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1

Clay Minerals  

SciTech Connect

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 speci?c sites on the clay mineral surfaces, have aided in understanding the reactivity of these complex aluminosilicate systems.

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

2014-03-14

2

The Clay Minerals Society  

NSDL National Science Digital Library

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

3

Green Clay Minerals  

NASA Astrophysics Data System (ADS)

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 ?m 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 in the silicate (clay mineral in our case) structure, the specific bonding of these ions, and other factors. In fact, the reasons for coloration are not known completely, but it is certain that a combination of Fe2+ and Fe3+ ions is necessary to give a nice green color to clays. In the green clay minerals discussed here, the colors vary greatly as seen under the optical microscope (not always the same as the one seen in hand specimen). Yellow to blue-green hues can be found. However, for the moment, no clear relation between iron content, iron valence ratio, or other factors such as minor transition element concentrations can be found to explain the greenness of green clay minerals. The fact that a clay is green just indicates a combination of the two oxidation states of iron. The color, however, indicates the key to the formation in nature of green clay minerals.Green clay minerals are in general the product of "mixed valence" conditions of formation, most often in a situation where some iron is reduced from Fe3+ and enters into a silicate mineral structure. In general, iron would rather be an oxide when it is in the trivalent state. The moment iron is reduced to a divalent state under surface or near-surface conditions, it looks for a silicate, sulfide, or carbonate to hide in. The reverse is also true, of course. When a silicate is oxidized, Fe2+ becoming Fe3+, the iron begins to group together in oxide clumps and eventually exits the silicate structure. This is seen in thin section in altered rocks (weathering or hydrothermal action). The production of trivalent, oxidized iron usually results in a brownish or orange mineral.If the geology of the formation of green silicate minerals is relatively well defined, especially at near surface or surface conditions, the question remains how much of the iron is in a reduced oxidation state and how? In the case of reduction of iron in surface environments: if most of the iron goes to Fe2+, one mineral is formed; if only part of it is reduced, another is formed. This is the fundamental geochemical aspect of

Velde, B.

2003-12-01

4

Clay Mineral: Radiological Characterization  

NASA Astrophysics Data System (ADS)

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.

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

2008-08-01

5

Killer clays! Natural antibacterial clay minerals  

USGS Publications Warehouse

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.

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

2004-01-01

6

Clay Mineral: Radiological Characterization  

SciTech Connect

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.

Cotomacio, J. G. [Centro Universitario Nove de Julho, R: Diamantina, 602-Vila Maria, CEP: 02117-0101, Sao Paulo (Brazil); Silva, P. S. C. [Centro de Metrologia das Radiacoes-Instituto de Pesquisas Energeticas e Nucleares, Av. Prof. Lineu Prestes 2242-Cidade Universitaria-CEP 05508 000 Sao Paulo-Brazil (Brazil); Mazzilli, B. P

2008-08-07

7

Hyperspectral analysis of clay minerals  

NASA Astrophysics Data System (ADS)

A study was carried out by collecting soil samples from parts of Gwalior and Shivpuri district, Madhya Pradesh in order to assess the dominant clay mineral of these soils using hyperspectral data, as 0.4 to 2.5 ?m spectral range provides abundant and unique information about many important earth-surface minerals. Understanding the spectral response along with the soil chemical properties can provide important clues for retrieval of mineralogical soil properties. The soil samples were collected based on stratified random sampling approach and dominant clay minerals were identified through XRD analysis. The absorption feature parameters like depth, width, area and asymmetry of the absorption peaks were derived from spectral profile of soil samples through DISPEC tool. The derived absorption feature parameters were used as inputs for modelling the dominant soil clay mineral present in the unknown samples using Random forest approach which resulted in kappa accuracy of 0.795. Besides, an attempt was made to classify the Hyperion data using Spectral Angle Mapper (SAM) algorithm with an overall accuracy of 68.43 %. Results showed that kaolinite was the dominant mineral present in the soils followed by montmorillonite in the study area.

Janaki Rama Suresh, G.; Sreenivas, K.; Sivasamy, R.

2014-11-01

8

Elastic Properties of Clay Minerals  

NASA Astrophysics Data System (ADS)

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

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

2001-12-01

9

Elastic Properties of Clay Minerals  

NASA Astrophysics Data System (ADS)

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

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

10

Mineral resource of the Month: Clay  

USGS Publications Warehouse

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.

Virta, Robert L.

2010-01-01

11

PROGRAM AND ABSTRACTS FOR CLAY MINERALS SOCIETY  

E-print Network

r PROGRAM AND ABSTRACTS FOR CLAY MINERALS SOCIETY 28th ANNUAL MEETING NI\\SI\\National Aeronautit &II LPI #12;PROGRAM AND ABSTRACTS FOR CLAY MINERALS SOCIETY 28th ANNUAL MEETING Houston, Texas October contains abstracts that have been accepted for presentation at the Clay Minerals Society 28th Annual

Rathbun, Julie A.

12

Mineral resource of the month: clays  

USGS Publications Warehouse

Clays represent one of the largest mineral commodities in the world in terms of mineral and rock production and use. Many people, however, do not recognize that clays are used in an amazingly wide variety of applications. Use continues to increase worldwide as populations and their associated needs increase. Robert Virta, clay and shale commodity specialist for the U.S. Geological Survey, has prepared the following information about clays.

Virta, Robert

2004-01-01

13

Surface Geochemistry of the Clay Minerals  

NASA Astrophysics Data System (ADS)

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

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

1999-03-01

14

Electrokinetics of pure clay minerals revisited  

Microsoft Academic Search

Clay minerals have long attracted the attention of colloid scientists. This paper considers, specifically, their important role in the transport of various contaminants from land to sea, e.g., metal ions and organic detrital and man-made material in watercourses. Advance in experimental techniques have enabled precise characterization of clays and then electrokinetic experiments at high electrolyte concentrations, such as in seawater.

I. Sondi; J. Biscan; V. Pravdic

1996-01-01

15

Electrokinetics of Pure Clay Minerals Revisited  

Microsoft Academic Search

Clay minerals have long attracted the attention of colloid scientists. This paper considers, specifically, their important role in the transport of various contaminants from land to sea, e.g., metal ions and organic detrital and man-made material in watercourses. Advances in experimental techniques have enabled precise characterization of clays and then electrokinetic experiments at high electrolyte concentrations, such as in seawater.

Ivan Sondi; Jasenka Biš?an; Velimir Pravdi?

1996-01-01

16

Ostwald ripening of clays and metamorphic minerals  

USGS Publications Warehouse

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.

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

1990-01-01

17

Metachromasy in clay mineral systems  

Microsoft Academic Search

Adsorption of the metachromic (colour depends on concentration) cationic dyes crystal violet (CV) and ethyl violet (EV) by Na-kaolinite and Na-montmorillonite has been studied by visible spectroscopy and titration calorimetry. In the kaolinite system, metachromasy stems from association of the dye cations on the external surface of the clay. Enthalpies of adsorption at small dye\\/clay ratios are ?3.5 and ?3.8

C. Dobrogowska; L. G. Hepler; D. K. Ghosh; Sh. Yariv

1991-01-01

18

Understanding clay minerals with fuzzy mathematics.  

PubMed

A long-existing geochemical problem is the lack of a means of chemically defining non-stoichiometric complex minerals such as clays, which have no distinct composition and no clear compositional boundaries. We propose here a novel approach for describing the chemical nature of clay minerals using fuzzy logic. This non-conventional mathematical approach allows us to quantify compositional vagueness in such systems. We show that a clay mineral can be described in terms of how compositionally representative it is, of its own type ("belonging-ness") and to what extent it resembles other types (compositional overlap). Many clay minerals are seen to be far from the ideal, and most minerals are also to a lesser (and sometimes greater) extent, close to types other than their own. This has provided a means of grading such minerals, evaluating how "good" a sample is, and defining the extent of transition to other phases. We have derived here the fundamental methodology for such computations, which could be a framework for the analysis of other complex chemical systems, especially in the fields of geology and metallurgy. PMID:12545244

Varadachari, Chandrika; Mukherjee, Gargi; Goswami, Damodar P; Chakraborty, Mihir K

2003-01-01

19

Release kinetics of volatiles from clay minerals  

NASA Astrophysics Data System (ADS)

Smectite clay minerals are known to have interesting sorption properties, but the prediction of the kinetics of desorption of volatile molecules from such clays remains a challenge. The aim of this work is to relate the isothermal rate of desorption of volatile molecules from cation exchanged smectite clays to the chemical structures and geometries of the interacting species (clay platelet surface, type of counter-ion, type of volatile). It is thought that the rate of desorption of the volatiles at a given time is governed by their instantaneous diffusion in the clay and in the gas phase, which in turns is dependent on the volatile's interaction with its chemical and geometrical environment. Therefore, in addition to isothermal desorption rate measurements by thermogravimetry, activation energies of desorption are measured and calculated and the interacting compounds are characterized in terms of their chemical structure and geometry.

Clausen, Pascal

2007-03-01

20

Clays and other minerals in prebiotic processes  

NASA Technical Reports Server (NTRS)

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.

Paecht-Horowitz, M.

1984-01-01

21

The Link between Clay Mineral Weathering and the Stabilization of  

E-print Network

The Link between Clay Mineral Weathering and the Stabilization of Ni Surface Precipitates R O B E R of the observed increase in dissolution resistance. Thus, clay mineral weathering and the time-dependent release was derived from weathering of the clay mineral surface. A time-dependent extended X

Sparks, Donald L.

22

Clay Mineral Formation and Transformation in Rocks and Soils  

Microsoft Academic Search

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

D. D. Eberl; V. C. Farmer; R. M. Barrer

1984-01-01

23

The oxygen and hydrogen isotope geochemistry of clay minerals  

Microsoft Academic Search

Oxygen and hydrogen isotope analyses have been made on a variety of clay minerals of sedimentary and diagenetic origins. The interlayer water of clay minerals was found to exchange rapidly with atmospheric water. Conditions under which the interlayer water could be removed from the clays without affecting the isotopic compositions of their aluminosilicate oxygen and hydrogen were therefore determined, and

Samuel M. Savin; Samuel Epstein

1970-01-01

24

The Origin and Fate of Clay Minerals on Mars  

NASA Astrophysics Data System (ADS)

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 the net decrease in the available amount of water through time would make it easier to maintain local acidity. Acidic conditions would be promoted in regions with limited water close to sources of S- and Cl-bearing volcanic gases. Conversely, locations with abundant water poor in Fe(II) and distal to volcanic sources would evolve towards more moderate pH levels and would be capable of nondestructive transport and/or formation of clay minerals during the Hesperian. This scenario is consistent with the presence of clays in several Hesperian-aged terrains, suggesting that acidic conditions were not global during this time. Martian clays would also be susceptible to burial diagenesis, and the survival of numerous smectite-bearing outcrops on Mars over several billion years suggests limited interaction with fluids over this timescale, providing a natural case study for long-term smectite stability. In summary, the apparent spatial-temporal distribution of clays (and sulfates) on Mars may not reflect a global temporal change from alkaline to acidic conditions as much as it reflects spatial variations in the local volume, availability, and Fe(II) concentration of near-surface water.

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

2009-12-01

25

Review Article Clay and non-clay minerals in the pharmaceutical and cosmetic industries  

E-print Network

Review Article Clay and non-clay minerals in the pharmaceutical and cosmetic industries Part II Pharmaceutical industry Cosmetic industry Active ingredients Physical and physico-chemical properties A wide cases the LADME process of the minerals is described. In the cosmetic industry minerals are used

Ahmad, Sajjad

26

Prolonged triboluminescence in clays and other minerals  

NASA Technical Reports Server (NTRS)

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.

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

1982-01-01

27

Analysis of mixed-layer clay mineral structures  

USGS Publications Warehouse

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.

Bradley, W.F.

1953-01-01

28

Clay mineral formation and transformation in rocks and soils  

USGS Publications Warehouse

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

Eberl, D.D.

1983-01-01

29

Elastic properties of dry clay mineral aggregates, suspensions and sandstones  

NASA Astrophysics Data System (ADS)

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

Vanorio, Tiziana; Prasad, Manika; Nur, Amos

2003-10-01

30

Microbe-Clay Mineral Reactions and Characterization Techniques  

NASA Astrophysics Data System (ADS)

Clays and clay minerals are ubiquitous in soils, sediments, and sedimentary rocks. They play an important role in environmental processes such as nutrient cycling, plant growth, contaminant migration, organic matter maturation, and petroleum production. The changes in the oxidation state of the structural iron in clay minerals, in part, control their physical and chemical properties in natural environments, such as clay particle flocculation, dispersion, swelling, hydraulic conductivity, surface area, cation and anion exchange capacity, and reactivity towards organic and inorganic contaminants. The structural ferric iron [Fe(III)] in clay minerals can be reduced either chemically or biologically. Many different chemical reductants have been tried, but the most commonly used agent is dithionite. Biological reductants are bacteria, including dissimilatory iron reducing prokaryotes (DIRP) and sulfate-reducing bacteria (SRB). A wide variety of DIRP have been used to reduce ferric iron in clay minerals, including mesophilic, thermophilic, and hyperthermophilic prokaryotes. Multiple clay minerals have been used for microbial reduction studies, including smectite, nontronite (iron-rich smectite variety), illite, illite/smectite, chlorite, and their various mixtures. All these clay minerals are reducible by microorganisms under various conditions with smectite (nontronite) being the most reducible. The reduction extent and rate of ferric iron in clay minerals are measured by wet chemistry, and the reduced clay mineral products are typically characterized with chemical methods, X-ray diffraction, scanning and transmission electron microscopy, Mössbauer spectroscopy, Fourier Transform Infrared Spectroscopy (FTIR), UV-vis spectroscopy, and synchrotron-based techniques (such as EXAFS). Microbially reduced smectites (nontronites) have been found to be reactive in reducing a variety of organic and inorganic contaminants. Degradable organic contaminants include pesticides, solvents, explosives, and nitroaromatic and polychlorinated compounds. Inorganic contaminants include Cr(VI), U(VI), and Tc(VII). Despite significant efforts, our understanding of mechanisms of chemical and microbial reduction of ferric iron in clay minerals is still limited. While some studies have presented evidence for a solid-state reduction mechanism, others argue that the clay mineral structure dissolves when the extent of reduction is higher (greater than 30 percent). The electron transfer process is also dependent on the reducing agent. While chemical reduction of ferric iron appears to occur at the basal surfaces, bacteria appear to attack clay minerals at the edges.

Dong, H.; Zhang, G.; Ji, S.; Jaisi, D.; Kim, J.

2008-12-01

31

Introduction to the properties of clay minerals  

NSDL National Science Digital Library

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

stephen Guggenheim

32

Enhance decarboxylation reaction of carboxylic acids in clay minerals.  

NASA Astrophysics Data System (ADS)

Clay minerals are important constituents of the Earth's crust. These minerals catalyze reactions in several ways: by energy transfer processes, redox reactions, stabilization of intermediates and by Brønsted or Lewis acidity behavior. Important set of organic reactions can be improved in the precedence of clay minerals. Besides the properties of clays to catalyze chemical reactions, it is possible to enhance some of its reactions by using ionizing radiation. The phenomenon of radiation-induced catalysis may be connected with ionizing process in the solid and with the trapped non-equilibrium charge cariers. In this paper we are reporting the decarboxylation reaction of carboxylic acids catalyzed by clay and by irradiation of the system acid-clay. We studied the behaviour of several carboxylic acids and analyzed them by gas chromatography, X ray and infrared spectroscopy. The results showed that decarboxylation of the target compound is the dominating pathway. The reaction is enhance by gamma radiation in several orders of magnitude.

Negrón-Mendoza, A.; Ramos, S.; Albarrán, G.

1995-02-01

33

Clay Minerals of Lake Abert, an Alkaline, Saline Lake  

Microsoft Academic Search

Mineralogical and chemical analyses of fine clay fractions from in and around Lake Abert, Lake County, Oregon, show that the pyroclastic rocks supplying detritus to the lake weather to a suite of layer silicate clay minerals varying from high-charge dioctahedral montmorillonite to montmorillonite\\/intergrade smectite-chlorite interstratifications. In the lake these clays extract K, Mg, and Si to form authigenic in- terstratified

Blair F. Jones; ALAN H. WEIR

1983-01-01

34

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

NASA Astrophysics Data System (ADS)

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

Brookins, D. G.

1982-03-01

35

Adsorption coefficients for TNT on soil and clay minerals  

NASA Astrophysics Data System (ADS)

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.

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

2007-04-01

36

Fluoride content of clay minerals and argillaceous earth materials  

USGS Publications Warehouse

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.

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

1977-01-01

37

Organic Complexing in Smectite Clay Minerals Under Hydrothermal Vent Conditions  

NASA Astrophysics Data System (ADS)

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

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

2002-12-01

38

Immersion Freezing of Clay Minerals and its Time Dependence  

NASA Astrophysics Data System (ADS)

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.

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

39

First Direct Detection of Clay Minerals on Mars  

NASA Technical Reports Server (NTRS)

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.

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

1985-01-01

40

Iodide interactions with clay minerals: Batch and diffusion studies  

NASA Astrophysics Data System (ADS)

Clay minerals are likely candidates to aid in nuclear waste isolation due to their low permeability, favorable swelling properties, and high cation sorption capacities. Iodine-129 is often the major driver of exposure risk from nuclear waste repositories at timescales >10,000 years. Therefore, understanding the geochemical cycling of iodine in clays is critical in developing defensible quantitative descriptions of nuclear waste disposal. Anions are not typically considered to interact with most clays as it is assumed that the fixed negative charge of clays actively repels the dissoloved anion. This is corroborated by many batch studies, but diffusion experiments in compacted clays have shown iodide retardation relative to chloride. The reasons for this are unknown; however, several possible hypotheses include: redox transformation controls on sorption behavior, complex surface charge environments due to overlapping charge domains, and sorption to ancillary minerals or weathering products. Seven different clay minerals have been examined using several techniques to chracterize the surface charge environment and iodide uptake. The use of a series of clays shifts the independent variable away from water chemistry characteristics (pH, contaminant concentration), and toward structural characterisitics of clay minerals including isomorphous substitution and clay texture. Iodide uptake batch experiments were completed with the clay minerals in a range of swamping electrolytes. The results give evidence for a novel uptake mechanism involving ion pair formation and iodide concentration within nano-confined environments. These results were further tested using diffusional columns where nano-confined regimes make up a larger proportion of the total porosity. These columns were compacted to different hydrostatic pressures and saturated with different ionic compositions. Porosity distributions were characterized with a fluoride tracer. Iodide diffusion characteristics were found to be dependent on ionic composition and confining pressure. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corperation, for the U.S. Department of Energy's Nation Nuclear Security Administration under contract DE-AC04-94AL85000.

Miller, A. W.; Kruichak, J.; Mills, M.; Wang, Y.

2012-12-01

41

Heteroaggregation of Silver Nanoparticles with Clay Minerals in Aqueous System  

NASA Astrophysics Data System (ADS)

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 Tween-coated silver nanoparticles showed high stability in both single and binary systems. There were no significant differences in early stage aggregation kinetics observed inthe Na-clay-nanoparticle or Ca-clay-nanoparticle systems, which suggested that the CCC values of the single Na- or Ca-clay suspensions depend only on the electrolyte concentration, not the original cations on the clay surface. These results provide a basic idea for understanding the heteroaggregation of different silver nanoparticles and clays, which can be utilized in further study of fate and transport of engineered nanoparticles in natural aqueous system.

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

2013-12-01

42

Removal of diphenhydramine from water by swelling clay minerals.  

PubMed

Frequent detection of pharmaceuticals in surface water and wastewater attracted renewed attention on studying interactions between pharmaceuticals and sludge or biosolids generated from wastewater treatment. Less attention was focused on studying interactions between pharmaceuticals and clay minerals, important soil and sediment components. This research targeted on investigating interactions between diphenhydramine (DPH), an important antihistamine drug, and a montmorillonite, a swelling clay, in aqueous solution. Stoichiometric desorption of exchangeable cations accompanying DPH adsorption confirmed that cation exchange was the most important mechanism of DPH uptake by the swelling clay. When the solution pH was below the pK(a) of DPH, its adsorption on the swelling clay was less affected by pH. Increasing solution pH above the pK(a) value resulted in a decrease in DPH adsorption by the clay. An increase in d(001) spacing at a high DPH loading level suggested interlayer adsorption, thus, intercalation of DPH. The results from this study showed that swelling clays are a good environmental sink for weak acidic drugs like DPH. In addition, the large cation exchange capacity and surface area make the clay a good candidate to remove cationic pharmaceuticals from the effluent of wastewater treatment facilities. PMID:21570085

Li, Zhaohui; Chang, Po-Hsiang; Jiang, Wei-Teh; Jean, Jiin-Shuh; Hong, Hanlie; Liao, Libing

2011-08-01

43

Fibrous-clay mineral formation and soil evolution in Aridisols of northeastern Patagonia, Argentina  

E-print Network

, palygorskite is the dominant clay mineral. Pedogenetic carbonate was qualified as low- Mg calcite, indicatingFibrous-clay mineral formation and soil evolution in Aridisols of northeastern Patagonia, Argentina Patagonia identified fibrous-clay minerals in calcic and petrocalcic horizons developed on old fluvio

Ahmad, Sajjad

44

Clay Minerals as Indicators of Sediment Source in Tidal Estuaries of Long Island Sound  

Microsoft Academic Search

Clay minerals were used as indicators for determining the source of sediment in recently dredged harbors along the north shore of Long Island Sound. Amount and characteristics of clay minerals in sediments from the dredged channels were compared to their amount and characteristics in the surrounding soils and in sediments from Long Island Sound. Clay minerals in sediments from the

B. L. Sawhney; C. R. FRINK

1978-01-01

45

Interaction of Chlordimeform with Clay Minerals  

Microsoft Academic Search

The adsorption-desorption of the cationic pesticide chlordimeform from aqueous solutions on montmorillonite, kaolinite, illite, and vermiculite appears to be a cation-exchange process coupled with the coadsorption of neutral molecules and the extraction of AI from the structure of the mineral. Chlordimeform adsorption on montmorillonite, illite, and vermiculite by cation exchange is an irreversible process, where- as chlordimeform adsorbed on kaolinite

Maria C. Hermosin; J. L. PEREZ RODRIGUEZ

1981-01-01

46

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

SciTech Connect

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.

Brookins, D.G. [Univ. of New Mexico, Albuquerque, NM (US). Dept. of Geology

1993-06-01

47

Adsorption of diethyl phthalate ester to clay minerals.  

PubMed

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>0.26mM). The calculated adsorption enthalpy (?Hobs) 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. PMID:25150972

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

2015-01-01

48

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

PubMed

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. PMID:19425352

Na?mark, E B; Eroshchev-Shak, V A; Chizhikova, N P; Kompantseva, E I

2009-01-01

49

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

NASA Astrophysics Data System (ADS)

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 samples. These confirmed that CO2 enters the interlayer spaces of monohydrated (D2O) smectites exchanged with Ca. The changes were proven to be fully reversible and mainly take place between 0 and 60 bar CO2. For a smectite exchanged with (CuTrien)2+ a decrease in intensity of the basal reflections with pressure was recorded, but no expansion of the basal spacing was observed. For kaolinite, similar changes in intensity upon CO2 addition were observed, but they correspond to a relative decrease of the intensity of the hk reflections. Measurements on illite yielded an unexpected increase in intensity of the basal reflections upon CO2 charging.

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

2013-04-01

50

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

NASA Astrophysics Data System (ADS)

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 ion population of a 2:1 clay structure. However the differences in interlayer ion chemistry give us such mineral names as chloritic hydroxyinterlayered mineral (Mg, OH interlayer), illite (K interlayer), and smectite (essentially hydrated Ca interlayer ions). Extraction of these interlayer ions can be reversed by chemistry engendered by plant regimes.

Barré, P.; Velde, B.

2012-04-01

51

Clay minerals in surface sediment of the north Yellow Sea and their implication to provenance and transportation  

NASA Astrophysics Data System (ADS)

The clay minerals in surface sediments of the north Yellow Sea have been identified with X-ray diffraction analysis and scanning electron microscope and energy dispersive X-ray spectrometer analysis to constrain the provenance and sediment transportation system in the area. Illite, with an average abundance of 58%, is the dominant mineral, followed by smectite (20% on average), chlorite (16% on average) and kaolinite (6% on average). The result of the a K-mean clustering analysis for the clay minerals show a close relationship between sedimentary types and clay mineral assemblages: there is more kaolinite and smectite in the muddy area in the western part of the north Yellow Sea and more chlorite in the sandy area in the eastern part. The Huanghe (Yellow River) is considered to provide most of the clay minerals, and in particular, rich kaolinite and smectite to the muddy area, whereas the Yalujiang provides large amounts of illite and chlorite. The spatial distribution characteristics of the clay minerals are closely related with the local circulation system, including the Shandong Coastal Current and Yellow Sea Warm Current. The former transports the outflow of the Huanghe to the north Yellow Sea, whereas the intrusion of the latter in wintertime is responsible for the annular enrichment of smectite in central part, as well as poor classification near Dalian Bay.

Li, Yan; Li, An-Chun; Huang, Peng; Xu, Fang-Jian; Zheng, Xu-Feng

2014-11-01

52

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

NASA Astrophysics Data System (ADS)

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.

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

2012-12-01

53

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

NASA Astrophysics Data System (ADS)

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

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

2011-09-01

54

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

NASA Astrophysics Data System (ADS)

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

Kostka, Joel E.; Wu, Jun; Nealson, Kenneth H.; Stucki, Joseph W.

1999-11-01

55

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

PubMed

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%). PMID:24617079

Kang, Il-Mo; Roh, Ki-Min

2013-01-01

56

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

SciTech Connect

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

Patricia A. Maurice

2010-02-08

57

Adsorption and separation of proteins by a smectitic clay mineral.  

PubMed

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

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

2010-09-01

58

Radiolysis of alanine adsorbed in a clay mineral  

SciTech Connect

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.

Aguilar-Ovando, Ellen Y.; Negron-Mendoza, Alicia [Instituto de Ciencias Nucleares, Universidad Nacional Autonoma de Mexico (UNAM), Circuito Exterior s/n, Ciudad Universitaria, Apartado Postal 70-543, Deleg. Coyoacan, C.P. 04510 (Mexico)

2013-07-03

59

Role of clay minerals in the transportation of iron  

USGS Publications Warehouse

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 seems to be necessary for maintaining reducing conditions in the environments studied. ?? 1958.

Carroll, D.

1958-01-01

60

Effects of clay mineral turbidity on dissolved organic carbon and bacterial production  

Microsoft Academic Search

Effects of inorganic turbidity from clay minerals on allochthonous dissolved organic matter (DOM), its consumption by bacteria and photodegradation by solar radiation were investigated. In controlled experiments of adsorption of DOM of six specific leaf leachates onto montmorillonite, kaolinite, and clay extracted from drainage basin soil, up to 31 mg C of leaf leachate was adsorbed g clay ?1. A suspension

Todd Tietjen; Anssi V. Vähätalo; Robert G. Wetzel

2005-01-01

61

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

PubMed

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

Samuels, Maya; Mor, Omer; Rytwo, Giora

2013-04-01

62

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

PubMed

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

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

2008-09-15

63

20. MINERALOGY AND ORIGIN OF CLAY MINERALS, SILICA AND AUTHIGENIC SILICATES IN LEG 14 SEDIMENTS  

Microsoft Academic Search

Preliminary X-ray, SEM, TEM, and optical mineralogical results are reported to discuss the paragenesis, age distribution, and origin of clay minerals, silica modifications and authigenic silicates found in nine drilling sites of Leg 14 of the Deep Sea Drilling Project, located off northwestern Africa and northeastern South America. Most noncarbonate minerals are diagenetic alteration products of volcanic ashes. Continent-derived clay

Ulrich von Rad; Heinrich Rösch

64

Heterogeneous Reactions of Gaseous Nitric Acid and Nitrogen Dioxide on the Clay Minerals Kaolinite and Pyrophyllite  

Microsoft Academic Search

Airborne clay mineral particles undergo long-range transport because of their small size. As a consequence, heterogeneous reactions on these particles may impact tropospheric photochemical cycles. Diffuse reflectance infrared spectroscopy provided identification of surface adsorbed products formed from the uptake of gaseous nitric acid and nitrogen dioxide on the prototype clay minerals kaolinite and pyrophyllite. The reaction of HNO3 on kaolinite

R. Z. Hinrichs; M. M. Angelini

2006-01-01

65

MINERAL CHARACTERIZATION IN GEOSYNTHETIC CLAY LINERS USING MICRO-XRAY DIFFRACTION  

Microsoft Academic Search

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

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

66

Cation exchange dynamics confined in a synthetic clay mineral  

NASA Astrophysics Data System (ADS)

In this work we report X-Ray Diffraction (XRD) and Energy Dispersive X-Ray Spectroscopy (EDS) measurements to investigate the confined cation exchange process in saline aqueous suspensions of a synthetic clay mineral from Lithium-Fluorohectorite to Nickel-Fluorohectorite, as well as the reverse process from Nickel-Fluorohectorite to Lithium-Fluorohectorite and also from Lithium-Fluorohectorite to Sodium-Fluorohectorite. The dynamics of these cation exchanges was followed and it was observed that these processes can be faster than 1 minute. The results are compared to the observations on samples prepared by cation exchange procedures for which the exchange process was performed on the time-scale of months.

Grassi, G.; Michels, L.; Rozynek, Z.; Altoé, M. A. S.; dos Santos, E. C.; da Fonseca, C. L. S.; Droppa, R.; Gholamipour-Shirazi, A.; Fossum, J. O.; da Silva, G. J.

2014-09-01

67

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

SciTech Connect

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.

Monaghan, G.W. (Geocomp Research, Eaton, NY (United States)); Larson, G.J. (Michigan State Univ., East Lansing, MI (United States). Dept. of Geological Sciences)

1994-04-01

68

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

USGS Publications Warehouse

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.

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

1971-01-01

69

Interactions of clay minerals with Arthrobacter crystallopoietes: starvation, survival and 2-hydroxypyridine catabolism  

Microsoft Academic Search

For bacterial inoculants to be effective in soil remediation, the bacterial strain must be capable of overcoming any negative\\u000a effects of soil minerals on cellular processes. One class of minerals commonly encountered by soil bacteria is clays. Thus,\\u000a the effect of commonly occurring clay minerals in soils on starvation, survival and 2-hydroxypyridine catabolism by Arthrobacter crystallopoietes was evaluated. Stationary phase

S. Hwang

1997-01-01

70

Determining Mineral Types and Abundances from Reflectance Measurements  

NASA Technical Reports Server (NTRS)

Mineral types and their abundances were quantitatively determined from laboratory reflectance spectra using principal components analysis (PCA). PCA reduced the measured spectral dimensionality and allowed testing the uniqueness and validity of spectral mixing models. In addition to interpreting absorption bands, in this new approach we interpreted variations in the overall spectral curves in terms of physical processes, namely changes in mixtures of minerals, in particle size and in illumination geometry. Application of this approach to reflectances of planetary surfaces allows interpretation to be extended to quantitative determinations of mineral types and abundances.

Smith, M. O.; Adams, J. B.

1985-01-01

71

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

NASA Technical Reports Server (NTRS)

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.

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

1994-01-01

72

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

NASA Astrophysics Data System (ADS)

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.

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

2015-01-01

73

Clay minerals and geochemistry of the bottom sediments in the northwestern East China Sea  

NASA Astrophysics Data System (ADS)

Clay minerals of 34 sediments collected from the northwestern continental shelf of the East China Sea have been determined by X-ray diffraction analysis. The clay mineral distribution is mainly controlled by the sediment source and the dominant circulation pattern. The predominant clay mineral in our study area is illite comprising more than 67% of the whole clay fraction. The highest concentration of illite (>68%) is found in the southeastern offshore parts beyond the reach of terrigenous input from the Jeju Island. It means that these illites are largely transported by the Kuroshio Current from the South China Sea (SCS). Smectite is highly concentrated in the northwest middle part and in the outer-shelf mud patch. It seems to be due to the high supply of smectite transported from China where fine-grained sediments are discharged from modern and ancient Huanghe (Yellow) River. The relatively high abundant kaolinite is likely derived from the Changjiang (Yangtze) River via the Taiwan Warm Current. In contrast, large amounts of chlorite and high chlorite/kaolinite ratios occur in the northwestern area, reflecting the transportation by the Yellow Sea Coastal Current from the southern Yellow Sea. The discrimination diagrams clearly show that the sediments in the northwestern East China Sea are ultimately sourced from Chinese rivers, especially from the Huanghe River, whereas the sediment in the northeast part might come from the Jeju Island. The muddy sediments of the Changjiang River’s submerged delta have much lower 87Sr/86Sr ratios (0.716 2-0.718 0) than those of the Shandong Peninsular mud wedge (0.721 6-0.724 9), which are supposed to be originated from the Huanghe River, suggesting the distribution pattern of 87Sr/86Sr ratios as a new tracer to discriminate the provenance of shelf sediments in the study area. The 87Sr/86Sr ratios of the outer-shelf muddy sediments ranged from 0.7169 to 0.7216 in a wide range and was between those of the Huanghe River and Changjiang River sediments, suggesting multiple sources of the sediment in the area.

