Influence of Dry Soil on the Ability of Formosan Subterranean Termites, Coptotermes formosanus, to Locate Food Sources

PubMed Central

Cornelius, Mary L.; Osbrink, Weste L.A.

2011-01-01

The effect of barriers of dry soil on the ability of Formosan subterranean termites, Coptotermes formosanus Shiraki (Isoptera: Rhinotermitidae), to construct tunnels and find food was evaluated. Termite movement and wood consumption in a three—chambered apparatus were compared between treatments with dry soil in the center container and treatments where the soil in the center container was moist. When a wood block was located in the release container, termites fed significantly more on that block, regardless of treatment or soil type. In the treatment with dry clay, none of the termites tunneled through the dry clay barrier to reach the distal container. When termites had to tunnel through a barrier of dry sand, topsoil, or clay to reach the sole wood block, there was no effect on wood consumption for the sand treatment, but there was significantly less feeding on wood in the treatments with dry topsoil or clay. When foraging arenas had a section of dry sand in the center, the dry sand significantly reduced tunneling in the distal section after 3 days, but not after 10 days. There was a highly significant effect on the ability of termites to colonize food located in dry sand. Only one feeding station located in dry sand was colonized by termites, compared with 11 feeding stations located in moist sand. PMID:22239343

Clay preference and particle transport behavior of Formosan subterranean termites (Isoptera: Rhinotermitidae): a laboratory study.

PubMed

Wang, Cai; Henderson, Gregg

2014-12-01

Although preference and utilization of clay have been studied in many higher termites, little attention has been paid to lower termites, especially subterranean termites. The Formosan subterranean termite, Coptotermes formosanus Shiraki, can modify its habitat by using clay to fill tree cavities. Here, the biological significance of clay on C. formosanus was investigated. Choice tests showed that significantly more termites aggregated in chambers where clay blocks were provided, regardless of colony group, observation period, or nutritional condition (fed or starved). No-choice tests showed that clay had no observable effect on survivorship, live or dry biomass, water content, and tunneling activity after 33-35 d. However, clay appeared to significantly decrease filter paper consumption (dry weight loss). Active particle (sand, paper, and clay) transport behavior was observed in both choice and no-choice tests. When present, clay was preferentially spread on the substrate, attached to the smooth surfaces of the containers, and used to line sand tunnels. Mechanisms and potential application of clay attraction are discussed. © 2013 Institute of Zoology, Chinese Academy of Sciences.

Field Performance of A Compacted Clay Landfill Final cover At A Humid Site

DOE Office of Scientific and Technical Information (OSTI.GOV)

Albright, William H.; Benson, Craig H.; Gee, Glendon W.

A study was conducted in southern Georgia, USA to evaluate how the hydraulic properties of the compacted clay barrier layer in a landfill final cover changed over a 4-yr service life. The cover was part of a test section constructed in a large drainage lysimeter that allowed CE Database subject headings: landfill, hydrogeology, compacted soils, lysimeters, desiccation continuous monitoring of the water balance. Patterns in the drainage (i.e., flow from the bottom of the cover) record suggest that preferential flow paths developed in the clay barrier soon after construction, apparently in response to desiccation cracking. After four years, the claymore » barrier was excavated and examined for changes in soil structure and hydraulic conductivity. Tests were conducted in situ with a sealed double-ring infiltrometer and two-stage borehole permeameters and in the laboratory on hand-carved blocks taken during construction and after four years of service. The in situ and laboratory tests indicated that the hydraulic conductivity increased approximately three orders of magnitude (from ? 10-7 to ? 10-4 cm s-1) during the service life. A dye tracer test and soil structure analysis showed that extensive cracking and root development occurred throughout the entire depth of the barrier layer. Laboratory tests on undisturbed specimens of the clay barrier indicated that the hydraulic conductivity of damaged clay barriers can be under-estimated significantly if small specimens (e.g., tube samples) are used for hydraulic conductivity assessment. The findings also indicate that clay barriers must be protected from desiccation and root intrusion if they are expected to function as intended, even at sites in warm, humid locations.« less

Permeability and porosity of hydrate-bearing sediments in the northern Gulf of Mexico

DOE Office of Scientific and Technical Information (OSTI.GOV)

Daigle, Hugh; Cook, Ann; Malinverno, Alberto

Hydrate-bearing sands are being actively explored because they contain the highest concentrations of hydrate and are the most economically recoverable hydrate resource. However, relatively little is known about the mechanisms or timescales of hydrate formation, which are related to methane supply, fluid flux, and host sediment properties such as permeability. We used logging-while-drilling data from locations in the northern Gulf of Mexico to develop an effective medium theory-based model for predicting permeability based on clay-sized sediment fraction. The model considers permeability varying between sand and clay endpoint permeabilities that are defined from laboratory data. We verified the model using permeabilitymore » measurements on core samples from three boreholes, and then used the model to predict permeability in two wells drilled in Walker Ridge Block 313 during the Gulf of Mexico Gas Hydrate Joint Industry Project Leg II expedition in 2009. We found that the cleanest sands (clay-sized fraction <0.05) had intrinsic (hydrate-free) permeability contrasts of 5-6 orders of magnitude with the surrounding clays, which is sufficient to provide focused hydrate formation due to advection of methane from a deep source or diffusion of microbial methane from nearby clay layers. In sands where the clay-sized fraction exceeds 0.05, the permeability reduces significantly and focused flow is less pronounced. In these cases, diffusion of dissolved microbial methane is most likely the preferred mode of methane supply for hydrate formation. In conclusion, our results provide important constraints on methane supply mechanisms in the Walker Ridge area and have global implications for evaluating rates of methane migration and hydrate formation in hydrate-bearing sands.« less

Permeability and porosity of hydrate-bearing sediments in the northern Gulf of Mexico

DOE PAGES

Daigle, Hugh; Cook, Ann; Malinverno, Alberto

2015-10-14

Hydrate-bearing sands are being actively explored because they contain the highest concentrations of hydrate and are the most economically recoverable hydrate resource. However, relatively little is known about the mechanisms or timescales of hydrate formation, which are related to methane supply, fluid flux, and host sediment properties such as permeability. We used logging-while-drilling data from locations in the northern Gulf of Mexico to develop an effective medium theory-based model for predicting permeability based on clay-sized sediment fraction. The model considers permeability varying between sand and clay endpoint permeabilities that are defined from laboratory data. We verified the model using permeabilitymore » measurements on core samples from three boreholes, and then used the model to predict permeability in two wells drilled in Walker Ridge Block 313 during the Gulf of Mexico Gas Hydrate Joint Industry Project Leg II expedition in 2009. We found that the cleanest sands (clay-sized fraction <0.05) had intrinsic (hydrate-free) permeability contrasts of 5-6 orders of magnitude with the surrounding clays, which is sufficient to provide focused hydrate formation due to advection of methane from a deep source or diffusion of microbial methane from nearby clay layers. In sands where the clay-sized fraction exceeds 0.05, the permeability reduces significantly and focused flow is less pronounced. In these cases, diffusion of dissolved microbial methane is most likely the preferred mode of methane supply for hydrate formation. In conclusion, our results provide important constraints on methane supply mechanisms in the Walker Ridge area and have global implications for evaluating rates of methane migration and hydrate formation in hydrate-bearing sands.« less

Archeointensity estimates of a tenth-century kiln: first application of the Tsunakawa-Shaw paleointensity method to archeological relics

NASA Astrophysics Data System (ADS)

Kitahara, Yu; Yamamoto, Yuhji; Ohno, Masao; Kuwahara, Yoshihiro; Kameda, Shuichi; Hatakeyama, Tadahiro

2018-05-01

Paleomagnetic information reconstructed from archeological materials can be utilized to estimate the archeological age of excavated relics, in addition to revealing the geomagnetic secular variation and core dynamics. The direction and intensity of the Earth's magnetic field (archeodirection and archeointensity) can be ascertained using different methods, many of which have been proposed over the past decade. Among the new experimental techniques for archeointensity estimates is the Tsunakawa-Shaw method. This study demonstrates the validity of the Tsunakawa-Shaw method to reconstruct archeointensity from samples of baked clay from archeological relics. The validity of the approach was tested by comparison with the IZZI-Thellier method. The intensity values obtained coincided at the standard deviation (1 σ) level. A total of 8 specimens for the Tsunakawa-Shaw method and 16 specimens for the IZZI-Thellier method, from 8 baked clay blocks, collected from the surface of the kiln were used in these experiments. Among them, 8 specimens (for the Tsunakawa-Shaw method) and 3 specimens (for the IZZI-Thellier method) passed a set of strict selection criteria used in the final evaluation of validity. Additionally, we performed rock magnetic experiments, mineral analysis, and paleodirection measurement to evaluate the suitability of the baked clay samples for paleointensity experiments and hence confirmed that the sample properties were ideal for performing paleointensity experiments. It is notable that the newly estimated archaomagnetic intensity values are lower than those in previous studies that used other paleointensity methods for the tenth century in Japan. [Figure not available: see fulltext.

Clays as possible catalysts for peptide formation in the prebiotic era

NASA Technical Reports Server (NTRS)

Paecht-Horowitz, M.

1976-01-01

From the point of view of prebiotic synthesis, clays might have performed functions of concentration, catalysis, and protection of molecules. The degrees of polymerization obtained, when amino acid adenylates are added to montmorillonite suspensions in water, are much higher than those obtained by polymerization in the absence of such a clay. In addition, they are of a discrete spectrum, usually multiples of 6 or 7, and reach values of up to 40 mers. In the absence of clay a continuous spectrum of degrees of polymerization is obtained, and usually up to 4-6 mers only. Copolymerization in the absence of clays yields mostly random copolymers, in their presence mostly block copolymers are obtained. Optical density measurements show that after adsorption has taken place on the clay, stacking of its layers occurs. Polymerization starts only after these stacked layers have been formed

Impact of Oriented Clay Particles on X-Ray Spectroscopy Analysis

NASA Astrophysics Data System (ADS)

Lim, A. J. M. S.; Syazwani, R. N.; Wijeyesekera, D. C.

2016-07-01

Understanding the engineering properties of the mineralogy and microfabic of clayey soils is very complex and thus very difficult for soil characterization. Micromechanics of soils recognize that the micro structure and mineralogy of clay have a significant influence on its engineering behaviour. To achieve a more reliable quantitative evaluation of clay mineralogy, a proper sample preparation technique for quantitative clay mineral analysis is necessary. This paper presents the quantitative evaluation of elemental analysis and chemical characterization of oriented and random oriented clay particles using X-ray spectroscopy. Three different types of clays namely marine clay, bentonite and kaolin clay were studied. The oriented samples were prepared by placing the dispersed clay in water and left to settle on porous ceramic tiles by applying a relatively weak suction through a vacuum pump. Images form a Scanning Electron Microscope (SEM) was also used to show the comparison between the orientation patterns of both the sample preparation techniques. From the quantitative analysis of the X-ray spectroscopy, oriented sampling method showed more accuracy in identifying mineral deposits, because it produced better peak intensity on the spectrum and more mineral content can be identified compared to randomly oriented samples.

Evaluation of the release of dioxins and PCBs during kiln-firing of ball clay.

PubMed

Broadwater, Kendra; Meeker, John D; Luksemburg, William; Maier, Martha; Garabrant, David; Demond, Avery; Franzblau, Alfred

2014-01-01

Ball clay is known to be naturally contaminated with high levels of polychlorinated di-benzo-p-dioxins (PCDDs). This study evaluated the potential for PCDD, polychlorinated dibenzofuran (PCDF) and polychlorinated biphenyl (PCB) release during the kiln firing of ball clay in an art studio. Toxic equivalence (TEQ) were calculated using World Health Organization (WHO) 2005 toxic equivalence factors (TEF) and congener concentrations. Ten bags of commercial ball clay were found to have an average TEQ of 1,370 nanograms/kilogram (ng kg(-1)) dry weight (dw), almost exclusively due to PCDDs (99.98% of TEQ). After firing, none of the 29 dioxin-like analytes was measured above the limits of detection (LOD) in the clay samples. Air samples were taken during firings using both low-flow and high-flow air samplers. Few low-flow air samples contained measurable levels of dioxin congeners above the LOD. The mean TEQ in the high volume air samples ranged from 0.07 pg m(-3) to 0.21 pg m(-3) when firing ball clay, and was 0.11 pg m(-3) when no clay was fired. These concentrations are within the range measured in typical residences and well-controlled industrial settings. The congener profiles in the high-flow air samples differed from the unfired clay; the air samples had a considerable contribution to the TEQ from PCDFs and PCBs. Given that the TEQs of all air samples were very low and the profiles differed from the unfired clay, it is likely that the PCDDs in dry ball clay were destroyed during kiln firing. These results suggest that inhalation of volatilized dioxins during kiln firing of dry ball clay is an unlikely source of exposure for vocational and art ceramicists. Copyright © 2013 Elsevier Ltd. All rights reserved.

The Magnet Cove Rutile Company mine, Hot Spring County, Arkansas

USGS Publications Warehouse

Kinney, Douglas M.

1949-01-01

The Magnet Cove Rutile Company mine was mapped by the U.S. Geological Survey in November 1944. The pits are on the northern edge of Magnet Cove and have been excavated in the oxidized zone of highly weathered and altered volcanic agglomerate. The agglomerate is composed of altered mafic igneous rocks in a matrix of white to gray clay, a highly altered tuff. The agglomerate appears layered and is composed of tuffaceous clay material below and igneous blocks above. The agglomerate is cut by aplite and lamprophyre dikes. Alkalic syenite dikes crop out on the ridge north of the pits. At the present stage of mine development the rutile seems to be concentrated in a narrow zone beneath the igneous blocks of the agglomerate. Rutile, associated with calcite and pyrite, occurs as disseminated acicular crystals and discontinuous vein-like masses in the altered tuff. Thin veins of rutile locally penetrate the mafic igneous blocks of the agglomerate.

Application of Nucleic Acid-Based Tools for Monitoring Monitored Natural Attenuation (MNA), Biostimulation and Bioaugmentation at Chlorinated Solvent Sites

DTIC Science & Technology

2011-02-01

TABLE OF CONTENTS TABLE OF CONTENTS ............................................................................................................... ii...gallons. In 1978, the lagoons were emptied by pumping the contents into the A-Block Lagoon (SWMU 22), a ESTCP ER-0518 Final Report 25...feet bgs, but deeper at some locations, the clay content increased significantly. In approximately 20 to 30 feet above bedrock, sandy clay and clayey

Quality evaluation of processed clay soil samples.

PubMed

Steiner-Asiedu, Matilda; Harrison, Obed Akwaa; Vuvor, Frederick; Tano-Debrah, Kwaku

2016-01-01

This study assessed the microbial quality of clay samples sold on two of the major Ghanaian markets. The study was a cross-sectional assessing the evaluation of processed clay and effects it has on the nutrition of the consumers in the political capital town of Ghana. The items for the examination was processed clay soil samples. Staphylococcus spp and fecal coliforms including Klebsiella, Escherichia, and Shigella and Enterobacterspp were isolated from the clay samples. Samples from the Kaneshie market in Accra recorded the highest total viable counts 6.5 Log cfu/g and Staphylococcal count 5.8 Log cfu/g. For fecal coliforms, Madina market samples had the highest count 6.5 Log cfu/g and also recorded the highest levels of yeast and mould. For Koforidua, total viable count was highest in the samples from the Zongo market 6.3 Log cfu/g. Central market samples had the highest count of fecal coliforms 4.6 Log cfu/g and yeasts and moulds 6.5 Log cfu/g. "Small" market recorded the highest staphylococcal count 6.2 Log cfu/g. The water activity of the clay samples were low, and ranged between 0.65±0.01 and 0.66±0.00 for samples collected from Koforidua and Accra respectively. The clay samples were found to contain Klebsiella spp. Escherichia, Enterobacter, Shigella spp. staphylococcus spp., yeast and mould. These have health implications when consumed.

Preparation and Characterization of Natural Rubber/Organophilic Clay Nanocomposites

NASA Astrophysics Data System (ADS)

Gonzales-Fernandes, M.; Esper, F. J.; Silva-Valenzuela, M. G.; Martín-Cortés, G. R.; Valenzuela-Diaz, F. R.; Wiebeck, H.

Natural rubber/organophilic clay nanocomposites were prepared and characterized. A brown bentonite from Paraiba's State, Brazil was modified with a sodium salt and treated with quaternary ammonium salt hexadecyltrimethyl ammonium chloride. The clay in its natural state, after cation exchange with sodium and after organophilization was characterized by XRD, IR, SEM, thermal analysis. Nanocomposite samples were prepared containing 10 resin percent of organophilic clay. The vulcanized samples were analyzed by XRD, SEM. The nanocomposites obtained showed improvement in their mechanical properties in comparison with samples without clay.

Geotechnical characterization of mined clay from Appalachian Ohio: challenges and implications for the clay mining industry.

PubMed

Moran, Anthony R; Hettiarachchi, Hiroshan

2011-07-01

Clayey soil found in coal mines in Appalachian Ohio is often sold to landfills for constructing Recompacted Soil Liners (RSL) in landfills. Since clayey soils possess low hydraulic conductivity, the suitability of mined clay for RSL in Ohio is first assessed by determining its clay content. When soil samples are tested in a laboratory, the same engineering properties are typically expected for the soils originated from the same source, provided that the testing techniques applied are standard, but mined clay from Appalachian Ohio has shown drastic differences in particle size distribution depending on the sampling and/or laboratory processing methods. Sometimes more than a 10 percent decrease in the clay content is observed in the samples collected at the stockpiles, compared to those collected through reverse circulation drilling. This discrepancy poses a challenge to geotechnical engineers who work on the prequalification process of RSL material as it can result in misleading estimates of the hydraulic conductivity of the samples. This paper describes a laboratory investigation conducted on mined clay from Appalachian Ohio to determine how and why the standard sampling and/or processing methods can affect the grain-size distributions. The variation in the clay content was determined to be due to heavy concentrations of shale fragments in the clayey soils. It was also concluded that, in order to obtain reliable grain size distributions from the samples collected at a stockpile of mined clay, the material needs to be processed using a soil grinder. Otherwise, the samples should be collected through drilling.

Geotechnical Characterization of Mined Clay from Appalachian Ohio: Challenges and Implications for the Clay Mining Industry

PubMed Central

Moran, Anthony R.; Hettiarachchi, Hiroshan

2011-01-01

Clayey soil found in coal mines in Appalachian Ohio is often sold to landfills for constructing Recompacted Soil Liners (RSL) in landfills. Since clayey soils possess low hydraulic conductivity, the suitability of mined clay for RSL in Ohio is first assessed by determining its clay content. When soil samples are tested in a laboratory, the same engineering properties are typically expected for the soils originated from the same source, provided that the testing techniques applied are standard, but mined clay from Appalachian Ohio has shown drastic differences in particle size distribution depending on the sampling and/or laboratory processing methods. Sometimes more than a 10 percent decrease in the clay content is observed in the samples collected at the stockpiles, compared to those collected through reverse circulation drilling. This discrepancy poses a challenge to geotechnical engineers who work on the prequalification process of RSL material as it can result in misleading estimates of the hydraulic conductivity of the samples. This paper describes a laboratory investigation conducted on mined clay from Appalachian Ohio to determine how and why the standard sampling and/or processing methods can affect the grain-size distributions. The variation in the clay content was determined to be due to heavy concentrations of shale fragments in the clayey soils. It was also concluded that, in order to obtain reliable grain size distributions from the samples collected at a stockpile of mined clay, the material needs to be processed using a soil grinder. Otherwise, the samples should be collected through drilling. PMID:21845150

Shear Strength of Remoulding Clay Samples Using Different Methods of Moulding

NASA Astrophysics Data System (ADS)

Norhaliza, W.; Ismail, B.; Azhar, A. T. S.; Nurul, N. J.

2016-07-01

Shear strength for clay soil was required to determine the soil stability. Clay was known as a soil with complex natural formations and very difficult to obtain undisturbed samples at the site. The aim of this paper was to determine the unconfined shear strength of remoulded clay on different methods in moulding samples which were proctor compaction, hand operated soil compacter and miniature mould methods. All the samples were remoulded with the same optimum moisture content (OMC) and density that were 18% and 1880 kg/m3 respectively. The unconfined shear strength results of remoulding clay soils for proctor compaction method was 289.56kPa with the strain 4.8%, hand operated method was 261.66kPa with the strain 4.4% and miniature mould method was 247.52kPa with the strain 3.9%. Based on the proctor compaction method, the reduction percentage of unconfined shear strength of remoulded clay soil of hand operated method was 9.66%, and for miniature mould method was 14.52%. Thus, because there was no significant difference of reduction percentage of unconfined shear strength between three different methods, so it can be concluded that remoulding clay by hand operated method and miniature mould method were accepted and suggested to perform remoulding clay samples by other future researcher. However for comparison, the hand operated method was more suitable to form remoulded clay sample in term of easiness, saving time and less energy for unconfined shear strength determination purposes.

Quality evaluation of processed clay soil samples

PubMed Central

Steiner-Asiedu, Matilda; Harrison, Obed Akwaa; Vuvor, Frederick; Tano-Debrah, Kwaku

2016-01-01

Introduction This study assessed the microbial quality of clay samples sold on two of the major Ghanaian markets. Methods The study was a cross-sectional assessing the evaluation of processed clay and effects it has on the nutrition of the consumers in the political capital town of Ghana. The items for the examination was processed clay soil samples. Results Staphylococcus spp and fecal coliforms including Klebsiella, Escherichia, and Shigella and Enterobacterspp were isolated from the clay samples. Samples from the Kaneshie market in Accra recorded the highest total viable counts 6.5 Log cfu/g and Staphylococcal count 5.8 Log cfu/g. For fecal coliforms, Madina market samples had the highest count 6.5 Log cfu/g and also recorded the highest levels of yeast and mould. For Koforidua, total viable count was highest in the samples from the Zongo market 6.3 Log cfu/g. Central market samples had the highest count of fecal coliforms 4.6 Log cfu/g and yeasts and moulds 6.5 Log cfu/g. “Small” market recorded the highest staphylococcal count 6.2 Log cfu/g. The water activity of the clay samples were low, and ranged between 0.65±0.01 and 0.66±0.00 for samples collected from Koforidua and Accra respectively. Conclusion The clay samples were found to contain Klebsiella spp. Escherichia, Enterobacter, Shigella spp. staphylococcus spp., yeast and mould. These have health implications when consumed. PMID:27642456

New polyelectrolyte complex from pectin/chitosan and montmorillonite clay.

PubMed

da Costa, Marcia Parente Melo; de Mello Ferreira, Ivana Lourenço; de Macedo Cruz, Mauricio Tavares

2016-08-01

A new nanocomposite hydrogel was prepared by forming a crosslinked hybrid polymer network based on chitosan and pectin in the presence of montmorillonite clay. The influence of clay concentration (0.5 and 2% wt) as well as polymer ratios (1:1, 1:2 and 2:1) was investigated carefully. The samples were characterized by different techniques: transmission and scanning electron microscopy, X-ray diffraction, thermogravimetric analysis, infrared spectroscopy, swelling degree and compression test. Most samples presented swelling degree above 1000%, which permits characterizing them as superabsorbent material. Images obtained by transmission electron microscopy showed the presence of clay nanoparticles into hydrogel. The hydrogels' morphological properties were evaluated by scanning electron microscope in high and low-vacuum. The micrographs showed that the samples presented porous. The incorporation of clay produced hydrogels with differentiated morphology. Thermogravimetric analysis results revealed that the incorporation of clay in the samples provided greater thermal stability to the hydrogels. The compression resistance also increased with addition of clay. Copyright © 2016 Elsevier Ltd. All rights reserved.

Burnt clay magnetic properties and palaeointensity determination

NASA Astrophysics Data System (ADS)

Avramova, Mariya; Lesigyarski, Deyan

2014-05-01

Burnt clay structures found in situ are the most valuable materials for archaeomagnetic studies. From these materials the full geomagnetic field vector described by inclination, declination and intensity can be retrieved. The reliability of the obtained directional results is related to the precision of samples orientation and the accuracy of characteristic remanence determination. Palaeointensity evaluations depend on much more complex factors - stability of carried remanent magnetization, grain-size distribution of magnetic particles and mineralogical transformations during heating. In the last decades many efforts have been made to shed light over the reasons for the bad success rate of palaeointensity experiments. Nevertheless, sometimes the explanation of the bad archaeointensity results with the magnetic properties of the studied materials is quite unsatisfactory. In order to show how difficult is to apply a priory strict criteria for the suitability of a given collection of archaeomagnetic materials, artificial samples formed from four different baked clays are examined. Two of the examined clay types were taken from clay deposits from different parts of Bulgaria and two clays were taken from ancient archaeological baked clay structures from the Central part of Bulgaria and the Black sea coast, respectively. The samples formed from these clays were repeatedly heated in known magnetic field to 700oC. Different analyses were performed to obtain information about the mineralogical content and magnetic properties of the samples. The obtained results point that all clays reached stable magnetic mineralogy after the repeated heating to 700oC, the main magnetic mineral is of titano/magnetite type and the magnetic particles are predominantly with pseudo single domain grain sizes. In spite that, the magnetic properies of the studied clays seem to be very similar, reliable palaeointensity results were obtained only from the clays coming from clay deposits. The palaeointensity experiments for the samples formed from the ancient baked clays completely failed to give relibable results.

In situ synthesis, characterization, and catalytic performance of tungstophosphoric acid encapsulated into the framework of mesoporous silica pillared clay.

PubMed

Li, Baoshan; Liu, Zhenxing; Han, Chunying; Ma, Wei; Zhao, Songjie

2012-07-01

Mesoporous silica pillared clay (SPC) incorporated with tungstophosphoric acid (HPW) has been synthesized via in situ introducing P and W source in the acidic suspension of the clay interlayer template during the formation of the silica pillared clay. The samples were characterized by XRD, XRF, FT-IR, TG-DTA, N(2) adsorption-desorption, and SEM techniques. The results showed that the HPW formed by in situ method has been effectively introduced into the framework of mesoporous silica pillared clay and its Keggin structure remained perfectly after formation of the materials. In addition, samples with similar HPW loadings were also prepared by impregnation method using SPC as the support. HPW in the incorporated samples was better dispersed into the silica pillared clay than in the impregnated samples. The results of catalytic tests indicated that the encapsulated materials demonstrated better catalytic performance than the impregnated samples in oxidative desulfurization (ODS) of dibenzothiophene (DBT). Copyright © 2012 Elsevier Inc. All rights reserved.

Clay Mineral Crystal Structure Tied to Composition

NASA Image and Video Library

2016-12-13

This diagram illustrates how the dimensions of clay minerals' crystal structure are affected by which ions are present in the composition of the mineral. Different clay minerals were identified this way at two sites in Mars' Gale Crater: "Murray Buttes" and "Yellowknife Bay." In otherwise identical clay minerals, a composition that includes aluminum and ferric iron ions (red dots) results in slightly smaller crystalline unit cells than one that instead includes magnesium and ferrous iron ions (green dots). Ferric iron is more highly oxidized than ferrous iron. Crystalline cell units are the basic repeating building blocks that define minerals. X-ray diffraction analysis, a capability of the Chemistry and Mineralogy (CheMin) instrument on NASA's Curiosity Mars rover, identifies minerals from their crystalline structure. http://photojournal.jpl.nasa.gov/catalog/PIA21148

Investigating the Influence of Clay Mineralogy on Stream Bank Erodibility

NASA Astrophysics Data System (ADS)

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

2005-12-01

Soil scientists concerned with erosion of agricultural fields and geotechnical engineers concerned with the mechanical behavior of soils under different conditions have both examined the role of clay mineralogy in controlling soil/sediment properties. Fluvial geomorphologists studying stream channel erosion and stability have focused more on the effects of particle-size distribution, vegetation and rooting. The clay mineralogy of bed and bank sediment has the potential to influence cohesiveness and erodibility, however. The goal of this study is to determine the influence of clay mineralogy on the erodibility of natural stream bank sediment, utilizing techniques drawn from pedology and soil mechanics. Bank samples were collected from eleven sites in small watersheds in central and western Virginia. To obtain sediment containing a range of different clay minerals, watersheds with different types of bedrock were chosen for sampling. Rock types included mafic to felsic metamorphic and igneous rocks, shale, sandstone, and limestone. Where stream bank materials were clearly stratified, different layers were sampled separately. X-ray diffraction of the clay-fraction of the sediment indicates the presence of kaolinite, illite, vermiculite, and mixed-layer clay minerals in various abundances in the different samples. Clay content is 9-46%, as determined by the hydrometer method, and textures range from silty clay and silt loam to clay loam and sandy loam. Organic mater contents range from 1-5% by the loss-on-ignition method. Bulk density of intact sediment samples averages 1.5 g/cc. Liquid limits range from 23-41 with one sample having a value of 65; plasticity indices range from 15-22. While these tests predict that the samples would show a range of mechanical behaviors, the channel morphology at the sampling sites was not strikingly different, all having steep cut banks eroded primarily by scour with no evidence of mass movement and most having a width/depth ratio around 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.

Composition, Alteration, and Texture of Fault-Related Rocks from Safod Core and Surface Outcrop Analogs: Evidence for Deformation Processes and Fluid-Rock Interactions

NASA Astrophysics Data System (ADS)

Bradbury, Kelly K.; Davis, Colter R.; Shervais, John W.; Janecke, Susanne U.; Evans, James P.

2015-05-01

We examine the fine-scale variations in mineralogical composition, geochemical alteration, and texture of the fault-related rocks from the Phase 3 whole-rock core sampled between 3,187.4 and 3,301.4 m measured depth within the San Andreas Fault Observatory at Depth (SAFOD) borehole near Parkfield, California. This work provides insight into the physical and chemical properties, structural architecture, and fluid-rock interactions associated with the actively deforming traces of the San Andreas Fault zone at depth. Exhumed outcrops within the SAF system comprised of serpentinite-bearing protolith are examined for comparison at San Simeon, Goat Rock State Park, and Nelson Creek, California. In the Phase 3 SAFOD drillcore samples, the fault-related rocks consist of multiple juxtaposed lenses of sheared, foliated siltstone and shale with block-in-matrix fabric, black cataclasite to ultracataclasite, and sheared serpentinite-bearing, finely foliated fault gouge. Meters-wide zones of sheared rock and fault gouge correlate to the sites of active borehole casing deformation and are characterized by scaly clay fabric with multiple discrete slip surfaces or anastomosing shear zones that surround conglobulated or rounded clasts of compacted clay and/or serpentinite. The fine gouge matrix is composed of Mg-rich clays and serpentine minerals (saponite ± palygorskite, and lizardite ± chrysotile). Whole-rock geochemistry data show increases in Fe-, Mg-, Ni-, and Cr-oxides and hydroxides, Fe-sulfides, and C-rich material, with a total organic content of >1 % locally in the fault-related rocks. The faults sampled in the field are composed of meters-thick zones of cohesive to non-cohesive, serpentinite-bearing foliated clay gouge and black fine-grained fault rock derived from sheared Franciscan Formation or serpentinized Coast Range Ophiolite. X-ray diffraction of outcrop samples shows that the foliated clay gouge is composed primarily of saponite and serpentinite, with localized increases in Ni- and Cr-oxides and C-rich material over several meters. Mesoscopic and microscopic textures and deformation mechanisms interpreted from the outcrop sites are remarkably similar to those observed in the SAFOD core. Micro-scale to meso-scale fabrics observed in the SAFOD core exhibit textural characteristics that are common in deformed serpentinites and are often attributed to aseismic deformation with episodic seismic slip. The mineralogy and whole-rock geochemistry results indicate that the fault zone experienced transient fluid-rock interactions with fluids of varying chemical composition, including evidence for highly reducing, hydrocarbon-bearing fluids.

Strength of Wet and Dry Montmorillonite

NASA Astrophysics Data System (ADS)

Morrow, C. A.; Lockner, D. A.; Moore, D. E.

2015-12-01

Montmorillonite, an expandable smectite clay, is a common mineral in fault zones to a depth of around 3 km. Its low strength relative to other common fault gouge minerals is important in many models of fault rheology. However, the coefficient of friction is not well constrained in the literature due to the difficulty of establishing fully drained or fully dried states in the laboratory. For instance, in some reported studies, samples were either partially saturated or possibly over pressured, leading to wide variability in reported shear strength. In this study, the coefficient of friction, μ, of both saturated and oven-dried (at 150°C) Na-montmorillonite was measured at normal stresses up to 680 MPa at room temperature and shortening rates from 1.0 to 0.01 μm/s. Care was taken to shear saturated samples slowly enough to avoid pore fluid overpressure in the clay layers. Coefficients of friction are reported after 8 mm of axial displacement in a triaxial apparatus on saw-cut samples containing a layer of montmorillonite gouge, with either granite or sandstone driving blocks. For saturated samples, μ increased from around 0.1 at low pressure to 0.25 at the highest test pressures. In contrast, values for oven-dried samples decreased asymptotically from approximately 0.78 at 10 MPa normal stress to around 0.45 at 400-680 MPa. While wet and dry strengths approached each other with increasing effective normal stress, wet strength remained only about half of the dry strength at 600 MPa effective normal stress. The increased coefficient of friction can be correlated with a reduction in the number of loosely bound lubricating surface water layers on the clay platelets due to applied normal stress under saturated conditions. The steady-state rate dependence of friction, a-b, was positive and dependent on normal stress. For saturated samples, a-b increased linearly with applied normal stress from ~0 to 0.004, while for dry samples a-b decreased with increasing normal stress from 0.008 to 0.002. All values were either neutral or rate strengthening, indicating a tendency for stable sliding.

Polyethylene organo-clay nanocomposites: the role of the interface chemistry on the extent of clay intercalation/exfoliation.

PubMed

Mainil, Michaël; Alexandre, Michaël; Monteverde, Fabien; Dubois, Philippe

2006-02-01

High density polyethylene (HDPE)/clay nanocomposites have been prepared using three different functionalized polyethylene compatibilizers: an ethylene/vinyl acetate copolymer, a polyethylene grafted with maleic anhydride functions and a (styrene-b-ethylene/butylene-b-styrene) block copolymer. The nanocomposites were prepared via two different routes: (1) the dispersion in HDPE of a masterbatch prepared from the compatibilizer and the clay or (2) the direct melt blending of the three components. For each compatibilizer, essentially intercalated nanocomposites were formed as determined by X-ray diffraction and transmission electron microscopy. With the ethylene/vinyl acetate copolymer, a significant delamination of the intercalated clay in thin stacks was observed. This dispersion of thin intercalated stacks within the polymer matrix allowed increasing significantly the stiffness and the flame resistance of the nanocomposite. A positive effect of shear rate and blending time has also been put into evidence, especially for the process based on the masterbatch preparation, improving both the formation of thin stacks of intercalated clay and the mechanical properties and the flame resistance of the formed nanocomposites.

Clay-mineral assemblages from some levels of K-118 drill core of Maha Sarakham evaporites, northeastern Thailand

NASA Astrophysics Data System (ADS)

Suwanich, Parkorn

Clay-mineral assemblages in Middle Clastic, Middle Salt, Lower Clastic, Potash Zone, and Lower Salt, totalling 13 samples from K-118 drill core, in the Maha Sarakham Formation, Khorat Basin, northeastern Thailand were studied. The clay-size particles were separated from the water-soluble salt by water leaching. Then the samples were leached again in the EDTA solution and separated into clay-size particles by using the timing sedimentation. The EDTA-clay residues were divided and analyzed by using the XRD and XRF method. The XRD peaks show that the major-clay minerals are chlorite, illite, and mixed-layer corrensite including traces of rectorite? and paragonite? The other clay-size particles are quartz and potassium feldspar. The XRF results indicate Mg-rich values and moderate MgAl atom ratio values in those clay minerals. The variable Fe, Na, and K contents in the clay-mineral assemblages can explain the environment of deposition compared to the positions of the samples from the core. Hypothetically, mineralogy and the chemistry of the residual assemblages strongly indicate that severe alteration and Mg-enrichment of normal clay detritus occurred in the evaporite environment through brine-sediment interaction. The various Mg-enrichment varies along the various members reflecting whether sedimentation is near or far from the hypersaline brine.

Clay Chemistry's Influence on the Average Carbon Content and Particle Size at the Ninety-Six Historical Site, South Carolina

NASA Astrophysics Data System (ADS)

Lintz, L.; Werts, S. P.

2014-12-01

The Ninety-Six National Historic Site is located in Greenwood County, SC. Recent geologic mapping of this area has revealed differences in soil properties over short distances within the park. We studied the chemistry of the clay minerals found within the soils to see if there was a correlation between the amounts of soil organic carbon contained in the soil and particle size in individual soil horizons. Three different vegetation areas, including an old field, a deciduous forest, and a pine forest were selected to see what influence vegetation type had on the clay chemistry and carbon levels as well. Four samples containing the O, A, and B horizons were taken from each location and we studied the carbon and nitrogen content using an elemental analyzer, particle size using a Laser Diffraction Particle Size Analyzer, and clay mineralogy with powder X-ray diffraction of each soil sample. Samples from the old field and pine forest gave an overall negative correlation between carbon content and clay percentage, which is against the normal trend for Southern Piedmont Ultisols. The deciduous forest samples gave no correlation at all between its carbon content and clay percentage. Together, all three locations show the same negative relationship, while once separated into vegetation type and A and B horizons it shows even more abnormal relationships of negative while several show no correlation (R2= 0.007403- 0.56268). Using powder XRD, we ran clay samples from each A and B horizon for the clay mineralogy. All three vegetation areas had the same results of containing quartz, kaolinite, and Fe oxides, therefore, clay chemistry is not a reason behind the abnormal trend of a negative correlation between average carbon content and clay percentage. Considering that all three locations have the same climate, topography, and parent material of metagranite, it could be reasonable to assume these results are a factor of environmental and biological influences rather than clay type.

Transport and retention of surfactant- and polymer-stabilized engineered silver nanoparticles in silicate-dominated aquifer material.

PubMed

Adrian, Yorck F; Schneidewind, Uwe; Bradford, Scott A; Simunek, Jirka; Fernandez-Steeger, Tomas M; Azzam, Rafig

2018-05-01

Packed column experiments were conducted to investigate the transport and blocking behavior of surfactant- and polymer-stabilized engineered silver nanoparticles (Ag-ENPs) in saturated natural aquifer media with varying content of material < 0.063 mm in diameter (silt and clay fraction), background solution chemistry, and flow velocity. Breakthrough curves for Ag-ENPs exhibited blocking behavior that frequently produced a delay in arrival time in comparison to a conservative tracer that was dependent on the physicochemical conditions, and then a rapid increase in the effluent concentration of Ag-ENPs. This breakthrough behavior was accurately described using one or two irreversible retention sites that accounted for Langmuirian blocking on one site. Simulated values for the total retention rate coefficient and the maximum solid phase concentration of Ag-ENPs increased with increasing solution ionic strength, cation valence, clay and silt content, decreasing flow velocity, and for polymer-instead of surfactant-stabilized Ag-ENPs. Increased Ag-ENP retention with ionic strength occurred because of compression of the double layer and lower magnitudes in the zeta potential, whereas lower velocities increased the residence time and decreased the hydrodynamics forces. Enhanced Ag-ENP interactions with cation valence and clay were attributed to the creation of cation bridging in the presence of Ca 2+ . The delay in breakthrough was always more pronounced for polymer-than surfactant-stabilized Ag-ENPs, because of differences in the properties of the stabilizing agents and the magnitude of their zeta-potential was lower. Our results clearly indicate that the long-term transport behavior of Ag-ENPs in natural, silicate dominated aquifer material will be strongly dependent on blocking behavior that changes with the physicochemical conditions and enhanced Ag-ENP transport may occur when retention sites are filled. Copyright © 2018 Elsevier Ltd. All rights reserved.

Correlation between thermal behavior of clays and their chemical and mineralogical composition: a review

NASA Astrophysics Data System (ADS)

Dwi Yanti, Evi; Pratiwi, I.

2018-02-01

Clay's abundance has been widely used as industrial raw materials, especially ceramic and tile industries. Utilization of these minerals needs a thermal process for producing ceramic products. Two studies conducted by Septawander et al. and Chin C et al., showed the relationship between thermal behavior of clays and their chemical and mineralogical composition. Clays are characterized by XRD analysis and thermal analysis, ranging from 1100°C to 1200°C room temperature. Specimen of raw materials of clay which is used for the thermal treatment is taken from different geological conditions and formation. In raw material, Quartz is almost present in all samples. Halloysite, montmorillonite, and feldspar are present in Tanjung Morawa raw clay. KC and MC similar kaolinite and illite are present in the samples. The research illustrates the interrelationships of clay minerals and chemical composition with their heat behavior. As the temperature of combustion increases, the sample reduces a significant weight. The minerals which have undergone a transformation phase became mullite, cristobalite or illite and quartz. Under SEM analysis, the microstructures of the samples showed irregularity in shape; changes occurred due the increase of heat.

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

USGS Publications Warehouse

Pollastro, R.M.

1982-01-01

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

Natural Radioactivity of Boron Added Clay Samples

NASA Astrophysics Data System (ADS)

Akkurt, I.; ćanakciı, H.; Mavi, B.; Günoǧlu, K.

2011-12-01

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

Effects of rock mineralogy and pore structure on stress-dependent permeability of shale samples

PubMed Central

Al Ismail, Maytham I.; Zoback, Mark D.

2016-01-01

We conducted pulse-decay permeability experiments on Utica and Permian shale samples to investigate the effect of rock mineralogy and pore structure on the transport mechanisms using a non-adsorbing gas (argon). The mineralogy of the shale samples varied from clay rich to calcite rich (i.e. clay poor). Our permeability measurements and scanning electron microscopy images revealed that the permeability of the shale samples whose pores resided in the kerogen positively correlated with organic content. Our results showed that the absolute value of permeability was not affected by the mineral composition of the shale samples. Additionally, our results indicated that clay content played a significant role in the stress-dependent permeability. For clay-rich samples, we observed higher pore throat compressibility, which led to higher permeability reduction at increasing effective stress than with calcite-rich samples. Our findings highlight the importance of considering permeability to be stress dependent to achieve more accurate reservoir simulations especially for clay-rich shale reservoirs. This article is part of the themed issue ‘Energy and the subsurface’. PMID:27597792

Soil forensics: How far can soil clay analysis distinguish between soil vestiges?

PubMed

Corrêa, R S; Melo, V F; Abreu, G G F; Sousa, M H; Chaker, J A; Gomes, J A

2018-03-01

Soil traces are useful as forensic evidences because they frequently adhere to individuals and objects associated with crimes and can place or discard a suspect at/from a crime scene. Soil is a mixture of organic and inorganic components and among them soil clay contains signatures that make it reliable as forensic evidence. In this study, we hypothesized that soils can be forensically distinguished through the analysis of their clay fraction alone, and that samples of the same soil type can be consistently distinguished according to the distance they were collected from each other. To test these hypotheses 16 Oxisol samples were collected at distances of between 2m and 1.000m, and 16 Inceptisol samples were collected at distances of between 2m and 300m from each other. Clay fractions were extracted from soil samples and analyzed for hyperspectral color reflectance (HSI), X-ray diffraction crystallographic (XRD), and for contents of iron oxides, kaolinite and gibbsite. The dataset was submitted to multivariate analysis and results were from 65% to 100% effective to distinguish between samples from the two soil types. Both soil types could be consistently distinguished for forensic purposes according to the distance that samples were collected from each other: 1000m for Oxisol and 10m for Inceptisol. Clay color and XRD analysis were the most effective techniques to distinguish clay samples, and Inceptisol samples were more easily distinguished than Oxisol samples. Soil forensics seems a promising field for soil scientists as soil clay can be useful as forensic evidence by using routine analytical techniques from soil science. Copyright © 2017 The Chartered Society of Forensic Sciences. Published by Elsevier B.V. All rights reserved.

Natural Radioactivity of Boron Added Clay Samples

DOE Office of Scientific and Technical Information (OSTI.GOV)

Akkurt, I.; Guenoglu, K.; Canakcii, H.

2011-12-26

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

Characterization of clay scales forming in Philippine geothermal wells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Reyes, A.G.; Cardile, C.M.

1989-01-01

Smectite scales occur in 24 out of the 36 blocked wells located in Tongonan, Palinpinon and Bacon-Manito. These comprise 2-85% of the well scales and form at depths of 33-2620 m, where measured and fluid inclusion temperatures are 40-320{sup 0}C. Most, however, occur below the production casing show where temperatures are {ge}230{sup 0}C, often at depths coinciding with aquifers. The clay scales are compositionally and structurally different from the bentonite used in drilling, which is essentially sodium-rich montmorillonite. The clay deposits are expanding, generally disordered, and combine the characteristics of a montmorillonite, saponite and vermiculite in terms of reaction tomore » cationic exchange treatments, structure and composition. Six types of clay scales are identified, but the predominant one, comprising 60-100% of the clay deposits in a well, is Mg- and Fe-rich and referred to as a vermiculitic species. The crystallinity, degree of disorder, textures, optical characteristics, structure and relative amounts of structural Al, Mg and Fe vary with time, temperature and fluid composition, but not with depth and measured pressure. Despite its variance from bentonite characteristics, one of the dominant suggested mechanisms of clay scale formation uses the drilling mud in the well as a substrate, from which the Mg- and Fe-rich clay evolves.« less

Observations on Cretaceous abyssal hills in the northeast Pacific

USGS Publications Warehouse

Eittreim, S.L.; Piper, D.Z.; Chezar, H.; Jones, D.R.; Kaneps, A.

1984-01-01

An abyssal hills area of 50 ?? 60 km in the northeast Pacific was studied using bottom transponder navigation, closely spaced survey lines, and long-traverse oblique photography. The block-faulted north-south hills are bounded by scarps, commonly with 40?? slopes. On these steep scarps sedimentation is inhibited and pillow basalts often crop out. An ash layer of high acoustic reflectivity at about 7 m subbottom depth blankets the area. This ash occurs in multiple beds altered to phillipsite and is highly consolidated. A 24 m.y. age for the ash is based on ichthyolith dates from samples in the overlying sediments. Acoustically transparent Neogene sediments above the ash are thickest in trough bottoms and are absent or thin on steep slopes. These Neogene sediments are composed of pale-brown pelagic clays of illite, quartz, smectite, chlorite and kaolinite. Dark-brown pelagic clays, rich in smectite and amorphous iron oxides, underlie the Neogene surficial sediments. Manganese nodules cover the bottom in varying percentages. The nodules are most abundant near basement outcrops and where the subbottom ash layer is absent. ?? 1984.

Small hazardous waste generators in developing countries: use of stabilization/solidification process as an economic tool for metal wastewater treatment and appropriate sludge disposal.

PubMed

Silva, Marcos A R; Mater, Luciana; Souza-Sierra, Maria M; Corrêa, Albertina X R; Sperb, Rafael; Radetski, Claudemir M

2007-08-25

The aim of this study was to propose a profitable destination for an industrial sludge that can cover the wastewater treatment costs of small waste generators. Optimized stabilization/solidification technology was used to treat hazardous waste from an electroplating industry that is currently released untreated to the environment. The stabilized/solidified (S/S) waste product was used as a raw material to build concrete blocks, to be sold as pavement blocks or used in roadbeds and/or parking lots. The quality of the blocks containing a mixture of cement, lime, clay and waste was evaluated by means of leaching and solubility tests according to the current Brazilian waste regulations. Results showed very low metal leachability and solubility of the block constituents, indicating a low environmental impact. Concerning economic benefits from the S/S process and reuse of the resultant product, the cost of untreated heavy metal-containing sludge disposal to landfill is usually on the order of US$ 150-200 per tonne of waste, while 1tonne of concrete roadbed blocks (with 25% of S/S waste constitution) has a value of around US$ 100. The results of this work showed that the cement, clay and lime-based process of stabilization/solidification of hazardous waste sludge is sufficiently effective and economically viable to stimulate the treatment of wastewater from small industrial waste generators.

Further studies on the problems of geomagnetic field intensity determination from archaeological baked clay materials

NASA Astrophysics Data System (ADS)

Kostadinova-Avramova, M.; Kovacheva, M.

2015-10-01

Archaeological baked clay remains provide valuable information about the geomagnetic field in historical past, but determination of the geomagnetic field characteristics, especially intensity, is often a difficult task. This study was undertaken to elucidate the reasons for unsuccessful intensity determination experiments obtained from two different Bulgarian archaeological sites (Nessebar - Early Byzantine period and Malenovo - Early Iron Age). With this aim, artificial clay samples were formed in the laboratory and investigated. The clay used for the artificial samples preparation differs according to its initial state. Nessebar clay was baked in the antiquity, but Malenovo clay was raw, taken from the clay deposit near the site. The obtained artificial samples were repeatedly heated eight times in known magnetic field to 700 °C. X-ray diffraction analyses and rock-magnetic experiments were performed to obtain information about the mineralogical content and magnetic properties of the initial and laboratory heated clays. Two different protocols were applied for the intensity determination-Coe version of Thellier and Thellier method and multispecimen parallel differential pTRM protocol. Various combinations of laboratory fields and mutual positions of the directions of laboratory field and carried thermoremanence were used in the performed Coe experiment. The obtained results indicate that the failure of this experiment is probably related to unfavourable grain sizes of the prevailing magnetic carriers combined with the chosen experimental conditions. The multispecimen parallel differential pTRM protocol in its original form gives excellent results for the artificial samples, but failed for the real samples (samples coming from previously studied kilns of Nessebar and Malenovo sites). Obviously the strong dependence of this method on the homogeneity of the used subsamples hinders its implementation in its original form for archaeomaterials. The latter are often heterogeneous due to variable heating conditions in the different parts of the archaeological structures. The study draws attention to the importance of multiple heating for the stabilization of grain size distribution in baked clay materials and the need of elucidation of this question.

Multi-block analysis coupled to laser-induced breakdown spectroscopy for sorting geological materials from caves.

PubMed

Ammari, Faten; Bassel, Léna; Ferrier, Catherine; Lacanette, Delphine; Chapoulie, Rémy; Bousquet, Bruno

2016-10-01

In this study, multi-block analysis was applied for the first time to LIBS spectra provided by a portable LIBS system (IVEA Solution, France) equipped with three compact Czerny-Turner spectrometers covering the spectral ranges 200-397nm, 398-571nm and 572-1000nm. 41 geological samples taken from a laboratory-cave situated in the "Vézère valley", an area rich with prehistoric sites and decorated caves listed as a UNESCO world heritage in the south west of France, were analyzed. They were composed of limestone and clay considered as underlying supports and of two types of alterations referred as moonmilk and coralloid. Common Components and Specific Weights Analysis (CCSWA) allowed sorting moonmilk and coralloid samples. The loadings revealed higher amounts of magnesium, silicon, aluminum and strontium in coralloids and the saliences emphasized that among the three spectrometers installed in the LIBS instrument used in this work; that covering the range 572-1000nm was less contributive. This new approach for processing LIBS data not only provides good results for sorting geological materials but also clearly reveals which spectral range contains most of the information. This specific advantage of multi-block analysis could lead for some applications to simplify the design and to reduce the size of LIBS instruments. Copyright © 2016 Elsevier B.V. All rights reserved.

Experimental study of Human Adenoviruses interactions with clays

NASA Astrophysics Data System (ADS)

Bellou, Maria; Syngouna, Vasiliki; Paparrodopoulos, Spyros; Vantarakis, Apostolos; Chrysikopoulos, Constantinos

2014-05-01

Clays are used to establish low permeability liners in landfills, sewage lagoons, water retention ponds, golf course ponds, and hazardous waste sites. Human adenoviruses (HAdVs) are waterborne viruses which have been used as viral indicators of fecal pollution. The objective of this study was to investigate the survival of HAdV in static and dynamic clay systems. The clays used as a model were crystalline aluminosilicates: kaolinite and bentonite. The adsorption and survival of HAdVs onto these clays were characterized at two different controlled temperatures (4 and 25o C) under static and dynamic batch conditions. Control tubes, in the absence of clay, were used to monitor virus inactivation due to factors other than adsorption to clays (e.g. inactivation or sorption onto the tubes walls). For both static and dynamic batch experiments, samples were collected for a maximum period of seven days. This seven day time - period was determined to be sufficient for the virus-clay systems to reach equilibrium. To infer the presence of infectious HAdV particles, all samples were treated with Dnase and the extraction of viral nucleid acid was performed using a commercial viral RNA kit. All samples were analyzed by Real - Time PCR which was used to quantify viral particles in clays. Samples were also tested for virus infectivity by A549 cell cultures. Exposure time intervals in the range of seven days (0.50-144 hours) resulted in a load reduction of 0.74 to 2.96 logs for kaolinite and a reduction of 0.89 to 2.92 for bentonite. Furthermore, virus survival was higher onto bentonite than kaolinite (p

Studies on thermal reactions and sintering behaviour of red clays by irreversible dilatometry

NASA Astrophysics Data System (ADS)

Anil, Asha; Misra, S. N.; Misra, N. M.

2018-05-01

Thermal behavior of clays strongly influences that of ceramic bodies made thereof and hence, its study is must for assessing its utility in ceramic products as well as to set the body composition. Irreversible dilatometry is an effective thermal analysis tool for evaluating thermal reactions as well as sintering behavior of clays or clay based ceramic bodies. In this study, irreversible dilatometry of four red clay samples (S, M, R and G) of Gujarat region, which vary in their chemical and mineralogical compositions was carried out using a Dilatometer and compared. Chemical analysis and XRD of red clays were carried out. XRD showed that major clay minerals in S, M and R clays are kaolinite. However, clay marked R and G showed presence of both kaolinite and illite and /muscovite. Presence of non-clay minerals such as hematite, quartz, anatase were also observed in all clays. XRD results were in agreement with chemical analyses results. Rational analyses showed variation in amount of clay and non-clay minerals in red clay samples. Evaluation of dilatometric curves showed that clay marked as S, M and R exhibit patterns typical for kaolinitic clays. Variation in linear expansion (up to 550°C) and shrinkage (above 550°C) between these three clays was found to be related to difference in amount of quartz and kaolinite respectively. However, dilatometric curve of G exhibit a pattern similar to that for an illitic clay. This study confirmed that sintering of investigated kaolinitic and illitic and / muscovitic red clays initiates at above 1060°C and 860°C respectively and this behaviour strongly depends upon type and amount of minerals and their chemical compositions.

DIBENZO-P-DIOXINS IN THE ENVIRONMENT FROM CERAMICS AND POTTERY PRODUCED FROM BALL CLAY MINED IN THE U.S.

EPA Science Inventory

Processed ball clay samples used in the production of ceramics and samples of the ceramic products were collected and analyzed for the presence and concentration of the 2,3,7,8-Cl substituted polychlorinated dibenzo-p-dioxins and furans (PCDDs/PCDFs). The processed ball clay had...

Single clay sheets inside electrospun polymer nanofibers

NASA Astrophysics Data System (ADS)

Sun, Zhaohui

2005-03-01

Nanofibers were prepared from polymer solution with clay sheets by electrospinning. Plasma etching, as a well controlled process, was used to supply electrically excited gas molecules from a glow discharge. To reveal the structure and arrangement of clay layers in the polymer matrix, plasma etching was used to remove the polymer by controlled gasification to expose the clay sheets due to the difference in reactivity. The shape, flexibility, and orientation of clay sheets were studied by transmission and scanning electron microscopy. Additional quantitative information on size distribution and degree of exfoliation of clay sheets were obtained by analyzing electron micrograph of sample after plasma etching. Samples in various forms including fiber, film and bulk, were thinned by plasma etching. Morphology and dispersion of inorganic fillers were studied by electron microscopy.

Mineralogical Characterization of the Miocene Olcese Formation, Southern San Joaquin Valley, California

NASA Astrophysics Data System (ADS)

Lopez, K. A.; Baron, D.; Guo, J.; Woolford, J. M.

2016-12-01

The early to middle Miocene Olcese Formation in the southern San Joaquin Valley of California consists of shallow marine shelf sands in its lower and upper parts, and non-marine, frequently pumiceous sands in its middle part, and varies in thickness up to 1800 ft. There is little known as to the origin, nature, quantity, and distribution of clay minerals throughout the formation. This study examined 95 sidewall core samples from three wells, as well as 388 cutting samples from four wells and 12 samples from 3 outcrops. Well samples were from depths between 1,800 and 4,000 ft. Qualitative and quantitative mineralogy including clay minerals of the sidewall samples and selected cutting samples was determined by powder X-ray diffraction (XRD). XRD analyses were supplemented by scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDS) and petrographic microscopy of selected samples. The main minerals of bulk samples include composite clay, quartz, potassium feldspar/plagioclase, calcite, and clinoptilolite. Content of composite clay varies between 17% and 51%. The clay-size fraction is predominantly composed of smectite, illite, kaolinite and chlorite with smectite being the most abundant. Smectite and clinoptilolite may be the alteration products of deeper burial of volcanic materials. The formation permeability could be significantly lowered by these authigenic minerals.

Direct visualization of clay microfabric signatures driving organic matter preservation in fine-grained sediment

NASA Astrophysics Data System (ADS)

Curry, Kenneth J.; Bennett, Richard H.; Mayer, Lawrence M.; Curry, Ann; Abril, Maritza; Biesiot, Patricia M.; Hulbert, Matthew H.

2007-04-01

We employed direct visualization of organic matter (OM) sequestered by microfabric signatures in organo-clay systems to study mechanisms of OM protection. We studied polysaccharides, an abundant class of OM in marine sediments, associated with the nano- and microfabric of clay sediment using a novel application of transmission electron microscopy, histochemical staining (periodic acid-thiosemicarbazide-silver proteinate), and enzymatic digestion techniques. We used two experimental organo-clay sediment environments. First, laboratory-consolidated sediment with 10% chitin (w/w) added was probed for chitin before and after digestion with chitinase. Second, fecal pellets from the polychaete Heteromastus filiformis were used as a natural environment rich in clay and polysaccharides. Sections of this material were probed with silver proteinate for polysaccharides before and after digestion with a mixture of enzymes (amylase, cellulase, chitinase, dextranase, and pectinase). In both environments, chitin or other polysaccharides were found within pores, bridging clay domains, and attached to clay surfaces in undigested samples. Digested samples showed chitin or polysaccharides more closely associated with clay surfaces and in small pores. Our results imply protective roles for both sorption to clay surfaces and encapsulation within clay microfabric signatures.

Color measurement of methylene blue dye/clay mixtures and its application using economical methods

NASA Astrophysics Data System (ADS)

Milosevic, Maja; Kaludjerovic, Lazar; Logar, Mihovil

2016-04-01

Identifying the clay mineral components of clay materials by staining tests is rapid and simple, but their applicability is restricted because of the mutual interference of the common components of clay materials and difficulties in color determination. The change of color with concentration of the dye is related to the use of colorants as a field test for identifying clay minerals and has been improved over the years to assure the accuracy of the tests (Faust G. T., 1940). The problem of measurement and standardization of color may be solved by combination of colors observed in staining tests with prepared charts of color chips available in the Munsell Book of Color, published by Munsell Color Co. Under a particular set of illumination conditions, a human eye can achieve an approximate match between the color of the dyed clay sample and that of a standard color chip, even though they do have different spectral reflectance characteristics. Experiments were carried out with diffuse reflectance spectroscopy on selected clay samples (three montmorillonite, three kaolinite and one mix-layer clay samples) saturated with different concentration of methylene blue dye solution. Dominant wavelength and purity of the color was obtained on oriented dry samples and calculated by use of the I. C. I. (x, y) - diagram in the region of 400-700 nm (reflectance spectra) without MB and after saturation with different concentrations of MB solutions. Samples were carefully photographed in the natural light environment and processed with user friendly and easily accessible applications (Adobe color CC and ColorHexa encyclopedia) available for android phones or tablets. Obtained colors were compared with Munsell standard color chips, RGB and Hexa color standards. Changes in the color of clay samples in their interaction with different concentration of the applied dye together with application of economical methods can still be used as a rapid fieldwork test. Different types of clay minerals can be distinguished by application of at least three concentrations of the methylene blue dye on the same sample and observing the color change in comparison with standardized color chips that can be easily obtained and free of charge. If the color tests are properly used in conjunction with other more complex analytical procedures, they can be helpful addition in identification of different clay minerals, especially montmorillonite and kaolinite minerals. - Faust G. T., 1940, Staining of clay minerals as a rapid means of identification in natural and beneficiated products, U. S. Bur. Mines, Investigation Report. N0.3522 - Munsell Color, Munsell Book of Color, 1942. Macbeth Division of Kollmorgen Corporation, Maryland, U.S.A. - https://color.adobe.com/create/color-wheel/ - http://www.colorhexa.com/

Phosphoric acid purification through different raw and activated clay materials (Southern Tunisia)

NASA Astrophysics Data System (ADS)

Trabelsi, Wafa; Tlili, Ali

2017-05-01

This study concerns the purification of Tunisian phosphoric acid produced by the Tunisian Chemical Group (TCG), using raw and activated clays materials from Southern Tunisia. The Gafsa basin clays samples (Jebel Hamadi (JHM); Jebel Stah (JS) and the El Hamma sample (Jebel Aïdoudi (JAD)) were activated with 3 M, HCl solution. Phosphoric acid purification was performed on raw and activated clays. Mineralogical characterisation was carried out using the X-ray powder diffraction method and infrared absorption spectroscopy. Textural changes between raw and activated clays were identified using SEM observations and specific surface analysis. Jebel Hamadi clays were almost dominated by smectite associated with kaolinite and illite traces, while Jebel Stah and Jebel Aïdoudi clays were composed of the association of smectite, illite and kaolinite. It is worth noting that the position of the smectite (001) reflection increased after the acidic activation in all studied samples, indicating the relaxation of the smectite structure along the c-axis. This was corroborated by the increasing specific surface area of the clay particles with the activation process. The specific surface area was close to 50 m2/g and 200 m2/g, for raw and activated materials, respectively. The maximum phosphoric acid purification was obtained by using activated clays with 3 N HCl for 4 h. This performance correlated with the maximum of the external specific surface area which generated strong acid sites. Furthermore, the best results of phosphoric acids purification from TCG were obtained at a specific consumption equivalent to 30 Kg of clay/ton of P2O5. These results showed that the best phosphoric acid purification was yielded by Jebel Aïdoudi clay. In all cases, the highest organic carbon reduction rates in the phosphoric acid after filtration were obtained at 90°C.

Block Slides on Extremely Weak Tectonic Clay Seams in Openly Folded Tertiary Mud-Rocks at Auckland and the Rangitikei Valley, North Island, New Zealand

NASA Astrophysics Data System (ADS)

Prebble, Warwick M.; Williams, Ann L.

2016-06-01

Block slides have developed on extremely weak, thin clay seams of tectonic origin, parallel to bedding in gently dipping sandstones and mudstones of Tertiary age. Two areas of noted instability are investigated at Auckland and the Rangitikei valley. Dimensions range from 100 m across × 100 m long for short displacement block slides up to 4 km across × 3 km long for large landslide complexes in which block slides are a major component. Displacements of blocks range from incipient (cm) through short (30 m) to 2 or 3 km for large slides. Many of the Auckland slides are dormant but likely to move in a 2000 year return period earthquake or 100 year high intensity rain storm. At Rangitikei there are many active, younger slides. Sliding rates for active failures vary from a few cm/year to 50 m in 30 min. Host rocks are weak to very weak clayey sandstones and sandy mudstones. The seams are rich in smectite. They have polished and crushed walls, may have slickensides and some contain rounded rock fragments. Laboratory shear strength of the seams is 13 kPa cohesion and 13° friction, with a lower bound of 8° at zero cohesion. Strength is increased at the field scale by waviness, steps and splays. Continuity can be demonstrated over distances of hundreds of metres. Key investigation methods were mapping, shafts and trenches. Tectonic uplift, folding and faulting of the weak Tertiary strata and river down-cutting are perpetuating block slide development.

Mineralogy and thermal properties of clay from Slatina (Ub, Serbia)

NASA Astrophysics Data System (ADS)

Milosevic, Maja; Logar, Mihovil; Kaludjerovic, Lazar; Jelic, Ivana

2017-04-01

The "Slatina" deposit, Ub, Serbia was opened in 1965 and represents one of few deposits exploited by "Kopovi" a.d., Ub, company. Deposit is composed of clay layers belonging to Neogene sediments that are widespread transgressive over granitoid rocks of Cer mountain and Paleozoic and Mesozoic sediments. Clay is mostly of illite-montmorillonite-kaolinite type and they are generally used as ceramic materials while some of the layers are used as fire-resistant materials. In this study we present mineralogical and thermal characterization of two samples to determine their application as industrial materials. Chemical and mineral composition was determined using inductively coupled plasma optical emission spectroscopy (ICP-OES), X-ray diffraction (XRD) on powder and oriented samples, infrared spectroscopy (IR) and granulometry. Cationic exchange capacity (CEC) and specific surface area (SSA) was determined using spectrophotometry and methylene blue (MB). Thermal properties where determined by gravimetry (120, 350, 600 and 1000 oC) and differential thermal analysis (DTA). Quantitative mineral composition obtained by Rietveld refinement of combined chemical and XRD data shows that the sample 1(SC) is mainly smectite-illite (45%) and kaolinite (14%) clay with 19% of quartz, 10% feldspars and 7% of limonite, while sample 2(SV) is smectite-illite (43%) and kaolinite (11%) clay with 10% of quartz, 15% feldspars and 7% of limonite. Both samples have low content of impurities (carbonate minerals). Medium grain size (μm) goes from 1.02 (SSA = 104 m2/g) for sample 1(SC) to 0.71 (SSA = 117 m2/g) for sample 2(SV) while their CEC is 12.7 and 14.9 mmol/100g for 1(SC) and 2(SV) respectively. IR spectra of the samples shows larger amount of smectite clays with quartz and carbonate minerals for both samples which is in accordance with XRD data. DTA data shows couple of events that are endothermic. First one (100-200 oC) is associated with loss of moisture and constitutive water, second (300-400 oC) with iron hydroxide minerals, third (500-600 oC) with smectite clay content with smaller separate bands of kaolinite clays while events between 800-900 oC correspond to carbonate minerals. Loss of mass after gravimetry measurement at given temperatures shows that the samples have significant amount of water in their structure (≈3 wt% (120 oC)) with larger weight loss at 600 oC (3.06 and 3.37 wt%) while total weight loss is 9.12 and 9.08 wt% for 1(SC) and 2(SV) respectively. The studied clays from "Slatina" deposit have a medium content of smectite-illite minerals with smaller amount of kaolinite mineral together with quartz and feldspars. Based on their mineral composition and characteristics, possible application should be in different types of ceramic and construction industries. REFERENCES - M. Milošević, M. Logar, B. Dojčinović, A. Rosić and S. Erić, 2016, Diffuse reflectance spectra of methylene blue adsorbed on different types of clay samples, Clay Minerals, (2016) 5, 1-15

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

USGS Publications Warehouse

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

2003-01-01

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

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

PubMed Central

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

2014-01-01

Geophagy, the deliberate consumption of earth, is strongly associated with iron (Fe) deficiency. It has been proposed that geophagy may be practiced as a means to improve Fe status by increasing Fe intakes and, conversely, that geophagy may cause Fe deficiency by inhibiting Fe absorption. We tested these hypotheses by measuring Fe concentration and relative bioavailable Fe content of 12 samples of geophagic earth and 4 samples of pure clay minerals. Further, we assessed the impact of these samples on the bioavailability of Fe from an Fe-rich test meal (cooked white beans, WB). Fe concentrations were measured with inductively coupled plasma atomic emission spectroscopy. Fe bioavailability was determined using an in vitro digestion/Caco-2 cell model in which ferritin formation was used as an index of Fe bioavailability. Geophagic earth and clay mineral samples were evaluated with this model, both alone and in combination with WB (1:16 ratio, sample:WB). Median Fe concentration of the geophagic earth was 3485 (IQR 2462, 14571) μg/g and mean Fe concentration in the clay minerals was 2791 (± 1782) μg/g. All specimens had Fe concentrations significantly higher (p ≤ 0.005) than the Fe concentration of WB (77 μg/g). Ferritin formation (i.e. Fe uptake) in cells exposed to geophagic earths and clay minerals was significantly lower than in cells exposed to WB (p ≤ 0.05) and Fe uptake responses of 11 of the 16 samples were not significantly different from the blank, indicating no bioavailable Fe. When samples were combined with WB, 5 of 16 had mean ferritin levels that were significantly lower (p ≤ 0.05, one tail) than the WB alone, indicating that the samples inhibited Fe uptake from the WB. None of the ferritin responses of cells exposed to both WB and earth/clay were significantly higher than WB alone. Thus, although geophagic earths and mineral clays are high in total Fe, very little of this Fe is bioavailable. Further, some geophagic earth and clay mineral samples inhibit Fe absorption from foods. In vivo research is warranted to confirm these observations and to determine if geophagic earth samples can be a source of Fe and/or inhibit Fe absorption. PMID:23787405

Pore characteristics and their emergent effect on water adsorption and transport in clays using small-angle neutron scattering with contrast variation

NASA Astrophysics Data System (ADS)

Ding, M.; Hartl, M.; Wang, Y.; Hjelm, R.

2013-12-01

In nuclear waste management, clays are canonical materials in the construction of engineered barriers. They are also naturally occurring reactive minerals which play an important role in retention and colloidal facilitated reactive transport in subsurface systems. Knowledge of total and accessible porosity in clays is crucial in determining fluids transport behavior in clays. It will provide fundamental insight on the performance efficiency of specific clays as a barrier material and their role in regulating radionuclide transport in subsurface environments. The aim of the present work is to experimentally investigate the change in pore characteristics of clays as function of moisture content, and to determine their pore character in relation to their water retention capacity. Recent developments in small-angle neutron scattering (SANS) techniques allow quantitative measurement of pore morphology and size distribution of various materials in their pristine state under various sample environments (exposure to solution, high temperature, and so on). Furthermore, due to dramatic different neutron scattering properties of hydrogen and deuterium, one can readily use contrast variation, which is the isotopic labeling with various ratios of H and D (e.g. mixture of H2O/D2O) to highlight or suppress features of the sample. This is particularly useful in the study of complex pore system such as clays. In this study, we have characterized the pore structures for a number of clays including clay minerals and field samples which are relevant to high-level waste systems under various sample environments (e.g., humidity, temperature and pressure) using SANS. Our results suggest that different clays show unique pore features under various sample environments. To distinguish between accessible/non-accessible pores and the nature of pore filling (e.g. the quantity of H2O adsorbed by clays, and the distribution of H2O in relation to pore character) to water, clays were exposed for various periods to a specific humidity (e.g., relative humidity: RH=100%, RH=75%). The humidity is controlled by using saturated aqueous solutions, consisting of specific H2O/D2O mixtures. Our results have shown distinct variations in water adsorption and moisture diffusivity among clays. Our results allow us to obtain on the pore scale porosity changes due to water movement in clays. As emergent transport property, nano- to micro-scale structural characterization is crucial in providing insights into pore-scale transport processes, which are pertinent to upscale continuum model development involving flow and transport at low water content, flow and phase behavior under confinement, and low-permeability media.

Heavy metal content and potential health risk of geophagic white clay from the Kumasi Metropolis in Ghana.

PubMed

Nkansah, Marian Asantewah; Korankye, Mavis; Darko, Godfred; Dodd, Matt

2016-01-01

Geophagia is the craving for non-food substances and commonly practiced among pregnant women and children. Consumption of geophagic clay samples can have serious implications on the health of the consumers as a result of the presence of toxic metals such as Pb, As, Hg and Cd. This study sought to determine the levels of heavy metals in the studied geophagic clay samples and to determine the potential risks of heavy metals as cumulative carcinogenic and non-carcinogenic risks to the health of the consumers via oral (ingestion) and dermal exposure routes. A total of thirty (30) white clay samples were analysed using Niton Thermo scientific XRF Analyser (Mobile Test S, NDTr-XL3t-86956, com 24). The clay samples were found to contain essential elements such as Ca, Fe, K and Zn as well as toxic metals such as As and Pb. There were isolated cases of the presence of Hg and all samples had Cd levels below detection. Health risk indices such as hazard quotient and cancer risk were calculated and the results indicated that consumers are likely to suffer from cancer through ingestion of geophagic clay. Bioaccessibility studies were done on zinc and it did not indicate any potential toxicity due to zincs essential nature. The levels of heavy metals in some of the geophagic clay consumed by some residents in the Kumasi were high compared to the Permitted Maximum Tolerable Daily Intake (PMTDI) by (WHO/FAO) and may pose potential health threat over time.

Evidence for Smectite Clays from MSL SAM Analyses of Mudstone at Yellowknife Bay, Gale Crater, Mars

NASA Technical Reports Server (NTRS)

McAdam, Amy; Franz, Heather; Mahaffy, Paul R.; Eigenbrode, Jennifer L.; Stern, Jennifer C.; Brunner, Anna; Archer, Paul Douglas; Ming, Douglas W.; Morris, Richard V.; Atreya, Sushil K.

2013-01-01

Drilled samples of mudstone from the Sheepbed unit at Yellowknife Bay were analyzed by MSL instruments including the Sample Analysis at Mars (SAM) and Chemistry and Mineralogy (CheMin) instruments in MSL's Analytical Laboratory. CheMin analyses revealed the first in situ X-ray diffraction based evidence of clay minerals on Mars, which are likely trioctahedral smectites (e.g., saponite) and comprise approx 20% of the mudstone sample (e.g., Bristow et al., this meeting). SAM analyses, which heated the mudstone samples to 1000 C and monitored volatiles evolved to perform in situ evolved gas analysis mass spectrometry (EGA-MS), resulted in a H2O trace exhibiting a wide evolution at temperatures < 500 C, and an evolution peak at higher temperatures near approx 750 C. The low temperature H2O evolution has many potential contributors, including adsorbed H2O, smectite interlayer H2O, and structural H2O/OH from bassanite and akaganeite (identified by CheMin) and H2O/OH from amorphous phases in the sample. The high temperature H2O is consistent with the evolution of H2O from the dehydroxylation of the smectite clay mineral. Comparison to EGA-MS data collected under SAM-like conditions on a variety of clay mineral reference materials indicate that a trioctahedral smectite, such as saponite, is most consistent with the high temperature H2O evolution observed. There may also be SAM EGA-MS evidence for a small high temperature H2O evolution from scoop samples from the Yellowknife Bay Rocknest sand shadow bedform. As in the mudstone samples, this evolution may indicate the detection of smectite clays, and the idea that minor clays may be present in Rocknest materials that could be expected to be at least partially derived from local sources is reasonable. But, because smectite clays were not definitively observed in CheMin analyses of Rocknest materials, they must be present at much lower abundances than the approx 20% observed in the mudstone samples. This potential detection underscores the complementary nature of the MSL CheMin and SAM instruments for investigations of martian sample mineralogy. Information on the nature of Yellowknife Bay clay minerals may also be available from the detection of H2 evolved during SAM EGA-MS at high temperature. A likely source of at least some of this H2 is H2O evolved from the smectite clays at high temperature, and it is possible these evolutions can be used in a similar fashion to high temperature H2O releases to provide constraints on the clay minerals in a sample. In addition, the D/H of this high temperature H2, as well as the H2O, can be derived from SAM MS and Tunable Laser Spectrometer (TLS) data, respectively. These D/H values may help to inform the provenance of high and low temperature water evolved from martian samples

Friction behavior for clay minerals during dehydration process: implication for unstable friction at shallow portion along subducting plate

NASA Astrophysics Data System (ADS)

Kubo, T.; Katayama, I.

2016-12-01

Along plate boundary subduction thrusts, the transformation of smectite to illite within fault gouge at temperatures around 100 - 200 °C is one of the key mineralogical changes thought to control the updip limit of seismicity (Hyndman et al., 1997). Since hydration state of clay minerals is possible to vary from moment to moment in nature, it is important to investigate the effect of dehydration and hydrate state on frictional properties with progression of a removal of water is rare. In this study, we focus on the effect of dehydration of water on the frictional properties of clay minerals by temperature-rising test. For the friction experiments, starting materials we used are Ca-montmorillonite, which were placed on the simulated fault surface and two side blocks were placed together to produce a double-direct shear configuration. The sample assembly was heated by an external furnace up to 400 °C that is monitored by thermocouples located in the central part of sample assembly. After steady-state friction at room temperature we started to elevate the temperature around the specimen at a constant heating rate of 1, 3, and 10 °C/min. Ca-montmorillonite gouge showed unique friction behavior development as elevated temperature, which is divided into three stages; (1) friction coefficient decreased at relative low temperature, (2) friction coefficient increased at middle temperature, and (3) stick-slip behavior occurred at high temperature. Stick-slip behavior as elevated temperature implies to have a potential of velocity weakening behavior. Observed stick-slip behavior occurs at a temperature of 320 °C, which is extremely higher from a temperature range of occurring dehydration for Ca-montmorillonite (100 - 200 °C). However, at low heating rate the temperature that stick-slip behavior occurs shifted to lower temperature. Our preliminary results suggest that the observed systematical shift suggest that these frictional behavior is likely to be controlled by dehydration reaction kinetics. Dehydration of clay minerals change friction behavior, and play a key role for the occurrence of earthquakes along subducting plate.

Isotropic-nematic phase transition in aqueous sepiolite suspensions.

PubMed

Woolston, Phillip; van Duijneveldt, Jeroen S

2015-01-01

Aqueous suspensions of sepiolite clay rods in water tend to form gels on increase of concentration. Here it is shown how addition of a small amount (0.1% of the clay mass) of a common stabiliser for clay suspensions, sodium polyacrylate, can allow the observation of an isotropic-nematic liquid crystal phase transition. This transition was found to move to higher clay concentrations upon adding NaCl, with samples containing 10(-3) M salt or above only displaying a gel phase. Even samples that initially formed liquid crystals had a tendency to form gels after several weeks, possibly due to Mg(2+) ions leaching from the clay mineral. Copyright © 2014 The Authors. Published by Elsevier Inc. All rights reserved.

Impact of Rotylenchulus reniformis on Cotton Yield as Affected by Soil Texture and Irrigation

PubMed Central

Herring, Stephanie L.; Heitman, Joshua L.

2010-01-01

The effects of soil type, irrigation, and population density of Rotylenchulus reniformis on cotton were evaluated in a two-year microplot experiment. Six soil types, Fuquay sand, Norfolk sandy loam, Portsmouth loamy sand, Muck, Cecil sandy loam, and Cecil sandy clay, were arranged in randomized complete blocks with five replications. Each block had numerous plots previously inoculated with R. reniformis and two or more noninoculated microplots per soil type, one half of which were irrigated in each replicate for a total of 240 plots. Greatest cotton lint yields were achieved in the Muck, Norfolk sandy loam, and Portsmouth loamy sand soils. Cotton yield in the Portsmouth loamy sand did not differ from the Muck soil which averaged the greatest lint yield per plot of all soil types. Cotton yield was negatively related to R. reniformis PI (initial population density) in all soil types except for the Cecil sandy clay which had the highest clay content. Supplemental irrigation increased yields in the higher yielding Muck, Norfolk sandy loam, and Portsmouth loamy sand soils compared to the lower yielding Cecil sandy clay, Cecil sandy loam, and Fuquay sand soils. The Portsmouth sandy loam was among the highest yielding soils, and also supported the greatest R. reniformis population density. Cotton lint yield was affected more by R. reniformis Pi with irrigation in the Portsmouth loamy sand soil with a greater influence of Pi on lint yield in irrigated plots than other soils. A significant first degree PI × irrigation interaction for this soil type confirms this observation. PMID:22736865

Impact of Rotylenchulus reniformis on Cotton Yield as Affected by Soil Texture and Irrigation.

PubMed

Herring, Stephanie L; Koenning, Stephen R; Heitman, Joshua L

2010-12-01

The effects of soil type, irrigation, and population density of Rotylenchulus reniformis on cotton were evaluated in a two-year microplot experiment. Six soil types, Fuquay sand, Norfolk sandy loam, Portsmouth loamy sand, Muck, Cecil sandy loam, and Cecil sandy clay, were arranged in randomized complete blocks with five replications. Each block had numerous plots previously inoculated with R. reniformis and two or more noninoculated microplots per soil type, one half of which were irrigated in each replicate for a total of 240 plots. Greatest cotton lint yields were achieved in the Muck, Norfolk sandy loam, and Portsmouth loamy sand soils. Cotton yield in the Portsmouth loamy sand did not differ from the Muck soil which averaged the greatest lint yield per plot of all soil types. Cotton yield was negatively related to R. reniformis PI (initial population density) in all soil types except for the Cecil sandy clay which had the highest clay content. Supplemental irrigation increased yields in the higher yielding Muck, Norfolk sandy loam, and Portsmouth loamy sand soils compared to the lower yielding Cecil sandy clay, Cecil sandy loam, and Fuquay sand soils. The Portsmouth sandy loam was among the highest yielding soils, and also supported the greatest R. reniformis population density. Cotton lint yield was affected more by R. reniformis Pi with irrigation in the Portsmouth loamy sand soil with a greater influence of Pi on lint yield in irrigated plots than other soils. A significant first degree PI × irrigation interaction for this soil type confirms this observation.

The use of fortified soil-clay as on-site system for domestic wastewater purification.

PubMed

Oladoja, N A; Ademoroti, C M A

2006-02-01

The quest for simple, low-cost and high-performance decentralized wastewater treatment system for domestic application in developing nations necessitated this study. Clay samples collected from different deposits in Nigeria were characterized by studying the mineralogical and geochemical composition using X-ray diffraction (XRD) and atomic absorption spectroscopy (AAS), respectively. Three major clay minerals of kaolinite, illite and smectite were identified. The geochemical studies showed the abundance of SiO2, Al2O3 and H2O+ in each of the clay samples. Performance efficiency studies were conducted to determine the best combination ratio of pebbles/soil-clay. Soil-clay fortified by pebbles in combination ratios of 1:3 (i.e. pebbles:soil-clay = 1:3 (w/w) showed the optimum water purification, while the combination 3:1 gave the least. The flow rate studies showed that the wastewater had a longer residence time in non-fortified soil-clay than in fortified soil-clay. Two modes of treatment methods were employed-single and double column treatment methods (SCT and DCT). The two methods gave effluents of good quality characteristics, but those from the DCT were of better quality. The quality of effluents also varies from one clay type to another. The quality of effluents from media containing smectite clay mineral was better than those from other columns. Repeated usage of the fortified clay column showed a decrease of pH, TS and DO, and an increase of COD when monitored over a period of 10 days.

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

PubMed

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

2013-08-01

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

Sampling Outdoor, Resting Anopheles gambiae and Other Mosquitoes (Diptera: Culicidae) in Western Kenya with Clay Pots

PubMed Central

Odiere, M.; Bayoh, M. N.; Gimnig, J.; Vulule, J.; Irungu, L.; Walker, E.

2014-01-01

Clay pots were analyzed as devices for sampling the outdoor resting fraction of Anopheles gambiae Giles (Diptera: Culicidae) and other mosquito species in a rural, western Kenya. Clay pots (Anopheles gambiae resting pots, herein AgREPOTs), outdoor pit shelters, indoor pyrethrum spray collections (PSC), and Colombian curtain exit traps were compared in collections done biweekly for nine intervals from April to June 2005 in 20 housing compounds. Of 10,517 mosquitoes sampled, 4,668 An. gambiae s.l. were sampled in total of which 63% were An. gambiae s.s. (46% female) and 37% were An. arabiensis (66% female). The clay pots were useful and practical for sampling both sexes of An. gambiae s.l. Additionally, 617 An. funestus (58% female) and 5,232 Culex spp. (males and females together) were collected. Temporal changes in abundance of An. gambiae s.l. were similarly revealed by all four sampling methods, indicating that the clay pots could be used as devices to quantify variation in mosquito population density. Dispersion patterns of the different species and sexes fit well the negative binomial distribution, indicating that the mosquitoes were aggregated in distribution. Aside from providing a useful sampling tool, the AgREPOT also may be useful as a delivery vehicle for insecticides or pathogens to males and females that enter and rest in them. PMID:17294916

The influence of shale depositional fabric on the kinetics of hydrocarbon generation through control of mineral surface contact area on clay catalysis

NASA Astrophysics Data System (ADS)

Rahman, Habibur M.; Kennedy, Martin; Löhr, Stefan; Dewhurst, David N.; Sherwood, Neil; Yang, Shengyu; Horsfield, Brian

2018-01-01

Accurately assessing the temperature and hence the depth and timing of hydrocarbon generation is a critical step in the characterization of a petroleum system. Clay catalysis is a potentially significant modifier of hydrocarbon generation temperature, but experimental studies of clay catalysis show inconsistent or contradictory results. This study tests the hypothesis that source rock fabric itself is an influence on clay mineral catalysis as it controls the extent to which organic matter and clay minerals are physically associated. Two endmember clay-organic fabrics distinguish the source rocks studied: (1) a particulate fabric where organic matter is present as discrete, >5 μm particles and (2) a nanocomposite fabric in which amorphous organic matter is associated with clay mineral surfaces at sub-micron scale. High-resolution electron imaging and bulk geochemical characterisation confirm that samples of the Miocene Monterey Formation (California) are representative of the nanocomposite source rock endmember, whereas samples from the Permian Stuart Range Formation (South Australia) represent the particulate source rock endmember. Kinetic experiments are performed on paired whole rock and kerogen isolate samples from these two formations using open system, non-isothermal pyrolysis at three different heating rates (0.7, 2 and 5 K/min) to determine the effects of the different shale fabrics on hydrocarbon generation kinetics. Extrapolation to a modelled geological heating rate shows a 20 °C reduction in the onset temperature of hydrocarbon generation in Monterey Formation whole rock samples relative to paired kerogen isolates. This result is consistent with the Monterey Formations's nanocomposite fabric where clay catalysis can proceed because reactive clay minerals are intimately associated with organic matter. By contrast, there is no significant difference in the modelled hydrocarbon generation temperature of paired whole rock and kerogen isolates from the Stuart Range Formation. This is consistent with its particulate fabric, where relatively large, discrete organic particles have limited contact with the mineral matrix and the clay minerals are mainly diagenetic and physically segregated within pores. While heating rate may have a control on mineral matrix effects, this result shows that the extent to which organic matter and clay minerals are physically associated could have a significant effect on the timing of hydrocarbon generation, and is a function of the depositional environment and detrital vs diagenetic origin of clay minerals in source rocks.

