometers (6.2 mile) wide. The map is draped over a topographical model that exaggerates the vertical dimension tenfold.

    The mineral mapping information comes from an image taken on Sept. 21, 2007, by the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM). Iron-magnesium phyllosilicate is shown in red. Aluminum phyllosyllicate is shown in blue. Hydrated silica and a ferrous iron phase are shown in yellow/green.

    The topographical information comes from the Mars Orbiter Laser Altimeter instrument on NASA's Mars Global Surveyor orbiter.

    Mawrth Vallis is an outflow channel centered near 24.7 degrees north latitude, 339.5 degrees east longitude, in northern highlands of Mars.

    CRISM is one of six science instruments on the Mars Reconnaissance Orbiter. Led by The Johns Hopkins University Applied Physics Laboratory, Laurel, Md., the CRISM team includes expertise from universities, government agencies and small businesses in the United States and abroad. NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Mars Reconnaissance Orbiter for NASA's Science Mission Directorate, Washington. Lockheed Martin Space Systems, Denver, built the orbiter.

  5. Bioremediation of PAHs and VOCs: Advances in clay mineral-microbial interaction.

    PubMed

    Biswas, Bhabananda; Sarkar, Binoy; Rusmin, Ruhaida; Naidu, Ravi

    2015-12-01

    Bioremediation is an effective strategy for cleaning up organic contaminants, such as polycyclic aromatic hydrocarbons (PAHs) and volatile organic compounds (VOCs). Advanced bioremediation implies that biotic agents are more efficient in degrading the contaminants completely. Bioremediation by microbial degradation is often employed and to make this process efficient, natural and cost-effective materials can serve as supportive matrices. Clay/modified clay minerals are effective adsorbents of PAHs/VOCs, and readily available substrate and habitat for microorganisms in the natural soil and sediment. However, the mechanism underpinning clay-mediated biodegradation of organic compounds is often unclear, and this requires critical investigation. This review describes the role of clay/modified clay minerals in hydrocarbon bioremediation through interaction with microbial agents in specific scenarios. The vision is on a faster, more efficient and cost-effective bioremediation technique using clay-based products. This review also proposes future research directions in the field of clay modulated microbial degradation of hydrocarbons.

  6. A general evaluation of the frequency distribution of clay and associated minerals in the alluvial soils of ceylon

    USGS Publications Warehouse

    Herath, J.W.; Grimshaw, R.W.

    1971-01-01

    Clay mineral analyses were made of several alluvial clay materials from Ceylon. These studies show that the soil materials can be divided into 3 clay mineral provinces on the basis of the frequency distribution of clay and associated minerals. The provinces closely follow the climatic divisions. The characteristic feature of this classification is the progressive development of gibbsite from Dry to Wet Zone areas. Gibbsite has been used as a reliable indicator mineral. ?? 1971.

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

    NASA Technical Reports Server (NTRS)

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

    1994-01-01

    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.

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

    ERIC Educational Resources Information Center

    Kohut, Connie K.; And Others

    1993-01-01

    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)

  9. Thermal magnetic behaviour of Al-substituted haematite mixed with clay minerals and its geological significance

    NASA Astrophysics Data System (ADS)

    Jiang, Zhaoxia; Liu, Qingsong; Zhao, Xiangyu; Jin, Chunsheng; Liu, Caicai; Li, Shihu

    2015-01-01

    Clay minerals and Al-substituted haematite (Al-hm) usually coexist in soils and sediments. However, effects of clay minerals on Al-hm during thermal magnetic measurements in argon environment have not been well studied. In order to quantify such effects, a series of Al-hm samples were synthesized, and were then mixed with clay minerals (illite, chlorite, kaolinite and Ca-montmorillonite). The temperature dependence of magnetic susceptibility curves in an argon environment showed that Al-substituted magnetite was produced during the thermal treatment via the reduction of Al-hm by the clay mineral, which leads to a significant magnetic enhancement of the thermal products. In addition, the reductive capacity varies among different types of clay minerals, that is, illite > chlorite > kaolinite > Ca-montmorillonite. Furthermore, the iron content in the clay minerals and Al content of Al-hm are two predominant factors controlling the reduced haematite content. The iron is released from the clay minerals and provides the reducing agent, while Al decreases the crystallinity of haematite and thus facilitates the chemical reaction. Therefore, the thermal magnetic measurements can be used to quantify the Al content of Al-hm in natural samples. Our study provides significant information for palaeomagnetism and environmental magnetism studies, such as thermal magnetic analysis and palaeomagnetic intensity reconstruction using ancient pottery and kilns.

  10. Transport and selective uptake of radium into natural clay minerals

    NASA Astrophysics Data System (ADS)

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

    2007-12-01

    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.

  11. A SEM, EDS and vibrational spectroscopic study of the clay mineral fraipontite.

    PubMed

    Theiss, Frederick L; López, Andrés; Scholz, Ricardo; Frost, Ray L

    2015-08-01

    The mineral fraipontite has been studied by using a combination of scanning electron microscopy with energy dispersive analysis and vibrational spectroscopy (infrared and Raman). Fraipontite is a member of the 1:1 clay minerals of the kaolinite-serpentine group. The mineral contains Zn and Cu and is of formula (Cu,Zn,Al)₃(Si,Al)₂O₅(OH)₄. Qualitative chemical analysis of fraipontite shows an aluminium silicate mineral with amounts of Cu and Zn. This kaolinite type mineral has been characterised by Raman and infrared spectroscopy; in this way aspects about the molecular structure of fraipontite clay are elucidated.

  12. 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)

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

    2011-12-01

    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.

  13. [Species Determination and Spectral Characteristics of Swelling Clay Minerals in the Pliocene Sandstones in Xinghai, Qinghai].

    PubMed

    Wang, Chao-wen; Chen, Jiang-jun; Fang, Qian; Yin, Ke; Hong, Han-lie

    2015-10-01

    X-ray diffraction (XRD) and Fourier infrared absorption spectroscopy (FTIR) were conducted to deepen our research on specific species and spectral characteristics of swelling clay minerals in the Pliocene sandstones in Xinghai, Qinghai province. XRD results show that swelling clay minerals are dominant clay minerals in the sandstones, which can be up to 97% in percentage. XRD patterns show 060 reflections of the samples occur both remarkably at 1.534 Å and 1.498 Å, indicating the samples contain physical mixtures of trioctahedral and dioctahedral swelling clay minerals, respectively. Further treatment of Li-300 degrees C heat and glycerol saturation shows the swelling clay minerals collapse to 9.3-9.9 Å with a partial expansion to -18 Å. This indicates the swelling clay minerals dominate montmorillonite and contain minor saponite. The montmorillonite shows no swelling after Li-300 degrees C heat and glycerol saturation because of Li+ inserting into the octahedral layers, which balances the layer charge caused by the substitution of Mg to Al. FTIR results show the samples are composed of a kind of phyllosilicate with absorbed and structural water, which is in agreement with the results of XRD. Absorbed peaks at 913, 842, 880 cm(-1), corresponding to OH associated with Al-Al, Al-Mg, and Al-Fe pairs, further indicates the minerals are dominant dioctahedron in structure. Meanwhile, absorbed peaks at 625 and 519 cm(-1), corresponding to coupled Si-O and Al-O-Si deformation, indicates parts of Si is replaced by Al in tetrahedron. The spectral characteristics of the samples are against the presence of beidellite and nontronite based on the results of XRD and FTIR, while demonstrating an,existence of montmorillonite. This study, to distinguish the specific species of swelling clay species in clay minerals, would be of great importance when using clay mineralogy to interpret provenance and climatic information.

  14. Clay Minerals as Solid Acids and Their Catalytic Properties.

    ERIC Educational Resources Information Center

    Helsen, J.

    1982-01-01

    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)

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

    PubMed

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

    2006-05-01

    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.

  16. Evaluation of the medicinal use of clay minerals as antibacterial agents

    PubMed Central

    Williams, Lynda B.; Haydel, Shelley E.

    2010-01-01

    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. PMID:20640226

  17. Enhanced cellular preservation by clay minerals in 1 billion-year-old lakes.

    PubMed

    Wacey, David; Saunders, Martin; Roberts, Malcolm; Menon, Sarath; Green, Leonard; Kong, Charlie; Culwick, Timothy; Strother, Paul; Brasier, Martin D

    2014-07-28

    Organic-walled microfossils provide the best insights into the composition and evolution of the biosphere through the first 80 percent of Earth history. The mechanism of microfossil preservation affects the quality of biological information retained and informs understanding of early Earth palaeo-environments. We here show that 1 billion-year-old microfossils from the non-marine Torridon Group are remarkably preserved by a combination of clay minerals and phosphate, with clay minerals providing the highest fidelity of preservation. Fe-rich clay mostly occurs in narrow zones in contact with cellular material and is interpreted as an early microbially-mediated phase enclosing and replacing the most labile biological material. K-rich clay occurs within and exterior to cell envelopes, forming where the supply of Fe had been exhausted. Clay minerals inter-finger with calcium phosphate that co-precipitated with the clays in the sub-oxic zone of the lake sediments. This type of preservation was favoured in sulfate-poor environments where Fe-silicate precipitation could outcompete Fe-sulfide formation. This work shows that clay minerals can provide an exceptionally high fidelity of microfossil preservation and extends the known geological range of this fossilization style by almost 500 Ma. It also suggests that the best-preserved microfossils of this time may be found in low-sulfate environments.

  18. Enhanced cellular preservation by clay minerals in 1 billion-year-old lakes

    NASA Astrophysics Data System (ADS)

    Wacey, David; Saunders, Martin; Roberts, Malcolm; Menon, Sarath; Green, Leonard; Kong, Charlie; Culwick, Timothy; Strother, Paul; Brasier, Martin D.

    2014-07-01

    Organic-walled microfossils provide the best insights into the composition and evolution of the biosphere through the first 80 percent of Earth history. The mechanism of microfossil preservation affects the quality of biological information retained and informs understanding of early Earth palaeo-environments. We here show that 1 billion-year-old microfossils from the non-marine Torridon Group are remarkably preserved by a combination of clay minerals and phosphate, with clay minerals providing the highest fidelity of preservation. Fe-rich clay mostly occurs in narrow zones in contact with cellular material and is interpreted as an early microbially-mediated phase enclosing and replacing the most labile biological material. K-rich clay occurs within and exterior to cell envelopes, forming where the supply of Fe had been exhausted. Clay minerals inter-finger with calcium phosphate that co-precipitated with the clays in the sub-oxic zone of the lake sediments. This type of preservation was favoured in sulfate-poor environments where Fe-silicate precipitation could outcompete Fe-sulfide formation. This work shows that clay minerals can provide an exceptionally high fidelity of microfossil preservation and extends the known geological range of this fossilization style by almost 500 Ma. It also suggests that the best-preserved microfossils of this time may be found in low-sulfate environments.

  19. Enhanced cellular preservation by clay minerals in 1 billion-year-old lakes.

    PubMed

    Wacey, David; Saunders, Martin; Roberts, Malcolm; Menon, Sarath; Green, Leonard; Kong, Charlie; Culwick, Timothy; Strother, Paul; Brasier, Martin D

    2014-01-01

    Organic-walled microfossils provide the best insights into the composition and evolution of the biosphere through the first 80 percent of Earth history. The mechanism of microfossil preservation affects the quality of biological information retained and informs understanding of early Earth palaeo-environments. We here show that 1 billion-year-old microfossils from the non-marine Torridon Group are remarkably preserved by a combination of clay minerals and phosphate, with clay minerals providing the highest fidelity of preservation. Fe-rich clay mostly occurs in narrow zones in contact with cellular material and is interpreted as an early microbially-mediated phase enclosing and replacing the most labile biological material. K-rich clay occurs within and exterior to cell envelopes, forming where the supply of Fe had been exhausted. Clay minerals inter-finger with calcium phosphate that co-precipitated with the clays in the sub-oxic zone of the lake sediments. This type of preservation was favoured in sulfate-poor environments where Fe-silicate precipitation could outcompete Fe-sulfide formation. This work shows that clay minerals can provide an exceptionally high fidelity of microfossil preservation and extends the known geological range of this fossilization style by almost 500 Ma. It also suggests that the best-preserved microfossils of this time may be found in low-sulfate environments. PMID:25068404

  20. Micro and nano-size pores of clay minerals in shale reservoirs: Implication for the accumulation of shale gas

    NASA Astrophysics Data System (ADS)

    Chen, Shangbin; Han, Yufu; Fu, Changqin; Zhang, han; Zhu, Yanming; Zuo, Zhaoxi

    2016-08-01

    A pore is an essential component of shale gas reservoirs. Clay minerals are the adsorption carrier second only to organic matter. This paper uses the organic maturity test, Field-Emission Scanning Electron Microscopy (FE-SEM), and X-ray Diffraction (XRD) to study the structure and effect of clay minerals on storing gas in shales. Results show the depositional environment and organic maturity influence the content and types of clay minerals as well as their structure in the three types of sedimentary facies in China. Clay minerals develop multi-size pores which shrink to micro- and nano-size by close compaction during diagenesis. Micro- and nano-pores can be divided into six types: 1) interlayer, 2) intergranular, 3) pore and fracture in contact with organic matter, 4) pore and fracture in contact with other types of minerals, 5) dissolved and, 6) micro-cracks. The contribution of clay minerals to the presence of pores in shale is evident and the clay plane porosity can even reach 16%, close to the contribution of organic matter. The amount of clay minerals and pores displays a positive correlation. Clay minerals possess a strong adsorption which is affected by moisture and reservoir maturity. Different pore levels of clay minerals are mutually arranged, thus essentially producing distinct reservoir adsorption effects. Understanding the structural characteristics of micro- and nano-pores in clay minerals can provide a tool for the exploration and development of shale gas reservoirs.

  1. Clay Mineral Assemblages as Proxies for Reconstructing Messinian Paleoenvironments in the Western Mediterranean

    NASA Astrophysics Data System (ADS)

    Martinez-Ruiz, Francisca; Comas, Menchu; Vasconcelos, Crisogono

    2014-05-01

    Significant tectonic and climate changes at time of the Messinian Salinity Crisis (MSC) led to a complex sedimentation involving marked changes in sediment composition, particularly in clay mineral assemblages. One of the noticeable mineralogical changes across this time interval is the strong smectite increase in Messinian deposits in comparison to the underlying Tortonian and overlaying Pliocene sediments. As no break in the clay mineralogy is recognized in the open ocean (Chamley et al., 1978), such changes are also distinctive of the Mediterranean basins. Since the early discoveries of the giant Messinian evaporite formation (DSDP Legs 13 and 42A), a vast literature contributed, during the last decades, to the continuous debate and re-examination of the actual Messinian paleoenvironment. Drilled records in the westernmost Mediterranean (Alboran Sea) have shown significant changes in the mineralogical assemblages associated to the Messinian events. This basin is depleted of significant salt deposits. Site 976 (ODP Leg 161) recovered a 670-m-thick, middle Miocene (Serravallian) to Pleistocene/Holocene sedimentary sequence, including a thin interval of Messinian sediment, lying directly upon the metamorphic basement. Analysis of clay mineral assemblages from the sedimentary cover of Hole 976B revealed an homogeneous clay association composed of illite, smectite, chlorite and kaolinite with no major changes in clay mineral abundances except for the sediment interval dated as Messinian, which is characterized by a sharp smectite increase (Martinez-Ruiz et al., 1999). Transmission Electron Microscope analyses of clay minerals revealed that smectite composition corresponds to Al-rich beidellites, which supports the existence of such smectites in peri-Mediterranean soils. Smectite formation was favored by the climate conditions at that time, comprising progressive aridification and the alternation of wet and dry climatic episodes. Diagenesis in these smectites is

  2. Potential bioavailability of mercury in humus-coated clay minerals.

    PubMed

    Zhu, Daiwen; Zhong, Huan

    2015-10-01

    It is well-known that both clay and organic matter in soils play a key role in mercury biogeochemistry, while their combined effect is less studied. In this study, kaolinite, vermiculite, and montmorillonite were coated or not with humus, and spiked with inorganic mercury (IHg) or methylmercury (MeHg). The potential bioavailability of mercury to plants or deposit-feeders was assessed by CaCl2 or bovine serum albumin (BSA) extraction. For uncoated clay, IHg or MeHg extraction was generally lower in montmorillonite, due to its greater number of functional groups. Humus coating increased partitioning of IHg (0.5%-13.7%) and MeHg (0.8%-52.9%) in clay, because clay-sorbed humus provided more strong binding sites for mercury. Furthermore, humus coating led to a decrease in IHg (3.0%-59.8% for CaCl2 and 2.1%-5.0% for BSA) and MeHg (8.9%-74.6% for CaCl2 and 0.5%-8.2% for BSA) extraction, due to strong binding between mercury and clay-sorbed humus. Among various humus-coated clay particles, mercury extraction by CaCl2 (mainly through cation exchange) was lowest in humus-coated vermiculite, explained by the strong binding between humus and vermiculite. The inhibitory effect of humus on mercury bioavailability was also evidenced by the negative relationship between mercury extraction by CaCl2 and mercury in the organo-complexed fraction. In contrast, extraction of mercury by BSA (principally through complexation) was lowest in humus-coated montmorillonite. This was because BSA itself could be extensively sorbed onto montmorillonite. Results suggested that humus-coated clay could substantially decrease the potential bioavailability of mercury in soils, which should be considered when assessing risk in mercury-contaminated soils.

  3. Ground Truthing Orbital Clay Mineral Observations with the APXS Onboard Mars Exploration Rover Opportunity

    NASA Technical Reports Server (NTRS)

    Schroeder, C.; Gellert, R.; VanBommel, S.; Clark, B. C.; Ming, D. W.; Mittlefehldt, D. S.; Yen, A. S.

    2016-01-01

    NASA's Mars Exploration Rover Opportunity has been exploring approximately 22 km diameter Endeavour crater since 2011. Its rim segments predate the Hesperian-age Burns formation and expose Noachian-age material, which is associated with orbital Fe3+-Mg-rich clay mineral observations [1,2]. Moving to an orders of magnitude smaller instrumental field of view on the ground, the clay minerals were challenging to pinpoint on the basis of geochemical data because they appear to be the result of near-isochemical weathering of the local bedrock [3,4]. However, the APXS revealed a more complex mineral story as fracture fills and so-called red zones appear to contain more Al-rich clay minerals [5,6], which had not been observed from orbit. These observations are important to constrain clay mineral formation processes. More detail will be added as Opportunity is heading into her 10th extended mission, during which she will investigate Noachian bedrock that predates Endeavour crater, study sedimentary rocks inside Endeavour crater, and explore a fluid-carved gully. ESA's ExoMars rover will land on Noachian-age Oxia Planum where abundant Fe3+-Mg-rich clay minerals have been observed from orbit, but the story will undoubtedly become more complex once seen from the ground.

  4. Structural and sorption characteristics of adsorbed humic acid on clay minerals.

    PubMed

    Wang, Kaijun; Xing, Baoshan

    2005-01-01

    Clay-humic complexes are commonly distributed in natural environments. They play very important roles in regulating the transport and retention of hydrophobic organic contaminants in soils and sediments. This study examined the structural changes of humic acid (HA) after adsorption by clay minerals and determined phenanthrene sorption by clay-humic complexes. Solid- and liquid-state 13C nuclear magnetic resonance (NMR), for the first time, provided direct evidence for HA fractionation during adsorption on mineral surfaces, that is, aliphatic fractions were preferentially adsorbed by clay minerals while aromatic fractions were left in the solution. The ratio of UV absorbance of HA at 465 and 665 nm (E4 to E6 ratio), which is related to aromaticity, corroborated with the NMR results. For both montmorillonite and kaolinite, adsorbed HA fractions had higher sorption linearity (N) and affinity (K(oc)) than the source HA. The K(oc) of adsorbed HA for the clay-humic complexes could be up to several times higher than that of the source HA. This large increase may be contributed by the low polarity of the bound HA. Moreover, for each mineral, the N values of adsorbed HA increased with increasing HA loading. It is believed that HA may develop a more condensed structure on mineral surface at lower HA loading level due to the stronger interactions between HA and mineral surface as a result of close contacts. PMID:15647564

  5. [Analysis of XRD spectral characteristics of soil clay mineral in two typical cultivated soils].

    PubMed

    Zhang, Zhi-Dan; Luo, Xiang-Li; Jiang, Hai-Chao; Li, Qiao; Shen, Cong-Ying; Liu, Hang; Zhou, Ya-Juan; Zhao, Lan-Po; Wang, Ji-Hong

    2014-07-01

    The present paper took black soil and chernozem, the typical cultivated soil in major grain producing area of Northeast, as the study object, and determinated the soil particle composition characteristics of two cultivated soils under the same climate and location. Then XRD was used to study the composition and difference of clay mineral in two kinds of soil and the evolutionary mechanism was explored. The results showed that the two kinds of soil particles were composed mainly of the sand, followed by clay and silt. When the particle accumulation rate reached 50%, the central particle size was in the 15-130 microm interval. Except for black soil profile of Shengli Xiang, the content of clay showed converse sequence to the central particle in two soils. Clay accumulated under upper layer (18.82%) in black soil profile while under caliche layer (17.41%) in chernozem profile. Clay content was the least in parent material horizon except in black profile of Quanyanling. Analysis of clay XRD atlas showed that the difference lied in not only the strength of diffraction peak, but also in the mineral composition. The main contents of black soil and chernozem were both 2 : 1 clay, the composition of black soil was smectite/illite mixed layer-illite-vermiculite and that of chernozem was S/I mixture-illite-montmorillonite, and both of them contained little kaolinite, chlorite, quartz and other primary mineral. This paper used XRD to determine the characteristics of clay minerals comprehensively, and analyzed two kinds of typical cultivated soil comparatively, and it was a new perspective of soil minerals study. PMID:25269317

  6. [Analysis of XRD spectral characteristics of soil clay mineral in two typical cultivated soils].

    PubMed

    Zhang, Zhi-Dan; Luo, Xiang-Li; Jiang, Hai-Chao; Li, Qiao; Shen, Cong-Ying; Liu, Hang; Zhou, Ya-Juan; Zhao, Lan-Po; Wang, Ji-Hong

    2014-07-01

    The present paper took black soil and chernozem, the typical cultivated soil in major grain producing area of Northeast, as the study object, and determinated the soil particle composition characteristics of two cultivated soils under the same climate and location. Then XRD was used to study the composition and difference of clay mineral in two kinds of soil and the evolutionary mechanism was explored. The results showed that the two kinds of soil particles were composed mainly of the sand, followed by clay and silt. When the particle accumulation rate reached 50%, the central particle size was in the 15-130 microm interval. Except for black soil profile of Shengli Xiang, the content of clay showed converse sequence to the central particle in two soils. Clay accumulated under upper layer (18.82%) in black soil profile while under caliche layer (17.41%) in chernozem profile. Clay content was the least in parent material horizon except in black profile of Quanyanling. Analysis of clay XRD atlas showed that the difference lied in not only the strength of diffraction peak, but also in the mineral composition. The main contents of black soil and chernozem were both 2 : 1 clay, the composition of black soil was smectite/illite mixed layer-illite-vermiculite and that of chernozem was S/I mixture-illite-montmorillonite, and both of them contained little kaolinite, chlorite, quartz and other primary mineral. This paper used XRD to determine the characteristics of clay minerals comprehensively, and analyzed two kinds of typical cultivated soil comparatively, and it was a new perspective of soil minerals study.

  7. Clay-mineral suites, sources, and inferred dispersal routes: Southern California continental shelf.

    PubMed

    Hein, James R; Dowling, Jennifer S; Schuetze, Anthony; Lee, Homa J

    2003-01-01

    Clay mineralogy is useful in determining the distribution, sources, and dispersal routes of fine-grained sediments. In addition, clay minerals, especially smectite, may control the degree to which contaminants are adsorbed by the sediment. We analyzed 250 shelf sediment samples, 24 river-suspended-sediment samples, and 12 river-bed samples for clay-mineral contents in the Southern California Borderland from Point Conception to the Mexico border. In addition, six samples were analyzed from the Palos Verdes Headland in order to characterize the clay minerals contributed to the offshore from that point source. The <2 microm-size fraction was isolated, Mg-saturated, and glycolated before analysis by X-ray diffraction. Semi-quantitative percentages of smectite, illite, and kaolinite plus chlorite were calculated using peak areas and standard weighting factors. Most fine-grained sediment is supplied to the shelf by rivers during major winter storms, especially during El Niño years. The largest sediment fluxes to the region are from the Santa Ynez and Santa Clara Rivers, which drain the Transverse Ranges. The mean clay-mineral suite for the entire shelf sediment data set (26% smectite, 50% illite, 24% kaolinite+chlorite) is closely comparable to that for the mean of all the rivers (31% smectite, 49% illite, 20% kaolinite+chlorite), indicating that the main source of shelf fine-grained sediments is the adjacent rivers. However, regional variations do exist and the shelf is divided into four provinces with characteristic clay-mineral suites. The means of the clay-mineral suites of the two southernmost provinces are within analytical error of the mineral suites of adjacent rivers. The next province to the north includes Santa Monica Bay and has a suite of clay minerals derived from mixing of fine-grained sediments from several sources, both from the north and south. The northernmost province clay-mineral suite matches moderately well that of the adjacent rivers, but does

  8. Clay-mineral suites, sources, and inferred dispersal routes: Southern California continental shelf

    USGS Publications Warehouse

    Hein, J.R.; Dowling, J.S.; Schuetze, A.; Lee, H.J.

    2003-01-01

    Clay mineralogy is useful in determining the distribution, sources, and dispersal routes of fine-grained sediments. In addition, clay minerals, especially smectite, may control the degree to which contaminants are adsorbed by the sediment. We analyzed 250 shelf sediment samples, 24 river-suspended-sediment samples, and 12 river-bed samples for clay-mineral contents in the Southern California Borderland from Point Conception to the Mexico border. In addition, six samples were analyzed from the Palos Verdes Headland in order to characterize the clay minerals contributed to the offshore from that point source. The <2 ??m-size fraction was isolated, Mg-saturated, and glycolated before analysis by X-ray diffraction. Semi-quantitative percentages of smectite, illite, and kaolinite plus chlorite were calculated using peak areas and standard weighting factors. Most fine-grained sediment is supplied to the shelf by rivers during major winter storms, especially during El Nin??o years. The largest sediment fluxes to the region are from the Santa Ynez and Santa Clara Rivers, which drain the Transverse Ranges. The mean clay-mineral suite for the entire shelf sediment data set (26% smectite, 50% illite, 24% kaolinite+chlorite) is closely comparable to that for the mean of all the rivers (31% smectite, 49% illite, 20% kaolinite+chlorite), indicating that the main source of shelf fine-grained sediments is the adjacent rivers. However, regional variations do exist and the shelf is divided into four provinces with characteristic clay-mineral suites. The means of the clay-mineral suites of the two southernmost provinces are within analytical error of the mineral suites of adjacent rivers. The next province to the north includes Santa Monica Bay and has a suite of clay minerals derived from mixing of fine-grained sediments from several sources, both from the north and south. The northernmost province clay-mineral suite matches moderately well that of the adjacent rivers, but does

  9. Molecular Basis of Clay Mineral Structure and Dynamics in Subsurface Engineering Applications

    NASA Astrophysics Data System (ADS)

    Cygan, R. T.

    2015-12-01

    Clay minerals and their interfaces play an essential role in many geochemical, environmental, and subsurface engineering applications. Adsorption, dissolution, precipitation, nucleation, and growth mechanisms, in particular, are controlled by the interplay of structure, thermodynamics, kinetics, and transport at clay mineral-water interfaces. Molecular details of these processes are typically beyond the sensitivity of experimental and analytical methods, and therefore require accurate models and simulations. Also, basal surfaces and interlayers of clay minerals provide constrained interfacial environments to facilitate the evaluation of these complex processes. We have developed and used classical molecular and quantum methods to examine the complex behavior of clay mineral-water interfaces and dynamics of interlayer species. Bulk structures, swelling behavior, diffusion, and adsorption processes are evaluated and compared to experimental and spectroscopic findings. Analysis of adsorption mechanisms of radionuclides on clay minerals provides a scientific basis for predicting the suitability of engineered barriers associated with nuclear waste repositories and the fate of contaminants in the environment. Similarly, the injection of supercritical carbon dioxide into geological reservoirs—to mitigate the impact of climate change—is evaluated by molecular models of multi-fluid interactions with clay minerals. Molecular dynamics simulations provide insights into the wettability of different fluids—water, electrolyte solutions, and supercritical carbon dioxide—on clay surfaces, and which ultimately affects capillary fluid flow and the integrity of shale caprocks. This work is supported as part of Center for Frontiers of Subsurface Energy Security, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science and by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Geosciences Research Program

  10. Manganese(II)-catalyzed and clay-minerals-mediated reduction of chromium(VI) by citrate.

    PubMed

    Sarkar, Binoy; Naidu, Ravi; Krishnamurti, Gummuluru S R; Megharaj, Mallavarapu

    2013-01-01

    Unlike lower valent iron (Fe), the potential role of lower valent manganese (Mn) in the reduction of hexavalent chromium (Cr(VI)) in soil is poorly documented. In this study, we report that citrate along with Mn(II) and clay minerals (montmorillonite and kaolinite) reduce Cr(VI) both in aqueous phase and in the presence of dissolved organic carbon (SDOC) extracted from a forest soil. The reduction was favorable at acidic pH (up to pH 5) and followed the pseudo-first-order kinetic model. The citrate (10 mM) + Mn(II) (182.02 μM) + clay minerals (3% w/v) system in SDOC accounted for complete reduction of Cr(VI) (192.32 μM) in about 72 h at pH 4.9. In this system, citrate was the reductant, Mn(II) was a catalyst, and the clay minerals acted as an accelerator for both the reductant and catalyst. The clay minerals also serve as a sink for Cr(III). This study reveals the underlying mechanism of the Mn(II)-induced reduction of Cr(VI) by organic ligand in the presence of clay minerals under certain environmental conditions.

  11. Characterization of Heat-treated Clay Minerals in the Context of Nuclear Waste Disposal

    NASA Astrophysics Data System (ADS)

    Matteo, E. N.; Wang, Y.; Kruichak, J. N.; Mills, M. M.

    2015-12-01

    Clay minerals are likely candidates to aid in nuclear waste isolation due to their low permeability, favorable swelling properties, and high cation sorption capacities. Establishing the thermal limit for clay minerals in a nuclear waste repository is a potentially important component of repository design, as flexibility of the heat load within the repository can have a major impact on the selection of repository design. For example, the thermal limit plays a critical role in the time that waste packages would need to cool before being transferred to the repository. Understanding the chemical and physical changes, if any, that occur in clay minerals at various temperatures above the current thermal limit (of 100 °C) can enable decision-makers with information critical to evaluating the potential trade-offs of increasing the thermal limit within the repository. Most critical is gaining understanding of how varying thermal conditions in the repository will impact radionuclide sorption and transport in clay materials either as engineered barriers or as disposal media. A variety of repository-relevant clay minerals (illite, mixed layer illite/smectite, and montmorillonite), were heated for a range of temperatures between 100-1000 °C. These samples were characterized to determine surface area, mineralogical alteration, and cation exchange capacity (CEC). Our results show that for conditions up to 500 °C, no significant change occurs, so long as the clay mineral remains mineralogically intact. At temperatures above 500 °C, transformation of the layered silicates into silica phases leads to alteration that impacts important clay characteristics. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's Nation Nuclear Security Administration under contract DE-AC04-94AL85000. SAND Number: SAND2015-6524 A

  12. Interaction of surface-modified silica nanoparticles with clay minerals

    NASA Astrophysics Data System (ADS)

    Omurlu, Cigdem; Pham, H.; Nguyen, Q. P.

    2016-05-01

    In this study, the adsorption of 5-nm silica nanoparticles onto montmorillonite and illite is investigated. The effect of surface functionalization was evaluated for four different surfaces: unmodified, surface-modified with anionic (sulfonate), cationic (quaternary ammonium (quat)), and nonionic (polyethylene glycol (PEG)) surfactant. We employed ultraviolet-visible spectroscopy to determine the concentration of adsorbed nanoparticles in conditions that are likely to be found in subsurface reservoir environments. PEG-coated and quat/PEG-coated silica nanoparticles were found to significantly adsorb onto the clay surfaces, and the effects of electrolyte type (NaCl, KCl) and concentration, nanoparticle concentration, pH, temperature, and clay type on PEG-coated nanoparticle adsorption were studied. The type and concentration of electrolytes were found to influence the degree of adsorption, suggesting a relationship between the interlayer spacing of the clay and the adsorption ability of the nanoparticles. Under the experimental conditions reported in this paper, the isotherms for nanoparticle adsorption onto montmorillonite at 25 °C indicate that adsorption occurs less readily as the nanoparticle concentration increases.

  13. Exploring biotic vs. abiotic controls on syngenetic carbonate and clay mineral precipitation

    NASA Astrophysics Data System (ADS)

    Nascimento, Gabriela S.; McKenzie, Judith A.; Martinez Ruiz, Francisca; Bontognali, Tomaso R. R.; Vasconcelos, Crisogono

    2016-04-01

    A possible syngenetic relationship between carbonate and clay mineral precipitation has been reported for sedimentary rocks deposited in both lacustrine and marine sedimentary environments throughout the geological record. In particular, the mineral dolomite is often found associated with Mg-rich clays, such as stevensite. It is notable that this carbonate/clay association has been recorded in numerous samples taken from modern dolomite precipitating environments; for example, the Coorong lakes, South Australia, coastal sabkhas, Abu Dhabi, UAE and coastal hypersaline lagoons (Lagoa Vermelha and Brejo do Espinho) east of Rio de Janeiro, Brazil. An HRTEM study of samples from these three locations indicates a possible physical/chemical association between the Ca-dolomite and Mg-rich clays, demonstrating a probable co-precipitation. To test this hypothesis, we have conducted a series of biotic and abiotic laboratory experiments. If this syngenesis actually occurs in nature, what, if any, are the biogeochemical processes controlling these precipitation reactions? Our experiments were designed to determine the extent of the biotic versus abiotic component influencing the mineral precipitation and, in the case of a biotic influence, to understand the mechanism through which microorganisms might mediate the formation of clay minerals. The experiments were carried out in the Geomicrobiology Laboratory of ETH Zürich using cultures of living microbes and artificial organic compounds that simulate functional groups present in natural biofilms formed under both aerobic and anaerobic conditions. In addition, pure inorganic experiments were designed to understand possible physico-chemical conditions for diagenetic processes that could induce dissolution of Mg-carbonates and precipitation of Mg-rich clays. Our results show a remarkable biotic influence during the formation of clay minerals. Specifically, extracellular polymeric substances (EPS), released by microbes in their

  14. Atom exchange between aqueous Fe(II) and structural Fe in clay minerals.

    PubMed

    Neumann, Anke; Wu, Lingling; Li, Weiqiang; Beard, Brian L; Johnson, Clark M; Rosso, Kevin M; Frierdich, Andrew J; Scherer, Michelle M

    2015-03-01

    Due to their stability toward reductive dissolution, Fe-bearing clay minerals are viewed as a renewable source of Fe redox activity in diverse environments. Recent findings of interfacial electron transfer between aqueous Fe(II) and structural Fe in clay minerals and electron conduction in octahedral sheets of nontronite, however, raise the question whether Fe interaction with clay minerals is more dynamic than previously thought. Here, we use an enriched isotope tracer approach to simultaneously trace Fe atom movement from the aqueous phase to the solid ((57)Fe) and from the solid into the aqueous phase ((56)Fe). Over 6 months, we observed a significant decrease in aqueous (57)Fe isotope fraction, with a fast initial decrease which slowed after 3 days and stabilized after about 50 days. For the aqueous (56)Fe isotope fraction, we observed a similar but opposite trend, indicating that Fe atom movement had occurred in both directions: from the aqueous phase into the solid and from the solid into aqueous phase. We calculated that 5-20% of structural Fe in clay minerals NAu-1, NAu-2, and SWa-1 exchanged with aqueous Fe(II), which significantly exceeds the Fe atom layer exposed directly to solution. Calculations based on electron-hopping rates in nontronite suggest that the bulk conduction mechanism previously demonstrated for hematite1 and suggested as an explanation for the significant Fe atom exchange observed in goethite2 may be a plausible mechanism for Fe atom exchange in Fe-bearing clay minerals. Our finding of 5-20% Fe atom exchange in clay minerals indicates that we need to rethink how Fe mobility affects the macroscopic properties of Fe-bearing phyllosilicates and its role in Fe biogeochemical cycling, as well as its use in a variety of engineered applications, such as landfill liners and nuclear repositories.

  15. Role of clay minerals in the formation of atmospheric aggregates of Saharan dust

    NASA Astrophysics Data System (ADS)

    Cuadros, Javier; Diaz-Hernandez, José L.; Sanchez-Navas, Antonio; Garcia-Casco, Antonio

    2015-11-01

    Saharan dust can travel long distances in different directions across the Atlantic and Europe, sometimes in episodes of high dust concentration. In recent years it has been discovered that Saharan dust aerosols can aggregate into large, approximately spherical particles of up to 100 μm generated within raindrops that then evaporate, so that the aggregate deposition takes place most times in dry conditions. These aerosol aggregates are an interesting phenomenon resulting from the interaction of mineral aerosols and atmospheric conditions. They have been termed "iberulites" due to their discovery and description from aerosol deposits in the Iberian Peninsula. Here, these aggregates are further investigated, in particular the role of the clay minerals in the aggregation process of aerosol particles. Iberulites, and common aerosol particles for reference, were studied from the following periods or single dust events and locations: June 1998 in Tenerife, Canary Islands; June 2001 to August 2002, Granada, Spain; 13-20 August 2012, Granada; and 1-6 June 2014, Granada. Their mineralogy, chemistry and texture were analysed using X-ray diffraction, electron microprobe analysis, SEM and TEM. The mineral composition and structure of the iberulites consists of quartz, carbonate and feldspar grains surrounded by a matrix of clay minerals (illite, smectite and kaolinite) that also surrounds the entire aggregate. Minor phases, also distributed homogenously within the iberulites, are sulfates and Fe oxides. Clays are apparently more abundant in the iberulites than in the total aerosol deposit, suggesting that iberulite formation concentrates clays. Details of the structure and composition of iberulites differ from descriptions of previous samples, which indicates dependence on dust sources and atmospheric conditions, possibly including anthropic activity. Iberulites are formed by coalescence of aerosol mineral particles captured by precursor water droplets. The concentration of

  16. Reduction And Immobilization Of Hexavalent Chromium By Microbially Reduced Fe-bearing Clay Minerals

    SciTech Connect

    Bishop, Michael E.; Glasser, Paul; Dong, Hailiang; Arey, Bruce W.; Kovarik, Libor

    2014-05-15

    Hexavalent chromium (Cr6+) is a major contaminant in the environment. As a redox-sensitive element, the fate and toxicity of chromium is controlled by reduction-oxidation (redox) reactions. Previous research has shown the ability of structural Fe(II) in naturally present and chemically reduced clay minerals to reduce Cr6+ to Cr(III) as a way of immobilization and detoxification. However, it is still poorly known whether or not structural Fe(II) in biologically reduced clay minerals exhibits a similar reactivity and if so, what the kinetics and mechanisms of Cr6+ reduction are. The objective of this study was to determine the kinetics and possible mechanisms of Cr6+ reduction by structural Fe(II) in microbially reduced clay minerals and the nature of reduced Cr(III). Structural Fe(III) in nontronite (NAu-2), montmorillonite (SWy-2), chlorite (CCa-2), and clay-rich sediments from the Ringold Formation of the Hanford site of Washington State, USA was first bioreduced to Fe(II) by an iron-reducing bacterium Geobacter sulfurreducens with acetate as the sole electron donor and anthraquinone-2,6-disulfate (AQDS) as electron shuttle in synthetic groundwater (pH 7). Biogenic Fe(II) was then used to reduce aqueous Cr6+ at three different temperatures, 10°, 20°, and 30°C, in order to determine the temperature dependence of the redox reaction between Cr6+ and clay-Fe(II). The results showed that nontronite and montmorillonite were most effective in reducing aqueous Cr6+ at all three temperatures. In contrast, most Fe(II) in chlorite was not reactive towards Cr6+ reduction at 10°C, though at 30°C there was some reduction. For all the clay minerals, the ratio of total Fe(II) oxidized to Cr6+ reduced was close to the expected stoichiometric value of 3. Characterization of the Cr-clay reaction product with scanning electron microscopy with focused ion beam and transmission electron microscopy with electron energy loss spectroscopy revealed that reduced chromium was possibly

  17. Reduction and immobilization of hexavalent chromium by microbially reduced Fe-bearing clay minerals

    NASA Astrophysics Data System (ADS)

    Bishop, Michael E.; Glasser, Paul; Dong, Hailiang; Arey, Bruce; Kovarik, Libor

    2014-05-01

    Hexavalent chromium (Cr6+) is a major contaminant in the environment. As a redox-sensitive element, the fate and toxicity of chromium is controlled by reduction-oxidation (redox) reactions. Previous research has shown the ability of structural Fe(II) in naturally present and chemically reduced clay minerals to reduce Cr6+ to Cr(III) as a way of immobilization and detoxification. However, it is still poorly known whether or not structural Fe(II) in biologically reduced clay minerals exhibits a similar reactivity and if so, what the kinetics and mechanisms of Cr6+ reduction are. The objective of this study was to determine the kinetics and possible mechanisms of Cr6+ reduction by structural Fe(II) in microbially reduced clay minerals and the nature of reduced Cr(III). Structural Fe(III) in nontronite (NAu-2), montmorillonite (SWy-2), chlorite (CCa-2), and clay-rich sediments from the Ringold Formation of the Hanford site of Washington State, USA was first bioreduced to Fe(II) by an iron-reducing bacterium Geobacter sulfurreducens with acetate as the sole electron donor and anthraquinone-2,6-disulfonate (AQDS) as electron shuttle in synthetic groundwater (pH 7). Biogenic Fe(II) was then used to reduce aqueous Cr6+ at three different temperatures, 10, 20, and 30 °C, in order to determine the temperature dependence of the redox reaction between Cr6+ and clay-Fe(II). The results showed that nontronite and montmorillonite were most effective in reducing aqueous Cr6+ at all three temperatures. In contrast, most Fe(II) in chlorite was not reactive towards Cr6+ reduction at 10 °C, though at 30 °C there was some reduction. For all the clay minerals, the ratio of total Fe(II) oxidized to Cr6+ reduced was close to the expected stoichiometric value of 3. Characterization of the Cr-clay reaction product with scanning electron microscopy with focused ion beam and transmission electron microscopy with electron energy loss spectroscopy revealed that reduced chromium was possibly

  18. Implications of Clay Mineral-RNA Interactions for the Origin of Life

    NASA Astrophysics Data System (ADS)

    Stephenson, J. D.; Ditzler, M. A.

    2014-12-01

    Due to its ability to both store information and catalyze reactions, RNA is considered by many to have been the dominant biopolymer at the origin of life. We are screening a large, random RNA population for catalytic activity in the presence and absence of prebiotically relevant clay minerals, to investigate the effect of RNA-clay mineral interactions on RNA function. There is an extensive precedent for screening RNA populations for enzymatic functions such as ligation, cleavage and binding in the laboratory. While several environmental parameters have been explored, previous screens have not considered geological interactions. This is surprising as the role of clay minerals has featured prominently in many origin of life theories. Recent empirical evidence demonstrating that clay minerals can adsorb and protect RNA molecules as well as catalyze RNA polymerization has specifically reinvigorated the proposed importance of clay mineral-RNA interactions. Although the identity of the first true biomolecules remains uncertain, interaction between emerging life and its geological environment appears inevitable. We therefore consider understanding the effect of geological-biological interactions to be of crucial importance when considering the earliest biopolymers at the origin of life. Our screens are from a random population of 10^14 unique random RNA sequences and are conducted with and without montmorillonite clay. We are screening for the ability of sequences to self cleave, one of the most basic enzymatic functions considered important to the earliest biopolymers. Our RNA function screens will therefore illuminate the effect of geological interactions at a crucial stage of early evolution.

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

    NASA Astrophysics Data System (ADS)

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

    2012-09-01

    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.

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

    PubMed

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

    2013-09-10

    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.

  1. Si isotopes record cyclical dissolution and re-precipitation of pedogenic clay minerals in a podzolic soil chronosequence

    NASA Astrophysics Data System (ADS)

    Cornelis, Jean-Thomas; Weis, Dominique; Lavkulich, Les; Vermeire, Marie-Liesse; Delvaux, Bruno; Barling*, Jane

    2014-05-01

    Soils are a major resource on the planet, acting as a key component for ecosystem function. The secondary minerals in the clay fraction are important players in soil biogeochemical processes as they provide a large reactive surface area. However, the origin and evolution of secondary minerals in soils are not yet fully understood. We determined the Si isotope compositions in the clay fraction of a podzolic soil chronosequence and document light 28Si enrichment during pedogenesis that increases with soil age. Relative to the original 'unweathered' clay-size minerals in deepsoil (δ30Si = -0.52±0.16 permil), the clay fraction of the topsoil eluvial horizon show less negative δ30Si values (δ30Sifrom -0.33 to -0.10 permil), while the clay fraction of the subsoil illuvial horizons is isotopically lighter (δ30Si from -0.60 to -0.84 permil). Geochemical and X-ray diffraction analyses show that the on-going enrichment in light 28Si in pedogenic minerals of illuvial subsoil horizons can only be related to the dissolution in the topsoil horizon of clay minerals previously enriched in 28Si. The 28Si enrichment in the clay fraction with pedogenesis and soil age provides consistent evidence for the cyclical dissolution and re-precipitation of pedogenic minerals. Our study shows that the successive generations of clay minerals occur over very short time scales (ca. 300 years). This is instrumental in the evolution of the clay mineral genesis in soils. This soil-forming process has implications for the modeling of soil evolution. Given the importance of clay minerals in the chemical cycles of elements, deciphering the origin of pedogenic Si in clay mineral genesis is central to a better understanding of soil development and associated terrestrial biogeochemical processes.

  2. Effect of purity on adsorption capacities of a Mars-like clay mineral at different pressures

    NASA Technical Reports Server (NTRS)

    Jenkins, Traci; Mcdoniel, Bridgett; Bustin, Roberta; Allton, Judith H.

    1992-01-01

    There has been considerable interest in adsorption of carbon dioxide on Marslike clay minerals. Some estimates of the carbon dioxide reservoir capacity of the martian regolith were calculated from the amount of carbon dioxide adsorbed on the ironrich smectite nontronite under martian conditions. The adsorption capacity of pure nontronite could place upper limits on the regolith carbon dioxide reservoir, both at present martian atmospheric pressure and at the postulated higher pressures required to permit liquid water on the surface. Adsorption of carbon dioxide on a Clay Mineral Society standard containing nontronite was studied over a wide range of pressures in the absence of water. Similar experiments were conducted on the pure nontronite extracted from the natural sample. Heating curves were obtained to help characterize and determine the purity of the clay sample.

  3. Investigating the behaviour of Mg isotopes during the formation of clay minerals

    NASA Astrophysics Data System (ADS)

    Wimpenny, Joshua; Colla, Christopher A.; Yin, Qing-Zhu; Rustad, James R.; Casey, William H.

    2014-03-01

    We present elemental and isotopic data detailing how the Mg isotope system behaves in natural and experimentally synthesized clay minerals. We show that the bulk Mg isotopic composition (δ26Mg) of a set of natural illite, montmorillonite and kaolinite spans a 2‰ range, and that their isotopic composition depends strongly on a balance between the relative proportions of structural and exchangeable Mg. After acid leaching, these natural clays become relatively enriched in isotopically heavy Mg by between 0.2‰ and 1.6‰. Results of exchange experiments indicate that the Mg that has adsorbed to interlayer spaces and surface charged sites is relatively enriched in isotopically light Mg compared to the residual clay. The isotopic composition of this exchangeable Mg (-1.49‰ to -2.03‰) is characteristic of the isotopic composition of Mg found in many natural waters. Further experiments with an isotopically characterized MgCl2 solution shows that the clay minerals adsorb this exchangeable Mg with little or no isotopic fractionation, although we cannot discount the possibility that the uptake of exchangeable Mg does so with a slight preference for 24Mg. To characterize the behaviour of Mg isotopes during clay mineral formation we synthesized brucite (Mg(OH)2), which we consider to be a good analogue for the incorporation of Mg into the octahedral sheet of Mg-rich clay minerals or into the brucitic layer of clays such as chlorite. In our experiment the brucite mineral becomes enriched in the heavy isotopes of Mg while the corresponding solution is always relatively enriched in isotopically light Mg. The system reaches a steady state after 10 days with a final fractionation factor (αsolid-solution) of 1.0005 at near-neutral pH. This result is consistent with the general consensus that secondary clay minerals preferentially take up isotopically heavy Mg during their formation. However our results also show that exchangeable Mg is an important component within bulk

  4. Chemistry and mineralogy of clay minerals in Asian and Saharan dusts and the implications for iron availability

    NASA Astrophysics Data System (ADS)

    Jeong, G. Y.; Achterberg, E. P.

    2014-06-01

    Mineral dust supplied to remote ocean regions stimulates phytoplankton growth through delivery of micronutrients, notably iron (Fe). Although attention is usually paid to Fe (hydr)oxides as major sources of available Fe, Fe-bearing clay minerals are typically the dominant phase in mineral dust. The mineralogy and chemistry of clay minerals in dust particles, however, are largely unknown. We conducted microscopic identification and chemical analysis of the clay minerals in Asian and Saharan dust particles. Cross-sectional slices of dust particles were prepared by focused ion beam (FIB) techniques and analyzed by transmission electron microscopy (TEM) combined with energy dispersive X-ray spectroscopy (EDXS). TEM images of FIB slices revealed that clay minerals occurred as either nano-thin platelets or relatively thick plates. The nano-thin platelets included illite, smectite, illite-smectite mixed layers and their nanoscale mixtures (illite-smectite series clay minerals, ISCMs) which could not be resolved with an electron microbeam. EDXS chemical analysis of the clay mineral grains revealed that the average Fe content was 5.8% in nano-thin ISCM platelets assuming 14% H2O, while the Fe content of illite and chlorite was 2.8 and 14.8%, respectively. In addition, TEM and EDXS analyses were performed on clay mineral grains dispersed and loaded on microgrids. The average Fe content of clay mineral grains was 6.7 and 5.4% in Asian and Saharan dusts, respectively. A comparative X-ray diffraction analysis of bulk dusts showed that Saharan dust was more enriched in clay minerals than in Asian dust, while Asian dust was more enriched in chlorite. The average Fe / Si, Al / Si and Fe / Al molar ratios of the clay minerals, compared to previously reported chemistries of mineral dusts and leached solutions, indicated that dissolved Fe originated from clay minerals. Clay minerals, in particular nanocrystalline ISCMs and Fe-rich chlorite are important sources of available Fe in

  5. Thermal behavior of water confined in micro porous of clay mineral at additional pressure.

    NASA Astrophysics Data System (ADS)

    Ito, Y.; Takemura, T.; Fujimori, H.; Nagoe, A.; Sugimoto, T.

    2014-12-01

    Water is the most familiar substance. However water has specific properties that has a crystal structure of a dozen and density of that is maximum at 277.15 K. Therefore it understands various natural phenomena to study physical properties of water. Oodo et al study physical properties of water confined in silica gel [1]. They indicate that melting point of water confined in silica gel decrease with decreasing pore size of silica gel. Also in case that pore size is less than 2 nm, water confined in silica gel is unfreezing water at low temperature. It is considered that effect of pore size prevent crystal growth of water. Therefore we are interested in water confined in clay minerals. Clay minerals have a number of water conditions. Also it is thought that water confined in clay minerals show different physical behavior to exist the domain where change with various effect. Therefore we studied a thermal properties and phase behavior of absorption water in clay minerals. In addition, we analyzed the changes in the thermal behavior of absorption water due to the effect of earth pressure that was an environmental factor in the ground. [1] Oodo & Fujimori, J. Non-Cryst. Solids, 357 (2011) 683.

  6. Modeling selenate adsorption behavior on oxides, clay minerals, and soils using the triple layer model

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Selenate adsorption behavior was investigated on amorphous aluminum oxide, amorphous iron oxide, goethite, clay minerals: kaolinites, montmorillonites, illite, and 18 soil samples from Hawaii, and the Southwestern and the Midwestern regions of the US as a function of solution pH. Selenate adsorpti...

  7. Modeling selenite adsorption envelopes on oxides, clay minerals, and soils using the triple layer model

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Selenite adsorption behavior was investigated on amorphous aluminum and iron oxides, clay minerals: kaolinite, montmorillonite, and illite, and 45 surface and subsurface soil samples from the Southwestern and Midwestern regions of the USA as a function of solution pH. Selenite adsorption decreased ...

  8. Clay minerals in primitive meteorites and interplanetary dust 1

    NASA Technical Reports Server (NTRS)

    Zolensky, M. E.; Keller, L. P.

