WorldWideScience

Sample records for clay soils

  1. Gardening in Clay Soils

    OpenAIRE

    Wagner, Katie; Kuhns, Michael; Cardon, Grant

    2015-01-01

    This fact sheet covers the basics of clay, silt and sand soils with an emphasis on gardening in soils with a high clay content. It includes information on the composition of clay soils, gardening tips for managing clay soils, and the types of plants that grow best in clay soils.

  2. Clay dispersibility and soil friability – testing the soil clay-to-carbon saturation concept

    OpenAIRE

    Schjønning, P.; de Jonge, L. W.; Munkholm, L.J.; P. Moldrup; B. T. Christensen; Olesen, J.E.

    2011-01-01

    Soil organic carbon (OC) influences clay dispersibility, which affects soil tilth conditions and the risk of vertical migration of clay colloids. No universal lower threshold of OC has been identified for satisfactory stabilization of soil structure. We tested the concept of clay saturation with OC as a predictor of clay dispersibility and soil friability. Soil was sampled three years in a field varying in clay content (~100 to ~220 g kg-1 soil) and grown with different crop rotations. Clay ...

  3. Clay Dispersibility and Soil Friability - Testing the Soil Clay-to-Carbon Saturation Concept

    DEFF Research Database (Denmark)

    Schjønning, Per; de Jonge, Lis Wollesen; Munkholm, Lars Juhl;

    2012-01-01

    either air-dried or rewetted to −100 hPa matric potential. Tensile strength of 1- to 2-, 2- to 4-, 4- to 8-, and 8- to 16-mm air-dried aggregates was calculated from their compressive strength, and soil friability estimated from the strength–volume relation. Crop rotation characteristics gave only minor......Soil organic carbon (OC) influences clay dispersibility, which affects soil tilth conditions and the risk of vertical migration of clay colloids. No universal lower threshold of OC has been identified for satisfactory stabilization of soil structure. We tested the concept of clay saturation with OC...... as a predictor of clay dispersibility and soil friability. Soil was sampled 3 yr in a field varying in clay content (∼100 to ∼220 g kg−1 soil) and grown with different crop rotations. Clay dispersibility was measured after end-over-end shaking of field-moist soil and 1- to 2-mm sized aggregates...

  4. The aeration of clay soils in cricket

    OpenAIRE

    Parsons, Simon A.

    2012-01-01

    In the game of cricket good ball-surface interactions are essential and require a hard, flat surface. To achieve this the clay loam soil comprising the pitch is compressed and compacted using a smooth wheeled roller, which when combined with the drying action of the grass plant roots, causing the clay minerals within the soil to shrink, creates a high bulk density, hard surface on which to play. High bulk density soils present difficult growing conditions for plants due to h...

  5. Radionuclides sorption in clay soils

    International Nuclear Information System (INIS)

    The sorption behaviour of clay soils is examined through a parametric study of the distribution coefficient (Kd) for the radionuclides of interest, Cs and Sr. This work is a preliminary stage of the migration studies of these nuclides in a porous medium (ground of Ezeiza, Argentina) and the evaluation of radiologic impact of the removal of low and intermediate activity wastes in shallow trenches. The determination of Kd is performed by a static technique or batch. The phases are separated by centrifugation at 20000 g during 1 hour. The activity of supernatant solution of Cs-137 and Sr-85 is measured in a detecting system of I Na(Tl) well-type. Two types of parameters were changed: a) those related to the determination method: phase separation (centrifugation vs. centrifugation plus filtration); equilibrium period, ratio solid/liquid; b) those related to the geochemical system: pH of contact solution, carrier concentration, competitive ions, ionic strength, desorption. It was observed that the modification of parameters in the Kd-measurement does not change the order of magnitude of results. (Author)

  6. Phosphorus speciation in Swedish agricultural clay soils

    OpenAIRE

    Eriksson, Ann Kristin

    2016-01-01

    Phosphorus (P) is an important element for crop production, but build-up of excess soil P can promote P leaching and eutrophication of surface waters. To better understand the dynamics of P release from soil to waters, more knowledge is needed about sorption patterns and P speciation in agricultural soils. Two new indices were developed to assess the importance of P sorption to hydroxy-interlayered clay minerals, and to evaluate the amount of hydroxy-interlayering and hydroxy-interlayer ...

  7. Quick clay and landslides of clayey soils.

    Science.gov (United States)

    Khaldoun, Asmae; Moller, Peder; Fall, Abdoulaye; Wegdam, Gerard; De Leeuw, Bert; Méheust, Yves; Otto Fossum, Jon; Bonn, Daniel

    2009-10-30

    We study the rheology of quick clay, an unstable soil responsible for many landslides. We show that above a critical stress the material starts flowing abruptly with a very large viscosity decrease caused by the flow. This leads to avalanche behavior that accounts for the instability of quick clay soils. Reproducing landslides on a small scale in the laboratory shows that an additional factor that determines the violence of the slides is the inhomogeneity of the flow. We propose a simple yield stress model capable of reproducing the laboratory landslide data, allowing us to relate landslides to the measured rheology. PMID:19905837

  8. Soil Microbes and soil microbial proteins: interactions with clay minerals

    International Nuclear Information System (INIS)

    Bacterial enumeration in soil environments estimates that the population may reach approximately 1010 g-1 of soil and comprise up to 90% of the total soil microbial biomass. Bacteria are present in soils as single cells or multicell colonies and often strongly adsorb onto mineral surfaces such as sand and clay. The interactions of microbes and microbial biomolecules with these minerals have profound impacts on the physical, chemical and biological properties of soils. (Author)

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

    Science.gov (United States)

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

    2014-01-15

    Enteropathogens released into the environment can represent a serious risk to public health. Soil clay content has long been known to have an important effect on enteropathogen survival in soil, generally enhancing survival. However, clay mineral composition in soils varies, and different clay minerals have specific physiochemical properties that would be expected to impact differentially on survival. This work investigated the effect of clay materials, with a predominance of a particular mineral type (montmorillonite, kaolinite, or illite), on the survival in soil microcosms over 96 days of Listeria monocytogenes, Salmonella Dublin, and Escherichia coli O157. Clay mineral addition was found to alter a number of physicochemical parameters in soil, including cation exchange capacity and surface area, and this was specific to the mineral type. Clay mineral addition enhanced enteropathogen survival in soil. The type of clay mineral was found to differentially affect enteropathogen survival and the effect was enteropathogen-specific. PMID:24035982

  10. Estimation of soil clay content from hygroscopic water content measurements

    OpenAIRE

    Wuddivira, Mark N.; Robinson, David A.; Lebron, Inma; Brechet, Laëtitia; Atwell, Melissa; De Caires, Sunshine; Oatham, Michael; Jones, Scott B.; Abdu, Hiruy; Verma, Aditya K.; Tuller, Markus

    2012-01-01

    Soil texture and the soil water characteristic are key properties used to estimate flow and transport parameters. Determination of clay content is therefore critical for understanding of plot-scale soil heterogeneity. With increasing interest in proximal soil sensing, there is the need to relate obtained signals to soil properties of interest. Inference of soil texture, especially clay mineral content, from instrument response from electromagnetic induction and radiometric methods is of subst...

  11. Structural classification of clay soils and its application in classifying Tehran City clays

    International Nuclear Information System (INIS)

    The behaviour of all reconstituted and natural clays is determined by their fabric and bonding. A new classification of clays is proposed in this paper on the basis of standard penetration test (Spt), the geological history and the one-dimensional compression of the clay in the 1v-σv plane. Although the eighth clay types defined in the classification have different origins, fabric and bonding, they all have either a syn-sedimentation or a post-sedimentation structure. The definition of these clay types is taken as a starting point for the construction of a general framework of behaviour of clays. In this research results of laboratory and field investigations of a very stiff Tehran silty clay in the natural and reconstituted states including Spt, Odometer, Scanning Electron Microscopy and polarizing microscopy are presented. The structure of the Tehran silty clay is strongly influenced by bonding, calcium carbonate content and weathering intensity. This soil is a very stiff to hard clay which geologically is over-consolidated. Consolidation curve of soils lies close to the Icl line. Hence the Tehran silty clay is a type 4 clay but, at certain depths where the yield stress ratio is greater than 1, the Tehran silty clay becomes a type 7 clay

  12. Clay Mineralogy of Various Marginal Soils in Vietnam

    OpenAIRE

    Nguyen, Quang Hai; Egashira, Kazuhiko

    2008-01-01

    Various marginal soils derived from different parent materials were collected from different landforms and agro-ecological regions in Vietnam and were subjected to clay mineral analysis in addition to particle-size analysis. The result showed that the particle-size distribution of the soils had a close relationship with the landform. The clay content was highest for the soils from the meander floodplain and inland valley, followed by the soil from the hill and lowest for the soils from the ...

  13. STABILISATION OF SILTY CLAY SOIL USING CHLORIDE

    Directory of Open Access Journals (Sweden)

    TAMADHER T. ABOOD

    2007-04-01

    Full Text Available The object of this paper is to investigate the effect of adding different chloride compounds including (NaCl, MgCl2, CaCl2 on the engineering properties of silty clay soil. Various amounts of salts (2%, 4%, and 8% were added to the soil to study the effect of salts on the compaction characteristics, consistency limits and compressive strength. The main findings of this study were that the increase in the percentage of each of the chloride compounds increased the maximum dry density and decrease the optimum moisture content. The liquid limit, plastic limit and plasticity index decreased with the increase in salt content. The unconfinedcompressive strength increased as the salt content increased.

  14. Differences in physical properties of two clay soils

    OpenAIRE

    Alakukku, Laura; Ristolainen, Antti; nuutinen, Visa

    2008-01-01

    We studied the physical properties of two clay soils (J1 and J2) having relatively similar texture but differing cultivation properties J2 being more sensitive to dry and wet conditions. The general assumption that the productivity of heavy clay soils is mainly threatened by excessive wetness holds in both fields.

  15. Wave liquefaction in soils with clay content

    DEFF Research Database (Denmark)

    Kirca, Özgür; Sumer, B. Mutlu; Fredsøe, Jørgen

    2012-01-01

    The paper presents the results of an experimental study of the influence of clay content (in silt-clay and sand-clay mixtures) on liquefaction beneath progressive waves. The experiments showed that the influence of clay content is very significant. Susceptibility of silt to liquefaction is increa...

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

    Science.gov (United States)

    Colman, Steven M.