Impact of monovalent cations on soil structure. Part II. Results of two Swiss soils

NASA Astrophysics Data System (ADS)

Farahani, Elham; Emami, Hojat; Keller, Thomas

2018-01-01

In this study, we investigated the impact of adding solutions with different potassium and sodium concentrations on dispersible clay, water retention characteristics, air permeability, and soil shrinkage behaviour using two agricultural soils from Switzerland with different clay content but similar organic carbon to clay ratio. Three different solutions (including only Na, only K, and the combination of both) were added to soil samples at three different cation ratio of soil structural stability levels, and the soil samples were incubated for one month. Our findings showed that the amount of readily dispersible clay increased with increasing Na concentrations and with increasing cation ratio of soil structural stability. The treatment with the maximum Na concentration resulted in the highest water retention and in the lowest shrinkage capacity. This was was associated with high amounts of readily dispersible clay. Air permeability generally increased during incubation due to moderate wetting and drying cycles, but the increase was negatively correlated with readily dispersible clay. Readily dispersible clay decreased with increasing K, while readily dispersible clay increased with increasing K in Iranian soil (Part I of our study). This can be attributed to the different clay mineralogy of the studied soils (muscovite in Part I and illite in Part II).

Hydraulic and mechanical behavior of landfill clay liner containing SSA in contact with leachate.

PubMed

Zhang, Qian; Lu, Haijun; Liu, Junzhu; Wang, Weiwei; Zhang, Xiong

2018-05-01

Sewage sludge ash (SSA) produced by municipal sludge can be used as a modified additive for clay liner, and improves the working performance of landfill clay liner in contact with leachate. Under the action of landfill leachate, the permeability, shear strength, phase composition, and pore structure of the modified clay are investigated through the flexible wall permeability test, triaxial shear test, thermal gravimetric and differential thermal analysis, and low-temperature nitrogen adsorption test, respectively. The hydraulic conductivity of the modified clay containing 0-5% SSA is in the range of 3.94 × 10 -8 -1.16 × 10 -7  cm/s, and the pollutant concentration of the sample without SSA was higher than others. The shear strength of the modified clay is more than that of the traditional clay liner, the cohesion rate of modified clay increases from 32.5 to 199.91 kPa, and the internal friction angle decreases from 32.5° to 15.6°. Furthermore, the weight loss rates of the samples are 15.69%, 17.92%, 18.06%, and 20.68%, respectively, when the SSA content increases from 0% to 5%. The total pore volume and average pore diameter of the modified clay decrease with the increase in the SSA content, respectively. However, the specific area of the modified clay increases with the increase in the SSA content.

Clays causing adhesion with tool surfaces during mechanical tunnel driving

NASA Astrophysics Data System (ADS)

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

2009-04-01

During mechanical excavation with a tunnel boring machine (TBM) it is possible that clays stick to the cutting wheel and to other metal parts. The resulting delays in the progress of construction work, cause great economic damage and often disputes between the public awarding authorities and executing companies. One of the most important factors to reduce successfully the clay adhesion is the use of special polymers and foams. But why does the clay stick to the metal parts? A first step is to recognize which kind of clay mineralogy shows serious adhesion problems. The mechanical properties of clay and clay suspensions are primarily determined by surface chemistry and charge distribution at the interfaces, which in turn affect the arrangement of the clay structure. As we know, clay is a multi-phase material and its behaviour depends on numerous parameters such as: clay mineralogy, clay fraction, silt fraction, sand fraction, water content, water saturation, Atterberg limits, sticky limit, activity, cation exchange capacity, degree of consolidation and stress state. It is therefore likely that adhesion of clay on steel is also affected by these clay parameters. Samples of clay formations, which caused problems during tunnel driving, will be analyzed in laboratory. Mineralogical analyses (diffractometry, etc.) will be carried out to observe which minerals are responsible for adherence problems. To manipulate the physical properties, batch tests will be carried out in order to eliminate or reduce the adhesion on tool surfaces through variation of the zeta potential. Second step is the performance of vane shear tests on clay samples. Different pore fluid (distilled water, pure NaCl solution, ethanol and methanol) will be used to study the variation of the mechanical behaviour of clay depending on the dielectric constant of the fluids. This project is funded by the German Federal Ministry of Education and Research (BMBF) and the DFG (German Research Foundation) in the frame of the programme GEOTECHNOLOGIEN.

Evidence for Smectite Clays from MSL SAM Analyses of Mudstone at Yellowknife Bay, Gale Crater, Mars

NASA Astrophysics Data System (ADS)

McAdam, A.; Franz, H.; Mahaffy, P. R.; Eigenbrode, J. L.; Stern, J. C.; Brunner, A.; Sutter, B.; Archer, P. D.; Ming, D. W.; Morris, R. V.; Atreya, S. K.; Team, M.

2013-12-01

Drilled samples of mudstone from the Sheepbed unit at Yellowknife Bay were analyzed by MSL instruments including the Sample Analysis at Mars (SAM) and Chemistry and Mineralogy (CheMin) instruments in MSL's Analytical Laboratory. CheMin analyses revealed the first in situ X-ray diffraction based evidence of clay minerals on Mars, which are likely trioctahedral smectites (e.g., saponite) and comprise ~20% of the mudstone sample (e.g., Bristow et al., this meeting). SAM analyses, which heated the mudstone samples to 1000oC and monitored volatiles evolved to perform in situ evolved gas analysis mass spectrometry (EGA-MS), resulted in a H2O trace exhibiting a wide evolution at temperatures <500oC, and an evolution peak at higher temperatures near ~750oC. The low temperature H2O evolution has many potential contributors, including adsorbed H2O, smectite interlayer H2O, and structural H2O/OH from bassanite and akaganeite (identified by CheMin) and H2O/OH from amorphous phases in the sample. The high temperature H2O is consistent with the evolution of H2O from the dehydroxylation of the smectite clay mineral. Comparison to EGA-MS data collected under SAM-like conditions on a variety of clay mineral reference materials indicate that a trioctahedral smectite, such as saponite, is most consistent with the high temperature H2O evolution observed. There may also be SAM EGA-MS evidence for a small high temperature H2O evolution from scoop samples from the Yellowknife Bay Rocknest sand shadow bedform. As in the mudstone samples, this evolution may indicate the detection of smectite clays, and the idea that minor clays may be present in Rocknest materials that could be expected to be at least partially derived from local sources is reasonable. But, because smectite clays were not definitively observed in CheMin analyses of Rocknest materials, they must be present at much lower abundances than the ~20% observed in the mudstone samples. This potential detection underscores the complementary nature of the MSL CheMin and SAM instruments for investigations of martian sample mineralogy. Information on the nature of Yellowknife Bay clay minerals may also be available from the detection of H2 evolved during SAM EGA-MS at high temperature. A likely source of at least some of this H2 is H2O evolved from the smectite clays at high temperature, and it is possible these evolutions can be used in a similar fashion to high temperature H2O releases to provide constraints on the clay minerals in a sample. In addition, the D/H of this high temperature H2, as well as the H2O, can be derived from SAM MS and Tunable Laser Spectrometer (TLS) data, respectively. These D/H values may help to inform the provenance of high and low temperature water evolved from martian samples (Mahaffy et al., this meeting).

XRD and SEM study of alumina silicate porcelain insulator

NASA Astrophysics Data System (ADS)

Duddi, Dharmender; Singh, G. P.; Kalra, Swati; Shekhawat, M. S.; Tak, S. K.

2018-05-01

Higher strength electrical porcelain is a requirement of industry. This will be achieved by a specific composition of raw materials, which is consisted of clays and feldspars. Water absorption, particle size and insulating properties are of special interest now a day. China clay, Ball clay and Quartz are widely used by ceramic industries in Bikaner district of Rajasthan. Sample for present study were prepared by mixing of above clay, feldspar with MnO2, then shrinkage is observed. Bar shaped samples were prepared and heated up to a temperature of about 1185° C to observe shrinkage. For phase study of XRD and SEM are observed.

The Influence of SAND’s Gradation and Clay Content of Direct Sheart Test on Clayey Sand

NASA Astrophysics Data System (ADS)

Wibisono, Gunawan; Agus Nugroho, Soewignjo; Umam, Khairul

2018-03-01

The shear strength of clayey-sand can be affected by several factors, e.g. gradation, density, moisture content, and the percentage of clay and sand fraction. The same percentage of clay and sand fraction in clayey-sand mixtures may have different shear strengths due to those factors. This research aims to study the effect of clay content on sand that cause the change of its shear strength. Samples consisted of different clay and sand fractions were reconstituted at a certain moisture content. Sand fractions varied from well-graded to poorly-graded sand. Shear strength was measured in terms of the direct shear test. Prior to the test, surcharge loads were applied to represent overburden pressures. Shear strength results and their components (i.e. Cohesion and internal angle of friction) were correlated with physical properties of samples (i.e. grading coefficient of curvature, coefficient of uniformity, and density). Results showed that samples classified as well-graded and dense sand had higher shear strength. In the other hand, the shear strengths decreased when the mixtures became poorly-graded and less dense. The inclusion of the clay fraction increased cohesion component and decreased internal angle of friction.

Optical Methods for Identifying Hard Clay Core Samples During Petrophysical Studies

NASA Astrophysics Data System (ADS)

Morev, A. V.; Solovyeva, A. V.; Morev, V. A.

2018-01-01

X-ray phase analysis of the general mineralogical composition of core samples from one of the West Siberian fields was performed. Electronic absorption spectra of the clay core samples with an added indicator were studied. The speed and availability of applying the two methods in petrophysical laboratories during sample preparation for standard and special studies were estimated.

Permeability Evolution With Shearing of Simulated Faults in Unconventional Shale Reservoirs

NASA Astrophysics Data System (ADS)

Wu, W.; Gensterblum, Y.; Reece, J. S.; Zoback, M. D.

2016-12-01

Horizontal drilling and multi-stage hydraulic fracturing can lead to fault reactivation, a process thought to influence production from extremely low-permeability unconventional reservoir. A fundamental understanding of permeability changes with shear could be helpful for optimizing reservoir stimulation strategies. We examined the effects of confining pressure and frictional sliding on fault permeability in Eagle Ford shale samples. We performed shear-flow experiments in a triaxial apparatus on four shale samples: (1) clay-rich sample with sawcut fault, (2) calcite-rich sample with sawcut fault, (3) clay-rich sample with natural fault, and (4) calcite-rich sample with natural fault. We used pressure pulse-decay and steady-state flow techniques to measure fault permeability. Initial pore and confining pressures are set to 2.5 MPa and 5.0 MPa, respectively. To investigate the influence of confining pressure on fault permeability, we incrementally raised and lowered the confining pressure and measure permeability at different effective stresses. To examine the effect of frictional sliding on fault permeability, we slide the samples four times at a constant shear displacement rate of 0.043 mm/min for 10 minutes each and measure fault permeability before and after frictional sliding. We used a 3D Laser Scanner to image fault surface topography before and after the experiment. Our results show that frictional sliding can enhance fault permeability at low confining pressures (e.g., ≥5.0 MPa) and reduce fault permeability at high confining pressures (e.g., ≥7.5 MPa). The permeability of sawcut faults almost fully recovers when confining pressure returns to the initial value, and increases with sliding due to asperity damage and subsequent dilation at low confining pressures. In contrast, the permeability of natural faults does not fully recover. It initially increases with sliding, but then decreases with further sliding most likely due to fault gouge blocking fluid pathways.

Cyclic deformations in the Opalinus clay: a laboratory experiment

NASA Astrophysics Data System (ADS)

Huber, Emanuel; Huggenberger, Peter; Möri, Andreas; Meier, Edi

2015-04-01

The influence of tunnel climate on deformation cycles of joint openings and closings is often observed immediately after excavation. At the EZ-B niche in the Mt. Terri rock laboratory (Switzerland), a cyclic deformation of the shaly Opalinus clay has been monitored for several years. The deformation cycles of the joints parallel to the clay bedding planes correlate with seasonal variations in relative humidity of the air in the niche. In winter, when the relative humidity is the lowest (down to 65%), the joints open as the clay volume decreases, whereas they tend to close in the summer when the relative humidity reaches up to 100%. Furthermore, in situ measurements have shown the trend of an increasingly smaller aperture of joints with time. A laboratory experiment was carried out to reproduce the observed cyclic deformation in a climate chamber using a core sample of Opalinus clay. The main goal of the experiment was to investigate the influence of the relative humidity on the deformation of the Opalinus clay while excluding the in situ effects (e.g. confining stress). The core sample of Opalinus clay was put into a closed ended PVC tube and the space between the sample and the tube was filled with resin. Then, the sample (size: 28 cm × 14 cm × 6.5 cm) was cut in half lengthways and the open end was cut, so that the half-core sample could move in one direction. The mounted sample was exposed to wetting and drying cycles in a climate chamber. Air temperature, air humidity and sample weight were continuously recorded. Photographs taken at regular time intervals by a webcam allowed the formation/deformation of cracks on the surface of the sample to be monitored. A crackmeter consisting of a double-plate capacitor attached to the core sample was developed to measure the dynamics of the crack opening and closing. Preliminary results show that: - Deformation movements during different climate cycles can be visualized with the webcam - The crackmeter signal gives a relatively precise response for relative humidity below 80% - The sample weight variations are clearly related to the climatic conditions (temperature and relative humidity) and associated with deformation of the sample (widening and narrowing of the cracks) - The control of the relative humidity in the climate chamber turned out to be difficult in a laboratory without climate conditioning, especially during summer time

Modified clay sorbents for wastewater treatment and immobilization of heavy metals in soils

NASA Astrophysics Data System (ADS)

Burlakovs, Juris; Klavins, Maris; Vincevica-Gaile, Zane; Stapkevica, Mara

2014-05-01

Soil and groundwater pollution with heavy metals is the result of both, anthropogenic and natural processes in the environment. Anthropogenic influence in great extent appears from industry, mining, treatment of metal ores and waste incineration. Contamination of soil and water can be induced by diffuse sources such as applications of agrochemicals and fertilizers in agriculture, air pollution from industry and transport, and by point sources, e.g., wastewater streams, runoff from dump sites and factories. Treatment processes used for metal removal from polluted soil and water include methodologies based on chemical precipitation, ion exchange, carbon adsorption, membrane filtration, adsorption and co-precipitation. Optimal removal of heavy metal ions from aqueous medium can be achieved by adsorption process which is considered as one of the most effective methods due to its cost-effectiveness and high efficiency. Immobilization of metals in contaminated soil also can be done with different adsorbents as the in situ technology. Use of natural and modified clay can be developed as one of the solutions in immobilization of lead, zinc, copper and other elements in polluted sites. Within the present study clay samples of different geological genesis were modified with sodium and calcium chlorides, iron oxyhydroxides and ammonium dihydrogen phosphate in variable proportions of Ca/P equimolar ratio to test and compare immobilization efficiency of metals by sorption and batch leaching tests. Sorption capacity for raw clay samples was considered as relatively lower referring to the modified species of the same clay type. In addition, clay samples were tested for powder X-ray difractometry, cation exchange, surface area properties, elemental composition, as well as scanning electron microscopy pictures of clay sample surface structures were obtained. Modified clay sorbents were tested for sorption of lead as monocontaminant and for complex contamination of heavy metals. The highest sorption capacity was observed for clay modified with hydroxyapatite and calcium salts. Sorption capacity increased with a rise of temperature; the best pH value for sorption was 5. Immobilization of metals in soil, as well as industrial wastewater treatment can be accomplished by using sorbents on modified clay basis.

Surveying Clay Mineral Diversity in the Murray Formation, Gale Crater, Mars

NASA Technical Reports Server (NTRS)

Bristow, T.F.; Blake, D. F..; Vaniman, D. T.; Chipera, S. J.; Rampe, E. B.; Grotzinger, J. P.; McAdam, A. C.; Ming, D. W..; Morrison, S. M.; Yen, A. S.;

The Effect of Traditional Treatments on Heavy Metal Toxicity of Armenian Bole

PubMed Central

Hosamo, Ammar; Zarshenas, Mohammad Mehdi; Mehdizadeh, Alireza; Zomorodian, Kamiar; Khani, Ayda Hossein

2016-01-01

Background: Clay has been used for its nutrition, cosmetic, and antibacterial properties for thousands of years. Its small particle size, large surface area, and high concentration of ions have made it an interesting subject for pharmaceutical research. There have been studies on scavenging foreign substances and antibacterial properties of clay minerals. The main problem with the medical use of these agents, today, is their heavy metal toxicity. This includes arsenic, cadmium, lead, nickel, zinc, and iron. Iranian traditional medicine (ITM) introduces different clays as medicaments. In this system, there are specific processes for these agents, which might reduce the chance of heavy metal toxicity. Armenian bole is a type of clay that has been used to treat a wound. Before in vivo studies of this clay, its safety should be confirmed. Methods: In this work, we investigated the effect of washing process as mentioned in ITM books regarding the presence of Pb, As, and Cd in 5 samples using atomic absorption spectrometry. We washed each sample (50 g) with 500 cc of distilled water. The samples were filtered and dried at room temperature for 24 hours. Results: In all studied samples, the amount of Pb and Cd was reduced after the ITM washing process. The amount of As was reduced in 3 samples and increased in 2 other samples. Conclusion: In ITM books, there are general considerations for the use of medicinal clay. These agents should not be used before special treatments such as the washing process. In this study, we observed the effect of washing process on reducing the amount of heavy metals in Armenian bole samples. In two samples, washing caused an increase in the amount of As. As these heavy metals sediment according to their density in different layers, the sample layer on which the spectrometry is performed could have an effect on the results. PMID:27840531

The Effect of Traditional Treatments on Heavy Metal Toxicity of Armenian Bole

PubMed Central

Hosamo, Ammar; Zarshenas, Mohammad Mehdi; Mehdizadeh, Alireza; Zomorodian, Kamiar; Khani, Ayda Hossein

2016-01-01

Background: Clay has been used for its nutrition, cosmetic, and antibacterial properties for thousands of years. Its small particle size, large surface area, and high concentration of ions have made it an interesting subject for pharmaceutical research. There have been studies on scavenging foreign substances and antibacterial properties of clay minerals. The main problem with the medical use of these agents, today, is their heavy metal toxicity. This includes arsenic, cadmium, lead, nickel, zinc, and iron. Iranian traditional medicine (ITM) introduces different clays as medicaments. In this system, there are specific processes for these agents, which might reduce the chance of heavy metal toxicity. Armenian bole is a type of clay that has been used to treat a wound. Before in vivo studies of this clay, its safety should be confirmed. Methods: In this work, we investigated the effect of washing process as mentioned in ITM books regarding the presence of Pb, As, and Cd in 5 samples using atomic absorption spectrometry. We washed each sample (50 g) with 500 cc of distilled water. The samples were filtered and dried at room temperature for 24 hours. Results: In all studied samples, the amount of Pb and Cd was reduced after the ITM washing process. The amount of As was reduced in 3 samples and increased in 2 other samples. Conclusion: In ITM books, there are general considerations for the use of medicinal clay. These agents should not be used before special treatments such as the washing process. In this study, we observed the effect of washing process on reducing the amount of heavy metals in Armenian bole samples. In two samples, washing caused an increase in the amount of As. As these heavy metals sediment according to their density in different layers, the sample layer on which the spectrometry is performed could have an effect on the results. PMID:27516695

The Effect of Traditional Treatments on Heavy Metal Toxicity of Armenian Bole.

PubMed

Hosamo, Ammar; Zarshenas, Mohammad Mehdi; Mehdizadeh, Alireza; Zomorodian, Kamiar; Khani, Ayda Hossein

2016-05-01

Clay has been used for its nutrition, cosmetic, and antibacterial properties for thousands of years. Its small particle size, large surface area, and high concentration of ions have made it an interesting subject for pharmaceutical research. There have been studies on scavenging foreign substances and antibacterial properties of clay minerals. The main problem with the medical use of these agents, today, is their heavy metal toxicity. This includes arsenic, cadmium, lead, nickel, zinc, and iron. Iranian traditional medicine (ITM) introduces different clays as medicaments. In this system, there are specific processes for these agents, which might reduce the chance of heavy metal toxicity. Armenian bole is a type of clay that has been used to treat a wound. Before in vivo studies of this clay, its safety should be confirmed. In this work, we investigated the effect of washing process as mentioned in ITM books regarding the presence of Pb, As, and Cd in 5 samples using atomic absorption spectrometry. We washed each sample (50 g) with 500 cc of distilled water. The samples were filtered and dried at room temperature for 24 hours. In all studied samples, the amount of Pb and Cd was reduced after the ITM washing process. The amount of As was reduced in 3 samples and increased in 2 other samples. In ITM books, there are general considerations for the use of medicinal clay. These agents should not be used before special treatments such as the washing process. In this study, we observed the effect of washing process on reducing the amount of heavy metals in Armenian bole samples. In two samples, washing caused an increase in the amount of As. As these heavy metals sediment according to their density in different layers, the sample layer on which the spectrometry is performed could have an effect on the results.

Dielectrophoretic sample preparation for environmental monitoring of microorganisms: Soil particle removal.

PubMed

Fatoyinbo, Henry O; McDonnell, Martin C; Hughes, Michael P

2014-07-01

Detection of pathogens from environmental samples is often hampered by sensors interacting with environmental particles such as soot, pollen, or environmental dust such as soil or clay. These particles may be of similar size to the target bacterium, preventing removal by filtration, but may non-specifically bind to sensor surfaces, fouling them and causing artefactual results. In this paper, we report the selective manipulation of soil particles using an AC electrokinetic microfluidic system. Four heterogeneous soil samples (smectic clay, kaolinitic clay, peaty loam, and sandy loam) were characterised using dielectrophoresis to identify the electrical difference to a target organism. A flow-cell device was then constructed to evaluate dielectrophoretic separation of bacteria and clay in a continous flow through mode. The average separation efficiency of the system across all soil types was found to be 68.7% with a maximal separation efficiency for kaolinitic clay at 87.6%. This represents the first attempt to separate soil particles from bacteria using dielectrophoresis and indicate that the technique shows significant promise; with appropriate system optimisation, we believe that this preliminary study represents an opportunity to develop a simple yet highly effective sample processing system.

Computational and experimental study of atmospheric moisture in ceramic blocks filled with waste fibres in winter season

NASA Astrophysics Data System (ADS)

Stastnik, S.

2016-06-01

Development of materials for vertical outer building structures tends to application of hollow clay blocks filled with some appropriate insulation material. Ceramic fittings provide high thermal resistance, but the walls built from them suffer from condensation of air humidity in winter season frequently. The paper presents the computational simulation and experimental laboratory validation of moisture behaviour of such masonry with insulation prepared from waste fibres under the Central European climatic conditions.

Revisiting the block method for evaluating thermal conductivities of clay and granite

USDA-ARS?s Scientific Manuscript database

Determination of thermal conductivities of porous media using the contact method is revisited and revalidated with consideration of thermal contact resistance. Problems that limit the accuracy of determination of thermal conductivities of porous media are discussed. Thermal conductivities of granite...

ESS/Special Education Teacher's Guide.

ERIC Educational Resources Information Center

Ball, Daniel W.

This teacher's guide provides Elementary Science Study (ESS) units that can be used with students in grades 1-12 in special education programs. The ESS units represent an interdisciplinary approach to learning and emphasize "hands-on" activities. Activities include Mirror Cards, Pattern Blocks, Clay Boats, Mapping, Earthworms, and…

Publications - GMC 41 | Alaska Division of Geological & Geophysical Surveys

Science.gov Websites

DGGS GMC 41 Publication Details Title: X-ray diffraction clay mineralogy analysis of core samples from Unknown, [n.d.], X-ray diffraction clay mineralogy analysis of core samples from Mobil West Staines State

Frictional Behavior of Altered Basement Approaching the Nankai Trough

NASA Astrophysics Data System (ADS)

Saffer, D. M.; Ikari, M.; Rooney, T. O.; Marone, C.

2017-12-01

The frictional behavior of basement rocks plays an important role in subduction zone faulting and seismicity. This includes earthquakes seaward of the trench, large megathrust earthquakes where seamounts are subducting, or where the plate interface steps down to basement. In exhumed subduction zone rocks such as the Shimanto complex in Japan, slivers of basalt are entrained in mélange which is evidence of basement involvement in the fault system. Scientific drilling during the Nankai Trough Seismogenic Zone Experiment (NanTroSEIZE) recovered basement rock from two reference sites (C0011 and C0012) located seaward of the trench offshore the Kii Peninsula during Integrated Ocean Discovery Program (IODP) Expeditions 322 and 333. The basement rocks are pillow basalts that appear to be heterogeneously altered, resulting in contrasting dense blue material and more vesicular gray material. Major element geochemistry shows differences in silica, calcium oxides and loss-on-ignition between the two types of samples. Minor element geochemistry reveals significant differences in vanadium, chromium, and barium. X-ray diffraction on a bulk sample powder representing an average composition shows a phyllosilicate content of 20%, most of which is expandable clays. We performed laboratory friction experiments in a biaxial testing apparatus as either intact sample blocks, or as gouge powders. We combine these experiments with measurements of Pennsylvania slate for comparison, including a mixed-lithology intact block experiment. Intact Nankai basement blocks exhibit a coefficient of sliding friction of 0.73; for Nankai basement powder, slate powder, slate blocks and slate-on-basement blocks the coefficient of sliding friction ranges from 0.44 to 0.57. At slip rates ranging from 3x10-8 to 3x10-4 m/s we observe predominantly velocity-strengthening frictional behavior, indicating a tendency for stable slip. At rates of < 1x10-6 m/s some velocity-weakening was observed, specifically in intact rock-on-rock experiments. Our results show that basement alteration tends to reduce the tendency for unstable slip, but that the altered Nankai basement may still exhibit seismogenic behavior in the case of localized slip in competent rock.

Landslides and Volcanoes: Fingerprinting Erosional Processes on a tropical island, Dominica, Lesser Antilles

NASA Astrophysics Data System (ADS)

Tomenchok, K.; Hill, M.; Jimerson, C.; Talbot-Wendlandt, , H.; Schmidt, A.; Frey, H. M.

2017-12-01

With 9 active volcanic centers, frequent tropical storms, and widespread landslides, the topography of Dominica is rugged and dynamic. This study aims to fingerprint sediment source dynamics in this relatively unstudied region with fallout radionuclides, clay mineralogy, and acid-extractable grain coating concentration measured in detrital sediments. We also aim to measure basin average erosion rates and determine river incision rates into the underlying ignimbrites. Baseline data on the effects of volcanoes, landslides, land use, and topography in setting erosional dynamics will be established. We sampled outlets of 20 large (>10 km2) rivers as well as 11 points in the Roseau River watershed for a network analysis. Block and ash flows and ignimbrites underlie 89% of the study area. Steep topography (mean slope = 19.6˚) and high levels of rainfall (mean annual rainfall = 1981.41 mm) are consistent throughout the 89% forested island. 934 landslides affect 13% of the study area. We hypothesize that basin average parameters and landslide frequency will correlate with erosion rates and fallout radionuclide activities. In addition, we used topographic data and published ignimbrite ages to calculate river incision rates that ranged from 0.448 - 113.9 mm/yr in the north and 0.86 - 44 mm/yr in the south. Basin average erosion rates will be compared to incision rates to quantify differences between basin wide erosional and river incision processes. We will fingerprint sediment sources with 7Be, 210Pbex, and 137Cs, concentration of grain coatings, and clay mineralogy. We hypothesize that watersheds with erosion from stabilizing landslide scars will have high 7Be, low 210Pbex and 137Cs, low concentrations of grain coatings, and less weathered clays. Watersheds with river bank/scarp erosion or active landslides will have little 7Be, 210Pbex, and 137Cs, less weathered clays, and low concentrations of grain coatings. Watersheds with widespread surface erosion will have high activities, weathered clays, and high concentrations of grain coatings. We will correlate basin average statistics with measured fingerprints to provide a better understanding of sediment source dynamics in an understudied region of the world. With the potential for future landslides, further information will advance hazard mitigation in Dominica.

Low frequency complex dielectric (conductivity) response of dilute clay suspensions: Modeling and experiments.

PubMed

Hou, Chang-Yu; Feng, Ling; Seleznev, Nikita; Freed, Denise E

2018-09-01

In this work, we establish an effective medium model to describe the low-frequency complex dielectric (conductivity) dispersion of dilute clay suspensions. We use previously obtained low-frequency polarization coefficients for a charged oblate spheroidal particle immersed in an electrolyte as the building block for the Maxwell Garnett mixing formula to model the dilute clay suspension. The complex conductivity phase dispersion exhibits a near-resonance peak when the clay grains have a narrow size distribution. The peak frequency is associated with the size distribution as well as the shape of clay grains and is often referred to as the characteristic frequency. In contrast, if the size of the clay grains has a broad distribution, the phase peak is broadened and can disappear into the background of the canonical phase response of the brine. To benchmark our model, the low-frequency dispersion of the complex conductivity of dilute clay suspensions is measured using a four-point impedance measurement, which can be reliably calibrated in the frequency range between 0.1 Hz and 10 kHz. By using a minimal number of fitting parameters when reliable information is available as input for the model and carefully examining the issue of potential over-fitting, we found that our model can be used to fit the measured dispersion of the complex conductivity with reasonable parameters. The good match between the modeled and experimental complex conductivity dispersion allows us to argue that our simplified model captures the essential physics for describing the low-frequency dispersion of the complex conductivity of dilute clay suspensions. Copyright © 2018 Elsevier Inc. All rights reserved.

Adsorption of lead onto smectite from aqueous solution.

PubMed

Mhamdi, M; Galai, H; Mnasri, N; Elaloui, E; Trabelsi-Ayadi, M

2013-03-01

The purpose of this research is to study the effect of a new method of adsorption using membrane filtration to determine the maximum amount of lead adsorbed by clay and investigate the behavior of the clay after adsorption of the said metal. Treatment of wastewater contaminated with heavy metals depends on the characteristics of the effluent, the amount of final discharge, the cost of treatment, and the compatibility of the treatment process. The process of adsorption of heavy metals by clays may be a simple, selective, and economically viable alternative to the conventional physical-chemical treatment. This is justified by the importance of the surface developed by this material, the presence of negative charges on the said surface, the possibility of ion exchange taking place, and its wide availability in nature. The removal of lead from wastewater was studied by using the adsorption technique and using clay as the adsorbent. A method was optimized for adsorption through a membrane approaching natural adsorption. This new method is simple, selective, and the lead adsorption time is about 3 days. The various properties of clay were determined. It was observed that the cation exchange capacity of the clay was 56 meq/100 g of hydrated clay for the raw sample and 82 meq/100 g for the purified sample. The total surface area determined by the methylene blue method was equal to 556 and 783 m(2)/g for the raw and purified samples, respectively. The adsorption kinetics depends on several parameters. The Pb(II) clay, obeys the Langmuir, Freundlich, and the Elovich adsorption isotherms with high regression coefficients. The use of this adsorbent notably decreases the cost of treatment. It was concluded that clay shows a strong adsorption capacity on Pb(II), the maximum interaction occurring with purified clay treated at high concentration of lead. It is proposed that this adsorption through a membrane be extended for the treatment of effluents containing other metals.

46 CFR 164.009-3 - Noncombustible materials not requiring specific approval.

Code of Federal Regulations, 2010 CFR

2010-10-01

... subpart: (a) Sheet glass, block glass, clay, ceramics, and uncoated fibers. (b) All metals, except... only sand, gravel, expanded vermiculite, expanded or vesicular slags, diatomaceous silica, perlite, or pumice. (d) Woven, knitted or needle punched glass fabric containing no additives other than lubricants...

46 CFR 164.009-3 - Noncombustible materials not requiring specific approval.

Code of Federal Regulations, 2011 CFR

2011-10-01

... Merchant Vessels § 164.009-3 Noncombustible materials not requiring specific approval. The following noncombustible materials may be used in merchant vessel construction though not specifically approved under this subpart: (a) Sheet glass, block glass, clay, ceramics, and uncoated fibers. (b) All metals, except...

Measuring the isoelectric point of the edges of clay mineral particles: the case of montmorillonite.

PubMed

Pecini, Eliana M; Avena, Marcelo J

2013-12-03

The isoelectric point (IEP) of the edge surface of a montmorillonite sample was determined by using electrophoretic mobility measurements. This parameter, which is fundamental for the understanding of the charging behavior of clay mineral surfaces, was never measured so far because of the presence of permanent negative charges within the montmorillonite structure, charges that mask the electrokinetic behavior of the edges. The strategy was to block or neutralize the structural charges with two different cations, methylene blue (MB(+)) and tetraethylenepentaminecopper(II) ([Cu(tetren)](2+)), so that the charging behavior of the particles becomes that of the edge surfaces. Adsorption isotherms of MB(+) and [Cu(tetren)](2+) at different ionic strengths (NaCl) were performed to establish the uptakes that neutralize the cation exchange capacity (CEC, 0.96 meq g(-1)) of the sample. At high adsorptive concentrations, there was a superequivalent adsorption of MB(+) (adsorption exceeding the CEC) and an equivalent adsorption of [Cu(tetren)](2+) (adsorption reaching the CEC). In both cases, structural charges were neutralized at uptakes very close to the CEC. Zeta potential (ζ) vs pH data at different ionic strengths of montmorillonite with adsorbed MB(+) allowed to estimate an upper limit of the edge's IEP, 5.3 ± 0.2. The same kind of data obtained with adsorbed [Cu(tetren)](2+) provided a lower limit of the IEP, 4.0 ± 0.2. These values are in agreement with previously informed IEP and point of zero charge of pyrophyllite, which is structurally analogous to montmorillonite but carries no permanent charges. The importance of knowing the IEP of the edge surface of clay minerals is discussed. This value characterizes the intrinsic reactivity of edges, that is, the protonating capacity of edge groups in absence of any electric field generated by structural charges. It also allows us to correct relative edge charge vs pH curves obtained by potentiometric titrations and to obtain the true edge charge vs pH curves at different electrolyte concentrations.

Hyperspectral analysis of clay minerals

NASA Astrophysics Data System (ADS)

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

2014-11-01

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 μm 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.

Effect of the platinum content on the microstructure and micropore size distribution of Pt/alumina-pillared clays.

PubMed

Barrera-Vargas, M; Valencia-Rios, J; Vicente, M A; Korili, S A; Gil, A

2005-12-15

The aim of this work is to study the effect of the platinum content (0-1.8 wt % Pt) on the microstructure of an alumina-pillared clay. For this purpose, the nitrogen physisorption data at -196 degrees C, the micropore size distributions of the supported platinum catalysts, and the hydrogen chemisorption results at 30 degrees C have been analyzed and compared. The preparation of the catalysts has modified the textural properties of the Al-pillared clay support, giving rise to a loss of surface area and micropore volume. After reduction at 420 degrees C, the presence of dispersed metallic platinum with mean crystallite size in the 22-55 A range has been found by hydrogen adsorption. Comparison of all results reveals that the platinum species block the micropore entrances by steric hindrance to nitrogen access as the platinum content increases.

Mineralogical characterization of Greda clays and monitoring of their phase transformations on thermal treatment

NASA Astrophysics Data System (ADS)

Panduro, E. Chavez; Cabrejos, J. Bravo

2010-01-01

The mineralogical characterization of two clay samples from the Central Andean Region of Peru, denominated White Greda and Red Greda, is reported. These clays contain the clay minerals mica and illite respectively. Both clays were treated thermally in an oxidising atmosphere under controlled conditions up to 1,100°C with the purpose of obtaining information about structural changes that may be useful for pottery manufacture. X-ray fluorescence was used for the elemental characterization of the samples and X-ray diffractometry was used to determine the collapse and formation of the mineral phases present in the samples caused by thermal treatment. At temperatures above 1,000°C it is observed the formation of spinel in the case of White Greda and of hematite, corundum and cristobalite in the case of Red Greda. Room temperature transmission Mössbauer spectroscopy allowed the monitoring of the variation of the hyperfine parameters with the thermal treatment temperature; In the case of the evolution of the quadruple splitting of the paramagnetic Fe3 + sites with temperature, in both clays, the analyses reproduced results such as the “camel back” curve shape, found by other workers (Wagner and Wagner, Hyperfine Interact 154:35-82, 2004; Wagner and Kyek, Hyperfine Interact 154:5-33, 2004).

The prehistoric Vajont rockslide: An updated geological model

NASA Astrophysics Data System (ADS)

Paronuzzi, Paolo; Bolla, Alberto

2012-10-01

This study presents the detailed reconstruction of the entire structure of the prehistoric Vajont rockslide (about 270-300 million m3 of rocks and debris) for the first time, describing the complex geometry and the characteristic superimposition of distinct rigid blocks on a very thick shear zone. The prehistoric Vajont rockslide was characterized by an enormous 'en masse' motion of a rigid overlying rock mass (100-130 m thick) that moved downslope, sliding onto a very thick shear zone (40-50 m thick, on average) made up of a chaotic assemblage of blocks, limestone angular gravel, and high plasticity clays (montmorillonitic clays). Coarse loose sediments, still exposed on the 9 October 1963 detachment surface, are always associated with large blocks made of strongly fractured rock masses (Fonzaso Formation: middle-upper Jurassic) preserving the stratification. The blocks of stratified and folded limestone sequences appear to be 'sheared off' from the underlying bedrock and can be considered as displaced rock masses planed off by the motion of the overlying rigid rock mass ('rock mass shavings'). The prehistoric Vajont rockslide was characterized by a multistage failure with a marked retrogressive evolution. The first rupture (Pian del Toc block) rapidly destabilized the upper slope, mobilizing a second rock mass block (Pian della Pozza block) that, in turn, determined the multiple rupture of the revealed shear zone material (Massalezza lobe). Even if the exact timing of the different phases is not known, the entire multistaged failure process was very rapid. At the end of the multistage retrogressive failure, the slope morphology of the northern toe of Mt. Toc was drastically changed and the large failed rock mass settled into the preexisting Vajont Valley assuming the unusual chair-like geometry. The Vajont rockslide represents a very significant example on how a complex geological situation, if not adequately analyzed and reconstructed, can lead to dangerous misinterpretations or even to erroneous engineering-geological and geotechnical models. Accurate fieldwork and modern technologies can be fundamental in solving such a very intriguing 'geological puzzle.'

A parametric study on hydraulic conductivity and self-healing properties of geotextile clay liners used in landfills.

PubMed

Parastar, Fatemeh; Hejazi, Sayyed Mahdi; Sheikhzadeh, Mohammad; Alirezazadeh, Azam

2017-11-01

Nowadays, the raise of excessive generation of solid wastes is considered as a major environmental concern due to the fast global population growth. The contamination of groundwater from landfill leachate compromises every living creature. Geotextile clay liner (GCL) that has a sandwich structure with two fibrous sheets and a clay core can be considered as an engineered solution to prevent hazardous pollutants from entering into groundwater. The main objective of the present study is therefore to enhance the performance of GCL structures. By changing some structural factors such as clay type (sodium vs. calcium bentonite), areal density of clay, density of geotextile, geotextile thickness, texture type (woven vs. nonwoven), and needle punching density a series of GCL samples were fabricated. Water pressure, type of cover soil and overburden pressure were the environmental variables, while the response variables were hydraulic conductivity and self-healing rate of GCL. Rigid wall constant head permeability test was conducted on all the samples. The outlet water flow was measured and evaluated at a defined time period and the hydraulic conductivity was determined for each sample. In the final stage, self-healing properties of samples were investigated and an analytical model was used to explain the results. It was found that higher Montmorillonite content of clay, overburden pressure, needle punching density and areal density of clay poses better self-healing properties and less hydraulic conductivity, meanwhile, an increase in water pressure increases the hydraulic conductivity. Moreover, the observations were aligned with the analytical model and indicated that higher fiber inclusion as a result of higher needle-punching density produces closer contact between bentonite and fibers, reduces hydraulic conductivity and increases self-healing properties. Copyright © 2017 Elsevier Ltd. All rights reserved.

Efficiency of a borehole seal by means of pre-compacted bentonite blocks

NASA Astrophysics Data System (ADS)

Van Geet, M.; Volckaert, G.; Bastiaens, W.; Maes, N.; Weetjens, E.; Sillen, X.; Vallejan, B.; Gens, A.

The backfilling and sealing of shafts and galleries is an essential part of the design of underground repositories for high-level radioactive waste. Part of the EC funded project RESEAL studied the feasibility of sealing off a borehole in plastic Boom Clay by means of pre-compacted bentonite blocks. Two bentonites, namely the FoCa and Serrata clay, have been used. Based on laboratory tests, the bentonite blocks had an initial dry density of about 1.8 g/cm 3 to obtain a swelling pressure of about 4.4 MPa, corresponding to the in situ lithostatic stress, at full saturation. The set-up was equipped with several sensors to follow-up the behaviour of the seal and the surrounding host rock during hydration. Full saturation was reached after five months and was mainly reached by natural hydration. Swelling pressure was lower than originally foreseen due to the slow reconsolidation of the host rock. Later on, the efficiency of the seal with respect to water, gas and radionuclide migration was tested. The in situ measured permeability of the seals was about 5 × 10 -13 m/s. A gas breakthrough experiment did not show any preferential gas migration through the seal. No evidences of a preferential pathway could be detected from 125I tracer test results.

Improving the Mechanical Performance and Thermal Stability of a PVA-Clay Nanocomposite by Electron Beam Irradiation

NASA Astrophysics Data System (ADS)

Shokuhi Rad, A.; Ebrahimi, D.

2017-07-01

The effects of electron beam irradiation and presence of clay on the mechanical properties and thermal stability of montmorillonite clay-modified polyvinyl alcohol nanocomposites were studied. By using the X-ray diffraction (XRD) and transmission electron microscopy (TEM), the microstructure of the nanocomposites was investigated. The results obtained from TEM and XRD tests showed that montmorillonite clay nanoparticles were located in the polyvinyl alcohol phase. The XRD analysis confirmed the formation of an exfoliated structure in nanocomposites samples. Increasing the amount of clay to 20 wt.% increased the tensile strength and modulus of the nanocomposite. Irradiation up to an absorbed dose of 100 kGy increased its mechanical properties and thermal stability, but at higher irradiation levels, the mechanical strength and thermal stability declined. The sample with 20 wt.% of the nanofiller, exposed to 100 kGy, showed the highest mechanical strength and thermal stability.

Preparation, characterization and application in deep catalytic ODS of the mesoporous silica pillared clay incorporated with phosphotungstic acid.

PubMed

Li, Baoshan; Liu, Zhenxing; Liu, Jianjun; Zhou, Zhiyuan; Gao, Xiaohui; Pang, Xinmei; Sheng, Huiting

2011-10-15

Mesoporous silica pillared clay (SPC) materials with different contents of H(3)PW(12)O(40) (HPW) heteropoly acid were synthesized by introducing HPW into clay interlayer template in an acidic suspension using sol-gel method. Samples with similar HPW loadings were also prepared by impregnation method using SPC as the support. The results of the characterizations showed that HPW was dispersed more homogeneously in the encapsulated samples than in the impregnated samples. The encapsulated materials exhibited better catalytic performance than the impregnated samples in oxidative desulfurization of dibenzothiophene-containing model oil. The sulfur removal reached up to 98.6% for the model oil under the experiential conditions. Copyright © 2011 Elsevier Inc. All rights reserved.

Creep and Sliding in Clay Slopes: Mutual Effects of Interlayer Swelling and Ice Jacking.

DTIC Science & Technology

1983-04-24

calcite and feldspar constituents. Therefore a swelling clay with low diagenetic lithification (matrix forming) e fects. Therefore, the clay shows...were determined quantitatively (Tab. 2). The CEC depends mainly on the montmorillonite content and shows values up to 86 meq/lOOg, which Indicates...high montmorillonite clays. First freezing tests have been performed within a freezer. After freezing, three typical zones within the samples can be

Rare earth element deposits in China

USGS Publications Warehouse

Xie, Yu-Ling; Hou, Zeng-qian; Goldfarb, Richard J.; Guo, Xiang; Wang, Lei

2016-01-01

China is the world’s leading rare earth element (REE) producer and hosts a variety of deposit types. Carbonatite- related REE deposits, the most significant deposit type, include two giant deposits presently being mined in China, Bayan Obo and Maoniuping, the first and third largest deposits of this type in the world, respectively. The carbonatite-related deposits host the majority of China’s REE resource and are the primary supplier of the world’s light REE. The REE-bearing clay deposits, or ion adsorption-type deposits, are second in importance and are the main source in China for heavy REE resources. Other REE resources include those within monazite or xenotime placers, beach placers, alkaline granites, pegmatites, and hydrothermal veins, as well as some additional deposit types in which REE are recovered as by-products. Carbonatite-related REE deposits in China occur along craton margins, both in rifts (e.g., Bayan Obo) and in reactivated transpressional margins (e.g., Maoniuping). They comprise those along the northern, eastern, and southern margins of the North China block, and along the western margin of the Yangtze block. Major structural features along the craton margins provide first-order controls for REE-related Proterozoic to Cenozoic carbonatite alkaline complexes; these are emplaced in continental margin rifts or strike-slip faults. The ion adsorption-type REE deposits, mainly situated in the South China block, are genetically linked to the weathering of granite and, less commonly, volcanic rocks and lamprophyres. Indosinian (early Mesozoic) and Yanshanian (late Mesozoic) granites are the most important parent rocks for these REE deposits, although Caledonian (early Paleozoic) granites are also of local importance. The primary REE enrichment is hosted in various mineral phases in the igneous rocks and, during the weathering process, the REE are released and adsorbed by clay minerals in the weathering profile. Currently, these REE-rich clays are primarily mined from open-pit operations in southern China. The complex geologic evolution of China’s Precambrian blocks, particularly the long-term subduction of ocean crust below the North and South China blocks, enabled recycling of REE-rich pelagic sediments into mantle lithosphere. This resulted in the REE-enriched nature of the mantle below the Precambrian cratons, which were reactivated and thus essentially decratonized during various tectonic episodes throughout the Proterozoic and Phanerozoic. Deep fault zones within and along the edges of the blocks, including continental rifts and strike-slip faults, provided pathways for upwelling of mantle material.

Transport and retention of surfactant- and polymer-stabilized engineered silver nanoparticles in silicate-dominated aquifer material

USDA-ARS?s Scientific Manuscript database

Packed column experiments were conducted to investigate the transport and blocking behavior of surfactant- and polymer-stabilized engineered silver nanoparticles (Ag-ENPs) in saturated natural aquifer material with varying silt and clay content, background solution chemistry, and flow velocity. Brea...

Alphatome--Enhancing Spatial Reasoning: A Simulation in Two and Three Dimensions

ERIC Educational Resources Information Center

LeClair, Elizabeth E.

2003-01-01

Using refrigerator magnets, foam blocks, ink pads, and modeling clay, students manipulate the letters of the alphabet at multiple angles, reconstructing three-dimensional forms from two-dimensional data. This exercise increases students' spatial reasoning ability, an important component in many scientific disciplines. (Contains 5 figures.)

A Simple Boyle's Law Experiment.

ERIC Educational Resources Information Center

Lewis, Don L.

1997-01-01

Describes an experiment to demonstrate Boyle's law that provides pressure measurements in a familiar unit (psi) and makes no assumptions concerning atmospheric pressure. Items needed include bathroom scales and a 60-ml syringe, castor oil, disposable 3-ml syringe and needle, modeling clay, pliers, and a wooden block. Commercial devices use a…

Effect of clay content and mineralogy on frictional sliding behavior of simulated gouges: binary and ternary mixtures of quartz, illite, and montmorillonite

USGS Publications Warehouse

Tembe, Sheryl; Lockner, David A.; Wong, Teng-Fong

2010-01-01

We investigated the frictional sliding behavior of simulated quartz-clay gouges under stress conditions relevant to seismogenic depths. Conventional triaxial compression tests were conducted at 40 MPa effective normal stress on saturated saw cut samples containing binary and ternary mixtures of quartz, montmorillonite, and illite. In all cases, frictional strengths of mixtures fall between the end-members of pure quartz (strongest) and clay (weakest). The overall trend was a decrease in strength with increasing clay content. In the illite/quartz mixture the trend was nearly linear, while in the montmorillonite mixtures a sigmoidal trend with three strength regimes was noted. Microstructural observations were performed on the deformed samples to characterize the geometric attributes of shear localization within the gouge layers. Two micromechanical models were used to analyze the critical clay fractions for the two-regime transitions on the basis of clay porosity and packing of the quartz grains. The transition from regime 1 (high strength) to 2 (intermediate strength) is associated with the shift from a stress-supporting framework of quartz grains to a clay matrix embedded with disperse quartz grains, manifested by the development of P-foliation and reduction in Riedel shear angle. The transition from regime 2 (intermediate strength) to 3 (low strength) is attributed to the development of shear localization in the clay matrix, occurring only when the neighboring layers of quartz grains are separated by a critical clay thickness. Our mixture data relating strength degradation to clay content agree well with strengths of natural shear zone materials obtained from scientific deep drilling projects.

Adsorption coefficients for TNT on soil and clay minerals

NASA Astrophysics Data System (ADS)

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

2007-04-01

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

High Temperature Thermosetting Polyimide Nanocomposites Prepared with Reduced Charge Organoclay

NASA Technical Reports Server (NTRS)

Campbell, Sandi; Liang, Margaret I.

2005-01-01

The naturally occurring sodium and calcium cations found in bentonite clay galleries were exchanged with lithium cations. Following the cation exchange, a series of reduced charge clays were prepared by heat treatment of the lithium bentonite at 130 C, 150 C, or 170 C. Inductively coupled plasma (ICP) analysis showed that heating the lithium clay at elevated temperatures reduced its cation exchange capacity. Ion exchange of heat-treated clays with either a protonated alkyl amine or a protonated aromatic diamine resulted in decreasing amounts of the organic modifier incorporated into the lithium clay. The level of silicate dispersion in a thermosetting polyimide matrix was dependent upon the temperature of Li-clay heat treatment as well as the organic modification. In general, clays treated at 150 C or 170 C, and exchanged with protonated octadcylamine or protonated 2,2'-dimethlybenzidine (DMBZ) showed a higher degree of dispersion than clays treated at 130 C, or exchanged with protonated dodecylamine. Dynamic mechanical analysis showed little change in the storage modulus or T(sub g) of the nanocomposites compared to the base resin. However, long term isothermal aging of the samples showed a significant decrease in the resin oxidative weight loss. Nanocomposite samples aged in air for 1000 hours at 288 C showed of to a decrease in weight loss compared to that of the base resin. This again was dependent on the temperature at which the Li-clay was heated and the choice of organic modification.

Effects of clay on toxin binding capacity, ruminal fermentation, diet digestibility, and growth of steers fed high-concentrate diets.

PubMed

Antonelo, D S; Lancaster, N A; Melnichenko, S; Muegge, C R; Schoonmaker, J P

2017-10-01

Three experiments were conducted to determine the effect of increasing concentrations of a smectite clay on toxin binding capacity, ruminal fermentation, diet digestibility, and growth of feedlot cattle. In Exp. 1, 72 Angus × Simmental steers were blocked by BW (395 ± 9.9 kg) and randomly allotted to 3 treatments (4 pens/treatment and 6 steers/pen) to determine the effects of increasing amounts of clay (0, 1, or 2%) on performance. The clay was top-dressed on an 80% concentrate diet at a rate of 0, 113, or 226 g/steer daily to achieve the 0, 1, and 2% treatments, respectively. Steers were slaughtered at a target BW of 606 kg. In Exp. 2, 6 steers (596 ± 22.2 kg initial BW) were randomly allotted to the same 3 treatments in a replicated 3 × 3 Latin square design (21-d periods) to determine the effects of increasing amounts of clay on ruminal pH, VFA, and nutrient digestibility. In Exp. 3, 150 mg of clay was incubated in 10 mL of rumen fluid with 3 incremental concentrations (6 replicates per concentration) of aflatoxin B (AFB) or ergotamine tartate (ET) to determine binding capacity. During the first 33-d period, there was a quadratic effect of clay on ADG ( < 0.01) and G:F ( < 0.01), increasing from 0 to 1% clay and then decreasing from 1 to 2% clay. However, during the second 30-d period, clay linearly decreased ADG and G:F ( ≤ 0.03) and overall ADG, DMI, and G:F were not impacted ( ≥ 0.46). Clay linearly decreased marbling score ( = 0.05). Hepatic enzyme activity did not differ among treatments on d 0 or at slaughter ( ≥ 0.15). Clay linearly decreased ruminal lactate and propionate, linearly increased formate and the acetate:propionate ratio ( ≤ 0.04), and tended ( = 0.07) to linearly increase butyrate. Clay tended to linearly increase ( = 0.06) OM and CP apparent digestibility. Ruminal pH, urine pH, and other digestibility measures did not differ among treatments ( ≥ 0.15). Clay was able to effectively bind AFB and ET at concentrations above the normal physiological range (52 and 520 μg/mL), but proportional adsorption was decreased to 35.5 and 91.1% at 5,200 μg/mL ( < 0.01) for AFB and ET, respectively. In conclusion, clay effectively binds ruminal toxins, decreases ruminal lactate, and improves performance only during adaptation to a high-concentrate feedlot diet.

Arsenic and lead concentrations in the Pond Creek and Fire Clay coal beds, eastern Kentucky coal field

USGS Publications Warehouse

Hower, J.C.; Robertson, J.D.; Wong, A.S.; Eble, C.F.; Ruppert, L.F.

1997-01-01

The Middle Pennsylvanian Breathitt Formation (Westphalian B) Pond Creek and Fire Clay coal beds are the 2 largest producing coal beds in eastern Kentucky. Single channel samples from 22 localities in the Pond Creek coal bed were obtained from active coal mines in Pike and Martin Countries, Kentucky, and a total of 18 Fire Clay coal bed channel samples were collected from localities in the central portion of the coal field. The overall objective of this study was to investigate the concentration and distribution of potentially hazardous elements in the Fire Clay and Pond Creek coal beds, with particular emphasis on As and Pb, 2 elements that are included in the 1990 Clean Air Act Amendments as potential air toxics. The 2 coals are discussed individually as the depositional histories are distinct, the Fire Clay coal bed having more sites where relatively high-S lithologies are encountered. In an effort to characterize these coals, 40 whole channel samples, excluding 1-cm partings, were analyzed for major, minor and trace elements by X-ray fluorescence and proton-induced X-ray emission spectroscopy. Previously analyzed samples were added to provide additional geographic coverage and lithotype samples from one site were analyzed in order to provide detail of vertical elemental trends. The As and Pb levels in the Fire Clay coal bed tend to be higher than in the Pond Creek coal bed. One whole channel sample of the Fire Clay coal bed contains 1156 ppm As (ash basis), with a single lithotype containing 4000 ppm As (ash basis). Most of the As and Pb appears to be associated with pyrite, which potentially can be removed in beneficiation (particularly coarser pyrite). Disseminated finer pyrite may not be completely removable by cleaning. In the examination of pyrite conducted in this study, it does not appear that significant concentration of As or Pb occurs in the finer pyrite forms. The biggest potential problem of As- or Pb-enriched pyrite is, therefore, one of refuse disposal.

Scanning electron microscopy of clays and clay minerals

USGS Publications Warehouse

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

1971-01-01

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

Integrating auxiliary data and geophysical techniques for the estimation of soil clay content using CHAID algorithm

NASA Astrophysics Data System (ADS)

Abbaszadeh Afshar, Farideh; Ayoubi, Shamsollah; Besalatpour, Ali Asghar; Khademi, Hossein; Castrignano, Annamaria

2016-03-01

This study was conducted to estimate soil clay content in two depths using geophysical techniques (Ground Penetration Radar-GPR and Electromagnetic Induction-EMI) and ancillary variables (remote sensing and topographic data) in an arid region of the southeastern Iran. GPR measurements were performed throughout ten transects of 100 m length with the line spacing of 10 m, and the EMI measurements were done every 10 m on the same transect in six sites. Ten soil cores were sampled randomly in each site and soil samples were taken from the depth of 0-20 and 20-40 cm, and then the clay fraction of each of sixty soil samples was measured in the laboratory. Clay content was predicted using three different sets of properties including geophysical data, ancillary data, and a combination of both as inputs to multiple linear regressions (MLR) and decision tree-based algorithm of Chi-Squared Automatic Interaction Detection (CHAID) models. The results of the CHAID and MLR models with all combined data showed that geophysical data were the most important variables for the prediction of clay content in two depths in the study area. The proposed MLR model, using the combined data, could explain only 0.44 and 0.31% of the total variability of clay content in 0-20 and 20-40 cm depths, respectively. Also, the coefficient of determination (R2) values for the clay content prediction, using the constructed CHAID model with the combined data, was 0.82 and 0.76 in 0-20 and 20-40 cm depths, respectively. CHAID models, therefore, showed a greater potential in predicting soil clay content from geophysical and ancillary data, while traditional regression methods (i.e. the MLR models) did not perform as well. Overall, the results may encourage researchers in using georeferenced GPR and EMI data as ancillary variables and CHAID algorithm to improve the estimation of soil clay content.

2,3,7,8-DIBENZO-P-DIOXINS IN MINED CLAY PRODUCTS ...

EPA Pesticide Factsheets

Ball clay was the source of dioxin contamination discovered in selected chickens analyzed as part of a joint U.S. Department of Agriculture/U.S. Environmental Protection Agency national survey of the U.S. poultry supply conducted in 1997. The affected animals, which had been raised in the southern United States, represented approximately 5% of the national poultry production . All of these chickens and other animal food sources (i.e., farm-raised catfish), similarly contaminated, were fed a diet of animal feed containing ball clay as an anti-caking additive. The clay was mined in northwestern Mississippi within a geological formation referred to as the Mississippi Embayment. Individual raw and processed ball clay samples were analyzed for the presence of the 2,3,7,8-PCDDs/PCDFs. The average toxic equivalents (TEQs) for the raw and processed samples were 1513 and 996 ppt dry weight, respectively. Other mined clay-based products used in animal feeds revealed lower TEQs. All of the products exhibited either an absence of detectable concentrations of 2,3,7,8-PCDFs or concentrations 2-3 orders of magnitude lower than the PCDDs. The isomer distribution, specific isomer identification, and congener profile of the PCDDs in the clay were established and compared to known sources of dioxin contamination. Several unique features of this isomer distribution are characteristic of the clays and are distinguishable from those other known sources. These characteristic

Implications of Smectite Subduction at the Costa Rican Convergent Margin

NASA Astrophysics Data System (ADS)

Cardace, D.; Morris, J. D.; Underwood, M. B.; Spinelli, G.

2003-12-01

Legs 205/170 of the Ocean Drilling Program (ODP) drilled a reference section on the incoming plate and sites at the toe of the sedimentary prism at the Costa Rican convergent margin. Complete sediment subduction has been documented, with the prism described by Leg 205/170 shipboard scientists as a paleoslump prism. Despite sediment subduction, Costa Rican arc lava geochemistry shows little sediment signal. Though subduction erosion has been posited as a mechanism for damping the geochemical sediment signal, this abstract addresses whether the clay content and distribution in the subducting pile can (a) play a role in localizing the decollement and (b) impact subduction of sediment to depth. X-ray diffraction (XRD) analyses of bulk sediment, with biogenic silica determinations, have been carried out for samples from the prism, through the decollement, to the underthrust sediments. Clay fractions have been isolated and silica studied for a subset of these samples. XRD peak areas of bulk samples were transformed into relative abundances via matrix singular value decomposition (Fisher and Underwood, 1995, Proc. ODP, Init. Repts., 156: 29-37), and adjusted following silica determination; volcanic ash has been neglected as a sedimentary component. Average relative weight percents of dominant minerals and biogenic silica (bSiO2) for prism toe units (Site 1040) are: P1A (silty clay, 74.8 m thick) 82 wt% clay, 5 wt% quartz, 13 wt% plagioclase, 0 wt% calcite; P1B (silty clay, 296.4 m thick) 82.1 wt% clay, 6.0 wt% quartz, 10.4 wt% plagioclase, 0 wt% calcite, 1.4 wt% bSiO2. Below the decollement, underthrust abundances are: U1A (clayey diatomite, 13.2 m thick) 82.7 wt% clay, 5.2 wt% quartz, 8.9 wt% plagioclase, 0 wt% calcite, 3.2 wt% bSiO2; U1B (clayey diatomite, 38.2 m thick) 80.7 wt% clay, 4.4 wt% quartz, 6.6 wt% plagioclase, 0 wt% calcite, 8.2 wt% bSiO2; U2 (silty claystone, 57.1 m thick) 84.8 wt% clay, 4.5 wt% quartz, 6.8 wt% plagioclase, 0 wt% calcite, 3.9 wt% bSiO2; U3A (siliceous nannofossil chalk, 18.1 m thick) 44.1 wt% clay, 2.0 wt% quartz, 5.6 wt% plagioclase, 31.8 wt% calcite, 16.5 wt% bSiO2; U3B (siliceous nannofossil chalk, 75.55 m thick) 1.9 wt% clay, 0 wt% quartz, 1.1 wt% plagioclase, 92.4 wt% calcite, 4.7 wt% bSiO2; and U3C (siliceous nannofossil chalk, 80.18 m thick) 6.6 wt% clay, 6.1 wt% quartz, 4.6 wt% plagioclase, 74.1 wt% calcite, 8.7 wt% bSiO2. XRD peak areas for clay fractions of prism samples above and in the decollement (Site 1254 ˜Site 1040, 300-370 mbsf) were transformed into relative weight percent data with Biscaye weighting factors. Smectites ranged from 77-93 wt%, illites ranged from 0-4 wt%, and kaolinites/chlorites ranged from 5-20 wt%. The maximum smectite value was obtained in the lower decollement. Bulk mineralogy data for sediments subducting at Costa Rica show that the prism and uppermost underthrust sediments are 80-93 wt% clay sized minerals. Clay mineralogy suggests that the smectite maximum occurs in the lower decollement and decreases dramatically below. Low biogenic silica abundances persist down core, emphasizing the importance of clays to the subducting section at Costa Rica.

Structure and fault mechanics of the shallow rupture zone of the 2011 Tohoku-oki earthquake, IODP expedition 343/343T (Invited)

NASA Astrophysics Data System (ADS)

Chester, F. M.

2013-12-01

The Japan Trench convergent margin produces frequent large interplate earthquakes greater than M7.5, and is known to display the primary characteristics of non-accretionary margins. The 2011 Mw 9.0 Tohoku-oki earthquake demonstrates the capability of this margin to rupture the full extent of the seismogenic zone and up-dip to the trench axis in a single great event. A variety of observations indicate that the slip magnitude of this rupture increased towards the trench, with 50+ m of slip occurring at the ~20-km-wide frontal prism of accreted sediments and lower trench slope. IODP expedition 343/343T (JFAST) was designed to address fundamental questions of earthquake physics through rapid-response drilling, but also provides new information on sediment accretion and the architecture of the frontal prism. The JFAST drill site is located above a horst block in the subducting plate and 6 km landward from the trench axis; three boreholes were drilled through the prism and across the plate-boundary. Palinspastic reconstruction of the prism structure based on a seismic line through the drill site, logging data, and lithologic and structural observations of core samples document a single dominant décollement that accommodated almost all of the interplate displacement (~3.2 km) at the drill site. The décollement is located in pelagic clay near the base of the incoming sediment section of the subducting plate, and maintains this stratigraphic position trenchward until it enters the graben below the trench axis where it cuts down-section to follow the basal strata. The structure indicates about half the incoming sediment is offscraped onto the leading edge of the prism but similar amount of sediment may be removed from the base of the frontal prism associated with progressive amplification of horsts and grabens more landward below the prism. The localization of nearly all the interplate displacement to a single narrow décollement composed of sheared pelagic clay indicates the décollement is relatively weak over geologic time. Borehole measurements of temperature across the plate boundary confirm the Tohoku earthquake ruptured the décollement and, consistent with results of high-speed friction experiments on sheared clay, that the décollement is extremely weak during seismic slip. These results, combined with borehole data indicating that the current in situ stress is approximately lithostatic, support the hypothesis that dynamic weakening of wet clay at seismic slip rates favor earthquake rupture propagation to shallow depths even though the frictional properties of wet clay at low slip rates prohibit the nucleation of slip instabilities. Core samples of sheared clay from the décollement are being analyzed to identify earthquake-related microstructures and determine the mechanisms of dynamic weakening during seismic slip.

Micromechanical Properties of Nanostructured Clay-Oxide Multilayers Synthesized by Layer-by-Layer Self-Assembly.

PubMed

Hou, Dongwei; Zhang, Guoping; Pant, Rohit Raj; Wei, Zhongxin; Shen, Shuilong

2016-11-08

Clay-based nanostructured multilayers, such as clay-polymer multilayers and clay-oxide multilayers, have attracted growing attention owing to their remarkable mechanical properties and promising application in various fields. In this paper, synthesis of a new kind of nanostructured clay-oxide multilayers by layer-by-layer self-assembly was explored. Nano-mechanical characterization of 18 clay-based multilayer samples, prepared under as-deposited (i.e., air-dried) and annealing conditions at 400 °C/600 °C with different precursor cations and multilayer structure, were carried out using nanoindentation testing, atomic force microscopy (AFM), and X-ray diffraction (XRD). The influencing factors, including as-deposited and annealing conditions and clay concentrations on the mechanical properties were analyzed. Results show that all of the multilayers exhibit high bonding strength between interlayers. Higher modulus and hardness of clay-based multilayers were obtained with lower clay concentrations than that with higher clay concentrations. Different relationships between the modulus and hardness and the annealing temperature exist for a specific type of clay-oxide multilayer. This work offers the basic and essential knowledge on design of clay-based nanostructured multilayers by layer-by-layer self-assembly.

Adsorption of hydrogen gas and redox processes in clays.

PubMed

Didier, Mathilde; Leone, Laura; Greneche, Jean-Marc; Giffaut, Eric; Charlet, Laurent

2012-03-20

In order to assess the adsorption properties of hydrogen gas and reactivity of adsorbed hydrogen, we measured H(2)(g) adsorption on Na synthetic montmorillonite-type clays and Callovo-Oxfordian (COx) clayrock using gas chromatography. Synthetic montmorillonites with increasing structural Fe(III) substitution (0 wt %, 3.2 wt %, and 6.4 wt % Fe) were used. Fe in the synthetic montmorillonites is principally present as structural Fe(III) ions. We studied the concomitant reduction of structural Fe(III) in the clays using (57)Fe Mössbauer spectrometry. The COx, which mainly contains smectite/illite and calcite minerals, is also studied together with the pure clay fraction of this clayrock. Experiments were performed with dry clay samples which were reacted with hydrogen gas at 90 and 120 °C for 30 to 45 days at a hydrogen partial pressure close to 0.45 bar. Results indicate that up to 0.11 wt % of hydrogen is adsorbed on the clays at 90 °C under 0.45 bar of relative pressure. (57)Fe Mössbauer spectrometry shows that up to 6% of the total structural Fe(III) initially present in these synthetic clays is reduced upon adsorption of hydrogen gas. No reduction is observed with the COx sample in the present experimental conditions.

Fire retardancy assessment of polypropylene composite filed with nano clay prepared from Iraqi bentonite

NASA Astrophysics Data System (ADS)

Kareem Salih, Watheq

2018-05-01

Fire retardants have an extraordinary importance because of their role in saving the people, property and reducing the damages and minimizing the dangers resulting from fires and burning of polymeric composites which are used in different civil and industrial fields. The work in this paper can be divided into two main stages. In first one nano-clay was manufactured from Iraqi bentonite and it was characterized using AFM, XRD, XRF, SEM, and BET. The AFM test showed the particle size of prepared nano clay was about 99.25 nm. In the second stage, polypropylene/nano clay composites at three low loading percents (0%,2%,4%,6%) were formulated via twin screw extruder. The fire retardancy tests included burning rate according to ASTM:D-635 and maximum flame height of flame according to ASTM:D-3014. Besides, the mechanical tests and thermal behavior of prepared samples were investigated. The results showed that (4%) of nano-clay had the maximum fire retardancy and while at (2%) loading, the maximum value of tensile strength and Yong modulus were obtained. The maximum heat of fusion was recorded for 6% nano clay sample. The final results assessment confirmed on the possibility of using low loadings of prepared nano clay to improve the fire retardancy, mechanical and thermal properties successfully.

Molecular Dynamics Simulation of the Crystal Nucleation and Growth Behavior of Methane Hydrate in the Presence of the Surface and Nanopores of Porous Sediment.

PubMed

Yan, Ke-Feng; Li, Xiao-Sen; Chen, Zhao-Yang; Xia, Zhi-Ming; Xu, Chun-Gang; Zhang, Zhiqiang

2016-08-09

The behavior of hydrate formation in porous sediment has been widely studied because of its importance in the investigation of reservoirs and in the drilling of natural gas hydrate. However, it is difficult to understand the hydrate nucleation and growth mechanism on the surface and in the nanopores of porous media by experimental and numerical simulation methods. In this work, molecular dynamics simulations of the nucleation and growth of CH4 hydrate in the presence of the surface and nanopores of clay are carried out. The molecular configurations and microstructure properties are analyzed for systems containing one H2O hydrate layer (System A), three H2O hydrate layers (System B), and six H2O hydrate layers (System C) in both clay and the bulk solution. It is found that hydrate formation is more complex in porous media than in the pure bulk solution and that there is cooperativity between hydrate growth and molecular diffusion in clay nanopores. The hydroxylated edge sites of the clay surface could serve as a source of CH4 molecules to facilitate hydrate nucleation. The diffusion velocity of molecules is influenced by the growth of the hydrate that forms a block in the throats of the clay nanopore. Comparing hydrate growth in different clay pore sizes reveals that the pore size plays an important role in hydrate growth and molecular diffusion in clay. This simulation study provides the microscopic mechanism of hydrate nucleation and growth in porous media, which can be favorable for the investigation of the formation of natural gas hydrate in sediments.

5. Long view of east half of site from Lawrence ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

5. Long view of east half of site from Lawrence General Hospital parking deck (former location of coating mill) showing north side of Clay Storage Silos and northeast block of Wilder Mill; view to southwest. - Champion-International Paper Company, West bank of Spicket River at Canal Street, Lawrence, Essex County, MA

Responses of rice cultivars and elite lines to diseases in conventional production system, 2010

USDA-ARS?s Scientific Manuscript database

The experiment was established in a field of League-type soil (3% sand, 32% silt, and 64% clay) under organic management for many years at the Texas A&M University System's Agrilife Research and Extension Center, Beaumont. Twenty rice cultivars and lines were arranged in a randomized complete block ...

Dibenzo-p-dioxins in the environment from ceramics and pottery produced from ball clay mined in the United States

NASA Technical Reports Server (NTRS)

Ferrario, Joseph; Byrne, Christian

2002-01-01

Processed ball clay samples used in the production of ceramics and samples of the ceramic products were collected and analyzed for the presence and concentration of the 2,3,7,8-Cl substituted polychlorinated dibenzo-p-dioxins and -furans (PCDDs/PCDFs). The processed ball clay had average PCDD concentrations of 3.2 ng/g toxic equivalents, a congener profile, and isomer distribution consistent with those found previously in raw ball clay. The PCDF concentrations were below the average limit of detection (LOD) of 0.5 pg/g. The final fired ceramic products were found to be free of PCDDs/PCDFs at the LODs. A consideration of the conditions involved in the firing process suggests that the PCDDs, if not destroyed, may be released to the atmosphere and could represent an as yet unidentified source of dioxins to the environment. In addition, the PCDDs in clay dust generated during manufacturing operations may represent a potential occupational exposure.

Dibenzo-p-dioxins in the environment from ceramics and pottery produced from ball clay mined in the United States.

PubMed

Ferrario, Joseph; Byrne, Christian

2002-03-01

Processed ball clay samples used in the production of ceramics and samples of the ceramic products were collected and analyzed for the presence and concentration of the 2,3,7,8-Cl substituted polychlorinated dibenzo-p-dioxins and -furans (PCDDs/PCDFs). The processed ball clay had average PCDD concentrations of 3.2 ng/g toxic equivalents, a congener profile, and isomer distribution consistent with those found previously in raw ball clay. The PCDF concentrations were below the average limit of detection (LOD) of 0.5 pg/g. The final fired ceramic products were found to be free of PCDDs/PCDFs at the LODs. A consideration of the conditions involved in the firing process suggests that the PCDDs, if not destroyed, may be released to the atmosphere and could represent an as yet unidentified source of dioxins to the environment. In addition, the PCDDs in clay dust generated during manufacturing operations may represent a potential occupational exposure.

An Exploratory Study: Assessment of Modeled Dioxin in ...

EPA Pesticide Factsheets

The purpose of this project is to investigate the potential dioxin exposure to artists/hobbyists who use ball clay to make pottery and related products. This project will focus on artists working in a ceramics studio where exposure could occur via three pathways: particle inhalation, incidental ingestion and dermal contact. Levels of clay will be measured in the studio air, deposition surfaces and skin of artists. It is anticipated that no samples will need to be analyzed for dioxin. Rather, all samples will be analyzed for total clay levels and theoretical dioxin exposures would be estimated using information on historical measurements of dioxin levels in ball clay. Data gathering completed in 2004, internal review of report completed in Summer 2005, external peer review completed in 2007, final in 2008. See www.epa.gov/ncea for final report The purpose of this project is to investigate the potential dioxin exposure to artists/hobbyists who use ball clay to make pottery and related products.

Radon exhalation study of manganese clay residue and usability in brick production.

PubMed

Kovács, Tibor; Shahrokhi, Amin; Sas, Zoltán; Vigh, Tamás; Somlai, János

2017-03-01

The reuse of by-products and residue streams is an important topic due to environmental and financial aspects. Manganese clay is a residue of manganese ore processing and is generated in huge amounts. This residue may contain some radionuclides with elevated concentrations. In this study, the radon emanation features and the massic exhalation rate of the heat-treated manganese clay were determined with regard to brick production. From the manganese mud depository, 20 samples were collected and after homogenization radon exhalation characteristics were determined as a function of firing temperatures from 100 to 750 °C. The major naturally occurring radionuclides 40 K, 226 Ra and 232 Th concentrations were 607 ± 34, 52 ± 6 and 40 ± 5 Bq kg -1 , respectively, comparable with normal clay samples. Similar to our previous studies a strong correlation was found between the internal structure and the radon emanation. The radon emanation coefficient decreased by ∼96% from 0.23 at 100 °C to 0.01 at 750 °C. The massic radon exhalation rate of samples fired at 750 °C reduced by 3% compared to samples fired at 100 °C. In light of the results, reusing of manganese clay as a brick additive is possible without any constraints. Copyright © 2016 Elsevier Ltd. All rights reserved.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Giaquinta, D.M.; Soderholm, L.; Yuchs, S.E.

1997-08-01

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 about the interactions of radionuclides with clays and how such interactions affect their speciations is crucial for successful modeling of actinide-migration. X-ray absorption spectroscopy (XAS) is used to determine the uranium speciation in exchanged and surface-modified clays. The XAS datamore » from uranyl-loaded bentonite clay are compared with those obtained after the particle surfaces have been coated with alkylsilanes. These silane films, which render the surface of the clay hydrophobic, are added in order to minimize the ability of external water to exchange with the water in the clay interlayer, thereby decreasing the release rate of the exchanged-uranium species. Mild hydrothermal conditions are used in an effort to mimic potential geologic conditions that may occur during long-term radioactive waste storage. The XAS spectra indicate that the uranyl monomer species remain unchanged in most samples, except in those samples that were both coated with an alkylsilane and hydrothermally treated. When the clay was coated with an organic film, formed by the acidic deposition of octadecyltrimethoxysilane, hydrothermal treatment results in the formation of aggregated uranium species in which the uranium is reduced from U{sup VI} to U{sup IV}.« less

NMR and Electrochemical Investigation of the Transport Properties of Methanol and Water in Nafion and Clay-Nanocomposites Membranes for DMFCs

PubMed Central

Nicotera, Isabella; Angjeli, Kristina; Coppola, Luigi; Aricò, Antonino S.; Baglio, Vincenzo

2012-01-01

Water and methanol transport behavior, solvents adsorption and electrochemical properties of filler-free Nafion and nanocomposites based on two smectite clays, were investigated using impedance spectroscopy, DMFC tests and NMR methods, including spin-lattice relaxation and pulsed-gradient spin-echo (PGSE) diffusion under variable temperature conditions. Synthetic (Laponite) and natural (Swy-2) smectite clays, with different structural and physical parameters, were incorporated into the Nafion for the creation of exfoliated nanocomposites. Transport mechanism of water and methanol appears to be influenced from the dimensions of the dispersed platelike silicate layers as well as from their cation exchange capacity (CEC). The details of the NMR results and the effect of the methanol solution concentration are discussed. Clays particles, and in particular Swy-2, demonstrate to be a potential physical barrier for methanol cross-over, reducing the methanol diffusion with an evident blocking effect yet nevertheless ensuring a high water mobility up to 130 °C and for several hours, proving the exceptional water retention property of these materials and their possible use in the DMFCs applications. Electrochemical behavior is investigated by cell resistance and polarization measurements. From these analyses it is derived that the addition of clay materials to recast Nafion decreases the ohmic losses at high temperatures extending in this way the operating range of a direct methanol fuel cell. PMID:24958179

Micro-fabric damages in Boom Clay inferred from cryo-BIB-SEM experiment: recent results

NASA Astrophysics Data System (ADS)

Desbois, Guillaume; Schmatz, Joyce; Klaver, Jop; Urai, Janos L.

2017-04-01

The Boom Clay is considered as a potential host rock in Belgium for nuclear waste disposal in a deep geological formation. One of the keys to understand the long-term performance of such a host rock is the fundamental understanding of coupling between microstructural evolution, poromechanical behaviour and the state of hydration of the system. At in situ conditions, Boom Clay is a nearly water-saturated (>94%) clay-rich geomaterial. Subsequently, for measurement of mechanical and transport properties in laboratory, cores of Boom Clay are vacuum-packed in Al-coated-poly-ethylene barrier foil to be best preserved at original hydric state. Because clay microstructures are very sensitive to dehydration, the validity of investigations done on such preserved or/and dried samples is often questionable. Desbois et al. (2009, 2013, 2014) showed the possibility to image fluid-filled porosity in Boom Clay, by using the FIB-cryo-SEM (FIB: Focussed Ion Beam) and FIB-cryo-SEM (BIB: Broad Ion Beam) techniques. However, surprisingly in Desbois et al. (2014), BIB-cryo-SEM experiments on Boom Clay, shown that the majority of the pores were fluid-free, contrasting with result in Desbois et al. (2009). In Desbois et al. (2014), several reasons were discussed to explain such discrepancies. The likely ones are the sealing efficiency of the Al-barrier foil at long term and the volume expansion due to the release of in-situ stress after core extraction, contributing both to dehydration and microfabric damage. This contribution presents the newest results based on cryo-BIB-SEM. Small pieces (30 mm3) of Boom Clay were preserved in liquid nitrogen after the core extraction at the MOL/Dessel Underground Research Laboratory in Belgium. A maximum of ten minutes time span was achieved between opening the core, the sub-sample extraction and the quenching of sub-samples in liquid nitrogen. First results show that all pores visible at cryo-SEM resolution are water saturated. However, water-filled micro-cracks are also present and they are interpreted to result from the releasing of in-situ stress after the core extraction. Moreover, the comparison of the clay micro-fabrics in the same preserved and dried sample suggests collapsing of the clay aggregates' pores in dried sample. These newest results are still preliminary and they need to be analysed in more details. However, if they are confirmed they may be important input to discuss about the validity of measurement of mechanical and transport properties done in laboratory. Desbois G., Urai J.L. and Kukla P.A. (2009). Morphology of the pore space in claystones - evidence from BIB/FIB ion beam sectioning and cryo-SEM observations. E-Earth, 4 :15-22. Desbois G., J.L. Urai, F. Pérez-Willard, Z. Radi, S. van Offern, I. Burkart, P.A. Kukla, U. Wollenberg (2013). Argon broad ion beam tomography in a cryogenic scanning electron microscope: a novel tool for the investigation of representative microstructures in sedimentary rocks containing pore fluid. Journal of Microscopy, 249(3): 215-235. Desbois G., Urai J.L., Hemes S., Brassinnes S., De Craen M., Sillen X. (2014). Nanometer-scale pore fluid distribution and drying damage in preserved clay cores from Belgian clay formations inferred by BIB-cryo-SEM. Engineering Geology, 170:117-131.

Gravel-Sand-Clay Mixture Model for Predictions of Permeability and Velocity of Unconsolidated Sediments

NASA Astrophysics Data System (ADS)

Konishi, C.

2014-12-01

Gravel-sand-clay mixture model is proposed particularly for unconsolidated sediments to predict permeability and velocity from volume fractions of the three components (i.e. gravel, sand, and clay). A well-known sand-clay mixture model or bimodal mixture model treats clay contents as volume fraction of the small particle and the rest of the volume is considered as that of the large particle. This simple approach has been commonly accepted and has validated by many studies before. However, a collection of laboratory measurements of permeability and grain size distribution for unconsolidated samples show an impact of presence of another large particle; i.e. only a few percent of gravel particles increases the permeability of the sample significantly. This observation cannot be explained by the bimodal mixture model and it suggests the necessity of considering the gravel-sand-clay mixture model. In the proposed model, I consider the three volume fractions of each component instead of using only the clay contents. Sand becomes either larger or smaller particles in the three component mixture model, whereas it is always the large particle in the bimodal mixture model. The total porosity of the two cases, one is the case that the sand is smaller particle and the other is the case that the sand is larger particle, can be modeled independently from sand volume fraction by the same fashion in the bimodal model. However, the two cases can co-exist in one sample; thus, the total porosity of the mixed sample is calculated by weighted average of the two cases by the volume fractions of gravel and clay. The effective porosity is distinguished from the total porosity assuming that the porosity associated with clay is zero effective porosity. In addition, effective grain size can be computed from the volume fractions and representative grain sizes for each component. Using the effective porosity and the effective grain size, the permeability is predicted by Kozeny-Carman equation. Furthermore, elastic properties are obtainable by general Hashin-Shtrikman-Walpole bounds. The predicted results by this new mixture model are qualitatively consistent with laboratory measurements and well log obtained for unconsolidated sediments. Acknowledgement: A part of this study was accomplished with a subsidy of River Environment Fund of Japan.

Assessment of toxic metals and phthalates in children's toys and clays.

PubMed

Korfali, Samira I; Sabra, Rayan; Jurdi, Mey; Taleb, Robin I

2013-10-01

Toxic metals and phthalates are introduced in the manufacturing of plastic toys and modeling clays. In Lebanon, inexpensive plastic toys and modeling clays (sold in dollar stores) are affordable and popular, and there is no legislation to monitor or regulate such toys. This study aimed to assess the quality of inexpensive plastic toys and modeling clays imported in Lebanon. Metal concentrations in toys, namely, zinc [not detectable (ND) to 3,708 μg/g], copper (ND to 140), chromium (ND to 75 μg/g), tin (ND to 39 μg/g), and cadmium (Cd) (ND to 20 μg/g), were lower than the European Union (EU) Directive limits, whereas lead (ND to 258 μg/g) in 10% of samples and antimony (Sb) (ND to 195 μg/g) in 5% of samples were greater than the EU limits. In modeling clays, most of the metals were lower than the EU Directive limits except for Cd and arsenic (As). Cd was detected in 83% of samples, with a mean level of 9.1 μg/g, which is far greater than the EU Directive limit (1.9 μg/g). The As mean level of 4.5 μg/g was greater than the EU limit (4.0 μg/g) and was detected in 9% of samples. Phthalic acid esters (PAEs) were found in 60% of children's toys and 77% of modeling clays. Phthalic acid butyl ester had the highest-level PAE encountered and was ≤59.1 % in one type of clay. However, among children's toys, di(4-octyl) ester terephthalic acid was the highest encountered phthalate at a concentration of 25.7%. The community survey indicated that 82% of households purchase their toys from inexpensive shops and that only 17% of parents were aware of the health hazard of such toys. Consequently, an intervention plan was proposed for the provision of safe toys to children.