Youn, Jeungsu; Yang, Shouye; Park, Yong Ahn

2007-07-01

74

Lithium, a preliminary survey of its mineral occurrence in flint clay and related rock types in the United States  

USGS Publications Warehouse

Maximum concentrations of lithium found in samples of flint clay and associated rocks of Pennsylvanian age in different States, in parts per million (ppm), are: Missouri, 5100; Pennsylvania-Maryland, 2100; Kentucky, 890; Ohio, 660; Alabama, 750; and Illinois, 160. Lithium-bearing kaolin deposits are distributed in the Coastal Plain province from New Jersey to Texas, and one occurs in Idaho; maximum lithium concentrations in samples from these deposits range from 64 to 180 ppm. The maximum concentration found in the Arkansas bauxite region is 460 ppm and that in flint clay in Colorado is 370 ppm. Samples from areas other than Pennsylvania, Maryland, Kentucky and Missouri are relatively few in number, represent mostly commercially valuable clays, and represent only a part of the refractory clay deposits in the United States. Data are not available on the clays associated with these deposits that may be unusable because they contain too much lithium as well as other deleterious elements. In both Pennsylvania and Missouri, lithium contents vary regionally between districts and locally between deposits. In samples containing more than 2000 ppm lithium, the lithium occurs in a dioctahedral chlorite mineral very similar to cookeite, which previously has not been recognized in sedimentary clays. The associated clays consist chiefly of well-crystallized kaolinite. The dioctahedral chlorite, however, seems to be most abundant where diaspore and boehmite occur along with the kaolinite. Barium, chromium, copper, phosphorus and strontium are present in some samples in amounts of several hundred pans per million or more, and may contribute to the failure of some clays to perform satisfactorily in firing tests. Lithium-rich clays could serve as a significant lithium resource in the very distant future. Clays that contain as much as 1% lithium may be common enough in Missouri or in Pennsylvania to be produced as a by-product to help support benefication costs for refractory clays. Sufficient amounts of lithium-rich clay may be found in deposits that have been explored, found unsatisfactory for normal refractory uses, and not developed. The lithium-rich clay in some deposits presently being worked may be worth stockpiling for eventual use. ?? 1978.

Tourtelot, H.A.; Brenner-Tourtelot, E. F.

1978-01-01

75

Detection and Quantification of Expansive Clay Minerals in Geologically-Diverse Texas Aggregate Fines  

E-print Network

by x-ray diffraction analysis (XRD). However, no cation saturation treatments were utilized, which would make clay mineral identification less reliable. Magnesium and potassium ion saturation would have fixed layer thickness of any expandable clay... Angstroms- squared. MB adsorbs to surfaces of negatively-charged clay surfaces primarily by cation exchange mechanisms but also by van der Waals forces or hydrogen bonding with silicon and aluminum hydroxide surfaces in layer silicates? crystal lattice...

Russell, George 1983-

2012-11-28

76

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

Microsoft Academic Search

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

J. Srodon

1999-01-01

77

High gradient magnetic separation of iron oxide minerals from soil clays  

E-print Network

HIGH GRADIENT MAGNETIC SEPARATION OF IRON OXIDE MINERALS FROM SOIL CLAYS A Thesis by DARRELL GENE SCHULZE Submitted to the Graduate College of Texas AIM University in partial fulfillment of the requirement for the degree of MASTER OF SCIENCE... December 1977 Major Subject: Soil Science HIGH GRADIENT MAGNETIC SEPARATION OF IRON OXIDE MINERALS FROM SOIL CLAYS A Thesis DARRELL GENE SCHULZE Approved as to style and content by: (Chairman of C ittee) epartm t) j (Member) (Membe December 1977...

Schulze, Darrell Gene

2012-06-07

78

Dynamic role of “illite-like” clay minerals in temperate soils: facts and hypotheses  

Microsoft Academic Search

Analysis of new data and reinterpretation of published information for clay minerals found in temperate climate soil profiles\\u000a indicates that there is often a gradient of “illite-like” clay minerals with depth. We used the term “illite-like” because\\u000a these observations are based on X-Ray Diffractogram patterns and not on layer charge measurements which allow to define properly\\u000a illite. It appears that

P. Barré; B. Velde; L. Abbadie

2007-01-01

79

Evaluation of the medicinal use of clay minerals as antibacterial agents  

PubMed Central

Natural clays have been used to heal skin infections since the earliest recorded history. Recently our attention was drawn to a clinical use of French green clay (rich in Fe-smectite) for healing Buruli ulcer, a necrotizing fasciitis (‘flesh-eating’ infection) caused by Mycobacterium ulcerans. These clays and others like them are interesting as they may reveal an antibacterial mechanism that could provide an inexpensive treatment for this and other skin infections, especially in global areas with limited hospitals and medical resources. Microbiological testing of two French green clays, and other clays used traditionally for healing, identified three samples that were effective at killing a broad-spectrum of human pathogens. A clear distinction must be made between ‘healing clays’ and those we have identified as antibacterial clays. The highly adsorptive properties of many clays may contribute to healing a variety of ailments, although they are not antibacterial. The antibacterial process displayed by the three identified clays is unknown. Therefore, we have investigated the mineralogical and chemical compositions of the antibacterial clays for comparison with non-antibacterial clays in an attempt to elucidate differences that may lead to identification of the antibacterial mechanism(s). The two French green clays used to treat Buruli ulcer, while similar in mineralogy, crystal size, and major element chemistry, have opposite effects on the bacterial populations tested. One clay deposit promoted bacterial growth whereas another killed the bacteria. The reasons for the difference in antibacterial properties thus far show that the bactericidal mechanism is not physical (e.g., an attraction between clay and bacteria), but by a chemical transfer or reaction. The chemical variables are still under investigation. Cation exchange experiments showed that the antibacterial component of the clay can be removed, implicating exchangeable cations in the antibacterial process. Furthermore, aqueous leachates of the antibacterial clays effectively kill the bacteria. Progressively heating the clay leads first to dehydration (200°C), then dehydroxylation (550°C or more), and finally to destruction of the clay mineral structure by (~900°C). By identifying the elements lost after each heating step, and testing the bactericidal effect of the heated product, we eliminated many toxins from consideration (e.g., microbes, organic compounds, volatile elements) and identified several redox-sensitive refractory metals that are common among antibacterial clays. We conclude that the pH and oxidation state buffered by the clay mineral surfaces is key to controlling the solution chemistry and redox related reactions occurring at the bacterial cell wall. PMID:20640226

Williams, Lynda B.; Haydel, Shelley E.

2010-01-01

80

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

SciTech Connect

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

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

1997-05-01

81

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

PubMed Central

Pyrosequencing-based analysis of 16S rRNA gene sequences revealed a significant correlation between apatite dissolution and the abundance of betaproteobacteria on apatite surfaces, suggesting a role for the bacteria belonging to this phylum in mineral weathering. Notably, the cultivation-dependent approach demonstrated that the most efficient mineral-weathering bacteria belonged to the betaproteobacterial genus Burhkolderia. PMID:22798365

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

2012-01-01

82

Elemental Abundance Distributions in Basalt Clays and Meteorites: Is It a Biosignature?  

NASA Technical Reports Server (NTRS)

Volcanic glass altered by microorganisms exhibits distinctive textures differing significantly from abiotic alteration [1-4]. We have previously presented morphological evidence of bioweathering in sub-oceanic basalt glass [5] and olivine [6], and noted similar alterations in Nakhla [7]. We have also introduced an autonomous Bayesian probabilistic classification methodology to identify biotic and abiotic alteration in sub-oceanic basalts using elemental abundance data [8]. We now present data from multiple sub-oceanic sites addressing the more general question of utilizing elemental abundance distribution in clays as a valid biosignature for the exploration of putative clay alteration products in meteorites.

Fisk, M. R.; Storrie-Lombardi, M. C.; Joseph, J.

2005-01-01

83

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

PubMed

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

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

2014-01-01

84

Clay Minerals as Solid Acids and Their Catalytic Properties.  

ERIC Educational Resources Information Center

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

Helsen, J.

1982-01-01

85

EUROPIUM RETENTION ONTO CLAY MINERALS FROM 25 TO 150C: EXPERIMENTAL MEASUREMENTS, SPECTROSCOPIC FEATURES AND SORPTION MODELLING.  

E-print Network

1 EUROPIUM RETENTION ONTO CLAY MINERALS FROM 25 TO 150°C: EXPERIMENTAL MEASUREMENTS, SPECTROSCOPIC.Tertre@univ-lille1.fr Keywords: europium, sorption, clays, experimental, temperature, Time-Resolved Laser

Paris-Sud XI, Université de

86

A Method for the Determination of the Cation Exchange Capacity of Clay Minerals and Soils  

Microsoft Academic Search

For many purposes it is desirable to have a method for the determination of the cation exchange capacity of clay minerals based on principles as free from ambiguity as pos- sible. Most of the many methods previously proposed have the drawback of entailing a great deal of work if one is to make sure that the mineral is completely saturated

Galen Frysinger; HENRY C. THOMAS

1954-01-01

87

MODELING OF CATION BINDING IN HYDRATED 2:1 CLAY MINERALS  

EPA Science Inventory

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

88

THE LINK BETWEEN CLAY MINERAL WEATHERING AND THE FORMATION OF NI SURFACE PRECIPITATES  

E-print Network

THE LINK BETWEEN CLAY MINERAL WEATHERING AND THE FORMATION OF NI SURFACE PRECIPITATES Andreas C minerals may proceed via formation of surface precipitates, which may lead to a significant long may precipitate from pure metal solutions, the formation of layered double hydroxides (LDH) and of 1

Sparks, Donald L.

89

A laboratory effort to quantitatively address clay abundance on Mars  

NASA Astrophysics Data System (ADS)

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

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

2011-12-01

90

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

PubMed

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 ?M) + clay minerals (3% w/v) system in SDOC accounted for complete reduction of Cr(VI) (192.32 ?M) 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. PMID:24195488

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

2013-12-01

91

ATTENUATION OF POLLUTANTS IN MUNICIPAL LANDFILL LEACHATE BY CLAY MINERALS  

EPA Science Inventory

The first part of this project was a laboratory column study of attenuation of pollutants in municipal solid waste landfill leachate by mixtures of sand and calcium-saturated clays. K, NH4, Mg, Si, and Fe were moderately attenuated; and the heavy metals Pb, Cd, Hg, and Zn were st...

92

PYROGENIC CARBON-CLAY MINERAL ASSOCIATIONS IN SOIL SMECTITES  

Technology Transfer Automated Retrieval System (TEKTRAN)

Bioorganic carbon is “sequestered” in soil as humic substances (HS). HS is believed to form strong complexes with clays by a number of bonding mechanisms, including ligand exchange, cation-bridging with metals, and H-bonding to siloxane sheets. However, the recent discovery of pyrogenic or black ca...

93

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

USGS Publications Warehouse

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

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

2004-01-01

94

Toxicological evaluation and metal bioavailability in pregnant rats following exposure to clay minerals in the diet.  

PubMed

Silicate clays are frequently added to animal feeds to bind and reduce the bioavailability of mycotoxins in the gastrointestinal tract. However, the bioavailability of trace metals in these clay feed additives has not been thoroughly investigated. Clays that act nonselectively may interact with nutrients, minerals, and other feedborne chemicals to pose significant hidden risks. In this study, a calcium montmorillonite clay (Novasil Plus, NSP) commonly used as an enterosorbent for aflatoxins and a sodium montmorillonite clay (Swy-2) (Source Clay Minerals Repository, Columbia, MO) were examined. Clays were supplemented in the balanced diet of Sprague-Dawley rats during pregnancy at a level of 2% (w/w). Evaluations of toxicity were performed on gestation d 16 and included maternal body weights, maternal feed intakes, litter weights, and embryonic resorptions. Liver, kidneys, tibia, brain, uterus, pooled placentas, and pooled embryonic mass were collected and weighed. Tissues were lyophilized and neutron activation analysis (NAA) was performed. Elements considered by NAA included Al, Ba, Br, Ca, Ce, Co, Cr, Cs, Cu, Dy, Eu, Fe, Hf, K, La, Lu, Mg, Mn, Na, Nd, Ni, Rb, S, Sb, Sc, Se, Sm, Sr, Ta, Tb, Te, Th, Ti, Tl, U, V, Yb, Zn, and Zr. Inductively coupled plasma-mass spectroscopy further confirmed that Al was below detection limits (<0.5 ppm) in the brain. Animals supplemented with either NSP or Swy-2 were similar to controls with respect to toxicity evaluations and metal analysis, with the exception of decreased brain Rb following clay supplementation. Overall, the results of this study suggest that neither NSP nor Swy-2, at relatively high dietary concentrations, influences mineral uptake or utilization in the pregnant rat. PMID:15205041

Wiles, Melinda; Huebner, Henry; Afriyie-Gyawu, Evans; Taylor, Robert; Bratton, Gerald; Phillips, Timothy

2004-06-11

95

Heterogeneous uptake of the C1 to C4 organic acids on a swelling clay mineral  

NASA Astrophysics Data System (ADS)

Mineral aerosol is of interest due to its physiochemical impacts on the Earth's atmosphere. However, adsorbed organics could influence the chemical and physical properties of atmospheric mineral particles and alter their impact on the biosphere and climate. In this work, the heterogeneous uptake of a series of small organic acids on the swelling clay, Na-montmorillonite, was studied at 212 K as a function of relative humidity (RH), organic acid pressure and clay mass. A high vacuum chamber equipped with a quadrupole mass spectrometer and a transmission Fourier transform infrared spectrometer was used to detect the gas and condensed phases, respectively. Sub-monolayer coverage of organic acid on montmorillonite was observed under dry conditions and relevant organic acid pressures. However, the organic acid content increased significantly with increasing humidity. Additionally, while the initial uptake efficiency was found to be independent of organic acid pressure, it increased linearly with increasing clay mass. Thus, the small masses studied allow access to the entire surface area of the clay sample with minimal effects due to surface saturation. Results from this study show that the initial uptake efficiency for n-butyric acid on the clay increases by an order of magnitude as the RH is raised from 0% to 45% RH at 212 K while the uptake of formic, acetic and propionic acids increase only slightly at higher humidities. Additionally, the presence of organic acids was found to slightly enhance the water content of the clay above 45% RH. Our results indicate that heterogeneous uptake of organic acids on swelling clay minerals provides an important heterogeneous sink for these species and may modify the cloud forming potential of the clay particles.

Hatch, C. D.; Gough, R. V.; Tolbert, M. A.

2007-05-01

96

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

NASA Astrophysics Data System (ADS)

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 in the form of sub-nanometer Cr2O3 in association with residual clay minerals as micro-aggregates. This textural association was expected to minimize the chance of Cr(III) reoxidation upon exposure to oxidants. These results are important for our understanding of how various clay minerals may be used to reductively immobilize the heavy metal contaminant Cr in the environment.

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

2014-05-01

97

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

SciTech Connect

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 in the form of sub-nanometer Cr2O3 in association with residual clay minerals as micro-aggregates. This textural association was expected to minimize the chance of Cr(III) reoxidation upon exposure to oxidants. These results are important for our understanding of how various clay minerals may be used to reductively immobilize the heavy metal contaminant Cr in the environment.

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

2014-05-15

98

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

NASA Astrophysics Data System (ADS)

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

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

2012-09-01

99

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

Microsoft Academic Search

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

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

1975-01-01

100

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

NASA Astrophysics Data System (ADS)

Atmospheric mineral aerosol is a potentially important reactive surface that may provide a heterogeneous sink for gas phase species such as nitric acid and oxygenated organic compounds in the Earth's troposphere. Smectite clays, such as montmorillonite, are particularly interesting reactive surfaces because they are commonly found in the atmosphere and have a unique ability to swell. The swelling properties of montmorillonite allow for substantial adsorbed water under humid conditions, possibly promoting further reactivity. The heterogeneous uptake of water, nitric acid and a series of small organic acids on Na-montmorillonite clay under upper tropospheric temperatures and humidities was studied in a high vacuum chamber equipped with a quadrupole mass spectrometer (MS) and a transmission Fourier transform infrared (FT-IR) spectrometer used to detect the gas and condensed phases, respectively. Water adsorption on montmorillonite clay was measured using FT-IR as a function of relative humidity (RH) with respect to liquid water at temperatures from 212 to 232 K. The specific surface area and adsorbed water content of the swollen clay were determined and are consistent with previous results from gravimetric methods at room temperature. Thus, water adsorption appears to be independent of temperature down to upper tropospheric temperatures. However, the amount of adsorbed water and swollen surface area was found to increase significantly as the RH was raised. Na-montmorillonite was found to contain 10% water by mass at 50% RH and the observed growth curve is comparable to that of ammonium sulfate, a well characterized hygroscopic species. Thus, swelling clays entrained in the Earth's atmosphere may be important cloud condensation nuclei and may indirectly affect the Earth's climate. The heterogeneous uptake of the C1 to C4 organic acids on Na-montmorillonite clay was studied at 212 K as a function of RH, from 0% to 45% RH, organic acid pressure and clay mass. While the initial uptake was found to be independent of organic acid pressure, linear dependence of the initial uptake on clay mass was observed. However, the organic acid content was found to increase significantly with increasing acid pressure. A significant enhancement in the organic acid content, water content and the initial uptake coefficients was observed as the RH was raised. Additionally, the presence of organic acids was found to slightly enhance the water content of the clay above 45% RH. Results suggest that that heterogeneous uptake of organic acids on swelling clay minerals is an important heterogeneous removal mechanism for carboxylic acids in the atmosphere at all RH values studied, and probably more so at higher humidities. The heterogeneous uptake of nitric acid on Na-montmorillonite clay at low temperatures as a function of RH, nitric acid pressure and clay mass has also been studied. Below 16% RH, uptake of nitric acid on Na-montmorillonite was below the detection limit. However, similar to the organic acids, the nitric acid content, water content and initial uptake coefficient all increase with increasing RH. Additionally, these values were all found to be independent of temperature from 210 to 232 K and independent of pressure from 1x10 -5 to 3x10-4 Torr nitric acid. However, a linear dependence on mass was observed for small sample masses. The adsorbed water content of Na-montmorillonite clay was also significantly enhanced compared to experiments performed when only water was present. Results suggest that heterogeneous uptake of nitric acid on swelling clay minerals is an important heterogeneous removal mechanism in the troposphere under humid conditions when clay is expected to be swollen. Higher in the atmosphere, it is currently questionable as to whether mineral particles are effective nuclei for polar stratospheric clouds (PSCs), which play a crucial role in polar ozone loss. The heterogeneous formation of nitric acid trihydrate (NAT) on Na-montmorillonite and kaolinite clays has also been studied. Both clays were found to accommodate monolaye

Mashburn, Courtney Dyan

101

Experimental Constraints on Microbial Liberation of Structural Iron from Common Clay Minerals in Marine Sediments  

NASA Astrophysics Data System (ADS)

Iron is a limiting nutrient in many marine settings. The marine Fe-cycle is complex because Fe may be used as an electron donor or acceptor and cycled many times before ultimate burial in sediments. Thus, the availability of iron plays a large role in the marine carbon cycle, influencing not only the extent of primary productivity but also the oxidation of organic matter in sediments. The primary constituents of marine sediments are clay minerals, which commonly contain lattice-bound Fe in octahedral sites. In marine settings, the pool of Fe bound within silicate mineral lattices has long been considered reactive only over long timescales, and thus non-bioavailable. In vitro experimental evidence has shown that lab cultures of Fe-reducing bacteria are able to utilize structurally-bound Fe (III) from the crystal lattice of nontronite, an uncommon but particularly Fe-rich (> 12 wt.%) smectite. Importantly, this process is capable of liberating Fe (II) to solution, where it is available to biotic processes as an electron donor. In order to constrain the capacity of naturally-occurring marine bacteria to liberate structurally-coordinated Fe from the lattices of common clay minerals, we exposed a suite of 16 different clay minerals (0.8-13.9 wt.% Fe) to lab cultures of known Fe-reducer S. onenidensis MR-1 and to a natural consortium of Fe-reducing microbes from the San Pedro and Santa Monica Basins over timescales ranging from 7-120 days. Clay minerals were treated with Na-dithionite to extract surface-bound Fe prior to exposure. Crystallographic data and direct measurements of Fe in solution demonstrate the release of structural Fe from all clay minerals analyzed. Neoformation of illite and amorphous quartz were observed. The array of clay minerals and microbes used in this experiment complement past findings and 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.

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

2013-12-01

102

Potential contributions of clay minerals and organic matter to pentachlorophenol retention in soils.  

PubMed

Sorption of pentachlorophenol (PCP) by pure minerals and humic acids were measured to obtain additional perspective on the potential contributions of both clay minerals and soil organic matter (SOM) to contaminants retention in soils. Four types of common soil minerals and two kinds of humic acids (HAs) were tested. The sorption affinity for PCP conformed to an order of HAs > K-montmorillonite > Ca-montmorillonite > goethite > kaolinite. Such a difference in sorption capacity could be attributed to the crucial control of HAs. Clay minerals also had their contribution, especially K-montmorillonite, which played an important, if not dominant, role in the controlling process of PCP sorption. By removing 80% (on average) of the organic carbon from the soils with H(2)O(2), the sorption decreased by an average of 50%. The sorption reversibility had been greatly favored as well. Considering the uncharged mineral fractions in soil before and after H(2)O(2)-treated, the main variation in sorption behavior of the soil might thus be related to the removed organic carbon and the reduced pH. This testified rightly the interactive effect of SOM and clay minerals on PCP sorption as a function of pH. PMID:16481030

He, Yan; Xu, Jianming; Wang, Haizhen; Zhang, Qichun; Muhammad, Akmal

2006-10-01

103

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

EPA Science Inventory

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

104

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

Microsoft Academic Search

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

Yvonne Hamann; Werner Ehrmann; Gerhard Schmiedl; Tanja Kuhnt

2009-01-01

105

Frictional properties of the shallow Nankai Trough accretionary sediments dependent on the content of clay minerals  

NASA Astrophysics Data System (ADS)

We conducted triaxial friction experiments on the shallow Nankai Trough accretionary sediments at confining pressures, pore water pressures, temperatures close to their in situ conditions, and axial displacement rates ( V axial) changed stepwise among 0.1, 1, and 10µm/s. The results revealed that their frictional properties change systematically according to the content of clay minerals, smectite in particular. The steady-state friction coefficient ( ? ss) at V axial = 1µm/s decreases with increasing clay mineral content, shown in weight percent, from 0.82 for a sandstone sample (6 wt%), through 0.71 for a tuff sample (?17 wt%), and 0.53 to 0.56 for siltstone samples (29 to 34 wt%), to 0.25 for a claystone sample (42 wt%). Slip-dependent frictional behavior changes accordingly from slip hardening for the sandstone sample, through quasi steady-state slip for the tuff and siltstone samples, to distinct slip weakening for the claystone sample. Although all samples exhibit velocity-strengthening behavior upon stepwise changes in sliding velocity, the ratio of the ( a - b) value to the velocity dependence of steady-state friction (? ? ss/?ln V sliding) decreases with increasing clay mineral content, which implies that the friction component decreases while the flow component increases accordingly. Thus, faulting in the shallow Nankai Trough accretionary prism is likely controlled by the clay mineral content, in particular the smectite content, in the sediments as well as in the fault zones.

Takahashi, Miki; Azuma, Shuhei; Ito, Hidenori; Kanagawa, Kyuichi; Inoue, Atsuyuki

2014-12-01

106

Auxiliary Information for "Wind-blown sandstones cemented by sulfate and clay minerals in Gale  

E-print Network

Auxiliary Information for "Wind-blown sandstones cemented by sulfate and clay minerals in Gale. Sharp exhibit features consistent with eolian sandstones that may be cemented by sulfates. As described to features observed in terrestrial eolian sandstones such as the Navajo sandstone in the southwestern U

107

Application of the Modified Methylene Blue Test to Detect Clay Minerals in Coarse Aggregate Fines  

E-print Network

The purpose of this study was to implement a new, rapid field method to effectively and accurately detect harmful clay minerals in aggregate fines by using the modified methylene blue (MMB) test. The focus of this study was based on existing...

Pitre, Brandon

2012-12-04

108

Heterogeneous uptake of the C1 to C4 organic acids on a swelling clay mineral  

NASA Astrophysics Data System (ADS)

Mineral aerosol is of interest due to its physiochemical impacts on the Earth's atmosphere. However, adsorbed organics could influence the chemical and physical properties of atmospheric mineral particles and alter their impact on the biosphere and climate. In this work, the heterogeneous uptake of a series of small organic acids on the swelling clay, Na-montmorillonite, was studied at 212 K as a function of relative humidity (RH), organic acid pressure and clay mass. A high vacuum chamber equipped with a quadrupole mass spectrometer and a transmission Fourier transform infrared spectrometer was used to detect the gas and condensed phases, respectively. Our results show that while the initial uptake efficiency was found to be independent of organic acid pressure, it increased linearly with increasing clay mass. Thus, the small masses studied allow access to the entire surface area of the clay sample with minimal effects due to surface saturation. Additionally, results from this study show that the initial uptake efficiency for butanoic (butyric) acid on the clay increases by an order of magnitude as the RH is raised from 0% to 45% RH at 212 K while the initial uptake efficiency of formic, acetic and propanoic (propionic) acids increases only slightly at higher humidities. However, the initial uptake efficiency decreases significantly in a short amount of time due to surface saturation effects. Thus, although the initial uptake efficiencies are appropriate for initial times, the fact that the uptake efficiency will decrease over time as the surface saturates should be considered in atmospheric models. Surface saturation results in sub-monolayer coverage of organic acid on montmorillonite under dry conditions and relevant organic acid pressures that increases with increasing humidity for all organic acids studied. Additionally, the presence of large organic acids may slightly enhance the water content of the clay above 45% RH. Our results indicate that heterogeneous uptake of organic acids on swelling clay minerals provides an important irreversible heterogeneous sink for these species.

Hatch, C. D.; Gough, R. V.; Tolbert, M. A.

2007-08-01

109

Clay minerals in basin of Mexico lacustrine sediments and their influence on ion mobility in groundwater  

NASA Astrophysics Data System (ADS)

Semiconfined aquifers used as the principal water supply within the Basin of Mexico are overlain by lacustrine deposits that provide a degree of protection from contamination associated with metropolitan Mexico City. Solute transport behavior and the nature of chemical interactions with mineral components in these sediments is poorly understood. The objectives of this paper were to identify the clay mineral phases of the lacustrine sediments and to determine the significance of the exchange properties of the day minerals on contaminant transport processes. Samples obtained from two cores were separated into sand, silt, and clay-size fractions. The clay-size fraction was analyzed by X-ray diffraction and Fourier transform infrared spectroscopy and for specific surface area and pH-dependent cation and anion exchange capacity. The clay-sized fraction averaged 56% of the sediment. Analyses indicated that the clay was predominantly composed of a Si-rich allophane with approximately 30% montmorillonite. Halloysite was also present to a depth of about 1.5 m, but was absent deeper in the sediment. Kaolinite and illite, reported in previous studies, and imogolite were not found in the samples. Solute transport in the sediment was modeled to demonstrate the impact of exchange properties imparted by the allophane compared to other possible clay mineral assemblages. The predominance of allophane in the Basin of Mexico sediments is responsible for many of the fundamental characteristics of the material including: high porosity (0.8-0.9), high water content (200-400%), and an extremely high and pH-dependent cation exchange capacity. The pH of the pore water within the lacustrine sediments of the Basin of Mexico is typically between 6.5 and 12. Measured cation exchange values ranged from ? 450 meq kg -1 at pH 6.5 to ? 650 meq kg -1 at pH 12 which could produce variable cation mobility in the semiconfining aquitard. The simulations illustrated that allophane is very effective for retarding the leaching of cationic metals compared to other possible clay mineral suites, particularly at high pH values. Simulation of long-term infiltration indicated that trace metals will become concentrated in the clay matrix adjacent to fracture faces in the sediment near ground surface. As such, the aquitard behaves as an efficient barrier to the infiltration of cationic metals into the underlying aquifer.

Warren, C. J.; Rudolph, D. L.

1997-09-01

110

Kinetics of Ion Exchange on Clay Minerals and Soil: I. Evaluation of Methods1 R. A. OGWADA AND D. L. SPARKS2  

E-print Network

Kinetics of Ion Exchange on Clay Minerals and Soil: I. Evaluation of Methods1 R. A. OGWADA AND D. L,vermiculite. Ogwada, R.A., and D.L. Sparks. 1986. Kinetics of ion exchangeon clay minerals and soil: I. Evaluation displacement or flow techniques to investigate kinetics of ion exchange on soils and clay minerals (Sparks

Sparks, Donald L.

111

Clay mineral formation on Mars: Chemical constraints and possible contribution of basalt out-gassing  

NASA Astrophysics Data System (ADS)

We focus on processes possibly occurring on Mars that could affect sufficiently large volumes of rocks to be detected by remote sensing techniques. When compared with the chemical modelling of water-rock interactions, the petrographic and mineralogical characteristics of clay deposited in the prismatic joints of a lava flow from the Parana basin (Brazil) suggest that the clay fraction of lava flows may be formed at least partly during an early post-magmatic stage associated with the degassing of acid volatiles. In view of the literature concerning other contexts, such as meteorites or experimental syntheses, we conclude that the crystallization of anhydrous mafic minerals and the formation of clay mineral are not systematically mutually exclusive phenomena. While clay formation is generally related to chemical reaction pathways, it is not necessarily due to the alteration of pre-existing silicates. Such post-magmatic reactions, even if they are likely to represent only a minor contribution to Martian clay formation limited to early Noachian times, require much lower amounts of water compared to conventional hydrothermal alteration or weathering systems. The products of these reactions can be detected over large surface areas, as in the case of the Mars sites, thus allowing us to envisage a greater diversity of paleogeographic scenarios for Early Mars.

Berger, Gilles; Meunier, Alain; Beaufort, Daniel

2014-05-01

112

Atomistic simulations of clay minerals subject to variably hydrated supercritical CO2  

NASA Astrophysics Data System (ADS)

Commonly occurring clay minerals, such as phyllosilicates, tend to expand as they incorporate water. The ubiquitous presence and importance of clay minerals in caprock seals and shale gas plays undergoing enhanced gas recovery with CO2 requires much better understanding of chemically induced changes in these minerals upon contact with variably wet scCO2. Recent advances in our groups experimental techniques have enabled detailed characterization of the H2O/CO2 intercalation in a variety of montmorillonites. In parallel, we have also initiated density functional (DFT) simulations to help understand the interactions between layered materials and the water-bearing supercritical fluid alone or in the presence of sulfur-containing species, pertinent to mixed-gas injection conditions. Through our simulations, we expect to understand how CO2 interacts with different intra-layer ions under different degrees of hydration or the presence of sulfur-containing species, and how the overall swelling properties of the clays will be affected. Preliminary results indicate that clays with higher degrees of hydration are likely to expand more after CO2 intercalation, as illustrated in Figure 1.; Figure 1. Radial distribution function of Ca-C obtained from DFT-based molecular dynamics simulations of fully hydrated Ca2+ ions in supercritical CO2 show that the CO2 molecules will be found at average distances > 5 Å and can potentially induce higher degrees of swelling.

Glezakou, V.; Schaef, T.; McGrail, P.

2012-12-01

113

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

PubMed

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. PMID:24603112

Plachá, Daniela; Rosenbergová, Kate?ina; Slabotínský, Ji?í; Kutláková, Kate?ina Mamulová; Studentová, So?a; Martynková, Gražyna Simha

2014-04-30

114

Clay minerals in primitive meteorites and interplanetary dust 1  

NASA Technical Reports Server (NTRS)

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.

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

1991-01-01

115

Areal distribution of clay minerals and their relationship to physical properties, Gulf of Mexico  

E-print Network

:. - . u 8 0, 0 0 . , ( 29 0 $0 0 l' ee 3 0 6 ' 31)', 0 / 06, ' 5 Iee . / eel c 95' eo 85' 80 F1G. 1 ? Locatioo )pap. of geotechnicai properties with the clay mineralogy will aid in understanding the degree to which variations in geotechnical... was then concentrated into a centrifuge cake and spread on a glass slide for X-ray diffraction. The smear method suggested both by Glbbs (1965) and Stokke and Carson (1979) was used to avoid segregation of clay minerals. Both studies showed that mounting techniques...

Hottman, William Edward

2012-06-07

116

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

PubMed Central

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

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

2013-01-01

117

Influence of soil properties on the toxicity of TiO? nanoparticles on carbon mineralization and bacterial abundance.  

PubMed

Information regarding the impact of low concentration of engineered nanoparticles on soil microbial communities is currently limited and the importance of soil characteristics is often neglected in ecological risk assessment. To evaluate the impact of TiO2 nanoparticles (NPs) on soil microbial communities (measured on bacterial abundance and carbon mineralization activity), 6 agricultural soils exhibiting contrasted textures and organic matter contents were exposed for 90 days to a low environmentally relevant concentration or to an accidental spiking of TiO2-NPs (1 and 500mgkg(-1) dry soil, respectively) in microcosms. In most soils, TiO2-NPs did not impact the activity and abundance of microbial communities, except in the silty-clay soil (high OM) where C-mineralization was significantly lowered, even with the low NPs concentration. Our results suggest that TiO2-NPs toxicity does not depend on soil texture but likely on pH and OM content. We characterized TiO2-NPs aggregation and zeta potential in soil solutions, in order to explain the difference of TiO2-NPs effects on soil C-mineralization. Zeta potential and aggregation of TiO2-NPs in the silty-clay (high OM) soil solution lead to a lower stability of TiO2-NP-aggregates than in the other soils. Further experiments would be necessary to evaluate the relationship between TiO2-NPs stability and toxicity in the soil. PMID:25464292

Simonin, Marie; Guyonnet, Julien P; Martins, Jean M F; Ginot, Morgane; Richaume, Agnès

2015-02-11

118

Sorption and Desorption of Pesticides by Clay Minerals and Humic Acid-Clay Complexes  

Microsoft Academic Search

small amounts of water to soil reduced the sorption of organic compounds relative to the sorption by the In soils, organic matter and minerals are often associated such that dehydrated soil in hexane, and that organic vapor ad- it is unclear how the presence of the former component influences sorption by soil was significantly depressed by increasing the sorptive properties

Hui Li; Guangyao Sheng; Brian J. Teppen; Cliff T. Johnston; Stephen A. Boyd

2003-01-01

119

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

NASA Technical Reports Server (NTRS)

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

Burt, D. M.