    1982-01-01

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

  17. Main Clay Minerals in Soils of Fujian Province,China

    Institute of Scientific and Technical Information of China (English)

    WANGGUO; ZHANGWEIMING; 等

    1996-01-01

    The clay minerals of more than 200 soil samples collected from various sites of Fujian Province were studied by the X-ray diffraction method and transmission electron microscopy to study their distribution and evolution.Montmorillonite was found in coastal solonchak,paddy soils derived from marine deposit,lacustrine deposit and river deposit,and some lateritic red soil,red soil and yellow soil with a low weathering degree.Chlorite existed mainly in coastal solonchak and paddy soil developed from marine deposit.1.4nm intergradient mineral appeared frequently in yellow soil,red soil and lateritic red soil.The content of 1.4nm intergradient mineral increased with the decrease of weathering degree from lateritic red soil to red soil to yellow soil.Hydrous micas were more in coastal solonchak,paddy soils derived from marine deposit,lacustrine deposit and river deposit.and puple soil from purple shale than in other soils.Kaolinte was the most important clay mineral in the soils iun this province.The higher the soil weathering degree,the more the kaolinite existed.From yellow soil to red soil to lateritic red soil,kaolinite increased gradually,Kaolinite was the predominant clay mineral accompanied by few other minerals in typical lateritic red soil. Tubular halloysite was a widespread clay mineral in soils of Fujian Province with varying quantities.The soil derived from the paent rocks rich in feldspar contained more tubular halloysite.Spheroidal halloysite was found in a red soil and a paddy soil developed from olivine basalt gibbsite in the soils in this district was largely“primary gibbsite” which formed in the early weathering stage.Gibbsite decreased with the increase of weathering degree from yellow soil to red soil to lateritic red soil.Goethite also decreased in the same sequence while hematite increased.

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

    Indian Academy of Sciences (India)

    Libo Hao; Qiaoqiao Wei; Yuyan Zhao; Zilong Lu; Xinyun Zhao

    2015-04-01

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

  19. Charge Properties and Clay Mineral Composition of Tianbao Mountains Soils

    Institute of Scientific and Technical Information of China (English)

    HEJI-ZHENG; LIXUE-YUAN; 等

    1992-01-01

    The clay mineral association,oxides of clay fraction and surface charge properties of 7 soils,which are developed from granite,located at different altitudesof the Tianbao Mountains were studied.Results indicate that with the increase in altitude,1) the weathering process and desilicification of soil clay minerals became weaker,whereas the leaching depotassication and the formation process of hydroxy-aluminum interlayer got stronger;2)the contents of amorphous and complex aluminum and iron,and the activity of aluminum and iron oxides for soil clay fraction increased;and 3) the amount of variable negarive charge,anion exchange capacity and the values of PZC and PZNC also increased.The activity of aluminum and iron oxides,the accumulation of aluminum,and surface charge characteristics and their relation to clay oxides of the vertical zone soils were observed and recorded.

  20. Mechanical dispersion of clay from soil into water: readily-dispersed and spontaneously-dispersed clay

    Science.gov (United States)

    Czyż, Ewa A.; Dexter, Anthony R.

    2015-01-01

    A method for the experimental determination of the amount of clay dispersed from soil into water is described. The method was evaluated using soil samples from agricultural fields in 18 locations in Poland. Soil particle size distributions, contents of organic matter and exchangeable cations were measured by standard methods. Sub-samples were placed in distilled water and were subjected to four different energy inputs obtained by different numbers of inversions (end-over-end movements). The amounts of clay that dispersed into suspension were measured by light scattering (turbidimetry). An empirical equation was developed that provided an approximate fit to the experimental data for turbidity as a function of number of inversions. It is suggested that extrapolation of the fitted equation to zero inversions enables the amount of spontaneously-dispersed clay to be estimated. This method introduces the possibility of replacing the existing subjective, qualitative method of determining spontaneously-dispersed clay with a quantitative, objective method. Even though the dispersed clay is measured under saturated conditions, soil samples retain a `memory' of the water contents at which they have been stored.

  1. Potential of Spectroradiometry to Classify Soil Clay Content

    Directory of Open Access Journals (Sweden)

    André Carnieletto Dotto

    2016-01-01

    Full Text Available ABSTRACT Diffuse reflectance spectroscopy (DRS is a fast and cheap alternative for soil clay, but needs further investigation to assess the scope of application. The purpose of the study was to develop a linear regression model to predict clay content from DRS data, to classify the soils into three textural classes, similar to those defined by a regulation of the Brazilian Ministry of Agriculture, Livestock and Food Supply. The DRS data of 412 soil samples, from the 0.0-0.5 m layer, from different locations in the state of Rio Grande do Sul, Brazil, were measured at wavelengths of 350 to 2,500 nm in the laboratory. The fitting of the linear regression model developed to predict soil clay content from the DRS data was based on a R2 value of 0.74 and 0.75, with a RMSE of 7.82 and 8.51 % for the calibration and validation sets, respectively. Soil texture classification had an overall accuracy of 79.0 % (calibration and 80.9 % (validation. The heterogeneity of soil samples affected the performance of the prediction models. Future studies should consider a previous classification of soil samples in different groups by soil type, parent material and/or sampling region.

  2. Effect of Ionic Soil Stabilizers on Soil-Water Characteristic of Special Clay

    Science.gov (United States)

    Cui, D.; Xiang, W.

    2011-12-01

    The engineering properties of special clay are conventionally improved through the use of chemical additive such as ionic soil stabilizer (ISS). Such special clays are often referred to as stabilized or treated clays. The soil-water characteristic curves (SWCC) of special clays from Henan province and Hubei province were measured both in natural and stabilized conditions using the pressure plate apparatus in the suction range of 0-500 kPa. The SWCC results are used to interpret the special clays behavior due to stabilizer treatment. In addition, relationships were developed between the basic clay and stabilized properties such as specific surface area and pore size distribution. The analysis showed that specific surface area decreases, cumulative pore volume and average pore size diameter decrease, dehydration rate slows and the thickness of water film thins after treatment with Ionic Soil Stabilizer. The research data and interpretation analysis presented here can be extended to understand the water film change behaviors influencing the mechanical and physical properties of stabilized special clay soils. KEY WORDS: ionic soil stabilizer, special clay, pore size diameter, specific surface area, soil water characteristic curve, water film

  3. Pesticide leaching in macroporous clay soils: field experiment and modeling

    NARCIS (Netherlands)

    Scorza Júnior, R.P.

    2002-01-01

    Keywords : pesticide leaching, macropores, preferential flow, preferential transport, cracked clay soil, pesticide leaching models, groundwater contamination, inverse modeling, bentazone and imidacloprid. The presence of macropores (i.e. shrinkage c

  4. Clay content evaluation in soils through GPR signal processing

    Science.gov (United States)

    Tosti, Fabio; Patriarca, Claudio; Slob, Evert; Benedetto, Andrea; Lambot, Sébastien

    2013-10-01

    The mechanical behavior of soils is partly affected by their clay content, which arises some important issues in many fields of employment, such as civil and environmental engineering, geology, and agriculture. This work focuses on pavement engineering, although the method applies to other fields of interest. Clay content in bearing courses of road pavement frequently causes damages and defects (e.g., cracks, deformations, and ruts). Therefore, the road safety and operability decreases, directly affecting the increase of expected accidents. In this study, different ground-penetrating radar (GPR) methods and techniques were used to non-destructively investigate the clay content in sub-asphalt compacted soils. Experimental layout provided the use of typical road materials, employed for road bearing courses construction. Three types of soils classified by the American Association of State Highway and Transportation Officials (AASHTO) as A1, A2, and A3 were used and adequately compacted in electrically and hydraulically isolated test boxes. Percentages of bentonite clay were gradually added, ranging from 2% to 25% by weight. Analyses were carried out for each clay content using two different GPR instruments. A pulse radar with ground-coupled antennae at 500 MHz centre frequency and a vector network analyzer spanning the 1-3 GHz frequency range were used. Signals were processed in both time and frequency domains, and the consistency of results was validated by the Rayleigh scattering method, the full-waveform inversion, and the signal picking techniques. Promising results were obtained for the detection of clay content affecting the bearing capacity of sub-asphalt layers.

  5. Ionic migration in soils and clays

    International Nuclear Information System (INIS)

    Migration of ions in soil to plant roots takes place either by the viscous movement of the soil solution through the pore space, or by ionic diffusion. As long as there is drainage viscous flow is possible, but when once the drainage stops ionic diffusion alone migrates the ions. The amount of the nutrient ion that diffuses at a given temperature in a soil depends upon the soil structure and the moisture condition. In free liquids, or in straight uniform channels, the diffusing ions are not obstructed in the course of their migration along the direction of measurement. In such cases the whole fractional area of the cross-section will be effective. But in a bed of soil where the channels bend round corners, forming twists and constrictions, the quantity of the ion diffused falls short of the expected value and the decrease in the ion diffused in such cases should be attributed to the twists and constrictions. The effective fractional areas obtained under different conditions of compaction give a measure of the effect of twists and constrictions on the migration of ions in each case

  6. Sorption of radionuclides on some clays and soils

    International Nuclear Information System (INIS)

    The sorption and desorption properties of radio- cesium, barium and iodine were studied using clay and soil fractions from various regions of Turkey. Clay minerals and soil fractions were identified by X-ray diffraction spectrometry and particle size distribution experiments. The clay minerals were found to be kaolinite, montmorillonite and mixed chlorite-illite types. Grain sizes of all solid particles were all -8 mols/L to 10-3 mols/L. The radionuclides 137Cs, 90Sr, 133Ba and 125I were used as tracers. Batch experiments were performed to determine the distribution ratio, RD, as a function of interaction time, shaking rate, ion concentration, pH, and volume/mass ratio. Cation exchange capacities were obtained using the silver-thiourea method. Kinetic studies indicated initial rapid sorption gradually reaching saturation in several days. The saturation time ranged from 6 to 12 days depending on clay as well as radionuclide types. Inverse S-shaped loading curves were obtained in the studies of RD versus cation concentration on the solid. The curves suggest the presence of at least two types of sorption sites on the clay minerals. The sorption process was observed to be reversible to a large extent in all cases. The distribution ratio was found to increase with increasing volume/mass ratio and with decreasing particle size. The latter observation suggests mainly surface sorption. Generally highest RD values were observed for cesium sorption followed by strontium and barium. Iodine was sorbed very little by clay minerals. (16 refs., 7 figs., 3 tabs.)

  7. Land Sliding Analysis on Red Clay soil using Fracture Criteria

    OpenAIRE

    Guthbutheen, Mohamed Riyazdeen Mavaday; ji, Yisho; Ji, Jin

    2012-01-01

    In order to assess the safe and functional design of road ways, buildings, bridges, dams, etc. Also to protect from structural damages and geological disasters. The landslide analysis is to conduct based on force resisting method by applying uniform loads on top of the hill to determine slope stability, instability, for with and without crack on clay soil is to be experimented and evaluate the mechanical properties such as elastic modulus, poison ratio, and shear strength. In addition, the nu...

  8. Rheological properties of different minerals and clay soils

    Directory of Open Access Journals (Sweden)

    Dolgor Khaydapova

    2015-07-01

    Full Text Available Rheological properties of kaolinite, montmorillonite, ferralitic soil of the humid subtropics (Norfolk island, southwest of Oceania, alluvial clay soil of arid subtropics (Konyaprovince, Turkey and carbonate loess loam of Russian forest-steppe zone were determined. A parallel plate rheometer MCR-302 (Anton Paar, Austria was used in order to conduct amplitude sweep test. Rheological properties allow to assess quantitatively structural bonds and estimate structural resistance to a mechanical impact. Measurements were carried out on samples previously pounded and capillary humidified during 24 hours. In the amplitude sweep method an analyzed sample was placed between two plates. The upper plate makes oscillating motions with gradually extending amplitude. Software of the device allows to receive several rheological parameters such as elastic modulus (G’, Pa, viscosity modulus (G", Pa, linear viscoelasticity range (G’>>G”, and point of destruction of structure at which the elastic modulus becomes equal to the viscosity modulus (G’=G”- crossover. It was found out that in the elastic behavior at G '>> G " strength of structural links of kaolinite, alluvial clay soil and loess loam constituted one order of 105 Pa. Montmorillonit had a minimum strength - 104 Pa and ferrallitic soil of Norfolk island [has] - a maximum one -106 Pa. At the same time montmorillonite and ferralitic soil were characterized by the greatest plasticity. Destruction of their structure (G '= G" took place only in the cases when strain was reaching 11-12%. Destraction of the kaolinite structure happened at 5% of deformation and of the alluvial clay soil and loess loam - at 4.5%.