Surveying Clay Mineral Diversity in the Murray Formation, Gale Crater, Mars

NASA Technical Reports Server (NTRS)

Bristow, T. F.; Blake, D. F.; Vaniman, D. T.; Chipera, S. J.; Rampe, E. B.; Grotzinger, J. P.; McAdam, A. C.; Ming, D. W.; Morrison, S. M.; Yen, A. S.;

Study of gamma spectrometry laboratory measurement in various sediment and vulcanic rocks

NASA Astrophysics Data System (ADS)

Nurhandoko, Bagus Endar B.; Kurniadi, Rizal; Rizka Asmara Hadi, Muhammad; Rizal Komara, Insan

2017-01-01

Gamma-ray spectroscopy is the quantitative study of the energy spectra of gamma-ray sources. This method is powerful to characterize some minerals, especially to differentiate rocks which contains among Potassium, Uranium, dan Thorium. Rock contains radioactive material which produce gamma rays in various energies and intensities. When these emissions are detected and analyzed with a spectroscopy system, a gamma-ray energy spectrum can be used as indicator for mineral content of rock. Some sediment and vulcanic rock have been collected from East Java Basin. Samples are ranging from Andesite vulcanics, Tuff, Shale, various vulcanic clay and Alluvial clay. We present some unique characteristics of gamma spectrometry in various sedimentar and vulcanic rocks of East Java Basins. Details contents of gamma ray spectra give enrichments to characterize sample of sediment and vulcanic in East Java. Weathered vulcanic clay has lower counting rate of gamma ray than alluvial deltaic clay counting rate. Therefore, gamma spectrometrometry can be used as tool for characterizing the enviroment of clay whether vulcanic or alluvial-deltaic. This phenomena indicates that gamma ray spectrometry can be as tool for characterizing the clay whether it tends to Smectite or Illite

Acid rock drainage passive remediation using alkaline clay: Hydro-geochemical study and impacts of vegetation and sand on remediation.

PubMed

Plaza, Fernando; Wen, Yipei; Liang, Xu

2018-10-01

Acid rock drainage (ARD) is one of the most adverse environmental problems of the mine industry, especially in regions with an abundance of coal refuse (CR) deposits (e.g. the Northern Appalachian Coalfield in the USA) where surface and ground waters are affected by this pollution due to the acidity and high content of sulfates and heavy metals. This study explores the effectiveness of the ARD passive remediation method using alkaline clay (AC) through a series of static and long-term kinetic laboratory experiments (over three years) complemented with field measurements and geochemical modeling. Two important issues associated with this passive and auto-sustainable ARD remediation method were investigated: 1) the hydrogeochemical study of the mixture in terms of the percentages of AC and CR, and, 2) impacts of vegetation cover and a saturated sand barrier on the remediation. Both the field measurements and the samples used for the experiments came from a local coal waste site. Through the analysis of the field measurements and the outcome of the laboratory experiments and the geochemical modeling, alkaline clay proved to be an effective remediation material for ARD, in terms of achieving a neutral pH in the leachate and immobilization of sulfate and metals such as Fe, Mn, Cu, Zn, Ni, Pb, Cd, Co. Moreover, it has been demonstrated that the use of vegetation and a saturated sand barrier are beneficial. Vegetation acted as a phytoaccumulation/phytoextraction agent, causing an additional immobilization of metals. The saturated sand barrier blocked downward the oxygen and water diffusion, reducing pyrite oxidation rates. The proposed remediation approach ensures that the acidity consumption will likely occur before all the alkalinity is exhausted. Copyright © 2018 Elsevier B.V. All rights reserved.

A record of reversed polarity carries by the iron sulphide greigite in British early Pleistocene sediments

NASA Astrophysics Data System (ADS)

Hallam, D. F.; Maher, B. A.

1994-01-01

Palaeomagnetic measurements were made on samples extracted from a short sequence of early Pleistocene estuarine clays, now exposed in a sea cliff near Sheringham on the north Norfolk coast, UK. On the basis of earlier palynological work, these clays had been ascribed a Pastonian (late Tiglian) age. The clays show marked changes in colour, from reddish-brown at the top of the unit, to blue-grey in the middle, and grey-brown at the base. The palaeomagnetic data vary in close association with these colour changes. The top and basal brown clays show scattered normal directions of low intensity, while the middle blue clays show strongly clustered reversed directions, of much higher intensities. Some samples taken from the boundary between the middle blue clays and upper red clays show upon demagnetisation a normal overprint on a stable reversed polarity. Using high-gradient magnetic extraction, magnetic concentrates have been obtained from the strongly magnetic middle blue clays. The presence of iron sulphide minerals in these concentrates was identified using energy-dispersive X-ray analysis during scanning electron microscopy. More specifically, X-ray diffraction identifies greigite as the only detectable ferrimagnetic mineral in the magnetic concentrates. Rock magnetic measurements show clear qualitative differences in the magnetic mineralogies of the three clay subunits, but absolute identification of the magnetic mineralogy of the weakly magnetic upper and basal brown clays has not yet been possible. We interpret the sequence as a primary reversed polarity record. This record is carried by the iron sulphide greigate as a chemical remanence acquired during `syn'-depositional reduction of iron via the decomposition of organic material in these anoxic tidal clays. Subsequently, the upper and basl subunits of the clay have been oxidised by permeation of groundwater from the adjacent coarse-grained sediments. Most of the griegite in the oxidised margins of the clay has been altered as a result, to a new, less efficient magnetic recording material which thus carries a later, scattered, low-intensity, normal overprint.

Lithological and hydrological influences on ground-water composition in a heterogeneous carbonate-clay aquifer system

USGS Publications Warehouse

Kauffman, S.J.; Herman, J.S.; Jones, B.F.

1998-01-01

The influence of clay units on ground-water composition was investigated in a heterogeneous carbonate aquifer system of Miocene age in southwest Florida, known as the Intermediate aquifer system. Regionally, the ground water is recharged inland, flows laterally and to greater depths in the aquifer systems, and is discharged vertically upward at the saltwater interface along the coast. A depth profile of water composition was obtained by sampling ground water from discrete intervals within the permeable carbonate units during coring and by squeezing pore water from a core of the less-permeable clay layers. A normative salt analysis of solute compositions in the water indicated a marine origin for both types of water and an evolutionary pathway for the clay water that involves clay diagenesis. The chemical composition of the ground water in the carbonate bedrock is significantly different from that of the pore water in the clay layers. Dissolution of clays and opaline silica results in high silica concentrations relative to water in other parts of the Intermediate aquifer system. Water enriched in chloride relative to the overlying and underlying ground water recharges the aquifer inland where the confining clay layer is absent, and it dissolves carbonate and silicate minerals and reacts with clays along its flow path, eventually reaching this coastal site and resulting in the high chloride and silica concentrations observed in the middle part of the Intermediate aquifer system. Reaction-path modeling suggests that the recharging surficial water mixes with sulfate-rich water upwelling from the Upper Floridan aquifer, and carbonate mineral dissolution and precipitation, weathering and exchange reactions, clay mineral diagenesis, clay and silica dissolution, organic carbon oxidation, and iron and sulfate reduction result in the observed water compositions.A study was conducted to clarify the influence of clay units on ground-water composition in a heterogeneous carbonate aquifer system of Miocene age in southwest Florida. A depth profile of water composition was obtained by sampling ground water from discrete intervals within the permeable carbonate units during coring and by squeezing pore water from a core of the less-permeable clay layers. A normative salt analysis of solute compositions in the water indicated a marine origin for both types of water and an evolutionary pathway for the clay water that involves clay diagenesis. The factors influencing water compositions were determined.

Dissipation of terbuthylazine, metolachlor and mesotrione in soils with contrasting texture

NASA Astrophysics Data System (ADS)

Carretta, Laura; Cardinali, Alessandra; Zanin, Giuseppe; Masin, Roberta

2017-04-01

Herbicides play an important role in the crops production, but their use may result in residues with undesirable effects on the environment. The determination of the herbicide dissipation rate in agricultural soil is an important issue for monitoring their environmental fate. As soil composition is one of the factors affecting herbicide persistence, this study aimed to evaluate the dissipation of three herbicides, terbuthylazine (TERB), metolachlor (METO) and mesotrione (MESO) in soils with contrasting texture. The field trial was conducted at the Padua University Experimental Farm (45.3° N, 12.0° E) in the Po Valley, north-east Italy in 2012. The persistence of three herbicides has been studied in three diverse soil textures (clay, sand and loam soil) at two different depths (0-5 and 5-15 cm). A randomized complete block design was used for this experiment with six plots (2 m × 2 m) for each of 3 treatments. TERB, METO and MESO were applied in May on maize as a formulated product (Lumax®) with hand-held field plot sprayer at a dose of 3.5 L/ha. Soil organic carbon content was the highest in clay texture (1.10%) followed by loam soil (0.67%) and sandy soil (0.24%). The soil was sampled with a soil auger before herbicides treatment, and soon after treatment soil samples were taken to assess initial concentration, then at increasing times from spraying to evaluate field dissipation kinetics (t50). The dissipation of the herbicides in the treated plots was followed for nearly 2 months after their application. The herbicides were analysed by liquid chromatography-mass spectrometry. The dissipation of TERB, METO and MESO could be described by a pseudo first order kinetics. Within the herbicides, TERB showed the highest t50, followed by METO and MESO. Considering the tested soil, the highest t50 value was found for clay soil texture for TERB and METO, whereas for MESO there was no difference among different soils. Significant differences were found within the 2 soil depths for TERB and MESO only in sandy soil, for METO only in loam soil. In detail, considering the average of both depths, TERB and METO degraded slowly in clay soil (22 days and 16 days respectively) followed by loam soil (14 days and 7 days) and sandy soil (12 days and 5 days). On the other hand, MESO did not show significant differences (ranging from about 4 days in clay soil to 5 days in loam soil). These results suggest that soil texture have a large influence on the dissipation of TERB and METO, whereas no influence was observed on MESO.

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

NASA Technical Reports Server (NTRS)

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

1992-01-01

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

Exchangeable Ions Are Responsible for the In Vitro Antibacterial Properties of Natural Clay Mixtures

PubMed Central

Otto, Caitlin C.; Haydel, Shelley E.

2013-01-01

We have identified a natural clay mixture that exhibits in vitro antibacterial activity against a broad spectrum of bacterial pathogens. We collected four samples from the same source and demonstrated through antibacterial susceptibility testing that these clay mixtures have markedly different antibacterial activity against Escherichia coli and methicillin-resistant Staphylococcus aureus (MRSA). Here, we used X-ray diffraction (XRD) and inductively coupled plasma – optical emission spectroscopy (ICP-OES) and – mass spectrometry (ICP-MS) to characterize the mineralogical and chemical features of the four clay mixture samples. XRD analyses of the clay mixtures revealed minor mineralogical differences between the four samples. However, ICP analyses demonstrated that the concentrations of many elements, Fe, Co, Cu, Ni, and Zn, in particular, vary greatly across the four clay mixture leachates. Supplementation of a non-antibacterial leachate containing lower concentrations of Fe, Co, Ni, Cu, and Zn to final ion concentrations and a pH equivalent to that of the antibacterial leachate generated antibacterial activity against E. coli and MRSA, confirming the role of these ions in the antibacterial clay mixture leachates. Speciation modeling revealed increased concentrations of soluble Cu2+ and Fe2+ in the antibacterial leachates, compared to the non-antibacterial leachates, suggesting these ionic species specifically are modulating the antibacterial activity of the leachates. Finally, linear regression analyses comparing the log10 reduction in bacterial viability to the concentration of individual ion species revealed positive correlations with Zn2+ and Cu2+ and antibacterial activity, a negative correlation with Fe3+, and no correlation with pH. Together, these analyses further indicate that the ion concentration of specific species (Fe2+, Cu2+, and Zn2+) are responsible for antibacterial activity and that killing activity is not solely attributed to pH. PMID:23691149

How Properties of Kenaf Fibers from Burkina Faso Contribute to the Reinforcement of Earth Blocks

PubMed Central

Millogo, Younoussa; Aubert, Jean-Emmanuel; Hamard, Erwan; Morel, Jean-Claude

2015-01-01

Physicochemical characteristics of Hibiscus cannabinus (kenaf) fibers from Burkina Faso were studied using X-ray diffraction (XRD), infrared spectroscopy, thermal gravimetric analysis (TGA), chemical analysis and video microscopy. Kenaf fibers (3 cm long) were used to reinforce earth blocks, and the mechanical properties of reinforced blocks, with fiber contents ranging from 0.2 to 0.8 wt%, were investigated. The fibers were mainly composed of cellulose type I (70.4 wt%), hemicelluloses (18.9 wt%) and lignin (3 wt%) and were characterized by high tensile strength (1 ± 0.25 GPa) and Young’s modulus (136 ± 25 GPa), linked to their high cellulose content. The incorporation of short fibers of kenaf reduced the propagation of cracks in the blocks, through the good adherence of fibers to the clay matrix, and therefore improved their mechanical properties. Fiber incorporation was particularly beneficial for the bending strength of earth blocks because it reinforces these blocks after the failure of soil matrix observed for unreinforced blocks. Blocks reinforced with such fibers had a ductile tensile behavior that made them better building materials for masonry structures than unreinforced blocks.

Adsorption and Desorption of Cesium in Clay Minerals: Effects of Natural Organic Matter and pH

NASA Astrophysics Data System (ADS)

Yoon, Hongkyu; Ilgen, Anastasia; Mills, Melissa; Lee, Moo; Seol, Jeung Gun; Cho, Nam Chan; Kang, Hyungyu

2017-04-01

Cesium (Cs) released into the environment (e.g., Fukushima accident) poses significant environmental concerns and remediation challenges. A majority of Cs in the environment have remained within the surface soils due to the strong adsorption affinity of Cs towards clay minerals. Different clay minerals have different bonding sites, resulting in various adsorption mechanisms at nanometer scale. For example, the illite commonly has a basal spacing of 1.0 nm, but becomes wider to 1.4 nm once other cations exchange with K in the interlayer site. Cs adsorbs into these expanded wedged zone strongly, which can control its mobility in the environment. In addition, natural organic matter (NOM) in the surface soils can interact with clay minerals, which can modify the mechanisms of Cs adsorption on the clay minerals by blocking specific adsorption sites and/or providing Cs adsorption sites on NOM surface. In this work, three representative clay minerals (illite, vermiculite, montmorillonite) and humic acid (HA) are used to systematically investigate the adsorption and desorption behavior of Cs. We performed batch adsorption experiments over a range of Cs concentrations on three clay minerals with and without HA, followed by sequential desorption batch testing. We tested desorption efficiency as a function of initial adsorbed Cs concentration, HA content, sodium concentration, and pH. The sequential extraction results are compared to the structural changes in clay minerals, measured using extended X-ray absorption fine structure spectroscopy (EXAFS) and aberration-corrected (scanning) transmission electron microscopy (TEM) - energy dispersive X-ray spectroscopy (EDX). Hence, this work aims to identify the mechanisms of Cs fixation at the nanometer (or atomic-) scale as a function of the clay mineral properties (e.g. expandability, permanent surface charge) and varying organic matter content at different pH values and to enhance our atomic-scale mechanistic understanding of the clay mineral interactions with cesium in the presence of NOM. The expandability of clay minerals and effect of HA addition on Cs adsorption and desorption are highlighted to address the efficiency of Cs removal schemes from contaminated soils. Sandia National Laboratories is a multi-mission laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

Block coals from Indiana: Inferences on changing depositional environment

USGS Publications Warehouse

Mastalerz, Maria; Padgett, P.L.; Eble, C.F.

2000-01-01

Significant differences in coal petrography, palynology and coal quality were found between the Lower Block and Upper Block Coal Members (Brazil Formation, Pennsylvanian) in Daviess County, Indiana. The Lower Block Coal Member ranges in thickness from 51 to 74 cm and the Upper Block Coal Member ranges from 20 to 65 cm. Average sulfur content and ash yield of the Lower Block coal (0.98%, 7.65%) are lower than in the Upper Block coal. Megascopically, the coals show distinct differences. The Lower Block is a banded coal with numerous thin fusain horizons and a thin clay parting in the lower third of the seam. The Upper Block coal has a dulling-upward trend, with a bright clarain found at the base that grades into a clarain and then into a durain in the upper portion of the seam. Vitrinite content of the Lower Block coal ranges from 63% to 78%, with the highest vitrinite content found in the middle portion of the seam. In the Upper Block coal, vitrinite content ranges from 40% to 83%, with the highest values found in the lower part of the seam. Ash yield is higher in the upper part of the Upper Block coal, reaching up to 40%. The Lower Block coal is dominated by lycopod trees and tree ferns. The Upper Block coal shows marked differences in spore assemblages between lower and upper parts of the seam. The lower half is dominated by large lycopod trees and tree ferns, similar to the Lower Block coal. The upper half is dominated by small lycopods, mainly Densosporites and Radiizonates. These differences between the Lower Block and Upper Block Coal Members are significant correlation tools applicable to mining exploration and chronostratigraphy. (C) 2000 Elsevier Science B.V. All rights reserved.Significant differences in coal petrography, palynology and coal quality were found between the Lower Block and Upper Block Coal Members (Brazil Formation, Pennsylvanian) in Daviess County, Indiana. The Lower Block Coal Member ranges in thickness from 51 to 74 cm and the Upper Block Coal Member ranges from 20 to 65 cm. Average sulfur content and ash yield of the Lower Block coal (0.98%, 7.65%) are lower than in the Upper Block coal. Megascopically, the coals show distinct differences. The Lower Block is a banded coal with numerous thin fusain horizons and a thin clay parting in the lower third of the seam. The Upper Block coal has a dulling-upward trend, with a bright clarain found at the base that grades into a clarain and then into a durain in the upper portion of the seam. Vitrinite content of the Lower Block coal ranges from 63% to 78%, with the highest vitrinite content found in the middle portion of the seam. In the Upper Block coal, vitrinite content ranges from 40% to 83%, with the highest values found in the lower part of the seam. Ash yield is higher in the upper part of the Upper Block coal, reaching up to 40%. The Lower Block coal is dominated by lycopod trees and tree ferns. The Upper Block coal shows marked differences in spore assemblages between lower and upper parts of the seam. The lower half is dominated by large lycopod trees and tree ferns, similar to the Lower Block coal. The upper half is dominated by small lycopods, mainly Densosporites and Radiizonates. These differences between the Lower Block and Upper Block Coal members are significant correlation tools applicable to mining exploration and chronostratigraphy.

Assessment of carbon nanotubes and silver nanoparticles loaded clays as adsorbents for removal of bacterial contaminants from water sources.

PubMed

Hassouna, M E M; ElBably, M A; Mohammed, Asmaa N; Nasser, M A G

2017-02-01

This work evaluated the antimicrobial efficacy of kaolin clay and its loaded forms with carbon nanotubes (CNTs) and silver nanoparticles (AgNPs) against bacterial isolates from different water supplies (tap, underground and surface water) in addition to wastewater. A total of 160 water samples were collected from different water sources in the investigated districts. Samples were cultured for isolation and serological identification of pathogenic bacteria. AgNPs were synthesized by a typical one-step synthesis protocol, where CNTs were carried out in a reactor employing the double bias-assisted hot filament chemical vapor deposition method. Both were characterized using transmission electron microscopy, infrared and X-ray fluorescence (XRF) spectroscopy. The antimicrobial efficacy of each of natural kaolin clay, AgNPs- and CNTs-loaded clays were evaluated by their application in four concentrations (0.01, 0.03, 0.05 and 0.1 ppm) at different contact times (5 min, 15 min, 30 min and 2 h). AgNPs-loaded clays at concentrations of 0.05 and 0.1 mg/l for 2 h contact time exhibited a higher bactericidal efficacy on Escherichia coli and Salmonella spp. (70, 70, 80 and 90%, respectively) compared to CNTs-loaded clay. Concluding, the application of AgNPs-loaded clay for removal of water bacterial contaminants at a concentration of 0.1 ppm for 2 h contact times resulted in highly effective removals.

Mid-term effect of silvicultural treatments on carbon cycling in a Mediterranean Pinus halepensis forest

NASA Astrophysics Data System (ADS)

Lull, Cristina; Bautista, Inmaculada; Lado-Monserrat, Luis; Lidón, Antonio

2014-05-01

Twelve years after a silvicultural treatment in a Pinus halepensis forest, seasonal variation of carbon pools were compared between three treatments: a control reference with no treatment (T0); a moderate thinning with 40% of mean basal area removed (T40); a total clearcut (T100). The silvicultural treatments were performed following a randomized block design. The three blocks selected, namely called Tuéjar izquierda (TI), Tuéjar derecha (TD) and Chelv a(CH) are located in Valencia (East of Spain) and have the same canopy characteristics, but different soils. Soil environmental conditions in each plot were continuously recorded with a pluviometer and two soil moisture and temperature sensors installed at 5 and 10 cm depth connected to a data logger. During two years (2009 and 2010), superficial soil samples (0-15 cm) were collected thrice per year, in spring, summer and autumn. In each sample, water holding capacity, total organic carbon (TOC), soluble organic carbon (SOC), microbial biomass carbon (MBC) and soil respiration were determined. Our results showed that the textural composition (clay loam for TI and TD soils and sandy loam for CH soil), affected carbon pools. Total organic carbon differs significantly between blocks, and also between T40 and the other two treatments in Chelva. Seasonal analysis of the data could not be performed because summer in the year 2009 was very dry compared with 2010. The SOC and MBC pools are related with TOC which explain 51% of the temporal and spatial variation of the SOC and 38% of the MBC. TOC also explain 75% of soil respiration variance. Despite the differences in soil properties between blocks, the silvicultural treatment affect significantly to the BMC pool and the basal respiration flux. Moreover, the most labile pool of soil organic carbon is affected by environmental variables such as soil temperature and for this reason changes seasonally.

Geological and technological characterization of the Late Jurassic-Early Cretaceous clay deposits (Jebel Ammar, northeastern Tunisia) for ceramic industry

NASA Astrophysics Data System (ADS)

Ben M'barek-Jemaï, Moufida; Sdiri, Ali; Ben Salah, Imed; Ben Aissa, Lassaad; Bouaziz, Samir; Duplay, Joelle

2017-05-01

Late Jurassic-Lower Cretaceous clays of the Jebel Ammar study site were used as raw materials for potential applications in ceramic industry. Physico-chemical characterization of the collected samples was performed using atomic absorption spectroscopy, X-ray diffraction, thermogravimetry and dilatometry (Bugot's curve). Geotechnical study was also undertaken by the assessment of plasticity and liquidity limits. It was found that high concentrations of silica, alumina with SiO2/Al2O3 ratio characterized the studied clays; its high amounts of CaO and Fe2O3 in the Late Jurassic clays indicated their calcareous nature. In addition, technological tests indicated moderate to low plasticity values for the Late Jurassic and Lower Cretaceous clays, respectively. Clay fraction (<2 μm) reached 50% of the natural clay in some cases. Mineralogical analysis showed that Jurassic clays were dominated by smectite, illite and kaolinite, as clay mineral species; calcite was the main associated mineral. Lower Cretaceous clays were mainly composed of abundant illite accompanied by well-crystallized smectite and kaolinite. Kaolinite gradually increased upwards, reaching 70% of the total clay fraction (i.e. <2 μm). Quartz, calcite and feldspar were the main non-clay minerals. Based on these analyses, the clays meet technological requirements that would allow their use in the ceramic industry and for the manufacturing of ceramic tiles.

Fire Events and Soil Thermometry: The Applications of Clay Chemistry for Tracing Temperature Changes in Soils and Sediments Below Surface Fires

NASA Astrophysics Data System (ADS)

Watson, E.; Werts, S. P.; Gelabert, M.

2016-12-01

Fires in the natural environment affect the physical, chemical, and biological properties of soils. However, fires may also alter the mineralogy of the geologic material in which it comes in contact. Previous experiments on high temperature alteration of clays indicate that dehydration, oxidation, and hydroxylation in clay minerals can occur progressively in that order at increasing temperatures up to 500°C. It is also well known that wildfire events can heat soils to these temperature ranges several centimeters deep. In this experiment, alterations in clay chemistry were used as a tool to investigate fire intensity along with the changing morphology of clay minerals. For data collection, small camp fires were set in York County, SC and temperatures were recorded using a datalogger system to 5 cm deep during the fire event. Control samples were taken adjacent to the fires to compare the changing morphology of the minerals when heated. Powder x-ray diffraction and scanning electron microscopy were used to identify the clay mineralogy. The clay from soil samples was identified as hydrous kaolinite, anhydrous kaolinite, and varying types of goethite. To observe the dehydration, oxidation, and hydroxylation of clay minerals, scanning electron microscopy with emission dispersive spectroscopy was used to identify the O/cation ratios present, which would indicate changes in the oxidation state of the clay minerals. By mapping the changes in O/cation ratios with temperature in silicates, we are able to trace the temperature of the sediments during fire events. This research suggests it may be possible to utilize these geochemical trends to aid in soil and sediment temperature investigations in both archeological and modern soil and surface process investigations.

Effect of fungicides on sorghum anthracnose and grain mold in Burleson County, Texas, 2014

USDA-ARS?s Scientific Manuscript database

The experiment was conducted at the Texas A&M AgriLife Experiment Station near College Station (Burleson County), using the hybrids BH3822 and BH 5566. The seed was planted 10 Apr in a Belk clay soil. There were four replicates per treatment arranged in a randomized, blocked factorial design. Tre...

Responses of rice cultivars and elite lines to diseases in tilled organic production system, 2010

USDA-ARS?s Scientific Manuscript database

The experiment was established in a field of League-type soil (3% sand, 32% silt, and 64% clay) under organic management for many years at the Texas A&M University system’' Agrilife Research and Extension Center, Beaumont. Twenty rice cultivars and lines were arranged in a randomized complete block ...

Responses of rice cultivars and elite lines to diseases in no-till organic production system, 2010

USDA-ARS?s Scientific Manuscript database

The experiment was established in a field of League-type soil (3% sand, 32% silt, and 64% clay) under organic management for many years at the Texas A&M University System's Agrilife Research and Extension Center, Beaumont. Twenty rice cultivars and lines were arranged in a randomized complete block ...

Mineralogy of selected sedimentary interbeds at or near the Idaho National Engineering Laboratory, Idaho

USGS Publications Warehouse

Reed, Michael F.; Bartholomay, Roy C.

1994-01-01

The U.S. Geological Survey (USGS) Project Office at the Idaho National Engineering Laboratory (INEL), in cooperation with the U.S. Department of Energy and Idaho State University, analyzed 66 samples from sedimentary interbed cores during a 38-month period beginning in October 1990 to determine bulk and clay mineralogy. These cores had been collected from 19 sites in the Big Lost River Basin, 2 sites in the Birch Creek Basin, and 1 site in the Mud Lake Basin, and were archived at the USGS lithologic core library at the INEL. Mineralogy data indicate that the core samples from the Big Lost River Basin have larger mean and median percentages of quartz, total feldspar, and total clay minerals, but smaller mean and median percentages of calcite than the core samples from the Birch Creek Basin. Core samples from the Mud Lake Basin have abundant quartz, total feldspar, calcite, and total clay minerals.

Study of Usage Areas of Clay Samples of Asphaltite Quarries in Sirnak, Turkey

NASA Astrophysics Data System (ADS)

Bilgin, Oyku

2017-12-01

The asphaltite of Sirnak, Turkey are in the form of 12 veins and their total reserves are anticipated to be approximately 200 million tons in a field of 25.000 hectares. The asphaltites at the Sirnak region are in the form of fault and crack fillings and take place together with clay minerals at their side rock. The main raw materials used in the production of cement are limestone, clay and marn known as sedimentary rocks. Limestone for CaO and clay minerals for SiO2, Al2O3, and Fe2O3, which are the main compounds of clinker production, are the main raw materials. Other materials containing these four oxides like marn are also used as cement raw material. Conformity levels of the raw materials to be used in cement production vary according to their chemical compounds. The rocks to be used as clay mineral are evaluated by taking the rate of silicate and alumina into consideration. The soils suitable for brick-tile productions are named as sandy clay. Their difference from the ceramic clays is that they are richer in terms of iron, silica and carbonate. These soils are also known under the names such as clay, arid, alluvium, silt, loam and argil. Inside these soils, minerals such as quartz, montmorillonite, kaolinite, calcite, limonite, hidromika, sericite, illite, and chlorite are available. Some parts of the soils consist of clays in amorphous structure. Limestone parts, gypsums, organic substances and bulky rock residuals spoil the quality. The soils suitable for brick production may not be suitable for tile production. In this case, their sandy soils should be mixed up with the clays with fine granule structure which is high in plasticity. During asphaltite mining in Sirnak region, clays forming side rock are gathered at dump sites. In this study; SQX analyses of the clay samples taken from Avgamasya, Seridahli and Segürük asphaltite veins run in Sirnak region are carried out and their usage areas are searched.

Porosity of the Marcellus Shale: A contrast matching small-angle neutron scattering study

USGS Publications Warehouse

Bahadur, Jitendra; Ruppert, Leslie F.; Pipich, Vitaliy; Sakurovs, Richard; Melnichenko, Yuri B.

2018-01-01

Neutron scattering techniques were used to determine the effect of mineral matter on the accessibility of water and toluene to pores in the Devonian Marcellus Shale. Three Marcellus Shale samples, representing quartz-rich, clay-rich, and carbonate-rich facies, were examined using contrast matching small-angle neutron scattering (CM-SANS) at ambient pressure and temperature. Contrast matching compositions of H2O, D2O and toluene, deuterated toluene were used to probe open and closed pores of these three shale samples. Results show that although the mean pore radius was approximately the same for all three samples, the fractal dimension of the quartz-rich sample was higher than for the clay-rich and carbonate-rich samples, indicating different pore size distributions among the samples. The number density of pores was highest in the clay-rich sample and lowest in the quartz-rich sample. Contrast matching with water and toluene mixtures shows that the accessibility of pores to water and toluene also varied among the samples. In general, water accessed approximately 70–80% of the larger pores (>80 nm radius) in all three samples. At smaller pore sizes (~5–80 nm radius), the fraction of accessible pores decreases. The lowest accessibility to both fluids is at pore throat size of ~25 nm radii with the quartz-rich sample exhibiting lower accessibility than the clay- and carbonate-rich samples. The mechanism for this behaviour is unclear, but because the mineralogy of the three samples varies, it is likely that the inaccessible pores in this size range are associated with organics and not a specific mineral within the samples. At even smaller pore sizes (~<2.5 nm radius), in all samples, the fraction of accessible pores to water increases again to approximately 70–80%. Accessibility to toluene generally follows that of water; however, in the smallest pores (~<2.5 nm radius), accessibility to toluene decreases, especially in the clay-rich sample which contains about 30% more closed pores than the quartz- and carbonate-rich samples. Results from this study show that mineralogy of producing intervals within a shale reservoir can affect accessibility of pores to water and toluene and these mineralogic differences may affect hydrocarbon storage and production and hydraulic fracturing characteristics

Evaluating mineralogy at terrestrial analogs for early Mars: Detection and characterization of clays with XRD and investigation of iron substitution in natroalunite

NASA Astrophysics Data System (ADS)

Beckerman, Laura Grace

The Mars Science Laboratory (MSL) Curiosity rover is equipped with CheMin, the first x-ray diffraction (XRD) instrument on Mars, for in situ mineralogy as part of its mission to seek evidence of past habitability at Gale Crater. Detection and characterization of hydrated minerals like clays and sulfates provides crucial insight into Mars' early geochemistry. For example, clays are often interpreted as having formed in lacustrine environments at neutral pHs, while sulfates such as jarosite are evidence of acid sulfate alteration. However, CheMin's inability to remove non-clay minerals and to preferentially orient samples may pose significant challenges to clay detection and characterization at Gale Crater. To evaluate the effect of particle size separation (<0.2 microm), removal of non-clay minerals, preferred orientation, and ethylene glycol solvation on XRD analyses of clays, we used both a CheMin analog instrument and a traditional laboratory XRD to identify clays in acid sulfate altered basalt from Mars analog sites in Costa Rica. We detected kaolinite in four of the fourteen samples studied, one of which also contained montmorillonite. Kaolinite was not detected in two samples with the analog instrument prior to clay isolation. These results suggest that CheMin may miss detection of some clays at Gale Crater, which could affect interpretations of early Mars' habitability. Mistaking iron-rich natroalunite (Na[Al,Fe]3(SO4) 2(OH)6) for jarosite (KFe3(SO4) 2(OH)6) could also impact interpretations of early Mars, as natroalunite can form over a broader range of pH, water:rock ratios, and redox conditions than can jarosite. To determine if iron-rich natroalunite is a common alteration product at Mars analog sites, we assessed iron content in natroalunite from Costa Rica. We detected up to 30% iron substitution in natroalunite at diverse geochemical settings. We also evaluated the feasibility of using XRD or Raman spectroscopy for in situ iron-rich natroalunite detection, and determined that CheMin on Curiosity and the Raman Laser Spectrometer on the upcoming ExoMars rover could detect natroalunite with ≥25% iron substitution. Distinguishing between iron-rich natroalunite and jarosite with CheMin could aid in interpreting geochemical conditions and habitability at Gale Crater.

Decolorization of Methyl Orange by a new clay-supported nanoscale zero-valent iron: Synergetic effect, efficiency optimization and mechanism.

PubMed

Li, Xiaoguang; Zhao, Ying; Xi, Beidou; Meng, Xiaoguang; Gong, Bin; Li, Rui; Peng, Xing; Liu, Hongliang

2017-02-01

In this study, a novel nanoscale zero-valent iron (nZVI) composite material was successfully synthesized using a low-cost natural clay, "Hangjin 2 # clay" (HJ clay) as the support and tested for the decolorization of the azo dye Methyl Orange (MO) in aqueous solution by nZVI particles. According to the characterization and MO decolorization experiments, the sample with 5:1 HJ clay-supported nZVI (HJ/nZVI) mass ratio (HJ-nZVI5) showed the best dispersion and reactivity and the highest MO decolorization efficiency. With the same equivalent Fe 0 dosage, the HJ-nZVI1 and HJ-nZVI5 samples demonstrated a synergetic effect for the decolorization of MO: their decolorization efficiencies were much higher than that achieved by physical mixing of HJ clay and nZVIs, or the sum of HJ clay and nZVIs alone. The synergetic effect was primarily due to the improved dispersion and more effective utilization of the nZVI particles on/in the composite materials. Higher decolorization efficiency of MO was obtained at larger HJ-nZVI dosage, higher temperature and under N 2 atmosphere, while the MO initial concentration and pH were negatively correlated to the efficiency. HJ clay not only works as a carrier for nZVI nanoparticles, but also contributes to the decolorization through an "adsorption-enhanced reduction" mechanism. The high efficiency of HJ-nZVI for decontamination gives it great potential for use in a variety of remediation applications. Copyright © 2016. Published by Elsevier B.V.

First characterisation of natural radioactivity in building materials manufactured in Albania.

PubMed

Xhixha, G; Ahmeti, A; Bezzon, G P; Bitri, M; Broggini, C; Buso, G P; Caciolli, A; Callegari, I; Cfarku, F; Colonna, T; Fiorentini, G; Guastaldi, E; Mantovani, F; Massa, G; Menegazzo, R; Mou, L; Prifti, D; Rossi Alvarez, C; Sadiraj Kuqi, Dh; Shyti, M; Tushe, L; Xhixha Kaçeli, M; Zyfi, A

2013-07-01

This study focuses on the radiological characterisation of building materials manufactured in Albania by using a high-resolution gamma-ray spectrometer. The average activity concentrations of (40)K, (226)Ra and (232)Th were, respectively, 644.1±64.2, 33.4 ± 6.4 and 42.2 ± 7.6 Bq kg(-1) in the clay brick samples and 179.7 ± 48.9, 55.0 ± 5.8 and 17.0 ± 3.3 Bq kg(-1) in the cement samples. The calculated activity concentration index (ACI), varied from 0.48±0.02 to 0.63±0.04 in the clay brick samples and from 0.29±0.03 to 0.37±0.02 in the cement samples. Based on the ACI, all of the clay brick and cement samples were categorised as A1 materials. The authors can exclude (at 3σ level) any restriction of their use as bulk materials.

Rheological properties of purified illite clays in glycerol/water suspensions

NASA Astrophysics Data System (ADS)

Dusenkova, I.; Malers, J.; Berzina-Cimdina, L.

2015-04-01

There are many studies about rheological properties of clay-water suspensions, but no published investigations about clay-glycerol suspensions. In this work apparent viscosity of previously purified illite containing clay fraction < 2 μm and glycerol/water suspensions were investigated. Carbonates were removed by dissolution in hydrochloric and citric acids and other non-clay minerals were almost totally removed by centrifugation. All obtained suspensions behaved as shear-thinning fluids with multiple times higher viscosity than pure glycerol/water solutions. Reduction of clay fraction concentration by 5% decreased the apparent viscosity of 50% glycerol/water suspensions approximately 5 times. There was basically no difference in apparent viscosity between all four 50% glycerol/water suspensions, but in 90% glycerol/water suspensions samples from Iecava deposit showed slightly higher apparent viscosity, which could be affected by the particle size distribution.

Strategy for Extracting DNA from Clay Soil and Detecting a Specific Target Sequence via Selective Enrichment and Real-Time (Quantitative) PCR Amplification ▿

PubMed Central

Yankson, Kweku K.; Steck, Todd R.

2009-01-01

We present a simple strategy for isolating and accurately enumerating target DNA from high-clay-content soils: desorption with buffers, an optional magnetic capture hybridization step, and quantitation via real-time PCR. With the developed technique, μg quantities of DNA were extracted from mg samples of pure kaolinite and a field clay soil. PMID:19633108

Geologic columns for the ICDP-USGS Eyreville A and B cores, Chesapeake Bay impact structure: Sediment-clast breccias, 1096 to 444 m depth

USGS Publications Warehouse

Edwards, L.E.; Powars, D.S.; Gohn, G.S.; Dypvik, H.

2009-01-01

The Eyreville A and B cores, recovered from the "moat" of the Chesapeake Bay impact structure, provide a thick section of sediment-clast breccias and minor stratified sediments from 1095.74 to 443.90 m. This paper discusses the components of these breccias, presents a geologic column and descriptive lithologic framework for them, and formalizes the Exmore Formation. From 1095.74 to ??867 m, the cores consist of nonmarine sediment boulders and sand (rare blocks up to 15.3 m intersected diameter). A sharp contact in both cores at ??867 m marks the lowest clayey, silty, glauconitic quartz sand that constitutes the base of the Exmore Formation and its lower diamicton member. Here, material derived from the upper sediment target layers, as well as some impact ejecta, occurs. The block-dominated member of the Exmore Formation, from ??855-618.23 m, consists of nonmarine sediment blocks and boulders (up to 45.5 m) that are juxtaposed complexly. Blocks of oxidized clay are an important component. Above 618.23 m, which is the base of the informal upper diamicton member of the Exmore Formation, the glauconitic matrix is a consistent component in diamicton layers between nonmarine sediment clasts that decrease in size upward in the section. Crystalline-rock clasts are not randomly distributed but rather form local concentrations. The upper part of the Exmore Formation consists of crudely fining-upward sandy packages capped by laminated silt and clay. The overlap interval of Eyreville A and B (940-??760 m) allows recognition of local similarities and differences in the breccias. ?? 2009 The Geological Society of America.

Reflectance spectroscopy of palagonite and iron-rich montmorillonite clay mixtures - Implications for the surface composition of Mars

NASA Technical Reports Server (NTRS)

Orenberg, James; Handy, Jonathan

1992-01-01

The diffuse reflectance spectra of Hawaiian palagonite mixtures with an Fe-rich montmorillonite have prompted their present use as spectral analogs of the Martian surface. Like the Mars spectrum and unlike clays, the 2.2-micron reflectance spectrum absorption band is not present in the palagonite sample; neither is the 2.2-micron Al-OH clay lattice band seen in palagonite-montmorillonite mixtures, where the latter component remains below 15 wt pct. Fe-rich montmorillonite clay may therefore be present in Mars, in combination with palagonite, while remaining undetected in remotely sensed spectra.

Variable Temperature Infrared Spectroscopy Investigations of Benzoic Acid Desorption from Sodium and Calcium Montmorillonite Clays.

PubMed

Nickels, Tara M; Ingram, Audrey L; Maraoulaite, Dalia K; White, Robert L

2015-12-01

Processes involved in thermal desorption of benzoic acid from sodium and calcium montmorillonite clays are investigated by using variable temperature diffuse reflection Fourier transform infrared spectroscopy (DRIFTS). By monitoring the temperature dependence of infrared absorbance bands while heating samples, subtle changes in molecular vibrations are detected and employed to characterize specific benzoic acid adsorption sites. Abrupt changes in benzoic acid adsorption site properties occur for both clay samples at about 125 °C. Difference spectra absorbance band frequency variations indicate that adsorbed benzoic acid interacts with interlayer cations through water bridges and that these interactions can be disrupted by the presence of organic anions, in particular, benzoate.

Preliminary report on the clay mineralogy of the Upper Devonian Shales in the southern and middle Appalachian Basin

USGS Publications Warehouse

Hosterman, John W.; Loferski, Patricia J.

1978-01-01

The distribution of kaolinite in parts of the Devonian shale section is the most significant finding of this work. These shales are composed predominately of 2M illite and illitic mixed-layer clay with minor amounts of chlorite and kaolinite. Preliminary data indicate that kaolinite, the only allogenic clay mineral, is present in successively older beds of the Ohio Shale from south to north in the southern and middle parts of the Appalachian basin. This trend in the distribution of kaolinite shows a paleocurrent direction to the southwest. Three well-known methods of preparing the clay fraction for X-ray diffraction analysis were tested and evaluated. Kaolinite was not identified in two of the methods because of layering due to differing settling rates of the clay minerals. It is suggested that if one of the two settling methods of sample preparation is used, the clay film be thin enough for the X-ray beam to penetrate the entire thickness of clay.

Biodegradation of crude oil saturated fraction supported on clays.

PubMed

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

2014-02-01

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.

The origin and implications of clay minerals from Yellowknife Bay, Gale crater, Mars†

PubMed Central

Bristow, Thomas F.; Bish, David L.; Vaniman, David T.; Morris, Richard V.; Blake, David F.; Grotzinger, John P.; Rampe, Elizabeth B.; Crisp, Joy A.; Achilles, Cherie N.; Ming, Doug W.; Ehlmann, Bethany L.; King, Penelope L.; Bridges, John C.; Eigenbrode, Jennifer L.; Sumner, Dawn Y.; Chipera, Steve J.; Moorokian, John Michael; Treiman, Allan H.; Morrison, Shaunna M.; Downs, Robert T.; Farmer, Jack D.; Marais, David Des; Sarrazin, Philippe; Floyd, Melissa M.; Mischna, Michael A.; McAdam, Amy C.

2016-01-01

The Mars Science Laboratory (MSL) rover Curiosity has documented a section of fluvio-lacustrine strata at Yellowknife Bay (YKB), an embayment on the floor of Gale crater, approximately 500 m east of the Bradbury landing site. X-ray diffraction (XRD) data and evolved gas analysis (EGA) data from the CheMin and SAM instruments show that two powdered mudstone samples (named John Klein and Cumberland) drilled from the Sheepbed member of this succession contain up to ~20 wt% clay minerals. A trioctahedral smectite, likely a ferrian saponite, is the only clay mineral phase detected in these samples. Smectites of the two samples exhibit different 001 spacing under the low partial pressures of H2O inside the CheMin instrument (relative humidity <1%). Smectite interlayers in John Klein collapsed sometime between clay mineral formation and the time of analysis to a basal spacing of 10 Å, but largely remain open in the Cumberland sample with a basal spacing of ~13.2 Å. Partial intercalation of Cumberland smectites by metal-hydroxyl groups, a common process in certain pedogenic and lacustrine settings on Earth, is our favored explanation for these differences. The relatively low abundances of olivine and enriched levels of magnetite in the Sheepbed mudstone, when compared with regional basalt compositions derived from orbital data, suggest that clay minerals formed with magnetite in situ via aqueous alteration of olivine. Mass-balance calculations are permissive of such a reaction. Moreover, the Sheepbed mudstone mineral assemblage is consistent with minimal inputs of detrital clay minerals from the crater walls and rim. Early diagenetic fabrics suggest clay mineral formation prior to lithification. Thermodynamic modeling indicates that the production of authigenic magnetite and saponite at surficial temperatures requires a moderate supply of oxidants, allowing circum-neutral pH. The kinetics of olivine alteration suggest the presence of fluids for thousands to hundreds of thousands of years. Mineralogical evidence of the persistence of benign aqueous conditions at YKB for extended periods indicates a potentially habitable environment where life could establish itself. Mediated oxidation of Fe2+ in olivine to Fe3+ in magnetite, and perhaps in smectites provided a potential energy source for organisms. PMID:28798492

The origin and implications of clay minerals from Yellowknife Bay, Gale crater, Mars.

PubMed

Bristow, Thomas F; Bish, David L; Vaniman, David T; Morris, Richard V; Blake, David F; Grotzinger, John P; Rampe, Elizabeth B; Crisp, Joy A; Achilles, Cherie N; Ming, Doug W; Ehlmann, Bethany L; King, Penelope L; Bridges, John C; Eigenbrode, Jennifer L; Sumner, Dawn Y; Chipera, Steve J; Moorokian, John Michael; Treiman, Allan H; Morrison, Shaunna M; Downs, Robert T; Farmer, Jack D; Marais, David Des; Sarrazin, Philippe; Floyd, Melissa M; Mischna, Michael A; McAdam, Amy C

2015-04-01

The Mars Science Laboratory (MSL) rover Curiosity has documented a section of fluvio-lacustrine strata at Yellowknife Bay (YKB), an embayment on the floor of Gale crater, approximately 500 m east of the Bradbury landing site. X-ray diffraction (XRD) data and evolved gas analysis (EGA) data from the CheMin and SAM instruments show that two powdered mudstone samples (named John Klein and Cumberland) drilled from the Sheepbed member of this succession contain up to ~20 wt% clay minerals. A trioctahedral smectite, likely a ferrian saponite, is the only clay mineral phase detected in these samples. Smectites of the two samples exhibit different 001 spacing under the low partial pressures of H 2 O inside the CheMin instrument (relative humidity <1%). Smectite interlayers in John Klein collapsed sometime between clay mineral formation and the time of analysis to a basal spacing of 10 Å, but largely remain open in the Cumberland sample with a basal spacing of ~13.2 Å. Partial intercalation of Cumberland smectites by metal-hydroxyl groups, a common process in certain pedogenic and lacustrine settings on Earth, is our favored explanation for these differences. The relatively low abundances of olivine and enriched levels of magnetite in the Sheepbed mudstone, when compared with regional basalt compositions derived from orbital data, suggest that clay minerals formed with magnetite in situ via aqueous alteration of olivine. Mass-balance calculations are permissive of such a reaction. Moreover, the Sheepbed mudstone mineral assemblage is consistent with minimal inputs of detrital clay minerals from the crater walls and rim. Early diagenetic fabrics suggest clay mineral formation prior to lithification. Thermodynamic modeling indicates that the production of authigenic magnetite and saponite at surficial temperatures requires a moderate supply of oxidants, allowing circum-neutral pH. The kinetics of olivine alteration suggest the presence of fluids for thousands to hundreds of thousands of years. Mineralogical evidence of the persistence of benign aqueous conditions at YKB for extended periods indicates a potentially habitable environment where life could establish itself. Mediated oxidation of Fe 2+ in olivine to Fe 3+ in magnetite, and perhaps in smectites provided a potential energy source for organisms.

Resource Materials for the Creative Curriculum (With Special Articles on Evaluating the Black & Hispanic Image in Children's Books).

ERIC Educational Resources Information Center

Frisby, Deborah

This annotated bibliography of early childhood curriculum materials is divided into two major sections. The first section reviews materials pertaining to house corner, blocks, table toys, art, clay and play dough, water and sand activities. Within these areas, entries are divided into three main lists: books, articles, and children's books. ERIC…

Novel Organically Modified Core-Shell Clay for Epoxy Composites-"SOBM Filler 1".

PubMed

Iheaturu, Nnamdi Chibuike; Madufor, Innocent Chimezie

2014-01-01

Preparation of a novel organically modified clay from spent oil base drilling mud (SOBM) that could serve as core-shell clay filler for polymers is herein reported. Due to the hydrophilic nature of clay, its compatibility with polymer matrix was made possible through modification of the surface of the core clay sample with 3-aminopropyltriethoxysilane (3-APTES) compound prior to its use. Fourier transform infrared (FT-IR) spectroscopy was used to characterize clay surface modification. Electron dispersive X-ray diffraction (EDX) and scanning electron microscopy (SEM) were used to expose filler chemical composition and morphology, while electrophoresis measurement was used to examine level of filler dispersion. Results show an agglomerated core clay powder after high temperature treatment, while EDX analysis shows that the organically modified clay is composed of chemical inhomogeneities, wherein elemental compositions in weight percent vary from one point to the other in a probe of two points. Micrographs of the 3-APTES coupled SOBM core-shell clay filler clearly show cloudy appearance, while FT-IR indicates 25% and 5% increases in fundamental vibrations band at 1014 cm(-1) and 1435 cm(-1), respectively. Furthermore, 3-APTES coupled core-shell clay was used to prepare epoxy composites and tested for mechanical properties.

Novel Organically Modified Core-Shell Clay for Epoxy Composites—“SOBM Filler 1”

PubMed Central

Iheaturu, Nnamdi Chibuike; Madufor, Innocent Chimezie

2014-01-01

Preparation of a novel organically modified clay from spent oil base drilling mud (SOBM) that could serve as core-shell clay filler for polymers is herein reported. Due to the hydrophilic nature of clay, its compatibility with polymer matrix was made possible through modification of the surface of the core clay sample with 3-aminopropyltriethoxysilane (3-APTES) compound prior to its use. Fourier transform infrared (FT-IR) spectroscopy was used to characterize clay surface modification. Electron dispersive X-ray diffraction (EDX) and scanning electron microscopy (SEM) were used to expose filler chemical composition and morphology, while electrophoresis measurement was used to examine level of filler dispersion. Results show an agglomerated core clay powder after high temperature treatment, while EDX analysis shows that the organically modified clay is composed of chemical inhomogeneities, wherein elemental compositions in weight percent vary from one point to the other in a probe of two points. Micrographs of the 3-APTES coupled SOBM core-shell clay filler clearly show cloudy appearance, while FT-IR indicates 25% and 5% increases in fundamental vibrations band at 1014 cm−1 and 1435 cm−1, respectively. Furthermore, 3-APTES coupled core-shell clay was used to prepare epoxy composites and tested for mechanical properties. PMID:27355022

Influence of Alkali Resistant (Ar) Fibreglass in Porcelain Clay for Manufacturing Vitrified Clay Pipes

NASA Astrophysics Data System (ADS)

Ikhmal Hanapi, Muhammad; Ahmad, Sufizar; Taib, Hariati; Ismail, Al Emran; Nasrull Abdol Rahman, Mohd; Salleh, Salihatun Md; Sadikin, Azmahani; Mahzan, Shahruddin

2017-10-01

The aim of this work is to determine the characteristics of porcelain ceramic with influence of milled Alkali Resistant (AR) fiberglass for manufacturing vitrified clay pipes. In this study, raw materials consist of porcelain clay and AR fiberglass were refined into powders less than 90μm. Subsequently, these samples were compacted into cylindrical pellet for chemical analysis using X-Ray Fluorescence (XRF). The ceramic sample was produced by mixing different weight percentage of AR glass to porcelain ceramic with 3 wt%, 6 wt%, 9 wt% and 12 wt%. Subsequently, the sample was compacted with 3 ton of pressure load and sintered at 900 °C, 1000 °C, 1100 °C and 1200 °C. The phase identification by using X-Ray Diffraction (XRD) and microstructural analysis were performed for the sintered sample. Chemical analysis revealed that the significant element for all raw material are SiO2, Al2O3, Na2O and K2O. Phase identification analysis shown that sample sintered at 1000 °C produces quartz (SiO2), berlinite (AlPO4), albite (NaAlSi3O8) and calcium-magnesium-aluminum-silicate (CaMgAlSiO). The formation of primary mullite was observed in sample sintered at 1100 °C. The image of microstructural morphology denoted that the formation of glassy phase with decreasing amount of void when sintering temperature and addition of AR glass were increased, which correspond well to phase identification analysis.

Lactate Injection by Electric Currents for Bioremediation of Tetrachloroethylene in Clay

PubMed Central

Wu, Xingzhi; Gent, David B.; Davis, Jeffrey L.; Alshawabkeh, Akram N.

2012-01-01

Biological transformation of tetrachloroethylene (PCE) in silty clay samples by ionic injection of lactate under electric fields is evaluated. To prepare contaminated samples, a silty clay slurry was mixed with PCE, inoculated with KB-1® dechlorinators and was consolidated in a 40 cm long cell. A current density between 5.3 and 13.3 A m−2 was applied across treated soil samples while circulating electrolytes containing 10 mg L−1 lactate concentration between the anode and cathode compartments to maintain neutral pH and chemically reducing boundary conditions. The total adsorbed and aqueous PCE was degraded in the soil to trichloroethylene (TCE), cis-1,2-dichloroethene (cis-DCE), vinyl chloride (VC) and ethene in 120 d, which is about double the time expected for transformation. Lactate was delivered into the soil by a reactive transport rate of 3.7 cm2 d−1 V−1. PCE degradation in the clay samples followed zero order transformation rates ranging from 1.5 to 5 mg L−1 d−1 without any significant formation of TCE. cis-DCE transformation followed first order transformation rates of 0.06 to 0.10 per day. A control experiment conducted with KB-1 and lactate, but without electricity did not show any significant lactate buildup or cis-DCE transformation because the soil was practically impermeable (hydraulic conductivity of 2×10−7 cm s−1). It is concluded that ionic migration will deliver organic additives and induce biological activity and complete PCE transformation in clay, even though the transformation occurs under slower rates compared to ideal conditions. PMID:23264697

Geology and resources of the Andersonville, Georgia, kaolin and bauxite district

USGS Publications Warehouse

Cofer, Harland E.; Manker, John Phillip

1983-01-01

The kaolin and kaolin-rich sediments of the Andersonville district were deposited in an estuary environment with restricted circulation and little tidal or longshore current influence. Micaceous kaolinitic clays were deposited during late Paleocene time on broad, shallow water flats between deeper water distributary channels in the estuarine system. During the cycle of deposition, kaolinitic sediments were temporarily exposed to weathering leading to bauxitization and further kaolinization. Subsequently, subaerial and/or subaqueous erosion planed off and redeposited some of the weathering products as organic-rich clays and silts, berthierine-bearing clays, and rarely as colluvial bauxite and sedimentary bauxitic clays. Upon resubmergence, gibbsite-rich, porous bauxite, and bauxitic clays were exposed to silica-saturated water of the estuary. Gibbsite reacted with silica to form kaolinite and resulted in the formation of the transitional (bauxitic) clays overlying the bauxite. Kaolinitic sediments transported by streams again spread over the altered and redeposited material. At the close of the kaolin depositional period movement along the Andersonville Fault Zone and related faults changed the basinal configuration, and the area of the uplifted (southern) block of the fault was exposed to weathering and bauxitization for a limited period of time. General submergence again occurred and much of the district was covered by marine and brackish water, ending the period of commercial kaolin deposition. The kaolin and bauxite deposits in the Andersonville district form a broad belt 15 kilometers wide and 22 kilometers long trending in a northwest-southeastward direction. Most of the kaolin and bauxite of commercial value occur within a narrow 10-kilometer-wide zone in the belt. The reserves of kaolin suitable for refractory and chemical use are approximately 290 million tonnes. Paramarginal resources of sandy kaolin suitable for refractory, chemical, or aluminum manufacture after beneficiation are approximately 240 million tonnes. Indicated and inferred reserves of bauxite and bauxitic clay are 1.8 million tonnes and 7.3 million tonnes respectively.

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

PubMed

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

1994-03-01

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

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

NASA Technical Reports Server (NTRS)

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

1994-01-01

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

Phosphates in some Missouri refractory clays

USGS Publications Warehouse

Halley, Robert B.; Foord, Eugene E.; Keller, David J.; Keller, Walter D.

1997-01-01

This paper describes in detail phosphate minerals occurring in refractory clays of Missouri and their effect on the refractory degree of the clays. The minerals identified include carbonate-fluorapatite (francolite), crandallite, goyazite, wavellite, variscite and strengite. It is emphasized that these phosphates occur only in local isolated concentrations, and not generally in Missouri refractory clays.The Missouri fireclay region comprises 2 districts, northern and southern, separated by the Missouri River. In this region, clay constitutes a major part of the Lower Pennsylvanian Cheltenham Formation. The original Cheltenham mud was an argillic residue derived from leaching and dissolution of pre-Pennsylvanian carbonates. The mud accumulated on a karstic erosion surface truncating the pre-Cheltenham rocks. Fireclays of the northern district consist mainly of poorly ordered kaolinite, with variable but minor amounts of illite, chlorite and fine-grained detrital quartz. Clays of the southern district were subjected to extreme leaching that produced well-ordered kaolinite flint clays. Local desilication formed pockets of diaspore, or more commonly, kaolinite, with oolite-like nubs or burls of diaspore (“burley”" clay).The phosphate-bearing materials have been studied by X-ray diffraction (XRD), scanning electron microscopy-energy dispersive spectral analysis (SEM-EDS) and chemical analysis. Calcian goyazite was identified in a sample of diaspore, and francolite in a sample of flint clay. A veinlet of wavellite occurs in flint clay at one locality, and a veinlet of variscite-strengite at another locality.The Missouri flint-clay-hosted francolite could not have formed in the same manner as marine francolite. The evidence suggests that the Cheltenham francolite precipitated from ion complexes in pore water, nearly simultaneously with crystallization of kaolinite flint clay from an alumina-silica gel. Calcian goyazite is an early diagenetic addition to its diaspore host. The wavellite and variscite-strengite veinlets are secondary, precipitated from ion complexes in ground water percolating along cracks in the flint clay. The flint clay host of the variscite-strengite veinlet contains strontian crandallite. All of the phosphates contain significant amounts of strontium. The source of P, Ca and Sr was the marine carbonates. Dissolution of these carbonates produced the argillic residue that became the primordial Cheltenham paludal mud, which ultimately altered to fireclay.Preliminary firing tests show that the presence of phosphates lowers fusion temperature. However, it is not clear whether poor refractoriness is due to the presence of phosphates, per se, or to Ca, Sr and other alkaline elements present in the phosphates.

Compaction and Plasticity Comparative Behaviour of Soft Clay Treated with Coarse and Fine Sizes of Ceramic Tiles

NASA Astrophysics Data System (ADS)

Al-Bared, Mohammed Ali Mohammed; Marto, Aminaton; Sati Hamonangan Harahap, Indra; Kasim, Fauziah

2018-03-01

Recycled blended ceramic tiles (RBT) is a waste material produced from ceramic tile factories and construction activities. RBT is found to be cost effective, sustainable, environmental-friendly and has the potential to be used as an additive in soft soil stabilization. Recent reports show that massive amounts of RBT are dumped into legal or illegal landfills every year consuming very large spaces and creating major environmental problems. On the other hand, dredged marine clay obtained from Nusajaya, Johor, Malaysia has weak physical and engineering characteristics to be considered as unsuitable soft soil that is usually excavated, dumped into landfills and replaced by stiff soil. Hence, this study investigates the suitability of possible uses of RBT to treat marine clay. Laboratory tests included Standard proctor tests and Atterberg limits tests. The plasticity of marine clay was evaluated by adding 10%, 20%, 30% and 40% of 0.3 mm RBT. In addition, the compaction behaviour of treated marine clay was compared by adding two different sizes (0.3 mm and 1.18 mm diameter) of RBT. For both coarse and fine sizes of RBT, 10%, 20%, 30% and 40% of the dry weight of the soft clay were added. The mixture of each combination was examined in order to evaluate the Maximum Dry Density (MDD) and the optimum moisture content (OMC) for the treated soft clay. MDD and OMC for soft untreated samples were 1.59 Mg/m3 and 22%, respectively. Treated samples with 10%, 20%, 30% and 40% of 0.30 mm size RBT resulted in a significant reduction of OMC ranged from 19 to 15% while MDD resulted in increment ranged from 1.69 to 1.77 Mg/m3. In addition, samples treated with 10%, 20%, 30% and 40% of 1.18 mm size RBT resulted in major reduction of OMC ranged from 15 to 13.5% while MDD increased effectively from 1.75 to 1.82 Mg/m3. For all mix designs of soft clay-RBT, MDD was gradually increasing and OMC was sharply reducing with further increments of both sizes of RBT.

Structure and clay mineralogy: borehole images, log interpretation and sample analyses at Site C0002 Nankai Trough accretionary prism

NASA Astrophysics Data System (ADS)

Jurado, Maria Jose; Schleicher, Anja

2015-04-01

Our research focused on the characterization of fracture and fault structures from the deep Nankai Trough accretionary prism in Japan. Logging Data and cuttings samples from the two most recent International Ocean Discovery Program (IODP) Expeditions 338 and 348 of the NanTroSEIZE project were analyzed by Logging While Drilling (LWD) oriented images, geophysical logs and clay mineralogy. Both expeditions took place at Site C0002, but whereas Hole C0002F (Expedition 338) was drilled down to 2004.5 mbsf, Hole C0002N and C0002P (Expedition 348) reached a depth of 2325.5 mbsf and 3058.8 mbsf respectively. The structural interpretation of borehole imaging data illustrates the deformation within the fractured and faulted sections of the accretionary prism. All drill holes show distinct areas of intense fracturing and faulting within a very clay-dominated lithology. Here, smectite and illite are the most common clay minerals, but the properties and the role they may play in influencing the fractures, faults and folds in the accretionary prism is still not well understood. When comparing clay mineralogy and fracture/fault areas in hole C0002F (Expedition 338), a trend in the abundance of illite and smectite, and in particular the swelling behavior of smectite is recognizable. In general, the log data provided a good correlation with the actual mineralogy and the relative abundance of clay. Ongoing postcruise preliminary research on hole C0002 N and C0002P (Expedition 348) should confirm these results. The relationship between fracture and fault structures and the changes in clay mineralogy could be explained by the deformation of specific areas with different compaction features, fluid-rock interaction processes, but could also be related to beginning diagenetic processes related to depth. Our results show the integration of logging data and cutting sample analyses as a valuable tool for characterization of petrophysical and mineralogical changes of the structures of the Nankai accretionary prism. This is critical for our understanding of clay-fluid interaction and mechanical properties duing fault displacements and seismogenesis.

U.S. Geological survey program on toxic waste--ground-water contamination; proceedings of the Second technical meeting, Cape Cod, Massachusetts, October 21-25, 1985

USGS Publications Warehouse

Ragone, S.E.

1988-01-01

This study characterizes the clay minerals in sediments associated with a plume of creosote-contaminated groundwater. The plume of contaminated groundwater near Pensacola, FL, is in shallow, permeable, Miocene to Holocene quartz sand and flows southward toward Pensacola Bay. Clay-size fractions were separated from 41 cores, chiefly split-spoon samples at 13 drill sites. The most striking feature of the chemical analyses of the clay fractions from uncontaminated site 2 and contaminated sites 4,5,6, and 7 is the variability of iron oxide (species in some samples as Fe2O3); total iron oxide abundance is lowest (2.5%) in uncontaminated sample 2-40, but is > 4.5% (4.5 to 8.5%) in the remaining assemblages. One feature suggesting interaction between the indigenous clays and the waste plume is the presence of nontronite-rich smectite. Nontronite commonly has been identified as the product of hydrothermal alteration and deep-sea weathering of submarine basalts; it is not a common constituent of Cenozoic Gulf Coast sediments. At the Pensacola site, relatively abundant nontronitic smectite is confined to contaminated sands or associated muds; it is least abundant or absent in sands and muds peripheral to the waste plume. The geochemistry of the waste plume, its substantial dissolved, (chiefly ferrous iron), mildly acidic (pH 5-6), and low redox composition, provides an environment similar to that previously determined for the low-temperature synthesis of nontronite. Data from clay-size fractions confirm conclusions that neoformed pyrite in some grain coatings occurs in an assemblage with excess iron over that required in the pyrite. Continuing studies to evaluate these tentative conclusions include: (1) chemical analysis of clay fractions from remaining sites to further examine the apparent relation between iron content and abundance of nontronitic smectite; (2) clay separation and analysis, and pore fluid extraction (squeezing or ultracentrifugation) and analysis from a continuous core through the mud lens to determine pore fluid composition (presence or absence of waste fluid), and character of associated clay minerals; and (3) clay separation and analysis in both permeable sands and the intervening mud lens that are clearly outside the limits of the waste plume to further document the effects of the plume. (See also W90-00022) (Lantz-PTT)

Petrography, mineralogy, and geochemistry of deep gravelly sands in the Eyreville B core, Chesapeake Bay impact structure

USGS Publications Warehouse

Bartosova, Katerina; Gier, Susanne; Horton, J. Wright; Koeberl, Christian; Mader, Dieter; Dypvik, Henning

2010-01-01

The ICDP–USGS Eyreville drill cores in the Chesapeake Bay impact structure reached a total depth of 1766 m and comprise (from the bottom upwards) basement-derived schists and granites/pegmatites, impact breccias, mostly poorly lithified gravelly sand and crystalline blocks, a granitic slab, sedimentary breccias, and postimpact sediments. The gravelly sand and crystalline block section forms an approximately 26 m thick interval that includes an amphibolite block and boulders of cataclastic gneiss and suevite. Three gravelly sands (basal, middle, and upper) are distinguished within this interval. The gravelly sands are poorly sorted, clast supported, and generally massive, but crude size-sorting and subtle, discontinuous layers occur locally. Quartz and K-feldspar are the main sand-size minerals and smectite and kaolinite are the principal clay minerals. Other mineral grains occur only in accessory amounts and lithic clasts are sparse (only a few vol%). The gravelly sands are silica rich (~80 wt% SiO2). Trends with depth include a slight decrease in SiO2 and slight increase in Fe2O3. The basal gravelly sand (below the cataclasite boulder) has a lower SiO2 content, less K-feldspar, and more mica than the higher sands, and it contains more lithic clasts and melt particles that are probably reworked from the underlying suevite. The middle gravelly sand (below the amphibolite block) is finer-grained, contains more abundant clay minerals, and displays more variable chemical compositions than upper gravelly sand (above the block). Our mineralogical and geochemical results suggest that the gravelly sands are avalanche deposits derived probably from the nonmarine Potomac Formation in the lower part of the target sediment layer, in contrast to polymict diamictons higher in the core that have been interpreted as ocean-resurge debris flows, which is in agreement with previous interpretations. The mineralogy and geochemistry of the gravelly sands are typical for a passive continental margin source. There is no discernible mixing with marine sediments (no glauconite or Paleogene marine microfossils noted) during the impact remobilization and redeposition. The unshocked amphibolite block and cataclasite boulder might have originated from the outer parts of the transient crater.

Effect of carbonate content on the mechanical behaviour of clay fault-gouges

NASA Astrophysics Data System (ADS)

Bakker, Elisenda; Niemeijer, André; Hangx, Suzanne; Spiers, Chris

2015-04-01

Carbon dioxide capture and storage (CCS) in depleted oil and gas reservoirs is considered to be the most promising technology to achieve large-scale reduction in anthropogenic emissions. In order to retain the stored CO2 from the atmosphere for the very long-term, i.e. on timescales of the order of 103-104 years, it is essential to maintain the integrity of the caprock, and more specifically of any faults penetrating the seal. When selecting suitable CO2-storage reservoirs, pre-exisiting faults within the caprock require close attention, as changes in the stress state resulting from CO2-injection may induce fault slip motion which might cause leakage. Little is known about the effect of fluid-rock interactions on the mineral composition, mechanical properties and the integrity and sealing capacity of the caprock. Previous studies on the effect of mineral composition on the frictional properties of fault gouges have shown that friction is controlled by the dominant phase unless there is a frictionally weak, through-going fabric. However, the effect on stability is less clear. Since long-term CO2-exposure might cause chemical reactions, potentially resulting in the dissolution or precipitation of carbonate minerals, a change in mineralogy could affect the mechanical stability of a caprock significantly. Calcite, for example, is known to be prone to micro-seismicity and shows a transition from velocity-strengthening to velocity-weakening behaviour around 100-150°C. Therefore, we investigated the effect of varying clay:carbonate ratios on fault friction behaviour, fault reactivation potential and slip stability, i.e. seismic vs. aseismic behaviour. Three types of simulated fault gouges were used: i) carbonate-free, natural clay-rich caprock samples, consisting of predominantly phyllosilicates (~80%) and quartz ~20%), ii) pure calcite, and iii) mixtures of carbonate-free clay-rich caprock and pure calcite, with predetermined clay:carbonate ratios. For the natural clay-rich caprock material we used Opalinus Claystone (Mont Terri, Switserland), which is considered to be an analogue for many shaly caprocks in Europe. We performed rotary shear experiments at in-situ reservoir conditions (T = 20-150˚C, σneff = 50 MPa, Pp = 25 MPa) at shear velocities of 0.22 -100 μm/s. Preliminary results show that the frictional strength of the carbonate-free, natural clay-rich caprock samples is 40-50% lower than for the pure calcite samples. Typical steady-state friction coefficient values obtained for the carbonate-free clay samples are ~0.3-0.4. These values are significantly smaller than the values of ~0.6-0.7 obtained for pure calcite. The friction coefficient values obtained for the mixture plot between the carbonate-free and pure calcite values. The samples show predominantly velocity-strengthening behaviour. However, the 90% pure calcite (and 10% clay-rich caprock) and 100% pure calcite samples show velocity-weakening behaviour at 100-150°C. This suggests that large amounts of carbonates, and thus significant carbonate precipitation as a result of CO2-exposure, are required to cause a transition from aseismic to seismic behaviour, at least under the experimental conditions investigated here.

Geological modeling of a fault zone in clay rocks at the Mont-Terri laboratory (Switzerland)

NASA Astrophysics Data System (ADS)

Kakurina, M.; Guglielmi, Y.; Nussbaum, C.; Valley, B.

2016-12-01

Clay-rich formations are considered to be a natural barrier for radionuclides or fluids (water, hydrocarbons, CO2) migration. However, little is known about the architecture of faults affecting clay formations because of their quick alteration at the Earth's surface. The Mont Terri Underground Research Laboratory provides exceptional conditions to investigate an un-weathered, perfectly exposed clay fault zone architecture and to conduct fault activation experiments that allow explore the conditions for stability of such clay faults. Here we show first results from a detailed geological model of the Mont Terri Main Fault architecture, using GoCad software, a detailed structural analysis of 6 fully cored and logged 30-to-50m long and 3-to-15m spaced boreholes crossing the fault zone. These high-definition geological data were acquired within the Fault Slip (FS) experiment project that consisted in fluid injections in different intervals within the fault using the SIMFIP probe to explore the conditions for the fault mechanical and seismic stability. The Mont Terri Main Fault "core" consists of a thrust zone about 0.8 to 3m wide that is bounded by two major fault planes. Between these planes, there is an assembly of distinct slickensided surfaces and various facies including scaly clays, fault gouge and fractured zones. Scaly clay including S-C bands and microfolds occurs in larger zones at top and bottom of the Mail Fault. A cm-thin layer of gouge, that is known to accommodate high strain parts, runs along the upper fault zone boundary. The non-scaly part mainly consists of undeformed rock block, bounded by slickensides. Such a complexity as well as the continuity of the two major surfaces are hard to correlate between the different boreholes even with the high density of geological data within the relatively small volume of the experiment. This may show that a poor strain localization occurred during faulting giving some perspectives about the potential for reactivation and leakage of faults affecting clay materials.

Reactivity of clay minerals with acids and alkalies

USGS Publications Warehouse

Carroll, Dorothy; Starkey, Harry C.

1971-01-01

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

Geothermal alteration of basaltic core from the Snake River Plain, Idaho

NASA Astrophysics Data System (ADS)

Sant, Christopher J.

The Snake River Plain is located in the southern part of the state of Idaho. The eastern plain, on which this study focuses, is a trail of volcanics from the Yellowstone hotspot. Three exploratory geothermal wells were drilled on the Snake River Plain. This project analyzes basaltic core from the first well at Kimama, north of Burley, Idaho. The objectives of this project are to establish zones of geothermal alteration and analyze the potential for geothermal power production using sub-aquifer resources on the axial volcanic zone of the Snake River Plain. Thirty samples from 1,912 m of core were sampled and analyzed for clay content and composition using X-ray diffraction. Observations from core samples and geophysical logs are also used to establish alteration zones. Mineralogical data, geophysical log data and physical characteristics of the core suggest that the base of the Snake River Plain aquifer at the axial zone is located 960 m below the surface, much deeper than previously suspected. Swelling smectite clay clogs pore spaces and reduces porosity and permeability to create a natural base to the aquifer. Increased temperatures favor the formation of smectite clay and other secondary minerals to the bottom of the hole. Below 960 m the core shows signs of alteration including color change, formation of clay, and filling of other secondary minerals in vesicles and fractured zones of the core. The smectite clay observed is Fe-rich clay that is authigenic in some places. Geothermal power generation may be feasible using a low temperature hot water geothermal system if thermal fluids can be attained near the bottom of the Kimama well.

Effects of exchanged cation on the microporosity of montmorillonite

USGS Publications Warehouse

Rutherford, David W.; Chiou, Cary T.; Eberl, Dennis D.

1997-01-01

The micropore volumes of 2 montmorillonites (SAz-1 and SWy-1), each exchanged with Ca, Na, K, Cs and tetramethylammonium (TMA) ions, were calculated from the measured vapor adsorption data of N2 and neo-hexane by use of t- and αs-plots. The corresponding surface areas of the exchanged clays were determined from Brunauer-Emmett-Teller (BET) plots of N2 adsorption data. Micropore volumes and surface areas of the samples increased with the size of exchanged cation: TMA > Cs > K > Ca > Na. The SAz-1 exchanged clays showed generally greater micropore volumes and surface areas than the corresponding SWy-1 clays. The vapor adsorption data and d(001) measurements for dry clay samples were used together to evaluate the likely locations and accessibility of clay micropores, especially the relative accessibility of their interlayer spacing. For both source clays exchanged with Na, Ca and K ions, the interlayer spacing appeared to be too small to admit nonpolar gases and the accessible micropores appeared to have dimensions greater than 5.0 Å, the limiting molecular dimension of neo-hexane. In these systems, there was a good consistency of micropore volumes detected by N2 and neo-hexane. When the clays were intercalated with relatively large cations (TMA and possibly Cs), the large layer expansion created additional microporosity, which was more readily accessible to small N2 than to relatively large neo-hexane. Hence, the micropore volume as detected by N2 was greater than that detected by neo-hexane. The micropore volumes with pore dimensions greater than 5 Å determined for clays exchanged with Na, Ca and K likely resulted from the pores on particle edges and void created by overlap regions of layers. The increase in micropore volumes with pore dimensions less than 5 Å determined for clays exchanged with TMA and possibly Cs could be caused by opening of the interlayer region by the intercalation of these large cations.

Bentonite Clay Adsorption Procedure for Concentrating Enteroviruses from Water.

DTIC Science & Technology

1992-07-01

1 pm (nominal porosity) wool filter bags, and filter beds of sand, glass, or diatomaceous earth , did not retain clay- adsorbed virus as effectively as...number) L/ A method of adsorbing enteroviruses to bentonite clay was developed for use as a concentration technique designed to sample low levels of...bentonite within a 20 minute contact period. A minimum bentonite level of 50 mg/L was necessary to adsorb the virus and to still allow efficient

Evaluation of free water and water activity measurements as functional alternatives to total moisture content in broiler excreta and litter samples.

PubMed

van der Hoeven-Hangoor, E; Rademaker, C J; Paton, N D; Verstegen, M W A; Hendriks, W H

2014-07-01

Litter moisture contents vary greatly between and within practical poultry barns. The current experiment was designed to measure the effects of 8 different dietary characteristics on litter and excreta moisture content. Additionally, free water content and water activity of the excreta and litter were evaluated as additional quality measures. The dietary treatments consisted of nonstarch polysaccharide content (NSP; corn vs. wheat), particle size of insoluble fiber (coarse vs. finely ground oat hulls), viscosity of a nonfermentable fiber (low- and high-viscosity carboxymethyl cellulose), inclusion of a clay mineral (sepiolite), and inclusion of a laxative electrolyte (MgSO4). The 8 treatments were randomly assigned to cages within blocks, resulting in 12 replicates per treatment with 6 birds per replicate. Limited effects of the dietary treatments were noted on excreta and litter water activity, and indications were observed that this measurement is limited in high-moisture samples. Increasing dietary NSP content by feeding a corn-based diet (low NSP) compared with a wheat-based diet (high NSP) increased water intake, excreta moisture and free water, and litter moisture content. Adding insoluble fibers to the wheat-based diet reduced excreta and litter moisture content, as well as litter water activity. Fine grinding of the oat hulls diminished the effect on litter moisture and water activity. However, excreta moisture and free water content were similar when fed finely or coarsely ground oat hulls. The effects of changing viscosity and adding a clay mineral or laxative deviated from results observed in previous studies. Findings of the current experiment indicate a potential for excreta free water measurement as an additional parameter to assess excreta quality besides total moisture. The exact implication of this parameter warrants further investigation. © 2014 Poultry Science Association Inc.

Analysis of wall plasters and natural sediments from the Neolithic town of Çatalhöyük (Turkey) by a range of analytical techniques

NASA Astrophysics Data System (ADS)

Anderson, Emma; Almond, Matthew J.; Matthews, Wendy

2014-12-01

Wall plaster sequences from the Neolithic town of Çatalhöyük have been analysed and compared to three types of natural sediment found in the vicinity of the site, using a range of analytical techniques. Block samples containing the plaster sequences were removed from the walls of several different buildings on the East Mound. Sub-samples were examined by IR spectroscopy, X-ray diffraction and X-ray fluorescence to determine the overall mineralogical and elemental composition, whilst thin sections were studied using optical polarising microscopy, IR Microscopy and Environmental Scanning Electron Microscopy with Energy Dispersive X-ray analysis. The results of this study have shown that there are two types of wall plaster found in the sequences and that the sediments used to produce these were obtained from at least two distinct sources. In particular, the presence of clay, calcite and magnesian calcite in the foundation plasters suggested that these were prepared predominantly from a marl source. On the other hand, the finishing plasters were found to contain dolomite with a small amount of clay and no calcite, revealing that softlime was used in their preparation. Whilst marl is located directly below and around Çatalhöyük, the nearest source of softlime is 6.5 km away, an indication that the latter was important to the Neolithic people, possibly due to the whiter colour (5Y 8/1) of this sediment. Furthermore, the same two plaster types were found on each wall of Building 49, the main building studied in this research, and in all five buildings investigated, suggesting that the use of these sources was an established practice for the inhabitants of several different households across the site.

Deformation and Fabric in Compacted Clay Soils

NASA Astrophysics Data System (ADS)

Wensrich, C. M.; Pineda, J.; Luzin, V.; Suwal, L.; Kisi, E. H.; Allameh-Haery, H.

2018-05-01

Hydromechanical anisotropy of clay soils in response to deformation or deposition history is related to the micromechanics of platelike clay particles and their orientations. In this article, we examine the relationship between microstructure, deformation, and moisture content in kaolin clay using a technique based on neutron scattering. This technique allows for the direct characterization of microstructure within representative samples using traditional measures such as orientation density and soil fabric tensor. From this information, evidence for a simple relationship between components of the deviatoric strain tensor and the deviatoric fabric tensor emerge. This relationship may provide a physical basis for future anisotropic constitutive models based on the micromechanics of these materials.

Radioactivity of Fertilizer and China (NORM) in Japan

DOE Office of Scientific and Technical Information (OSTI.GOV)

Michikuni, Shimo; Yuka, Matsuura; Noriko, Itoh

2008-08-07

Radioactivity of 6 fertilizer samples, 7 china clay samples and 5 china glaze samples, which are commonly used in Japan, was measured using a NaI(Tl) scintillation spectrometer. Potassium activity of fertilizer was almost 540-740 Bq/kg, and the highest activity was 9,100 Bq/kg. Activity of fertilizer was 10 times higher for potassium than for uranium-series. Furthermore, these activities were 25 times for potassium and 18 times for uranium-series in comparison with those in natural soil. In china clay, activities of potassium, uranium-series nuclides and thorium-series nuclides were 543-823 Bq/kg, 74.6-94.3 Bq/kg, and 86.3-128 Bq/kg, respectively. These were 1.5-2.2, 2.1-2.6 and 2.3-3.5more » times higher than activity of common soil. Activity of glaze was almost equal to that of china clay.« less

Permeability and compressibility of resedimented Gulf of Mexico mudrock

NASA Astrophysics Data System (ADS)

Betts, W. S.; Flemings, P. B.; Schneider, J.

2011-12-01

We use a constant-rate-of strain consolidation test on resedimented Gulf of Mexico mudrock to determine the compression index (Cc) to be 0.618 and the expansion index (Ce) to be 0.083. We used crushed, homogenized Pliocene and Pleistocene mudrock extracted from cored wells in the Eugene Island block 330 oil field. This powdered material has a liquid limit (LL) of 87, a plastic limit (PL) of 24, and a plasticity index (PI) of 63. The particle size distribution from hydrometer analyses is approximately 65% clay-sized particles (<2 μm) with the remainder being less than 70 microns in diameter. Resedimented specimens have been used to characterize the geotechnical and geophysical behavior of soils and mudstones independent of the variability of natural samples and without the effects of sampling disturbance. Previous investigations of resedimented offshore Gulf of Mexico sediments (e.g. Mazzei, 2008) have been limited in scope. This is the first test of the homogenized Eugene Island core material. These results will be compared to in situ measurements to determine the controls on consolidation over large stress ranges.

Evaluation of White Bentonite Modified by Acid Attack

NASA Astrophysics Data System (ADS)

Andrade, C. G. Bastos; Fermino, D. M.; Fernandes, M. G.; Valenzuela-Diaz, F. R.

For industrial use, the smectite clays must be cleared of impurities, usually obtained by acid modification, using a high concentration solution of inorganic acid at temperatures under boiling point. In the present paper, a sample of white bentonite from Paraiba, Brazil, was modified by hydrochloric acid under moderate conditions (90°C, reaction times of 1, 6, 12, 18 and 24hours in close reactor, concentration of the aqueous solution of hydrochloric acid 1.5 M, acid solution/clay ratio of 1g/10mL). The purpose of these attacks is to reduce the concentration of impurities with minimal change in the clay minerals structure. The modified samples were characterized by X-ray diffraction (XRD), X-ray fluorescence (XRF), Cation Exchange Capacity (CEC), Stereomicroscopy, Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Detector (EDS). Thus, this modified bentonite tends to be a good economic and environmental alternative in manufacturing of products with high added value such as cosmetics and polymer/clay nanocomposites.

Investigations of some building materials for γ-rays shielding effectiveness

NASA Astrophysics Data System (ADS)

Mann, Kulwinder Singh; Kaur, Baljit; Sidhu, Gurdeep Singh; Kumar, Ajay

2013-06-01

For construction of residential and non-residential buildings bricks are used as building blocks. Bricks are made from mixtures of sand, clay, cement, fly ash, gypsum, red mud and lime. Shielding effectiveness of five soil samples and two fly ash samples have been investigated using some energy absorption parameters (Mass attenuation coefficients, mass energy absorption coefficients, KERMA (kinetic energy released per unit mass), HVL, equivalent atomic number and electron densities) firstly at 14 different energies from 81-1332 keV then extended to wide energy range 0.015-15 MeV. The soil sample with maximum shielding effectiveness has been used for making eight fly ash bricks [(Lime)0.15 (Gypsum)0.05 (Fly Ash)x (Soil)0.8-x, where values of x are from 0.4-0.7]. High Purity Germanium (HPGe) detector has been used for gamma-ray spectroscopy. The elemental compositions of samples were analysed using an energy dispersive X-ray fluorescence (EDXRF) spectrometer. The agreements of theoretical and experimental values of mass attenuation coefficient have been found to be quite satisfactory. It has been verified that common brick possess the maximum shielding effectiveness for wide energy range 0.015-15 MeV. The results have been shown graphically with some useful conclusions for making radiation safe buildings.

40 KG Sample of Fish-Clay from Stevns Klint, Denmark

NASA Astrophysics Data System (ADS)

Gwozdz, R.; Hansen, H. J.; Rasmussen, K. L.