    1991-01-01

    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 system. These meteorites are chondrites (near solar composition) of the carbonaceous and ordinary varieties. The former are subdivided (according to bulk composition and petrology) into CI, CM, CV, CO, CR, and ungrouped classes. IDPs are extraterrestrial particulates, collected in stratosphere, which have chemical compositions indicative of a primitive origin; they are typically distinct from the primitive meteorites. Characterization of phyllosilicates in these materials is a high priority because of the important physico-chemical information they hold. The most common phyllosilicates present in chondritic extraterrestrial materials are serpentine-group minerals, smectites, and micas. We discuss these phyllosilicates and describe the interpretation of their occurrence in meteorites and IDPs and what this indicates about history of their parent bodies, which are probably the hydrous asteroids.

  9. Is the geological concept of clay minerals appropriate for soil science? A literature-based and philosophical analysis

    NASA Astrophysics Data System (ADS)

    Churchman, G. Jock

    Data in the literature for soils that are dominated by each of the main types of clay minerals were examined and compared with those for reference clay minerals of the same types to determine the extent to which the nature and properties of clay-size minerals in soils could be explained by those of clay minerals with the same name from non-soil, ‘geological’ environments. Published information on soils from Australia, New Zealand and Iran was sourced for this study. The clay fractions of each of the soils are dominated by either one of the common phyllosilicates: kaolinite, halloysite, illite/mica, vermiculite, smectite, and palygorskite, or by the nanocrystalline mineral, allophane. Data for samples of kaolinite that had been extracted from soils from several countries (Australia, Thailand, Indonesia and Brazil) and purified before characterization have also been examined. In soils, each dominant clay mineral is generally associated with other materials, including iron oxides, other phyllosilicates and/or nanocrystalline minerals and organic matter. As the most studied example of an extracted phyllosilicate, kaolinite shows a wide range of properties in different soils, but a narrower range of properties within a particular locality. However, almost all of the soil kaolinites studied have larger specific surface areas and higher cation exchange capacities than reference kaolinites. The literature also reveals that, among phyllosilicates in soils, illites have a wide range of potassium contents, expandable minerals (vermiculites and smectites) may be interlayered by hydroxy-Al species particularly, and smectitic layers often occur interstratified with other layers, including those of illite, kaolinite and halloysite. The variability of soil phyllosilicates and their common association with other, often poorly crystallized but highly reactive minerals and compounds can be explained by their formation in the highly heterogeneous and dynamic soil environment

  10. Can clay minerals account for the non-asperity on the subducting plate interface?

    NASA Astrophysics Data System (ADS)

    Katayama, I.; Kubo, T.; Sakuma, H.; Kawai, K.

    2014-12-01

    Seismicity along the subducting plate interface shows a regional variation, in which large earthquakes occur repeatedly at the strongly coupled patches that are surrounded by weakly coupled regions. This model suggests that the subduction plate interface is heterogeneous in terms of frictional properties; however, mechanism making the difference in strong and weak coupling is still not well understood. We consider this difference to relate to the alternation of plate interface due to aqueous fluids that result in the spatial distribution of clay minerals. In order to test this hypothesis, we measured frictional healing of clay minerals and discuss whether the frictional properties of clays can account for the weakly coupled non-asperity regions in the subducting plate interface. We carried out a series of slide-hold-slide frictional experiments to examine the time-dependent frictional restrengthening of the simulated fault gouge. In the experiments, the axial loading was interrupted for periods ranging 10 to 3000 s after steady-state friction, and we measured the difference between the steady-state friction and the peak friction after each holding period. The preliminary results show that the frictional strength of clay minerals (saponite, illite and chlorite) slightly increases with holding time; however, the healing rate is significantly smaller than that of dry silicates such as quartz. Similar weak healing rate has been reported in the serpentinized simulated faults (Katayama et al. 2013). These experimental results suggest that the recovery of fault strength is different in materials, in which clay minerals show weak and slow recovery whereas dry materials show relatively quick and thereby strong coupling on the fault surface. Aqueous fluids that are released from the descending plate may change the mineralogy on the plate interface where clay minerals become dominant at the channel of fluid flow surrounding the unaltered dry patches that potentially act as a

  11. Cesium adsorption/desorption behavior of clay minerals considering actual contamination conditions in Fukushima

    PubMed Central

    Mukai, Hiroki; Hirose, Atsushi; Motai, Satoko; Kikuchi, Ryosuke; Tanoi, Keitaro; Nakanishi, Tomoko M.; Yaita, Tsuyoshi; Kogure, Toshihiro

    2016-01-01

    Cesium adsorption/desorption experiments for various clay minerals, considering actual contamination conditions in Fukushima, were conducted using the 137Cs radioisotope and an autoradiography using imaging plates (IPs). A 50 μl solution containing 0.185 ~ 1.85 Bq of 137Cs (10−11 ~ 10−9 molL−1 of 137Cs) was dropped onto a substrate where various mineral particles were arranged. It was found that partially-vermiculitized biotite, which is termed “weathered biotite” (WB) in this study, from Fukushima sorbed 137Cs far more than the other clay minerals (fresh biotite, illite, smectite, kaolinite, halloysite, allophane, imogolite) on the same substrate. When WB was absent on the substrate, the amount of 137Cs sorbed to the other clay minerals was considerably increased, implying that selective sorption to WB caused depletion of radiocesium in the solution and less sorption to the coexisting minerals. Cs-sorption to WB continued for about one day, whereas that to ferruginous smectite was completed within one hour. The sorbed 137Cs in WB was hardly leached with hydrochloric acid at pH 1, particularly in samples with a longer sorption time. The presence/absence of WB sorbing radiocesium is a key factor affecting the dynamics and fate of radiocesium in Fukushima. PMID:26868138

  12. Cesium adsorption/desorption behavior of clay minerals considering actual contamination conditions in Fukushima

    NASA Astrophysics Data System (ADS)

    Mukai, Hiroki; Hirose, Atsushi; Motai, Satoko; Kikuchi, Ryosuke; Tanoi, Keitaro; Nakanishi, Tomoko M.; Yaita, Tsuyoshi; Kogure, Toshihiro

    2016-02-01

    Cesium adsorption/desorption experiments for various clay minerals, considering actual contamination conditions in Fukushima, were conducted using the 137Cs radioisotope and an autoradiography using imaging plates (IPs). A 50 μl solution containing 0.185 ~ 1.85 Bq of 137Cs (10‑11 ~ 10‑9 molL‑1 of 137Cs) was dropped onto a substrate where various mineral particles were arranged. It was found that partially-vermiculitized biotite, which is termed “weathered biotite” (WB) in this study, from Fukushima sorbed 137Cs far more than the other clay minerals (fresh biotite, illite, smectite, kaolinite, halloysite, allophane, imogolite) on the same substrate. When WB was absent on the substrate, the amount of 137Cs sorbed to the other clay minerals was considerably increased, implying that selective sorption to WB caused depletion of radiocesium in the solution and less sorption to the coexisting minerals. Cs-sorption to WB continued for about one day, whereas that to ferruginous smectite was completed within one hour. The sorbed 137Cs in WB was hardly leached with hydrochloric acid at pH 1, particularly in samples with a longer sorption time. The presence/absence of WB sorbing radiocesium is a key factor affecting the dynamics and fate of radiocesium in Fukushima.

  13. Cesium adsorption/desorption behavior of clay minerals considering actual contamination conditions in Fukushima

    NASA Astrophysics Data System (ADS)

    Mukai, Hiroki; Hirose, Atsushi; Motai, Satoko; Kikuchi, Ryosuke; Tanoi, Keitaro; Nakanishi, Tomoko M.; Yaita, Tsuyoshi; Kogure, Toshihiro

    2016-02-01

    Cesium adsorption/desorption experiments for various clay minerals, considering actual contamination conditions in Fukushima, were conducted using the 137Cs radioisotope and an autoradiography using imaging plates (IPs). A 50 μl solution containing 0.185 ~ 1.85 Bq of 137Cs (10-11 ~ 10-9 molL-1 of 137Cs) was dropped onto a substrate where various mineral particles were arranged. It was found that partially-vermiculitized biotite, which is termed “weathered biotite” (WB) in this study, from Fukushima sorbed 137Cs far more than the other clay minerals (fresh biotite, illite, smectite, kaolinite, halloysite, allophane, imogolite) on the same substrate. When WB was absent on the substrate, the amount of 137Cs sorbed to the other clay minerals was considerably increased, implying that selective sorption to WB caused depletion of radiocesium in the solution and less sorption to the coexisting minerals. Cs-sorption to WB continued for about one day, whereas that to ferruginous smectite was completed within one hour. The sorbed 137Cs in WB was hardly leached with hydrochloric acid at pH 1, particularly in samples with a longer sorption time. The presence/absence of WB sorbing radiocesium is a key factor affecting the dynamics and fate of radiocesium in Fukushima.

  14. Cesium adsorption/desorption behavior of clay minerals considering actual contamination conditions in Fukushima.

    PubMed

    Mukai, Hiroki; Hirose, Atsushi; Motai, Satoko; Kikuchi, Ryosuke; Tanoi, Keitaro; Nakanishi, Tomoko M; Yaita, Tsuyoshi; Kogure, Toshihiro

    2016-01-01

    Cesium adsorption/desorption experiments for various clay minerals, considering actual contamination conditions in Fukushima, were conducted using the (137)Cs radioisotope and an autoradiography using imaging plates (IPs). A 50 μl solution containing 0.185 ~ 1.85 Bq of (137)Cs (10(-11) ~ 10(-9 )molL(-1) of (137)Cs) was dropped onto a substrate where various mineral particles were arranged. It was found that partially-vermiculitized biotite, which is termed "weathered biotite" (WB) in this study, from Fukushima sorbed (137)Cs far more than the other clay minerals (fresh biotite, illite, smectite, kaolinite, halloysite, allophane, imogolite) on the same substrate. When WB was absent on the substrate, the amount of (137)Cs sorbed to the other clay minerals was considerably increased, implying that selective sorption to WB caused depletion of radiocesium in the solution and less sorption to the coexisting minerals. Cs-sorption to WB continued for about one day, whereas that to ferruginous smectite was completed within one hour. The sorbed (137)Cs in WB was hardly leached with hydrochloric acid at pH 1, particularly in samples with a longer sorption time. The presence/absence of WB sorbing radiocesium is a key factor affecting the dynamics and fate of radiocesium in Fukushima.

  15. Influence of Water Content on the Mechanical Behaviour of Limestone: Role of the Clay Minerals Content

    NASA Astrophysics Data System (ADS)

    Cherblanc, F.; Berthonneau, J.; Bromblet, P.; Huon, V.

    2016-06-01

    The mechanical characteristics of various sedimentary stones significantly depend on the water content, where 70 % loss of their mechanical strengths can be observed when saturated by water. Furthermore, the clay fraction has been shown to be a key factor of their hydro-mechanical behaviour since it governs for instance the hydric dilation. This work aims at investigating the correlations between the clay mineral content and the mechanical weakening experienced by limestones when interacting with water. The experimental characterization focuses on five different limestones that exhibit very different micro-structures. For each of them, we present the determination of clay mineral composition, the sorption isotherm curve and the dependences of tensile and compressive strengths on the water content. It emerges from these results that, first, the sorption behaviour is mainly governed by the amount of smectite layers which exhibit the larger specific area and, second, the rate of mechanical strength loss depends linearly on the sorption capacity. Indeed, the clay fraction plays the role of a retardation factor that delays the appearance of capillary bridges as well as the mechanical weakening of stones. However, no correlation was evidenced between the clay content and the amplitude of weakening. Since the mechanisms whereby the strength decreases with water content are not clearly established, these results would help to discriminate between various hypothesis proposed in the literature.

  16. Neocrystallization, fabrics and age of clay minerals from an exposure of the Moab Fault, Utah

    NASA Astrophysics Data System (ADS)

    Solum, John G.; van der Pluijm, Ben A.; Peacor, Donald R.

    2005-09-01

    Pronounced changes in clay mineral assemblages are preserved along the Moab Fault (Utah). Gouge is enriched up to ˜40% in 1M d illite relative to protolith, whereas altered protolith in the damage zone is enriched ˜40% in illite-smectite relative to gouge and up to ˜50% relative to protolith. These mineralogical changes indicate that clay gouge is formed not solely through mechanical incorporation of protolith, but also through fault-related authigenesis. The timing of mineralization is determined using 40Ar/ 39Ar dating of size fractions of fault rocks with varying detrital and authigenic clay content. We applied Ar dating of illite-smectite samples, as well as a newer approach that uses illite polytypes. Our analysis yields overlapping, early Paleocene ages for neoformed (1M d) gouge illite (63±2 Ma) and illite-smectite in the damage zone (60±2 Ma), which are compatible with results elsewhere. These ages represent the latest period of major fault motion, and demonstrate that the fault fabrics are not the result of recent alteration. The clay fabrics in fault rocks are poorly developed, indicating that fluids were not confined to the fault zone by preferentially oriented clays; rather we propose that fluids in the illite-rich gouge were isolated by adjacent lower permeability, illite-smectite-bearing rocks in the damage zone.

  17. Neocrystallization, fabrics and age of clay minerals from an exposure of the Moab Fault, Utah

    USGS Publications Warehouse

    Solum, J.G.; van der Pluijm, B.A.; Peacor, D.R.

    2005-01-01

    Pronounced changes in clay mineral assemblages are preserved along the Moab Fault (Utah). Gouge is enriched up to ???40% in 1Md illite relative to protolith, whereas altered protolith in the damage zone is enriched ???40% in illite-smectite relative to gouge and up to ???50% relative to protolith. These mineralogical changes indicate that clay gouge is formed not solely through mechanical incorporation of protolith, but also through fault-related authigenesis. The timing of mineralization is determined using 40Ar/39Ar dating of size fractions of fault rocks with varying detrital and authigenic clay content. We applied Ar dating of illite-smectite samples, as well as a newer approach that uses illite polytypes. Our analysis yields overlapping, early Paleocene ages for neoformed (1Md) gouge illite (63??2 Ma) and illite-smectite in the damage zone (60??2 Ma), which are compatible with results elsewhere. These ages represent the latest period of major fault motion, and demonstrate that the fault fabrics are not the result of recent alteration. The clay fabrics in fault rocks are poorly developed, indicating that fluids were not confined to the fault zone by preferentially oriented clays; rather we propose that fluids in the illite-rich gouge were isolated by adjacent lower permeability, illite-smectite-bearing rocks in the damage zone. ?? 2005 Elsevier Ltd. All rights reserved.

  18. Leaching of clay minerals in a limestone environment

    USGS Publications Warehouse

    Carroll, D.; Starkey, H.C.

    1959-01-01

    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.

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

    SciTech Connect

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

    2011-07-01

    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

  20. Genesis of clay mineral assemblages and micropaleoclimatic implications in the Tertiary Powder River Basin, Wyoming

    SciTech Connect

    Flores, R.M.; Weaver, J.N. ); Bossiroy, D.; Thorez, J. )

    1990-05-01

    An x-ray diffraction (XRD) study was undertaken on the clay mineralogy of the early Tertiary coal-bearing sequences of the Powder River basin. The vertical and lateral distribution of alternating fluvial conglomerates, sandstones, mudstones, shales, coals, and paleosols reveals a transition from alluvial fans along the basin margin to an alluvial plain and peat bogs basinward. Samples included unweathered shales and mudstones from a borehole and a variety of corresponding surface outcrop samples of Cambrian to Eocene age. Samples older than Tertiary were collected along the basin margin specifically to determine the potential source of parent material during Tertiary sedimentation. XRD analyses were performed on the <2-{mu}m fraction prepared as oriented aggregates. To investigate the materials in their natural state, no chemical pre-treatments the authors applied before the analysis. A series of specific post-treatments, consisting of catonic saturation (Li+, K+), a solution with polyalcohols, heating, acid attack and hydrazine saturation was selectively applied. These post-treatments permit a good discrimination between the mimetic clay minerals such as smectite and illite-smectite mixed layers that constitute the bulk of the clay fraction in the Tertiary rocks. When analyzed only using routine XRD, these swelling minerals are apparently uniformly distributed in the fluvial sedimentary rocks and are better interpreted as a single smectitic population. However, the post-treatments clearly differentiate both qualitatively and quantitatively this smectitic stock. Other clays include illite and kaolinite, which have different degrees of crystallinity, and minor interstratified clays (i.e., illite-chlorite, chlorite-smectite). The clay minerals in pre-Tertiary (and pedogenic) materials are different from those in the Tertiary rocks.

  1. Modified clay minerals efficiency against chemical and biological warfare agents for civil human protection.

    PubMed

    Plachá, Daniela; Rosenbergová, Kateřina; Slabotínský, Jiří; Kutláková, Kateřina Mamulová; Studentová, Soňa; Martynková, Gražyna Simha

    2014-04-30

    Sorption efficiencies of modified montmorillonite and vermiculite of their mono ionic Na and organic HDTMA and HDP forms were studied against chemical and biological warfare agents such as yperite and selected bacterial strains. Yperite interactions with modified clay minerals were observed through its capture in low-density polyethylene foil-modified clay composites by measuring yperite gas permeation with using chemical indication and gas chromatography methods. The antibacterial activities of synthetized organoclays were tested against selected Gram-positive and Gram-negative bacterial species in minimum inhibitory concentration tests. The obtained results showed a positive influence of modified clay minerals on the significant yperite breakthrough-time increase. The most effective material was the polyethylene-Na form montmorillonite, while the polyethylene-Na form vermiculite showed the lowest efficiency. With increasing organic cations loading in the interlayer space the montmorillonite efficiency decreased, and in the case of vermiculite an opposite effect was observed. Generally the modified montmorillonites were more effective than modified vermiculites. The HDP cations seem to be more effective compare to the HDTMA. The antibacterial activity tests confirmed efficiency of all organically modified clay minerals against Gram-positive bacteria. The confirmation of antibacterial activity against Y. pestis, plague bacteria, is the most interesting result of this part of the study.

  2. Clay mineral distribution and provenance in the Heuksan mud belt, Yellow Sea

    NASA Astrophysics Data System (ADS)

    Cho, Hyen Goo; Kim, Soon-Oh; Kwak, Kyeong Yoon; Choi, Hunsoo; Khim, Boo-Keun

    2015-12-01

    The Heuksan mud belt (HMB), located in the southeastern Yellow Sea, runs parallel to the southwest coast of Korea. In this study, the distribution and relative contribution of four major clay minerals are investigated using 101 surface sediment samples collected in the course of KIOST (2001, 2010, 2011) and KIGAM (2012) cruises, as well as 33 river sediment samples (four from the Huanghe River, three from the Changjiang River, and 26 from Korean rivers) in order to clarify the provenance of fine-grained sediments in the HMB. Based on this currently largest and most robust dataset available for interpretation, the clay mineral assemblages of the fine-grained sediments in the HMB are found to be on average composed of 64.7% illite, 17.9% chlorite, 11.4% kaolinite, and 5.9% smectite. Overall, the clay mineral assemblages are similar in both the northern and the southern parts of the HMB, although smectite seems to be relatively enriched in the southern part, whereas kaolinite is slightly more dominant in the northern part. This clearly indicates that the clays are mostly derived from Korean rivers and, in the southern part of the HMB, partly also from the Huanghe River in China. The new data thus confirm and strengthen the tentative interpretation of some earlier work based on a more limited dataset.

  3. Adsorption of herbicide paraquat by clay mineral regenerated from spent bleaching earth.

    PubMed

    Tsai, Wen-Tien; Lai, Chi-Wei

    2006-06-30

    The adsorption of herbicide paraquat (as model adsorbate) in aqueous solution onto regenerated clay mineral from bleaching earth waste has been studied in a batch reaction system. The adsorption rate has been investigated under the controlled process parameters including initial pH, salinity and temperature. Based on the high affinity between cationic paraquat and clay mineral, a pseudo-second order model has been developed using experimental data to predict the rate constant of adsorption, and equilibrium adsorption capacity. The results showed that the adsorption process could be satisfactorily described with the reaction model and were reasonably explained by assuming a competitive adsorption mechanism in the ion exchange process. Further, the fitted adsorption capacity at equilibrium decreased with increasing temperature. It implied that the strong interaction might play an important role in the paraquat-clay system. Overall, the results from this study demonstrated that the clay resource regenerated from bleaching earth waste could be used as a low-cost mineral adsorbent for the removal of environmental cationic organic pollutants from the aqueous solution.

  4. Bioremediating oil spills in nutrient poor ocean waters using fertilized clay mineral flakes: some experimental constraints.

    PubMed

    Warr, Laurence N; Friese, André; Schwarz, Florian; Schauer, Frieder; Portier, Ralph J; Basirico, Laura M; Olson, Gregory M

    2013-01-01

    Much oil spill research has focused on fertilizing hydrocarbon oxidising bacteria, but a primary limitation is the rapid dilution of additives in open waters. A new technique is presented for bioremediation by adding nutrient amendments to the oil spill using thin filmed minerals comprised largely of Fullers Earth clay. Together with adsorbed N and P fertilizers, filming additives, and organoclay, clay flakes can be engineered to float on seawater, attach to the oil, and slowly release contained nutrients. Our laboratory experiments of microbial activity on weathered source oil from the Deepwater Horizon spill in the Gulf of Mexico show fertilized clay treatment significantly enhanced bacterial respiration and consumption of alkanes compared to untreated oil-in-water conditions and reacted faster than straight fertilization. Whereas a major portion (up to 98%) of the alkane content was removed during the 1 month period of experimentation by fertilized clay flake interaction; the reduced concentration of polyaromatic hydrocarbons was not significantly different from the non-clay bearing samples. Such clay flake treatment could offer a way to more effectively apply the fertilizer to the spill in open nutrient poor waters and thus significantly reduce the extent and duration of marine oil spills, but this method is not expected to impact hydrocarbon toxicity.

  5. Bioremediating oil spills in nutrient poor ocean waters using fertilized clay mineral flakes: some experimental constraints.

    PubMed

    Warr, Laurence N; Friese, André; Schwarz, Florian; Schauer, Frieder; Portier, Ralph J; Basirico, Laura M; Olson, Gregory M

    2013-01-01

    Much oil spill research has focused on fertilizing hydrocarbon oxidising bacteria, but a primary limitation is the rapid dilution of additives in open waters. A new technique is presented for bioremediation by adding nutrient amendments to the oil spill using thin filmed minerals comprised largely of Fullers Earth clay. Together with adsorbed N and P fertilizers, filming additives, and organoclay, clay flakes can be engineered to float on seawater, attach to the oil, and slowly release contained nutrients. Our laboratory experiments of microbial activity on weathered source oil from the Deepwater Horizon spill in the Gulf of Mexico show fertilized clay treatment significantly enhanced bacterial respiration and consumption of alkanes compared to untreated oil-in-water conditions and reacted faster than straight fertilization. Whereas a major portion (up to 98%) of the alkane content was removed during the 1 month period of experimentation by fertilized clay flake interaction; the reduced concentration of polyaromatic hydrocarbons was not significantly different from the non-clay bearing samples. Such clay flake treatment could offer a way to more effectively apply the fertilizer to the spill in open nutrient poor waters and thus significantly reduce the extent and duration of marine oil spills, but this method is not expected to impact hydrocarbon toxicity. PMID:23864952

  6. Bioremediating Oil Spills in Nutrient Poor Ocean Waters Using Fertilized Clay Mineral Flakes: Some Experimental Constraints

    PubMed Central

    Warr, Laurence N.; Friese, André; Schwarz, Florian; Schauer, Frieder; Portier, Ralph J.; Basirico, Laura M.; Olson, Gregory M.

    2013-01-01

    Much oil spill research has focused on fertilizing hydrocarbon oxidising bacteria, but a primary limitation is the rapid dilution of additives in open waters. A new technique is presented for bioremediation by adding nutrient amendments to the oil spill using thin filmed minerals comprised largely of Fullers Earth clay. Together with adsorbed N and P fertilizers, filming additives, and organoclay, clay flakes can be engineered to float on seawater, attach to the oil, and slowly release contained nutrients. Our laboratory experiments of microbial activity on weathered source oil from the Deepwater Horizon spill in the Gulf of Mexico show fertilized clay treatment significantly enhanced bacterial respiration and consumption of alkanes compared to untreated oil-in-water conditions and reacted faster than straight fertilization. Whereas a major portion (up to 98%) of the alkane content was removed during the 1 month period of experimentation by fertilized clay flake interaction; the reduced concentration of polyaromatic hydrocarbons was not significantly different from the non-clay bearing samples. Such clay flake treatment could offer a way to more effectively apply the fertilizer to the spill in open nutrient poor waters and thus significantly reduce the extent and duration of marine oil spills, but this method is not expected to impact hydrocarbon toxicity. PMID:23864952

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

    NASA Technical Reports Server (NTRS)

    Burt, D. M.

    1989-01-01

    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.

  8. Reactive Clay Minerals in a land use sequence of disturbed soils of the Belgian Loam Belt

    NASA Astrophysics Data System (ADS)

    Barao, Lucia; Vandevenne, Floor; Ronchi, Benedicta; Meire, Patrick; Govers, Gerard; Struyf, Eric

    2014-05-01

    Clay minerals play a key role in soil biogeochemistry. They can stabilize organic matter, improve water storage, increase cation exchange capacity of the soil (CEC) and lower nutrient leaching. Phytoliths - the biogenic silica bodies (BSi) deposited in cell walls of plants - are important Si pools in soil horizons due to their higher solubility compared to minerals. They provide the source of Si for plant uptake in short time scales, as litter dissolves within soils. In a recent study, we analyzed the BSi pool differences across a set of different land uses (forests, pastures, croplands) in 6 long-term disturbed (multiple centuries) soil sites in the Belgium Loam Belt. Results from a simultaneous chemical extraction in 0.5M NaOH of Si and Al, showed that soils were depleted in the BSi pool while showing high levels of reactive secondary clay minerals, mainly in the deeper horizons and especially in the forests and the croplands. During the extraction, clays were similar in reactivity to the biogenic pool of phytoliths. In order to study the kinetics in a more natural environment, batch dissolution experiments were conducted. Samples from different soil depths for each land use site (0.5 g) were mixed with 0.5 L of demineralised water modified to pH 4, 7 and 10. Subsamples of 2 ml were taken during 3 months. In the end of the period, results for pH 7 showed that in the pastures, where reactive clays were almost absent, the ratio Si/RSi (defined as the Si concentration in the end of the batch experiment divided by the reactive silica extracted from the soil with the alkaline extraction) was lower than 0.005%. The same ratio was higher in the mineral horizons of forests (Si/RSi>0.01%) and croplands (0.005% < Si/RSi <0.01%) where clay minerals were the dominant fraction. These preliminary results highlight the clay minerals' strong potential for Si mobilization. More attention should be paid to this important fraction as it can contribute strongly to Si availability

  9. Structural Transformation of Clay Minerals by a New Molecular Dynamics Simulation Method

    NASA Astrophysics Data System (ADS)

    Wang, Jianfeng; Gutierrez, Marte

    2010-05-01

    A MD simulation study of 2:1 clay minerals is carried out using a new MD simulation method which is capable of simulating a system under the most general external stress conditions by considering the changes of MD cell size and shape. The tensor defining the cell size and shape is correlated with the atomic level stress tensors (both internal and external) through a Lagrangian formulation. Due to this feature, the method is able to predict the crystal transformation of molecular structures which is compatible with the imposed external stress and boundary conditions. In this paper, the new method has been applied for the first time to the simulations of dehydrated montmorillonite sheets, and has successfully revealed unforeseen structural transformations of clay minerals upon relaxation under different normal stress conditions. In order to first achieve the correct coupled simulation of atomic structural change and MD cell deformation, parametric studies were made on the effects of the time step and the "imaginary" mass M of the MD cell on the model behavior. It is found that the time step essentially controls the convergence behavior of the system, while the "imaginary" mass M has large influences on the final equilibrated structure of the system. Results of the parametric study suggest that values of 1.0×10-17 sec for the time step and 1.0×105 for the "imaginary" mass M are appropriate for the simulation of 2:1 clay minerals using the current method. Simulation results reveal the strong correlations between the degrees of constraints imposed on the simulation cell (i.e., whether the cell size or shape change is allowed) and the final equilibrated crystal structure of clay minerals. It is found during the relaxation process that large shear distortions of clay minerals will occur if full allowance is given to the cell size and shape change, while large shear stress in the sheet plane will be retained if only the cell size change is allowed. These structural

  10. Influence of clay minerals on sorption and bioreduction of arsenic under anoxic conditions.

    PubMed

    Ghorbanzadeh, Nasrin; Lakzian, Amir; Halajnia, Akram; Kabra, Akhil N; Kurade, Mayur B; Lee, Dae S; Jeon, Byong-Hun

    2015-12-01

    Adsorption of As(V) on various clay minerals including kaolinite (KGa-1), montmorillonite (SWy-1) and nontronites (NAU-1 and NAU-2), and subsequent bioreduction of sorbed As(V) to As(III) by bacterium Shewanella putrefaciens strain CN-32 were investigated. Nontronites showed relatively higher sorption capacity for As(V) primarily due to higher iron oxide content. Freundlich equation well described the sorption of As(V) on NAU-1, NAU-2 and SWy-1, while As(V) sorption isotherm with KGa-1 fitted well in the Langmuir model. The bacterium rapidly reduced 50% of dissolved As(V) to As(III) in 2 h, followed by its complete reduction (>ca. 98%) within 12 h. In contrast, sorption of As(V) to the mineral surfaces interferes with the activity of bacterium, resulting in low bioreduction of As(V) by 27% for 5 days of incubation. S. putrefaciens also promoted the reduction of Fe(III) present in the clay mineral to Fe(II). This study indicates that the sorption and subsequent bioreduction of As(V) on clay minerals can significantly influence the mobility of As(V) in subsurface environment. PMID:25971375

  11. Influence of clay minerals on sorption and bioreduction of arsenic under anoxic conditions.

    PubMed

    Ghorbanzadeh, Nasrin; Lakzian, Amir; Halajnia, Akram; Kabra, Akhil N; Kurade, Mayur B; Lee, Dae S; Jeon, Byong-Hun

    2015-12-01

    Adsorption of As(V) on various clay minerals including kaolinite (KGa-1), montmorillonite (SWy-1) and nontronites (NAU-1 and NAU-2), and subsequent bioreduction of sorbed As(V) to As(III) by bacterium Shewanella putrefaciens strain CN-32 were investigated. Nontronites showed relatively higher sorption capacity for As(V) primarily due to higher iron oxide content. Freundlich equation well described the sorption of As(V) on NAU-1, NAU-2 and SWy-1, while As(V) sorption isotherm with KGa-1 fitted well in the Langmuir model. The bacterium rapidly reduced 50% of dissolved As(V) to As(III) in 2 h, followed by its complete reduction (>ca. 98%) within 12 h. In contrast, sorption of As(V) to the mineral surfaces interferes with the activity of bacterium, resulting in low bioreduction of As(V) by 27% for 5 days of incubation. S. putrefaciens also promoted the reduction of Fe(III) present in the clay mineral to Fe(II). This study indicates that the sorption and subsequent bioreduction of As(V) on clay minerals can significantly influence the mobility of As(V) in subsurface environment.

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

    PubMed

    Kennedy, Martin J; Wagner, Thomas

    2011-06-14

    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.

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

    PubMed Central

    Kennedy, Martin J.; Wagner, Thomas

    2011-01-01

    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. PMID:21576498

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

    PubMed

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

    2011-11-01

    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 than at present. However, available data instead indicate substantial Martian clay formation by hydrothermal groundwater circulation and a Noachian rock record dominated by evidence of subsurface waters. Cold, arid conditions with only transient surface water may have characterized Mars's surface for over 4 billion years, since the early-Noachian period, and the longest-duration aqueous, potentially habitable environments may have been in the subsurface.

  15. Microbial metabolism mediates interactions between dissolved organic matter and clay minerals in streamwater

    PubMed Central

    Hunter, W. R.; Battin, T. J.

    2016-01-01

    Sorption of organic molecules to mineral surfaces is an important control upon the aquatic carbon (C) cycle. Organo-mineral interactions are known to regulate the transport and burial of C within inland waters, yet the mechanisms that underlie these processes are poorly constrained. Streamwater contains a complex and dynamic mix of dissolved organic compounds that coexists with a range of organic and inorganic particles and microorganisms. To test how microbial metabolism and organo-mineral complexation alter amino acid and organic carbon fluxes we experimented with 13C-labelled amino acids and two common clay minerals (kaolinite and montmorillonite). The addition of 13C-labelled amino acids stimulated increased microbial activity. Amino acids were preferentially mineralized by the microbial community, concomitant with the leaching of other (non-labelled) dissolved organic molecules that were removed from solution by clay-mediated processes. We propose that microbial processes mediate the formation of organo-mineral particles in streamwater, with potential implications for the biochemical composition of organic matter transported through and buried within fluvial environments. PMID:27481013

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

    USGS Publications Warehouse

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

    1986-01-01

    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.

  17. Microbial metabolism mediates interactions between dissolved organic matter and clay minerals in streamwater

    NASA Astrophysics Data System (ADS)

    Hunter, W. R.; Battin, T. J.

    2016-08-01

    Sorption of organic molecules to mineral surfaces is an important control upon the aquatic carbon (C) cycle. Organo-mineral interactions are known to regulate the transport and burial of C within inland waters, yet the mechanisms that underlie these processes are poorly constrained. Streamwater contains a complex and dynamic mix of dissolved organic compounds that coexists with a range of organic and inorganic particles and microorganisms. To test how microbial metabolism and organo-mineral complexation alter amino acid and organic carbon fluxes we experimented with 13C-labelled amino acids and two common clay minerals (kaolinite and montmorillonite). The addition of 13C-labelled amino acids stimulated increased microbial activity. Amino acids were preferentially mineralized by the microbial community, concomitant with the leaching of other (non-labelled) dissolved organic molecules that were removed from solution by clay-mediated processes. We propose that microbial processes mediate the formation of organo-mineral particles in streamwater, with potential implications for the biochemical composition of organic matter transported through and buried within fluvial environments.

  18. Microbial metabolism mediates interactions between dissolved organic matter and clay minerals in streamwater.

    PubMed

    Hunter, W R; Battin, T J

    2016-01-01

    Sorption of organic molecules to mineral surfaces is an important control upon the aquatic carbon (C) cycle. Organo-mineral interactions are known to regulate the transport and burial of C within inland waters, yet the mechanisms that underlie these processes are poorly constrained. Streamwater contains a complex and dynamic mix of dissolved organic compounds that coexists with a range of organic and inorganic particles and microorganisms. To test how microbial metabolism and organo-mineral complexation alter amino acid and organic carbon fluxes we experimented with (13)C-labelled amino acids and two common clay minerals (kaolinite and montmorillonite). The addition of (13)C-labelled amino acids stimulated increased microbial activity. Amino acids were preferentially mineralized by the microbial community, concomitant with the leaching of other (non-labelled) dissolved organic molecules that were removed from solution by clay-mediated processes. We propose that microbial processes mediate the formation of organo-mineral particles in streamwater, with potential implications for the biochemical composition of organic matter transported through and buried within fluvial environments. PMID:27481013

  19. Microbial metabolism mediates interactions between dissolved organic matter and clay minerals in streamwater.

    PubMed

    Hunter, W R; Battin, T J

    2016-01-01

    Sorption of organic molecules to mineral surfaces is an important control upon the aquatic carbon (C) cycle. Organo-mineral interactions are known to regulate the transport and burial of C within inland waters, yet the mechanisms that underlie these processes are poorly constrained. Streamwater contains a complex and dynamic mix of dissolved organic compounds that coexists with a range of organic and inorganic particles and microorganisms. To test how microbial metabolism and organo-mineral complexation alter amino acid and organic carbon fluxes we experimented with (13)C-labelled amino acids and two common clay minerals (kaolinite and montmorillonite). The addition of (13)C-labelled amino acids stimulated increased microbial activity. Amino acids were preferentially mineralized by the microbial community, concomitant with the leaching of other (non-labelled) dissolved organic molecules that were removed from solution by clay-mediated processes. We propose that microbial processes mediate the formation of organo-mineral particles in streamwater, with potential implications for the biochemical composition of organic matter transported through and buried within fluvial environments.

  20. Chemistry and mineralogy of clay minerals in Asian and Saharan dusts and the implications for iron supply to the oceans

    NASA Astrophysics Data System (ADS)

    Jeong, G. Y.; Achterberg, E. P.

    2014-11-01

    Mineral dust supplied to remote ocean regions stimulates phytoplankton growth through delivery of micronutrients, notably iron (Fe). Although attention is usually paid to Fe (hydr)oxides as major sources of available Fe, Fe-bearing clay minerals are typically the dominant phase in mineral dust. The mineralogy and chemistry of clay minerals in dust particles, however, are largely unknown. We conducted microscopic identification and chemical analysis of the clay minerals in Asian and Saharan dust particles. Cross-sectional slices of dust particles were prepared by focused ion beam (FIB) techniques and analyzed by transmission electron microscopy (TEM) combined with energy dispersive X-ray spectroscopy (EDXS). TEM images of FIB slices revealed that clay minerals occurred as either nano-thin platelets or relatively thick plates. Chemical compositions and lattice fringes of the nano-thin platelets suggested that they included illite, smectite, illite-smectite mixed layers, and their nanoscale mixtures (illite-smectite series clay minerals, ISCMs) which could not be resolved with an electron microbeam. EDXS chemical analysis of the clay mineral grains revealed that the average Fe content was 5.8% in nano-thin ISCM platelets assuming 14% H2O, while the Fe content of illite and chlorite was 2.8 and 14.8%, respectively. In addition, TEM and EDXS analyses were performed on clay mineral grains dispersed and loaded on micro-grids. The average Fe content of clay mineral grains was 6.7 and 5.4% in Asian and Saharan dusts, respectively. A comparative X-ray diffraction analysis of bulk dusts showed that Saharan dust was more enriched in clay minerals than Asian dust, while Asian dust was more enriched in chlorite. Clay minerals, in particular nanocrystalline ISCMs and Fe-rich chlorite, are probably important sources of Fe to remote marine ecosystems. Further detailed analyses of the mineralogy and chemistry of clay minerals in global mineral dusts are required to evaluate the

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

    USGS Publications Warehouse

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

    1969-01-01

    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

  2. Aqueous suspensions of natural swelling clay minerals. 1. Structure and electrostatic interactions.

    PubMed

    Paineau, Erwan; Bihannic, Isabelle; Baravian, Christophe; Philippe, Adrian-Marie; Davidson, Patrick; Levitz, Pierre; Funari, Sérgio S; Rochas, Cyrille; Michot, Laurent J

    2011-05-01

    In this article, we present a general overview of the organization of colloidal charged clay particles in aqueous suspension by studying different natural samples with different structural charges and charge locations. Small-angle X-ray scattering experiments (SAXS) are first used to derive swelling laws that demonstrate the almost perfect exfoliation of clay sheets in suspension. Using a simple approach based on geometrical constraints, we show that these swelling laws can be fully modeled on the basis of morphological parameters only. The validity of this approach was further extended to other clay data from the literature, in particular, synthetic Laponite. For all of the investigated samples, experimental osmotic pressures can be properly described by a Poisson-Boltzmann approach for ionic strength up to 10(-3) M, which reveals that these systems are dominated by repulsive electrostatic interactions. However, a detailed analysis of the Poisson-Boltzmann treatment shows differences in the repulsive potential strength that are not directly linked to the structural charge of the minerals but rather to the charge location in the structure for tetrahedrally charged clays (beidellite and nontronites) undergoing stronger electrostatic repulsions than octahedrally charged samples (montmorillonites, laponite). Only minerals subjected to the strongest electrostatic repulsions present a true isotropic to nematic phase transition in their phase diagrams. The influence of ionic repulsions on the local order of clay platelets was then analyzed through a detailed investigation of the structure factors of the various clay samples. It appears that stronger electrostatic repulsions improve the liquidlike positional local order. PMID:21476528

  3. Importance of Tetrahedral Iron during Microbial Reduction of Clay Mineral NAu-2

    NASA Astrophysics Data System (ADS)

    Shi, B.; Wu, L.; Liu, K.; Smeaton, C. M.; Li, W.; Beard, B. L.; Johnson, C.; Roden, E. E.; Van Cappellen, P.

    2015-12-01

    Transformations between Fe(II) and Fe(III) in ferruginous clay minerals significantly impact the physicochemical properties of soils and sediments, such as the ion exchange capacity and redox potential. An increasing number of studies have focused on clay minerals that undergo redox changes, however, none have so far addressed Fe isotope fractionation during these processes. In this study, Fe isotope fractionations were determined during microbial reduction of Fe(III) in nontronite NAu-2 with different concentrations of lactate. No secondary Fe-bearing minerals, including Fe oxides, were detected by SEM in over 100 days of incubation, suggesting that the measured fractionations only reflected the net isotope effect associated with the clay minerals. The initial reduction likely started from edge sites, and the reductive dissolution released aqueous Fe(II). Basal plane sorbed Fe(II) was detectable after the extent of Fe reduction exceeded 5% and extensive electron transfer and isotope exchange had occurred between basal plane sorbed Fe(II) and structural Fe(III). With lower concentrations of the lactate(40 mM), the maximum Fe isotope fractionation was larger (∆56Febasal Fe(II)-structure Fe(III)= -4.37‰), consistent with greater adsorption than in systems with more lactate. After the Fe in reactive sites was all reduced, isotope exchange between Fe(II) and structural Fe(III) was inhibited due to blockage of electron transfer pathways by the collapse of the clay layers. The results agree with another study in our group on microbial reduction of NAu-1, despite both the smaller extent of reduction (~10% vs. 22% max bioreduction for NAu-1 and NAu-2, respectively) and smaller isotope fractionation factor than for NAu-2. We speculate that tetrahedral Fe in NAu-2 may have accelerated the electron transfer between Fe atoms, thus inducing a higher extent of reduction and a larger Fe isotope fractionation compared to NAu-1.

  4. The First X-ray Diffraction Patterns of Clay Minerals from Gale Crater

    NASA Astrophysics Data System (ADS)

    Bristow, T.; Blake, D.; Bish, D. L.; Vaniman, D.; Ming, D. W.; Morris, R. V.; Chipera, S.; Rampe, E. B.; Farmer, J. D.; Treiman, A. H.; Downs, R.; Morrison, S.; Achilles, C.; Des Marais, D. J.; Crisp, J. A.; Sarrazin, P.; Morookian, J.; Grotzinger, J. P.; Team, M.

    2013-12-01

    The Mars Science Laboratory (MSL) Rover, Curiosity spent ~150 sols at Yellowknife Bay (YKB) studying a section of fluvio-lacustrine sedimentary rocks (with potential indications of volcanic influence), informally known as the Yellowknife Bay formation. YKB lies in a distal region of the Peace Vallis alluvial fan, which extends from the northern rim of Gale Crater toward the dune field at the base of Mt Sharp. Sedimentological and stratigraphic observations are consistent with the Yellowknife Bay formation being part of a distal fan deposit, which could be as young as middle Hesperian to even early Amazonian in age (~3.5 to 2.5 Ga). The Yellowknife Bay formation hosts a unit of mudstone called the Sheepbed member. Curiosity obtained powdered rock samples from two drill holes in the Sheepbed Member, named John Klein and Cumberland, and delivered them to instruments in Curiosity. Data from CheMin, a combined X-ray diffraction (XRD)/X-ray fluorescence instrument (XRF), has allowed detailed mineralogical analysis of mudstone powders revealing a clay mineral component of ~20 wt.% in each sample. The clay minerals are important indicators of paleoenvironmental conditions and sensitive recorders of post-depositional alteration processes. The XRD pattern of John Klein reveals a 02l band consistent with a trioctahedral phyllosilicate. A broad peak at ~10A with a slight inflexion at ~12A indicates the presence of 2:1 type clay minerals in the John Klein sample. The trioctahedral nature of the clay minerals, breadth of the basal reflection, and presence of a minor component with larger basal spacing suggests that John Klein contains a trioctahedral smectite (probably saponite), whose interlayer is largely collapsed because of the low-humidity conditions. The XRD patterns show no evidence of corrensite (mixed-layer chlorite/smectite) or chlorite, which are typical diagenetic products of trioctahedral smectites when subjected to burial and heating >60°C in the presence of water

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

    SciTech Connect

    Ford, R.G.; Scheinost, A.C.; Scheckel, K.G.; Sparks, D.L.

    1999-09-15

    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.

  6. Authigenic clay minerals in the Rustler Formation, WIPP (Waste Isolation Pilot Plant) Site area, New Mexico

    SciTech Connect

    Brookins, D.G.; Ward, D.B. . Dept. of Geology); Lambert, S.J. )

    1990-05-01

    Transuranic waste is planned for disposal in the Late Permian evaporites of the Delaware Basin, southeastern New Mexico, at the WIPP Site. The disposal horizon is located in the bedded halite of the Salado Formation, which is overlain by the impure haliteanhydrite(gypsum)-siltstone-mudstone of the Rustler Formation. The Rustler Formation also contains two dolomite members, the Magenta and Culebra, which transmit water. The Culebra Member is suspected to have actively interacted with waters at time(s) from the Late Permian to the present, and it is important to assess the reactivity of these waters in conjunction with WIPP stability. We have investigated the Rb--Sr systematics of clay minerals from the Culebra Member and elsewhere in the Rustler Formation. The authigenic fraction is especially sensitive to chemical and isotopic exchange with waters, and an episodic exposure to a large amount of water will reset the clay minerals to such a time. Our data yield 259 {plus minus} 22 MaRb--Sr isochron, which is consistent with the Late Permian age of the Rustler Formation. This age demonstrates that age-determining cations in these clay minerals have preserved their isotopic and chemical integrity since the Late Permian. 16 refs.

  7. Heterogeneous nucleation of nitric acid trihydrate on clay minerals: relevance to type ia polar stratospheric clouds.

    PubMed

    Hatch, Courtney D; Gough, Raina V; Toon, Owen B; Tolbert, Margaret A

    2008-01-17

    Although critical to atmospheric modeling of stratospheric ozone depletion, selective heterogeneous nuclei that promote the formation of Type Ia polar stratospheric clouds (PSCs) are largely unknown. While mineral particles are known to be good ice nuclei, it is currently not clear whether they are also good nuclei for PSCs. In the present study, a high-vacuum chamber equipped with transmission Fourier transform infrared spectroscopy and a quadrupole mass spectrometer was used to study heterogeneous nucleation of nitric acid trihydrate (NAT) on two clay minerals-Na-montmorillonite and kaolinite-as analogs of atmospheric terrestrial and extraterrestrial minerals. The minerals are first coated with a 3:1 supercooled H2O/HNO3 solution prior to the observed nucleation of crystalline NAT. At 220 K, NAT formation was observed at low SNAT values of 12 and 7 on kaolinite and montmorillonite clays, respectively. These are the lowest SNAT values reported in the literature on any substrate. However, NAT nucleation exhibited significant temperature dependence. At lower temperatures, representative of typical polar stratospheric conditions, much higher supersaturations were required before nucleation was observed. Our results suggest that NAT nucleation on mineral particles, not previously treated with sulfuric acid, may not be an important nucleation platform for Type Ia PSCs under normal polar stratospheric conditions.

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

    SciTech Connect

    Nagy, Kathryn L.

    2008-07-03

    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.

  9. Ancient and recent clay formation on Mars as revealed from a global survey of hydrous minerals in crater central peaks

    NASA Astrophysics Data System (ADS)

    Sun, Vivian Z.; Milliken, Ralph E.

    2015-12-01

    Clay minerals on Mars have commonly been interpreted as the remnants of pervasive water-rock interaction during the Noachian period (>3.7 Ga). This history has been partly inferred by observations of clays in central peaks of impact craters, which often are presumed uplifted from depth. However, combined mineralogical and morphological analyses of individual craters have shown that some central peak clays may represent post-impact, possibly authigenic processes. Here we present a global survey of 633 central peaks to assess their hydrous minerals and the prevalence of uplifted, detrital, and authigenic clays. Central peak regions are examined using high-resolution Compact Reconnaissance Imaging Spectrometer for Mars and High Resolution Imaging Science Experiment data to identify hydrous minerals and place their detections in a stratigraphic and geologic context. We find that many occurrences of Fe/Mg clays and hydrated silica are associated with potential impact melt deposits. Over 35% of central peak clays are not associated with uplifted rocks; thus, caution must be used when inferring deeper crustal compositions from surface mineralogy of central peaks. Uplifted clay-bearing rocks suggest the Martian crust hosts clays to depths of at least 7 km. We also observe evidence for increasing chloritization with depth, implying the presence of fluids in the upper portions of the crust. Our observations are consistent with widespread Noachian/Early Hesperian clay formation, but a number of central peak clays are also suggestive of clay formation during the Amazonian. These results broadly support current paradigms of Mars' aqueous history while adding insight to global crustal and diagenetic processes associated with clay mineral formation and stability.

  10. Investigating the Thermal Limit of Clay Minerals for Applications in Nuclear Waste Repository Design

    NASA Astrophysics Data System (ADS)

    Matteo, E. N.; Miller, A. W.; Kruichak, J.; Mills, M.; Tellez, H.; Wang, Y.

    2013-12-01

    Clay minerals are likely candidates to aid in nuclear waste isolation due to their low permeability, favorable swelling properties, and high cation sorption capacities. Establishing the thermal limit for clay minerals in a nuclear waste repository is a potentially important component of repository design, as flexibility of the heat load within the repository can have a major impact on the selection of repository design. For example, the thermal limit plays a critical role in the time that waste packages would need to cool before being transferred to the repository. Understanding the chemical and physical changes that occur in clay minerals at various temperatures above the current thermal limit (of 100 °C) can enable decision-makers with information critical to evaluating the potential trade-offs of increasing the thermal limit within the repository. Most critical is gaining understanding of how varying thermal conditions in the repository will impact radionuclide sorption and transport in clay materials either as engineered barriers or as disposal media. A variety of clays (illite, mixed layer illite/smectite, montmorillonite, and palygorskite) were heated for a range of temperatures between 100-500 °C. These samples were characterized by a variety of methods, including nitrogen adsorption, x-ray diffraction, thermogravimetric analysis, barium chloride exchange for cation exchange capacity (CEC), and iodide sorption. The nitrogen porosimetry shows that for all the clays, thermally-induced changes in BET surface area are dominated by collapse/creation of the microporosity, i.e. pore diameters < 17 angstroms. Changes in micro porosity (relative to no heat treatment) are most significant for heat treatments 300 °C and above. Alterations are also seen in the chemical properties (CEC, XRD, iodide sorption) of clays, and like pore size distribution changes, are most significant above 300 °C. Overall, the results imply that changes seen in pores size distribution

  11. Relationship between heavy metal contents and clay mineral properties in surface sediments: Implications for metal pollution assessment

    NASA Astrophysics Data System (ADS)

    Chen, Yueh-Min; Gao, Jin-bo; Yuan, Yong-Qiang; Ma, Jun; Yu, Shen

    2016-08-01

    Clay minerals in surface sediments can affect the adsorption of heavy metals. However, few historical studies have focused on the influence of fine clay mineral characteristics on metal sorption. Since the reactions between heavy metals and fine clay minerals in sediments remain obscure, this study investigates the influence of fine clay mineral characteristics on metal sorption in a typical urbanizing small watershed. Clay minerals, including nanoparticles with various size fractions ranging from 1000 to 2000 (clay), 450-1000 (fine clay), and 220-450 (very fine clay) nm were used to demonstrate their transformation from well crystalline to poorly crystalline. The nanoparticles were collected and evaluated by determination of their surface area, X-ray diffraction, scanning electron microscopy (SEM) and chemical analyses. The relationship between metal content and properties of the surface sediments was also revealed by canonical correlation analysis. With smaller particle sizes, nanoparticles (very fine clay) were observed to be poorly crystalline, possibly indicating few repetitions of unit cells as a result of preferential structural disruption of other crystal planes caused by pressure-induced phase transition in the fine-size fractions. The first canonical matrix (M) variables of metal contents can be predicted by both surface area and pore volume, followed by kaolinite and illite contents. On the other hand, the category of metal, i.e., Cu, Cr, Zn, or Pb, was significantly correlated with the first 'M' canonical variables. The data obtained in the present study are of fundamental significance in advancing our understanding of the reactions between heavy metals and fine clay minerals in the terrestrial ecosystem.

  12. Mineral carbonation of gaseous carbon dioxide using a clay-hosted cation exchange reaction.

    PubMed

    Kang, Il-Mo; Roh, Ki-Min

    2013-01-01

    The mineral carbonation method is still a challenge in practical application owing to: (1) slow reaction kinetics, (2) high reaction temperature, and (3) continuous mineral consumption. These constraints stem from the mode of supplying alkaline earth metals through mineral acidification and dissolution. Here, we attempt to mineralize gaseous carbon dioxide into calcium carbonate, using a cation exchange reaction of vermiculite (a species of expandable clay minerals). The mineralization is operated by draining NaCI solution through vermiculite powders and continuously dropping into the pool of NaOH solution with CO2 gas injected. The mineralization temperature is regulated here at 293 and 333 K for 15 min. As a result of characterization, using an X-ray powder diffractometer and a scanning electron microscopy, two types of pure CaCO3 polymorphs (vaterite and calcite) are identified as main reaction products. Their abundance and morphology are heavily dependent on the mineralization temperature. Noticeably, spindle-shaped vaterite, which is quite different from a typical vaterite morphology (polycrystalline spherulite), forms predominantly at 333 K (approximately 98 wt%).