1989-01-01

120

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

PubMed Central

The majority of carbon sequestration at the Earth’s surface occurs in marine continental margin settings within fine-grained sediments whose mineral properties are a function of continental climatic conditions. We report very high mineral surface area (MSA) values of 300 and 570 m2 g in Late Cretaceous black shales from Ocean Drilling Program site 959 of the Deep Ivorian Basin that vary on subcentennial time scales corresponding with abrupt increases from approximately 3 to approximately 18% total organic carbon (TOC). The observed MSA changes with TOC across multiple scales of variability and on a sample-by-sample basis (centimeter scale), provides a rigorous test of a hypothesized influence on organic carbon burial by detrital clay mineral controlled MSA. Changes in TOC also correspond with geochemical and sedimentological evidence for water column anoxia. Bioturbated intervals show a lower organic carbon loading on mineral surface area of 0.1 mg-OC m-2 when compared to 0.4 mg-OC m-2 for laminated and sulfidic sediments. Although either anoxia or mineral surface protection may be capable of producing TOC of < 5%, when brought together they produced the very high TOC (10–18%) apparent in these sediments. This nonlinear response in carbon burial resulted from minor precession-driven changes of continental climate influencing clay mineral properties and runoff from the African continent. This study identifies a previously unrecognized land–sea connection among continental weathering, clay mineral production, and anoxia and a nonlinear effect on marine carbon sequestration during the Coniacian-Santonian Oceanic Anoxic Event 3 in the tropical eastern Atlantic. PMID:21576498

Kennedy, Martin J.; Wagner, Thomas

2011-01-01

121

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

Microsoft Academic Search

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

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

2004-01-01

122

Clay mineral-organic matter relationships in the early solar system  

NASA Astrophysics Data System (ADS)

As the solar system formed, it inherited and perpetuated a rich organic chemistry, the molecular products of which are preserved in ancient extraterrestrial objects such as carbonaceous chondrites. These organic-rich meteorites provide a valuable and tangible record of the chemical steps taken towards the origin of life in the early solar system. Chondritic organic matter is present in the inorganic meteorite matrix which, in the CM and CI chondrites, contains evidence of alteration by liquid water on the parent asteroid. An unanswered and fundamental question is to what extent did the organic matter and inorganic products of aqueous alteration interact or display interdependence? We have used an organic labelling technique to reveal that the meteoritic organic matter is strongly associated with clay minerals. This association suggests that clay minerals may have had an important trapping and possibly catalytic role in chemical evolution in the early solar system prior to the origin of life on the early Earth.

Pearson, Victoria K.; Sephton, Mark A.; Kearsley, Anton T.; Bland, Philip A.; Franchi, Ian A.; Gilmour, Iain

2002-12-01

123

Catalytic activity of hammerhead ribozymes in a clay mineral environment: Implications for the RNA world  

Microsoft Academic Search

The hypothesized RNA-based world would have required the presence of a protected environment in which RNA, or an RNA-like molecule, could originate and express its biological activity.Recent studies have indicated that RNA molecules adsorbed\\/bound on clay minerals are able to persist in the presence of degrading agents, to interact with surrounding molecules, and to transmit the information contained in their

Elisa Biondi; Sergio Branciamore; Luca Fusi; Selma Gago; Enzo Gallori

2007-01-01

124

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

NASA Astrophysics Data System (ADS)

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. Given estimated geothermal gradients on Mars temperatures <60 °C might still be consistent with (but do not require) moderate burial. However, our ability to identify interstratified minerals is greatly limited by the lack of access to traditional treatments methods used in the lab (e.g., ethylene glycol solvation). Our preferred explanation for the origin of trioctahedral smectites in Sheepbed mudstone is in situ production via reaction of olivine, water and Si-bearing amorphous material, an important mudstone component detected by XRD. Elevated levels of magnetite in the Sheepbed and the trioctahedral monomineralic nature of the clay minerals support this model. These observations, combined with previous studies of olivine stability, support the persistence of circum-neutral hydrous conditions for thousands of years at YKB.

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

125

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

SciTech Connect

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.

Brookins, D.G.; Ward, D.B. (New Mexico Univ., Albuquerque, NM (USA). Dept. of Geology); Lambert, S.J. (Sandia National Labs., Albuquerque, NM (USA))

1990-05-01

126

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

NASA Astrophysics Data System (ADS)

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 correlate with cation exchange capacity and cation exchange processes. 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: 2013-6352A.

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

2013-12-01

127

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

PubMed

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. PMID:23841441

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

2013-04-01

128

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

PubMed

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. PMID:24816462

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

2014-09-01

129

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

SciTech Connect

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

Nagy, Kathryn L.

2008-07-03

130

Mineral contributions to atrazine and alachlor sorption in soil mixtures of variable organic carbon and clay content  

NASA Astrophysics Data System (ADS)

A sediment mixing approach was taken to systematically vary the organic carbon (oc) and clay content (cm) of a suite of organic-poor, clay-rich sediments. Organic carbon content ranged from 3.2% to 0.4% and clay content ranged from 24% to 51%. Atrazine and alachlor were shown to sorb to both natural organic carbon and clay minerals. Partition coefficients to natural organic carbon ( Koc) were found to be 217 and 412 L/kg organic carbon for atrazine and alachlor, respectively. Partition coefficients to the clay fraction were found to be 3.5 and 4.9 L/kg clay for atrazine and alachlor, respectively. When expressed in terms of surface area, the partition coefficients to clay for atrazine and alachlor were 1.80·10 -5 and 2.51·10 -5 L/m 2 clay, respectively. Critical cm/oc ratios at which mineral phase sorption accounts for 50% of the total are defined. Implications for the modelling of herbicide movement in the subsurface if mineral phase sorption is ignored is discussed.

Grundl, Tim; Small, Greg

1993-09-01

131

Sorption of humic acids and alpha-endosulfan by clay minerals.  

PubMed

Sorption of alpha-endosulfan by kaolinite and montmorillonite alone and in the presence of sorbed and dissolved humic acid (HA) was investigated (pH 8 and 25 degrees C). Three types of HA, Elliot soil HA (EHA), Peat HA (PHA), and Summit Hill HA (SHHA), were used to represent typical humic substances found in soils. For sorption of HA by either mineral, Freundlich sorption coefficient (K(f)) values appeared to decrease in the order of EHA > PHA > SHHA, which followed increasing polarity (expressed as the O/C atomic ratio) and decreasing percent-carbon content. For both clays, sorption of alpha-endosulfan by the HA mineral complex was greater than for sorption by the clay alone. Sorption of alpha-endosulfan by the HA mineral complexes followed the same order as the K(f) of the HAs (EHA > PHA > SHHA). Based on the amount of HA adsorbed by each mineral, organic carbon partition coefficients (K(oc)) were determined for sorption of alpha-endosulfan by two of the HA mineral complexes. The value of K(oc) for alpha-endosulfan sorption was greater for kaolinite EHA than kaolinite SHHA. However, the opposite trend was found with the montmorillonite HA complexes. Montmorillonite appeared to sorb alpha-endosulfan and/or HA with higher affinity than kaolinite, which likely is due to its 2:1 layer structure and higher surface area. Sorption of endosulfan diol, a hydrolysis product, by the minerals was much less than the parent pesticide. PMID:16494219

Hengpraprom, Sarunya; Lee, Cindy M; Coates, John T

2006-01-01

132

Syn- and post-sedimentary controls on clay mineral assemblages in a tectonically active basin, Andean Argentinean foreland  

NASA Astrophysics Data System (ADS)

In the northern part of the Calchaquí Valley (NW Argentina), Palaeogene Andean foreland sediments are represented by a 1400-metre-thick continental succession (QLC: Quebrada de Los Colorados Formation) consisting of claystones, siltstones, sandstones, and conglomerates representing sedimentation in fluvial-alluvial plains and alluvial fan settings. To understand the main syn- and postsedimentary variables controlling the clay mineral assemblages of this succession, we have studied the fine-grained clastic sediments by X-ray diffraction and electron microscopy, along with a detailed sedimentary facies analysis, for two representative sections. In the northern section, the whole succession was sampled and analysed by XRD, whereas in the second section, a control point 15 km to the south, only the basal levels were analysed. The XRD study revealed a strong contrast in clay mineral assemblages between these two sections as well as with sections in the central Calchaquí Valley studied previously. In the northernmost part of the study area, a complete evolution from smectite at the top to R3 illite/smectite mixed-layers plus authigenic kaolinite at the bottom, through R1-type mixed-layers in between, has been recognized, indicating the attainment of late diagenesis. In contrast, the clay mineral assemblages of equivalent foreland sediments cropping out only 15 km to the south contain abundant smectite and micas, subordinate kaolinite and chlorite, and no I/S mixed-layers to the bottom of the sequence. Early diagenetic conditions were also inferred in a previous study for equivalent sediments of the QLC Formation cropping out to the south, in the central Calchaquí Valley, as smectite occurs in basal strata. Burial depths of approximately 3000 m were estimated for the QLC Formation in the central and northern Calchaquí Valley; in addition, an intermediate to slightly low geothermal gradient can be considered likely for both areas as foreland basins are regarded as hypothermal basins. Consequently, the attainment of late diagenesis in the northernmost study area cannot be explained by significant differences in burial depth nor in geothermal gradient in relation to the section 15 km to the south nor with the central Calchaquí Valley. The formation of R3 mixed-layer I/S and authigenic kaolinite in the northern study area was most likely controlled by the circulation of hot, deep fluids along the reverse faults that bounded the Calchaquí valley. These faults were active during the Cenozoic, as evidenced by the syndepositional deformation features preserved in the studied sediments. Stress could also have been a driving force in burial diagenesis at the R3 mixed-layer I/S stage in these young continental sediments.

Do Campo, Margarita; Nieto, Fernando; del Papa, Cecilia; Hongn, Fernando

2014-07-01

133

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

USGS Publications Warehouse

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 (?s°) 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 is stronger than for most common clay minerals. Thus, it is expected that CH4 molecules may preferentially occupy surface sites on organic matter. However, active sites on clay mineral surfaces are easily blocked by water. As a consequence, organic-rich shales possess a larger CH4-sorption capacity than clay-rich rocks lacking organic matter. The thermodynamic parameters obtained in this study can be incorporated into model predictions of the maximum Langmuir pressure and CH4- sorption capacity of shales under reservoir temperature and pressure conditions.

Zhang, Tongwei; Ellis, Geoffrey S.; Ruppel, Stephen C.; Milliken, Kitty; Lewan, Mike; Sun, Xun

2013-01-01

134

Stable isotope geochemistry of sulfur bearing minerals and clay mineralogy of some soils and sediments in Loot Desert, central Iran  

E-print Network

Stable isotope geochemistry of sulfur bearing minerals and clay mineralogy of some soils Desert Stable isotope geochemistry is a unique technique to study the source of salts in soils and sediments. In the present research, sources of gypsum and other sulfur bearing minerals using stable isotope

Ahmad, Sajjad

135

Removal of phosphate ions from aqueous solution using Tunisian clays minerals and synthetic zeolite.  

PubMed

Phosphate ions are usually considered to be responsible for the algal bloom in receiving water bodies and aesthetic problems in water. From the environmental point of view, the management of such contaminant and valuable resource is very important. The present work deals with the removal of phosphate ions from aqueous solutions using kaolinitic and smectic clay minerals and synthetic zeolite as adsorbent. The pH effect and adsorption kinetic were studied. It was found that phosphate could be efficiently removed at acidic pH (between 4 and 6) and the second order model of kinetics is more adopted for all samples. The isotherms of adsorption of phosphate ions by the two clays and the zeolite samples show that the zeolite has the highest rate of uptake (52.9 mg P/g). Equilibrium data were well fitted with Langmuir and Freundlich isotherm. PMID:22894095

Hamdi, Noureddine; Srasra, Ezzeddine

2012-01-01

136

Clay mineral distributions in surface sediments of the Liaodong Bay, Bohai Sea and surrounding river sediments: Sources and transport patterns  

NASA Astrophysics Data System (ADS)

Clay mineralogy of surface sediments throughout the Liaodong Bay and surrounding fluvial samples has been analyzed in order to reveal sources and spatial transport patterns of the detrital fine-grained sediments. Four characteristic end-members in clay compositions were observed from four major provenances, respectively: high content of smectite and scarce chlorite from northern rivers, and Luan River, high illite and low smectite from southern rivers, highest content of illite from eastern rivers, mediate content from western rivers. The sources and distribution patterns of clay minerals are closely related to river inputs, the regional currents, and tide systems. The clays covered in the southwest (SW zone) are primarily supplied by the Luan River and the Liugu River. While the clays in the northern Liaodong Bay (North Zone) derived from the northern rivers seem to be transported mainly via the surface currents. The clay minerals in the southeast (SE zone) sourced from the Laotieshan passage are attributed to the northward residual currents. Furthermore, the materials resulted from bedrocks erosion may bring a few clay minerals.

Dou, Yanguang; Li, Jun; Zhao, Jingtao; Wei, Helong; Yang, Shouye; Bai, Fenglong; Zhang, Daolai; Ding, Xue; Wang, Libo

2014-02-01

137

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

SciTech Connect

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 surface area when developing and using dissolution rate models for clay minerals and other heterogeneous materials in the environment.

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

2012-09-01

138

Ammonia transformations and abundance of ammonia oxidizers in a clay soil underlying a manure pond.  

PubMed

Unlined manure ponds are constructed on clay soil worldwide to manage farm waste. Seepage of ammonia-rich liquor into underlying soil layers contributes to groundwater contamination by nitrate. To identify the possible processes that lead to the production of nitrate from ammonia in this oxygen-limited environment, we studied the diversity and abundance of ammonia-transforming microorganisms under an unlined manure pond. The numbers of ammonia-oxidizing bacteria and anammox bacteria were most abundant in the top of the soil profile and decreased significantly with depth (0.5 m), correlating with soil pore-water ammonia concentrations and soil ammonia concentrations, respectively. On the other hand, the numbers of ammonia-oxidizing archaea were relatively constant throughout the soil profile (10(7) amoA copies per g(soil)). Nitrite-oxidizing bacteria were detected mainly in the top 0.2 m. The results suggest that nitrate accumulation in the vadose zone under the manure pond could be the result of complete aerobic nitrification (ammonia oxidation to nitrate) and could exist as a byproduct of anammox activity. While the majority of the nitrogen was removed within the 0.5-m soil section, possibly by combined anammox and heterotrophic denitrification, a fraction of the produced nitrate leached into the groundwater. PMID:22385337

Sher, Yonatan; Baram, Shahar; Dahan, Ofer; Ronen, Zeev; Nejidat, Ali

2012-07-01

139

The growth of multi-walled carbon nanotubes on natural clay minerals (kaolinite, nontronite and sepiolite)  

NASA Astrophysics Data System (ADS)

The suitability of clay minerals - kaolinite, nontronite and sepiolite - is studied for synthesis of nanocomposites based on carbon nanotubes. Particles of iron were used as catalysts. Prior to synthesis, kaolinite and sepiolite were doped by the catalytically active metal, whereas in the case of nontronite the presence was used of this metal in the matrix of this mineral. Synthesis of CNTs was performed by hot filament chemical vapor deposition method. The produced nanocomposites were examined by transmission and scanning electron microscopies and energy dispersive X-ray spectroscopy. The experiment verified the potential of the three microcrystalline phyllosilicates for the growth of carbon nanotubes. Under the same technology conditions, the type of catalyst carrier affects the morphology and structure of the nanotube product markedly.

Pastorková, K.; Jesenák, K.; Kadle?íková, M.; Breza, J.; Kolma?ka, M.; ?aplovi?ová, M.; Laziš?an, F.; Michalka, M.

2012-01-01

140

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

NASA Technical Reports Server (NTRS)

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 >60degC in the presence of water. Given estimated geothermal gradients on Mars temperatures <60 degC might still be consistent with (but do not require) moderate burial. However, our ability to identify interstratified minerals is greatly limited by the lack of access to traditional treatments methods used in the lab (e.g., ethylene glycol solvation). Our preferred explanation for the origin of trioctahedral smectites in Sheepbed mudstone is in situ production via reaction of olivine, water and Si-bearing amorphous material, an important mudstone component detected by XRD. Elevated levels of magnetite in the Sheepbed and the trioctahedral monomineralic nature of the clay minerals support this model. These observations, combined with previous studies of olivine stability, support the persistence of circum-neutral hydrous conditions for thousands of years at YKB.

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

141

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

NASA Technical Reports Server (NTRS)

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 heating >60 C in the presence of water. Given estimated geothermal gradients on Mars temperatures <60 C might still be consistent with (but do not require) moderate burial. However, our ability to identify interstratified minerals is greatly limited by the lack of access to traditional treatments methods used in the lab (e.g., ethylene glycol solvation). Our preferred explanation for the origin of trioctahedral smectites in Sheepbed mudstone is in situ production via reaction of olivine, water and Si-bearing amorphous material, an important mudstone component detected by XRD. Elevated levels of magnetite in the Sheepbed and the trioctahedral monomineralic nature of the clay minerals support this model. These observations, combined with previous studies of olivine stability, support the persistence of circum-neutral hydrous conditions for thousands of years at YKB.

Bristow, Thomas F.; Blake, David F.

2014-01-01

142

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

USGS Publications Warehouse

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.

Glanzman, Richard K.; Rytuba, James J.

1979-01-01

143

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

NASA Astrophysics Data System (ADS)

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

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

2005-09-01

144

An Assessment of the Reliability of Mineral Abundance Estimates Derived from TES Data over Dune Sites  

NASA Astrophysics Data System (ADS)

Overlapping and adjacent TES emissivity data of a dune site was analyzed to evaluate mineral abundances. An error analysis was done to test the repeatability of the data using the Analysis of Variance (ANOVA) technique.

Ahrens, C. J.; Titus, T. N.

2014-07-01

145

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

NASA Technical Reports Server (NTRS)

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

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

1985-01-01

146

Kinetics of Ion Exchange on Clay Minerals and Soil: II. Elucidation of Rate-limiting Steps1 R. A. OGWADA ANDD. L. SPARKS2  

E-print Network

Kinetics of Ion Exchange on Clay Minerals and Soil: II. Elucidation of Rate-limiting Steps1 R. A, diffusion, reaction kinetics, K-ion selective electrode, energies of activation. Ogwada, R.A., and D.L. Sparks. 1986. Kinetics of ion exchange on clay minerals and soil: II. Elucidation of rate-limiting steps

Sparks, Donald L.

147

Authigenic clay minerals in sandstones of the Delaware Mountain Group: Bell Canyon and Cherry Canyon Formations, Waha Field, West Texas  

E-print Network

AUTHIGENIC CLAY MINERALS IN SANDSTONES OF THE DELAWARE MOUNTAIN GROUP: BELL CANYON AND CHERRY CANYON FORMATIONS, WAHA FIELD, WEST TEXAS A Thesis by SUZETTE DENISE WALLING Submitted to the Office of Graduate Studies of Texas A&M University... Minerals in Sandstones of the Delaware Mountain Group: Bell Canyon and Cherry Canyon Formations, Waha Field, West Texas. (December 1992) Suzette Denise Walling, B. S. , Texas A8tM University Chair of Advisory Committee: Dr. Thomas T. Tieh Late...

Walling, Suzette Denise

2012-06-07

148

Water adsorption on model atmospheric clay minerals as a function of relative humidity: Application of experimental results to Adsorption Activation Theory  

NASA Astrophysics Data System (ADS)

The indirect aerosol effect on climate includes radiative effects from aerosol particles that take up water and form cloud droplets or alter the radiative properties and lifetimes of clouds. This effect is currently one of the largest uncertainties in understanding climate change. Natural aerosols, including mineral dust, have received little attention with respect to their contribution to indirect forcing largely due to the difficulties arising from laboratory measurements. In the past, atmospheric climate models have neglected the potentially significant effect of mineral dust aerosol on the indirect climate effect. However, a number of recent studies have revealed the importance of adsorbed water on the surface of minerals for predicting their CCN activity. Laboratory water adsorption measurements on the three most abundant clay minerals found in the atmosphere using an ATR-FTIR equipped with a flow cell will be reported. The FHH adsorption isotherm model was applied to the experimental results and resulting adsorption parameters have been used in FHH-Adsorption Activation Theory (FHH-AT) in an effort to provide adsorption parameters to predict CCN activation of mineral dust aerosol in the atmosphere.

Hatch, C. D.; Greenaway, A. L.; Harris, K. J.; Christie, M. J.

2012-12-01

149

Mineral abundance determination: Quantitative deconvolution of thermal emission spectra  

Microsoft Academic Search

A linear retrieval (spectral deconvolution) algorithm is developed and applied to high-resolution laboratory infrared spectra of particulate mixtures and their end- members. The purpose is to place constraints on, and test the viability of, linear spectral deconvolution of high-resolution emission spectra. The effects of addition of noise, data reproducibility, particle size variation, an increasing number of minerals in the mixtures,

Michael S. Ramsey; Philip R. Christensen

1998-01-01

150

Mineralogy and chemistry of altered Icelandic basalts: Application to clay mineral detection and understanding aqueous environments on Mars  

NASA Astrophysics Data System (ADS)

We used a suite of techniques, including those emulating compositional data sets obtained from Mars orbit and obtainable at the Mars surface, to examine aqueous alteration of basaltic rocks from Iceland as a mineralogic and geochemical analog for Noachian environments on Mars. A sample suite was collected for laboratory measurement of (1) whole-rock visible/near-infrared (VNIR) reflectance and thermal infrared (TIR) emission spectra; (2) VNIR and TIR reflectance spectra of particle-size separates derived from the bulk rock and from materials extracted from fractures/vesicles; (3) X-ray diffraction (XRD) patterns for determination of quantitative modal mineralogy; (4) major element chemistry using flux fusion of whole-rock powders; and (5) electron microprobe analyses of minerals in thin sections. Conclusions about aqueous alteration can be influenced by technique. For these basalts, whole-rock chemical data showed scant evidence for chemical fractionation, but TIR, VNIR, and XRD measurements identified distinctive assemblages of hydrous silicate minerals, differing by sample. XRD provided the most complete and accurate quantitative determination of sample mineralogy. However, VNIR spectroscopy was the technique most useful for determining composition of low-abundance smectite clays, and TIR spectroscopy was the most useful for recognizing hydrated silicates in thin surface coatings. High spatial resolution mineralogical and chemical data sets were useful for understanding the texture and distribution of alteration products and variations in fluid chemistry. No single approach provides a complete assessment of the environment of alteration, demonstrating the importance of employing multiple, synergistic mineralogical and geochemical techniques and instruments in exploration of rock strata from aqueous paleoenvironments on Mars.

Ehlmann, B. L.; Bish, D. L.; Ruff, S. W.; Mustard, J. F.

2012-10-01

151

The differences in clay minerals between the northern and southern Chelungpu fault, Taiwan  

NASA Astrophysics Data System (ADS)

In 1999, we obtained a detailed data about motion of fault from the Taiwan Chi-Chi earthquake. The motion represents the high frequency of acceleration and small slip distance in southern part, and low frequency of acceleration and large slip distance in the northern part. Those differences in the fault motion between the southern and northern parts are coincidence with occurrences of deformation textures of rocks which were sampled by drilling of shallow parts (a few hundreds meter) of the fault in 2000. In the southern core, a relatively strong deformation structure is preserved in total, and gouge containing fragments of pseudotachylytes and ultracataclasites is observed at the Chi-Chi- earthquake fault, which indicates that the main deformation mechanisms for the southern part of the fault was brittle. On the other hands, in the northern part, sand layer with much amount of water is found at the Chi-Chi- earthquake fault zone, and no breakage of sand grain is observed, which suggests that the deformation mechanism for northern part is independent particulate flow. The purpose of this study is to reveal the differences in clay minerals between the southern and northern part of the Chi-Chi earthquake fault. And then, we discuss about rock-fluid interaction and frictional heating characterized in seismogenic fault system. We analyzed clay minerals by X-ray diffract meter (XRD) after classification of rock types such as sandstone, alteration of sandstone and mudstone, breccia, and gouge. 1.33 micron meter of grains are obtained. Oriented sample was made. XRD analysis was conducted under following condition; 35kV, 15mA, 1 degree per minute of scan rate, and 0.02 degree of scan step. Range of 2 theta was from 2 degree to 35 degree. At first, air-dried condition of samples was measured. After that, ethylene glycol solvated samples were measured. The result represents that all samples contain smectite, illite, chlorite. No difference in components of clay mineral is observed between the southern and northern site. We focused on Chlorite which is contained in all analyzed samples. Total number of iron and magnesium (Y value), or asymmetry of iron between silicate layer and hydroxide layer (D value) is affected by pH of fluid when the chlorite is precipitated. In the northern site, Y value increases and D value decrease in gouge relatively to that in other rocks. On the other hand, in southern site, Y value decreases and D value increases in gouge which is located just at the Chi-Chi earthquake fault. This result suggests that pH of fluid differed at the time of fault activities. One of the possibilities of this cause is radical reaction. The differences of deformation mechanisms between the southern site and northern may be affected by whether radical reaction occurred or not at the time of chlorite precipitation. Other characteristic in clay mineral is smectite consumption. Illite% to smectite of host rock represents about 96% in average. Whereas, some gouge samples have no smectite. Smectite-illite transition is mainly affected by temperature. Treated samples are about 15cm in size. Therefore, this smectite consumption may be due to localized heating, which may be frictional heating. Temperature loggings after 1.5 year from the Chi-Chi- earthquake represent temperature anomalies both in the northern and southern site. If those temperature anomalies are due to frictional heating, localized increment in temperature is about a few tens degrees Celsius in the order. This temperature rise can not consume smectite to transit to illite from 96% to under 1%. Therefore, the smectite consumption may be integrated result of repetition of frictional heating in seismic history.

Hashimoto, Y.

2004-12-01

152

Sedimentary processes on the Mekong subaqueous delta: Clay mineral and geochemical analysis  

NASA Astrophysics Data System (ADS)

Sedimentary processes on the inner Mekong Shelf were investigated by examining the characteristics of sediments sampled in gravity cores at 15 locations, including grain size, clay mineralogy, sediment accumulation rates, and the elemental and stable carbon isotopic composition of organic matter (atomic C/N ratios and ?13C). Deltaic deposits exhibit contrasting characteristics along different sides of the delta plain (South China Sea, SCS hereafter, to the east and Gulf of Thailand, GOT hereafter, to the west) as well as on and off the subaqueous deltaic system. On one hand, cores recovered from the subaqueous delta in the SCS/GOT are consisted of poorly/well sorted sediments with similar/different clay mineral assemblage with/from Mekong sediments. Excess 210Pb profiles, supported by 14C chronologies, indicate either "non-steady" (SCS side) or "rapid accumulation" (GOT side) processes on the subaqueous delta. The ?13C and C/N ratio indicate a mixture of terrestrial and marine-sourced organic matter in the deltaic sediment. On the other hand, cores recovered from areas with no deltaic deposits or seaward of the subaqueous delta show excess 210Pb profiles indicating "steady-state" accumulation with a greater proportion of marine-sourced organic matter. Core analysis's relevance with local depositional environment and previous acoustic profiling are discussed.

Xue, Zuo; Paul Liu, J.; DeMaster, Dave; Leithold, Elana L.; Wan, Shiming; Ge, Qian; Nguyen, Van Lap; Ta, Thi Kim Oanh

2014-01-01

153

CLAY MINERALOGY OF INSOLUBLE RESIDUES IN MARINE EVAPORITES.  

USGS Publications Warehouse

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

Bodine, Marc W., Jr.

1985-01-01

154

Structural charge site influence on the interlayer hydration of expandable three-sheet clay minerals  

USGS Publications Warehouse

Previous investigations have demonstrated the influences of interlayer cation composition, relative humidity, temperature, and magnitude of interlayer surface charge on the interlayer hydration of montmorillonites and vermiculites. It has been suggested that the sites of layer charge deficiencies may also have an influence upon the amount of hydration that can take place in the interlayers of expandable clay minerals. If the interlayer cation-to-layer bonds are considered as ideally electrostatic, the magnitude of the forces resisting expansion may be expressed as a form of Coulomb's law. If this effect is significant, expandable structures in which the charge-deficiency sites are predominantly in the tetrahedral sheet should have less pronounced swelling properties than should structures possessing charge deficiencies located primarily in the octahedral sheet. Three samples that differed in location of layer charge sites were selected for study. An important selection criterion was a non-correlation between tetrahedral charge sites and high surface-charge density, and between octahedral charge sites and low surface-charge density. The effects of differences in interlayer cation composition were eliminated by saturating portions of each sample with the same cations. Equilibrium (001) d values at controlled constant humidities were used as a measure of the relative degree of interlayer hydration. Although no correlation could be made between the degree of interlayer hydration and total surface-charge density, the investigation does not eliminate total surface-charge density as being significant to the swelling properties of three-sheet clay-mineral structures. The results do indicate a correlation between more intense expandability and predominance of charge deficiencies in the octahedral sheet. Conversely, less intense swelling behavior is associated with predominantly tetrahedral charge deficiencies. ?? 1968.

Kerns, R.L., Jr.; Mankin, C.J.

1968-01-01

155

Removal of organic pollutants in model water and thermal wastewater using clay minerals.  

PubMed

Water treatment method was developed for the removal of different anionic dyes such as methyl orange and indigo carmine, and also for thymol applying sodium bentonite and cationic surfactant - hexadecyltrimethylammonium bromide (HTAB) - or polyelectrolytes (polydiallyldimethylammonium chloride, poly-DADMAC and poly-amines). The removal efficiency of these model substrates was examined in model water using UV-Vis spectrophotometry, HPLC and TOC analysis. The clay mineral and HTAB were added in one step to the polluted model water in Jar-test experiments. The influence of the cation exchange capacity (CEC) of the applied clay mineral and the presence of polyaluminium chloride coagulant (BOPAC) were also tested for the water treatment process. The structures of the in situ produced and pre-prepared organoclay composites were compared by XRD analysis. The rapid formation of organoclay adsorbents provided very efficient removal of the dyes (65-90 % in 3-10 mg/L TOC(0) range) with 200 mg/L sodium bentonite dose, however thymol was less efficiently separated. Adsorption efficiencies of the composites were compared at different levels of ion exchange such as at 40, 60 and 100 %. In the case of thymol, the elimination of inorganic carbon from the model water before the TOC analysis resulted in some loss of the analysed volatile compound therefore the HPLC analysis was found to be the most suitable tool for the evaluation of the process. This one-step adsorption method using in situ formed organoclay was better performing than the conventional process in which the montmorillonite-surfactant composite is pre-preapared and subsequently added to the polluted water. The purification performance of this method was also evaluated on raw and artificially polluted thermal wastewater samples containing added thymol. PMID:21929471

Szabó, Emese; Vajda, Krisztina; Veréb, Gábor; Dombi, András; Mogyorósi, Károly; Ábrahám, Imre; Májer, Marcell

2011-01-01

156

Adsorption of coliphages T1 and T7 to host and non-host microbes and to clay minerals  

Microsoft Academic Search

The clay minerals, kaolinite (K) and montmorillonite (M), suspended in either distilled water (DW) or a minimal medium (M-9), were better adsorbents for coliphages T1 or T7 than were bacteria (including early log, late log, or stationary phase cultures of the hosts), actinomycetes, and yeasts. Except for the host bacteria, the microbial cells (regardless of their type, phase of growth,

Milton Schiffenbauer; G. Stotzky

1983-01-01

157

Sorption of different cations onto clay minerals: Modelling approach with ion exchange and surface complexation  

NASA Astrophysics Data System (ADS)

The present article investigates the sorption of heavy metals, U(VI) and Eu(III), as an analog of An(III), on montmorillonite, illite and kaolinite suspensions in aqueous Na-electrolyte solutions by applying the Gibbs energy minimization computer code. Due to the complex nature of the sorption process, several simplifying assumptions should be made to solve the problem. The cation exchange capacity of clays, the density of the aluminol (>AlOH) and silanol (>SiOH) edge-type sites, responsible for the pH-dependent surface complexation, their acidity constants were derived from the reference data and fixed as non-adjustable parameters. The site-binding constants for all selected cations were calculated according to the direct correlations with their aqueous hydrolysis constants, and an exchange parameter Kex was accepted depending on the clay type, the valence of the exchanging cations and the solid to liquid ratio. The last parameters could be adjusted for goodness of fit in some cases. Relatively good correspondence between model sorption edges, distribution coefficients and those from experimental measurements was found; moreover, these observations are also consistent with the conceptual framework of the abundant reference data. The comparative model presented here is aimed to predict sorption uptake of cations over the whole spectrum of conditions in real systems having complex solid phase composition and water chemistries.

Gaskova, Olga L.; Bukaty, Mikhail B.

158

Mineral abundance determination: Quantitative deconvolution of thermal emission spectra  

Microsoft Academic Search

A linear retrieval (spectral deconvolution) algorithm is developed and applied to high-resolution laboratory infrared spectra of particulate mixtures and their end-members. The purpose is to place constraints on, and test the viability of, linear spectral deconvolution of high-resolution emission spectra. The effects of addition of noise, data reproducibility, particle size variation, an increasing number of minerals in the mixtures, and

Michael S. Ramsey; Philip R. Christensen

1998-01-01

159

Characteristics of Microstructure and Clay Minerals of Fault Gouges From Surface Rupture of Wenchuan Ms8.0 Earthquake  

NASA Astrophysics Data System (ADS)

Field investigations after the Ms 8.0 Wenchuan earthquake show that the Beichuan-Yingxiu fault mainly ruptured in the loose sediments, but some co-sesimic fault profiles in the bed rock are found. In this study, we give the characteristics microstructure and clay minerals of the co-sesimic fault gouge. Fault profiles show a significant damage zones, including fault breccia, old fault gouge and new fault gouge. The structures of fault damage zone are strongly dependent on wall rocks. When the wall rocks are including many type of rocks and the strength rocks between the hanging wall and the footwall of the fault are very different, the fault gouge are thicker layer, and the structure of fault slip zones are more complex, which are consisted of multiple slide belts. However, when the rocks between the hanging wall and the footwall of the fault are similar, the structure of fault slip zone are rather simple, which is a single thin slide belt. Microstructure observation show that the old fault gouge with highly foliated is composed of a pale-yellow-brown clay matrix containing calcite, quartz and feldspar clasts. The latest calcite vein generation overprints the fault related fabric. The co-seismic new gouge are very fine-grained, dark color and thin thickness, and almost with none breccia, and its contact boundaries are straight and easy to distingue with old fault gouge as well as fault breccia. The clay minerals of gouge and wall rocks were analyzed using an X-ray diffractometer (XRD). Compared with wall rocks, the mineral of fault damage rocks and gouges are more complex, most of them are including Quartz, calcite, and clay minerals. In fault gouge, the proportions of clay minerals are very higher than that of breccia. In new slide gouge, percentage of illite is high than old fault gouge.