  9. Field methods for studying soil moisture regimes and irrigation practices in clay soils

    International Nuclear Information System (INIS)

    Characterization of water flow through swelling clay soils with macropores (''cracks'') requires special techniques because these soils are not isotropic and homogeneous as required by standard flow theory. The techniques should preferably be rapid and inexpensive to allow applications in the field. Three experimental techniques, which were recently developed at the Netherlands Soil Survey Institute, are discussed. The measure: (i) vertical and horizontal Ksub(sat) in a gypsum-covered cube of soil which is carved out in situ (the cube method); (ii) the Ksub(unsat) near saturation down to pressure heads of about -15cm by determining fluxes through a series of crusts and the associated negative pressure heads below the crusts (the crusts test); and (iii) short-circuiting, which is the preferential movement of free water along vertical macropores in unsaturated soil, by applying sprinkling irrigation to large, undisturbed cores. In addition, three examples are discussed whereby soil morphological field data are used for simulation models which characterize soil moisture regimes of clay soils. These examples cover: (i) the effect of horizontal cracks on upward unsaturated flow; (ii) infiltration of sprinkling irrigation in a cracked clay soil; and (iii) ponded infiltration of water in a clay soil with worm channels. (author)

  10. Influence of cracking in the desiccation process of clay soils

    OpenAIRE

    Levatti, Hector Ulises; Prat Catalán, Pere; Ledesma Villalba, Alberto

    2009-01-01

    It is well known that clayey soils undergoing desiccation tend to shrink and eventually crack. Analysis of the behaviour and influence of cracks in these types of soils is very important in several engineering fields such as mine tailing dams, long-term radioactive waste storage, impervious core of earth dams, and in any situation where clay is used as a barrier to fluid flow. Loss of humidity and cracking changes the permeability of such barriers that may no longer work properly and pose pot...

  11. Soil-Water Characteristic Curves of Red Clay treated by Ionic Soil Stabilizer

    Science.gov (United States)

    Cui, D.; Xiang, W.

    2009-12-01

    The relationship of red clay particle with water is an important factor to produce geological disaster and environmental damage. In order to reduce the role of adsorbed water of red clay in WuHan, Ionic Soil Stabilizer (ISS) was used to treat the red clay. Soil Moisture Equipment made in U.S.A was used to measure soil-water characteristic curve of red clay both in natural and stabilized conditions in the suction range of 0-500kPa. The SWCC results were used to interpret the red clay behavior due to stabilizer treatment. In addition, relationship were compared between the basic soil and stabilizer properties such as water content, dry density, liquid limit, plastic limit, moisture absorption rate and stabilizer dosages. The analysis showed that the particle density and specific surface area increase, the dehydration rate slows and the thickness of water film thins after treatment with Ionic Soil Stabilizer. After treatment with the ISS, the geological disasters caused by the adsorbed water of red clay can be effectively inhibited.

  12. Origin of the high sensitivity of Chinese red clay soils to drought : significance of the clay characteristics

    OpenAIRE

    D'Angelo, Benoît; Bruand, Ary; Qin, Jiangtao; Peng, Xihnua; Hartmann, Christian; Bo, Sun; Hao, Hongtao; Rozenbaum, Olivier; Muller, Fabrice

    2014-01-01

    The red clay soils which are widespread in China are known to be highly sensitive to drought during the dry season but the origin of this high sensitivity to drought remains unclear. Several red clay soils were selected in the Hunan province for study. We studied their basic physico-chemical properties and clay mineralogy, their structure and shrinkage properties, as well as their water retention properties. Results show that the amount of water available between -330 and -15 000 hPa water po...

  13. A Preliminary Study on Identification of Clay Minerals in Soils with Reference to Reflectance Spectra

    Institute of Scientific and Technical Information of China (English)

    XUBIN-BIN; LIDE-CHENG; 等

    1995-01-01

    The characteristics of the reflectance spectra of clay minerals and their influences on the reflectance spectra of soils are dealt with in the paper.The results showed that dominant clay minerals in soils could be distinguished in light of the spectral -form parameters of the reflectance spectra of soils,thus making it possible to develop a quick method to determine clay minerals by means of reflectance spectra of soils in the lab.and providing a theoretic basis for remote sensing of clay minerals in soils with a high resolution imaging spectrometer.

  14. Lability of soil organic carbon in tropical soils with different clay minerals

    DEFF Research Database (Denmark)

    Bruun, Thilde Bech; Elberling, Bo; Christensen, Bent Tolstrup

    2010-01-01

    of SOC in tropical soils with contrasting clay mineralogy (kaolinite, smectite, allophane and Al-rich chlorite). Soil was sampled from A horizons at six sites in humid tropical areas of Ghana, Malaysian Borneo and the Solomon Islands and separated into fractions above and below 250 µm by wet sieving...

  15. Effects of Tillage Methods on Soil Fragmentation in Loamy-Clay Soils

    Directory of Open Access Journals (Sweden)

    Yousef Abbaspour-Gilandeh

    2009-01-01

    Full Text Available Problem statement: Soil fragmentation is a primary aim in tillage in order to create a favorable soil environment for crop growth. Soil fragmentation is defined as the process of breakdown and crumbling of soil aggregates. Currently, there is no published research data on optimum tillage operations for seedbed preparation in loamy-clay soils of western Caspian Sea region of Iran. Approach: Tests were conducted on a loamy-clay soil near the city of Ardabil, Iran, to investigate the effects of different tillage operations on soil crumbling. Four tillage treatments: Moldboard plow (M (conventional method, Moldboard plow and Disk-Harrow (MH, Decompactor and Moldboard plow (DM and De-Compactor and Disk-Harrow (DH were used in this study with four replications. The tillage depth for all treatments was about 30 cm. Following tillage operations, intensive soil samples were taken from the top 25 cm of soil at 5 cm depth increments and were analyzed for aggregate size and distribution using 9 standard sieves (0.25-19 mm mesh. Analysis of variance was carried out regarding soil crumbling percentage and mean diameter of soil aggregates in each treatment. The experiment was arranged in a split-plot design with five levels of soil sampling depths and two main factors (tillage method and tillage depth which were arranged in Latin Square design. Results: Results showed that the tillage treatments had a significant effect on soil crumbling. Also, soil crumbling varied with soil depth and the optimum particle sizes were developed at the 5-20 cm soil depth. There was a non-linear correlation between soil crumbling percentage and tillage depth. Conclusion/Recommendations: Tillage methods and soil sampling depth had interaction effect on soil crumbling percentage. The MH treatment had the greatest amount of soil crumbling and the best seed-bed condition.

  16. Prediction of clay content from water vapour sorption isotherms considering hysteresis and soil organic matter content

    DEFF Research Database (Denmark)

    Arthur, E.; Tuller, M.; Møldrup, Per;

    2015-01-01

    (average RMSE = 5.0%, ME = 2.4%) prediction of clay contents. However, the model for soils with small OC contents showed only minor improvement when compared with recently published models. Three main sources of prediction errors, namely large OC and silt contents, and a prevalence of 1:1 clay minerals......Soil texture, in particular the clay fraction, governs numerous environmental, agricultural and engineering soil processes. Traditional measurement methods for clay content are laborious and impractical for large-scale soil surveys. Consequently, clay prediction models that are based on water...... for estimating clay content from hygroscopic water at different relative humidity (RH) levels while considering hysteresis and organic matter content. Continuous adsorption/desorption vapour sorption isotherm loops were measured for 150 differently textured soils with a state-of-the-art vapour...

  17. Improved estimation of soil clay content by the fusion of remote hyperspectral and proximal geophysical sensing

    Science.gov (United States)

    Ciampalini, Andrea; André, Frédéric; Garfagnoli, Francesca; Grandjean, Gilles; Lambot, Sébastien; Chiarantini, Leandro; Moretti, Sandro

    2015-05-01

    Planning sustainable soil exploitation and land resource evaluation require up-to-date and accurate maps of soil properties. In that respect, geophysical techniques present particular interests given their non-invasiveness and their fast data acquisition capacity, which permit to characterize large areas with fine spatial and/or temporal resolutions. We investigated the relevancy of combining data from airborne hyperspectral (Hs), electromagnetic induction (EMI) and far-field ground-penetrating radar (GPR) for mapping soil properties, in particular soil clay content, at the field scale. Data from the three techniques were acquired at a test site in Mugello (Italy) characterized by relatively strong spatial variations of soil texture. Soil samples were collected for determining ground truth clay content. For the frequencies used in this study (200-650 MHz), the GPR surface reflection is mainly determined by soil dielectric permittivity, itself primarily influenced by soil moisture. In contrast, EMI is mostly sensitive to soil electrical conductivity, which integrates several soil properties including in particular soil moisture and clay content. Taking advantage of the complementary information provided by the two instruments, the GPR and EMI data were combined and correlated to local ground-truth clay content data to provide high-resolution clay content maps over the entire field area. Besides, a relationship was also observed between Hs data and clay content measurements, which permitted to produce a Hs-derived clay content map. EMI-GPR and Hs maps showed close spatial patterns and a relatively high correlation was observed between both clay content estimates, as well as between clay content estimates and ground-truth clay content measurements. Moreover, data fusion allowed constraining the EMI-GPR and Hs information and reduced the uncertainty of mapped clay content estimates. These results demonstrated great promise for integrated, digital soil mapping

  18. Theoretical Analysis of the Influence of the Thermal Diffusivity of Clay Soil on the Thermal Energy Distribution in Clay Soil of Abakaliki, Nigeria

    OpenAIRE

    Ugwu, E. I.

    2010-01-01

    The influence of the thermal diffusivity of clay soil on thermal energy distribution in clay soil was studied using one and two dimensioned heat equation, which was solved, by using separation of variables method. In the analysis, heat was assumed to be propagated along rectangular moldedclaywithlength(L)with the width being considered negligible in the case of one dimension with different temperature ranging from 350 to 1290ºC within zero to one minute chosen where some parameters such as th...