  13. Geochemical study of evaporite and clay mineral-oxyhydroxide samples from the Waste Isolation Pilot Plant site

    SciTech Connect

    Brookins, D.G.

    1993-06-01

    Samples of clay minerals, insoluble oxyhydroxides, and their host evaporites from the WIPP site have been studied for their major and minor elements abundances, x-ray diffraction characteristics, K-Ar ages, and Rb-Sr ages. This study was undertaken to determine their overall geochemical characteristics and to investigate possible interactions between evaporates and insoluble constituents. The evaporite host material is water-soluble, having Cl/Br ratios typical of marine evaporites, although the Br content is low. Insoluble material (usually a mixture of clay minerals and oxyhydroxide phases) yields very high Cl/Br ratios, possibly because of Cl from admixed halide minerals. This same material yields K/Rb and Th/U ratios in the normal range for shales; suggesting little, if any, effect of evaporite-induced remobilization of U, K, or Rb in the insoluble material. The rare-earth element (REE) data also show normal REE/chondrite (REE/CHON) distribution patterns, supporting the K/Rb and Th/U data. Clay minerals yield K-Ar dates in the range 365 to 390 Ma and a Rb-Sr isochron age of 428 {+-} 7 Ma. These ages are well in excess of the 220- to 230-Ma formational age of the evaporites, and confirm the detrital origin of the clays. The ages also show that any evaporite or clay mineral reactions that might have occurred at or near the time of sedimentation and diagenesis were not sufficient to reset the K-Ar and Rb-Sr systematics of the clay minerals. Further, x-ray data indicate a normal evaporitic assemblage of clay minerals and Fe-rich oxyhydroxide phases. The clay minerals and other insoluble material appear to be resistant to the destructive effects of their entrapment in the evaporites, which suggests that these insoluble materials would be good getters for any radionuclides (hypothetically) released from the storage of radioactive wastes in the area.

  14. Impact of clay mineral on air oxidation of PAH-contaminated soils.

    PubMed

    Biache, Coralie; Kouadio, Olivier; Lorgeoux, Catherine; Faure, Pierre

    2014-09-01

    This work investigated the impact of a clay mineral (bentonite) on the air oxidation of the solvent extractable organic matters (EOMs) and the PAHs from contaminated soils. EOMs were isolated from two coking plant soils and mixed with silica sand or bentonite. These samples, as well as raw soils and bentonite/soil mixtures, were oxidized in air at 60 and 100 °C for 160 days. Mineralization was followed by measuring the CO2 produced over the experiments. EOM, polycyclic aromatic compound (PAC), including PAH, contents were also determined. Oxidation led to a decrease in EOM contents and PAH concentrations, these diminutions were enhanced by the presence of bentonite. Transfer of carbon from EOM to insoluble organic matter pointed out a condensation phenomenon leading to a stabilization of the contamination. Higher mineralization rates, observed during the oxidation of the soil/bentonite mixtures, seem to indicate that this clay mineral had a positive influence on the transformation of PAC into CO2.

  15. [Effect of treatments of hydrogen peroxide and sodium dithionite-citrate-bicarbonate on clay minerals of red earth sediments].

    PubMed

    Li, Rong-Biao; Hong, Han-Lie; Yin, Ke; Wang, Chao-Wen; Gao, Wen-Peng; Han, Wen; Wu, Qing-Feng

    2013-04-01

    As classical procedures for pretreatment of soil sediments, hydrogen peroxide (H2O2) and sodium dithionite-citrate-bicarbonate (DCB) treatment methods are very important in removing the organic matter and iron oxides acting as cementing agents in the soils. However, both of these methods have less been focused on the effect on the clay minerals when separating. Here, we report the comparable methods between H2O2 and DCB to reveal their effect on clay minerals in red earth sediments using X-ray diffraction (XRD). The XRD results suggested that mineral particles can be totally decentralized by either H2O2 or DCB method in the soils and high purity clay minerals can be obtained by separating quartz and other impurities from clay minerals effectively. However, the XRD data were distorted by the DCB treatment owning to the cation exchange between Na+ and interlayer cation. On the contrary, the authentic data can be obtained by H2O2 treatment. Therefore, the H2O2 treatment seems to be a more appropriate method to obtain authentic information of clay mineralogy when separating of clay minerals from red earth sediments.

  16. Clay minerals in delta deposits and organic preservation potential on Mars

    NASA Astrophysics Data System (ADS)

    Ehlmann, Bethany L.; Mustard, John F.; Fassett, Caleb I.; Schon, Samuel C.; Head, James W., III; Des Marais, David J.; Grant, John A.; Murchie, Scott L.

    2008-06-01

    Clay-rich sedimentary deposits are often sites of organic matter preservation, and have therefore been sought in Mars exploration. However, regional deposits of hydrous minerals, including phyllosilicates and sulphates, are not typically associated with valley networks and layered sediments that provide geomorphic evidence of surface water transport on early Mars. The Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) has recently identified phyllosilicates within three lake basins with fans or deltas that indicate sustained sediment deposition: Eberswalde crater, Holden crater and Jezero crater. Here we use high-resolution data from the Mars Reconnaissance Orbiter (MRO) to identify clay-rich fluvial-lacustrine sediments within Jezero crater, which has a diameter of 45km. The crater is an open lake basin on Mars with sedimentary deposits of hydrous minerals sourced from a smectite-rich catchment in the Nili Fossae region. We find that the two deltas and the lowest observed stratigraphic layer within the crater host iron-magnesium smectite clay. Jezero crater holds sediments that record multiple episodes of aqueous activity on early Mars. We suggest that this depositional setting and the smectite mineralogy make these deltaic deposits well suited for the sequestration and preservation of organic material.

  17. Hydrogen and oxygen isotope exchange reactions between clay minerals and water

    USGS Publications Warehouse

    O'Neil, J.R.; Kharaka, Y.K.

    1976-01-01

    The extent of hydrogen and oxygen isotope exchange between clay minerals and water has been measured in the temperature range 100-350?? for bomb runs of up to almost 2 years. Hydrogen isotope exchange between water and the clays was demonstrable at 100??. Exchange rates were 3-5 times greater for montmorillonite than for kaolinite or illite and this is attributed to the presence of interlayer water in the montmorillonite structure. Negligible oxygen isotope exchange occurred at these low temperatures. The great disparity in D and O18 exchange rates observed in every experiment demonstrates that hydrogen isotope exchange occurred by a mechanism of proton exchange independent of the slower process of O18 exchange. At 350?? kaolinite reacted to form pyrophyllite and diaspore. This was accompanied by essentially complete D exchange but minor O18 exchange and implies that intact structural units in the pyrophyllite were inherited from the kaolinite precursor. ?? 1976.

  18. Molecular simulation of carbon dioxide, brine, and clay mineral interactions and determination of contact angles.

    PubMed

    Tenney, Craig M; Cygan, Randall T

    2014-01-01

    Capture and subsequent geologic storage of CO2 in deep brine reservoirs plays a significant role in plans to reduce atmospheric carbon emission and resulting global climate change. The interaction of CO2 and brine species with mineral surfaces controls the ultimate fate of injected CO2 at the nanoscale via geochemistry, at the pore-scale via capillary trapping, and at the field-scale via relative permeability. We used large-scale molecular dynamics simulations to study the behavior of supercritical CO2 and aqueous fluids on both the hydrophilic and hydrophobic basal surfaces of kaolinite, a common clay mineral. In the presence of a bulk aqueous phase, supercritical CO2 forms a nonwetting droplet above the hydrophilic surface of kaolinite. This CO2 droplet is separated from the mineral surface by distinct layers of water, which prevent the CO2 droplet from interacting directly with the mineral surface. Conversely, both CO2 and H2O molecules interact directly with the hydrophobic surface of kaolinite. In the presence of bulk supercritical CO2, nonwetting aqueous droplets interact with the hydrophobic surface of kaolinite via a mixture of adsorbed CO2 and H2O molecules. Because nucleation and precipitation of minerals should depend strongly on the local distribution of CO2, H2O, and ion species, these nanoscale surface interactions are expected to influence long-term mineralization of injected carbon dioxide.

  19. Adsorption of iron cyanide complexes onto clay minerals, manganese oxide, and soil.

    PubMed

    Kang, Dong-Hee; Schwab, A Paul; Johnston, C T; Banks, M Katherine

    2010-09-01

    The adsorption characteristics of an iron cyanide complex, soluble Prussian blue KFe(III)[Fe(II)(CN)(6)], were evaluated for representative soil minerals and soil at pH 3.7, 6.4 and 9.7. Three specimen clay minerals (kaolinite, montmorillonite, and illite), two synthesized manganese oxides (birnessite and cryptomelane), and a Drummer soil from Indiana were used as the adsorbents. Surface protonation of variable charge sites increased with decreasing pH yielding positively charged sites on crystal edges and enhancing the attractive force between minerals and iron cyanide complexes. Anion adsorption on clays often is correlated to the metal content of the adsorbent, and a positive relationship was observed between iron or aluminum content and Prussian blue adsorption. Illite had high extractable iron and adsorbed more ferro-ferricyande anion, while kaolinite and montmorillonite had lower extractable iron and adsorbed less. However, less pH effect was observed on the adsorption of iron cyanide to manganese oxides. This may due to the manganese oxide mediated oxidation of ferrocyanide [Fe(II)(CN)(6)(4-)], to ferricyanide [Fe(III)(CN)(6)(3-)], which has a low affinity for manganese oxides.

  20. Clay minerals on Mars: Riotinto mining district (Huelva, Spain) as Earth analogue for acidic alteration pathways

    NASA Astrophysics Data System (ADS)

    Mavris, C.; Cuadros, J.; Bishop, J. L.; Nieto, J. M.; Michalski, J. R.

    2015-12-01

    Combined satellite and in-situ measurements of Mars surface have detected mineral assemblages indicating processes for which Earth analogues exist. Among them, aluminous clay-sulfate assemblages have been observed, which suggest alteration by acidic fluids. The Riotinto mining district (SW Spain) provides an Earth analogue site for such Martian processes. The parent rocks belong to an Upper Palaeozoic (Late Famennian-Tournaisian) volcano-sedimentary complex including siliciclastic sediments and mafic and felsic volcanics, all of which underwent hydrothermal alteration. The oxidation of an extensive pyrite-rich orebody provided mild to extreme acidic fluxes that leached the surrounding rocks for over 20 million years. The mineral assemblages are strongly dependent on their acidic alteration intensity. The observed mineralogical parageneses and leaching conditions for our sites at Riotinto are consistent with three alteration sequences: i) Mild: containing a range of clay minerals from vermiculite to kaolinite, with a wide variety of crystal order and mixed-layering; ii) Intermediate: containing smectite to kaolinite with jarosite-group phases; iii) Advanced: containing kaolinite, jarosite-group phases, and iron oxides. Our findings suggest that, even within this general scheme, the specific alteration pathways can be different.

  1. Evidence for microbial liberation of structurally-coordinated iron in clay minerals as a nutrient source in the world ocean

    NASA Astrophysics Data System (ADS)

    Metcalfe, K. S.; Gaines, R. R.; Trang, J.; Scott, S.; Crane, E. J.; Lackey, J.; Prokopenko, M. G.; Berelson, W.

    2012-12-01

    Clay minerals are the most abundant materials found at the surface of earth and they are the primary constituents of marine sediments. Iron, a limiting nutrient in many marine settings, is a common constituent of clay minerals. Recent in vitro experimental evidence has shown that lab cultures of Fe-reducing bacteria are able to utilize structurally-bound Fe from the crystal lattice of nontronite, an uncommon and particularly Fe-rich (> 12 wt.%) smectitie. Reduction of structurally-coordinated Fe results in both the liberation of Fe(II) to solution, where it is available for other biotic processes, as well as the transformation of smectite to illite. However, it remains unclear: 1. whether Fe-reducers are able to access structurally coordinated Fe found at low wt.% in common clay minerals; and 2. if naturally occuring populations of Fe-reducers are able to reduce structurally coordinated Fe as are some lab strains. In order to address these questions, we conducted in vitro experiments using a suite of sixteen clay minerals with low (0.8 wt.%) to high (13.9 wt.%) Fe concentrations. Clays were treated with Na-dithionite solution to remove surface-bound Fe, isolating for study Fe sourced from within the clay crystal lattice. Experimental evidence clearly indicates that, under in vitro conditions, Fe(III) bound in common clay minerals is available for reduction by the lab strain Shewanella oneidensis MR-1 as well as by naturally-occuring consortia of Fe-reducers cultured from the San Pedro and Santa Monica Basins. Our findings suggest that common clay minerals may represent a large and previously unrecognized pool of bioavailable Fe in the world ocean that contributes significantly to biogeochemical cycling of Fe and C.

  2. Redox properties of structural Fe in clay minerals: 3. Relationships between smectite redox and structural properties.

    PubMed

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

    2013-01-01

    Structural Fe in clay minerals is an important redox-active species in many pristine and contaminated environments as well as in engineered systems. Understanding the extent and kinetics of redox reactions involving Fe-bearing clay minerals has been challenging due to the inability to relate structural Fe(2+)/Fe(total) fractions to fundamental redox properties, such as reduction potentials (EH). Here, we overcame this challenge by using mediated electrochemical reduction (MER) and oxidation (MEO) to characterize the fraction of redox-active structural Fe (Fe(2+)/Fe(total)) in smectites over a wide range of applied EH-values (-0.6 V to +0.6 V). We examined Fe(2+)/Fe(total )- EH relationships of four natural Fe-bearing smectites (SWy-2, SWa-1, NAu-1, NAu-2) in their native, reduced, and reoxidized states and compared our measurements with spectroscopic observations and a suite of mineralogical properties. All smectites exhibited unique Fe(2+)/Fe(total) - EH relationships, were redox active over wide EH ranges, and underwent irreversible electron transfer induced structural changes that were observable with X-ray absorption spectroscopy. Variations among the smectite Fe(2+)/Fe(total) - EH relationships correlated well with both bulk and molecular-scale properties, including Fe(total) content, layer charge, and quadrupole splitting values, suggesting that multiple structural parameters determined the redox properties of smectites. The Fe(2+)/Fe(total) - EH relationships developed for these four commonly studied clay minerals may be applied to future studies interested in relating the extent of structural Fe reduction or oxidation to EH-values.

  3. Inelastic neutron scattering and molecular simulation of the dynamics of interlayer water in smectite clay minerals

    SciTech Connect

    Cygan, Randall T.; Daemen, Luke L.; Ilgen, Anastasia G.; Krumhansl, James L.; Nenoff, Tina M.

    2015-11-16

    The study of mineral–water interfaces is of great importance to a variety of applications including oil and gas extraction, gas subsurface storage, environmental contaminant treatment, and nuclear waste repositories. Understanding the fundamentals of that interface is key to the success of those applications. Confinement of water in the interlayer of smectite clay minerals provides a unique environment to examine the interactions among water molecules, interlayer cations, and clay mineral surfaces. Smectite minerals are characterized by a relatively low layer charge that allows the clay to swell with increasing water content. Montmorillonite and beidellite varieties of smectite were investigated to compare the impact of the location of layer charge on the interlayer structure and dynamics. Inelastic neutron scattering of hydrated and dehydrated cation-exchanged smectites was used to probe the dynamics of the interlayer water (200–900 cm–1 spectral region) and identify the shift in the librational edge as a function of the interlayer cation. Molecular dynamics simulations of equivalent phases and power spectra, derived from the resulting molecular trajectories, indicate a general shift in the librational behavior with interlayer cation that is generally consistent with the neutron scattering results for the monolayer hydrates. Both neutron scattering and power spectra exhibit librational structures affected by the location of layer charge and by the charge of the interlayer cation. Furthermore, divalent cations (Ba2+ and Mg2+) characterized by large hydration enthalpies typically exhibit multiple broad librational peaks compared to monovalent cations (Cs+ and Na+), which have relatively small hydration enthalpies.

  4. Inelastic neutron scattering and molecular simulation of the dynamics of interlayer water in smectite clay minerals

    DOE PAGESBeta

    Cygan, Randall T.; Daemen, Luke L.; Ilgen, Anastasia G.; Krumhansl, James L.; Nenoff, Tina M.

    2015-11-16

    The study of mineral–water interfaces is of great importance to a variety of applications including oil and gas extraction, gas subsurface storage, environmental contaminant treatment, and nuclear waste repositories. Understanding the fundamentals of that interface is key to the success of those applications. Confinement of water in the interlayer of smectite clay minerals provides a unique environment to examine the interactions among water molecules, interlayer cations, and clay mineral surfaces. Smectite minerals are characterized by a relatively low layer charge that allows the clay to swell with increasing water content. Montmorillonite and beidellite varieties of smectite were investigated to comparemore » the impact of the location of layer charge on the interlayer structure and dynamics. Inelastic neutron scattering of hydrated and dehydrated cation-exchanged smectites was used to probe the dynamics of the interlayer water (200–900 cm–1 spectral region) and identify the shift in the librational edge as a function of the interlayer cation. Molecular dynamics simulations of equivalent phases and power spectra, derived from the resulting molecular trajectories, indicate a general shift in the librational behavior with interlayer cation that is generally consistent with the neutron scattering results for the monolayer hydrates. Both neutron scattering and power spectra exhibit librational structures affected by the location of layer charge and by the charge of the interlayer cation. Furthermore, divalent cations (Ba2+ and Mg2+) characterized by large hydration enthalpies typically exhibit multiple broad librational peaks compared to monovalent cations (Cs+ and Na+), which have relatively small hydration enthalpies.« less

  5. [Research on characteristics of soil clay mineral evolution in paddy field and dry land by XRD spectrum].

    PubMed

    Zhang, Zhi-dan; Li, Qiao; Luo, Xiang-li; Jiang, Hai-chao; Zheng, Qing-fu; Zhao, Lan-po; Wang, Ji-hong

    2014-08-01

    The present paper took the typical saline-alkali soil in Jilin province as study object, and determinated the soil clay mineral composition characteristics of soil in paddy field and dry land. Then XRD spectrum was used to analyze the evolutionary mechanism of clay mineral in the two kinds of soil. The results showed that the physical and chemical properties of soil in paddy field were better than those in dry land, and paddy field would promote the weathering of mineral particles in saline-alkali soil and enhance the silt content. Paddy field soil showed a strong potassium-removal process, with a higher degree of clay mineral hydration and lower degree of illite crystallinity. Analysis of XRD spectrum showed that the clay mineral composition was similar in two kinds of soil, while the intensity and position of diffraction peak showed difference. The evolution process of clay mineral in dry land was S/I mixture-->vermiculite, while in paddy field it was S/I mixture-->vermiculite-->kaolinite. One kind of hydroxylated 'chlorite' mineral would appear in saline-alkali soil in long-term cultivated paddy field. Taking into account that the physical and chemical properties of soil in paddy field were better then those in dry land, we could know that paddy field could help much improve soil structure, cultivate high-fertility soil and improve saline-alkali soil. This paper used XRD spectrum to determine the characteristics of clay minerals comprehensively, and analyzed two'kinds of land use comparatively, and was a new perspective of soil minerals study. PMID:25508755

  6. [Research on characteristics of soil clay mineral evolution in paddy field and dry land by XRD spectrum].

    PubMed

    Zhang, Zhi-dan; Li, Qiao; Luo, Xiang-li; Jiang, Hai-chao; Zheng, Qing-fu; Zhao, Lan-po; Wang, Ji-hong

    2014-08-01

    The present paper took the typical saline-alkali soil in Jilin province as study object, and determinated the soil clay mineral composition characteristics of soil in paddy field and dry land. Then XRD spectrum was used to analyze the evolutionary mechanism of clay mineral in the two kinds of soil. The results showed that the physical and chemical properties of soil in paddy field were better than those in dry land, and paddy field would promote the weathering of mineral particles in saline-alkali soil and enhance the silt content. Paddy field soil showed a strong potassium-removal process, with a higher degree of clay mineral hydration and lower degree of illite crystallinity. Analysis of XRD spectrum showed that the clay mineral composition was similar in two kinds of soil, while the intensity and position of diffraction peak showed difference. The evolution process of clay mineral in dry land was S/I mixture-->vermiculite, while in paddy field it was S/I mixture-->vermiculite-->kaolinite. One kind of hydroxylated 'chlorite' mineral would appear in saline-alkali soil in long-term cultivated paddy field. Taking into account that the physical and chemical properties of soil in paddy field were better then those in dry land, we could know that paddy field could help much improve soil structure, cultivate high-fertility soil and improve saline-alkali soil. This paper used XRD spectrum to determine the characteristics of clay minerals comprehensively, and analyzed two'kinds of land use comparatively, and was a new perspective of soil minerals study. PMID:25474976

  7. [Research on characteristics of soil clay mineral evolution in paddy field and dry land by XRD spectrum].

    PubMed

    Zhang, Zhi-dan; Li, Qiao; Luo, Xiang-li; Jiang, Hai-chao; Zheng, Qing-fu; Zhao, Lan-po; Wang, Ji-hong

    2014-08-01

    The present paper took the typical saline-alkali soil in Jilin province as study object, and determinated the soil clay mineral composition characteristics of soil in paddy field and dry land. Then XRD spectrum was used to analyze the evolutionary mechanism of clay mineral in the two kinds of soil. The results showed that the physical and chemical properties of soil in paddy field were better than those in dry land, and paddy field would promote the weathering of mineral particles in saline-alkali soil and enhance the silt content. Paddy field soil showed a strong potassium-removal process, with a higher degree of clay mineral hydration and lower degree of illite crystallinity. Analysis of XRD spectrum showed that the clay mineral composition was similar in two kinds of soil, while the intensity and position of diffraction peak showed difference. The evolution process of clay mineral in dry land was S/I mixture-->vermiculite, while in paddy field it was S/I mixture-->vermiculite-->kaolinite. One kind of hydroxylated 'chlorite' mineral would appear in saline-alkali soil in long-term cultivated paddy field. Taking into account that the physical and chemical properties of soil in paddy field were better then those in dry land, we could know that paddy field could help much improve soil structure, cultivate high-fertility soil and improve saline-alkali soil. This paper used XRD spectrum to determine the characteristics of clay minerals comprehensively, and analyzed two'kinds of land use comparatively, and was a new perspective of soil minerals study.

  8. Radiation Sensitivity of Natural Organic Matter: Clay Mineral Association Effects in the Callovo-Oxfordian Argillite

    SciTech Connect

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

    2009-01-01

    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 the radiation sensitivity of the undisturbed host rock organics was investigated. The clay sample originates from Oxfordian argillite (447 m depth, borehole EST 104). HA and FA were extracted following the standard International Humic Substance Society (IHSS) isolation procedure. Synchrotron based (C-, K-, Ca-, O- and Fe-edge XANES) scanning transmission X-ray microscopy (STXM) and FT-IR microspectroscopy was used to identify under high spatial resolution the distribution of clay-organic matter with different functionality using principal component and cluster analysis. The results show that in this old (Jurassic) geological formation, small parts of the organic inventory (1-5%) keeps the structure/functionality and can be mobilized as hydrophilic humic substance type material (HA and FA). Target spectra analysis shows best correlation for isolated humic acids with organics found in smectite-rich regions, whereas the extractable FA has better spectral similarities with the illite mixed layer minerals (MLM) regions. After radiation of 1.7 GGy under helium atmosphere the same rock sample area was investigated for radiation damage. Radiation damage in the smectite and illite-MLM associated organic matter is comparably low with 20-30% total oxygen mass loss and 13-18% total carbon mass loss. A critical dose dc of 2.5 GGy and a optical density after infinite radiation (OD?) of 54% was calculated under room temperature conditions. C(1s) XANES show a clear increase in Cdouble bond; length as m-dashC bonds especially in the illite-MLM associated organics. This results

  9. Clay mineral content of continental shelf and river sediments, southern California

    USGS Publications Warehouse

    Hein, James R.; Dowling, Jennifer S.

    2001-01-01

    This report contains data on the clay mineral content of 250 shelf surface-sediment samples from the California Continental Borderland (Tables 1, 2; Figures 1-7), 79 samples with depth in cores from Santa Monica Bay (Table 3; see Table 1 for surface sediment data for those same cores and for core locations), 24 suspended and 13 bottom sediment samples from rivers draining Southern California (Table 4), and six rock samples or composite rock samples from the Palos Verdes Headland (Table 4). This report is designed as the data repository and these data are discussed in a paper by Hein et al. (2001).

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

    SciTech Connect

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

    2012-06-20

    Environmental weathering is typically viewed as a macroscopic phenomenon that is based on a number of competing atomic- or molecular-level processes. One important process is the release of metal or metalloid elements into solution at the water-rock interface. To both explain and predict environmental weathering, the atomic-level “reactive sites” on the surfaces of minerals must be characterized and quantified. Whether these sites are atomic in nature, represented by a chemical bond, or comprise a more complex assemblage of covalently or ionically linked atoms or molecules, the kinetic rate of atomic release (dissolution) depends on the available reactive surface. For one important class of materials, clay minerals, their reactive surface areas are a challenge to quantify as it is well recognized that there are two distinct types of surfaces: edge sites and basal planes1-3. Clay dissolution rates continuously decrease over time as reactive edge sites are preferentially depleted4. Changes in reactive surface area and the difficulties in quantifying this elusive variable have often been cited as one key reason for the complexity in developing accurate rate equations3,5,6. In this work, we demonstrate a solid-state nuclear magnetic resonance (SSNMR) method for counting the number of reactive surface sites on a defined quantity of a clay mineral. Using this SSNMR proxy7-9, changes in reactive surface area were monitored for a series of batch dissolution experiments of low-defect kaolinite KGa-1b at 21 ºC and pH 3 over the course of 80 days. While no changes (within error) were observed for specific surface area (as determined from BET gas isotherm data), the SSNMR proxy revealed decreases in the number of reactive surface sites per gram of kaolinite as a function of dissolution time. This observation can be tied to a concomitant decrease in the rates of release of Si and Al into solution. These results further highlight the need to account for changes in reactive

  11. Potential Sites for Ice Nucleation on Aluminosilicate Clay Minerals and Related Materials.

    PubMed

    Freedman, Miriam Arak

    2015-10-01

    Few aerosol particles in clouds nucleate the formation of ice. The surface sites available for nucleus formation, which can include surface defects and functional groups, determine in part the activity of an aerosol particle toward ice formation. Although ice nucleation on particles has been widely studied, exploration of the specific sites at which the initial germ forms has been limited, but is important for predicting the microphysical properties of clouds, which impact climate. This Perspective focuses on what is currently known about surface sites for ice nucleation on aluminosilicate clay minerals, which are commonly found in ice residuals, as well as related materials. PMID:26722881

  12. Potential Sites for Ice Nucleation on Aluminosilicate Clay Minerals and Related Materials.

    PubMed

    Freedman, Miriam Arak

    2015-10-01

    Few aerosol particles in clouds nucleate the formation of ice. The surface sites available for nucleus formation, which can include surface defects and functional groups, determine in part the activity of an aerosol particle toward ice formation. Although ice nucleation on particles has been widely studied, exploration of the specific sites at which the initial germ forms has been limited, but is important for predicting the microphysical properties of clouds, which impact climate. This Perspective focuses on what is currently known about surface sites for ice nucleation on aluminosilicate clay minerals, which are commonly found in ice residuals, as well as related materials.

  13. Ball clay

    USGS Publications Warehouse

    Virta, R.L.

    2001-01-01

    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.

  14. Preferential adsorption of extracellular polymeric substances from bacteria on clay minerals and iron oxide.

    PubMed

    Cao, Yuanyuan; Wei, Xing; Cai, Peng; Huang, Qiaoyun; Rong, Xinming; Liang, Wei

    2011-03-01

    The adsorption of extracellular polymeric substances (EPS) from Bacillus subtilis on montmorillonite, kaolinite and goethite was investigated as a function of pH and ionic strength using batch studies coupled with Fourier transform infrared (FTIR) spectroscopy. The adsorption isotherms of EPS on minerals conformed to the Langmuir equation. The amount of EPS-C and -N adsorbed followed the sequence of montmorillonite>goethite>kaolinite. However, EPS-P adsorption was in the order of goethite>montmorillonite>kaolinite. A marked decrease in the mass fraction of EPS adsorption on minerals was observed with the increase of final pH from 3.1 to 8.3. Calcium ion was more efficient than sodium ion in promoting EPS adsorption on minerals. At various pH values and ionic strength, the mass fraction of EPS-N was higher than those of EPS-C and -P on montmorillonite and kaolinite, while the mass fraction of EPS-P was the highest on goethite. These results suggest that proteinaceous constituents were adsorbed preferentially on montmorillonite and kaolinite, and phosphorylated macromolecules were absorbed preferentially on goethite. Adsorption of EPS on clay minerals resulted in obvious shifts of infrared absorption bands of adsorbed water molecules, showing the importance of hydrogen bonding in EPS adsorption. The highest K values in equilibrium adsorption and FTIR are consistent with ligand exchange of EPS phosphate groups for goethite surface. The information obtained is of fundamental significance for understanding interfacial reactions between microorganisms and minerals. PMID:21130614

  15. Development and evaluation of a new sorption model for organic cations in soil: contributions from organic matter and clay minerals.

    PubMed

    Droge, Steven T J; Goss, Kai-Uwe

    2013-12-17

    This study evaluates a newly proposed cation-exchange model that defines the sorption of organic cations to soil as a summed contribution of sorption to organic matter (OM) and sorption to phyllosilicate clay minerals. Sorption to OM is normalized to the fraction organic carbon (fOC), and sorption to clay is normalized to the estimated cation-exchange capacity attributed to clay minerals (CECCLAY). Sorption affinity is specified to a fixed medium composition, with correction factors for other electrolyte concentrations. The model applies measured sorption coefficients to one reference OM material and one clay mineral. If measured values are absent, then empirical relationships are available on the basis of molecular volume and amine type in combination with corrective increments for specific polar moieties. The model is tested using new sorption data generated at pH 6 for two Eurosoils, one enriched in clay and the other, OM, using 29 strong bases (pKa > 8). Using experimental data on reference materials for all tested compounds, model predictions for the two soils differed on average by only -0.1 ± 0.4 log units from measured sorption affinities. Within the chemical applicability domain, the model can also be applied successfully to various reported soil sorption data for organic cations. Particularly for clayish soils, the model shows that sorption of organic cations to clay minerals accounts for more than 90% of the overall affinity.

  16. The First X-ray Diffraction Patterns of Clay Minerals from Gale Crater

    NASA Technical Reports Server (NTRS)

    Bristow, Thomas; Blake, David; Bish, David L.; Vaniman, David; Ming, Douglas W.; Morris, Richard V.; Chipera, Steve; Rampe, Elizabeth B.; Farmer, Jack, D.; Treiman, Allan H; Downs, Robert; Morrison, Shaunna; Achilles, Cherie; DesMarais, David J.; Crisp, Joy A.; Sarrazin, Philippe; Morookian, John Michael; Grotzinger. John P.

    2013-01-01

    The Mars Science Laboratory (MSL) Rover, Curiosity spent approx 150 sols at Yellowknife Bay (YKB) studying a section of fluvio-lacustrine sedimentary rocks (with potential indications of volcanic influence), informally known as the Yellowknife Bay formation. YKB lies in a distal region of the Peace Vallis alluvial fan, which extends from the northern rim of Gale Crater toward the dune field at the base of Mt Sharp. Sedimentological and stratigraphic observations are consistent with the Yellowknife Bay formation being part of a distal fan deposit, which could be as young as middle Hesperian to even early Amazonian in age (approx 3.5 to 2.5 Ga). The Yellowknife Bay formation hosts a unit of mudstone called the Sheepbed member. Curiosity obtained powdered rock samples from two drill holes in the Sheepbed Member, named John Klein and Cumberland, and delivered them to instruments in Curiosity. Data from CheMin, a combined X-ray diffraction (XRD)/X-ray fluorescence instrument (XRF), has allowed detailed mineralogical analysis of mudstone powders revealing a clay mineral component of approx 20 wt.% in each sample. The clay minerals are important indicators of paleoenvironmental conditions and sensitive recorders of post-depositional alteration processes. The XRD pattern of John Klein reveals a 021 band consistent with a trioctahedral phyllosilicate. A broad peak at approx 10A with a slight inflexion at approx 12A indicates the presence of 2:1 type clay minerals in the John Klein sample. The trioctahedral nature of the clay minerals, breadth of the basal reflection, and presence of a minor component with larger basal spacing suggests that John Klein contains a trioctahedral smectite (probably saponite), whose interlayer is largely collapsed because of the low-humidity conditions. The XRD patterns show no evidence of corrensite (mixed-layer chlorite/smectite) or chlorite, which are typical diagenetic products of trioctahedral smectites when subjected to burial and heating

  17. Paleoenvironmental Implications of Clay Minerals at Yellowknife Bay, Gale Crater, Mars

    NASA Technical Reports Server (NTRS)

    Bristow, Thomas F.; Blake, David F.

    2014-01-01

    The Mars Science Laboratory (MSL) Rover, Curiosity spent approx 150 sols at Yellowknife Bay (YKB) studying a section of fluvio-lacustrine sedimentary rocks (with potential indications of volcanic influence), informally known as the Yellowknife Bay formation. YKB lies in a distal region of the Peace Vallis alluvial fan, which extends from the northern rim of Gale Crater toward the dune field at the base of Mt Sharp. Sedimentological and stratigraphic observations are consistent with the Yellowknife Bay formation being part of a distal fan deposit, which could be as young as middle Hesperian to even early Amazonian in age (approx. 3.5 to 2.5 Ga). The Yellowknife Bay formation hosts a unit of mudstone called the Sheepbed member. Curiosity obtained powdered rock samples from two drill holes in the Sheepbed Member, named John Klein and Cumberland, and delivered them to instruments in Curiosity. Data from CheMin, a combined X-ray diffraction (XRD)/X-ray fluorescence instrument (XRF), has allowed detailed mineralogical analysis of mudstone powders revealing a clay mineral component of approx. 20 wt.% in each sample. The clay minerals are important indicators of paleoenvironmental conditions and sensitive recorders of post-depositional alteration processes. The XRD pattern of John Klein reveals a 02l band consistent with a trioctahedral phyllosilicate. A broad peak at approx. 10A with a slight inflexion at approx. 12A indicates the presence of 2:1 type clay minerals in the John Klein sample. The trioctahedral nature of the clay minerals, breadth of the basal reflection, and presence of a minor component with larger basal spacing suggests that John Klein contains a trioctahedral smectite (probably saponite), whose interlayer is largely collapsed because of the low-humidity conditions. The XRD patterns show no evidence of corrensite (mixed-layer chlorite/smectite) or chlorite, which are typical diagenetic products of trioctahedral smectites when subjected to burial and

  18. Effect of clay minerals and nanoparticles on chromium fractionation in soil contaminated with leather factory waste.

    PubMed

    Taghipour, Marzieh; Jalali, Mohsen

    2015-10-30

    This study was conducted to investigate the effect of time, clay minerals and nanoparticles (NPs) on chromium (Cr) fractionation in a soil contaminated with leather factory waste (LFW). Soil was mixed with LFW, then, the contaminated soils were treated with clay minerals (bentonite and zeolite) and nanoparticles (MgO, TiO2 and ZnO) at 5% and 1%, respectively. The samples were incubated for 15-180 days at 25 °C and constant moisture. After incubation, Cr in control and treated soils was fractionated by the sequential extraction procedure. The distribution of various Cr fractions in control soil indicated that the greatest amounts of Cr were found in the residual fraction (RES) followed by the carbonate (CAR), organic matter (OM) and exchangeable (EXC) fractions. The addition of LFW in soils increased Cr concentration in all fractions. The higher proportion of EXC fraction in the soil treated with LFW indicates its higher potential of leaching and runoff transport. In all treated soils, the RES fraction was increased, while EXC and OM fractions were decreased during incubation. The results indicated that NPs are effective adsorbent for the removal of Cr ions from LFW treated soil, and they could be useful in reducing their environment risk.

  19. Effect of clay minerals and nanoparticles on chromium fractionation in soil contaminated with leather factory waste.

    PubMed

    Taghipour, Marzieh; Jalali, Mohsen

    2015-10-30

    This study was conducted to investigate the effect of time, clay minerals and nanoparticles (NPs) on chromium (Cr) fractionation in a soil contaminated with leather factory waste (LFW). Soil was mixed with LFW, then, the contaminated soils were treated with clay minerals (bentonite and zeolite) and nanoparticles (MgO, TiO2 and ZnO) at 5% and 1%, respectively. The samples were incubated for 15-180 days at 25 °C and constant moisture. After incubation, Cr in control and treated soils was fractionated by the sequential extraction procedure. The distribution of various Cr fractions in control soil indicated that the greatest amounts of Cr were found in the residual fraction (RES) followed by the carbonate (CAR), organic matter (OM) and exchangeable (EXC) fractions. The addition of LFW in soils increased Cr concentration in all fractions. The higher proportion of EXC fraction in the soil treated with LFW indicates its higher potential of leaching and runoff transport. In all treated soils, the RES fraction was increased, while EXC and OM fractions were decreased during incubation. The results indicated that NPs are effective adsorbent for the removal of Cr ions from LFW treated soil, and they could be useful in reducing their environment risk. PMID:25956643

  20. Removal of polycyclic aromatic hydrocarbons (PAHs) from inorganic clay mineral: Bentonite.

    PubMed

    Karaca, Gizem; Baskaya, Hüseyin S; Tasdemir, Yücel

    2016-01-01

    There has been limited study of the removal of polycyclic aromatic hydrocarbons (PAHs) from inorganic clay minerals. Determining the amount of PAH removal is important in predicting their environmental fate. This study was carried out to the degradation and evaporation of PAHs from bentonite, which is an inorganic clay mineral. UV apparatus was designed specifically for the experiments. The impacts of temperature, UV, titanium dioxide (TiO2), and diethylamine (DEA) on PAH removal were determined. After 24 h, 75 and 44 % of ∑12 PAH in the bentonite were removed with and without UV rays, respectively. DEA was more effective as a photocatalyst than TiO2 during UV application. The ∑12 PAH removal ratio reached 88 % with the addition of DEA to the bentonite. It was concluded that PAHs were photodegraded at high ratios when the bentonite samples were exposed to UV radiation in the presence of a photocatalyst. At the end of all the PAH removal applications, higher evaporation ratios were obtained for 3-ring compounds than for heavier ones. More than 60 % of the amount of ∑12 PAH evaporated consisted of 3-ring compounds.

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

    SciTech Connect

    Collins, Y.E.

    1987-01-01

    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.

  2. Stable isotope geochemistry of clay minerals from fossil and active hydrothermal systems, southwestern Hokkaido, Japan

    SciTech Connect

    Marumo, Katsumi; Longstaffe, F.J.; Matsubaya, Osamu

    1995-06-01

    Miocene submarine to Quaternary terrestrial volcanism in southwestern Hokkaido, Japan, is associated with hydrothermal clay alteration and mineralization, including Kuroko-type deposits at Kagenosawa (14.2 Ma, Cu > Zn, Pb > Au) and Minamishiraoi (12.5 Ma, Ba > Zn, Pb, Cu), vein-style at Noboribetsu ({le} 1.8 Ma). The {delta}D and {delta}{sup 18}O values of mica (sericite), mica-smectite, chlorite, chlorite-smectite, nacrite, dickite, kaolinite, and smectite were used to deduce the type(s) of hydrothermal fluid at each locality. Calculated compositions for Minamishiraoi and Kagenosawa fluids suggest that seawater was dominant, but some mixing with magmatic water is also indicated, particularly for the polymetallic Kagenosawa deposit. Hydrothermal fluids at Date, Chitose, and the Noboribetsu geothermal area were dominated by meteoric water. The {delta}D and {delta}{sup 18}O values of modern hot-spring waters at Noboribetsu closely parallel fluid compositions calculated for the clay alteration at Date, Chitose, and Noboribetsu. In vacuo TG patterns of other smectitic clays suggested gradual loss of hydroxyl-groups beginning near 200{degrees}C, rather than the more typical distinct separation between interlayer water at <200{degrees}C and hydroxyl-groups at >400{degrees}C. This behaviour constrains the maximum temperature that can be used for in vacuo preheating. Furthermore, shifts to lower {delta}D values (by as much as 19{per_thousand}) were obtained when this smectite was dispersed in low-D water for three weeks, perhaps indicating isotopic exchange. However, with appropriate care, {delta}D values obtained by conventional procedures (including preheating to {le}200{degrees}C) normally reproduced natural compositions of the smectitic clays with acceptable accuracy and precision.

  3. Zeolite-clay mineral zonation of volcaniclastic sediments within the McDermitt caldera complex of Nevada and Oregon

    USGS Publications Warehouse

    Glanzman, Richard K.; Rytuba, James J.

    1979-01-01

    Volcaniclastic sediments deposited in the moat of the collapsed McDermitt caldera complex have been altered chiefly to zeolites and potassium feldspar. The original rhyolitic and peralkaline ash-flow tuffs are included in conglomerates at the caldera rims and grade into a lacustrine series near the center of the collapse. The tuffs show a lateral zeolitic alteration from almost fresh glass to clinoptilolite, clinoptilolite-mordenite, and erionite; to analcime-potassium feldspar; and finally to potassium feldspar. Vertical zonation is in approximately the same order. Clay minerals in associated mudstones, on the other hand, show little lateral variation but a distinct vertical zonation, having a basal dioctahedral smectite, a medial trioctahedral smectite, and an upper dioctahedral smectite. The medial trioctahedral smectite is enriched in lithium (as much as 6,800 ppm Li). Hydrothermal alteration of the volcaniclastic sediments, forming both mercury and uranium deposits, caused a distinct zeolite and clay-mineral zonation within the general lateral zonation. The center of alteration is generally potassium feldspar, commonly associated with alunite. Potassium feldspar grades laterally and vertically to either clinoptilolite or clinoptilolite-mordenite, generally associated with gypsum. This zone then grades vertically and laterally into fresh glass. The clay minerals are a dioctahedral smectite, a mixed-layer clay mineral, and a 7-A clay mineral. The mixed-layer and 7-A clay minerals are associated with the potassium feldspar-alunite zone of alteration, and the dioctahedral smectite is associated with clinoptilolite. This mineralogical zonation may be an exploration guide for mercury and uranium mineralization in the caldera complex environment.

  4. 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)

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

    2004-12-01

    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.

  5. Microorganism-induced weathering of clay minerals in a hydromorphic soil

    NASA Astrophysics Data System (ADS)

    Hong, Hanlie; Fang, Qian; Cheng, Liuling; Wang, Chaowen; Churchman, Gordon Jock

    2016-07-01

    In order to improve the understanding of factors influencing weathering in hydromorphic soils, the clay mineral and chemical compositions, iron (hydr)oxides, organic compounds, and Sr and Nd isotopic compositions, of hydromorphic soils on the banks of the Liangzi Lake, Hubei province, south China, were investigated. The B horizon in the lower profile exhibits a distinct net-like pattern, with abundant short white veins within the red-brown matrix. Their various 87Sr/86Sr and 143Nd/144Nd isotopic compositions showed only small variations of 0.7270-0.7235 and 0.51200-0.51204, respectively, consistent with the composition of Yangtze River sediments, indicating that the soils were all derived from alluvium from the catchment. The white veins contained notably more SiO2, Al2O3, TiO2, and mobile elements relative to the red-brown matrix, while they both showed similar values for the chemical index of alteration of 86.7 and 87.1, respectively, and displayed similar degrees of weathering. The clay minerals in A, AE, and E horizons of the soil profile were illite, kaolinite, and mixed-layer illite-smectite. These same three clay minerals comprised the white net-like veins in the soil B horizon, whereas only illite and kaolinite were observed in the red-brown matrix. Iron (hydr)oxides in A, AE, and E horizons of the soil profile were hematite and goethite, whereas in the red-brown matrix of the B horizon they were hematite, goethite, and ferrihydrite. Different organic compounds were observed for the white vein and the red-brown matrix in the soil B horizon: an 18:2 fatty acid biomarker for fungi in the net-like vein, but not in the red-brown matrix. Compared with the red-brown matrix, the white net-like vein also clearly contained more mono-unsaturated fatty acids, which are sometimes associated with bacteria that have the capacity to reduce Fe(III). Thus, migration of iron and the formation of the net-like veins involved the participation of biota during the hydromorphic

  6. Ball clay

    USGS Publications Warehouse

    Virta, R.L.

    2007-01-01

    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.

  7. Spectroscopic evidence for Fe(II)-Fe(III) electron transfer at clay mineral edge and basal sites.

    PubMed

    Neumann, Anke; Olson, Tyler L; Scherer, Michelle M

    2013-07-01

    Despite the importance of Fe redox cycling in clay minerals, the mechanism and location of electron transfer remain unclear. More specifically, there is some controversy whether electron transfer can occur through both basal and edge surfaces. Here we used Mössbauer spectroscopy combined with selective chemical extractions to study electron transfer from Fe(II) sorbed to basal planes and edge OH-groups of clay mineral NAu-1. Fe(II) sorbed predominantly to basal planes at pH values below 6.0 and to edge OH-groups at pH value 7.5. Significant electron transfer occurred from edge OH-group bound Fe(II) at pH 7.5, whereas electron transfer from basal plane-sorbed Fe(II) to structural Fe(III) in clay mineral NAu-1 at pH 4.0 and 6.0 occurred but to a much lower extent than from edge-bound Fe(II). Mössbauer hyperfine parameters for Fe(II)-reacted NAu-1 at pH 7.5 were consistent with structural Fe(II), whereas values found at pH 4.0 and 6.0 were indicative of binding environments similar to basal plane-sorbed Fe(II). Reference experiments with Fe-free synthetic montmorillonite SYn-1 provided supporting evidence for the assignment of the hyperfine parameters to Fe(II) bound to basal planes and edge OH-groups. Our findings demonstrate that electron transfer to structural Fe in clay minerals can occur from Fe(II) sorbed to both basal planes and edge OH-groups. These findings require us to reassess the mechanisms of abiotic and microbial Fe reduction in clay minerals as well as the importance of Fe-bearing clay minerals as a renewable source of redox equivalents in subsurface environments.

  8. Soft X-ray spectromicroscopy study of mineral-organic matter associations in pasture soil clay fractions.

    PubMed

    Chen, Chunmei; Dynes, James J; Wang, Jian; Karunakaran, Chithra; Sparks, Donald L

    2014-06-17

    There is a growing acceptance that associations with soil minerals may be the most important overarching stabilization mechanism for soil organic matter. However, direct investigation of organo-mineral associations has been hampered by a lack of methods that can simultaneously characterize organic matter (OM) and soil minerals. In this study, STXM-NEXAFS spectroscopy at the C 1s, Ca 2p, Fe 2p, Al 1s, and Si 1s edges was used to investigate C associations with Ca, Fe, Al, and Si species in soil clay fractions from an upland pasture hillslope. Bulk techniques including C and N NEXAFS, Fe K-edge EXAFS spectroscopy, and XRD were applied to provide additional information. Results demonstrated that C was associated with Ca, Fe, Al, and Si with no separate phase in soil clay particles. In soil clay particles, the pervasive C forms were aromatic C, carboxyl C, and polysaccharides with the relative abundance of carboxyl C and polysaccharides varying spatially at the submicrometer scale. Only limited regions in the soil clay particles had aliphatic C. Good C-Ca spatial correlations were found for soil clay particles with no CaCO3, suggesting a strong role of Ca in organo-mineral assemblage formation. Fe EXAFS showed that about 50% of the total Fe in soils was contained in Fe oxides, whereas Fe-bearing aluminosilicates (vermiculite and Illite) accounted for another 50%. Fe oxides in the soil were mainly crystalline goethite and hematite, with lesser amounts of poorly crystalline ferrihydrite. XRD revealed that soil clay aluminosilicates were hydroxy-interlayered vermiculite, Illite, and kaolinite. C showed similar correlation with Fe to Al and Si, implying a similar association of Fe oxides and aluminosilicates with organic matter in organo-mineral associations. These direct microscopic determinations can help improve understanding of organo-mineral interactions in soils.

  9. Quality-assured evaluation of effective porosity using fit-for-purpose estimates of clay-mineral volume fraction

    NASA Astrophysics Data System (ADS)

    Worthington, Paul F.

    2010-05-01

    Reservoirs that contain dispersed clay minerals traditionally have been evaluated petrophysically using either the effective or the total porosity system. The major weakness of the former is its reliance on "shale" volume fraction ( Vsh) as a clay-mineral indicator in the determination of effective porosity from well logs. Downhole clay-mineral indicators have usually delivered overestimates of fractional clay-mineral volume ( Vcm) because they use as a reference nearby shale beds that are often assumed to comprise clay minerals exclusively, whereas those beds also include quartzitic silts and other detritus. For this reason, effective porosity is often underestimated significantly, and this shortfall transmits to computed hydrocarbons in place and thence to estimates of ultimate recovery. The problem is overcome here by using, as proxy groundtruths, core porosities that have been upscaled to match the spatial resolutions of porosity logs. Matrix and fluid properties are established over clean intervals in the usual way. Log-derived values of Vsh are tuned so that, on average, the resulting log-derived porosities match the corresponding core porosities over an evaluation interval. In this way, Vsh is rendered fit for purpose as an indicator of clay-mineral content Vcm for purposes of evaluating effective porosity. The method is conditioned to deliver a value of effective porosity that shows overall agreement with core porosity to within the limits of uncertainty of the laboratory measurements. This is achieved through function-, reservoir- and tool-specific Vsh reduction factors that can be applied to downhole estimates of clay-mineral content over uncored intervals of similar reservoir character. As expected, the reduction factors can also vary for different measurement conditions. The reduction factors lie in the range of 0.29-0.80, which means that in its raw form, log-derived Vsh can overestimate the clay-mineral content by more than a factor of three. This

  10. First-principles study of cesium adsorption to weathered micaceous clay minerals

    NASA Astrophysics Data System (ADS)

    Okumura, Masahiko; Nakamura, Hiroki; Machida, Masahiko

    2014-05-01

    A large amount of radioactive nuclides was produced into environment due to the Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident. Residents near FDNPP were suffering from radioactive cesium and then evacuated, because which has long half-life and is retained by surface soil for long time. The Japanese government has been decontaminating the cesium by removing the surface soil in order to return them to their home. This decontamination method is very effective, but which produces huge amount of waste soil. This becomes another big problem in Fukushima, because it is not easy to find large storage sites. Then effective and economical methods to reduce the volume of the waste soil are needed. However, it has not been invented yet. One of the reasons is lack of knowledge about microscopic process of adsorption/desorption of cesium to/from soil. It is known that weathered micaceous clay minerals play crucial role on adsorption and retention of cesium. They are expected to have special sorption sites, called frayed edge sites (FESs), which adsorb cesium selectively and irreversibly. Properties of FES have been intensely investigated by experiments. But microscopic details of the adsorption process on FES are still unclear. Because direct observation of the process with current experimental techniques is quite difficult. We investigated the adsorption of cesium to FES in muscovite, which is a typical micaceous clay mineral, via first-principles calculations (density functional theory). We made a minimal model of FES and evaluate the energy difference before and after cesium adsorption to FES. This is the first numerical modeling of FES. It was shown that FES does adsorb cesium if the weathering of muscovite has been weathered. In addition, we revealed the mechanism of cesium adsorption to FES, which is competition between ion radius of cesium and the degree of weathering. I plan to discuss volume reduction of the waste soil based on our result. Reference M. Okumura

  11. Terrestrial Analogs for Clay Minerals at Yellowknife Bay, Gale Crater, Mars

    NASA Astrophysics Data System (ADS)

    Treiman, A. H.; Morris, R. V.; Bristow, T.; Ming, D. W.; Achilles, C.; Bish, D. L.; Blake, D.; Vaniman, D.; Chipera, S.; Team, M.

    2013-12-01

    varieties may be contemporaneous. One sample shows agate (α-quartz) that was precipitated between the episodes of deposition of the fine-grained and coarse-grained ';griffithite.' ';Griffithite' is not unique as a possible terrestrial analog - some clay minerals from the Doushantou formation, China, have similar 02L diffraction bands, and many basalts contain smectites in vesicles and as replacements after olivine. Similar trioctahedral smectites occur also in the nakhlite martian meteorites - as veinlets and replacements of olivine. By understanding the formation of these terrestrial clays, we hope to constrain the nature and mechanism of formation of the Sheepbed clay mineral.

  12. Terrestrial Analogs for Clay Minerals at Yellowknife Bay, Gale Crater, Mars

    NASA Technical Reports Server (NTRS)

    Treiman, Allan H; Morris, Richard V.; Bristow, Thomas; Ming, Douglas W.; Achillies, Cherie; Bish, David L.; Blake, David; Vaniman, David; Chipera, Steve

    2013-01-01

    the last three varieties may be contemporaneous. One sample shows agate (alpha- quartz) that was precipitated between the episodes of deposition of the fine-grained and coarse-grained 'griffithite.' 'Griffithite' is not unique as a possible terrestrial analog - some clay minerals from the Doushantou formation, China, have similar 02L diffraction bands, and many basalts contain smectites in vesicles and as replacements after olivine. Similar trioctahedral smectites occur also in the nakhlite martian meteorites - as veinlets and replacements of olivine. By understanding the formation of these terrestrial clays, we hope to constrain the nature and mechanism of formation of the Sheepbed clay mineral.