1992-07-01

In March 1986 a 50-m-long exposure of the cliff at Stevns Klint fell down and exposed about 40 square meters of Fish Clay. Due to this extraordinary event we were able to pick by hand about 50 kg black KT boundary layer material. After drying, the material was homogenized using a wooden pestle and an agate mortar. The powdered material was sieved through 200 mesh nylon gauze. The fraction larger than 200 mesh was collected and powdered again in an agate mortar. After four repetitions the amount of material with grain size less than 200 mesh was about 40 kg. The fraction larger than 200 mesh was reduced to about 7 kg. The 40-kg powder was mixed in a rotating polyethylene drum for three weeks. The material was analyzed by instrumental neutron activation analysis, atomic absorption and X-ray fluorescence analysis for about 40 elements. INAA was made on 20 aliquots with weight about 300 mg, 20 aliquots with weight about 80 mg, and 30 with weights between 10 and 20 mg. The preliminary results show that our KT boundary sample (1) is very homogeneous, (2) is very close in composition to other K-T boundary clays analyzed by us or described in the literature, and (3) has an Ir concentration of 32 +- 2 ng/g. We hope that our Fish Clay sample (termed by us "Mesozoic Midnight") after analysis in other laboratories and by other analytical methods may qualify as reference material in analytical work on boundary clay material.

VIS/NIR Spectroscopy to determine the spatial variation of the weathering degree in Paleogene clay soil - London Clay Formation

NASA Astrophysics Data System (ADS)

Nasser, Mohammed; Gibson, Andy, ,, Dr; Koor, Nick, ,, Dr; Gale, Professor Andy; Huggett, Jenny, ,, Dr; Branch, Steve

2017-04-01

The London Clay Formation (LCF) which underlies much of South-East England is hugely important as a construction medium. However, its geotechnical performance (shear strength, compressive strength, shrink-swell behaviour, etc. ) is greatly affected by its degree of weathering. Despite this importance, little attention has been focussed on a robust method to define and measure its degree of weathering. This is perhaps a result of a well-known colour change from bluish-grey to brown that accompanies 'weathering' and considered to be the result of oxidisation (Chandler and Apted 1988). Through wide experience, this definition is normally effective, but it is perhaps subjective and reliant on the experience of the investigator and the ability to observe samples or exposures. More objective investigation, typically using SEM is not normally economically feasible or expedient for construction works. We propose a simple, robust method to characterise the degree of weathering in the LCF using reflective or Visible-Near-InfraRed-Spectroscopy (VNIRS). 24 samples were extracted from 2 boreholes drilled in the Hampstead area of London to depths of 12 m within the uppermost Claygate Member of the LCF. VNIRS spectra (350-2500 nm) were measured from all samples and compared with XRD, XRF, SEM and PSD results on the same samples. Results show increased magnitude of absorption features related to clay mineralogy around 1400, 1900 and 2200 nm to a depth of 5 m beneath ground level. Beneath this depth, the absorption features show little variation. SEM analyses show corresponding changes in the degradation of pyrite crystals and individual clay (illite/smectite). These preliminary results show that there is a good potential for VNIRS spectroscopy to determine the variation of weathering in the LCF.

Rock Physics and Petrographic Parameters Relationship Within Siliciclastic Rocks: Quartz Sandstone Outcrop Study Case

NASA Astrophysics Data System (ADS)

Syafriyono, S.; Caesario, D.; Swastika, A.; Adlan, Q.; Syafri, I.; Abdurrokhim, A.; Mardiana, U.; Mohamad, F.; Alfadli, M. K.; Sari, V. M.

2018-03-01

Rock physical parameters value (Vp and Vs) is one of fundamental aspects in reservoir characterization as a tool to detect rock heterogenity. Its response is depend on several reservoir conditions such as lithology, pressure and reservoir fluids. The value of Vp and Vs is controlled by grain contact and contact stiffness, a function of clay mineral content and porosity also affected by mineral composition. The study about Vp and Vs response within sandstone and its relationship with petrographic parameters has become important to define anisotrophy of reservoir characteristics distribution and could give a better understanding about local diagenesis that influence clastic reservoir properties. Petrographic analysis and Vp-Vs calculation was carried out to 12 core sample which is obtained by hand-drilling of the outcrop in Sukabumi area, West Java as a part of Bayah Formation. Data processing and interpretation of sedimentary vertical succession showing that this outcrop comprises of 3 major sandstone layers indicating fluvial depositional environment. As stated before, there are 4 petrographic parameters (sorting, roundness, clay mineral content, and grain contact) which are responsible to the differences of shear wave and compressional wave value in this outcrop. Lithology with poor-sorted and well- roundness has Vp value lower than well-sorted and poor-roundness (sub-angular) grain. For the sample with high clay content, Vp value is ranging from 1681 to 2000 m/s and could be getting high until 2190 to 2714 m/s in low clay content sample even though the presence of clay minerals cannot be defined neither as matrix nor cement. The whole sample have suture grain contact indicating telogenesis regime whereas facies has no relationship with Vp and Vs value because of the different type of facies show similar petrographic parameters after diagenesis.

Sources & Transport Mechanisms of Sediments in the Oceans.

DTIC Science & Technology

1982-03-31

estuaries 03si e m arh ket. The. peristaltic action, dugt is. pro ~gre- and oceans. The concentration of doe suspended sample was testig were obtained by...waters: Clays Clay Minerals, Seventh National Con - weer: Progress in water technology. v. 7, p. 207-216. ference, p. 1-79. Guess, R. J. (1977), Clay...the (10) ZAbawa, C. Science (Wahigton, D.C) 1978,202,49.4 dlyt Of the GMo wer 45 jum wit a meal portion (11) G b.I J.; Kenwar, L Environ. Sci. Technol

Ostwald ripening of clays and metamorphic minerals

USGS Publications Warehouse

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

1990-01-01

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

Reconstruction of a digital core containing clay minerals based on a clustering algorithm.

PubMed

He, Yanlong; Pu, Chunsheng; Jing, Cheng; Gu, Xiaoyu; Chen, Qingdong; Liu, Hongzhi; Khan, Nasir; Dong, Qiaoling

2017-10-01

It is difficult to obtain a core sample and information for digital core reconstruction of mature sandstone reservoirs around the world, especially for an unconsolidated sandstone reservoir. Meanwhile, reconstruction and division of clay minerals play a vital role in the reconstruction of the digital cores, although the two-dimensional data-based reconstruction methods are specifically applicable as the microstructure reservoir simulation methods for the sandstone reservoir. However, reconstruction of clay minerals is still challenging from a research viewpoint for the better reconstruction of various clay minerals in the digital cores. In the present work, the content of clay minerals was considered on the basis of two-dimensional information about the reservoir. After application of the hybrid method, and compared with the model reconstructed by the process-based method, the digital core containing clay clusters without the labels of the clusters' number, size, and texture were the output. The statistics and geometry of the reconstruction model were similar to the reference model. In addition, the Hoshen-Kopelman algorithm was used to label various connected unclassified clay clusters in the initial model and then the number and size of clay clusters were recorded. At the same time, the K-means clustering algorithm was applied to divide the labeled, large connecting clusters into smaller clusters on the basis of difference in the clusters' characteristics. According to the clay minerals' characteristics, such as types, textures, and distributions, the digital core containing clay minerals was reconstructed by means of the clustering algorithm and the clay clusters' structure judgment. The distributions and textures of the clay minerals of the digital core were reasonable. The clustering algorithm improved the digital core reconstruction and provided an alternative method for the simulation of different clay minerals in the digital cores.

Microstructural controls on the macroscopic behavior of geo-architected rock samples

NASA Astrophysics Data System (ADS)

Mitchell, C. A.; Pyrak-Nolte, L. J.

2017-12-01

Reservoir caprocks, are known to span a range of mechanical behavior from elastic granitic units to visco-elastic shale units. Whether a rock will behave elastically, visco-elastically or plastically depends on both the compositional and textural or microsctructural components of the rock, and how these components are spatially distributed. In this study, geo-architected caprock fabrication was performed to develop synthetic rock to study the role of rock rheology on fracture deformations, fluid flow and geochemical alterations. Samples were geo-architected with Portland Type II cement, Ottawa sand, and different clays (kaolinite, illite, and Montmorillonite). The relative percentages of these mineral components are manipulated to generate different rock types. With set protocols, the mineralogical content, texture, and certain structural aspects of the rock were controlled. These protocols ensure that identical samples with the same morphological and mechanical characteristics are constructed, thus overcoming issues that may arise in the presence of heterogeneity and high anisotropy from natural rock samples. Several types of homogeneous geo-architected rock samples were created, and in some cases the methods were varied to manipulate the physical parameters of the rocks. Characterization of rocks that the samples exhibit good repeatability. Rocks with the same mineralogical content generally yielded similar compressional and shear wave velocities, UCS and densities. Geo-architected rocks with 10% clay in the matrix had lower moisture content and effective porosities than rocks with no clay. The process by which clay is added to the matrix can strongly affect the resulting compressive strength and physical properties of the geo-architected sample. Acknowledgment: This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Geosciences Research Program under Award Number (DE-FG02-09ER16022).

Clay mineralogy of weathering profiles from the Carolina Piedmont.

USGS Publications Warehouse

Loferski, P.J.

1981-01-01

Saprolite profiles (12) that formed over various crystalline rocks from the Charlotte 1o X 2o quadrangle showed overall similarity in their clay mineralogy to depths of 6 to 45 m indicating control by weathering processes rather than by rock type. Most saprolite contained 10-25% clay, and ranged 3 to 70%. Kaolinite and halloysite composed = or >75% of the clay fraction of most samples. The ratio kaolinite:halloysite ranged widely, from 95% kaolinite to 90% halloysite, independent of depth. Clay-size mica was present in all profiles, and ranged 5-75% over a sericite schist. Mixed-layer mica-smectite and mica-vermiculite were subordinate; discrete smectite and vermiculite were rare. The abundance of halloysite indicates a continuously humid environment since the time of profile formation, because of the rapidity with which halloysite dehydrates irreversibly. -R.S.M.

Removal of Cr(VI) from Aqueous Environments Using Micelle-Clay Adsorption

PubMed Central

Qurie, Mohannad; Khamis, Mustafa; Manassra, Adnan; Ayyad, Ibrahim; Nir, Shlomo; Scrano, Laura; Bufo, Sabino A.; Karaman, Rafik

2013-01-01

Removal of Cr(VI) from aqueous solutions under different conditions was investigated using either clay (montmorillonite) or micelle-clay complex, the last obtained by adsorbing critical micelle concentration of octadecyltrimethylammonium ions onto montmorillonite. Batch experiments showed the effects of contact time, adsorbent dosage, and pH on the removal efficiency of Cr(VI) from aqueous solutions. Langmuir adsorption isotherm fitted the experimental data giving significant results. Filtration experiments using columns filled with micelle-clay complex mixed with sand were performed to assess Cr(VI) removal efficiency under continuous flow at different pH values. The micelle-clay complex used in this study was capable of removing Cr(VI) from aqueous solutions without any prior acidification of the sample. Results demonstrated that the removal effectiveness reached nearly 100% when using optimal conditions for both batch and continuous flow techniques. PMID:24222757

Quantification of Biogenic Magnetite by Synchrotron X-ray Microscopy During the PETM

NASA Astrophysics Data System (ADS)

Wang, H.; Wang, J.; Kent, D. V.; Chen-Wiegart, Y. C. K.

2014-12-01

Exceptionally large biogenic magnetite crystals, including spearhead-like and spindle-like ones up to 4 microns, have been reported in clay-rich sediments recording the ~56 Ma Paleocene-Eocene thermal maximum (PETM) and carbon isotope excursion (CIE) in a borehole at Ancora, NJ and along with magnetotactic bacteria (MTB) chains, were suggested [Schumann et al. 2008 PNAS; Kopp et al. 2009 Paleoceanography] to account for the distinctive single domain (SD) rock magnetic properties of these sediments [Lanci et al. 2002 JGR]. However, because uncalibrated magnetic extraction techniques were used to provide material for TEM imaging of the biogenic magnetite, it is difficult to quantitatively analyze their concentration in the bulk clay. In this study, we use a synchrotron transmission X-ray microscope to image bulk CIE clay. We first take mosaic images of sub-millimeter-sized bulk clay samples, in which we can identify many of the various types of giant biogenic magnetite crystals, as well as several other types of iron minerals, such as pyrite framboids, siderite, and detrital magnetite. However, limited by the instrument resolution (~50 nm), we are not able to identify MTB chains let alone isolated magnetic nanoparticles that may be abundant the clay. To quantitatively estimate the concentration of the giant biogenic magnetite, we re-deposited the bulk clay sample in an alcohol solution on a silicon nitride membrane for 2D X-ray scans. After scanning a total area of 0.55 mm2 with average clay thickness of 4 μm, we identified ~40 spearheads, ~5 spindles and a few elongated rods and estimated their total magnetization as SD particles to be less than about 10% of the mass normalized clay for the scanned area. This result suggests that the giant biogenic magnetite is not a major source of the SD signal for the clay and is in good agreement with rock magnetic analyses using high-resolution first-order reversal curves and thermal fluctuation tomography on bulk CIE clay showing that most of the magnetite occurs as isolated, near-equant SD particles [Wang et al. 2013 PNAS]. This would also exclude a significant contribution from MTB chains and points to a non-biogenic origin, such as a comet impact plume condensate, for the magnetic nanoparticles [Kent et al. 2003 EPSL] in the very rapidly deposited CIE clays [Wright & Schaller 2014 PNAS].

NMR imaging and cryoporometry of swelling clays

NASA Astrophysics Data System (ADS)

Dvinskikh, Sergey V.; Szutkowski, Kosma; Petrov, Oleg V.; Furó, István.

2010-05-01

Compacted bentonite clay is currently attracting attention as a promising "self-sealing" buffer material to build in-ground barriers for the encapsulation of radioactive waste. It is expected to fill up the space between waste canister and surrounding ground by swelling and thus delay flow and migration from the host rock to the canister. In environmental sciences, evaluation and understanding of the swelling properties of pre-compacted clay are of uttermost importance for designing such buffers. Major goal of present study was to provide, in a non-invasive manner, a quantitative measure of bentonite distribution in extended samples during different physical processes in an aqueous environment such as swelling, dissolution, and sedimentation on the time scale from minutes to years. The propagation of the swelling front during clay expansion depending on the geometry of the confining space was also studied. Magnetic resonance imaging and nuclear magnetic resonance spectroscopy were adapted and used as main experimental techniques. With this approach, spatially resolved movement of the clay/water interface as well as clay particle distributions in gel phase can be monitored [1]. Bulk samples with swelling in a vertical tube and in a horizontal channel were investigated and clay content distribution profiles in the concentration range over five orders of magnitude and with sub-millimetre spatial resolution were obtained. Expansion rates for bulk swelling and swelling in narrow slits were compared. For sodium-exchanged montmorillonite in contact with de-ionised water, we observed a remarkable acceleration of expansion as compared to that obtained in the bulk. To characterize the porosity of the clay a cryoporometric study [2] has been performed. Our results have important implications to waste repository designs and for the assessment of its long-term performance. Further research exploring clay-water interaction over a wide variety of clay composition and water ionic strength as well as investigating the effect of the confining geometry and material surface properties seem to be worth to pursue. Acknowledgements: This work has been supported by the Swedish Nuclear Fuel and Waste Management Co (SKB) and the Swedish Research Council VR. References: [1] Dvinskikh S. V., Szutkowski K., Furó I. MRI profiles over a very wide concentration ranges: application to swelling of a bentonite clay. J. Magn. Reson. 198, 146 (2009). [2] Petrov O. V., Furó I. NMR cryoporometry: Principles, applications and potential. Prog. Nucl. Magn. Reson. Spec. 54, 97 (2009).

Copolymerization of Glycolide and ɛ-Caprolactone Using 12-Aminolauric Acid Modified Montmorillonite

NASA Astrophysics Data System (ADS)

Gallos, HAV; Reyes, LQ

2017-09-01

Poly(glycolide-co-ɛ-caprolactone) (PGLYCL) nanocomposites were prepared by copolymerization glycolide (GLY) and ɛ-caprolactone (ɛ-CL) in the presence of varying loadings 12-aminolauric acid (12-ALA)-modified montmorillonite. Copolymerization was successfully achieved based on the increase in polymer molecular weight after the reaction determined by gel permeation chromatography (GPC). The amount of the poly(glycolide) block and poly(ɛ-caprolactone) block units in the copolymer, identified by proton nuclear magnetic resonance (1H-NMR) spectroscopy, suggested that the increase in organo-clay loading cause a reduction GLYL: ɛ-CLL ratio. The arrangement of the monomers in the polymer products was elucidated to have an ABA triblock structure, where PCL block is the central block and the PGLY is found at both end of the copolymer. The presence of intercalated and exfoliated silicates in the nanocomposites were observed by x-ray diffraction (XRD) analysis. The biocompatibility of the nanocomposites with NCTC 292 mouse normal fibroblast was high relative to untreated cell cultures using tetrazolium bromide (MTT)-dye reduction assay.

Reflectance Spectroscopy of Palagonite and Iron-Rich Montmorillonite Clay Mixtures: Implications for the Surface Composition of Mars

NASA Technical Reports Server (NTRS)

Orenberg, James; Handy, Jonathan

1992-01-01

Mixtures of a Hawaiian palagonite and an iron-rich, montmorillonite clay (15.8 +/- 0.4 wt% Fe as Fe2O3) were evaluated as Mars surface spectral analogs from their diffuse reflectance spectra. The presence of the 2.2 microns absorption band in the reflectance spectrum of clays and its absence in the Mars spectrum have been interpreted as indicating that highly crystalline aluminous hydroxylated clays cannot be a major mineral component of the soil on Mars. The palagonite sample used in this study does not show this absorption feature in its spectrum. In mixtures of palagonite and iron-rich montmorillonite, the 2.2 microns Al-OH clay lattice band is not seen below 15 wt% montmorillonite. This suggests the possibility that iron-rich montmorillonite clay may be present in the soil of Mars at up to 15 wt% in combination with palagonite, and remain undetected in remotely sensed spectra of Mars.

An Exploratory Study: Assessment of Modeled Dioxin ...

EPA Pesticide Factsheets

EPA announced the availability of the final report, An Exploratory Study: Assessment of Modeled Dioxin Exposure in Ceramic Art Studios. This report investigates the potential dioxin exposure to artists/hobbyists who use ball clay to make pottery and related products. Dermal, inhalation, and ingestion exposures to clay were measured at the ceramics art department of Ohio State University in Columbus, OH. The exposure estimates were based on measured levels of clay in the studio air, deposited on surrogate food samples and on the skin of the artists. The purpose of this report is to describe an exploratory investigation of potential dioxin exposures to artists/hobbyists who use ball clay to make pottery and related products.

Fine Structure of Starch-Clay Composites as Biopolymers

USDA-ARS?s Scientific Manuscript database

Midsol 50 wheat starch and 5% Cloisite clay with or without the addition of glycerin were used to prepare biopolymers in a twin-screw extruder. Early trials of sectioning the unembedded biopolymer resulted in the immediate absorption of water and subsequent dissolution of the sample due to the the ...

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

USDA-ARS?s Scientific Manuscript database

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

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

USDA-ARS?s Scientific Manuscript database

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

The Preparation and Simple Analysis of a Clay Nanoparticle Composite Hydrogel

ERIC Educational Resources Information Center

Warren, David S.; Sutherland, Sam P. H.; Kao, Jacqueline Y.; Weal, Geoffrey R.; Mackay, Sean M.

2017-01-01

Samples of a composite hydrogel incorporating clay (Laponite XLG and S-482) nanoparticles were prepared using N-isopropylacrylamide. The hydrogels were formed via a radical-initiated addition polymerization using potassium persulfate and N,N,N',N'-tetramethylethylenediamine. Students then measured the force required to stretch the gels and…

Valorisation of Sugarcane Bagasse Ash in the Manufacture of Lime-Stabilized Blocks

NASA Astrophysics Data System (ADS)

James, Jijo; Pandian, Pitchai Kasinatha

2016-06-01

The study investigated the potential of lime in the manufacture of stabilized soil blocks and the valorisation of a solid waste, Bagasse Ash (BA), in its manufacture. A locally available soil was collected from a field and characterized in the soil laboratory as a clay of intermediate plasticity. This soil was stabilized using lime, the quantity of which was determined from the Eades and Grim pH test. The soil was stabilized using this lime content, amended with various BA contents during mixing, and moulded into blocks of 19 cm x 9 cm x 9 cm. The blocks were then moist cured for a period of 28 days, following which they were subjected to compressive strength, water absorption and efflorescence tests. The results of the tests revealed that the addition of BA resulted in enhanced compressive strength of the blocks, increased the water absorption marginally, and resulted in no efflorescence in any of the combinations, although the limited combinations in the study could not produce enough strength to meet the specifications of the Bureau of Indian Standards. The study revealed that BA can be effectively valorised in the manufacture of stabilized soil blocks.

Geohydrology of the High Energy Laser System Test Facility site, White Sands Missile Range, Tularosa Basin, south-central New Mexico

USGS Publications Warehouse

Basabilvazo, G.T.; Nickerson, E.L.; Myers, R.G.

1994-01-01

The Yesum-HoHoman and Gypsum land (hummocky) soils at the High Energy Laser System Test Facility (HELSTF) represent wind deposits from recently desiccated lacustrine deposits and deposits from the ancestral Lake Otero. The upper 15-20 feet of the subsurface consists of varved gypsiferous clay and silt. Below these surfidai deposits the lithology consists of interbedded clay units, silty-clay units, and fine- to medium-grained quartz arenite units in continuous and discontinuous horizons. Clay horizons can cause perched water above the water table. Analyses of selected clay samples indicate that clay units are composed chiefly of kaolinire and mixed-layer illite/ smectite. The main aquifer is representative of a leaky-confined aquifer. Estimated aquifer properties are: transmissivity (T) = 780 feet squared per day, storage coefficient (S) = 3.1 x 10-3, and hydraulic conductivity (K) = 6.0 feet per day. Ground water flows south and southwest; the estimated hydraulic gradient is 5.3 feet per mile. Analyses of water samples indicate that ground water at the HELSTF site is brackish to slightly saline at the top of the main aquifer. Dissolved-solids concentration near the top of the main aquifer ranges from 5,940 to 11,800 milligrams per liter. Predominant ions are sodium and sulfate. At 815 feet below land surface, the largest dissolved-solids concentration measured is 111,000 milligrams per liter, which indicates increasing salinity with depth. Predominant ions are sodium and chloride.

Adsorption-regeneration by heterogeneous Fenton process using modified carbon and clay materials for removal of indigo blue.

PubMed

Almazán-Sánchez, Perla Tatiana; Solache-Ríos, Marcos J; Linares-Hernández, Ivonne; Martínez-Miranda, Verónica

2016-01-01

Indigo blue dye is mainly used in dyeing of denim clothes and its presence in water bodies could have adverse effects on the aquatic system; for this reason, the objective of this study was to promote the removal of indigo blue dye from aqueous solutions by iron and copper electrochemically modified clay and activated carbon and the saturated materials were regenerated by a Fenton-like process. Montmorillonite clay was modified at pH 2 and 7; activated carbon at pH 2 and pH of the system. The elemental X-ray dispersive spectroscopy analysis showed that the optimum pH for modification of montmorillonite with iron and copper was 7 and for activated carbon was 2. The dye used in this work was characterized by infrared. Unmodified and modified clay samples showed the highest removal efficiencies of the dye (90-100%) in the pH interval from 2 to 10 whereas the removal efficiencies decrease as pH increases for samples modified at pH 2. Unmodified clay and copper-modified activated carbon at pH 2 were the most efficient activated materials for the removal of the dye. The adsorption kinetics data of all materials were best adjusted to the pseudo-second-order model, indicating a chemisorption mechanism and the adsorption isotherms data showed that the materials have a heterogeneous surface. The iron-modified clay could be regenerated by a photo-Fenton-like process through four adsorption-regeneration cycles, with 90% removal efficiency.

An experimental study of the effects of adsorbing and non-adsorbing gases on friction and permeability evolution in clay-rich fault gouge

NASA Astrophysics Data System (ADS)

Lisabeth, H. P.; Zoback, M. D.

2017-12-01

Understanding the flow of fluids through fractures in clay-rich rocks is fundamental to a number of geoengineering enterprises, including development of unconventional hydrocarbon resources, nuclear waste storage and geological carbon sequestration. High clay content tends to make rocks plastic, low-porosity and anisotropic. In addition, some gasses adsorb to clay mineral surfaces, resulting in swelling and concomitant changes in physical properties. These complexities can lead to coupled behaviors that render prediction of fluid behavior in the subsurface difficult. We present the results of a suite of triaxial experiments on binary mixtures of quartz and illite grains to separate and quantify the effects of hydrostatic pressure, differential stress, clay content and gas chemistry on the evolution of mechanical and hydraulic characteristics of the gouge material during deformation. Tests are run on saw-cut samples prepared with gouge at 20 MPa confining pressure, 10 MPa pore pressure and at room temperature. Argon or carbon dioxide is used as pore fluid. Sample permeability, stress and strain are monitored continuously during hydrostatic and axial deformation. We find that pressure and shearing both lead to reductions in permeability. Adsorbing gas leads to swelling and promotes permeability reduction, but appears to have no effect on frictional properties. These results indicate that the seal integrity of clay-rich caprocks may not be compromised by shear deformation, and that depletion and shear deformation of unconventional reservoirs is expected to result in production declines.

Iridium, sulfur isotopes and rare earth elements in the Cretaceous-Tertiary boundary clay at Stevns Klint, Denmark

NASA Astrophysics Data System (ADS)

Schmitz, Birger; Andersson, Per; Dahl, Jeremy

1988-01-01

Microbial activity and redox-controlled precipitation have been of major importance in the process of metal accumulation in the strongly Ir-enriched Cretaceous-Tertiary (K-T) boundary clay, the Fish Clay, at Stevns Klint in Denmark. Two important findings support this view: 1) Kerogen, recovered by leaching the Fish Clay in HCl and HF, shows an Ir concentration of 1100 ppb; this represents about 50% of the Ir present in the bulk sample Fish Clay. Strong organometallic complexes is the most probable carrier phase for this fraction of Ir. Kerogen separated from the K-T boundary clay at Caravaca, Spain, similarly exhibits enhanced Ir concentrations. 2) Sulfur isotope analyses of metal-rich pyrite spherules, which occur in extreme abundance (about 10% by weight) in the basal Fish Clay, give a δ 34S value of -32%.. This very low value shows that sulfide formation by anaerobic bacteria was intensive in the Fish Clay during early diagenesis. Since the pyrite spherules are major carriers of elements such as Ni, Co, As, Sb and Zn, microbial activity may have played an important role for concentrating these elements. In the Fish Clay large amounts of rare earth elements have precipitated from sea water on fish scales. Analyses reveal that, compared with sea water, the Fish Clay is only about four times less enriched in sea-water derived lanthanides than in Ir. This shows that a sea-water origin is plausible for elements that are strongly enriched in the clay, but whose origin cannot be accounted for by a lithogenic precursor.

Fabrication and Characterization of Flexible Organic Light Emitting Diodes Based on Transparent Flexible Clay Substrates

NASA Astrophysics Data System (ADS)

Venkatachalam, Shanmugam; Hayashi, Hiromichi; Ebina, Takeo; Nakamura, Takashi; Nanjo, Hiroshi

2013-03-01

In the present work, transparent flexible polymer-doped clay (P-clay) substrates were prepared for flexible organic light emitting diode (OLED) applications. Nanocrystalline indium tin oxide (ITO) thin films were prepared on P-clay substrates by ion-beam sputter deposition method. The structural, optical, and electrical properties of as-prepared ITO/P-clay showed that the as-prepared ITO thin film was amorphous, and the average optical transparency and sheet resistance were around 84% and 56 Ω/square, respectively. The as-prepared ITO/P-clay samples were annealed at 200 and 270 °C for 1 h to improve the optical transparency and electrical conductivity. The average optical transparency was found to be maximum at an annealing temperature of 200 °C. Finally, N,N-bis[(1-naphthyl)-N,N '-diphenyl]-1,1'-biphenyl)-4,4'-diamine (NPB), tris(8-hydroxyquinoline) aluminum (Alq3) thin films, and aluminum (Al) electrode were prepared on ITO/P-clay substrates by thermal evaporation method. The current density-voltage (J-V) characteristic of Al/NPB/ITO/P-clay showed linear Ohmic behaviour. In contrast, J-V characteristic of Al/Alq3/NPB/ITO/P-clay showed non-linear Schottky behaviour. Finally, a very flexible OLED was successfully fabricated on newly fabricated transparent flexible P-clay substrates. The electroluminescence study showed that the emission intensity of light from the flexible OLED device gradually increased with increasing applied voltage.

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

NASA Astrophysics Data System (ADS)

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

2015-12-01

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

Do scaly clays control seismicity on faulted shale rocks?

NASA Astrophysics Data System (ADS)

Orellana, Luis Felipe; Scuderi, Marco M.; Collettini, Cristiano; Violay, Marie

2018-04-01

One of the major challenges regarding the disposal of radioactive waste in geological formations is to ensure isolation of radioactive contamination from the environment and the population. Shales are suitable candidates as geological barriers. However, the presence of tectonic faults within clay formations put the long-term safety of geological repositories into question. In this study, we carry out frictional experiments on intact samples of Opalinus Clay, i.e. the host rock for nuclear waste storage in Switzerland. We report experimental evidence suggesting that scaly clays form at low normal stress (≤20 MPa), at sub-seismic velocities (≤300 μm/s) and is related to pre-existing bedding planes with an ongoing process where frictional sliding is the controlling deformation mechanism. We have found that scaly clays show a velocity-weakening and -strengthening behaviour, low frictional strength, and poor re-strengthening over time, conditions required to allow the potential nucleation and propagation of earthquakes within the scaly clays portion of the formation. The strong similarities between the microstructures of natural and experimental scaly clays suggest important implications for the slip behaviour of shallow faults in shales. If natural and anthropogenic perturbations modify the stress conditions of the fault zone, earthquakes might have the potential to nucleate within zones of scaly clays controlling the seismicity of the clay-rich tectonic system, thus, potentially compromising the long-term safeness of geological repositories situated in shales.

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

NASA Astrophysics Data System (ADS)

Goodfellow, Bradley W.

2012-12-01

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.

MX Siting Investigation. Geotechnical Summary. Prime Characterization Sites, Sonoran, Candidate Siting Province.

DTIC Science & Technology

1979-02-15

fracture along which there has been displacement. FAULT BLOCK MOUNTAINS - Mountains that are formed by normal faulting in which the surface crust is...sized particles. Psa. Pm, S2 Limestone and Dolomite . Composed predominantly of carbonate material. Ph, Cau, S3 Shale. Composed predominantly of clay...METAMORPHIC (UNDIFFERENTIATED). Rocks formed through alteration of igneous orgn sedimentary rock material by pressure , heat, or chemical changes below the

Rapid Soil Stabilization of Soft Clay Soils for Contingency Airfields

DTIC Science & Technology

2006-12-01

quicklime or calcium carbide, could possibly crosslink the polymers of sodium or potassium polyacrylic acid together to form a harder material. Very...LiquiBlock 40K and 41K are both potassium salts of crosslinked polyacrylic acids/polyacrylamide copolymers in granular form that also gel in the presence...communication, 2006), soil could possibly be stabilized with calcium and super absorbent polymers, such as sodium or potassium polyacrylic acids. This

Towards Characterization, Modeling, and Uncertainty Quantification in Multi-scale Mechanics of Oragnic-rich Shales

NASA Astrophysics Data System (ADS)

Abedi, S.; Mashhadian, M.; Noshadravan, A.

2015-12-01

Increasing the efficiency and sustainability in operation of hydrocarbon recovery from organic-rich shales requires a fundamental understanding of chemomechanical properties of organic-rich shales. This understanding is manifested in form of physics-bases predictive models capable of capturing highly heterogeneous and multi-scale structure of organic-rich shale materials. In this work we present a framework of experimental characterization, micromechanical modeling, and uncertainty quantification that spans from nanoscale to macroscale. Application of experiments such as coupled grid nano-indentation and energy dispersive x-ray spectroscopy and micromechanical modeling attributing the role of organic maturity to the texture of the material, allow us to identify unique clay mechanical properties among different samples that are independent of maturity of shale formations and total organic content. The results can then be used to inform the physically-based multiscale model for organic rich shales consisting of three levels that spans from the scale of elementary building blocks (e.g. clay minerals in clay-dominated formations) of organic rich shales to the scale of the macroscopic inorganic/organic hard/soft inclusion composite. Although this approach is powerful in capturing the effective properties of organic-rich shale in an average sense, it does not account for the uncertainty in compositional and mechanical model parameters. Thus, we take this model one step forward by systematically incorporating the main sources of uncertainty in modeling multiscale behavior of organic-rich shales. In particular we account for the uncertainty in main model parameters at different scales such as porosity, elastic properties and mineralogy mass percent. To that end, we use Maximum Entropy Principle and random matrix theory to construct probabilistic descriptions of model inputs based on available information. The Monte Carlo simulation is then carried out to propagate the uncertainty and consequently construct probabilistic descriptions of properties at multiple length-scales. The combination of experimental characterization and stochastic multi-scale modeling presented in this work improves the robustness in the prediction of essential subsurface parameters in engineering scale.

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

USGS Publications Warehouse

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

1989-01-01

Silver metal-membrane filters are commonly used as substrates in the preparation of oriented clay-mineral specimens for X-ray powder diffraction (XRD). They are relatively unaffected by organic solvent treatments and specimens can be prepared rapidly. The filter mounts are adaptable to automatic sample changers, have few discrete reflections at higher 20 angles, and, because of the high atomic number of silver, produce a relatively low overall background compared with other membrane filters, such as cellulose (Poppe and Hathaway, 1979). 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.

Smectite clays of Serbia and their application in adsorption of organic dyes

NASA Astrophysics Data System (ADS)

Milošević, Maja; Logar, Mihovil

2014-05-01

Colorants and dyes are currently available in over a 100.000 different species and several biggest industries are using them daily in their manufacture processes (textile, cosmetics, food industry, etc.). Since colorants are easily dissoluble in water they pass through filter membranes without further decomposing and in that manner they end up in the environment. The main goal of this work is to apply certain methods in determining the suitability of individual clay in adsorbing and removing colorants from polluted waters. For this study we have chosen four different raw clays from three regions in Serbia: Svrljig (B), Bogovina (Bo) and Slatina-Ub (C and V) and as colorant - methylene blue dye (MB (MERCK, for analytical purposes)). Experiments where carried out to determine the sample structure (XRD and IR), grain size (granulometry), cationic exchange capacity (CEC via spectrophotometry using MB) and adsorption capabilities (spectrophotometry and fluorimetry using MB). XRD and IR data are showing that the samples are smectite clays where samples B i Bo are mainly montmorillonite while C and V are montmorillonite-illite clays. Granulometric distribution results indicate that samples B i Bo have smaller grain size, less that 1μ (over 60%) whereas the samples C and V are more coarse grained (40% over 20μ). This grain distribution is affecting their specific surface area in the manner that those coarse grained samples have smaller specific surface area. Cationic exchange capacity determined with methylene blue indicate that montmorillonite samples have larger CEC (B = 37 meq/100g, Bo = 50 meq/100g) and montmorillonite-illite samples smaller CEC (V = 5 meq/100g, V = 3 meq/100g). Fluorimetry measurement results gave us a clear distinction between those with higher and smaller adsorption capability. Montmorillonite samples (B and Bo) with higher CEC values and smaller grain size are adsorbing large amounts of methylene blue witch is visible by absence of fluorimetric band corresponding to methylene blue. Montmorillonite-illite samples with smaller CEC values and coarser grain size are adsorbing very small amounts of methylene blue from the suspension which is visible by appearance of the methylene blue band. Untreated, raw smectite clays of Serbia are efficient adsorbent material for removal of dyes from polluted waters. Samples from two regions especially, Bogovina and Svrljig, are showing favorable adsorption results and they are representing good raw materials for purification of waste-waters containing dyes. References: - Jović-Jovičić, N., Milutinović-Nikolić, A., Gržetić, I., Jovanović, D.; Organobentonite as efficient textile dye sorbent; Chem. Eng. Technol. 2008, 31, No. 4, 567-574 - Žunić, M.J., Milutinović-Nikolić, A.D., Jović-Jovičić, N.P., Banković, P.T., Mojović, Z.D., Manojlović, D.D., Jovanović, D.M.; Modified bentonite as adsorbent and catalyst for purification of wastewaters containing dyes; Hem. ind. 2010, 64 ,No. 3, 193-199

An abiogenic photochemical synthesis on surface of meteorites and other small space bodies

NASA Astrophysics Data System (ADS)

Simakov, M.; Kuzicheva, E.

Abiogenic photochemical synthesis of complex biochemical compounds on the surface of small bodies in our Solar system was examined. The hydrated minerals are found within a chondrite matrix of meteorites together with significant amounts of organic matter. Clays are likely to have formed when water was presented on parent meteoritic bodies. In order to verify the existence of a relationship between abiogenic synthesis of nucleotides and inorganic components of the meteorites we have investigated possible abiogenic reactions at the presence of different clay minerals (montmorillonite, kaolinite) and basaltic sample (Tjatja's volcanic ash) under action of open space energy sources for modeling of different exobiological environments on the surface of small space bodies. The abiogenic synthesis of natural adenine nucleotides from mixture of adenosine plus inorganic phosphate has been observed under an irradiation with VUV radiation at the presence of different mineral samples. The yields of the products (5'AMP, 2'AMP, 3'AMP, 2'3'cAMP and 3'5'cAMP) were depended from irradiation time and kind of used minerals. The discovery that meteoritic organic compounds may be trapped and protected within a clay mineral matrix has implications for our understanding of prebiotic molecular evolution in the early Solar system. Clay minerals may have concentrated organic compounds thereby promoting polymerization reactions also. An adsorption/binding of nucleic acids components by clay crystals could change in the electron distribution and/or the conformation of the molecules. The remnant water molecules in the clay sheets also could influence on the course of the reaction. Besides, an immobilization of phosphate on clay also could play an important role in our reaction. Chondritic material would have been a common component of the inner Solar system shortly after its formation and the biologically useful products of clay mineral-organic matter interactions would have also widespread, and delivered to planetary surfaces through the accretion of carbonaceous asteroids.

Aggregation and stability of anisotropic charged clay colloids in aqueous medium in the presence of salt.

PubMed

Ali, Samim; Bandyopadhyay, Ranjini

2016-01-01

Na-montmorillonite nanoclay is a colloid of layered mineral silicate. When dispersed in water, this mineral swells on absorption of water and exfoliates into platelets with electric double layers on their surfaces. Even at low particle concentration, the aqueous dispersion can exhibit a spontaneous ergodicity breaking phase transition from a free flowing liquid to nonequilibrium, kinetically arrested and disordered states such as gels and glasses. In an earlier publication [Applied Clay Science, 2015, 114, 8592], we showed that the stability of clay gels can be enhanced by adding a salt later to the clay dispersion prepared in deionized water, rather than by adding the clay mineral to a previously mixed salt solution. Here, we directly track the collapsing interface of sedimenting clay gels using an optical method and show that adding salt after dispersing the clay mineral does indeed result in more stable gels even in very dilute dispersions. These weak gels are seen to exhibit a transient collapse after a finite delay time, a phenomenon observed previously in depletion gels. The velocity of the collapse oscillates with the age of the sample. However, the average velocity of collapse increases with sample age up to a peak value before decreasing at higher ages. With increasing salt concentration, the delay time for transient collapse decreases, while the peak value of the collapsing velocity increases. Using ultrasound attenuation spectroscopy, rheometry and cryogenic scanning electron microscopy, we confirm that morphological changes of the gel network assembly, facilitated by thermal fluctuations, lead to the observed collapse phenomenon. Since clay minerals are used extensively in polymer nanocomposites, as rheological modifiers, stabilizers and gas absorbents, we believe that the results reported in this work are extremely useful for several practical applications and also for understanding geophysical phenomena such as the formation and stability of quicksand and river deltas.

Analysis of the seismic signals generated by controlled single-block rockfalls on soft clay shales sediments: the Rioux Bourdoux slope experiment (French Alps).

NASA Astrophysics Data System (ADS)

Hibert, Clément; Provost, Floriane; Malet, Jean-Philippe; Bourrier, Franck; Berger, Frédéric; Bornemann, Pierrick; Borgniet, Laurent; Tardif, Pascal; Mermin, Eric

2016-04-01

Understanding the dynamics of rockfalls is critical to mitigate the associated hazards but is made very difficult by the nature of these natural disasters that makes them hard to observe directly. Recent advances in seismology allow to determine the dynamics of the largest landslides on Earth from the very low-frequency seismic waves they generate. However, the vast majority of rockfalls that occur worldwide are too small to generate such low-frequency seismic waves and thus these methods cannot be used to reconstruct their dynamics. However, if seismic sensors are close enough, these events will generate high-frequency seismic signals. Unfortunately we cannot yet use these high-frequency seismic records to infer parameters synthetizing the rockfall dynamics as the source of these waves is not well understood. One of the first steps towards understanding the physical processes involved in the generation of high-frequency seismic waves by rockfalls is to study the link between the dynamics of a single block propagating along a well-known path and the features of the seismic signal generated. We conducted controlled releases of single blocks of limestones in a gully of clay-shales (e.g. black marls) in the Rioux Bourdoux torrent (French Alps). 28 blocks, with masses ranging from 76 kg to 472 kg, were released. A monitoring network combining high-velocity cameras, a broadband seismometer and an array of 4 high-frequency seismometers was deployed near the release area and along the travel path. The high-velocity cameras allow to reconstruct the 3D trajectories of the blocks, to estimate their velocities and the position of the different impacts with the slope surface. These data are compared to the seismic signals recorded. As the distance between the block and the seismic sensors at the time of each impact is known, we can determine the associated seismic signal amplitude corrected from propagation and attenuation effects. We can further compare the velocity, the energy and the momentum of the block at each impact to the true amplitude and the energy of the corresponding part of the seismic signal. Finding potential correlations and scaling laws between the dynamics of the source and the high-frequency seismic signal features constitutes an important breakthrough to understand more complex slope movements that involve multiple blocks or granular flows. This approach may lead to future developments of methods able to determine the dynamics of a large variety of slope movements directly from the seismic signals they generate.

The Effect of Art Therapy with Clay on Hopelessness Levels Among Neurology Patients.

PubMed

Akhan, Latife Utas; Kurtuncu, Meltem; Celik, Sevim

This study was performed to determine the effect of art therapy with clay on hopelessness levels of patients under treatment in departments of neurology. The study was of one group, pre- and posttest design. This study was performed on patients who were hospitalized in the neurology departments of a university and a state hospital between February and May 2012 in Turkey. The sample for the study comprised 50 neurology patients with diagnoses of epilepsy (17 patients) and stroke (33 patients). The patients in the study were asked to create objects of clay of any shape they desired. Data for the research were collected with a sociodemographic data form and by using the Beck Hopelessness Scale (BHS). While BHS scores of neurology patients before clay therapy were found higher compared to the scores after therapy with clay, there was also a statistically significant difference. After clay therapy, BHS scores were lower in women, in married patients, in patients who suffered from a stroke, people who had chronic disease, people without psychological illness, and in the case of children. The study showed that clay therapy had an impact on the hopelessness levels of neurology patients. Art therapy with clay may be used for rehabilitation purposes in neurology patients, both in the hospital and at home after discharge.

Strength of the San Andreas Fault Zone: Insight From SAFOD Cuttings and Core

NASA Astrophysics Data System (ADS)

Tembe, S.; Lockner, D. A.; Solum, J. G.; Morrow, C. A.; Wong, T.; Moore, D. E.

2005-12-01

Cuttings acquired during drilling of the SAFOD scientific hole near Parkfield, California offer a continuous physical record of the lithology across the San Andreas fault (SAF) zone and provide the only complete set of samples available for laboratory testing. Guided by XRD clay mineral analysis and velocity and gamma logs, we selected washed cuttings from depths spanning the main hole from 1.85 to 3.0 km true vertical depth. Cuttings were chosen to represent primary lithologic units as well as significant shear zones, including candidates for the currently active SAF. To determine frictional properties triaxial sliding tests were conducted on cylindrical granite blocks containing sawcuts inclined at 30° and filled with 1 mm-thick sample gouge layers. Tests were run at constant effective normal stresses of 10 and 40 MPa and constant pore pressure of 1 MPa. Samples were sheared up to 10.4 mm at room temperature and velocities of 1, 0.1 and 0.01 μm/s. Stable sliding behavior and overall strain hardening were observed in all tests. The coefficient of friction typically showed a modest decrease with increasing effective normal stress and mostly velocity strengthening was observed. Preliminary results yield coefficients of friction, μ, which generally fell into two clusters spanning the range of 0.45 to 0.8. The higher values of friction (~0.7 - 0.8) corresponded to quartzofeldspathic samples derived from granodiorites and arkoses encountered in the drill hole. Lower values of friction (0.45 - 0.55) were observed at depth intervals interpreted as shear zones based on enriched clay content, reduced seismic velocities and increased gamma radiation. Arguments for a weak SAF suggest coseismic frictional strength of μ = 0.1 to 0.2 yet the actual fault zone materials studied here appear consistently stronger. At least two important limitations exist for inferring in-situ fault strength from cuttings. (1) Clays and weak minerals are preferentially lost during drilling and therefore undersampled in the cuttings and (2) cuttings are mixed as they travel up the borehole. To test the validity of this approach sliding tests were conducted on core samples obtained from a prominent fault zone at 2.56 km (10062 ft measured depth). Coefficient of friction was measured to be 0.42-0.5, notably weaker than that for cuttings tested at this depth (~0.6) but similar to values obtained for other shear zones. This difference between core and cuttings from the equivalent depth is likely due to mixing, resulting in the averaging of mechanical properties over a 1 to 10 foot interval. Nevertheless, we find good agreement in the strength of materials obtained from shallow shear zones, an indication that some weak mineral phases are preserved in the cuttings. While our findings indicate that meaningful mechanical data can be derived from the cuttings, it should be noted that these observations do not represent an exhaustive study of SAF frictional strength. We continue to explore the effectiveness of the present technique by a variety of methods. For example, estimates of lost clay fractions determined from XRD analysis of unwashed cuttings can be used in the application of approximate mixing laws to correct friction measurements. In addition, comparisons of strength of cuttings and corresponding sidewall cores will help refine our results. While the analysis of cuttings provides the best fault zone strength data to date, unresolved questions show the importance of collecting continuous core in Phase 3 drilling planned for 2007.

Determining photon energy absorption parameters for different soil samples

PubMed Central

Kucuk, Nil; Tumsavas, Zeynal; Cakir, Merve

2013-01-01

The mass attenuation coefficients (μs) for five different soil samples were measured at 661.6, 1173.2 and 1332.5 keV photon energies. The soil samples were separately irradiated with 137Cs and 60Co (370 kBq) radioactive point gamma sources. The measurements were made by performing transmission experiments with a 2″ × 2″ NaI(Tl) scintillation detector, which had an energy resolution of 7% at 0.662 MeV for the gamma-rays from the decay of 137Cs. The effective atomic numbers (Zeff) and the effective electron densities (Neff) were determined experimentally and theoretically using the obtained μs values for the soil samples. Furthermore, the Zeff and Neff values of the soil samples were computed for the total photon interaction cross-sections using theoretical data over a wide energy region ranging from 1 keV to 15 MeV. The experimental values of the soils were found to be in good agreement with the theoretical values. Sandy loam and sandy clay loam soils demonstrated poor photon energy absorption characteristics. However, clay loam and clay soils had good photon energy absorption characteristics. PMID:23179375

Factors of soil diversity in the Batumi delta (Georgia)

NASA Astrophysics Data System (ADS)

Turgut, Bülent; Ateş, Merve

2017-01-01

The aim of this study was to determine certain basic properties of soils in the Batumi delta (southwestern Georgia) to determine the relationships of studied properties and to identify differences with regards to these properties between different sampling sites in the delta that were selected based on the delta morphology. In this context, a total of 125 soil samples were collected from five different sampling sites, and the clay, silt and sand content of the samples were determined along with their mean weight diameter (MWD) values, aggregate stability (AS) values, amount of water retained under -33 (FC) and -1500 kPa (WP) pressure and organic matter (OM) content. Correlation analysis indicated that clay content and OM were positively correlated with MWD, and OM was positively correlated with AS. However, the sand content was found to be negatively correlated with MWD. In addition, clay, silt and OM content were positive correlated with FC and WP. Variance analysis results determined statistically significant differences between the sampling sites with respect to all of the evaluated properties. The active delta section of the study area was characterized by high sand content, while the lower delta plain was characterized by high OM and AS values, and the upper delta plain was characterized by high MWD values, high FC and WP moisture content levels and high clay and silt content. In conclusion, it was demonstrated that the examined properties were significantly affected by the different morphological positions and usages of these different areas. These results may help with the management of agricultural lands in the Batumi delta, which has never been studied before.

Proposal of a sequential treatment methodology for the safe reuse of oil sludge-contaminated soil.

PubMed

Mater, L; Sperb, R M; Madureira, L A S; Rosin, A P; Correa, A X R; Radetski, C M

2006-08-25

In this study sequential steps were used to treat and immobilize oil constituents of an oil sludge-contaminated soil. Initially, the contaminated soil was oxidized by a Fenton type reaction (13 wt% for H(2)O(2); 10mM for Fe(2+)). The oxidative treatment period of 80 h was carried out under three different pH conditions: 20 h at pH 6.5, 20 h at pH 4.5, and 40 h at pH 3.0. The oxidized contaminated sample (3 kg) was stabilized and solidified for 2h with clay (1 kg) and lime (2 kg). Finally, this mixture was solidified by sand (2 kg) and Portland cement (4 kg). In order to evaluate the efficiency of different processes to treat and immobilize oil contaminants of the oil sludge-contaminated soil, leachability and solubility tests were performed and extracts were analyzed according to the current Brazilian waste regulations. Results showed that the Fenton oxidative process was partially efficient in degrading the oil contaminants in the soil, since residual concentrations were found for the PAH and BTEX compounds. Leachability tests showed that clay-lime stabilization/solidification followed by Portland cement stabilization/solidification was efficient in immobilizing the recalcitrant and hazardous constituents of the contaminated soil. These two steps stabilization/solidification processes are necessary to enhance environmental protection (minimal leachability) and to render final product economically profitable. The treated waste is safe enough to be used on environmental applications, like roadbeds blocks.

Distribution, fate and formation of non-extractable residues of a nonylphenol isomer in soil with special emphasis on soil derived organo-clay complexes.

PubMed

Riefer, Patrick; Klausmeyer, Timm; Schäffer, Andreas; Schwarzbauer, Jan; Schmidt, Burkhard

2011-01-01

Anthropogenic contaminants like nonylphenols (NP) are added to soil, for instance if sewage-sludge is used as fertilizer in agriculture. A commercial mixture of NP consists of more than 20 isomers. For our study, we used one of the predominate isomers of NP mixtures, 4-(3,5-dimethylhept-3-yl)phenol, as a representative compound. The aim was to investigate the fate and distribution of the isomer within soil and soil derived organo-clay complexes. Therefore, (14)C- and (13)C-labeled NP was added to soil samples and incubated up to 180 days. Mineralization was measured and soil samples were fractionated into sand, silt and clay; the clay fraction was further separated in humic acids, fulvic acids and humin. The organo-clay complexes pre-incubated for 90 or 180 days were re-incubated with fresh soil for 180 days, to study the potential of re-mobilization of incorporated residues. The predominate incorporation sites of the nonylphenol isomer in soil were the organo-clay complexes. After 180 days of incubation, 22 % of the applied (14)C was mineralized. The bioavailable, water extractable portion was low (9 % of applied (14)C) and remained constant during the entire incubation period, which could be explained by an incorporation/release equilibrium. Separation of organo-clay complexes, after extraction with solvents to release weakly incorporated, bioaccessible portions, showed that non-extractable residues (NER) were preferentially located in the humic acid fraction, which was regarded as an effect of the chemical composition of this fraction. Generally, 27 % of applied (14)C was incorporated into organo-clay complexes as NER, whereas 9 % of applied (14)C was bioaccessible after 180 days of incubation. The re-mobilization experiments showed on the one hand, a decrease of the bioavailability of the nonylphenol residues due to stronger incorporation, when the pre-incubation period was increased from 90 to 180 days. On the other hand, a shift of these residues from the clay fraction to other soil fractions was observed, implying a dynamic behavior of incorporated residues, which may result in bioaccessibility of the NER of nonylphenol.

Clay catalyzed RNA synthesis under Martian conditions: Application for Mars return samples.

PubMed

Joshi, Prakash C; Dubey, Krishna; Aldersley, Michael F; Sausville, Meaghen

2015-06-26

Catalysis by montmorillonites clay minerals is regarded as a feasible mechanism for the abiotic production and polymerization of key biomolecules on early Earth. We have investigated a montmorillonite-catalyzed reaction of the 5'-phosphorimidazolide of nucleosides as a model to probe prebiotic synthesis of RNA-type oligomers. Here we show that this model is specific for the generation of RNA oligomers despite deoxy-mononucleotides adsorbing equally well onto the montmorillonite catalytic surfaces. Optimum catalytic activity was observed over a range of pH (6-9) and salinity (1 ± 0.2 M NaCl). When the weathering steps of early Earth that generated catalytic montmorillonite were modified to meet Martian soil conditions, the catalytic activity remained intact without altering the surface layer charge. Additionally, the formation of oligomers up to tetramer was detected using as little as 0.1 mg of Na⁺-montmorillonite, suggesting that the catalytic activity of a Martian clay return sample can be investigated with sub-milligram scale samples. Copyright © 2015 Elsevier Inc. All rights reserved.

AN ASSESSMENT OF DIOXIN LEVELS IN PROCESSED BALL CLAY FROM THE U.S.

EPA Science Inventory

The presence of dioxin-like compounds in ball clay was discovered in 1996 as a result of an investigation to determine the sources of elevated levels of dioxin found in two chicken fat samples from a national survey of poultry. The investigation indicated that soybean meal added...

Comparison of rapid methods for chemical analysis of milligram samples of ultrafine clays

USGS Publications Warehouse

Rettig, S.L.; Marinenko, J.W.; Khoury, Hani N.; Jones, B.F.

1983-01-01

Two rapid methods for the decomposition and chemical analysis of clays were adapted for use with 20–40-mg size samples, typical amounts of ultrafine products (≤0.5-µm diameter) obtained by modern separation methods for clay minerals. The results of these methods were compared with those of “classical” rock analyses. The two methods consisted of mixed lithium metaborate fusion and heated decomposition with HF in a closed vessel. The latter technique was modified to include subsequent evaporation with concentrated H2SO4 and re-solution in HCl, which reduced the interference of the fluoride ion in the determination of Al, Fe, Ca, Mg, Na, and K. Results from the two methods agree sufficiently well with those of the “classical” techniques to minimize error in the calculation of clay mineral structural formulae. Representative maximum variations, in atoms per unit formula of the smectite type based on 22 negative charges, are 0.09 for Si, 0.03 for Al, 0.015 for Fe, 0.07 for Mg, 0.03 for Na, and 0.01 for K.

Hydro-mechanical properties of the Red Salt Clay (T4) - Relevancy of the minimum stress criterion for barrier integrity

NASA Astrophysics Data System (ADS)

Minkley, W.; Popp, T.; Salzer, K.; Gruner, M.; Böttge, V.

The so-called Red Salt Clay (T4) is deposited as clay-rich clastic sediment at the base of the Aller-series forming a persistent lateral layer of up to 20 m thickness above the lower Zechstein-series. The clay layers may act as a protective shield in the hanging wall of gas storages or underground repositories in salt formations, thus resulting in a multi-barrier system. As a proof of its reliability comprehensive hydro-mechanical investigations were performed on clay samples recovered at different sites in Germany. Most important, rock tightness against various fluids was confirmed in the lab and field-scale. Remarkably, only if the fluid pressure equalises the acting minimal stress (i.e. violence of the “minimum stress criterion”) a significant increase of permeability is observed (“pathway dilatation”) but no macro-frac. However, the material properties from different locations showed a significant variability according to different burial depths. Thus the Red Salt Clay may act as natural analogue, representing the material variability of various indurated clays. In addition, the existing knowledge gained from practical mining activities can be used to evaluate extreme in situ loading conditions.

Clay-sewage sludge co-pyrolysis. A TG-MS and Py-GC study on potential advantages afforded by the presence of clay in the pyrolysis of wastewater sewage sludge

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ischia, Marco, E-mail: marco.ischia@ing.unitn.it; Maschio, Roberto Dal; Grigiante, Maurizio

2011-01-15

Wastewater sewage sludge was co-pyrolyzed with a well characterized clay sample, in order to evaluate possible advantages in the thermal disposal process of solid waste. Characterization of the co-pyrolysis process was carried out both by thermogravimetric-mass spectrometric (TG-MS) analysis, and by reactor tests, using a lab-scale batch reactor equipped with a gas chromatograph for analysis of the evolved gas phase (Py-GC). Due to the presence of clay, two main effects were observed in the instrumental characterization of the process. Firstly, the clay surface catalyzed the pyrolysis reaction of the sludge, and secondly, the release of water from the clay, atmore » temperatures of approx. 450-500 deg. C, enhanced gasification of part of carbon residue of the organic component of sludge following pyrolysis. Moreover, the solid residue remaining after pyrolysis process, composed of the inorganic component of sludge blended with clay, is characterized by good features for possible disposal by vitrification, yielding a vitreous matrix that immobilizes the hazardous heavy metals present in the sludge.« less

Determination of trace elements and their concentrations in clay balls: problem of geophagia practice in Ghana.

PubMed

Arhin, Emmanuel; Zango, Musah S

2017-02-01

Ten samples of 100 g weight were subsampled from 1400 g of the clay balls from which the contained trace element levels were determined by X-ray fluorescence technique. The results of trace elements in the clay balls were calibrated using certified reference materials "MAJMON" and "BH-1." The results showed elevated concentrations but with different concentration levels in the regions, particularly with arsenic, chromium, cobalt, Cs, Zr and La. These trace elements contained in the clay balls are known to be hazardous to human health. Thence the relatively high concentrations of these listed trace elements in clay balls in the three regions, namely Ashanti, Upper East and Volta, which are widely sold in markets in Ghana, could present negative health impact on consumers if consumed at 70 g per day or more and on regular basis. On the basis of these, the study concludes an investigation to establish breakeven range for trace element concentrations in the clay balls as it has been able to demonstrate the uneven and elevated values in them. The standardized safe ranges of trace elements will make the practice safer for the people that ingest clay balls in Ghana.

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

PubMed

Williams, Lynda B; Haydel, Shelley E

2010-07-01

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 degrees C), then dehydroxylation (550 degrees C or more), and finally to destruction of the clay mineral structure by (~900 degrees 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.

Concentrations of selected constituents in surface-water and streambed-sediment samples collected from streams in and near an area of oil and natural-gas development, south-central Texas, 2011-13

USGS Publications Warehouse

Opsahl, Stephen P.; Crow, Cassi L.

2014-01-01

During collection of streambed-sediment samples, additional samples from a subset of three sites (the SAR Elmendorf, SAR 72, and SAR McFaddin sites) were processed by using a 63-µm sieve on one aliquot and a 2-mm sieve on a second aliquot for PAH and n-alkane analyses. The purpose of analyzing PAHs and n-alkanes on a sample containing sand, silt, and clay versus a sample containing only silt and clay was to provide data that could be used to determine if these organic constituents had a greater affinity for silt- and clay-sized particles relative to sand-sized particles. The greater concentrations of PAHs in the <63-μm size-fraction samples at all three of these sites are consistent with a greater percentage of binding sites associated with fine-grained (<63 μm) sediment versus coarse-grained (<2 mm) sediment. The larger difference in total PAHs between the <2-mm and <63-μm size-fraction samples at the SAR Elmendorf site might be related to the large percentage of sand in the <2-mm size-fraction sample which was absent in the <63-μm size-fraction sample. In contrast, the <2-mm size-fraction sample collected from the SAR McFaddin site contained very little sand and was similar in particle-size composition to the <63-μm size-fraction sample.

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

NASA Astrophysics Data System (ADS)

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

2016-04-01

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

Laboratory electrical resistivity analysis of geologic samples from Fort Irwin, California: Chapter E in Geology and geophysics applied to groundwater hydrology at Fort Irwin, California

USGS Publications Warehouse

Bloss, Benjamin R.; Bedrosian, Paul A.; Buesch, David C.

2015-01-01

Correlating laboratory resistivity measurements with geophysical resistivity models helps constrain these models to the geology and lithology of an area. Throughout the Fort Irwin National Training Center area, 111 samples from both cored boreholes and surface outcrops were collected and processed for laboratory measurements. These samples represent various lithologic types that include plutonic and metamorphic (basement) rocks, lava flows, consolidated sedimentary rocks, and unconsolidated sedimentary deposits that formed in a series of intermountain basins. Basement rocks, lava flows, and some lithified tuffs are generally resistive (≥100 ohm-meters [Ω·m]) when saturated. Saturated unconsolidated samples are moderately conductive to conductive, with resistivities generally less than 100 Ω·m, and many of these samples are less than 50 Ω·m. The unconsolidated samples can further be separated into two broad groups: (1) younger sediments that are moderately conductive, owing to their limited clay content, and (2) older, more conductive sediments with a higher clay content that reflects substantial amounts of originally glassy volcanic ash subsequently altered to clay. The older sediments are believed to be Tertiary. Time-domain electromagnetic (TEM) data were acquired near most of the boreholes, and, on the whole, close agreements between laboratory measurements and resistivity models were found. 

Assessing behind armor blunt trauma in accordance with the National Institute of Justice Standard for Personal Body Armor Protection using finite element modeling.

PubMed

Roberts, Jack C; Ward, Emily E; Merkle, Andrew C; O'Connor, James V

2007-05-01

To assess the possibility of injury as a result of behind armor blunt trauma (BABT), a study was undertaken to determine the conditions necessary to produce the 44-mm clay deformation as set forth in the National Institute of Justice (NIJ) Standard 0101.04. These energy levels were then applied to a three-dimensional Human Torso Finite Element Model (HTFEM) with soft armor vest. An examination will be made of tissue stresses to determine the effects of the increased kinetic energy levels on the probability of injury. A clay finite element model (CFEM) was created with a material model that required nonlinear properties for clay. To determine these properties empirically, the results from the CFEM were matched with experimental drop tests. A soft armor vest was modeled over the clay to create a vest over clay block finite element model (VCFEM) and empirical methods were again used to obtain material properties for the vest from experimental ballistic testing. Once the properties for the vest and clay had been obtained, the kinetic energy required to produce a 44-mm deformation in the VCFEM was determined through ballistic testing. The resulting kinetic energy was then used in the HTFEM to evaluate the probability of BABT. The VCFEM, with determined clay and vest material properties, was exercised with the equivalent of a 9-mm (8-gm) projectile at various impact velocities. The 44-mm clay deformation was produced with a velocity of 785 m/s. This impact condition (9-mm projectile at 785 m/s) was used in ballistic exercises of the HTFEM, which was modeled with high-strain rate human tissue properties for the organs. The impact zones were over the sternum anterior to T6 and over the liver. The principal stresses in both soft and hard tissue at both locations exceeded the tissue tensile strength. This study indicates that although NIJ standard 0101.04 may be a good guide to soft armor failure, it may not be as good a guide in BABT, especially at large projectile kinetic energies. Further studies, both numerical and experimental, are needed to assist in predicting injury using the NIJ standard.

Deformation mechanisms in experimentally deformed Boom Clay

NASA Astrophysics Data System (ADS)

Desbois, Guillaume; Schuck, Bernhard; Urai, Janos

2016-04-01

Bulk mechanical and transport properties of reference claystones for deep disposal of radioactive waste have been investigated since many years but little is known about microscale deformation mechanisms because accessing the relevant microstructure in these soft, very fine-grained, low permeable and low porous materials remains difficult. Recent development of ion beam polishing methods to prepare high quality damage free surfaces for scanning electron microscope (SEM) is opening new fields of microstructural investigation in claystones towards a better understanding of the deformation behavior transitional between rocks and soils. We present results of Boom Clay deformed in a triaxial cell in a consolidated - undrained test at a confining pressure of 0.375 MPa (i.e. close to natural value), with σ1 perpendicular to the bedding. Experiments stopped at 20 % strain. As a first approximation, the plasticity of the sample can be described by a Mohr-Coulomb type failure envelope with a coefficient of cohesion C = 0.117 MPa and an internal friction angle ϕ = 18.7°. After deformation test, the bulk sample shows a shear zone at an angle of about 35° from the vertical with an offset of about 5 mm. We used the "Lamipeel" method that allows producing a permanent absolutely plane and large size etched micro relief-replica in order to localize and to document the shear zone at the scale of the deformed core. High-resolution imaging of microstructures was mostly done by using the BIB-SEM method on key-regions identified after the "Lamipeel" method. Detailed BIB-SEM investigations of shear zones show the following: the boundaries between the shear zone and the host rock are sharp, clay aggregates and clastic grains are strongly reoriented parallel to the shear direction, and the porosity is significantly reduced in the shear zone and the grain size is smaller in the shear zone than in the host rock but there is no evidence for broken grains. Comparison of microstructures within the host rock and the undeformed sample shows that the sample underwent compaction prior shearing that results in a change of power law exponent of the pore size distribution within the clay matrix and a slight reorientation of clastic grains' long axis perpendicular to σ1. Microstructures in the shear zone indicate ductile behavior before the specimen's failure. Deformation mechanisms are bending of clay plates and sliding along clay-clay contacts. Strain is strongly localised in thin, anastomosing zones of strong preferred orientation, producing slickensided shear surfaces common in shallow clays. There is no evidence for intragranular cracking.We propose that the deformation localizes in regions without hard quartz grains.

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

NASA Technical Reports Server (NTRS)

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

2001-01-01

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

Storage and persistence of a candidate fungal biopesticide for use against adult malaria vectors

PubMed Central

2012-01-01

Background New products aimed at augmenting or replacing chemical insecticides must have operational profiles that include both high efficacy in reducing vector numbers and/or blocking parasite transmission and be long lasting following application. Research aimed at developing fungal spores as a biopesticide for vector control have shown considerable potential yet have not been directly assessed for their viability after long-term storage or following application in the field. Methods Spores from a single production run of the entomopathogenic fungi Beauveria bassiana were dried and then stored under refrigeration at 7°C. After 585 days these spores were sub-sampled and placed at either 22°C, 26°C or 32°C still sealed in packaging (closed storage) or in open beakers and exposed to the 80% relative humidity of the incubator they were kept in. Samples were subsequently taken from these treatments over a further 165 days to assess viability. Spores from the same production run were also used to test their persistence following application to three different substrates, clay, cement and wood, using a hand held sprayer. The experiments were conducted at two different institutes with one using adult female Anopheles stephensi and the other adult female Anopheles gambiae. Mosquitoes were exposed to the treated substrates for one hour before being removed and their survival monitored for the next 14 days. Assays were performed at monthly intervals over a maximum seven months. Results Spore storage under refrigeration resulted in no loss of spore viability over more than two years. Spore viability of those samples kept under open and closed storage was highly dependent on the incubation temperature with higher temperatures decreasing viability more rapidly than cooler temperatures. Mosquito survival following exposure was dependent on substrate type. Spore persistence on the clay substrate was greatest achieving 80% population reduction for four months against An. stephensi and for at least five months against Anopheles gambiae. Cement and wood substrates had more variable mortality with the highest spore persistence being two to three months for the two substrates respectively. Conclusions Spore shelf-life under refrigeration surpassed the standard two year shelf-life expected of a mosquito control product. Removal to a variety of temperatures under either closed or open storage indicated that samples sent out from refrigeration should be deployed rapidly in control operations to avoid loss of viability. Spore persistence following application onto clay surfaces was comparable to a number of chemical insecticides in common use. Persistence on cement and wood was shorter but in one assay still comparable to some organophosphate and pyrethroid insecticides. Optimized formulations could be expected to improve spore persistence still further. PMID:23098323

Storage and persistence of a candidate fungal biopesticide for use against adult malaria vectors.

PubMed

Blanford, Simon; Jenkins, Nina E; Christian, Riann; Chan, Brian H K; Nardini, Luisa; Osae, Michael; Koekemoer, Lizette; Coetzee, Maureen; Read, Andrew F; Thomas, Matthew B

2012-10-25

New products aimed at augmenting or replacing chemical insecticides must have operational profiles that include both high efficacy in reducing vector numbers and/or blocking parasite transmission and be long lasting following application. Research aimed at developing fungal spores as a biopesticide for vector control have shown considerable potential yet have not been directly assessed for their viability after long-term storage or following application in the field. Spores from a single production run of the entomopathogenic fungi Beauveria bassiana were dried and then stored under refrigeration at 7°C. After 585 days these spores were sub-sampled and placed at either 22°C, 26°C or 32°C still sealed in packaging (closed storage) or in open beakers and exposed to the 80% relative humidity of the incubator they were kept in. Samples were subsequently taken from these treatments over a further 165 days to assess viability. Spores from the same production run were also used to test their persistence following application to three different substrates, clay, cement and wood, using a hand held sprayer. The experiments were conducted at two different institutes with one using adult female Anopheles stephensi and the other adult female Anopheles gambiae. Mosquitoes were exposed to the treated substrates for one hour before being removed and their survival monitored for the next 14 days. Assays were performed at monthly intervals over a maximum seven months. Spore storage under refrigeration resulted in no loss of spore viability over more than two years. Spore viability of those samples kept under open and closed storage was highly dependent on the incubation temperature with higher temperatures decreasing viability more rapidly than cooler temperatures. Mosquito survival following exposure was dependent on substrate type. Spore persistence on the clay substrate was greatest achieving 80% population reduction for four months against An. stephensi and for at least five months against Anopheles gambiae. Cement and wood substrates had more variable mortality with the highest spore persistence being two to three months for the two substrates respectively. Spore shelf-life under refrigeration surpassed the standard two year shelf-life expected of a mosquito control product. Removal to a variety of temperatures under either closed or open storage indicated that samples sent out from refrigeration should be deployed rapidly in control operations to avoid loss of viability. Spore persistence following application onto clay surfaces was comparable to a number of chemical insecticides in common use. Persistence on cement and wood was shorter but in one assay still comparable to some organophosphate and pyrethroid insecticides. Optimized formulations could be expected to improve spore persistence still further.

Evaluation of the medicinal use of clay minerals as antibacterial agents

PubMed Central

Williams, Lynda B.; Haydel, Shelley E.

2010-01-01

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

Distribution of clay minerals in surface sediments of the western Gulf of Thailand: Sources and transport patterns

NASA Astrophysics Data System (ADS)

Shi, Xuefa; Liu, Shengfa; Fang, Xisheng; Qiao, Shuqing; Khokiattiwong, Somkiat; Kornkanitnan, Narumol

2015-06-01

A high density sampling program during two joint China-Thailand scientific cruises in 2011-2012 included collection of 152 gravity box cores in the Gulf of Thailand (GoT). Samples from the top 5 cm of each core were analyzed by X-ray diffraction for clay mineral content. Several systemic analytical approaches were applied to examine the distribution pattern and the constraint factors of clay minerals in the surface sediments of the western GoT. The clay minerals mainly comprise illite, kaolinite, chlorite and smectite, having the average weight percent distributions of 50%, 34%, 14% and 2%, respectively. Based on the spatial distribution characteristics and statistical results, the study area can be classified into three provinces. Province I contains high concentrations of smectite, and covers the northern GoT, sediments in this province are mainly from rivers discharging into the upper GoT, especially the Chao Phraya and Mae Klong Rivers. Sediments in Province II are characterized by higher values of illite, located in the central GoT, where fine sediments are contributed by the Mekong River and from the South China Sea. Province Ш, in the coastal regions of southwestern GoT close to Malaysia, exhibits a clay mineral assemblage with complex distribution patterns, and may contain terrestrial materials from the Mae Klong River as well as re-suspended sediments. Results of integrative analysis also demonstrate that the hydrodynamic environment in the study area, especially the seasonal various circumfluence and eddies, play an important role in the spatial distribution and dispersal of clay fraction in sediments.

Clay-enhanced DNA separation in low-molecular-weight poly(N,N-dimethylacrylamide) solution by capillary electrophoresis.

PubMed

Liang, D; Song, L; Chen, Z; Chu, B

2001-06-01

The effect of the separation medium in capillary electrophoresis consisting of a low-molecular-mass poly(N,N-dimethylacrylamide) (PDMA) solution on the DNA separation by adding a small amount of montmorillonite clay into the polymer matrix is presented. On the separation of the pBR322/HaeIII digest, both the resolution and the efficiency were increased by adding 2.5-5.0 x 10(-5) g/mL clay into the 5% w/v PDMA with a molecular mass of only 100 K. Moreover, there was no increase in the migration time of DNA fragments. Similar results were observed by using a C-terminated pGEM-3Zf(+) sequencing DNA sample in a sequencing buffer. Experimental data also showed that the addition of clay increased the viscosity of the polymer solution. We attribute this effect to the structural change of the polymer matrix caused by the exfoliated clay sheets, whereby the thin clay sheets function like a "dynamic cross-linking plate" for the PDMA chains and effectively increase the apparent molecular mass of PDMA.

Implementation of a best management practice (BMP) system for a clay mining facility in Taiwan.

PubMed

Lin, Jen-Yang; Chen, Yen-Chang; Chen, Walter; Lee, Tsu-Chuan; Yu, Shaw L

2006-01-01

The present paper describes the planning and implementation of a best management practice (BMP) system for a clay mining facility in Northern Taiwan. It is a challenge to plan and design BMPs for mitigating the impact of clay mining operations due to the fact that clay mining drainage typically contains very high concentrations of suspended solids (SS), Fe-ions, and [H+] concentrations. In the present study, a field monitoring effort was conducted to collect data for runoff quality and quantity from a clay mining area in Northern Taiwan. A BMP system including holding ponds connected in series was designed and implemented and its pollutant removal performance was assessed. The assessment was based on mass balance computations and an analysis of the relationship between BMP design parameters such as pond depth, detention time, surface loading rate, etc. and the pollutant removal efficiency. Field sampling results showed that the surface-loading rate is exponential related to the removing rate. The results provide the basis for a more comprehensive and efficient BMP implementation plan for clay mining operations.

ON THE GEOCHEMISTRY OF NIOBIUM AND TANTALUM IN CLAYS (in Russian)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pachadzhanov, D.N.

1963-10-01

With the aid of the spectral method with a preliminary enrichment in tannin, the niobium and tantalum content was determined in some humid and arid clays of the Russian platform. The investigated samples were composed of 354 specimens. The average content of niobium in humid clays is 0.0020%, of tantalum 0.00024% (the Nb/Ta ratio is 8.4) and in arid clays is respectively the content of niobium 0.00133% and the content of tantalum 0.00009% (the Nb/Ta ratio is 14.8). The average value of the content of niobium content for all studied clays is 0.00183% and of the tantalum content 0.00020%, themore » Nb/Ta ratio being 9.1. In clays an interconnection of niobium with tantalum, as well as with aluminium, titanium, zirconium, and hafnium was observed. However, on the background of this connection some separation of the named elements is noted. A tendency for the Nb/Ta ratio shift from the region of matter removal towards the center of the marine basin was observed. The study of niobium and tantalum distribution over different clay fractions showed that one part of elements is connected with zircon and titanium minerals in aleuosand fraction (0.1-- 0.01 mm). Another, approximately similar part is contained in the proper clay fraction (<0. 01 mm), the tantalum somewhat more concentrating in the aleurosand fraction and niobium in the clay fraction. (P.C.H.)« less

Tailoring the mechanical properties of SU-8/clay nanocomposites: polymer microcantilever fabrication perspective

NASA Astrophysics Data System (ADS)

Chen, Hao; Ojijo, Vincent; Cele, Hastings; Joubert, Trudi; Suprakas, Sinha Ray; Land, Kevin

2014-06-01

SU-8/Clay nanocomposite is considered as a candidate material for microcantilever sensor fabrication. Organically modified montmorillonite clay nanoparticles are dispersed in the universally used negative photoresist polymer SU-8, for a low cost material, which is also biocompatible. If varying the clay loading of the composite material yields a variation of the Young's modulus, the tailored material stiffness presents an opportunity for fabrication of microcantilevers with tunable sensor sensitivity. With this microcantilever application perspective, mechanical and thermal properties of the material were investigated. SU-8/Clay nanocomposite samples were prepared with clay loadings from 1wt% - 10wt%. Tensile test results show a general trend of increase in composite modulus with an increase in the clay loading up to 7wt%, followed by a small drop at 10wt%. The composite material indeed yields moderate variation of the Young's modulus. It was also found that the thermal degradation peak of the material occurred at 300°C, which is beyond the operating temperature of typical microcantilever sensor applications. The fabrication of a custom designed microcantilever array chip with the SU-8/Clay nanocomposite material was achieved in a class 100 cleanroom, using spin-coating and photolithography microfabrication techniques. The optimization of the process for fabricating microcantilever with the SU-8/Clay nanocomposite material is discussed in this paper. The results of this research are promising for cheaper mass production of low cost disposable, yet sensitive, microcantilever sensor elements, including biosensor applications.

Fire performance of fiber board coated with nano kaolin-clay film

Treesearch

Zhijia Liu; John F. Hunt; Zhiyong Cai

2013-01-01

Fiberboard is a common interior material used both in China and the United States of America. The increase in demand for interior materials has raised concerns regarding combustibility of the materials. The pyrolysis characteristics of fiber, phenolic resin (PF), and nano kaolin-clay (NK) were investigated using thermogravimetry. The fire performances of samples coated...

[Characteristics of soil moisture in artificial impermeable layers].

PubMed

Suo, Gai-Di; Xie, Yong-Sheng; Tian, Fei; Chuai, Jun-Feng; Jing, Min-Xiao

2014-09-01

For the problem of low water and fertilizer use efficiency caused by nitrate nitrogen lea- ching into deep soil layer and soil desiccation in dryland apple orchard, characteristics of soil moisture were investigated by means of hand tamping in order to find a new approach in improving the water and fertilizer use efficiency in the apple orchard. Two artificial impermeable layers of red clay and dark loessial soil were built in soil, with a thickness of 3 or 5 cm. Results showed that artificial impermeable layers with the two different thicknesses were effective in reducing or blocking water infiltration into soil and had higher seepage controlling efficiency. Seepage controlling efficiency for the red clay impermeable layer was better than that for the dark loessial soil impermeable layer. Among all the treatments, the red clay impermeable layer of 5 cm thickness had the highest bulk density, the lowest initial infiltration rate (0.033 mm · min(-1)) and stable infiltration rate (0.018 mm · min(-1)) among all treatments. After dry-wet alternation in summer and freezing-thawing cycle in winter, its physiochemical properties changed little. Increase in years did not affect stable infiltration rate of soil water. The red clay impermeable layer of 5 cm thickness could effectively increase soil moisture content in upper soil layer which was conducive to raise the water and nutrient use efficiency. The approach could be applied to the apple production of dryland orchard.

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

NASA Astrophysics Data System (ADS)

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

2015-04-01

Cation exchange capacity (CEC) represents one of the most important parameters of clay minerals which reflects their ability to exchange cations with liquid phases in near contact. Measurement of CEC is used for characterizing sample plasticity, adsorbing and swelling properties which later define their usage in industrial purposes. Several methods have been developed over the years for determination of layer charge, charge density, charge distribution, etc. and have been published in numerous papers (Czimerova et al., 2006; Yukselen and Kaya, 2008). The main goal of present study is comparison of suitability of more recent method - methylene blue test in regard to older method - ammonium acetate for determination of CEC. For this study, we selected one montmorillonite clay (Bogovina, Serbia) and two mainly kaolinite clays (Miličinica, Serbia). Chemicals used for CEC determinations were solution of methylene blue (MB)(14*10-6M/ml) and ammonium acetate (AA) solution (1M). The obtained results are showing generally lower values in case of MB method. The main difference is due to molecular aggregation of MB on the clay surface. AA method is highly sensitive to the presence of CaO. Release of Ca ion from the sample into the solution can limit the saturation of exchange sites by the ammonium ion. This is clearly visible in case of montmorillonite clay. Fe2+ and Mg ions are difficult to move by the ammonium ion because of their ion radius, but in case of MB molecule there is no such restriction in removing them from the exchange sites. MB solution, even in a low concentration (2*10-6M/ml), is showing preferable results in moving the ions from their positions which is already visible after adding a small quantity of solution (25cm3). Both MB-titration and MB-spot test yield similar results and are much simpler methods than AA and they also give other information such as specific surface area (external and internal) whereas AA method only provides information about cations in exchangeable positions. Both methods, methylene blue test and ammonium acetate method, have advantages and disadvantages and differ in their requirements for the sample preparations but in general method selection is depending on the specific application of the given sample. References: - Yukselen, Y. and Kaya, A., Engineering Geology 102 (2008) 38-45 - Czimerova, A., Bujdak, J. and Dohrmann, R., Applied Clay Science 34 (2006) 2-13

The origin of high sulfate concentrations in a coastal plain aquifer, Long Island, New York

USGS Publications Warehouse

Brown, C.J.; Schoonen, M.A.A.

2004-01-01

Ion-exchange batch experiments were run on Cretaceous (Magothy aquifer) clay cores from a nearshore borehole and an inland borehole on Long Island, NY, to determine the origin of high SO42- concentrations in ground water. Desorption batch tests indicate that the amounts of SO 42- released from the core samples are much greater (980-4700 ??g/g of sediment) than the concentrations in ground-water samples. The locally high SO42- concentrations in pore water extracted from cores are consistent with the overall increase in SO 42- concentrations in ground water along Magothy flow paths. Results of the sorption batch tests indicate that SO42- sorption onto clay is small but significant (40-120 ??g/g of sediment) in the low-pH (<5) pore water of clays, and a significant part of the SO42- in Magothy pore water may result from the oxidation of FeS2 by dissolved Fe(III). The acidic conditions that result from FeS2 oxidation in acidic pore water should result in greater sorption of SO42- and other anions onto protonated surfaces than in neutral-pH pore water. Comparison of the amounts of Cl- released from a clay core sample in desorption batch tests (4 ??g/g of sediment) with the amounts of Cl- sorbed to the same clay in sorption tests (3.7-5 ??g/g) indicates that the high concentrations of Cl- in pore water did not originate from connate seawater but were desorbed from sediment that was previously in contact with seawater. Furthermore, a hypothetical seawater transgression in the past is consistent with the observed pattern of sorbed cation complexes in the Magothy cores and could be a significant source of high SO42- concentrations in Magothy ground water.

Sensitive life detection strategies for low-biomass environments: optimizing extraction of nucleic acids adsorbing to terrestrial and Mars analogue minerals.

PubMed

Direito, Susana O L; Marees, Andries; Röling, Wilfred F M

2012-07-01

The adsorption of nucleic acids to mineral matrixes can result in low extraction yields and negatively influences molecular microbial ecology studies, in particular for low-biomass environments on Earth and Mars. We determined the recovery of nucleic acids from a range of minerals relevant to Earth and Mars. Clay minerals, but also other silicates and nonsilicates, showed very low recovery (< 1%). Consequently, optimization of DNA extraction was directed towards clays. The high temperatures and acidic conditions used in some methods to dissolve mineral matrices proved to destruct DNA. The most efficient method comprised a high phosphate solution (P/EtOH; 1 M phosphate, 15% ethanol buffer at pH 8) introduced at the cell-lysing step in DNA extraction, to promote chemical competition with DNA for adsorption sites. This solution increased DNA yield from clay samples spiked with known quantities of cells up to nearly 100-fold. DNA recovery was also enhanced from several mineral samples retrieved from an aquifer, while maintaining reproducible DGGE profiles. DGGE profiles were obtained for a clay sample for which no profile could be generated with the standard DNA isolation protocol. Mineralogy influenced microbial community composition. The method also proved suitable for the recovery of low molecular weight DNA (< 1.5 kb). © 2012 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.

Adsorption of arsenic ions on Brazilian sepiolite: effect of contact time, pH, concentration, and calorimetric investigation.

PubMed

Guerra, Denis L; Batista, Adriano C; da Costa, Paulo C Corrêa; Viana, Rúbia R; Airoldi, Claudio

2010-06-01

The original sepiolite clay mineral has been collected from Amazon region, Brazil. The compound 2-aminomethylpyridine (AMP) was anchored onto Amazon sepiolite surface by heterogeneous route. The natural (SPT) and modified (SPT(AMP)) sepiolite samples were characterized by elemental analysis, SEM, N(2) adsorption, and nuclear magnetic nuclei of (29)Si and (13)C. The well-defined peaks obtained in the (13)C NMR spectrum in the 0-160 ppm region confirmed the attachment of organic functional groups as pendant chains bonded into the porous clay. The ability of these materials to remove As(V) from aqueous solution was followed by a series of adsorption isotherms at room temperature and pH 4.0. The maximum number of moles adsorbed was determined to be 7.26×10(-2) and 11.70×10(-2) mmol g(-1) for SPT and SPT(AMP), respectively. In order to evaluate the clay samples as adsorbents in dynamic system, a glass column was fulfilled with clay samples (1.0 g) and it was fed with 2.0×10(-2) mmol dm(-3) As(V) at pH 4.0. The energetic effects caused by metal cations adsorption were determined through calorimetric titrations. Thermodynamics indicated the existence of favorable conditions for such As(V)-nitrogen interactions. Copyright © 2010. Published by Elsevier Inc.