Zhou, Y.; Dang, J.; Han, L.; Chen, J.; Ma, S.; Yang, X.; He, C.

2010-12-01

160

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)

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 variable climate and weathering conditions controlled the mineralogical transformations and the arrangement of clay-mineral assemblages. The paleoclimatic reconstruction suggests a general warm and humid climate. However, the temporal trend of the clay-mineral assemblages, the ratios between smectite and kaolinite and the micromorphological analysis of clay minerals contrasted with evidence from sedimentological analyses suggest a warm and seasonal climate for the basal part of the unit, a warm and humid climate with a relatively more perennial rainfall regime in the middle part of the unit, and a warm and less humid, probably subhumid, climate up-section. Such a reconstruction makes it possible to establish a correlation with some of the hyperthermal events of the Early Paleogene Global Warming (EPGW) and, consequently, constitute one of the most complete time records of the EPGW in South America.

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

2014-07-01

161

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

NASA Astrophysics Data System (ADS)

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

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

1993-02-01

162

The study of the soil clay minerals within the framework of the integrated research headed by N.I. Bazilevich  

NASA Astrophysics Data System (ADS)

The main areas of the integrated biogeochemical studies performed under the supervision of N.I. Bazilevich dealing with the investigation of soil minerals were considered. The development of the clay profiles in soils under the effect of chernozem formation, solodization, salinization, solonetzization, and gleyzation, the spatial differentiation of which favored the development of the pronounced complexity of the soil cover in the forest-steppe zone of the Baraba Lowland, was described. It was shown that irrigation with sodic water induces the evolution of chernozems to solodized soils due to the dispersion and destruction of the clay minerals. The behavior of the minerals in the sodic solonetz-solonchaks of Armenia during their reclamation with sulfuric acid and iron (II) sulfate was explained. The effect of the root exudates from black saxaul ( Haloxylon aphyllum) on the transformation of the layered silicates in the rooting zone of sandy desert soils was noted.

Chizhikova, N. P.

2010-11-01

163

Interplay between cataclasis, clay mineral diagenesis and porosity reduction in deformation bands in unconsolidated arkosic sands  

NASA Astrophysics Data System (ADS)

As a response to tectonic and gravitational stresses, unconsolidated sediments can develop zones of localized deformation, commonly described as deformation bands. These are tabular fault zones in high porosity rocks and sediments characterized by small offsets causing reduction of porosity through grain rotation, translation and fracturing. Classified by deformation mechanism and depth of formation, there are two main types of deformation bands: disaggregation bands, where compaction is achieved only by grain rotation and translation, and cataclastic bands, which show intense grain size reduction by grain fracturing. In various examples the porosity and permeability reduction in these fault zones inhibits the flow of fluids. The timing of deformation band formation relative to diagenesis and fluid migration is relevant in relation to the quality and connectivity of hydrocarbon or groundwater reservoirs. The investigated outcrop in a sandpit near Eisenstadt (Eisenstadt-Sopron Basin, Austria) exposes numerous conjugate deformation bands, which are formed in lower Miocene uncemented, arkosic sands and gravels. These deformation bands formed at shallow burial depth (< 1km) and are kinematically related to the nearby Eisenstadt Fault. This outcrop offers the unique possibility to investigate deformation bands with identical kinematic boundary conditions in highly variable sediments, i.e. with a wide range of different grain sizes from fine sand to coarse gravel, variable porosity and mineral content, different stages of diagenesis and carbonate-free or carbonatic sediments. The fact that cataclasis is one of the dominant mechanisms at these shallow depths (< 1km) is unusual and an exception to most cataclastic bands described in literature. This is probably related to the composition, coarse grain size and the high porosity of the sediments. The coarse host sediment mainly consists of detrital quartz, albite, biotite, sericite, muscovite and metamorphic lithoclasts. The dominant deformation mechanisms and the magnitude of porosity reduction in the carbonate-free lithologies are controlled by the initial mica content, mean grain size, level of alteration and albite content in the host rock. The studied deformation bands show a preferred fracturing of sericitized albite grains and the smearing of micas into the pore space. These processes increase the amount of phyllosilicates in the pore space and facilitate the growth of various authigenic clay minerals like smectite, vermiculite, kaolinite and illite. Because of the changed petrophysical properties the deformation bands show a different diagenetic evolution in comparison with the host rock. We identified 4 steps in the development from a high-porosity host rock to a low porosity deformation band. The measured reduction in porosity by up to 18% is associated with a permeability reduction, reflected in the retention of fluids along the deformation bands with the highest content of authigenic clay minerals.

Lommatzsch, Marco; Exner, Ulrike; Gier, Susanne

2013-04-01

164

Abundance and distribution of mineral components associated with Moses Rock (kimberlite) diatreme  

NASA Technical Reports Server (NTRS)

The surface mineralogy in and around Moses Rock diatreme, a kimberlite-bearing dike in SW Utah, was examined using internally calibrated Airborne Imaging Spectrometer (AIS) data. Distinct near-infrared absorption characteristics of clays, gypsum, and serpentine (a key marker for kinberlite concentration) allowed the surface units containing these components to be identified spatially and the relative abundance of each component measured. Within the dike itself, channels and dispersed components of kimberlite and blocks of country rocks were accurately determined.

Mustard, J. F.; Pieters, C. M.

1986-01-01

165

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

NASA Astrophysics Data System (ADS)

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

Miloševi?, Maja; Logar, Mihovil

2013-04-01

166

Experimental evidence that nucleation of ice on clay mineral dust is a stochastic process  

NASA Astrophysics Data System (ADS)

Mixed phase clouds are very sensitive to the presence of solid particles that can catalyse freezing. Unfortunately, the rates and mechanisms through which atmospheric aerosol nucleate ice are poorly constrained. We will present new experimental data which challenges the widely held, although not ubiquitous, view that heterogeneous ice nucleation is a singular process in which time is a secondary factor. A new experimental approach has been developed in which the time and temperature dependence of nucleation can be separated (Murray et al., 2010a;Murray et al., 2010b). In this contribution we describe experiments to determine the rate at which kaolinite and montmorillonite nucleate ice when immersed within water droplets. These are the first immersion mode experiments in which the ice nucleating ability of individual minerals has been determined as a function of both clay surface area and cooling rate. Water droplets containing a known amount of clay mineral were supported on a hydrophobic surface and cooled at rates of between 0.8 and 10 K min-1. The temperatures at which individual 10-40 µm diameter droplets froze were determined by optical microscopy. As the concentration of kaolinite in the droplets was increased from 0.005 wt% to 1 wt% the median nucleation temperature increased from close to the homogeneous nucleation limit (236 K) to 240.8 ± 0.6 K for a cooling rate of 10 K min-1. This data shows that the probability of freezing scales with surface area of the kaolinite inclusions. We also show that the number of liquid droplets containing kaolinite decays exponentially with time when held at a temperature of 242 K. This, in addition to other experiments with variable cooling rates, provides compelling evidence that ice nucleation by kaolinite in the immersion mode can be described by a stochastic model (i.e. time dependent). We report temperature dependent nucleation rate coefficients (per unit time per unit area) for kaolinite and present a general parameterisation for immersion nucleation which may be suitable for cloud modelling. We also report freezing temperatures for droplets containing montmorillonite at a range of concentrations. We have not reported a parameterisation for the temperature dependent nucleation rate for this material because the nucleation probability in our experiments does not scale with the montmorillonite concentration. However, for a single concentration, rate coefficients do scale with cooling rate indicating that nucleation is time dependent. Further work to investigate ice nucleation by montmorillonite particles as well as other atmospherically relevant minerals is required. Our results highlight the importance of understanding the ice nucleating properties of individual minerals and how this information may be used to understand nucleation by complex mixtures of minerals found in natural dusts. Murray et al.: Kinetics of the homogeneous freezing of water, Phys. Chem. Chem. Phys., 12, 10380-10387, 2010a. Murray et al.: Heterogeneous freezing of water droplets containing kaolinite and montmorillonite particles, Atmos. Chem. Phys. Discuss., 10, 9695-9729, 2010b.

Murray, B. J.; Wilson, T. W.; Broadley, S. L.; Atkinson, J. D.

2010-12-01

167

Simple algorithms for remote determination of mineral abundances and particle sizes from reflectance spectra  

NASA Technical Reports Server (NTRS)

Algorithms were developed, based on Hapke's (1981) equations, for remote determinations of mineral abundances and particle sizes from reflectance spectra. In this method, spectra are modeled as a function of end-member abundances and illumination/viewing geometry. The method was tested on a laboratory data set. It is emphasized that, although there exist more sophisticated models, the present algorithms are particularly suited for remotely sensed data, where little opportunity exists to independently measure reflectance versus article size and phase function.

Johnson, Paul E.; Smith, Milton O.; Adams, John B.

1992-01-01

168

Broad-spectrum in vitro antibacterial activities of clay minerals against antibiotic-susceptible and antibiotic-resistant bacterial pathogens  

PubMed Central

SYNOPSIS Objectives The capacity to properly address the worldwide incidence of infectious diseases lies in the ability to detect, prevent, and effectively treat these infections. Therefore, identifying and analyzing inhibitory agents are worthwhile endeavors in an era when few new classes of effective antimicrobials have been developed. The use of geological nanomaterials to heal skin infections has been evident since the earliest recorded history, and specific clay minerals may prove valuable in the treatment of bacterial diseases, including infections for which there are no effective antibiotics, such as Buruli ulcer and multi-drug resistant infections. Methods We have subjected two iron-rich clay minerals, which have previously been used to treat Buruli ulcer patients, to broth culture testing of antibiotic-susceptible and -resistant pathogenic bacteria to assess the feasibility of using clay minerals as therapeutic agents. Results One specific mineral, CsAg02, demonstrated bactericidal activity against pathogenic Escherichia coli, extended-spectrum ?-lactamase (ESBL) E. coli, S. enterica serovar Typhimurium, Pseudomonas aeruginosa, and Mycobacterium marinum and a combined bacteriostatic/bactericidal effect against Staphylococcus aureus, penicillin-resistant S. aureus (PRSA), methicillin-resistant S. aureus (MRSA), and Mycobacterium smegmatis, while another mineral with similar structure and bulk crystal chemistry, CsAr02, had no effect on or enhanced bacterial growth. The <0.2 ?m fraction of CsAg02 and CsAg02 heated to 200°C or 550°C retained bactericidal activity, while cation-exchanged CsAg02 and CsAg02 heated to 900°C no longer killed E. coli. Conclusions Our results indicate that specific mineral products have intrinsic, heat-stable antibacterial properties, which could provide an inexpensive treatment against numerous human bacterial infections. PMID:18070832

HAYDEL, SHELLEY E.; REMENIH, CHRISTINE M.; WILLIAMS, LYNDA B.

2008-01-01

169

Stochastic Approach to Determine CO2 Hydrate Induction Time in Clay Mineral Suspensions  

NASA Astrophysics Data System (ADS)

A large number of induction time data for carbon dioxide hydrate formation were obtained from a batch reactor consisting of four independent reaction cells. Using resistance temperature detector(RTD)s and a digital microscope, we successfully monitored the whole process of hydrate formation (i.e., nucleation and crystal growth) and detected the induction time. The experiments were carried out in kaolinite and montmorillonite suspensions at temperatures between 274 and 277 K and pressures ranging from 3.0 to 4.0 MPa. Each set of data was analyzed beforehand whether to be treated by stochastic manner or not. Geochemical factors potentially influencing the hydrate induction time under different experimental conditions were investigated by stochastic analyses. We observed that clay mineral type, pressure, and temperature significantly affect the stochastic behavior of the induction times for CO2 hydrate formation in this study. The hydrate formation kinetics along with stochastic analyses can provide basic understanding for CO2 hydrate storage in deep-sea sediment and geologic formation, securing its stability under the environments.

Lee, K.; Lee, S.; Lee, W.

2008-12-01

170

Interactions of Clay Minerals and a Layered Double Hydroxide with Water Stable, Nano Scale Fullerene Aggregates (nC 60)  

Microsoft Academic Search

The research presented details specific interactions of underivatized C60 as an aggregate suspension in water (termed nC60) with clay minerals (montmorillonite and kaolinite), and a synthetic layered double hydroxide LDH. Batch and 1-D flow-through column interactions were analysed via UV\\/Vis spectroscopy, X-ray diffraction analysis, and transmission electron microscopy. Results indicate that nC60 suspended in water interacted with all the solid

J. D. Fortner; C. Solenthaler; J. B. Hughes; A. M. Puzrin; M. Plötze

171

Failure of Dietary Bentonite Clay, Silent Herder® Mineral Supplement, or Parenteral Banamine® to Alleviate Locoweed Toxicosis in Rats1  

Microsoft Academic Search

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 ben- tonite clay (1.5% of diet). Pregnant female rats fed 10% LW were treated i.m. with Banamine® (a prostaglandins suppressor) or saline. The LW con- tained

Mari Dugarte-Stavanja; G. Stanley Smith; Thomas S. Edrington; Dennis M. Hallford

172

New information on the glacial history of the NW Barents Sea from clay minerals and radiocarbon dates  

NASA Astrophysics Data System (ADS)

Here we present results from new analyses on marine sediment cores that recovered subglacial and postglacial units deposited in the NW Barents Sea during the LGM and the Holocene. We have performed a pilot study on clay-mineral assemblages in three cores collected in palaeo-ice stream troughs surrounding Nordaustlandet (Hinlopen, Erik Eriksen and Kvitøya troughs) to investigate the provenance and pathways of subglacial sediment transported by the Barents Sea Ice Sheet (BSIS) during the LGM and of Holocene marine sediments. In all of the cores there is a clear change in clay mineral composition between the subglacial diamicts and the postglacial muds, and the clay-mineral assemblage in the diamicts is distinctive in each core. This suggests that the clay mineral composition records different pathways of subglacially transported detritus around eastern Svalbard. We interpret these data in relation to local source rocks on the Svalbard archipelago and in the central Barents Sea in order to provide new information regarding the BSIS dynamics during the last glacial period, about which there is still considerable debate for the central-northern Barents Sea sector (cf. Landvik and Ingolfsson, 2013). In addition, new radiocarbon ages from sediment cores around Nordaustlandet suggest that grounded ice had retreated from the shelf break north of Nordaustlandet and in Kvitøya Trough east of Svalbard by 13.3-13.6 14C kyrs BP. This is in line with deglacial dates of 13-13.3 14C kyrs BP from the other major troughs on the northern Barents Sea margin (Saint Anna and Franz Victoria troughs). In Hinlopen Trough our deglacial date confirms that the Polar Front was in the vicinity of the core site on the continental shelf some 20 km landward of the shelf break by 11.0 14C kyrs BP.

Hogan, Kelly; Dowdeswell, Julian; Hillenbrand, Claus-Dieter; Ehrmann, Werner

2014-05-01

173

Fractionation of Stable Si Isotopes During in-situ Dissolution of Feldspars and Formation of Secondary Clay Minerals  

NASA Astrophysics Data System (ADS)

It has been proposed that weathering of igneous silicate minerals may fractionate Si isotopes (Douthitt 1982, de la Rocha et al. 2000). This is supported by the observation that clays yield ?30Si compositions between +0.5‰ and -2.5‰ compared to the igneous range for ?30Si between +0.1‰ and -1‰ respectively (Douthitt 1982). The difference may relate to a discrimination against heavier Si isotopes during clay mineral formation. However, no study has yet shown a direct Si isotope fractionation between coexisting primary igneous and secondary clay mineral phases. We have measured the stable Si isotope fractionation during in-situ feldspar dissolution and formation of secondary clay minerals in the Navajo Sandstone, Black Mesa, Arizona. The Jurassic Navajo Sandstone is composed of about 94% quartz and 2-4% K-feldspar. The K-feldspar grains are covered with kaolinite, and both quartz and feldspars are covered with a mantle of smectite coating. Petrographic studies demonstrate that the clay minerals formed in situ as alteration products of feldspar, and the smectite is of a low-temperature variety (Zhu, 2005). Therefore, the Si isotope fractionation at low temperature (15-35°C) can be evaluated - something that is difficult to replicate in the laboratory. For the Si isotope analyses we used 20-30 mg of 5 separated clay samples, and 0.36 mg of hand picked feldspars. The silicates were fused with an alkaline flux and dissolved in a weak HCl acid. The dissolved Si was then separated by ion-exchange chromatography. The relative Si isotope compositions were measured using a high-resolution MC-ICP-MS (The Nu1700 at ETH Zurich) and are reported in ? notation relative to the international Si standard NBS 28. The bulk rock and separated feldspar fraction have Si isotope compositions are -0.09 ± 0.03‰ and -0.15 ±0.03 ‰ (±2?SEM) ?30Si, respectively. The clay samples have ?30Si values of -0.24 ±0.05‰, -0.16 ±0.03‰, -0.30 ±0.03‰, -0.42 ±0.03‰ and -0.52 ±0.04‰ (±2?SEM). These Si isotope analyses reveal that the majority of the clay separates are isotopically lighter by up to 0.4% compared to precursor feldspars. The results demonstrate for the first time that Si isotopes are indeed fractionated during the breakdown of feldspar minerals and the subsequent formation of isotopically lighter Si in clays. From mass-balance considerations, circulating fluids should have higher ?30Si values, however the analysis of groundwater samples show variations of ?30Si values between +0.43‰ and -1.43‰ representing the most negative dissolved Si isotope composition so far found. As groundwater constitutes 98% of the global fresh water (excluding ice), the global Si biogeochemical cycle must include groundwater as an important component that is often overlooked. References: De La Rocha, Brzezinski, and DeNiro (2000), A first look at the distribution of the stable isotopes of silicon in natural waters, GCA 64, 2467-2477; Douthitt (1982), The geochemistry of the stable isotopes of silicon, GCA 46, 1449 - 1458; Zhu (2005), In situ feldspar dissolution rates in an aquifer, GCA 69, 1435-1453.

Georg, R. B.; Reynolds, B. C.; Halliday, A. N.; Zhu, C.

2005-12-01

174

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

PubMed

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. PMID:17350665

Kahle, Maren; Stamm, Christian

2007-07-01

175

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

NASA Astrophysics Data System (ADS)

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

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

2009-12-01

176

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

PubMed

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

Kavurmaci, Sibel Sen; Bekbolet, Miray

2014-01-01

177

Oxygen isotope fractionation effects in soil water via interaction with cations (Mg, Ca, K, Na) adsorbed to phyllosilicate clay minerals  

NASA Astrophysics Data System (ADS)

In isotope-enabled hydrology, soil and vadose zone sediments have been generally considered to be isotopically inert with respect to the water they host. This is inconsistent with knowledge that clay particles possessing an electronegative surface charge and resulting cation exchange capacity (CEC) interact with a wide range of solutes which, in the absence of clays, have been shown to exhibit ?18O isotope effects that vary in relation to the ionic strength of the solutions. To investigate the isotope effects caused by high CEC clays in mineral-water systems, we created a series of monominerallic-water mixtures at gravimetric water contents ranging from 5% to 32%, consisting of pure deionized water of known isotopic composition with homoionic (Mg, Ca, Na, K) montmorillonite. Similar mixtures were also created with quartz to determine the isotope effect of non-, or very minimally-, charged mineral surfaces. The ?18O value of the water in these monominerallic soil analogs was then measured by isotope ratio mass spectrometry (IRMS) after direct headspace CO2 equilibration. Mg- and Ca-exchanged homoionic montmorillonite depleted measured ?18O values up to 1.55‰ relative to pure water at 5% water content, declining to 0.49‰ depletion at 30% water content. K-montmorillonite enriched measured ?18O values up to 0.86‰ at 5% water content, declining to 0.11‰ enrichment at 30% water. Na-montmorillonite produces no measureable isotope effect. The isotope effects observed in these experiments may be present in natural, high-clay soils and sediments. These findings have relevance to the interpretation of results of direct CO2-water equilibration approaches to the measurement of the ?18O value of soil water. The adsorbed cation isotope effect may bear consideration in studies of pedogenic carbonate, plant-soil water use and soil-atmosphere interaction. Finally, the observed isotope effects may prove useful as molecular scale probes of the nature of mineral-water interactions.

Oerter, Erik; Finstad, Kari; Schaefer, Justin; Goldsmith, Gregory R.; Dawson, Todd; Amundson, Ronald

2014-07-01

178

Glacial cycle and precessional period of clay mineral assemblage during late Quaternary in the Western Equatorial Pacific  

NASA Astrophysics Data System (ADS)

Clay mineralogy, coupled with oxygen isotope records and elemental XRF scanning data, have been conducted on Core KX21-2 recovered from the Ontong Java Plateau, Western Equatorial Pacific. The clay mineral assemblage over the last 370 kyr displays strong glacial-interglacial cyclicity, with higher contents of smectite (average 76%), lower contents of chlorite (10%), illite (8%) and kaolinite (6%) during glacials, and vice versa. Fe mainly originates from smectite, and has therefore been used to represent it. In addition to glacial cycle (100 ka), spectral analysis reveals that Fe contents also display precessional period (26.8 ka and 14.4 ka). The question is, why and how the features of high-latitude and tropical-process could be exhibited in concert? The clay mineral assemblage dominating by smectite is detrital, and derived from river sediment of New Guinea, though possibly minor Asian dust. Fluctuation of sea-level combined with contrasting styles of Source-to-Sink in New Guinea cause the glacial-interglacial cycles of clay mineral assemblage. Regardless of sea-level, river sediments can travel across the narrow shelves off the northern New Guinea and then inject directly into New Guinea Coastal Undercurrent, which finally contribute Equatorial Undercurrent. In contrast, when the sea-level were high, only few sediment could be transported from southern New Guinea to the Western Equatorial Pacific, possibly by surface current. Considering the positive correlation between contents of smectite and feldspar/quartz ratios, we conclude that, because of the limitation of weathering time, the contents of smectite essentially indicate the intensity of mechanical erosion, responding to the river runoff and precipitation. Furthermore, due to the regional precipitation pattern is under control of ITCZ, these variations of smectite reflect the meridional migration of ITCZ, indirectly.

Wu, J.; Liu, Z.; Zhou, C.

2011-12-01

179

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

SciTech Connect

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

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

2010-11-01

180

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

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.

Pollastro, R.M.

1982-01-01

181

The Timing and Distribution of Clay and Hydrated Mineral Formation in Martian Central Peaks  

NASA Astrophysics Data System (ADS)

A significant proportion of central peak clays may be postimpact (detrital/authigenic), and impact-generated clays may have formed at a constant rate through martian history. Additional hydrated silica formation may have been favored from 3.4-3.5 Ga.

Sun, V. Z.; Milliken, R. E.

2014-07-01

182

Magnetic minerals: Understanding the processes of formation in soils and clays and identifying their presence in the rock record  

NASA Astrophysics Data System (ADS)

Magnetic minerals can form authigenically in soils and sediments, but the processes involved can be complex and are often a matter of debate. For example, anomalous concentrations in magnetic minerals have been described in soils and their origin has been ascribed to a range of processes including inorganic and biological precipitation. Also, the presence of secondary magnetic minerals in sedimentary rocks has been described and their origin has been related to a variety of geologic processes such as orogenic fluid migration, presence of hydrocarbons, and clay diagenesis. Developing a better understanding for the conditions by which magnetic minerals form in soils and sediments is important because of the information they can provide to decipher the geologic past on Earth and potentially on other planets. This work presents results of biological formation of magnetite under a variety of laboratory conditions in a hydrocarbon-contaminated soil profile. Magnetite was formed only in biological samples but not in the abiotic: counterparts suggesting biological processes may be more important in the formation of magnetic minerals in soils than previously thought. A study on naturally occurring clays heated to temperatures equivalent to low burial conditions (62 and 98°C) resulted in increases in the bulk magnetic susceptibility (chib) in some smectites but not in any of the other tested clays. Furthermore, a closer look was taken at heated smectites and the authigenic magnetic grains that were formed in the process were rock magnetically characterized. The findings suggest that clay diagenetic processes occurring at low temperatures can lead to the formation of magnetite capable of carrying remanence and thus, provide a viable mechanism for the acquisition of secondary magnetizations in sedimentary rocks. Lastly, a rock magnetic comparison of two Paleozoic loessite-paleosol couplets is presented to investigate whether the enhanced chi b trends in the paleosols as compared to the loessite can be confirmed in ancient deposits. The results for one couplet are similar to those from the Chinese Loess Plateau, which have an enrichment of ferrimagnetic material in the paleosol. The second couplet, however, reveals that the variations in the chib can be more complex and shows the importance of combining rock magnetic with sedimentologic evidence in order to identify the origin and preservation of chib patterns in geologic deposits.

Cogoini, Monika

183

The MS-Q Force Field for Clay Minerals: Application to Oil Production Sungu Hwang, Mario Blanco, Ersan Demiralp, Tahir Cagin, and William A. Goddard, III*  

E-print Network

and corrosion inhibition). Among the minerals present in the walls of oil reservoirs, clay minerals are believed corrosion treatment strategies, we calculate the adsorption energy of oleic imidazoline, a corrosion in studying oil production chemicals, including corrosion inhibitors,11 scale inhibitors,12 and dissolvers.13

Ã?agin, Tahir

184

Mineralogy. Discovery of bridgmanite, the most abundant mineral in Earth, in a shocked meteorite.  

PubMed

Meteorites exposed to high pressures and temperatures during impact-induced shock often contain minerals whose occurrence and stability normally confine them to the deeper portions of Earth's mantle. One exception has been MgSiO3 in the perovskite structure, which is the most abundant solid phase in Earth. Here we report the discovery of this important phase as a mineral in the Tenham L6 chondrite and approved by the International Mineralogical Association (specimen IMA 2014-017). MgSiO3-perovskite is now called bridgmanite. The associated phase assemblage constrains peak shock conditions to ~ 24 gigapascals and 2300 kelvin. The discovery concludes a half century of efforts to find, identify, and characterize a natural specimen of this important mineral. PMID:25430766

Tschauner, Oliver; Ma, Chi; Beckett, John R; Prescher, Clemens; Prakapenka, Vitali B; Rossman, George R

2014-11-28

185

Determination of Mineral Type, Abundance, and Grain Size with Remotely Obtained Reflectance Spectra  

NASA Technical Reports Server (NTRS)

To derive the abundances of minerals in a surface composed of more then one mineral in an intimate mixture, the bidirectional reflectance spectrum must be measured at several angles of incidence and emission. From these measurements, the scattering parameters may be derived, and the effective single scattering albedo can be computed from the models. If the scattering parameters are not derived, and the particles scatter anisotropically, then the computed effective single scattering albedo has been computed, the solution to the model is a nonlinear least squares problem with three unknowns per particle type. The solution is feasible when the complex indices of refraction and the densities of each mineral component are known. The unknowns are: the grain size of each particle type, the mass fraction of each particle type, and a grain internal scattering coefficient that describes grain imperfections.

Clark, R. N.

1985-01-01

186

Three-component Langmuir-Blodgett films consisting of surfactant, clay mineral, and lysozyme: construction and characterization.  

PubMed

The Langmuir-Blodgett (L-B) technique has been employed for the construction of hybrid films consisting of three components: surfactant, clay, and lysozyme (Lys). The surfactants are octadecylammonium chloride (ODAH) and octadecyl ester of rhodamine B (RhB18). The clays include saponite and laponite. Surface pressure versus area isotherms indicate that lysozyme is adsorbed by the surfactant-clay L-B film at the air-water interface without phase transition. The UV-visible spectra of the hybrid film ODAH-saponite-Lys show that the amount of immobilized lysozyme in the hybrid film is (1.3+/-0.2) ng mm(-2). The average surface area (Omega) per molecule of lysozyme is approximately 18.2 nm(2) in the saponite layer. For the multilayer film (ODAH-saponite-Lys)(n), the average amount of lysozyme per layer is (1.0+/-0.1) ng mm(-2). The amount of lysozyme found in the hybrid films of ODAH-laponite-Lys is at the detection limit of about 0.4 ng mm(-2). Attenuated total reflectance (ATR) FTIR spectra give evidence for clay layers, ODAH, lysozyme, and water in the hybrid film. The octadecylammonium cations are partially oxidized to the corresponding carbamate. A weak 1620 cm(-1) band of lysozyme in the hybrid films is reminiscent of the presence of lysozyme aggregates. AFM reveals evidence of randomly oriented saponite layers of various sizes and shapes. Individual lysozyme molecules are not resolved, but aggregates of about 20 nm in diameter are clearly seen. Some aggregates are in contact with the clay mineral layers, others are not. These aggregates are aligned in films deposited at a surface pressure of 20 mN m(-1). PMID:20104549

Miao, Shiding; Leeman, Hugo; De Feyter, Steven; Schoonheydt, Robert A

2010-02-22

187

Protection of Nitrosomonas europaea colonizing clay minerals from inhibition by nitrapyrin  

Microsoft Academic Search

Nitrite production by Nifrosomonas europaea in inorganic liquid medium containing ammonium was limited by reduction in pH. In the presence of montmorillonite and vermiculite, expanding clays with high cation-exchange- capacity (CEC), nitrite yield was increased, ammonia oxidation continued at pH values below those which inhibited growth in the absence of clays and growth was biphasic. The first phase was similar

S. J. Powell; J. I. Prosser

1991-01-01

188

Adsorption and aggregation of a cationic cyanine dye on layered clay minerals  

Microsoft Academic Search

The adsorption and aggregation of a cationic cyanine dye, 1,1?-diethyl-2,2?-cyanine (pseudoisocyanine; abbreviated as PIC), on various clays have been investigated. The PIC formed J-aggregates on Na-montmorillonite and synthetic Na-fluor-tetrasilicic mica (TSM), while they distributed molecularly on synthetic Na-saponite and synthetic Na-hectorites. The particle size of the clays was considered to be a dominant factor to control the aggregation of PIC.

Nobuyoshi Miyamoto; Ryo Kawai; Kazuyuki Kuroda; Makoto Ogawa

2000-01-01

189

Protection of Nitrosomonas europaea colonizing clay minerals from inhibition by nitrapyrin.  

PubMed

Nitrate production by Nitrosomonas europaea in inorganic liquid medium containing ammonium was limited by reduction in pH. In the presence of montmorillonite and vermiculite, expanding clays with high cation-exchange-capacity (CEC), nitrite yield was increased, ammonia oxidation continued at pH values below those which inhibited growth in the absence of clays and growth was biphasic. The first phase was similar to that in the absence of clays, while the second was characterized by a lower rate of nitrite production. Illite, a non-expanding clay with low CEC, had no significant effect on ammonia oxidation, while oxidation of ammonia-treated vermiculite (ATV) occurred with no significant change in the pH of the medium. ATV, montmorillonite and vermiculite, but not illite, protected cells from inhibition by nitrapyrin at concentrations inhibitory to cells growing in suspended culture. This protection was maintained in ATV homo-ionic to Al3+, but montmorillonite made homo-ionic to Al3+ did not provide protection from inhibition. Attachment of cells to clays with high CEC is therefore advantageous in providing exchange at the clay surface of NH+4 and H+ produced by ammonia oxidation, in reducing pH toxicity, and in protecting cells from inhibition. PMID:1955871

Powell, S J; Prosser, J I

1991-08-01

190

Seismic stratigraphy and clay mineral distribution in shallow-marine siliciclastic deposits, central Mississippi sound, North-central Gulf of Mexico  

Microsoft Academic Search

Three north-south high-resolution (7 kHz) seismic profiles and 16 20-foot cores taken at shot-point locations in central Mississippi Sound were utilized to determine: (1) any meaningful seismic reflector configurations in the subsurface; (2) the clay species dispersal pattern and its relation to transport systems that move sediment into the depositional basin; (3) any change in clay mineral species that has

G. G. Harper; F. H. Manley; A. C. Staheli

1983-01-01

191

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

NASA Astrophysics Data System (ADS)

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

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

2012-09-01

192

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

NASA Astrophysics Data System (ADS)

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

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

2010-01-01

193

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

NASA Astrophysics Data System (ADS)

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

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

2009-02-01

194

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

NASA Technical Reports Server (NTRS)

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.

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

1981-01-01

195

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

NASA Astrophysics Data System (ADS)

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

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

196

On-going laboratory efforts to quantitatively address clay abundance on Mars  

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

197

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

NASA Astrophysics Data System (ADS)

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

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

2007-10-01

198

INFLUENCE OF TEMPERATURE ON NICKEL SORPTION ON CLAY MINERAL AND OXIDE SURFACES. K. G. Scheckel1  

E-print Network

and Methods: Pyrophyllite and talc were employed in this research because they show very little deviation from the chemical formula of an ideal 2:1 clay. The structural difference between talc and pyrophyllite is that talc. By using talc, Al3+ will not be present in solution which is believed to be the driving mechanism behind

Sparks, Donald L.

199

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...

200

CARBON SEQUESTRATION IN CLAY MINERAL FRACTIONS FROM 14C-LABELED PLANT RESIDUES  

Technology Transfer Automated Retrieval System (TEKTRAN)

An understanding of organic C dynamics in soils is necessary to develop management options to enhance soil organic C sequestration. The objective of this research was to study the distribution of newly formed humic materials into mineralogically distinct clay-size fractions of a silt loam soil. Oats...