  13. Understanding the role of clay minerals in the chromium(VI) bioremoval by Pseudomonas aeruginosa CCTCC AB93066 under growth condition: microscopic, spectroscopic and kinetic analysis.

    PubMed

    Kang, Chunxi; Wu, Pingxiao; Li, Yuewu; Ruan, Bo; Li, Liping; Tran, Lytuong; Zhu, Nengwu; Dang, Zhi

    2015-11-01

    Laboratory batch experiments were conducted to investigate the role of clay minerals, e.g., kaolinite and vermiculite, in microbial Cr(VI) reduction by Pseudomonas aeruginosa under growth condition in glucose-amended mediums as a method for treating Cr(VI)-contaminated subsurface environment such as soil. Our results indicated that glucose could acted as an essential electron donor, and clay minerals significantly enhanced microbial Cr(VI) reduction rates by improving the consumption rate of glucose and stimulating the growth and propagation of P. aeruginosa. Cr(VI) bioreduction by both free cells and clay minerals-amended cells followed the pseudo-first-order kinetic model, with the latter one fitting better. The mass balance analyses and X-ray photoelectron spectroscopy analysis found that Cr(VI) was reduced to Cr(III) and the adsorption of total chromium on clay minerals-bacteria complex was small, implying that Cr(VI) bioremoval was not mainly due to the adsorption of Cr(VI) onto cells or clay minerals or clay minerals-cells complex but mainly due to the Cr(VI) reduction capacity of P. aeruginosa under the experimental conditions studied (e.g., pH 7). Atomic force microscopy revealed that the addition of clay minerals (e.g. vermiculite) decreased the surface roughness of Cr(VI)-laden cells and changed the cell morphology and dimension. Fourier transform infrared spectroscopy revealed that organic matters such as aliphatic species and/or proteins played an important role in the combination of cells and clay minerals. Scanning electron microscopy confirmed the attachment of cells on the surface of clay minerals, indicating that clay minerals could provide a microenvironment to protect cells from Cr(VI) toxicity and serve as growth-supporting materials. These findings manifested the underlying influence of clay minerals on microbial reduction of Cr(VI) and gave an understanding of the interaction between pollutants, the environment and the biota.

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

    PubMed

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

    2012-06-01

    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 π-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.

  15. Preparation of porous clay minerals with organic-inorganic hybrid pillars using solvent-extraction route.

    PubMed

    Nakatsuji, Minori; Ishii, Ryo; Wang, Zheng-Ming; Ooi, Kenta

    2004-04-01

    A microporous clay mineral with organic-inorganic hybrid pillars was synthesized using a hydrochloric acid (HCl)/ethanol extraction method after intercalation of tetraethoxysilane (TEOS) or TEOS/methyltriethoxysilane (MTS) into the cetyltrimetylammonium ion (CTA)-exchanged vermiculite. The products retained their layered structure, due to the formation of stable pillars by the polymerization of hydrolyzed TEOS and MTS during the HCl/ethanol treatment. The BET surface areas, which increased to above 500 m2g(-1) with an increase in the HCl concentration up to 0.4 moldm(-3), are nearly equal to that of the calcined product obtained by the conventional method. However, the pore sizes of HCl/ethanol-treated materials were narrower than those of the calcined product, owing to the formation of the polysiloxane networks in the gallery. A water adsorption study showed that the product treated with a TEOS/MTS mixture had a hydrophobic surface as a result of the successful incorporation of methyl groups at the surface of the pillars. This novel method is advantageous for the synthesis of organophilic pillared clays with different kinds of organic materials in the interlayers. PMID:14985033

  16. The Imprint of Atmospheric Evolution in the D/H of Hesperian Clay Minerals on Mars

    NASA Technical Reports Server (NTRS)

    Mahaffy, P. R.; Webster, C. R.; Stern, J. C.; Brunner, A. E.; Atreya, S. K.; Conrad, P. G.; Domagal-Goldman, S.; Eigenbrode, J. L.; Flesch, G. J.; Christensen, L. E.; Franz, H. B.; Glavin, D. P.; Jones, J. H.; McAdam, A. C.; Pavlov, A. A.; Trainer, M. G.; Williford, K. H.

    2014-01-01

    The deuterium-to-hydrogen (D/H) ratio in strongly bound water or hydroxyl groups in ancient Martian clays retains the imprint of the water of formation of these minerals. Curiosity's Sample Analysis at Mars (SAM) experiment measured thermally evolved water and hydrogen gas released between 550 degrees Centigrade and 950 degrees Centigrade from samples of Hesperian-era Gale crater smectite to determine this isotope ratio. The D/H value is 3.0 (plus or minus 0.2) times the ratio in standard mean ocean water. The D/H ratio in this approximately 3-billion-year-old mudstone, which is half that of the present Martian atmosphere but substantially higher than that expected in very early Mars, indicates an extended history of hydrogen escape and desiccation of the planet.

  17. Isotope fractionation during Ca exchange on clay minerals in a marine environment

    NASA Astrophysics Data System (ADS)

    Ockert, C.; Gussone, N.; Kaufhold, S.; Teichert, B. M. A.

    2013-07-01

    In order to interpret marine porewater profiles it is mandatory to understand the behavior of calcium (Ca) and its isotopes during cation exchange in marine sediments. It has been proposed that the exchange of adsorbed Ca2+ for ammonium, which is a product of organic matter decomposition, results in the releases of light Ca from clay minerals into the porewater (Teichert et al., 2009). In order to investigate the effect of ammonium on Ca isotope fractionation, experiments with clay mineral separates (illites, montmorillonite, kaolinite) and natural marine sediments from the North Atlantic (Integrated Ocean Drilling Project Site U1306A) in artificial seawater were carried out at different temperatures (4, 14, 21 °C) and ammonium concentrations (100, 140, 180 mM). The results of the adsorption experiments, carried out in artificial seawater, show that during adsorption of Ca2+ the light Ca isotopes are favored over the heavier Ca isotopes. This effect is most prominent for the illite samples (1000lnα = -0.82 to -1.15) and kaolinite sample (1000lnα = -1.23 to -2.76), whereas montmorillonite and the natural marine sediments show smaller degrees of fractionation from the fluid in the range of -0.46 to +0.06‰. Determination of the desorbed Ca2+ is based on the adsorbed Ca2+ left on the exchanger and reveals that the desorbed Ca2+ has a significantly different isotopic signature from the surrounding fluid. In general, the degree of Ca isotope fractionation is dependent on the ammonium concentration, and does not show significant influence of temperature. Modeling the Ca2+ desorption induced by ammonium adsorption demonstrates, that according to the prevailing mineralogy and porewater:sediment ratio, desorbed Ca2+ has the potential to shift the porewater isotopy by up to -2.5‰ and needs to be considered when interpreting Ca isotope porewater profiles.

  18. A comparison of heavy mineral assemblage between the loess and the Red Clay sequences on the Chinese Loess Plateau

    NASA Astrophysics Data System (ADS)

    Peng, Wenbin; Wang, Zhao; Song, Yougui; Pfaff, Katharina; Luo, Zeng; Nie, Junsheng; Chen, Wenhan

    2016-06-01

    QEMSCAN-based (Quantitative Evaluation of Minerals by Scanning Electron Microscopy) heavy mineral analysis has recently been demonstrated an efficient way to allow a rapid extraction of provenance information from sediments. However, one key issue to correctly obtain a provenance signal using this technique is to clearly separate effects of diagenetic alteration on heavy minerals in sediments, especially in fine-grained loess. Here we compare heavy mineral assemblages of bottom Quaternary loess (L33) and upper Pliocene Red Clay of three sites on the Chinese Loess Plateau (CLP). Two sites (Chaona and Luochuan) with similar modern climate conditions show similar heavy mineral assemblages but contain much less of the unstable heavy mineral amphibole than the drier Xifeng site. This result provides strong evidence supporting that climate-caused diagenesis is an important factor controlling heavy mineral assemblages of fine-grained loess. However, heavy mineral assemblages are similar for loess and paleosol layers deposited after 0.5 Ma on the Chinese Loess Plateau regardless of climate differences, suggesting that time is also a factor controlling heavy mineral assemblages of loess and Red Clay. Our high resolution sampling of the upper Miocene-Pliocene Chaona Red Clay sequence reveals similar heavy mineral compositions with a minor amphibole content, different from the drier Xifeng site results of the same age. This result indicates that the monsoonal climate pattern might have been maintained since the late Miocene. Furthermore, it indicates that the heavy mineral method is promising in tracing provenance for sites northwest of the Xifeng site on the Loess Plateau.

  19. Clay fractions from a soil chronosequence after glacier retreat reveal the initial evolution of organo-mineral associations

    NASA Astrophysics Data System (ADS)

    Dümig, Alexander; Häusler, Werner; Steffens, Markus; Kögel-Knabner, Ingrid

    2012-05-01

    Interactions between organic and mineral constituents prolong the residence time of organic matter in soils. However, the structural organization and mechanisms of organic coverage on mineral surfaces as well as their development with time are still unclear. We used clay fractions from a soil chronosequence (15, 75 and 120 years) in the foreland of the retreating Damma glacier (Switzerland) and from mature soils outside the proglacial area (>700 and <3000 years) to elucidate the evolution of organo-mineral associations during initial soil formation. The chemical composition of the clay-bound organic matter (OM) was assessed by solid-state 13C NMR spectroscopy while the quantities of amino acids and neutral sugar monomers were determined after acid hydrolysis. The mineral phase was characterized by X-ray diffraction, oxalate extraction, specific surface area by N2 adsorption (BET approach), and cation exchange capacity at pH 7 (CECpH7). The last two methods were applied before and after H2O2 treatment. We found pronounced shifts in quantity and quality of OM during aging of the clay fractions, especially within the first one hundred years of soil formation. The strongly increasing organic carbon (OC) loading of clay-sized particles resulted in decreasing specific surface areas (SSA) of the mineral phases and increasing CECpH7. Thus, OC accumulation was faster than the supply of mineral surfaces and cation exchange capacity was mainly determined by the OC content. Clay-bound OC of the 15-year-old soils showed high proportions of carboxyl C and aromatic C. This may point to remnants of ancient OC which were inherited from the recently exposed glacial till. With increasing age (75 and 120 years), the relative proportions of carboxyl and aromatic C decreased. This was associated with increasing O-alkyl C proportions, whereas accumulation of alkyl C was mainly detected in clay fractions from the mature soils. These findings from solid-state 13C NMR spectroscopy are in

  20. The role of clay minerals in the preservation of organic matter in sediments of qinghai lake, NW China

    USGS Publications Warehouse

    Yu, B.; Dong, H.; Jiang, H.; Lv, G.; Eberl, D.; Li, S.; Kim, J.

    2009-01-01

    The role of saline lake sediments in preserving organic matter has long been recognized. In order to further understand the preservation mechanisms, the role of clay minerals was studied. Three sediment cores, 25, 57, and 500 cm long, were collected from Qinghai Lake, NW China, and dissected into multiple subsamples. Multiple techniques were employed, including density fractionation, X-ray diffraction, scanning and transmission electron microscopy (SEM and TEM), total organic carbon (TOC) and carbon compound analyses, and surface area determination. The sediments were oxic near the water-sediment interface, but became anoxic at depth. The clay mineral content was as much as 36.8%, consisting mostly of illite, chlorite, and halloysite. The TEM observations revealed that organic matter occurred primarily as organic matter-clay mineral aggregates. The TOC and clay mineral abundances are greatest in the mid-density fraction, with a positive correlation between the TOC and mineral surface area. The TOC of the bulk sediments ranges from 1 to 3% with the non-hydrocarbon fraction being predominant, followed by bitumen, saturated hydrocarbon, aromatic hydrocarbons, and chloroform-soluble bitumen. The bimodal distribution of carbon compounds of the saturated hydrocarbon fraction suggests that organic matter in the sediments was derived from two sources: terrestrial plants and microorganisms/algae. Depthrelated systematic changes in the distribution patterns of the carbon compounds suggest that the oxidizing conditions and microbial abundance near the water-sediment interface promote degradation of labile organic matter, probably in adsorbed form. The reducing conditions and small microbial biomass deeper in the sediments favor preservation of organic matter, because of the less labile nature of organic matter, probably occurring within clay mineral-organic matter aggregates that are inaccessible to microorganisms. These results have important implications for our

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

    SciTech Connect

    Fernandez, Rodrigo; Martirena, Fernando; Scrivener, Karen L.

    2011-01-15

    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.

  2. Surficial clay mineral distribution on the southwestern continental margin of India: evidence of input from the Bay of Bengal

    NASA Astrophysics Data System (ADS)

    Chauhan, Onkar S.; Gujar, A. R.

    1996-03-01

    Analyses of spatial distribution of clay minerals, sediment texture, and > 63 μm fractions of the grab samples from the S W continental margin of India exhibit: (i) higher contents of illite and chlorite on the lower slope and (ii) a well-defined no-clay zone on the entire shelf. Kaolinite and smectite are also present in significant quantities on the slope with traces of gibbsite and palygorskite in some samples. The high contents of illite and chlorite (clay minerals which are not abundant in the soils and estuarine sediments of this region) in the southern region of the study area are evidence for sediment contribution from the Bay of Bengal waters (BBW), which enter this region after the SW monsoon. Distribution trends of kaolinite, smectite, gibbsite, and laterite granules on the slope are suggestive of contribution from chemically weathered soils of Peninsular India.

  3. Effect of ionic strength on the adsorption of copper and chromium ions by vermiculite pure clay mineral.

    PubMed

    El-Bayaa, A A; Badawy, N A; Alkhalik, E Abd

    2009-10-30

    It is important to assess the effects of ionic strength when studying adsorption of metal ions on clay mineral because the background salt may complex metals and compete for adsorption sites. The sorption behavior of vermiculite pure clay mineral has been studied with respect to copper and chromium as a function of ionic strength in single metal ion solutions. Background electrolytes used in these experiments were KCl, NaCl and NH4Cl. The studies were conducted by a batch method at temperature 25 degrees C. The adsorption capacity and adsorption energy for each metal ion were calculated from the Langmuir adsorption isotherm. Also the competitive adsorption behavior of some heavy metal ions such as Cr(III), Cu(II), Ni(II) and Co(II) by vermiculite pure clay mineral was studied. The result shows the competition between coexisting heavy metal cations for the same adsorption sites of an adsorbent. However, when trivalent metal was added to the solution it competitively replaced divalent ions that had been previously adsorbed onto the vermiculite pure clay mineral, resulting in the desorption of these metals into the solution. PMID:19524366

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

    PubMed

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

    2013-03-01

    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.

  5. Determination of the composition of the organic matter chemically stabilized by agricultural soil clay minerals: Spectroscopy and Density Fractionation

    NASA Astrophysics Data System (ADS)

    Oufqir, Sofia; Bloom, Paul; Toner, Brandy; Hatcher, Patrick

    2014-05-01

    The interactions between soil organic matter and clay minerals are considered important processes because of their ability to sequester C in soil for long periods of time, and hence control C in the global C cycle when present. However, differing results have been reported regarding the composition of the soil organic matter - aromatic fractions versus aliphatic fractions - associated with clay minerals. To clarify this critical issue and better understand the C sequestration process in soils, we aimed to determine the nature of the chemically bound natural organic matter on clay surfaces, and to probe the speciation and spatial distribution of C in the soil clay nanoparticles using direct spectroscopic measurements namely solid-state CP-MAS and DP-MAS 13C NMR spectroscopy, x-ray diffraction spectroscopy (XRD), and scanning transmission x-ray microscopy (STXM). We tested the hypotheses that peptides and polysaccharides are stabilized by the smectite-illite clay while the lipids and black carbon are a separate phase; and that they are evenly distributed on clay surfaces. A soil clay fraction (5.5% organic C) was isolated from the surface of a prairie soil (Mollisol) in southwestern Minnesota, characterized by a pH 6.0, 32.5% clay content, and 3.7% organic carbon, using a sonication-sedimentation-siphoning process in distilled water. Then was subjected to density separation combined with low energy ultrasonic dispersion to separate the free organic and black C (light fraction) from the chemically bound C (heavy fraction). The XRD results indicated a dominance of interstratified smectite-illite clays in soil. The 13C-NMR spectra of the soil clay fraction suggested that polysaccharides and polypeptides are the prevailing components of the organic matter associated with the mineral clay, with only a minor component of aromatic C. The light fraction has strong alkyl C-H bands characteristic of fatty acids plus strong C-O bands characteristic of polysaccharides, including

  6. Lithologic Control on Secondary Clay Mineral Formation in the Valles Caldera, New Mexico

    NASA Astrophysics Data System (ADS)

    Caylor, E.; Rasmussen, C.; Dhakal, P.

    2015-12-01

    Understanding the transformation of rock to soil is central to landscape evolution and ecosystem function. The objective of this study was to examine controls on secondary mineral formation in a forested catchment in the Catalina-Jemez CZO. We hypothesized landscape position controls the type of secondary minerals formed in that well-drained hillslopes favor Si-poor secondary phases such as kaolinite, whereas poorly drained portions of the landscape that collect solutes from surrounding areas favor formation of Si-rich secondary phases such as smectite. The study focused on a catchment in Valles Caldera in northern New Mexico where soils are derived from a mix of rhyolitic volcanic material, vegetation includes a mixed conifer forest, and climate is characterized by a mean annual precipitation of ~800 mm yr-1 and mean annual temperature of 4.5°C. Soils were collected at the soil-saprolite boundary from three landscape positions, classified as well drained hillslope, poorly drained convergent area, and poorly drained hill slope. Clay fractions were isolated and analyzed using a combination of quantitative and qualitative x-ray diffraction (XRD) analyses and thermal analysis. Quantitative XRD of random powder mounts indicated the presence of both primary phases such as quartz, and alkali and plagioclase feldspars, and secondary phases that include illite, Fe-oxyhydroxides including both goethite and hematite, kaolinite, and smectite. The clay fractions were dominated by smectite ranging from 36-42%, illite ranging from 21-35%, and kaolinite ranging from 1-8%. Qualitative XRD of oriented mounts confirmed the presence of smectite in all samples, with varying degrees of interlayering and interstratification. In contrast to our hypothesis, results indicated that secondary mineral assemblage was not strongly controlled by landscape position, but rather varied with underlying variation in lithology. The catchment is underlain by a combination of porphorytic rhyolite and

  7. Effect of organic matter properties, clay mineral type and thermal maturity on gas adsorption in organic-rich shale systems

    USGS Publications Warehouse

    Zhang, Tongwei; Ellis, Geoffrey S.; Ruppel, Stephen C.; Milliken, Kitty; Lewan, Mike; Sun, Xun; Baez, Luis; Beeney, Ken; Sonnenberg, Steve

    2013-01-01

    A series of CH4 adsorption experiments on natural organic-rich shales, isolated kerogen, clay-rich rocks, and artificially matured Woodford Shale samples were conducted under dry conditions. Our results indicate that physisorption is a dominant process for CH4 sorption, both on organic-rich shales and clay minerals. The Brunauer–Emmett–Teller (BET) surface area of the investigated samples is linearly correlated with the CH4 sorption capacity in both organic-rich shales and clay-rich rocks. The presence of organic matter is a primary control on gas adsorption in shale-gas systems, and the gas-sorption capacity is determined by total organic carbon (TOC) content, organic-matter type, and thermal maturity. A large number of nanopores, in the 2–50 nm size range, were created during organic-matter thermal decomposition, and they significantly contributed to the surface area. Consequently, methane-sorption capacity increases with increasing thermal maturity due to the presence of nanopores produced during organic-matter decomposition. Furthermore, CH4 sorption on clay minerals is mainly controlled by the type of clay mineral present. In terms of relative CH4 sorption capacity: montmorillonite ≫ illite – smectite mixed layer > kaolinite > chlorite > illite. The effect of rock properties (organic matter content, type, maturity, and clay minerals) on CH4 adsorption can be quantified with the heat of adsorption and the standard entropy, which are determined from adsorption isotherms at different temperatures. For clay-mineral rich rocks, the heat of adsorption (q) ranges from 9.4 to 16.6 kJ/mol. These values are considerably smaller than those for CH4 adsorption on kerogen (21.9–28 kJ/mol) and organic-rich shales (15.1–18.4 kJ/mol). The standard entropy (Δs°) ranges from -64.8 to -79.5 J/mol/K for clay minerals, -68.1 to -111.3 J/mol/K for kerogen, and -76.0 to -84.6 J/mol/K for organic-rich shales. The affinity of CH4 molecules for sorption on organic matter

  8. Calcium-ammonium exchange experiments on clay minerals using a (45)Ca tracer technique in marine pore water.

    PubMed

    Ockert, Charlotte; Wehrmann, Laura M; Kaufhold, Stephan; Ferdelman, Tim G; Teichert, Barbara M A; Gussone, Nikolaus

    2014-01-01

    Understanding cation exchange processes is important for evaluating early diagenetic and synsedimentary processes taking place in marine sediments. To quantify calcium (Ca) exchange and Ca-ammonium exchange in a seawater environment, we performed experiments with a radioactive (45)Ca tracer on clay mineral standards (Fithian illite, montmorillonite and kaolinite) and marine sediments from the North Atlantic Integrated Ocean Drilling Program Site U1306A in artificial seawater (ASW). The results show that equilibrium during the initial attachment of Ca as well as the exchange of Ca by [Formula: see text] is attained in less than 2 min. On average 8-20% of the exchangeable sites of the clay minerals were occupied by Ca in a seawater medium. The conditional selectivity coefficient, describing the [Formula: see text] exchange in ASW is mineral specific and it was determined to be 0.07 for montmorillonite, 0.05 for a natural marine sediment and 0.013 for Fithian illite.

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

    SciTech Connect

    Collins, Y.E.; Stotzky, G. )

    1992-05-01

    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.

  10. Clays, common

    USGS Publications Warehouse

    Virta, R.L.

    1998-01-01

    Part of a special section on the state of industrial minerals in 1997. The state of the common clay industry worldwide for 1997 is discussed. Sales of common clay in the U.S. increased from 26.2 Mt in 1996 to an estimated 26.5 Mt in 1997. The amount of common clay and shale used to produce structural clay products in 1997 was estimated at 13.8 Mt.

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

    SciTech Connect

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

    2004-03-28

    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.

  12. Controls on clay minerals assemblages in an early paleogene nonmarine succession: Implications for the volcanic and paleoclimatic record of extra-andean patagonia, Argentina

    NASA Astrophysics Data System (ADS)

    Raigemborn, María Sol; Gómez-Peral, Lucía E.; Krause, Javier Marcelo; Matheos, Sergio Daniel

    2014-07-01

    The distribution of the clay minerals of the Banco Negro Inferior-Río Chico Group succession (BNI-RC), a middle Danian-middle Eocene mainly continental epiclastic-pyroclastic succession exposed in the Golfo San Jorge Basin, extra-Andean Patagonia (∼46° LS), is assessed in order to determine the possible origin of clay and specific non-clay minerals using X-ray diffraction and scanning electron microscopy analyses. The control over the clay mineralogy of the sedimentary settings, contemporary volcanism, paleoclimate and weathering conditions is considered. A paleoclimatic reconstruction is provided and correlated with the main global warming events that occurred during the early Paleogene. Mineralogical analyses of BNI-RC demonstrate that smectite and kaolin minerals (kaolinite, halloysite and kaolinite/smectite mixed layers) are the main clay minerals, whereas silica polymorphs (volcanic glass and opal) are common non-clay minerals. Throughout the succession, smectite and kaolin minerals are arranged in different proportions in the three clay-mineral assemblages. These show a general vertical trend in which the smectite-dominated assemblage (S1) is replaced by the smectite-dominated assemblage associated with other clays (S2) and the kaolinite-dominated assemblage (K), and finally by S2 up-section. The detailed micromorphological analysis of the clay and non-clay minerals allows us to establish that the origins of these are by volcanic ash weathering, authigenic and pedogenic, and that different stages in the evolution of mineral transformations have occurred. The supply of labile pyroclastic material from an active volcanic area located to the northwest of the study area could have acted as precursor of the authigenic and volcanogenic minerals of the analyzed succession. Diverse fine-grained lithological facies (muddy and tuffaceous facies) and sedimentary settings (coastal swamp and transitional environments, and different fluvial systems) together with

  13. Adsorption of reovirus to clay minerals: effects of cation-exchange capacity, cation saturation, and surface area.

    PubMed Central

    Lipson, S M; Stotzky, G

    1983-01-01

    The adsorption of reovirus to clay minerals has been reported by several investigators, but the mechanisms defining this association have been studied only minimally. The purpose of this investigation was to elucidate the mechanisms involved with this interaction. More reovirus type 3 was adsorbed, in both distilled and synthetic estuarine water, by low concentrations of montmorillonite than by comparable concentrations of kaolinite containing a mixed complement of cations on the exchange complex. Adsorption to the clays was essentially immediate and was correlated with the cation-exchange capacity of the clays, indicating that adsorption was primarily to negatively charged sites on the clays. Adsorption was greater with low concentrations of clays in estuarine water than in distilled water, as the higher ionic strength of the estuarine water reduced the electrokinetic potential of both clay and virus particles. The addition of cations (as chloride salts) to distilled water enhanced adsorption, with divalent cations being more effective than monovalent cations and 10(-2) M resulting in more adsorption than 10(-3) M. Potassium ions suppressed reovirus adsorption to montmorillonite, probably by collapsing the clay lattices and preventing the expression of the interlayer-derived cation-exchange capacity. More virus was adsorbed by montmorillonite made homoionic to various mono-, di-, and trivalent cations (except by montmorillonite homoionic to potassium) than by comparable concentrations of kaolinite homoionic to the same cations. The sequence of the amount of adsorption to homoionic montmorillonite was Al greater than Ca greater than Mg greater than Na greater than K; the sequence of adsorption to kaolinite was Na greater than Al greater than Ca greater than Mg greater than K. The constant partition-type adsorption isotherms obtained when the clay concentration was maintained constant and the virus concentration was varied indicated that a fixed proportion of the

  14. Numerical Simulation of Injectivity Effects of Mineral Scaling and Clay Swelling in a Fractured Geothermal Reservoir

    SciTech Connect

    Xu, Tianfu; Pruess, Karsten

    2004-05-10

    A major concern in the development of hot dry rock (HDR) and hot fractured rock (HFR) reservoirs is achieving and maintaining adequate injectivity, while avoiding the development of preferential short-circuiting flow paths such as those caused by thermally-induced stress cracking. Past analyses of HDR and HFR reservoirs have tended to focus primarily on the coupling between hydrology (flow), heat transfer, and rock mechanics. Recent studies suggest that rock-fluid interactions and associated mineral dissolution and precipitation effects could have a major impact on the long-term performance of HFR reservoirs. The present paper uses recent European studies as a starting point to explore chemically-induced effects of fluid circulation in HFR systems. We examine ways in which the chemical composition of reinjected waters can be modified to improve reservoir performance by maintaining or even enhancing injectivity. Chemical manipulations considered here include pH modification and dilution with fresh water. We performed coupled thermo-hydrologic-chemical simulations in which the fractured medium was represented by a one-dimensional MINC model (multiple interacting continua), using the non-isothermal multi-phase reactive geochemical transport code TOUGHREACT. Results indicate that modifying the injection water chemistry can enhance mineral dissolution and reduce clay swelling. Chemical interactions between rocks and fluids will change a HFR reservoir over time, with some changes favorable and others not. A detailed, quantitative understanding of processes and mechanisms can suggest chemical methods for reservoir management, which may be employed to improve the performance of the geothermal system.

  15. Characterization of Adsorbed Alkali Metal Ions in 2:1 Type Clay Minerals from First-Principles Metadynamics.

    PubMed

    Ikeda, Takashi; Suzuki, Shinichi; Yaita, Tsuyoshi

    2015-07-30

    Adsorption states of alkali metal ions in three kinds of 2:1 type clay minerals are systematically investigated via first-principles-based metadynamics. Our reconstructed free energy surfaces in a two-dimensional space of coordination numbers specifically employed as collective variables for describing the interlayer cations show that an inner-sphere (IS) complex is preferentially formed for Cs(+) in the 2:1 type trioctahedral clay minerals with saponite-like compositions, where lighter alkali metal ions show a tendency to form an outer-sphere one instead. The strong preference for an IS complex observed for Cs(+) is found to result partially from the capability of recognizing selectively Cs(+) ions at the basal O atoms with the Lewis basicity significantly enhanced by the isomorphic substitution in tetrahedral sheets.

  16. Geochemical studies of clay minerals III. The determination of free silica and free alumina in montmorillonites

    USGS Publications Warehouse

    Foster, M.D.

    1953-01-01

    Determination of free silica by the method proposed made possible the derivation of logical formulas for several specimens of montmorillonites for which the formulas could not be derived from the analyses alone. Other montmorillonites, for which logical formulas could be derived from their analyses, were found to contain small amounts of free silica or free alumina. Others were found to contain neither free silica nor free alumina. The method consists of the following steps: (1) digestion of 1 g of the specimen with 0.5 N NaOH solution in a covered platinum crucible or dish on a steam bath for 4 hrs, stirring the mixture at 30-min intervals, (2) filtration of the undissolved material, followed by washing several times with 1% NaOH solution, (3) neutralization of the filtrate with HCl, addition of 5 ml HCl in excess and determination of SiO and Al2O3 in the usual way and (4) calculation of the amount of free SiO2 or free Al2O3 if any and the amount of attack of the clay structure by the treatment from the ratio of SiO2 to Al2O3 dissolved and the ratio of SiO2 to Al2O3 obtained on analysis. Tests with 5% Na2CO3 solution, the reagent formerly used for the solution of free SiO2 in rocks and minerals, showed that solution of opal by this reagent is always fractional, never complete, no matter how small the amount present or how long the period of treatment. Re-treatment of the sample results in 90-95% solution if 10 mg or less of opal is present, but for larger amounts of opal the percentage dissolved decreases as the amount present increases. On the other hand, 75 ml of 0.5 N NaOH completely dissolves as much as 400 mg of opal in 4 hrs digestion in a covered platinum crucible or dish, on a steam bath. However, a weaker solution or a shorter period of digestion does not effect complete solution. The same amount (75 ml) of 0.5 N NaOH also dissolves 90 mg of cristobalite and 57 mg of quartz having a grain size of less than 2 microns. Use of NaOH also permits determination

  17. Role of Clay Minerals in Long-Distance Transport of Landslides in Valles Marineris, Mars

    NASA Astrophysics Data System (ADS)

    Watkins, J.; Ehlmann, B. L.; Yin, A.

    2014-12-01

    Long-runout (> 50 km) subaerial landslides are rare on Earth, but are common features episodically shaping Mars' Valles Marineris (VM) trough system over the past 3.5 billion years. They display two end-member morphologies: a thick-skinned inner zone, characterized by fault-bounded, rotated blocks near their source region, and a thin-skinned, exceptionally long-runout outer zone, characterized by thin sheets spreading over 10s of km across the trough floor. Four decades of studies on the latter have resulted in two main competing hypotheses to explain their long-distance transport: (1) movement of landslides over layers of trapped air or soft materials containing ice or snow, enabling basal lubrication, and (2) fluidization of landslide materials with or without the presence of water and volatiles. To address this issue, we examine the mineralogic composition of landslides across VM using Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) near-infrared spectral data analysis coupled with detailed geologic mapping and morphometric analysis of satellite images. Our survey reveals a general correlation between transport distance, significant lateral spreading, and the presence of hydrated silicates among VM landslides. Given that smectite clay absorbs water into its layered crystal structure and can reduce the friction coefficient by a factor of three v. that of dry rocks, these results suggest that hydrated silicates played a decisive role in facilitating long-runout landslide transport in VM. We propose that, concurrent with downslope failure and sliding of broken trough-wall rock, frontal landslide masses overrode and entrained hydrated-silicate-bearing trough-floor deposits, lubricating the basal sliding zones and permitting the landslide outer zones to spread laterally while moving forward over the low-friction surface. The key participation of hydrated silicates in episodic, sustained landslide activity throughout the canyon implies that clay minerals

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

    PubMed

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

    2012-09-01

    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.

  19. Time and pH-dependent sorption of the veterinary antimicrobial sulfathiazole to clay minerals and ferrihydrite.

    PubMed

    Kahle, Maren; Stamm, Christian

    2007-07-01

    Substantial amounts of sulfonamides, ionizable, polar veterinary antimicrobials, may reach the environment by spreading of manure. Sorption to soils and sediments is a crucial but not sufficiently understood process influencing the environmental fate of sulfonamides. Therefore, we investigated sorption of sulfathiazole to clay minerals (montmorillonite, illite) and ferrihydrite for varying pH values and two contact times (1d, 14 d) under sterile conditions. Results were compared to sulfathiazole sorption to organic sorbents. Sulfathiazole sorption to inorganic sorbents exhibited pronounced pH dependence consistent with sorbate speciation and sorbent charge properties. While sulfathiazole cations were most important for sorption to clay minerals, followed by neutral species, ferrihydrite was a specific anion sorbent, showing significant sorption only between pH 5.5-7. Experiments revealed a substantial increase of sorption with time for ferrihydrite (pH 5.5-7) and illite (pH<5.5). Reasons may be disaggregation of clay minerals and, for ferrihydrite, diffusion and sorption of sulfathiazole in micropores. Independent of contact time and pH, sorption to inorganic sorbents was more than an order of magnitude lower than to organic sorbents. This implies that in many topsoils and sediments inorganic sorbents play a minor role. Our results highlight the need to account for contact time and speciation when predicting sulfonamide sorption in the environment.

  20. Effects of Clay Mineral Provenance and Clay Diagenesis on the Hanging Wall of a Megasplay Fault: Results from Riser Drilling, Nankai Trough Seismogenic Zone Experiment

    NASA Astrophysics Data System (ADS)

    Underwood, M.; Song, C.

    2015-12-01

    IODP Expedition 348 set a new record for sampling depth by scientific ocean drilling. Cores were recovered from the Nankai accretionary prism (Site C0002) at depths of 2163-2218 mbsf; cuttings were recovered continuously to 3058 mbsf. Shallower strata near the top of the accretionary prism are as young as 5.6 Ma, but the deeper interval has an apparent depositional age of 9.56-10.73 Ma. The structural context is within the hanging wall of a megasplay fault. Quantitative analyses of the clay mineral assemblages (using X-ray diffraction) show that the most abundant clay mineral is smectite, followed by illite, chlorite, and kaolinite. The mudstones at Site C0002 contain significantly lower percentages of smectite (~40% of clay-size fraction) as compared to coeval Miocene strata at Sites C0011 and C0012 in the nearby subduction inputs of Shikoku Basin (>50% of clay-size fraction). One likely reason for the difference is an overprint of detrital assemblages by smectite-to-illite diagenesis, which results in a steady down-hole increase in illite within the I/S mixed-layer phase. Another possible reason, however, is a spatial shift in depositional environments and detrital provenance. The mud-dominant facies of the accretionary prism is enigmatic (when compared to the frontal prism), and its original depositional setting remains uncertain. The accreted mudstones might have been deposited in a trench during a period in which supplies of sandy sediment were restricted. Northwestward migration of a triple junction that joins the Japan, Izu-Bonin, and Nankai plate boundaries also might have played a role, either by reducing the rate of plate convergence at ~7-12 Ma or by shifting pre-accretion depositional settings from the NE side of the triple junction (subducting Pacific plate) to the SW side (Shikoku Basin, subducting Philippine Sea plate). Regardless of the exact paleogeography, we predict that lower initial percentages of detrital smectite and gradual diagenetic loss

  1. Formation of replicating saponite from a gel in the presence of oxalate: implications for the formation of clay minerals in carbonaceous chondrites and the origin of life

    USGS Publications Warehouse

    Schumann, Dirk; Hartman, Hyman; Eberl, Dennis D.; Sears, S. Kelly; Hesse, Reinhard; Vali, Hojatollah

    2012-01-01

    The potential role of clay minerals in the abiotic origin of life has been the subject of ongoing debate for the past several decades. At issue are the clay minerals found in a class of meteorites known as carbonaceous chondrites. These clay minerals are the product of aqueous alteration of anhydrous mineral phases, such as olivine and orthopyroxene, that are often present in the chondrules. Moreover, there is a strong correlation in the occurrence of clay minerals and the presence of polar organic molecules. It has been shown in laboratory experiments at low temperature and ambient pressure that polar organic molecules, such as the oxalate found in meteorites, can catalyze the crystallization of clay minerals. In this study, we show that oxalate is a robust catalyst in the crystallization of saponite, an Al- and Mg-rich, trioctahedral 2:1 layer silicate, from a silicate gel at 60°C and ambient pressure. High-resolution transmission electron microscopy analysis of the saponite treated with octadecylammonium (n(C)=18) cations revealed the presence of 2:1 layer structures that have variable interlayer charge. The crystallization of these differently charged 2:1 layer silicates most likely occurred independently. The fact that 2:1 layer silicates with variable charge formed in the same gel has implications for our understanding of the origin of life, as these 2:1 clay minerals most likely replicate by a mechanism of template-catalyzed polymerization and transmit the charge distribution from layer to layer. If polar organic molecules like oxalate can catalyze the formation of clay-mineral crystals, which in turn promote clay microenvironments and provide abundant adsorption sites for other organic molecules present in solution, the interaction among these adsorbed molecules could lead to the polymerization of more complex organic molecules like RNA from nucleotides on early Earth.

  2. Formation of replicating saponite from a gel in the presence of oxalate: implications for the formation of clay minerals in carbonaceous chondrites and the origin of life.

    PubMed

    Schumann, Dirk; Hartman, Hyman; Eberl, Dennis D; Sears, S Kelly; Hesse, Reinhard; Vali, Hojatollah

    2012-06-01

    The potential role of clay minerals in the abiotic origin of life has been the subject of ongoing debate for the past several decades. At issue are the clay minerals found in a class of meteorites known as carbonaceous chondrites. These clay minerals are the product of aqueous alteration of anhydrous mineral phases, such as olivine and orthopyroxene, that are often present in the chondrules. Moreover, there is a strong correlation in the occurrence of clay minerals and the presence of polar organic molecules. It has been shown in laboratory experiments at low temperature and ambient pressure that polar organic molecules, such as the oxalate found in meteorites, can catalyze the crystallization of clay minerals. In this study, we show that oxalate is a robust catalyst in the crystallization of saponite, an Al- and Mg-rich, trioctahedral 2:1 layer silicate, from a silicate gel at 60°C and ambient pressure. High-resolution transmission electron microscopy analysis of the saponite treated with octadecylammonium (n(C)=18) cations revealed the presence of 2:1 layer structures that have variable interlayer charge. The crystallization of these differently charged 2:1 layer silicates most likely occurred independently. The fact that 2:1 layer silicates with variable charge formed in the same gel has implications for our understanding of the origin of life, as these 2:1 clay minerals most likely replicate by a mechanism of template-catalyzed polymerization and transmit the charge distribution from layer to layer. If polar organic molecules like oxalate can catalyze the formation of clay-mineral crystals, which in turn promote clay microenvironments and provide abundant adsorption sites for other organic molecules present in solution, the interaction among these adsorbed molecules could lead to the polymerization of more complex organic molecules like RNA from nucleotides on early Earth.

  3. Formation of replicating saponite from a gel in the presence of oxalate: implications for the formation of clay minerals in carbonaceous chondrites and the origin of life.

    PubMed

    Schumann, Dirk; Hartman, Hyman; Eberl, Dennis D; Sears, S Kelly; Hesse, Reinhard; Vali, Hojatollah

    2012-06-01

    The potential role of clay minerals in the abiotic origin of life has been the subject of ongoing debate for the past several decades. At issue are the clay minerals found in a class of meteorites known as carbonaceous chondrites. These clay minerals are the product of aqueous alteration of anhydrous mineral phases, such as olivine and orthopyroxene, that are often present in the chondrules. Moreover, there is a strong correlation in the occurrence of clay minerals and the presence of polar organic molecules. It has been shown in laboratory experiments at low temperature and ambient pressure that polar organic molecules, such as the oxalate found in meteorites, can catalyze the crystallization of clay minerals. In this study, we show that oxalate is a robust catalyst in the crystallization of saponite, an Al- and Mg-rich, trioctahedral 2:1 layer silicate, from a silicate gel at 60°C and ambient pressure. High-resolution transmission electron microscopy analysis of the saponite treated with octadecylammonium (n(C)=18) cations revealed the presence of 2:1 layer structures that have variable interlayer charge. The crystallization of these differently charged 2:1 layer silicates most likely occurred independently. The fact that 2:1 layer silicates with variable charge formed in the same gel has implications for our understanding of the origin of life, as these 2:1 clay minerals most likely replicate by a mechanism of template-catalyzed polymerization and transmit the charge distribution from layer to layer. If polar organic molecules like oxalate can catalyze the formation of clay-mineral crystals, which in turn promote clay microenvironments and provide abundant adsorption sites for other organic molecules present in solution, the interaction among these adsorbed molecules could lead to the polymerization of more complex organic molecules like RNA from nucleotides on early Earth. PMID:22794298

  4. Non-selective oxidation of humic acid in heterogeneous aqueous systems: a comparative investigation on the effect of clay minerals.

    PubMed

    Kavurmaci, Sibel Sen; Bekbolet, Miray

    2014-01-01

    Application of photocatalysis for degradation of natural organic matter (NOM) has received wide interest during the last decades. Besides NOM, model compounds more specifically humic acids (HAs) were also studied. As a continuation of the previous research, TiO2 photocatalytic degradation of HA was investigated in the presence of clay minerals, i.e., montmorillonite (Mt) and kaolinite (Kt). Degradation of HA was expressed by the pseudo-first-order kinetic modelling of dissolved organic carbon (DOC) and UV-VIS parameters (Colour436 and UV254). A slight rate enhancement was attained for Colour436 and UV254 in the presence of either Mt or Kt. The presence of clay particles did not significantly change the DOC degradation rate of HA. The effect of ionic strength (Ca2+ loading from 5 x 10(-4) M to 5 x 1(-3) M) was also assessed for the photocatalytic degradation of sole HA and HA in the presence of either Mt or Kt. Following photocatalytic treatment, molecular size distribution profiles of HA were presented. Besides the effective removal of higher molecular size fractions (100 and 30 kDa fractions), transformation to lower molecular size fractions (<3 kDa) was more pronounced for sole HA rather than HA in the presence of clay minerals. Scanning electron microscopic images with the energy dispersive X-ray analysis confirmed the diversities in surface morphologies of the binary and ternary systems composed of HA, TiO2 and Mt or Kt both prior to and following photocatalysis. This study demonstrated that photocatalysis could be applicable for DOC degradation in the presence of clay minerals in natural waters. PMID:25145193

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

    SciTech Connect

    Sugama, T.; Ecker, L.; Gill, S.; Butcher, T.; Bour, D.

    2010-11-01

    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.

  6. Non-selective oxidation of humic acid in heterogeneous aqueous systems: a comparative investigation on the effect of clay minerals.

    PubMed

    Kavurmaci, Sibel Sen; Bekbolet, Miray

    2014-01-01

    Application of photocatalysis for degradation of natural organic matter (NOM) has received wide interest during the last decades. Besides NOM, model compounds more specifically humic acids (HAs) were also studied. As a continuation of the previous research, TiO2 photocatalytic degradation of HA was investigated in the presence of clay minerals, i.e., montmorillonite (Mt) and kaolinite (Kt). Degradation of HA was expressed by the pseudo-first-order kinetic modelling of dissolved organic carbon (DOC) and UV-VIS parameters (Colour436 and UV254). A slight rate enhancement was attained for Colour436 and UV254 in the presence of either Mt or Kt. The presence of clay particles did not significantly change the DOC degradation rate of HA. The effect of ionic strength (Ca2+ loading from 5 x 10(-4) M to 5 x 1(-3) M) was also assessed for the photocatalytic degradation of sole HA and HA in the presence of either Mt or Kt. Following photocatalytic treatment, molecular size distribution profiles of HA were presented. Besides the effective removal of higher molecular size fractions (100 and 30 kDa fractions), transformation to lower molecular size fractions (<3 kDa) was more pronounced for sole HA rather than HA in the presence of clay minerals. Scanning electron microscopic images with the energy dispersive X-ray analysis confirmed the diversities in surface morphologies of the binary and ternary systems composed of HA, TiO2 and Mt or Kt both prior to and following photocatalysis. This study demonstrated that photocatalysis could be applicable for DOC degradation in the presence of clay minerals in natural waters.

  7. Swelling properties of montmorillonite and beidellite clay minerals from molecular simulation: Comparison of temperature interlayer cation, and charge location effects

    DOE PAGESBeta

    Teich-McGoldrick, Stephanie L.; Greathouse, Jeffery A.; Jove-Colon, Carlos F.; Cygan, Randall Timothy

    2015-08-27

    In this study, the swelling properties of smectite clay minerals are relevant to many engineering applications including environmental remediation, repository design for nuclear waste disposal, borehole stability in drilling operations, and additives for numerous industrial processes and commercial products. We used molecular dynamics and grand canonical Monte Carlo simulations to study the effects of layer charge location, interlayer cation, and temperature on intracrystalline swelling of montmorillonite and beidellite clay minerals. For a beidellite model with layer charge exclusively in the tetrahedral sheet, strong ion–surface interactions shift the onset of the two-layer hydrate to higher water contents. In contrast, for amore » montmorillonite model with layer charge exclusively in the octahedral sheet, weaker ion–surface interactions result in the formation of fully hydrated ions (two-layer hydrate) at much lower water contents. Clay hydration enthalpies and interlayer atomic density profiles are consistent with the swelling results. Water adsorption isotherms from grand canonical Monte Carlo simulations are used to relate interlayer hydration states to relative humidity, in good agreement with experimental findings.« less

  8. Swelling properties of montmorillonite and beidellite clay minerals from molecular simulation: Comparison of temperature interlayer cation, and charge location effects

    SciTech Connect

    Teich-McGoldrick, Stephanie L.; Greathouse, Jeffery A.; Jove-Colon, Carlos F.; Cygan, Randall Timothy

    2015-08-27

    In this study, the swelling properties of smectite clay minerals are relevant to many engineering applications including environmental remediation, repository design for nuclear waste disposal, borehole stability in drilling operations, and additives for numerous industrial processes and commercial products. We used molecular dynamics and grand canonical Monte Carlo simulations to study the effects of layer charge location, interlayer cation, and temperature on intracrystalline swelling of montmorillonite and beidellite clay minerals. For a beidellite model with layer charge exclusively in the tetrahedral sheet, strong ion–surface interactions shift the onset of the two-layer hydrate to higher water contents. In contrast, for a montmorillonite model with layer charge exclusively in the octahedral sheet, weaker ion–surface interactions result in the formation of fully hydrated ions (two-layer hydrate) at much lower water contents. Clay hydration enthalpies and interlayer atomic density profiles are consistent with the swelling results. Water adsorption isotherms from grand canonical Monte Carlo simulations are used to relate interlayer hydration states to relative humidity, in good agreement with experimental findings.

  9. Climatic and stratigraphic implications of clay mineral changes in Paleocene/Eocene boundary strata -- Eastern United States

    SciTech Connect

    Gibson, T.G.; Bybell, L.M.; Owens, J.P.; Mason, D.B.; McCartan, L.; Snow, J.N. )

    1994-03-01

    A major change in the clay mineral suite from predominantly illite/smectite and illite to predominantly kaolinite is present in uppermost Paleocene neritic deposits in the Salisbury embayment of the northeastern US. The clay mineral change occurred during a time of relatively high sea level and is associated with biotic, climatic, and oceanographic changes. This kaolinite increase in middle-latitude areas of the western North Atlantic Ocean, and similar increases in coeval deep-marine sediments off Antarctica and in the eastern North Atlantic Ocean, suggests that intensified weathering due to increased temperature and precipitation was widespread in the latest Paleocene. In the Salisbury embayment, kaolinite proportions rapidly increase from less than 5% in upper Paleocene strata to maximum values of 50 to 60% near the top of the Paleocene (top of calcareous nannofossil Zone NP 9). High kaolinite proportions continue into the lowest Eocene strata (lowermost zone NP 10), but the kaolinite proportion rapidly decreases to 5% or less within the lower part of Zone NP 10. The pattern of kaolinite increasing to maximum values in the latest Paleocene, followed by decreasing values in the earliest Eocene can be used for correlation within the upper Paleocene and lower Eocene units in the Salisbury embayment. On this basis, it is suggested that during the early Eocene, large parts of the uppermost Paleocene and lowermost Eocene clay were eroded from landward parts of the basin.

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

    PubMed

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

    2012-10-01

    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.

  11. A recommended procedure for the preparation of oriented clay-mineral specimens for X-ray diffraction analysis; modifications to Drever's filter-membrane peel technique

    USGS Publications Warehouse

    Pollastro, R.M.

    1982-01-01

    Extremely well-oriented clay mineral mounts for X-ray diffraction analysis can be prepared quickly and without introducing segregation using the filter-membrane peel technique. Mounting problems encountered with smectite-rich samples can be resolved by using minimal sample and partial air-drying of the clay film before transfer to a glass slide. Samples containing small quantities of clay can produce useful oriented specimens if Teflon masks having more restrictive areas are inserted above the membrane filter during clay deposition. War]page and thermal shock of glass slides can be controlled by using a flat, porous, ceramic plate as a holding surface during heat treatments.

  12. Alteration of glass as a possible source of clay minerals on Mars

    NASA Technical Reports Server (NTRS)

    Gooding, J. L.; Keil, K.

    1978-01-01

    Thermodynamic calculations show that, under present Martian surface conditions, favorable gas-solid weathering products of feldspar glasses should include beidellites (clays of the montmorillonite series) + carbonates + quartz. The gas-solid weathering of mafic silicate glass ( of volcanic or impact origin) may similarly favor the production of metastable Fe-rich montmorillonite clays. Simple mass-balance calculations suggest that gas-solid weathering of Martian proto-regolith containing 10% glass could conceivably produce a global blanket of clays at a rate of at least 0.4 cm/b.y. The production rate should be expected to increase significantly with the glass content and rate of reworking of the proto-regolith and with the availability of water. Complete extraction of altered glass from a lunar-like proto-regolith might yield a global Martian clay blanket about 10-100 cm in thickness.

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

    SciTech Connect

    Baxter, P.; Ferrell, R.E.

    1987-05-01

    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.

  14. Recognition of coseismic-related microstructures and behaviour of clay minerals within the core of active fault

    NASA Astrophysics Data System (ADS)

    Buatier, M.; Chauvet, A.; Ritz, J.; Jolivet, M.; Bayarjargal, B.; Vitalie, M.; Vassalo, R.

    2008-12-01

    Seismogenic faults are commonly characterized by a zonation with foliated gouge and breccias surrounded by damage zone. This zonation results from co-seismic or inter-seismic deformation and fluid-rock interactions. Based on field, textural, microtextural and clay mineralogical analysis, the core zone of an active fault located in the Bogd Mongolian massif has been studied. This fault is supposed to be an ancient major ductile shear zone re-activated during the Quaternary. Field studies reveal the complexity of the fault cores with the association between fragmented/ brecciated domains and at least two generations of gouge. The first gouge presents a foliated structure. The second one is characterized by an homogeneous black, thin, fine-grained, gouge. According to field constraints, the thin gouge level can correspond to the last seismic event. Catholuminescence and SEM investigations allow to characterize the texture of each gouge and surrounding rocks. Additional measurement of grain size distribution, grain circularity, grain shape and grain fabrics allow the clear distinction between the two different gouge textures: foliated and isotropic. In the foliated gouge, mineralogical study (SEM-BSE and DRX) displays evidence of fluid-rock interactions with alteration of micas to illite/smectite and formation of kaolinite. The presence of authigenic gypsum crystals and Fe-oxyhydroxyde suggests interseismic fluid circulation in this permeable structure. The last generation of gouge with isotropic texture is clay rich and is characterized by the presence of smectite (hydrated clay mineral). The data suggest polyphase deformation with ductile structures associated with brittle deformation implying communition process. The debate concerns the mode of formation of the gouge and the origin of clay minerals.

  15. Clay minerals and metal oxides strongly influence the structure of alkane-degrading microbial communities during soil maturation

    PubMed Central

    Steinbach, Annelie; Schulz, Stefanie; Giebler, Julia; Schulz, Stephan; Pronk, Geertje J; Kögel-Knabner, Ingrid; Harms, Hauke; Wick, Lukas Y; Schloter, Michael

    2015-01-01

    Clay minerals, charcoal and metal oxides are essential parts of the soil matrix and strongly influence the formation of biogeochemical interfaces in soil. We investigated the role of these parental materials for the development of functional microbial guilds using the example of alkane-degrading bacteria harbouring the alkane monooxygenase gene (alkB) in artificial mixtures composed of different minerals and charcoal, sterile manure and a microbial inoculum extracted from an agricultural soil. We followed changes in abundance and community structure of alkane-degrading microbial communities after 3 and 12 months of soil maturation and in response to a subsequent 2-week plant litter addition. During maturation we observed an overall increasing divergence in community composition. The impact of metal oxides on alkane-degrading community structure increased during soil maturation, whereas the charcoal impact decreased from 3 to 12 months. Among the clay minerals illite influenced the community structure of alkB-harbouring bacteria significantly, but not montmorillonite. The litter application induced strong community shifts in soils, maturated for 12 months, towards functional guilds typical for younger maturation stages pointing to a resilience of the alkane-degradation function potentially fostered by an extant ‘seed bank'. PMID:25535940

  16. [X-ray powder diffraction of clay minerals of SZK01 core of Zabuye Lake, Tibetan Plateau].