Chlorination of alumina in kaolinitic clay

NASA Astrophysics Data System (ADS)

Grob, B.; Richarz, W.

1984-09-01

The chlorination of alumina in kaolinitic clay with Cl2 and CO gas mixtures was studied gravimetrically. The effects of the calcination method and of NaCl addition on the reactivity of the clay were examined. Fast reaction rates were achieved only with samples previously exposed to a sulfating treatment. Optimum conditions, with maximum yield and selectivity to A1C13 and minimum SiO2 conversion, were found between 770 and 970 K. At higher temperatures the SiCl4 formed poisons the reactive alumina surface by selective chemisorption with a marked decrease of the reaction rate.

Use of sepiolite as an adsorbent for the removal of copper (II) from industrial waste leachate

NASA Astrophysics Data System (ADS)

Gamze Turan, N.; Ardali, Yüksel

2013-04-01

Land filling is the most common method of disposal of solid waste all over the world. As well as municipal solid waste, industrial wastes, which may contain hazardous substances, are also received by landfills in many countries. Leachate is one of the problems arising from landfills. When water percolates through solid wastes, contaminants are leached into solution. The major concern with the movement of leachate into the subsurface aquifer is the fate of the constituents found in leachate. The fate of heavy metals is the greatest interest in leachate. Several treatment technologies have been developed for eliminating heavy metals recently. Adsorption is one of the most interesting methods that it has been successfully applied for the heavy metal removal. Activated carbons were widely used as adsorbent materials because of their extended surface area, microporous structure, high adsorption capacity and high degree of surface reactivity. However, it is restricted due to its relatively high price, high operation costs, and problems with generation for the industrial scale applications. Recently, more research efforts have been focused on effective sorbents material in order to minimize the processing cost and solve their disposal problems in an environmentally sustainable way. Adsorption of metal ions onto clay minerals has been studied extensively because both metal ions and clays are common components in nature. The cost of clays is relatively low as compared to other alternative adsorbents. Furthermore, the high specific surface area, chemical and mechanical stability, variety of structural and surface properties and higher values of cation exchange capacities make the clays an excellent group of adsorbents. Sepiolite (Si12O30Mg8(OH)4(H2O)4•8H2O) is a natural, fibrous clay mineral with fine microporous channels running parallel to the length of the fibers. The structure of sepiolite, in some aspects, is similar to those of other 2:1 trioctahedral silicates, such as talc, but it has discontinuities and inversion of the silica sheets, which give rise to structural tunnels and blocks. In the inner blocks, all corners of the silica tetrahedral are connected to adjacent blocks, but in the outer blocks, some of the corners are Si atoms bound to hydroxyls (Si-OH). This unique structure allows the penetration of organic and inorganic species into the structure and assigns sepiolite an industrial importance in adsorption. The objective of the present study is to investigate the feasibility of using sepiolite for the adsorptive removal of Cu (II) from the industrial waste leachate. The adsorption capacities and sorption efficiencies are determined. The pseudo first order, the pseudo-second order, Elovich and the intra particle diffusion kinetic models are used to describe the kinetic data to estimate the rate constants. The adsorption of Cu (II) from the aqueous leachate of industrial wastes onto sepiolite was performed using a batch equilibrium technique. At first stage, one-factor-at-a-time experiments were performed to see the individual effects of initial pH, adsorbent dosage and contact time. The adsorption of Cu (II) was favorably influenced by an increase in the adsorbent dosage. The maximum percent removal of Cu (II) were observed at pH>6, and significantly decreased at lower pH value. The optimum contact time is found as 10 min. for the removal of Cu (II). The increment in contact time from 10 min. to 120 min. did not show a significant effect on efficiency. The maximum Cu (II) adsorption efficiencies were obtained at 94.45%. The pseudo second order kinetic model agrees very well with the dynamical behavior for the adsorption of Cu (II) from aqueous leachate of industrial waste onto sepiolite. The results indicate that the use of sepiolite that is locally available and almost free of cost as an adsorbent could be a viable alternative to activated carbon for the removal of Cu (II) ions from aqueous solutions.

A minimalistic microbial food web in an excavated deep subsurface clay rock.

PubMed

Bagnoud, Alexandre; de Bruijn, Ino; Andersson, Anders F; Diomidis, Nikitas; Leupin, Olivier X; Schwyn, Bernhard; Bernier-Latmani, Rizlan

2016-01-01

Clay rocks are being considered for radioactive waste disposal, but relatively little is known about the impact of microbes on the long-term safety of geological repositories. Thus, a more complete understanding of microbial community structure and function in these environments would provide further detail for the evaluation of the safety of geological disposal of radioactive waste in clay rocks. It would also provide a unique glimpse into a poorly studied deep subsurface microbial ecosystem. Previous studies concluded that microorganisms were present in pristine Opalinus Clay, but inactive. In this work, we describe the microbial community and assess the metabolic activities taking place within borehole water. Metagenomic sequencing and genome-binning of a porewater sample containing suspended clay particles revealed a remarkably simple heterotrophic microbial community, fueled by sedimentary organic carbon, mainly composed of two organisms: a Pseudomonas sp. fermenting bacterium growing on organic macromolecules and releasing organic acids and H2, and a sulfate-reducing Peptococcaceae able to oxidize organic molecules to CO(2). In Opalinus Clay, this microbial system likely thrives where pore space allows it. In a repository, this may occur where the clay rock has been locally damaged by excavation or in engineered backfills. © FEMS 2015. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

The effect of clay nanoparticleon the retention and attack of drywood termite (Cryptotermes cynocephalus Light).

NASA Astrophysics Data System (ADS)

Alex, T.; Winarni, B.; Kusuma, I. W.; Arung, E. T.; Budiarso, E.

2018-04-01

The aplication of clay nanoparticles as wood preservative was intended to examine its resistant to infestation of drywood termite (C. cynocephalusLight). Loam was crushed into small pieces as clay nanoparticles, which was used as wood preservative that was soluble in water. The material was dissolved with water in a given concentration and put it into anggerung (Trema orientalis), white meranti (Shorea bracteolata) and sengon (Paraseriehthes falcataria) by full cell method or impregnation. The tested samples were preserved by clay nanoparticles at the air pressure 60 psi for 2 hours and then furnace-dried, and tested by infestation of drywood termites. Results of the research showed that mortality of the drywood termites on those three preserved woods with clay nanoparticles by concentration of 2.5% and 5%, which reached 96.4% and 100% on average, respectively, in comparison without preservation by average mortality value was 27.4%. The highest retention of clay nanoparticle was 24.89 kg.m3 was obtained by concentration of 5% for white merantiand the lowest was 9.32 kg.m3 by concentration of 2.5% for anggerung. The application of clay nanoparticle as effective wood preservative against the infestation of drywood termite by concentration of 5% has been proven by mortality 100%.

Kisameet Glacial Clay: an Unexpected Source of Bacterial Diversity

PubMed Central

Svensson, Sarah L.; Behroozian, Shekooh; Xu, Wanjing; Surette, Michael G.; Li, Loretta

2017-01-01

ABSTRACT Widespread antibiotic resistance among bacterial pathogens is providing the impetus to explore novel sources of antimicrobial agents. Recently, the potent antibacterial activity of certain clay minerals has stimulated scientific interest in these materials. One such example is Kisameet glacial clay (KC), an antibacterial clay from a deposit on the central coast of British Columbia, Canada. However, our understanding of the active principles of these complex natural substances is incomplete. Like soils, clays may possess complex mixtures of bacterial taxa, including the Actinobacteria, a clade known to be rich in antibiotic-producing organisms. Here, we present the first characterization of both the microbial and geochemical characteristics of a glacial clay deposit. KC harbors surprising bacterial species richness, with at least three distinct community types. We show that the deposit has clines of inorganic elements that can be leached by pH, which may be drivers of community structure. We also note the prevalence of Gallionellaceae in samples recovered near the surface, as well as taxa that include medically or economically important bacteria such as Actinomycetes and Paenibacillus. These results provide insight into the microbial taxa that may be the source of KC antibacterial activity and suggest that natural clays may be rich sources of microbial and molecular diversity. PMID:28536287

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

PubMed Central

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

2013-01-01

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

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

PubMed

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

2013-01-01

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

Organofunctionalized Amazon smectite for dye removal from aqueous medium--kinetic and thermodynamic adsorption investigations.

PubMed

Guerra, Denis L; Silva, Weber L L; Oliveira, Helen C P; Viana, Rúbia R; Airoldi, Claudio

2011-02-15

The objective of this study is to examine the adsorption behavior of Sumifix Brilliant Orange 3R textile dye from aqueous solution on smectite sample, an abundant Amazon clay. The original smectite clay mineral has been collected from Amazon region, Brazil. The compound 2-aminomethylpyridine was anchored onto smectite surface by heterogeneous route. The ability of these materials to remove the Sumifix Brilliant Orange 3R textile dye from aqueous solution was followed by a series of adsorption isotherms, using a batchwise process. The maximum number of moles adsorbed was determined to be 1.26 and 2.07 mmol g(-1) for natural and modified clay samples, respectively. The energetic effects caused by dye cations adsorption were determined through calorimetric titrations. Thermodynamics indicated the existence of favorable conditions for such dye-nitrogen interactions. Copyright © 2010. Published by Elsevier B.V.

Gas breakthrough and emission through unsaturated compacted clay in landfill final cover

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ng, C.W.W.; Chen, Z.K.; Coo, J.L.

Highlights: • Explore feasibility of unsaturated clay as a gas barrier in landfill cover. • Gas breakthrough pressure increases with clay thickness and degree of saturation. • Gas emission rate decreases with clay thickness and degree of saturation. • A 0.6 m-thick clay layer may be sufficient to meet gas emission rate limit. - Abstract: Determination of gas transport parameters in compacted clay plays a vital role for evaluating the effectiveness of soil barriers. The gas breakthrough pressure has been widely studied for saturated swelling clay buffer commonly used in high-level radioactive waste disposal facility where the generated gas pressuremore » is very high (in the order of MPa). However, compacted clay in landfill cover is usually unsaturated and the generated landfill gas pressure is normally low (typically less than 10 kPa). Furthermore, effects of clay thickness and degree of saturation on gas breakthrough and emission rate in the context of unsaturated landfill cover has not been quantitatively investigated in previous studies. The feasibility of using unsaturated compacted clay as gas barrier in landfill covers is thus worthwhile to be explored over a wide range of landfill gas pressures under various degrees of saturation and clay thicknesses. In this study, to evaluate the effectiveness of unsaturated compacted clay to minimize gas emission, one-dimensional soil column tests were carried out on unsaturated compacted clay to determine gas breakthrough pressures at ultimate limit state (high pressure range) and gas emission rates at serviceability limit state (low pressure range). Various degrees of saturation and thicknesses of unsaturated clay sample were considered. Moreover, numerical simulations were carried out using a coupled gas–water flow finite element program (CODE-BRIGHT) to better understand the experimental results by extending the clay thickness and varying the degree of saturation to a broader range that is typical at different climate conditions. The results of experimental study and numerical simulation reveal that as the degree of saturation and thickness of clay increase, the gas breakthrough pressure increases but the gas emission rate decreases significantly. Under a gas pressure of 10 kPa (the upper bound limit of typical landfill gas pressure), a 0.6 m or thicker compacted clay is able to prevent gas breakthrough at degree of saturation of 60% or above (in humid regions). Furthermore, to meet the limit of gas emission rate set by the Australian guideline, a 0.6 m-thick clay layer may be sufficient even at low degree of saturation (i.e., 10% like in arid regions)« less

AAPG-SEPM Gulf of Mexico type-well project

DOE Office of Scientific and Technical Information (OSTI.GOV)

Slatt, R.M.; Christopher, R.C.; Katz, B.J.

1992-12-01

In 1991, The American Association of Petroleum Geologists (AAPG) published a regional stratigraphic cross section and accompanying seismic line that extends from the south flank of the Ouachita tectonic belt in southern Arkansas (lat. 34.15'N) to south of the 28th parallel in the High Island area, South Addition Block of offshore Gulf of Mexico. The cross section shows chronostratigraphic correlations, lithostratigraphy, and generalized structural relations common to the central Gulf Coast and mid-continent region. The section has been published in three large sheets, each representing approximately 425 statue mi of geographic coverage. As an outgrowth of this project, AAPG, jointlymore » with the Society of Sedimentary Geology (SEPM), organized and sponsored a project through their respective Research Committees on biostratigraphic, lithostratigraphic, and organic geochemical analyses of cuttings from key wells tied to the cross section. Separate splits of samples were sent to volunteers for the following analyses: (1) binocular microscope lithology analysis, (2) detailed biostratigraphy, (3) organic geochemistry, and (4) clay mineralogy by x-ray diffraction (XRD).« less

Effects of preparation methods on the structure and mechanical properties of wet conditioned starch/montmorillonite nanocomposite films.

PubMed

Müller, Péter; Kapin, Éva; Fekete, Erika

2014-11-26

TPS/Na-montmorillonite nanocomposite films were prepared by solution and melt blending. Clay content changed between 0 and 25 wt% based on the amount of dry starch. Structure, tensile properties, and water content of wet conditioned films were determined as a function of clay content. Intercalated structure and VH-type crystallinity of starch were found for all the nanocomposites independently of clay and plasticizer content or preparation method, but at larger than 10 wt% clay content nanocomposites prepared by melt intercalation contained aggregated particles as well. In spite of the incomplete exfoliation clay reinforces TPS considerably. Preparation method has a strong influence on mechanical properties of wet conditioned films. Mechanical properties of the conditioned samples prepared by solution homogenization are much better than those of nanocomposites prepared by melt blending. Water, which was either adsorbed or bonded in the composites in conditioning or solution mixing process, respectively, has different effect on mechanical properties. Copyright © 2014 Elsevier Ltd. All rights reserved.

Soil texture analysis revisited: Removal of organic matter matters more than ever

PubMed Central

Schjønning, Per; Watts, Christopher W.; Christensen, Bent T.; Munkholm, Lars J.

2017-01-01

Exact estimates of soil clay (<2 μm) and silt (2–20 μm) contents are crucial as these size fractions impact key soil functions, and as pedotransfer concepts based on clay and silt contents are becoming increasingly abundant. We examined the effect of removing soil organic matter (SOM) by H2O2 before soil dispersion and determination of clay and silt. Soil samples with gradients in SOM were retrieved from three long-term field experiments each with uniform soil mineralogy and texture. For soils with less than 2 g C 100 g-1 minerals, clay estimates were little affected by SOM. Above this threshold, underestimation of clay increased dramatically with increasing SOM content. Silt contents were systematically overestimated when SOM was not removed; no lower SOM threshold was found for silt, but the overestimation was more pronounced for finer textured soils. When exact estimates of soil particles <20 μm are needed, SOM should always be removed before soil dispersion. PMID:28542416

Soil texture analysis revisited: Removal of organic matter matters more than ever.

PubMed

Jensen, Johannes Lund; Schjønning, Per; Watts, Christopher W; Christensen, Bent T; Munkholm, Lars J

2017-01-01

Exact estimates of soil clay (<2 μm) and silt (2-20 μm) contents are crucial as these size fractions impact key soil functions, and as pedotransfer concepts based on clay and silt contents are becoming increasingly abundant. We examined the effect of removing soil organic matter (SOM) by H2O2 before soil dispersion and determination of clay and silt. Soil samples with gradients in SOM were retrieved from three long-term field experiments each with uniform soil mineralogy and texture. For soils with less than 2 g C 100 g-1 minerals, clay estimates were little affected by SOM. Above this threshold, underestimation of clay increased dramatically with increasing SOM content. Silt contents were systematically overestimated when SOM was not removed; no lower SOM threshold was found for silt, but the overestimation was more pronounced for finer textured soils. When exact estimates of soil particles <20 μm are needed, SOM should always be removed before soil dispersion.

Reuse of industrial sludge as construction aggregates.

PubMed

Tay, J H; Show, K Y; Hong, S Y

2001-01-01

Industrial wastewater sludge and dredged marine clay are high volume wastes that needed enormous space at landfill disposal sites. Due to the limitation of land space, there is an urgent need for alternative disposal methods for these two wastes. This study investigates the possibility of using the industrial sludge in combination with marine clay as construction aggregates. Different proportions of sludge and clay were made into round and angular aggregates. It was found that certain mix proportions could provide aggregates of adequate strength, comparable to that of conventional aggregates. Concrete samples cast from the sludge-clay aggregates yield compressive strengths in the range of 31.0 to 39.0 N/mm2. The results showed that the round aggregates of 100% sludge and the crush aggregates of sludge with up to 20% clay produced concrete of compressive strengths which are superior to that of 38.0 N/mm2 for conventional aggregate. The study indicates that the conversion of high volume wastes into construction materials is a potential option for waste management.

pH profile of the adsorption of nucleotides onto montmorillonite. I - Selected homoionic clays

NASA Technical Reports Server (NTRS)

Lawless, J. G.; Church, F. M.; Mazzurco, J.; Banin, A.; Huff, R.; Kao, J.; Cook, A.; Lowe, T.; Orenberg, J. B.; Edelson, E.

1985-01-01

The effect of pH and adsorbed ions on the adsorption of purine and pyrimidine nucleotides on montmorillonite clay was studied experimentally. The specific nucleotides examined were: 5 prime-AMP; 3-prime AMP; and 5 prime-CMP. The pH of the clay samples was adjusted to various levels in the 2-12 pH range using microliter volumes of concentrated acid (1N HCl) and base (1NHNaOH). It was found that preferential adsorption among nulceotides was dependent on the pH level and on the characteristics of the substituted metal cation and anion exchange mechanisms. Below pH 4, adsorption was attributed to cation and anion exchange mechanisms. Above pH 4, however, adsorption was attributed to the complexation mechanisms occurring between the metal cations in the clay exchange site and in the biomolecule. The possible role of homoionic clays in the concentration mechanisms of biomonomers in the prebiotic environment is discussed.

Five-Year-Old Cottonwood Plantation on a Clay Site: Growth, Yield, and Soil Properties

Treesearch

R. M. Krinard; H. E. Kennedy

1980-01-01

A random sample of Stoneville select cottonwood (Populus deltoides Bartr.) clones planted on recent old-field clay soils at 12- by 12- foot spacing averaged 75-percent survival after five years. The growth and yield was about half that expected from planted cottonwood on medium-textured soils. Soil moisture analysis showed more height growth in years...

Detection and cultivation of indigenous microorganisms in Mesozoic claystone core samples from the Opalinus Clay Formation (Mont Terri Rock Laboratory)

NASA Astrophysics Data System (ADS)

Mauclaire, L.; McKenzie, J. A.; Schwyn, B.; Bossart, P.

Although microorganisms have been isolated from various deep-subsurface environments, the persistence of microbial activity in claystones buried to great depths and on geological time scales has been poorly studied. The presence of in-situ microbial life in the Opalinus Clay Formation (Mesozoic claystone, 170 million years old) at the Mont Terri Rock Laboratory, Canton Jura, Switzerland was investigated. Opalinus Clay is a host rock candidate for a radioactive waste repository. Particle tracer tests demonstrated the uncontaminated nature of the cored samples, showing their suitability for microbiological investigations. To determine whether microorganisms are a consistent and characteristic component of the Opalinus Clay Formation, two approaches were used: (i) the cultivation of indigenous micoorganisms focusing mainly on the cultivation of sulfate-reducing bacteria, and (ii) the direct detection of molecular biomarkers of bacteria. The goal of the first set of experiments was to assess the presence of cultivable microorganisms within the Opalinus Clay Formation. After few months of incubation, the number of cell ranged from 0.1 to 2 × 10 3 cells ml -1 media. The microorganisms were actively growing as confirmed by the observation of dividing cells, and detection of traces of sulfide. To avoid cultivation bias, quantification of molecular biomarkers (phospholipid fatty acids) was used to assess the presence of autochthonous microorganisms. These molecules are good indicators of the presence of living cells. The Opalinus Clay contained on average 64 ng of PLFA g -1 dry claystone. The detected microbial community comprises mainly Gram-negative anaerobic bacteria as indicated by the ratio of iso/anteiso phospholipids (about 2) and the detection of large amount of β-hydroxy substituted fatty acids. The PLFA composition reveals the presence of specific functional groups of microorganisms in particular sulfate-reducing bacteria ( Desulfovibrio, Desulfobulbus, and Desulfobacter). This study demonstrates that microorganisms are a characteristic component of the unperturbed Opalinus Clay Formation.

Comparative characterization of the quaternary deposits of Northwest Peninsular Malaysia by wash boring and CPTU site investigation methods

NASA Astrophysics Data System (ADS)

Selamat, Mohamad R.; Rosli, Ros N.; Ramli, Muhd H.; Azmi, Mastura; Kumaravelu, Prakash; Govindasamy, Darvintharen

2017-10-01

A site investigation by wash boring method was carried out in the compound of the Engineering Campus, Universiti Sains Malaysia, in Northwest Peninsular Malaysia. The subsurface soils of the region are known to be comprised of quaternary deposits including the prominent marine clays of the Gula formation. The conventional Standard Penetration Test, or SPT, was carried out for every 1.5m depth. The 18 disturbed samples collected were tested for grain size distribution, Atterberg limits, and specific gravity; and categorized according to the unified soil classification system. The results indicate low SPT numbers, or SPTN, i.e. SPTN<4 for depths lesser than 10m, slightly high SPTN, i.e. 4≤SPTN≤8 for depths between 10 and 12m, and very high SPTN, i.e. SPTN>8 for depths deeper than 12m. Samples from shallower than 12m were mostly classified as low plasticity clay, or CL, which represents the soft marine clay while the underlying materials were mostly sands, namely poorly graded sand, or SP, silty sand, or SM, clayey sand, or SC, and well graded sand, or SW. Another site investigation by the CPTU method was also carried out 5m from the wash boring position, penetrating the entire soft clay stratum, thus giving another marine clay characterization in addition to the one given by the first method. The CPTU results generally gave SPTN≤2 for depths lesser than 8m, 2≤;SPTN≤4 for depths between 8 and 12m, and SPTN=23 at 12.5m, where the CPTU test terminated. The CPTU method classified the soft materials as sensitive fine grains, clays, and clayey silts to silty clays. Thus the CPTU results did not agree very well with the conventional wash boring SPT results in terms of the SPTN obtained. Nevertheless both methods equally identified the prominent presence of the soft marine clay stratum in the top 12.5m and the underlying strong sandy bed with higher bearing capacity values.

Behavior of nonplastic silty soils under cyclic loading.

PubMed

Ural, Nazile; Gunduz, Zeki

2014-01-01

The engineering behavior of nonplastic silts is more difficult to characterize than is the behavior of clay or sand. Especially, behavior of silty soils is important in view of the seismicity of several regions of alluvial deposits in the world, such as the United States, China, and Turkey. In several hazards substantial ground deformation, reduced bearing capacity, and liquefaction of silty soils have been attributed to excess pore pressure generation during dynamic loading. In this paper, an experimental study of the pore water pressure generation of silty soils was conducted by cyclic triaxial tests on samples of reconstituted soils by the slurry deposition method. In all tests silty samples which have different clay percentages were studied under different cyclic stress ratios. The results have showed that in soils having clay content equal to and less than 10%, the excess pore pressure ratio buildup was quicker with an increase in different cyclic stress ratios. When fine and clay content increases, excess pore water pressure decreases constant cyclic stress ratio in nonplastic silty soils. In addition, the applicability of the used criteria for the assessment of liquefaction susceptibility of fine grained soils is examined using laboratory test results.

Behavior of Nonplastic Silty Soils under Cyclic Loading

PubMed Central

Ural, Nazile; Gunduz, Zeki

2014-01-01

The engineering behavior of nonplastic silts is more difficult to characterize than is the behavior of clay or sand. Especially, behavior of silty soils is important in view of the seismicity of several regions of alluvial deposits in the world, such as the United States, China, and Turkey. In several hazards substantial ground deformation, reduced bearing capacity, and liquefaction of silty soils have been attributed to excess pore pressure generation during dynamic loading. In this paper, an experimental study of the pore water pressure generation of silty soils was conducted by cyclic triaxial tests on samples of reconstituted soils by the slurry deposition method. In all tests silty samples which have different clay percentages were studied under different cyclic stress ratios. The results have showed that in soils having clay content equal to and less than 10%, the excess pore pressure ratio buildup was quicker with an increase in different cyclic stress ratios. When fine and clay content increases, excess pore water pressure decreases constant cyclic stress ratio in nonplastic silty soils. In addition, the applicability of the used criteria for the assessment of liquefaction susceptibility of fine grained soils is examined using laboratory test results. PMID:24672343

Distribution of trace elements in drilling chip samples around a roll-type uranium deposit, San Juan Basin, New Mexico

USGS Publications Warehouse

Day, H.C.; Spirakis, C.S.; Zech, R.S.; Kirk, A.R.

1983-01-01

Chip samples from rotary drilling in the vicinity of a roll-type uranium deposit in the southwestern San Juan Basin were split into a whole-washed fraction, a clay fraction, and a heavy mineral concentrate fraction. Analyses of these fractions determined that cutting samples could be used to identify geochemical halos associated with this ore deposit. In addition to showing a distribution of selenium, uranium, vanadium, and molybdenum similar to that described by Harshman (1974) in uranium roll-type deposits in Wyoming, South Dakota, and Texas, the chemical data indicate a previously unrecognized zinc anomaly in the clay fraction downdip of the uranium ore.

Necessity of purification during bacterial DNA extraction with environmental soils

PubMed Central

Choi, Jung-Hyun

2017-01-01

Complexity and heterogeneity of soil samples have often implied the inclusion of purification steps in conventional DNA extraction for polymerase chain reaction (PCR) assays. Unfortunately the purification steps are also time and labor intensive. Therefore the necessity of DNA purification was re-visited and investigated for a variety of environmental soil samples that contained various amounts of PCR inhibitors. Bead beating and centrifugation was used as the baseline (without purification) method for DNA extraction. Its performance was compared with that of conventional DNA extraction kit (with purification). The necessity criteria for DNA purification were established with environmental soil samples. Using lysis conditions at 3000 rpm for 3 minutes with 0.1 mm glass beads, centrifugation time of 10 minutes and 1:10 dilution ratio, the baseline method outperformed conventional DNA extraction on cell seeded sand samples. Further investigation with PCR inhibitors (i.e., humic acids, clay, and magnesium [Mg]) showed that sand samples containing less than 10 μg/g humic acids and 70% clay may not require purifications. Interestingly, the inhibition pattern of Mg ion was different from other inhibitors due to the complexation interaction of Mg ion with DNA fragments. It was concluded that DNA extraction method without purification is suitable for soil samples that have less than 10 μg/g of humic acids, less than 70% clay content and less than 0.01% Mg ion content. PMID:28793754

Permeability of Granite Including Macro-Fracture Naturally Filled with Fine-Grained Minerals

NASA Astrophysics Data System (ADS)

Nara, Yoshitaka; Kato, Masaji; Niri, Ryuhei; Kohno, Masanori; Sato, Toshinori; Fukuda, Daisuke; Sato, Tsutomu; Takahashi, Manabu

2018-03-01

Information on the permeability of rock is essential for various geoengineering projects, such as geological disposal of radioactive wastes, hydrocarbon extraction, and natural hazard risk mitigation. It is especially important to investigate how fractures and pores influence the physical and transport properties of rock. Infiltration of groundwater through the damage zone fills fractures in granite with fine-grained minerals. However, the permeability of rock possessing a fracture naturally filled with fine-grained mineral grains has yet to be investigated. In this study, the permeabilities of granite samples, including a macro-fracture filled with clay and a mineral vein, are investigated. The permeability of granite with a fine-grained mineral vein agrees well with that of the intact sample, whereas the permeability of granite possessing a macro-fracture filled with clay is lower than that of the macro-fractured sample. The decrease in the permeability is due to the filling of fine-grained minerals and clay in the macro-fracture. It is concluded that the permeability of granite increases due to the existence of the fractures, but decreases upon filling them with fine-grained minerals.

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

USGS Publications Warehouse

Crowley, James K.; Vergo, Norma

1988-01-01

Near-infrared (NIR) reflectance spectra for mixtures of ordered kaolinite and ordered dickite have been found to simulate the spectral response of disordered kaolinite. The amount of octahedral vacancy disorder in nine disordered kaolinite samples was estimated by comparing the sample 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. The ordered kaolinite and dickite samples used in the reference mixtures were carefully selected to avoid undesirable particle size effects that could bias the spectral results.NIR spectra were also recorded for laboratory mixtures of ordered kaolinite and halloysite to assess whether the spectra could be potentially useful for determining mineral proportions in natural physical mixtures of these two clays. Although the kaolinite-halloysite proportions could only be roughly estimated from the mixture spectra, the halloysite component was evident even when halloysite was present in only minor amounts. A similar approach using NIR spectra for laboratory mixtures may have applications in other studies of natural clay mixtures.

Can Transport of Saharan Dust Explain Extensive Clay Deposits in the Amazon Basin? A Test Using Radiogenic Isotopes

NASA Astrophysics Data System (ADS)

Andreae, M. O.; Abouchami, W.; Näthe, K.; Kumar, A.; Galer, S. J.; Jochum, K. P.; Williams, E.; Horbe, A. M.; Rosa, J. W.; Adams, D. K.; Balsam, W. R.

2012-12-01

The Bodélé Depression, located in the Southern Sahara, is a huge source of atmospheric dust and thus an important element in biogeochemical cycles and the radiative budget of Earth's atmosphere. Previous studies have shown that Saharan dust transport across the Atlantic acts as an important source of mineral nutrients to the Amazon rainforest. The Belterra Clay, which outcrops extensively across the Amazon Basin in Brazil, has been proposed to result from dry deposition of African dusts. We have investigated this hypothesis by measuring the radiogenic isotopic composition (Sr, Nd and Pb) of a suite of samples from the Belterra Clay, the Bodélé Depression, dusts deposits collected at various locations along the airmass transport trajectory, as well as loess from the Cape Verde Islands. Radiogenic isotope systems are powerful tracers of provenance and can be used to fingerprint dust sources and atmospheric transport patterns. Our results identify distinct isotopic signatures in the Belterra Clay samples and the African sources. The Belterra Clay display radiogenic Sr and Pb isotope ratios associated with non-radiogenic Nd isotope signatures. In contrast, Bodélé samples and dusts deposits show lower Pb isotope ratios, variable 87Sr/86Sr, and relatively homogeneous Nd isotopic compositions, albeit more radiogenic than those of the Belterra Clay. Our data show unambiguously that the Belterra Clay is not derived from African dust deposition, nor from the Andean chain, as originally suggested by W. Sombroek. Rather, isotopic compositions and Nd model ages are consistent with simple mixing of Archean and younger Proterozoic terranes within the Amazon Basin as a result of weathering and erosion under humid tropical conditions. Whether Saharan dusts contribute to the fertilization in the Amazon Basin cannot be ruled out, however, since the African dust isotopic signature is expected to be entirely overprinted by local sources. Radiogenic isotope data obtained on aerosol filters collected in the US Virgin Islands and Tobago are similar to those of aerosols from Mali, demonstrating that the African dust isotope signal is detectable and transported as far as Central and South America. Thus, while it appears undeniable that Saharan dust reaches the Amazon Basin, its importance for overall soil fertility requires a careful assessment of the dust budget versus bedrock weathering rates for key nutrient elements.

Maintenance Resources by Building Use for Installations in Germany

DTIC Science & Technology

1991-11-01

125125. .01 0531140 STEEL ( INSULATED ) PAINTED INTERIOR DOOR 124956. .01 0432710 DOUBLE PANE STEEL FIXED WNDW. 1ST FLOOR 124922. .01 1131200 QUARTZ...FINISH 8507. .00 0535400 ALUMINUM DOUBLE ROLL-UP INTERIOR DOOR 8490. .00 0424310 ALUMINUM LOUVERED EXT DOORS 7973. .00 0421340 STEEL ( INSUL CORE) UNPUT...H.P. 0831130 20 1.09 Clay Block (Painted) Interior 0612200 21 1.08 Wall Sink. Stainless Steel 0811F00 22 1.03 Steel (Painted) Exterior Door 0421210 23

The U.S. M-16 rifle versus the Russian AK-47 rifle. A comparison of terminal ballistics.

PubMed

Swan, K G; Swan, R C; Levine, M G; Rocko, J M

1983-09-01

The standard U.S. military rifle (M-16) is substantially more destructive than its Russian counterpart (AK-47) when fired at short range into clay blocks, despite the fact that the AK-47 is of larger caliber and fires a much heavier bullet with a kinetic energy (muzzle) 25% greater when compared to the M-16. The decisive factor is the 40% greater muzzle velocity of the M-16.

Effect of confining pressure on diffusion coefficients in clay-rich, low-permeability sedimentary rocks.

PubMed

Xiang, Y; Al, T; Mazurek, M

2016-12-01

The effect of confining pressure (CP) on the diffusion of tritiated-water (HTO) and iodide (I - ) tracers through Ordovician rocks from the Michigan Basin, southwestern Ontario, Canada, and Opalinus Clay from Schlattingen, Switzerland was investigated in laboratory experiments. Four samples representing different formations and lithologies in the Michigan Basin were studied: Queenston Formation shale, Georgian Bay Formation shale, Cobourg Formation limestone and Cobourg Formation argillaceous limestone. Estimated in situ vertical stresses at the depths from which the samples were retrieved range from 12.0 to 17.4MPa (Michigan Basin) and from 21 to 23MPa (Opalinus Clay). Effective diffusion coefficients (D e ) were determined in through-diffusion experiments. With HTO tracer, applying CP resulted in decreases in D e of 12.5% for the Queenston Formation shale (CP max =12MPa), 30% for the Georgian Bay Formation shale (15MPa), 34% for the Cobourg Formation limestone (17.4MPa), 31% for the Cobourg Formation argillaceous limestone (17.4MPa) and 43-46% for the Opalinus Clay (15MPa). Decreases in D e were larger for the I - tracer: 13.8% for the Queenston shale, 42% for the Georgian Bay shale, 50% for the Cobourg Formation limestone, 55% for the Cobourg Formation argillaceous limestone and 63-68% for the Opalinus Clay. The tracer-specific nature of the response is attributed to an increasing influence of anion exclusion as the pore size decreases at higher CP. Results from the shales (including Opalinus Clay) indicate that the pressure effect on D e can be represented by a linear relationship between D e and ln(CP), which provides valuable predictive capability. The nonlinearity results in a relatively small change in D e at high CP, suggesting that it is not necessary to apply the exact in situ pressure conditions in order to obtain a good estimate of the in situ diffusion coefficient. Most importantly, the CP effect on shale is reversible (±12%) suggesting that, for argillaceous rocks, it is possible to obtain D e values that are representative of the in-situ condition by conducting measurements on re-pressurized samples that were obtained with standard drilling practices. This may not be the case for brittle rock samples as the results from limestone suggest that irreversible damage occurred during the pressure cycling. Copyright © 2016 Elsevier B.V. All rights reserved.

The nature of porosity in organic-rich mudstones of the Upper Jurassic Kimmeridge Clay Formation, North Sea, offshore United Kingdom

USGS Publications Warehouse

Fishman, Neil S.; Hackley, Paul C.; Lowers, Heather; Hill, Ronald J.; Egenhoff, Sven O.; Eberl, Dennis D.; Blum, Alex E.

2012-01-01

Analyses of organic-rich mudstones from wells that penetrated the Upper Jurassic Kimmeridge Clay Formation, offshore United Kingdom, were performed to evaluate the nature of both organic and inorganic rock constituents and their relation to porosity in this world-class source rock. The formation is at varying levels of thermal maturity, ranging from immature in the shallowest core samples to mature in the deepest core samples. The intent of this study was to evaluate porosity as a function of both organic macerals and thermal maturity. At least four distinct types of organic macerals were observed in petrographic and SEM analyses and they all were present across the study area. The macerals include, in decreasing abundance: 1) bituminite admixed with clays; 2) elongate lamellar masses (alginite or bituminite) with small quartz, feldspar, and clay entrained within it; 3) terrestrial (vitrinite, fusinite, semifusinite) grains; and 4) Tasmanites microfossils. Although pores in all maceral types were observed on ion-milled surfaces of all samples, the pores (largely nanopores with some micropores) vary as a function of maceral type. Importantly, pores in the macerals do not vary systematically as a function of thermal maturity, insofar as organic pores are of similar size and shape in both the immature and mature Kimmeridge rocks. If any organic pores developed during the generation of hydrocarbons, they were apparently not preserved, possibly because of the highly ductile nature of much of the rock constituents of Kimmeridge mudstones (clays and organic material). Inorganic pores (largely micropores with some nanopores) have been observed in all Kimmeridge mudstones. These pores, particularly interparticle (i.e., between clay platelets), and intraparticle (i.e., in framboidal pyrite, in partially dissolved detrital K-feldspar, and in both detrital and authigenic dolomite) are noteworthy because they compose much of the observable porosity in the shales in both immature and mature samples. The absence of a systematic increase in organic porosity as a function of either maceral type or thermal maturity indicates that such porosity was probably unrelated to hydrocarbon generation. Instead, much of the porosity within mudstones of the Kimmeridge appears to be largely intraparticle and interparticle (adjacent to inorganic constituents), so the petroleum storage potential in these organic-rich mudstones largely resides in inorganic pores.

Morphology of the pore space in claystones - evidence from BIB/FIB ion beam sectioning and cryo-SEM observations

NASA Astrophysics Data System (ADS)

Desbois, G.; Urai, J. L.; Kukla, P. A.

2009-12-01

Mudrocks and clay-rich fault gouges are important mechanical elements in the Earth’s crust and form seals for crustal fluids such as groundwater and hydrocarbons. Other fields of interest are the storage of anthropogenic carbon dioxide and radioactive waste in geologic formations. In addition, coupled flows, capillary processes, and associated deformation are of importance in many applied fields. A key factor to understanding these processes is a detailed understanding of the morphology of the pore space. Classic studies of porosity in fine grained materials are performed on dried or freeze dried samples and include metal injection methods, magnetic susceptibility measurement, SEM and TEM imaging, neutron scattering, NMR spectroscopy, and ESEM. Confocal microscopy and X-ray tomography are used to image porosity in coarse grained sediments but the resolution of these techniques is not sufficient at present for applications to mudrocks or clay-rich fault gouges. Therefore, observations and interpretations remain difficult because none of these approaches is able to directly describe the in-situ porosity at the pore scale. In addition, some methods require dried samples in which the natural structure of pores may have been damaged to some extent due to desiccation and dehydration of the clay minerals. A recently developed alternative is to study wet samples using a cryo-SEM, which allows stabilization of wet media at cryo-temperature, in-situ sample preparation by ion beam cross-sectioning (BIB, FIB) and observations of the stabilized microstructure at high resolution. We report on a study of Boom clay from a proposed disposal site of radioactive waste (Mol site, Belgium) using cryo-SEM at cryogenic temperature, with ion beam cross-sectioning to prepare smooth, damage free surfaces. Pores commonly have crack-like tips, preferred orientation parallel to bedding and power law size distribution. We define a number of pore types depending on shape and location in the microstructure. 3-D reconstruction by serial cross-sectioning shows 3-D connectivity of the pore space. These findings offer a new insight into the morphology of pores down to nano-scale and provide the basis for microstructure-based models of transport in clays. SEM image (SE) of a Broad Ion Beam polished cross-section performed on dry Boom clay (Mol site, Belgium) showing the 2D apparent porosity (26.3%). The cross-section is perpendicular to the bedding.

Effect of bovine manure on fecal coliform attachment to soil and soil particles of different sizes.

PubMed

Guber, Andrey K; Pachepsky, Yakov A; Shelton, Daniel R; Yu, Olivia

2007-05-01

Manure-borne bacteria can be transported in runoff as free cells, cells attached to soil particles, and cells attached to manure particles. The objectives of this work were to compare the attachment of fecal coliforms (FC) to different soils and soil fractions and to assess the effect of bovine manure on FC attachment to soil and soil fractions. Three sand fractions of different sizes, the silt fraction, and the clay fraction of loam and sandy clay loam soils were separated and used along with soil samples in batch attachment experiments with water-FC suspensions and water-manure-FC suspensions. In the absence of manure colloids, bacterial attachment to soil, silt, and clay particles was much higher than the attachment to sand particles having no organic coating. The attachment to the coated sand particles was similar to the attachment to silt and clay. Manure colloids in suspensions decreased bacterial attachment to soils, clay and silt fractions, and coated sand fractions, but did not decrease the attachment to sand fractions without the coating. The low attachment of bacteria to silt and clay particles in the presence of manure colloids may cause predominantly free-cell transport of manure-borne FC in runoff.

Transfer zones in listric normal fault systems

NASA Astrophysics Data System (ADS)

Bose, Shamik

Listric normal faults are common in passive margin settings where sedimentary units are detached above weaker lithological units, such as evaporites or are driven by basal structural and stratigraphic discontinuities. The geometries and styles of faulting vary with the types of detachment and form landward and basinward dipping fault systems. Complex transfer zones therefore develop along the terminations of adjacent faults where deformation is accommodated by secondary faults, often below seismic resolution. The rollover geometry and secondary faults within the hanging wall of the major faults also vary with the styles of faulting and contribute to the complexity of the transfer zones. This study tries to understand the controlling factors for the formation of the different styles of listric normal faults and the different transfer zones formed within them, by using analog clay experimental models. Detailed analyses with respect to fault orientation, density and connectivity have been performed on the experiments in order to gather insights on the structural controls and the resulting geometries. A new high resolution 3D laser scanning technology has been introduced to scan the surfaces of the clay experiments for accurate measurements and 3D visualizations. Numerous examples from the Gulf of Mexico have been included to demonstrate and geometrically compare the observations in experiments and real structures. A salt cored convergent transfer zone from the South Timbalier Block 54, offshore Louisiana has been analyzed in detail to understand the evolutionary history of the region, which helps in deciphering the kinematic growth of similar structures in the Gulf of Mexico. The dissertation is divided into three chapters, written in a journal article format, that deal with three different aspects in understanding the listric normal fault systems and the transfer zones so formed. The first chapter involves clay experimental models to understand the fault patterns in divergent and convergent transfer zones. Flat base plate setups have been used to build different configurations that would lead to approaching, normal offset and overlapping faults geometries. The results have been analyzed with respect to fault orientation, density, connectivity and 3D geometry from photographs taken from the three free surfaces and laser scans of the top surface of the clay cake respectively. The second chapter looks into the 3D structural analysis of the South Timbalier Block 54, offshore Louisiana in the Gulf of Mexico with the help of a 3D seismic dataset and associated well tops and velocity data donated by ExxonMobil Corporation. This study involves seismic interpretation techniques, velocity modeling, cross section restoration of a series of seismic lines and 3D subsurface modeling using depth converted seismic horizons, well tops and balanced cross sections. The third chapter deals with the clay experiments of listric normal fault systems and tries to understand the controls on geometries of fault systems with and without a ductile substrate. Sloping flat base plate setups have been used and silicone fluid underlain below the clay cake has been considered as an analog for salt. The experimental configurations have been varied with respect to three factors viz. the direction of slope with respect to extension, the termination of silicone polymer with respect to the basal discontinuities and overlap of the base plates. The analyses for the experiments have again been performed from photographs and 3D laser scans of the clay surface.

Tc(VII) and Cr(VI) Interaction with Naturally Reduced Ferruginous Smectite from a Redox Transition Zone

DOE Office of Scientific and Technical Information (OSTI.GOV)

Qafoku, Odeta; Pearce, Carolyn I.; Neumann, Anke

Fe(II)-rich clay minerals found in subsurface redox transition zones (RTZs) can serve as important source of electron equivalents limiting the transport of redox active contaminants. While most laboratory reactivity studies are based on reduced model clays, the reactivity of naturally reduced clays in field samples remains poorly explored. Characterization of the clay size fraction of a fine-grained unit from RTZ interface at the Hanford site, Washington, including mineralogy, crystal chemistry, and Fe(II)/(III) content, indicates that ferruginous montmorillonite is the dominant mineralogical component. Oxic and anoxic fractions differ significantly in Fe(II) concentration, but FeTOTAL remains constant demonstrating no Fe loss duringmore » reduction-oxidation cycling. At its native pH of 8.6, the anoxic fraction despite its significant Fe(II) (~23% of FeTOTAL), exhibits minimal reactivity with TcO4- and CrO42- and much slower reaction kinetics than that measured in studies with biologically/chemically reduced model clays. Reduction capacity is enhanced by added Fe(II) (if Fe(II)SORBED >8% clay Fe(II)LABILE), however the kinetics of this conceptually surface-mediated reaction remain sluggish. Surface-sensitive Fe L-edge X-ray absorption spectroscopy shows that Fe(II)SORBED and the resulting reducing equivalents are not available in the outermost few nanometers of clay surfaces. Slow kinetics thus appear related to diffusion-limited access to electron equivalents retained within clay mineral.« less

Flocculation of Clay Colloids Induced by Model Polyelectrolytes: Effects of Relative Charge Density and Size.

PubMed

Sakhawoth, Yasine; Michot, Laurent J; Levitz, Pierre; Malikova, Natalie

2017-10-06

Flocculation and its tuning are of utmost importance in the optimization of several industrial protocols in areas such as purification of waste water and civil engineering. Herein, we studied the polyelectrolyte-induced flocculation of clay colloids on a model system consisting of purified clay colloids of well-defined size fractions and ionene polyelectrolytes presenting regular and tunable chain charge density. To characterize ionene-induced clay flocculation, we turned to the combination of light absorbance (turbidity) and ζ-potential measurements, as well as adsorption isotherms. Our model system allowed us to identify the exact ratio of positive and negative charges in clay-ionene mixtures, the (c+/c-) ratio. For all samples studied, the onset of efficient flocculation occurred consistently at c+/c- ratios significantly below 1, which indicated the formation of highly ionene-deficient aggregates. At the same time, the ζ-potential measurements indicated an apparent zero charge on such aggregates. Thus, the ζ-potential values could not provide the stoichiometry inside the clay-ionene aggregates. The early onset of flocculation in clay-ionene mixtures is reminiscent of the behavior of multivalent salts and contrasts that of monovalent salts, for which a large excess amount of ions is necessary to achieve flocculation. Clear differences in the flocculation behavior are visible as a function of the ionene charge density, which governs the conformation of the ionene chains on the clay surface. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Hydraulic anisotropy characterization of pneumatic-fractured sediments using azimuthal self potential gradient

USGS Publications Warehouse

Wishart, D.N.; Slater, L.D.; Schnell, D.L.; Herman, G.C.

2009-01-01

The pneumatic fracturing technique is used to enhance the permeability and porosity of tight unconsolidated soils (e.g. clays), thereby improving the effectiveness of remediation treatments. Azimuthal self potential gradient (ASPG) surveys were performed on a compacted, unconsolidated clay block in order to evaluate their potential to delineate contaminant migration pathways in a mechanically-induced fracture network. Azimuthal resistivity (ARS) measurements were also made for comparative purposes. Following similar procedures to those used in the field, compressed kaolinite sediments were pneumatically fractured and the resulting fracture geometry characterized from strike analysis of visible fractures combined with strike data from optical borehole televiewer (BHTV) imaging. We subsequently injected a simulated treatment (electrolyte/dye) into the fractures. Both ASPG and ARS data exhibit anisotropic geoelectric signatures resulting from the fracturing. Self potentials observed during injection of electrolyte are consistent with electrokinetic theory and previous laboratory results on a fracture block model. Visual (polar plot) analysis and linear regression of cross plots show ASPG lobes are correlated with azimuths of high fracture strike density, evidence that the ASPG anisotropy is a proxy measure of hydraulic anisotropy created by the pneumatic fracturing. However, ARS data are uncorrelated with fracture strike maxima and resistivity anisotropy is probably dominated by enhanced surface conduction along azimuths of weak 'starter paths' formed from pulverization of the clay and increases in interfacial surface area. We find the magnitude of electrokinetic SP scales with the applied N2 gas pressure gradient (??PN2) for any particular hydraulically-active fracture set and that the positive lobe of the ASPG anomaly indicates the flow direction within the fracture network. These findings demonstrate the use of ASPG in characterizing the effectiveness of (1) pneumatic fracturing and (2) defining likely flow directions of remedial treatments in unconsolidated sediments and rock. ?? 2008 Elsevier B.V. All rights reserved.

Fractional calculus applied to the analysis of spectral electrical conductivity of clay-water system.

PubMed

Korosak, Dean; Cvikl, Bruno; Kramer, Janja; Jecl, Renata; Prapotnik, Anita

2007-06-16

The analysis of the low-frequency conductivity spectra of the clay-water mixtures is presented. The frequency dependence of the conductivity is shown to follow the power-law with the exponent n=0.67 before reaching the frequency-independent part. When scaled with the value of the frequency-independent part of the spectrum the conductivity spectra for samples at different water content values are shown to fit to a single master curve. It is argued that the observed conductivity dispersion is a consequence of the anomalously diffusing ions in the clay-water system. The fractional Langevin equation is then used to describe the stochastic dynamics of the single ion. The results indicate that the experimentally observed dielectric properties originate in anomalous ion transport in clay-water system characterized with time-dependent diffusion coefficient.

Mixed-layer kerolite/stevensite from the Amargosa Desert, Nevada

USGS Publications Warehouse

Eberl, Dennis D.; Jones, Blair F.; Khoury, Hani N.

1982-01-01

Mixed-layer clays composed of randomly interstratified kerolite/stevensite occur as lake and/or spring deposits of probable Pliocene and Pleistocene age in the Amargosa Desert of southern Nevada, U.S.A. The percentage of expandable layers of these clays, determined from computer-simulated X-ray diffractograms, ranges from almost 0 to about 80%. This range in expandabilities most likely results from differences in solution chemistry and/or temperature at the time of formation. An average structural formula for the purest clay (sample P-7), a clay with about 70% expandable layers, is:[(Mg2.72Al0.07Fe0.03Li0.09)(Si3.96Al0.04)O10(OH)0.2]-0.21[X+0.21]+0.21The data suggest that talc, kerolite, and stevensite form a continuous structural series based on layer charge.

To what extent clay mineralogy affects soil aggregation? Consequences for soil organic matter stabilization

NASA Astrophysics Data System (ADS)

Fernandez-Ugalde, O.; Barré, P.; Hubert, F.; Virto, I.; Chenu, C.; Ferrage, E.; Caner, L.

2012-12-01

Aggregation is a key process for soil functioning as it influences C storage, vulnerability to erosion and water holding capacity. While the influence of soil organic C on aggregation has been documented, much less is known about the role of soil mineralogy. Soils usually contain a mixture of clay minerals with contrasted surface properties, which should result on different abilities of clay minerals to aggregation. We took advantage of the intrinsic mineral heterogeneity of a temperate Luvisol to compare the role of clay minerals (illite, smectite, kaolinite, and mixed-layer illite-smectite) in aggregation. In a first step, grassland and tilled soil samples were fractionated in water in aggregate-size classes according to the hierarchical model of aggregation (Tisdall and Oades, 1982). Clay mineralogy and organic C in the aggregate-size classes were analyzed. The results showed that interstratified minerals containing swelling phases accumulated in aggregated fractions (>2 μm) compared to free clay fractions (<2 μm) in the two land-uses. The accumulation increased from large macro-aggregates (>500 μm) to micro-aggregates (50-250 μm). C concentration and C/N ratio followed the opposite trend. These results constitute a clay mineral-based evidence for the hierarchical model of aggregation, which postulates an increasing importance of the reactivity of clay minerals in the formation of micro-aggregates compared to larger aggregates. In the latter aggregates, formation relies on the physical enmeshment of particles by fungal hyphae, and root and microbial exudates. In a second step, micro-aggregates from the tilled soil samples were submitted to increasingly disaggregating treatments by sonication to evaluate the link between their water stability and clay mineralogy. Micro-aggregates with increasing stability showed an increase of interstratified minerals containing swelling phases and C concentration for low intensities of disaggregation (from 0 to 5 J mL-1). This suggests that swelling phases promote their stability. Swelling phases and organic C decreased for greater intensities of disaggregation. These results and the SEM images taken at different disaggregation intensities indicate that when increasing disaggregation intensity above 5 J mL-1, the recovered material consists on sand particles covered by physical coatings of illite and kaolinite. Our results show that different clay minerals have different contribution to soil aggregation. Swelling phases are especially important for water-stable aggregates formation, whereas illite and kaolinite can either contribute to aggregation or been coated to sand grains in "mineral aggregates", without porosity and organic C protection capability. In conclusion, soils with large proportion of swelling clay minerals have greater potential for carbon storage by occlusion in aggregates and greater resistance to erosion. Tisdall JM, Oades JM (1982) Organic matter and water-stable aggregates in soils. J Soil Sci 62: 141-163.

Effects of the earthquake of March 27, 1964, at Anchorage, Alaska: Chapter A in The Alaska earthquake, March 27, 1964: effects on communities

USGS Publications Warehouse

Hansen, Wallace R.

1965-01-01

Anchorage, Alaska’s largest city, is about 80 miles west-northwest of the epicenter of the March 27 earthquake. Because of its size, Anchorage bore the brunt of property damage from the quake; it sustained greater losses than all the rest of Alaska combined. Damage was caused by direct seismic vibration, by ground cracks, and by landslides. Direct seismic vibration affected chiefly multistory buildings and buildings having large floor areas, probably because of the long period and large amplitude of the seismic waves reaching Anchorage. Most small buildings were spared. Ground cracks caused capricious damage throughout the Anchorage Lowland. Cracking was mast prevalent near the heads or within landslides but was also widespread elsewhere. Landslides themselves caused the most devastating damage. Triggering of landslides by the earthquake was related to the physical-engineering properties of the Bootlegger Cove Clay, a glacial estuarine-marine deposit that underlies much of the Anchorage area. The Bootlegger Cove Clay contains zones of low shear strength, high water content, and high sensitivity that failed under the vibratory stress of the earthquake. Shear strength in sensitive zones ranged from less than 0.2 tsf to about 0.5 tsf; sensitivity ranged from about 10 to more than 40. Sensitive zones generally are centered about 10 to 20 feet above sea level, between zones of stiff insensitive clay. Many physical tests by the U.S. Army Corps of Engineers were directed toward analyzing the causes of failure in the Bootlegger Cove Clay and finding possible remedies. Strengths and sensitivities were measured directly in the field by means of vane shear apparatus. A4tterberg limits, natural water contents, triaxial shear, sensitivity, dynamic modulus, consolidation strength, and other properties were measured in the laboratory. Pulsating-load tests simulated earthquake loading. Most of the destructive landslides in the Anchorage area moved primarily by translation rather than by rotation. Thus, all the highly damaging slides were of a single structural dynamic family despite wide variations in size, appearance, and complexity. They slid on nearly horizontal slip surfaces after loss of strength in the Bootlegger Core Clay. Same failures are attributed to spontaneous liquefaction of sand layers. All translatory slides surmounted flat-topped bluffs bounded marginally by steep slopes facing lower ground. Destructive translatory slides occurred in the downtown area (Fourth Avenue slide and L Street slide), at Government Hill, and at Turnagain Heights. Less destructive slides occurred in many other places-mostly uninhabited or undeveloped areas. In most translatory slides, damage was greatest in graben areas at the head and in pressure-ridge areas at the toe. Many buildings inside the perimeters of slide blocks were little damaged despite horizontal translations of several feet. The large Turnagain Heights slide, however, was characterized by a complete disintegration and drastic lowering of the prequake land surface. Extensive damage back from the slide, moreover, was caused by countless tension cracks. An approximation of the depth of failure in the Bootlegger Cove Clay in the various slides may be obtained by using a geometric relationship herein called the "graben rule." Because the cross-sectional area of the graben at the head of the slide approximated the cross-sectional area of the space voided behind the slide block as the block moved outward, the depth of failure was equal to the area of the graben divided by the lateral displacement. This approximation supplements and accords with test data obtained from borings. The graben rule should apply to any translatory slide in which flowage of material from the zone of failure has not been excessive. Geologic evidence indicates that landslides similar to those triggered by the March 27 earthquake have occurred in the Anchorage area at various times in the past.

Potential of polyaniline modified clay nanocomposite as a selective decontamination adsorbent for Pb(II) ions from contaminated waters; kinetics and thermodynamic study.

PubMed

Piri, Somayeh; Zanjani, Zahra Alikhani; Piri, Farideh; Zamani, Abbasali; Yaftian, Mohamadreza; Davari, Mehdi

2016-01-01

Nowadays significant attention is to nanocomposite compounds in water cleaning. In this article the synthesis and characterization of conductive polyaniline/clay (PANI/clay) as a hybrid nanocomposite with extended chain conformation and its application for water purification are presented. Clay samples were obtained from the central plain of Abhar region, Abhar, Zanjan Province, Iran. Clay was dried and sieved before used as adsorbent. The conductive polyaniline was inflicted into the layers of clay to fabricate a hybrid material. The structural properties of the fabricated nanocomposite are studied by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscope (SEM). The elimination process of Pb(II) and Cd(II) ions from synthetics aqueous phase on the surface of PANI/clay as adsorbent were evaluated in batch experiments. Flame atomic absorption instrument spectrophotometer was used for determination of the studied ions concentration. Consequence change of the pH and initial metal amount in aqueous solution, the procedure time and the used adsorbent dose as the effective parameters on the removal efficiency was investigated. Surface characterization was exhibited that the clay layers were flaked in the hybrid nanocomposite. The results show that what happen when a nanocomposite polyaniline chain is inserted between the clay layers. The adsorption of ions confirmed a pH dependency procedure and a maximum removal value was seen at pH 5.0. The adsorption isotherm and the kinetics of the adsorption processes were described by Temkin model and pseudo-second-order equation. Time of procedure, pH and initial ion amount have a severe effect on adsorption efficiency of PANI/clay. By using suggested synthesise method, nano-composite as the adsorbent simply will be prepared. The prepared PANI/clay showed excellent adsorption capability for decontamination of Pb ions from contaminated water. Both of suggested synthesise and removal methods are affordable techniques.

Faulting processes in active faults - Evidences from TCDP and SAFOD drill core samples

DOE Office of Scientific and Technical Information (OSTI.GOV)

Janssen, C.; Wirth, R.; Wenk, H. -R.

The microstructures, mineralogy and chemistry of representative samples collected from the cores of the San Andreas Fault drill hole (SAFOD) and the Taiwan Chelungpu-Fault Drilling project (TCDP) have been studied using optical microscopy, TEM, SEM, XRD and XRF analyses. SAFOD samples provide a transect across undeformed host rock, the fault damage zone and currently active deforming zones of the San Andreas Fault. TCDP samples are retrieved from the principal slip zone (PSZ) and from the surrounding damage zone of the Chelungpu Fault. Substantial differences exist in the clay mineralogy of SAFOD and TCDP fault gouge samples. Amorphous material has beenmore » observed in SAFOD as well as TCDP samples. In line with previous publications, we propose that melt, observed in TCDP black gouge samples, was produced by seismic slip (melt origin) whereas amorphous material in SAFOD samples was formed by comminution of grains (crush origin) rather than by melting. Dauphiné twins in quartz grains of SAFOD and TCDP samples may indicate high seismic stress. The differences in the crystallographic preferred orientation of calcite between SAFOD and TCDP samples are significant. Microstructures resulting from dissolution–precipitation processes were observed in both faults but are more frequently found in SAFOD samples than in TCDP fault rocks. As already described for many other fault zones clay-gouge fabrics are quite weak in SAFOD and TCDP samples. Clay-clast aggregates (CCAs), proposed to indicate frictional heating and thermal pressurization, occur in material taken from the PSZ of the Chelungpu Fault, as well as within and outside of the SAFOD deforming zones, indicating that these microstructures were formed over a wide range of slip rates.« less

A procedure for partitioning bulk sediments into distinct grain-size fractions for geochemical analysis

USGS Publications Warehouse

Barbanti, A.; Bothner, Michael H.

1993-01-01

A method to separate sediments into discrete size fractions for geochemical analysis has been tested. The procedures were chosen to minimize the destruction or formation of aggregates and involved gentle sieving and settling of wet samples. Freeze-drying and sonication pretreatments, known to influence aggregates, were used for comparison. Freeze-drying was found to increase the silt/clay ratio by an average of 180 percent compared to analysis of a wet sample that had been wet sieved only. Sonication of a wet sample decreased the silt/clay ratio by 51 percent. The concentrations of metals and organic carbon in the separated fractions changed depending on the pretreatment procedures in a manner consistent with the hypothesis that aggregates consist of fine-grained organic- and metal-rich particles. The coarse silt fraction of a freeze-dried sample contained 20–44 percent higher concentrations of Zn, Cu, and organic carbon than the coarse silt fraction of the wet sample. Sonication resulted in concentrations of these analytes that were 18–33 percent lower in the coarse silt fraction than found in the wet sample. Sonication increased the concentration of lead in the clay fraction by an average of 40 percent compared to an unsonicated sample. Understanding the magnitude of change caused by different analysis protocols is an aid in designing future studies that seek to interpret the spatial distribution of contaminated sediments and their transport mechanisms.

Chemical and mineralogical analysis of devonian black-shale samples from Martin County, Kentucky; Carroll and Washington counties, Ohio; Wise County, Virginia; and Overton County, Tennessee, U.S.A.

USGS Publications Warehouse

Leventhal, J.S.; Hosterman, J.W.

1982-01-01

Core samples of Devonian shales from five localities in the Appalachian basin have been analyzed chemically and mineralogically. The amounts of major elements are similar; however, the minor constituents, organic C, S, phosphate and carbonate show ten-fold variations in amounts. Trace elements Mo, Ni, Cu, V, Co, U, Zn, Hg, As and Mn show variations in amounts that can be related to the minor constituents. All samples contain major amounts of quartz, illite, two types of mixed-layer clays, and chlorite in differing quantities. Pyrite, calcite, feldspar and kaolinite are also present in many samples in minor amounts. Dolomite, apatite, gypsum, barite, biotite and marcasite are present in a few samples in trace amounts. Trace elements listed above are strongly controlled by organic C with the exception of Mn which is associated with carbonate minerals. Amounts of organic C generally range from 3 to 6%, and S is in the range of 2-5%. Amounts of trace elements show the following general ranges in ppm (parts per million): Co, 20-40; Cu, 40-70; U, 10-40; As, 20-40; V, 150-300; Ni, 80-150; high values are as much as twice these values. The organic C was probably the concentrating agent, and the organic C and sulfide S together created an environment that immobilized and preserved these trace elements. Closely spaced samples showing an abrupt transition in color also show changes in organic C, S and trace-element contents. Several associations exist between mineral and chemical content. Pyrite and marcasite are the only minerals found to contain sulfide-S. In general, the illite-chlorite mixed-layer clay mineral shows covariation with organic C if calcite is not present. The enriched trace elements are not related to the clay types, although the clay and organic matter are intimately associated as the bulk fabric of the rock. ?? 1982.

Mössbauer analysis of recent ceramic finds from Chavin

NASA Astrophysics Data System (ADS)

Wagner, U.; Wagner, F. E.; Stockklauser, A.; Salazar, R.; Riederer, J.; Kauffmann-Doig, F.

1986-02-01

A large number of ceramic sherds from Chavin, Peru, as well as recent clay samples from the same region have been studied by Mössbauer spectroscopy. The changes of the Mössbauer spectra of the clay were studied as a function of firing temperature and atmosphere. From a comparison of these data with those form the sherds one can make estimates of the precolumbian firing conditions.

Analysis of wall plasters and natural sediments from the Neolithic town of Çatalhöyük (Turkey) by a range of analytical techniques.

PubMed

Anderson, Emma; Almond, Matthew J; Matthews, Wendy

2014-12-10

Wall plaster sequences from the Neolithic town of Çatalhöyük have been analysed and compared to three types of natural sediment found in the vicinity of the site, using a range of analytical techniques. Block samples containing the plaster sequences were removed from the walls of several different buildings on the East Mound. Sub-samples were examined by IR spectroscopy, X-ray diffraction and X-ray fluorescence to determine the overall mineralogical and elemental composition, whilst thin sections were studied using optical polarising microscopy, IR Microscopy and Environmental Scanning Electron Microscopy with Energy Dispersive X-ray analysis. The results of this study have shown that there are two types of wall plaster found in the sequences and that the sediments used to produce these were obtained from at least two distinct sources. In particular, the presence of clay, calcite and magnesian calcite in the foundation plasters suggested that these were prepared predominantly from a marl source. On the other hand, the finishing plasters were found to contain dolomite with a small amount of clay and no calcite, revealing that softlime was used in their preparation. Whilst marl is located directly below and around Çatalhöyük, the nearest source of softlime is 6.5km away, an indication that the latter was important to the Neolithic people, possibly due to the whiter colour (5Y 8/1) of this sediment. Furthermore, the same two plaster types were found on each wall of Building 49, the main building studied in this research, and in all five buildings investigated, suggesting that the use of these sources was an established practice for the inhabitants of several different households across the site. Copyright © 2014 Elsevier B.V. All rights reserved.

Magnetic resonance imaging of clays: swelling, sedimentation, dissolution

NASA Astrophysics Data System (ADS)

Dvinskikh, Sergey; Furo, Istvan

2010-05-01

While most magnetic resonance imaging (MRI) applications concern medical research, there is a rapidly increasing number of MRI studies in the field of environmental science and technology. In this presentation, MRI will be introduced from the latter perspective. While many processes in these areas are similar to those addressed in medical applications of MRI, parameters and experimental implementations are often quite different and, in many respects, far more demanding. This hinders direct transfer of existing methods developed for biomedical research, especially when facing the challenging task of obtaining spatially resolved quantitative information. In MRI investigation of soils, clays, and rocks, mainly water signal is detected, similarly to MRI of biological and medical samples. However, a strong variation of water mobility and a wide spread of water spin relaxation properties in these materials make it difficult to use standard MRI approaches. Other significant limitations can be identified as following: T2 relaxation and probe dead time effects; molecular diffusion artifacts; varying dielectric losses and induced currents in conductive samples; limited dynamic range; blurring artifacts accompanying drive for increasing sensitivity and/or imaging speed. Despite these limitations, by combining MRI techniques developed for solid and liquid states and using independent information on relaxation properties of water, interacting with the material of interest, true images of distributions of both water, material and molecular properties in a wide range of concentrations can be obtained. Examples of MRI application will be given in the areas of soil and mineral research where understanding water transport and erosion processes is one of the key challenges. Efforts in developing and adapting MRI approaches to study these kinds of systems will be outlined as well. Extensive studies of clay/water interaction have been carried out in order to provide a quantitative measure of clay distribution in extended samples during different physical processes such as swelling, dissolution, and sedimentation on the time scale from minutes to years [1-3]. To characterize the state of colloids that form after/during clay swelling the water self-diffusion coefficient was measured on a spatially resolved manner. Both natural clays and purified and ion-exchanged montmorillonite clays were investigated. The primary variables were clay composition and water ionic strength. These results have a significant impact for engineering barriers for storage of spent nuclear fuel where clay erosion by low salinity water must be addressed. Presented methods were developed under the motivation of using bentonite clays as a buffer medium to build in-ground barriers for the encapsulation of radioactive waste. Nevertheless, the same approaches can be found suitable in other applications in soil and environmental science to study other types of materials as they swell, dissolve, erode, or sediment. Acknowledgements: This work has been supported by the Swedish Nuclear Fuel and Waste Management Co (SKB) and the Swedish Research Council VR. [1] N. Nestle, T. Baumann, R. Niessner, Magnetic resonance imaging in environmental science. Environ. Sci. Techn. 36 154A (2002). [2] S. V. Dvinskikh, K. Szutkowski, I. Furó. MRI profiles over a very wide concentration ranges: application to swelling of a bentonite clay. J. Magn. Reson. 198 146 (2009). [3] S. V. Dvinskikh, I. Furó. Magnetic resonance imaging and nuclear magnetic resonance investigations of bentonite systems. Technical Report, TR-09-27, SKB (2009), www.skb.se.

Acid activation of upper Eocene Ca-bentonite for soybean oil clarification.

PubMed

Chakroun, Salima; Herchi, Mongi; Mechti, Wafa; Gaied, Mohamed Essghaier

2017-10-01

In central Tunisia, many upper Eocene outcrops supply smectitic claystone which are characterized by several analytical techniques (calcimetry, XRD, SediGraph, chemical analysis, surface area, etc.). Beidellite is the main mineral detected by the XRD method. Representative raw samples M1, taken from Henchir Souar (Zaghouan, Tunisia), were acid activated in order to improve their physicochemical properties. This study consists in optimizing the activation conditions with HCl 3 N by varying the following parameters: time (2, 4, and 6 h) and temperature (25, 50, 75, and 90 °C). The characterization by XRD and chemical analysis was carried out on the samples (M1, activated for 2 and 6 h at 75 °C), showing a structural modification of the clay by reduction of intensity reflection 001 order of smectite and dissolution of metal ions (Al 3+ , Fe 3+ , and Mg 2+ ) from clay structure. Optimum condition for soybean oil clarification is obtained using a variety of amount raw clays (0.5, 0.75, and 1%). Thus, the best clarification yield is given at 0.75% of clay, showing a capacity of about 55%. Various forms of activated materials were used with a 75% proportion to leach soybean oil. Results were compared with commercial bentonite (Tonsil) having surface area (378 m 2 /g). The activated sample M1 during 4 h at 75 °C possesses a decolorizing capacity of about 85% greater than the oil treated by Tonsil in laboratory (58%).

Ball clay and bentonite deposits of the central and western Gulf of Mexico Coastal Plain, United States

USGS Publications Warehouse

Hosterman, John W.

1984-01-01

The Gulf of Mexico Coastal Plain produces approximately 85 percent of the ball clay used in the United States. The best commercial-grade clay deposits are composed of poorly crystalline kaolinite and small amounts of Md illite and (or) smectite. Sand and silt and iron oxide minerals are virtually absent, but quartz is present in the clay-size fraction. The best grade ball clays are found as lenses limited to the Wilcox Group (Paleocene and lower Eocene) and Claiborne Group (middle Eocene). Reserves of ball clay are sufficient for the present, but because of the lenticular nature of the clay bodies, close-spaced drilling, detailed sampling, mineralogic analyses, and ceramic testing are needed to prove future reserves.Approximately 11 percent of the total bentonite produced in the United States comes from the Gulf Coast region. The commercial-grade bentonites are composed primarily of smectite with little or no Md illite and kaolinite. The nonclay impurities are quartz, feldspar, muscovite, biotite, calcite, dolomite, gypsum, and heulandite. Commercial bentonites occur in the Upper Cretaceous formations in Alabama and Mississippi, in Paleocene formations in Mississippi and Tennessee, and in Eocene and Miocene formations in Texas. The demand for low-swelling bentonite of the Gulf Coastal Plain has not increased along with the demand for swelling bentonite; therefore the reserves are adequate.

Decomposition of algal lipids in clay-enriched marine sediment under oxic and anoxic conditions

NASA Astrophysics Data System (ADS)

Lü, Dongwei; Song, Qian; Wang, Xuchen

2010-01-01

A series of laboratory incubation experiments were conducted to examine the decomposition of algal organic matter in clay-enriched marine sediment under oxic and anoxic conditions. During the 245-day incubation period, changes in the concentrations of TOC, major algal fatty acid components (14:0, 16:0, 16:1, 18:1 and 20:5), and n-alkanes (C16-C23) were quantified in the samples. Our results indicate that the organic matters were degraded more rapidly in oxic than anoxic conditions. Adsorption of fatty acids onto clay minerals was a rapid and reversible process. Using a simple G model, we calculated the decomposition rate constants for TOC, n-alkanes and fatty acids which ranged from 0.017-0.024 d-1, 0.049-0.103 d-1 and 0.011 to 0.069 d-1, respectively. Algal organic matter degraded in two stages characterized by a fast and a slow degradation processes. The addition of clay minerals montmorillonite and kaolinite to the sediments showed significant influence affecting the decomposition processes of algal TOC and fatty acids by adsorption and incorporation of the compounds with clay particles. Adsorption/association of fatty acids by clay minerals was rapid but appeared to be a slow reversible process. In addition to the sediment redox and clay influence, the structure of the compounds also played important roles in affecting their degradation dynamic in sediments.

Improved Yield of High Molecular Weight DNA Coincides with Increased Microbial Diversity Access from Iron Oxide Cemented Sub-Surface Clay Environments

PubMed Central

Hurt, Richard A.; Robeson, Michael S.; Shakya, Migun; Moberly, James G.; Vishnivetskaya, Tatiana A.; Gu, Baohua; Elias, Dwayne A.

2014-01-01

Despite over three decades of progress, extraction of high molecular weight (HMW) DNA from high clay soils or iron oxide cemented clay has remained challenging. HMW DNA is desirable for next generation sequencing as it yields the most comprehensive coverage. Several DNA extraction procedures were compared from samples that exhibit strong nucleic acid adsorption. pH manipulation or use of alternative ion solutions offered no improvement in nucleic acid recovery. Lysis by liquid N2 grinding in concentrated guanidine followed by concentrated sodium phosphate extraction supported HMW DNA recovery from clays high in iron oxides. DNA recovered using 1 M sodium phosphate buffer (PB) as a competitive desorptive wash was 15.22±2.33 µg DNA/g clay, with most DNA consisting of >20 Kb fragments, compared to 2.46±0.25 µg DNA/g clay with the Powerlyzer system (MoBio). Increasing PB concentration in the lysis reagent coincided with increasing DNA fragment length during initial extraction. Rarefaction plots of 16S rRNA (V1–V3 region) pyrosequencing from A-horizon and clay soils showed an ∼80% and ∼400% larger accessed diversity compared to the Powerlyzer soil DNA system, respectively. The observed diversity from the Firmicutes showed the strongest increase with >3-fold more operational taxonomic units (OTU) recovered. PMID:25033199

Zr-doped TiO2 supported on delaminated clay materials for solar photocatalytic treatment of emerging pollutants.

PubMed

Belver, C; Bedia, J; Rodriguez, J J

2017-01-15

Solar light-active Zr-doped TiO 2 nanoparticles were successfully immobilized on delaminated clay materials by a one-step sol-gel route. Fixing the amount of TiO 2 at 65wt.%, this work studies the influence of Zr loading (up to 2%) on the photocatalytic activity of the resulting Zr-doped TiO 2 /clay materials. The structural characterization demonstrates that all samples were formed by a delaminated clay with nanostructured anatase assembled on its surface. The Zr dopant was successfully incorporated into the anatase lattice, resulting in a slight deformation of the anatase crystal and the reduction of the band gap. These materials exhibit high surface area with a disordered mesoporous structure formed by TiO 2 particles (15-20nm) supported on a delaminated clay. They were tested in the solar photodegradation of antipyrine, usually used as an analgesic drug and selected as an example of emerging pollutant. High degradation rates have been obtained at low antipyrine concentrations and high solar irradiation intensities with the Zr-doped TiO 2 /clay catalyst, more effective than the undoped one. This work demonstrates the potential application of the synthesis method for preparing novel and efficient solar-light photocatalysts based on metal-doped anatase and a delaminated clay. Copyright © 2016 Elsevier B.V. All rights reserved.

How do changes in bulk soil organic carbon content affect carbon concentrations in individual soil particle fractions?

PubMed Central

Yang, X. M.; Drury, C. F.; Reynolds, W. D.; Yang, J. Y.

2016-01-01

We test the common assumption that organic carbon (OC) storage occurs on sand-sized soil particles only after the OC storage capacity on silt- and clay-sized particles is saturated. Soil samples from a Brookston clay loam in Southwestern Ontario were analysed for the OC concentrations in bulk soil, and on the clay (<2 μm), silt (2–53 μm) and sand (53–2000 μm) particle size fractions. The OC concentrations in bulk soil ranged from 4.7 to 70.8 g C kg−1 soil. The OC concentrations on all three particle size fractions were significantly related to the OC concentration of bulk soil. However, OC concentration increased slowly toward an apparent maximum on silt and clay, but this maximum was far greater than the maximum predicted by established C sequestration models. In addition, significant increases in OC associated with sand occurred when the bulk soil OC concentration exceeded 30 g C kg−1, but this increase occurred when the OC concentration on silt + clay was still far below the predicted storage capacity for silt and clay fractions. Since the OC concentrations in all fractions of Brookston clay loam soil continued to increase with increasing C (bulk soil OC content) input, we concluded that the concept of OC storage capacity requires further investigation. PMID:27251365

How do changes in bulk soil organic carbon content affect carbon concentrations in individual soil particle fractions?

NASA Astrophysics Data System (ADS)

Yang, X. M.; Drury, C. F.; Reynolds, W. D.; Yang, J. Y.

2016-06-01

We test the common assumption that organic carbon (OC) storage occurs on sand-sized soil particles only after the OC storage capacity on silt- and clay-sized particles is saturated. Soil samples from a Brookston clay loam in Southwestern Ontario were analysed for the OC concentrations in bulk soil, and on the clay (<2 μm), silt (2-53 μm) and sand (53-2000 μm) particle size fractions. The OC concentrations in bulk soil ranged from 4.7 to 70.8 g C kg-1 soil. The OC concentrations on all three particle size fractions were significantly related to the OC concentration of bulk soil. However, OC concentration increased slowly toward an apparent maximum on silt and clay, but this maximum was far greater than the maximum predicted by established C sequestration models. In addition, significant increases in OC associated with sand occurred when the bulk soil OC concentration exceeded 30 g C kg-1, but this increase occurred when the OC concentration on silt + clay was still far below the predicted storage capacity for silt and clay fractions. Since the OC concentrations in all fractions of Brookston clay loam soil continued to increase with increasing C (bulk soil OC content) input, we concluded that the concept of OC storage capacity requires further investigation.

Contribution to the study of thermal properties of clay bricks reinforced by date palm fiber

NASA Astrophysics Data System (ADS)

Mekhermeche, A.; Kriker, A.; Dahmani, S.

2016-07-01

The Saharan regions of Algeria are characterized by a hot and dry climate. The most used cement materials such as theconcrete or the mortar blocks have bad thermal characteristic. However, these regions have several local materials: clay, dune sand and some natural fibers, which are formerly proved their thermal efficiency. The price of construction material used therefore depends on the international market constantly destabilized by theeconomic crisis coupled with the energy crisis in recent times. To produce a framework of life at a lower cost, it is important, therefore, to circumvent the influence of the cost of energy by upgrading the local materials of construction. In order to improve thermal performances in Saharan building materials this study was lanced. The aim of this research isthen to fabricate some bricks using three local materials: namely the clay, sand dune and the fibers of date palm. The percentage of sand and fibers varies from 0% to 40% and 0% to 3% by mass respectively. A sand dune of Ain El Beida of Ouargla of Algeria was used. Clay was extracted from Beldet Amer of Touggourt Ouargla Algérie. The fibers used in this study were vegetable fibers from date palm of Ouargla Algeria. The results showed that increasing in the mass fraction of sand and of fiber were beneficial for improving thermal properties. As function of increasing the percentage of sand dune and fibers there were: A decrease in: thermal conductivity, specific heat, heat capacity, thermal effusivity and thermal diffusivity and there were an increase in the thermal resistance.

Pore- and fracture-filling gas hydrate reservoirs in the Gulf of Mexico Gas Hydrate Joint Industry Project Leg II Green Canyon 955 H well

USGS Publications Warehouse

Lee, M.W.; Collett, T.S.

2012-01-01

High-quality logging-while-drilling (LWD) downhole logs were acquired in seven wells drilled during the Gulf of MexicoGasHydrateJointIndustryProjectLegII in the spring of 2009. Well logs obtained in one of the wells, the GreenCanyon Block 955Hwell (GC955-H), indicate that a 27.4-m thick zone at the depth of 428 m below sea floor (mbsf; 1404 feet below sea floor (fbsf)) contains gashydrate within sand with average gashydrate saturations estimated at 60% from the compressional-wave (P-wave) velocity and 65% (locally more than 80%) from resistivity logs if the gashydrate is assumed to be uniformly distributed in this mostly sand-rich section. Similar analysis, however, of log data from a shallow clay-rich interval between 183 and 366 mbsf (600 and 1200 fbsf) yielded average gashydrate saturations of about 20% from the resistivity log (locally 50-60%) and negligible amounts of gashydrate from the P-wave velocity logs. Differences in saturations estimated between resistivity and P-wave velocities within the upper clay-rich interval are caused by the nature of the gashydrate occurrences. In the case of the shallow clay-rich interval, gashydrate fills vertical (or high angle) fractures in rather than fillingpore space in sands. In this study, isotropic and anisotropic resistivity and velocity models are used to analyze the occurrence of gashydrate within both the clay-rich and sand dominated gas-hydrate-bearing reservoirs in the GC955-Hwell.

Research and application of multi-hydrogen acidizing technology of low-permeability reservoirs for increasing water injection

NASA Astrophysics Data System (ADS)

Ning, Mengmeng; Che, Hang; Kong, Weizhong; Wang, Peng; Liu, Bingxiao; Xu, Zhengdong; Wang, Xiaochao; Long, Changjun; Zhang, Bin; Wu, Youmei

2017-12-01

The physical characteristics of Xiliu 10 Block reservoir is poor, it has strong reservoir inhomogeneity between layers and high kaolinite content of the reservoir, the scaling trend of fluid is serious, causing high block injection well pressure and difficulty in achieving injection requirements. In the past acidizing process, the reaction speed with mineral is fast, the effective distance is shorter and It is also easier to lead to secondary sedimentation in conventional mud acid system. On this point, we raised multi-hydrogen acid technology, multi-hydrogen acid release hydrogen ions by multistage ionization which could react with pore blockage, fillings and skeletal effects with less secondary pollution. Multi-hydrogen acid system has advantages as moderate speed, deep penetration, clay low corrosion rate, wet water and restrains precipitation, etc. It can reach the goal of plug removal in deep stratum. The field application result shows that multi-hydrogen acid plug removal method has good effects on application in low permeability reservoir in Block Xiliu 10.

Green Clay Minerals

NASA Astrophysics Data System (ADS)

Velde, B.

2003-12-01

Color is a problem for scientific study. One aspect is the vocabulary one used to describe color. Mint green, bottle green, and Kelly green are nice names but not of great utility in that people's physical perception of color is not always the same. In some industries, such as colored fabric manufacture, current use is to send a set of standard colors which are matched by the producer. This is similar to the use of the Munsell color charts in geology. None of these processes makes use of physical optical spectral studies. The reason is that they are difficult to obtain and interpret. For a geologist, color is very important but we rarely have the possibility to standardize the method of our color perception. One reason is that color is both a reflective and transmission phenomenon. The thickness of the sample is critical to any transmission characteristics. Hence, a field color determination is different from one made by using a petrographic microscope. Green glauconite in a hand specimen is not the same color in 30 μm thick thin section seen with a microscope using transmitted light.A second problem is that color in a spectral identification is the result of several absorption emissions,with overlapping signal, forming a complicated spectrum. Interpretation depends very greatly on the spectrum of the light source and the conditions of transmission-reflection of the sample. As a result, for this text, we will not attempt to analyze the physical aspect of green in green clays. In the discussion which follows, reference is made concerning color, to thin section microscopic perception.Very briefly, green clay minerals are green, because they contain iron. This is perhaps not a great revelation to mineralogists, but it is the key to understanding the origin and stability of green clay minerals. In fact, iron can color minerals either red or green or in various shades of orange and brown. The color most likely depends upon the relative abundance of the iron ion valence 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 the genesis of green clay minerals; they contain iron in both oxidation states.Unfortunately modern methods of mineral analysis on a microscopic scale, electron microbeam and others, do not allow the determination of the different oxidation states of iron especially for nonstoichiometric minerals. One can use Mössbauer spectral analysis, but the scales of observations are not the same (Mössbauer needing more material); one method used for observations on a microscale, the other on a macroscale. Given the problems of micro- and macroscale observations, oxidation state information is almost excluded from data gathered since the 1980s or so, and hence information concerning the relations of iron reduction and clay genesis must be taken from older studies. A second, much greater problem is that little X-ray diffraction (XRD) work is done on samples which are analyzed chemically by electron microbeam studies. In the past both types of information, structural and chemical, were available for the same sample. Hence not only do we have no precise chemical data for many samples (oxidation state of iron), but there is a rarity of mineral structural information to go along with the incomplete chemistry. This is critical for the study of clay minerals, because slight chemical changes in a clay mineral are frequently accompanied by changes in its structure, especially when one deals with interstratified clay minerals (mica/smectites for example). In fact, the tendency to obtain more and more precision (analysis of a smaller and smaller sized sample) has led to a total loss of mineralogical data. The Heisenberg principle is unwittingly verified by geologists. We know more about a small part of a sample, but we know less about its whole. As a result, the following discussion is based largely upon old data, those which combine iron oxidation states and XRD information.

Impact of treated wastewater on growth, respiration and hydraulic conductivity of citrus root systems in light and heavy soils.