201

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

USGS Publications Warehouse

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.

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

1989-01-01

202

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

NASA Astrophysics Data System (ADS)

Caustic high level radioactive waste induces mineral weathering reactions that can influence the fate of radionuclides released in the vicinity of leaking storage tanks. The uptake and release of Cs I and Sr II were studied in batch reactors of 2:1 layer-type silicates—illite (Il), vermiculite (Vm) and montmorillonite (Mt)—under geochemical conditions characteristic of leaking tank waste at the Hanford Site in WA (0.05 m Al T, 2 m Na +, 1 m NO 3-, pH ˜14, Cs and Sr present as co-contaminants). Time series (0 to 369 d) experiments were conducted at 298 K, with initial [Cs] 0 and [Sr] 0 concentrations from 10 -5 to 10 -3 mol kg -1. Clay mineral type affected the rates of (i) hydroxide promoted dissolution of Si, Al and Fe, (ii) precipitation of secondary solids and (iii) uptake of Cs and Sr. Initial Si release to solution followed the order Mt > Vm > Il. An abrupt decrease in soluble Si and/or Al after 33 d for Mt and Vm systems, and after 190 d for Il suspensions was concurrent with accumulation of secondary aluminosilicate precipitates. Strontium uptake exceeded that of Cs in both rate and extent, although sorbed Cs was generally more recalcitrant to subsequent desorption and dissolution. After 369 d reaction time, reacted Il, Vm and Mt solids retained up to 17, 47 and 14 mmol kg -1 (0.18, 0.24 and 0.02 ?mol m -2) of Cs, and 0, 27 and 22 mmol kg -1 (0, 0.14 and 0.03 ?mol m -2) Sr, respectively, which were not removed in subsequent Mg exchange or oxalic acid dissolution reactions. Solubility of Al and Si decreased with initial Cs and Sr concentration in Mt and Il, but not in Vm. High co-contaminant sorption to the Vm clay, therefore, appears to diminish the influence of those ions on mineral transformation rates.

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

2005-09-01

203

Seismic stratigraphy and clay mineral distribution in shallow-marine siliciclastic deposits, central Mississippi sound, North-central Gulf of Mexico  

SciTech Connect

Three north-south high-resolution (7 kHz) seismic profiles and 16 20-foot cores taken at shot-point locations in central Mississippi Sound were utilized to determine: (1) any meaningful seismic reflector configurations in the subsurface; (2) the clay species dispersal pattern and its relation to transport systems that move sediment into the depositional basin; (3) any change in clay mineral species that has occurred through time with respect to deposition of 5 to 6 m (16 to 20 ft) of sediment. Interpretation of shallow seismic events (20 m (66 ft)) and clay mineral analysis indicates that extrinsic factors largely determined the clay mineral species and geologic history of Pleistocene and Holocene sedimentation in central Mississippi Sound. Trend surface maps, residual maps, profiles of the smectite (montmorillonite) to kaolinite ratios, and seismic profiles illustrate that: (1) Mississippi Sound has been influenced by transgressions and regressions associated with proglacial and interglacial stages; (2) a toplap seismic reflection configuration forms the probable Pleistocene-Holocene boundary; (3) at least one ancient barrier island is located inside the Holocene barrier system; (4) there is a late date for sea level reaching its present location (2500 years B.P.); (5) the influence of the Mississippi River system on sedimentation is soon after inundation of Mississippi Sound; (6) the longshore currents and flood tides supplied sediment rich in kaolinite to the study area; (7) the drainage systems emptying into the study area have local influence on clay mineral distribution; and (8) the dredging of ship channels affects the clay-mineral distribution within the sediments immediately below the sediment-water interface in central Mississippi Sound.

Harper, G.G.; Manley, F.H.; Staheli, A.C.

1983-03-01

204

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

USGS Publications Warehouse

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

Crowley, J.K.; Vergo, N.

1988-01-01

205

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

PubMed

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

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

2012-01-01

206

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

PubMed Central

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

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

2012-01-01

207

Stability of guanine adsorbed in a clay mineral under gamma irradiation at temperatures (77 and 298 K): Implications for chemical evolution studies  

NASA Astrophysics Data System (ADS)

Chemical evolution is a physical and chemical preamble prior the appearance of life. In these processes, clay minerals might have played an important role on the early Earth. The relevance of these solids in the emergence of life is due to their ancient origin, wide distribution, and especially, their physico-chemical properties. Clays, therefore, are considered the most likely inorganic materials to promote organic reactions in the primitive Earth. John D. Bernal suggested clays as concentrators of biological precursor molecules, as catalysis and clays might protect these molecules from high-energy radiation. On the other hand, nucleic acid bases and their derivatives are important compounds in biological systems. Their synthesis and stability in environmental conditions are of paramount importance in chemical evolution. The aim of this work is to extend the knowledge of the role of clays in the prebiotic epoch in relation to the behavior of guanine, a nucleic acid base, adsorbed in a clay mineral. To this end, we studied its adsorption in clays, its site of binding, and its survival under a high radiation field and at different temperatures and pH. The results showed guanine adsorption onto clays increased with the decreasing of the pH. This result could be explained by electrostatic forces between guanine positively charged at an acid pH and the negatively charged interlamellar channel of the clay. X-ray diffractograms showed that guanine is adsorbed onto the clay at the interlayer channel. To study the survival of guanine in a high radiation field, the system guanine-clay was irradiated under different irradiation doses, temperatures, and pH. The results showed that more than 90% of the guanine survives, and when the radiolysis is made without clay, the decomposition of this molecule occurs at low irradiation doses. The radiolysis performed at 77 K showed very low decomposition, which is important in cometary chemistry. These results show the protection role of the clay toward ionizing radiation of an organic compound adsorbed into it.

Meléndez-López, A. L.; Ramos-Bernal, S.; Ramírez-Vázquez, M. L.

2014-07-01

208

Clay mineralogy and its effect on physical properties in the Gulf of Mexico northwestern continental slope  

E-print Network

was the most abundant mineral in sediments of the current (stage 1) and last interglacial maxima (stage 5) while illite dominates the clay min-eralogy of sediments from the last glacial maximum (stage 2). Relationships between clay mineralogy and physical...

Berti, Debora

2005-02-17

209

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

PubMed

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

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

210

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

PubMed

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

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

2013-01-01

211

Experimental Determination of Clay Mineral Reactions in Clastic Reservoir Rock Resulting from the Injection of Supercritical CO2  

NASA Astrophysics Data System (ADS)

The Cretaceous Frontier Formation of the Powder River Basin, WY has been considered as a potential reservoir for storing anthropogenic CO2. The reservoir zones are composed of fine-grained quartz and potassium feldspar rich sandstones, cemented with clay minerals (kaolinite and interlayered illite and montmorillonite). The purpose of these experiments is to determine whether susceptible minerals such as illite, montmorillonite, and potassium feldspar undergo in-situ 'weathering' reactions when exposed to the high concentrations of carbonic acid generated by the dissolution of supercritical CO2 in formation water. The transformation of these minerals has the potential to: 1.) open up pore space through dissolution; 2.) reduce pore space and/or close pore throats by precipitating new minerals, or 3.) cause little change if the reactions take place slowly. Core samples of the Frontier Formation were obtained from the USGS Core Repository in Denver, CO and their physical and mineralogical properties analyzed. Porosity and permeability of the cores have been determined by helium porosimetry and gas permeability testing. Pore space distribution was analyzed by CT scan. Mineralogy was determined by thin section analysis, X-Ray diffraction, and Scanning Electron Microscopy. Ongoing experiments will expose the cores to CO2 saturated brine in a flow-through reactor at conditions similar to those found in the subsurface (100oC and 15MPa). Changes to the chemical composition of the brine will be determined by withdrawing samples at regular intervals during the experiment and analyzing their contents with ion chromatography and colorimetry. The physical and mineralogical properties of the cores will be analyzed after each experiment and compared to the initial conditions. We will report on the results of these experiments.

Mangini, S. A.; Shaw, C. A.; Skidmore, M. L.

2013-12-01

212

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

NASA Technical Reports Server (NTRS)

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.

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

1991-01-01

213

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

PubMed

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

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

2014-09-25

214

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

NASA Astrophysics Data System (ADS)

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 dehydration easily occurs, is more appropriate condition to form and condense oligomer of amino acids than the seafloor surface. Moreover, clay minerals, as catalyst of peptide formation, must be an essential factors to proceed the chemical evolution of precursor life on the primitive earth.

Fuchida, S.; Masuda, H.

2012-12-01

215

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

SciTech Connect

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

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

2009-06-20

216

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

PubMed

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 d, but LW failed to affect numbers of live concepti at d 10 (P > .5) or numbers of offspring at parturition (P > .10). Banamine did not alleviate LW toxicosis of dams (P > .10). Provision of Silent Herder or bentonite in the diet or Banamine i.m. had no benefit for rats fed toxic locoweed. PMID:9222844

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

1997-07-01

217

Improvements in proteomic metrics of low abundance proteins through proteome equalization using ProteoMiner prior to MudPIT  

PubMed Central

Ideally shotgun proteomics would facilitate the identification of an entire proteome with 100% protein sequence coverage. In reality, the large dynamic range and complexity of cellular proteomes results in oversampling of abundant proteins, while peptides from low abundance proteins are undersampled or remain undetected. We tested the proteome equalization technology, ProteoMiner, in conjunction with Multidimensional Protein Identification Technology (MudPIT) to determine how the equalization of protein dynamic range could improve shotgun proteomics methods for the analysis of cellular proteomes. Our results suggest low abundance protein identifications were improved by two mechanisms: (1) depletion of high abundance proteins freed ion trap sampling space usually occupied by high abundance peptides and (2) enrichment of low abundance proteins increased the probability of sampling their corresponding more abundant peptides. Both mechanisms also contributed to dramatic increases in the quantity of peptides identified and the quality of MS/MS spectra acquired due to increases in precursor intensity of peptides from low abundance proteins. From our large data set of identified proteins, we categorized the dominant physicochemical factors which facilitate proteome equalization with a hexapeptide library. These results illustrate that equalization of the dynamic range of the cellular proteome is a promising methodology to improve low abundance protein identification confidence, reproducibility, and sequence coverage in shotgun proteomics experiments, opening a new avenue of research for improving proteome coverage. PMID:21702434

Fonslow, Bryan R.; Carvalho, Paulo C.; Academia, Katrina; Freeby, Steve; Xu, Tao; Nakorchevsky, Aleksey; Paulus, Aran; Yates, John R.

2011-01-01

218

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

PubMed

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. PMID:25027303

Ghadiri, M; Chrzanowski, W; Rohanizadeh, R

2014-11-01

219

Europium retention onto clay minerals from 25 to 150 °C: Experimental measurements, spectroscopic features and sorption modelling  

NASA Astrophysics Data System (ADS)

The sorption of Eu(III) onto kaolinite and montmorillonite was investigated up to 150 °C. The clays were purified samples, saturated with Na in the case of montmorillonite. Batch experiments were conducted at 25, 40, 80 and 150 °C in 0.5 M NaClO 4 solutions to measure the distribution coefficients (Kd) of Eu as a trace element (<10 -6 mol/L) between the solution and kaolinite. For the Na-montmorillonite, we used Kd results from a previous study [Tertre, E., Berger, G., Castet, S., Loubet, M., Giffaut, E., 2005. Experimental study of adsorption of Ni 2+, Cs + and Ln 3+ onto Na-montmorillonite up to 150 °C. Geochim. Cosmochim. Acta69, 4937-4948] obtained under exactly the same conditions. The number and nature of the Eu species sorbed onto both clay minerals were investigated by time resolved laser fluorescence spectroscopy (TRLFS) in specific experiments in the same temperature range. We identified a unique inner-sphere complex linked to the aluminol sites in both clays, assumed to be dbnd AlOEu 2+ at the edge of the particles, and a second exchangeable outer-sphere complex for montmorillonite, probably in an interlayer position. The Kd values were used to adjust the parameters of a surface complexation model (DLM: diffuse layer model) from 25 to 150 °C. The number of Eu complexes and the stoichiometry of reactions were constrained by TRLFS. The acidity constants of the amphoteric aluminol sites were taken from another study [Tertre, E., Castet, S., Berger, G., Loubet, M., Giffaut, E. Acid/base surface chemistry of kaolinite and Na-montmorillonite at 25 and 60 °C: experimental study and modelling. Geochim. Cosmochim. Acta, in press], which integrates the influence of the negative structural charge of clays on the acid/base properties of edge sites as a function of temperature and ionic strength. The results of the modelling show that the observed shift of the sorption edge towards low pH with increasing temperature results solely from the contribution of the dbnd AlOEu 2+ edge complexes. Finally, we successfully tested the performance of our model by confronting the predictions with experimental Kd data. We used our own data obtained at lower ionic strength (previous study) or higher suspension density and higher starting concentration (TRLFS runs, this study), as well as published data from other experimental studies [Bradbury, M.H., Baeyens, B., 2002. Sorption of Eu on Na and Ca-montmorillonite: experimental investigations and modeling with cation exchange and surface complexation. Geochim. Cosmochim. Acta66, 2325-2334; Kowal-Fouchard, A., 2002. Etude des mécanismes de rétention des ions U(IV) et Eu(III) sur les argiles: influence des silicates. Ph.D. Thesis, Université Paris Sud, France, 330p].

Tertre, E.; Berger, G.; Simoni, E.; Castet, S.; Giffaut, E.; Loubet, M.; Catalette, H.

2006-09-01

220

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

PubMed

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 starting point of an experiment favor the dissolution of aluminum, dissolved Al may remain in the experimental system and interact with the target surfaces. The systems are then no longer pristine and points of zero charge or sorption data are those of aluminum-bearing systems. PMID:25045321

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

2014-01-01

221

Provenance and depositional environments of the late Neogene Red Clay deposits in Northern China based on detrital zircon and heavy mineral analysis  

NASA Astrophysics Data System (ADS)

The late Miocene - Pliocene (about 11-2.5 Ma) time is the latest period of undisturbed global warmth before the onset of glacial times. Pliocene climate state is proposed as almost an analogue for future global climate by the end of 21st century and has been focus of much research. The Neogene red earth underlying the Pleistocene loess - paleosol deposits in northern China, has been demonstrated to have a relatively continuous depositional character at least over the past ~7-8 to ~2.6Ma. These Red Clay deposits are not only important continental archives of late Miocene-Pliocene environmental and climatic changes, but also preserve significant information on past atmospheric circulation patterns. Multiple competing hypotheses have been proposed for the provenance of Red Clay deposits of the Chinese Loess Plateau (CLP), yet none has been confirmed. Whether it is sediments derived from single or multiple source areas still remains ambiguous. U-Pb age dating of detrital zircons from clastic sediments has proved to be powerful tool to trace sediment sources. However, this method is seldom applied in constraining the provenance of Red Clay deposits. In this study, we selected three typical Red Clay sections across the northern China. They are Dongwan in the western part, Lantian in the southern part and Baode in the northeastern part of the CLP. Based on the systematic field geologic survey, stratigraphic investigation and magnetostratigraphy, 15 samples in different stratigraphic levels were chosen. By applying the zircon U-Pb dating and single grain zircon morphology, combined with heavy mineral analysis of the Red Clay samples, the research aims to investigate the source and spatio-temporal evolution of Neogene Red Clay deposits of northern China. This study has significant implications for understanding the Red Clay depositional environments and will give insight into the past wind systems responsible for transporting dust onto the Chinese Loess Plateau.

Shang, Yuan; Kaakinen, Anu; Beets, Christiaan J.; Prins, Maarten A.

2014-05-01

222

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

SciTech Connect

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.

Alexandrov, Vitali Y.; Rosso, Kevin M.

2013-10-02

223

Origin and diagenesis of clay minerals in relation to sandstone paragenesis: An example in eolian dune reservoirs and associated rocks, Permian upper part of the Minnelusa Formation, Powder River basin, Wyoming  

SciTech Connect

Eolian dune sandstones are the principal reservoir rocks in the Permian upper part of the Minnelusa Formation, Powder River basin, Wyoming. These sandstones formed as shorelines retreated and dunes migrated across siliciclastic sabkhas. Sandstones are mainly quartzarenites; on average, clay minerals constitute about 5 wt.% the whole rock. Although present in minor amounts, clay minerals play an important role in the diagenetic evolution of these sandstones. Allogenic clay minerals are present in shaly rock fragments and laminae. Early infiltration of clays into porous sabkha sands commonly form characteristic menisei or bridges between framework grains or, when more extensive, form coatings or rims on grain surfaces. Authigenic clays include nearly pure smectite, mixed-layer illite/smectite (I/S), and late diagenetic illite and corrensite; these clay minerals are present as pore-lining cements. In addition to the deposition and neoformation of clay minerals throughout sandstone paragenesis, the conversion of smectite to illite occurred as temperatures increased with progressive burial. A temperature of 103C is calculated at a present depth of 3,200 m using a geothermal gradient of 30C/km and a mean annual surface temperature of 7C. After correction for uplift and erosion (250 m), the maximum calculated temperature for the conversion of all random I/S to ordered I/S is 100C. This calculated temperature is in excellent agreement with temperatures of 100-110C implied from I/S geothermometry.

Pollastro, R.M.; Schenk, C.J. (Geological Survey, Denver, CO (United States))

1991-06-01

224

Instability in Soft Sensitive Clays  

Microsoft Academic Search

Soft sensitive clays like quick clays are well known in Scandinavia and in some regions in Canada. The salt pore water of these marine clays has been leached out since last glaciations and left a brittle mineral structure. Slides in quick clays can be extremely disastrous, as in Verdal, Norway in 1893 or Rissa in 1978. The slides may be

V. Thakur; G. Grimstad; S. Nordal

2006-01-01

225

Characterization of clay from northern of Morocco for their industrial application  

NASA Astrophysics Data System (ADS)

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.

El Ouahabi, Meriam; Fagel, Nathalie

2010-05-01

226

How clays weaken faults.  

NASA Astrophysics Data System (ADS)

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

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

2010-05-01

227

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

SciTech Connect

{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 also resulted in the decreased extent of Tc(IV) reoxidation. The results were attributed to the effect of NAu-2 aggregation that effectively retained Tc(IV) in the solid and decreased its vulnerability to reoxidation. Overall, our results implied that bioreduced clay minerals could play an important role in reducing Tc(VII) and in maintaining the long-term stability of reduced Tc(IV).

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

2009-01-01

228

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

PubMed

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

Schaumberger, Simone; Ladinig, Andrea; Reisinger, Nicole; Ritzmann, Mathias; Schatzmayr, Gerd

2014-01-01

229

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

PubMed Central

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

2014-01-01

230

Fluid-rock interaction controlling clay-mineral crystallization in quartz-rich rocks and its influence on the seismicity of the Carboneras fault area (SE Spain)  

NASA Astrophysics Data System (ADS)

The Carboneras Fault zone is one of the longest fault in the Betic Cordillera (SE Spain) and it would be a good candidate to generate large magnitude earthquakes (Gracia et al., 2006). Seismicity in the region is characterised by low to moderate magnitude events, although large destructive earthquakes have occurred, which reveals significant earthquake and tsunami hazards (Masana et al., 2004). Due to the internal architecture of the fault zone, shear lenses of post-orogenic sediments of Miocene and Pliocene age including marls and sandstones sequences are juxtaposed to the predominant slaty gouges of the Alpine basement. Microcataclasites and gouges of the quartz-rich post-orogenic sediments are also developed as cm- to m-scale bands, allowing the comparison between the deformed materials and their protoliths. Red, yellow and white sandstones and their respective cataclasites can be identified. This communication is concerned with the clay mineral crystallization events in these materials and its possible influence on the seismicity model of the region. The presence of phyllosilicates in fault zones as either neoformed or inherited clays is commonly related with fluid circulation and a mechanically weak fault behaviour (e.g., Wang, 1984). A critical factor for the understanding of the mechanical role of clays in fault rocks is to determine the timing of formation of mineral assemblages and microstructure of fault rocks and protolith. The effects of post-faulting alteration limit inferences about fault behaviour that can be made from exhumed rocks. The Carboneras fault zone provides good opportunities to study mineral processes enhanced by deformation, given that it is located in a region of arid climate and shows outcroppings of quartzitic rocks included in slaty rocks. Combined XRD, optical microscopy and SEM analyses reveal that deformed quartzitic rocks are enriched in phyllosilicates, increasing especially the amount of chlorite. The samples strongly damaged are characterised also by the presence of dolomite and gypsum. The deformation is highly localized, developing phyllosilicate-rich bands highly foliated due to the presence of fine-sized aligned clays (chlorite and mica). In some undeformed lenses of the cataclastic rocks, variable-sized patches of phyllosilicates containing random oriented stacks of chlorite and mica are developed. BSE images reveal that the stacks are made of two intergrown compositional types of chlorite. These results lead to conclude that limited clay growth during faulting occurred. The absence of significant compositional differences between undeformed and deformed phyllosilicates suggests that whereas fluids were present during strike-slip faulting, fluids were not preferentially focused along the quartz-rich rocks of the fault zone by phyllosilicates avoiding the development of the synkinematic clay alteration process. However, clays played an important role for the mechanical behaviour of the quartzitic rocks in the fault zone. Deformation is highly localized in chlorite-rich sandstones. These sandstones show substantial clay crystallization which texture can be related with a hydrothermal origin before strike-slip faulting, likely associated with the volcanic activity of the area leading to form of chlorite/mica patches. These data indicate that, although elevated fluid pressure confined by clay fabric cannot be appealed for the mechanical behaviour of the sandstones of the Carboneras fault, clay fabrics developed during deformation dominated the fault-weakening mechanism. We consider that lubricating properties of phyllosilicates in the quartzitic rocks were an important factor controlling movement mechanisms promoting the predominance of creep as regards seismic stick-slip (Bedrosian et al., 2004) reducing the possibility of larger seismogenic events that nucleate on localized fault planes developed within quartzitic rocks contained within the fault zone. Finally the crystallization of dolomite and gypsum in the highly damaged areas of the microcataclasites could be related with rec

Jimenez-Espinosa, R.; Abad, I.; Jimenez-Millan, J.; Lorite-Herrera, M.

2009-04-01

231

Distribution of clay minerals in surface sediments from the eastern Barents and south-western Kara seas  

Microsoft Academic Search

Surface samples from the eastern Barents and south-western Kara seas have been analysed for clay mineralogy. Transport paths, the role of regional sources and local bedrock outcrops and the influence of hydrodynamic and glacigenous processes for clay distribution on the shelves are discussed in relation to central Arctic Ocean deep sea and sea ice sediments. Franz Josef Land and Novaya

D. Nürnberg; M. A. Levitan; J. A. Pavlidis; E. S. Shelekhova

1995-01-01

232

Clay mineral assemblages of terrestrial records (Xining Basin, China) during the Eocene-Oligocene climate Transition (EOT) and its environmental implications  

NASA Astrophysics Data System (ADS)

The Eocene-Oligocene Transition (EOT) between ~34.0 and 33.5 million years ago, where global climate cooled from 'greenhouse' to 'icehouse' at ~33.5 Ma ago, is one of the great events during Cenozoic climate deterioration. In contrast to the marine records of the EOT, significantly less research has focused on the continental climate change during this time, particularly in inner Asia. We present a comprehensive study of the upper Eocene to lower Oligocene succession with regular alternations of laterally continuous gypsum/gypsiferous layers and red mudstone beds in Tashan section of Xining Basin, which is located at the northeastern margin of the Tibetan Plateau. Clay minerals, which were extracted from this succession, were analyzed qualitatively and semi-quantitatively by using X-ray differaction (XRD). Base on detailed magnetostratigraphic time control, clay mineral compositions of this succession (33.1-35.5 Ma) are compared with open ocean marine records and Northern Hemisphere continental records to understand the process and characteristics of Asian climate change before, during and after EOT. Our results indicate that illite is the dominant clay mineral with less chlorite and variable smectite. Multi-parameter evidence suggests that the source areas of detrital inputs in Tashan have not changed and climate is the main control for the composition of the clay fraction. The characteristics of clay mineral concentrations suggest warm and humid fluctuations with cold and dry conditions and intense of seasonality during ~35.5-34.0 Ma in inner Asian. This changed to cold and dry condition at ~34 Ma and remained so from ~34-33.1 Ma. The comparisons between continental and marine records indicate that the climate changes experienced in the Xining basin region are more consistent with Northern Hemisphere rather than open oceans records. This indicates that paleoclimate changes for inner Asian before, during and after EOT was not controlled by Antarctic ice growth, but may be due to atmospheric cooling linked to the existence and expansion of Northern Hemisphere glaciation.

Zhang, C.; Guo, Z.

2013-12-01

233

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

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. PMID:24275986

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

2014-07-01

234

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)

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.

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

2014-02-01

235

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)

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.

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

1989-03-01

236

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

NASA Astrophysics Data System (ADS)

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

Terajima, Tomomi; Moriizumi, Mihoko; Nakamura, Tomohiro

2010-05-01

237

Introduction Clays and health: An introduction  

E-print Network

of clay minerals in pharmacy and cosmetics indicating the broad variety of these materials as active and safety specifica- tions of clays to be used as pharmaceutical and cosmetic products by López-Galindo et and Summa (2007-this issue): Element mobility in clays for healing use. Examples of beneficial clay mineral­organic

Ahmad, Sajjad

238

Stepwise effects of the BCR sequential chemical extraction procedure on dissolution and metal release from common ferromagnesian clay minerals: a combined solution chemistry and X-ray powder diffraction study.  

PubMed

Sequential extraction procedures (SEPs) are commonly used to determine speciation of trace metals in soils and sediments. However, the non-selectivity of reagents for targeted phases has remained a lingering concern. Furthermore, potentially reactive phases such as phyllosilicate clay minerals often contain trace metals in structural sites, and their reactivity has not been quantified. Accordingly, the objective of this study is to analyze the behavior of trace metal-bearing clay minerals exposed to the revised BCR 3-step plus aqua regia SEP. Mineral quantification based on stoichiometric analysis and quantitative powder X-ray diffraction (XRD) documents progressive dissolution of chlorite (CCa-2 ripidolite) and two varieties of smectite (SapCa-2 saponite and SWa-1 nontronite) during steps 1-3 of the BCR procedure. In total, 8 (+/-1) % of ripidolite, 19 (+/-1) % of saponite, and 19 (+/-3) % of nontronite (% mineral mass) dissolved during extractions assumed by many researchers to release trace metals from exchange sites, carbonates, hydroxides, sulfides and organic matter. For all three reference clays, release of Ni into solution is correlated with clay dissolution. Hydrolysis of relatively weak Mg-O bonds (362 kJ/mol) during all stages, reduction of Fe(III) during hydroxylamine hydrochloride extraction and oxidation of Fe(II) during hydrogen peroxide extraction are the main reasons for clay mineral dissolution. These findings underscore the need for precise mineral quantification when using SEPs to understand the origin/partitioning of trace metals with solid phases. PMID:18951614

Ryan, P C; Hillier, S; Wall, A J

2008-12-15

239

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

NASA Astrophysics Data System (ADS)

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

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

2010-01-01

240

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)

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 ?m 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 is not systematic in clay-type material. The finest grain sizes (e.g., < 0.2 ?m) are usually least contaminated with detrital components and can be dated by the K-Ar method without special preparation. Alternatively, such fine fractions are most susceptible to 39Ar recoil, and are, therefore, only datable by the 40Ar/39Ar method using an encapsulation technique that still needs to be technically evaluated. In this study, 39Ar recoil during irradiation was quantified by encapsulation; it ranged from about 20% of the total 39Ar for the < 0.2 ?m fractions to ca. 10% for the 2-6 ?m fractions. Basic interpolation of this 39Ar recoil confirms that grain size increasing minimizes the recoil effect, but how it proceeds has still to be explained. Despite recent developments in 40Ar/39Ar dating, the conventional K-Ar method is still a valuable tool for clay dating due to a convenient and straightforward use supported by a standardized and well-controlled technical approach. The present comparison of the two Ar-dating methods as applied to clay material shows that neither method is presently outdated, and that they are even of reciprocal use. Both methods have distinct application fields in clay geochronology and complementary application fields in clay crystallography.

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

2012-10-01

241

Mechanisms of Sedimentation Inferred from Quantitative Characteristics of Heavy and Light Minerals Sorting and Abundance  

E-print Network

. This was because particles moved in a cluster-like motion. Terminal settling velocities of both particles converged at C_(v )? 25%, and particle sorting was diminished. Spatial and size distributions of mineral grains with contrasting densities in massive...

Motanated, Kannipa

2014-07-16

242

Evolution of clay mineral assemblages in the Tinguiririca geothermal field, Andean Cordillera of central Chile: an XRD and HRTEM-AEM study  

NASA Astrophysics Data System (ADS)

HRTEM textural evidence shows that clay minerals in the Tinguiririca geothermal field (Andean Cordillera, central Chile) are the result of direct alteration of former volcanic glass and minerals by hydrothermal fluids at similar temperatures to the present day. They show the classical pattern of diagenetic transformation from smectite at the top to illite at the bottom, with the progressive formation of corrensite and chlorite. The high fluid/rock ratio, disposability of necessary cations and absence of previous detrital phyllosilicates allow the consideration of this area as a natural laboratory to establish the extreme ideal conditions for very low-T reactions. Transformations from smectite to R1 illite-smectite (I-S) and from these to R3 mixed-layers occur respectively at 80-120 °C and 125-180 °C. In spite of ideal genetic conditions, the new-formed minerals show all the defective character and lack of textural and chemical equilibrium previously described in the literature for diagenetic and hydrothermal low-temperature assemblages. Chemistry of smectite-illite phases evolves basically through a diminution of the pyrophyllitic component toward a theoretical muscovite (Si4 + + ? -> Al3 ++ K+). However, a second chemical vector (Si4 ++ Mg2 + ? Al3 ++ Al3 +), that is, decreasing of the tschermack component, also contributes to the evolution toward the less Si-more Al rich muscovite in relation to the original smectite. Residual Mg (and Fe) from the latter reaction is consumed in the genesis of chloritic phases. Nevertheless, as a consequence of the lack of chemical equilibrium (probably because of the short time-scale of the geothermal alteration processes), the composition of clay minerals is highly heterogeneous at the level of a single sample. Consequently, the respective fields of smectite, R1 I-S and R3 I-S overlap each other, making the distinction among these three phases impossible based exclusively on chemical data.

Vázquez, M.; Nieto, F.; Morata, D.; Droguett, B.; Carrillo-Rosua, F. J.; Morales, S.

2014-08-01

243

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

NASA Astrophysics Data System (ADS)

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.

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

244

Discoloration and mineralization of Orange II by using a bentonite clay-based Fe nanocomposite film as a heterogeneous photo-Fenton catalyst.  

PubMed

Discoloration and mineralization of an azo dye Orange II was conducted by using a bentonite clay-based Fe nanocomposite (Fe-B) film as a heterogeneous photo-Fenton catalyst in the presence of UVC light and H(2)O(2). Under optimal conditions (pH=3.0, 10 mM H(2)O(2), and 1 x 8W UVC), 100% discoloration and 50-60% TOC removal of 0.2 mM Orange II can be achieved in 90 and 120 min, respectively. The mineralization kinetics of 0.2 mM Orange II is much slower than the corresponding discoloration kinetics. Under the same conditions, the Fe leaching from the Fe-B-coated catalyst film is very low. The Fe-B-coated catalyst film could be used in the pre-treatment of wastewater for an integrated system consisting of a photochemical reactor and a biological reactor. Multi-run experimental results reveal that the Fe-B-coated catalyst film could have a long-term stability for the discoloration and mineralization of Orange II. A comparison between the performance of the Fe-B-coated catalyst film and a suspended Fe-B catalyst in the discoloration and mineralization of Orange II was also discussed. PMID:15607168

Feng, Jiyun; Hu, Xijun; Yue, Po Lock

2005-01-01

245

Modeling near-infrared reflectance spectra of clay and sulfate mixtures and implications for Mars  

NASA Astrophysics Data System (ADS)

High-resolution mapping by visible and near-infrared orbital spectrometers has revealed a diversity of hydrated mineral deposits on the surface of Mars. Quantitative analysis of mineral abundances within these deposits has the potential to distinguish depositional and diagenetic processes. Such analysis can also provide important constraints on the nature of putative global and local-scale mineralogical transitions on Mars. However, the ability of models to extract quantitative mineral abundances from spectra of mixtures relevant to sedimentary rocks remains largely untested. This is particularly true for clay and sulfate minerals, which often occur as fine-grained components of terrestrial sedimentary rocks and are known to occur in a number of sedimentary deposits on Mars. This study examines the spectral properties of a suite of mixtures containing the Mg-sulfate epsomite mixed with varying proportions of smectitic clay (saponite, nontronite, and montmorrilonite). The goal of this work is to test the ability of checkerboard (linear) and intimate (non-linear) mixing models to obtain accurate estimates of mineral abundances under ideal and controlled laboratory conditions. The results of this work suggest that: (1) spectra of clay-sulfate mixtures can be reproduced by checkerboard and intimate mixing models to within 2% absolute reflectance or single scattering albedo, (2) clay and epsomite abundance can be modeled to within 5 wt.% when particle diameter is optimized, and (3) the lower threshold for modeling clay in spectra of clay-epsomite mixtures is approximately 10 wt.%, below which the models often fail to recognize the presence of clay.

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

2015-04-01

246

ABUNDANCE OF TRACE AND MINOR ELEMENTS IN ORGANIC AND MINERAL FRACTIONS OF COAL  

EPA Science Inventory

The report gives results of subjecting 27 U.S. coals to float/sink, acid, and ion-exchange treatments. From these treatments, coal fractions were obtained and analyzed to determine the organic and mineral associations of 45 elements. Of the elements studied, B, Be, Br, Ge, and Sb...

247

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

NASA Technical Reports Server (NTRS)

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.