  19. Clay slurry and engineered soils as containment technologies for remediation of contaminated sites

    Energy Technology Data Exchange (ETDEWEB)

    Williams, J.R. [Reclamation Technology, Inc., Athens, GA (United States); Dudka, S.; Miller, W.P. [Univ. of Georgia, Athens, GA (United States); Johnson, D.O. [Argonne National Lab., IL (United States)

    1997-12-31

    Clay Slurry and Engineered Soils are containment technologies for remediation of waste disposal sites where leaching, groundwater plumes and surface runoff of contaminants are serious ecological hazards to adjacent environments. This technology is a patent-pending process which involves the use of conditioned clay materials mixed with sand and water to form a readily pourable suspension, a clay slurry, which is either placed into a trench barrier system or allowed to de-water to create Engineered Soils. The Engineered Soil forms a layer impervious to water and air, therefore by inhibiting both water and oxygen from penetrating through the soil the material. This material can be installed in layers and as a vertical barrier to create a surface barrier containment system. The clay percentage in the clay slurry and Engineered Soils varies depending on site characteristics and desired performance standards. For example Engineered Soils with 1-2% of clay (dry wt.) had a hydraulic conductivity (K) of 10{sup -8} to 10{sup -1} cm/sec. Tests of tailing materials from a kyanite and pyrite mine showed that the clay slurry was effective not only in reducing the permeability of the treated tailings, but also in decreasing their acidity due to the inherent alkalinity of the clay. The untreated tailings had pH values in the range of 2.4 - 3.1; whereas, the effluent from clay and tailings mixtures had pH values in a slightly alkaline range (7.7-7.9). Pug-mills and high volume slurry pumps can be readily adapted for use in constructing and placing caps and creating Engineered Soils. Moreover, material on site or from a local sand supply can be used to create clay slurries and engineered soils. Clay materials used in cap construction are likewise readily available commercially. As a result, the clay slurry system is very cost effective compared to other capping systems, including the commonly used High Density Polyethylene (HDPE) liner systems.

  20. Effects of organic matter and clay content in soil on pesticide adsorption processes

    OpenAIRE

    Rada Đurović; Jelena Gajić-Umiljendić; Tijana Đorđević

    2009-01-01

    The effect of organic matter and clay content on the adsorption of atrazine, acetochlor, clomazone, pendimethalin and oxyfluorfen in soil samples was studied. In order to determine whether and to what degree different soil properties affect the process of determination of selected pesticides, three soils with different clay and organic matter contents were used. An optimized liquid-solid extraction procedure followed by SPME measurement was applied to analyze the selected pesticides in soil s...

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

    International Nuclear Information System (INIS)

    Relationships between Radiocesium Interception Potential (RIP) and mineralogical characteristics of the clay fraction isolated from 97 paddy soils (Hama-dori, n = 25; Naka-dori, n = 36; Aizu, n = 36) in Fukushima Prefecture, Japan were investigated to clarify the mineralogical factors controlling the 137Cs retention ability of soils (half-life 30.1 y). Of all the fission products released by the Fukushima accident, 137Cs is the most important long-term contributor to the environmental contamination. The RIP, a quantitative index of the 137Cs retention ability, was determined for the soil clays. The composition of clay minerals in the soil clays was estimated from peak areas obtained using X-ray diffraction (XRD) analyses. The predominant clay mineral was smectite in soils from Hama-dori and Aizu, while this was variable for those from Naka-dori. Native K content of the soil clays was found to be an indicator of the amount of micaceous minerals. The average RIP for the 97 soil clays was 7.8 mol kg−1, and ranged from 2.4 mol kg−1 to 19.4 mol kg−1. The RIP was significantly and positively correlated with native K content for each of the geographical regions, Hama-dori (r = 0.76, p 137Cs retention ability of the soil clays, but also could be used to predict the 137Cs retention ability of soil clays for other paddy fields in Fukushima and other areas. - Highlights: • RIP was measured for 97 paddy soils from Fukushima to assess 137Cs retention ability. • The dominant clay mineral was smectite, but this did not control RIP. • RIP was positively correlated with native K content. • Micaceous minerals were found to control the 137Cs retention ability of the soil

  2. Effect of Clay Minerals on the Chemical Characteristics of Soil Humus

    Institute of Scientific and Technical Information of China (English)

    YEWEI; WENQIXIAO

    1996-01-01

    Chemical characteristics of humic substances in soils with different mineralogical characteristics and under different utilization paterns in Zhangpu,Fujian Province,together with two pairs of cultivated soils in North China Plain were studied by chemical analysis,visible and IR spectroscopy and 13C NMR spectrometry.For soils in Zhanpu the HA/FA ratio and both the aromaticity and the degree of humification of HA were higher in soils with montmorillonite as the predominant clay mineral than in those with kaolinite as the predominant clay mineral,provided these soils were under the same utilization pattern.While for each pair of soils with similar mineralogical characteristics the HA/FA ratio was higher and the C/H ratio and the contnet of carboxyl group of HA were lower in paddy soil than in upland soil.Among the upland soils(or paddy soils)studied the Ha/FA ratio of soil in Zhangpu with kaolinite as the predominant clay mineral was the lowest,and that of soil in Zhangpu with montmorillonite as the predominant clay mineral was the highest .the lowest.and that of soil in Zhangpu with montmorillonite as the predominant clay mineral was the highest It was concluded that the presence of montmorillonite favored the fromation and maturation of humic acid.

  3. Polyacrylamide effects on aggregate and structure stability of soils with different clay mineralogy

    Science.gov (United States)

    Adding anionic polyacrylamide (PAM) to soils stabilizes existing aggregates and improves bonding between and aggregation of soil particles. However, the dependence of PAM efficacy as an aggregate stabilizing agent with soils having different clay mineralogy has not been studied. Sixteen soil samples...

  4. Soil aggregate stability as affected by clay mineralogy and polyacrylamide addition

    Science.gov (United States)

    The addition of polyacrylamide (PAM) to soil leads to stabilization of existing aggregates and improved bonding between, and aggregation of adjacent soil particles However, the dependence of PAM efficacy as an aggregate stabilizing agent on soil-clay mineralogy has not been studied. Sixteen soil sam...

  5. Soil Compaction and Oil Palm (Elaeis guineensis Yield in a Clay Textured Soil

    Directory of Open Access Journals (Sweden)

    Zuraidah Yahya

    2010-01-01

    Full Text Available Problem statement: The impacts of soil compaction on crop yields have been studied extensively by soil scientists due to declining soil productivity associated with mechanisation. However, a relationship between machine-induced soil compaction and oil palm (Elaeis guineensis yield is unclear. Therefore, the objectives of this study were to determine the effects of mechanization on soil physical properties and the influence on oil palm yield. Approach: The palms were planted in Bernam series soil which is clay textured. Compaction treatments were imposed for 6 consecutive years. Comparisons were made between the effects of soil compaction caused by different trailer weights and monthly transportation frequency. Results: The results showed a beneficial effect of soil compaction on the oil palm yield. It significantly increased the yield with increased mean soil bulk density. The transportation frequency played a greater role than the trailer weight. After six years of soil compaction, there was a positive relationship between mean soil bulk density, porosity and oil palm yield. Conclusion: Thus compaction may not often be a problem.

  6. Estimation of the density of the clay-organic complex in soil

    Science.gov (United States)

    Czyż, Ewa A.; Dexter, Anthony R.

    2016-01-01

    Soil bulk density was investigated as a function of soil contents of clay and organic matter in arable agricultural soils at a range of locations. The contents of clay and organic matter were used in an algorithmic procedure to calculate the amounts of clay-organic complex in the soils. Values of soil bulk density as a function of soil organic matter content were used to estimate the amount of pore space occupied by unit amount of complex. These estimations show that the effective density of the clay-organic matter complex is very low with a mean value of 0.17 ± 0.04 g ml-1 in arable soils. This value is much smaller than the soil bulk density and smaller than any of the other components of the soil considered separately (with the exception of the gas content). This low value suggests that the clay-soil complex has an extremely porous and open structure. When the complex is considered as a separate phase in soil, it can account for the observed reduction of bulk density with increasing content of organic matter.

  7. Clays Can Decrease Gaseous Nutrient Losses from Soil-Applied Livestock Manures.

    Science.gov (United States)

    Pratt, Chris; Redding, Matthew; Hill, Jaye; Brown, Grant; Westermann, Maren

    2016-03-01

    Clays could underpin a viable agricultural greenhouse gas (GHG) abatement technology given their affinity for nitrogen and carbon compounds. We provide the first investigation into the efficacy of clays to decrease agricultural nitrogen GHG emissions (i.e., NO and NH). Via laboratory experiments using an automated closed-vessel analysis system, we tested the capacity of two clays (vermiculite and bentonite) to decrease NO and NH emissions and organic carbon losses from livestock manures (beef, pig, poultry, and egg layer) incorporated into an agricultural soil. Clay addition levels varied, with a maximum of 1:1 to manure (dry weight). Cumulative gas emissions were modeled using the biological logistic function, with 15 of 16 treatments successfully fitted ( carbon retained in treatments containing clay compared with treatments containing no clay. This preliminary assessment of the efficacy of clays to mitigate agricultural GHG emissions indicates strong promise. PMID:27065411

  8. Experimental Study on Unconfined Compressive Strength of Basalt Fiber Reinforced Clay Soil

    OpenAIRE

    Lei Gao; Guohui Hu; Nan Xu; Junyi Fu; Chao Xiang; Chen Yang

    2015-01-01

    In order to study the mechanism and effect of basalt fiber reinforced clay soil, a series of unconfined compressive strength tests conducted on clay soil reinforced with basalt fiber have been performed under the condition of optimum water content and maximum dry density. Both the content and length of basalt fiber are considered in this paper. When the effect of content is studied, the 12 mm long fibers are dispersed into clay soil at different contents of 0.05%, 0.1%, 0.15%, 0.20%, 0.25%, 0...

  9. Clay mineral formation and transformation in rocks and soils

    Science.gov (United States)

    Eberl, D.D.

    1983-01-01

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

  10. Phosphorus leaching from clay soils can be counteracted by structure liming

    OpenAIRE

    Ulen, Barbro; Etana, Ararso

    2014-01-01

    Two field experiments with drained plots on clay soils (60 and 25 % clay) demonstrated a significant reduction in leaching of total phosphorus after application of structure lime. Aggregate stability, was significantly improved. Phosphorus leaching in particulate form was significantly reduced following structure liming at the site with a very high clay content. Sites representing low (50 mg kg-1) and high (140 mg kg-1) levels of phosphorus extractable with acid ammonium lactate in topsoil di...

  11. Searching the critical soil organic carbon threshold for satisfactory tilth conditions – test of the Dexter clay:carbon hypothesis

    OpenAIRE

    Schjønning, P.; de Jonge, L. W.; P. Moldrup; B. T. Christensen; Olesen, J.E.

    2010-01-01

    The concern for deteriorating soil structure at low soil organic matter (SOM) contents calls for better knowledge of SOM interaction with soil minerals as well as guidelines for soil conservation. We measured clay dispersibility in a field with a textural gradient. Our results support the concept of differentiating soil content of clay in a complexed and non-complexed part although our data did not point out an exact clay/OC ratio threshold. Our results also indicated that labile fractions of...