    PubMed

    Zhang, Xue-Fei; Zheng, Mian-Ping

    2014-11-01

    The present article chooses the core from the borehole SZK01 in Zabuye Lake as the main research object. According to the results of X-ray powder diffraction of clay minerals, the major components are illite, illite and smectite mixed layer mineral (I/S), kaolinite and chlorite. According to the different species and contents of clay, integration of the characteristics of mineral and the results of Δ18O, we reestablished the evolution process of paleoclimate in Zabuye Lake. In compaison with SZK02 core in Zabuye, Greenland GISP2 and GRIP and Guliya ice core, it contains 5 stages since 115 ka in Zabuye: the last interglacial (15-75.5 ka), the earlier last glacial (75.5-60 ka), the interstage of the last glacial (60-30.1 ka), the last glacial maximum (30.1-16.7 ka) and deglacial-holocene (since 16.7 ka). We also recognized 6 Heinrich events (H1-H6) and warm event in 71 ka. In particular, the content of kaolinite is low, with the negative-skewed value of Δ18O in 52-53 ka, while the value of Δ18O in SZK02 and Guliya ice core is negative-skewed too, indicating the cold event in Tibet plateau, named H5-1. All the above demonstrated that the climate in Tibet plateau is global since the earlier last glacial, and it also has regional characteristics. PMID:25752070

  17. Calcium-ammonium exchange experiments on clay minerals using a (45)Ca tracer technique in marine pore water.

    PubMed

    Ockert, Charlotte; Wehrmann, Laura M; Kaufhold, Stephan; Ferdelman, Tim G; Teichert, Barbara M A; Gussone, Nikolaus

    2014-01-01

    Understanding cation exchange processes is important for evaluating early diagenetic and synsedimentary processes taking place in marine sediments. To quantify calcium (Ca) exchange and Ca-ammonium exchange in a seawater environment, we performed experiments with a radioactive (45)Ca tracer on clay mineral standards (Fithian illite, montmorillonite and kaolinite) and marine sediments from the North Atlantic Integrated Ocean Drilling Program Site U1306A in artificial seawater (ASW). The results show that equilibrium during the initial attachment of Ca as well as the exchange of Ca by [Formula: see text] is attained in less than 2 min. On average 8-20% of the exchangeable sites of the clay minerals were occupied by Ca in a seawater medium. The conditional selectivity coefficient, describing the [Formula: see text] exchange in ASW is mineral specific and it was determined to be 0.07 for montmorillonite, 0.05 for a natural marine sediment and 0.013 for Fithian illite. PMID:24437731

  18. Clay minerals and metal oxides strongly influence the structure of alkane-degrading microbial communities during soil maturation.

    PubMed

    Steinbach, Annelie; Schulz, Stefanie; Giebler, Julia; Schulz, Stephan; Pronk, Geertje J; Kögel-Knabner, Ingrid; Harms, Hauke; Wick, Lukas Y; Schloter, Michael

    2015-07-01

    Clay minerals, charcoal and metal oxides are essential parts of the soil matrix and strongly influence the formation of biogeochemical interfaces in soil. We investigated the role of these parental materials for the development of functional microbial guilds using the example of alkane-degrading bacteria harbouring the alkane monooxygenase gene (alkB) in artificial mixtures composed of different minerals and charcoal, sterile manure and a microbial inoculum extracted from an agricultural soil. We followed changes in abundance and community structure of alkane-degrading microbial communities after 3 and 12 months of soil maturation and in response to a subsequent 2-week plant litter addition. During maturation we observed an overall increasing divergence in community composition. The impact of metal oxides on alkane-degrading community structure increased during soil maturation, whereas the charcoal impact decreased from 3 to 12 months. Among the clay minerals illite influenced the community structure of alkB-harbouring bacteria significantly, but not montmorillonite. The litter application induced strong community shifts in soils, maturated for 12 months, towards functional guilds typical for younger maturation stages pointing to a resilience of the alkane-degradation function potentially fostered by an extant 'seed bank'.

  19. [X-ray powder diffraction of clay minerals of SZK01 core of Zabuye Lake, Tibetan Plateau].

    PubMed

    Zhang, Xue-Fei; Zheng, Mian-Ping

    2014-11-01

    The present article chooses the core from the borehole SZK01 in Zabuye Lake as the main research object. According to the results of X-ray powder diffraction of clay minerals, the major components are illite, illite and smectite mixed layer mineral (I/S), kaolinite and chlorite. According to the different species and contents of clay, integration of the characteristics of mineral and the results of Δ18O, we reestablished the evolution process of paleoclimate in Zabuye Lake. In compaison with SZK02 core in Zabuye, Greenland GISP2 and GRIP and Guliya ice core, it contains 5 stages since 115 ka in Zabuye: the last interglacial (15-75.5 ka), the earlier last glacial (75.5-60 ka), the interstage of the last glacial (60-30.1 ka), the last glacial maximum (30.1-16.7 ka) and deglacial-holocene (since 16.7 ka). We also recognized 6 Heinrich events (H1-H6) and warm event in 71 ka. In particular, the content of kaolinite is low, with the negative-skewed value of Δ18O in 52-53 ka, while the value of Δ18O in SZK02 and Guliya ice core is negative-skewed too, indicating the cold event in Tibet plateau, named H5-1. All the above demonstrated that the climate in Tibet plateau is global since the earlier last glacial, and it also has regional characteristics.

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

    PubMed

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

    2010-03-01

    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.

  1. Sorption of organic cations to phyllosilicate clay minerals: CEC-normalization, salt dependency, and the role of electrostatic and hydrophobic effects.

    PubMed

    Droge, Steven T J; Goss, Kai-Uwe

    2013-12-17

    Sorption to the phyllosilicate clay minerals Illite, kaolinite, and bentonite has been studied for a wide variety of organic cations using a flow-through method with fully aqueous medium as the eluent. Linear isotherms were observed at concentrations below 10% of the cation-exchange capacity (CEC) for Illite and kaolinite and below 1 mmol/kg (<1% CEC) for bentonite. Sorption to clays was strongly influenced by the electrolyte composition of the eluent but with a consistent trend for a diverse set of compounds on all clays, thus allowing for empirical correction factors. When sorption affinities for a given compound to a given clay are normalized to the CEC of the clay, the differences in sorption affinities between clays are reduced to less than 0.5 log units for most compounds. Although CEC-normalized sorption of quaternary ammonium compounds to clay was up to 10-fold higher than CEC-normalized sorption to soil organic matter, CEC-normalized sorption for most compounds was comparable between clays and soil organic matter. The clay fraction is thus a potentially relevant sorption phase for organic cations in many soils. The sorption data for organic cations to clay showed several regular trends with molecular structure but also showed quite a few systematic effects that we cannot explain. A model on the basis of the molecular size and charge density at the ionized nitrogen is used here as a tool to obtain benchmark values that elucidate the effect of specific polar moieties on the sorption affinity.

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

    PubMed Central

    Lavie, S; Stotzky, G

    1986-01-01

    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. Images PMID:3954340

  3. Crystal growth of a layered silicate clay mineral as revealed by atomic force microscopy

    SciTech Connect

    Carrado, K.A.; Song, Kang; Zajac, G.W.

    1997-12-31

    Non-contact atomic force microscopy, commonly referred to as {open_quotes}tapping mode{close_quotes} AFM, has been used to scan primarily the morphological features of growing hectorite clay crystallites synthesized in the presence of organo-ammonium cations. The use of such cations allows larger crystals to form in this system, making study by AFM feasible. This is the first time that actual temporal {open_quotes}snapshots{close_quotes} of a clay`s nucleation and crystallization processes have been presented. The observed view does not support the perhaps predicted scene of small crystallites slowly ripening into larger and larger plates. Instead, larger and larger aggregates appear to coalesce from a larger number of small crystallites that are closely associated in globular networks similar in appearance to {open_quotes}strings of pearls{close_quotes} at the initial stages of crystallization.

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

    PubMed

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

    2010-10-01

    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

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

    PubMed

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

    2010-10-01

    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.

  6. 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

    Folk, R.L.; Lynch, F.L.

    1997-05-01

    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.

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

    SciTech Connect

    Carrado, K.A.; Thiyagarajan, P.; Winans, R.E.; Song, Kang

    1997-09-01

    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.

  8. Influence of Biogenic Fe(II) on the Extent of Microbial Reduction of Fe(III) in Clay Minerals Nontronite, Illite, and Chlorite

    SciTech Connect

    Jaisi, Deb P.; Dong, Hailiang; Liu, Chongxuan

    2007-03-01

    Microbial reduction of Fe(III) in clay minerals is an important process that affects properties of clay-rich materials and iron biogeochemical cycling in natural environments. Microbial reduction often ceases before all Fe(III) in clay minerals is exhausted. The factors causing the cessation are, however, not well understood. The objective of this study was to assess the role of biogenic Fe(II) in microbial reduction of Fe(III) in various clay minerals. Bioreduction experiments were performed in a batch system, where lactate was used as the sole electron donor, Fe(III) in clay minerals as the sole electron acceptor, and Shewanella putrefaciens CN32 as the mediator with and without an electron shuttle AQDS. Our results showed that bioreduction activity ceased within two weeks with variable extents of bioreduction of structural Fe(III) in clay minerals. When fresh CN32 cells were added to the old cultures (6 months), bioreduction resumed and extents increased. This result indicated that the previous cessation of Fe(III) bioreduction was not necessarily due to the exhaustion of bioavailable Fe(III) in the mineral structure, and suggested that the changes of cell physiology or solution chemistry, such as Fe(II) production during microbial reduction, affected the extent of bioreduction. To investigate the effect of Fe(II) production on Fe(III) bioreduction, a typical bioreduction process (consisting of lactate, clay, cells and AQDS) was separated into two steps: 1. AQDS was reduced by cells in the absence of clay but in the presence of variable Fe(II) concentrations; 2. reduction of Fe(III) in clays by biogenic AH2DS in the absence of cells. The inhibitory effect of Fe(II) on CN32 activity was confirmed. TEM analysis revealed a thick electron dense halo surrounding the cell surfaces that most likely resulted from Fe(II) sorption/precipitation. Such electron dense materials might have blocked or interfered electron transfers on cell surfaces. The inhibitory effect of Fe

  9. 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...

  10. Structural Investigation of Alkali Activated Clay Minerals for Application in Water Treatment Systems

    NASA Astrophysics Data System (ADS)

    Bumanis, G.; Bajare, D.; Dembovska, L.

    2015-11-01

    Alkali activation technology can be applied for a wide range of alumo-silicates to produce innovative materials with various areas of application. Most researches focuse on the application of alumo-silicate materials in building industry as cement binder replacement to produce mortar and concrete [1]. However, alkali activation technology offers high potential also in biotechnologies [2]. In the processes where certain pH level, especially alkaline environment, must be ensured, alkali activated materials can be applied. One of such fields is water treatment systems where high level pH (up to pH 10.5) ensures efficient removal of water pollutants such as manganese [3]. Previous investigations had shown that alkali activation technology can be applied to calcined clay powder and aluminium scrap recycling waste as a foam forming agent to create porous alkali activated materials. This investigation focuses on the structural investigation of calcined kaolin and illite clay alkali activation processes. Chemical and mineralogical composition of both clays were determined and structural investigation of alkali activated materials was made by using XRD, DTA, FTIR analysis; the microstructure of hardened specimens was observed by SEM. Physical properties of the obtained material were determined. Investigation indicates the essential role of chemical composition of the clay used in the alkali activation process, and potential use of the obtained material in water treatment systems.

  11. Suitability of the methylene blue test for determination of cation exchange capacity of clay minerals related to ammonium acetate method

    NASA Astrophysics Data System (ADS)

    Milošević, Maja; Logar, Mihovil; Dojčinović, Biljana; Erić, Suzana

    2015-04-01

    Cation exchange capacity (CEC) represents one of the most important parameters of clay minerals which reflects their ability to exchange cations with liquid phases in near contact. Measurement of CEC is used for characterizing sample plasticity, adsorbing and swelling properties which later define their usage in industrial purposes. Several methods have been developed over the years for determination of layer charge, charge density, charge distribution, etc. and have been published in numerous papers (Czimerova et al., 2006; Yukselen and Kaya, 2008). The main goal of present study is comparison of suitability of more recent method - methylene blue test in regard to older method - ammonium acetate for determination of CEC. For this study, we selected one montmorillonite clay (Bogovina, Serbia) and two mainly kaolinite clays (Miličinica, Serbia). Chemicals used for CEC determinations were solution of methylene blue (MB)(14*10-6M/ml) and ammonium acetate (AA) solution (1M). The obtained results are showing generally lower values in case of MB method. The main difference is due to molecular aggregation of MB on the clay surface. AA method is highly sensitive to the presence of CaO. Release of Ca ion from the sample into the solution can limit the saturation of exchange sites by the ammonium ion. This is clearly visible in case of montmorillonite clay. Fe2+ and Mg ions are difficult to move by the ammonium ion because of their ion radius, but in case of MB molecule there is no such restriction in removing them from the exchange sites. MB solution, even in a low concentration (2*10-6M/ml), is showing preferable results in moving the ions from their positions which is already visible after adding a small quantity of solution (25cm3). Both MB-titration and MB-spot test yield similar results and are much simpler methods than AA and they also give other information such as specific surface area (external and internal) whereas AA method only provides information about

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

    NASA Astrophysics Data System (ADS)

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

    2010-01-01

    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.

  13. 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)

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

    2012-09-01

    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.

  14. Adsorption mechanisms of emerging micro-pollutants with a clay mineral: Case of tramadol and doxepine pharmaceutical products.

    PubMed

    Thiebault, Thomas; Guégan, Régis; Boussafir, Mohammed

    2015-09-01

    A sodium exchanged smectite clay mineral (Mt) was used as geo-sorbent for the adsorption of tramadol and doxepin: two pharmaceutical products (PPs) defined as emerging pollutants due to their presence at significant concentration in numerous water compartments. The adsorption isotherms for both the temperatures of 20 and 40°C and the derived data determined through the fitting procedure by using Langmuir, Freundlich and Dubinin-Radushkevich equation models explicitly pointed out that the sorption of both tramadol and doxepin is mainly driven by electrostatic interaction. The studied PPs are intercalated in a monolayer arrangement within the interlayer space through a cation exchange in stoichiometric proportion with the Na(+) cations leading to adsorbed PPs amounts that match the cation exchange capacity (CEC) of Mt. Due to their hydrophobic character, additional doxepin molecules could be adsorbed by weak molecular interaction driving to an increase of the adsorbed amount beyond the CEC at low temperature (20°C). The confinement of PPs within the interlayer space of Mt confirms the use of clay minerals as potential material for the wastewater treatment as well as it drives to an amorphous or glassy state, which can find echo in biopharmaceutical applications for a controlled release of PPs.

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

    PubMed

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

    2013-02-19

    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.

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

    PubMed Central

    Rosenzweig, William D.; Stotzky, G.

    1979-01-01

    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. PMID:16345477

  17. Structure of a seafloor hydrothermal system in volcanic sediment: distribution of hydrothermal clay minerals, at the Iheya North Knoll, Okinawa Trough

    NASA Astrophysics Data System (ADS)

    Miyoshi, Y.; Ishibashi, J.; Faure, K.; Uehara, S.

    2012-12-01

    Detailed investigation of clay minerals in hydrothermal fields provides fundamental information for understanding the physical and geochemical conditions within a hydrothermal system. Moreover, stable isotope geochemistry of clay minerals provides constraints on formation temperature. We investigated the distribution of clay minerals by XRD and TEM-EDS in a seafloor hydrothermal field at Iheya North Knoll in the Okinawa Trough, using cored sediment obtained from the Integrated Ocean Drilling Program (IODP) Expedition 331. The chemical composition and isotope values of the representative clay minerals were analyzed to obtain information on the hydrothermal system beneath the seafloor. Vertically, two different clay mineral facies are present. The boundary between the facies was identified at 6 mbsf (meters below the seafloor) at Site C0013 (100 m east of hydrothermal mound) and at 23 mbsf at Site C0014 (450 m east of the mound). In the lower facies (6 - 28 mbsf and 45 mbsf at Site C0013, 23 - 114 mbsf at Site C0014), Mg-chlorite and/or Mg-chlorite-smectite mixed layer minerals are dominant. They are associated with sericite in deeper parts (45 mbsf at Site C0013 and 38 - 114 mbsf at Site C0014). The δ18O values of the clays range from +1.5 to +4.7 ‰ (VSMOW) and the formation temperatures of the Mg-chlorite are estimated to be 230 - 300 °C, assuming a value from 0 to +1.5 ‰ for δ18Owater. The original sediment in the Iheya North Knoll is considered to have been volcanic of felsic chemical composition, so alteration to Mg-rich chlorite would require supply of substantial amount of Mg. Abundant formation of Mg-chlorite is attributed to mixing of hydrothermal fluid and seawater. In the upper facies at both sites, Al-rich clay minerals (kaolinite and montmorillonite) dominate. The δ18O values of clays range between +9.6 and +13.3 ‰ and formation temperatures are estimated to range between 120 - 160 °C. As kaolinite formation is favorable under acidic

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

    NASA Astrophysics Data System (ADS)

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

    2009-02-01

    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 ( ΔGmθr) values of the adsorption indicated that the adsorption of the Bt toxin by the minerals was spontaneous, and the changes of the standard enthalpy ( ΔHmθr) showed that the adsorption of the Bt toxin by montmorillonite was endothermic while the adsorption by the other three minerals was exothermic.

  19. The 1.7- to 4.2-micron spectrum of asteroid 1 Ceres - Evidence for structural water in clay minerals

    NASA Technical Reports Server (NTRS)

    Lebofsky, L. A.; Feierberg, M. A.; Larson, H. P.; Johnson, J. R.; Tokunaga, A. T.

    1981-01-01

    A high-resolution Fourier spectrum (1.7-3.5 microns) and medium-resolution spectrophotometry (2.7-4.2 microns) were obtained for Asteroid 1 Ceres. The presence of the 3-micron absorption feature due to water of hydration was confirmed. The 3-micron feature is compared with the 3-micron bands due to water of hydration in clays and salts. It is concluded that the spectrum of Ceres shows a strong absorption at 2.7-2.8 microns due to structural OH groups in clay minerals. The dominant minerals on the surface of Ceres are therefore hydrated clay minerals structurally similar to terrestrial montmorillonites. There is also a narrow absorption feature at 3.1 microns which is attributable to a very small amount of water ice on Ceres. This is the first evidence for ice on the surface of an asteroid.

  20. Effect of pH on the heavy metal-clay mineral interaction

    SciTech Connect

    Altyn, O.; Oezbelge, H.O.; Dogu, T.; Oezbelge, T.A.

    1997-12-31

    Adsorption and ion exchange of Pb and Cd on the surface of kaolinite and montmorillonite were studied with a strong emphasis on the pH values of solutions containing heavy metal ions. The pH range studied was 2.5 - 9. For kaolinite at a clay/solution ratio of 1/10 (w/w), Pb removal changes from 20 to 30% for an initial Pb concentration of 1640 ppm, and Cd removal changes from 10 to 20% for an initial Cd concentration of 1809 ppm. Due to its high exchange capacity, montmorillonite can remove more heavy metal than kaolinite. Removal rates for montmorillonite can reach up to 90% for both Pb and Cd. In the pH range of 3-6, there is a plateau for the removal rates. At pH values higher than 6, removal seems to increase artificially due to the precipitation of heavy metals. Under similar conditions for both clays, the rate of removal of Pb is always higher than that of Cd. As the pH value decreases for montmorillonite, there is a strong tendency for decreased surface area and swelling, as indicated by BET surface area measurements, adsorbed layer thickness and pore size distribution data. In the range of pH values studied, X-ray diffraction analysis showed the appearance of a characteristic (001) peak for montmorillonite, indicating that the crystalline structure of the clay was intact during the experiments.

  1. The protective effect of clay minerals against damage to adsorbed DNA induced by cadmium and mercury.

    PubMed

    Hou, Yakun; Wu, Pingxiao; Zhu, Nengwu

    2014-01-01

    The adsorption of Salmon Sperm DNA on three kinds of raw clay (rectorite, montmorillonite and sericite) was investigated as a function of pH, ionic strength and the concentrations of DNA and phosphate ions in solution. The DNA adsorption was reduced in the following order: rectorite>montmorillonite>sericite. Based on these findings, there is a strong evidence that the mechanisms for DNA adsorption on clay involve electrostatic forces, cation bridging and ligand exchange. Cyclic voltammetry (CV) and UV-vis absorption and fluorescence spectroscopy were used to compare the properties of unbound DNA and the absorbed DNA on rectorite, both in the absence and presence of Cd(2+) and Hg(2+) inaqueous solutions. The interaction of heavy metals with the unbound DNA was evidenced by the disappearance of reduction peaks in CV, a small bathochromic shift in UV-vis spectroscopy and an incomplete quenching in the emission spectra. Such changes were not observed in the DNA-rectorite hybrids, which is evidence that adsorption on the clay can reduce the extent of the DNA damage caused by heavy metals. Therefore, in these experience the rectorite played an important role in protecting DNA against Cd(2+) and Hg(2+) induced damage.

  2. Estimating mineral abundances of clay and gypsum mixtures using radiative transfer models applied to visible-near infrared reflectance spectra

    NASA Astrophysics Data System (ADS)

    Robertson, K. M.; Milliken, R. E.; Li, S.

    2016-10-01

    Quantitative mineral abundances of lab derived clay-gypsum mixtures were estimated using a revised Hapke VIS-NIR and Shkuratov radiative transfer model. Montmorillonite-gypsum mixtures were used to test the effectiveness of the model in distinguishing between subtle differences in minor absorption features that are diagnostic of mineralogy in the presence of strong H2O absorptions that are not always diagnostic of distinct phases or mineral abundance. The optical constants (k-values) for both endmembers were determined from bi-directional reflectance spectra measured in RELAB as well as on an ASD FieldSpec3 in a controlled laboratory setting. Multiple size fractions were measured in order to derive a single k-value from optimization of the optical path length in the radiative transfer models. It is shown that with careful experimental conditions, optical constants can be accurately determined from powdered samples using a field spectrometer, consistent with previous studies. Variability in the montmorillonite hydration level increased the uncertainties in the derived k-values, but estimated modal abundances for the mixtures were still within 5% of the measured values. Results suggest that the Hapke model works well in distinguishing between hydrated phases that have overlapping H2O absorptions and it is able to detect gypsum and montmorillonite in these simple mixtures where they are present at levels of ∼10%. Care must be taken however to derive k-values from a sample with appropriate H2O content relative to the modeled spectra. These initial results are promising for the potential quantitative analysis of orbital remote sensing data of hydrated minerals, including more complex clay and sulfate assemblages such as mudstones examined by the Curiosity rover in Gale crater.

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

    NASA Astrophysics Data System (ADS)

    Bonaccorsi, R.; McKay, C. P.

    2009-12-01

    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

  4. Pathways of clay mineral transport in the coastal zone of the Brazilian continental shelf from Ceará to the mouth of the Amazon River

    NASA Astrophysics Data System (ADS)

    de Morais, J. O.; Tintelnot, M.; Irion, G.; Souza Pinheiro, L.

    2006-03-01

    The transport pathways of fine sediments (fraction <2 μm) along the Brazilian continental shelf from Ceará to the Amazon River mouth were studied by means of clay mineral analyses. On the continental shelf southeast of the Amazon mouth, fluctuations in clay mineral compositions reflect simple mixing between the suspended load of the North Brazil Current and sediment from several smaller rivers. Previously, clay mineral variations west of the Amazon mouth have been explained by variable settling velocities of different grain-size classes within the <2 μm fraction or by selective coagulation of individual clay mineral groups. By contrast, our experiments with river bank samples show that selective coagulation does not occur in Amazon River sediments. A more appropriate explanation for observed variations in clay mineral composition off the Amazon mouth seems to be, similarly to that for the shelf between Ceará and the Amazon mouth, a mixing of Amazon sediments with suspended material of the North Brazil Current. This interpretation is supported by data on clay mineral composition east and south of the Amazon mouth, showing more affinity to sediments of the North Brazil Current than to the suspended load of the Amazon River. Additionally, relatively low sedimentation rates and low concentrations of fine-grained sediments on the shelf suggest that high riverine input by the Amazon River does not overprint the sediments of the North Brazil Current in this region. The strong North Brazil Current shunts the Amazon suspended load in a north-westerly direction along the north-eastern coast of South America. Hence, stronger sedimentation of Amazon sediments would occur only west of the river mouth.

  5. Near-infrared reflectance spectra of mixtures of kaolin-group minerals: use in clay mineral studies

    USGS Publications Warehouse

    Crowley, J.K.; Vergo, N.

    1988-01-01

    Near-infrared (NIR) reflectance spectra for mixtures of ordered kaolinite and ordered dickite have been found to simulate the spectral response of disordered kaolinite. The amount of octahedral vacancy disorder in nine disordered kaolinite samples was estimated by comparing the same spectra to the spectra of reference mixtures. The resulting estimates are consistent with previously published estimates of vacancy disorder for similar kaolin minerals that were modeled from calculated X-ray diffraction patterns. -from Authors

  6. Effect of chlorine in clay-mineral specimens prepared on silver metal-membrane mounts for X-ray powder diffraction analysis

    USGS Publications Warehouse

    Poppe, L.J.; Commeau, J.A.; Pense, G.M.

    1989-01-01

    Silver metal-membrane filters are commonly used as substrates in the preparation of oriented clay-mineral specimens for X-ray powder diffraction (XRD). The silver metal-membrane filters, however, present some problems after heat treatment if either the filters or the samples contain significant amounts of chlorine. At elevated temperature, the chloride ions react with the silver substrate to form crystalline compounds. These compounds change the mass-absorption coefficient of the sample, reducing peak intensities and areas and, therefore, complicating the semiquantitative estimation of clay minerals. A simple procedure that eliminates most of the chloride from a sample and the silver metal-membrane substrate is presented here.

  7. Langmuir-Blodgett films of a clay mineral and ruthenium(II) complexes with a noncentrosymmetric structure.

    PubMed

    Umemura, Yasushi; Yamagishi, Akihiko; Schoonheydt, Robert; Persoons, André; De Schryver, Frans

    2002-02-13

    Mono- and multilayers of amphiphilic [Ru(phen)(2)(dcC12bpy)](2+) (phen = 1,10-phenanthroline, dcC12bpy = 4,4'-caboxyl-2,2'-bipyridyl didodecyl ester) hybridized with a clay mineral have been prepared by a modified Langmuir-Blodgett method, and their structures and properties have been investigated. Formation of a hybrid monolayer of the Ru(II) complex cations and the clay platelets at an air-clay suspension interface was confirmed by surface pressure-molecular area (pi-A) isotherm measurement and atomic force microscopic (AFM) observation. Multilayers were fabricated by depositing the hybrid monolayers onto glass substrates. The absorbance at 492 nm due to the Ru(II) complex cation in the multilayer increased linearly with the increase in the layer number, indicating layer-by-layer deposition of the hybrid monolayers. Because no increase in the second-harmonic generation (SHG) signal from the multilayers against the layer number was observed, the orientation of the Ru(II) complex cations in the layer would be disturbed. The hydrophilic surface of the transferred hybrid monolayer can be converted to a hydrophobic surface by dipping it in an aqueous solution of octadecylammonium chloride (ODAH(+)Cl(-)). The multilayers modified with ODAH(+) showed a quadratic relation between the SHG intensity and the layer number. This means that the Ru(II) complex cations in the multilayer are successfully oriented in a noncentrosymmetric way by the conversion of the surface property. Both a racemic mixture and an enantiomer of the Ru(II) complex cations were employed to examine the chiral effect on the film properties. The chiral contribution to the SHG signal was enhanced in the multilayer modified with ODAH(+).

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

    PubMed

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

    2013-01-01

    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 μm. 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.

  9. Mars atmosphere. The imprint of atmospheric evolution in the D/H of Hesperian clay minerals on Mars.

    PubMed

    Mahaffy, P R; Webster, C R; Stern, J C; Brunner, A E; Atreya, S K; Conrad, P G; Domagal-Goldman, S; Eigenbrode, J L; Flesch, G J; Christensen, L E; Franz, H B; Freissinet, C; Glavin, D P; Grotzinger, J P; Jones, J H; Leshin, L A; Malespin, C; McAdam, A C; Ming, D W; Navarro-Gonzalez, R; Niles, P B; Owen, T; Pavlov, A A; Steele, A; Trainer, M G; Williford, K H; Wray, J J

    2015-01-23

    The deuterium-to-hydrogen (D/H) ratio in strongly bound water or hydroxyl groups in ancient martian clays retains the imprint of the water of formation of these minerals. Curiosity's Sample Analysis at Mars (SAM) experiment measured thermally evolved water and hydrogen gas released between 550° and 950°C from samples of Hesperian-era Gale crater smectite to determine this isotope ratio. The D/H value is 3.0 (±0.2) times the ratio in standard mean ocean water. The D/H ratio in this ~3-billion-year-old mudstone, which is half that of the present martian atmosphere but substantially higher than that expected in very early Mars, indicates an extended history of hydrogen escape and desiccation of the planet.

  10. Characterization of clay minerals and organic matter in shales: Application to high-level nuclear waste isolation

    SciTech Connect

    Gueven, N.; Landis, C.R.; Jacobs, G.K.

    1988-10-01

    The objective of the Sedimentary Rock Program at the Oak Ridge National Laboratory is to conduct investigations to assess the potential for shale to serve as a host medium for the isolation of high-level nuclear wastes. The emphasis on shale is a result of screening major sedimentary rock types (shale, sandstone, carbonate , anhydrite, and chalk) for a variety of attributes that affect the performance of repositories. The retardation of radionuclides was recognized as one of the potentially favorable features of shale. Because shale contains both clay minerals and organic matter, phases that may provide significant sorption of radioelement, the characterization of these phases is essential. In addition, the organic matter in shale has been identified as a critical area for study because of its potential to play either a favorable (reductant) or deleterious (organic ligands) role in the performance of a repository sited in shale. 36 refs., 36 figs., 10 tabs.

  11. Mars atmosphere. The imprint of atmospheric evolution in the D/H of Hesperian clay minerals on Mars.

    PubMed

    Mahaffy, P R; Webster, C R; Stern, J C; Brunner, A E; Atreya, S K; Conrad, P G; Domagal-Goldman, S; Eigenbrode, J L; Flesch, G J; Christensen, L E; Franz, H B; Freissinet, C; Glavin, D P; Grotzinger, J P; Jones, J H; Leshin, L A; Malespin, C; McAdam, A C; Ming, D W; Navarro-Gonzalez, R; Niles, P B; Owen, T; Pavlov, A A; Steele, A; Trainer, M G; Williford, K H; Wray, J J

    2015-01-23

    The deuterium-to-hydrogen (D/H) ratio in strongly bound water or hydroxyl groups in ancient martian clays retains the imprint of the water of formation of these minerals. Curiosity's Sample Analysis at Mars (SAM) experiment measured thermally evolved water and hydrogen gas released between 550° and 950°C from samples of Hesperian-era Gale crater smectite to determine this isotope ratio. The D/H value is 3.0 (±0.2) times the ratio in standard mean ocean water. The D/H ratio in this ~3-billion-year-old mudstone, which is half that of the present martian atmosphere but substantially higher than that expected in very early Mars, indicates an extended history of hydrogen escape and desiccation of the planet. PMID:25515119

  12. Clay-mineral segregation by differential flocculation: Jourdan River-St. Louis Bay estuary, Hancock County, Mississippi

    SciTech Connect

    McRae, G.

    1988-09-01

    Within the Jourdan River-St. Louis Bay estuarine system, the dominant depositional mechanism of suspended clays is preferential flocculation of kaolinite with increasing salinity. Flocculation and deposition of kaolinite occur mainly within the confines of the Jourdan River, hence the effects of differential gravity settling of mineral species are unlikely. Statistical analyses show that water turbidity and salinity are linearly related to distance from the mouth of the Jourdan River and to each other up to the point where kaolinite is largely removed from the suspended sediments by flocculation. X-ray diffraction data show that maximum flocculation of suspended kaolinite has occurred where the kaolinite/illite ratio (K/I) reaches its minimum. Bottom-sediment mineralogy follows the trend of the suspended sediments with K/I of the bottom sediments increasing as K/I of the suspended sediments decreases.

  13. Cesium and Strontium Uptake to Clay Minerals and Their Weathering Products in a Caustic Waste

    SciTech Connect

    Choi, Sunkyung; Amistadi, Mary Kay; Seraphin, Supapan; Chorover, Jon

    2004-03-28

    Weathering behavior and contaminant (Sr and Cs) uptake by specimen clays (illite, vermiculite, montmorillonite and kaolinite) and their secondary solid phase products were studied in batch systems under geochemical conditions characteristic of leaking tank waste at the Hanford Site in WA (0.05 M AlT, 2 M Na+, 1 M NO3 -, pH {approx}14, Cs+ and Sr2+ present as co-contaminants). Time series experiments were conducted from 0 to 369 days, with initial Cs+ and Sr2+ concentrations ranging from 10-5 to 10-3 M. Cesium sorption after 369 d reaction was the greatest in the order of vermiculite, illite, montmorillonite and kaolinite at 10-3 M Cs/Sr. In the case of Sr, vermiculite showed highest Sr sorption and was followed by kaolinite, montmorillonite and illite at highest loading Cs/Sr after 369 d. Secondary phase products were feldspathoid sodium aluminum nitrate silicate, sodium aluminum nitrate silicate hydrate, Na-Al chabazite and zeolite X in weathered clays. Discrete Sr single phases were found in kaolinite and illite systems after 369 d at 10-3 M Cs/Sr.

  14. Clay minerals in primitive meteorites and interplanetary dust 2. Smectites and micas

    NASA Technical Reports Server (NTRS)

    Keller, L. P.; Zolensky, M. E.

    1991-01-01

    The classification is briefly summarized of stony meteorites and cosmic dust, and the mineralogy and chemistry is described of serpentine group minerals. The occurrence of smectites and micas in extraterrestrial materials is examined. The characterization of fine grained minerals in meteorites and IDPs relies heavily on electron beam instruments, especially the transmission electron microscope (TEM). Typically, phyllosilicates are identified by a combination of high resolution imaging of basal spacings, electron diffraction, and chemical analysis. Smectites can be difficult to differentiate from micas because the smectites lose their interlayer water and the interlayer partly collapse in the high vacuum of the TEM.

  15. Stratigraphic and climatic implications of clay mineral changes around the Paleocene/Eocene boundary of the northeastern US margin

    USGS Publications Warehouse

    Gibson, T.G.; Bybell, L.M.; Mason, D.B.

    2000-01-01

    Kaolinite usually is present in relatively small amounts in most upper Paleocene and lower Eocene neritic deposits of the northern US Atlantic Coastal Plain. However, there is a short period (less than 200,000 k.y.) in the latest Paleocene (upper part of calcareous nannoplankton Zone NP 9) when kaolinite-dominated clay mineral suites replaced the usual illite/smectite-dominated suites. During this time of global biotic and lithologic changes, kaolinite increased from less than 5% of the clay mineral suite to peak proportions of 50-60% of the suite and then returned to less than 5% in uppermost Paleocene/lowermost Eocene strata. This kaolinite pulse is present at numerous localities from southern Virginia to New Jersey. These sites represent both inner and middle neritic depositional environments and reflect input from several river drainage systems. Thus, it is inferred that kaolinite-rich source areas were widespread in the northeastern US during the latest Paleocene. Erosion of these source areas contributed the kaolinite that was transported and widely dispersed into shelf environments of the Salisbury embayment. The kaolinite increase, which occurred during a time of relatively high sea level, probably is the result of intensified weathering due to increased temperature and precipitation. The southern extent of the kaolinite pulse is uncertain in that uppermost Paleocene beds have not been identified in the southern Atlantic Coastal Plain. The late Paleocene kaolinite pulse that consists of an increase to peak kaolinite levels followed by a decrease can be used for detailed correlation between more upbasin and more downbasin sections in the Salisbury embayment. Correlations show that more upbasin Paleocene/Eocene boundary sections are erosionally truncated. They have varying portions of the kaolinite increase and, if present at all, discontinuous portions of the subsequent kaolinite decrease. As these truncated sections are disconformably overlain by lower

  16. Chemical and physical transformations of aluminosilicate clay minerals due to acid treatment and consequences for heterogeneous ice nucleation.

    PubMed

    Sihvonen, Sarah K; Schill, Gregory P; Lyktey, Nicholas A; Veghte, Daniel P; Tolbert, Margaret A; Freedman, Miriam Arak

    2014-09-25

    Mineral dust aerosol is one of the largest contributors to global ice nuclei, but physical and chemical processing of dust during atmospheric transport can alter its ice nucleation activity. In particular, several recent studies have noted that sulfuric and nitric acids inhibit heterogeneous ice nucleation in the regime below liquid water saturation in aluminosilicate clay minerals. We have exposed kaolinite, KGa-1b and KGa-2, and montmorillonite, STx-1b and SWy-2, to aqueous sulfuric and nitric acid to determine the physical and chemical changes that are responsible for the observed deactivation. To characterize the changes to the samples upon acid treatment, we use X-ray diffraction, transmission electron microscopy, and inductively coupled plasma-atomic emission spectroscopy. We find that the reaction of kaolinite and montmorillonite with aqueous sulfuric acid results in the formation of hydrated aluminum sulfate. In addition, sulfuric and nitric acids induce large structural changes in montmorillonite. We additionally report the supersaturation with respect to ice required for the onset of ice nucleation for these acid-treated species. On the basis of lattice spacing arguments, we explain how the chemical and physical changes observed upon acid treatment could lead to the observed reduction in ice nucleation activity. PMID:25211030

  17. Chemical and physical transformations of aluminosilicate clay minerals due to acid treatment and consequences for heterogeneous ice nucleation.

    PubMed

    Sihvonen, Sarah K; Schill, Gregory P; Lyktey, Nicholas A; Veghte, Daniel P; Tolbert, Margaret A; Freedman, Miriam Arak

    2014-09-25

    Mineral dust aerosol is one of the largest contributors to global ice nuclei, but physical and chemical processing of dust during atmospheric transport can alter its ice nucleation activity. In particular, several recent studies have noted that sulfuric and nitric acids inhibit heterogeneous ice nucleation in the regime below liquid water saturation in aluminosilicate clay minerals. We have exposed kaolinite, KGa-1b and KGa-2, and montmorillonite, STx-1b and SWy-2, to aqueous sulfuric and nitric acid to determine the physical and chemical changes that are responsible for the observed deactivation. To characterize the changes to the samples upon acid treatment, we use X-ray diffraction, transmission electron microscopy, and inductively coupled plasma-atomic emission spectroscopy. We find that the reaction of kaolinite and montmorillonite with aqueous sulfuric acid results in the formation of hydrated aluminum sulfate. In addition, sulfuric and nitric acids induce large structural changes in montmorillonite. We additionally report the supersaturation with respect to ice required for the onset of ice nucleation for these acid-treated species. On the basis of lattice spacing arguments, we explain how the chemical and physical changes observed upon acid treatment could lead to the observed reduction in ice nucleation activity.

  18. Nitrogen mineralization potential of three animal manures applied on a sandy clay loam soil.

    PubMed

    Azeez, J O; Van Averbeke, W

    2010-07-01

    Understanding the dynamics of N forms applied as manure is germane for appropriate rate and timing of applications of manure. Manure characterization and laboratory incubation were conducted for 120 days to study the mineralization of poultry, cattle and goat manures. Results showed that manure properties differ. Net immobilization of N was recorded for goat and cattle manures while poultry manure mineralized marginally. The relationship between N release and time is polynomial (cubic). The release phases were: initial rapid N release at 0-30 days; phase of constant release; 40-55 days; decline phase in N release 70-90 days and sharp increase in N release at 120 days. Increasing the N rates of manures above 120 kgNha(-1) will improve their potential as plant nutrient sources. Complementing the manures with inorganic N fertilizers in integrated nutrient management will also improve its quality and effectiveness. PMID:20171089

  19. Oligomerization of glycine on clay mineral surface and implication to oligin of life under seafloor hydrothermal conditions

    NASA Astrophysics Data System (ADS)

    Fuchida, S.; Masuda, H.

    2012-12-01

    The sediments at hydrothermal and/or various parts of the crust has been believed to be good environments to proceed the chemical evolution of life precursor, since minerals promoted oligomerization of amino acids, sugars and lipids on the primitive earth. In this study, the thermal behaviors of glycine (Gly), the simplest amino acid, adsorbed on montmorillonite was observed to evaluate the role of clay minerals and water on the oligomerization under thermal condition of sediments. Gly was adsorbed on montmorillonite was heated at 150 degree C for 3-288 hrs under dry and wet condition. In the latter case, 10 - 60% water was added in the system. The amount of Gly monomer remaining in the montmorillonite exponentially decreased with time; 46% Gly remained in the montmorillonite under dry condition and 74% under wet condition after 288 hrs. The Gly monomer was more stable under hydrothermal condition than dry thermal condtion. FT-IR analysis suggested that the Gly was intercalated in the montmorillonite via hydrogen bond, which is likely to promote to stabilize Gly, between amino group of the Gly and silanol group of the montmorillonite. On the contrast, the yields of peptides were low on motmorillonite after heated under the wet condition: the amounts of glycilglycine (Gly-Gly) and diketopiperazine (DKP) are 0.8% and 0.9%, respectively. The amounts of DKP and GlyGly are 12.9% and 4.8% after heated under the dry condtion. Excessive water would promote to hydrolyze synthesized peptides. New band at 1671cm-1 by FT-IR implies that DKP was condensed on the montmorillonite. DKP was not formed without montmorillonite under the dry condition, although peptide formation is theoretically favorable. Water molecules including in the montmorillonite would act as proton transfer to promote the peptide formation. The peptide formation would be more proceeded under a little wet condition than completely dry condition. Results of this study suggested that deep sediments, where

  20. Clay mineral contribution from various provenances in the northern South China Sea over the past 400 kyr: implications for the East Asian monsoon evolution

    NASA Astrophysics Data System (ADS)

    Chen, Quan; Liu, Zhifei; Xie, Xin; Kissel, Catherine

    2014-05-01

    Clay mineralogy of Core MD12-3432 taken at 2125 m water depth (CIRCEA cruise on board the R.V. Marion Dufresne, IPEV) in the northern South China Sea was investigated in order to understand the time series contribution of terrigenous sediments from various provenances. With calibration of a low-resolution analysis on carbonate concentration and major elements, we converted the XRF core scanned calcium data into a high-resolution carbonate content records. Through referring to the well-dated carbonate record of nearby Core MD05-2904, we established a reliable age model, indicating about 400 kyr ago at the bottom of Core MD12-3432. The clay mineral assemblage is dominated by smectite (23-59%) and illite (22-43%), with minor chlorite (13-27%) and kaolinite (4-13%). The time series variation of clay mineral assemblages indicates strong glacial-interglacial cyclicity. In general, the variation in smectite content is similar to that of carbonate concentration, with higher values during interglacials than during glacials, while illite and chlorite contents showing opposite patterns. The change in kaolinite content shows an independent pattern with high values during glacials, corresponding well with the illite crystallinity variation. The provenance analysis of these clay minerals suggests three end-member sources: all smectites derive from Luzon, all kaolinites originate from the Pearl River, and illite and chlorite are coming from both the Pearl River and Taiwan. Using the linear separation method of illite crystallinity, a time series of the clay mineral contribution from the three major provenances to the northern South China Sea was reconstructed. Combined with spectral analyses, we suggest the clay mineral contribution from Pearl River was mainly influenced by sea level change, while the East Asian summer monsoon controlled the contribution from Luzon. The strong precipitation rate related to intensive East Asian summer monsoon would have enhanced the denudation and

  1. Bioavailability of iron in geophagic earths and clay minerals, and their effect on dietary iron absorption using an in vitro digestion/Caco-2 cell model.

    PubMed

    Seim, Gretchen L; Ahn, Cedric I; Bodis, Mary S; Luwedde, Flavia; Miller, Dennis D; Hillier, Stephen; Tako, Elad; Glahn, Raymond P; Young, Sera L

    2013-08-01

    Geophagy, the deliberate consumption of earth, is strongly associated with iron (Fe) deficiency. It has been proposed that geophagy may be practiced as a means to improve Fe status by increasing Fe intakes and, conversely, that geophagy may cause Fe deficiency by inhibiting Fe absorption. We tested these hypotheses by measuring Fe concentration and relative bioavailable Fe content of 12 samples of geophagic earth and 4 samples of pure clay minerals. Further, we assessed the impact of these samples on the bioavailability of Fe from an Fe-rich test meal (cooked white beans, WB). Fe concentrations were measured with inductively coupled plasma atomic emission spectroscopy. Fe bioavailability was determined using an in vitro digestion/Caco-2 cell model in which ferritin formation was used as an index of Fe bioavailability. Geophagic earth and clay mineral samples were evaluated with this model, both alone and in combination with WB (1 : 16 ratio, sample : WB). Median Fe concentration of the geophagic earth was 3485 (IQR 2462, 14 ,571) μg g⁻¹ and mean Fe concentration in the clay minerals was 2791 (±1782) μg g⁻¹. All specimens had Fe concentrations significantly higher (p ≤ 0.005) than the Fe concentration of WB (77 μg g⁻¹). Ferritin formation (i.e. Fe uptake) in cells exposed to geophagic earths and clay minerals was significantly lower than in cells exposed to WB (p ≤ 0.05) and Fe uptake responses of 11 of the 16 samples were not significantly different from the blank, indicating no bioavailable Fe. When samples were combined with WB, 5 of 16 had mean ferritin levels that were significantly lower (p ≤ 0.05, one tail) than the WB alone, indicating that the samples inhibited Fe uptake from the WB. None of the ferritin responses of cells exposed to both WB and earth/clay were significantly higher than WB alone. Thus, although geophagic earths and mineral clays are high in total Fe, very little of this Fe is bioavailable. Further, some

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

    NASA Astrophysics Data System (ADS)

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

    2007-12-01

    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.

  3. Antibiotic eluting clay mineral (Laponite®) for wound healing application: an in vitro study.

    PubMed

    Ghadiri, M; Chrzanowski, W; Rohanizadeh, R

    2014-11-01

    Different materials in form of sponge, hydrogel and film have been developed and formulated for treating and dressing burn wounds. In this study, the potential of Laponite, a gel forming clay, in combination with an antimicrobial agent (mafenide), as a wound dressing material was tested in vitro. Laponite/mafenide (Lap/Maf) hydrogel was formulated in three different ratios of Lap/Maf 1:1, 1:2, 1:3. Laponite/mafenide/alginate (Lap/Maf/Alg) film was also formulated by combining Lap/Maf gel (1:1) with alginate. Intercalation rate of mafenide into the layers of Laponite nanoparticles and physico-chemical properties, including wound dressing characteristics of materials were studied using various analytical methods. Furthermore, the degradation of materials and the release profile of mafenide were investigated in simulated wound exudates fluid and antibacterial effectiveness of the eluted mafenide was tested on a range of bacterial species. The cytotoxicity of materials was also evaluated in skin fibroblast culture. The results showed that mafenide molecules were intercalated between the nano-sized layers of Laponite. The eluted mafenide showed active antibacterial effects against all three tested bacteria. All intercalated mafenide released from Lap/Maf 1:1 and 1:2 gel formulations and nearly 80% release from 1:3 formulation during test period. No significant difference was observed in release profile of mafenide between Lap/Maf/Alg film and Lap/Maf formulations. Wound dressing tests on Lap/Maf/Alg film showed it is a breathable dressing and has capacity to absorb wound exudates. The study showed that prepared Lap/Maf composite has the potential to be used as an antibiotic eluting gel or film for wound healing application. Additionally, Laponite has shown benefits in wound healing processes by releasing Mg(2+) ions and thereby reducing the cytotoxic effect of mafenide on fibroblast cells.

  4. 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.

    PubMed

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

    2002-12-01

    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 microorganisms, 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 MR-1 as well as enrichment cultures of Fe(III)-reducing bacteria from rice paddy soil and subsurface sediments are capable of conserving energy for growth with the structural Fe(III) bound in smectite clay as the sole electron acceptor. Pure cultures of S. oneidensis were used for more detailed growth rate and yield experiments on various solid- and soluble-phase electron acceptors [smectite, Fe(III) oxyhydroxide FeOOH, Fe(III) citrate, and oxygen] in the same minimal medium. Growth was assessed as direct cell counts or as an increase in cell carbon (measured as particulate organic carbon). Cell counts showed that similar growth of S. oneidensis (10(8) cells ml(-1)) occurred with smectitic Fe(III) and on other Fe forms [amorphous Fe(III) oxyhydroxide, and Fe citrate] or oxygen as the electron acceptor. In contrast, cell yields of S. oneidensis measured as the increase in cell carbon were similar on all Fe forms tested while yields on oxygen were five times higher, in agreement with thermodynamic predictions. Over a range of particle loadings (0.5 to 4 g liter(-1)), the increase in cell number was highly correlated to the amount of structural Fe in smectite reduced. From phylogenetic analysis of the complete 16S rRNA gene sequences, a predominance of clones retrieved from the clay mineral-reducing enrichment cultures were most closely related to the low-G+C gram-positive members of the Bacteria (Clostridium and Desulfitobacterium) and the delta-Proteobacteria (members of the Geobacteraceae). Results indicate that growth with smectitic Fe(III) is similar in magnitude to that with Fe

  5. Failure of dietary bentonite clay, Silent Herder mineral supplement, or parenteral Banamine to alleviate locoweed toxicosis in rats.

    PubMed

    Dugarte-Stavanja, M; Smith, G S; Edrington, T S; Hallford, D M

    1997-07-01

    To evaluate treatments purportedly beneficial for livestock grazing locoweeds (LW), growing rats were fed diets containing 10 or 20% whole-plant Oxytropis sericea (LW) with and without Silent Herder mineral mix (1.5% of diet) or bentonite clay (1.5% of diet). Pregnant female rats fed 10% LW were treated i.m. with Banamine (a prostaglandins suppressor) or saline. The LW contained swainsonine (430 micrograms/g DM) and elicited toxicosis within 10 d at intake of 2 mg/kg BW. In Trial 1, 96 immature male Sprague-Dawley rats (BW approximately 100 g) were fed commercial rat feed (CRF) with and without LW, as follows: 100% CRF, free choice; 100% CRF, restricted intake to equal average intake of rats consuming 10 and 20% LW; 90% CRF+10% LW free choice; and 80% CRF+20% LW free choice. Diets with LW contained either no supplement or supplemental mineral mixture (Silent Herder, 1.5% of diet) or added bentonite clay (1.5% of diet). Twelve rats received each of eight dietary regimens through 28 d. Locoweed depressed (P < .05) feed intake and BW gain, increased (P < .05) relative size of liver, kidneys, heart, spleen, and testes, and altered blood serum components (P < .05) indicating toxicosis. Dietary provision of Silent Herder or bentonite failed to benefit rats that ingested approximately 4 or 8 mg of swainsonine/kg BW daily through 28 d. In Trial 2, 68 young adult female Sprague-Dawley rats (approximately 230 g BW) were mated and directly assigned to three diets (100% CRF, free choice, 100% CRF, intake restricted slightly below average intake of diet by rats consuming LW, or 90% CRF+10% LW free choice) and two treatments (i.m. saline or i.m. Banamine at .25 mg/kg BW daily for 10 d) in a 3 x 2 factorial arrangement. Approximately half (31 of 68) of the impregnated rats were killed at d 10, when Banamine was discontinued, but diets were continued until the remaining females gave birth. Ingested LW provided approximately 2 mg swainsonine/kg BW daily and elicited toxicosis in 10

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

    SciTech Connect

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

    2009-06-20

    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

  7. Adsorption of dissolved aluminum on sapphire-c and kaolinite: implications for points of zero charge of clay minerals.