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

1989-01-01

248

Abundance and diversity of total and nitrifying prokaryotes as influenced by biochemical quality of organic inputs combined with mineral nitrogen  

NASA Astrophysics Data System (ADS)

Ammonia-oxidizing bacteria and archaea (AOB, AOA) co-exist in soil, but they respond differently to distinct fertilization strategies in agricultural soils. Accordingly, effects of organic inputs and combination with mineral nitrogen (N) on AOB and AOA remain poorly understood. The aim of this study was to compare soil amendment with contrasting quality of organic inputs (i.e., high quality Tithonia diversifolia (TD; C/N ratio: 13, Lignin: 8.9 %; Polyphenols: 1.7 %), intermediate quality Calliandra calothyrsus (CC; 13; 13; 9.4) and low quality Zea mays (ZM; 59; 5.4; 1.2)), and combination with mineral N on the abundance (i.e., DNA-based gene quantification) and community structure (i.e., T-RFLP analysis) of total bacterial and archaea (16S rRNA gene), as well as AOB and AOA (targeting the amoA gene) communities in a Humic Nitisol. Soils (0-15 cm depth) were sampled prior to the onset of the rainy season in March 2012 in a 10 years old field experiment established in the central highlands of Kenya in 2002. Since the start of the experiment, organic inputs were applied annually at a rate of 4 Mg C ha-1 and mineral N twice a year as calcium ammonium nitrate (5Ca(NO3)2NH4NO3) at a rate of 120 kg N ha-1 growing season-1. Quality of organic inputs posed only a significant effect on the AOB community structure between TD versus ZM and CC versus ZM. Moreover, TD significantly increased the size of AOB over ZM input, while higher abundances for total bacteria, total archaea and AOA were measured in ZM and TD over CC. This was explained by high and available N in TD, but low lignin and polyphenol contents in TD and ZM as opposed to CC. AOB responded sensitively (i.e., complete community structure separation) to mineral N, specifically when combined with low quality ZM. Hence, AOB community was specifically responsive to quality of organic inputs and combination of low organic input with mineral N over AOA and total prokaryotic communities in the studied soil. The results presented were however, generated on one occasion soil sampling representing the effect of continuous organic and inorganic fertilizer application for ten years. We therefore recommend for prospective research, further investigations to rule out the temporal (short-term) variations of microbial decomposer dynamics at different crops growth stages during a cropping season as well as comparing different soil types.

Muema, Esther; Vanlauwe, Bernard; Röhl, Carolin; Cadisch, Georg; Rasche, Frank

2014-05-01

249

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

NASA Astrophysics Data System (ADS)

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

Roters, B.

2009-04-01

250

Optical constants using two particle size distributions: On-going laboratory efforts to quantitatively address clay abundance on Mars  

NASA Astrophysics Data System (ADS)

Data obtained at visible and near-infrared wavelengths by OMEGA on MarsExpress and CRISM on MRO provide definitive evidence for the presence of phyllosilicates and other hydrated phases on Mars. A diverse range of both Fe/Mg-OH and Al-OH-bearing phyllosilicates were identified including the smectites, nontronite, saponite, and montmorillonite. In order to constrain the abundances of these phyllosilicates spectral analyses of mixtures of pure end-members are needed. We report on the final stages of our on-going effort to enable the quantitative evaluation of the abundance of hydrated-hydroxylated silicates when they are contained in mixtures. We include several two component mixtures of hydrated/hydroxylated silicates with each other and with two analogs for other martian materials: pyroxene (enstatite) and palagonitic soil (an alteration product of basaltic glass). For the hydrated-hydroxylated silicates we include saponite and montmorillonite (Mg- and Al- rich smectites). We prepared three size separates of each end-member for study: 20-45, 63-90, and 125-150 ?m. We used scanning electron microscope images to characterize the grain size distribution, of each sample. Using the grain size distribution, we have derived initial estimates of the optical constants of these materials and compare them to values estimated for the same samples, but using the mean particle size of the sieve fraction. We discuss the results of our calculations for these materials and their implications for modeling the physical mixtures and eventual comparison to Martian spectra.

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

2013-12-01

251

Novel bentonite clay-based Fe-nanocomposite as a heterogeneous catalyst for photo-Fenton discoloration and mineralization of Orange II.  

PubMed

A novel bentonite clay-based Fe-nanocomposite (Fe-B) was successfully developed as a heterogeneous catalyst for photo-Fenton discoloration and mineralization of an azo-dye Orange II. X-ray diffraction (XRD) analysis clearly reveals that the Fe-B nanocomposite catalyst mainly consists of Fe2O3 (hematite) and SiO2 (quartz) crystallites, and the Fe concentration of the Fe-B catalyst determined by X-reflective fluorescence (XRF) is 31.8 wt %. The catalytic activity of the Fe-B was evaluated in the discoloration and mineralization of Orange II in the presence of H2O2 and UVC light (254 nm). It was found that the optimal Fe-B catalyst dosage is around 1.0 g/L, and the efficiency of discoloration and mineralization of Orange II increases as initial Orange II concentration decreases or reaction temperature increases. In addition, at optimal conditions (10 mM H2O2, 1.0 g of Fe-B/L, 1 x 8W UVC, and pH = 3.0), complete discoloration and mineralization of 0.2 mM Orange II can be achieved in less than 60 and 120 min, respectively. The result strongly indicates that the Fe-B nanocomposite catalyst exhibits a high catalytic activity not only in the photo-Fenton discoloration of Orange II but also in the mineralization of Orange II. The reaction kinetics analysis illustrates that the photo-Fenton discoloration of Orange II in the first 15 min obeys the pseudo-first-order kinetics. The reaction activation energy calculated was 9.94 kJ/mol, indicating that the photo-Fenton discoloration of Orange II is not very sensitive to reaction temperature. PMID:14740746

Feng, Jiyun; Hu, Xijun; Yue, Po Lock

2004-01-01

252

Use of DTA to determine the effect of mineralizers on the cement-quartz hydrothermal reactions. Part 2. Clay addition  

Microsoft Academic Search

The effect of adding up to 40% by weight of kaolinite and metakaolinite to cement-quartz mortars hydrothermally cured (autoclaved) at 175°C was investigated by DTA. It is evident that aluminium substitution in the CSH-I lattice takes place with the clay additions in a manner similar to that observed for gibbsite addition, as reported in the previous paper (Part 1, Thermochim.

A. Ray; E. R. Cantrill; M. G. Stevens; L. Aldridge

1995-01-01

253

Clay-based Nanocomposites Possibilities and Limitations  

NASA Astrophysics Data System (ADS)

In the last decades, clay mineral based nanocomposites and polymer-clay nanocomposites (PCNC) have been proposed as very useful materials for many uses including photocatalysis, medicinal uses as tissue engineering or modified drug delivery systems. Clay minerals and especially montmorillonite, kaolinite, halloysite palygorskite and sepiolite are the most used clay minerals because of their high surface areas, colloidal dimensions of their particles and other properties. This lecture aims at reporting on very recent developments in the use of clay minerals and PCNC as materials with photocatalytic and medical interest.

Papoulis, Dimitris

2011-09-01

254

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

NASA Astrophysics Data System (ADS)

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

Müller, Claudia; Stein, Ruediger

2000-08-01

255

Stepwise effects of the BCR sequential chemical extraction procedure on dissolution and metal release from common ferromagnesian clay minerals: A combined solution chemistry and X-ray powder diffraction study  

Microsoft Academic Search

Sequential extraction procedures (SEPs) are commonly used to determine speciation of trace metals in soils and sediments. However, the non-selectivity of reagents for targeted phases has remained a lingering concern. Furthermore, potentially reactive phases such as phyllosilicate clay minerals often contain trace metals in structural sites, and their reactivity has not been quantified. Accordingly, the objective of this study is

P. C. Ryan; S. Hillier; A. J. Wall

2008-01-01

256

Comparison of the sorption behaviors and mechanisms of perfluorosulfonates and perfluorocarboxylic acids on three kinds of clay minerals.  

PubMed

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

Zhao, Lixia; Bian, Jingna; Zhang, Yahui; Zhu, Lingyan; Liu, Zhengtao

2014-11-01

257

21 CFR 186.1256 - Clay (kaolin).  

Code of Federal Regulations, 2010 CFR

...alkalies and alkaline earths. Clay (kaolin) is a white to yellowish or grayish fine powder. There are at least three different minerals...classified as kaolin. Kaolinite or china clay is whiter, less contaminated with extraneous...

2010-04-01

258

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)

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.

Macklin, J. W.; White, D. H.

1985-01-01

259

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)

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.

Wang, H.; Liu, Z.; Colin, C.; Sathiamurthy, E.; Hantoro, W. S.; Zhao, Y.

2010-12-01

260

U, Th, Pb and REE abundances and Pb 207/Pb 206 ages of individual minerals in returned lunar material by ion microprobe mass analysis.  

NASA Technical Reports Server (NTRS)

Results of ion microprobe analyses of Apollo 11, 12 and 14 material, showing that U, Th, Pb and REE are concentrated in accessory minerals such as apatite, whitlockite, zircon, baddeleyite, zirkelite, and tranquillityite. Th/U ratios are found to vary by over a factor of 40 in these minerals. K, Ba, Rb and Sr have been localized in a K rich, U and Th poor glass phase that is commonly associated with the U and Th bearing accessory minerals. Li is observed to be fairly evenly distributed between the various accessory phases. The phosphates have been found to have REE abundance patterns (normalized to the chondrite abundances) that are fairly flat, while the Zr bearing minerals have patterns that rise steeply, by factors of ten or more, from La to Gd. All the accessory minerals have large negative Eu anomalies. Radiometric age dates (Pb 207/Pb 206) of the individual U and Th bearing minerals compare favorably with the Pb 207/Pb 206 age of the bulk rocks.

Andersen, C. A.; Hinthorne, J. R.

1972-01-01

261

Clays as prebiotic photocatalysts  

NASA Technical Reports Server (NTRS)

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

Coyne, L. M.; Lawless, J.; Lahav, N.; Sutton, S.; Sweeney, M.

1981-01-01

262

Influence of suspended clay minerals and humic matter on the solid phase extraction efficiency of selected pesticides from water.  

PubMed

The purpose of this investigation was to determine the influence of humic acids (HA) and Ca-montmorillonite (CaM) on the solid-phase extraction (SPE) efficiency of atrazine, alachlor and alpha-cypermethrin from water samples at various pH-values. The nature and intensity of binding of the studied pesticides to CaM were determined by X-ray diffraction analysis and termogravimetric analysis (TGA) test. The studied pesticides eluted from discs were analysed by thin-layer chromatography (TLC). The effects of CaM and humic acid were generally pH-dependent and acted independently in extraction efficiency influence. Lower recovery of pesticides was observed at higher pH values when CaM was > or =0.1 g and was attributed to greater dispersion of clay, increased surface area and subsequent adsorption. Concentrations of dissolved organic carbon (DOC) in humic acid had less effect on the extraction efficiency when water was at pH 8 compared to water at pH 2, which was probably due to greater nonpolar interactions of the pesticides to the charge-neutralized humic acid molecule. PMID:16923593

Mutavdzi?, Dragana; Brnardi?, Ivan; Kastelan-Macan, Marija

2006-01-01

263

Radiocesium sorption in relation to clay mineralogy of paddy soils in Fukushima, Japan.  

PubMed

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 = 36; Aizu, n = 36) in Fukushima Prefecture, Japan were investigated to clarify the mineralogical factors controlling the (137)Cs retention ability of soils (half-life 30.1 y). Of all the fission products released by the Fukushima accident, (137)Cs is the most important long-term contributor to the environmental contamination. The RIP, a quantitative index of the (137)Cs retention ability, was determined for the soil clays. The composition of clay minerals in the soil clays was estimated from peak areas obtained using X-ray diffraction (XRD) analyses. The predominant clay mineral was smectite in soils from Hama-dori and Aizu, while this was variable for those from Naka-dori. Native K content of the soil clays was found to be an indicator of the amount of micaceous minerals. The average RIP for the 97 soil clays was 7.8 mol kg(-1), and ranged from 2.4 mol kg(-1) to 19.4 mol kg(-1). The RIP was significantly and positively correlated with native K content for each of the geographical regions, Hama-dori (r = 0.76, p < 0.001), Naka-dori (r = 0.43, p < 0.05), and Aizu (r = 0.76, P < 0.001), while it was not related to the relative abundance of smectite. The linear relationship between RIP and native K content not only indicate a large contribution of micaceous minerals to the (137)Cs retention ability of the soil clays, but also could be used to predict the (137)Cs retention ability of soil clays for other paddy fields in Fukushima and other areas. PMID:24055668

Nakao, Atsushi; Ogasawara, Sho; Sano, Oki; Ito, Toyoaki; Yanai, Junta

2014-01-15

264

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

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.

Chiou, C.T.; Rutherford, D.W.; Manes, M.

1993-01-01

265

Clay Play  

ERIC Educational Resources Information Center

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

Rogers, Liz; Steffan, Dana

2009-01-01

266

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

SciTech Connect

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

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

2000-06-01

267

21 CFR 186.1256 - Clay (kaolin).  

Code of Federal Regulations, 2012 CFR

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

2012-04-01

268

21 CFR 186.1256 - Clay (kaolin).  

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

2014-04-01

269

21 CFR 186.1256 - Clay (kaolin).  

Code of Federal Regulations, 2013 CFR

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

2013-04-01

270

Mineralogy and instrumental neutron activation analysis of seven National Bureau of Standards and three Instituto de Pesquisas Tecnologicas clay reference samples  

USGS Publications Warehouse

The concentrations of 3 oxides and 29 elements in 7 National Bureau of Standards (NBS) and 3 Instituto de Pesquisas Techno16gicas (IPT) reference clay samples were etermined by instrumental neutron activation analysis. The analytical work was designed to test the homogeneity of constituents in three new NBS reference clays, NBS-97b, NBS-98b, and NBS-679. The analyses of variance of 276 sets of data for these three standards show that the constituents are distributed homogeneously among bottles of samples for 94 percent of the sets of data. Three of the reference samples (NBS-97, NBS-97a, and NBS-97b) are flint clays; four of the samples (NBS-98, NBS-98a, NBS-98b, and IPT-32) are plastic clays, and three of the samples (NBS-679, IPT-28, and IPT-42) are miscellaneous clays (both sedimentary and residual). Seven clays are predominantly kaolinite; the other three clays contain illite and kaolinite in the approximate ratio 3:2. Seven clays contain quartz as the major nonclay mineral. The mineralogy of the flint and plastic clays from Missouri (NBS-97a and NBS-98a) differs markedly from that of the flint and plastic clays from Pennsylvania (NBS-97, NBS-97b, NBS-98, and NBS-98b). The flint clay NBS-97 has higher average chromium, hafnium, lithium, and zirconium contents than its replacement, reference sample NBS-97b. The differences between the plastic clay NBS-98 and its replacement, NBS-98b, are not as pronounced. The trace element contents of the flint and plastic clays from Missouri, NBS-97a and NBS-98a, differ significantly from those of the clays from Pennsylvania, especially the average rare earth element (REE) contents. The trace element contents of clay sample IPT-32 differ from those of the other plastic clays. IPT-28 and IPT-42 have some average trace element contents that differ not only between these two samples but also from all the other clays. IPT-28 has the highest summation of the average REE contents of the 10 samples. The uranium content of NBS-98a, 46 parts per million, is very much higher than that of the other clays. Plots of average REE contents of the flint and plastic clays, normalized to chondritic abundances, show that the clays from Missouri differ from the same types of clay from Pennsylvania. The plot of REE contents for the miscellaneous clays shows that the normalized means for the elements lanthanum through samarium for IPT-28 are much greater than those for the other miscellaneous clays. The means for the elements europium through lutetium are similar for all three miscellaneous clays.

Hosterman, John W.; Flanagan, F.J.; Bragg, Anne; Doughten, M.W.; Filby, R.H.; Grimm, Catherine; Mee, J.S.; Potts, P.J.; Rogers, N.W.

1987-01-01

271

Fire clay  

USGS Publications Warehouse

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.

Virta, R.L.

2011-01-01

272

Clay Houses  

ERIC Educational Resources Information Center

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

Pedro, Cathy

2011-01-01

273

Abundances and distribution of minerals and elements in high-alumina coal fly ash from the Jungar Power Plant, Inner Mongolia, China  

USGS Publications Warehouse

The fly ash from the Jungar Power Plant, Inner Mongolia, China, is unique because it is highly enriched in alumina (Al2O3>50%). The fly ash mainly consists of amorphous glass and mullite and trace amounts of corundum, quartz, char, calcite, K-feldspar, clay minerals, and Fe-bearing minerals. The mullite content in fly ash is as high as 37.4% because of high boehmite and kaolinite contents in feed coal. Corundum is a characteristic mineral formed during the combustion of boehmite-rich coal.Samples from the economizer were sieved into six size fractions (<120, 120-160, 160-300, 300-360, 360-500, and >500 mesh) and separated into magnetic, mullite+corundum+quartz (MCQ) and glass phases for mineralogical and chemical analysis. The corundum content increases but amorphous glass decreases with decreasing particle size. Fractions of small particle sizes are relatively high in mullite, probably because mullite was formed from fine clay mineral particles under high-temperature combustion condition. Similarly, fine corundum crystals formed in the boiler from boehmite in feed coal. The magnetic phase consists of hematite, magnetite, magnesioferrite, and MgFeAlO4 crystals. The MCQ phase is composed of 89% mullite, 6.1% corundum, 4.5% quartz, and 0.5% K-feldspar.Overall, the fly ash from the power plant is significantly enriched in Al2O3 with an average of 51.9%, but poor in SiO2, Fe2O3, CaO, MgO, Na2O, P2O5, and As. Arsenic, TiO2, Th, Al2O3, Bi, La, Ga, Ni, and V are high in mullite, and the magnetic matter is enriched in Fe2O3, CaO, MnO, TiO2, Cs, Co, As, Cd, Ba, Ni, Sb, MgO, Zn, and V. The remaining elements are high in the glass fraction. The concentration of K2O, Na2O, P2O5, Nb, Cr, Ta, U, W, Rb, and Ni do not clearly vary with particle size, while SiO2 and Hg decrease and the remaining elements clearly increase with decreasing particle size. ?? 2009 Elsevier B.V.

Dai, S.; Zhao, L.; Peng, S.; Chou, C.-L.; Wang, X.; Zhang, Y.; Li, D.; Sun, Y.

2010-01-01

274

Fire clay  

USGS Publications Warehouse

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.

Virta, R.L.

2013-01-01

275

Investigating the Influence of Clay Mineralogy on Stream Bank Erodibility  

NASA Astrophysics Data System (ADS)

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 4.5. The ASTM pinhole test for identifying dispersive clay soils is being adapted to measure erodibility of intact and remolded sediment samples in the laboratory to look for more subtle differences in behavior under erosive conditions. Factors such as the extent and method of sample compaction are being taken into account in order to standardize the method.

Ambers, R. K.; Stine, M. B.

2005-12-01

276

Light-stable-isotope studies of spring and thermal waters from the Roosevelt Hot Springs and Cove Fort/Sulphurdale Thermal areas and of clay minerals from the Roosevelt Hot Springs thermal area  

SciTech Connect

The isotopic compositions of hydrogen and oxygen have been determined for spring waters and thermal fluids from the Roosevelt Hot Springs and Cove Fort-Sulphurdale thermal areas, for clay mineral separates from shallow alteration of the acid-sulfate type in the Roosevelt Hot Springs area, and for spring and well waters from the Goshen Valley area of central Utah. The water analyses in the Roosevelt Hot Springs thermal area confirm the origin of the thermal fluids from meteoric water in the Mineral Range. The water analyses in the Cove Fort-Sulphurdale thermal area restrict recharge areas for this system to the upper elevations of the Pavant and/or Tushar Ranges. The low /sup 18/O shift observed in these thermal fluids (+0.7 permil) implies either high water/rock ratios or incomplete isotope exchange or both, and further suggests minimal interaction between the thermal fluid and marble country rock in the system. Hydrogen and oxygen-isotope data for clay mineral separates from shallow alteration zones in the Roosevelt Hot Springs thermal system suggest that the fluids responsible for the shallow acid-sulfate alteration were in part derived from condensed steam produced by boiling of the deep reservoir fluid. The isotope evidence supports the chemical model proposed by Parry et al. (1980) for origin of the acid-sulfate alteration at Roosevelt Hot Springs. The isotope analyses of spring and well waters from the Goshen Valley area indicate only a general correlation of isotope composition, salinity and chemical temperatures.

Bowman, J.R.; Rohrs, D.T.

1981-10-01

277

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

NASA Astrophysics Data System (ADS)

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

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

2013-01-01

278

Fire clay  

USGS Publications Warehouse

In 2005, six companies mined fire clay in Missouri, Ohio and South Carolina. Production was estimate to be 300 kt with a value of $8.3 million. Missouri was the leading producer state followed by Ohio and South Carolina. For the third consecutive year, sales and use of fire clays have been relatively unchanged. For the next few years, sales of fire clay is forecasted to remain around 300 kt/a.

Virta, R.L.

2006-01-01

279

Trace element abundances and mineral\\/melt distribution coefficients in phonolites from the Laacher See volcano (Germany)  

Microsoft Academic Search

Twenty six whole rocks, seven matrix and fifty three mineral separates from the compositionally zoned late Quaternary Laacher See tephra sequence (East Eifel, W Germany) were analyzed by instrumental neutron activation. These data document the chemical variation within the Laacher See magma chamber prior to eruption with a highly fractionated phonolite at the top and a more mafic phonolite at

G. Wörrier; J.-M. Beusen; N. Duchateau; R. Gijbels; H.-U. Schmincke

1983-01-01

280

Smart Clays: SAFOD Samples Confirm the Key Role of Newly-formed Clays in Shallow Fault Zones  

NASA Astrophysics Data System (ADS)

Analysis of fault rocks from drill-cores of the San Andreas Fault Observatory at Depth (SAFOD) project in Parkfield (CA) confirm our original hypothesis that active clay growth can occur locally at shallow conditions and that such clay localization affect fault mechanics and fault creep in particular. SAFOD fault rocks contain a variety of newly formed clay minerals including smectite, illite-smectite and chlorite-smectite, as well as illite and chlorite. Brecciated host rock fragments are abundantly coated by polished and/or striated thin-films of hydrated clay minerals, creating an interconnected and pervasive network of displacement surfaces. Ar encapsulation dating of mixed-layer nanocoatings demonstrates recent crystallization and reveal an 'older' fault strand (~8 Ma) at 3066 m measured depth and a 'younger' fault strand (~4 Ma) at 3296 m measured depth. Today, the younger strand is the site of active creep behavior, demonstrating continued (re)activation of clay-weakened zones. Recent experimental work on aseismically creeping segments of SAFOD samples showed frictional strengths that are significantly weaker than neighboring wall rocks, offering independent validation of our model. Using a range of analytical methods that include X-ray diffraction, X-ray goniometry, elemental analysis and electron microscopy, we determined the location and nature of smectitic clay minerals in borehole samples, to assess the extent of smectitic phases in space and depth, any fault zone fabric development, and the swelling behavior of smectitic phases within the fault zone. Beyond the occurrence of illite-smectite in these relatively shallow fault rocks, the localized concentration of chlorite-smectite can extend the role of smectitic clays to depths down to ~10 km. We conclude that ultrathin hydrous clay films, or nanocoatings, on displacement surfaces play a key role in influencing weak fault and creep behavior along the San Andreas Fault at Parkfield, and likely in shallow faults systems elsewhere. These results indicate that scenarios involving talc/serpentine phases or locally enhanced fluid pressure as explanations for mechanically weak crustal faults are not required.

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

2013-12-01

281

Chemical disaggregation of kaolinitic claystones (tonsteins and flint clays)  

USGS Publications Warehouse

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.

Triplehorn, D.M.; Bohor, B.F.; Betterton, W.J.

2002-01-01

282

Sr-Nd isotope composition and clay mineral assemblages in eolian dust from the central Philippine Sea over the last 600 kyr: Implications for the transport mechanism of Asian dust  

NASA Astrophysics Data System (ADS)

transport to the tropical/subtropical northwestern Pacific over the past 600 kyr was investigated using radiogenic isotopes (87Sr/86Sr and ?Nd), together with the clay mineral composition, of eolian dust preserved in a sediment core obtained from the Philippine Sea (12°30'N, 134°60'E). These data revealed the influence of two prevailing dust sources, namely, the Asian deserts and nearby volcanic arcs (e.g., the Luzon Arc), with average contributions of around 70% and 30%, respectively, from each. The clay mineral composition of the core resembled dust from the central Asian deserts (CADs; e.g., the Taklimakan Desert) as in the north-central Pacific, but published aerosol data collected near the study site during winter/spring have the mineralogical signature of dust originating from the East Asian deserts (EADs). These data indicate that the relative contribution of EAD dust increases with the northeasterly surface winds associated with the East Asian Winter Monsoon (EAWM) during winter/spring, but the Prevailing Westerlies and Trade Winds that carry dust from the CADs is the dominant transport agent in the overall dust budget of the study site. The results of this study contradict the prevailing view that direct dust transport by the EAWM winds in spring dominates the annual flux of eolian dust in the northwest Pacific.

Seo, Inah; Lee, Yong Il; Yoo, Chan Min; Kim, Hyung Jeek; Hyeong, Kiseong

2014-10-01

283

PII S0016-7037(98)00136-7 The kinetics of mixed Ni-Al hydroxide formation on clay and aluminum oxide minerals  

E-print Network

PII S0016-7037(98)00136-7 The kinetics of mixed Ni-Al hydroxide formation on clay and aluminum. LAMBLE,3 and DONALD L. SPARKS 1 1 Department of Plant and Soil Sciences, University of Delaware, Newark investigations were combined with X-ray Absorption Fine Structure (XAFS) measurements to determine Ni sorption

Sparks, Donald L.

284

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

NASA Technical Reports Server (NTRS)

The Miniature Thermal Emission Spectrometer (Mini-TES) has provided remote measurements of mineralogy, thermophysical properties, and atmospheric temperature profile and composition of the outcrops, rocks, spherules, and soils surrounding the Spirit and Opportunity Rovers. The mineralogy of volcanic rocks provides insights into the composition of the source regions and the nature of martian igneous processes. Carbonates, sulfates, evaporites, and oxides provide information on the role of water in the surface evolution. Oxides, such as crystalline hematite, provide insight into aqueous weathering processes, as would the occurrence of clay minerals and other weathering products. Diurnal temperature measurements can be used to determine particle size and search for the effects of sub-surface layering, which in turn provide clues to the origin of surficial materials through rock disintegration, aeolian transport, atmospheric fallout, or induration. In addition to studying the surface properties, Mini-TES spectra have also been used to determine the temperature profile in the lower boundary layer, providing evidence for convective activity, and have determined the seasonal trends in atmospheric temperature and dust and cloud opacity.

Christensen, P. R.; Wyatt, M. B.; Glotch, T. D.; Rogers, A. D.; Anwar, S.; Arvidson, R. E.; Bandfield, J. L.; Blaney, D. L.; Budney, C.; Calvin, W. M.

2005-01-01

285

Fine-grained clay fraction (,0.2 {mu}m): An interesting tool to approach the present thermal and permeability state in active geothermal systems  

SciTech Connect

We have investigated by X-ray diffraction the very fine grained secondary minerals (< 0.2 {micro}m) developed in geothermal systems, in relation with their present thermal and permeability state. Because the smallest particles are the most reactive part of a rock, they are the youngest mineral phases of the geothermal fields. This study has been performed on two active geothermal fields: Milos field, Greece (130 < T < 320 C) and Chipilapa field, Salvador (90 < T < 215 C). In the Milos field, the mineralogical composition of the < 0.2 {micro}m clay fraction observed in the reservoir strongly differs from the overlying altered metamorphic schists in the presence of abundant quantities of saponite and talc/saponite interstratified minerals at unusually high temperature. These phases are considered to be kinetically control-led ''metastable'' minerals which rapidly evolve towards actinolite and talc for present temperatures higher than 300 C. Their occurrence is a good indicator of discharge in highly permeable zones. In the geothermal field of Chipilapa, the mineralogical composition of the < 0.2 {micro}m clay fractions fairly agrees with the temperatures presently measured in the wells, whereas several discrepancies may be pointed out from the compositions of coarser clay fractions (< 5 {micro}m) which contain minerals inherited from higher temperature stages. Permeable zones may be evidenced from an increase of expandable components in the interstratified minerals and a decrease of the coherent domain of the unexpandable clay particles (chlorite).

Patrier, P.; Papapanagiotou, P.; Beaufort, D.; Traineau, H.; Bril, H.

1992-01-01

286

The colloidal chemistry of ceramic clays  

NASA Technical Reports Server (NTRS)

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.

Phelps, G. W.

1984-01-01

287

Fire clay  

USGS Publications Warehouse

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.

Virta, R.L.

2012-01-01

288

Coating of silica sand with aluminosilicate clay.  

PubMed

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

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

2006-02-01

289

Trace element abundances and mineral/melt distribution coefficients in phonolites from the Laacher See volcano (Germany)  

NASA Astrophysics Data System (ADS)

Twenty six whole rocks, seven matrix and fifty three mineral separates from the compositionally zoned late Quaternary Laacher See tephra sequence (East Eifel, W Germany) were analyzed by instrumental neutron activation. These data document the chemical variation within the Laacher See magma chamber prior to eruption with a highly fractionated phonolite at the top and a more mafic phonolite at its base as derived from other data. Incompatible elements such as Zn, Zr, Nb, Hf, U, light and heavy rare earths are extremely enriched towards the top whereas compatible elements (e.g. Sr, Sc, Co, Eu) are strongly depleted. Semicompatible elements (Ta and some middle REE) are depleted at intermediate levels. This chemical variation is shown by whole rock and matrix data indicating the phonolite liquid was compositionally zoned regardless of phenocryst content. Hybrid rocks (phonolite-basanite) show the largest concentrations for compatible elements. All elements (except Rb) display continuous compositional variations with regard to the stratigraphic position of pumice samples. From these data we are able to distinguish three main units: An early erupted highly fractionated magma, the main volume of evolved phonolite and a mafic phonolite as the final products. The extreme variation of trace element distribution coef ficients (K) for 9 mineral phases with respect to stratigraphic position (resp. matrix composition) cannot be explained by conventional mechanisms. We postulate a significant modification of the trace element content of the phonolite melt by liquid-liquid controlled differentiation processes subsequent to and/or contemporaneous with (fractional) crystallization which caused disequilibrium between phenocrysts and host matrix. Therefore, our “distribution coefficients” deviate from equilibrium partition coefficients equivalent to the amount of this post crystallization modification of the matrix composition. The relationship between varying K and matrix composition is demonstrated by a ?K-?M-diagram (variation of K versus variation of matrix, M). Different parts of this diagram relate to different parameters ( T, P, polymerization, complex-building, equilibrium crystallization in a zoned magma column and post crystallization disequilibrium effects) which are responsible for the variation of distribution coefficients in general. The ?K-?M-diagram may allow to distinguish between different processes affecting the distribution coefficients measured in natural volcanic rocks from a differentiating magma system.

Wörrier, G.; Beusen, J.-M.; Duchateau, N.; Gijbels, R.; Schmincke, H.-U.

1983-11-01

290

UTILIZATION OF SOME CERAMIC INDUSTRIAL WASTES FOR MAKING CLAY-BUILDING BRICKS  

Microsoft Academic Search

The clay deposits at Kom Osheem area, Fayoum Governorate, Egypt, were previously investigated. These clays are silty to silty mud with a mineralogical composition of montmorillonite, montmorillonite - illite, kaolinite and illite clay minerals in addition to, quartz, feldspar and calcite as the non-clay minerals. Chemically, these clays contain low Al2O3, high SiO2 and low soluble salts. The ceramic properties

N. G. Abd El-Ghafour; H. S. Hassan; H. H. Assal

291

Sedimentary and Related Minerals  

NSDL National Science Digital Library

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

Perkins, Dexter

292

Characterizing regional soil mineral composition using spectroscopyand geostatistics  

USGS Publications Warehouse

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

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

2013-01-01

293

Clay at Nili Fossae  

NASA Technical Reports Server (NTRS)

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 at the upper right, the small mesa -- a flat-topped hill -- at the center of the image is a remnant of an overlying rock layer that was eroded away. The greenish clay areas at the base of the hill were exposed by erosion of the overlying rock. The images at the upper right and lower left both show that the reddish-toned olivine occurs as sand dunes on top of the greenish clay deposits. The image at the lower right shows details of the clay-rich rock, including that they are extensively fractured into small, polygonal blocks just a few meters in size. Taken together, the CRISM and HiRISE data show that the clay-rich rocks are the oldest at the site, that they are exposed where overlying rock has been eroded away, and that the olivine is not part of the clay-rich rock. Rather it occurs in sand dunes blowing across the clay.

Many more images of Nili Fossae and other clay-rich areas will be taken over the next two years. They will be used to try to understand the earliest climate of Mars that is recorded in the planet's rocks.

The Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) is one of six science instruments on NASA's Mars Reconnaissance Orbiter. Led by The Johns Hopkins University Applied Physics Laboratory, the CRISM team includes expertise from universities, government agencies and small businesses in the United States and abroad.

CRISM's mission: Find the spectral fingerprints of aqueous and hydrothermal deposits and map the geology, composition and stratigraphy of surface features. The instrument will also watch the seasonal variations in Martian dust and ice aerosols, and water content in surface materials o leading to new understanding of the climate.

NASA's Jet Propulsion Laboratory, a division of the Califonia Institute of Technology, Pasadena, manages the Mars Reconnaissance Orbiter for the NASA Science Mission Directorate, Washington. Lockheed Martin Space Systems, Denver, is the prime contractor and built the spacecraft.