  12. Electrical properties of water in clay and silty soils

    Science.gov (United States)

    Saarenketo, Timo

    1998-10-01

    In order to better understand ground penetrating radar (GPR) results obtained in road surveys and site investigations, the dielectric properties and electrical conductivity of four silt and clay soils were measured at different densities and moisture contents ranging from oven dry material to the plastic state. The real parts K' and imaginary parts K″ of the relative dielectric permittivity values of the soils were measured with an HP Surface Network Analyzer over a frequency range from 30 MHz to 3.0 GHz. A dielectric and electrical conductivity meter produced by Adek was also used. The results suggest that water in soils can be classified according to its electrical properties as: (1) an adsorption water layer, also known as the hygroscopic water layer; (2) a viscous or capillary water layer; and (3) free water. The measurements also showed that the adsorption water layer can be divided into inner and outer layers in accordance with the electrical double layer theory. The imaginary part of the dielectric value of the material is formed mainly in the outer layer and partly in the viscous (capillary) water layer, which also has two layers with differing electrical properties. The measurements also clearly showed that if the Cation Exchange Capacity (CEC) of a material is low, the water molecules are orderly arranged around the soil particles and the dielectric values of the bound water layers remain almost independent of frequency. If the CEC increases, the molecular structure of the bound water layers is disturbed and the water molecules more easily follow the changing AC field so that the dielectric value is higher. These materials are also highly dielectrically dispersive, especially at GPR frequencies below 400 MHz. Increasing CEC correlates well with increasing imaginary part of the adsorption water layer. Measured ohmic electrical conductivities were low at low moisture content and increased as the outer viscous water layer developed with higher moisture

  13. Comparing Kriging and Regression Approaches for Mapping Soil Clay Content in a diverse Danish Landscape

    DEFF Research Database (Denmark)

    Adhikari, Kabindra; Bou Kheir, Rania; Greve, Mette Balslev;

    2013-01-01

    Information on the spatial variability of soil texture including soil clay content in a landscape is very important for agricultural and environmental use. Different prediction techniques are available to assess and map spatial variability of soil properties, but selecting the most suitable...

  14. Evaluation of Water Vapor Sorption Hysteresis in Soils: The Role of Organic Matter and Clay

    DEFF Research Database (Denmark)

    Arthur, Emmanuel; Tuller, Markus; Moldrup, Per;

    2015-01-01

    Hysteresis of the soil water characteristic (SWC) has been extensively studied for matric potentials between zero and −1.5 MPa. However, little information is available on how to quantify, evaluate, and identify the causes of hysteresis at potentials below −10 MPa where vapor sorption plays an...... important role. It is clear that modeling physical and biological soil processes is more accurate when SWC hysteresis is considered, particularly at low potentials where small differences in water content are associated with large changes in potential energy. The objectives of the presented study were to......: (i) evaluate and compare recently developed methods (MBET-n, Dh and SPN) for quantifying hysteresis in soils and pure clays, and (ii) investigate the role of organic matter (OM) and clay content and type on hysteresis. Five pure clays and two sets of soils with gradients in organic matter and clay...

  15. Effect of Polypropylene Fibers, Lime and Ceramic Additives on the Compressibility of Silty-Clay Soil

    OpenAIRE

    Hiba D. Saleem; Asad H. Humaish

    2016-01-01

    Soil stabilization is widely used by geotechnical engineers in the world to increase soil strength, soil compressibility and reduce the permeability. The main aim of this paper is to investigate the effect of adding different materials to the silty clayey soil (i.e. polypropylene fibers, lime and ceramic) and to figure out how the compressibility behave under mixture soil and these stabilized material at different percent (investigation their effect on the value of settlement). Silty clay ...

  16. Electron Microscopic Observation of Clays of Calcareous and Noncalcareous Soils in Bangladesh

    OpenAIRE

    ALAM, Md. Lutfe; KAKOI, Teruzane; MIYAUCHI, Nobufumi; SHINAGAWA, Akio; カコイ, テルザネ; ミヤウチ, ノブフミ; シナガワ, アキオ

    1993-01-01

    Electron microscopic observation of calcareous and noncalcareous floodplain soils of Bangladesh were carried out by TEM and SEM. Morphological changes in relation to clay formation and weathering process were investigated. Unweathered, partially weathered and weathered micaceous mineralsaccompanying with poorly crystallized kaolinite and halloysite and other primary minerals were observed in silt and coarse clay of both calcareous and noncalcareous soil. Smectite and vermiculite which aredomi...

  17. Electron Microscopic Observation of Clays of Calcareous and Noncalcareous Soils in Bangladesh

    OpenAIRE

    ALAM, Md. Lutfe; KAKOI, Teruzane; MIYAUCHI, Nobufumi; SHINAGAWA, Akio; カコイ, テルザネ; ミヤウチ, ノブフミ; シナガワ, アキオ

    1993-01-01

    Electron microscopic observation of calcareous and noncalcareous floodplain soils of Bangladesh were carried out by TEM and SEM. Morphological changes in relation to clay formation and weathering process were investigated. Unweathered, partially weathered and weathered micaceous minerals accompanying with poorly crystallized kaolinite and halloysite and other primary minerals were observed in silt and coarse clay of both calcareous and noncalcareous soil. Smectite and vermiculite which are...

  18. Mineral composition of the clay fraction in soils with a cambic horizon in the Czech Republic

    Czech Academy of Sciences Publication Activity Database

    Žigová, Anna; Šťastný, Martin; Krejčová, J.

    Szeged : University of Szeged, 2010 - (Zaharia, L.). Roč. 6, - (2010), s. 648-648 ISSN 0324-6523. [Mid-European Clay Conference (MECC 2010) /5./. 25.08.2010-29.08.2010, Budapest] R&D Projects: GA ČR GA526/08/0434 Institutional research plan: CEZ:AV0Z30130516 Keywords : soil s * cambic horizon * parent material * clay minerals Subject RIV: DF - Soil Science

  19. Potential use of lateritic and marine clay soils as landfill liners to retain heavy metals.

    Science.gov (United States)

    Chalermyanont, Tanit; Arrykul, Surapon; Charoenthaisong, Nanthanit

    2009-01-01

    The potential of a lateritic soil and a marine clay, typical of those found in hot and humid climatic regions, was assessed for use as a landfill liner material. A series of tests were conducted - physical and chemical, batch adsorption, column, hydraulic conductivity, etc., - to evaluate the heavy metal sorption capacity, chemical compatibility of hydraulic conductivity, and transport parameters of the soils. Experimental results showed that the marine clay had better adsorption capacity than that of the lateritic soil and that its hydraulic conductivity was an order of magnitude lower. In addition, the hydraulic conductivities of both soils when permeated with low concentration heavy metal solutions were below 1x10(-7)cm/s. When permeated with Cr, Pb, Cd, Zn, and Ni solutions, the retardation factors of the lateritic soil and the marine clay ranged from 10 to 98 and 37 to 165, respectively, while the diffusion coefficients ranged from 1.0x10(-5) to 7.5x10(-6) and 3.0 to 9.14x10(-7)cm2/s, respectively. For both soils, Cr and Pb were retained relatively well, while Cd, Zn, and Ni were more mobile. The marine clay had higher retardation factors and lower diffusion coefficients, and its hydraulic conductivity was more compatible with Cr solution, than that of the lateritic soil. In general, the properties of the marine clay indicate that it has significant advantages over the lateritic soil as landfill liner material. PMID:18550353

  20. Estimation of hydraulic conductivity on clay content in soil determined from resistivity data

    Energy Technology Data Exchange (ETDEWEB)

    Shevnin, Vladimir; Delgado-Rodriguez, Omar; Mousatov, Aleksandr [Mexican Petroleum Institute, Mexico, D.F. (Mexico); Ryjov, Albert [Moscow State Geological Prospecting Academy, Geophysical Faculty, Moscow (Russian Federation)

    2006-07-15

    The influence of clay content in sandy and clayey soils on hydraulic conductivity (filtration coefficient) is considered. A review of published experimental data on the relationship of hydraulic conductivity with soil lithology and grain size, as dependent on clay content is presented. Theoretical calculations include clay content. Experimental and calculated data agree, and several approximation formulas for filtration coefficient vs clay content are presented. Clay content in soil is estimated from electric resistivity data obtained from 2D VES interpretation. A two-step method is proposed, the first step including clay content calculating from soil resistivity and groundwater salinity, and the second step including filtration coefficient estimating from clay content. Two applications are presented. [Spanish] El contenido de arcilla en suelos areno-arcillosos influye sobre la permeabilidad hidraulica (coeficiente de filtracion). Se presenta una revision de datos experimentales publicados que relacionan el coeficiente de filtracion con el tipo litologico del suelo y el tamano de las particulas. A partir de calculos teoricos, se modifican las conocidas formulas que relacionan el coeficiente de filtracion con el contenido de arcilla. Se estima el contenido de arcilla a partir de los datos interpretados por el metodo SEV, y se propone un procedimiento para la estimacion del coeficiente de filtracion: (a) calculo del contenido de arcilla a partir de la resistividad del suelo y de la salinidad del agua subterranea, (b) estimacion del coeficiente de filtracion a partir del contenido de arcilla. Se presentan algunos ejemplos de la aplicacion de esta metodologia.

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

    Science.gov (United States)

    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. Effect of Soil Clay Content on RNA Isolation and on Detection and Quantification of Bacterial Gene Transcripts in Soil by Quantitative Reverse Transcription-PCR ▿†

    OpenAIRE

    Novinscak, A.; Filion, M.

    2011-01-01

    In this study, we evaluated the effect of soil clay content on RNA isolation and on quantitative reverse transcription-PCR (qRT-PCR) quantification of microbial gene transcripts. The amount of clay significantly altered RNA isolation yields and qRT-PCR analyses. Recommendations are made for quantifying microbial gene transcripts in soil samples varying in clay content.

  3. Water storage change estimation from in situ shrinkage measurements of clay soils

    OpenAIRE

    Brake, B.; M. J. van der Ploeg; Rooij, G. H.

    2012-01-01

    The objective of this study is to assess the applicability of clay soil elevation change measurements to estimate soil water storage changes, using a simplified approach. We measured moisture contents in aggregates by EC-5 sensors, and in multiple aggregate and inter-aggregate spaces (bulk soil) by CS616 sensors. In a long dry period, the assumption of constant isotropic shrinkage proved invalid and a soil moisture dependant geo...

  4. Measurement of exchangeable aluminium in soils and clay minerals by isotopic exchange

    International Nuclear Information System (INIS)

    Isotopically exchangeable Al was determined in soils and clay minerals by equilibration with 28Al. Best results were obtained with a weak extractant and an equilibration time of eight min. The calculated amount of isotopically exchangeable Al was independent of the amount of carrier-Al added with the 28Al. In some soils isotopically exchangeable Al did not appear to be related to the amount of Al which could be extracted by various electrolyte solutions. This technique provides an improved means of studying the exchange reactions of Al in acid soils and clay minerals

  5. Chemical dispersants and pre-treatments to determine clay in soils with different mineralogy

    Directory of Open Access Journals (Sweden)

    Cristiane Rodrigues

    2011-10-01

    Full Text Available Knowledge of the soil physical properties, including the clay content, is of utmost importance for agriculture. The behavior of apparently similar soils can differ in intrinsic characteristics determined by different formation processes and nature of the parent material. The purpose of this study was to assess the efficacy of separate or combined pre-treatments, dispersion methods and chemical dispersant agents to determine clay in some soil classes, selected according to their mineralogy. Two Brazilian Oxisols, two Alfisols and one Mollisol with contrasting mineralogy were selected. Different treatments were applied: chemical substances as dispersants (lithium hydroxide, sodium hydroxide, and hexametaphosphate; pre-treatment with dithionite, ammonium oxalate, and hydrogen peroxide to eliminate organic matter; and coarse sand as abrasive and ultrasound, to test their mechanical action. The conclusion was drawn that different treatments must be applied to determine clay, in view of the soil mineralogy. Lithium hydroxide was not efficient to disperse low-CEC electropositive soils and very efficient in dispersing high-CEC electronegative soils. The use of coarse sand as an abrasive increased the clay content of all soils and in all treatments in which dispersion occurred, with or without the use of chemical dispersants. The efficiency of coarse sand is not the same for all soil classes.