PubMed

Paudel, Indira; Cohen, Shabtai; Shaviv, Avi; Bar-Tal, Asher; Bernstein, Nirit; Heuer, Bruria; Ephrath, Jhonathan

2016-06-01

Roots interact with soil properties and irrigation water quality leading to changes in root growth, structure and function. We studied these interactions in an orchard and in lysimeters with clay and sandy loam soils. Minirhizotron imaging and manual sampling showed that root growth was three times lower in the clay relative to sandy loam soil. Treated wastewater (TWW) led to a large reduction in root growth with clay (45-55%) but not with sandy loam soil (<20%). Treated wastewater increased salt uptake, membrane leakage and proline content, and decreased root viability, carbohydrate content and osmotic potentials in the fine roots, especially in clay. These results provide evidence that TWW challenges and damages the root system. The phenology and physiology of root orders were studied in lysimeters. Soil type influenced diameter, specific root area, tissue density and cortex area similarly in all root orders, while TWW influenced these only in clay soil. Respiration rates were similar in both soils, and root hydraulic conductivity was severely reduced in clay soil. Treated wastewater increased respiration rate and reduced hydraulic conductivity of all root orders in clay but only of the lower root orders in sandy loam soil. Loss of hydraulic conductivity increased with root order in clay and clay irrigated with TWW. Respiration and hydraulic properties of all root orders were significantly affected by sodium-amended TWW in sandy loam soil. These changes in root order morphology, anatomy, physiology and hydraulic properties indicate rapid and major modifications of root systems in response to differences in soil type and water quality. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Trace Elements in Cretaceous-Tertiary Boundary Clay at Gubbio, Italy

NASA Astrophysics Data System (ADS)

Ebihara, M.; Miura, T.

1992-07-01

In 1980, Alvarez et al. reported high Ir concentrations for the Cretaceous-Tertiary (hereafter, K/T) boundary layer, suggesting an impact of extraterrestrial material as a possible cause of the sudden mass extinction at the end of the Cretaceous period. Since then, high Ir abundances have been reported for K/T layers all over the world. Iridium enrichments were alternatively explained in terms of volcanic eruptions (Officer and Drake, 1982) or sedimentation (Zoller et al, 1982). Thus, abundances of Ir only cannot be critical in explaining the cause of the mass extinctions at the K/T boundary. In contrast to the fairly large number of Ir data for K/T boundary geological materials, only limited data are available for other siderophile elements. Relative abundances of siderophiles must be more informative in considering the causes of extinction, and provide further data on the type of extraterrestrial material of the projectile if siderophile abundances are in favor of an impact as the cause of the mass extinction at the K/T boundary. Thus, we analyzed additional K/T boundary materials for trace elements, including some of the siderophiles. A total of 7 samples collected from the K/T boundary near Gubbio, Italy (three from Bottaccione, four from Contessa) were analyzed. For comparison, we analyzed three additional samples, one from a Cretaceous sediment layer and the remaining two from a Tertiary layer. Four siderophile elements (Ir, Pt, Au, and Pd) were measured by RNAA and more than 25 elements, including 9 lanthanoids, were measured by INAA. The siderophiles listed above and Ni were found to be present in all of the boundary clay samples. They have C1-normalized abundances of 0.02 for Ni, Ir, and Pt, 0.04 for Pd, and Au was exceptionally depleted at 0.005. Both Ni and Ir show fairly small variations in abundances among the clay samples, whereas the other three elements show quite large variations, exceeding error limits. We believe that similar enrichments for these siderophiles in the K/T boundary clays were caused by an impact of extraterrestrial material having siderophiles that have not been largely fractionated. Similar abundance patterns of REE were confirmed not only for clay samples but also for the Cretaceous and Tertiary sediments. This suggests that sedimentation continued in similar circumstances without a large disturbance at the K/T boundary. We confirmed excellent correlations among Ir, As, and Sb abundances in the K/T samples, suggesting that they had a similar solution chemistry when sedimentation occurred. Both As and Sb show similar abundances, even for the Cretaceous as well as the Tertiary sediments, while Ir does not. Neither Pd nor Pt shows any correlation with these elements or with each other. This suggests that Ir was trapped into the clay together with As and Sb, but not with Pd or Pt. It is highly unlikely that these siderophiles were supplied only from sea water, and were eventually greatly enriched in clay materials, with the relative elemental abundances coinciding with those in chondrites. Thus, our data strongly suggest that a large impact of extraterrestrial material (chondritic?) caused the enrichment of siderophiles at K/T boundary. Acknowledgment. We are indebted to M. Ozima and S. Amari for samples analyzed in this work. References Alvarez, L.W., Alvarez, W., Asaro, F., and Michel, H.V. (1980) Science 208, 1095-1108. Officer, C.B. and Drake, C.L. (1982) Science 219, 1383-1390. Zoller, W.H., Parrington, J.R., and Kotra, J.M.P. (1983) Science 222, 1118-1120.

Frictional Properties of the Nankai Trough Accretionary Mud Samples Collected from 1000-3000 mbsf at IODP Site C0002

NASA Astrophysics Data System (ADS)

Kanagawa, K.; Hoshino, K.; Abe, K.; Sawai, M.

2016-12-01

We conducted triaxial friction experiments on the Nankai Trough accretionary mud samples collected from 1000-3000 mbsf (meters below seafloor) at IODP Site C0002 off Kii Peninsula, at confining pressures of 44-83 MPa, pore water pressures of 32-50 MPa and temperatures of 51-98°C equivalent to their in situ conditions, and at axial displacement rates changed stepwise among 0.1, 1 and 10 µm/s, in order to investigate their frictional properties changing with depth. XRD analyses of tested mud samples revealed that the content of total clay minerals tends to increase with depth from 30 to 60 wt%, while the smectite fraction in total clay minerals decreases with depth from 0.75 to 0.3. Because the temperature at 3000 mbsf reaches 100°C, this decrease in smectite fraction with depth is likely due to the progress of smectite dehydration with increasing temperature. Friction experiments on tested mud samples revealed that the steady-state friction coefficient at an axial displacement rate of 1 µm/s tends to decrease with depth from 0.5 to 0.3, according to the increasing content of total clay minerals with depth. Velocity dependence of steady-state friction also tends to decrease with depth, likely reflecting a decrease in smectite fraction in total clay minerals. Although velocity dependence of steady-state friction is mostly positive at depths down to 3000 mbsf, it is locally neutral or negative at depths deeper than 2000 mbsf, implying that faulting at these depths is conditionally stable and possibly accompanied by slow slip events.

Park River, Local Protection Auxiliary Conduit Tunnel As-Built Foundation Report, Hartford, Connecticut. Volume II. Appendices.

DTIC Science & Technology

1982-12-01

AUXILIARY TUNNEL AS-BUILT FOUNDATION REPORT It. KEY WORDS (Cenlasa on icteic. &#it* it necessary ad Identifpy block o"Whow) Strain Gages Settlement PeB...anomalously high bedding angles, severe brecciation and fracturing and an approximately 65-ft- wide zone of a plastic mixture of sand, silt and clay with some...wetted and partially filled with a mortar cement mix with Sika #2 added as a hardening agent. The mount assembly was then inserted into the holes so

Clay Improvement with Burned Olive Waste Ash

PubMed Central

Mutman, Utkan

2013-01-01

Olive oil is concentrated in the Mediterranean basin countries. Since the olive oil industries are incriminated for a high quantity of pollution, it has become imperative to solve this problem by developing optimized systems for the treatment of olive oil wastes. This study proposes a solution to the problem. Burned olive waste ash is evaluated for using it as clay stabilizer. In a laboratory, bentonite clay is used to improve olive waste ash. Before the laboratory, the olive waste is burned at 550°C in the high temperature oven. The burned olive waste ash was added to bentonite clay with increasing 1% by weight from 1% to 10%. The study consisted of the following tests on samples treated with burned olive waste ash: Atterberg Limits, Standard Proctor Density, and Unconfined Compressive Strength Tests. The test results show promise for this material to be used as stabilizer and to solve many of the problems associated with its accumulation. PMID:23766671

The Evaluation of Basal Respiration for Various Soil Textures in Ecologically Sensitive Area

NASA Astrophysics Data System (ADS)

Huličová, P.; Kotorová, D.; Fazekašová, D.; Hynšt, J.

2017-10-01

The present contribution was focused on monitoring changes in the soil basal respiration in different textures of soil in the dry polder Beša. The research was conducted between 2012 and 2014 on soil type Fluvisol locations on three soil textures: clay - loam soil, clayey soil and clay soil in three soil depths. The basal respiration (BR) has been determine by soil CO2 production measuring from incubated soil samples in serum bottles in laboratory condition. Release Co2 has been analysed by gas chromatography. Content of clay particles were in the range 52.18 % to 81.31%, indicating the high difference between the minimum and maximum content. By using of multiple LSD-test we recorded statistically significant impact of clay on basal respiration. Results confirm the values of basal respiration with the depth of the soil profile decreased.

Thermal expansion of ceramic samples containing natural zeolite

NASA Astrophysics Data System (ADS)

Sunitrová, Ivana; Trník, Anton

2017-07-01

In this study the thermal expansion of ceramic samples made from natural zeolite is investigated. Samples are prepared from the two most commonly used materials in ceramic industry (kaolin and illite). The first material is Sedlec kaolin from Czech Republic, which contains more than 90 mass% of mineral kaolinite. The second one is an illitic clay from Tokaj area in Hungary, which contains about 80 mass% of mineral illite. Varying amount of the clay (0 % - 50 %) by a natural zeolite from Nižný Hrabovec (Slovak Republic), containing clinoptilolite as major mineral phase is replaced. The measurements are performed on cylindrical samples with a diameter 14 mm and a length about 35 mm by a horizontal push - rod dilatometer. Samples made from pure kaolin, illite and zeolite are also subjected to this analysis. The temperature regime consists from linear heating rate of 5 °C/min from 30 °C to 1100 °C. The results show that the relative shrinkage of ceramic samples increases with amount of zeolite in samples.

Influence of nanoclay on interlaminar shear strength and fracture toughness of glass fiber reinforced nanocomposites

NASA Astrophysics Data System (ADS)

Senthil Kumar, M. S.; Chithirai Pon Selvan, M.; Sampath, P. S.; Raja, K.; Balasundaram, K.

2018-04-01

Multilayer glass fiber reinforced polymer (GFRP) laminates filled with nanoclay was manufactured with compression moulding machine. In the present work, five kinds of nanoclay (Cloisite 25A) loadings viz. 2, 4, 6, 8 and 10% on weight basis of epoxy resin were employed to modify the interlaminar shear strength (ILSS), critical energy release rate (GIc) and impact energy properties of GFRP laminates. Experimental results obtained from ILSS test on clay filled GFRP confirm that the superior strength was attained at low clay content of 155.10 MPa. Furthermore, the mode I interlaminar fracture toughness test conducted on DCB specimens revealed that the commanding improvement of GIc was obtained at 2 wt.% clay content level. On the other hand, both ILSS and fracture toughness was getting reduced at higher clay loadings. At last, the impact strength of the test samples was investigated by using Izod impact test apparatus and observed that the impact energy was increased by 44.39% for 2 wt.% and followed by 24.87% for 4 wt.% clay loadings.

Study on Fired Clay Bricks by Replacing Clay with Palm Oil Waste: Effects on Physical and Mechanical Properties

NASA Astrophysics Data System (ADS)

Kadir, A. A.; Sarani, N. A.; Abdullah, M. M. A. B.; Perju, M. C.; Sandu, A. V.

2017-06-01

Palm oil is one of the major agricultural industries in Malaysia. Due to the poor management system, the discarded palm oil waste has always been linked to the environment issues. During processing of palm oil, a considerable amount of solid waste by-products in the form of fibres, shells, empty fruit bunches and fly ashes are produce rapidly. Therefore, this study was conducted to incorporate 1%, 5% and 10% of palm oil waste into fired clay brick. Samples of brick were fired at 1050°C temperature with heating rates of 1°C/min. Manufactured bricks were tested with physical and mechanical properties including firing shrinkage, dry density, water absorption and compressive strength. The results demonstrated that the replacement of 1% up to 5% of palm oil waste had improved several properties, although, a decrease of performance in certain aspects has also been observed. As a result, palm oil waste can be utilized in an environmentally safe way into fired clay brick thus providing adequate properties of fired clay brick.

The radiolysis and radioracemization of amino acids on clays

NASA Technical Reports Server (NTRS)

Bonner, W. A.; Hall, H.; Chow, G.; Yi, L.; Lemmon, R. M.

1985-01-01

The effects of the surfaces of kaolinite and bentonite clays on the radiolysis and radioracemization of L-leucine and its hydrochloride salt have been investigated experimentally. L-leucine and its hydrochloride salt were deposited on the clays and the amino acid/clay preparations were irradiated by a Co-60 gamma-ray source which induced 2-89 percent radiolysis. The efficiency of radiolysis and radioracemization were measured using gas chromatography. Results were obtained for leucine in 0.1 M aqueous solution for comparison with the clay-deposted leucine and leucine hydrochloride. It is found that radiolysis and radioracemization in the samples occurred according to a pseudo-first-order rate law. Comparison of the specific rate constants showed that leucine and its hydrochloride salt were the most resistant to both radiolysis and radioracemization, followed by leucine and its hydrochloride salt on kaolin. Leucine and its HCl salt on bentonite, and leucine in aqueous solution were found to be the least resistant to radiolysis and radioracemization. The experimental results are intepreted with respect to the Vester-Ulbricht mechanism for the origin of optical activity.

Ultrasonically assisted single screw extrusion, film blowing and film casting of LLDPE/clay and PA6/clay nanocomposites

NASA Astrophysics Data System (ADS)

Niknezhad, Setareh

The major objective of this study was to investigate the effect of ultrasonic treatment on the dispersion of modified clay particles in LLDPE and PA6 matrices and the final properties of nanocomposites. LLDPE and PA6 are two polymers that are widely used in packaging industry. Blown and cast films were manufactured from the prepared nanocomposites. To achieve one step film processing, an online ultrasonic film casting was developed. Ultrasonic waves caused high-energy mixing and dispersion due to the acoustic cavitation, causing the clay agglomorates to separate into individual platelets in polymer matrix. Ultrasonic waves also broke down the polymer molecular chains reducing viscosity of the melt, facilating dispersion of the clay platelets throughout the matrix. Ultrasound also led to a breakage of the clay platelets reducing the particle size and improving their distribution. Clay particles acted as a heterogenous nucleation agent generating smaller size polymer crystals. In turn, these improved different properties including mechanical properties, oxygen permeability and transparency of films. In LLDPE/clay 20A nanocomposites, the effect of ultrasound was more obvious at higher clay loadings. Exfoliated structure for ultrasonically treated nanocomposites containing 2.5, 5 and 7.5 wt% of clay 20A and highly intercalated structure for ultrasonically treated nanocomposites containing 10 wt% of clay 20A were achieved. However, in blown films, the exfoliated structure transferred to the intercalated structure due to the addition of more shear and thermal degradation of surfactants of the clay particles. While, manufacturing cast films using the new developed online ultrasonic cast film machine revealed the exfoliated structure with ultrasonic treatment till 7.5 wt% of clay loadings. Cast films of nanocomposites containing 5 wt% of clay loadings were also prepared with addition of different compatibilizers. The compatibilizer containing higher amount of grafted maleic anhydride (MA) affected mechanical properties and oxygen permeability with ultrasonic treatment to higher extent. However, use of compatibilizers led to a higher die pressure and resulted in opaque cast films. The mechanical properties were in agreement with crystallinity of samples. The exfoliated structure was achieved for PA6/clay 30B nanocomposites prepared using ultrasonically assisted single screw extrusion except for untreated nanocomposites containing 10 wt% of clay 30B. Untreated 92.5/7.5 and 90/10 PA6/clay 30B blown films showed the intercalated structure, but the exfoliated structure was achieved with ultrasonic treatment. All cast films of PA6/clay 30B showed the exfoliated structure. FTIR spectroscopy along with XRD results confirmed the existence of alpha and gamma-type crystals in the cast films, with clay particles favoring the formation of gamma-type crystals, and ultrasonic treatment favoring the formation of alpha-type crystals. Both parameters increased crystallinity of cast films improving their mechanical properties and oxygen permeability.

Detailed mineral and chemical relations in two uranium-vanadium ores

USGS Publications Warehouse

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

1956-01-01

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 identical in mineralogy prior to oxidation by weathering: vanadium was present as V(III) in montroseite and V(IV) in the vanadium clays; uranium was present largely as U(IV) in coffinite and/or uraninite. The Mineral Joe No. 1 mine channel sample is now more fully oxidized. Vanadium clays are unquestionably formed abundantly during the primary mineralization, and they persist with a minimum of alteration during much of the weathering. They suggest that the vanadium is carried as V(IV) in the ore-forming fluids; it seems likely too that the uranium is carried as a U(VI) ion.

Structural control of co-continuous poly(L-lactide)/poly(butylene succinate)/clay nanocomposites.

PubMed

Zhao, Li; Li, Yongjin; Shimizu, Hiroshi

2009-04-01

Poly(L-lactide) (PLLA)/poly(butylene succinate) (PBS) (55/45 w/w) blends with different amounts of nanoclay loadings were prepared using a specially designed high-shear extruder, HSE3000mini, which can reach a maximum shear rate of 4400 sec(-1). The resulted co-continuous structural morphologies were observed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). SEM observation revealed that through the combination of various amounts of nanoclay loadings and processing under various shear conditions, the phase size of co-continuous structures of PLLA/PBS blends can be controlled over a wide range from several tens of micrometers to submicrometers. TEM observation shows that all the nanoclays are selectively dispersed in the PBS phase. We also found that clays in low-shear processed sample were mainly located at the interface of PBS phase, while in high-shear sample, the clays were mainly located inside of the PBS phase. It was considered that the dependence of nanoclay location in the PBS phase on the shear conditions, as well as the changing of the viscosity ratio of PBS and PLLA phase with different amounts of clay loading, play important roles in controlling the phase size of the co-continuous structures of PLLA/PBS blends.

Investigation of mechanical properties of hemp/glass fiber reinforced nano clay hybrid composites

NASA Astrophysics Data System (ADS)

Unki, Hanamantappa Ningappa; Shivanand, H. K.; Vidyasagar, H. N.

2018-04-01

Over the last twenty to thirty years composite materials have been used in engineering field. Composite materials possess high strength, high strength to weight ratio due to these facts composite materials are becoming popular among researchers and scientists. The major proportion of engineering materials consists of composite materials. Composite materials are used in vast applications ranging from day-to-day household articles to highly sophisticated applications. In this paper an attempt is made to prepare three different composite materials using e-glass and Hemp. In this present investigation hybrid composite of Hemp, Glass fiber and Nano clay will be prepared by Hand-layup technique. The glass fiber used in this present investigation is E-glass fiber bi-directional: 90˚ orientation. The composite samples will be made in the form of a Laminates. The wt% of nanoclay added in the preparation of sample is 20 gm constant. The fabricated composite Laminate will be cut into corresponding profiles as per ASTM standards for Mechanical Testing. The effect of addition of Nano clay and variation of Hemp/glass fibers will be studied. In the present work, a new Hybrid composite is developed in which Hemp, E glass fibers is reinforced with epoxy resin and with Nano clay.

Hf-Nd isotopic variability in mineral dust from Chinese and Mongolian deserts: implications for sources and dispersal

PubMed Central

Zhao, Wancang; Sun, Youbin; Balsam, William; Lu, Huayu; Liu, Lianwen; Chen, Jun; Ji, Junfeng

2014-01-01

Mineral dust provenances are closely related to the orogenic processes which may have distinct Hf-Nd isotopic signatures. Here we report the clay-sized (<2 μm) Hf-Nd isotope data from Asian dust sources to better constrain the source and transport dynamics of dust deposition in the North Pacific. Our results show that there is a more positive radiogenic Hf isotopic composition with clay-sized fractions than the corresponding bulk sample and a decoupling of the Hf-Nd couplets in the clay formation during the weathering process. The clay-sized Hf-Nd isotopic compositions of the desert samples from the Sino-Korean-Tarim Craton (SKTC) are different from those of the Gobi and deserts from the Central Asian Orogeny Belt (CAOB) due to varying tectonic and weathering controls. The Hf-Nd isotopic compositions of dust in the North Pacific central province (NPC) match closely with those from the Taklimakan, Badain Jaran and adjacent Tengger deserts, implying that the NPC dust was mainly transported from these potential sources by the westerly jet. Our study indicates that dusts from the CAOB Gobi deserts either didn't arrive in NPC or were quantitatively insignificant, but they were likely transported to the North Pacific margin province (NPM) by East Asian winter monsoon. PMID:25060781

Hf-Nd isotopic variability in mineral dust from Chinese and Mongolian deserts: implications for sources and dispersal.

PubMed

Zhao, Wancang; Sun, Youbin; Balsam, William; Lu, Huayu; Liu, Lianwen; Chen, Jun; Ji, Junfeng

2014-07-25

Mineral dust provenances are closely related to the orogenic processes which may have distinct Hf-Nd isotopic signatures. Here we report the clay-sized (<2 μm) Hf-Nd isotope data from Asian dust sources to better constrain the source and transport dynamics of dust deposition in the North Pacific. Our results show that there is a more positive radiogenic Hf isotopic composition with clay-sized fractions than the corresponding bulk sample and a decoupling of the Hf-Nd couplets in the clay formation during the weathering process. The clay-sized Hf-Nd isotopic compositions of the desert samples from the Sino-Korean-Tarim Craton (SKTC) are different from those of the Gobi and deserts from the Central Asian Orogeny Belt (CAOB) due to varying tectonic and weathering controls. The Hf-Nd isotopic compositions of dust in the North Pacific central province (NPC) match closely with those from the Taklimakan, Badain Jaran and adjacent Tengger deserts, implying that the NPC dust was mainly transported from these potential sources by the westerly jet. Our study indicates that dusts from the CAOB Gobi deserts either didn't arrive in NPC or were quantitatively insignificant, but they were likely transported to the North Pacific margin province (NPM) by East Asian winter monsoon.

Spatially resolved nanoscale observations of soil carbon multidecadal persistence

NASA Astrophysics Data System (ADS)

Lutfalla, S.; Chenu, C.; Bernard, S.; Le Guillou, C.; Barré, P.

2015-12-01

Assessing how mineral surfaces, especially at small scale, can protect soil organic carbon (SOC) from biodegradation is crucial. The question we address in this work is whether different mineral species lead to different organo-mineral interactions and stabilize different quantities of SOM and different types of SOC. Here we used the unique opportunity offered by long term bare fallows (BF) to study in situ C dynamics in several fine fractions of a silty loam soil. With no vegetation i.e. no external input of fresh C, the plant-free soil of the Versailles 42 Plots (INRA, France) has been progressively enriched in persistent SOC during the 80 years of BF. Contrasted mineral phases of the clay size fraction were isolated by size fractionation on samples from 5 different dates (0, 10, 22, 52, and 79 years after the beginning of the BF, four field replicates per date). Four fractions were studied: total clays (< 2 μm), and three sub fractions in the clay (fine clay: 0 - 0.05 μm, intermediate clay: 0.05 - 0.2 μm, and coarse clay: 0.2 - 2 μm). X-ray diffraction analyses showed contrasted mineralogies in the fine and intermediate clay (smectite and mixed layered illite/smectite) as opposed to the coarse clay (smectite, illite, kaolinite and mixed layered I/S). We performed CHN elemental analysis and synchrotron based spectroscopy and microscopy (NEXAFS bulk and STXM at the carbon K edge of 280 eV, CLS Saskatoon, Canada) to study the dynamics, the distribution and the chemical speciation of the SOC in these fractions. The quantity of C appears to be stabilized after 50 years of BF, even though the dynamics are different for the three clay fractions. Indeed, coarse and intermediate clays have the same final C content but coarse clays lose more C. Fine clay experiences the highest C losses and displays the highest final C content suggesting that fine clays contained more labile C and more persistent C. In all fractions, C:N ratios are really low (below 8) and are decreasing with time, evidencing the dominant presence of microbial SOC. STXM-NEXAFS data shows that, in the fine and intermediate clay fractions, during the first 50 years of BF all mineral particles are associated with SOC. On the contrary, in the coarse clays, SOC displays more diversity: the chemical signature is more diverse and mineral particles not associated with SOC appear more quickly.

Evaluating Weathering of Food Packaging Polyethylene-Nano-clay Composites: Release of Nanoparticles and their Impacts.

PubMed

Han, Changseok; Zhao, Amy; Varughese, Eunice; Sahle-Demessie, E

2018-01-01

Nano-fillers are increasingly incorporated into polymeric materials to improve the mechanical, barrier or other matrix properties of nanocomposites used for consumer and industrial applications. However, over the life cycle, these nanocomposites could degrade due to exposure to environmental conditions, resulting in the release of embedded nanomaterials from the polymer matrix into the environment. This paper presents a rigorous study on the degradation and the release of nanomaterials from food packaging composites. Films of nano-clay-loaded low-density polyethylene (LDPE) composite for food packaging applications were prepared with the spherilene technology and exposed to accelerated weathering of ultraviolet (UV) irradiation or low concentration of ozone at 40 °C. The changes in the structural, surface morphology, chemical and physical properties of the films during accelerated weathering were investigated. Qualitative and quantitative changes in properties of pristine and aged materials and the release of nano-clay proceeded slowly until 130 hr irradiation and then accelerated afterward resulting complete degradation. Although nano-clay increased the stability of LDPE and improved thermal and barrier properties, they accelerated the UV oxidation of LDPE. With increasing exposure to UV, the surface roughness, chemiluminescence index, and carbonyl index of the samples increased while decreasing the intensity of the wide-angle X-ray diffraction pattern. Nano-clay particles with sizes ranging from 2-8 nm were released from UV and ozone weathered composite. The concentrations of released nanoparticles increased with an increase in aging time. Various toxicity tests, including reactive oxygen species generation and cell activity/viability were also performed on the released nano-clay and clay polymer. The released nano-clays basically did not show toxicity. Our combined results demonstrated the degradation properties of nano-clay particle-embedded LDPE composites toxicity of released nano-clay particles to A594 adenocarcinomic human alveolar basal epithelial cells was observed, which will help with future risk based-formulations of exposure.

Cell block samples from malignant pleural effusion might be valid alternative samples for anaplastic lymphoma kinase detection in patients with advanced non-small-cell lung cancer.

PubMed

Zhou, Jianya; Yao, Hongtian; Zhao, Jing; Zhang, Shumeng; You, Qihan; Sun, Ke; Zou, Yinying; Zhou, Caicun; Zhou, Jianying

2015-06-01

To evaluate the clinical value of cell block samples from malignant pleural effusion (MPE) as alternative samples to tumour tissue for anaplastic lymphoma kinase (ALK) detection in patients with advanced non-small-cell lung cancer (NSCLC). Fifty-two matched samples were eligible for analysis. ALK status was detected by Ventana immunohistochemistry (IHC) (with the D5F3 clone), reverse transcription polymerase chain reaction (RT-PCR) and fluorescence in-situ hybridization (FISH) in MPE cell block samples, and by FISH in tumour tissue block samples. In total, ALK FISH results were obtained for 52 tumour tissue samples and 41 MPE cell block samples. Eight cases (15.4%) were ALK-positive in tumour tissue samples by FISH, and among matched MPE cell block samples, five were ALK-positive by FISH, seven were ALK-positive by RT-PCR, and eight were ALK-positive by Ventana IHC. The ALK status concordance rates between tumour tissue and MPE cell block samples were 78.9% by FISH, 98.1% by RT-PCR, and 100% by Ventana IHC. In MPE cell block samples, the sensitivity and specificity of Ventana IHC (100% and 100%) and RT-PCR (87.5% and 100%) were higher than those of FISH (62.5% and 100%). Malignant pleural effusion cell block samples had a diagnostic performance for ALK detection in advanced NSCLC that was comparable to that of tumour tissue samples. MPE cell block samples might be valid alternative samples for ALK detection when tissue is not available. Ventana IHC could be the most suitable method for ALK detection in MPE cell block samples. © 2014 John Wiley & Sons Ltd.

Antibacterial performance of nano polypropylene filter media containing nano-TiO2 and clay particles

NASA Astrophysics Data System (ADS)

Shafiee, Sara; Zarrebini, Mohammad; Naghashzargar, Elham; Semnani, Dariush

2015-10-01

Disinfection and elimination of pathogenic microorganisms from liquid can be achieved by filtration process using antibacterial filter media. The advent of nanotechnology has facilitated the introduction of membranes consisting of nano-fiber in filtration operations. The melt electro-spun fibers due to their extremely small diameters are used in the production of this particular filtration medium. In this work, antibacterial polypropylene filter medium containing clay particles and nano-TiO2 were made using melt electro-spun technology. Antibacterial performance of polypropylene nano-filters was evaluated using E. coli bacteria. Additionally, filtration efficiency of the samples in terms fiber diameter, filter porosity, and fiber distribution using image processing technique was determined. Air permeability and dust aerosol tests were conducted to establish the suitability of the samples as a filter medium. It was concluded that as far as antibacterial property is concerned, nano-fibers filter media containing clay particles are preferential to similar media containing TiO2 nanoparticles.

Potentialité d'utilisation d'argiles marocaines de Jbel Kharrou dans l'industrie céramique

NASA Astrophysics Data System (ADS)

El Yakoubi, Nadia; Aberkan, M'hamed; Ouadia, Mohamed

2006-08-01

The Ordovician clays of Jbel Kharrou (Rehamna, Morocco) have been studied for their use in ceramic industry. The realised studies were carried out on two samples B1 and B2, the most representative, taken from a clay dominated formation that outcrops 25 km east of the Skhour Rehamna city. The chemical analyses, mineralogical studies and advanced technological tests undertaken on the two samples indicate that these clays can be considered as non-refractory material, so they can be used to the manufacturing of ceramic products: soil and wall tiles, sanitary, pottery, etc. The tested briquettes, cooked at 1040 °C, remain flat, without deformation or defects; they are of cream white dye. These briquettes show a high mechanical resistance to the flexion, the loss in weight remains tolerable with cooking, lightly elevated (12% ); it can be corrected by the addition of a grease-remover. To cite this article: N. El Yakoubi et al., C. R. Geoscience 338 (2006).

X-ray Diffraction and Rietveld Refinement in Deferrified Clays for Forensic Science.

PubMed

Prandel, Luis V; Melo, Vander de F; Brinatti, André M; Saab, Sérgio da C; Salvador, Fábio A S

2018-01-01

Soil vestiges might provide information about a crime scene. The Rietveld method with X-ray diffraction data (RM-XRD) is a nondestructive technique that makes it possible to characterize minerals present in the soils. Soil clays from the metropolitan region of Curitiba (Brazil) were submitted to DCB treatment and analyzed using XRD with CuK α radiation in the step-scan mode (0.02° 2θ/5 s). The GSAS+EXPGUI software was used for RM refinement. The RM-XRD results, together with the principal component analysis (PCA) (52.6% total variance), showed the kaolinite predominance in most analyzed samples and the highest quartz contents in "site 1." Higher anatase, and gibbsite and muscovite contents influenced discrimination, mainly in "site 3" and "site 1," respectively. These results were enough to discriminate clays of four sites and two horizons using a reduced amount of sample showing that the technique can be applied to the investigation into soil vestiges. © 2017 American Academy of Forensic Sciences.

The Leaching of Aluminium In Spanish Clays, Coal Mining Wastes and Coal Fly Ashes by Sulphuric Acid.

NASA Astrophysics Data System (ADS)

Fernández, A. M.; Ibáñez, J. L.; Llavona, M. A.; Zapico, R.

The acid leaching of aluminium from several non traditional ores, bayerite, kaolinite, different clays, coal mining wastes and coal fly ashes, and the kinetic of their dissolution are described. The effects of time, temperature, acid concentration, sample calcination, particle size were examined. The leaching of aluminium is dependent on acid concentration and strongly on temperature. Generally, the time to reach a fixed percentage of dissolution decreases with increasing acid concentration in the range 6% to 40% acid by weight. On clays and coal mining wastes a good relation between Al removal and ratio kaolinite/illite was also observed at all temperatures and acid concentration tested. Coal fly ashes are particles that were heated at very high temperatures in the power station and Al compounds were transformed into mullite and so Al recovery was minor. Several rate equations describing the kinetics of the leach reaction were discussed and Kinetic parameters and activation energy values of samples are presented.

Application of woven tires waste as soft clay subgrade reinforcement for preventing highway structural failure

NASA Astrophysics Data System (ADS)

Apriyono, Arwan; Sumiyanto, Gusmawan, Dadan Deri

2017-03-01

This study presents the application of woven waste tires as soft clay subgrade reinforcement for preventing highway structural failure, reducing construction cost and minimizing environmental hazards associated with the increasingly large amount of waste tires in Indonesia. To his end, we performed experiments using five stripe distance variations of woven tires - i.e. 2, 2.5, 3, 3.5 and 4 cm. Five soft clay samples were made and each was reinforced using each of these woven tires. The California Bearing Ratio (CBR) test was conducted on each softclay sample and the CBR value was determined from the stress on the displacement of 0.10 and 0.20 inch. The correlation between CBR value and strip distance was used to infer the optimum woven tires strip distance, indicated by the largest CBR value. The result suggests that the strip distance of 3 cm is optimum with corresponding CBR value of ˜20%, which is 115% increase compared to softclay without reinforcement.

Stabilization Of Marine Clay Using Biomass Silica-Rubber Chips Mixture

NASA Astrophysics Data System (ADS)

Marto, Aminaton; Ridzuan Jahidin, Mohammed; Aziz, Norazirah Abdul; Kasim, Fauziah; Zurairahetty Mohd. Yunus, Nor

2016-11-01

Marine clay is found widely along the coastal area and had caused expensive solutions in the construction of coastal highways. Hence, soil stabilization was suggested by some consultant to increase the strength of this soil in order to meet the highway construction requirement and also to achieve the specification for the development. Biomass Silica (BS), particularly the SH85 as a non-traditional stabilisation method, has been gaining more interest from the engineers recently. Rubber chips (RC), derived from waste rubber tyres, are considered ‘green’ element and had been used previously in some geotechnical engineering works. This paper presents the effect of using BS and RC as a mixture (BS-RC mixture), to increase the strength of marine clay for highway construction. Samples of marine clay, obtained from the West Coast Expressway project at Teluk Intan, Perak, were oven dried and grind to fine-grained sized. The marine clay was mixed with 9 % by weight proportion of BS- RC; that were 8%-l% and 7%-2%, respectively. For comparison purposes the result of BS-RC was compared to the result of stabilization by using 9% BS only. Laboratory tests were then carried out to determine the Atterberg limits and compaction characteristics of the untreated and treated marine clay. The Unconfined Compressive Strength (UCS) of the untreated and treated marine clays, compacted at the optimum moisture content was later obtained. The treated marine clay was tested at 0, 3 and 7 days curing periods. The results show that the Plasticity Index of BS-RC treated marine clay was lower than the untreated marine clay. From the UCS test results, it is shown that BS-RC mixtures had significantly improved the strength of marine clay. With the same percentage of 9% BS-RC, the increased of BS from 7% to 8% increased the UCS further to about six times more than untreated marine clay soils in 7 days curing period. The strength gained by using BS-RC at 8%-1% is slightly below the strength by using 9% BS only. From the experimental results, it is shown that BS, in the form of SH85, admixed with rubber chips could significantly improve the strength of marine clay soils.

Mössbauer studies on some Argentinian soil: Mollisols from Bahia Blanca

NASA Astrophysics Data System (ADS)

Saragovi, C.; Labenski, F.; Duhalde, S. M.; Acebal, S.; Venegas, R.

1994-12-01

Clay fractions of a Mollisol sample as is, treated with ammonium oxalate (AO), with dithionite-citrate-bicarbonate (DCB) and with dithionite-ethilene-diamine-tetraacetic acid (D-EDTA) methods, were studied. Illite-montmorillonites together with hematites, goethites and maghemites, all of the AI-substituted and with a wide range of sizes, were identified. It is found that the AO attack extracts little iron, whereas the other two attacks extract the magnetic signal. Furthermore, the DCB attack facilitates the reduction of the Fe3+ ions, while the D-EDTA method does not. Instead, this attack extracts more clay mineral Fe ions. A comparison with large grain soil samples is made.

Arsenic Groundwater Contamination in Bengal: a Coupled Geochemical and Geophysical Study

NASA Astrophysics Data System (ADS)

Charlet, L.; Ansari, A. A.; Dietrich, M.; Latscha, A.; LeBeux, A.; Chatterjee, D.; Mallik, S. B.

2001-05-01

Arsenic contamination in drinking water is a problem of great concern in Ganges delta region, and could be one of the largest natural calamity in the world. In the present study, a contamination plume located in the Lalpur area (Chakdaha Block, Nadia District, West Bengal, India) was studied. A coupled geochemical and geophysical approach was employed to understand the mechanism of arsenic mobilisation from the sediments to groundwater, as a first step towards a global explanation of the phenomenon for other contaminated areas in the Ganges delta. The groundwater As concentration, in the 10 km x 10 km studied area, ranges from 10 to 500 ppb. In situ chemical speciation of arsenic was carried out and various geochemical parameters were measured in representative contaminated wells to interpret the mobilization mechanism in terms of redox kinetics. Through geophysical investigations, subsurface lithology, sediment depositional and geomorphological characteristics were determined and correlated with the arsenic contamination processes. From a geomorphological viewpoint, the contaminated area is located in an abandoned paleochannel of the Hooghly river, interpreted as the active site of deposition of fine sediments which were preserved as clay pockets at certain depths. These clay pockets are rich in organic matter, which may be the driving force for redox potential change and thus, may have driven the mobilisation of arsenic in groundwater. The clay pockets rich in organic matter presumably represent the major reservoir where arsenic is sitting and getting released due to redox mechanism. They are sampled at present. A piezometric depression cone characterized by a radial groundwater flow is located underneath the highly populated Lalpur area. The arsenic plume appears to migrate from the Hooghly river towards the cone of depression following the water flowpath, and this shall be verified in forthcoming field campaigns. As (III) constitutes 42 % of the total As concentration. It is several times more toxic than As (V). The As (III) / As (V) and S (-II) / S (VI) ratios are not at equilibrium with the Eh measured in groundwater. The groundwater is at equilibrium with Ba(II) and Fe(II) arsenate minerals, barite and siderite. The reactive transport modeling of the data is explored.

Characterizing the interaction among bullet, body armor, and human and surrogate targets.

PubMed

Shen, Weixin; Niu, Yuqing; Bykanova, Lucy; Laurence, Peter; Link, Norman

2010-12-01

This study used a combined experimental and modeling approach to characterize and quantify the interaction among bullet, body armor, and human surrogate targets during the 10-1000 μs range that is crucial to evaluating the protective effectiveness of body armor against blunt injuries. Ballistic tests incorporating high-speed flash X-ray measurements were performed to acquire the deformations of bullets and body armor samples placed against ballistic clay and gelatin targets with images taken between 10 μs and 1 ms of the initial impact. Finite element models (FEMs) of bullet, armor, and gelatin and clay targets were developed with material parameters selected to best fit model calculations to the test measurements. FEMs of bullet and armor interactions were then assembled with a FEM of a human torso and FEMs of clay and gelatin blocks in the shape of a human torso to examine the effects of target material and geometry on the interaction. Test and simulation results revealed three distinct loading phases during the interaction. In the first phase, the bullet was significantly slowed in about 60 μs as it transferred a major portion of its energy into the body armor. In the second phase, fibers inside the armor were pulled toward the point of impact and kept on absorbing energy until about 100 μs after the initial impact when energy absorption reached its peak. In the third phase, the deformation on the armor's back face continued to grow and energies inside both armor and targets redistributed through wave propagation. The results indicated that armor deformation and energy absorption in the second and third phases were significantly affected by the material properties (density and stiffness) and geometrical characteristics (curvature and gap at the armor-target interface) of the targets. Valid surrogate targets for testing the ballistic resistance of the armor need to account for these factors and produce the same armor deformation and energy absorption as on a human torso until at least about 100 μs (maximum armor energy absorption) or more preferably 300 μs (maximum armor deformation).

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

NASA Astrophysics Data System (ADS)

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

2009-02-01

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

Variable Temperature Infrared Spectroscopy Investigation of Benzoic Acid Interactions with Montmorillonite Clay Interlayer Water.

PubMed

Nickels, Tara M; Ingram, Audrey L; Maraoulaite, Dalia K; White, Robert L

2015-07-01

Molecular interactions between benzoic acid and cations and water contained in montmorillonite clay interlayer spaces are characterized by using variable temperature diffuse reflection infrared Fourier transform spectroscopy (VT-DRIFTS). Using sample perturbation and difference spectroscopy, infrared spectral changes resulting from removal of interlayer water and associated changes in local benzoic acid environments are identified. Difference spectra features can be correlated with changes in specific molecular vibrations that are characteristic of benzoic acid molecular orientation. Results suggest that the carboxylic acid functionality of benzoic acid interacts with interlayer cations through a bridging water molecule and that this interaction is affected by the nature of the cation present in the clay interlayer space.

Strength and Stiffness Development in Soft Soils: A FESEM aided Soil Microstructure Viewpoint

NASA Astrophysics Data System (ADS)

Wijeyesekera, D. C.; Ho, M. H.; Bai, X.; Bakar, I.

2016-07-01

This paper opens with an overview of the debatable definition of soft soil that goes beyond a (CH) organic / inorganic clay and OH peat to include weakly cemented periglacial deposits of loess and alike. It then outlines the findings obtained from stiffness test on cement-stabilised soft clay. The findings are complemented with a microstructure viewpoint obtained using field emission scanning electron microscope (FESEM). Research also comprised of making cylindrical stabilised clay samples, prepared in the laboratory with various rubber chips contents and cement, and then aged for 28 days. The samples were then subjected to unconfined compressive strength (UCS) test and observations were also made of its microstructure using the FESEM. The impact of the soil microstructure on the stiffness result was studied both with the stabilized soil and also of some of the natural undisturbed loess soils. Sustainability aspect and the potential of the use of rubber chips and sand as additives to cement stabilisation are also discussed. The overall test results indicated that rubber chips and sand contributed to the improvement in unconfined compressive strength (qu). The derogatory influence of moisture on the stiffness of the stabilised clay was studied simultaneously. SEM micrographs are presented that show bonding of cement, rubber chips/ sand and soft clay, granular units and aggregated / agglomerated units in loess. The paper concludes with observations on the dependence of soil microstructure on the soil strength and deformability and even collapsibility of the loess. Current practices adopted as engineering solutions to these challenging soils are outlined.

Estimation of landslide-triggering factors using clay minerals, ASTER satellite image and GIS in the Busan area, southeastern Korea

NASA Astrophysics Data System (ADS)

Jeong, G. C.; Kim, M. G.; Choi, J. J.; Ryu, J. O.; Nho, J. G.; Choo, C. O.

2016-12-01

This study aims at estimating landslide-inducing factors such as extreme rainfall, slope, and geological factors in Busan city, southeastern Korea, using clay mineralogy, DM analysis and DB construction in order to develop the landslide evaluation standards suitable for the country. GIS-based data collected from the study area include geological maps, topological maps, soil maps, forest maps and others in the DB construction. Data extraction and processing for landslide-induced factors consist of expandable clay minerals identified using XRD, along with XRF and weathering sensitivity analysis and fundamental soil analysis on 38 bulk samples composed of weathered rocks and soils. Finally landslide sensibility maps were constructed using ArcGIS, together with ASTER satellite images for identifying clay minerals on regional areas helpful for saving time and money. In Mt. Cheonma, 16 samples are composed of quartz, albite, illite, vermiculite, and kaolinite, with little difference in mineralogy. In Mt. Hwangryeong and Mt. Geumryeun, 12 samples consist of quartz, albite, illite, vermiculite, kaolinite and hornblende, with little difference in mineralogy. In Mt. Songhak, 10 samples are composed of quartz, illite, vermiculite, and kaolinite. Quartz, albite and illite are abundant in most samples, regardless of sites studied. IDW interpolation method was applied to the Busan area. The resolution of space grids consists of 5 m x 5 m. Especially, illite was used as the most effective factor that induces landslide using IDW interpolation and ASTER satellite images. In conclusion, sensibility maps constructed using 16 layers including illite content, weathered sensibility are well in accordance with the real sites where landslides took place, showing that areas with high sensibility are closely related to the high frequencies of landslide. This research was supported by the Public Welfare & Safety Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT & Future Planning (grant number 2012M3A2A1050976)

Water uptake of clay and desert dust aerosol particles at sub- and supersaturated water vapor conditions.

PubMed

Herich, Hanna; Tritscher, Torsten; Wiacek, Aldona; Gysel, Martin; Weingartner, Ernest; Lohmann, Ulrike; Baltensperger, Urs; Cziczo, Daniel J

2009-09-28

Airborne mineral dust particles serve as cloud condensation nuclei (CCN), thereby influencing the formation and properties of warm clouds. It is therefore of atmospheric interest how dust aerosols with different mineralogy behave when exposed to high relative humidity (RH) or supersaturation (SS) with respect to liquid water. In this study the subsaturated hygroscopic growth and the supersaturated cloud condensation nucleus activity of pure clays and real desert dust aerosols were determined using a hygroscopicity tandem differential mobility analyzer (HTDMA) and a cloud condensation nuclei counter (CCNC), respectively. Five different illite, montmorillonite and kaolinite clay samples as well as three desert dust samples (Saharan dust (SD), Chinese dust (CD) and Arizona test dust (ATD)) were investigated. Aerosols were generated both with a wet and a dry disperser. The water uptake was parameterized via the hygroscopicity parameter kappa. The hygroscopicity of dry generated dust aerosols was found to be negligible when compared to processed atmospheric aerosols, with CCNC derived kappa values between 0.00 and 0.02 (the latter corresponds to a particle consisting of 96.7% by volume insoluble material and approximately 3.3% ammonium sulfate). Pure clay aerosols were generally found to be less hygroscopic than natural desert dust particles. The illite and montmorillonite samples had kappa approximately 0.003. The kaolinite samples were less hygroscopic and had kappa=0.001. SD (kappa=0.023) was found to be the most hygroscopic dry-generated desert dust followed by CD (kappa=0.007) and ATD (kappa=0.003). Wet-generated dust showed an increased water uptake when compared to dry-generated samples. This is considered to be an artifact introduced by redistribution of soluble material between the particles. Thus, the generation method is critically important when presenting such data. These results indicate any atmospheric processing of a fresh mineral dust particle which leads to the addition of more than approximately 3% soluble material will significantly enhance its hygroscopicity and CCN activity.

Clay mineralogy and source-to-sink transport processes of Changjiang River sediments in the estuarine and inner shelf areas of the East China Sea

NASA Astrophysics Data System (ADS)

Zhao, Yifei; Zou, Xinqing; Gao, Jianhua; Wang, Chenglong; Li, Yali; Yao, Yulong; Zhao, Wancang; Xu, Min

2018-02-01

We examined the source-to-sink sediment transport processes from the Changjiang River to the estuarine coastal shelf area by analyzing the clay mineral assemblages in suspended sediment samples from the Changjiang River catchment and surface samples from the estuarine coastal shelf area following the impoundment of the Three Gorges Dam (TGD) in 2003. The results indicate that the clay mineral compositions throughout the study area are dominated by illite, with less abundant kaolinite and chlorite and scarce smectite. The clay minerals display distinct differences in the tributaries and exhibit obvious changes in the trunk stream compared with the periods before 2003, and the source of sediment has largely shifted to the mid- to lower reaches of the river after 2003. Spatially, the clay mineral assemblages in the estuarine area define two compositionally distinct provinces. Province I covers the mud area of the Changjiang River estuary and the Zhe-Min coastal region, where sediment is primarily supplied by the Changjiang River. Province II includes part of the Changjiang River estuary and the southeastern portion of the study area, where the sediment is composed of terrestrial material from the Changjiang River and re-suspended material from the Huanghe River carried by the Jiangsu coastal current. Moreover, the other smaller rivers in China (including the Oujiang and Minjiang rivers of mainland China and the rivers of West Taiwan) also contribut sediments to the estuarine and inner shelf areas. In general, the clay mineral assemblages in the Changjiang River estuarine area are have mainly been controlled by sediment supplied from upstream of the Changjiang River tributaries. However, since the completion of the TGD in 2003, the mid- to downstream tributaries have become the main source of sediments from the Changjiang catchment into the East China Sea. These analyses further demonstrate that the coastal currents and the decrease in the sediment load of the river have the greatest impacts on the distribution and transport of clay minerals assemblages in the sediments.

Macroaggregation and soil organic carbon restoration in a highly weathered Brazilian Oxisol after two decades under no-till.

PubMed

de Oliveira Ferreira, Ademir; de Moraes Sá, João Carlos; Lal, Rattan; Tivet, Florent; Briedis, Clever; Inagaki, Thiago Massao; Gonçalves, Daniel Ruiz Potma; Romaniw, Jucimare

2018-04-15

Conclusions based on studies of the impacts of soil organic carbon (SOC) fractions and soil texture on macroaggregation and SOC stabilization in long-term (>20years) no-till (NT) fields remain debatable. This study was based on the hypothesis that the amount and frequency of biomass-C input associated with NT can be a pathway to formation of macroaggregates and to SOC buildup. The objectives were to: 1) assess the macroaggregate distribution (proportional mass, class mass) and the SOC and particulate organic carbon (POC) stocks of extra-large (8-19mm), large (2-8mm) and small (0.25-2mm) macroaggregate size classes managed for two decades by NT, and 2) assess the recovery of SOC stocks in extra-large macroaggregates compared to adjacent native vegetation (Andropogon sp., Aristida sp., Paspalum sp., and Panicum sp.). The crop rotation systems were: soybean (Glycine max L.), maize (Zea mays L.) and beans (Phaseolus vulgaris L.) in summer; and black oat (Avena strigosa Schreb), white oat (Avena sativa), vetch (Vicia sativa L.), black oat.+vetch (Avena strigosa Schreb+vetch) and wheat (Triticum aestivum L.) in winter. The experimental was laid out as 2×2 randomized block factorial with 12 replicates of a NT experiment established in 1997 on two highly weathered Oxisols. The factors comprised of: (a) two soil textural types: clay loam and sandy clay, and (b) two sampling depths: 0-5 and 5-20cm. The three classes of macroaggregates were obtained by wet sieving, and the SOC content was determined by the dry combustion method. The extra-large macroaggregate classes in 0-20cm depth for sandy clay (SdC) and clay loam (CL) Oxisol represented 75.2 and 72.4% of proportional mass, respectively. The SOC and POC stocks among macroaggregate classes in 0-5 and 5-20cm depths decreased in the order: 8-19mm>2-8mm ≈ 0.25-2mm. The SdC plots under soybean/maize at 3:1 ratio recovered 58.3%, while those at 1:1 ratio (high maize frequency) in CL recovered 73.1% of SOC stock in the extra-large macroaggregates compared with the same under native vegetation for 0-20cm depth. Thus, partial restoration of the SOC stock in original extra-large macroaggregate confirms the hypothesis that NT through higher maize cultivation frequency can be a pathway to fomation of macroaggregates and SOC buildup. Copyright © 2017 Elsevier B.V. All rights reserved.

High Concentration of Red Clay as an Alternative for Antibiotics in Aquaculture.

PubMed

Jung, Jaejoon; Jee, Seung Cheol; Sung, Jung-Suk; Park, Woojun

2016-01-01

The use of antibiotics in aquaculture raises environmental and food safety concerns because chronic exposure of an aquatic ecosystem to antibiotics can result in the spread of antibiotic resistance, bioaccumulation of antibiotics in the organisms, and transfer of antibiotics to humans. In an attempt to overcome these problems, high-concentration red clay was applied as an alternative antibiotic against the following common fish pathogens: Aeromonas salmonicida, Vibrio alginolyticus, and Streptococcus equinus. The growth of A. salmonicida and V. alginolyticus was retarded by red clay, whereas that of S. equinus was promoted. Phase contrast and scanning electron microscopy analyses confirmed the attachment of red clay on cell surfaces, resulting in rapid gravitational removal and cell surface damage in both A. salmonicida and V. alginolyticus, but not in S. equinus. Different cell wall properties of grampositive species may explain the unharmed cell surface of S. equinus. Significant levels of oxidative stress were generated in only the former two species, whereas significant changes in membrane permeability were found only in S. equinus, probably because of its physiological adaptation. The bacterial communities in water samples from Oncorhynchus mykiss aquacultures supplemented with red clay showed similar structure and diversity as those from oxytetracycline-treated water. Taken together, the antibiotic effects of high concentrations of red clay in aquaculture can be attributed to gravitational removal, cell surface damage, and oxidative stress production, and suggest that red clay may be used as an alternative for antibiotics in aquaculture.

Removal of crude oil polycyclic aromatic hydrocarbons via organoclay-microbe-oil interactions.

PubMed

Ugochukwu, Uzochukwu C; Fialips, Claire I

2017-05-01

Clay minerals are quite vital in biogeochemical processes but the effect of organo-clays in the microbial degradation of crude oil polycyclic aromatic hydrocarbons is not well understood. The role of organo-saponite and organo-montmorillonite in comparison with the unmodified clays in crude oil polycyclic aromatic hydrocarbons (PAHs) removal via adsorption and biodegradation was studied by carrying out microcosm experiments in aqueous clay/oil systems with a hydrocarbon degrading microbial community that is predominantly alcanivorax spp. Montmorillonite and saponite samples were treated with didecyldimethylammonium bromide to produce organo-montmorillonite and organo-saponite used in this study. Obtained results indicate that clays with high cation exchange capacity (CEC) such as montmorillonite produced organo-clay (organomontmorillonite) that was not stimulatory to biodegradation of crude oil polycyclic aromatic compounds, especially the low molecular weight (LMW) ones, such as dimethylnaphthalenes. It is suggested that interaction between the organic phase of the organo-clay and the crude oil PAHs which is hydrophobic in nature must have reduced the availability of the polycyclic aromatic hydrocarbons for biodegradation. Organo-saponite did not enhance the microbial degradation of dimethylnaphthalenes but enhanced the biodegradation of some other PAHs such as phenanthrene. The unmodified montmorillonite enhanced the microbial degradation of the PAHs and is most likely to have done so as a result of its high surface area that allows the accumulation of microbes and nutrients enhancing their contact. Copyright © 2017 Elsevier Ltd. All rights reserved.

Tertiary carbonate-dissolution cycles on the Sierra Leone Rise, eastern equatorial Atlantic Ocean

USGS Publications Warehouse

Dean, W.E.; Gardner, J.V.; Cepek, P.

1981-01-01

Most of the Tertiary section on Sierra Leone Rise off northwest Africa consists of chalk, marl, and limestone that show cyclic alterations of clay-rich and clay-poor beds about 20-60 cm thick. On the basis of biostratigraphic accumulation rates, the cycles in Oligocene and Miocene chalk have periods which average about 44,000 years, and those in Eocene siliceous limestone have periods of 4000-27,000 years. Several sections were sampled in detail to further define the cycles in terms of content of CaCO3, clay minerals, and relative abundances of calcareous nannofossils. Extending information gained by analyses of Pleistocene cores from the continental margin of northwest Africa to the Tertiary cycles on Sierra Leone Rise, both dilution by noncarbonate material and dissolution of CaCO3 could have contributed to the observed relative variations in clay and CaCO3. However, dissolution of CaCO3 as the main cause of the carbonate-clay cycles on the Sierra Leone Rise, rather than dilution by clay, is suggested by the large amount of change (several thousand percent) in terrigenous influx required to produce the observed variations in amount of clay and by the marked increase in abundance of dissolution-resistant discoasters relative to more easily dissolved coccoliths in low-carbonate parts of cycles. The main cause of dissolution of CaCO3 was shoaling of the carbonate compensation depth (CCD) during the early Neogene and climatically induced fluctuations in the thickness of Antarctic Bottom Water. ?? 1981.

Tc(VII) and Cr(VI) Interaction with Naturally Reduced Ferruginous Smectite from a Redox Transition Zone.

PubMed

Qafoku, Odeta; Pearce, Carolyn I; Neumann, Anke; Kovarik, Libor; Zhu, Mengqiang; Ilton, Eugene S; Bowden, Mark E; Resch, Charles T; Arey, Bruce W; Arenholz, Elke; Felmy, Andrew R; Rosso, Kevin M

2017-08-15

Fe(II)-rich clay minerals found in subsurface redox transition zones (RTZs) can serve as important sources of electron equivalents limiting the transport of redox-active contaminants. While most laboratory reactivity studies are based on reduced model clays, the reactivity of naturally reduced field samples remains poorly explored. Characterization of the clay size fraction of a fine-grained unit from the RTZ interface at the Hanford site, Washington, including mineralogy, crystal chemistry, and Fe(II)/(III) content, indicates that ferruginous montmorillonite is the dominant mineralogical component. Oxic and anoxic fractions differ significantly in Fe(II) natural content, but Fe TOTAL remains constant, demonstrating no Fe loss during its reduction-oxidation cyclings. At native pH of 8.6, the anoxic fraction, despite its significant Fe(II), ∼23% of Fe TOTAL , exhibits minimal reactivity with TcO 4 - and CrO 4 2- and much slower reaction kinetics than those measured in studies with biologically/chemically reduced model clays. Reduction capacity is enhanced by added/sorbed Fe(II) (if Fe(II) SORBED > 8% clay Fe(II) LABILE ); however, the kinetics of this conceptually surface-mediated reaction remain sluggish. Surface-sensitive Fe L-edge X-ray absorption spectroscopy shows that Fe(II) SORBED and the resulting reducing equivalents are not available in the outermost few nanometers of clay surfaces. Slow kinetics thus appear related to diffusion-limited access to electron equivalents retained within the clay mineral structure.

Clay mineralogy of surface sediments as a tool for deciphering river contributions to the Cariaco Basin (Venezuela)

NASA Astrophysics Data System (ADS)

Bout-Roumazeilles, V.; Riboulleau, A.; du Châtelet, E. Armynot; Lorenzoni, L.; Tribovillard, N.; Murray, R. W.; Müller-Karger, F.; Astor, Y. M.

2013-02-01

The mineralogical composition of 95 surface sediment samples from the Cariaco Basin continental shelf and Orinoco delta was investigated in order to constrain the clay-mineral main provenance and distribution within the Cariaco Basin. The spatial variability of the data set was studied using a geo-statistical approach that allows drawing representative clay-mineral distribution maps. These maps are used to identify present-day dominant sources for each clay-mineral species in agreement with the geological characteristics of the main river watersheds emptying into the basin. This approach allows (1) identifying the most distinctive clay-mineral species/ratios that determine particle provenance, (2) evaluating the respective contribution of local rivers, and (3) confirming the minimal present-day influence of the Orinoco plume on the Cariaco Basin sedimentation. The Tuy, Unare, and Neveri Rivers are the main sources of clay particles to the Cariaco Basin sedimentation. At present, the Tuy River is the main contributor of illite to the western part of the southern Cariaco Basin continental shelf. The Unare River plume, carrying smectite and kaolinite, has a wide westward propagation, whereas the Neveri River contribution is less extended, providing kaolinite and illite toward the eastern Cariaco Basin. The Manzanares, Araya, Tortuga, and Margarita areas are secondary sources of local influence. These insights shed light on the origin of present-day terrigenous sediments of the Cariaco Basin and help to propose alternative explanations for the temporal variability of clay mineralogy observed in previously published studies.

Mineralogy and geochemistry of the Lower Cretaceous siliciclastic rocks of the Morita Formation, Sierra San José section, Sonora, Mexico

NASA Astrophysics Data System (ADS)

Madhavaraju, J.; Pacheco-Olivas, S. A.; González-León, Carlos M.; Espinoza-Maldonado, Inocente G.; Sanchez-Medrano, P. A.; Villanueva-Amadoz, U.; Monreal, Rogelio; Pi-Puig, T.; Ramírez-Montoya, Erik; Grijalva-Noriega, Francisco J.

2017-07-01

Clay mineralogy and geochemical studies were carried out on sandstone and shale samples collected from the Sierra San José section of the Morita Formation to infer the paleoclimate and paleoweathering conditions that prevailed in the source region during the deposition of these sediments. The clay mineral assemblages (fraction < 2 μm) of the Sierra San José section are composed of chlorite and illite. The abundance of illite and chlorite in the studied samples suggest that the physical weathering conditions were dominant over chemical weathering. Additionally, the illite and chlorite assemblages reflect arid or semi-arid climatic conditions in the source regions. K2O/Al2O3 ratio of shales vary between 0.15 and 0.26, which lie in the range of values for clay minerals, particularly illite composition. Likewise, sandstones vary between 0.06 and 0.13, suggesting that the clay minerals are mostly kaolinte and illite types. On the chondrite-normalized diagrams, sandstone and shale samples show enriched light rare earth elements (LREE), flat heavy rare earth elements (HREE) patterns and negative Eu anomalies. The CIA and PIA values and A-CN-K plot of shales indicate low to moderate degree of weathering in the source regions. However, the sandstones have moderate to high values of CIA and PIA suggesting a moderate to intense weathering in the source regions. The SiO2/Al2O3 ratios, bivariate and ternary plots, discriminant function diagram and elemental ratios indicate the felsic source rocks for sandstone and shale of the Morita Formation.

Assessing bioturbation using micromorphology and biosilicate evidence: A case study of the early-Holocene Brady Soil, central Great Plains, USA

NASA Astrophysics Data System (ADS)

Woodburn, T. L.; Hasiotis, S. T.; Johnson, W. C.

2012-12-01

The Old Wauneta Roadcut site in southwestern Nebraska exhibits a 1.2 meter-thick exposure of the Brady Soil, a buried paleosol which formed within loess during the Pleistocene-Holocene transition. Excavation of the loess-paleosol sequence has revealed considerable bioturbation by plant roots, invertebrates, and small vertebrates. Bioturbation was not restricted to a single time period, but occurred continually throughout soil development, as evidenced by differing sediment fills and crosscutting relationships. The Brady Soil is an accretionary soil within the uppermost part of the Last Glacial Maximum Peoria Loess. At the base of the solum, the Bkb horizon exhibits an increased illuvial clay and carbonate content, and contains extensive, small (~2cm width), backfilled burrows typically produced by cicada nymphs (Cicadidae) or beetle larvae. The most stable period of the Brady Soil is expressed by the dark (9.8 YR 4/1), thick Ab horizon. This is overlain by an ACb horizon, where soil formation was being extinguished by the onset of Holocene-age Bignell Loess deposition. Within the upper solum and Bignell Loess, a shift in biota activity occurs as indicated by the large burrow (6-12 cm width) and chamber (30-40 cm width) systems observed. Trace sizes suggest that a burrowing rodent, such as the prairie dog (Cynomys sp.) or ground squirrel (Spermophilus sp.), was responsible for their creation. Soil micromorphology was used to distinguish sediment-size classes, mineralogy, and clay morphology of specific loess deposits and soil horizons in order to track displacement of sediment through the profile due to bioturbation. Five block samples were taken in undisturbed sediment and soil horizons for thin-section analysis. Twelve additional samples of burrow cross-sections or bioturbated sediment were analyzed for comparison. Soil features produced by faunal and floral activity were differentiated from features produced by pedologic processes through the identification and classification of granular and spongy microstructures indicative of excrement, calcitic biospheroids, infilling, meniscate backfilling, channel microstructures, and well-oriented clay coatings. Sediment morphology, mineralogy of the infill and backfill material, and biosilicate assemblages were used to trace the material to the source sediment location providing a timeline for events of bioturbation. Defining localized versus deep-mixing events provides an assessment of the disturbance to paleoclimate proxies and age data and will allow for a more accurate paleoclimate reconstruction in this heavily bioturbated paleosol.

Modern Foraminifera from a depth transect offshore Brunei Darussalam: diversity, sedimentation rate and preservation pathways.

NASA Astrophysics Data System (ADS)

Briguglio, Antonino; Goeting, Sulia; Kusli, Rosnani; Roslim, Amajida; Polgar, Gianluca; Kocsis, Laszlo

2016-04-01

For this study, 11 samples have been collected by scuba diving from 5 to 35 meters water depth off shore Brunei Darussalam. The locations sampled are known as: Pelong Rock (5 samples, shallow reef with soft and stony corals and larger foraminifera, 5 to 8 meters water depth), Abana Rock (1 sample, shallow reef with mainly soft corals and larger foraminifera, 13 to 18 meters water depth), Oil Rig wreck (1 sample, very sandy bottom with larger foraminifera, 18 meters water depth), Dolphin wreck (1 sample, muddy sand with many small rotaliids, 24 meters water depth), US wreck, (1 sample, sand with small clay fraction, 28 meters water depth), Australian wreck (1 sample, mainly medium to coarse sand with larger foraminifera, 34 meters water depth) and Blue water wreck (1 sample, mainly coarse sand, coral rubble and larger foraminifera, 35 meters water depth). Those samples closer to the river inputs are normally richer in clay, while the most distant samples are purely sandy. Some additional samples have been collected next to reef environments which, even if very shallow, are mainly sandy with almost no clay fraction. The deepest sample, which is 30 km offshore, contains some planktonic foraminifera and is characterized by a large range of preservations concerning foraminifera, thus testifying the presence or relict sediments at the sea bottom. The presence of relict sediments was already pointed out by older oil-related field studies offshore Brunei Darussalam, and now it is possible to draw the depth limit of these deposits. The diversity of the benthic foraminiferal fauna is relatively high but not as higher as neighboring regions as some studies have highlighted. The species collected and identified are more than 50: in reef environment the most abundant are Calcarina defrancii, Neorotalia calcar and the amphisteginidae; deeper in the muddy sediments the most abundant is Pararotalia schroeteriana and in the deepest sandy sample the most abundant are Calcarina hispida, followed by Operculina ammonoides.

A method for the concentration of fine-grained rutile (TiO2) from sediment and sedimentary rocks by chemical leaching

USGS Publications Warehouse

Commeau, Judith A.; Valentine, Page C.

1991-01-01

Most of the sample analyzed by the method described were marine muds collected from the Gulf of Maine (Valentine and Commeau, 1990). The silt and clay fraction (up to 99 wt% of the sediment) is composed of clay minerals (chiefly illite-mica and chlorite), silt-size quartz and feldspar, and small crystals (2-12 um) of rutile and hematite. The bulk sediment samples contained an average of 2 to 3 wt percent CaCO3. Tiher samples analyzed include red and gray Carboniferous and Triassic sandstones and siltstones exposed around the Bay of Fundy region and Paleozoic sandstones, siltstones, and shales from northern Maine and New Brunswick. These rocks are probable sources for the fine-grained rutile found in the Gulf of Maine.

AN ASSESSMENT OF DIOXIN LEVELS IN PROCESSED ...

EPA Pesticide Factsheets

The presence of dioxin-like compounds in ball clay was discovered in 1996 as a result of an investigation to determine the sources of elevated levels of dioxin found in two chicken fat samples from a national survey of poultry. The investigation indicated that soybean meal added to chicken feed was the source of dioxin contamination. Further investigation showed that the dioxin contamination came from the mixing of a natural clay known as

Mineralogical control of soil organic carbon persistence at the multidecadal time scale

NASA Astrophysics Data System (ADS)

Lutfalla, Suzanne; Barré, Pierre; Bernard, Sylvain; Le Guillou, Corentin; Chenu, Claire

2015-04-01

One of the current challenges in understanding the long term persistence of organic carbon in soils is to assess how mineral surfaces, especially at small scale, can stabilize soil organic carbon (SOC). The question we address in this work is whether different mineral species stabilize different types of SOC. Here we used the unique opportunity offered by long term bare fallows to study in situ C dynamics in several fine fractions of a silty loam soil. Indeed, with no vegetation i.e. no external input of fresh C, the plant-free soil of the Versailles 42 Plots (INRA, France) has been progressively enriched in persistent SOC during the 80 years of bare fallow. To separate mineral phases of the clay size fraction we performed a size fractionation on samples taken from 4 different plots at 5 different dates (0, 10, 22, 52, and 79 years after the beginning of the BF) and analyzed the SOC in the different fractions thus obtained. First, the clay fraction (< 2 µm) was isolated by wet sieving and centrifugation in water. Then, the clay fraction was further separated into 3 size fractions by centrifugation: fine clay (< 0.05 µm), intermediate clay (0.05 - 0.2 µm), and coarse clay (0.2 - 2 µm). X-ray diffraction was used to determine the mineralogy of the phases and we found that the coarse clay fraction on the one hand and fine and intermediate clay fractions on the other hand exhibited contrasted mineralogies. Fine and intermediate clay fractions contained almost exclusively smectite and mixed-layered illite/smectite minerals whereas coarse clays contained also discrete illite and kaolinite on top of smectite and illite/smectite. We carried out CHN elemental analysis to study the C and nitrogen dynamics with time in the different fractions. And synchrotron based spectroscopy and microscopy (NEXAFS bulk and STXM at the carbon K edge of 280 eV, CLS Saskatoon, Canada) was used to get information on the distribution and the chemical speciation of the SOC in fractions with contrasted mineralogies. Data analysis is still ongoing and full results will be presented at EGU. First results show that the dynamics and quality of the SOC differ in the different clay fractions. SOC decay was greater in coarse clays compared to intermediate clays, SOC in the coarse clay fraction displaying more diversity than in the other fractions. SOC persistence at the multidecadal timescale also seems to be mineral dependent: smectite being more efficient at protecting carbon compared to illite.

Experimental layering development by indenter technique and application to fault rheology differentiation

NASA Astrophysics Data System (ADS)

Gratier, J. P.; Noiriel, C. N.; Renard, F.

2014-12-01

Natural deformation of rocks is often associated with differentiation processes leading to irreversible transformations of their microstructural thus leading in turn to modifications of their rheological properties. The mechanisms of development of such processes at work during diagenesis, metamorphism or fault differentiation are poorly known as they are not easy to reproduce in the laboratory due to the long duration required for most of chemically controlled differentiation processes. Here we show that experimental compaction with layering development, similar to what happens in natural deformation, can be obtained in the laboratory by indenter techniques. Samples of plaster mixed with clay and samples of diatomite loosely interbedded with clays were loaded during several months at 40°C (plaster) and 150°C (diatomite) in presence of their saturated solutions. High-resolution X-ray tomography and SEM studies show that the layering development is a self-organized process. Stress driven dissolution of the soluble minerals (gypsum in plaster, silica in diatomite) is initiated in the zones initially richer in clays because the kinetics of diffusive mass transfer along the clay/soluble mineral interfaces is much faster than along the healed boundaries of the soluble minerals. The passive concentration of the clay minerals amplifies the localization of the dissolution along some layers oriented perpendicular to the maximum compressive stress component. Conversely, in the areas with initial low content in clay and clustered soluble minerals, dissolution is more difficult as the grain boundaries of the soluble species are healed together. These areas are less deformed and they act as rigid objects that concentrate the dissolution near their boundaries thus amplifying the differentiation. Applications to fault processes are discussed: i) localized pressure solution and sealing processes may lead to fault rheology differentiation with a partition between two end-member behaviors: seismic (in sealed zones) and aseismic (in dissolved zones); ii) tectonic layering may lead to highly anisotropic structures with a drastic decrease of the rock strength parallel to the layering.

Investigating Interactions between the Silica and Carbon Cycles during Precipitation and Early Diagenesis of Authigenic Clay/Carbonate-Mineral Associations in the Carbonate Rock Record

NASA Astrophysics Data System (ADS)

McKenzie, J. A.; Francisca Martinez Ruiz, F.; Sanchez-Roman, M.; Anjos, S.; Bontognali, T. R. R.; Nascimento, G. S.; Vasconcelos, C.

2017-12-01

The study of authigenic clay/carbonate-mineral associations within carbonate sequences has important implications for the interpretation of scientific problems related with rock reservoir properties, such as alteration of potential porosity and permeability. More specifically, when clay minerals are randomly distributed within the carbonate matrix, it becomes difficult to predict reservoir characteristics. In order to understand this mineral association in the geological record, we have undertaken a comparative study of specially designed laboratory experiments with modern environments, where clay minerals have been shown to precipitate together with a range of carbonate minerals, including calcite, Mg-calcite and dolomite. Two modern dolomite-forming environments, the Coorong lakes, South Australia and Brejo do Espinho Rio de Janeiro, Brazil, were selected for this investigation. For comparative evaluation, enrichment microbial culture experiments, using natural pore water from Brejo do Espinho as the growth medium to promote mineral precipitation, were performed under both aerobic and anaerobic conditions. To establish the environmental parameters and biological processes facilitating the dual mineral association, the experimental samples have been compared with the natural minerals using HRTEM measurements. The results demonstrate that the clay and carbonate minerals apparently do not co-precipitate, but the precipitation of the different minerals in the same sample has probably occurred under different environmental conditions with variable chemistries, e.g., hypersalinity versus normal salinity resulting from the changing ratio of evaporation versus precipitation. Thus, the investigated mineral association is not a product of diagenetic processes but of sequential in situ precipitation processes related to changes in the silica and carbon availability. Implications for ancient carbonate formations will be presented and discussed in the context of a specific example of this clay/carbonate-mineral association recorded in the Lower Cretaceous Codó Formation, NE Brazil (Bahniuk et al., 2015. Sedimentology, 62, 155-181).

Influence of Soil Organic Matter Stabilization Mechanisms on Temperature Sensitivity of Soil Respiration

NASA Astrophysics Data System (ADS)

Gillabel, J.; de Gryze, S.; Six, J.; Merckx, R.

2007-12-01

Knowledge on the sensitivity of soil organic matter (SOM) respiration to changes in temperature is crucial for predicting future impacts of climate change on soil C stocks. Temperature sensitivity of respiration is determined by the chemical structure of the compound to be decomposed and by the availability of the organic matter for decomposers. Biochemically recalcitrant SOM has a higher temperature sensitivity than biochemically labile SOM. However, it is hypothesized that the stabilization of SOM by interaction with the soil matrix could be an important attenuating control on temperature sensitivity. We investigated the effect of different SOM stabilization mechanisms on temperature sensitivity of SOM respiration. Two main mechanisms were considered: chemical interactions of SOM with clay and silt particles, and physical protection inside aggregates. Soil samples from an agricultural silt loam soil were fractionated by wet-sieving into macroaggregates, microaggregates and silt+clay fractions. SOM stabilization in the silt+clay fraction occurs mainly chemically, whereas in aggregates physical protection of SOM is more important. Samples of each fraction and of bulk soil were incubated at two temperatures (20°C and 30°C) for one month. After 2% of total soil carbon was respired, temperature sensitivity was determined for respiration of the next 0.5% of total soil carbon. This was done by calculating a Q10 value as the ratio of the times needed at each temperature to respire that fraction of the soil C. This method allows determination of temperature sensitivity independent of C quality. Calculated Q10 values decreased in the order bulk soil > macroaggregates > microaggregates > silt+clay, with the difference between macroaggregate Q10 and silt+clay Q10 being the only significant difference. These results indicate that protection of SOM attenuates temperature sensitivity, with chemical protection (silt+clay) having a larger effect than physical protection (aggregates).

Influence of soil types and osmotic pressure on growth and 137Cs accumulation in blackgram (Vigna mungo L.).

PubMed

Win, Khin Thuzar; Oo, Aung Zaw; Bellingrath-Kimura, Sonoko Dorothea

2017-04-01

A pot experiment was conducted to study the effects of soil types and osmotic levels on growth and 137 Cs accumulation in two blackgram varieties differing in salinity tolerance grown in Fukushima contaminated soils. The contamination levels of the sandy clay loam and clay soil were 1084 and 2046 Bq kg -1 DW, respectively. The 137 Cs activity was higher in both plants grown on the sandy clay loam than on the clay soil regardless of soil 137 Cs activity concentration. No significant differences were observed in all measured growth parameters between the two varieties under optimal water conditions for both types of soil. However, the growth, leaf water contents and 137 Cs activity concentrations in both plants were lower in both soil types when there was water stress induced by addition of polyethylene glycol. Water stress-induced reduction in total leaf area and total biomass, in addition to leaf relative water content, were higher in salt sensitive 'Mut Pe Khaing To' than in salt tolerant 'U-Taung-2' plants for both soil types. Varietal difference in decreased 137 Cs uptake under water stress was statically significant in the sandy clay loam soil, however, it was not in the clay soil. The transfer of 137 Cs from soil to plants (i.e., root, stem and leaf) was higher for the sandy clay loam for both plants when compared with those of the clay soil. The decreased activity of 137 Cs in the above ground samples (leaf and stem) in both plants in response to osmotic stress suggested that plant available 137 Cs decreased when soil water is limited by osmotic stress. Copyright © 2017 Elsevier Ltd. All rights reserved.

Distribution and possible immobilization of lead in a forest soil (Luvisol) profile.

PubMed

Sipos, Péter; Németh, Tibor; Mohai, Ilona

2005-02-01

Geochemical analyses using a sequential extraction method and lead adsorption studies were carried out in order to characterize the distribution and adsorption of lead on each genetic horizon of a Luvisol profile developed on a pelagic clayey aleurolite. Clay illuviation is the most important pedogenic process in the profile studied. Its clay mineralogy is characterized by chlorite/vermiculite species with increasing chlorite component downward. The amount of carbonate minerals strongly increases in the lower part of the profile resulting in an abrupt rise in soil pH within a small distance. The Pb content of the soil profile exceeds the natural geochemical background only in the Ao horizon, and its amount decreases with depth in the profile without correcting for differences in bulk density, suggesting the binding of Pb to soil organic matter. According to the sequential extraction analysis the organic matter and carbonate content of the soil have the most significant effect on lead distribution. This effect varies in the different soil horizons. Lead adsorption experiments were carried out on whole soil samples, soil clay fractions, as well as on their carbonate and organic matter free variant. The different soil horizons adsorb lead to different extents depending on their organic matter, clay mineral and carbonate content; and the mineralogical features of soil clays significantly affect their lead adsorption capacity. The clay fraction adsorbs 25% more lead than the whole soil, while in the calcareous subsoil a significant proportion of lead is precipitated due to the alkaline conditions. 10 and 5% of adsorbed Pb can be leached with distilled water in the organic matter and clay mineral dominated soil horizons, respectively. These results suggest that soil organic matter plays a decisive role in the adsorption of Pb, but the fixation by clay minerals is stronger.

Archeointensity study on baked clay samples taken from the reconstructed ancient kiln: implication for validity of the Tsunakawa-Shaw paleointensity method

NASA Astrophysics Data System (ADS)

Yamamoto, Yuhji; Torii, Masayuki; Natsuhara, Nobuyoshi

2015-05-01

In 1972, a reconstruction experiment of a kiln had been done to reproduce an excavated kiln of the seventh century in Japan. Baked clay samples were taken from the floor surface and -20 cm level, and they have been stored after determinations of the paleomagnetic directions by partial alternating field demagnetizations. We recently applied the Tsunakawa-Shaw method to the samples to assess how reliable archeointensity results are obtained from the samples. A suite of the rock magnetic experiments and the scanning electron microscope observations elucidate that dominant magnetic carriers of the floor surface samples are Ti-poor titanomagnetite grains in approximately 10 nm size with single-domain and/or super-paramagnetic states, whereas contributions of multi-domain grains seem to be relatively large for the -20-cm level samples. From the floor surface samples, six out of the eight successful results were obtained and they give an average of 47.3 μT with a standard deviation of 2.2 μT. This is fairly consistent with the in situ geomagnetic field of 46.4 μT at the time of the reconstruction. They are obtained with a built-in anisotropy correction using anhysteretic remanent magnetization and without any cooling rate corrections. In contrast, only one out of four was successful from the -20-cm level samples. It yields an archeointensity of 31.6 μT, which is inconsistent with the in situ geomagnetic field. Considering from the in situ temperature record during the firing of the kiln and the unblocking temperature spectra of the samples, the floor surface samples acquired full thermoremanent magnetizations (TRMs) as their natural remanent magnetizations whereas the -20-cm level samples only acquired partial TRMs, and these differences probably cause the difference in the archeointensity results between the two sample groups. For archeointensity researches, baked clay samples from a kiln floor are considered to be ideal materials.

How does the composition affect the mechanical behaviour of simulated clay-rich fault gouges?

NASA Astrophysics Data System (ADS)

Bakker, Elisenda; Spiers, Christopher J.; Hangx, Suzanne J. T.

2014-05-01

CO2 capture and storage (CCS) in depleted oil and gas reservoirs is seen as one of the most promising large-scale CO2-mitigation strategies. Prediction of the effect of fluid-rock interaction on the mechanical integrity and sealing capacity of a reservoir-seal system, on timescales of the order of 1,000 or 10,000 years, is important to ensure the safety and containment of a reservoir in relation to long-term CO2 storage. However, most chemical reactions in rock/CO2/brine systems are slow, which means that long-term effects of fluids on rock composition, microstructure, mechanical properties and transport properties cannot be easily reproduced under laboratory conditions. One way to overcome this problem is to use simulated fault gouges in experiments, investigating a range of possible mineralogical compositions resulting from CO2-exposure. Previous studies have shown that the mechanical and transport properties of clay-rich fault gouges are significantly influenced by the mineralogy, particularly by the presence and relative amount of secondary phases, such as quartz and/or carbonate. In CCS settings, where dissolution and/or precipitation of carbonates may play an important role, the carbonate:clay ratio is expected to influence fault frictional behaviour. This is supported by the different behaviour of phyllosilicates, which generally show stable slip behaviour (aseismic), compared to carbonates, which have shown to become prone to unstable slip (potentially seismic) with increasing temperature. However, little is known about the mechanical and transport properties of carbonate/clay mixtures. We investigated the effect of the carbonate:clay ratio on fault friction, fault reactivation potential and slip stability, i.e. seismic vs. aseismic behaviour, as well as transmissivity evolution during and after fault reactivation. We used two types of starting material, derived from crushed Opalinus Claystone (Mont Terri, Switzerland): i) untreated samples consisting mainly of phyllosilicates (60%), quartz (~20%) and calcite (~15-25%) and ii) "leached" samples consisting of phyllosilicate (65%) and quartz (35%), where the removal of the calcite represents a worst-case scenario for rock/CO2/brine (dissolution) reactions. We performed triaxial direct shear experiments at relevant in-situ temperatures (60-120°C) under saturated conditions (Pp = 25 MPa), using demineralized water as pore fluid, at an effective normal stress (σn) of 50 MPa and shear velocities of 0.22 to 10.9 μm/s. Preliminary results show that the shear strength of the leached samples decreases by ~10-15% with respect to the natural, untreated clay samples. Typical steady-state friction coefficient values obtained for the natural samples are in the range 0.27-0.33, whereas for the leached samples they vary between 0.24 and 0.27. These values are significantly lower than typical friction coefficient values obtained for pure calcite (i.e. 0.62 to 0.71). Both natural and leached samples show velocity strengthening behaviour. The slip stability of the natural gouge appears to be slightly more temperature dependent, showing somewhat higher values of the stability (rate and state friction) parameter (a-b) for lower temperatures.

Effect of Mineral and Microbe Interactions on Biomass Yield

NASA Astrophysics Data System (ADS)

Pena, S. A.; Block, K. A.; Katz, A.; Gottlieb, P.

2016-12-01

The ecological feedback of microbes (bacteria and viruses) in association with minerals is virtually unexplored in the context of characterizing how carbon cycles in the terrestrial ecosystem. These interactions include the ability for bacteriophage to control bacteria populations, the ability of minerals to provide a substrate for bacteria growth, and the effect of minerals on bacteriophage viability. We investigate bacteriophage aggregation with minerals in the clay size fraction (< 0.2 µm) as well as the interaction between bacteriophage and mineral biofilms. In our virus experiments, bacteriophage Φ6 was suspended with the minerals smectite, illite, kaolinite, and goethite at low divalent cation concentrations so aggregation was in the reaction limited colloidal aggregation (RLCA) regime, at neutral pH and room temperature conditions. Virus remained viable at a 1:1 virus-clay ratio for clays, and at an approximate 100:1 ratio for goethite. However, the number of plaque forming units was reduced by 99%. Electron micrographs show viable as well as partially disassembled virus, similar to the results found by Block et al. 2014. We found that inactivation of a 4 x 1011 cm-3 concentration of bacteriophage Φ6 by smectite, illite, kaolinite, and goethite, required a minimum sediment concentration of 1.5 x 1011 cm-3, 1.4 x 1011 cm-3, 2.5 x 1011 cm-3, and 1.1 x 109 cm-3, respectively. Mineral biofilms were generated by suspension of tropical soil clays with gram-positive and gram-negative microbes and characterized by x-ray diffraction and imaged by electron microscopy (SEM and TEM). Mineral biomass produced by gram negative organisms were subjected to virus infection to determine influence of minerals on community resilience. Lastly, we report biomass yield in each instance to quantify the influence of mineral composition on total biomass production.

75 FR 44937 - Submission for OMB Review; Comment Request

Federal Register 2010, 2011, 2012, 2013, 2014

2010-07-30

... is a block cluster, which consists of one or more contiguous census blocks. The P sample is a sample of housing units and persons obtained independently from the census for a sample of block clusters. The E sample is a sample of census housing units and enumerations in the same block of clusters as the...

Laboratory Study of Quaternary Sediment Resistivity Related to Groundwater Contamination at Mae-Hia Landfill, Mueang District, Chiang Mai Province

NASA Astrophysics Data System (ADS)

Sichan, N.