2006-01-01

294

Searching for reciclability of modified clays for an environmental application  

NASA Astrophysics Data System (ADS)

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. 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. We have studied the adsorption of several contaminants related to the food industry by natural or modified clays, searching their interaction mechanisms and the possible recycling of these materials for environmental purposes and prevention of the health. We have used the FT-IR spectroscopy and DTA/TG studies to confirm the reciclability of these materials and the possible application in the industry to prevent the contamination. References -del Hoyo, C. (2007). Applied Clay Science. 36, 103-121.Layered Double Hydroxides and human health: An overview. -Valderrábano, M., Rodríguez-Cruz, S., del Hoyo, C., Sánchez-Martín, M.J. (2006). 4th International Workshop "Bioavalailability of pollutants and soil remediation". 1, 5-6. Physicochemical study of the adsorption of pesticides by lignins. -Volzone, C. (2007). Applied Clay Science. 36, 191-196. Retention of pollutant gases: Comparison between clay minerals and their modified products.

Del Hoyo Martínez, Carmen; Solange Lozano García, Marina; Sánchez Escribano, Vicente; Antequera, Jorge

2014-05-01

295

Clay for Little Fingers.  

ERIC Educational Resources Information Center

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

Koster, Joan Bouza

1999-01-01

296

Detailed mineral and chemical relations in two uranium-vanadium ores  

USGS Publications Warehouse

Channel samples from two mines on the Colorado Plateau have been studied in detail both mineralogically and chemically. A channel sample from the Mineral Joe No. 1 mine, Montrose County, Colo., extends from unmineralized rock on one side, through a zone of variable mineralization, into only weakly mineralized rock. The unmineralized rock is a fairly clean quartz sand cemented with gypsum and contains only minor amounts of clay minerals. One boundary between unmineralized and mineralized rock is quite sharo and is nearly at right angles to the bedding. Vanadium clay minerals, chiefly mixed layered mica-montmorillonite and chlorite-monmorillonite, are abundant throughout the mineralized zone. Except in the dark "eye" of the channel sample, the vanadium clay minerals are accompanied by hewettite, carnotite, tyuyamunite, and probably unidentified vanadates. In the dark "eye," paramontroseite, pyrite, and marcasite are abundant, and bordered on each side by a zone containing abundant corvusite. No recognizable uranium minerals were seen in the paramontroseite zone although uranium is abundant there. Coaly material is recognizable throughout all of the channel but is most abundant in and near the dark "eye." Detailed chemical studies show a general increase in Fe, Al, U, and V, and a decrease in SO4 toward the "eye" of the channel. Reducing capacity studies indicate that V(IV) and Fe(II) are present in the clay mineral throughout the channel, but only in and near the "eye" are other V(IV) minerals present (paramontroseite and corvusite). The uranium is sexivalent, although its state of combination is conjectural where it is associated with paramontroseite. Where the ore boundary is sharp, the boundary of introduced trace elements is equally sharp. Textural and chemical relations leave no doubt that the "eye: is a partially oxidized remnant of a former lower-valence ore, and the remainder of the channel is a much more fully oxidized remnant. A channel sample from the Virgin No. 3 mine, Montrose County, Colo., extends from weakly mineralized sandstone on both sides through a strongly mineralized central zone. The weakly mineralized zone is a poorly sorted sandstone with common detrital clay partings; chlorite and mixed layer mica-montmorrillonite are abundant interstitial to the quartz grains. No distinct vanadium or uranium minerals are recognizable, although the clay minerals are vanadium bearing. Euherdral pyrite grains and selenian galena are present but rare. The strongly mineralized rock is separated from the weakly mineralized rock by a narrow transition zone which only apporiximates the bedding planes. It contains abundant vanadium-bearing clay minerals (predominantly chlorite) interstitial to the quartz grains, and apparently replacing them. Paramontroseite is common and is intergrown with the clay minerals. Pyrite and marcasite are present, chiefly in or near the abundant blebs and fragments of carbonaceous material. Selenian galena is rarely present, and generally in or near carbonaceous material. Coffinite is the only uranium mineral idenitified; it is extremely fine grained and was identified only in X-ray diffraction patterns of heavy separates. Distribution of trace elements is not clear; some are consistently high in the strongly mineralized rocks, and some are consistently low. The trace element composition of the unmineralized rock is not known. Chemical studies show a very abrupt rise in the total U, V, and Fe from the weakly mineralized to strongly mineralized rock. Reducing-capacity studies indicate that most of the vanadium is present as V(IV), but some is present as V(V); that iron is present as both Fe(II) and Fe(III), the latter believed to have been present in the primary clays of the unmineralized rock; and that come of the uranium is present as U(VI) in addition to the U(IV) in the coffinite. All evidence points to weak oxidation of an ore once having a somewhat lower valence state. The channel samples from both the Mineral Joe No. 1 mine and the Virgin No. 3 mine are believe to have been essentially

Garrels, Robert M.; Larsen, E. S., III; Pommer, A.M.; Coleman, R.G.

1956-01-01

297

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

NASA Astrophysics Data System (ADS)

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

Sharma, Prasesh; Kappler, Andreas

2011-11-01

298

Fire clay  

USGS Publications Warehouse

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.

Virta, R.L.

2004-01-01

299

Clay Boats  

NSDL National Science Digital Library

Students use a small quantity of modeling clay to make boats that float in a tub of water. The object is to build boats that hold as much weight as possible without sinking. In the process of designing and testing their prototype creations, students discover some of the basic principles of boat design, gain first-hand experience with concepts such as buoyancy and density, and experience the steps of the engineering design process.

Engineering K-PhD Program,

300

Sorption of Cm(III) and Eu(III) onto clay minerals under saline conditions: Batch adsorption, laser-fluorescence spectroscopy and modeling  

NASA Astrophysics Data System (ADS)

The present work reports experimental data for trivalent metal cation (Cm/Eu) sorption onto illite (Illite du Puy) and montmorillonite (Na-SWy-2) in NaCl solutions up to 4.37 molal (m) in the absence of carbonate. Batch sorption experiments were carried out for a given ionic strength at fixed metal concentration (mEu = 2 × 10-7 m, labeled with 152Eu for ?-counting) and at a constant solid to liquid ratio (S:L = 2 g/L) for 3 < pHm < 12 (pHm = -log mH+). The amount of clay sorbed Eu approaches almost 100% (with log KD > 5) for pHm > 8, irrespective of the NaCl concentration. Variations in Eu uptake are minor at elevated NaCl concentrations. Time-resolved laser fluorescence spectroscopy (TRLFS) studies on Cm sorption covering a wide range of NaCl concentrations reveal nearly identical fluorescence emission spectra after peak deconvolution, i.e. no significant variation of Cm surface speciation with salinity. Beyond the three surface complexes already found in previous studies an additional inner-sphere surface species with a fluorescence peak maximum at higher wavelength (? ? 610 nm) could be resolved. This new surface species appears in the high pH range and is assumed to correspond to a clay/curium/silicate complex as already postulated in the literature for kaolinite. The 2 site protolysis non-electrostatic surface complexation and cation exchange sorption model (2SPNE SC/CE) was applied to describe Eu sorption data by involving the Pitzer and SIT (specific ion interaction) formalism in the calculation of the activities of dissolved aqueous species. Good agreement of model and experiment is achieved for sorption data at pHm < 6 without the need of adjusting surface complexation constants. For pHm > 6 in case of illite and pHm > 8 in case of montmorillonite calculated sorption data systematically fall below experimental data with increasing ionic strength. Under those conditions sorption is almost quantitative and deviations must be discussed considering uncertainties of measured Eu concentrations in the range of analytical detection limits.

Schnurr, Andreas; Marsac, Rémi; Rabung, Thomas; Lützenkirchen, Johannes; Geckeis, Horst

2015-02-01

301

Thermo Gravimetric and Differential Thermal Analysis of Clay of Western Rajasthan (india)  

NASA Astrophysics Data System (ADS)

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.

Shekhawat, M. S.

302

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

USGS Publications Warehouse

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

Whitney, G.; Northrop, H.R.

1987-01-01

303

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

NASA Astrophysics Data System (ADS)

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

Goodfellow, Bradley W.

2012-12-01

304

Mineral reactions and controls on zeolite facies alteration in sandstone of central Transantarctic Mountains, Antarctica  

SciTech Connect

Volcanic sandstones of the Fremouw and Falla formations contain abundant zeolite-facies authigenic minerals. Mineral and chemical patterns in Fremouw and Falla sandstone suggest that porosity and authigenic mineralogy were controlled by parent material composition, fluid chemistry, permeability, and temperature. Mineral patterns suggest simple rock-fluid reactions in which unstable volcanic rock fragments and plagioclase grains were altered to clay, heulandite, albite, laumontite, and/or prehnite. Chemical patterns suggest that significant mass transfer of Na+, Ca+2 and Si+4 occurred in the sandstone during alteration, whereas Al+3 mobility was restricted and was incorporated into clay and/or zeolite cements. These cements typically reduced primary porosity to a few percent; however, some secondary porosity was created by the dissolution of detrital plagioclase grains.

Vavra, C.L.

1983-03-01

305

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

NASA Astrophysics Data System (ADS)

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

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

2010-12-01

306

Microbial mediation of authigenic clays during hydrothermal alteration of basaltic tephra, Kilauea Volcano  

E-print Network

Microbial mediation of authigenic clays during hydrothermal alteration of basaltic tephra, Kilauea at Kilauea Volcano, Hawaii, contain subsurface bacteria characterized by small ( silica. For both the clays and silica, the microbial surfaces are clearly sites for mineral nucleation

Konhauser, Kurt

307

Method for dissolving clay  

Microsoft Academic Search

A method is described for dissolving clay which comprises contacting the clay alternately with separate slugs of a hydrogen ion-containing chemical and a fluoride ion-containing chemical. The hydrogen ions and fluoride ions react on the surface of the clay to produce hydrofluoric acid to dissolve the clay. The method is particularly valuable in dissolving the clay in a mixture of

Hall

1977-01-01

308

Formation of hydrocarbons from acid-Clay suspensions by gamma irradiation  

NASA Astrophysics Data System (ADS)

The adsorption of certain organic compounds by clays gives rise to the transformation of the adsorbate through the action of the clays. This phenomenon can be enhanced using ionizing radiation. In this context, these kinds of reactions play an important role in many natural and industrial processes. For example, in oil and gas exploration, the source and trap of petroleum hydrocarbons is frequently clay-rich rocks. Clay-water-based muds are also seen as environmentally friendly alternatives to toxic oil-based fluids. The principal processes that occur in sediments are usually held to be of bacterial action and thermal transformation, which may include thermally induced catalytic alteration of the organic debris. On the other hand, radioactive materials are widely distributed throughout Earth. They were more abundant in the past, but are present in petroleum reservoirs. Their presence induced radioactive bombardment, which may have altered these sediments. This important subject has not been extensively studied. The aim of this work is to study the behavior of fatty acids—like behenic acid—and dicarboxylic acids—like fumaric acid—as model compounds, which are adsorbed in a clay mineral (Na-montmorillonite) and exposed to gamma radiation. The results show that the radiation-induced decomposition of the clay-acid system goes along a definitive path (oxidation), rather than following several modes of simultaneous decomposition, as happens in radiolysis without clay or by heating the system. The main radiolytic products for fatty acids are their corresponding hydrocarbons, with one C-atom less than the original acid.

Cruz-Castañeda, J.; Negron-Mendoza, A.; Ramos-Bernal, S.

2013-07-01

309

Burnt clay magnetic properties and palaeointensity determination  

NASA Astrophysics Data System (ADS)

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 palaeointensity experiments for the samples formed from the ancient baked clays completely failed to give relibable results.

Avramova, Mariya; Lesigyarski, Deyan

2014-05-01

310

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...

311

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

Microsoft Academic Search

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

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

2001-01-01

312

Griffith Saponite as an Analog for Clay Minerals at Yellowknife Bay in Gale Crater, Mars: A Marker for Low-temperature Hydrothermal Processes  

NASA Technical Reports Server (NTRS)

The CheMin X-ray diffraction (XRD) instrument onboard the Mars Science Laboratory rover Curiosity in Gale Crater, Mars, discovered smectite in drill fines of the Sheepbed mudstone at Yellowknife Bay (YNB). The mudstone has a basaltic composition, and the XRD powder diffraction pattern shows smectite 02l diffraction bands peaking at 4.59 A for targets John Klein and Cumberland, consistent with tri-octahedral smectites (saponite). From thermal analysis, the saponite abundance is 20 wt. %. Among terrestrial analogues we have studied, ferrian saponite from Griffith Park (Los Angeles, CA) gives the best match to the position of the 02l diffraction band of YNB saponites. Here we describe iron-rich saponites from a terrestrial perspective, with a focus on Griffith saponite, and discuss their implications for the mineralogy of Sheepbed saponite and its formation pathways. Iron-rich saponite: Iron-rich saponite on the Earth is recognized as a low-temperature (<100 C), authigenic alteration product of basalt [e.g., 4-16]. In the discussion that follows, we reference the position of the 02l band because it is a measure of the unit cell 'b' dimension of the octahedral layer and thus the cations (including Fe redox state) in the octahedral layer. Ordinarily, the 06l band near 1.5 A is used to determine the 'b' dimension of smectite, but this band is not accessible with MSL CheMin instrument. For reference, a ferrosaponite (i.e., Fe2+ saponite) studied by [15] has a 02l spacing of 4.72 A and Fe3+/?Fe = 0.27 [15]. Samples of terrestrial ferrosaponite, however, are reported to oxidize on the timescale of days when removed from their natural environment and not protected from oxidation. The Griffith saponite is Mg-rich ferrian saponite, and sample AMNH 89172 has an 02l spacing of 4.59 A (same as the Sheepbed saponites) and Fe3+/?Fe = 0.64 [3]. This similarity suggests that Sheepbed saponites are ferrian (incompletely oxidized ferrosaponite). More oxidized Griffith saponites (Fe3+/?Fe > 0.90) have somewhat smaller 02l d-spacings and also show Mossbauer evidence for an XRD amorphous Fe-bearing phase (e.g., ferrihydrite, hisingerite, superparamagnetic ferric oxides, etc.). The Griffith saponite occurs as vesicle fills, as replacements of olivine, and as replacements of mesostasis (basaltic glass). Similar occurrence modes are reported elsewhere. Hisingerite has been proposed by [13] as the alteration product of ferrian saponite whose precursor by oxidation was ferrosaponite.

Morris, R.V.; Treiman, A. H.; Agresti, D. G.; Graff, T. G.; Achilles, C. N.; Rampe, E. B.; Bristow, T. F.; Ming, D. W.; Blake, D. F.; Vaniman, D. T.; Bish, D. L.; Chipera, S. J.; Morrison, S. M.; Downs, R. T.

2014-01-01

313

Imprinted Clay Coil Vessels  

ERIC Educational Resources Information Center

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…

Lohr, Tresa Rae

2006-01-01

314

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)

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.

Tertre, E.; Hubert, F.; Bruzac, S.; Pacreau, M.; Ferrage, E.; Prêt, D.

2013-07-01

315

... FIELD TRIP GUIDEBOOK ON ENVIRONMENTAL IMPACT OF CLAYS  

E-print Network

............................................31 STOP 2-4. Visitor Center and Gift Shop (Optional For the Clay Minerals Society 28th Annual Meeting Hosted with NASA Johnson Space Center Lunar and Planetary

Rathbun, Julie A.

316

Sandstone Acidizing Using Chelating Agents and their Interaction with Clays  

E-print Network

in the application of acidizing, coreflood tests were performed on Berea and Bandera sandstone cores. Another disadvantage of mud acid has been the fast spending at clay mineral surfaces leading to depletion of acid strength, migration of fines, and formation...

George, Noble Thekkemelathethil 1987-

2013-01-09

317

Cloud condensation nucleus activity comparison of dry- and wet-generated mineral dust aerosol: the significance of soluble material  

E-print Network

This study examines the interaction of clay mineral particles and water vapor for determining the conditions required for cloud droplet formation. Droplet formation conditions are investigated for two common clay minerals, ...

Garimella, Sarvesh

318

Cloud condensation nucleus activity comparison of dry- and wet-generated mineral dust aerosol : the significance of soluble material  

E-print Network

This study examines the interaction of clay mineral particles and water vapor to determine the conditions required for cloud droplet formation. Droplet formation conditions are investigated for two common clay minerals, ...

Garimella, Sarvesh

2014-01-01

319

Evaporite mineral assemblages in the nakhlite (martian) meteorites  

Microsoft Academic Search

A mineralogical study of the three nakhlite (martian) meteorites has revealed that they contain evaporite mineral assemblages. Lafayette has Ca-siderite and clay minerals (smectite\\/illite) along fractures within olivine; Governador Valadares contains clay mineral veins in olivine, with siderite, gypsum and anhydrite in interstitial areas; Nakhla has clay and gypsum veins in olivine, with Mg-, Mn-rich siderite, anhydrite and halite in

J. c. Bridges; M. M. Grady

2000-01-01

320

Maps showing interpretation, using R-mode factor analysis, of trace-element abundances in heavy-mineral concentrate samples, Delta 1° x 2° Quadrangle, Utah  

USGS Publications Warehouse

A set of heavy-mineral concentrate data for the Delta 1° x 2° quadrangle, Utah Conterminous U.S. Mineral Assessment Program (CUSMAP) project was compiled from results of analyses of samples collected during the National Uranium Resource Evaluation Program (SURE), as well as results obtained from samples collected more recently by the USGS. Data results, sampling methods, and analytical methods are provided in Abrogast and others, 1993; 1990; 1988a; 1988b). A similar report, discussing results obtained from stream-sediment samples, is presented in Zimbelman (1993a). The Delta 1° x 2° quadrangle, Utah (figure 1) contains a variety of hydrothermal mineral deposit types, including porphyry-, vein-, replacement-, and Carlin-type deposits. These deposit types have been worked for commodities including gold, silver, beryllium, uranium, lead, zinc, copper, manganese, and cadmium (Lindsey, 1977; Morris and Mogensen, 1978; Zimbelman and others, 1990; Zimbelman and others, 1988). Heavy-mineral concentrate and stream-sediment samples derived from these hydrothermally altered rocks typically contain many geochemical anomalies (for example, see Zimbelman 1993b, c, d). Element associations characterizing lithology and hydrothermal mineral deposits can be distinguished using R-mode factor analysis. This tool often is useful in reconnaissance-scale surveys where sample anomalies are often weak. and single-element distributions may not help to delineate targets. R-mode factors analysis can help identify geologic trends and areas most likely to contain the mineral deposits. R-mode factor analysis was performed on a data set of results of analyses for 19 elements in 643 samples and produced a six-factor model. These six factors represent the geochemical contributions to the data set provided by lithologic and mineralization processes, The distribution of samples that contain high scores for mineralization-related factors is widespread in the Delta quadrangle. These sample sites are though to relate to both known prospect and mineralization areas, as well as define new areas that are geochemically favorable to contain altered or mineralized rocks.

Zimbelman, David R.

1994-01-01

321

Using Natural Clays and Spent Bleaching Clay as Cheap Adsorbent for the Removal of Phenol in Aqueous Media  

E-print Network

Abstract-- Clay samples of six different locations of Kurdistan region were characterized. Chemical compositions of the clays were found using XRF technique for the clay powders. The mineralogy of the samples by XRD shows that the clay samples are mostly mixed layer type of Chlorite/Smectite composition with different types and quantities of mineral impurities. Specific surface area (SSA) and cation exchange capacity (CEC) for the clay samples were determined by methylene blue adsorption method. Although the de-oiled spent clays have less SSA and CEC compared with their virgin samples, but their adsorption efficiency is 70-80 % higher than their virgin clays due to the increase in the organophilic character of the de-oiled spent clays, while acid activation of the natural clays has no significant effect on the adsorption efficiency. Charcoal, the universal adsorbent, has removed 58 % of 50 ppm phenol solution, while de-oiled spent clays have removed 80-95 % of the phenol concentration. Index Term-- removal of phenol, de-oiling of clay, spent bleaching clay, adsorption efficiency. I.

Bakhtyar K. Aziz; Fuad H. Shareef

322

Effects of calcination temperature of kaolinite clays on the properties of geopolymer cements  

Microsoft Academic Search

The aim of this work is to determine the most convenient calcination temperature of kaolinite clays in view of producing geopolymer cements. In this light, the clay fractions of three kaolin minerals were used. The clay fractions were characterized (chemical and thermal analyses and X-ray diffraction) and then calcined in the temperature range of 450 and 800°C. The obtained amorphous

A. Elimbi; H. K. Tchakoute; D. Njopwouo

2011-01-01

323

The role of charcoal on DTA curves of organo-clay complexes: an overview  

Microsoft Academic Search

DTA of organo-clay complexes supplemented by other thermal analysis methods supplies information on the thermal reactions, properties and stability of the complex, the amount and properties of the adsorbed water in the organo-clay and on the bonding between the organic species and the clay. It is used to identify the mineral to differentiate between various complexes composed of the same

Shmuel Yariv

2004-01-01

324

Natural Radioactivity of Boron Added Clay Samples  

NASA Astrophysics Data System (ADS)

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

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

2011-12-01

325

Natural Radioactivity of Boron Added Clay Samples  

SciTech Connect

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

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

2011-12-26

326

Mineral Commodities  

NSDL National Science Digital Library

This exercise introduces mineral commodities (elements). Students consider the elements aluminum, iron, copper, nickel, zinc, uranium, lead, gold, mercury and tin and match them with their definintions in a table. Then they use minable grade (minable weight percent) and normal crustal abundance (crustal weight percent) to calculate the concentration factor for several commodities to determine their economic minability. Students then graph their calculations and explain their trend.

Dexter Perkins

327

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...

328

Prolonged triboluminescence in clays and other minerals  

NASA Technical Reports Server (NTRS)

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.

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

1982-01-01

329

Lipid Peroxidation Induced by Expandable Clay Minerals  

E-print Network

I E T O - C A M A C H O , A N D J A V I E R A C E R V I N I - S I L V A * , § , , Facultad de Qui´mica, Universidad Nacional Auto´noma de Me´xico, Instituto de Qui´mica, Universidad Nacional Auto´noma de Me

Ahmad, Sajjad

330

Sediment management and renewability of floodplain clay for structural ceramics  

NASA Astrophysics Data System (ADS)

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.

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

331

Clays causing adhesion with tool surfaces during mechanical tunnel driving  

NASA Astrophysics Data System (ADS)

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 frame of the programme GEOTECHNOLOGIEN.

Spagnoli, G.; Fernández-Steeger, T.; Stanjek, H.; Feinendegen, M.; Post, C.; Azzam, R.

2009-04-01

332

Recordof Mineral Aerosolsand Their Roleinthe Earth System  

E-print Network

, feldspars, and calcite, clay minerals rich in elements such as aluminum, and oxides and hydroxides rich4.13 Recordof Mineral Aerosolsand Their Roleinthe Earth System K.E. Kohfeld Simon Fraser University dust is a type of mineral aerosol, and comprises one component of the total atmos- pheric aerosol

Kohfeld, Karen

333

Comparison of tetrachloromethane sorption to an alkylammonium-clay and an alkyldiammonium-clay  

USGS Publications Warehouse

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.

Smith, J.A.; Jaffe, P.R.

1991-01-01

334

Iodide Sorption to Clays and the Relationship to Surface Charge and Clay Texture - 12356  

SciTech Connect

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)

Miller, Andrew; Kruichiak, Jessica; Tellez, Hernesto; Wang, Yifeng [Sandia National Laboratories, Albuquerque, NM 87185 (United States)

2012-07-01

335

Rocks and Minerals  

NSDL National Science Digital Library

This unit provides younger students with an introduction to rocks and minerals. Topics include the definition of a mineral, the physical properties of minerals and how they are measured, and a discussion of quartz, the most basic silicate mineral and one of the most abundant minerals in the Earth's crust. The discussion on rocks includes the rock cycle, the three rock types (igneous, sedimentary, metamorphic), and how they are formed. There is also a vocabulary list and downloadable, printable worksheets for each major topic.

Medina, Philip

2010-09-08

336

Soil clay content underlies prion infection odds  

USGS Publications Warehouse

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.

David, Walter W.; Walsh, D.P.; Farnsworth, Matthew L.; Winkelman, D.L.; Miller, M.W.

2011-01-01

337

Clays in prebiological chemistry  

NASA Technical Reports Server (NTRS)

The ways in which clays have been utilized in studies of prebiological chemistry are reviewed, and an assessment is given of the possible role of clays in prebiological systems. The adsorption of organic molecules on clays has been demonstrated, as has the synthesis of bioorganic monomers in the presence of clays. For instance, amino acids, purines and pyrimidines have been obtained from carbon monoxide and nitric acid in the presence of clays at relatively high temperatures (250-325 C). The oligomerization of biochemical monomers, mediated by clays, has also been shown to result in the formation of polymer molecules basic to life. Clays have also been found to affect the condensation of mononucleotides to oligonucleotides.

Rao, M.; Oro, J.; Odom, D. G.

1980-01-01

338

Influence of improved subsurface drainage on phosphorus losses and nitrogen leaching from a heavy clay soil  

Microsoft Academic Search

Without proper subsurface drainage of heavy clay soil, water logging due to low hydraulic conductivity of the surface soil and especially the subsoil will lead to abundant surface runoff. The abundant runoff will induce soil erosion and phosphorus losses. To determine the influence of improved subsurface drainage (IMP) on soil erosion, phosphorus losses and nitrogen leaching, a heavy clay soil

E. Turtola; A. Paajanen

1995-01-01

339

Modeling Oil-Mineral Interactions Sungu Hwang, Mario Blanco, and William A. Goddard, III  

E-print Network

1 #12;Objectives Forcefield development of calcite and clay minerals Mineral - water, and mineralModeling Oil-Mineral Interactions Sungu Hwang, Mario Blanco, and William A. Goddard, III Materials - chemicals interactions The adsorption of chemicals on minerals The atomistic simulation of the minerals

Goddard III, William A.

340

Yangtze River sediments from source to sink traced with clay mineralogy  

NASA Astrophysics Data System (ADS)

River bed sediments were collected from the main stream and major tributaries of the Yangtze River for clay mineralogy study. Surface sediments from the Yarlung Zangbo River on the Tibetan Plateau were also examined for comparison. The results show that the clay mineral compositions of the Yangtze River display a similar pattern through the whole truck stream, with illite being dominant, kaolinite and chlorite being lesser abundant, and smectite being minor component. Clay mineralogy shows distinct differences in the tributaries, which correspond to the heterogeneous source rocks and weathering intensity of the drainage. The illite crystallity and the illite chemical weathering index (5 Å/10 Å peak ratio) both increase downstream, indicating a increasing trend of hydrolysis along the river. It also indicates that the upperstream of the drainage is characterized with physical weathering while the middle- and lower reaches are controlled by chemical weathering process. In accordance with the result derived by the illite indexes, sediment input from upperstream including Yalong Jiang, Dadu He, Min Jiang and Jialing Jiang accounts for the major sediment load, whereas Wu Jiang, Xiang Jiang, Gan Jiang and Dongting Lake provide relatively less sediments.

He, Mengying; Zheng, Hongbo; Huang, Xiangtong; Jia, Juntao; Li, Ling

2013-06-01

341

The influence of authigenic clay formation on the mineralogy and stable isotopic record of lacustrine carbonates  

NASA Astrophysics Data System (ADS)

The mineralogical, compositional and stable isotopic variability of lacustrine carbonates are frequently used as proxies for ancient paleoenvironmental change in continental settings, under the assumption that precipitated carbonates reflect conditions and chemistry of ancient lake waters. In some saline and alkaline lake systems, however, authigenic clay minerals, forming at or near the sediment water interface, are a major sedimentary component. Often these clays are rich in Mg, influencing the geochemical budget of lake waters, and are therefore expected to influence the properties of contemporaneous authigenic carbonate precipitates (which may also contain Mg). This paper documents evidence for a systematic feedback between clay mineral and carbonate authigenesis through multiple precessionally driven, m-scale sedimentary cycles in lacustrine oil-shale deposits of the Eocene Green River Formation from the Uinta Basin (NE Utah). In the studied section, authigenic, Mg-rich, trioctahedral smectite content varies cyclically between 9 and 39 wt.%. The highest concentrations occur in oil-shales and calcareous mudstones deposited during high lake level intervals that favored sedimentary condensation, lengthening the time available for clay diagenesis and reducing dilution by other siliciclastic phases. An inverse relation between dolomite percentage of carbonate and trioctahedral smectite abundance suggests the Mg uptake during clay authigenesis provides a first order control on carbonate mineralogy that better explains carbonate mineralogical trends than the possible alternative controls of (1) variable Mg/Ca ratios in lake water and (2) degree of microbial activity in sediments. We also observe that cyclical change in carbonate mineralogy, believed to be induced by clay authigenesis, also causes isotopic covariation between ?13CPDB and ?18OPDB of bulk sediments because of differences in the equilibrium fractionation factors of dolomite and calcite (˜2‰ and ˜2.6%, respectively). This provides an alternative mechanism for the common pattern of isotopic covariation, which is typically attributed to the effect of simultaneous changes in water balance and biological activity on the carbon and oxygen isotopic composition of lake waters. These findings may help improve paleoenvironmental reconstructions based on lacustrine carbonate records by adding to the factors known to influence the mineralogical, compositional and stable isotopic signals recorded by lacustrine carbonates.

Bristow, Thomas F.; Kennedy, Martin J.; Morrison, Keith D.; Mrofka, David D.

2012-08-01

342

Comparison of abundances of chemical elements in mineralized and unmineralized sandstone of the Brushy Basin Member of the Morrison Formation, Smith Lake District, Grants uranium region, New Mexico  

USGS Publications Warehouse

Statistical treatment of analytical data from the Mariano Lake and Ruby uranium deposits in the Smith Lake district, New Mexico, indicates that organic carbon, arsenic, barium, calcium, cobalt, copper, gallium, iron, lead, manganese, molybdenum, nickel, selenium, strontium, sulfur, vanadium, yttrium, and zirconium are concentrated along with uranium in primary ore. Comparison of the Smith Lake data with information from other primary deposits in the Grants uranium region and elsewhere in the Morrison Formation of the Colorado Plateau suggests that these elements, with the possible exceptions of zirconium and gallium and with the probable addition of aluminum and magnesium, are typically associated with primary, tabular uranium deposits. Chemical differences between the Ruby and Mariano Lake deposits are consistent with the interpretation that the Ruby deposit has been more affected by post-mineralization oxidizing solutions than has the Mariano Lake deposit.

Pierson, C.T.; Spirakis, C.S.; Robertson, J.F.

1983-01-01

343

Mineralogical and geochemical signatures of clays associated with rhyodacites in the Nefza area (northern Tunisia)  

NASA Astrophysics Data System (ADS)

The geology of northern Tunisia is marked by magmatic extrusion that occurred during the Middle Miocene (Langhian-Lower Tortonian), which led to the outcrops of rhyodacites in the Nefza-Tabarka region. This event is contemporaneous with the Alpine compressional phase, which is well-characterised in the western Mediterranean area, where intense fracturing and hydrothermalism occurred with evidence of metallogenic consequences. In this paper, a detailed study is presented on the acid volcanic rocks that outcrop at the core of the Oued Belif structure in the Nefza area of northern Tunisia. The results indicate that these series have undergone various transformations subsequent to their extrusion. These alterations include ferrugination, silicification, argilitisation and devitrification of volcanic glass. Petrographic observations demonstrated that the primary minerals, particularly feldspars, biotite and mesostasis glass, were affected by hydrothermal and meteoric weathering. The mineralogical study of the neogenic products revealed a nearly monomineral smectitic phase with relatively low levels of added illite and/or kaolinite. These neoformed smectites were classified as ferroan beidellites-nontronite based on thermal and crystallochemical analyses. Chemical analysis of the major elements, trace elements and rare Earth elements (REEs) show the presence of Al, Fe and K and an enrichment of REE in the clay fraction with a greater fractionation of light rare Earth elements (LREEs) compared with that of heavy rare Earth elements (HREEs). The abundance of these elements is attributed to their mobility during chemical weathering of acidic lavas and their adsorption by clay minerals.

Sghaier, D.; Chaabani, F.; Proust, D.; Vieillard, Ph.

2014-12-01

344

Modified clay sorbents  

DOEpatents

A novel modified clay sorbent and method of treating industrial effluents to remove trace pollutants, such as dioxins, biphenyls, and polyaromatics such as benzo(a)pyrene and pentachlorophenol. The novel clay sorbent has a composite structure in which the interlayer space of an expandable clay, such as smectite, is filled with polyvalent or multivalent inorganic cations which forces weaker surfactant cations to locate on the surface of the clay in such an orientation that the resulting composite is hydrophilic in nature. A specific example is cetylpyridinium-hydroxy aluminum-montmorillonite. In certain embodiments, a non-expanding clay, such as kaolinite, is used and surfactant cations are necessarily located on an external surface of the clay. A specific example is cetylpyridinium-kaolinite.

Fogler, H. Scott (Ann Arbor, MI); Srinivasan, Keeran R. (Livonia, MI)

1990-01-01

345

Ni Sorption/Release on Soil Clay Fractions A Kinetic and EXAFS Study D. R. Roberts, and A. M. Scheidegger  

E-print Network

mechanisms on soil clay fractions based on XAFS and kinetic analysis and on a complete characterizationNi Sorption/Release on Soil Clay Fractions A Kinetic and EXAFS Study D. R. Roberts, and A. M in soils have often been studied on standard clay minerals and metal oxides while using a macroscopic

Sparks, Donald L.

346

The occurrence of clays and their bearing on evaporite mineralogy in the Salado Formation, Delaware Basin, New Mexico  

E-print Network

, potassium, and magnesium K-alpha linescans from sample in SEM photograph (thin 'line). The dark area corresponding to the high silicon area is clay. The mineral to the left of the clay is langbefnite, and to the right of the clay is halite. . . . Thin... by solutions high in magnesium and/or potassium. Bodine (1978) also favored a diagenetic origin for clays in Ochoan Rocks of the Delaware Basin, where illite and corrensite were found to be the dominant clay minerals. Bodine (1978) also recognized...