  6. Efficient resource management in dairy farming on peat and heavy clay soils

    NARCIS (Netherlands)

    Visser, de P.H.B.; Keulen, van H.; Lantinga, E.A.; Udo, H.M.J.

    2001-01-01

    Peat and heavy clay soils in the Netherlands are mainly used for permanent grassland to support dairy farming. As a result of intensification in dairy farming during the last decades, environmental quality is threatened by high emissions of N and P. Increased drainage of the wet soils has induced hi

  7. Effects of acid atmospheric deposition on the chemical composition of loess, clay and peat soils under forest in the Netherlands

    NARCIS (Netherlands)

    Klap, J.M.; Vries, de W.; Leeters, E.E.J.M.

    1999-01-01

    In addition to a survey of the soils under 150 forest stands on non-calcareous sandy soils, the chemical composition of the soils under 40 stands on non-calcareous loess soil, 30 stands on non-calcareous clay soils and 30 stands on oligotrophous peat soils have been examined, to assess the current s

  8. Effects of clay minerals on radiocesium sorption behavior onto paddy field soils

    International Nuclear Information System (INIS)

    From the viewpoint of radiological dose assessment, 137Cs is one of the most important radionuclides due to its long half life (30 y). In this work, sorption behavior of 137Cs in Japanese paddy field soils was investigated, taking into account effects of chemical properties. Soil-soil solution distribution coefficients (KdS) which are defined as the relation between an adsorbed radionuclide concentration and that present in the solution were measured for 30 daddy field soil samples collected throughout Japan. These measurements were carried out using the batch sorption test. Then, sequential extraction methods were carried out to determine the ratio of 137Cs fixed on soil. In addition, soil properties, such as pH, cation exchange capacity (CEC) and total carbon, total nitrogen and clay contents were measured as well. X-ray diffraction analysis was carried out to identify the clay minerals in soil samples. In particular, content of illite which can sorb Cs strongly was determined as a relative amount for all soil samples. Kd values ranged from 269-16 637 L/kg (geometric mean=2 286 L/kg). A correlation was observed between the Kd values and clay content with a Spearman rank correlation coefficient (Rc) of 0.55 (p 137Cs fixed in soil had good correlation with relative illite content (Rc=0.68, p137Cs fixed on soil. (author)

  9. Effects of Organic Matter and Clay Content in Soil on Pesticide Adsorption Processes

    Directory of Open Access Journals (Sweden)

    Rada Đurović

    2009-01-01

    Full Text Available The effect of organic matter and clay content on the adsorption of atrazine, acetochlor, clomazone, pendimethalin and oxyfluorfen in soil samples was studied. In order to determine whether and to what degree different soil properties affect the process of determinationof selected pesticides, three soils with different clay and organic matter contents were used. An optimized liquid-solid extraction procedure followed by SPME measurement was applied to analyse the selected pesticides in soil samples. Detection and quantificationwere done by gas chromatography-mass spectrometry (GC/MS. Relative standard deviation (RSD values for multiple analyses of soil samples fortified at 30 μg/kg of each pesticide were below 19%. Limits of detection (LODs for all compounds studied were less than 2 μg/kg. The results indicate that soils with different physico-chemical properties have different effects on the adsorption of most pesticides, especially at higher concentration levels.

  10. "Clay grounds” in Denmark: from soil to canvas

    DEFF Research Database (Denmark)

    Buti, David; Vila, Anna; Haack Christensen, Anne; Filtenborg, Troels Folke; Dalby, Kim Nicole; Wadum, Jørgen

    large decorative scheme showed that at least two grounds from those paintings consist mainly of clay mixed with iron and magnesium-containing compounds. Furthermore, both SEM-EDX and µRaman measurements clearly highlighted the presence of a large amount of quartz particles. It is well known that clay is...... a sheet silicate mineral and may contain variable amounts of water trapped in its structure and can occur with other phases including quartz and carbonates. Studies carried out by Kühn and Groen and summarized by the latter show that in the Netherlands this kind of preparation layer was first...

  11. Effect of potassium on fixation of ammonium by clay minerals in different soil layers

    Directory of Open Access Journals (Sweden)

    Agelda Ajazi

    2013-12-01

    Full Text Available In intensive agriculture systems, efficient nutrient use is necessary for high crop yields as well as for sustainable environment management. Fixation of NH4+ and K+ by soil clays affect N and K availability to plants. Latest studies indicates that non-exchangeable NH4+, may affect crop productivity and soil N dynamics more than previously thought. An incubation study with K2SO4 and NH4NO3 was conducted to evaluate NH4+ and K+ fixation in two southern Albanian soils. Soils contained significant amount of native-fixed NH4+ and showed relatively high NH4+ fixing capacity. Native fixed ammonium content varied for horizons Ap and BCg, from 97 to 133 mg/kg and accounted for between 5 to 19, 8 % of the total nitrogen, respectively . Ammonium fixation was increased with N rates and was reduced with increased K rates. When K was added to the soil prior to the NH4, the amount of ammonium fixed was reduced. By contrast, when K+ and NH4+ were added to the soils simultaneously (equivalent amount; 2mEq/100g, the ammonium fixation was increased somewhat in the BCg horizon , whereas no such preference for ammonium fixation was found in the Ap horizon. In case when NH4+ and K+ were added to the soil samples in form of solutions, containing equal amounts of NH4+ (corresponding to 2 mEq NH4+/100 g soil but varying amounts of K+, the capacity of the soil to fix ammonium was reduced in proportion to the amount of K+ added. The soil samples incubated anaerobically, were with high differences in clay minerals content. The dominate clay minerals for profile (I-Ap horizon are smectite > vermiculite > Ilite, while vermiculite plus ilite (as the most important clay fixed minerals, comprised 21% of clay fraction and 13 % of the soil. In the profile (II-BCg horizon, the dominant clay minerals ranged; vermiculite > Ilite > smectite, while (vermiculite + ilite, comprised 52% of the clay fraction and 23, 4 % of the soil. Studies on Ap and BCg horizons comparing the amount of

  12. Nematodes in clay colliery spoil heaps and experimentally introduced strips of meadow soil

    Czech Academy of Sciences Publication Activity Database

    Háněl, Ladislav

    České Budějovice : Institute of Soil Biology AS CR, 2003. s. 25. [Central European Workshop on Soil Zoology /7./. 14.04.2003-16.04.2003, České Budějovice] R&D Projects: GA ČR GA526/01/1055 Institutional research plan: CEZ:AV0Z6066911 Keywords : nematodes * clay colliery spoil heaps * strips of meadow soil Subject RIV: EH - Ecology, Behaviour

  13. Hydraulic conductivity study of compacted clay soils used as landfill liners for an acidic waste

    International Nuclear Information System (INIS)

    Highlights: ► Examined the hydraulic conductivity evolution as function of dry density of Tunisian clay soil. ► Follow the hydraulic conductivity evolution at long-term of three clay materials using the waste solution (pH=2.7). ► Determined how compaction affects the hydraulic conductivity of clay soils. ► Analyzed the concentration of F and P and examined the retention of each soil. - Abstract: Three natural clayey soils from Tunisia were studied to assess their suitability for use as a liner for an acid waste disposal site. An investigation of the effect of the mineral composition and mechanical compaction on the hydraulic conductivity and fluoride and phosphate removal of three different soils is presented. The hydraulic conductivity of these three natural soils are 8.5 × 10−10, 2.08 × 10−9 and 6.8 × 10−10 m/s for soil-1, soil-2 and soil-3, respectively. Soil specimens were compacted under various compaction strains in order to obtain three wet densities (1850, 1950 and 2050 kg/m3). In this condition, the hydraulic conductivity (k) was reduced with increasing density of sample for all soils. The test results of hydraulic conductivity at long-term (>200 days) using acidic waste solution (pH = 2.7, charged with fluoride and phosphate ions) shows a decrease in k with time only for natural soil-1 and soil-2. However, the specimens of soil-2 compressed to the two highest densities (1950 and 2050 kg/m3) are cracked after 60 and 20 days, respectively, of hydraulic conductivity testing. This damage is the result of a continued increase in the internal stress due to the swelling and to the effect of aggressive wastewater. The analysis of anions shows that the retention of fluoride is higher compared to phosphate and soil-1 has the highest sorption capacity.

  14. Carbon-Nitrogen Relationships during the Humification of Cellulose in Soils Containing Different Amounts of Clay

    DEFF Research Database (Denmark)

    Sørensen, Lasse Holst

    1981-01-01

    amount of labeled N incorporated into organic forms increased in the clay-rich soils with increasing size of amendments. Of the total labeled C remaining in the soils after the 1st mo. of incubation 50-70% was acid hydrolyzable, compared to 80-100% of the total remaining labeled organic N. This...... 1st mo. of incubation at temperatures of 10, 20 and 30.degree. C, respectively, 38-65% of the labeled C added in cellulose had disappeared from the soils as CO2, and 60-nearly 100% of the labeled N added as NH4+ were incorporated into organic forms. The retention of total labeled C was largest in...... the soil with thg highest content of clay where after 4 yr it was 25% of that added, compared to 12 in the soil with the lowest content of clay. The incorporation of labeled N in organic forms and its retention in these forms was not directly related to the content of clay in the soils, presumably...

  15. Soil Clay Minerals in Namibia and their Significance for the Terrestrial and Marine Past Global Change Research

    OpenAIRE

    HEINE, Klaus; Völkel, Jörg

    2010-01-01

    We delineated seven soil clay mineral provinces in Namibia. Many individual clay mineral assemblages occur in fluvial, pan, cave and other environments. Previous researchers have used clay mineral compositions as evidence for palaeoenvironmental reconstructions, often without analyzing the formation, the transport and the deposition of these clay minerals. In Namibia, rates of erosion and denudation by water and wind have been very small since early Quaternary times. During the Quaternary, th...

  16. A semi-analytical solution for frost heave prediction of clay soil

    Institute of Scientific and Technical Information of China (English)

    Hui Bing; Ying Zhang; GuoYu Li

    2014-01-01

    Frost heave is one of the main freezing problems for construction in permafrost regions. The Konrad-Morgenstern seg-regation potential (SP) model is being used in practice for frost heave using numerical techniques. However, the heat re-lease from in-situ and migrated water in the freezing zone could result in some numerical instability, so the simulation of frost fringe is not ideal. In this study, a semi-analytical solution is developed for frost heave prediction of clay soil. The prediction results to the two tests with different freezing mode with clay soil agree well with the tested behavior, which indicates the feasibility of the solution.