2007-12-01

This study was aimed to understand the nature of the resistivity value of the sediment when it is contaminated, in order to use the information solving the obscure interpretation in the field. The pilot laboratory experiments were designed to simulate various degree of contamination and degree of saturation then observe the resulting changes in resistivity. The study was expected to get a better understanding of how various physical parameters effect the resistivity values in term of mathematic function. And also expected to apply those obtained function to a practical quantitatively interpretation. The sediment underlying the Mae-Hia Landfill consists of clay-rich material, with interfingerings of colluvium and sandy alluvium. A systematic study identified four kinds of sediment, sand, clayey sand, sandy clay, and clay. Representative sediment and leachate samples were taken from the field and returned to the laboratory. Both the physical and chemical properties of the sediments and leachate were analyzed to delineate the necessary parameters that could be used in Archie's equation. Sediment samples were mixed with various concentration of leachate solutions. Then the resistivity values were measured at various controlled steps in the saturation degree in a well- calibrated six-electrode model resistivity box. The measured resistivity values for sand, clayey sand, sandy clay when fully and partly saturated were collected, then plotted and fitted to Archie's equation, to obtain a mathematical relationship between bulk resistivity, porosity, saturation degree and resistivity of pore fluid. The results fit well to Archie's equation, and it was possible to determine all the unknown parameters representative of the sediment samples. For sand, clayey sand, sandy clay, and clay, the formation resistivity factors (F) are 2.90, 5.77, 7.85, and 7.85 with the products of cementation factor (m) and the pore geometry factors (a) (in term of -am) are 1.49, -1.63, -1.92, -2.24 and the saturation exponents (n) are 2.06, 2.58, 3.52, and 2.46, respectively. These results were used to reinterpret the existing resistivity data of this area. The result of this reinterpretation is a map showing the quantitative distribution of the contaminant plume in the vicinity of the Mae-Hia Landfill.

Effects of Freezing and Thawing on Consolidation Behavior of Clayey Soils

NASA Astrophysics Data System (ADS)

Binal, Adil; Adeli, Parisa

2015-04-01

An apprehending of freezing and thawing effects on cohesive soil is considerable for many construction and environmental subjects. This paper relates the effects of freezing and thawing on consolidation behaviour of clayey soils. The Capital of Ankara settled on a sequence of lacustrine sediments. These sediments include fine grain soils, locally. Collected samples were undisturbed grey clay and clayey sand that were obtained from the bottom of a construction zone at about 1m depth below the ground surface. Total of 32 moulded samples were prepared with constant water content to reflect the moisture condition in the active surface layer. Gray clay and clayey sand were analysed in the laboratory, and found to have the plastic limits (PL) of 33.01% and 22.56%, the liquid limits (LL) of 75.05% and 36.97%, and the plasticity indexes (PI) of 42.04% and 14.41%. The soil samples were classified as "CH" and "SC" in accordance with the unified soil classification system. Soil samples for all tests were placed in a freezer that has -18°C temperature. Samples have been waited in it for twenty-four hours. Then, they have been removed from the freezer and allowed to stand for twenty-four hours at a constant room temperature (21°C) and humidity (80% RH). As a result, one freezing and thawing cycle was achieved between -18°C (24 hours) and 21°C (24 hours), and it took two days. Freezing and thawing (FT) sequences were selected as 1, 3, 7, 14 and 21. After each FT sequence, Atterberg limits and consolidation tests were carried out in accordance with ASTM standards. Liquid and plastic limits of soil samples, suddenly, were decreased after first FT cycle. That state is a sign of the clay mineral orientation due to freezing and thawing process. The soil classification of clayey sand was changed from "SC" to "SM" after first FT cycle. Furthermore, the coefficient of consolidation and permeability of grey clay had been increased by rising in FT cycles up to 7 and then continue to decline as well as these values of clayey sand start to decrease after 14 FT cycles.

Hydrogeochemistry for the assessment of groundwater quality in Varanasi: a fast-urbanizing center in Uttar Pradesh, India.

PubMed

Janardhana Raju, Nandimandalam; Shukla, U K; Ram, Prahlad

2011-02-01

The hydrogeochemical parameters for groundwater samples of the Varanasi area, a fast-urbanizing region in India, were studied to evaluate the major ion chemistry, weathering and solute acquisition processes controlling water composition, and suitability of water quality for domestic and irrigation uses. Sixty-eight groundwater samples were collected randomly from dug wells and hand pumps in the urban Varanasi area and analyzed for various chemical parameters. Geologically, the study area comprises Quaternary alluvium made up of an alternating succession of clay, silty clay, and sand deposits. The Total dissolved solids classification reveals that except two locations, the groundwater samples are desirable for drinking, and all are useful for irrigation purposes. The cationic and anionic concentrations indicated that the majority of the groundwater samples belong to the order of Na>Ca>Mg>K and HCO3>Cl>SO4 types, respectively. Geochemical classification of groundwater based on the Chadha rectangular diagram shows that the majority (81%) of groundwater samples belong to the calcium-bicarbonate type. The HCO3/(HCO3+SO4) ratio (0.87) indicates mostly carbonic acid weathering process due to presence of kankar carbonate mixed with clay/fine sand. The high nitrate concentration (>45 mg/l) of about 18% of the groundwater samples may be due to the local domestic sewage, leakage of septic tanks, and improper management of sanitary landfills. In general, the calculated values of sodium adsorption ratio, percent sodium, residual sodium carbonate, and permeability index indicate good to permissible use of water for irrigation, and only a few locations demand remedial measures for better crop yields.

Influence of smectite suspension structure on sheet orientation in dry sediments: XRD and AFM applications.

PubMed

Zbik, Marek S; Frost, Ray L

2010-06-15

The structure-building phenomena within clay aggregates are governed by forces acting between clay particles. Measurements of such forces are important to understand in order to manipulate the aggregate structure for applications such as dewatering of mineral processing tailings. A parallel particle orientation is required when conducting XRD investigation on the oriented samples and conduct force measurements acting between basal planes of clay mineral platelets using atomic force microscopy (AFM). To investigate how smectite clay platelets were oriented on silicon wafer substrate when dried from suspension range of methods like SEM, XRD and AFM were employed. From these investigations, we conclude that high clay concentrations and larger particle diameters (up to 5 microm) in suspension result in random orientation of platelets in the substrate. The best possible laminar orientation in the clay dry film, represented in the XRD 001/020 intensity ratio of 47 was obtained by drying thin layers from 0.02 wt.% clay suspensions of the natural pH. Conducted AFM investigations show that smectite studied in water based electrolytes show very long-range repulsive forces lower in strength than electrostatic forces from double-layer repulsion. It was suggested that these forces may have structural nature. Smectite surface layers rehydrate in water environment forms surface gel with spongy and cellular texture which cushion approaching AFM probe. This structural effect can be measured in distances larger than 1000 nm from substrate surface and when probe penetrate this gel layer, structural linkages are forming between substrate and clay covered probe. These linkages prevent subsequently smooth detachments of AFM probe on way back when retrieval. This effect of tearing new formed structure apart involves larger adhesion-like forces measured in retrieval. It is also suggested that these effect may be enhanced by the nano-clay particles interaction. 2010 Elsevier Inc. All rights reserved.

Bentonite-Clay Waste Form for the Immobilization of Cesium and Strontium from Fuel Processing Waste Streams

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kaminski, Michael D.; Mertz, Carol J.

2016-01-01

The physical properties of a surrogate waste form containing cesium, strontium, rubidium, and barium sintered into bentonite clay were evaluated for several simulant feed streams: chlorinated cobalt dicarbollide/polyethylene glycol (CCD-PEG) strip solution, nitrate salt, and chloride salt feeds. We sintered bentonite clay samples with a loading of 30 mass% of cesium, strontium, rubidium, and barium to a density of approximately 3 g/cm 3. Sintering temperatures of up to 1000°C did not result in volatility of cesium. Instead, there was an increase in crystallinity of the waste form upon sintering to 1000ºC for chloride- and nitrate-salt loaded clays. The nitrate saltmore » feed produced various cesium pollucite phases, while the chloride salt feed did not produce these familiar phases. In fact, many of the x-ray diffraction peaks could not be matched to known phases. Assemblages of silicates were formed that incorporated the Sr, Rb, and Ba ions. Gas evolution during sintering to 1000°C was significant (35% weight loss for the CCD-PEG waste-loaded clay), with significant water being evolved at approximately 600°C.« less

Frictional, Hydraulic, and Acoustic Properties of Alpine Fault DFDP-1 Core

NASA Astrophysics Data System (ADS)

Carpenter, B. M.; Ikari, M.; Kitajima, H.; Kopf, A.; Marone, C.; Saffer, D. M.

2012-12-01

The Alpine Fault, a transpressional plate-boundary fault transecting the South Island of New Zealand, is the current focus of the Deep Fault Drilling Project (DFDP), a major fault zone drilling initiative. Phase 1 of this project included 2 boreholes that penetrated the active fault at depths of ˜100 m and ˜150 m, and provided a suite of core samples crossing the fault. Here, we report on laboratory measurements of frictional strength and constitutive behavior, permeability, and ultrasonic velocities for a suite of the recovered core samples We conducted friction experiments on powdered samples in a double-direct shear configuration at room temperature and humidity. Our results show that over a range of effective normal stresses from 10-100 MPa, friction coefficients are ~0.60-0.70, and are similar for all of the materials we tested. Rate-stepping tests document velocity-weakening behavior in the majority of wall rock samples, whereas the principal slip surface (PSS) and an adjacent clay-rich cataclasite exhibit velocity-strengthening behavior. We observe significant rates of frictional healing in all of our samples, indicating that that the fault easily regains its strength during interseismic periods. Our results indicate that seismic slip is not likely to nucleate in the clay-rich PSS at shallow depths, but might nucleate and propagate on the gouge/wall rock interface. We measured permeability using a constant head technique, on vertically oriented cylindrical mini-cores (i.e. ˜45 degrees to the plane of the Alpine Fault). We conducted these tests in a triaxial configuration, under isotropic stress conditions and effective confining pressures from ~2.5 - 63.5 MPa. We conducted ultrasonic wavespeed measurements concurrently with the permeability measurements to determine P- and S-wave velocities from time-of-flight. The permeability of all samples decreases systematically with increasing effective stress. The clay-rich cataclasite (1.37 x 10-19 m2) and PSS (1.62 x 10-20 m2) samples exhibit the lowest permeabilities. The cataclasite, and wall rock mylonite and gravel samples, all exhibit permeabilities > 10-18 m2. We also observe that permeability of the cataclasites appears to decrease with proximity to the active fault zone. Our laboratory measurements are consistent with borehole slug tests that show the fault is a hydraulic barrier, and suggest that fault rock permeability is sufficiently low to facilitate transient pore pressure effects during rapid slip, including thermal pressurization and dilatancy hardening. Elastic wave velocity increases systematically with increasing effective stress. We find the lowest P-wave velocities in clay-rich, poorly lithified samples from within and near the active fault, including hanging wall cataclasite, fault gouge, and footwall gravel. Our results are consistent with borehole logging data that show an increase in P-wave velocity from the mylonite into the competent cataclasites, and a decrease in P-wave velocity through the clay-rich cataclasite and into the fault zone.

Chemical Mobility, Variability, and Components of the Yaxcopoil Impact Melt Breccia Matrix as a Function of Depth

NASA Astrophysics Data System (ADS)

Nelson, M. J.; Newsom, H.

2005-05-01

The matrix in the Yaxcopoil 1 drill core produced by the Chicxulub event is semi-amorphous, containing clays and evidence for elemental mobility. We analyzed matrix in impact melt and suevitic breccia samples from the drill hole to detect mineralogical and chemical variability with depth in upper and lower core samples. SEM, microprobe, Cameca 4f ion probe, and XRD were used to determine chemical mobility and variation, and clay structure in several YAX samples, covering the top five units, at a depth range of about 61m. We investigated the possibility of glass, clay, and metastable eutectic dehydroxylates as components in the matrix. Matrix in upper suevite is not optically distinct, but a type of groundmass, with an admixture of calcite, crystallites, and several melt phases with melt texture indicative of simultaneous formation. With an increase in depth, flow tex-ture in the melt matrix is obvious around clasts on all scales, indicating a different temporal relationship than in the upper suevite. Chemically, the matrix is Si and Mg rich in most samples. With an increase in depth, the bulk matrix contains a strong linear increase of Mg, and a decrease of Al. With depth, the increasingly Mg-rich matrix exhibits a stronger flow texture. Aluminum also appears mobile, with enrichments mostly around clasts and veins. In addition, Li and B are strongly correlated, and decrease linearly with depth. The matrix contains materials that appear to be chemically and structurally consistent with smectites at all depths. The compositions range from that of an average montmorillonite in the uppermost units to that of a magnesium rich saponite in the lower units. Aside from the exis-tence of clays, we are considering the possibility that the matrix could contain metastable condensates from the im-pact dust cloud. As an introductory step to test this, matrix compositions were plotted among metastable eutectic dehydroxylate (MED) end members. This produced a remarkably co-linear trend with the join between MED pyro-phyllite and MED serpentine. High resolution equipment will be used to follow up on this idea. The matrix in lower samples had more element mobility, and likely more chemical reactions occurring among phases. An increase in mobility and transport of Mg could help explain this bulk enrichment in lower samples. In addition, variations in the original target material would logically contribute to chemical variations in the matrix. Dolomite and mafic minerals present at greater depth could react with matrix in the melt breccia, while dust and clay may exist in variable amounts within the drill core samples. The linear trend toward metastable dehydroxylate eutec-tic compositions is an encouraging first step to further investigate the possible existence of condensates from the impact cloud within the matrix.

Eagel Hill: A Late Quaternary Upland Site in Western Louisiana.

DTIC Science & Technology

1982-01-01

the Florida and Yucatan penin- sulas. The continental shelf is considered to extend to the 200 m contour. The slope is very gradual to the 100 m...it to advantage. It is also counter to dogma on hunter and horticultural nutritional affects on stature. With such a small sample we can at best ask...colluvium-clay interface between, for humans, two nutritionally unproductive sand bodies, which provide the most efficient access to the colluvium-clay

CO 2 Sorption to Subsingle Hydration Layer Montmorillonite Clay Studied by Excess Sorption and Neutron Diffraction Measurements

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rother, Gernot; Ilton, Eugene S.; Wallacher, Dirk

2013-01-02

Geologic storage of CO 2 requires that the caprock sealing the storage rock is highly impermeable to CO 2. Swelling clays, which are important components of caprocks, may interact with CO 2 leading to volume change and potentially impacting the seal quality. The interactions of supercritical (sc) CO 2 with Na saturated montmorillonite clay containing a subsingle layer of water in the interlayer region have been studied by sorption and neutron diffraction techniques. The excess sorption isotherms show maxima at bulk CO2 densities of ≈0.15 g/cm 3, followed by an approximately linear decrease of excess sorption to zero and negativemore » values with increasing CO 2 bulk density. Neutron diffraction experiments on the same clay sample measured interlayer spacing and composition. The results show that limited amounts of CO 2 are sorbed into the interlayer region, leading to depression of the interlayer peak intensity and an increase of the d(001) spacing by ca. 0.5 Å. The density of CO 2 in the clay pores is relatively stable over a wide range of CO 2 pressures at a given temperature, indicating the formation of a clay-CO 2 phase. Finally, at the excess sorption maximum, increasing CO 2 sorption with decreasing temperature is observed while the high-pressure sorption properties exhibit weak temperature dependence.« less

A remediation performance model for enhanced metabolic reductive dechlorination of chloroethenes in fractured clay till

NASA Astrophysics Data System (ADS)

Manoli, Gabriele; Chambon, Julie C.; Bjerg, Poul L.; Scheutz, Charlotte; Binning, Philip J.; Broholm, Mette M.

2012-04-01

A numerical model of metabolic reductive dechlorination is used to describe the performance of enhanced bioremediation in fractured clay till. The model is developed to simulate field observations of a full scale bioremediation scheme in a fractured clay till and thereby to assess remediation efficiency and timeframe. A relatively simple approach is used to link the fermentation of the electron donor soybean oil to the sequential dechlorination of trichloroethene (TCE) while considering redox conditions and the heterogeneous clay till system (clay till matrix, fractures and sand stringers). The model is tested on lab batch experiments and applied to describe sediment core samples from a TCE-contaminated site. Model simulations compare favorably to field observations and demonstrate that dechlorination may be limited to narrow bioactive zones in the clay matrix around fractures and sand stringers. Field scale simulations show that the injected donor is expected to be depleted after 5 years, and that without donor re-injection contaminant rebound will occur in the high permeability zones and the mass removal will stall at 18%. Long remediation timeframes, if dechlorination is limited to narrow bioactive zones, and the need for additional donor injections to maintain dechlorination activity may limit the efficiency of ERD in low-permeability media. Future work should address the dynamics of the bioactive zones, which is essential to understand for predictions of long term mass removal.

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

USGS Publications Warehouse

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

2005-01-01

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

Effect on mechanical properties of glass reinforced epoxy (GRE) pipe filled with different geopolymer filler molarity for piping application

NASA Astrophysics Data System (ADS)

Hashim, M. F. Abu; Abdullah, M. M. A.; Ghazali, C. M. R.; Hussin, K.; Binhussain, M.

2017-04-01

This study investigated the use of a novel white clay geopolymer as a filler to produce high strength glass reinforced epoxy pipe. It was found that using white clay geopolymer as filler gives better compressive strength to the glass reinforced epoxy pipe. The disadvantages of current glass reinforced epoxy pipes such low compressive strength which can be replaced by the composite pipes. Geopolymerization is an innovative technology that can transform several aluminosilicate materials into useful products called geopolymers or inorganic polymers. A series of glass reinforced epoxy pipe and glass reinforced epoxy pipe filled with 10 - 40 weight percentages white clay geopolymer filler with 4 Molarity and 8 Molarity were prepared. Morphology of white clay geopolymer filler surface was indicates using scanning electron microscopy. The additions of white clay geopolymer filler for both 4 Molarity and 8 Molarity show higher compressive strength than glass reinforced epoxy pipe without any geopolymer filler. The compressive test of these epoxy geopolymer pipe samples was determined using Instron Universal Testing under compression mode. Nonetheless, the compressive strength of glass reinforced epoxy pipe with white clay geopolymer filler continues to drop when added to 40 wt% of the geopolymer filler loading for both 4 Molarity and 8 Molarity. These outcomes showed that the mixing of geopolymer materials in epoxy system can be attained in this research.

Nontronite Stability in Near-Surface Sediments

NASA Astrophysics Data System (ADS)

Home, C.; Baker, L.

2015-12-01

The purpose of this study is to examine how long nontronite clays persist in soil, by studying samples collected from a sediment cone weathering out of crack in a basalt outcrop near Moscow Idaho. Nontronite, a dioctahedral ferric smectite clay, is a frequent weathering product of basaltic rocks. However, it is rarely described in surface soils, even in basaltic terrains. At our field site, nontronite formed by basalt weathering is eroding from cracks in the basalt and forming small talus cones. We are examining samples collected from a trench and several soil cores to determine the clay mineralogy at different depths in the talus cone. Bulk and clay mineralogy is being determined using X-ray Diffractometry (XRD) analysis and Fourier Transform Infrared Spectroscopy (FT-IR) analysis. Bulk chemical analyses, and selective extractions with acid oxalate and citrate-bicarbonate-dithionite reagents, are being used to analyze Fe mineralogy and amorphous constituents. Preliminary observations suggest that iron mineralogy may vary with depth in the sediments, and that older, deeper sediments may contain more Fe in oxide phases. We hypothesize that nontronite in the sediments is decomposing over time to form low-Fe smectites + Fe oxides. The results of this study will help determine whether nontronite is stable to erosion and redeposition in a surficial environment, as well as the timescale of its possible decomposition. These results may be useful in assessing proposed models of nontronite transport and redeposition on Mars.

Multisensor on-the-go mapping of readily dispersible clay, particle size and soil organic matter

NASA Astrophysics Data System (ADS)

Debaene, Guillaume; Niedźwiecki, Jacek; Papierowska, Ewa

2016-04-01

Particle size fractions affect strongly the physical and chemical properties of soil. Readily dispersible clay (RDC) is the part of the clay fraction in soils that is easily or potentially dispersible in water when small amounts of mechanical energy are applied to soil. The amount of RDC in the soil is of significant importance for agriculture and environment because clay dispersion is a cause of poor soil stability in water which in turn contributes to soil erodibility, mud flows, and cementation. To obtain a detailed map of soil texture, many samples are needed. Moreover, RDC determination is time consuming. The use of a mobile visible and near-infrared (VIS-NIR) platform is proposed here to map those soil properties and obtain the first detailed map of RDC at field level. Soil properties prediction was based on calibration model developed with 10 representative samples selected by a fuzzy logic algorithm. Calibration samples were analysed for soil texture (clay, silt and sand), RDC and soil organic carbon (SOC) using conventional wet chemistry analysis. Moreover, the Veris mobile sensor platform is also collecting electrical conductivity (EC) data (deep and shallow), and soil temperature. These auxiliary data were combined with VIS-NIR measurement (data fusion) to improve prediction results. EC maps were also produced to help understanding RDC data. The resulting maps were visually compared with an orthophotography of the field taken at the beginning of the plant growing season. Models were developed with partial least square regression (PLSR) and support vector machine regression (SVMR). There were no significant differences between calibration using PLSR or SVMR. Nevertheless, the best models were obtained with PLSR and standard normal variate (SNV) pretreatment and the fusion with deep EC data (e.g. for RDC and clay content: RMSECV = 0,35% and R2 = 0,71; RMSECV = 0,32% and R2 = 0,73 respectively). The best models were used to predict soil properties from the field spectra collected with the VIS-NIR platform. Maps of soil properties were generated using natural neighbour (NN) interpolation. Calibration results were satisfactory for all soil properties and allowed for the generation of detailed maps. The spatial variability of RDC was in accordance with the field orthophotography. Areas of high RDC content were corresponding to area of bad plant development. Soil texture has been correctly predicted by VIS-NIR spectroscopy (laboratory or on-the-go) before. However, readily dispersible clay (an important parameter for soil stability) has never been investigated before. This study introduces the possibility of using VIS-NIR for predicting readily dispersible clay at field level. The results obtained could be used in preventing soil erosion. Acknowledgement: This research was financed by a National Science Centre grant (NCN - Poland) with decision number UMO-2012/07/B/ST10/04387

Rb-Sr, Sm-Nd, K-Ca, O, and H isotopic study of Cretaceous-Tertiary boundary sediments, Caravaca, Spain: evidence for an oceanic impact site

USGS Publications Warehouse

DePaolo, D.J.; Kyte, F.T.; Marshall, B.D.; O'Neil, J.R.; Smit, J.

1983-01-01

Isotopic ratios and trace element abundances were measured on samples of Ir-enriched clay at the Cretaceous-Tertiary boundary, and in carbonate and marl from 5 cm below and 3 cm above the boundary. Samples were leached with acetic acid to remove carbonate, and with hydrochloric acid. Leachates and residues were measured. The Sr, Nd, O and H isotopic compositions of the boundary clay residues are distinct from those of the stratigraphically neighboring materials. The data indicate that most of the clay material was derived from a terrestrial source with relatively low 87Sr/86Sr and high 143Nd/144Nd ratios. The ??18O data suggest that the detritus has been modified by submarine weathering. K-Ca and Rb-Sr systematics, as well as O isotope ratios of K-feldspar spherules within the boundary clay, suggest that they are predominantly authigenic and may have formed after the time of deposition. However, Sm-Nd and Rb-Sr isotopic data indicate that the spherules contain relict material that provides information on the nature of the original detritus. The isotopic evidence for foreign terrestrial detritus in the boundary clay, the low rare earth element concentrations and high Ni concentration, support the hypothesis of a terminal Cretaceous asteroidal impact that produced a global layer of fallout. The data are most easily explained if the impact site was on oceanic crust rather than continental crust, and if a substantial fraction of the fallout was derived from relatively deep within the lithosphere (>3 km). This would probably require a single large impactor. ?? 1983.

Amino Acid Interaction with and Adsorption on Clays: FT-IR and Mössbauer Spectroscopy and X-ray Diffractometry Investigations

NASA Astrophysics Data System (ADS)

Benetoli, Luís O. B.; de Souza, Cláudio M. D.; da Silva, Klébson L.; de Souza, Ivan G.; de Santana, Henrique; Paesano, Andrea; da Costa, Antonio C. S.; Zaia, Cássia Thaïs B. V.; Zaia, Dimas A. M.

2007-12-01

In the present paper, the adsorption of amino acids (Ala, Met, Gln, Cys, Asp, Lys, His) on clays (bentonite, kaolinite) was studied at different pH (3.00, 6.00, 8.00). The amino acids were dissolved in seawater, which contains the major elements. There were two main findings in this study. First, amino acids with a charged R group (Asp, Lys, His) and Cys were adsorbed on clays more than Ala, Met and Gln (uncharged R groups). However, 74% of the amino acids in the proteins of modern organisms have uncharged R groups. These results raise some questions about the role of minerals in providing a prebiotic concentration mechanism for amino acids. Several mechanisms are also discussed that could produce peptide with a greater proportion of amino acids with uncharged R groups. Second, Cys could play an important role in prebiotic chemistry besides participating in the structure of peptides/proteins. The FT-IR spectra showed that the adsorption of amino acids on the clays occurs through the amine group. However, the Cys/clay interaction occurs through the sulfhydryl and amine groups. X-ray diffractometry showed that pH affects the bentonite interlayer, and at pH 3.00 the expansion of Cys/bentonite was greater than that of the samples of ethylene glycol/bentonite saturated with Mg. The Mössbauer spectrum for the sample with absorbed Cys showed a large increase (˜20%) in ferrous ions. This means that Cys was able to partially reduce iron present in bentonite. This result is similar to that which occurs with aconitase where the ferric ions are reduced to Fe 2.5.

Modeling the arrangement of particles in natural swelling-clay porous media using three-dimensional packing of elliptic disks

NASA Astrophysics Data System (ADS)

Ferrage, Eric; Hubert, Fabien; Tertre, Emmanuel; Delville, Alfred; Michot, Laurent J.; Levitz, Pierre

2015-06-01

Swelling clay minerals play a key role in the control of water and pollutant migration in natural media such as soils. Moreover, swelling clay particles' orientational properties in porous media have significant implications for the directional dependence of fluid transfer. Herein we investigate the ability to mimic the organization of particles in natural swelling-clay porous media using a three-dimensional sequential particle deposition procedure [D. Coelho, J.-F. Thovert, and P. M. Adler, Phys. Rev. E 55, 1959 (1997), 10.1103/PhysRevE.55.1959]. The algorithm considered is first used to simulate disk packings. Porosities of disk packings fall onto a single master curve when plotted against the orientational scalar order parameter value. This relation is used to validate the algorithm used in comparison with existing ones. The ellipticity degree of the particles is shown to have a negligible effect on the packing porosity for ratios ℓa/ℓb less than 1.5, whereas a significant increase in porosity is obtained for higher values. The effect of the distribution of the geometrical parameters (size, aspect ratio, and ellipticity degree) of particles on the final packing properties is also investigated. Finally, the algorithm is used to simulate particle packings for three size fractions of natural swelling-clay mineral powders. Calculated data regarding the distribution of the geometrical parameters and orientation of particles in porous media are successfully compared with experimental data obtained for the same samples. The results indicate that the obtained virtual porous media can be considered representative of natural samples and can be used to extract properties difficult to obtain experimentally, such as the anisotropic features of pore and solid phases in a system.

Viscoelastic and Mechanical Properties of Thermoset PMR-type Polyimide-Clay Nanocomposites

NASA Technical Reports Server (NTRS)

Abdalla, Mohamed O.; Dean, Derrick; Campbell, Sandi

2002-01-01

High temperature thermoset polyimide-clay nanocomposites were prepared by blending 2.5 and 5 wt% of an unmodified Na(+-) montmorillonite (PGV) and two organically modified FGV (PGVCl0COOH, PGVC12) with a methanol solution of PMR-15 precursor. The methanol facilitated the dispersal of the unmodified clay. Dynamic mechanical analysis results showed a significant increase in the thermomechanical properties (E' and E") of 2.5 wt% clay loaded nanocomposites in comparison with the neat polyimide. Higher glass transition temperatures were observed for 2.5 wt% nanocomposites compared to the neat polyimide. Flexural properties measurements for the 2.5 wt% nanocomposites showed a significant improvement in the modulus and strength, with no loss in elongation. This trend was not observed for the 5 wt% nanocomposites. An improvement in the CTE was observed for the PGV/PMR-15 nanocomposites, while a decrease was observed for the organically modified samples. This was attributed to potential variations in the interface caused by modifier degradation.

Sorption characteristics of organic compounds on hexadecyltrimethylammonium-smectite

USGS Publications Warehouse

Boyd, Stephen A.; Mortland, Max M.; Chiou, Cary T.

1988-01-01

When hexadedyltrimethylammonium (HDTMA) ion is exchanged for metal cations like calcium in smectite, the sorptive properties of the clay are greatly modified. The resultant HDTMA-smectite complex behaves as a dual sorbent, in the sorption of organic compounds, in which the mineral fraction functions as a solid adsorbent and the organic (HDTMA) phase as a partition medium. Capacities of mineral adsorption and partition uptake by HDTMA in the HDTMA-smectites are illustrated by sorption of benzene, trichloroethene (TCE), and water as vapors on the dry sample and by sorption of benzene and TCE from water. The exchanged HDTMA in clay is found to be a much more powerful partition medium than ordinary soil organic matter in the uptake of benzene and TCE. Based on this finding, HDTMA-smectite appears to be an effective sorbent for removing organic contaminants from water. It is suggested that such sorptive organo-clay complexes could be used to enhance the containment capabilities of clay landfill liners and bentonite slurry walls.

Microbial effects on colloidal agglomeration

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hersman, L.

1995-11-01

Colloidal particles are known to enhance the transport of radioactive metals through soil and rock systems. This study was performed to determine if a soil microorganism, isolated from the surface samples collected at Yucca Mountain, NV, could affect the colloidal properties of day particles. The agglomeration of a Wyoming bentonite clay in a sterile uninoculated microbial growth medium was compared to the agglomeration in the medium inoculated with a Pseudomonas sp. In a second experiment, microorganisms were cultured in the succinate medium for 50 h and removed by centrifugation. The agglomeration of the clay in this spent was compared tomore » sterile uninoculated medium. In both experiments, the agglomeration of the clay was greater than that of the sterile, uninoculated control. Based on these results, which indicate that this microorganism enhanced the agglomeration of the bentonite clay, it is possible to say that in the presence of microorganisms colloidal movement through a rock matrix could be reduced because of an overall increase in the size of colloidal particle agglomerates. 32 refs.« less

Mineralogy and provenance of clays in miarolitic cavities of the Pikes Peak Batholith, Colorado

USGS Publications Warehouse

Kile, D.E.

2005-01-01

Clay samples from 105 cavities within miarolitic granitic pegmatites throughout the Pikes Peak batholith, in Colorado, were analyzed by powder X-ray diffraction (XRD). Smectite (beidellite), illite, and kaolinite were found within the cavities. Calculation of crystallite-thickness distribution (CTD), mean thickness of the crystallites, and variance in crystallite thickness, as deduced from XRD patterns, allowed a determination of provenance and mode of formation for illite and smectite. Authigenic miarolitic-cavity illite and smectite show lognormal CTDs and larger mean thicknesses of crystallites than do their soil-derived counterparts; non-lognormal illite in a cavity results from mixing of cavity and soil illite. Analysis of mean thickness and thickness variance shows that crystal growth of illite is initiated by a nucleation event of short duration, followed by surface-controlled kinetics. Crystallization of the miarolitic cavity clays is presumed to occur by neoformation from hydrothermal fluids. The assessment of provenance allows a determination of regional and local distributions of clay minerals in miarolitic cavities within the Pikes Peak batholith.

Physico-chemistry and geochemistry of Balengou clay deposit (West Cameroon) with inference to an argillic hydrothermal alteration

NASA Astrophysics Data System (ADS)

Tassongwa, Bernard; Eba, François; Njoya, Dayirou; Tchakounté, Jacqueline Numbem; Jeudong, Narcisse; Nkoumbou, Charles; Njopwouo, Daniel

2017-09-01

Field description and sampling along two pits, granulometry, Atterberg limits, mineralogical (XRD, FTIR, DSC & TGA) and geochemical analyses of the Balengou clays help to determine their characteristics and the genesis of the deposit. The mineralogical composition is comprised of halloysite-kaolinite, quartz, montmorillonite, hematite, anatase, feldspar, zircon, chromite, and apatite. Gibbsite and illite occur at the shallow and deep depth, respectively. Dikes of sand-poor clays contain also cristobalite and tridymite. Pairs of elements Rb-Ba, Rb-Sr, Nb-Ta, Ta-Zr, TiO2-Zr display good positive correlations (R2 > 0.85). REE patterns are highly fractionated (LaN up to 3312, LaN/YbN: 19-10) and are marked by deep Ce and Eu negative anomalies. Immobile element canonical ratios indicate that the protoliths were commendite/pantelerite, rhyolite and dacite, or their plutonic equivalents. Mineralogical and geochemical features lead to the suggestion that the clays derived from an advanced argillic hydrothermal alteration.

Terrain Analysis and Settlement Pattern Survey: Upper Bayou Zourie, Fort Polk, Louisiana.

DTIC Science & Technology

1981-10-01

Louisiana , Vernon Parish 20. AsSrl ACT (Coawnuo - Fevwe eie if nacee.,y ad identify by block number) "- As part of a cultural resources survey of...on the hilltops and along the tops of ridges between the incised drain- ages. The bulk of the soil is a colluvial sand and clay. To the north is a...general exposure of red clayey sands which were probably a product 25 Table 10 16VN441 Site DFI Summary Table FP-31 Material Primary Secondary Tertiary Non

Case Report: Human Exposure to Dioxins from Clay

PubMed Central

Franzblau, Alfred; Hedgeman, Elizabeth; Chen, Qixuan; Lee, Shih-Yuan; Adriaens, Peter; Demond, Avery; Garabrant, David; Gillespie, Brenda; Hong, Biling; Jolliet, Olivier; Lepkowski, James; Luksemburg, William; Maier, Martha; Wenger, Yvan

2008-01-01

Context For the general population, the dominant source of exposure to dioxin-like compounds is food. As part of the University of Michigan Dioxin Exposure Study (UMDES), we measured selected polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and dioxin-like polychlorinated biphenyls (PCBs) in serum of 946 subjects who were a representative sample of the general population in five Michigan counties. Case presentation The total toxic equivalency (TEQ; based on 2005 World Health Organization toxic equivalency factors) of serum from the index case was 211 ppt on a lipid-adjusted basis, which was the highest value observed in the UMDES study population. This subject had no apparent opportunity for exposure to dioxins, except that she had lived on property with soil contaminated with dioxins for almost 30 years, and had been a ceramics hobbyist for > 30 years. Soil from her property and clay that she used for ceramics were both contaminated with dioxins, but the congener patterns differed. Discussion The congener patterns in this subject’s serum, soil, and ceramic clay suggest strongly that the dioxin contamination in clay and not soil was the dominant source of dioxin contamination in her serum. Relevance to public health practice: It appears that ceramic clay, in particular the process of firing clay with unvented kilns, can be a significant nonfood and nonindustrial source of human exposure to dioxins among ceramics hobbyists. The extent of human exposure from ceramic clay is unclear, but it may be widespread. Further work is needed to more precisely characterize the routes of exposure. PMID:18288324

Dynamics of confined reactive water in smectite clay-zeolite composites.

PubMed

Pitman, Michael C; van Duin, Adri C T

2012-02-15

The dynamics of water confined to mesoporous regions in minerals such as swelling clays and zeolites is fundamental to a wide range of resource management issues impacting many processes on a global scale, including radioactive waste containment, desalination, and enhanced oil recovery. Large-scale atomic models of freely diffusing multilayer smectite particles at low hydration confined in a silicalite cage are used to investigate water dynamics in the composite environment with the ReaxFF reactive force field over a temperature range of 300-647 K. The reactive capability of the force field enabled a range of relevant surface chemistry to emerge, including acid/base equilibria in the interlayer calcium hydrates and silanol formation on the edges of the clay and inner surface of the zeolite housing. After annealing, the resulting clay models exhibit both mono- and bilayer hydration structures. Clay surface hydration redistributed markedly and yielded to silicalite water loading. We find that the absolute rates and temperature dependence of water dynamics compare well to neutron scattering data and pulse field gradient measures from relevant samples of Ca-montmorillonite and silicalite, respectively. Within an atomistic, reactive context, our results distinguish water dynamics in the interlayer Ca(OH)(2)·nH(2)O environment from water flowing over the clay surface, and from water diffusing within silicalite. We find that the diffusion of water when complexed to Ca hydrates is considerably slower than freely diffusing water over the clay surface, and the reduced mobility is well described by a difference in the Arrhenius pre-exponential factor rather than a change in activation energy.

Deformation mechanisms and resealing of damage zones in experimentally deformed cemented and un-cemented clay-rich geomaterials, at low bulk strain

NASA Astrophysics Data System (ADS)

Desbois, Guillaume; Urai, Janos L.; Schuck, Bernhardt; Hoehne, Nadine; Oelker, Anne; Bésuelle, Pierre; Viggiani, Gioacchino; Schmatz, Joyce; Klaver, Jop

2017-04-01

A microphysics-based understanding of mechanical and fluid flow properties in clay-rich geomaterials is required for extrapolating better constitutive equations beyond the laboratory's time scales, so that predictions over the long term can be made less uncertain. In this contribution, we present microstructural investigations of rocks specimens sheared in triaxial compression at low bulk strain, by using the combination of broad-ion-beam (BIB) milling and scanning electron microscopy (SEM) to infer deformation mechanisms based on microstructures imaged at sub-micron resolution. Two end-member clay-rich geomaterials from European Underground Laboratories (URL) were analysed: (i) the poorly cemented Boom Clay sediment (BC from URL at Mol/Dessel, Belgium; confining pressure [CP] = 0.375 & 1.5 MPa) and (ii) the Callovo-Oxfordian claystone (COx from the URL at Bure, France; CP = 2 & 10 MPa). Although as a first approximation the inelastic bahvior of cemented and uncemented clay-rich geomaterials can be described by similar pressure-dependent hardening plasticity models, deformed samples in this contribution show very contrasting micro-scale behaviour: microstructures reveal brittle-ductile transitional behaviour in BC, whereas deformation in COx is dominantly cataclastic. In Boom Clay, at meso-scale, shear bands exhibit characteristics that are typical of uncemented small-grained clay-rich materials deformed at high shear strains, consisting of anastomosing shears interpreted as Y- and B-shears, which bound the passively deformed microlithons. At micro- down to nano-scale, the strong shape preferential orientation of clay aggregates in the anastomosing shears is interpreted to be responsible of the shear weakness. More over, the reworking of clay aggregates during deformation contributes to the collapsing of porosity in the shear band. Ductile deformation mechanisms represented by grain-rotation, grain-sliding, bending and granular flow mechanisms are strongly involved for the development of the shear band. At the same time, evidence for dilatancy at low confining pressure indicates that deformation involves also brittle deformation. Our observations strongly suggest that the deformation mostly localizes in those regions of the specimen, where the original grain sizes are smaller. In COx, microstructures show evidence for dominantly cataclastic deformation involving intergranular - transgranular - and - intragranular micro fracturing, grain rotation and clay particle bending mechanisms, down to nm- scale. Micro fracturing of the original fabric results in fragments at a range of scales, which are reworked into a clay-rich cataclastic gouge during frictional flow. Intergranular and minor intragranular micro fracturing occur in regions of non localized deformation, whereas transgranular micro fracturing occurs at regions of localized deformation. These processes are accompanied by dilatancy, but also by progressive decrease of porosity and pore size in the gouge with the non-clay particles embedded in reworked clay. The mechanism of this compaction during shearing is interpreted to be a combination of cataclasis of the cemented clay matrix, and shear-induced rearrangement of clay particles around the fragments of non-clay particles.

Kisameet Glacial Clay: an Unexpected Source of Bacterial Diversity.

PubMed

Svensson, Sarah L; Behroozian, Shekooh; Xu, Wanjing; Surette, Michael G; Li, Loretta; Davies, Julian

2017-05-23

Widespread antibiotic resistance among bacterial pathogens is providing the impetus to explore novel sources of antimicrobial agents. Recently, the potent antibacterial activity of certain clay minerals has stimulated scientific interest in these materials. One such example is Kisameet glacial clay (KC), an antibacterial clay from a deposit on the central coast of British Columbia, Canada. However, our understanding of the active principles of these complex natural substances is incomplete. Like soils, clays may possess complex mixtures of bacterial taxa, including the Actinobacteria , a clade known to be rich in antibiotic-producing organisms. Here, we present the first characterization of both the microbial and geochemical characteristics of a glacial clay deposit. KC harbors surprising bacterial species richness, with at least three distinct community types. We show that the deposit has clines of inorganic elements that can be leached by pH, which may be drivers of community structure. We also note the prevalence of Gallionellaceae in samples recovered near the surface, as well as taxa that include medically or economically important bacteria such as Actinomycetes and Paenibacillus These results provide insight into the microbial taxa that may be the source of KC antibacterial activity and suggest that natural clays may be rich sources of microbial and molecular diversity. IMPORTANCE Identifying and characterizing the resident microbial populations (bacteria, viruses, protozoa, and fungi) is key to understanding the ecology, chemistry, and homeostasis of virtually all sites on Earth. The Kisameet Bay deposit in British Columbia, Canada, holds a novel glacial clay with a history of medicinal use by local indigenous people. We previously showed that it has potent activity against a variety of antibiotic-resistant bacteria, suggesting it could complement our dwindling arsenal of antibiotics. Here, we have characterized the microbiome of this deposit to gain insight into what might make the clay antibacterial. Our analyses suggest that the deposit contains a surprising diversity of bacteria, which live in at least three distinct environments. In addition, the clay harbors bacteria that may have interesting potential as biocontrol/bioremediation agents or producers of novel bioactive compounds. Copyright © 2017 Svensson et al.

Laser ablation ICP-MS and traditional micromorphological techniques applied to the study of different genetic horizons in thin sections: soil genesis and trace element distribution

NASA Astrophysics Data System (ADS)

Scarciglia, Fabio; Barca, Donatella; de Rosa, Rosanna; Pulice, Iolanda; Vacca, Andrea

2010-05-01

This work focuses on an innovative methodological approach to investigate in situ chemical composition of trace and rare earth (REE) elements in discrete soil features from different soil horizons: laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) was applied to clay coatings, pedogenic matrix and skeletal parent rock fragments in thin sections, coupled with traditional pedological investigations, specially clay mineralogy and micromorphology. Analyses were performed on 80 μm-thick sections obtained from undisturbed soil samples, which represent three reddish argillic (Bt) horizons from an Alfisol developed on late Pleistocene slope deposits and three brown organic-mineral (A) horizons from an Entisol formed on Holocene aggrading fluvial sediments in the Muravera area (southeast Sardinia, Italy). Validation of the LA-ICP-MS technique provides in situ accurate and reproducible (RSD 13-18%) analysis of low concentration trace elements in the studied soil samples (0.001-0.1 ppm). Our results showed a high reliability of this method on soil thin sections and revealed that concentrations of trace and rare earth elements in the different portions of a soil profile can be used to investigate their distribution, as a response to soil-forming processes. A general trend of increase of most trace elements from rock fragments to (both clayey and organic-rich) soil matrix, to clay coatings in argillic horizons is clearly highlighted. On this basis a prominent role of pedogenetic processes in element fractionation and distribution during weathering can be supposed. In particular, element adsorption onto reactive sites of organic matter and clay particles (and possibly Fe-oxyhydroxides) and clay illuviation appear the main pedogenetic processes able to promote element enrichment after their release from the weathering of primary minerals. As clay coatings exhibit the highest concentration of trace elements, and specifically of REEs, and represent the most mobile solid phase in the soil profile, this tool can be used as a reliable indicator of soil weathering after a preliminary assessment of illuvial clay pedofeatures. This feature is consistent with a progressively increasing time of soil development, testified by the older age of the Alfisol than the Entisol profile. Such a result is also supported by a comparison of trace element concentrations between the clay and the fine earth fractions of the bulk soil horizons performed with ICP-MS in solution, showing REE enrichment in the clays from the former soil. Moreover, trace element patterns show some discontinuous trends among soil features of different horizons, coherently with erosive and/or depositional discontinuities described in the field.

Sorption characteristics of cadmium in a clay soil of Mae Ku creek, Tak Province, Thailand

NASA Astrophysics Data System (ADS)

Thunyawatcharakul, P.; Chotpantarat, S.

2018-05-01

Mae Sot is a district in Tak province, the northern part of Thailand where has encountered with cadmium (Cd) contaminated in soils. Exposure of Cd can lead to severe health effect, for examples, bone softening, osteoporosis, renal dysfunction, and Itai-Itai disease. This study aims at elucidating sorption behavior of Cd in the contaminated soil collected from Mae Ku creek, Mae Sot district, Thailand. Batch sorption experiment was conducted in order to investigate sorption characteristics of Cd onto the contaminated soil. The soil sample taken from the study area consists of 26% sand, 16% silt 58% clay, which categorized as a clay soil, based on USDA classification. Soil pH is slightly alkaline (pH∼7.7) and organic matter in the soil is 2.93%. The initial concentration in the batch sorption experiment was in the range from 0- 200 ppm. The result from the batch sorption experiment showed that soil sample can adsorb Cd up to 173.5 ppm and the sorption behavior of the soil sample can be well described by Freundlich isotherm, indicating the multilayer sorption (R2 = 0.9964), with Freundlich constants of 0.312 and 1.760 L g-1 for 1/n and Kf, respectively.

The Physical Behavior of Stabilised Soft Clay by Electrokinetic Stabilisation Technology

NASA Astrophysics Data System (ADS)

Azhar, A. T. S.; Nordin, N. S.; Azmi, M. A. M.; Embong, Z.; Sunar, N.; Hazreek, Z. A. M.; Aziman, M.

2018-04-01

Electrokinetic Stabilisation (EKS) technology is the combination processes of electroosmosis and chemical grouting. This technique is most effective in silty and clayey soils where the hydraulic conductivity is very low. Stabilising agents will assist the EKS treatment by inducing it into soil under direct current. The movement of stabilising agents into soil is governed by the principle of electrokinetics. The aim of this study is to evaluate the physical behavior of soft soil using the EKS technology as an effective method to strengthen soft clay soils with calcium chloride (CaCl2) as the stabilising agent. Stainless steel plates were used as the electrodes, while 1.0 mol/l of CaCl2 was used as the electrolyte that fed at the anode compartment. Soft marine clay at Universiti Tun Hussein Onn Malaysia was used as the soil sample. The EKS treatment was developed at Research Centre for Soft Soil (RECESS), UTHM with a constant voltage gradient (50 V/m) in 21 days. The result shows that the shear strength of treated soil was increased across the soil sample. The treated soil near the cathode showed the highest value of shear strength (24.5 – 33 kPa) compared with the anode and in the middle of the soil sample.

Analysis of clay smoking pipes from archeological sites in the region of the Guanabara Bay (Rio de Janeiro, Brazil) by FT-IR

NASA Astrophysics Data System (ADS)

Freitas, Renato P.; Ribeiro, Iohanna M.; Calza, Cristiane; Oliveira, Ana L.; Silva, Mariane L.; Felix, Valter S.; Ferreira, Douglas S.; Coelho, Felipe A.; Gaspar, Maria D.; Pimenta, André R.; Medeiros, Elanio A.; Lopes, Ricardo T.

2016-06-01

In this study, twenty samples of clay smoking pipes excavated in an 18 km2 area between the Macacu and Caceribu rivers, in the municipality of Itaboraí, Rio de Janeiro, Brazil were analyzed by FT-IR technique. The samples, excavated in different archeological sites of the region, are dated between the seventeenth and the nineteenth centuries and are part of the material culture left by Africans and African descendants that lived in the complex. FT-IR analyses and complementary SEM-EDS studies showed that the clay paste used in the manufacture of smoking pipes, mostly handcrafted, is composed of quartz, feldspar, phyllosilicates and iron oxides. Multivariate statistical tests (PCA) were applied to FT-IR data to assess the interactions between the archeological sites. The results indicated that one archeological site - Macacu IV - is greatly related to the other sites. The results obtained have helped archeologists and anthropologists in better understanding the manufacturing process employed in ancient ceramic artifacts produced during the period of colonial Brazil.

Analysis of clay smoking pipes from archeological sites in the region of the Guanabara Bay (Rio de Janeiro, Brazil) by FT-IR.

PubMed

Freitas, Renato P; Ribeiro, Iohanna M; Calza, Cristiane; Oliveira, Ana L; Silva, Mariane L; Felix, Valter S; Ferreira, Douglas S; Coelho, Felipe A; Gaspar, Maria D; Pimenta, André R; Medeiros, Elanio A; Lopes, Ricardo T

2016-06-15

In this study, twenty samples of clay smoking pipes excavated in an 18km(2) area between the Macacu and Caceribu rivers, in the municipality of Itaboraí, Rio de Janeiro, Brazil were analyzed by FT-IR technique. The samples, excavated in different archeological sites of the region, are dated between the seventeenth and the nineteenth centuries and are part of the material culture left by Africans and African descendants that lived in the complex. FT-IR analyses and complementary SEM-EDS studies showed that the clay paste used in the manufacture of smoking pipes, mostly handcrafted, is composed of quartz, feldspar, phyllosilicates and iron oxides. Multivariate statistical tests (PCA) were applied to FT-IR data to assess the interactions between the archeological sites. The results indicated that one archeological site - Macacu IV - is greatly related to the other sites. The results obtained have helped archeologists and anthropologists in better understanding the manufacturing process employed in ancient ceramic artifacts produced during the period of colonial Brazil. Copyright © 2016 Elsevier B.V. All rights reserved.

Using Layer-by-Layer Coating and Nanocomposite Technologies to Improve the Barrier Properties of Polymeric Materials

NASA Astrophysics Data System (ADS)

Soltani, Iman

Means for improving barrier properties of polymers against gases, particularly for promoting their applications as packaging materials, are divided into surface coating and embedding nanoparticles in the bulk of the polymeric membranes. In this research, we mainly investigated improvement in barrier properties of polymers against oxygen and carbon dioxide, through layer-by-layer (LBL) coating and bulk nanocomposite methods. Initially, we studied the morphology of layer-by-layer assemblies comprising alternating layers of polyelectrolyte (PE) and natural montmorillonite (MMT) platelets, where polyethyleneterephthalate ionomer was used as our proposed alternative PE, to be compared with already examined polyethyleneimine. For both investigated PEs, while microscopic images showed the formation of tortuous networks of galleries between subsequent layers of oriented clay platelets parallel to the substrate surface, x-ray diffractometry (XRD) traces pointed to the intercalation of PE layers between clay platelets. As a confirmation of forming tortuous networks between oriented and high aspect ratio clay platelets to increase the path length of diffusing gas species dramatically, LBL-coated polystyrene-based membranes demonstrated pronounced decreases in permeability of oxygen and carbon dioxide (e.g. about the scale of 500 times decrease in permeability, with only five cycles of bilayer deposition). Before LBL deposition, the surface of the hydrophobic polymeric substrate was pretreated with oxygen plasma to improve its interaction with the coating. In the next study, previously LBL-coated samples were melt pressed in a cyclic manner to embed and to crush the coating inside the polystyrene-based matrix, aiming the exfoliated polymer-clay nanocomposites. The morphological investigations by transmission electron microscopy (TEM) revealed the tortuous internal structure of crushed LBL assemblies' portions, mainly comprising swollen intercalated stacks of clay, as well as flocculated exfoliated tactoids of a few clay platelets, down to about 2nm thickness. Moreover, XRD traces confirmed this increase in intercalation and exfoliation of clay platelets. Following ahead, dynamic mechanical thermal analysis (DMA) revealed significant increases in the storage and loss moduli values for our PNCs over those of pristine polystyrenebased matrix, hypothesizing the occurrence of substantial interactions between clay and the polymeric matrix, induced by intervening effect of PE interlayers. Also, permeation experiments showed noticeable improvement in gas barrier properties of processed PNCs. Considering the low content of clay particles and their limited level of global dispersions throughout the matrix, it may theorize the significant efficiency of high aspect ratio and tortuous LBL assemblies portions, oriented (induced by cycling pressing into thin films) perpendicular to the permeants' path routes. Thus, it might act almost as scavenging hubs against transport of diffusing gases. Finally, using PVAc, as the matrix, with this novel two-step approach of preparing PNCs, showed relatively higher clay content, when prepared with similar coating conditions. Also, DMA and permeation experiments pointed to significant improvements in mechanical and gas barrier properties of the PNCs, prepared by only 25 times melt pressing steps. Additionally, XRD traces postulated occurrence of noticeable irregularities in the interdistance of clay platelets. So, it is conjectured that semi-hydrophilic PVAc matrix promotes stronger interactions with clay particles, compared with those of polystyrene-based PNCs. However, moderate global dispersion of clay throughout the matrix points to the insufficient efficiency of repetitive melt pressing procedure to apply intensive enough stresses on samples, in order to overcome internal cohesion in LBL assemblies, which established initial intercalation and exfoliation in the otherwise aggregately clustered natural clay platelets. In addition, it is postulated that possibly occurring slight thermal degradations induce adverse results on the dispersion level and aforementioned properties of PNCs, processed over extended times.

Compositional controls on early diagenetic pathways in fine-grained sedimentary rocks: Implications for predicting unconventional reservoir attributes of mudstones

USGS Publications Warehouse

Keller, Margaret A.; Macquaker, Joe H.S.; Taylor, Kevin G.; Polya, David

2014-01-01

Diagenesis significantly impacts mudstone lithofacies. Processes operating to control diagenetic pathways in mudstones are poorly known compared to analogous processes occurring in other sedimentary rocks. Selected organic-carbon-rich mudstones, from the Kimmeridge Clay and Monterey Formations, have been investigated to determine how varying starting compositions influence diagenesis.The sampled Kimmeridge Clay Formation mudstones are organized into thin homogenous beds, composed mainly of siliciclastic detritus, with some constituents derived from water-column production (e.g., coccoliths, S-depleted type-II kerogen, as much as 52.6% total organic carbon [TOC]) and others from diagenesis (e.g., pyrite, carbonate, and kaolinite). The sampled Monterey Formation mudstones are organized into thin beds that exhibit pelleted wavy lamination, and are predominantly composed of production-derived components including diatoms, coccoliths, and foraminifera, in addition to type-IIS kerogen (as much as 16.5% TOC), and apatite and silica cements.During early burial of the studied Kimmeridge Clay Formation mudstones, the availability of detrital Fe(III) and reactive clay minerals caused carbonate- and silicate-buffering reactions to operate effectively and the pore waters to be Fe(II) rich. These conditions led to pyrite, iron-poor carbonates, and kaolinite cements precipitating, preserved organic carbon being S-depleted, and sweet hydrocarbons being generated. In contrast, during the diagenesis of the sampled Monterey Formation mudstones, sulfide oxidation, coupled with opal dissolution and the reduced availability of both Fe(III) and reactive siliciclastic detritus, meant that the pore waters were poorly buffered and locally acidic. These conditions resulted in local carbonate dissolution, apatite and silica cements precipitation, natural kerogen sulfurization, and sour hydrocarbons generation.Differences in mud composition at deposition significantly influence subsequent diagenesis. These differences impact their source rock attributes and mechanical properties.

Structural architecture and petrophysical properties of the Rocca di Neto extensional fault zone developed in the shallow marine sediments of the Crotone Basin (Southern Apennines, Italy).

NASA Astrophysics Data System (ADS)

Pizzati, Mattia; Balsamo, Fabrizio; Iacumin, Paola; Swennen, Rudy; Storti, Fabrizio

2017-04-01

In this contribution we describe the architecture and petrophysical properties of the Rocca di Neto extensional fault zone in loose and poorly lithified sediments, located in the Crotone forearc basin (south Italy). To this end, we combined fieldwork with microstructural observations, grain size analysis, and in situ permeability measurements. The studied fault zone has an estimated maximum displacement of 80-90 m and separates early Pleistocene age (Gelasian) sands in the footwall from middle Pleistocene (Calabrian) silty clay in the hangingwall. The analysed outcrop consists of about 70 m section through the fault zone mostly developed in the footwall block. Fault zone consists of four different structural domains characterized by distinctive features: (1) <1 m-thick fault core (where the majority of the displacement is accommodated) in which bedding is transposed into foliation imparted by grain preferential orientation and some black gouges decorate the main slip surfaces; (2) zone of tectonic mixing characterized by a set of closely spaced and anastomosed deformation bands parallel to the main slip surface; (3) about 8 m-thick footwall damage zone characterized by synthetic and antithetic sets of deformation bands; (4) zone of background deformation with a few, widely-spaced conjugate minor faults and deformation bands. The boundary between the relatively undeformed sediments and the damage zone is not sharp and it is characterized by a progressive decrease in deformation intensity. The silty clay in the hangingwall damage zone is characterized by minor faults. Grain size and microstructural data indicate that particulate flow with little amount of cataclasis is the dominant deformation mechanism in both fault core rocks and deformation bands. Permeability of undeformed sediments is about 70000 mD, whereas the permeability in deformation bands ranges from 1000 to 18000 mD; within the fault core rocks permeability is reduced up to 3-4 orders of magnitude respect to the undeformed domains. Structural and petrophysical data suggest that the Rocca di Neto fault zone may compartmentalize the footwall block due to both juxtaposition of clay-rich lithology in the hangingwall and the development of low permeability fault core rocks.

Assessing the Relative Mobility of Submarine Landslides from Deposit Morphology and Physical Properties: an Example from Nankai Trough, Offshore Japan

NASA Astrophysics Data System (ADS)

Sawyer, D.; Moore, Z. T.

2014-12-01

A prominent landslide deposit in the Slope Basin seaward of the Megasplay Fault in the Nankai Trough was emplaced by a high-mobility landslide based on analysis of physical properties and seismic geomorphology. Slide acceleration is a critical variable that determines amplitude of slide-generated tsunami but is many times a variable with large uncertainty. In controlled laboratory experiments, the ratio of the shear stress to yield strength, defined as the Flow Factor, controls a wide spectrum of mass movement styles from slow, retrogressive failure to rapid, liquefied flows. We apply the laboratory Flow Factor approach to a natural landslide in the Nankai Trough by constraining pre-failure particle size analysis and porosity. Several mass transport deposits (MTDs), were drilled and cored at Site C0021 in the Nankai Trough during Integrated Ocean Drilling Program (IODP) Expedition 338. The largest, MTD-6, occurs at 133-176 meters below seafloor and occurred approximately 0.87 Mya. Slide volume is 2 km3, transport distance is 5 km, and average deposit thickness is 50 m (maximum 180 m). Pre-failure water content was estimated from shallow sediments at Site C0018 (porosity = 72%). The average grain size distribution is 39% clay-sized, 58% silt-sized, and 3% sand-size particles as determined by hydrometer analyses of the MTD. Together, the porosity and clay fraction predict a Flow Factor of approximately 4, which corresponds to a relatively high mobility slide. We interpret this result to indicate the landslide that created MTD-6 was a single event that transported the slide mass relatively rapidly as opposed to a slow, episodic landslide event. This is supported by the observation of a completely evacuated source area with no remnant blocks or retrogressive headscarp and the internally chaotic seismic facies with large entrained blocks. Future works will focus on the tsunamigenic potential of this high mobility slide. This approach can be extended to other field settings characterized by fine-grained siliciclastics and where porosity and clay content are known.

Application of Spectral Gamma Ray for Lithofacies and Paleo-environmental Interpretation: A Case Study from the Late Ordovician Glaciogenic Deposits, Saudi Arabia

NASA Astrophysics Data System (ADS)

Alqubalee, Abdullah; Abdullatif, Osman; Babalola, Lamidi

2017-04-01

This study is an integral part of multidisciplinary research being carried out on the Late Ordovician Sarah Formation in the Rub' Al-Khali Basin, Saudi Arabia. Sarah Formation proved to be important target for tight gas reservoir in Saudi Arabia. This study integrates lithofacies characteristics and spectral Gamma Ray of core samples so as to identify and differentiate among different depositional environments. Thorium (Th, ppm) and potassium (K, %) are acquired with approximately a reading point per inch using high-resolution Spectral Core Gamma. The cores description and analysis from six exploratory wells revealed four depositional environments ranging from the glaciofluvial, glaciolacustrine delta, subglacial to the nearshore environments. Based on lithofacies and geochemical analysis of the core samples, four groups of lithofacies including sandstone (G1), claystone and/or argillaceous sandstone (G2), calcareous and/or evaporitic sandstone (G3), and diamictites (G4) were recognized in each well. The bivariate plots of Th and K were used to delineate the minerals contents in each core and environment. The results showed that the G1 facies of the nearshore and glaciofluvial environments are characterized by similar distribution patterns of these elements exhibiting lower clay minerals variations than that in the other groups of lithofacies. These patterns consist of two mineral groups, the first one includes illite and montmorillonite clay minerals while the second one includes mica, glauconite, and feldspar. By contrast, G1 and G2 lithofacies of the glaciolacustrine delta environment are characterized by a range of clay minerals. However, G3 of this environment exhibits similar pattern of the nearshore and the glaciofluvial environments This is because the grains of G3 are cemented by anhydrite rather than by clays. Based on the lithological characteristic, matrix-supported and clast-supported diamictites were identified in the subglacial environment. The differences between these two lithofacies were clearly detected using Th/K plot. Both diamictites are characterized by a range of minerals including illite, mixed layer clays, glauconite, and feldspar. The matrix-supported diamictites contain higher proportions of these minerals. This study indicates that the relationship between Th and K can be used to predict the types of lithofacies and clay contents in different glaciogenic depositional environments. In addition, it can be used to predict the relative amounts of the clay minerals in each lithofacies. In turn, identifying the types and the amounts of clay minerals in lithofacies facilitate the prediction of reservoir quality and eventually lead to enhancement of their development and productivity.

Early Jurassic clay authigenesis in the Central Appalachian Valley and Ridge province; infiltration of surface-derived fluids during Pangean rifting

NASA Astrophysics Data System (ADS)

Lynch, E. A.; van der Pluijm, B.; Vennemann, T. W.

2017-12-01

The eastern margin of North America has a protracted and intricate tectonic history. The terminal collision of Gondwana and Laurentia in the late Paleozoic formed the Appalachian mountain belt, a trans-continental orogen that persisted for almost 100 million years until Mesozoic break-up of the supercontinent Pangea. A host of studies have targeted the evolution and migration of fluids through Appalachian crust in an effort to understand how fluid promotes mass and heat redistribution, and mediates crustal deformation, particularly during the assembly of Pangea. Folded clay units from the Central Appalachian Valley and Ridge province were sampled for stable and radiogenic isotope analysis. Separation of samples into different grain-size fractions characterizes detrital (host) and authigenic (neomineralized) clays. Stable H-isotope compositions reveal a systematic pattern with varying proportions of illite polytypes—the finer, younger fraction is D-depleted compared to the coarser, primarily detrital fraction. For each individual location, the H-isotopic composition of the fluid from which the authigenic population was grown is calculated. δDVSMOW of these fluids has a range from -77 to -52 ± 2 ‰, consistent with a surface-derived fluid source. The notably negative values for several samples indicates a meteoric composition of moderate to high elevation origin, suggesting that they are not connate waters, but instead preserve infiltration of fluids due to fracture-induced permeability. Key to this interpretation is 40Ar/39Ar-dating of a subset of these samples that reveals a post-orogenic age for authigenic clay mineralization in the Early Jurassic ( 180 Ma). These ages are evidence that surface fluid infiltration was unrelated to the Appalachian orogeny, but coeval with (upper) crustal extension from the initial break-up of Pangea and the emplacement of the Central Atlantic Magmatic Province.

Shear weakening for different lithologies observed at different saturation stages

NASA Astrophysics Data System (ADS)

Diethart-Jauk, Elisabeth; Gegenhuber, Nina

2018-01-01

For this study, samples from different lithologies ("Leitha"-limestone, "Dachstein"-limestone, "Haupt"-dolomite, "Bunt"-sandstone, Grey Berea sandstone, granite, quartzite and basalt) were selected. Samples were dried at 70 °C, respectively 105 °C and were saturated with brine. Mass, porosity, permeability, compressional and shear wave velocity were determined from dry and brine saturated samples at laboratory conditions, based on an individual measurement program. Shear modulus was calculated to find out, if shear weakening exists for the dataset. Shear weakening means that shear modulus of dry samples is higher than of saturated samples, but it is assumed that shear modulus is unaffected by saturation. "Dachstein"-limestone and basalt show shear weakening, quartzite samples show both weakening and hardening. Granite samples are affected by temperature, after drying with 105 °C no change can be observed anymore. "Bunt"-sandstone samples show a change in the shear modulus in a small extent, although they may contain clay minerals. The other lithologies show no effect. Explanations for carbonate samples can be the complicated pore structure, for basalt it could be that weathering creates clay minerals which are known as causes for a change of the shear modulus. Fluid viscosity can also be an important factor.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Barber, A.J.; Tjokrosapoetro, S.; Charlton, T.R.

In Timor, eastern Indonesia, where the northern margin of the Australian continent is colliding with the Banda Arc, Australian continental margin sediments are being incorporated into an imbricate wedge, which passes northward into a foreland fold and thrust belt. Field mapping in Timor has shown that scale clays, containing irregularly shaped or phacoidal blocks (up to several meters long) and composed of a wide range of lithologies derived from local stratigraphic units, occur in three environments: along wrench faults, as crosscutting shale diapirs, and associated with mud volcanoes. A model is proposed linking these phenomena. Shales become overpressured as amore » result of overthrusting; this overpressure is released along vertical wrench faults, which cut through the overthrust units; overpressured shales containing blocks of consolidated units rise along the fault zones as shale diapirs; and escaping water, oil, and gas construct mud volcanoes at the surface. 6 figures, 1 table.« less

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

NASA Astrophysics Data System (ADS)

Bonaccorsi, R.; McKay, C. P.

2009-12-01

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

An AEM-TEM study of weathering and diagenesis, Abert Lake, Oregon: II. Diagenetic modification of the sedimentary assemblage

USGS Publications Warehouse

Banfield, J.F.; Jones, B.F.; Veblen, D.R.

1991-01-01

This paper compares the mineralogy and chemistry of clay minerals in sediments from various depths and positions in Abert Lake and surrounding playa with those of the weathered materials entering the lake in order to reveal the nature and extent of post-depositional mineralogical modification. Analytical electron microscope (AEM) data from individual clay particles reveal that each sample is comprised of a highly inhomogeneous smectite assemblage. The thin clay flakes (commonly less than 10 nm wide) display a complete range in octahedral sheet compositions from nearly dioctahedral to nearly trioctahedral. The very abundant Mg-rich lake smectites with an estimated composition K0.29(Al0.23-Mg2.16Fe0.30)Si3.80Al0.20O10(OH)2 are not formed by weathering. This confirms the importance of diagenetic Mg uptake. Lattice-fringe imaging failed to reveal distinct brucite-like or vermiculite-like layers, suggesting that interstratifications of this type are rare or absent. Siliceous coatings on clay particles (identified by silica excess in smectite analyses) seem to favor topotactic overgrowth of stevensite rather than addition of brucite-like layers to the dioctahedral nuclei. The growth of K-stevensite dilutes the Al content of the crystal, and thus the increasing diagenetic modification reduces rather than supplements its illite component. Smectite compositions within individual samples were highly variable, yet source-related characteristics such as the abundance of Fe-rich smectite were apparent. Little evidence for systematic K or Mg enrichment with depth was identified in samples from depths of down to 16 feet below the sediment-water interface. The most magnesian assemblages are associated both with weathering sources of Mg-rich smectite and playa environments subjected to repeated wetting and drying cycles. Thus, the observations suggest that clay compositions primarily reflect changes in lake levels, brine composition, and source characteristics, rather than time and depth/compaction effects. Other diagenetic reactions in the sediment include recrystallization of Na-rich silica gel and diatom fragments. Abundant, submicron-sized, untwinned, euhedral crystals of K-feldspar are interpreted to be authigenic in origin. ?? 1991.

Modeling tsunamis induced by retrogressive submarine landslides

NASA Astrophysics Data System (ADS)

Løvholt, F.; Kim, J.; Harbitz, C. B.

2015-12-01

Enormous submarine landslides having volumes up to thousands of km3 and long run-out may cause tsunamis with widespread effects. Clay-rich landslides, such as Trænadjupet and Storegga offshore Norway commonly involve retrogressive mass and momentum release mechanisms that affect the tsunami generation. Therefore, such landslides may involve a large amount of smaller blocks. As a consequence, the failure mechanisms and release rate of the individual blocks are of importance for the tsunami generation. Previous attempts to model the tsunami generation due to retrogressive landslides are few, and limited to idealized conditions. Here, we review the basic effects of retrogression on tsunamigenesis in simple geometries. To this end, two different methods are employed for the landslide motion, a series block with pre-scribed time lags and kinematics, and a dynamic retrogressive model where the inter-block time lag is determined by the model. The effect of parameters such as time lag on wave-height, wave-length, and dispersion are discussed. Finally, we discuss how the retrogressive effects may have influenced the tsunamis due to large landslides such as the Storegga slide. The research leading to these results has received funding from the Research Council of Norway under grant number 231252 (Project TsunamiLand) and the European Union's Seventh Framework Programme (FP7/2007-2013) under grant agreement 603839 (Project ASTARTE).

New approach of a transient ICP-MS measurement method for samples with high salinity.

PubMed

Hein, Christina; Sander, Jonas Michael; Kautenburger, Ralf

2017-03-01

In the near future it is necessary to establish a disposal for high level nuclear waste (HLW) in deep and stable geological formations. In Germany typical host rocks are salt or claystone. Suitable clay formations exist in the south and in the north of Germany. The geochemical conditions of these clay formations show a strong difference. In the northern ionic strengths of the pore water up to 5M are observed. The determination of parameters like K d values during sorption experiments of metal ions like uranium or europium as homologues for trivalent actinides onto clay stones are very important for long term safety analysis. The measurement of the low concentrated, not sorbed analytes commonly takes place by inductively coupled plasma mass spectrometry (ICP-MS). A direct measurement of high saline samples like seawater with more than 1% total dissolved salt content is not possible. Alternatives like sample clean up, preconcentration or strong dilution have more disadvantages than advantages for example more preparation steps or additional and expensive components. With a small modification of the ICP-MS sample introduction system and a home-made reprogramming of the autosampler a transient analysing method was developed which is suitable for measuring metal ions like europium and uranium in high saline sample matrices up to 5M (NaCl). Comparisons at low ionic strength between the default and the transient measurement show the latter performs similarly well to the default measurement. Additionally no time consuming sample clean-up or expensive online dilution or matrix removal systems are necessary and the analysation shows a high sensitivity due to the data processing based on the peak area. Copyright © 2016 Elsevier B.V. All rights reserved.

Alteration of bentonite when contacted with supercritical CO2

NASA Astrophysics Data System (ADS)

Jinseok, K.; Jo, H. Y.; Yun, S. T.

2014-12-01

Deep saline formations overlaid by impermeable caprocks with a high sealing capacity are attractive CO2 storage reservoirs. Shales, which consist of mainly clay minerals, are potential caprocks for the CO2 storage reservoirs. The properties of clay minerals in shales may affect the sealing capacity of shales. In this study, changes in clay minerals' properties when contacted with supercritical (SC) CO2 at various conditions were investigated. Bentonite, whichis composed of primarily montmorillonite, was used as the clay material in this study. Batch reactor tests on wet bentonite samples in the presence of SC CO2 with or without aqueous phases were conducted at high pressure (12 MPa) and moderate temperature (50 oC) conditions for a week. Results show that the bentonite samples obtained from the tests with SC CO2 had less change in porosity than those obtained from the tests without SC CO2 (vacuum-drying) at a given reaction time, indicating that the bentonite samples dried in the presence of SC CO2 maintained their structure. These results suggest that CO2 molecules can diffuse into interlayer of montmorillonite, which is a primary mineral of bentonite, and form a single CO2 molecule layer or double CO2 molecule layers. The CO2 molecules can displace water molecules in the interlayer, resulting in maintaining the interlayer spacing when dehydration occurs. Noticeable changes in reacted bentonite samples obtained from the tests with an aqueous phase (NaCl, CaCl2, or sea water) are decreases in the fraction of plagioclase and pyrite and formation of carbonate minerals (i.e., calcite and dolomite) and halite. In addition, no significant exchanges of Na or Ca on the exchangeable complex of the montmorillonite in the presence of SC CO2 occurred, resulting in no significant changes in the swelling capacity of bentonite samples after reacting with SC CO2 in the presence of aqueous phases. These results might be attributed by the CO2 molecule layer, which prevents diffusion of ions into the interlayer.

Monomers of cutin biopolymer: sorption and esterification on montmorillonite surfaces

NASA Astrophysics Data System (ADS)

Olshansky, Yaniv; Polubesova, Tamara; Chefetz, Benny

2013-04-01

One of the important precursors for soil organic matter is plant cuticle, a thin layer of predominantly lipids that cover all primary aerial surfaces of vascular plants. In most plant species cutin biopolymer is the major component of the cuticle (30-85% weight). Therefore cutin is the third most abundant plant biopolymer (after lignin and cellulose). Cutin is an insoluble, high molecular weight bio-polyester, which is constructed of inter-esterified cross linked hydroxy-fatty acids and hydroxyepoxy-fatty acids. The most common building blocks of the cutin are derivatives of palmitic acid, among them 9(10),16 dihydroxy palmitic acid (diHPA) is the main component. These fatty acids and their esters are commonly found in major organo-mineral soil fraction-humin. Hence, the complexes of cutin monomers with minerals may serve as model of humin. Both cutin and humin act as adsorption efficient domains for organic contaminants. However, only scarce information is available about the interactions of cutin with soil mineral surfaces, in particular with common soil mineral montmorillonite. The main hypothesize of the study is that adsorbed cutin monomers will be reconstituted on montmorillonite surface due to esterification and oligomerization, and that interactions of cutin monomers with montmorillonite will be affected by the type of exchangeable cation. Cutin monomers were obtained from the fruits of tomato (Lycopersicon esculentum). Adsorption of monomers was measured for crude Wyoming montmorillonites and montmorillonites saturated with Fe3+ and Ca2+. To understand the mechanism of monomer-clay interactions and to evaluate esterification on the clay surface, XRD and FTIR analyses of the montmorillonite-monomers complexes were performed. Our results demonstrated that the interactions of cutin monomers with montmorillonite are affected by the type of exchangeable cation. Isotherms of adsorption of cutin monomers on montmorillonites were fitted by a dual mode model of sorption, which combines site specific adsorption mechanism (Langmuir) and partitioning mechanism. Adsorption of monomers by Fe3+-montmorillonite was higher than for Ca2+ and crude -montmorillonites. XRD measurements showed expansion of d-spacing of montmorillonite samples with the increase in diHPA loading from 12.32, 12.66 and 12.17 Å for Fe3+- Ca2+- and crude-montmorillonite up to 16.84, 16.62 and 16.79 Å for organo-clay complexes of Fe3+-, Ca2+- and crude-montmorillonites respectively. This significant expansion of d-spacing suggests interlayer, and probably, multilayer diHPA adsorption by montmorillonite. Based on FTIR data we suggest that diHPA forms inner-sphere complexes with Fe3+-montmorillonite surface but not with Ca2+ and crude-montmorillonites. However all montmorillonite samples induce esterification and oligomerization of the monomers, which was demonstrated by FTIR spectra of the organo-montmorillonite complexes and by LC-MS analysis of the organic material extracted from organo-clay complexes. These results confirmed our hypothesis about oligomerization of cuticular monomers on mineral surfaces. We assume that esterification and oligomerization of monomers on montmorillonite surfaces simulate similar soil processes, which result in the formation of soil organo-mineral complexes and humin.

Characterization of electron-beam-modified surface coated clay fillers and their influence on physical properties of rubbers

NASA Astrophysics Data System (ADS)

Ray, Sudip; Bhowmick, Anil K.; Sarma, K. S. S.; Majali, A. B.; Tikku, V. K.

2002-12-01

A novel process of surface modification of clay filler has been developed by coating this with an acrylate monomer, trimethylol propane triacrylate (TMPTA) or a silane coupling agent, triethoxy vinyl silane (TEVS) followed by electron beam irradiation. Characterization of these surface modified fillers has been carried out by Fourier-transform infrared analysis (FTIR), electron spectroscopy for chemical analysis (ESCA), wettability by dynamic wicking method measuring the rise of a liquid through a filler-packed capillary tube and water flotation test, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), thermogravimetric analysis (TGA), and X-ray diffraction (XRD). Presence of the acrylate and the silane coupling agent on the modified fillers has been confirmed from FTIR, ESCA, and EDX studies, which has also been supported by TGA studies. The contact angle measurement by dynamic wicking method suggests improvement in hydrophobicity of the treated fillers, which is supported by water flotation test especially in the case of silanized clay. However, XRD studies demonstrate that the entire modification process does not affect the bulk properties of the fillers. Finally, both unmodified and modified clay fillers have been incorporated in styrene butadiene rubber (SBR) and nitrile rubber (NBR). Rheometric and mechanical properties reveal that there is a definite improvement using these modified fillers specially in the case of silanized clay compared to the control sample, probably due to successful enhancement in interaction between the treated clay and the base polymer.

Effect of temperature and aging time on the rheological behavior of aqueous poly(ethylene glycol)/Laponite RD dispersions.

PubMed

Morariu, Simona; Bercea, Maria

2012-01-12

The viscoelastic properties of 2% poly(ethylene glycol) aqueous solutions containing Laponite RD from 1% to 4% were investigated by oscillatory and flow measurements in the temperature range of 15-40 °C. The enhancement of the clay content from mixture causes the increase of the viscoelastic moduli and the change of the flow from liquid-like behavior (Maxwellian fluid) to a solid-like one at a set temperature. The longest relaxation times (τ(1)) of the mixtures with low clay concentrations (1% and 2%) are not affected by changes in temperature unlike the samples having high content of clay at which τ(1) increases above 30 °C and below 17.5 °C. The characteristic behavior of the mixtures with the high clay concentration could be explained by considering the effect of Brownian motion on the network structure formed in these dispersions as well as by the poor solubility of poly(ethylene glycol) in water at high temperatures. The flow activation energy was determined and discussed. An abrupt increase of the flow activation energy was evidenced between 2% and 3% Laponite RD. The rheological measurements carried out at different rest times showed a decrease of the gelation time from 1 week to 2 h when the clay concentration increases from 2% to 4%. The aging kinetics of poly(ethylene glycol)/Laponite RD/water mixtures, investigated at 25 °C, revealed the increase of the viscosity-rate kinetic constant by increasing the clay concentration.

Improved Yield of High Molecular Weight DNA Coincides with Increased Microbial Diversity Access from Iron Oxide Cemented Sub-Surface Clay Environments

DOE PAGES

Hurt, Jr., Richard A.; Robeson II, Michael S.; Shakya, Migun; ...

2014-07-14

Despite more than three decades of progress, efficient nucleic acid extraction from microbial communities has remained difficult, particularly from clay environments. Lysis with concentrated guanidine followed by concentrated sodium phosphate extraction supported DNA and RNA recovery from high iron, low humus content clay. Alterating the extraction pH or using other ionic solutions (Na 2SO 4 and NH 4H 2PO 4) yielded no detectable nucleic acid. DNA recovered using a lysis solution with 500 mM phosphate buffer (PB) followed by a 1 M PB wash was 15.22±2.33 g DNA/g clay, with most DNA consisting of >20 Kb fragments, compared to 2.46±0.25more » g DNA/g clay with the Powerlyzer soil DNA system (MoBio). Increasing [PB] in the lysis reagent coincided with increasing DNA fragment length. Rarefaction plots based on16S rRNA (V1/V3 region) pyrosequencing libraries from A-horizon and clay soils showed an ~80% and ~400% larger accessed diversity compared to a previous grinding protocol or the Powerlyzer soil DNA system, respectively. The observed diversity from the Firmicutes showed the strongest increase with >3-fold more bacterial species recovered using this system. Additionally, some OTU's having more than 100 sequences in these libraries were absent in samples extracted using the PowerLyzer reagents or the previous lysis method.« less

Improved Yield of High Molecular Weight DNA Coincides with Increased Microbial Diversity Access from Iron Oxide Cemented Sub-Surface Clay Environments

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hurt, Jr., Richard A.; Robeson II, Michael S.; Shakya, Migun

Despite more than three decades of progress, efficient nucleic acid extraction from microbial communities has remained difficult, particularly from clay environments. Lysis with concentrated guanidine followed by concentrated sodium phosphate extraction supported DNA and RNA recovery from high iron, low humus content clay. Alterating the extraction pH or using other ionic solutions (Na 2SO 4 and NH 4H 2PO 4) yielded no detectable nucleic acid. DNA recovered using a lysis solution with 500 mM phosphate buffer (PB) followed by a 1 M PB wash was 15.22±2.33 g DNA/g clay, with most DNA consisting of >20 Kb fragments, compared to 2.46±0.25more » g DNA/g clay with the Powerlyzer soil DNA system (MoBio). Increasing [PB] in the lysis reagent coincided with increasing DNA fragment length. Rarefaction plots based on16S rRNA (V1/V3 region) pyrosequencing libraries from A-horizon and clay soils showed an ~80% and ~400% larger accessed diversity compared to a previous grinding protocol or the Powerlyzer soil DNA system, respectively. The observed diversity from the Firmicutes showed the strongest increase with >3-fold more bacterial species recovered using this system. Additionally, some OTU's having more than 100 sequences in these libraries were absent in samples extracted using the PowerLyzer reagents or the previous lysis method.« less

Synthesis and innovation of PLA/clay nanocomposite characterization againts to mechanical and thermal properties

NASA Astrophysics Data System (ADS)

Salim, S.; Agusnar, H.; Wirjosentono, B.; Tamrin; Marpaung, H.; Rihayat, T.; Nurhanifa; Adriana

2018-03-01

Plastic polymer is one of the most dominant materials of daily human activities because of its multifunctional nature, light and strong and anti-corrosion so it is easy to apply in various equipment. Plastic is generally derived from petroleum material so it is nonbiodegradable. Therefore, this study aims to create a breakthrough of natural and biodegradable biodegradable plastic materials from plant starch (pisok kepok starch) with the help of 3 types of acid (HNO3, HCl and H2SO4) called Poly Lactid Acid (PLA). PLA is enhanced by mixing with a clay material with a variation of 1, 3 and 5% composition to form a PLA / Clay Nanocomposite material which is expected to have superior properties and resemble conventional plastics in general. Several types of characterization were performed to see the quality of the resulting material including tensile strength test with UTM tool, thermal endurance test with TGA tool, morphological structure test using SEM tool and additional test to see filler clay quality through X-RD tool. Based on the characterization of tensile and thermal test, 5B nanocomposite with addition of 5% clay and HCl acid aid showed the best tensile strength of 36 Mpa and the highest stability was 446,63 oC. Based on the results of morphological analysis of the best samples (5B) showed good interface ties. Meanwhile, based on the results of filler analysis, the opening of clay layer d-spacing occurred at 0.355 nm.

Effects of a thermal perturbation on mineralogy and pore water composition in a clay-rock: An experimental and modeling study

NASA Astrophysics Data System (ADS)

Gailhanou, H.; Lerouge, C.; Debure, M.; Gaboreau, S.; Gaucher, E. C.; Grangeon, S.; Grenèche, J.-M.; Kars, M.; Madé, B.; Marty, N. C. M.; Warmont, F.; Tournassat, C.

2017-01-01

The physical and chemical properties of clay-rocks are, at least partly, controlled by the chemical composition of their pore water. In evaluating the concept of disposing of radioactive waste in clay-rock formations, determining pore water composition is an important step in predicting how a clay-rock will behave over time and as a function of external forces, such as chemical and thermal perturbations. This study aimed to assess experimental and modeling methodology to calculate pore water composition in a clay-rock as a function of temperature (up to 80 °C). Hydrothermal alteration experiments were carried out on clay-rock samples. We conducted comprehensive chemical and mineralogical characterization of the material before and after reaction, and monitored how the chemical parameters in the liquid and gas phases changed. We compared the experimental results with the a priori predictions made by various models that differed in their hypotheses on the reactivity of the minerals present in the system. Thermodynamic equilibrium could not be assessed unequivocally in these experiments and most of the predicted mineralogy changes were too subtle to be tracked quantitatively. However, from observing the neo-formation of minerals such as goethite we were able to assess the prominent role of Fe-bearing phases in the outcome of the experiments, especially for the measured pH and pCO2 values. After calibrating the amount of reacting Fe-bearing phases with our data, we proposed a thermodynamic model that was capable of predicting the chemical evolution of the systems under investigation as well as the evolution of other systems already published in the literature, with the same clay-rock material but with significant differences in experimental conditions.