    PubMed

    Lützenkirchen, Johannes; Abdelmonem, Ahmed; Weerasooriya, Rohan; Heberling, Frank; Metz, Volker; Marsac, Remi

    2014-01-01

    We have studied the impact of dissolved aluminum on interfacial properties of two aluminum bearing minerals, corundum and kaolinite. The effect of intentionally adding dissolved aluminum on electrokinetic potential of basal plane surfaces of sapphire was studied by streaming potential measurements as a function of pH and was complemented by a second harmonic generation (SHG) study at pH 6. The electrokinetic data show a similar trend as the SHG data, suggesting that the SHG electric field correlates to zeta-potential. A comparable study was carried out on kaolinite particles. In this case electrophoretic mobility was measured as a function of pH. In both systems the addition of dissolved aluminum caused significant changes in the charging behavior. The isoelectric point consistently shifted to higher pH values, the extent of the shift depending on the amount of aluminum present or added. The experimental results imply that published isoelectric points of clay minerals may have been affected by this phenomenon. The presence of dissolved aluminum in experimental studies may be caused by particular pre-treatment methods (such as washing in acids and subsequent adsorption of dissolved aluminum) or even simply by starting a series of measurements from extreme pH (causing dissolution), and subsequently varying the pH in the very same batch. This results in interactions of dissolved aluminum with the target surface. A possible interpretation of the experimental results could be that at low aluminum concentrations adatoms of aluminum (we will refer to adsorbed mineral constituents as adatoms) can form at the sapphire basal plane, which can be rather easily removed. Simultaneously, once the surface has been exposed to sufficiently high aluminum concentration, a visible change of the surface is seen by AFM which is attributed to a surface precipitate that cannot be removed under the conditions employed in the current study. In conclusion, whenever pre-treatment or the

  8. Adsorption of dissolved aluminum on sapphire-c and kaolinite: implications for points of zero charge of clay minerals

    PubMed Central

    2014-01-01

    We have studied the impact of dissolved aluminum on interfacial properties of two aluminum bearing minerals, corundum and kaolinite. The effect of intentionally adding dissolved aluminum on electrokinetic potential of basal plane surfaces of sapphire was studied by streaming potential measurements as a function of pH and was complemented by a second harmonic generation (SHG) study at pH 6. The electrokinetic data show a similar trend as the SHG data, suggesting that the SHG electric field correlates to zeta-potential. A comparable study was carried out on kaolinite particles. In this case electrophoretic mobility was measured as a function of pH. In both systems the addition of dissolved aluminum caused significant changes in the charging behavior. The isoelectric point consistently shifted to higher pH values, the extent of the shift depending on the amount of aluminum present or added. The experimental results imply that published isoelectric points of clay minerals may have been affected by this phenomenon. The presence of dissolved aluminum in experimental studies may be caused by particular pre-treatment methods (such as washing in acids and subsequent adsorption of dissolved aluminum) or even simply by starting a series of measurements from extreme pH (causing dissolution), and subsequently varying the pH in the very same batch. This results in interactions of dissolved aluminum with the target surface. A possible interpretation of the experimental results could be that at low aluminum concentrations adatoms of aluminum (we will refer to adsorbed mineral constituents as adatoms) can form at the sapphire basal plane, which can be rather easily removed. Simultaneously, once the surface has been exposed to sufficiently high aluminum concentration, a visible change of the surface is seen by AFM which is attributed to a surface precipitate that cannot be removed under the conditions employed in the current study. In conclusion, whenever pre-treatment or the

  9. Adsorption of dissolved aluminum on sapphire-c and kaolinite: implications for points of zero charge of clay minerals.

    PubMed

    Lützenkirchen, Johannes; Abdelmonem, Ahmed; Weerasooriya, Rohan; Heberling, Frank; Metz, Volker; Marsac, Remi

    2014-01-01

    We have studied the impact of dissolved aluminum on interfacial properties of two aluminum bearing minerals, corundum and kaolinite. The effect of intentionally adding dissolved aluminum on electrokinetic potential of basal plane surfaces of sapphire was studied by streaming potential measurements as a function of pH and was complemented by a second harmonic generation (SHG) study at pH 6. The electrokinetic data show a similar trend as the SHG data, suggesting that the SHG electric field correlates to zeta-potential. A comparable study was carried out on kaolinite particles. In this case electrophoretic mobility was measured as a function of pH. In both systems the addition of dissolved aluminum caused significant changes in the charging behavior. The isoelectric point consistently shifted to higher pH values, the extent of the shift depending on the amount of aluminum present or added. The experimental results imply that published isoelectric points of clay minerals may have been affected by this phenomenon. The presence of dissolved aluminum in experimental studies may be caused by particular pre-treatment methods (such as washing in acids and subsequent adsorption of dissolved aluminum) or even simply by starting a series of measurements from extreme pH (causing dissolution), and subsequently varying the pH in the very same batch. This results in interactions of dissolved aluminum with the target surface. A possible interpretation of the experimental results could be that at low aluminum concentrations adatoms of aluminum (we will refer to adsorbed mineral constituents as adatoms) can form at the sapphire basal plane, which can be rather easily removed. Simultaneously, once the surface has been exposed to sufficiently high aluminum concentration, a visible change of the surface is seen by AFM which is attributed to a surface precipitate that cannot be removed under the conditions employed in the current study. In conclusion, whenever pre-treatment or the

  10. Clay minerals and gravels of late Pleistocene interstadial coastal sediments above the current sea level, south coast of Korea

    NASA Astrophysics Data System (ADS)

    Yang, D. Y.; Kim, J. C.; Lim, J.; Yi, S.; Nahm, W. H.; Kim, J. Y.; Han, M.

    2015-12-01

    At nowadays, the severe greenhouse effect causes rapid sea level rise around the Korea Peninsula. Paleo-climate researches have been concentrating on hydrological activities during the mid-Holocene optimum and the last interglacial period to use the paleo-analogues data in predicting the future hydrological environments. The previous studies on the late Pleistocene interstadial coastal sediments have primarily been biased towards the terraces of the east coast in the Korean Peninsula. According to the results, the last interglacial marine terraces of the east coast were existed at 18 m in elevation. Uplift rate of them was presumed to be 0.1mm/year (Choi, 2006). Also, the stratigraphy of the Quaternary coastal deposits of the Yellow Sea has been suggested by Park et al. (1998) and Lim et al. (2003). In recent, Jang et al. (2014) reported the OSL dated Eemian marine deposit along the southwest coast of Korea. However, the age-equivalent outcrops of the south coast are not discovered yet. The first outcrops of the late Pleistocene interstadial coastal sediment above the present sea level were discovered at IJin-ri site of Haenam, south coast of Korea. It would be very useful for calculating the rates of Eemian sea level rise and uplift of south coast of Korea. 62 cubic samples were collected at 6 cm intervals from the section (4.8-8.83m in elevation). Four sedimentary units, from Unit 1 to 4 in ascending order, are distinguished based on sedimentary textures and grain size distribution as follows: Unit 1 (sand, 4.8 m-5.32 m in elevation), Unit 2 (silty clay, 5.32 m-6.8 m in elevation), Unit 3 (gravelly sand, 6.8m-7.8m in elevation) and, Unit 4(sandy gravel, 7.8m-8.83m in elevation). The sediments which included rounded or semi-rounded gravels are thought to be transported from marine. Also, the assemblages of clay minerals from the sections are similar to those of Yellow Sea. It shows the possibility that the sediments originated from marine during high sea level

  11. Potential application of microbial iron redox cycles in nitrate removal and their effects on clay mineral properties

    NASA Astrophysics Data System (ADS)

    Zhao, L.; Dong, H.; Kukkadapu, R. K.; Briggs, B. R.; Zeng, Q.

    2014-12-01

    Phyllosilicates that are ubiquitous in subsurface can serve as an iron source for microbial respiration. The objective of this research is to determine the ability of the phyllosilicate Fe to remove nitrate in subsurface undergoing microbial-driven redox cycles. In this study, thus, a well-characterized reference clay (NAu-2; nontronite), was subjected to redox cycles in a system containing dissimilatory Fe(III)-reducing bacteria, Shewanella putrefaciens CN32, and nitrate-dependent Fe(II)-oxidizing bacteria, Pseudogulbenkiania sp. Strain 2002. Three redox cycles were conducted in bicarbonate- and PIPES-buffered medium. The extents of Fe(III) reduction, Fe(II) oxidation, nitrate reduction, and its various intermediate products were measured by wet chemical methods. For each cycle, Electron Energy Loss Spectroscopy and Mossbauer spectroscopy confirmed Fe oxidation state. Mineralogical changes were identified by using X-ray diffraction (XRD), 57Fe-Mössbauer spectroscopy, and infrared absorption spectroscopy. For all three cycles, nitrate was completely reduced to nitrogen gas under both bicarbonate- and PIPES- buffered conditions. As redox cycle increased, bio-reduction extents of Fe(III) in NAu-2 decreased by 33% and 48% in PIPES- and bicarbonate-buffered medium, respectively; however, bio-oxidation extents increased by 66% and 55% in the same medium, respectively. Despite the change of OH-stretching vibration band and OH-bending vibration bands in NAu-2 structure along Fe redox cycles, XRD data showed interlayer spacing of NAu-2 to be constant along the same Fe redox cycle. 57Fe-Mössbauer spectroscopy indicated complex reduction and re-oxidation pathways. For example, a distinct Fe(II) doublet and a Fe2.5+ feature due to interfacial Fe(II)-Fe(III) electron transfer on clay mineral are prominent in their RT spectra. Both these Fe(II) are partially oxidized by Fe(II)-oxidizing bacteria. The result of this study shows that Fe in biogenically reduced or oxidized NAu-2

  12. 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

    Bodine, M.W., Jr.

    1987-01-01

    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.

  13. Insights into the Mechanism of Fe(II) Adsorption and Oxidation at Fe-Clay Mineral Surfaces from First-Principles Calculations

    SciTech Connect

    Alexandrov, Vitali Y.; Rosso, Kevin M.

    2013-10-02

    Interfacial reactivity of redox-active iron-bearing mineral surfaces plays a crucial role in many environmental processes including biogeochemical cycling of various elements and contaminants. Herein, we apply density-functional-theory (DFT) calculations to provide atomistic insights into the heterogeneous reaction between aqueous Fe(II) and the Fe-bearing clay mineral nontronite Fe2Si4O10(OH)2 by studying its adsorption mechanism and interfacial Fe(II)-Fe(III) electron transfer (ET) at edge and basal surfaces. We find that edge-bound Fe(II) adsorption complexes at different surface sites (ferrinol, silanol and mixed) may coexist on both (010) and (110) edge facets, with complexes at ferrinol FeO(H) sites being the most energetically favorable and coupled to proton transfer. Calculation of the ET activation energy suggests that interfacial ET into dioctahedral Fe(III) sheets is probable at the clay edges and occurs predominantly but not exclusively through the complexes adsorbed at ferrinol sites and might also involve mixed sites. No clear evidence is found for complexes on basal surface that are compatible with ET through the basal sheet despite this experimentally hypothesized ET interface. This study suggests a strong pH-dependence of Fe(II) surface complexation at basal versus edge facets and highlights the importance of the protonation state of bridging ligands and proton coupled electron transfer to facilitate ET into Fe-rich clay minerals.

  14. Synergy between polyaniline and OMt clay mineral in Langmuir-Blodgett films for the simultaneous detection of traces of metal ions.

    PubMed

    de Barros, Anerise; Ferreira, Mariselma; Constantino, Carlos José Leopoldo; Bortoleto, José Roberto Ribeiro; Ferreira, Marystela

    2015-04-01

    We report on Langmuir-Blodgett (LB) films made with emeraldine salt polyaniline (PAni-ES) and organophilic montmorillonite clay mineral (OMt), where synergy between the components was reached to yield an enhanced performance in detecting trace levels of cadmium (Cd(2+)), lead (Pb(2+)) and copper (Cu(2+)). Detection was carried out using square wave anodic stripping (SWAS) voltammetry with indium tin oxide (ITO) electrodes modified with LB films of PAni-ES/OMt nanocomposite, whose data were compared to those obtained with electrodes coated with neat PAni-ES and neat OMt LB films. The enhanced performance in the nanocomposite may be attributed to the stabilizing and ordering effect promoted by OMt in PAni-ES Langmuir films, which then led to more homogeneous LB films. According to X-ray diffraction data, the stacking of OMt layers was preserved in the LB films and therefore the PAni-ES chains did not cause clay mineral exfoliation. Instead, OMt affected the polaronic state of PAni-ES as indicated in UV-vis, Raman and FTIR spectra, also consistent with the changes observed for the Langmuir films. Taken together these results do indicate that semiconducting polymers and clay minerals may be combined for enhancing the electrical properties of nanostructures for sensing and related applications.

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

    SciTech Connect

    Jaisi, D. P.; Dong, H.; Plymale, A. E.; Fredrickson, J. K.; Zachara, J. M.; Heald, S.; Liu, C.; Miami Univ.; PNNL

    2009-01-01

    {sup 99}Tc 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)O{sub 4}{sup -}) and its possible uptake into the food chain cause {sup 99}Tc 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)O{sub 4}{sup -} 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 these 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{sup +}-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 TcO{sub 2} {center_dot} nH{sub 2}O), the extent of Tc(IV) reoxidation decreased significantly relative to fresh Tc(IV) products. Increasing NAu-2 concentration

  16. Evaluation of the endotoxin binding efficiency of clay minerals using the Limulus Amebocyte lysate test: an in vitro study

    PubMed Central

    2014-01-01

    Endotoxins are part of the cell wall of Gram-negative bacteria. They are potent immune stimulators and can lead to death if present in high concentrations. Feed additives, which bind endotoxins in the gastrointestinal tract of animals, could help to prevent their negative impact. The objective of our study was to determine the potential of a bentonite (Bentonite 1), a sodium bentonite (Bentonite 2), a chemically treated smectite (Organoclay 1) and a modified attapulgite (Organoclay 2) to bind endotoxins in vitro. Polymyxin B served as positive control. The kinetic chromogenic Limulus Amebocyte lysate test was adapted to measure endotoxin activity. Firstly, a single sorption experiment (10 endotoxin units/mL (EU/mL)) was performed. Polymyxin B and organoclays showed 100% binding efficiency. Secondly, the adsorption efficiency of sorbents in aqueous solution with increasing endotoxin concentrations (2,450 – 51,700 EU/mL) was investigated. Organoclay 1 (0.1%) showed a good binding efficiency in aqueous solution (average 81%), whereas Bentonite 1 (0.1%) obtained a lower binding efficiency (21-54%). The following absorbent capacities were calculated in highest endotoxin concentration: 5.59 mg/g (Organoclay 1) > 3.97 mg/g (Polymyxin B) > 2.58mg/g (Organoclay 2) > 1.55 mg/g (Bentonite 1) > 1.23 mg/g (Bentonite 2). Thirdly, a sorption experiment in artificial intestinal fluid was conducted. Especially for organoclays, which are known to be unspecific adsorbents, the endotoxin binding capacity was significantly reduced. In contrast, Bentonite 1 showed comparable results in artificial intestinal fluid and aqueous solution. Based on the results of this in vitro study, the effect of promising clay minerals will be investigated in in vivo trials. PMID:24383578

  17. Stable Isotope Systematics of Abiotic Nitrite Reduction Coupled with Anaerobic Iron Oxidation: The Role of Reduced Clays and Fe-bearing Minerals

    NASA Astrophysics Data System (ADS)

    Grabb, K. C.; Buchwald, C.; Hansel, C. M.; Wankel, S. D.

    2014-12-01

    Under anaerobic conditions, it is widely assumed that nitrate (NO3-) and nitrite (NO2-) reduction is primarily the result of microbial respiration. However, it has also been shown that abiotic reduction of nitrate and nitrite by reduced iron (Fe(II)), whether mineral-bound or surface-associated, may also occur under certain environmentally relevant conditions. With a range of experimental conditions, we investigated the nitrogen and oxygen stable isotope systematics of abiotic nitrite reduction by Fe(II) in an effort to characterize biotic and abiotic processes in the environment. While homogenous reactions between NO2- and Fe(II) in artificial seawater showed little reduction, heterogeneous reactions involving Fe-containing minerals showed considerable nitrite loss. Specifically, rapid nitrite reduction was observed in experiments that included reduced clays (illite, Na-montmorillonite, and nontronite) and those that exhibited iron oxide formation (ferrihydrite, magnetite and/or green rust). While these iron oxides and clay minerals offer both a source of reduced iron in the mineral matrix as well as a surface for Fe(II) activation, control experiments with corundum as a non-Fe containing mineral surface showed little NO2- loss, implicating a more dominant role of structural Fe in the clays during nitrite reduction. The isotope effects for 15N and 18O (15ɛ and 18ɛ) ranged from 5 to 14‰ for 15ɛ and 5 to 17‰ for 18ɛ and were typically coupled such that 15ɛ ~ 18ɛ. Reactions below pH 7 were slower and the 18ɛ was affected by oxygen atom exchange with water. Although little data exist for comparison with the dual isotopes of microbial NO2- reduction, these data serve as a benchmark for evaluating the role of abiotic processes in N reduction, particularly in sediment systems low in organic carbon and high in iron.

  18. [Effect of Cr (VI) anions on the Cu (II) adsorption behavior of two kinds of clay minerals in single and binary solution].

    PubMed

    Liu, Juan-Juan; Liang, Dong-Li; Wu, Xiao-Long; Qu, Guang-Zhou; Qian, Xun

    2014-01-01

    The adsorption of Cu (II) on kaolinite and montmorillonite was investigated through batch adsorption experiment. Several adsorption models were employed to describe the adsorption of Cu (II) on the two clay minerals in single Cu (II) and Cu(II)-Cr (VI) binary solutions, and the impact of solution with various pH values on the adsorption of Cu (II) on the two target mineral clays was investigated in order to explain the environmental chemical behavior of heavy metals in soil and to provide theoretical basis in remediation of multi-element contaminated soil. The results indicated that the adsorption process of Cu (II) on kaolinite and montmorillonite in both single and binary solutions was fast at the beginning and then slowed down. Adsorption equilibrium was observed within 120 min. In both single and binary solutions, pseudo-second-order model (R2 > 0.983) showed the highest agreement with the adsorption of Cu (II) on the two mineral clays, followed by the intra-particle diffusion model and pseudo-first-order model. Both Intra-particle diffusion model and Boyd model illustrated that the film diffusion process was the rate-limiting step, which mainly occurred at the edge and surface of mineral clays. Copper adsorption on kaolinite was well fitted with the Freundlich equation (R2 > 0.971), which could be attributed to the heterogeneity of kaolinite surface with adsorption sites that have different energies of adsorption. Langmuir equation was best fitted with the isotherm for montmorillonite (R2 > 0.983), which indicated that the adsorption was on a single molecular layer or chemisorptions. In both single and binary solutions, the adsorption of Cu (II ) on the two clay minerals first increased and then decreased with the rising of pH values. The maximum adsorption amount was found at pH = 5.0, and was in the order of Qmon. > Qkao. and Q(Single-Cu) > Q(Cu-Cr binary). Cr (VI) in the solution reduced the adsorption of Cu (II), and the minimal influence of Cr (VI) on Cu

  19. [Effect of Cr (VI) anions on the Cu (II) adsorption behavior of two kinds of clay minerals in single and binary solution].

    PubMed

    Liu, Juan-Juan; Liang, Dong-Li; Wu, Xiao-Long; Qu, Guang-Zhou; Qian, Xun

    2014-01-01

    The adsorption of Cu (II) on kaolinite and montmorillonite was investigated through batch adsorption experiment. Several adsorption models were employed to describe the adsorption of Cu (II) on the two clay minerals in single Cu (II) and Cu(II)-Cr (VI) binary solutions, and the impact of solution with various pH values on the adsorption of Cu (II) on the two target mineral clays was investigated in order to explain the environmental chemical behavior of heavy metals in soil and to provide theoretical basis in remediation of multi-element contaminated soil. The results indicated that the adsorption process of Cu (II) on kaolinite and montmorillonite in both single and binary solutions was fast at the beginning and then slowed down. Adsorption equilibrium was observed within 120 min. In both single and binary solutions, pseudo-second-order model (R2 > 0.983) showed the highest agreement with the adsorption of Cu (II) on the two mineral clays, followed by the intra-particle diffusion model and pseudo-first-order model. Both Intra-particle diffusion model and Boyd model illustrated that the film diffusion process was the rate-limiting step, which mainly occurred at the edge and surface of mineral clays. Copper adsorption on kaolinite was well fitted with the Freundlich equation (R2 > 0.971), which could be attributed to the heterogeneity of kaolinite surface with adsorption sites that have different energies of adsorption. Langmuir equation was best fitted with the isotherm for montmorillonite (R2 > 0.983), which indicated that the adsorption was on a single molecular layer or chemisorptions. In both single and binary solutions, the adsorption of Cu (II ) on the two clay minerals first increased and then decreased with the rising of pH values. The maximum adsorption amount was found at pH = 5.0, and was in the order of Qmon. > Qkao. and Q(Single-Cu) > Q(Cu-Cr binary). Cr (VI) in the solution reduced the adsorption of Cu (II), and the minimal influence of Cr (VI) on Cu

  20. Mineral catalysis of the formation of dimers of 5'-AMP in aqueous solution: The possible role of montmorillonite clays in the prebiotic synthesis of RNA

    NASA Astrophysics Data System (ADS)

    Ferris, James P.; Ertem, Gözen; Agarwal, Vipin

    1989-03-01

    The reaction of the 5'-AMP with water soluble carbodiimide (EDAC) in the presence of Na+-montmorillonite 22A results in the formation of 2',5'-(pA)2 (18.9%), 3',5'-(pA)2 (11%), and AppA (4.8%). When poly(U) is used in place of the clay the product yields are 2',5'-(pA)2 (15.5%), 3',5'-(pA)2 (3.7%) and AppA (14.9%). The 3',5'-cyclic dinucleotide, 3',5'-c(pA)2, is also formed when poly(U) is used. AppA is the principal reaction product when neither clay nor poly(U) is present in the reaction mixture. Products which contain the phophodiester bond are formed at different ionic strengths, pH and temperatures using Na+-montmorillonite. Phosphodiester bond formation was not observed when Cu2+-montmorillonite was used or when DISN was used in the place of EDAC. The extent catalysis of phophodiester bond formation varied with the particular clay mineral used. Those Na+-clays which bind 5'-AMP more strongly are better catalysts. Cu2+-montmorillonite, which binds 5'-AMP strongly, exhibits no catalytic activity.

  1. Diagenesis of clay minerals and K-bentonites in Late Permian/Early Triassic sediments of the Sichuan Basin (Chaotian section, Central China)

    NASA Astrophysics Data System (ADS)

    Deconinck, J. F.; Crasquin, S.; Bruneau, L.; Pellenard, P.; Baudin, F.; Feng, Q.

    2014-02-01

    Detailed clay mineralogical analyses were carried out on Late Permian/Early Triassic carbonate sediments exposed on the Chaotian section (Sichuan Basin, Central China). The clay assemblages are dominantly composed of illite in platform carbonates and clay seams, and illite-smectite mixed-layers (I/S) in tuff layers (K-bentonites) intercalated in the carbonate succession. Detrital and authigenic volcanogenic clay minerals have been partially replaced through illitisation processes during burial, raising questions about diagenetic effects. The precise determination of I/S occurring in K-bentonites shows that the sediments reached a temperature of about 180 °C, which is consistent with (1) previous estimates based on fluid-inclusion homogenisation temperature analysis, (2) the burial depth of the sedimentary series deduced from the post-Palaeozoic geological history of the Sichuan Basin and (3) the new data (Tmax) obtained on organic matter indicating the transition between oil and gas windows. The Wangpo Bed, located close to the Guadalupian-Lopingian Boundary, is interpreted either as a volcanic acidic tuff or as a clastic horizon. This controversial origin probably results from mixed volcanogenic and detrital influences. The Wangpo Bed is therefore interpreted as a reworked bentonite as revealed by the occurrence of I/S similar to those found in tuff layers, together with preserved detrital kaolinite.

  2. Biodegradation and adsorption of C1- and C2-phenanthrenes and C1- and C2-dibenzothiophenes in the presence of clay minerals: effect on forensic diagnostic ratios.

    PubMed

    Ugochukwu, Uzochukwu C; Head, Ian M; Manning, David A C

    2014-07-01

    The impact of modified montmorillonites on adsorption and biodegradation of crude oil C1-phenanthrenes, C1-dibenzothiophenes, C2-phenanthrenes and C2-dibenzothiophenes was investigated in aqueous clay/oil microcosm experiments with a hydrocarbon degrading microorganism community. Consequently, the effect on C1-dibenzothiophenes/C1-phenanthrenes, C2-dibenzothiophenes/C2-phenanthrenes, 2+3-methyldibenzothiophene/4-methyldibenzothiophene and 1-methyldibenzothiophene/4-methyldibenzothiophene ratios commonly used as diagnostic ratios for oil forensic studies was evaluated. The clay mineral samples were treated to produce acid activated montmorillonite, organomontmorillonite and homoionic montmorillonite which were used in this study. The different clay minerals (modified and unmodified) showed varied degrees of biodegradation and adsorption of the C1-phenanthrenes, C1-dibenzothiophenes, C2-phenanthrenes and C2-dibenzothiophenes. The study indicated that as opposed to biodegradation, adsorption has no effect on the diagnostic ratios. Among the diagnostic ratios reviewed, only C2-dibenzothiophenes/C2-phenanthrenes ratio was neither affected by adsorption nor biodegradation making this ratio very useful in forensic studies of oil spills and oil-oil correlation.

  3. An EXAFS study on the effects of natural organic matter and the expandability of clay minerals on cesium adsorption and mobility

    NASA Astrophysics Data System (ADS)

    Fan, Q. H.; Tanaka, M.; Tanaka, K.; Sakaguchi, A.; Takahashi, Y.

    2014-06-01

    The relationship between cesium (Cs) adsorption on clay minerals with various expandabilities and Cs mobility in environment was investigated using sequential extraction, batch adsorption, X-ray diffraction (XRD), generalized adsorption model (GAM), and Cs LIII-edge extended X-ray absorption fine structure (EXAFS) analyses with molecular simulations using the density functional theory (DFT). In particular, the difference between the affinities of illite (non-expansion) and vermiculite (intermediate expansion) for Cs and the effect of humic acid (HA) addition on the Cs/clay mineral system were highlighted in this study. These two factors affect Cs mobility and bioavailability in surface soil and sediments. The batch adsorption results showed that Cs adsorption was inhibited to some extent in the ternary clay + HA + Cs system because of (i) the blocked access of Cs to the frayed edge site (FES) and type II site [inner-sphere (IS) complex in GAM] by HA, and (ii) the reduced availability of the interlayer site in vermiculite. EXAFS analysis further confirmed that the adsorbed Cs in clay minerals was drastically changed by the sequential addition of HA. In addition, the dominant IS complex in the illite + Cs and illite + Cs + HA systems (in which HA was added after Cs adsorption on illite) can be converted to the outer-sphere (OS) complex largely in the illite + HA + Cs system (in which HA was added prior to Cs adsorption). These results are consistent with the sequential extraction and GAM results. The IS complex of dehydrated Cs+ mainly formed at the FES and interlayer site on illite (non-expansion) without resulting in any illite structural changes. However, on vermiculite (intermediate expansion), the dehydrated Cs+ can be adsorbed as an IS complex associated with the siloxane group of the di-trigonal cavity in the tetrahedral SiO4 sheet. This adsorption is accompanied by collapse of the layer, which can be easily coated by HA molecules to prevent Cs fixation

  4. Evidence of multi-stage faulting by clay mineral analysis: Example in a normal fault zone affecting arkosic sandstones (Annot sandstones)

    NASA Astrophysics Data System (ADS)

    Buatier, Martine D.; Cavailhes, Thibault; Charpentier, Delphine; Lerat, Jérémy; Sizun, Jean Pierre; Labaume, Pierre; Gout, Claude

    2015-06-01

    Fault affecting silicoclastic sediments are commonly enriched in clay minerals. Clays are sensitive to fluid-rock interactions and deformation mechanisms; in this paper, they are used as proxy for fault activity and behavior. The present study focuses on clay mineral assemblages from the Point Vert normal fault zone located in the Annot sandstones, a Priabonian-Rupelian turbidite succession of the Alpine foredeep in SE France. In this area, the Annot sandstones were buried around 6-8 km below the front of Alpine nappes soon after their deposition and exhumed during the middle-late Miocene. The fault affects arkosic sandstone beds alternating with pelitic layers, and displays throw of about thirty meters. The fault core zone comprises intensely foliated sandstones bounding a corridor of gouge about 20 cm thick. The foliated sandstones display clay concentration along S-C structures characterized by dissolution of K-feldspar and their replacement by mica, associated with quartz pressure solution, intense microfracturation and quartz vein precipitation. The gouge is formed by a clayey matrix containing fragments of foliated sandstones and pelites. However, a detailed petrographical investigation suggests complex polyphase deformation processes. Optical and SEM observations show that the clay minerals fraction of all studied rocks (pelites and sandstones from the damage and core zones of the fault) is dominated by white micas and chlorite. These minerals have two different origins: detrital and newly-formed. Detrital micas are identified by their larger shape and their chemical composition with a lower Fe-Mg content than the newly-formed white micas. In the foliated sandstones, newly-formed white micas are concentrated along S-C structures or replace K-feldspar. Both types of newly formed micas display the same chemical composition confirmed microstructural observations suggesting that they formed in the same conditions. They have the following structural formulas: Na0

  5. Colorimetric Humidity and Solvent Recognition Based on a Cation-Exchange Clay Mineral Incorporating Nickel(II)-Chelate Complexes.

    PubMed

    Hosokawa, Hitoshi; Mochida, Tomoyuki

    2015-12-01

    Solvatochromic nickel(II) complexes with diketonato and diamine ligands were incorporated into a saponite clay by ion exchange, and their colorimetric humidity- and solvent-recognition properties were investigated. These powders exhibit color change from red to blue-green depending on humidity, and the detection range can be controlled by modifying the metal complex. The humidity response takes advantage of the humidity-dependent water content in clay and the coordination of water molecules to the metal complex in equilibrium. The addition of organic solvents to the powders causes a color change to occur, varying from red to blue-green depending on the donor number of the solvent, thereby enabling solvent recognition. In the clay, the affinity of less sterically hindered complexes to water or solvent molecules is decreased compared with that in solution because the cationic complexes interact with the anionic layers in the clay. Incorporating diethylene glycol into the materials produced thermochromic powders.

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

    NASA Astrophysics Data System (ADS)

    Jun, Y.; Hu, Y.

    2011-12-01

    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

  7. 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)

    Terajima, Tomomi; Moriizumi, Mihoko; Nakamura, Tomohiro

    2010-05-01

    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 μm 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

  8. 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 ...

  9. Synthesis and structural characterization of ferrous trioctahedral smectites: Implications for clay mineral genesis and detectability on Mars

    NASA Astrophysics Data System (ADS)

    Chemtob, Steven M.; Nickerson, Ryan D.; Morris, Richard V.; Agresti, David G.; Catalano, Jeffrey G.

    2015-06-01

    Widespread detections of phyllosilicates in Noachian terrains on Mars imply a history of near-surface fluid-rock interaction. Ferrous trioctahedral smectites are thermodynamically predicted products of basalt weathering on early Mars, but to date only Fe3+-bearing dioctahedral smectites have been identified from orbital observations. In general, the physicochemical properties of ferrous smectites are poorly studied because they are susceptible to air oxidation. In this study, eight Fe2+-bearing smectites were synthesized from Fe2+-Mg-Al silicate gels at 200°C under anoxic conditions. Samples were characterized by inductively coupled plasma optical emission spectrometry, powder X-ray diffraction, Fe K-edge X-ray absorption spectroscopy (XAS), Mössbauer spectroscopy, and visible/near-infrared (VNIR) reflectance spectroscopy. The range of redox states was Fe3+/ΣFe = 0 to 0.06 ± 0.01 as determined by both XAS and, for short integration times, Mössbauer. The smectites have 060 distances (d(060)) between 1.53 and 1.56 Å, indicating a trioctahedral structure. d(060) and XAS-derived interatomic Fe-(Fe,Mg,Al) distance scaled with Fe content. Smectite VNIR spectra feature OH/H2O absorption bands at 1.4 and 1.9 µm, (Fe2+,Mg,Al)3-OH stretching bands near 1.4 µm, and Fe2+Fe2+Fe2+-OH, MgMgMg-OH, AlAl(Mg,Fe2+)-OH, and AlAl-OH combination bands at 2.36 µm, 2.32 µm 2.25 µm, and 2.20 µm, respectively. The spectra for ferrous saponites are distinct from those for dioctahedral ferric smectites, permitting their differentiation from orbital observations. X-ray diffraction patterns for synthetic high-Mg ferrosaponite and high-Mg ferrian saponite are both consistent with the Sheepbed saponite detected by the chemistry and mineralogy (CheMin) instrument at Gale Crater, Mars, suggesting that anoxic basalt alteration was a viable pathway for clay mineral formation on early Mars.

  10. Comparative 40Ar/39Ar and K-Ar dating of illite-type clay minerals: A tentative explanation for age identities and differences

    NASA Astrophysics Data System (ADS)

    Clauer, Norbert; Zwingmann, Horst; Liewig, Nicole; Wendling, Raymond

    2012-10-01

    The 40K/40Ar (K-Ar) and 40Ar/39Ar dating methods are applied here to the same, very small, micrometric illite-type particles that crystallized under low-temperature (< 175 °C) hydrothermal conditions in deeply buried Rotliegend (Permian) gas-bearing sandstones of NW Germany. Four samples with a total of fifteen size fractions from < 2 to 20-40 μm yield K-Ar ages that range from 166.0 ± 3.4 to 214.0 ± 5.9 Ma. The same size fractions dated by the 40Ar/39Ar method give total-gas ages ranging from 173.3 ± 2.0 to 228.8 ± 1.6 Ma. Nearly all 40Ar/39Ar total-gas ages are slightly older, which cannot be explained by the recoil effect only, the impact of which being amplified by the inhomogeneous shape of the clay minerals and their crystallographic characteristics, with varied crystallinity indices, and a particle width about 10 times large than thickness. The 40Ar/39Ar data outline some advantages, such as the plateaus obtained by incremental step heating of the various size fractions, even if not translatable straight as ages of the illite populations; they allow identification of two generations of authigenic illite that formed at about 200 and 175 Ma, and one detrital generation. However, 40Ar/39Ar dating of clay minerals remains challenging as technical factors, such as the non-standardized encapsulation, may have potential unexpected effects. Both dating methods have their limitations: (1) K-Ar dating requires relatively large samples (ca. 10-20 mg) incurring potential sample homogeneity problems, with two aliquots required for K and Ar analysis for an age determination, also inducing a higher analytical uncertainty; (2) an identified drawback of 40Ar/39Ar dating is Ar recoil and therefore potential loss that occurs during neutronic creation of 39Ar from 39K, mostly in the finer mineral particles. If all the recoiled 39Ar is redistributed into adjacent grains/minerals, the final 40Ar/39Ar age of the analyzed size fraction remains theoretically identical, but it

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

    NASA Astrophysics Data System (ADS)

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

    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 in the binding of uracil derivatives to the clay since the uracil ring system is not basic. The reaction of the 5'-AMP with water soluble carbodiimide in the presence of Na+-montmorillonite results in the formation of 2',5'-pApA (18.9%), 3',5'-pApA (11%), and AppA (4.8%). When poly(U) is used in place of the clay the product yields are 2',5',-pApA (15.5%), 3',5'-pApA (3.7%) and AppA (14.9%). The cyclic nucleotide, c(pA)2 is also formed when poly(U) is used. AppA is the principal reaction product when neither clay nor poly(U) is present in the reaction mixture. When 2'-deoxy-5'-AMP reacts with carbodiimide in the presence of Na+-montmorillonite 22A the products are dpApA (4.8%), dAppApA (4.5%) and dAppA (17.4%). Cyclic 3',5'-dAMP is the main product (14%) of the reaction of 2'-deoxy-3'-AMP.

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

    PubMed

    Ferris, J P; Ertem, G; Kamaluddin; Agarwal, V; Hua, L L

    1989-01-01

    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 in the binding of uracil derivatives to the clay since the uracil ring system is not basic. The reaction of the 5'-AMP with water soluble carbodiimide in the presence of Na(+)-montmorillonite results in the formation of 2',5'-pApA (18.9%), 3',5'-pApA (11%), and AppA (4.8%). When poly(U) is used in place of the clay the product yields are 2',5'-pApA (15.5%), 3',5'-pApA (3.7%) and AppA (14.9%). The cyclic nucleotide, c(pA)2 is also formed when poly(U) is used. AppA is the principal reaction product when neither clay nor poly(U) is present in the reaction mixture. When 2'-deoxy-5'-AMP reacts with carbodiimide in the presence of Na(+)-montmorillonite 22A the products are dpApA (4.8%), dAppApA (4.5%) and dAppA (17.4%). Cyclic 3',5'-dAMP is the main product (14%) of the reaction of 2'-deoxy-3'-AMP.

  13. Common clay and shale

    USGS Publications Warehouse

    Virta, R.L.

    2003-01-01

    Part of the 2002 industrial minerals review. The production, consumption, and price of shale and common clay in the U.S. during 2002 are discussed. The impact of EPA regulations on brick and structural clay product manufacturers is also outlined.

  14. Common clay and shale

    USGS Publications Warehouse

    Virta, R.L.

    2004-01-01

    Part of the 2003 industrial minerals review. The legislation, production, and consumption of common clay and shale are discussed. The average prices of the material and outlook for the market are provided.

  15. Mineral catalysis of the formation of the phosphodiester bond in aqueous solution - The possible role of montmorillonite clays

    NASA Technical Reports Server (NTRS)

    Ferris, James P.; Ertem, Gozen; KAMALUDDIN; Agarwal, Vipin; Hua, Lu Lin

    1989-01-01

    The possible role of montmorillonite clays in the spontaneous formation on the primitive earth of the phosphodiester bond in the presence of water was investigated in experiments measuring the binding of various nucleosides and nucleotides with Na(+)-montmorillonite 22A and the reactions of these compounds with a water-soluble carbodiimide. It was found that, at neutral pH, adenine derivatives bind stronger than the corresponding uracil derivatives, 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. The reaction of the 5-prime-AMP with carbodiimide resulted in the formation of 2-prime,5-prime-pApA (18.9 percent), 3-prime,5-prime-pApA (11 percent), and AppA (4.8 percent). The yields of these oligomers obtained when poly(U) was used in place of the clay were 15.5 percent, 3.7 percent, and 14.9 percent AppA, respectively.

  16. Biomass and habitability potential of clay minerals- and iron-rich environments: Testing novel analogs for Mars Science Laboratory landing sites candidates

    NASA Astrophysics Data System (ADS)

    Bonaccorsi, Rosalba; McKay, Christopher P.; Chen, Bin

    2010-06-01

    The landing site of the next mission to Mars (the US 2011 Mars Science Laboratory) will include phyllosilicate outcrops as targets for investigating the geological and biological history of the planet. In this context, we present a preliminary study assessing the living biomass and habitability potential in mineralogical Mars analogs by means of multi-component investigations (X-ray diffraction, microRaman spectroscopy and SEMEDX). Phyllosilicate and hematite-rich deposits from the Atacama Desert (Chile), Death Valley (CA), and the California Coast, encompassing a broad arid to hyper-arid climate range (annual rainfall <0.2 to ∼700 mm/year), were analyzed for total and viable Gram-negative biomass, i.e. adenosine 5‧-triphosphate (ATP) and Limulus amebocyte lysate (LAL) assays. Basic observations were: (1) there is no systematic pattern in biomass content of clay-rich versus non-clay (oxidized) materials; (2) Atacama desiccation polygons (6.0 × 104 cells/g) and contiguous hematite-rich deposits contain the lowest biomass (1.2 × 105 cells/g), which is even lower than that of coarse-grained soil nearby (3.3-5.0 × 105 cells/g); (3) the Atacama clay-rich samples (illite-muscovite and kaolinite) are three orders of magnitude lower than surface clay (montmorillonite, illite, and chlorite) from Death Valley; and (4) finally, and unexpectedly, the Gram-negative content (∼6.4 × 107 cells/g) of clay mineral-rich materials from the arid Death Valley region is up to six times higher than that (∼1.5 to ∼3.0 × 107 cells/g) of water-saturated massive clays (kaolinite, illite and montmorillonite) from the California Coast (wetter end-member). MicroRaman spectroscopy investigation on a Death Valley sample indicates that gypsum (1008, 618, and 414 cm-1 Raman shift), and inferred associated organic (scytonemin) biosignatures (1281 cm-1) for the measured Gram-negatives (cyanobacteria) were successfully captured.

  17. Structure, dynamics, and function of the hammerhead ribozyme in bulk water and at a clay mineral surface from replica exchange molecular dynamics.

    PubMed

    Swadling, Jacob B; Wright, David W; Suter, James L; Coveney, Peter V

    2015-03-01

    Compared with proteins, the relationship between structure, dynamics, and function of RNA enzymes (known as ribozymes) is far less well understood, despite the fact that ribozymes are found in many organisms and are often conceived as "molecular fossils" of the first self-replicating molecules to have arisen on Earth. To investigate how ribozymal function is governed by structure and dynamics, we study the full hammerhead ribozyme in bulk water and in an aqueous clay mineral environment by computer simulation using replica-exchange molecular dynamics. Through extensive sampling of the major conformational states of the hammerhead ribozyme, we are able to show that the hammerhead manifests a free-energy landscape reminiscent of that which is well known in proteins, exhibiting a "funnel" topology that guides the ribozyme into its globally most stable conformation. The active-site geometry is found to be closely correlated to the tertiary structure of the ribozyme, thereby reconciling conflicts between previously proposed mechanisms for the self-scission of the hammerhead. The conformational analysis also accounts for the differences reported experimentally in the catalytic activity of the hammerhead ribozyme, which is reduced when interacting with clay minerals as compared with bulk water.

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

    PubMed

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

    2013-10-01

    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.

  19. 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)

    Roters, B.

    2009-04-01

    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

  20. Common clay and shale

    USGS Publications Warehouse

    Virta, R.L.

    2000-01-01

    Part of the 1999 Industrial Minerals Review. The clay and shale market in 1999 is reviewed. In the U.S., sales or use of clay and shale increased from 26.4 million st in 1998 to 27.3 million st in 1999, with an estimated 1999 value of production of $143 million. These materials were used to produce structural clay products, lightweight aggregates, cement, and ceramics and refractories. Production statistics for clays and shales and for their uses in 1999 are presented.

  1. 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

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

    2003-01-01

    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.

  2. Detection of Soluble and Fixed NH4+ in Clay Minerals by DTA and IR Reflectance Spectroscopy : A Potential Tool for Planetary Surface Exploration

    NASA Technical Reports Server (NTRS)

    Janice, Bishop; Banin, A.; Mancinelli, R. L.; Klovstad, M. R.; DeVincenzi, Donald L. (Technical Monitor)

    2001-01-01

    Nitrogen is an essential element for life. It is the only element among the six major biogenic elements, C, O, S, O, P, H, whose presence in the Martian soil has not been positively and directly established. We describe here a study assessing the ability to detect NH4 in soils by two methods: differential thermal analysis (DTA) and infrared (IR) reflectance spectroscopy. Four standard clay minerals (kaolinite, montmorillonite, illite and attapulgite) and an altered tephra sample from Mauna Kea were treated with NH4 in this study. Samples of the NH4-treated and leached clays were analyzed by DTA and infrared (IR) reflectance spectroscopy to quantify the delectability of soluble and sorbed/fixed NH4. An exotherm at 270-280 C was clearly detected in the DTA curves of NH4-treated (non-leached) samples. This feature is assigned to the thermal decomposition reaction of NH4. Spectral bands observed at 1.56, 2.05, 2.12, 3.06, 3.3, 3.5, 5.7 and 7.0 microns in the reflectance spectra of NH4-treated and leached samples are assigned to the sorbed/fixed ammonium in the clays. The montmorillonite has shown the most intense absorbance due to fixed ammonium among the leached samples in this study, as a result of its high cation sorption capacity. It is concluded that the presence of sorbed or fixed NH4 in clays may be detected by infrared (IR) reflectance or emission spectroscopy. Distinction between soluble and sorbed NH4 may be achieved through the presence or absence of several spectral features assigned to the sorbed NH4 moietyi and, specifically, by use of the 4.2 micrometer feature assigned to solution NH4. Thermal analyses furnish supporting evidence of ammonia in our study through detection of N released at temperatures of 270-330 C. Based on these results it is estimated that IR spectra measured from a rover should be able to detect ammonia if present above 20 mg NH4/g sample in the surface layers. Orbital IR spectra and thermal analyses measured on a rover may be able to

  3. Ball clay

    USGS Publications Warehouse

    Virta, Robert L.

    2010-01-01

    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.

  4. Mycotoxins modify the barrier function of Caco-2 cells through differential gene expression of specific claudin isoforms: Protective effect of illite mineral clay.

    PubMed

    Romero, Alejandro; Ares, Irma; Ramos, Eva; Castellano, Víctor; Martínez, Marta; Martínez-Larrañaga, María-Rosa; Anadón, Arturo; Martínez, María-Aránzazu

    2016-04-15

    Aflatoxin B1 (AFB1), fumonisin B1 (FB1), ochratoxin A (OTA) and T-2 toxin (T2) are mycotoxins that commonly contaminate the food chain and cause various toxicological effects. Their global occurrence is regarded as an important risk factor for human and animal health. In this study, the results demonstrate that, in human Caco-2 cells, AFB1, FB1, OTA and T2 origin cytotoxic effects, determining cell viability through MTT assay and LDH leakage, and decrease trans-epithelial electrical resistance (TEER). The decrease in barrier properties is concomitant with a reduction in the expression levels of the tight junction constituents claudin-3, claudin-4 and occludin. The protective effect of mineral clays (diosmectite, montmorillonite and illite) on alterations in cell viability and epithelial barrier function induced by the mycotoxins was also evaluated. Illite was the best clay to prevent the mycotoxin effects. Illite plus mycotoxin co-treatment completely abolished AFB1 and FB1-induced cytotoxicity. Also, the decreases in the gene expression of claudins and the reduction of TEER induced by mycotoxins were reversed by the illite plus mycotoxin co-treatment. In conclusion, these results demonstrated that mycotoxins AFB1, FB1, T2 and OTA disrupt the intestinal barrier permeability by a mechanism involving reduction of claudin isoform expressions, and illite counteracts this disruption. PMID:27153755

  5. Mycotoxins modify the barrier function of Caco-2 cells through differential gene expression of specific claudin isoforms: Protective effect of illite mineral clay.

    PubMed

    Romero, Alejandro; Ares, Irma; Ramos, Eva; Castellano, Víctor; Martínez, Marta; Martínez-Larrañaga, María-Rosa; Anadón, Arturo; Martínez, María-Aránzazu

    2016-04-15

    Aflatoxin B1 (AFB1), fumonisin B1 (FB1), ochratoxin A (OTA) and T-2 toxin (T2) are mycotoxins that commonly contaminate the food chain and cause various toxicological effects. Their global occurrence is regarded as an important risk factor for human and animal health. In this study, the results demonstrate that, in human Caco-2 cells, AFB1, FB1, OTA and T2 origin cytotoxic effects, determining cell viability through MTT assay and LDH leakage, and decrease trans-epithelial electrical resistance (TEER). The decrease in barrier properties is concomitant with a reduction in the expression levels of the tight junction constituents claudin-3, claudin-4 and occludin. The protective effect of mineral clays (diosmectite, montmorillonite and illite) on alterations in cell viability and epithelial barrier function induced by the mycotoxins was also evaluated. Illite was the best clay to prevent the mycotoxin effects. Illite plus mycotoxin co-treatment completely abolished AFB1 and FB1-induced cytotoxicity. Also, the decreases in the gene expression of claudins and the reduction of TEER induced by mycotoxins were reversed by the illite plus mycotoxin co-treatment. In conclusion, these results demonstrated that mycotoxins AFB1, FB1, T2 and OTA disrupt the intestinal barrier permeability by a mechanism involving reduction of claudin isoform expressions, and illite counteracts this disruption.

  6. TEM/AEM characterization of fine-grained clay minerals in very-low-grade rocks: Evaluation of contamination by EMPA involving celadonite family minerals

    SciTech Connect

    Li, Gejing; Peacor, D.R.; Coombs, D.S.; Kawachi, Y.

    1996-12-31

    Recent advances in transmission electron microscopy (TEM) and analytical electron microscopy (AEM) have led to many new insights into the structural and chemical characteristics of very fine-grained, optically homogeneous mineral aggregates in sedimentary and very low-grade metamorphic rocks. Chemical compositions obtained by electron microprobe analysis (EMPA) on such materials have been shown by TEM/AEM to result from beam overlap on contaminant phases on a scale below resolution of EMPA, which in turn can lead to errors in interpretation and determination of formation conditions. Here we present an in-depth analysis of the relation between AEM and EMPA data, which leads also to the definition of new mineral phases, and demonstrate the resolution power of AEM relative to EMPA in investigations of very fine-grained mineral aggregates in sedimentary and very low-grade metamorphic rocks.

  7. Comparison of the sorption behaviors and mechanisms of perfluorosulfonates and perfluorocarboxylic acids on three kinds of clay minerals.

    PubMed

    Zhao, Lixia; Bian, Jingna; Zhang, Yahui; Zhu, Lingyan; Liu, Zhengtao

    2014-11-01

    The sorption of four perfluoroalkyl acids (PFAAs) [perfluorooctane sulfonate (PFOS), perfluorohexane sulfonate (PFHxS), perfluorooctanoic acid (PFOA) and perfluorohexanoic acid (PFHxA)] on three typical minerals [montmorillonite (MM), kaolinite (KL) and hematite (HM)] was studied. The sorption of PFOS and PFHxS was much stronger than PFOA and PFHxA. The sorption of each PFAA on the minerals followed an order of HM>KL>MM, even though MM was positively while KL and HM were negatively charged, implying that the sorption is driven by some other interactions besides electrostatic attraction. The sorption decreased with an increase in pH and a decrease in ionic strength of the solution, and their impacts on PFOS were much stronger than other three PFAAs. Surface complexing and hydrogen-bonding could make great contributions to the sorption of PFOS on the minerals. The results are important for understanding the transport and fate of PFAAs in sediment and ground water. PMID:25113183

  8. Comparison of the sorption behaviors and mechanisms of perfluorosulfonates and perfluorocarboxylic acids on three kinds of clay minerals.

    PubMed

    Zhao, Lixia; Bian, Jingna; Zhang, Yahui; Zhu, Lingyan; Liu, Zhengtao

    2014-11-01

    The sorption of four perfluoroalkyl acids (PFAAs) [perfluorooctane sulfonate (PFOS), perfluorohexane sulfonate (PFHxS), perfluorooctanoic acid (PFOA) and perfluorohexanoic acid (PFHxA)] on three typical minerals [montmorillonite (MM), kaolinite (KL) and hematite (HM)] was studied. The sorption of PFOS and PFHxS was much stronger than PFOA and PFHxA. The sorption of each PFAA on the minerals followed an order of HM>KL>MM, even though MM was positively while KL and HM were negatively charged, implying that the sorption is driven by some other interactions besides electrostatic attraction. The sorption decreased with an increase in pH and a decrease in ionic strength of the solution, and their impacts on PFOS were much stronger than other three PFAAs. Surface complexing and hydrogen-bonding could make great contributions to the sorption of PFOS on the minerals. The results are important for understanding the transport and fate of PFAAs in sediment and ground water.

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

    NASA Astrophysics Data System (ADS)

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

    2007-09-01

    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 Ma

  10. Infrared spectroscopic studies of the effect of elevated temperature on the association of pyroglutamic acid with clay and other minerals

    NASA Technical Reports Server (NTRS)

    Macklin, J. W.; White, D. H.

    1985-01-01

    Fourier transform i.r. measurements of L-pyroglutamic acid dispersed in a matrix of a clay, silica or alumina have been obtained at various temperatures between 25 and 220 degrees C. The i.r. spectrum of L-pyroglutamic acid varies in a manner dependent upon the matrix material and shows considerable change as the temperature of the mixtures is increased. The differences in the spectrum at elevated temperatures are explained in terms of a chemical reaction between hydroxyl groups in the matrix and the carboxylic acid. The i.r. spectra of trimethylsilyl derivatives of L-pyroglutamic acid and aluminum pyroglutamate were also measured to assist the understanding of spectra and interpretation of the spectral changes dependent upon increasing temperature.

  11. 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)

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

    2003-04-01

    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

  12. Assemblage characteristics of clay minerals and its implications to evolution of eolian dust input to the Parece Vela Basin since 1.95 Ma

    NASA Astrophysics Data System (ADS)

    Ming, Jie; Li, Anchun; Huang, Jie; Wan, Shiming; Meng, Qingyong; Jiang, Fuqing; Yan, Wenwen

    2014-01-01

    To understand the provenance and evolution of eolian input in the last 1.95 Ma in the Parece Vela Basin in the eastern Philippine Sea, the clay mineral assemblage of a gravity core PV090510 from the basin was investigated using paleogeomagnetic dating and X-ray diffraction. The assemblage of the core mainly consisted of smectite (˜46%) and illite (˜40%), with some chlorite (˜10%) and kaolinite (˜4%). Analysis of the provenance of these minerals suggested that smectite was mainly derived from volcanic rocks of the Mariana Arc, while illite, chlorite, and kaolinite were mainly transported as eolian dust by the East Asian monsoon from central Asia. We used the ratio of (illite+chlorite+kaolinite)/smectite as a proxy for Asian eolian input to the Parece Vela Basin since 1.95 Ma. This ratio followed glacial and interglacial cycles and was consistent with the intensity of the East Asian monsoon and aridity of central Asia since 1.95 Ma. The changes of the ratio reflected three different stages of the East Asian monsoon and provenance climate.