  17. Clay Mineralogical Composition of Tea Garden Soils in Shandong Province, China

    OpenAIRE

    Han, Jing-Long; Yang, Qi-Xia; Ming ZHAO; Liu, Ying-Xia; Egashira, Kazuhiko

    2008-01-01

    For assistance of the appropriate plant-nutrient management practice to keep the sustainable tea production in Shandong Province, particle-size and clay mineral analyses were carried out to the surface layer of soils collected in tea gardens of Laoshan region of Qingdao City and Dahainanchun region of Jimo City, Shandong Province, People's Republic of China. Variation of the particle-size distribution with sites was small in each region. The clay content ranged from 17.6 to 22.7% for soils ...

  18. Clay Mineralogy Investigation In The Soils Of Arid Almanaqil Ridge Gezira State Sudan Using Xrd Diffractograms

    Directory of Open Access Journals (Sweden)

    Elhag A.M.H

    2015-07-01

    Full Text Available Abstract Clay mineralogy was studied in the soils of Arid Almanaqil Ridge. The soils are classified according to the American System Keys to Soil Taxonomy 2010 in the fallowing families Fine loamy mixed isohyperthermic TypicHaplustepts unit1 sample A1 and A2 Fine mont superactive Isohyperthermic VerticHaplocambids unit2 sample A3 and Fine mont superactive isohyperthermic TypicHaploustert unit3 sample A4. Representative soil samples were collected from these units. These samples were samples A1 and A2 for unit1 sample A3 for unit 2 and sample A4 for uint3 respectively. Those samples were compared with samples from outside the study area from north of the study area sample A5 and A6 and from the alluvium of the Blue Nile sample A7 according to their lithology topographic position soil types and soil mapping units. Clay mineralogy of the samples was studied using X-ray diffractograms XRD techniques. The XRD diffractograms indicated the presence of smectite chlorite illite and kaolinite as the major clay minerals in the soil of the study area and outside of the study area. The major clay minerals in these soils Chlorite illite and kaolinite could have originated from parent material. Smectite showed an increasing trend in samples A7 outside of study area and sample A4 unit 3. The CEC of clay minerals in unit 1 and 2 were less than 50 Cmolkg which indicated that minerals with low CEC were dominant this result conformed with the XRD results that showed dominance of Chlorite illite and Kaolinite. Higher CEC values more than 50 Cmolkg of the clay were encountered in soils samples from unit3 A4 and those from outside study area Sample A7 XRD results showed that the samples were dominated by smectite. Moreover the CEC values of clay minerals were consistent with results of XRD. The X-ray mineralogy indicated that the Vertisols and Aridisols of the study area had the same origin as that of the Gezira soils.

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

    Science.gov (United States)

    Churchman, G. Jock

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

  20. Clay-associated organic matter in kaolinitic and smectitic soils

    NARCIS (Netherlands)

    Wattel-Koekkoek, E.J.W.

    2002-01-01

    The primary source of soil organic matter is plant debris of all kinds, such as dead roots, leaves and branches that enter into the soil and are then biologically decomposed at variable rates. Organic matter has many different important functions on a local and global scale. Soil organic matter is a

  1. Effects of acid atmospheric deposition on the chemical composition of loess, clay and peat soils under forest in the Netherlands

    OpenAIRE

    Klap, J.M.; Vries, de, H.J.C.; Leeters, E.E.J.M.

    1999-01-01

    In addition to a survey of the soils under 150 forest stands on non-calcareous sandy soils, the chemical composition of the soils under 40 stands on non-calcareous loess soil, 30 stands on non-calcareous clay soils and 30 stands on oligotrophous peat soils have been examined, to assess the current status with repect to acidification and eutrophication, and the provide data for further studies. Only the clay soils are not yet seriously affected by the atmospheric inputs. The loess soils are ge...

  2. THE EFFECT OF REINFORCEMENT ON THE GBFS AND LIME TREATED MARINE CLAY FOR FOUNDATION SOIL BEDS

    Directory of Open Access Journals (Sweden)

    D. Koteswara Rao,

    2011-03-01

    Full Text Available India being peninsular country has large area coming under coastal region and also it has been the habitat for considerable percentage of population. The marine clays are generally found in the coastal region of West Bengal, Orissa, Andhra Pradesh, Tamilnadu, Kerala, Karnataka, Maharashtra and some parts of Gujarat. Marine or soft clays exists in these region are weak and deformative in nature. The present study deals with the strength characteristics of the marine clay collected from Kakinada Sea Port Ltd, Kakinada, A.P, India. The effect of lime on the strength characteristics of marine clay are studied in this investigation along with the reinforcement effect using geotextile as reinforcement and separator for the foundation soil bed.

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

    Science.gov (United States)

    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

  4. Sand and clay mineralogy of sal forest soils of the Doon Siwalik Himalayas

    Indian Academy of Sciences (India)

    Mukesh; R K Manhas; A K Tripathi; A K Raina; M K Gupta; S K Kamboj

    2011-02-01

    The peteromineralogical characterization of the soil was carried out for the 12 soil profiles exposed in the Shorea robusta dominated forests of the Siwalik forest division, Dehradun. The quartz was observed as the dominating light mineral fraction (64–80%) in all the profiles studied. Biotite, hornblende, zircon, tourmaline, rutile and opaques comprising of iron minerals constituted the heavy mineral fraction (20%). The mineralogy of both the sand and clay fractions revealed a mixed mineralogy. The clay minerals in the order of their dominance were vermiculite, illite, kaolinite and mixed layer minerals. The presence of vermiculite and illite in appreciable quantities indicates that these were synthesized from the K-rich soil solution, as orthoclase and micas were present in significant quantities in the sand minerals. The mineral suites identified in the study shows that the geological, climatological and topographical factors of the region collectively played a dominant role in their formation and transformation. After critical appraisal of the results, it may be deduced that the mineralogical composition, physicochemical properties and total elemental analysis of the soils do not show any deficiency of the bases and other plant nutrients in general. The inherent fertility of the soil is good as indicated by the sand and clay mineralogy of the soil and the biotite and feldspar together with the mica is an important source of nutrients for the vegetation in the soils of the Doon valley.

  5. The Influence of Clay on the Rate of Decay of Amino Acid Metabolites Synthesized in Soils during Decomposition of Cellulose

    DEFF Research Database (Denmark)

    Sørensen, Lasse Holst

    1975-01-01

    amounts of labelled amino acid C in the soils were proportional to their content of silt + clay. After 30 days of incubation labelled amino acid C remaining in the soil with the lowest content of silt + clay constituted 6 per cent of the carbon added in cellulose, as compared with 18 per cent in the soil...... increase in the CO2 evolution caused by the treatments in the different soils was, however, not related to the amount of silt + clay, and a high content of this material did not protect organic material against the effect of the treatments. is concluded that the silt + clay fraction ensures stabilization......14C-labelled cellulose was added to seven different soils containing silt + clay (particles <0.02 mm) in amounts which varied from 8 to 75 per cent. The cellulose was allowed to decompose, and the amounts of labelled C transformed into metabolites hydrolyzable into amino acids were determined. The...

  6. Water and solute transport in agricultural soils predicted by volumetric clay and silt contents

    DEFF Research Database (Denmark)

    Karup, Dan; Møldrup, Per; Paradelo Pérez, Marcos;

    2016-01-01

    -and-eighty-seven undisturbed soil columns 20 cm in height and 20 cm in diameter were sampled from six conventionally managed agricultural fields in Denmark. The soils exhibited a wide range in texture, with clay contents and organic carbon (OC) contents ranging from 0.03 to 0.41 kg kg-1 and 0.01 to 0.08 kg kg-1, respectively...... (particles ≤ 50 μm). The results showed that the mineral fines content was strongly correlated to functional soil structure and the derived tracer breakthrough curve (BTC), whereas the OC content appeared less important for the shape of the BTC. Organic carbon was believed to support the stability of the......Solute transport through the soil matrix is heterogeneous and greatly affected by soil texture, soil structure, and macropore networks. This study examined the relationship between tracer breakthrough characteristics, soil hydraulic properties, and basic soil properties. Hundred...

  7. Effect of clay minerals on the stabilization of black cotton and lateritic soils

    International Nuclear Information System (INIS)

    The problem associated with black cotton and lateritic soils because of the swelling-shrinkage property of their constituent clay minerals were investigated. Samples of black cotton lateritic soils were collected from different parts of Kenya. The samples were analysed for their mineral compositions and later treated with hydrated lime in order to eliminate the swelling shrinkage behaviour. The samples were subsequently tested for their engineering properties in a soil mechanics laboratory using shear box and Casagrande apparatus. It was found that the chemical treatment of the soils with hydrated lime removes their plastic property and improves their shear strength. (author)

  8. Effect of potassium on fixation of ammonium by clay minerals in different soil layers

    OpenAIRE

    , Agelda Ajazi; Liri Miho; Aida Bani; , Ardian Maçi

    2013-01-01

    In intensive agriculture systems, efficient nutrient use is necessary for high crop yields as well as for sustainable environment management. Fixation of NH4+ and K+ by soil clays affect N and K availability to plants. Latest studies indicates that non-exchangeable NH4+, may affect crop productivity and soil N dynamics more than previously thought. An incubation study with K2SO4 and NH4NO3 was conducted to evaluate NH4+ and K+ fixation in two southern Albanian soils. Soils contained significa...

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

    Science.gov (United States)

    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 ...

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

    Science.gov (United States)

    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...

  11. Effects of clay amendment on adsorption and desorption of copper in water repellent soils

    NARCIS (Netherlands)

    Xiong, X.; Stagnitti, F.; Allinson, G.; Turoczy, N.; Li, P.; LeBlanc, M.; Cann, M.A.; Doerr, S.H.; Steenhuis, M.M.; Parlange, J.Y.; Rooij, de G.; Ritsema, C.J.; Dekker, L.W.

    2005-01-01

    Copper is an important micronutrient and trace amounts are essential for crop growth. However, high concentrations of copper will produce toxic effects. Australia is increasingly developing production of crops in water repellent soils. Clay amendment, a common amelioration techniques used in Austral

  12. Peculiarities of strength and deformability properties of clay soils in districts of Western Siberia

    Science.gov (United States)

    Efimenko, Sergey; Efimenko, Vladimir; Sukhorukov, Alexey

    2016-01-01

    The article demonstrates the methodology of the substantiation of the calculated values of moisture, strength, and deformability characteristics of clay subgrade soils for the design of pavements by strength conditions in II, III, and IV road-climatic zones in West Siberia. The main purpose of the work is to ensure the quality of the design of roads in newly developed regions of Russia. To achieve this goal the following problems have been solved: the dislocation of boundary lines of road-climatic zones has been specified, zoning of the investigated territory for the design of roads has been detailed; regularities of changes in strength and deformability characteristics of clay subgrade soils of their moisture have been established; the territorial normalization of the calculated values of moisture, strength, and deformability of clay subgrade soils in relation to the allocated road districts has been carried out. Specification of boundary lines of road-climatic zones has been implemented on the basis of the taxonomic system "zone-subzone-road district". The calculated values of moisture, strength, and deformability characteristics of clay soils, established and differentiated according to road-climatic zones, will ensure the required level of the reliability of transport infrastructure facilities during the life cycle of roads.