Contrasting frictional behaviour of fault gouges containing Mg-rich phyllosilicates

NASA Astrophysics Data System (ADS)

Sanchez Roa, C.; Faulkner, D.; Jimenez Millan, J.; Nieto, F.

2015-12-01

The clay mineralogy of fault gouges has important implications on frictional properties and stability of fault planes. We studied the specific case of the Galera fault zone where fault gouges containing Mg-rich phyllosilicates appear as hydrothermal deposits related to high salinity fluids enriched in Mg2+. These deposits are dominated by sepiolite and palygorskite, both fibrous clay minerals with similar composition to Mg-smectite. The frictional strengths of sepiolite and palygorskite have not yet been determined, however, as they are part of the clay mineral group, it has been assumed that their frictional behaviour would be in line with platy clay minerals. We performed frictional sliding experiments on powdered pure standards and fault rocks in order to establish the frictional behaviour of sepiolite and palygorskite using a triaxial deformation apparatus with a servo-controlled axial loading system and fluid pressure pump. Friction coefficients for palygorskite and sepiolite as monomineralic samples were found to be 0.65 to 0.7 for dry experiments, and 0.45 to 0.5 for water-saturated experiments. Although these fibrous minerals are part of the phyllosilicates group, they show higher friction coefficients and their mechanical behaviour is less stable than platy clay minerals. This difference is a consequence of their stronger structural framework and the discontinuity of water layers. Our results present a contrast in mechanical behaviour between Mg-rich fibrous and platy clay minerals in fault gouges, where smectite is known to considerably reduce friction coefficients and to increase the stability of the fault plane leading to creeping processes. Transformations between saponite and sepiolite have been previously observed and could modify the deformation regime of a fault zone. Constraining the stability conditions and possible mineral reactions or transformations in fault gouges could help us understand the general role of clay minerals in fault stability.

The effect of soil type on the bioremediation of petroleum contaminated soils.

PubMed

Haghollahi, Ali; Fazaelipoor, Mohammad Hassan; Schaffie, Mahin

2016-09-15

In this research the bioremediation of four different types of contaminated soils was monitored as a function of time and moisture content. The soils were categorized as sandy soil containing 100% sand (type I), clay soil containing more than 95% clay (type II), coarse grained soil containing 68% gravel and 32% sand (type III), and coarse grained with high clay content containing 40% gravel, 20% sand, and 40% clay (type IV). The initially clean soils were contaminated with gasoil to the concentration of 100 g/kg, and left on the floor for the evaporation of light hydrocarbons. A full factorial experimental design with soil type (four levels), and moisture content (10 and 20%) as the factors was employed. The soils were inoculated with petroleum degrading microorganisms. Soil samples were taken on days 90, 180, and 270, and the residual total petroleum hydrocarbon (TPH) was extracted using soxhlet apparatus. The moisture content of the soils was kept almost constant during the process by intermittent addition of water. The results showed that the efficiency of bioremediation was affected significantly by the soil type (Pvalue < 0.05). The removal percentage was the highest (70%) for the sandy soil with the initial TPH content of 69.62 g/kg, and the lowest for the clay soil (23.5%) with the initial TPH content of 69.70 g/kg. The effect of moisture content on bioremediation was not statistically significant for the investigated levels. The removal percentage in the clay soil was improved to 57% (within a month) in a separate experiment by more frequent mixing of the soil, indicating low availability of oxygen as a reason for low degradation of hydrocarbons in the clay soil. Copyright © 2016 Elsevier Ltd. All rights reserved.

Utility of Cytospin and Cell block Technology in Evaluation of Body Fluids and Urine Samples: A Comparative Study.

PubMed

Qamar, Irmeen; Rehman, Suhailur; Mehdi, Ghazala; Maheshwari, Veena; Ansari, Hena A; Chauhan, Sunanda

2018-01-01

Cytologic examination of body fluids commonly involves the use of direct or sediment smears, cytocentrifuge preparations, membrane filter preparations, or cell block sections. Cytospin and cell block techniques are extremely useful in improving cell yield of thin serous effusions and urine samples, and ensure high diagnostic efficacy. We studied cytospin preparations and cell block sections prepared from 180 samples of body fluids and urine samples to compare the relative efficiency of cell retrieval, preservation of cell morphology, ease of application of special stains, and diagnostic efficacy. Samples were collected and processed to prepare cytospin smears and cell block sections. We observed that overall, cell yield and preservation of individual cell morphology were better in cytospin preparations as compared to cell blocks, while preservation of architectural pattern was better in cell block sections. The number of suspicious cases also decreased on cell block sections, with increased detection of malignancy. It was difficult to prepare cell blocks from urine samples due to low cellularity. Cytospin technology is a quick, efficient, and cost-effective method of increasing cell yield in hypocellular samples, with better preservation of cell morphology. Cell blocks are better prepared from high cellularity fluids; however, tissue architecture is better studied, with improved rate of diagnosis and decrease in ambiguous results. Numerous sections can be prepared from a small amount of material. Special stains and immunochemical stains can be easily applied to cell blocks. It also provides a source of archival material.

Cytotoxicity and mutagenicity studies on migration extracts from nanocomposites with potential use in food packaging.

PubMed

Maisanaba, Sara; Pichardo, Silvia; Jordá-Beneyto, María; Aucejo, Susana; Cameán, Ana M; Jos, Ángeles

2014-04-01

Clays are used in the food packaging industry to obtain nanocomposites. The use of these new materials is a concern, because they could reach consumers by oral exposure through possible migration, and potential toxic effects could be derived. In the present study, several in vitro basal cytotoxicity and mutagenicity tests on migration extracts obtained from a nanocomposite material with poly (lactic) acid (PLA) and two modified clays, Clay1 and Clay2, are shown. Migration extracts in distilled water showed values of 0.1 ± 0.2mg/dm(2) in all samples. Also, the content of characteristic metals of the clays structure (Al, Ca, Mg, Fe, Si) was studied and no statistical differences were observed. For the cytotoxicity assays, the human intestinal Caco-2 and human liver HepG2 cells were selected. Cells were exposed to concentrations between 2.5% and 100% extracts determining three different biomarkers of cellular viability. No significant differences were observed in the cytotoxicity assays. Finally, mutagenicity was evaluated by the Ames test and resulted in the absence of mutagenic response at all the concentrations assayed. Taking in account all above mentioned, these new materials show a good profile for their use in food packaging although further research is still needed. Copyright © 2014 Elsevier Ltd. All rights reserved.

Study of Adsorption and Flocculation Properties of Natural Clays to Remove Prorocentrum lima

PubMed Central

Louzao, Maria Carmen; Abal, Paula; Fernández, Diego A.; Vieytes, Mercedes R.; Legido, José Luis; Gómez, Carmen P.; Pais, Jesus; Botana, Luis M.

2015-01-01

High accumulations of phytoplankton species that produce toxins are referred to as harmful algal blooms (HABs). HABs represent one of the most important sources of contamination in marine environments, as well as a serious threat to public health, fisheries, aquaculture-based industries, and tourism. Therefore, methods effectively controlling HABs with minimal impact on marine ecology are required. Marine dinoflagellates of the genera Dinophysis and Prorocentrum are representative producers of okadaic acid (OA) and dinophysistoxins responsible for the diarrhetic shellfish poisoning (DSP) which is a human intoxication caused by the consumption of shellfish that bioaccumulate those toxins. In this work we explore the use of natural clay for removing Prorocentrum lima. We evaluate the adsorption properties of clays in seawater containing the dinoflagellates. The experimental results confirmed the cell removal through the flocculation of algal and mineral particles leading to the formation of aggregates, which rapidly settle and further entrain cells during their descent. Moreover, the microscopy images of the samples enable one to observe the clays in aggregates of two or more cells where the mineral particles were bound to the outer membranes of the dinoflagellates. Therefore, this preliminary data offers promising results to use these clays for the mitigation of HABs. PMID:26426051

Mercury content of Illinois soils

USGS Publications Warehouse

Dreher, G.B.; Follmer, L.R.

2004-01-01

For a survey of Illinois soils, 101 cores had been collected and analyzed to determine the current and background elemental compositions of Illinois soils. Mercury and other elements were determined in six samples per core, including a surface sample from each core. The mean mercury content in the surface samples was 33 ?? 20 ??g/kg soil, and the background content was 20 ?? 9 ??g/kg. The most probable sources of mercury in these soils were the parent material, and wet and dry deposition of Hg0 and Hg2+ derived from coal-burning power plants, other industrial plants, and medical and municipal waste incinerators. Mercury-bearing sewage sludge or other fertilizers applied to agricultural fields could have been the local sources of mercury. Although the mercury content correlated with organic carbon content or clay content in individual cores, when all the data were considered, there was no strong correlation between mercury and either the organic carbon or the clay-size content.

First compositional evidences on the local production of Dressel 2-4 amphorae in Calabria (Southern Italy): characterization and mixing simulations

NASA Astrophysics Data System (ADS)

Miriello, D.; Bloise, A.; De Luca, R.; Apollaro, C.; Crisci, G. M.; Medaglia, S.; Taliano Grasso, A.

2015-06-01

Dressel 2-4 amphorae are a type of pottery, which was used to transport wine and produced in the Mediterranean area between the first century BC and the second century AD. This study shows, for the first time, that their production also occurred in Ionian Calabria. These results were achieved by studying 11 samples of archaeological pottery (five samples of Dressel 2-4 and six samples of other ceramic types) taken from Cariati (Calabria—Southern Italy). The composition of the pottery was compared with that of the local raw materials (clays and sands) potentially usable for their production. Samples were studied by polarized optical microscopy and analysed by XRF, XRPD and Raman spectroscopy. An innovative approach, based on Microsoft Excel optimizer "Solver" add-in on geochemical data, was used to define the provenance of archaeological pottery and to calculate the mixtures of local clay and sand needed for the production of the pottery itself.

Plasma cholinesterase inhibition in the clay-colored robin (Turdus grayi) exposed to diazinon in maradol papaya crops in Yucatan, Mexico

USGS Publications Warehouse

Cobos, V.M.; Mora, M.A.; Escalona, G.

2006-01-01

The use of organophosphorous pesticides in agriculture can result in intoxication of birds foraging in sprayed crops. Effects on birds resulting from pesticide intoxication are varied and include behavioral and reproductive effects, including death. One widely used insecticide in Maradol papaya crops is diazinon which has been associated with various incidents of intoxication and death of wild birds. The objective of this study was to evaluate the impact of diazinon application to papaya crops on plasma cholinesterase activity of the clay-colored robin (Turdus grayi). We captured clay-colored robins foraging in a papaya crop the following day after the field had been sprayed with diazinon at a dose of 1.5 kg/ha during March and May, respectively. We took a blood sample from the brachialis vein of the birds captured and measured plasma enzymatic activity. The plasma samples from birds used as controls were taken during the same time period and were analyzed in a similar way. Enzymatic activity of males was greater than that of females (53,52%) and mean cholinesterase inhibition was 49.43%. Cholinesterase inhibition was greater during May than in March probably due to more continuous exposure and ingestion of the insecticide through food and possible absorption through the skin. This degree of enzymatic inhibition is possibly affecting the behavior of the clay-colored robin and could result in death in severe cases.

Quantitative Relationship of Soil Texture with the Observed Population Density Reduction of Heterodera glycines after Annual Corn Rotation in Nebraska

PubMed Central

Pérez-Hernández, Oscar; Giesler, Loren J.

2014-01-01

Soil texture has been commonly associated with the population density of Heterodera glycines (soybean cyst nematode: SCN), but such an association has been mainly described in terms of textural classes. In this study, multivariate analysis and a generalized linear modeling approach were used to elucidate the quantitative relationship of soil texture with the observed SCN population density reduction after annual corn rotation in Nebraska. Forty-five commercial production fields were sampled in 2009, 2010, and 2011 and SCN population density (eggs/100 cm3 of soil) for each field was determined before (Pi) and after (Pf) annual corn rotation from ten 3 × 3-m sampling grids. Principal components analysis revealed that, compared with silt and clay, sand had a stronger association with SCN Pi and Pf. Cluster analysis using the average linkage method and confirmed through 1,000 bootstrap simulations identified two groups: one corresponding to predominant silt-and-clay fields and other to sand-predominant fields. This grouping suggested that SCN relative percent population decline was higher in the sandy than in the silt-and-clay predominant group. However, when groups were compared for their SCN population density reduction using Pf as the response, Pi as a covariate, and incorporating the year and field variability, a negative binomial generalized linear model indicated that the SCN population density reduction was not statistically different between the sand-predominant field group and the silt-and-clay predominant group. PMID:24987160

Mineralogy and Geochemistry of the Main Glauconite Bed in the Middle Eocene of Texas: Paleoenvironmental Implications for the Verdine Facies

PubMed Central

Harding, Sherie C.; Nash, Barbara P.; Petersen, Erich U.; Ekdale, A. A.; Bradbury, Christopher D.; Dyar, M. Darby

2014-01-01

The Main Glauconite Bed (MGB) is a pelleted greensand located at Stone City Bluff on the south bank of the Brazos River in Burleson County, Texas. It was deposited during the Middle Eocene regional transgression on the Texas Gulf Coastal Plain. Stratigraphically it lies in the upper Stone City Member, Crockett Formation, Claiborne Group. Its mineralogy and geochemistry were examined in detail, and verdine facies minerals, predominantly odinite, were identified. Few glauconitic minerals were found in the green pelleted sediments of the MGB. Without detailed mineralogical work, glaucony facies minerals and verdine facies minerals are easily mistaken for one another. Their distinction has value in assessing paleoenvironments. In this study, several analytical techniques were employed to assess the mineralogy. X-ray diffraction of oriented and un-oriented clay samples indicated a clay mixture dominated by 7 and 14Å diffraction peaks. Unit cell calculations from XRD data for MGB pellets match the odinite-1M data base. Electron microprobe analyses (EMPA) from the average of 31 data points from clay pellets accompanied with Mössbauer analyses were used to calculate the structural formula which is that of odinite: Fe3+ 0.89 Mg0.45 Al0.67 Fe2+ 0.30 Ti0.01 Mn0.01) Σ = 2.33 (Si1.77 Al0.23) O5.00 (OH)4.00. QEMSCAN (Quantitative Evaluation of Minerals by Scanning Electron Microscopy) data provided mineral maps of quantitative proportions of the constituent clays. The verdine facies is a clay mineral facies associated with shallow marine shelf and lagoonal environments at tropical latitudes with iron influx from nearby runoff. Its depositional environment is well documented in modern nearshore locations. Recognition of verdine facies clays as the dominant constituent of the MGB clay pellets, rather than glaucony facies clays, allows for a more precise assessment of paleoenvironmental conditions. PMID:24503875

Abiogenic photochemical synthesis on surface of meteorites and other small space bodies

NASA Astrophysics Data System (ADS)

Simakov, Michael B.; Kuzicheva, Eugenia A.

The abiogenic photochemical synthesis of complex biochemical compounds on the surface of small bodies in our Solar system was examined. Hydrated minerals are found within a chondrite matrix of meteorites together with significant amounts of organic matter. Clays are likely to have formed when water was present on parent meteoritic bodies. In order to verify the existence of a relationship between abiogenic synthesis of nucleotides and inorganic components of the meteorites, we have investigated possible abiogenic reactions associated with different clay (montmorillonite, kaolinite) and a basaltic one (Tyatya's volcanic ash) under action of open space energy sources as a model of different exobiological environments on the surface of small space bodies. The abiogenic synthesis of natural adenine nucleotides from a mixture of adenosine and inorganic phosphate has been observed following irradiation with VUV light in the presence of different mineral samples. The yields of the products (5'AMP, 2'AMP, 3'AMP, 2'3'cAMP and 3'5'cAMP) depended on irradiation time and kinds of minerals used. The discovery that meteoritic organic compounds may be trapped and protected within a clay mineral matrix has implications for our understanding of prebiotic molecular evolution in the early Solar system. Clay minerals may also have concentrated organic compounds thereby promoting polymerization reactions. An adsorption/binding of nucleic acids components by clay crystals could change the electron distribution and/or the conformation of the molecules. The remnant water molecules in the clay sheets also could influence the course of the reaction. Clay immobilization of phosphate could play an important role in this reaction. Chondritic material could have been a common component of the inner Solar system shortly after its formation and the biologically useful products of clay mineral-organic matter interactions could have also widespread, and delivered to planetary surfaces through the accretion of carbonaceous asteroids.

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

NASA Astrophysics Data System (ADS)

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

2015-12-01

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

Effectiveness Study of Drinking Water Treatment Using Clays/Andisol Adsorbent in Lariat Heavy Metal Cadmium (Cd) and Bacterial Pathogens

NASA Astrophysics Data System (ADS)

Pranoto; Inayati; Firmansyah, Fathoni

2018-04-01

Water is a natural resource that is essential for all living creatures. In addition, water also caused of disease affecting humans. The existence of one of heavy metal pollutants cadmium (Cd) in the body of water is an environmental problem having a negative impact on the quality of water resources. Adsorption is one of the ways or methods that are often used for the treatment of wastewater. Clay and allophanic soil were used as Cd adsorbent by batch method. Ceramic filter was used to reduce Cd concentration in the ground water. This study aims to determine the effect of the composition of clay and Allophane, activation temperature and contact time on the adsorption capacity of Cd in the model solution. The optimum adsorption condition and the effectiveness of drinking water treatment in accordance with Regulation of the Minister of Health using clay/Andisol adsorbents in ensnare heavy metals Cd and bacterial pathogens. Identification and characterization of adsorbent is done by using NaF, Infrared Spectroscopy (FTIR), X-ray diffraction (XRD), specific surface area and total acidity specific. The Cd metal concentrations were analysed by atomic absorption spectroscopy. Adsorption isotherms determined by Freundlich and Langmuir equations. Modified water purification technology using ceramic filters are made with a mixture of clay and Andisol composition. The results showed samples of clay and Andisol containing minerals. The optimum condition of adsorption was achieved at 200 °C of activation temperature, 60 minutes of contact time and the 60:40 of clay:Andisol adsorbent composition. Freundlich isotherm represented Cd adsorption on the clay/Andisol adsorbent with a coefficient of determination (R2=0.99) and constant (k=1.59), higher than Langmuir (R2=0.89). The measurement results show the water purification technology using ceramic filters effectively reduce E. coli bacterial and Cd content in the water.

Smectite Dehydration, Membrane Filtration, and Pore-Water Freshening in Deep Ultra-Low Permeability Formations: Deep Processes in the Nankai Accretionary Wedge

NASA Astrophysics Data System (ADS)

Brown, K. M.; Sample, J. C.; Even, E.; Poeppe, D.; Henry, P.; Tobin, H. J.; Saffer, D. M.; Hirose, T.; Toczko, S.; Maeda, L.

2014-12-01

We address the fundamental questions surrounding the nature of water and chemical transport processes deep within sedimentary basin and accretionary-wedge environments. Consolidation and permeability studies conducted to 165 MPa (~10km depth) indicate that ultra-tight clay formations (10-18 m2 to10-21 m2) can substantially modify the fluids migrating through then. Pore-water extractions conducted on smectite/illite rich core samples obtained from 1-3 km depths at IODP (NanTroSEIZE, Chikyu) deep-riser drilling Site C0002, at the elevated loads required to squeeze waters from such deeply buried sediment (stresses up to 100 MPa),resulted in anomalous patterns of sequential freshening with progressive loading. More accurate laboratory investigations (both incremental loading and Constant Rate of Strain test) revealed that such freshening initiates above 20 MPa and progresses with consolidation to become greater than 20% by effective normal load of 165 MPa. Log-log plots of stress vs. hydraulic conductivity reveal that trends remain linear to elevated stresses and total porosities as low at 14%. The implications are that stress induced smectite dehydration and/or membrane filtration effects cause remarkable changes in pore water chemistry with fluid migration through deep, tight, clay-rich formations. These changes should occur in addition to any thermally induced diagenetic and clay-dehydration effects on pore water chemistry. Work is progressing to evaluate the impact of clay composition and temperature to ascertain if purely illitic compositions show similar trends and if the mass fractionation of water and other isotopes also occurs. Such studies will ascertain if the presence of smectite is a prerequisite for freshening or if membrane filtration is a major process in earth systems containing common clay minerals. The results have major implications for interpretations of mass chemical balances, pore water profiles, and the hydrologic, geochemical, and stress state controls on deep system behavior in all deep accretionary wedge and basin environments where clays are abundant. This research used samples provided by the International Ocean Discovery Program (IODP).

Long-term variations of clay mineral composition in the Andaman Sea (IODP Exp. 353 Site U1447): preliminary result

NASA Astrophysics Data System (ADS)

Lee, J.; Khim, B. K.; Cho, H. G.; Kim, S.; 353 Scientists, I. E.

2016-12-01

Clay mineral studies in the Bengal Fan have allowed the reconstruction of the erosional history of the Himalayan-Tibetan complex since the Early Miocene. Several factors such as climate change and tectonic activity are important for the erosion rate of the Himalaya-Tibet complex. IODP Expedition 353 Site U1447 (10°47.4'N, 93°00'E; 1391 mbsl) was drilled on a ridge 45 km offshore Little Andaman Island in the Andaman Sea, penetrating to total depths of 738 m. Riverine sediments supplied mainly by the Irrawaddy and Salween (draining the Indo-Burman Ranges; smectite-rich) and the Ganga/Brahmaputra (draining the Himalaya; illite-rich) via the surface currents have been known to deposit in the Andaman Sea. We measured clay minerals of 38 sediment samples collected from 150 to 737 m CSF-A at Site U1447 in order to reveal long-term variation patterns of clay minerals and their controlling factors. Age reconstruction of Site U1447 aided by shipboard biostratigraphic and paleomagnetic data defined the study interval spanning from the Late Miocene ( 10 Ma) to Early Pleistocene ( 1.25 Ma). At this interval, clay minerals consist mainly of smectite (28-61% with an average of 47%) followed by illite (20-41% with an average of 29%), kaolinite (9-19% with an average of 14%), and chlorite (5-15% with an average of 10%). Variation of clay mineral compositions is divided into three stages; almost consistent variations of all clay minerals (from 750 to 570 m CSF-A; 10.0 to 7.5 Ma), gradual decrease of smectite and increase of illite and chlorite (from 570 to 400 m CSF-A; 7.5 to 4.5 Ma), and great fluctuation of all clay minerals (from 400 to 150 m CSF-A; 4.5 to 1.1 Ma). Such long-term clay mineral changes may be related to provenance switches, tectonic evolution of the source regions, climatic variations, degree of volcanism with basin evolution, sedimentation history by sea level changes or some combination of these factors.

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

NASA Astrophysics Data System (ADS)

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

2015-11-01

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

Dynamics of landslide model with time delay and periodic parameter perturbations

NASA Astrophysics Data System (ADS)

Kostić, Srđan; Vasović, Nebojša; Franović, Igor; Jevremović, Dragutin; Mitrinovic, David; Todorović, Kristina

2014-09-01

In present paper, we analyze the dynamics of a single-block model on an inclined slope with Dieterich-Ruina friction law under the variation of two new introduced parameters: time delay Td and initial shear stress μ. It is assumed that this phenomenological model qualitatively simulates the motion along the infinite creeping slope. The introduction of time delay is proposed to mimic the memory effect of the sliding surface and it is generally considered as a function of history of sliding. On the other hand, periodic perturbation of initial shear stress emulates external triggering effect of long-distant earthquakes or some non-natural vibration source. The effects of variation of a single observed parameter, Td or μ, as well as their co-action, are estimated for three different sliding regimes: β < 1, β = 1 and β > 1, where β stands for the ratio of long-term to short-term stress changes. The results of standard local bifurcation analysis indicate the onset of complex dynamics for very low values of time delay. On the other side, numerical approach confirms an additional complexity that was not observed by local analysis, due to the possible effect of global bifurcations. The most complex dynamics is detected for β < 1, with a complete Ruelle-Takens-Newhouse route to chaos under the variation of Td, or the co-action of both parameters Td and μ. These results correspond well with the previous experimental observations on clay and siltstone with low clay fraction. In the same regime, the perturbation of only a single parameter, μ, renders the oscillatory motion of the block. Within the velocity-independent regime, β = 1, the inclusion and variation of Td generates a transition to equilibrium state, whereas the small oscillations of μ induce oscillatory motion with decreasing amplitude. The co-action of both parameters, in the same regime, causes the decrease of block's velocity. As for β > 1, highly-frequent, limit-amplitude oscillations of initial stress give rise to oscillatory motion. Also for β > 1, in case of perturbing only the initial shear stress, with smaller amplitude, velocity of the block changes exponentially fast. If the time delay is introduced, besides the stress perturbation, within the same regime, the co-action of Td (Td < 0.1) and small oscillations of μ induce the onset of deterministic chaos.

View of Expedition 15 FE Anderson performing the ANITA Experiment in the Node 1

NASA Image and Video Library

2007-10-06

ISS015-E-32200 (6 Oct. 2007) --- Astronaut Clay Anderson, Expedition 15 flight engineer, uses an air sample pump and 2.5 liter gas sample bag to gather and analyze air samples for the Analyzing Interferometer for Ambient Air (ANITA) experiment in the Unity node of the International Space Station.

Escherichia coli challenge and one type of smectite alter intestinal barrier of pigs

PubMed Central

2013-01-01

An experiment was conducted to determine how an E. coli challenge and dietary clays affect the intestinal barrier of pigs. Two groups of 32 pigs (initial BW: 6.9 ± 1.0 kg) were distributed in a 2 × 4 factorial arrangement of a randomized complete block design (2 challenge treatments: sham or E. coli, and 4 dietary treatments: control, 0.3% smectite A, 0.3% smectite B and 0.3% zeolite), with 8 replicates total. Diarrhea score, growth performance, goblet cell size and number, bacterial translocation from intestinal lumen to lymph nodes, intestinal morphology, and relative amounts of sulfo and sialo mucins were measured. The E. coli challenge reduced performance, increased goblet cell size and number in the ileum, increased bacterial translocation from the intestinal lumen to the lymph nodes, and increased ileal crypt depth. One of the clays (smectite A) tended to increase goblet cell size in ileum, which may indicate enhanced protection. In conclusion, E. coli infection degrades intestinal barrier integrity but smectite A may enhance it. PMID:24359581

Escherichia coli challenge and one type of smectite alter intestinal barrier of pigs.

PubMed

Almeida, Juliana Abranches Soares; Liu, Yanhong; Song, Minho; Lee, Jeong Jae; Gaskins, H Rex; Maddox, Carol Wolfgang; Osuna, Orlando; Pettigrew, James Eugene

2013-12-20

An experiment was conducted to determine how an E. coli challenge and dietary clays affect the intestinal barrier of pigs. Two groups of 32 pigs (initial BW: 6.9 ± 1.0 kg) were distributed in a 2 × 4 factorial arrangement of a randomized complete block design (2 challenge treatments: sham or E. coli, and 4 dietary treatments: control, 0.3% smectite A, 0.3% smectite B and 0.3% zeolite), with 8 replicates total. Diarrhea score, growth performance, goblet cell size and number, bacterial translocation from intestinal lumen to lymph nodes, intestinal morphology, and relative amounts of sulfo and sialo mucins were measured. The E. coli challenge reduced performance, increased goblet cell size and number in the ileum, increased bacterial translocation from the intestinal lumen to the lymph nodes, and increased ileal crypt depth. One of the clays (smectite A) tended to increase goblet cell size in ileum, which may indicate enhanced protection. In conclusion, E. coli infection degrades intestinal barrier integrity but smectite A may enhance it.

Characterization and Beneficiation Studies of a Low Grade Bauxite Ore

NASA Astrophysics Data System (ADS)

Rao, D. S.; Das, B.

2014-10-01

A low grade bauxite sample of central India was thoroughly characterized with the help of stereomicroscope, reflected light microscope and electron microscope using QEMSCAN. A few hand picked samples were collected from different places of the mine and were subjected to geochemical characterization studies. The geochemical studies indicated that most of the samples contain high silica and low alumina, except a few which are high grade. Mineralogically the samples consist of bauxite (gibbsite and boehmite), ferruginous mineral phases (goethite and hematite), clay and silicate (quartz), and titanium bearing minerals like rutile and ilmenite. Majority of the gibbsite, boehmite and gibbsitic oolites contain clay, quartz and iron and titanium mineral phases within the sample as inclusions. The sample on an average contains 39.1 % Al2O3 and 12.3 % SiO2, and 20.08 % of Fe2O3. Beneficiation techniques like size classification, sorting, scrubbing, hydrocyclone and magnetic separation were employed to reduce the silica content suitable for Bayer process. The studies indicated that, 50 % by weight with 41 % Al2O3 containing less than 5 % SiO2 could be achieved. The finer sized sample after physical beneficiation still contains high silica due to complex mineralogical associations.

Admixing dredged marine clay with cement-bentonite for reduction of compressibility

NASA Astrophysics Data System (ADS)

Rahilman, Nur Nazihah Nur; Chan, Chee-Ming

2017-11-01

Cement-based solidification/stabilization is a method that is widely used for the treatment of dredged marine clay. The key objective for solidification/stabilization is to improve the engineering properties of the originally soft, weak material. Dredged materials are normally low in shear strength and bearing capacity while high incompressibility. In order to improve the material's properties for possible reuse, a study on the one-dimensional compressibility of lightly solidified dredged marine clay admixed with bentonite was conducted. On the other hand, due to the viscous nature, particularly the swelling property, bentonite is a popular volumising agent for backfills. In the present study, standard oedometer test was carried out to examine the compressibility of the treated sample. Complementary strength measurements were also conducted with laboratory vane shear setup on both the untreated and treated dredged marine clay. The results showed that at the same binder content, the addition of bentonite contributed significantly to the reduction of compressibility and rise in undrained shear strength. These improved properties made the otherwise discarded dredged marine soils potentially reusable for reclamation works, for instance.

Role of DDL processes during electrolytic reduction of Cu(II) in a low oxygen environment.

PubMed

Brosky, Rebekah T; Pamukcu, Sibel

2013-11-15

Heavy metals typically accumulate in reduced bottom sediments after being discharged into waterways by industrial and municipal processes. A laboratory experiment was conducted in order to determine if abundance of clay in the bottom sediments of a Cu-contaminated aqueous ecosystem could enhance electrolytic reduction of the heavy metal. Cu(NO3)2 · 2.5H2O was added to simulate a moderately contaminated system with 650 μg Cu/ml kaolinite clay-water slurry. A constant electrical potential of 1.0 V/cm was applied across platinum wire electrodes inserted into the continuously stirred system for four days while the system ORP(2) was monitored and periodic sub-samples were taken for analysis. The electrical as well as the chemical results indicate that the quantity of Cu(II) being reduced to Cu(I), especially within the aqueous phase, is increased within the first 48 h of experimentation by the presence of kaolinite clay up to 0.05 mg clay/l slurry. Copyright © 2013 Elsevier B.V. All rights reserved.

Smectite clays in Mars soil - Evidence for their presence and role in Viking biology experimental results

NASA Technical Reports Server (NTRS)

Banin, A.; Rishpon, J.

1979-01-01

Evidence for the presence of smectite clays in Martian soils is reviewed and results of experiments with certain active clays simulating the Viking biology experiments are reported. Analyses of Martian soil composition by means of X-ray fluorescence spectrometry and dust storm spectroscopy and Martian geological history strongly suggest the presence of a mixture of weathered ferro-silicate minerals, mainly nontronite and montmorillonite, accompanied by soluble sulphate salts, as major constituents. Samples of montmorillonite and nontronite incubated with (C-14)-formate or the radioactive nutrient medium solution used in the Viking Labeled Release experiment, were found to produce patterns of release of radioactive gas very similar to those observed in the Viking experiments, indicating the iron-catalyzed decomposition of formate as the reaction responsible for the Viking results. The experimental results of Hubbard (1979) simulating the results of the Viking Pyrolytic Release experiment using iron montmorillonites are pointed out, and it is concluded that many of the results of the Viking biology experiments can be explained in terms of the surface activity of smectite clays in catalysis and adsorption.

Adsorption of Radioactive Cesium to Illite-Sericite Mixed Clays

NASA Astrophysics Data System (ADS)

Hwang, J. H.; Choung, S.; Park, C. S.; Jeon, S.; Han, J. H.; Han, W. S.

2016-12-01

Once radioactive cesium is released into aquatic environments through nuclear accidents such as Chernobyl and Fukushima, it is harmful to human and ecological system for a long time (t1/2 = 30.2 years) because of its chemical toxicity and γ-radiation. Sorption mechanism is mainly applied to remove the cesium from aquatic environments. Illite is one of effective sorbent, considering economical cost for remediation. Although natural illite is typically produced as a mixture with sericite formed by phyllic alteration in hydrothermal ore deposits, the effects of illite-sericite mixed clays on cesium sorption was rarely studied. This study evaluated the sorption properties of cesium to natural illite collected at Yeongdong in Korea as the world-largest illite producing areas (termed "Yeongdong illite"). The illite samples were analyzed by XRF, XRD, FT-IR and SEM-EDX to determine mineralogy, chemical composition, and morphological characteristics, and used for batch sorption experiments. Most of "Yeongdong illite" samples predominantly consist of sericite, quartz, albite, plagioclase feldspar and with minor illite. Cesium sorption distribution coefficients (Kd,Cs) of various "Yeongdong illite" samples ranged from 500 to 4000 L/kg at low aqueous concentration (Cw 10-7 M). Considering Kd,Cs values were 400 and 6000 using reference sericite and illite materials, respectively, in this study, these results suggested that high contents of sericite significantly affect the decrease of sorption capabilities for radiocesium by natural illite (i.e., illite-sericite mixed clay).

Utility of Cytospin and Cell block Technology in Evaluation of Body Fluids and Urine Samples: A Comparative Study

PubMed Central

Qamar, Irmeen; Rehman, Suhailur; Mehdi, Ghazala; Maheshwari, Veena; Ansari, Hena A.; Chauhan, Sunanda

2018-01-01

Background: Cytologic examination of body fluids commonly involves the use of direct or sediment smears, cytocentrifuge preparations, membrane filter preparations, or cell block sections. Cytospin and cell block techniques are extremely useful in improving cell yield of thin serous effusions and urine samples, and ensure high diagnostic efficacy. Materials and Methods: We studied cytospin preparations and cell block sections prepared from 180 samples of body fluids and urine samples to compare the relative efficiency of cell retrieval, preservation of cell morphology, ease of application of special stains, and diagnostic efficacy. Samples were collected and processed to prepare cytospin smears and cell block sections. Results: We observed that overall, cell yield and preservation of individual cell morphology were better in cytospin preparations as compared to cell blocks, while preservation of architectural pattern was better in cell block sections. The number of suspicious cases also decreased on cell block sections, with increased detection of malignancy. It was difficult to prepare cell blocks from urine samples due to low cellularity. Conclusions: Cytospin technology is a quick, efficient, and cost-effective method of increasing cell yield in hypocellular samples, with better preservation of cell morphology. Cell blocks are better prepared from high cellularity fluids; however, tissue architecture is better studied, with improved rate of diagnosis and decrease in ambiguous results. Numerous sections can be prepared from a small amount of material. Special stains and immunochemical stains can be easily applied to cell blocks. It also provides a source of archival material. PMID:29643653

Synthesis, characterization and electrospinning of corn cob cellulose-graft-polyacrylonitrile and their clay nanocomposites.

PubMed

Kalaoğlu, Özlem I; Ünlü, Cüneyt H; Galioğlu Atıcı, Oya

2016-08-20

This study aims at evaluation of cellulose recovered from agricultural waste (corn cob) in terms of synthesis of graft copolymers, polymer/clay nanocomposites, and nanofibers. The copolymers and nanocomposites were synthesized in aqueous solution using Ce(4+) initiator. Conditions (concentrations of the components, reaction temperature, and period) were determined first for copolymer synthesis to obtain the highest conversion ratio. Then found parameters were used to synthesize nanocomposites adding clay mineral to reaction medium. Although there was a decrease in conversion in nanocomposites syntheses, thermal and rheologic measurements indicated enhancements compared to pristine copolymer. Obtained polymeric materials have been successfully electrospun into nanofibers and characterized. Average diameter of the nanofibers was about 650nm and was strongly influenced by NaMMT amount in the nanocomposite sample. Copyright © 2016 Elsevier Ltd. All rights reserved.

Clays of Ladon Basin

NASA Image and Video Library

2018-01-23

Ladon Basin was a large impact structure that was filled in by the deposits from Ladon Valles, a major ancient river on Mars as seen in this image from NASA's Mars Reconnaissance Orbiter (MRO). These wet sediments were altered into minerals such as various clay minerals. Clays imply chemistry that may have been favorable for life on ancient Mars, if anything lived there, so this could be a good spot for future exploration by rovers and perhaps return of samples to Earth. The map is projected here at a scale of 50 centimeters (19.7 inches) per pixel. [The original image scale is 52.1 centimeters (20.5 inches) per pixel (with 2 x 2 binning); objects on the order of 156 centimeters (61.4 inches) across are resolved.] North is up. https://photojournal.jpl.nasa.gov/catalog/PIA22183

Turbulent Coagulation of Particles Smaller Than the Length Scales of Turbulence and Equilibrium Sorption of Phenanthrene to Clay: Implications for Pollutant Transport in the Estuarine Water Column

DTIC Science & Technology

1997-05-01

estuaries was modeled using phenanthrene, bacterial extracellular polymer and kaolinite clay as surrogates for a hydrophobic organic pollutant...coefficients obtained for phenanthrene sorption to kaolinite and bentonite in the presence of varying amounts of DOM represented by alginic acid and tannic...acid. 333 Table B.3: Literature values for sorption between phenanthrene, humic acid and kaolinite for [DOM]a = 10 mg/L 334 Table E.1: Sample output data

Effect of wet grinding on structural properties of ball clay

DOE Office of Scientific and Technical Information (OSTI.GOV)

Purohit, A., E-mail: anuradha.purohit34@gmail.com; Chander, S.; Dhaka, M. S.

2015-05-15

In this paper, the effect of wet grinding on structural properties of ball clay is undertaken. The wet grinding treatment was performed employing ball and vibro mills for different time spells of 2, 4, 8 and 16 hours. The structural properties were carried out using X-ray diffraction (XRD). The structure of ground samples is found to be simple cubic. The crystallographic parameters are calculated and slight change in lattice constant, inter planner spacing and particle size is observed with grinding treatment. The results are in agreement with the available literature.

Particle size distribution of typical ceramic raw materials by laser granulometry

NASA Technical Reports Server (NTRS)

Wojnarovitsne, I. H.; Lenkel, M.

1984-01-01

The principles of the method are explained and the working of the CILAS 715 laser granulometer is described. The particle size distributions of milled glazes, quartz, feldspar and china clay were determined by this instrument and by Andreasen sedimentation. The agreement was good for isometric particles, but the china clay appears finer by sedimentation, because the platelets arrange themselves horizontally during sedimentation, while in the laser granulometer preferred orientation is prevented by circulation between the sample holder and the vibrated and stirred reservoir of the slip.

Major and Trace Element Variations in Impact Crater Clay from Chicxulub, Lonar, and Mistastin, Implications for the Martian Soil

NASA Technical Reports Server (NTRS)

Newsom, H. E.; Nelson, M. J.; Shearer, C. K.; Rietmeijer, F. J. M.; Gakin, R.; Lee, K.

2004-01-01

The catastrophic Chicxulub event should have generated a large hydrothermal system with volatile element mobilization, producing interesting alteration materials and clays. The Yaxcopoil-1 (YAX) drill hole is located in the annular trough, about 70 km southwest of the crater center, in an area where the impactite layers are relatively thin (approx. 100 m thick). We have analyzed samples from the YAX drill core and from other impact craters including Mistastin and Lonar to determine the nature of alteration and trace element mobilization.

Cesium-137 Fallout in Indiana Soil

NASA Astrophysics Data System (ADS)

Whitman, Richard T.

Atomic weapons testing during the Cold War and accidents at nuclear power plants have resulted in the release of radioactive fallout over great distances. Little is known about levels of fallout deposited in Indiana. The reported study sampled soil in all 92 Indiana counties to determine the present level of cesium-137 from the 2 to 12 centimeter depth from previous nuclear tests and other nuclear releases. A total of 67 samples were collected from forested areas and 25 from grasslands, both undisturbed since 1940, along with four controls from crawl spaces. Greater Cs-137 retention occurred in the forested areas at approximately a 2:1 ratio. Other parameters investigated included soil clay content, rate of rainfall, and soil pH. Each variable was examined for possible statistical correlation with Cs-137 retention. Both clay content and combined clay content/rainfall were significantly (p < 0.05) correlated with soil Cs-137 levels. The four controls showed very low values of Cs-137 indicating the movement of sub-micron sized fallout into areas considered safe from fallout. The Cs-137 data from this study will serve as a reliable baseline of Cs-137 levels in the event of a future release of fallout.

Spatial Dependence of Physical Attributes and Mechanical Properties of Ultisol in a Sugarcane Field.

PubMed

Tavares, Uilka Elisa; Rolim, Mário Monteiro; de Oliveira, Veronildo Souza; Pedrosa, Elvira Maria Regis; Siqueira, Glécio Machado; Magalhães, Adriana Guedes

2015-01-01

This study investigates the effect of conventional tillage and application of the monoculture of sugar cane on soil health. Variables like density, moisture, texture, consistency limits, and preconsolidation stress were taken as indicators of soil quality. The measurements were made at a 120 × 120 m field cropped with sugar cane under conventional tillage. The objective of this work was to characterize the soil and to study the spatial dependence of the physical and mechanical attributes. Then, undisturbed soil samples were collected to measure bulk density, moisture content and preconsolidation stress and disturbed soil samples for classification of soil texture, and consistency limits. The soil texture indicated that soil can be characterized as sandy clay soil and a sandy clay loam soil, and the consistency limits indicated that the soil presents an inorganic low plasticity clay. The preconsolidation tests tillage in soil moisture content around 19% should be avoided or should be chosen a management of soil with lighter vehicles in this moisture content, to avoid risk of compaction. Using geostatistical techniques mapping was possible to identify areas of greatest conservation soil and greater disturbance of the ground.

Lake Chad sedimentation and environments during the late Miocene and Pliocene: New evidence from mineralogy and chemistry of the Bol core sediments

NASA Astrophysics Data System (ADS)

Moussa, Abderamane; Novello, Alice; Lebatard, Anne-Elisabeth; Decarreau, Alain; Fontaine, Claude; Barboni, Doris; Sylvestre, Florence; Bourlès, Didier L.; Paillès, Christine; Buchet, Guillaume; Duringer, Philippe; Ghienne, Jean-François; Maley, Jean; Mazur, Jean-Charles; Roquin, Claude; Schuster, Mathieu; Vignaud, Patrick; Brunet, Michel

2016-06-01

This study presents mineralogical and geochemical data from a borehole drilled near the locality of Bol (13°27‧N, 14°44‧E), in the eastern archipelago of the modern Lake Chad (Chad). Samples were taken from a ∼200 m long core section forming a unique sub-continuous record for Central Africa. Among these samples, 25 are dated between 6.4 and 2.4 Ma. Dominant minerals are clays (66% average) mixed with varying amounts of silt and diatomite. The clay fraction consists of Fe-beidellite (87% average), kaolinite, and traces of illite. Clay minerals originate from the erosion of the vertisols that surrounded the paleolake Chad. Sedimentological data indicate that a permanent lake (or recurrent lakes) existed from 6.7 until 2.4 Ma in the vicinity of Bol. By comparison with modern latitudinal distribution of vertisols in Africa the climate was Sudanian-like. Changes in the sedimentation rate suggest a succession of wetter and dryer periods during at least six million years in the region during the critical time period covering the Miocene-Pliocene transition.

Determination of essential and toxic elements in clay soil commonly consumed by pregnant women in Tanzania

NASA Astrophysics Data System (ADS)

Mwalongo, D.; Mohammed, N. K.

2013-10-01

A habit of eating clay soil especially among pregnant women is a common practice in Tanzania. This practice known as geophagy might introduce toxic elements in the consumer's body to endanger the health of the mother and her child. Therefore it is very important to have information on the elemental composition of the eaten soil so as to assess the safety nature of the habit. In this study 100 samples of clay soil, which were reported to be originating from five regions in Tanzania and are consumed by pregnant women were analyzed to determine their levels of essential and toxic elements. The analysis was carried out using energy dispersive X-ray fluorescent technique (EDXRF) of Tanzania Atomic Energy Commission, Arusha. Essential elements Fe, Zn, Cu, Se and Mn and toxic elements As, Pb, Co, Ni, U and Th were detected in concentrations above WHO permissible limits in some of the samples. The results from this study show that the habit of eating soil is exposing the pregnant mothers and their children to metal toxicity which is detrimental to their health. Hence, further actions should be taken to discourage the habit of eating soil at all levels.

Influence of Laser Radiation Power Density on the Intensity of Spectral Lines for Main Components in a Clay Laser-Induced Plasma

NASA Astrophysics Data System (ADS)

Anufrik, S. S.; Kurian, N. N.; Znosko, K. F.; Belkov, M. V.

2018-05-01

We have studied the intensity of the spectral lines for the main components in clay: Al I 309.4 nm, Al II 358.7 nm, Mg II 279.6 nm, Ti II 323.6 nm vs. the position of the object relative to the focus of the optical system when the samples are exposed to single laser pulses from a YAG:Nd3+ laser. We have determined the permissible ranges for positioning the object relative to the focus of the optical system (positive and negative defocusing) for which there is practically no change in the reproducibility of the intensity for the spectral lines for red and white clay samples. We show that the position of the object relative to the focus of the optical system should be within the range ΔZ ±1.5 mm for optimal laser pulse energies for the analyte spectral lines. We have calculated the radiation flux density for different laser pulse energies and different distances from the focus to the object. We have shown experimentally that reducing the radiation flux density leads to a decrease in the intensity of the analyte spectral lines.

Spatial Dependence of Physical Attributes and Mechanical Properties of Ultisol in a Sugarcane Field

PubMed Central

Tavares, Uilka Elisa; Monteiro Rolim, Mário; Souza de Oliveira, Veronildo; Maria Regis Pedrosa, Elvira; Siqueira, Glécio Machado; Guedes Magalhães, Adriana

2015-01-01

This study investigates the effect of conventional tillage and application of the monoculture of sugar cane on soil health. Variables like density, moisture, texture, consistency limits, and preconsolidation stress were taken as indicators of soil quality. The measurements were made at a 120 × 120 m field cropped with sugar cane under conventional tillage. The objective of this work was to characterize the soil and to study the spatial dependence of the physical and mechanical attributes. Then, undisturbed soil samples were collected to measure bulk density, moisture content and preconsolidation stress and disturbed soil samples for classification of soil texture, and consistency limits. The soil texture indicated that soil can be characterized as sandy clay soil and a sandy clay loam soil, and the consistency limits indicated that the soil presents an inorganic low plasticity clay. The preconsolidation tests tillage in soil moisture content around 19% should be avoided or should be chosen a management of soil with lighter vehicles in this moisture content, to avoid risk of compaction. Using geostatistical techniques mapping was possible to identify areas of greatest conservation soil and greater disturbance of the ground. PMID:26167528

Geochemical and technological characterization of clays of Corumbataí Formation, Paraná Basin, in the state of São Paulo, Brazil for the application in the ceramic industry.

NASA Astrophysics Data System (ADS)

Christofoletti, Sergio Ricardo; Torres Moreno, Maria Margarita; Batezelli, Alessandro; Zanardo, Antenor

2014-05-01

The Corumbataí Formation is a geological unit of the Paraná Basin comprises a range of predominantly argillaceous facies. These clays are important from an economic point of view, because they represent important mineral deposits suppliers of raw materials for the ceramic industry in the production of ceramic tiles.The study presents preliminary results of a research that aims to study the clays municipalities Tambaú, Ferreira and Santa Rosa of Viterbo in the State of São Paulo for their application and diversification of ceramic products. The methodology used was based on a detailed description of facies using the methodology in principles of analysis of Basin Miall (1984), followed by mineralogical identification by X-ray Diffraction, chemical analysis of major elements by X-ray Fluorescence and technological tests ceramic. According to the geological surveys of mines studied through columnar sections were identified the following lithofacies from base to top: Massive, Laminated, Intercalated and Altered. The mineralogy present on these lithofacies is composed by minerals: quartz, microclineo, albite, calcite, dolomite and hematite and by clay minerals illite, kaolinite and montmorillonite. The quartz represents the mineral more present in diffraction and occurs with d001 of 3.33Å in all lithofacies studied. The illite clay mineral represents the most frequent in studied samples presenting d 001 10Å in three conditions (natural, heated and treated with ethylene glycol) in which the blade was subjected to the analysis of X-ray diffraction, the presence of kaolinite or montmorillonite occurs or not in samples. It was observed a increased frequency of some minerals in the lithofacies studied, carbonates (calcite and dolomite), hematite and feldspar occurring in the intermediate portions of the profile with a predominance in lithofacies Intercalated. The illita clay mineral occurs throughout the profile, but with greater frequency in the lithofacies Massive and Laminated. The clay minerals kaolinite and montmorillonite occur in portions intermediate and top of the profiles studied in the intercalated and altered lithofacies. The chemical results of major elements by X-ray fluorescence confirmed the mineralogical results, with average values of 63.74 % of SiO2, 12.50 of Al2O3, 4.35% of of K2O, 0.45% of Na2O, 2,72% of CaO and 1,87 of MgO. The results chemical and mineralogical subsidized testing and ceramic formulations due to be executed later so defining the main applications of these clays in the production of ceramic products. The authors acknowledge the finantial support of Fundação de Amparo à Pesquisa do Estado de São Paulo-FAPESP, (Process, number 2012/24219-9).

Diffusion of U(VI) in Opalinus Clay: Influence of temperature and humic acid

NASA Astrophysics Data System (ADS)

Joseph, C.; Van Loon, L. R.; Jakob, A.; Steudtner, R.; Schmeide, K.; Sachs, S.; Bernhard, G.

2013-05-01

The diffusion of U(VI) (c0 = 1 × 10-6 mol/L) in compacted Opalinus Clay from the Mont Terri underground laboratory, Switzerland, was studied in the absence and presence of humic acid (10 mg/L) at two different temperatures (25 °C, 60 °C) under anaerobic conditions. As background electrolyte synthetic Opalinus Clay pore water (pH 7.6, I = 0.36 mol/L) was used. The diffusion-accessible porosity, ɛ, was determined for each Opalinus Clay bore core sample by through-diffusion experiments with tritiated water (HTO) before the U(VI) diffusion experiments were carried out. The values for the effective diffusion and distribution coefficients De and Kd obtained for U(VI) and humic acid at 25 °C as well as at 60 °C showed that humic acid has no significant influence on the U(VI) diffusion. The diffusion profiles of humic acid in Opalinus Clay at 25 and 60 °C indicate the contributions of two different humic acid particle size fractions (<1 kDa and 10-100 kDa). The small-sized humic acid fraction diffused through the whole Opalinus Clay samples at both temperatures within the 3 month duration of the U(VI) diffusion experiments. At 60 °C, diffusion profiles of two different U(VI) species were observed. In a separate experiment the U(VI) speciation in the source reservoir solution at 60 °C was analyzed by laser-induced fluorescence spectroscopy, photon correlation spectroscopy and scanning electron microscopy with an energy dispersive X-ray detector. The two diffusion profiles could be attributed to an unknown colloidal and a known aquatic U(VI) species (Ca2UO2(CO3)3(aq)). The diffusion results showed that the interaction of U(VI) and of the large-sized humic acid colloid fraction with the clay is stronger at 60 °C. An increase of Kd from 0.025 ± 0.003 m3/kg at 25 °C to 0.25 ± 0.05 m3/kg for U(VI)colloidal at 60 °C was determined. In addition, the value for De of U(VI) increased with increasing temperature. Using the De values at 25 and 60 °C, a preliminary activation energy for the diffusion of U(VI) through Opalinus Clay of 10 kJ/mol was calculated. The observed increased Kd and De values for U(VI)aqueous at 60 °C compensated each other to almost equal values of the apparent diffusion coefficient Da at 25 and 60 °C. Hence, an elevated temperature of 60 °C does not impact the migration of U(VI) through OPA significantly.

NovaSil clay intervention in Ghanaians at high risk for aflatoxicosis: II. Reduction in biomarkers of aflatoxin exposure in blood and urine.

PubMed

Wang, P; Afriyie-Gyawu, E; Tang, Y; Johnson, N M; Xu, L; Tang, L; Huebner, H J; Ankrah, N-A; Ofori-Adjei, D; Ellis, W; Jolly, P E; Williams, J H; Wang, J-S; Phillips, T D

2008-05-01

The efficacy of NovaSil clay (NS) to reduce aflatoxin (AF) biomarkers of exposure was evaluated in 656 blood samples and 624 urine samples collected from study participants during a 3-month phase IIa clinical intervention trial in Ghana. NS was delivered before meals via capsules. Serum AFB (1)-albumin adduct was measured by radioimmunoassay and urinary AFM (1) metabolites were quantified by immunoaffinity-high-performance liquid chromatography (HPLC)-fluorescence methods. Levels of AFB (1) -albumin adduct in serum samples collected at baseline and at 1 month were similar (p = 0.2354 and p = 0.3645, respectively) among the placebo (PL), low dose (LD, 1.5 g NS day (-1)), and high dose (HD, 3.0 g NS day (-1)) groups. However, the levels of AFB (1)-albumin adduct at 3 months were significantly decreased in both the LD group (p < 0.0001) and the HD group (p < 0.0001) compared with levels in the PL group. Levels of AFM(1) in urine samples collected at baseline and at 1 month were not statistically different among the three study groups. However, a significant decrease (up to 58%) in the median level of AFM (1) in samples collected at 3 months was found in the HD group when compared with the median level in the PL group (p < 0.0391). In addition, significant effects were found for dose, time, and dose-time interaction with serum AFB(1)-albumin adduct and dose-time interaction with urinary AFM (1) metabolites. The results suggest that capsules containing NS clay can be used to reduce effectively the bioavailability of dietary AF based on a reduction of AF-specific biomarkers.

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

NASA Technical Reports Server (NTRS)

Mahaffy, P. R.; Webster, C. R.; Stern, J. C.; Brunner, A. E.; Atreya, S. K.; Conrad, P. G.; Domagal-Goldman, S.; Eigenbrode, J. L.; Flesch, G. J.; Christensen, L. E.;

Mineralogical, crystallographic and morphological characteristics of natural kaolins from the Ivory Coast (West Africa)

NASA Astrophysics Data System (ADS)

Sei, J.; Morato, F.; Kra, G.; Staunton, S.; Quiquampoix, H.; Jumas, J. C.; Olivier-Fourcade, J.

2006-10-01

Thirteen clay samples from four deposits in the Ivory Coast (West Africa) were studied using X-ray diffraction, thermogravimetric analysis and chemical analysis. Mineralogical, crystallographic and morphological characteristics of these samples are given. Kaolinite is the principal mineral but other minerals are present in small quantities: illite, quartz, anatase and iron oxides (oxides and oxyhydroxides). The crystallographic, morphological and surface characteristics are influenced by the presence of these impurities. In particular, the presence of iron oxides was associated with reduced structural ordering and thermal stability of kaolinite and increased specific surface area. These clays could be used in the ceramics industry to make tiles and bricks, and also in agronomy as supports for chemical fertilizers or for environmental protection by immobilising potentially toxic waste products.

Lightweight aggregate production from claystone and shale in Bangladesh

USGS Publications Warehouse

Parker, Norbert A.; Khan, M.A.

1976-01-01

Muffle furnace tests were made on samples of clay, claystone, and shale collected in the Chittagong and Dacca areas of East Pakistan to determine their amenability to bloating for the commercial production of light-weight aggregate. Several areas, sampled in some detail, were selected for investigation because of their proximity to market, and accessibility to fuel and electricity. Muffle furnace tests show that the clay, claystone, and shale are natural bloaters at temperatures in the 1700? to 2200? F range, and do not require additives. The most desirable deposit, insofar as producing a strong aggregate is concerned, can be determined only by pilot-kiln testing and by crushing-strength tests made on concrete test cylinders. Reserves of suitable raw material are large in both the Chittagong and Dacca areas.

Lanthanide, yttrium, and zirconium anomalies in the Fire Clay coal bed, Eastern Kentucky

USGS Publications Warehouse

Hower, J.C.; Ruppert, L.F.; Eble, C.F.

1999-01-01

The Fire Clay coal bed in the Central Appalachian basin region contains a laterally-persistent tonstein that is found in the coal throughout most of its areal extent. The tonstein contains an array of minerals, including sanidine, ??-quartz, anatase and euhedral zircon, thhat constitutes strong evidence for a volcanic origin of the parting. For this study, five samples of the tonstein and four sets of coal samples underlying the tonstein were collected from five sites in eastern Kentucky. Inductively coupled plasma-mass spectroscopy (ICP-MS) analysis of the tonstein and underlying coal collected from four sites in eastern Kentucky show that although Zr concentrations are high in the tonstein (570-1820 ppm on a coal-ash basis (cab)), they are highest in the coal directly underlying the tonstein (2870-4540 ppm (cab)). A similar enrichment pattern is observed in the concentration of Y plus the sum of the rare earth elements (Y + ??REE): total Y + ??REE concentrations in the five tonstein samples range from 511 to 565 ppm (cab). However, Y + ??REE contents are highest in the coals directly underlying the tonsteins: values range from 1965 to 4198 ppm (cab). Scanning electron microscopy of samples from coal which directly underlies two of the tonstein samples show that REE-rich phosphate, tentatively identified as monazite, commonly infills cracks in clays and cells in clarain and vitrain. Zircon is rare and commonly subhedral. On the basis of coal chemistry and grain morphology, we suggest that volcanic components in the tonstein were leached by ground water. The leachate, rich in Y and REE precipitated as authigenic mineral phases in the underlying coal.The Fire Clay coal bed in the Central Appalachian basin region contains a laterally-persistent tonstein that is found in the coal throughout most of its areal extent. The tonstein contains an array of minerals, including sanidine, ??-quartz, anatase and euhedral zircon, that constitutes strong evidence for a volcanic origin of the parting. For this study, five samples of the tonstein and four sets of coal samples underlying the tonstein were collected from five sites in eastern Kentucky. Inductively coupled plasma-mass spectroscopy (ICP-MS) analysis of the tonstein and underlying coal collected from four sites in eastern Kentucky show that although Zr concentrations are high in the tonstein (570-1820 ppm on a coal-ash basis (cab)), they are highest in the coal directly underlying the tonstein (2870-4540 ppm (cab)). A similar enrichment pattern is observed in the concentration of Y plus the sum of the rare earth elements (Y+???REE): total Y+???REE concentrations in the five tonstein samples range from 511 to 565 ppm (cab). However, Y+???REE contents are highest in the coals directly underlying the tonsteins: values range from 1965 to 4198 ppm (cab). Scanning electron microscopy of samples from coal which directly underlies two of the tonstein samples show that REE-rich phosphate, tentatively identified as monazite, commonly infills cracks in clays and cells in clarain and vitrain. Zircon is rare and commonly subhedral. On the basis of coal chemistry and grain morphology, we suggest that volcanic components in the tonstein were leached by ground water. The leachate, rich in Y and REE precipitated as authigenic mineral phases in the underlying coal.

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

PubMed

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

2013-09-10

This work studied the influence of "maturation" conditions (time and agitation) on aggregation states, gel structure and rheological behaviour of a special kind of pharmaceutical semisolid products made of concentrated clay suspensions in mineral medicinal water. Maturation of the samples was carried out in distilled and sulphated mineral medicinal water, both in static conditions (without agitation) and with manual stirring once a week, during a maximum period of three months. At the measured pH interval (7.5-8.0), three-dimensional band-type networks resulting from face/face contacts were predominant in the laminar (disc-like) clay suspensions, whereas the fibrous (rod-like) particles formed micro-aggregates by van der Waals attractions. The high concentration of solids in the studied systems greatly determined their behaviour. Rod-like sepiolite particles tend to align the major axis in aggregates promoted by low shearing maturation, whereas aggregates of disc-like smectite particles did not have a preferential orientation and their complete swelling required long maturation time, being independent of stirring. Maturation of both kinds of suspensions resulted in improved rheological properties. Laminar clay suspensions became more structured with time, independently from static or dynamic maturation conditions, whereas for fibrous clay periodic agitation was also required. Rheological properties of the studied systems have been related to aggregation states and networking mechanisms, depending on the type of clay minerals constituents. Physical stability of the suspensions was not impaired by the specific composition of the Graena medicinal water. Copyright © 2013 Elsevier B.V. All rights reserved.

Selectivity sequences and sorption capacities of phosphatic clay and humus rich soil towards the heavy metals present in zinc mine tailing.

PubMed

Chaturvedi, Pranav Kumar; Seth, Chandra Shekhar; Misra, Virendra

2007-08-25

Sorption efficacy of phosphatic clay and humus rich soil alone and on combination were tested towards heavy metals present in zinc mine tailing (Zawar Zinc Mine), Udaipur (India). Characterization of the zinc mine tailing sample indicated the presence of Pb, Cu, Zn and Mn in the concentration of 637, 186, 720 and 577microg(-1), respectively. For sorption efficacy, the zinc mine tailing soil were properly amended with phosphatic clay and humus rich soil separately and in combination and leachability study was performed by batch experiment at different pH range from 3 to 9. The data showed that the percent leachability of heavy metal in non-amended soil was 75-90%. After amendment with phosphatic clay percent leachability of heavy metals became 35-45%. Further, the addition of humus soil to phosphatic clay decreased the percent leachability up to 5-15% at all tested pH. Column leachability experiment was performed to evaluate the rate of leachability. The shape of cumulative curves of Pb, Cu, Zn and Mn showed an increase in its concavity in following order: PbCu>Zn>Mn. Further, Langmuir isotherms applied for the sorption studies indicated that phosphatic clay in the presence of humus soil had high affinity for Pb followed by Cu, Zn and Mn, with sorption capacities (b) 139.94, 97.02, 83.32 and 67.58microgg(-1), respectively.

Effects of using arsenic-iron sludge wastes in brick making.

PubMed

Hassan, Khondoker Mahbub; Fukushi, Kensuke; Turikuzzaman, Kazi; Moniruzzaman, S M

2014-06-01

The arsenic-iron sludge generated in most of the treatment systems around the world is discharged into the nearest watercourse, which leads to accumulative rise of arsenic and iron concentrations in water. In this study, attempts were made to use the arsenic-iron sludge in making bricks and to analyze the corresponding effects on brick properties. The water treatment plant sludge is extremely close to brick clay in chemical composition. So, the sludge could be a potential substitute for brick clay. This study involved the addition of sludge with ratios 3%, 6%, 9% and 12% of the total weight of sludge-clay mixture. The physical and chemical properties of the produced bricks were then determined and evaluated and compared to control brick made entirely from clay. Results of different tests indicated that the sludge proportion and firing temperature were the two key factors in determining the quality of bricks. The compressive strength of 3%, 6%, 9% and 12% sludge containing brick samples were found to be 14.1 MPa, 15.1 MPa, 9.4 MPa and 7.1 MPa, respectively. These results indicate that the compressive strength of prepared bricks initially increased and then decreased with the increase of sludge proportion. Leaching characteristics of burnt bricks were determined with the variation of pH at a constant temperature. The optimum amount of sludge that could be mixed with clay to produce good bonding of clay-sludge bricks was found to be 6% (safely maximum) by weight. Copyright © 2013 Elsevier Ltd. All rights reserved.

Variations in the provenance of the late Neogene Red Clay deposits in northern China

NASA Astrophysics Data System (ADS)

Shang, Yuan; Beets, Christiaan J.; Tang, Hui; Prins, Maarten A.; Lahaye, Yann; van Elsas, Roel; Sukselainen, Leena; Kaakinen, Anu

2016-04-01

The voluminous loess-Red Clay deposits in northern China forming part of the Chinese Loess Plateau (CLP) are valuable terrestrial archives of climatic evolution for the late Cenozoic Era. Fundamental in reconstructing the late Miocene and Pliocene wind patterns and aridification history is a detailed knowledge of the provenance of these deposits. This paper provides end member modelling of bulk grain-size distributions and U-Pb dating of detrital zircons for three distant Red Clay sequences in the northeastern (Baode), southern (Lantian) and western (Dongwan) CLP. Data show that these different sections each display a distinctive compositional structure indicating variable depositional processes, but they also share two significant zircon age populations of 200-300 Ma and 400-500 Ma. While the Permian-Triassic (200-300 Ma) group accounts for a larger proportion of zircons' ages in the northeastern (NE) CLP, the Ordovician-Silurian (400-500 Ma) component is dominant in the southern and western CLP. It is suggested that the Red Clay in the southern and western CLP was mainly derived from the Northern Tibetan Plateau (NTP) and the Taklimakan desert by low-level westerly winds. Samples of the NE CLP show an increased signature of sediments transported by near-surface northwesterly winds from the broad area of the Central Asian Orogen Belt (CAOB). This spatial transport and deposition pattern is supported by the results from the backtrace trajectory modelling of the dominant dust transport pathways in the CLP. It is noted that the Red Clay sample of around 3.6 Ma obtained from the NE CLP shows increased detrital contributions from its west, possibly indicating an intensified westerly wind strength and/or aridity of the NTP and Taklimakan desert due to the uplift of the Tibetan Plateau and Tianshan Mountains in the Pliocene. The onset of enhanced drainage of the Yellow River caused by the increased denudation of the NETP since 3.6 Ma could also have contributed to this.

Evaluation of physico-mechanical properties of clayey soils using electrical resistivity imaging technique

NASA Astrophysics Data System (ADS)

Kibria, Golam

Resistivity imaging (RI) is a promising approach to obtaining continuous profile of soil subsurface. This method offers simple technique to identify moisture variation and heterogeneity of the investigated area. However, at present, only qualitative information of subsurface can be obtained using RI. A study on the quantification of geotechnical properties has become important for rigorous use of this method in the evaluation of geohazard potential and construction quality control of landfill liner system. Several studies have been performed to describe electrical resistivity of soil as a function of pore fluid conductivity and surface conductance. However, characterization tests on pore water and surface charge are not typically performed in a conventional geotechnical investigation. The overall objective of this study is to develop correlations between geotechnical parameters and electrical resistivity of soil, which would provide a mean to estimate geotechnical properties from RI. As a part of the study, multiple regression analyses were conducted to develop practically applicable models correlating resistivity with influential geotechnical parameters. The soil samples considered in this study were classified as highly plastic clay (CH) and low plasticity clay (CL) according to Unified Soil Classification System (USCS). Based on the physical tests, scanning electron microscope (SEM), and energy dispersive X-ray spectroscopy (EDS) analysis, kaolinite was identified as the dominant mineral with some traces of magnesium, calcium, potassium, and iron. Electrical resistivity tests were conducted on compacted clays and undisturbed samples under varied geotechnical conditions. The experimental results indicated that the degree of saturation substantially influenced electrical resistivity. Electrical resistivity decreased as much as 11 times from initial value for the increase of degree of saturation from 23 to 100% in the laboratory tests on compacted clays. In case of undisturbed soil samples, resistivity decreased as much as sixteen fold (49.4 to 3.2 Ohm-m) for an increase of saturation from 31 to 100%. Furthermore, the resistivity results were different for the specimens at a specific degree of saturation because of varied surface activity and isomorphous substitution of clayey soils. In addition to physical properties, compressibility of clays was correlated with electrical conductivity. Based on the investigation, it was determined that the electrical conductivity vs. pressure curves followed similar trends as e vs. logp curves. Multiple linear regression (MLR) models were developed for compacted and undisturbed samples using statistical analysis software SAS (2009). During model development, degree of saturation and CEC were selected as independent variables. The proposed models were validated using experimental results on a different set of samples. Moreover, the applicability of the models in the determination of degrees of saturation was evaluated using field RI tests.

Sorption of radioiodide in an acidic, nutrient-poor boreal bog: insights into the microbial impact.

PubMed

Lusa, M; Bomberg, M; Aromaa, H; Knuutinen, J; Lehto, J

2015-05-01

Batch sorption experiments were conducted to evaluate the sorption behaviour of iodide and the microbial impact on iodide sorption in the surface moss, subsurface peat, gyttja, and clay layers of a nutrient-poor boreal bog. The batch distribution coefficient (Kd) values of iodide decreased as a function of sampling depth. The highest Kd values, 4800 L/Kg dry weight (DW) (geometric mean), were observed in the fresh surface moss and the lowest in the bottom clay (geometric mean 90 mL/g DW). In the surface moss, peat and gyttja layers, which have a high organic matter content (on average 97%), maximum sorption was observed at a pH between ∼ 4 and 5 and in the clay layer at pH 2. The Kd values were significantly lower in sterilized samples, being 20-fold lower than the values found for the unsterilized samples. In addition, the recolonization of sterilized samples with a microbial population from the fresh samples restored the sorption capacity of surface moss, peat and gyttja samples, indicating that the decrease in the sorption was due to the destruction of microbes and supporting the hypothesis that microbes are necessary for the incorporation of iodide into the organic matter. Anoxic conditions reduced the sorption of iodide in fresh, untreated samples, similarly to the effect of sterilization, which supports the hypothesis that iodide is oxidized into I2/HIO before incorporation into the organic matter. Furthermore, the Kd values positively correlated with peroxidase activity in surface moss, subsurface peat and gyttja layers at +20 °C, and with the bacterial cell counts obtained from plate count agar at +4 °C. Our results demonstrate the importance of viable microbes for the sorption of iodide in the bog environment, having a high organic matter content and a low pH. Copyright © 2015 Elsevier Ltd. All rights reserved.

Clay at Nili Fossae

NASA Technical Reports Server (NTRS)

2006-01-01

This image of the Nili Fossae region of Mars was compiled from separate images taken by the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) and the High-Resolution Imaging Science Experiment (HiRISE), two instruments on NASA's Mars Reconnaissance Orbiter. The images were taken at 0730 UTC (2:30 a.m. EDT) on Oct. 4, 2006, near 20.4 degrees north latitude, 78.5 degrees east longitude. CRISM's image was taken in 544 colors covering 0.36 to 3.92 micrometers, and shows features as small as 18 meters (60 feet) across. HiRISE's image was taken in three colors, but its much higher resolution shows features as small as 30 centimeters (1 foot) across.

CRISM's sister instrument on the Mars Express spacecraft, OMEGA, discovered that some of the most ancient regions of Mars are rich in clay minerals, formed when water altered the planet's volcanic rocks. From the OMEGA data it was unclear whether the clays formed at the surface during Mars' earliest history of if they formed at depth and were later exposed by impact craters or erosion of the overlying rocks. Clays are an indicator of wet, benign environments possibly suitable for biological processes, making Nili Fossae and comparable regions important targets for both CRISM and HiRISE.

In this visualization of the combined data from the two instruments, the CRISM data were used to calculate the strengths of spectral absorption bands due to minerals present in the scene. The two major minerals detected by the instrument are olivine, a mineral characteristic of primitive igneous rocks, and clay. Areas rich in olivine are shown in red, and minerals rich in clay are shown in green. The derived colors were then overlayed on the HiRISE image.

The area where the CRISM and HiRISE data overlap is shown at the upper left, and is about 5 kilometers (3 miles) across. The three boxes outlined in blue are enlarged to show how the different minerals in the scene match up with different landforms. In the image 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.

Recurrence of water bodies in the hyperarid core of the Atacama Desert - New insights into the Late Pleistocene paleoclimate history of Northern Chile

NASA Astrophysics Data System (ADS)

Diederich, J. L.; Wennrich, V.; Fernández Galego, E.; Ritter, B.; Brill, D.; Niemann, K.; Rolf, C.; Melles, M.

2017-12-01

The Atacama Desert of northern Chile is regarded as the driest desert on Earth. Although still controversially discussed, overall arid to hyperarid conditions in the Atacama are thought to have persisted at least since the early Miocene, but were frequently punctuated by pluvial phases. The knowledge of past changes in humidity is strongly hampered by the fact that sediment records from the central Atacama Desert, which enable longer-scale precipitation reconstructions, are rare and mostly restricted to the Miocene/Pliocene or the late Pleistocene <50 kyrs. In this study, we focus on a sediment record from the hyperarid core of the Atacama Desert, derived from a tectonically blocked clay pan in the Coastal Cordillera (20°04'33.64"S, 69°55'01.75"W). This clay pan `Huara' has been initially investigated by a geophysical survey in spring 2015, followed by drilling of a short core (HU-III) covering the uppermost 4 m of sediment. Initial results of the ground penetrating radar (GPR) and horizontal to vertical (H/V) spectral ratio measurements indicate well-stratified sediment bodies in the basin with a maximum sediment infill of 30 ± 4 m. The chronology of core HU-III was established by a combination of optically stimulated luminescence (OSL) and paleomagnetic dating. The sedimentological and geochemical data of core HU-III as well as it's sediment geophysical properties indicate the primary accumulation of fine-grained sediments over the past ca. 50 kyrs, interpreted to be deposited under arid conditions with only sporadic precipitation. Intercalated coarser horizons indicate several periods of semiarid climate conditions, causing multiple phases of local alluvial deposition from the interior catchment area into the clay pan. The results are in agreement with a cosmogenic nuclide study from an adjacent meander system, indicating that the whole sediment sequence of the Huara clay pan covers the regional climate history of the past 500 - 700 kyrs.

Past seismic slip-to-the-trench recorded in Central America megathrust

NASA Astrophysics Data System (ADS)

Vannucchi, Paola; Spagnuolo, Elena; Aretusini, Stefano; Di Toro, Giulio; Ujiie, Kohtaro; Tsutsumi, Akito; Nielsen, Stefan

2017-12-01

The 2011 Tōhoku-Oki earthquake revealed that co-seismic displacement along the plate boundary megathrust can propagate to the trench. Co-seismic slip to the trench amplifies hazards at subduction zones, so its historical occurrence should also be investigated globally. Here we combine structural and experimental analyses of core samples taken offshore from southeastern Costa Rica as part of the Integrated Ocean Drilling Program (IODP) Expedition 344, with three-dimensional seismic reflection images of the subduction zone. We document a geologic record of past co-seismic slip to the trench. The core passed through a less than 1.9-million-year-old megathrust frontal ramp that superimposes older Miocene biogenic oozes onto late Miocene-Pleistocene silty clays. This, together with our stratigraphic analyses and geophysical images, constrains the position of the basal decollement to lie within the biogenic oozes. Our friction experiments show that, when wet, silty clays and biogenic oozes are both slip-weakening at sub-seismic and seismic slip velocities. Oozes are stronger than silty clays at slip velocities of less than or equal to 0.01 m s-1, and wet oozes become as weak as silty clays only at a slip velocity of 1 m s-1. We therefore suggest that the geological structures found offshore from Costa Rica were deformed during seismic slip-to-the-trench events. During slower aseismic creep, deformation would have preferentially localized within the silty clays.

Study on the Particle Size Distribution Nano-Particles of Mining Minerals on Whiteness of Triaxial Body

NASA Astrophysics Data System (ADS)

Mathur, Ravi; Soni, Aditi

White wares produced worldwide represent the foundation of much of the ceramic industry; Porcelain bodies fabricated from triaxial mixtures of clay, quartz and feldspar with different size and amounts of nano particles were investigated. Although the purity of raw materials has a strong effect on the colour of the fired bodies, the particle size of raw materials also effect the whiteness The raw material mining minerals china Clay, Feldspar, quarts were prepared of various sized nano particles contains 10.60 -20.22%, 56.84- 70.80 % and 34.87-50.76 % of 100nm respectively. The fired bodies of raw mining minerals and triaxial bodies were subjected to colour measurement. The differences in whiteness were compared and discussed. The studies so far carried out is upto 400 mesh size while the present study has included up to 100nm particle size. A statistical correlation between whiteness of feldspar and triaxial body was also carried out. The correlation between china clay and triaxial body are 0.53, 0.57 and 0.66 for china clay similarly correlation for feldspar is 0.49, 0.73 and 0.83 for triaxial body it are 0.97, 0.84 and 0.75 for A1, A2 and A3 samples. Correlation between china clay and feldspar with triaxial body are 0.79 and 0.92 respectively.

[Effects of Long-term Implementation of the Flow-Sediment Regulation Scheme on Grain and Clay Compositions of Inshore Sediments in the Yellow River Estuary].

PubMed

Wang, Miao-miao; Sun, Zhi-gao; Lu, Xiao-ning; Wang, Wei; Wang, Chuan-yuan

2015-04-01

Based on the laser particle size and X-ray diffraction (XRD) analysis, 28 sediment samples collected from the inshore region of the Yellow River estuary in October 2013 were determined to discuss the influence of long-term implementation of the flow-sediment regulation scheme (FSRS, initiated in 2002) on the distributions of grain size and clay components (smectite, illite, kaolinite and chlorite) in sediments. Results showed that, after the FSRS was implemented for more than 10 years, although the proportion of sand in inshore sediments of the Yellow River estuary was higher (average value, 23.5%) than those in sediments of the Bohai Sea and the Yellow River, silt was predominated (average value, 59.1%) and clay components were relatively low (average value, 17.4%). The clay components in sediments of the inshore region in the Yellow River estuary were close with those in the Yellow River. The situation was greatly changed due to the implementation of FSRS since 2002, and the clay components were in the order of illite > smectite > chlorite > kaolinite. This study also indicated that, compared to large-scale investigation in Bohai Sea, the local study on the inshore region of the Yellow River estuary was more favorable for revealing the effects of long-term implementation of the FSRS on sedimentation environment of the Yellow River estuary.

Pupal development of Ceratitis capitata (Diptera: Tephritidae) and Diachasmimorpha longicaudata (Hymenoptera: Braconidae) at different moisture values in four soil types.

PubMed

Bento, F de M M; Marques, R N; Costa, M L Z; Walder, J M M; Silva, A P; Parra, J R P

2010-08-01

This study aimed to evaluate adult emergence and duration of the pupal stage of the Mediterranean fruit fly, Ceratitis capitata (Wiedemann), and emergence of the fruit fly parasitoid, Diachasmimorpha longicaudata (Ashmead), under different moisture conditions in four soil types, using soil water matric potential. Pupal stage duration in C. capitata was influenced differently for males and females. In females, only soil type affected pupal stage duration, which was longer in a clay soil. In males, pupal stage duration was individually influenced by moisture and soil type, with a reduction in pupal stage duration in a heavy clay soil and in a sandy clay, with longer duration in the clay soil. As matric potential decreased, duration of the pupal stage of C. capitata males increased, regardless of soil type. C. capitata emergence was affected by moisture, regardless of soil type, and was higher in drier soils. The emergence of D. longicaudata adults was individually influenced by soil type and moisture factors, and the number of emerged D. longicaudata adults was three times higher in sandy loam and lower in a heavy clay soil. Always, the number of emerged adults was higher at higher moisture conditions. C. capitata and D. longicaudata pupal development was affected by moisture and soil type, which may facilitate pest sampling and allow release areas for the parasitoid to be defined under field conditions.

Soil variation and sampling intensity under red pine and aspen in Minnesota.

Treesearch

David H. Alban

1974-01-01

In red pine or aspen stands only two soil samples were needed to estimate (+/- 10%, 95% confidence) pH, bulk density, or sand, but 25 to 60 samples were required to estimate N, P, K, Ca, Mg, available water, or silt + clay. To estimate most forest floor properties required 30 to 50 samples in red pine stands, but only about half as many in aspen stands.

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

PubMed

Kennedy, Martin J; Wagner, Thomas

2011-06-14

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

Estimation of soil clay and organic matter using two quantitative methods (PLSR and MARS) based on reflectance spectroscopy

NASA Astrophysics Data System (ADS)

Nawar, Said; Buddenbaum, Henning; Hill, Joachim

2014-05-01

A rapid and inexpensive soil analytical technique is needed for soil quality assessment and accurate mapping. This study investigated a method for improved estimation of soil clay (SC) and organic matter (OM) using reflectance spectroscopy. Seventy soil samples were collected from Sinai peninsula in Egypt to estimate the soil clay and organic matter relative to the soil spectra. Soil samples were scanned with an Analytical Spectral Devices (ASD) spectrometer (350-2500 nm). Three spectral formats were used in the calibration models derived from the spectra and the soil properties: (1) original reflectance spectra (OR), (2) first-derivative spectra smoothened using the Savitzky-Golay technique (FD-SG) and (3) continuum-removed reflectance (CR). Partial least-squares regression (PLSR) models using the CR of the 400-2500 nm spectral region resulted in R2 = 0.76 and 0.57, and RPD = 2.1 and 1.5 for estimating SC and OM, respectively, indicating better performance than that obtained using OR and SG. The multivariate adaptive regression splines (MARS) calibration model with the CR spectra resulted in an improved performance (R2 = 0.89 and 0.83, RPD = 3.1 and 2.4) for estimating SC and OM, respectively. The results show that the MARS models have a great potential for estimating SC and OM compared with PLSR models. The results obtained in this study have potential value in the field of soil spectroscopy because they can be applied directly to the mapping of soil properties using remote sensing imagery in arid environment conditions. Key Words: soil clay, organic matter, PLSR, MARS, reflectance spectroscopy.

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

PubMed

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

2010-03-01

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

75 FR 16424 - Proposed Information Collection; Comment Request; Census Coverage Measurement Final Housing Unit...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-04-01

... unit is a block cluster, which consists of one or more geographically contiguous census blocks. As in... a number of distinct processes, ranging from forming block clusters, selecting the block clusters... sample of block clusters, while the E Sample is the census of housing units and enumerations in the same...

Diffusion, sorption, and retardation processes of anions in bentonite and organo-bentonites for multibarrier systems

NASA Astrophysics Data System (ADS)

Schampera, Birgit; Dultz, Stefan

2013-04-01

The low permeability, high cation exchange capacity (CEC) and plasticity of bentonites favor their use in multibarrier systems of waste deposits [1]. Bentonites have a high CEC but their ability to sorb anions is very low. There is, however, need for retardation of anions and organic pollutants in many applications. Bentonites, modified with certain organic cations, have the capacity to sorb anions and non-polar organic compounds in addition to cations. Investigations on organically modified clays address a wide variety of applications including immobilization of pollutants in contaminated soils, waste water treatment and in situ placement for the protection of ground water [2]. Many experiments on anion and cation sorption of organo-clays were conducted in the batch mode which does not reflect solid-liquid ratios and material densities in barrier systems. Diffusion experiments on compacted clays allow the evaluation of transport processes and sorption of pollutants at conditions relevant for repositories. For organo-clays only few diffusion studies are published e.g. [3] measured the diffusion of tritium and [4] the diffusion of H2O in bentonite and organo-bentonites. The organic cation hexadecylpyridinium (HDPy) was added to Wyoming bentonite (MX-80) in amounts corresponding to 2-400 % of the CEC. The uptake of organic cations was determined by the C-content, XRD and IR-spectroscopy. Wettability was analyzed by the contact angle. Physical, chemical and mineralogical properties of clays were characterized. Diffusion experiments were carried out in situ in a cell attached to the ATR-unit of a FTIR-spectrometer. For H2O-diffusion the compacted organo-clays are saturated first with D2O, afterwards H2O is supplied to the surface at the top of the clay platelet. Anion-diffusion was conducted with NO3--solution instead of H2O only having characteristic IR band positions at 1350 cm-1. Three different concentrations (0.25M, 0.5M and 1M) were used. Additional batch experiments with NO3- will support the understanding of sorption behavior of the anions. All hydrophilic samples have a higher retardation capacity, indicated by diffusion coefficients of 2.44 x 10-11 m/s2 for original bentonite and ˜2.1 x 10-11m/s2 for hydrophilic organo-clays. For hydrophobic organo-clays the H2O diffusion can be higher and is increased at high bulk density (1-1.5 g/m3) up to 2.76 x 10-10m2/s. Experiments with NO3- at bulk density of 1.5 g/m3 reveal that the apparent diffusion coefficients of nitrate are with results up to 5.61 x 1012 m2/s distinctively lower than free diffusion of nitrate in pure water (6.46 x 1010 m2/s at experimental conditions) and nitrate diffusion in natural bentonite (2.63 x 1011 m2/s). The measurements allow the interpretation of the different sorption mechanisms, retardation capacity and diffusion behavior of the analyzed clays at different anion concentrations. Ongoing molecular dynamic simulations will contribute understanding of diffusion processes in organo-clays including the conditions at the interface of the clay minerals and in solution. References: [1] Shackelford, C.D., Moore S.M. (2013) Fickian diffusion of radionuclides for engineered containment barriers: Diffusion coefficients, porosities, and complicating issues. Engineering Geology, 152, 133-147. [2] Rytwo, G., Nir, S., Shuali, U. (2012) Clay and water treatment. Applied Clay Science, 67-68, 117-118. [3] Lorenzetti, R.L., Bartelt-Hunt, S.L., Burns, S.E., Smith, J.A. (2005) Hydraulic conductivities and effective diffusion coefficients of geosynthetic clay liners with organobentonite amendments. Geotextiles and Geomembranes, 23, 385-400. [4] Schampera, B., Dultz, S. (2011) H2O self-diffusion in compacted clays as influenced by surface charge and wettability - obstruction effects of bound H2O layers. Clay and Clay Minerals,59, 42-57.