  13. Clay Play

    ERIC Educational Resources Information Center

    Rogers, Liz; Steffan, Dana

    2009-01-01

    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…

  14. Clays as prebiotic photocatalysts

    NASA Technical Reports Server (NTRS)

    Coyne, L. M.; Lawless, J.; Lahav, N.; Sutton, S.; Sweeney, M.

    1981-01-01

    Clay minerals catalyze peptide bond formation in fluctuating environments. A number of plausible mechanisms have been proposed and tested. The possibility that clays may actually be energizing the reaction by means of electronic excitation, creating mobile or trapped holes and electrons in the lattice, is explored. It has been discovered that clays emit light upon dehydration. The correlation between dehydration-induced, or thermoluminescent, processes and the yield of glycine oligomers after treatments known to affect the luminescent yields is being tested, in an effort to understand the catalytic mechanism

  15. Intercalated clay catalysts

    SciTech Connect

    Pinnavaia, T.J.

    1983-04-22

    Recent advances in the intercalation of metal complex cations in smectite clay minerals are leading to the development of new classes of selective heterogeneous catalysts. The selectivity of both metal-catalyzed and proton-catalyzed chemical conversions in clay intercalates can often be regulated by controlling surface chemical equilibria, interlamellar swelling, or reactant pair proximity in the interlayer regions. Also, the intercalation of polynuclear hydroxy metal cations and metal cluster cations in smectites affords new pillared clay catalysts with pore sizes that can be made larger than those of conventional zeolite catalysts.

  16. Intercalated Clay Catalysts

    NASA Astrophysics Data System (ADS)

    Pinnavaia, Thomas J.

    1983-04-01

    Recent advances in the intercalation of metal complex cations in smectite clay minerals are leading to the development of new classes of selective heterogeneous catalysts. The selectivity of both metal-catalyzed and proton-catalyzed chemical conversions in clay intercalates can often be regulated by controlling surface chemical equilibria, interlamellar swelling, or reactant pair proximity in the interlayer regions. Also, the intercalation of polynuclear hydroxy metal cations and metal cluster cations in smectites affords new pillared clay catalysts with pore sizes that can be made larger than those of conventional zeolite catalysts.

  17. Ball clay

    USGS Publications Warehouse

    Virta, R.L.

    2011-01-01

    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.

  18. Early diagenesis and clay mineral adsorption as driving factors of metal pollution in sediments: the case of Aveiro Lagoon (Portugal).

    PubMed

    Martins, Maria Virgínia Alves; Mane, Miguel Ângelo; Frontalini, Fabrizio; Santos, José Francisco; da Silva, Frederico Sobrinho; Terroso, Denise; Miranda, Paulo; Figueira, Rubens; Laut, Lazaro Luiz Mattos; Bernardes, Cristina; Filho, João Graciano Mendonça; Coccioni, Rodolfo; Dias, João M Alveirinho; Rocha, Fernando

    2015-07-01

    This work aims to define the factors driving the accumulation of metals in the sediment of the lagoon of Aveiro (Portugal). The role of initial diagenetic processes in controlling trace metal retention in surface sediment is traced by mineralogy, magnetic susceptibility and geochemical analyses. Although several studies have focused on the metal distribution in this polihaline and anthropized coastal lagoon, most of them have been solely focused on the total metal concentrations. This study instead represents the first attempt to evaluate in a vast area of the Aveiro Lagoon the role of biogeochemical processes in metal availability and distribution in three extracted phases: exchangeable cations adsorbed by clay and elements co-precipitated with carbonates (S1), organic matter (S2) and amorphous Mn hydroxides (S3). According to the sediment guideline values, the sediment is polluted by, for instance, As and Hg in the inner area of the Murtosa Channel, Pb in the Espinheiro Channel, Aveiro City canals and Aveiro Harbour, and Zn in the northern area of the Ovar Channel. These sites are located near the source areas of pollutants and have the highest total available concentrations in each extracted phase. The total available concentrations of all toxic metals are however associated, firstly, with the production of amorphous Mn hydroxides in most of the areas and, secondly, with adsorption by organic compounds. The interplay of the different processes implies that not all of the sites near pollution sources have polluted surface sediment. The accumulation of metals depends on not only the pollution source but also the changing in the redox state of the sediments that may cause alterations in the sediment retention or releasing of redox-sensitive metals. Results of this work suggest that the biogeochemical processes may play a significant role in the increase of the pollutants in the sediment of the Aveiro Lagoon.

  19. Sea-level and provenance controlled clay mineral assemblage since the last 19 ka in the southern South China Sea: records of Core MD05-2894 off the Sunda Shelf

    NASA Astrophysics Data System (ADS)

    Wang, H.; Liu, Z.; Colin, C.; Sathiamurthy, E.; Hantoro, W. S.; Zhao, Y.

    2010-12-01

    High-resolution clay mineral assemblage at Core MD05-2894 (7°2.25'N, 111°33.11'E, water depth 1982 m) in the southern South China Sea is used to investigate the provenance and transport process of fine-grained sediments since the last 19 ka. In order to perform the source analysis, clay minerals in surface sediments of various potential source areas are also analyzed, including the Mekong River, Malay Peninsula, Sumatra, Borneo, and the Sunda Shelf. Clay mineralogical results at Core MD05-2894 indicate the sea level rise as the principal factor to drive provenance changes. During the late glacial stage, the Sunda Shelf was exposed. High values of smectite (average 32%) and kaolinite (27%) at the core suggest a large contribution of fine-grained sediments transported by the potential Sunda paleo-drainage system from Malaysia Peninsula and Sumatra, where kaolinite and smectite are rich. During the deglaciation when the sea level rises, illite and chlorite contents increased with a similar pattern, whereas kaolinite and smectite contents decreased, suggesting more sediment contribution from the Mekong River and Northwest Borneo. During the Holocene, variations in four clay mineral contents keep relatively stable with more illite and chlorite contents than those of the deglaciation and last glacial stage, indicating a mixture of various provenances.

  20. Impact of clay mineral, wood sawdust or root organic matter on the bacterial and fungal community structures in two aged PAH-contaminated soils.

    PubMed

    Cébron, Aurélie; Beguiristain, Thierry; Bongoua-Devisme, Jeanne; Denonfoux, Jérémie; Faure, Pierre; Lorgeoux, Catherine; Ouvrard, Stéphanie; Parisot, Nicolas; Peyret, Pierre; Leyval, Corinne

    2015-09-01

    The high organic pollutant concentration of aged polycyclic aromatic hydrocarbon (PAH)-contaminated wasteland soils is highly recalcitrant to biodegradation due to its very low bioavailability. In such soils, the microbial community is well adapted to the pollution, but the microbial activity is limited by nutrient availability. Management strategies could be applied to modify the soil microbial functioning as well as the PAH contamination through various amendment types. The impact of amendment with clay minerals (montmorillonite), wood sawdust and organic matter plant roots on microbial community structure was investigated on two aged PAH-contaminated soils both in laboratory and 1-year on-site pot experiments. Total PAH content (sum of 16 PAHs of the US-EPA list) and polar polycyclic aromatic compounds (pPAC) were monitored as well as the available PAH fraction using the Tenax method. The bacterial and fungal community structures were monitored using fingerprinting thermal gradient gel electrophoresis (TTGE) method. The abundance of bacteria (16S rRNA genes), fungi (18S rRNA genes) and PAH degraders (PAH-ring hydroxylating dioxygenase and catechol dioxygenase genes) was followed through qPCR assays. Although the treatments did not modify the total and available PAH content, the microbial community density, structure and the PAH degradation potential changed when fresh organic matter was provided as sawdust and under rhizosphere influence, while the clay mineral only increased the percentage of catechol-1,2-dioxygenase genes. The abundance of bacteria and fungi and the percentage of fungi relative to bacteria were enhanced in soil samples supplemented with wood sawdust and in the plant rhizospheric soils. Two distinct fungal populations developed in the two soils supplemented with sawdust, i.e. fungi related to Chaetomium and Neurospora genera and Brachyconidiellopsis and Pseudallescheria genera, in H and NM soils respectively. Wood sawdust amendment favoured the

  1. Sorption of N2 and EGME vapors on some soils, clays, and mineral oxides and determination of sample surface areas by use of sorption data

    USGS Publications Warehouse

    Chiou, C.T.; Rutherford, D.W.; Manes, M.

    1993-01-01

    Vapor sorption isotherms of ethylene glycol monoethyl ether (EGME) at room temperature and isotherms of N2 gas at liquid nitrogen temperature were determined for various soils and minerals. The N2 monolayer capacities [Qm (N2)] were calculated from the BET equation and used to determine the surface areas. To examine whether EGME is an appropriate adsorbate for determination of surface areas, the apparent EGME monolayer capacities [Qm (EGME)ap] were also obtained by use of the BET equation. For sand, aluminum oxide, kaolinite, hematite, and synthetic hydrous iron oxide, which are relatively free of organic impurity and expanding/solvating minerals, the Qm (EGME)ap values are in good conformity with the corresponding Qm (N2) values and would give surface areas consistent with BET (N2) values. For other samples (Woodburn soil, a natural hydrous iron oxide, illite, and montmorillonite), the Qm (EGME)ap values overestimate the Qm (N2) values from a moderate to a large extent, depending on the sample. A high-organic-content peat shows a very small BET (N2) surface area; the EGME/ peat isotherm is linear and does not yield a calculation of the surface area. Large discrepancies between results of the two methods for some samples are attributed to the high solubility of polar EGME in soil organic matter and/ or to the cation solvation of EGME with solvating clays. The agreement for other samples is illustrative of the consistency of the BET method when different adsorbates are used, so long as they do not exhibit bulk penetration and/or cation solvation. ?? 1993 American Chemical Society.

  2. Comparing the activity of aluminum in two B horizons developed from volcanic ash deposits in Japan, dominated by short-range ordered aluminosilicates and crystalline clay minerals, respectively

    NASA Astrophysics Data System (ADS)

    Yagasaki, Yasumi; Mulder, Jan; Okazaki, Masanori

    2006-01-01

    Mechanisms controlling the activity of free aluminum (Al) in Bw1 horizons of soils developed from volcanic ash deposits in Japan were investigated by means of acid-base titrations and kinetic studies. In a Bw1 horizon, with a high content of acid-oxalate extractable Al, soil solution reached equilibrium with short-range ordered aluminosilicates in the order of days. Relatively fast kinetics of the release and precipitation of Al and Si indicate a high reactivity of short-range ordered aluminosilicates in the soil. In the Bw1 horizon of an adjacent soil, with a high content of crystalline clay minerals like halloysite and interlayered vermiculite, solution remained well undersaturated with respect to short-range ordered aluminosilicates and aluminum hydroxide. Apparent equilibrium with respect to halloysite occurred after more than 30 days. This halloysite ( logKso0=3.74±0.02 (25 °C)) has a solubility that is less than that reported in the literature ( logKso0=4.36 (25°C)). Our findings suggest that different reactive aluminosilicates may control the activity of free Al in sub-surface horizons of volcanic ash soils with different mineralogy.

  3. Impact of medicated feed along with clay mineral supplementation on Escherichia coli resistance to antimicrobial agents in pigs after weaning in field conditions.

    PubMed

    Jahanbakhsh, Seyedehameneh; Kabore, Kiswendsida Paul; Fravalo, Philippe; Letellier, Ann; Fairbrother, John Morris

    2015-10-01

    The aim of this study was to examine changes in antimicrobial resistance (AMR) phenotype and virulence and AMR gene profiles in Escherichia coli from pigs receiving in-feed antimicrobial medication following weaning and the effect of feed supplementation with a clay mineral, clinoptilolite, on this dynamic. Eighty E. coli strains isolated from fecal samples of pigs receiving a diet containing chlortetracycline and penicillin, with or without 2% clinoptilolite, were examined for antimicrobial resistance to 15 antimicrobial agents. Overall, an increased resistance to 10 antimicrobials was observed with time. Supplementation with clinoptilolite was associated with an early increase but later decrease in blaCMY-2, in isolates, as shown by DNA probe. Concurrently, a later increase in the frequency of blaCMY-2 and the virulence genes iucD and tsh was observed in the control pig isolates, being significantly greater than in the supplemented pigs at day 28. Our results suggest that, in the long term, supplementation with clinoptilolite could decrease the prevalence of E. coli carrying certain antimicrobial resistance and virulence genes.

  4. Ball clay

    USGS Publications Warehouse

    Virta, R.L.

    2013-01-01

    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.

  5. Fire clay

    USGS Publications Warehouse

    Virta, R.L.

    2011-01-01

    The article discusses the latest developments in the fire clay industry, particularly in the U.S., as of June 2011. It claims that the leading fire clay producer in the U.S. is the state of Missouri. The other major producers include California, Texas and Washington. It reports that the use of heavy clay products made of fire clay like brick, cement and lightweight aggregate has increased slightly in 2010.

  6. Clay Houses

    ERIC Educational Resources Information Center

    Pedro, Cathy

    2011-01-01

    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.

  7. Common clay and shale

    USGS Publications Warehouse

    Virta, R.L.

    2001-01-01

    Part of the 2000 annual review of the industrial minerals sector. A general overview of the common clay and shale industry is provided. In 2000, U.S. production increased by 5 percent, while sales or use declined to 23.6 Mt. Despite the slowdown in the economy, no major changes are expected for the market.

  8. Fire clay

    USGS Publications Warehouse

    Virta, R.L.

    2013-01-01

    Four companies mined fire clay in three states in 2012. Production, based on a preliminary survey of the fire clay industry, was estimated to be 230 kt (254,000 st) valued at $6.98 million, an increase from 215 kt (237,000 st) valued at $6.15 million in 2011. Missouri was the leading producing state, followed by Colorado and Texas, in decreasing order by quantity. The number of companies mining fire clay declined in 2012 because several common clay producers that occasionally mine fire clay indicated that they did not do so in 2012.

  9. Iodide uptake by negatively charged clay interlayers?

    PubMed

    Miller, Andrew; Kruichak, Jessica; Mills, Melissa; Wang, Yifeng

    2015-09-01

    Understanding iodide interactions with clay minerals is critical to quantifying risk associated with nuclear waste disposal. Current thought assumes that iodide does not interact directly with clay minerals due to electrical repulsion between the iodide and the negatively charged clay layers. However, a growing body of work indicates a weak interaction between iodide and clays. The goal of this contribution is to report a conceptual model for iodide interaction with clays by considering clay mineral structures and emergent behaviors of chemical species in confined spaces. To approach the problem, a suite of clay minerals was used with varying degrees of isomorphic substitution, chemical composition, and mineral structure. Iodide uptake experiments were completed with each of these minerals in a range of swamping electrolyte identities (NaCl, NaBr, KCl) and concentrations. Iodide uptake behaviors form distinct trends with cation exchange capacity and mineral structure. These trends change substantially with electrolyte composition and concentration, but do not appear to be affected by solution pH. The experimental results suggest that iodide may directly interact with clays by forming ion-pairs (e.g., NaI(aq)) which may concentrate within the interlayer space as well as the thin areas surrounding the clay particle where water behavior is more structured relative to bulk water. Ion pairing and iodide concentration in these zones is probably driven by the reduced dielectric constant of water in confined space and by the relatively high polarizability of the iodide species.

  10. Deglacial Record in the Illinois River Valley Explains Asynchronous Phases of Meltwater Pulses and Clay Mineral Excursions in the Gulf of Mexico

    NASA Astrophysics Data System (ADS)

    Wang, H.

    2014-12-01

    One prominent event of the Bølling/Allerød (B/A) interstadial was the large meltwater release to global oceans. The Laurentide Ice Sheet (LIS) is usually considered the main source. But, the large LIS meltwater discharge conflicts with the marine record showing an active North Atlantic meridional overturning circulation (AMOC) during the B/A interval. Continuous dune-lacustrine successions in the Illinois River Valley (IRV) have shown complete records of the last deglacial chronozones. Their grain-size distributions and accurate B/A age 14C dates of plant fossils from 15 m deep lacustrine sediment in the IRV suggest that most of the IRV and parts of the adjacent upland were inundated by water. The inundation was caused by a sediment dam interpreted to have been constructed and followed by a breach at the confluence of the Mississippi and Illinois Rivers during the B/A interval due to sediment mobilization by the large meltwater release. The grain size distributions correlate with meltwater pulses and mineralogical excursions in sediments from the Gulf of Mexico (GOM) very well. The blockage and release of illite and chlorite rich fine-grained sediments from the Lake Michigan basin changed the relative abundance of clay minerals and thus the ratio of smectite/(illite + chlorite) in the sediment of the GOM. This finding explains why the meltwater episodes from the LIS and the associated detrital discharges are not synchronous in the sediments in the GOM. The finding also ties meltwater pulses and associated detrital discharges in the GOM closely to the LIS discharges via the Mississippi River Valley on chronozonal scales. Three arguments can be made from this result: 1) unaffected AMOC during B/A interval resulted potentially from the hyperpycnal inflow into the GOM floor; 2) limited volume of the meltwater discharge did not significantly influence the AMOC; and 3) the freshwater input into the GOM from the LIS at this particular location did not significantly

  11. Fire clay

    USGS Publications Warehouse

    Virta, R.L.

    2012-01-01

    Five companies mined fire clay in four states in 2011. Production, based on a preliminary survey of the fire clay industry, was estimated to be 240 kt (265,000 st), valued at $7.68 million, an increase from 216 kt (238,000 st), valued at $6.12 million in 2010. Missouri was the leading producing state, followed by Texas, Washington and Ohio, in decreasing order by quantity.

  12. MSL at Gale Crater: What do the clays tell?

    NASA Astrophysics Data System (ADS)

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

    2011-12-01

    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.

  13. Chemical disaggregation of kaolinitic claystones (tonsteins and flint clays)

    USGS Publications Warehouse

    Triplehorn, D.M.; Bohor, B.F.; Betterton, W.J.

    2002-01-01

    The coarse, non-clay fraction of many flint-like kaolinitic claystones often contains mineral grains diagnostic of the claystone's origin and, in the case of tonsteins (altered volcanic ashes), may also provide minerals suitable for radiometric dating. Separation of the non-clay mineral fraction is often difficult because flint clays and flint-like clays resist slaking in water and thus are difficult to disaggregate. Chemical disaggregation of resistant kaolinitic claystones may be achieved by immersion in either hydrazine monohydrate or DMSO for periods ranging from one day to several weeks. Generally, hydrazine monohydrate works more quickly and efficiently than DMSO to disaggregate most kaolinitic claystones and flint clays.

  14. Ball clay

    USGS Publications Warehouse

    Virta, R.L.

    2012-01-01

    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.

  15. 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)

    Okumura, Masahiko; Nakamura, Hiroki; Machida, Masahiko

    2013-03-01

    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.

  16. CLAY MINERALOGY OF INSOLUBLE RESIDUES IN MARINE EVAPORITES.

    USGS Publications Warehouse

    Bodine, Marc W.

    1985-01-01

    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.

  17. The colloidal chemistry of ceramic clays

    NASA Technical Reports Server (NTRS)

    Phelps, G. W.

    1984-01-01

    The colloidal chemistry and mineralogy of two argil minerals were studied. Deposits of kaolin and of ceramic clays in the United States and England are discussed for the probable mechanism of formation. The structural modifications of the bed, original material associated with the clays and the proper use of flocculants are discussed.

  18. Clay at Nili Fossae

    NASA Technical Reports Server (NTRS)

    2006-01-01

    This image of the Nili Fossae region of Mars was compiled from separate images taken by the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) and the High-Resolution Imaging Science Experiment (HiRISE), two instruments on NASA's Mars Reconnaissance Orbiter. The images were taken at 0730 UTC (2:30 a.m. EDT) on Oct. 4, 2006, near 20.4 degrees north latitude, 78.5 degrees east longitude. CRISM's image was taken in 544 colors covering 0.36 to 3.92 micrometers, and shows features as small as 18 meters (60 feet) across. HiRISE's image was taken in three colors, but its much higher resolution shows features as small as 30 centimeters (1 foot) across.

    CRISM's sister instrument on the Mars Express spacecraft, OMEGA, discovered that some of the most ancient regions of Mars are rich in clay minerals, formed when water altered the planet's volcanic rocks. From the OMEGA data it was unclear whether the clays formed at the surface during Mars' earliest history of if they formed at depth and were later exposed by impact craters or erosion of the overlying rocks. Clays are an indicator of wet, benign environments possibly suitable for biological processes, making Nili Fossae and comparable regions important targets for both CRISM and HiRISE.

    In this visualization of the combined data from the two instruments, the CRISM data were used to calculate the strengths of spectral absorption bands due to minerals present in the scene. The two major minerals detected by the instrument are olivine, a mineral characteristic of primitive igneous rocks, and clay. Areas rich in olivine are shown in red, and minerals rich in clay are shown in green. The derived colors were then overlayed on the HiRISE image.

    The area where the CRISM and HiRISE data overlap is shown at the upper left, and is about 5 kilometers (3 miles) across. The three boxes outlined in blue are enlarged to show how the different minerals in the scene match up with different landforms. In the image

  19. Clay energetics in chemical evolution

    NASA Technical Reports Server (NTRS)

    Coyne, L. M.

    1986-01-01

    Clays have been implicated in the origin of terrestrial life since the 1950's. Originally they were considered agents which aid in selecting, concentrating and promoting oligomerization of the organic monomeric substituents of cellular life forms. However, more recently, it has been suggested that minerals, with particular emphasis on clays, may have played a yet more fundamental role. It has been suggested that clays are prototypic life forms in themselves and that they served as a template which directed the self-assembly of cellular life. If the clay-life theory is to have other than conceptual credibility, clays must be shown by experiment to execute the operations of cellular life, not only individually, but also in a sufficiently concerted manner as to produce some semblance of the functional attributes of living cells. Current studies are focussed on the ability of clays to absorb, store and transfer energy under plausible prebiotic conditions and to use this energy to drive chemistry of prebiotic relevance. Conclusions of the work are applicable to the role of clays either as substrates for organic chemistry, or in fueling their own life-mimetic processes.

  20. Clay for Little Fingers.

    ERIC Educational Resources Information Center

    Koster, Joan Bouza

    1999-01-01

    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…

  1. Clay mineral provinces in tidal mud flats at Germany's North Sea coast with illite K-Ar ages potentially modified by biodegradation

    NASA Astrophysics Data System (ADS)

    Brockamp, Olaf; Clauer, Norbert

    2012-07-01

    Mineralogical studies, chemical analyses and K-Ar dating were carried out on clay fractions from tidal mud flats along the Lower Saxony coast and its bays to identify material sources and sedimentary processes at this dynamic interface between air, land and sea. From the coast into the bays, sediments are enriched in fine-grained smectite relative to the coarser grained illite, chlorite and kaolinite, due to the weakening of the tidal current energy in the bays. In addition, the study area can be divided into two provinces on the basis of the illite K/Rb ratios and Mg contents. To the west [Schiermonnikoog, Dollart, Ley Bay up to Norderney island], longshore currents carry suspensions from the Belgian and Dutch coasts; to the east [from Langeoog island, Jade Bay to the Helgoland mud area] suspensions from the Elbe and Weser rivers are mixed with submarine reworked glacial sediments, whereas the portion of longshore current suspensions from the west decreases, becoming negligible in the Helgoland mud area off the Elbe and Weser estuaries. The illite K-Ar data vary considerably and fail as source indicators due to differential settling and mixing of the clay material and probably to Ar loss from illite by biodegradation during digestive processes. Only further offshore, outside the zone of dynamic sediment dispersion, do the K-Ar data fit provenance patterns.

  2. Fire clay

    USGS Publications Warehouse

    Virta, R.L.

    2004-01-01

    Seven companies mined fire clay in four states during 2003. From 1984 to 1992, production declined to 383 kt (422,000 st) from a high of 1.04 Mt (1.14 million st) as markets for clay-based refractories declined. Since 1992, production levels have been erratic, ranging from 383 kt (422,000 st) in 1992 and 2001 to 583 kt (642,000 st) in 1995. Production in 2003, based on preliminary data, was estimated to be around 450 kt (496,000 st) with a value of about $10.5 million. This was about the same as in 2002. Missouri remained the leading producer state, followed by South Carolina, Ohio and California.

  3. Effects of clay minerals and organic matter in formulated sediments on the bioavailability of sediment-associated uranium to the freshwater midge, Chironomus dilutus.

    PubMed

    Crawford, Sarah E; Liber, Karsten

    2015-11-01

    It is well established that bioavailability influences metal toxicity in aquatic ecosystems. However, the factors and mechanisms that influence uranium (U) bioavailability and toxicity in sediment have not been thoroughly evaluated, despite evidence that suggests different sediment components can influence the sorption and interaction of some metals. Given that dissolved U is generally accepted as being the primary bioavailable fraction of U, it is hypothesized that adsorption and interaction of U with different sediment components will influence the bioavailability of U in sediment. We investigated the effects of key sediment physicochemical properties on the bioavailability of U to a model freshwater benthic invertebrate, Chironomus dilutus. Several 10-day spiked sediment bioaccumulation experiments were performed, exposing C. dilutus larvae to a variety of formulated sediments spiked with different concentrations of U (5, 50 and/or 200 mg U/kg d.w.). Mean accumulation of U in C. dilutus larvae decreased significantly from 1195 to 10 mg U/kg d.w. as kaolin clay content increased from 0% to 60% in sediment spiked with 50 mg U/kg d.w. Similarly, higher organic matter content also resulted in a significant reduction of U bioaccumulation in C. dilutus larvae, indicating a reduction in U bioavailability. Concentrations of U in both the overlying water and sediment pore water displayed a strong positive relationship to U bioaccumulation in C. dilutus larvae (r(2) = 0.77, p<0.001 and r(2) = 0.57, p < 0.001, respectively) for all experiments, while total U concentrations in the sediment had a poor relationship to U bioaccumulation (r(2) = 0.10, p = 0.028). Results from this research confirm that sediment clay and organic matter content play a significant role in altering U bioavailability, which is important in informing risk assessments of U contaminated sites and in the development of site-specific sediment quality guidelines for U.

  4. Antimicrobial clay-based materials for wound care.

    PubMed

    Gaskell, Elsie E; Hamilton, Ashley R

    2014-04-01

    The historical use of clay minerals for the treatment of wounds and other skin ailments is well documented and continues within numerous human cultures the world over. However, a more scientific inquiry into the chemistry and properties of clay minerals emerged in the 19th century with work investigating their role within health gathering pace since the second half of the 20th century. This review gives an overview of clay minerals and how their properties can be manipulated to facilitate the treatment of infected wounds. Evidence of the antimicrobial and healing effects of some natural clay minerals is presented alongside a range of chemical modifications including metal-ion exchange, the formation of clay-drug composites and the development of various polymer-clay systems. While the evidence for applying these materials to infected wounds is limited, we contextualize and discuss the future of this research. PMID:24895893

  5. Antimicrobial clay-based materials for wound care.

    PubMed

    Gaskell, Elsie E; Hamilton, Ashley R

    2014-04-01

    The historical use of clay minerals for the treatment of wounds and other skin ailments is well documented and continues within numerous human cultures the world over. However, a more scientific inquiry into the chemistry and properties of clay minerals emerged in the 19th century with work investigating their role within health gathering pace since the second half of the 20th century. This review gives an overview of clay minerals and how their properties can be manipulated to facilitate the treatment of infected wounds. Evidence of the antimicrobial and healing effects of some natural clay minerals is presented alongside a range of chemical modifications including metal-ion exchange, the formation of clay-drug composites and the development of various polymer-clay systems. While the evidence for applying these materials to infected wounds is limited, we contextualize and discuss the future of this research.

  6. Chemical reactions of organic compounds on clay surfaces

    SciTech Connect

    Soma, Yuko; Soma, Mitsuyuki )

    1989-11-01

    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.

  7. Mars, clays and the origins of life

    NASA Technical Reports Server (NTRS)

    Hartman, Hyman

    1989-01-01

    To detect life in the Martian soil, tests were designed to look for respiration and photosynthesis. Both tests (labeled release, LR, and pyrolytic release, PR) for life in the Martian soils were positive. However, when the measurement for organic molecules in the soil of Mars was made, none were found. The interpretation given is that the inorganic constituents of the soil of Mars were responsible for these observations. The inorganic analysis of the soil was best fitted by a mixture of minerals: 60 to 80 percent clay, iron oxide, quartz, and soluble salts such as halite (NaCl). The minerals most successful in simulating the PR and LR experiments are iron-rich clays. There is a theory that considers clays as the first organisms capable of replication, mutation, and catalysis, and hence of evolving. Clays are formed when liquid water causes the weathering of rocks. The distribution of ions such as aluminum, magnesium, and iron play the role of bases in the DNA. The information was stored in the distribution of ions in the octahedral and tetrahedral molecules, but that they could, like RNA and DNA, replicate. When the clays replicated, each sheet of clay would be a template for a new sheet. The ion substitutions in one clay sheet would give rise to a complementary or similar pattern on the clay synthesized on its surface. It was theorized that it was on the surface of replicating iron-rich clays that carbon dioxide would be fixed in the light into organic acids such as formic or oxalic acid. If Mars had liquid water during a warm period in its past, clay formation would have been abundant. These clays would have replicated and evolved until the liquid water was removed due to cooling of Mars. It is entirely possible that the Viking mission detected life on Mars, but it was clay life that awaits the return of water to continue its evolution into life based on organic molecules.

  8. Genotoxic potential of montmorillonite clay mineral and alteration in the expression of genes involved in toxicity mechanisms in the human hepatoma cell line HepG2.

    PubMed

    Maisanaba, Sara; Hercog, Klara; Filipic, Metka; Jos, Ángeles; Zegura, Bojana

    2016-03-01

    Montmorillonite, also known as Cloisite(®)Na(+) (CNa(+)), is a natural clay with a wide range of well-documented and novel applications, such as pharmaceutical products or food packaging. Although considered a low toxic product, the expected increased exposure to CNa(+) arises concern on the potential consequences on human and environmental health especially as its genotoxicity has scarcely been investigated so far. Thus, we investigated, for the first time, the influence of non-cytotoxic concentrations of CNa(+) (15.65, 31.25 and 62.5 μg/mL) on genomic instability of human hepatoma cell line (HepG2) by determining the formation of micronuclei (MNi), nucleoplasmic bridges (NPBs) and nuclear buds (NBUDs) with the Cytokinesis block micronucleus cytome assay. Further on we studied the influence of CNa(+) on the expression of several genes involved in toxicity mechanisms using the real-time quantitative PCR. The results showed that CNa(+) increased the number of MNi, while the numbers of NBUDs and NPBs were not affected. In addition it deregulated genes in all the groups studied, mainly after longer time of exposure. These findings provide the evidence that CNa(+) is potentially genotoxic. Therefore further studies that will elucidate the molecular mechanisms involved in toxic activity of CNa(+) are needed for hazard identification and human safety assessment.

  9. 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)

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

    2014-01-01

    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.

  10. 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

    Whitney, G.; Northrop, H.R.

    1987-01-01

    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

  11. Investigation of the microporous structure of clays and pillared clays by {sup 129}Xe NMR.

    SciTech Connect

    Tsaio, C.-J.; Carrado, K. A.; Botto, R. E.; Chemistry

    1998-04-01

    {sup 129}Xe NMR spectroscopy of xenon gas adsorbed in clays and pillared clays has been used to glean information on the interlayer gallery height of clays before and after pillaring. Two clay minerals were studied, a Ca{sup 2+}-montmorillonite and Bentonite L. The NMR results indicate that the effective interlamellar spacing of the montmorillonite increased from 5.4 to 8.0 Angstroms after pillaring with aluminum polyoxohydroxy Keggin cations. These data are consistent with X-ray powder diffraction results, which show a corresponding increase in gallery height from 5.6 to 8.4 Angstroms.

  12. 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...

  13. Thermo Gravimetric and Differential Thermal Analysis of Clay of Western Rajasthan (india)

    NASA Astrophysics Data System (ADS)

    Shekhawat, M. S.

    The paper presents the study of thermo gravimetric and differential thermal analysis of blended clay. Western part of Rajasthan (India) is rich resource of Ball clays and it is mainly used by porcelain, sanitary ware, and tile industry. The quality and grade of clay available in the region vary from one deposit to other. To upgrade the fired colour and strength properties, different variety of clays may be blended together. The paper compares the results of thermal analysis one of blended clay B2 with reference clay of Ukraine which is imported by industries owners. The result revealed that the blended clay is having mineral kaolinite while the Ukrainian clay is Halloysite.

  14. Burnt clay magnetic properties and palaeointensity determination

    NASA Astrophysics Data System (ADS)

    Avramova, Mariya; Lesigyarski, Deyan

    2014-05-01

    Burnt clay structures found in situ are the most valuable materials for archaeomagnetic studies. From these materials the full geomagnetic field vector described by inclination, declination and intensity can be retrieved. The reliability of the obtained directional results is related to the precision of samples orientation and the accuracy of characteristic remanence determination. Palaeointensity evaluations depend on much more complex factors - stability of carried remanent magnetization, grain-size distribution of magnetic particles and mineralogical transformations during heating. In the last decades many efforts have been made to shed light over the reasons for the bad success rate of palaeointensity experiments. Nevertheless, sometimes the explanation of the bad archaeointensity results with the magnetic properties of the studied materials is quite unsatisfactory. In order to show how difficult is to apply a priory strict criteria for the suitability of a given collection of archaeomagnetic materials, artificial samples formed from four different baked clays are examined. Two of the examined clay types were taken from clay deposits from different parts of Bulgaria and two clays were taken from ancient archaeological baked clay structures from the Central part of Bulgaria and the Black sea coast, respectively. The samples formed from these clays were repeatedly heated in known magnetic field to 700oC. Different analyses were performed to obtain information about the mineralogical content and magnetic properties of the samples. The obtained results point that all clays reached stable magnetic mineralogy after the repeated heating to 700oC, the main magnetic mineral is of titano/magnetite type and the magnetic particles are predominantly with pseudo single domain grain sizes. In spite that, the magnetic properies of the studied clays seem to be very similar, reliable palaeointensity results were obtained only from the clays coming from clay deposits. The

  15. Imprinted Clay Coil Vessels

    ERIC Educational Resources Information Center

    Lohr, Tresa Rae

    2006-01-01

    The author teaches clay vessel construction in the fifth grade, and it is amazing what can be accomplished in one forty-five minute period when the expectations are clarified in the initial lesson. The author introduces clay coil vessels with a discussion of the sources of clay and how clay relates to fifth-grade science curriculum concepts such…

  16. Common clay and shale

    USGS Publications Warehouse

    Virta, R.L.

    2011-01-01

    The article discusses the latest developments in the global common clay and shale industry, particularly in the U.S. It claims that common clay and shale is mainly used in the manufacture of heavy clay products like brick, flue tile and sewer pipe. The main producing states in the U.S. include North Carolina, New York and Oklahoma. Among the firms that manufacture clay and shale-based products are Mid America Brick & Structural Clay Products LLC and Boral USA.

  17. Ion-exchange reactions on clay minerals coupled with advection/dispersion processes. Application to Na+/Ca2+ exchange on vermiculite: Reactive-transport modeling, batch and stirred flow-through reactor experiments

    NASA Astrophysics Data System (ADS)

    Tertre, E.; Hubert, F.; Bruzac, S.; Pacreau, M.; Ferrage, E.; Prêt, D.

    2013-07-01

    The present study aims at testing the validity of using an Na+/Ca2+ ion-exchange model, derived from batch data to interpret experimental Ca2+-for-Na+ exchange breakthrough curves obtained on vermiculite (a common swelling clay mineral in surface environments). The ion-exchange model was constructed considering the multi-site nature of the vermiculite surface as well as the exchange of all aqueous species (Mg2+ derived from the dissolution of the solid and H+). The proposed ion-exchange model was then coupled with a transport model, and the predicted breakthrough curves were compared with the experimental ones obtained using a well stirred flow-through reactor. For a given solute residence time in the reactor (typically 50 min), our thermodynamic model based on instantaneous equilibrium was found to accurately reproduce several of the experimental breakthrough curves, depending on the Na+ and Ca2+ concentrations of the influents pumped through the reactor. However the model failed to reproduce experimental breakthrough curves obtained at high flow rates and low chemical gradient between the exchanger phase and the solution. An alternative model based on a hybrid equilibrium/kinetic approach was thus used and allowed predicting experimental data. Based on these results, we show that a simple parameter can be used to differentiate between thermodynamic and kinetic control of the exchange reaction with water flow. The results of this study are relevant for natural systems where two aquatic environments having contrasted chemistries interact. Indeed, the question regarding the attainment of a full equilibrium in such a system during the contact time of the aqueous phase with the particle/colloid remains most often open. In this context, we show that when a river (a flow of fresh water) encounters marine colloids, a systematic full equilibrium can be assumed (i.e., the absence of kinetic effects) when the residence time of the solute in 1 m3 of the system is ⩾6200 h.

  18. Phosphates in some missouri refractory clays

    USGS Publications Warehouse

    Hall, R.B.; Foord, E.E.; Keller, D.J.; Keller, W.D.

    1997-01-01

    This paper describes in detail phosphate minerals occurring in refractory clays of Missouri and their effect on the refractory degree of the clays. The minerals identified include carbonate-fluorapatite (francolite), crandallite, goyazite, wavellite, variscite and strengite. It is emphasized that these phosphates occur only in local isolated concentrations, and not generally in Missouri refractory clays. The Missouri fireclay region comprises 2 districts, northern and southern, separated by the Missouri River In this region, clay constitutes a major part of the Lower Pennsylvanian Cheltenham Formation. The original Cheltenham mud was an argillic residue derived from leaching and dissolution of pre-Pennsylvanian carbonates. The mud accumulated on a karstic erosion surface truncating the pre-Cheltenham rocks. Fireclays of the northern district consist mainly of poorly ordered kaolinite, with variable but minor amounts of illite, chlorite and fine-grained detrital quartz. Clays of the southern district were subjected to extreme leaching that produced well-ordered kaolinite flint clays. Local desilication formed pockets of diaspora, or more commonly, kaolinite, with oolite-like nubs or burls of diaspore ("burley" clay). The phosphate-bearing materials have been studied by X-ray diffraction (XRD), scanning electron microscopy-energy dispersive spectral analysis (SEM-EDS) and chemical analysis. Calcian goyazite was identified in a sample of diaspore, and francolite in a sample of flint clay. A veinlet of wavellite occurs in flint clay at one locality, and a veinlet of variscite-strengite at another locality. The Missouri flint-clay-hosted francolite could not have formed in the same manner as marine francolite The evidence suggests that the Cheltenham francolite precipitated from ion complexes in pore water nearly simultaneously with crystallization of kaolinite flint clay from an alumina-silica gel. Calcian goyazite is an early diagenetic addition to its diaspore host

  19. Prolonged triboluminescence in clays and other minerals

    NASA Technical Reports Server (NTRS)

    Lahav, N.; Coyne, L. M.; Lawless, J. G.

    1982-01-01

    The decay curves of various triboluminescent-excited materials were obtained, including well-crystallized and poorly crystallized kaolin, bentonite, quartz, sodium chloride, and chalk calcite. A qualitative increase in triboluminescence was observed for kaolin dipped in water or tryptophan solution compared to dry kaolin, and for frozen kaolin and montmorillonite pastes. Theoretical explanations for the tryptophan effect are discussed.

  20. Structures and properties of anionic clay minerals

    NASA Astrophysics Data System (ADS)

    Koch, Chr. Bender

    1998-12-01

    The Mössbauer spectra of pyroaurite-sjögrenite-type compounds (PTC) (layered anion exchangers) are discussed with reference to the crystal structure, cation order, and crystallite morphology. It is shown that cation-ordered layers are produced in the synthesis of carbonate and sulphate types of green rust. In contrast, synthetic and natural pyroaurite only occurs as disordered types. The redox chemistry of Fe(III) within the metal hydroxide layer is illustrated with examples of electrochemical oxidation and reversible reduction by boiling glycerol. The chemistry of iron in the interlayer is exemplified by the intercalation of Fe-cyanide complexes in hydrotalcite. This reaction may be used as a probe for the charge distribution in the interlayer.

  1. ADSORPTION OF BACTERIOPHAGES ON CLAY MINERALS

    EPA Science Inventory

    Theability to predict the fate of microorganisms in soil is dependent on an understanding of the process of their sorption on soil and subsurface materials. Presently, we have focused on studying the thermodynamics of sorption of bacteriophages (T-2, MS-2, and

  2. Natural Radioactivity of Boron Added Clay Samples

    SciTech Connect

    Akkurt, I.; Guenoglu, K.; Canakcii, H.; Mavi, B.

    2011-12-26

    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.

  3. Natural Radioactivity of Boron Added Clay Samples

    NASA Astrophysics Data System (ADS)

    Akkurt, I.; ćanakciı, H.; Mavi, B.; Günoǧlu, K.

    2011-12-01

    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.

  4. Chemical reactions of organic compounds on clay surfaces.

    PubMed Central

    Soma, Y; Soma, M

    1989-01-01

    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. PMID:2533556

  5. Sediment management and renewability of floodplain clay for structural ceramics

    NASA Astrophysics Data System (ADS)

    van der Meulen, M. J.; Wiersma, A. P.; Middelkoop, H.; van der Perk, M.; Bakker, M.; Maljers, D.; Hobo, N.; Makaske, B.

    2009-04-01

    The Netherlands have vast resources of clay that are exploited for the fabrication of structural ceramic products such as bricks and roof tiles. The extraction of clay creates land surface lowerings of about 1.5 m, of which the majority are located in the embanked floodplains of the rivers Rhine and Meuse. At these surface lowerings, clay is replenished within several decades. This study explores to which extent the clay can be regarded as a renewable resource, with potential for sustainable use. For this purpose, first the current and past clay consumption is calculated. Subsequently, clay deposition in the floodplains is estimated from literature data on clay accumulation using sediment traps, heavy metal and radionuclide distribution in soil profiles, and from morphological modelling studies. These estimates of clay-deposition and consumption are then compared following three approaches that consider various temporal and spatial scales of clay deposition. This allows us to establish the extent to which man determines sedimentary processes in the Dutch floodplains. Consequently, using the sediment response to the land surface lowering resulting from clay extraction, we explore sediment management options for the Dutch Rhine and Meuse. Altogether we argue that clay has been, probably is, and certainly can be managed as a renewable mineral resource.

  6. Zinc-rich clays in supergene non-sulfide zinc deposits

    NASA Astrophysics Data System (ADS)

    Choulet, F.; Buatier, M.; Barbanson, L.; Guégan, R.; Ennaciri, A.

    2016-04-01

    The nature and the origin of zinc clays are poorly understood. With the example of the Bou Arhous Zn-Pb ore deposit in the Moroccan High Atlas, this study presents new data for the mineralogical and chemical characterization of barren and zinc clays associated with non-sulfide zinc ores. In the field, white to ocher granular clays are associated with willemite (Zn2SiO4), while red clays fill karst-related cavities cutting across the non-sulfide ore bodies. Red clays (kaolinite, chlorite, illite, and smectite) present evidence of stratification that reflects internal sedimentation processes during the karst evolution. White clays contain 7-Å clay mineral/smectite irregular interstratified minerals with less than 20 % of smectite layers. Willemite is partially dissolved and is surrounded by authigenic zinc clay minerals. Together with XRD results, WDS analyses on newly formed clay aggregates suggest that this interstratified mineral is composed of fraipontite and sauconite. CEC measurements support that zinc is only located within the octahedral sheets. These new results support the following process: (i) dissolution of willemite, leading to release of Si and Zn, (ii) interaction between Zn-Si-rich solutions and residual-detrital clays, and (iii) dissolution of kaolinite and formation of interstratified zinc clay minerals that grew over detrital micas.

  7. Clays causing adhesion with tool surfaces during mechanical tunnel driving

    NASA Astrophysics Data System (ADS)

    Spagnoli, G.; Fernández-Steeger, T.; Stanjek, H.; Feinendegen, M.; Post, C.; Azzam, R.

    2009-04-01

    During mechanical excavation with a tunnel boring machine (TBM) it is possible that clays stick to the cutting wheel and to other metal parts. The resulting delays in the progress of construction work, cause great economic damage and often disputes between the public awarding authorities and executing companies. One of the most important factors to reduce successfully the clay adhesion is the use of special polymers and foams. But why does the clay stick to the metal parts? A first step is to recognize which kind of clay mineralogy shows serious adhesion problems. The mechanical properties of clay and clay suspensions are primarily determined by surface chemistry and charge distribution at the interfaces, which in turn affect the arrangement of the clay structure. As we know, clay is a multi-phase material and its behaviour depends on numerous parameters such as: clay mineralogy, clay fraction, silt fraction, sand fraction, water content, water saturation, Atterberg limits, sticky limit, activity, cation exchange capacity, degree of consolidation and stress state. It is therefore likely that adhesion of clay on steel is also affected by these clay parameters. Samples of clay formations, which caused problems during tunnel driving, will be analyzed in laboratory. Mineralogical analyses (diffractometry, etc.) will be carried out to observe which minerals are responsible for adherence problems. To manipulate the physical properties, batch tests will be carried out in order to eliminate or reduce the adhesion on tool surfaces through variation of the zeta potential. Second step is the performance of vane shear tests on clay samples. Different pore fluid (distilled water, pure NaCl solution, ethanol and methanol) will be used to study the variation of the mechanical behaviour of clay depending on the dielectric constant of the fluids. This project is funded by the German Federal Ministry of Education and Research (BMBF) and the DFG (German Research Foundation) in the

  8. Portable Radiometer Identifies Minerals in the Field

    NASA Technical Reports Server (NTRS)

    Goetz, A. F. H.; Machida, R. A.

    1982-01-01

    Hand-held optical instrument aids in identifying minerals in field. Can be used in exploration for minerals on foot or by aircraft. The radiometer is especially suitable for identifying clay and carbonate minerals. Radiometer measures reflectances of mineral at two wavelengths, computes ratio of reflectances, and displays ratio to user.

  9. Clay swelling — A challenge in the oilfield

    NASA Astrophysics Data System (ADS)

    Anderson, R. L.; Ratcliffe, I.; Greenwell, H. C.; Williams, P. A.; Cliffe, S.; Coveney, P. V.

    2010-02-01

    Water-based drilling fluids are increasingly being used for oil and gas exploration, and are generally considered to be more environmentally acceptable than oil-based or synthetic-based fluids. Unfortunately, their use facilitates clay hydration and swelling. Clay swelling, which occurs in exposed sedimentary rock formations, can have an adverse impact on drilling operations and may lead to significantly increased oil well construction costs. Minimizing clay swelling is therefore an important area attracting a large amount of interest from both academia and industry. To effectively reduce the extent of clay swelling the mechanism by which clay minerals swell needs to be understood so that efficient swelling inhibitors may be developed. Acceptable clay swelling inhibitors must not only significantly reduce clay hydration, but must also meet increasingly stringent environmental guidelines while remaining cost effective. The development of these inhibitors, which are generally based upon water soluble polymers, therefore represents a challenge to oilfield geochemistry. This review aims to provide a comprehensive understanding of the mechanism by which clay minerals swell and what steps have been taken in the development of effective and environmentally friendly clay swelling inhibitors.

  10. Modified clay sorbents

    DOEpatents

    Fogler, H. Scott; Srinivasan, Keeran R.

    1990-01-01

    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.

  11. Soil clay content underlies prion infection odds

    USGS Publications Warehouse

    David, Walter W.; Walsh, D.P.; Farnsworth, Matthew L.; Winkelman, D.L.; Miller, M.W.

    2011-01-01

    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. ?? 2011 Macmillan Publishers Limited. All rights reserved.

  12. What makes a natural clay antibacterial?

    PubMed

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

    2011-04-15

    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 Fe(2+) 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 Fe(2+). Fenton reaction products can degrade critical cell components, but we deduce that extracellular processes do not cause cell death. Rather, Fe(2+) overwhelms outer membrane regulatory proteins and is oxidized when it enters the cell, precipitating Fe(3+) and producing lethal hydroxyl radicals.

  13. What Makes a Natural Clay Antibacterial?

    PubMed Central

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

    2011-01-01

    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. PMID:21413758

  14. Soil clay content underlies prion infection odds

    PubMed Central

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

    2011-01-01

    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. PMID:21326232

  15. Comparison of tetrachloromethane sorption to an alkylammonium-clay and an alkyldiammonium-clay

    USGS Publications Warehouse

    Smith, J.A.; Jaffe, P.R.

    1991-01-01

    The interlamellar space of Wyoming bentonite (clay) was modified by exchanging either decyltrimethyl-ammonium (DTMA) or decyltrimethyldiammonium (DTMDA) cations for inorganic ions, and tetrachloromethane sorption to the resulting two organoclays from water was studied at 10, 20, and 35??C. Only one end of the 10-carbon alkyl chain of the DTMA cation is attached to the silica surface of the clay mineral, and tetrachloromethane sorption of DTMA-clay is characterized by isotherm linearity, noncompetitive sorption, weak solute uptake, and a relatively low heat of sorption. Both ends of the 10-carbon chain of the DTMDA cation are attached to the silica surface of the clay mineral, and tetrachloromethane sorption to DTMDA-clay is characterized by nonlinear isotherms, competitive sorption, strong solute uptake, and a relatively high, exothermic heat of sorption that varies as a function of the mass of tetrachloromethane sorbed. Therefore, the attachment of both ends of the alkyl chain to the interlamellar mineral surface appears to change the sorption mechanism from a partition-dominated process to an adsorption-dominated process. ?? 1991 American Chemical Society.

  16. Iodide Sorption to Clays and the Relationship to Surface Charge and Clay Texture - 12356

    SciTech Connect

    Miller, Andrew; Kruichiak, Jessica; Tellez, Hernesto; Wang, Yifeng

    2012-07-01

    Iodine is assumed to behave conservatively in clay barriers around nuclear waste repositories and in natural sediments. Batch experiments tend to show little to no sorption, while in column experiments iodine is often retarded relative to tritiated water. Current surface complexation theory cannot account for negatively charged ion sorption to a negatively charged clay particle. Surface protonation and iodide sorption to clay minerals were examined using surface titrations and batch sorption experiments with a suite of clay minerals. Surface titrations were completed spanning a range of both pH values and ionic strengths. For reference, similar titrations were performed on pure forms of an Al-O powder. The titration curves were deconvoluted to attain the pKa distribution for each material at each ionic strength. The pKa distribution for the Al-O shows two distinct peaks at 4.8 and 7.5, which are invariant with ionic strength. The pKa distribution of clays was highly variable between the different minerals and as a function of ionic strength. Iodide sorption experiments were completed at high solid:solution ratios to exacerbate sorption properties. Palygorskite and kaolinite had the highest amount of iodide sorption and montmorillonite had the least. (authors)

  17. The Ultrastructure of Clay-Humic Complexes in an Iowa Mollisol

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The chemical and physical activity of clay minerals in soils, particularly in surface horizons, is significantly mediated by interactions with organic components. The reactivity of soil organic matter, including its resistance to decomposition, is regulated by interactions with clay minerals. This m...

  18. Finicky clay divers

    NASA Astrophysics Data System (ADS)

    Cordry, Sean M.

    1998-02-01

    Clay spheres dropped into a dilute vinegar/baking-soda solution accumulate CO2 bubbles on their surfaces. Spheres below a certain size will then float, otherwise they remain sunken. Students must determine the maximum size that will float by considering the net density of the clay/bubble system.

  19. The Science of Clay

    ERIC Educational Resources Information Center

    Warwick, Sharon

    2005-01-01

    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…

  20. Columns in Clay

    ERIC Educational Resources Information Center

    Leenhouts, Robin

    2010-01-01

    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…

  1. Clay Portrait Boxes

    ERIC Educational Resources Information Center

    Wilbert, Nancy Corrigan

    2009-01-01

    In an attempt to incorporate sculptural elements into her ceramics program, the author decided to try direct plaster casting of the face to make a plaster mold for clay. In this article, the author shares an innovative ceramics lesson that teaches students in making plaster casts and casting the face in clay. This project gives students the…

  2. The clays of the United States east of the Mississippi River

    USGS Publications Warehouse

    Ries, Henrich

    1903-01-01

    Since clays vary mineralogically they vary also chemically, but the plasticity may remain the same through a wide range of chemical composition, and this property is evidently not dependent on the chemical composition alone, but is due rather to some physical cause. The plasticity may be destroyed by heating the clay to a sufficiently high temperature to drive off the chemically combined water. Although varying in their mineral composition, most clays are supposed to contain more or less of the mineral kaolinite (a hydrated silicate of alumina), which is commonly referred to as the clay base or clay substance. The adoption of the latter term has probably arisen from the fact that many have 'considered this mineral to be the cause of plasticity, an idea now known to be somewhat incorrect, because some of the most plastic clays contain but small quantities of kaolinite, and vice versa. 

  3. Effects of shock metamorphism on clay mineralogy: Implications for remote sensing of martian clays

    NASA Astrophysics Data System (ADS)

    Michalski, J. R.; Glotch, T. D.; Friedlander, L.; Bish, D. L.; Sharp, T. G.; Dyar, M. D.