Harville, Donald Gene

1985-01-01

347

Field trip guidebook on environmental impact of clays along the upper Texas coast  

NASA Technical Reports Server (NTRS)

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.

Garcia, Theron D.; Ming, Douglas W.; Tuck, Lisa Kay

1991-01-01

348

Clay Portrait Boxes  

ERIC Educational Resources Information Center

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…

Wilbert, Nancy Corrigan

2009-01-01

349

Columns in Clay  

ERIC Educational Resources Information Center

This article describes a clay project for students studying Greece and Rome. It provides a wonderful way to learn slab construction techniques by making small clay column capitols. With this lesson, students learn architectural vocabulary and history, understand the importance of classical architectural forms and their influence on today's…

Leenhouts, Robin

2010-01-01

350

External Resource: Clay Planets  

NSDL National Science Digital Library

In this activity, learners/students use given amounts of clay to create models of the solar system. Learners/students use clay to represent different planets and other objects in the solar system (asteroids, moons, etc.). The learners/students can use as

1900-01-01

351

Biodegradation of crude oil saturated fraction supported on clays.  

PubMed

The role of clay minerals in crude oil saturated hydrocarbon removal during biodegradation was investigated in aqueous clay/saturated hydrocarbon microcosm experiments with a hydrocarbon degrading microorganism community. The clay minerals used for this study were montmorillonite, palygorskite, saponite and kaolinite. The clay mineral samples were treated with hydrochloric acid and didecyldimethylammonium bromide to produce acid activated- and organoclays respectively which were used in this study. The production of organoclay was restricted to only montmorillonite and saponite because of their relative high CEC. The study indicated that acid activated clays, organoclays and unmodified kaolinite, were inhibitory to biodegradation of the hydrocarbon saturates. Unmodified saponite was neutral to biodegradation of the hydrocarbon saturates. However, unmodified palygorskite and montmorillonite were stimulatory to biodegradation of the hydrocarbon saturated fraction and appears to do so as a result of the clays' ability to provide high surface area for the accumulation of microbes and nutrients such that the nutrients were within the 'vicinity' of the microbes. Adsorption of the saturated hydrocarbons was not significant during biodegradation. PMID:23670057

Ugochukwu, Uzochukwu C; Jones, Martin D; Head, Ian M; Manning, David A C; Fialips, Claire I

2014-02-01

352

Composition and geochemistry of clay sediments offshore the northeastern Sicilian coast (Southeastern Tyrrhenian Sea, Italy)  

NASA Astrophysics Data System (ADS)

Grain-size, mineralogical and chemical analyses were carried out on fine fraction of sediments collected in the Gulfs of Patti and Milazzo, two borderland basins in the Southern Tyrrhenian extending offshore the northeastern Sicilian coast. Results of granulometric analyses on size fractions smaller than 63 ?m showed that the investigated samples can be classified mainly as clayey silts. The coarse fractions (>63 ?m), examined by optical microscopy, consist of a terrigenous component, representing in some samples about 98-99% of the total sediment, and by a biogenic component. This latter is mainly made up of benthic Foraminifera. The mineralogical composition of the fine fraction, determined by X-Ray diffractometry, is represented by muscovite, quartz, clay minerals, carbonates (calcite) and, in some samples, by calcium and sodium-rich plagioclases. The method of saturation with K and Mg, followed by ethylene glycol solvation and heating, are used for a qualitative determination of the clay minerals. Clay mineralogical composition is characterized by the dominance of clinochlore and illite, with minor amounts of smectite (especially montmorillonite) and vermiculite. The chemical data reflect the main mineralogical composition showing a uniform quantitative composition, with high Al 2O 3 and SiO 2 values and very few variations in the relative abundance of the other components. The Cr/Th, Th/Sc, Th/Co and La/Sc ratios suggest a felsic nature of the source rocks. Finally the geochemical parameters such as V/Cr, U/Th, Ni/Co and Cu/Zn ratios indicate that examined sediments were deposited under oxic environments.

Saccà, Carmelo; Saccà, Domenica; Nucera, Preziosa; De Fazio, Anna

2011-05-01

353

Semi-permeable vesicles composed of natural clay  

E-print Network

We report a simple route to form robust, inorganic, semi-permeable compartments composed of montmorillonite, a natural plate-like clay mineral that occurs widely in the environment. Mechanical forces due to shear in a narrow gap assemble clay nanoplates from an aqueous suspension onto air bubbles. Translucent vesicles suspended in a single-phase liquid are produced when the clay-covered air bubbles are exposed to a variety of water-miscible organic liquids. These vesicles of clay are mechanically robust and are stable in water and other liquids. The formation of clay vesicles can be described by a physical mechanism that recognizes changes in the wetting characteristics of clay-covered air bubbles in organic liquids. The clay vesicles are covered with small pores and so intrinsically exhibit size-selective permeability, which allows spontaneous compartmentalization of self-assembling molecules in aqueous environments. The results we report here expand our understanding of potential paths to micro-compartmentalization in natural settings and are of relevance to theories of colloidal aggregation, mineral cycles, and the origins of life.

Anand B. Subramaniam; Jiandi Wan; Arvind Gopinath; Howard A. Stone

2010-11-22

354

Zeta Potential Measurements on Three Clays from Turkey and Effects of Clays on Coal Flotation  

PubMed

There is a growing trend of characterizing coal and coal wastes in order to study the effect of clays present in them during coal washing. Coarse wastes from the Zonguldak Coal Washery, Turkey, were characterized and found to contain kaolinite, illite, and chlorite. These three clays, obtained in almost pure form from various locations in Turkey, have been subjected to X-ray diffraction (XRD) analysis to assess their purity and zeta potential measurements in order to evaluate their properties in terms of their surface charge and point of zero charge (pzc) values. It was found from XRD data that these clays were almost pure and their electrokinetic potential should therefore be representative of their colloidal behavior. All three clay minerals were negatively charged over the range from pH 2.5 to 11. Chlorite and illite have pzc at pH 3 and pH 2.5, respectively, whereas kaolinite has no pzc. The effect of these clays in Zonguldak coal, wastes, and black waters on coal flotation was studied by floating artificial mixtures of Zonguldak clean coal (4.5% ash) and individual clay. The flotation tests on coal/individual clay revealed that each clay influences coal flotation differently according to its type and amount. Illite had the worst effect on coal floated, followed by chlorite and kaolinite. The loss of yield in coal was found to be 18% for kaolinite, 20% for chlorite, and 28% for illite, indicating the worst effect of illite and least for kaolinite during coal flotation. PMID:8978557

Hussain; Dem&idot;rc&idot;; özbayoğlu

1996-12-25

355

Chemistry, mineralogy and origin of the clay-hill nitrate deposits, Amargosa River valley, Death Valley region, California, U.S.A.  

USGS Publications Warehouse

The clay-hill nitrate deposits of the Amargosa River valley, California, are caliche-type accumulations of water-soluble saline minerals in clay-rich soils on saline lake beds of Miocene, Pliocene(?) and Pleistocene age. The soils have a maximum thickness of ??? 50 cm, and commonly consist of three layers: (1) an upper 5-10 cm of saline-free soil; (2) an underlying 15-20 cm of rubbly saline soil; and (3) a hard nitrate-rich caliche, 10-20 cm thick, at the bottom of the soil profile. The saline constituents, which make up as much as 50% of the caliche, are chiefly Cl-, NO-3, SO2-4 and Na+. In addition are minor amounts of K+, Mg2+ and Ca2+, varying, though generally minor, amounts of B2O3 and CO2-3, and trace amounts of I (probably as IO-3), NO-2, CrO2-4 and Mo (probably as MoO2-4). The water-soluble saline materials have an I/Br ratio of ??? 1, which is much higher than nearly all other saline depostis. The principal saline minerals of the caliche are halite (NaCl), nitratite (NaNO3), darapskite (Na3(SO4)(NO3)??H2O), glauberite (Na2Ca(SO4)2), gypsum (CaSO4??2H2O) and anhydrite (CaSO4). Borax (Na2B4O5(OH)4??8H2O), tincalconite (Na2B4O5(OH)4??3H2O) and trona (Na3(CO3)(HCO3)??2H2O) are abundant locally. The clay-hill nitrate deposits are analogous to the well-known Chilean nitrate deposits, and probably are of similar origin. Whereas the Chilean deposits are in permeable soils of the nearly rainless Atacama Desert, the clay-hill deposits are in relatively impervious clay-rich soils that inhibited leaching by rain water. The annual rainfall in the Death Valley region of ??? 5 cm is sufficient to leach water-soluble minerals from the more permeable soils. The clay-hill deposits contain saline materials from the lake beds beneath the nitrate deposits are well as wind-transported materials from nearby clay-hill soils, playas and salt marshes. The nitrate is probably of organic origin, consisting of atmospheric nitrogen fixed as protein by photoautotrophic blue-green algae, which are thought to form crusts on soils at the sites of the deposits when moistened by rainfall. The protein is subsequently transformed to nitrate by autotophic bacteria. ?? 1988.

Ericksen, G.E.; Hosterman, J.W.; St., Amand, P.

1988-01-01

356

Low temperature CO2 mineralization into basalt: solution chemistry and secondary mineral assemblages  

NASA Astrophysics Data System (ADS)

CO2 represents one of the most abundant acid supplies in nature and has an important impact on element fluxes and water chemistry on the Earth surface. CO2 emissions due to increased industrialization are causing an important imbalance in this surface system and affect the global climate. Therefore, different methods to trap CO2 are developed and studied in response to the CO2 increase. CO2 sequestration into secondary minerals is considered as one possible way of reducing those CO2 levels. The Carbfix project is a pilot study in SW Iceland aiming to inject CO2-loaded waters from the Hellisheidi geothermal powerplant into basaltic rock formations. The goal is to mineralize CO2 by reacting Ca+2, Mg+2 and Fe+2 ions released by the basalt into carbonates. We investigated the geochemical aspects of CO2-water-basalt interaction at pCO2 between 0-20 bar and temperatures of 25-40°C by combining experiments and numerical modelling. The aim of our studies are to gain a better understanding of the key reactions, mass fluxes and porosity changes associated to CO2-water-basalt interaction. Modelling results show that at low reaction progress (pH <7), the main secondary mineral assemblages formed by reacting CO2- water-basalt are amorphous SiO2, Fe-Mg carbonates, Al-silicates and Fe-hydroxides, whereas at high reaction progress (pH >8) the main stable minerals precipitating from solution are (Ca)-Mg-Fe clays, Ca-Mg carbonates and zeolites (Gysi and Stéfansson 2008). Laboratory experiments were performed by reacting basaltic glass with aqueous solutions initially saturated at pCO2 ranging between 0-10 bar at 40°C for 120 days. Results from solution chemistry show that there are three different element mobility behaviors: i) Si+4 and Al+3 dissolve non-stochiometrically and/or precipitate into secondary minerals independent of the intial pCO2 and the water/rock ratios used in the experiments, b) Ca+2 and Mg+2 dissolve stochiometrically independent of the initial pCO2, but precipitate into secondary minerals at high water/rock ratios and low initial pCO2 after about 100 days, c) elements like Fe show a mixed behavior from mobile to immobile depending on the solution pH and their oxidation state. Secondary mineral assemblages were identified using SEM, and WDS elemental maps combined with quantitative analysis on EMPA. In all experiments, secondary minerals precipitating from solution were (Ca)-(Mg)-Fe-rich carbonates, amorphous Fe-hydroxides and (Na)-Ca-Mg-Fe clays. Our model compare qualitatively well with the experiments, the key factors controlling CO2 mineralization into carbonates beeing competing reactions between clays and carbonates for Ca+2, Mg+2 and Fe+2 ions.

Gysi, A.; Stefánsson, A.

2009-12-01

357

The effects of the mineral phase on C stabilization mechanisms and the microbial community along an eroding slope transect  

NASA Astrophysics Data System (ADS)

An increasing number of studies show the importance of including soil redistribution processes in understanding carbon (C) dynamics in eroding landscapes. The quality and quantity of soil organic carbon in sloping cropland differs with topographic position. These differences are commonly more visible in the subsoil, while the size and composition of topsoil C pools are similar along the hillslope. The type (plant- or microbial-derived) and quality (level of degradation) of C found in a specific soil fraction depends on the interplay between the temporal dynamic of the specific mechanism and it's strength to protect C from decomposition. Here, we present an analysis that aims to clarify the bio/geo-chemical and mineralogical components involved in stabilizing C at various depths and slope positions and how they affect the microbial community and the degradation of C. For this we analyzed soil samples from different soil depths along a slope transect applying (i) a sequential extraction of the reactive soil phase using pyrophosphate, oxalate and dithionite-citrate-bicarbonate, (ii) a semi-quantitative and qualitative analysis of the clay mineralogy, (iii) an analysis of the microbial community using amino sugars and (iv) an analysis of the level of degradation of C in different soil fractions focusing on the soil Lignin signature. The results show that the pattern of minerals and their relative importance in stabilizing C varies greatly along the transect. In the investigated soils, pyrophosphate extractable Manganese, and not Iron or Aluminum as often observed, is strongly correlated to C in the bulk soil and in the non-aggregated silt and clay fractions. This suggests a certain role of Manganese for C stabilization where physical protection is absent. In contrast, pyrophosphate extractable Iron and Aluminum components are largely abundant in water-stable soil aggregates but not correlated to C, suggesting importance of these extracts to stabilize aggregates and, hence, providing physical protection of C. Oxalate extractable amorphous and poorly crystalline minerals are correlated to C, especially for the more recalcitrant C fractions, but only at the depositional site. However, decreasing contents of oxalate extractable elements with depth indicate a temporal limitation of this stabilization mechanism and this is also supported by the results of our lignin extraction. Non-expandable clay minerals experience a relative enrichment at the depositional site while expandable clay minerals experience the same at the eroding site. These changes in clay mineralogy along the slope are partly responsible for the abundance of silt and clay associated C. The changes in soil mineralogy and micro-scale environmental conditions led to an adaptation of the microbial community in comparison to sites not affected by soil redistribution.

Doetterl, S.; Opfergelt, S.; Cornelis, J.; Boeckx, P. F.; van oost, K.; Six, J.

2013-12-01

358

Reductive Dissolution of Iron Oxides and Iron-Rich Clays Enhanced by Sulfate-Reducing Bacteria  

NASA Astrophysics Data System (ADS)

Iron oxides and iron-rich clays are abundant in low-temperature sedimentary environments where sulfate-reducing bacteria are also present. This study summarizes our research on reductive dissolution of ferrihydrite, goethite, hematite, magnetite, and a nontronite clay by Desulfovibrio spp. strain G-20 and strain G-11. The goal was twofold: (1) to understand the enzymatic processes of iron reduction by sulfate-reducing bacteria (SRB) using iron as the sole electron acceptor and (2) to determine whether iron reduction from the oxides and clays could be enhanced by biogenic H2S through an enzymatic process during sulfate reduction. In the iron-oxide experiments without sulfate, iron reduction by G-20 averaged about 4.5% of total iron for ferrihydrite, goethite, and hematite. The reduction of magnetite, however, was about threefold higher (13.3%). The maximum biomass of G-20 gained during iron reduction was also highest in the magnetite culture, suggesting that reduction of magnetite may have stimulated the growth of G-20. In the presence of sulfate, iron reduction was dramatically enhanced in all cultures (>70%). In inorganic experiments using Na2S, less than 4% total iron was reduced from goethite or hematite and about 19% was reduced from magnetite. The enhanced reduction of iron during sulfate reduction may have resulted from enzymatic activity of the SRB or through the chelation of solids with organic acids and other organic molecules. Transmission electron microscopy (TEM) showed shortened and thinned goethite and hematite crystals during sulfate and iron reduction. The magnetite crystals, on the other hand, were disintegrated extensively. For the nontronite experiments using G-11, iron reduction from the clay was about 10% of total structural Fe(III) in the absence of sulfate but reached 29% in the presence of sulfate. Abiotic iron reduction using Na2S, on the other hand, was ca. 7.5% of total structural Fe(III). Analyses of TEM and X-ray diffraction revealed significant changes in structure and composition of the clay during its dissolution by G-11. Overall, this study demonstrates that sulfate-reducing bacteria can dramatically enhance the dissolution of iron oxides and iron-rich clays, thus accelerating the transformation of these minerals in sulfate-rich environments.

Zhang, C. L.

2003-12-01

359

Induced polarization of clay-sand mixtures. Experiments and modelling.  

NASA Astrophysics Data System (ADS)

The complex conductivity of saturated unconsolidated sand-clay mixtures was experimentally investigated using two types of clay minerals, kaolinite and smectite (mainly Na-Montmorillonite) in the frequency range 1.4 mHz - 12 kHz. The experiments were performed with various clay contents (1, 5, 20, and 100 % in volume of the sand-clay mixture) and salinities (distilled water, 0.1 g/L, 1 g/L, and 10 g/L NaCl solution). Induced polarization measurements were performed with a cylindrical four-electrode sample-holder associated with a SIP-Fuchs II impedance meter and non-polarizing Cu/CuSO4 electrodes. The results illustrate the strong impact of the CEC of the clay minerals upon the complex conductivity. The quadrature conductivity increases steadily with the clay content. We observe that the dependence on frequency of the quadrature conductivity of sand-kaolinite mixtures is more important than for sand-bentonite mixtures. For both types of clay, the quadrature conductivity seems to be fairly independent on the pore fluid salinity except at very low clay contents. The experimental data show good agreement with predicted values given by our SIP model. This complex conductivity model considers the electrochemical polarization of the Stern layer coating the clay particles and the Maxwell-Wagner polarization. We use the differential effective medium theory to calculate the complex conductivity of the porous medium constituted of the grains and the electrolyte. The SIP model includes also the effect of the grain size distribution upon the complex conductivity spectra.

Okay, G.; Leroy, P.

2012-04-01

360

Effects of tunneling on groundwater flow and swelling of clay-sulfate rocks  

E-print Network

[1] Swelling of clay-sulfate rocks is a major threat in tunneling. It is triggered by the transformation of the sulfate mineral anhydrite into gypsum as a result of water inflow in anhydrite-containing layers after tunnel ...

Butscher, Christoph

361

BASE-EXCHANGE CAPACITY AND CLAY MINERALOGY OF SOME MODERN STREAM SEDIMENTS  

Microsoft Academic Search

Clay mineralogy and exchange capacity of modern stream sediments in the United States appear to show definite changes with geographic location, presumably due in part to climatic differences. In the eastern United States, kaolinite, illite, and dioctahc- dral vcrmiculite arc the most common clay minerals in stream sediments, but west of the Mississippi River montmorillonite, illite, or mixed-layer montmorillonite-illite are

Vance C. KENNEDY

362

The use of illitic clays in the production of stoneware tile ceramics  

Microsoft Academic Search

Illite is one of the main clay phases used for the preparation of mixtures for traditional ceramics. The raw materials used for production of white porcelain stoneware tiles mainly consist of feldspars, quartz, and clay minerals (kaolinite, smectite and illite). In this study, eight clayey raw materials with a different content of illite up to 70 wt.%, have been considered.

S. Ferrari; A. F. Gualtieri

2006-01-01

363

Effects of Clay Dispersion on Aquifer Storage and Recovery in Coastal Aquifers  

Microsoft Academic Search

Cyclic injection, storage, and withdrawal of freshwater in brackish aquifers is a form of aquifer storage and recovery (ASR) that can beneficially supplement water supplies in coastal areas. A 1970s field experiment in Norfolk, Virginia, showed that clay dispersion in the unconsolidated sedimentary aquifer occurred because of cation exchange on clay minerals as freshwater displaced brackish formation water. Migration of

L. F. Konikow; L. L. August; C. I. Voss

2001-01-01

364

Speciation of uranium in surface-modified, hydrothermally treated, (UOâ){sup 2+}-exchanged smectite clays  

Microsoft Academic Search

A successful solution to the problem of disposal and permanent storage of water soluble radioactive species must address two issues: exclusion of the radionuclides from the environment and the prevention of leaching from the storage media into the environment. Immobilization of radionuclides in clay minerals has been studied. In addition to the use of clays as potential waste forms, information

D. M. Giaquinta; L. Soderholm; S. E. Yuchs; S. R. Wasserman

1997-01-01

365

Retention of organic molecule ‘‘quinalizarin’’ by bentonitic clay saturated with different cations  

Microsoft Academic Search

The adsorption of organic molecule to clay mineral has been reported by several investigators. The purpose of this investigation was to removal quinalizarin, witch is a toxic molecule used to dye cotton, from aqueous solution by smectite clay modified by different exchangeable cations: monovalent, divalent and trivalent cations.A group of isotherm tests were performed to clarify specific sorption behaviors due

F. Ayari; E. Srasra; M. Trabelsi-Ayadi

2007-01-01

366

Liquid–crystalline aqueous clay suspensions  

PubMed Central

This article demonstrates the occurrence of a true isotropic/nematic transition in colloidal Brownian aqueous suspensions of natural nontronite clay. The liquid–crystalline character is further evidenced by polarized light microscopy and small-angle x-ray scattering experiments in the presence and absence of modest external magnetic fields. The complete phase diagram ionic strength/volume fraction then exhibits a clear biphasic domain in the sol region just before the gel transition in contrast with the situation observed for other swelling clays in which the sol/gel transition hinders the isotropic/nematic transition. Small-angle x-ray scattering measurements of gel samples reveal strong positional and orientational orders of the particles, proving unambiguously the nematic character of the gel and, thus, clearly refuting the still prevalent “house of cards” model, which explains the gel structure by means of attractive interactions between clay platelets. Such order also is observed in various other swelling clay minerals; therefore, this very general behavior must be taken into account to reach a better understanding of the rheological properties and phase behavior of these systems. PMID:17060625

Michot, Laurent J.; Bihannic, Isabelle; Maddi, Solange; Funari, Sérgio S.; Baravian, Christophe; Levitz, Pierre; Davidson, Patrick

2006-01-01

367

Liquid-crystalline aqueous clay suspensions.  

PubMed

This article demonstrates the occurrence of a true isotropic/nematic transition in colloidal Brownian aqueous suspensions of natural nontronite clay. The liquid-crystalline character is further evidenced by polarized light microscopy and small-angle x-ray scattering experiments in the presence and absence of modest external magnetic fields. The complete phase diagram ionic strength/volume fraction then exhibits a clear biphasic domain in the sol region just before the gel transition in contrast with the situation observed for other swelling clays in which the sol/gel transition hinders the isotropic/nematic transition. Small-angle x-ray scattering measurements of gel samples reveal strong positional and orientational orders of the particles, proving unambiguously the nematic character of the gel and, thus, clearly refuting the still prevalent "house of cards" model, which explains the gel structure by means of attractive interactions between clay platelets. Such order also is observed in various other swelling clay minerals; therefore, this very general behavior must be taken into account to reach a better understanding of the rheological properties and phase behavior of these systems. PMID:17060625

Michot, Laurent J; Bihannic, Isabelle; Maddi, Solange; Funari, Sérgio S; Baravian, Christophe; Levitz, Pierre; Davidson, Patrick

2006-10-31

368

Role of interlayer hydration in lincomycin sorption by smectite clays.  

PubMed

Lincomycin, an antibiotic widely administered as a veterinary medicine, is frequently detected in water. Little is known about the soil-water distribution of lincomycin despite the fact that this is a major determinant of its environmental fate and potential for exposure. Cation exchange was found to be the primary mechanism responsible for lincomycin sorption by soil clay minerals. This was evidenced by pH-dependent sorption, and competition with inorganic cations for sorptive sites. As solution pH increased, lincomycin sorption decreased. The extent of reduction was consistent with the decrease in cationic lincomycin species in solution. The presence of Ca2+ in solution diminished lincomycin sorption. Clay interlayer hydration status strongly influenced lincomycin adsorption. Smectites with the charge deficit from isomorphic substitution in tetrahedral layers (i.e., saponite) manifest a less hydrated interlayer environment resulting in greater sorption than that by octahedrally substituted clays (i.e., montmorillonite). Strongly hydrated exchangeable cations resulted in a more hydrated clay interlayer environment reducing sorption in the order of Ca- < K- < Cs-smectite. X-ray diffraction revealed that lincomycin was intercalated in smectite clay interlayers. Sorption capacity was limited by clay surface area rather than by cation exchange capacity. Smectite interlayer hydration was shown to be a major, yet previously unrecognized, factor influencing the cation exchange process of lincomycin on aluminosilicate mineral surfaces. PMID:19746709

Wang, Cuiping; Ding, Yunjie; Teppen, Brian J; Boyd, Stephen A; Song, Cunyi; Li, Hui

2009-08-15

369

Clay-based polymer nanocomposites: research and commercial development.  

PubMed

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

Zeng, Q H; Yu, A B; Lu, G Q; Paul, D R

2005-10-01

370

Clay particles destabilize engineered nanoparticles in aqueous environments.  

PubMed

Given the ubiquity of natural clay minerals, the most likely interaction of nanoparticles released into an aquatic environment will be with suspended clay minerals. Thus, the transport of engineered nanoparticles in the subsurface and the water column will most likely be altered by their interaction with these minerals. We studied the interactions of two of the most produced nanoparticles, Ag and TiO(2), and montmorillonite to determine how heteroaggregation can alter the stability of nanoparticle/clay mineral mixtures. Since at low pH montmorillonite has a negatively charged basal plane and positively charged edges, its interaction with these nanoparticles at different pH lead to unusual behaviors. There are six different interactions for each clay-nanoparticle pair. At pH values below the IEP of montmorillonite edge site, montmorillonite reduced the stability of both negatively charged Ag and positively charged TiO(2) nanoparticles. Surprisingly this enhanced coagulation only occurs within an intermediate ionic strength range. The spillover of the montmorillonite basal plane electric double layer to the montmorillonite edge may screen the electrostatic attraction between Ag and the montmorillonite edge at low ionic strength, whereas a repulsion between TiO(2) and montmorillonite face sites may restabilize the mixture. PMID:22721423

Zhou, Dongxu; Abdel-Fattah, Amr I; Keller, Arturo A

2012-07-17

371

Modeling the dissolution behavior of standard clays in seawater  

SciTech Connect

The present investigation tests a model to explain the behavior of dissolved Si during early diagenesis in sediments. The model assumes that low-Fe clays and other minerals can be treated simply as Al hydroxides, having attached silica. When the minerals are placed in seawater solutions, Si is released, causing exposure of fresh Al-octahedra, which are reactive toward Si and other elements in solution. Standard clays (kaolinite, montmorillonite) and solid silicic acid were suspended in seawater solutions in various combinations, and dissolved Al, Si, Ca, pH and alkalinity were determined as a function of time. The theoretical model correctly predicts the behavior of Si in mixtures of the different minerals, based upon the dissolution behavior of the minerals in suspension alone. Further, the decrease in the alkalinity of kaolinite-containing seawater solutions, where carbonate dissolution, organic matter decomposition and reduced sulfur oxidation are apparently unimportant, can be predicted from a simple extrapolation of the silica model results. The alkalinity changes observed in this study, as well as the pH changes observed in standard clay suspensions by other researchers, can be explained simply by equilibration of the charge on exposed Al-octahedra with the pH of the surrounding waters. The results of this study indicate that theoretical models of Si diagenesis in sediments should have general usefulness for predicting the effects of clay dissolution on sediment properties.

Mackin, J.E.; Swider, K.T. (State Univ. of New York, Stony Brook (USA))

1987-11-01

372

RANGES OF BOUND WATER PROPERTIES ASSOCIATED WITH A SMECTITE CLAY  

Technology Transfer Automated Retrieval System (TEKTRAN)

Dielectric spectroscopy has been used to characterize various colloids with constant potential surfaces. The objective of this study is to utilize dielectric and electrical conductivity spectroscopy to study a humidified Ca -- Wyoming bentonite, a clay mineral with variable potential surfaces due to...

373

Pyrene photochemical species in commercial clays.  

PubMed

The photochemistry of pyrene, a polycyclic aromatic hydrocarbon, adsorbed on kaolinite, sodium montmorillonite and acid bentonite K10® was investigated to determine how the concentration and structure of the clay minerals affect the formation of different species of pyrene. Fluorescence emission spectra were obtained using reflection geometry for pyrene at the concentrations ranging from 0.5 to 100.0 ?mol g(-1) (pyrene:clay). Two pyrene photochemical species were observed, the monomer, which fluoresces at 396 nm, and its excimer which fluoresces at 470 nm. The formation of excimers occurred first on the kaolinite, due to the smaller surface area. In the acid montmorillonite, the fixed interlamellar space provided greater specific area, leading to lower formation of excimers. Emission from pyrene crystals was also detected for samples with high loadings. PMID:23089391

Teixeira, Silvio Cesar Godinho; Oliveira, Anabela; Duarte, Paulo; Vieira Ferreira, Luis Filipe; Moreira, Josino Costa; Peréz, Daniel Vidal; Marques, Monica Regina da Costa

2013-01-01

374

Dewatering of industrial clay wastes  

SciTech Connect

As a part of research conducted to effect pollution a dewatering technique that allows for disposal of clay wastes, for reuse of water now lost with clays, and for reclamation of mined land was developed. The technique utilizes a high-molecular-weight nonionic polyethylene oxide polymer (PEO) that has the ability to flocculate and dewater materials containing clay wastes. In laboratory experiments, coal-clay waste, potash-clay brine slurry, phosphatic clay waste, uranium tailings, and talc tailings were successfully consolidated. Coal-clay waste was consolidated from 3.6 to 57%; potash-clay brine slurry was consolidated from 3.8 to 35%; phosphatic clay waste from 15.6 to 49%; uranium tailings from 15.4 to 67%; tailings from talc production from 9.7 to 53%; and an acidic TiO/sub 2/ slurr slurry from 1.68 to 30%.

Smelley, A.G.; Scheiner, B.J.; Zatko, J.R.

1980-01-01

375

Mineral of the month: indium  

USGS Publications Warehouse

Indium was discovered in Germany in 1863. Although it is a lustrous silver-white color, the finders named the new material for the “indigo” spectral lines the mineral created on the spectrograph. Indium ranks 61st in abundance in Earth’s crust and is about three times more abundant than silver or mercury.

George, Micheal W.

2004-01-01

376

Mineral Animation  

NSDL National Science Digital Library

This site will help you to learn minerals! This module has two modes: an overview that takes you through some of the fundamentals of minerals and an interactive model that allows you to build your own virtual minerals.

2010-01-01

377

Wellbore instability mechanisms in clays  

E-print Network

This dissertation investigates the stability of wellbores drilled in Ko-consolidated clays using non-linear finite element method (FEM) and effective stress soil models to characterize the behavior of clay and unconsolidated ...

Akl, Sherif Adel

2011-01-01

378

Mineral Surface Directed Membrane Assembly  

NASA Astrophysics Data System (ADS)

The transition from non-living to living matter may have resulted from the self-organizing properties of organic molecules and their interactions with a chemically rich inorganic environment. We have shown that a solution containing RNA, fatty acids and clay produces structures that contain a potentially catalytic surface (clay) and a potential informational biopolymer (RNA) encapsulated within a membrane. This highlights the ability of mineral surfaces to bring together and organize key components of primordial life. We have extended our analysis of mineral-mediated vesicle catalysis to include other natural minerals and synthetic surfaces of varying shape, size, and charge density. Our results show that while RNA polymerization on minerals may be restricted to the surface environment provided by montmorillonite, vesicle formation is enhanced in the presence of disparate types of surfaces. A model is presented in which new sheets of amphiphiles form just proximal to a surface. Similar interactions between amphiphiles and minerals on early Earth may have resulted in the encapsulation of a diverse array of mineral particulates with catalytic properties.

Hanczyc, Martin M.; Mansy, Sheref S.; Szostak, Jack W.

2007-02-01

379

Mineral Source and Transport in Waters of the Gulf of Mexico and Caribbean Sea  

Microsoft Academic Search

Mineral particles suspended in the Gulf of Mexico and Caribbean Sea were analyzed in relation to clay mineral distributions in bottom sediments, to sedimentation processes active in the region, and to the prevailing currents. Circulation in the upper layers of water flowing from the Caribbean, carrying a micaceous-rich mineral assemblage, has exercised an influence on mineral transport into the Gulf

Marian B. Jacobs; Maurice Ewing

1969-01-01

380

Rattles of Clay.  

ERIC Educational Resources Information Center

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)

Banning, Donna

1983-01-01

381

Mineral Precipitation by Epilithic Biofilms in the Speed River, Ontario, Canada  

PubMed Central

Epilithic microbial communities, ubiquitously found in biofilms on submerged granite, limestone, and sandstone, as well as on the concrete support pillars of bridges, were examined in the Speed River, Ontario, Canada. Transmission electron microscopy showed that attached bacteria (on all substrata) were highly mineralized, ranging from Fe-rich capsular material to fine-grained (<1 ?m) authigenic (primary) mineral precipitates. The authigenic grains exhibited a wide range of morphologies, from amorphous gel-like phases to crystalline structures. Energy-dispersive X-ray spectroscopy indicated that the most abundant mineral associated with epilithic bacteria was a complex (Fe, Al) silicate of variable composition. The gel-like phases were similar in composition to a chamositic clay, whereas the crystalline structures were more siliceous and had compositions between those of glauconite and kaolinite. The consistent formation of (Fe, Al) silicates by all bacterial populations, regardless of substratum lithology, implies that biomineralization was a surface process associated with the anionic nature of the cell wall. The adsorption of dissolved constituents from the aqueous environment contributed significantly to the mineral formation process. In this regard, it appears that epilithic microbial biofilms dominate the reactivity of the rock-water interface and may determine the type of minerals formed, which will ultimately become part of the riverbed sediment. Because rivers typically contain high concentrations of dissolved iron, silicon, and aluminum, these findings provide a unique insight into biogeochemical activities that are potentially widespread in natural waters. Images PMID:16349185

Konhauser, K. O.; Schultze-Lam, S.; Ferris, F. G.; Fyfe, W. S.; Longstaffe, F. J.; Beveridge, T. J.

1994-01-01