    2012-12-01

    One of the most important discoveries in recent exploration of Mars has been the detection of clay minerals within materials exhumed by meteor impact, which point to ancient subsurface alteration and possible habitable conditions at depth. These "crustal clays" occur within central peaks, ejecta, and uplifted rims of many large craters (Ehlmann et al., Nature 2011). The geologic context of phyllosilicates in these settings suggests that most of these deposits represent clays that formed in the subsurface and were later exhumed by impact, rather than clays that formed as a consequence of impact. Therefore, crustal clays exposed at the surface are likely to have experienced some effects of shock metamorphism and/or thermal alteration related to meteor impact. We are investigating the effects of shock metamorphism on the mineralogy of phyllosilicates in the laboratory. Purified, size-separated clay mineral samples were pressed into pellets to decrease internal porosity and were subsequently shocked using the Flat Plate Accelerator at NASA Johnson Space Center. Five minerals (nontronite, saponite, serpentine, chlorite, and kaolinite) were shocked to six pressure steps (10, 20, 25, 30, 35, and 40 GPa). The recovered, shocked samples are being analyzed by thermal infrared emission, visible/near-infrared reflectance, X-ray diffraction (XRD), Mossbauer spectroscopy, and transmission electron microscopy (TEM). Results thus far suggest that shock metamorphism has little effect on the structure or infrared signature of the clay minerals at pressures <20 GPa. One exception is the decrease in 3-D ordering in chlorite at 10 GPa, which steadily decreases until it is essentially lost at 30 GPa. At shock pressures of 20 GPa and higher, all minerals show evidence for broadening of the basal 001 reflection, indicative of progressive decrease in crystallite size. Above 30 GPa, the structures are intensely altered and by 40 GPa, most structural order is lost, based on both XRD and TEM

  4. Cytotoxicity and mutagenicity assessment of organomodified clays potentially used in food packaging.

    PubMed

    Maisanaba, Sara; Prieto, Ana I; Pichardo, Silvia; Jordá-Beneyto, María; Aucejo, Susana; Jos, Ángeles

    2015-09-01

    Modern food packaging has made great advances as result of global trends and consumer preferences, which are oriented to obtain improved food quality and safety. In this regard, clay minerals, and mainly Montmorillonite (Mt) are attracting considerable interest in food packaging because of the improvements developed in mechanical and barrier properties. Hence, the present work aim to assess the toxicity of four Montmorillonite-based clay minerals, an unmodified clay, Cloisite®Na+ (CNa+), and three modified Mt clays: Cloisite®30B (C30B), a commercial clay, and Clay1 and Clay2, two novel modified organoclays developed by the Packaging, Transport, & Logistics Research Institute (ITENE). First, the cytotoxic effects were studied in the Human Umbilical Vein Endothelial Cells (HUVEC). In addition, the potential mutagenicity of the clays was evaluated by the Ames test. Clay1 did not induce any cytotoxic effects in HUVEC, although it exhibited potential mutagenicity in TA98 Salmonella typhimurium strain. In contrast, Clay2 produced cytotoxicity in endothelial cells but no mutagenicity was recorded. However, CNa+ was not cytotoxic neither mutagenic. And finally, C30B showed positive results in both assays. Therefore, results showed that clay minerals have a different toxicity profile and a case by case toxicity evaluation is required.

  5. 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

    Ilgen, Anastasia G.; Trainor, Thomas P.

    2012-11-13

    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.

  6. Characterization of clay from northern of Morocco for their industrial application

    NASA Astrophysics Data System (ADS)

    El Ouahabi, Meriam; Fagel, Nathalie

    2010-05-01

    Clays are a natural resource used for millennia. Currently applications such as industrial minerals are diversified. In this context, our goal is to estimate the potential of the many clay deposits in northern of Morocco. The choice of this region is justified by the particular abundance of clay deposits used to manufacture building materials (brick, ceramic and refractories) and pottery. This study focuses on the mineralogical, chemical and geotechnical characterization tests carried out on Tangier-Tetouan and Meknes clays from northern of Morocco. The suitability of raw clay material from those regions in order to produce ceramic and brick has not been tested yet. The results revealed that the studied samples are diversified, kaolinite and illite (Tetouan clay) and kaolinite and illite and smectite and vermiculite (Tangier and Meknes clay) based materials. There were no major differences in grain-size distribution, whereas Meknes clay was more plastic than Tetouan-Tangier clay. The cation exchange capacity show that Meknes and Tangier clay were more important than Tetouan clay. Specific surface area and thermal analaysis complete this caracterization. It was found that almost all technological properties of the Meknes clay deposit are led to the manufacture of ceramic floor tile, and Tetouan-Tangier clay provide opportunities to making brick and ceramic floor. The Tetouan-Tangier and Meknes clay are a potential ceramic raw material for growing Morrocan ceramic tile and brick industries.

  7. Clays as dietary supplements for swine: A review.

    PubMed

    Subramaniam, Mohana Devi; Kim, In Ho

    2015-01-01

    Clays are crystalline, hydrated aluminosilicate molecules composed of alkali and alkaline earth cations along with small amounts of various other elements. The best-known are montmorillonite, smectite, illite, kaolinite, biotite and clinoptilolite. The molecules in these clays are arranged in three-dimensional structures creating internal voids and channels capable of trapping a wide variety of molecules. As a result of this structure, clay minerals are regarded as a simple and effective tool for the prevention of the negative effects of many toxic compounds. Dietary supplementation with clays has been shown to improve weight gain and feed conversion in pigs. Where improvements in performance have been noted, one of the most likely explanations for the improvement is the fact clays increase nutrient digestibility. Clays reduce the speed of passage of feed along the digestive tract which allows more time for digestion. Feeding clays also causes morphological changes in the intestinal mucosa such as an increase in villus height and an increase in the villus height to crypt depth ratio. These changes increase the surface area of the gastrointestinal tract thus increasing nutrient digestibility. Several studies have indicated that feeding clay reduces the incidence, severity and duration of diarrhea in pigs. The mechanism for the reduction in diarrhea is likely due to increases in the numbers of Bifidobacteria and Lactobacillus and decreases in Clostridia and E. coli in the small intestine of pigs fed clays. In addition, the numbers of pigs born alive and weaned, birth weight and weaning weight have been shown to be higher for sows fed clays. Several studies have indicated that clays can help mitigate the effects of mycotoxins. The aim of the present review is to focus on the various clays which have been given attention in recent research and to discuss their potential to improve pig performance. PMID:26301092

  8. Designing in Clay

    ERIC Educational Resources Information Center

    Nigrosh, Leon I.

    1977-01-01

    What can be done to transform a lump of wet clay into something more than a lump of glaze-fired clay? It is at this point when forming techniques have been mastered that good design becomes most important. Discusses six criteria involved in the search for good design so that students can discover what good design is and how important it is.…

  9. Common clay and shale

    USGS Publications Warehouse

    Virta, R.L.

    2006-01-01

    At present, 150 companies produce common clay and shale in 41 US states. According to the United States Geological Survey (USGS), domestic production in 2005 reached 24.8 Mt valued at $176 million. In decreasing order by tonnage, the leading producer states include North Carolina, Texas, Alabama, Georgia and Ohio. For the whole year, residential and commercial building construction remained the major market for common clay and shale products such as brick, drain tile, lightweight aggregate, quarry tile and structural tile.

  10. Inter-layered clay stacks in Jurassic shales

    NASA Technical Reports Server (NTRS)

    Pye, K.; Krinsley, D. H.

    1983-01-01

    Scanning electron microscopy in the backscattered electron mode is used together with energy-dispersive X-ray microanalysis to show that Lower Jurassic shales from the North Sea Basin contain large numbers of clay mineral stacks up to 150 microns in size. Polished shale sections are examined to determine the size, shape orientation, textural relationships, and internal compositional variations of the clays. Preliminary evidence that the clay stacks are authigenic, and may have formed at shallow burial depths during early diagenesis, is presented.

  11. Field trip guidebook on environmental impact of clays along the upper Texas coast

    NASA Technical Reports Server (NTRS)

    Garcia, Theron D.; Ming, Douglas W.; Tuck, Lisa Kay

    1991-01-01

    The field trip was prepared to provide an opportunity to see first hand some the environmental hazards associated with clays in the Houston, Texas area. Because of the very high clay content in area soils and underlying Beaumont Formation clay, Houston is a fitting location to host the Clay Mineral Society. Examinations were made of (1) expansive soils, (2) subsidence and surface faulting, and (3) a landfill located southeast of Houston at the Gulf Coast Waste Disposal Authority where clay is part of the liner material.

  12. Formation of stable nanocomposite clays from small peptides reacted with montmorillonite and illite-smectite mixed layer clays

    NASA Astrophysics Data System (ADS)

    Block, K. A.; Katz, A.; LeBlanc, J.; Peña, S.; Gottlieb, P.

    2015-12-01

    Understanding how organic compounds interact with clay minerals and which functional groups result in the strongest bonds is pivotal to achieving a better understanding of how mineral composition affects the residence time of carbon and nitrogen in soils. In this work, we describe how small peptides derived from tryptone casein digest are dissolved and suspended with clay minerals to examine the nature of OM adsorption to mineral surfaces and the resulting effect on clay mineral structure. XRD analyses indicate that peptides intercalation results in expansion of the d001 spacing of montmorillonite (Mt) and the smectite component of a 70-30 illite-smectite mixed layer clay (I-S) and poorer crystallinity overall as a result of exfoliation of tactoids. Peptide adsorption is concentration-dependent, however, surface adsorption appears to mediate interlayer adsorption in Mt reaching a maximum of 16% of the mass of the organoclay complex, indicating that at a critical concentration, peptide intercalation will supersede surface adsorption resulting in a more stable attachment. In I-S the degree of surface adsorption and intercalation is proportional to concentration, however, surface adsorption is not a priming mechanism for interlayer adsorption. Thermogravimetric analysis of the organoclay complexes determined by TGA coupled to GC-MS indicate that the most prominent product species measured was 1-(1-Trimethylsiloxyethenyl)-3-trimethylsiloxy-benzene, likely from tryptophan monomer decomposition. The compound was detected over a broad temperature range, greater than 300 oC, during pyrolysis and suggests a carbon-silicon covalent bond formed between the peptide and tetrahedral layers in the clay. An additional silicon-bearing VOC detected at lower pyrolysis temperature by GC was N,N-Diethyl-1-(trimethylsilyl)-9,10-didehydroergoline-8-carboxamide, likely derived from a lysine-bearing peptide derivative. We hypothesize that hydrophobic (non-ionic) peptides react with silanol

  13. Clay nanocomposites for use in Li batteries

    NASA Astrophysics Data System (ADS)

    Moore, Gregory John

    1999-11-01

    Nanocomposites, materials made of more than one component and combined in an ordered manner on the nanometer scale, were synthesized using clay mineral hosts with various types of guests. The guests include polymers such as polyethylene oxide (PEO) and polyaniline (PANI), large molecules such as ethylmethyl sulfone, tetramethylene sulfone, and various length alkylamines. Vanadyl groups (VO 2+) were also incorporated with the clays. The otherwise non-swellable mica clay, synthetic Na-fluorophlogopite, was expanded by intercalation of acidic ions such as Cu2+ and Fe3+. As aqueous solutions, these ions caused the stable fluoromica to go from its dehydrated interlayer spacing of 9.8 A to over 14 A. This clay became a host for many other reactions including swelling with alkylamines to over 25 A. However, despite hydrated Cu2+ ions swelling fluorophlogopite, polymeric species such as PEO or PANI could not be inserted. Another clay that was used for formation of nanocomposites came from a procedure for the synthesis of Li-taeniolite, Li(Mg2Li)Si 4O10F2. The clay was synthesized following a high temperature method that led to a non-reactive product. Instead, a novel precursor route was employed that gave a clay product with a single hydration layer. Various chemical analyses gave a formula of Li0.8(Mg 2.2Li0.8)Si4O10(F1.6O 0.4)·H2O. For the purpose of forming nanocomposite electrolytes, ethylmethyl sulfone was synthesized and incorporated into the clay. For comparison of different shaped sulfones, tetramethylene sulfone also was inserted into the layers for electrolytic studies. To make a polymer-clay electrolyte, polyethylene oxide was intercalated into the Li-taeniolite. All of these new electrolyte materials were characterized using impedance spectroscopy for measurement of their conductivity. Syntheses and analyses are thoroughly discussed for all of these materials. Special attention is placed on powder x-ray diffraction and thermogravimetric techniques to

  14. Adsorption and Desorption of Nitrogen and Water Vapor by clay

    NASA Astrophysics Data System (ADS)

    Cui, Deshan; Chen, Qiong; Xiang, Wei; Huang, Wei

    2015-04-01

    Adsorption and desorption of nitrogen and water vapor by clay has a significant impact on unsaturated soil physical and mechanical properties. In order to study the adsorption and desorption characteristics of nitrogen and water vapor by montmorillonite, kaolin and sliding zone soils, the Autosorb-iQ specific surface area and pore size analyzer instrument of United State was taken to carry out the analysis test. The adsorption and desorption of nitrogen at 77K and water vapor at 293K on clay sample were conducted. The theories of BET, FHH and hydration energy were taken to calculate the specific surface, surface fractal dimension and adsorption energy. The results show that the calculated specific surface of water vapor by clay is bigger than nitrogen adsorption test because clay can adsorb more water vapor molecule than nitrogen. Smaller and polar water vapor molecule can access the micropore and then adsorb on the mineral surface and mineral intralayer, which make the mineral surface cations hydrate and the mineral surface smoother. Bigger and nonpolar nitrogen molecule can not enter into the micropore as water vapor molecule and has weak interaction with clay surface.

  15. Clay mineralogy in agrochernozems of western Ukraine

    NASA Astrophysics Data System (ADS)

    Papish, I. Ya.; Chizhikova, N. P.; Poznyak, S. P.; Varlamov, E. B.

    2016-10-01

    The mineralogy of clay fractions separated from deep low-humus deep-gleyic loamy typical agrochernozems on loess-like loams of the Upper Bug and Dniester uplands in the Central Russian loess province of Ukraine consists of complex disordered interstratifications with the segregation of mica- and smectite-type layers (hereafter, smectite phase), tri- and dioctahedral hydromicas, kaolinite, and chlorite. The distribution of the clay fraction is uniform. The proportions of the layered silicates vary significantly within the profile: a decrease in the content of the smectite phase and a relative increase in the content of hydromicas up the soil profile are recorded. In the upper horizons, the contents of kaolinite and chlorite increase, and some amounts of fine quartz, potassium feldspars, and plagioclases are observed. This tendency is observed in agrochernozems developed on the both Upper Bug and Dniester uplands. The differences include the larger amounts of quartz, potassium feldspars, and plagioclases in the clay material of the Upper Bug Upland, while the contents of the smectite phase in the soil profiles of the areas considered are similar. An analogous mineral association is noted in podzolized agrochernozems on loess-like deposits in the Cis-Carpathian region of the Southern Russian loess province developed on the Prut-Dniester and Syan-Dniester uplands. The distribution of particle-size fractions and the mineralogy of the clay fraction indicate the lithogenic heterogeneity of the soil-forming substrate. When the drifts change, the mineral association of the soils developed within the loess-like deposits gives place to minerals dominated by individual smectite with some mica-smectite inter stratifications, hydromicas, and chlorite.

  16. CEC-normalized clay-water sorption isotherm

    NASA Astrophysics Data System (ADS)

    Woodruff, W. F.; Revil, A.

    2011-11-01

    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.

  17. Spectromicroscopy of Fe distributions in clay microcrystals

    SciTech Connect

    Grundl, T.; Cerasari, S.; Garcia, A.

    1997-04-01

    Clays are ubiquitous crystalline particles found in nature that are responsible for contributing to a wide range of chemical reactions in soils. The structure of these mineral particles changes when the particle is hydrated ({open_quotes}wet{close_quotes}), from that when it is dry. This makes a study of the microscopic distribution of chemical content of these nanocrystals difficult using standard techniques that require vacuum. In addition to large structural changes, it is likely that chemical changes accompany the drying process. As a result, spectroscopic measurements on dried clay particles may not accurately reflect the actual composition of the material as found in the environment. In this work, the authors extend the use of the ALS Spectromicroscopy Facility STXM to high spectral and spatial resolution studies of transition metal L-edges in environmental materials. The authors are studying mineral particles of montmorillonite, which is an Fe bearing clay which can be prepared with a wide distribution of Fe concentrations, and with Fe occupying different substitutional sites.

  18. Co-evolution of monsoonal precipitation in East Asia and the tropical Pacific ENSO system since 2.36 Ma: New insights from high-resolution clay mineral records in the West Philippine Sea

    NASA Astrophysics Data System (ADS)

    Yu, Zhaojie; Wan, Shiming; Colin, Christophe; Yan, Hong; Bonneau, Lucile; Liu, Zhifei; Song, Lina; Sun, Hanjie; Xu, Zhaokai; Jiang, Xuejun; Li, Anchun; Li, Tiegang

    2016-07-01

    Clay mineralogical analysis and scanning electron microscope (SEM) analysis were performed on deep-sea sediments cored on the Benham Rise (core MD06-3050) in order to reconstruct long-term evolution of East Asian Summer Monsoon (EASM) rainfall in the period since 2.36 Ma. Clay mineralogical variations are due to changes in the ratios of smectite, which derive from weathering of volcanic rocks in Luzon Island during intervals of intensive monsoon rainfall, and illite- and chlorite-rich dusts, which are transported from East Asia by winds associated with the East Asian Winter Monsoon (EAWM). Since Luzon is the main source of smectite to the Benham Rise, long-term consistent variations in the smectite/(illite + chlorite) ratio in core MD06-3050 as well as ODP site 1146 in the Northern South China Sea suggest that minor contributions of eolian dust played a role in the variability of this mineralogical ratio and indicate strengthening EASM precipitation in SE Asia during time intervals from 2360 to 1900 kyr, 1200 to 600 kyr, and after 200 kyr. The EASM rainfall record displays a 30 kyr periodicity suggesting the influence of El Niño-Southern Oscillation (ENSO). These intervals of rainfall intensification on Luzon Island are coeval with a reduction in precipitation over central China and an increase in zonal SST gradient in the equatorial Pacific Ocean, implying a reinforcement of La Niña-like conditions. In contrast, periods of reduced rainfall on Luzon Island are associated with higher precipitation in central China and a weakening zonal SST gradient in the equatorial Pacific Ocean, thereby suggesting the development of dominant El Niño-like conditions. Our study, therefore, highlights for the first time a long-term temporal and spatial co-evolution of monsoonal precipitation in East Asia and of the tropical Pacific ENSO system over the past 2.36 Ma.

  19. The composition and origin of Ghana medicine clays

    PubMed Central

    van Dongen, Bart E.; Fraser, Sharon E.; Insoll, Timothy

    2011-01-01

    The mineral, organic and elemental composition of medicine clays from three shrines in the Tong Hills in northern Ghana (Gbankil, Kusanaab, and Yaane) are assessed to ascertain what additives they might contain and the implications for their recognition, for example in archaeological contexts. These are clays that are widely used for healing purposes being perceived efficacious in curing multiple ailments and which are given a divine provenance, but their collection is ascribed human agency. The Yaane clay is also supplied as part of the process of obtaining the right to operate the shrine elsewhere making it widely dispersed. Organic geochemical analyses revealed a predominance of plant-derived material with a substantial contribution of microbial origin. Based on these (supported by elemental and mineral analyses), no unnatural organic material could be detected, making an exogenous contribution to these clays unlikely. The implications are that these are wholly natural medicinal substances with no anthropogenic input into their preparation, as the traditions suggest. The very similar mineralogy of all the clays, including a non-medicine clay sampled, suggests that, unless the geology radically differed, differentiating between them analytically in an archaeological contexts would be doubtful. PMID:21810043

  20. Rattles of Clay.

    ERIC Educational Resources Information Center

    Banning, Donna

    1983-01-01

    Using the rattles of Native American cultures as inspiration, students used pinching, coiling, and slab and molding techniques to form the bodies of rattles and clay pellets for sound. Surface decoration included glazed and unglazed areas as well as added handles, feathers, and leather. (IS)

  1. Modeling in Ceramic Clay

    ERIC Educational Resources Information Center

    Miller, Louis J.

    1976-01-01

    Modeling is an additive process of building up a sculpture with some plastic material like clay. It affords the student an opportunity to work in three dimensions, a creative relief from the general two-dimensional drawing and design activities that occupy a large segment of time in the art curriculum. (Author/RK)

  2. Magnificent Clay Murals

    ERIC Educational Resources Information Center

    Kirker, Sara Schmickle

    2007-01-01

    Each August, third grade artists at Apple Glen Elementary in Bentonville, Arkansas, start the school year planning, creating, and exhibiting a clay relief mural. These mural projects have helped students to acquire not only art knowledge and techniques, but an even more important kind of knowledge: what it means to plan and successfully complete a…

  3. Humidity Dependent Extinction of Clay Aerosols

    NASA Astrophysics Data System (ADS)

    Greenslade, M. E.; Attwood, A. R.

    2010-12-01

    Aerosols play an important role in the Earth’s radiative balance by directly scattering and absorbing radiation. The magnitude of aerosol forcing can be altered by changes in relative humidity which cause aerosol size, shape and refractive index to vary. To quantify these effects, a custom cavity ring down instrument operated at 532 nm with two sample channels measures aerosols extinction under dry conditions and at elevated humidity. The optical growth, fRH(ext), is determined as a ratio of the extinction cross section at high relative humidity to that under dry conditions. Three key clay components of mineral dust and mixtures of clay components with ammonium sulfate are investigated using this method. Experimentally obtained optical growth is compared with physical growth factors from the literature and our work determined using several different techniques. Further, Mie theory calculations based on published optical constants are compared with experimental results. Differences between theory and experiment will be discussed.

  4. Chemical and mineralogical characteristics of French green clays used for healing

    USGS Publications Warehouse

    Williams, L.B.; Haydel, S.E.; Giese, R.F.; Eberl, D.D.

    2008-01-01

    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. Copyright ?? 2008, The Clay Minerals Society.

  5. Implications of cation exchange on clay release and colloid-facilitated transport in porous media

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Column experiments were conducted to study chemical factors that influence the release of clay (kaolinite and quartz minerals) from saturated Ottawa sand of different sizes (710, 360, and 240 µm). A relatively minor enhancement of clay release occurred when the pH was increased (5.8 to 10) or the i...

  6. Carbon Stabilization by Clays in the Environment: Process and Characterization Methods

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This workshop brings together experts and non-experts interested in understanding at the process level the role of clay minerals in soil organic carbon sequestration. Participants will leave with a thorough understanding of the current state of knowledge about the nature of clay-humic complexes, the...

  7. Clay Animals and Their Habitats

    ERIC Educational Resources Information Center

    Adamson, Kay

    2010-01-01

    Creating clay animals and their habitats with second-grade students has long been one of the author's favorite classroom activities. Students love working with clay and they also enjoy drawing animal homes. In this article, the author describes how the students created a diorama instead of drawing their clay animal's habitat. This gave students…

  8. Clay-based polymer nanocomposites: research and commercial development.

    PubMed

    Zeng, Q H; Yu, A B; Lu, G Q; Paul, D R

    2005-10-01

    This paper reviews the recent research and development of clay-based polymer nanocomposites. Clay minerals, due to their unique layered structure, rich intercalation chemistry and availability at low cost, are promising nanoparticle reinforcements for polymers to manufacture low-cost, lightweight and high performance nanocomposites. We introduce briefly the structure, properties and surface modification of clay minerals, followed by the processing and characterization techniques of polymer nanocomposites. The enhanced and novel properties of such nanocomposites are then discussed, including mechanical, thermal, barrier, electrical conductivity, biodegradability among others. In addition, their available commercial and potential applications in automotive, packaging, coating and pigment, electrical materials, and in particular biomedical fields are highlighted. Finally, the challenges for the future are discussed in terms of processing, characterization and the mechanisms governing the behaviour of these advanced materials. PMID:16245517

  9. Mineral Process Chemistry: A Special Study.

    ERIC Educational Resources Information Center

    Dudeney, A. W. L.

    1982-01-01

    Mineral Process Chemistry is one of the special study options of the Nuffield Advanced Science course in chemistry. Following general comments on mineral process chemistry, the subject matter of the option is described, focusing on copper and china clay. (Author/JN)

  10. Simultaneous enhancements of UV resistance and mechanical properties of polypropylene by incorporation of dopamine-modified clay.

    PubMed

    Phua, Si Lei; Yang, Liping; Toh, Cher Ling; Guoqiang, Ding; Lau, Soo Khim; Dasari, Aravind; Lu, Xuehong

    2013-02-01

    Inspired by the radical scavenging function of melanin-like materials and versatile adhesive ability of mussel-adhesion proteins, dopamine-modified clay (D-clay) was successfully incorporated into polypropylene (PP) using an amine-terminated PP oligomer as the compatibilizer. Although the PP/D-clay nanocomposites exhibit intercalated morphology, the incorporation of D-clay greatly improves the thermo-oxidative stability and UV resistance of PP owing to the strong radical scavenging ability of polydopamine (PDA) and large contact area between PP and the PDA coating on clay mineral. Moreover, the reinforcement effect brought by D-clay is fairly significant at very low clay loadings probably owing to the strong interfacial interactions between the layered silicates and the compatibilizer as well as that between the compatibilizer and the PP matrix. The work demonstrates that D-clay is a type of promising nanofiller for thermoplastics used for outdoor applications since it stabilizes and reinforces the polymers simultaneously.

  11. Clay exfoliation and polymer/clay aerogels by supercritical carbon dioxide

    PubMed Central

    Longo, Simona; Mauro, Marco; Daniel, Christophe; Galimberti, Maurizio; Guerra, Gaetano

    2013-01-01

    Supercritical carbon dioxide (scCO2) treatments of a montmorillonite (MMT) intercalated with ammonium cations bearing two long hydrocarbon tails (organo-modified MMT, OMMT) led to OMMT exfoliation, with loss of the long-range order in the packing of the hydrocarbon tails and maintenance of the long-range order in the clay layers. The intercalated and the derived exfoliated OMMT have been deeply characterized, mainly by X-ray diffraction analyses. Monolithic composite aerogels, with large amounts of both intercalated and exfoliated OMMT and including the nanoporous-crystalline δ form of syndiotactic polystyrene (s-PS), have been prepared, by scCO2 extractions of s-PS-based gels. Also for high OMMT content, the gel and aerogel preparation procedures occur without re-aggregation of the exfoliated clay, which is instead observed for other kinds of polymer processing. Aerogels with the exfoliated OMMT have more even dispersion of the clay layers, higher elastic modulus and larger surface area than aerogels with the intercalated OMMT. Extremely light materials with relevant transport properties could be prepared. Moreover, s-PS-based aerogels with exfoliated OMMT could be helpful for the handling of exfoliated clay minerals. PMID:24790956

  12. Impact of Oriented Clay Particles on X-Ray Spectroscopy Analysis

    NASA Astrophysics Data System (ADS)

    Lim, A. J. M. S.; Syazwani, R. N.; Wijeyesekera, D. C.

    2016-07-01

    Understanding the engineering properties of the mineralogy and microfabic of clayey soils is very complex and thus very difficult for soil characterization. Micromechanics of soils recognize that the micro structure and mineralogy of clay have a significant influence on its engineering behaviour. To achieve a more reliable quantitative evaluation of clay mineralogy, a proper sample preparation technique for quantitative clay mineral analysis is necessary. This paper presents the quantitative evaluation of elemental analysis and chemical characterization of oriented and random oriented clay particles using X-ray spectroscopy. Three different types of clays namely marine clay, bentonite and kaolin clay were studied. The oriented samples were prepared by placing the dispersed clay in water and left to settle on porous ceramic tiles by applying a relatively weak suction through a vacuum pump. Images form a Scanning Electron Microscope (SEM) was also used to show the comparison between the orientation patterns of both the sample preparation techniques. From the quantitative analysis of the X-ray spectroscopy, oriented sampling method showed more accuracy in identifying mineral deposits, because it produced better peak intensity on the spectrum and more mineral content can be identified compared to randomly oriented samples.

  13. Modelling iron clay interactions in deep geological disposal conditions

    NASA Astrophysics Data System (ADS)

    Bildstein, O.; Trotignon, L.; Perronnet, M.; Jullien, M.

    In the context of deep geological disposal of high level radioactive wastes, the interactions between iron and clay-rich materials may lead to adverse transformations of clay minerals with a potential loss of confining properties such as swelling and capacity to exchange cations. Such transformations have been experimentally observed at temperatures starting at ca. 80 °C, where smectites contained in a mixture of bentonite and iron powder are transformed into iron-rich serpentine-type minerals. The reaction-transport code CRUNCH is used to investigate the iron-clay interactions at 50 °C over a period of 10,000 years, which are the conditions considered here to represent the mean temperature value and the expected timescale for the corrosion stage. The aim is to predict the nature and quantity of corrosion product, calculate the chemistry of water (essentially the pH) and the mineralogical transformation in the system containing the canister, an optional engineered barrier (bentonite) and the host-rock (argillite). The results of the calculations show that at the interface with the canister, where steel corrosion occurs, the iron is partly immobilized by the precipitation of iron oxides (essentially magnetite) and small amounts of siderite. The pH stabilizes at high values, between 10 and 11, at this location. In the bentonite or the argillite in contact with the container, the primary clay minerals are destabilized and iron-rich serpentine-like minerals precipitate as observed in the experiments (cronstedtite and berthierine). These minerals show low cation exchange and swelling capacities. The results also show that the interactions between iron and clay may lead to significant porosity changes in the system. A reduction of the porosity is predicted at the surface of the steel canister, due to the precipitation of iron oxides. Porosity increase is predicted in the clay material due to the dissolution of the primary clay minerals. The effect of these porosity

  14. Porous networks derived from synthetic polymer-clay complexes

    SciTech Connect

    Carrado, K.A.; Thiyagarajan, P.; Elder, D.L.

    1995-05-12

    Synthetic hectorites were hydrothermally crystallized with direct incorporation of a cationic polymer poly(dimethyl diallyl ammonium chloride) (PDDA), and two neutral cellulosic polymers hydroxypropyl methylcellulose (HPMC) and hydroxyethyl cellulose (HEC). Synthetic PDDA-hectorite displays the lowest d-spacing at 15.8 {Angstrom} along with less polymer incorporation (7.8 wt % organic) than the neutral polymers (18--22 wt % organic). Thermal analysis and small angle neutron scattering were used to further examine the polymer-clay systems. Clay platelets of the largest size and best stacking order occur when cationic PDDA polymer is used. PDDA also enhances these properties over the crystallites prepared for a control mineral, where no polymer is used. HEC acts to aggregate the silica, leaving less to react to form clay. The clay platelets which result from HEC are small, not stacked to a large degree, and oriented randomly. Neutral HPMC acts more like cationic PDDA in that larger clay platelets are allowed to form. The extended microstructure of the clay network remains undisturbed after polymer is removed by calcination. When no polymer is used, the synthetic hectorite has a N{sub 2} BET surface area of 200 M{sup 2}/gm, even after calcination. This increases by 20--50% for the synthetic polymer-hectorites after the polymer is removed by calcination.

  15. The geology and mineralogy of Ritchey crater, Mars: Evidence for post-Noachian clay formation

    NASA Astrophysics Data System (ADS)

    Sun, Vivian Z.; Milliken, Ralph E.

    2014-04-01

    Widespread detection of phyllosilicates (clay minerals) in Noachian (>3.5 Ga) terrains on Mars and their paucity in younger terrains have led to the hypothesis that Noachian conditions were more clement than the colder, drier conditions that have since followed. However, recent clay detections in several Hesperian impact craters suggest that fluvial transport and alteration were possible after the posited early era of phyllosilicate formation. Here we present evidence that rocks within Hesperian age Ritchey crater (28.5°S, 51°W) record a period of post-Noachian fluvial transport and in situ alteration. This resulted in the transport of clays from the crater wall to the crater floor and the formation of hydrated silica and Fe/Mg smectite in Ritchey's central uplift. Clay minerals associated with central uplifts are commonly interpreted to represent preexisting clays excavated from depth, potentially providing insight into older crustal clay-forming processes. Here we present detailed geomorphic and mineralogic maps and show that the clays in Ritchey's central peak formed after or as a direct result of the impact and are thus Hesperian or younger. Clays on the crater wall were either preexisting clays exposed by the impact or formed in situ through postimpact water-rock interaction. In either scenario, some of these clays were likely subsequently transported to the crater floor by fluvial-alluvial processes in a source-to-sink system. In this context, the hydrated phases in Ritchey indicate several different formation and transport mechanisms and provide further evidence that near-surface clay mineral formation, and thus habitable conditions, existed on Mars after the Noachian.

  16. Functionalized synthetic clays designed for polymer-clay nanocomposites

    NASA Astrophysics Data System (ADS)

    Chastek, Thuy Truong

    Polymer-clay nanocomposites have many advantageous properties such as their light weight, transparency, flame retardency, barrier properties, and low cost. Exfoliation of natural clays into commercially important non-polar polymers such as polystyrene (PS) and polypropylene (PP) melts has been limited due to the immiscibility of these polymers with highly polar clays. Current means of addressing this problem, such as treating clays with surfactants, has met with limited success. Motivated by the need for synthetic clays that can be dispersed and exfoliated in non-polar polymer melts without added compatibilizers, we synthesized lamellar silicates and aluminosilicates to act as clay analogs. The flexibility of the sol-gel syntheses allowed hexadecyl and isobutyl functional groups to be covalently attached to the surface of the clays. Incorporating a high content of octahedral aluminum also strengthened the clay layers. The strength and surface functionalities of the layered silicates improved exfoliation during melt blending with PS and PP. We studied the effects of clay layer composition (silicate and alumino-silicate), layer thickness, organic functional groups, aluminum coordination, and covalent linking of surfactants on the performance of the nanocomposites. The lamellar morphology was determined from XRD and TEM. Organic functionalization was determined with solid state NMR and IR spectroscopy. The synthetic clays were mixed with various solvents to help predict their miscibility with PS and PP. Composites were prepared with different molecular weight polymers, which subjected the clays to a wide range of shear stresses. The clays were also pretreated by mixing in a master batch or dispersing in an organic solvent. The effects of PS and PP molecular weight, master batch, and solvent dispersion on the exfoliation of synthetic clays in PS are examined. Rheology and TEM were used to observe the quality of exfoliation and the final aspect ratio of the clay layers

  17. Acid activation of bentonites and polymer-clay nanocomposites.

    SciTech Connect

    Carrado, K. A.; Komadel, P.; Center for Nanoscale Materials; Slovak Academy of Sciences

    2009-04-01

    Modified bentonites are of widespread technological importance. Common modifications include acid activation and organic treatment. Acid activation has been used for decades to prepare bleaching earths for adsorbing impurities from edible and industrial oils. Organic treatment has sparked an explosive interest in a class of materials called polymer-clay nanocomposites (PCNs). The most commonly used clay mineral in PCNs is montmorillonite, which is the main constituent of bentonite. PCN materials are used for structural reinforcement and mechanical strength, for gas permeability barriers, as flame retardants, and to minimize surface erosion (ablation). Other specialty applications include use as conducting nanocomposites and bionanocomposites.

  18. Investigating the Influence of Clay Mineralogy on Stream Bank Erodibility

    NASA Astrophysics Data System (ADS)

    Ambers, R. K.; Stine, M. B.

    2005-12-01

    Soil scientists concerned with erosion of agricultural fields and geotechnical engineers concerned with the mechanical behavior of soils under different conditions have both examined the role of clay mineralogy in controlling soil/sediment properties. Fluvial geomorphologists studying stream channel erosion and stability have focused more on the effects of particle-size distribution, vegetation and rooting. The clay mineralogy of bed and bank sediment has the potential to influence cohesiveness and erodibility, however. The goal of this study is to determine the influence of clay mineralogy on the erodibility of natural stream bank sediment, utilizing techniques drawn from pedology and soil mechanics. Bank samples were collected from eleven sites in small watersheds in central and western Virginia. To obtain sediment containing a range of different clay minerals, watersheds with different types of bedrock were chosen for sampling. Rock types included mafic to felsic metamorphic and igneous rocks, shale, sandstone, and limestone. Where stream bank materials were clearly stratified, different layers were sampled separately. X-ray diffraction of the clay-fraction of the sediment indicates the presence of kaolinite, illite, vermiculite, and mixed-layer clay minerals in various abundances in the different samples. Clay content is 9-46%, as determined by the hydrometer method, and textures range from silty clay and silt loam to clay loam and sandy loam. Organic mater contents range from 1-5% by the loss-on-ignition method. Bulk density of intact sediment samples averages 1.5 g/cc. Liquid limits range from 23-41 with one sample having a value of 65; plasticity indices range from 15-22. While these tests predict that the samples would show a range of mechanical behaviors, the channel morphology at the sampling sites was not strikingly different, all having steep cut banks eroded primarily by scour with no evidence of mass movement and most having a width/depth ratio around

  19. Unraveling the antibacterial mode of action of a clay from the Colombian Amazon.

    PubMed

    Londono, Sandra Carolina; Williams, Lynda B

    2016-04-01

    Natural antibacterial clays can inhibit growth of human pathogens; therefore, understanding the antibacterial mode of action may lead to new applications for health. The antibacterial modes of action have shown differences based on mineralogical constraints. Here we investigate a natural clay from the Colombian Amazon (AMZ) known to the Uitoto natives as a healing clay. The physical and chemical properties of the AMZ clay were compared to standard reference materials: smectite (SWy-1) and kaolinite (API #5) that represent the major minerals in AMZ. We tested model Gram-negative (Escherichia coli ATCC #25922) and Gram-positive (Bacillus subtilis ATCC #6633) bacteria to assess the clay's antibacterial effectiveness against different bacterial types. The chemical and physical changes in the microbes were examined using bioimaging and mass spectrometry of clay digests and aqueous leachates. Results indicate that a single dose of AMZ clay (250 mg/mL) induced a 4-6 order of magnitude reduction in cell viability, unlike the reference clays that did not impact bacterial survival. AMZ clay possesses a relatively high specific surface area (51.23 m(2)/g) and much higher total surface area (278.82 m(2)/g) than the reference clays. In aqueous suspensions (50 mg clay/mL water), soluble metals are released and the minerals buffer fluid pH between 4.1 and 4.5. We propose that the clay facilitates chemical interactions detrimental to bacteria by absorbing nutrients (e.g., Mg, P) and potentially supplying metals (e.g., Al) toxic to bacteria. This study demonstrates that native traditional knowledge can direct scientific studies.

  20. CHEMICAL AND MINERALOGICAL CHARACTERISTICS OF FRENCH GREEN CLAYS USED FOR HEALING

    PubMed Central

    Williams, Lynda B.; Haydel, Shelley E.; Giese, Rossman F.; Eberl, Dennis D.

    2008-01-01

    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. PMID:19079803

  1. Does the preferential microbial colonisation of ferromagnesian minerals affect mineral weathering in soil?

    PubMed

    Wilson, Michael J; Certini, Giacomo; Campbell, Colin D; Anderson, Ian C; Hillier, Stephen

    2008-09-01

    Fungal activity is thought to play a direct and effective role in the breakdown and dissolution of primary minerals and in the synthesis of clay minerals in soil environments, with important consequences for plant growth and ecosystem functioning. We have studied primary mineral weathering in volcanic soils developed on trachydacite in southern Tuscany using a combination of qualitative and quantitative mineralogical and microbiological techniques. Specifically, we characterized the weathering and microbiological colonization of the magnetically separated ferromagnesian minerals (biotite and orthopyroxene) and non-ferromagnesian constituents (K-feldspar and volcanic glass) of the coarse sand fraction (250-1,000 microm). Our results show that in the basal horizons of the soils, the ferromagnesian minerals are much more intensively colonized by microorganisms than K-feldspar and glass, but that the composition of the microbial communities living on the two mineral fractions is similar. Moreover, X-ray diffraction, optical and scanning electron microscope observations show that although the ferromagnesian minerals are preferentially associated with an embryonic form of the clay mineral halloysite, they are still relatively fresh. We interpret our results as indicating that in this instance microbial activity, and particularly fungal activity, has not been an effective agent of mineral weathering, that the association with clay minerals is indirect, and that fungal weathering of primary minerals may not be as important a source of plant nutrients as previously claimed.

  2. Effect of red clay on diesel bioremediation and soil bacterial community.

    PubMed

    Jung, Jaejoon; Choi, Sungjong; Hong, Hyerim; Sung, Jung-Suk; Park, Woojun

    2014-08-01

    Red clay is a type of soil, the red color of which results from the presence of iron oxide. It is considered an eco-friendly material, with many industrial, cosmetic, and architectural uses. A patented method was applied to red clay in order to change its chemical composition and mineral bioavailability. The resulting product was designated processed red clay. This study evaluates the novel use of red clay and processed red clay as biostimulation agents in diesel-contaminated soils. Diesel biodegradation was enhanced in the presence of red clay and processed red clay by 4.9- and 6.7-fold, respectively, and the number of culturable bacterial cells was correlated with the amount of diesel biodegradation. The growth of Acinetobacter oleivorans DR1, Pseudomonas putida KT2440, and Cupriavidus necator was promoted by both types of red clays. Culture-independent community analysis determined via barcoded pyrosequencing indicated that Nocardioidaceae, Xanthomonadaceae, Pseudomonadaceae, and Caulobacteraceae were enriched by diesel contamination. Bacterial strain isolation from naphthalene- and liquid paraffin-amended media was affiliated with enriched taxa based on 16S rRNA gene sequence identity. We suggest that the biostimulating mechanism of red clay and processed red clay is able to support bacterial growth without apparent selection for specific bacterial species.

  3. Removal of waterborne microorganisms by filtration using clay-polymer complexes.

    PubMed

    Undabeytia, Tomas; Posada, Rosa; Nir, Shlomo; Galindo, Irene; Laiz, Leonila; Saiz-Jimenez, Cesareo; Morillo, Esmeralda

    2014-08-30

    Clay-polymer composites were designed for use in filtration processes for disinfection during the course of water purification. The composites were formed by sorption of polymers based on starch modified with quaternary ammonium ethers onto the negatively charged clay mineral bentonite. The performance of the clay-polymer complexes in removal of bacteria was strongly dependent on the conformation adopted by the polycation on the clay surface, the charge density of the polycation itself and the ratio between the concentrations of clay and polymer used during the sorption process. The antimicrobial effect exerted by the clay-polymer system was due to the cationic monomers adsorbed on the clay surface, which resulted in a positive surface potential of the complexes and charge reversal. Clay-polymer complexes were more toxic to bacteria than the polymers alone. Filtration employing our optimal clay-polymer composite yielded 100% removal of bacteria after the passage of 3L, whereas an equivalent filter with granular activated carbon (GAC) hardly yielded removal of bacteria after 0.5L. Regeneration of clay-polymer complexes saturated with bacteria was demonstrated. Modeling of the filtration processes permitted to optimize the design of filters and estimation of experimental conditions for purifying large water volumes in short periods.

  4. Removal of waterborne microorganisms by filtration using clay-polymer complexes.

    PubMed

    Undabeytia, Tomas; Posada, Rosa; Nir, Shlomo; Galindo, Irene; Laiz, Leonila; Saiz-Jimenez, Cesareo; Morillo, Esmeralda

    2014-08-30

    Clay-polymer composites were designed for use in filtration processes for disinfection during the course of water purification. The composites were formed by sorption of polymers based on starch modified with quaternary ammonium ethers onto the negatively charged clay mineral bentonite. The performance of the clay-polymer complexes in removal of bacteria was strongly dependent on the conformation adopted by the polycation on the clay surface, the charge density of the polycation itself and the ratio between the concentrations of clay and polymer used during the sorption process. The antimicrobial effect exerted by the clay-polymer system was due to the cationic monomers adsorbed on the clay surface, which resulted in a positive surface potential of the complexes and charge reversal. Clay-polymer complexes were more toxic to bacteria than the polymers alone. Filtration employing our optimal clay-polymer composite yielded 100% removal of bacteria after the passage of 3L, whereas an equivalent filter with granular activated carbon (GAC) hardly yielded removal of bacteria after 0.5L. Regeneration of clay-polymer complexes saturated with bacteria was demonstrated. Modeling of the filtration processes permitted to optimize the design of filters and estimation of experimental conditions for purifying large water volumes in short periods. PMID:25063930

  5. Clay mineralogy of Pleistocene Lake Tecopa, Inyo County, California

    USGS Publications Warehouse

    Starkey, Harry C.; Blackmon, Paul D.

    1979-01-01

    Pleistocene Lake Tecopa in southeastern Inyo County, Calif., was formed when the Amargosa River was blocked at the southern end of its valley. The lake acted as a settling basin for detrital material being transported by the river. This detritus consisted of clays, quartz, feldspars, and micas which became mudstones and siltstones. These mudstones and siltstones, much eroded and dissected after the draining of the lake, extend over the entire basin and are interbedded with tuffs formed by the intermittent deposition of volcanic ashfalls in the former lake waters. These lightcolored mudstones and siltstones are tough and well indurated and break with a conchoidal fracture. The predominant clay mineral in these detrital beds is a lithiumbearing saponite, which is found not only in the lake beds but also in the area beyond the boundaries of the lake, especially in fluvial deposits in the drainage basin of the Amargosa River to the north. This saponite does not contain enough lithium to be classified as a hectorite, and we have observed no indications that this clay consists of a mixture of two phases, such as hectorite and a diluent. Some authigenic dioctahedral montmorillonite, found only in small quantities close to the tuffs, was formed by alteration of the volcanic glass of the tuffs and was then admixed with the overlying or underlying detrital clays. The only authigenic clay-type mineral found in any significant quantity is sepiolite, found near the edges of the lake basin and stratigraphically located mainly within a meter of the two uppermost tuffs. This sepiolite probably was precipitated when silica became available to the magnesium-bearing lake water through dissolution of the volcanic ash. Precipitation of sepiolite probably did not occur within the tuffs owing to the presence of alumina in solution. Zeolites were produced there and sepiolite formed outside the margins of the tuffs. Also formed by the high-pH lake waters were water-soluble minerals, which

  6. [Kinetics and mechanism of removing Microcystis aeruginosa using clay flocculation].

    PubMed

    Pan, Gang; Zhang, Mingming; Yan, Hai; Zou, Hua; Chen, Hao

    2003-09-01

    Twenty-six natural clays were studied for their kinetics of flocculating and removing algal cells of Microcystis aeruginosa. According to the 8 h equilibrium removal efficiencies and removal rates at a clay-loading of 0.7 g.L-1, all the 26 clays were classified into three categories. Type-I clay, which includes talc, ferric oxide, sepiolite, ferroferric oxide, and kaolinite, has an equilibrium removal efficiency greater than 90%, a t50 (time needed to remove 50% of the algae) of less than 30 min, and a t80 (time needed to remove 80% of the algae) of less than 2.5 h. Type-II clay, which includes argillanceous rocks, attapulgite, rectorite, illite, and argil, etc., has an equilibrium removal efficiency of 50%-80%, a t50 of less than 2.5 h, and a t80 of more than 5 h. Type-III clay consists of 14 minerals, including laterite, zeolite, mica, clinoptilolite, pumice, tripoli, feldspar and quartz, etc. with the removal efficiency less than 50%, and t50 > > 8 h. When the clay loading was decreased to 0.1-0.2 g.L-1, the 8 h equilibrium removal efficiencies for 25 clays declined to below 60%, except for sepiolite, a Type-I clay, which maintained around 90%. After the sepiolite was modified with Fe3+ to increase its surface charge (Zeta potential from -24.0 mV to +0.43 mV at pH 7.4), the initial removal rate was increased remarkably although its 8 h equilibrium removal efficiency was not improved substantially. As a comparison, the 8 h equilibrium removal efficiency of PAC was no greater than 40% at loadings of 0.02-0.2 g.L-1. Following the analysis of the flocculation mechanism it was concluded that the effect of bridging and netting may play a key role in the clay-algae flocculation processes, which may be important for selecting and modifying clays to improve significantly the removal efficiency. PMID:14719252

  7. [Kinetics and mechanism of removing Microcystis aeruginosa using clay flocculation].

    PubMed

    Pan, Gang; Zhang, Mingming; Yan, Hai; Zou, Hua; Chen, Hao

    2003-09-01

    Twenty-six natural clays were studied for their kinetics of flocculating and removing algal cells of Microcystis aeruginosa. According to the 8 h equilibrium removal efficiencies and removal rates at a clay-loading of 0.7 g.L-1, all the 26 clays were classified into three categories. Type-I clay, which includes talc, ferric oxide, sepiolite, ferroferric oxide, and kaolinite, has an equilibrium removal efficiency greater than 90%, a t50 (time needed to remove 50% of the algae) of less than 30 min, and a t80 (time needed to remove 80% of the algae) of less than 2.5 h. Type-II clay, which includes argillanceous rocks, attapulgite, rectorite, illite, and argil, etc., has an equilibrium removal efficiency of 50%-80%, a t50 of less than 2.5 h, and a t80 of more than 5 h. Type-III clay consists of 14 minerals, including laterite, zeolite, mica, clinoptilolite, pumice, tripoli, feldspar and quartz, etc. with the removal efficiency less than 50%, and t50 > > 8 h. When the clay loading was decreased to 0.1-0.2 g.L-1, the 8 h equilibrium removal efficiencies for 25 clays declined to below 60%, except for sepiolite, a Type-I clay, which maintained around 90%. After the sepiolite was modified with Fe3+ to increase its surface charge (Zeta potential from -24.0 mV to +0.43 mV at pH 7.4), the initial removal rate was increased remarkably although its 8 h equilibrium removal efficiency was not improved substantially. As a comparison, the 8 h equilibrium removal efficiency of PAC was no greater than 40% at loadings of 0.02-0.2 g.L-1. Following the analysis of the flocculation mechanism it was concluded that the effect of bridging and netting may play a key role in the clay-algae flocculation processes, which may be important for selecting and modifying clays to improve significantly the removal efficiency.

  8. Substantial iron sequestration during green-clay authigenesis in modern deep-sea sediments

    NASA Astrophysics Data System (ADS)

    Baldermann, A.; Warr, L. N.; Letofsky-Papst, I.; Mavromatis, V.

    2015-11-01

    In much of the global ocean, iron is a limiting nutrient for marine productivity. The formation of pyrite has been considered the most important sink of reactive iron in modern, organic-rich sediments. However, clay mineral transformations can also lead to long-term sequestration of iron during late diagenesis and in hydrothermal settings. Here we present evidence for substantial iron sequestration during the early diagenetic formation of ferruginous clay minerals, also called green-clay authigenesis, in the deep-sea environment of the Ivory Coast-Ghana Marginal Ridge. Using high-resolution electron microscopic methods and sequential sediment extraction techniques, we demonstrate that iron uptake by green-clay authigenesis can amount to 76 +/- 127 μmol Fe cm-2 kyr-1, which is on average six times higher than that of pyrite in suboxic subsurface sediments 5 m below the sea floor or shallower. Even at depths of 15 m below the sea floor or greater, rates of iron burial by green clay and pyrite are almost equal at ~80 μmol Fe cm-2 kyr-1. We conclude that green-clay formation significantly reduces the pore water inventory of dissolved iron in modern and ancient pelagic sediments, which challenges the long-standing conceptual view that clay mineral diagenesis is of little importance in current biogeochemical models of the marine iron cycle.

  9. Organic Pillared Clays.

    PubMed

    Meier, L. P.; Nueesch, R.; Madsen, F. T.

    2001-06-01

    Commonly used organophilic clays are modified by alkylammonium cations which hold apart the aluminosilicate layers permanently. The cations fill the interlayer space and are contemplated as flexible pillars, resulting from the mobility of the alkyl chains. Therefore, the interlayer distance varies depending on the layer charge and on the alkyl chain length. Contrary to these cations, rigid pillaring cations guarantee a constant interlayer distance without occupying the interlayer by themselves and show special adsorption properties such as hydrophilic behavior contrary to the generally hydrophobic ones. Smectites were modified by flexible organic cations, e.g., dimethyldioctadecylammonium, and by rigid ones, e.g., tetraphenylphosphonium. Their adsorption properties are compared. Our investigations showed improved adsorption properties for rigid organic cations on smectites using 2-chlorophenol as pollutant. Best adsorption results are achieved using pillaring cations in combination with low charged smectites, especially at low pollutant concentrations. The properties of organic modified smectites are discussed by a pollution intercalation model. The intercalation process of an organic pollutant into an organic modified smectite is expressed by a two-step Born-Haber cycle process: (i) the formation of an adsorbing position by layer expansion and (ii) the occupation of the adsorbing position by the pollutant. The first step of the formation of the adsorbing position is an endothermal transition state which lowers the total intercalation energy and therefore worsens the adsorption behavior. Thus, an already expanded organophilic smectite will show improved adsorption behavior. The formed adsorbing position state on organic modified smectites is comparable to the pillared state of inorganic pillared clays. Copyright 2001 Academic Press. PMID:11350131

  10. Radiocesium sorption in relation to clay mineralogy of paddy soils in Fukushima, Japan.

    PubMed

    Nakao, Atsushi; Ogasawara, Sho; Sano, Oki; Ito, Toyoaki; Yanai, Junta

    2014-01-15

    Relationships between Radiocesium Interception Potential (RIP) and mineralogical characteristics of the clay fraction isolated from 97 paddy soils (Hama-dori, n = 25; Naka-dori, n = 3