  13. COMPARISON OF GLYPHOSATE PERSISTENCE IN CLAY SOIL ON NO-TILLED AND AUTUMN PLOUGHED PLOTS

    OpenAIRE

    Petruneva, Ekaterina

    2015-01-01

    The present work was based on the analysis of glyphosate concentrations in six soil layers after continuous multiple applications of herbicide products and various sampling times during the study period of 2010−2012, and aimed to contribute to a better recognition of the glyphosate persistence in clay soil. Two tillage methods (conventional tillage and no-till) were carried out in two replicates on the experimental field located in Jokioinen, South-Western Finland. This experiment was impo...

  14. Multisensor on-the-go mapping of readily dispersible clay, particle size and soil organic matter

    Science.gov (United States)

    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

  15. Theoretical Analysis of the Influence of the Thermal Diffusivity of Clay Soil on the Thermal Energy Distribution in Clay Soil of Abakaliki, Nigeria

    Directory of Open Access Journals (Sweden)

    E.I Ugwu

    2010-05-01

    Full Text Available The influence of the thermal diffusivity of clay soil on thermal energy distribution in clay soil was studied using one and two dimensioned heat equation, which was solved, by using separation of variables method. In the analysis, heat was assumed to be propagated along rectangular moldedclaywithlength(Lwith the width being considered negligible in the case of one dimension with different temperature ranging from 350 to 1290ºC within zero to one minute chosen where some parameters such as thermal diffusivity In the second case, a steady state heat flow was considered in two dimensions w ith the assumption that temperature distribution is constant. Different temperature ranging from 350 to 1290ºC within zero to one minute were chosen with some parameters such as thermal diffusivity, specific heat and m ass per unit length of the clay are specified. The variation of the thermal conductivity and diffusivity with temperature was analyzed while that of the energy flux, u(x,t variation with time for different chosen length were plotted Two dimensional thermal energy distribution viewed at different points was also considered using different values of therm al diffusivity respectively.

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

    Science.gov (United States)

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

    2014-05-01

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

  17. Distinguishing black carbon from biogenic humic substances in soil clay fractions

    Science.gov (United States)

    Laird, D.A.; Chappell, M.A.; Martens, D.A.; Wershaw, R. L.; Thompson, M.

    2008-01-01

    Most models of soil humic substances include a substantial component of aromatic C either as the backbone of humic heteropolymers or as a significant component of supramolecular aggregates of degraded biopolymers. We physically separated coarse (0.2-2.0????m e.s.d.), medium (0.02-0.2????m e.s.d.), and fine (> 0.02????m e.s.d.) clay subfractions from three Midwestern soils and characterized the organic material associated with these subfractions using 13C-CPMAS-NMR, DTG, SEM-EDX, incubations, and radiocarbon age. Most of the C in the coarse clay subfraction was present as discrete particles (0.2-5????m as seen in SEM images) of black carbon (BC) and consisted of approximately 60% aromatic C, with the remainder being a mixture of aliphatic, anomeric and carboxylic C. We hypothesize that BC particles were originally charcoal formed during prairie fires. As the BC particles aged in soil their surfaces were oxidized to form carboxylic groups and anomeric and aliphatic C accumulated in the BC particles either by adsorption of dissolved biogenic compounds from the soil solution or by direct deposition of biogenic materials from microbes living within the BC particles. The biogenic soil organic matter was physically separated with the medium and fine clay subfractions and was dominated by aliphatic, anomeric, and carboxylic C. The results indicate that the biogenic humic materials in our soils have little aromatic C, which is inconsistent with the traditional heteropolymer model of humic substances.

  18. Assessment of fate of thiodicarb pesticide in sandy clay loam soil

    International Nuclear Information System (INIS)

    in present study the fate of thiodicarb pesticide in sandy clay loam soil was investigated through its adsorption and leaching using hplc. Experimental results revealed that thiodicarb follows first order kinetic with rate constant value of 0.711 h-1 and equilibrium study showed that freundlich model was best fitted with multilayer adsorption capacity 3.749 mol/g and adsorption intensity 1.009. Therefore, adsorption of thiodicarb was multilayer, reversible and non-ideal. Leaching study has indicated intermediate mobility of thiodicarb with water due to its solubility, while field study showed the non-leacher nature. However both adsorption and leaching were heavily affected by soil characteristics. As the soil taken was sandy clay loam hence due to clay texture adsorption was higher because of vacant sites existing and greater surface area. For this the pesticide has remained adsorbed in above 20 cm soil layer as clearly seen from field study, minor amount was recorded in third layer of soil having 21-30 cm depth. The leached amount of thiodicarb in first and last part of water was 1.075 and 0.003 ng/ mu l. The general trend observed for adsorption in column and field soil was decreased downwards from 2.027 to 0.618 and 5.079 to 0.009 ng/mu l. (author)

  19. Assessment of Fate of Thiodicarb Pesticide in Sandy Clay Loam Soil

    Directory of Open Access Journals (Sweden)

    M. A. Bajeer

    2015-06-01

    Full Text Available In present study the fate of thiodicarb pesticide in sandy clay loam soil was investigated through its adsorption and leaching using HPLC. Experimental results revealed that thiodicarb follows first order kinetic with rate constant value of 0.711 h-1 and equilibrium study showed that Freundlich model was best fitted with multilayer adsorption capacity 3.749 mol/g and adsorption intensity 1.009. Therefore, adsorption of thiodicarb was multilayer, reversible and non-ideal. Leaching study has indicated intermediate mobility of thiodicarb with water due to its solubility, while field study showed the non-leacher nature. However both adsorption and leaching were heavily affected by soil characteristics. As the soil taken was sandy clay loam hence due to clay texture adsorption was higher because of vacant sites existing and greater surface area. For this the pesticide has remained adsorbed in above 20 cm soil layer as clearly seen from field study, minor amount was recorded in third layer of soil having 21-30 cm depth. The leached amount of thiodicarb in first and last part of water was 1.075 and 0.003 ng/µl. The general trend observed for adsorption in column and field soil was decreased downwards from 2.027 to 0.618 and 5.079 to 0.009 ng/µl.

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

    Science.gov (United States)

    Taghipour, Marzieh; Jalali, Mohsen

    2015-10-30

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

  1. Competitive sorption between glyphosphate and inorganic phosphate on clay minerals and low organic matter soils

    International Nuclear Information System (INIS)

    Inorganic phosphate may influence the adsorption of glyphosate to soil surface sites. It has been postulated that glyphosphate sorption is dominated by the phosphoric acid moiety, therefore, inorganic phosphate could compete with glyphosate for surface sorption sites. Sorption of glyphosate is examined in low organic carbon systems where clay minerals dominate the available adsorption sites using 32P-labeled phosphate and 14C-labeled glyphosate to track sorption. Glyphosate sorption was found to be strongly dependent on phosphate additions. Isotherms were generally of the L type, which is consistent with a limited number of surface sites. Most sorption on whole soils could be accounted for by sorption observed on model clays of the same mineral type as found in the soils. (author)

  2. Irrigation with saline-sodic water: effects on two clay soils

    OpenAIRE

    Giovanna Cucci; Giovanni Lacolla

    2013-01-01

    The results of a 4-year experiment aimed at evaluating the effect of irrigation with saline-sodic water on the soil are reported. The research was carried out at the Campus of the Agricultural Faculty of Bari University (Italy) on 2 clay soils (Bologna – T1 and Locorotondo – T2). The soils were cropped to borlotto bean (Phaseolus vulgaris L.), capsicum (Capsicum annuum L.), sunflower (Helianthus annuus L.), wheat (Triticum durum Desf) grown in succession; the crops were irrigated with 9 salin...

  3. Lead pollution of soil and groundwater in clay-pigeon shooting ranges

    International Nuclear Information System (INIS)

    Within the framework of the exemplary investigation of soil and groundwater pollution with lead on clay-pigeon shooting ranges, three facilities were sampled. The analyses for depth distribution in the main area of the ammunition deposition showed that the dissolved lead amounts are as a rule smaller than the limiting value of the Sewage Sludge Regulation (100 mg/kg). In two groundwater samples, no lead could be found. Considerable amounts of small lead balls are found on the soil surface, but only a very small part appears to be washed out and adsorbed by the soil matrix. (orig.)

  4. Swelling clays and salt-affected soils : demixing of Na / Ca clays as the rationale for discouraging the use of sodium adsorption ratio (SAR)

    OpenAIRE

    Guilhem Bourrie

    2014-01-01

    Sodium adsorption ratio SAR defined as SAR = (Na) / V w(Ca+Mg)/2 here concentrations of cations in solution are expressed in meq/L has long been considered as correlated to exchangeable sodium percentage (ESP) on clay minerals or soil exchange complex, and as the key concept to explain swelling of clay minerals and the difficulties of reclaiming salt-affected soils. Though its basis is empirical, it was alleged to be theoretically justified on the basis of ion exchange, derived from the Gapo...

  5. Removal of MTBE from a clay soil using electrokinetic technique.

    Science.gov (United States)

    Estabragh, A R; Bordbar, A T; Ghaziani, F; Javadi, A A

    2016-01-01

    Remediation of a soil contaminated with methyl tertiary butyl ether (MTBE) was studied by using the electrokinetic technique. A series of experimental tests were carried out on contaminated soil in an electro-osmotic apparatus at different applied gradients of voltage and time. The tests were conducted with distilled water and ethylenediaminetetra acetic acid (EDTA) solution as electrolyte. During each test the values of pH at anode and cathode reservoirs and also the discharge from cathode were measured. At the end of each test a number of soil samples were extracted from the middle of the soil at different distances from the anode and the removal of contaminant was measured by a gas chromatography apparatus. The results indicate that with EDTA as electrolyte the highest efficiency for removal of MTBE is achieved with 2.0 V/cm gradient and in the duration of 14 days. In addition, EDTA causes the values of pH to increase and decrease in the cathode and anode reservoirs, respectively. It also decreases the effluent and electro-osmotic permeability in comparison with distilled water. Experimental data were analysed by ANOVA and t-test methods. These statistical analyses showed significant difference (at 5% level) between the reference and other tests. PMID:26787321

  6. Short-Term Effects of Land Leveling on Irrigation-Related Some Soil Properties in a Clay Loam Soil

    OpenAIRE

    Öztekin, Tekin

    2013-01-01

    There are few studies conducted on the short-term effects of land leveling on soil water holding capacity. The objectives of this study were to analyze the short-term effects of land leveling on the magnitudes, variances, spatial variability, and distributions of surface (0–20 cm) and subsurface (20–40 cm) soil properties of bulk density, field capacity, permanent wilting point, water holding capacity and particle size fractions. The study was conducted in a 1.2 ha field with clay loam soil l...

  7. Competitive adsorption of 90Sr on soil sediments, pure clay phases and feldspar minerals

    International Nuclear Information System (INIS)

    Study of the adsorption of 90Sr by a soil sediment, mineralogically pure clay phases and feldspar minerals as a function of ionic composition of Ca, Mg and Na has been conducted. It is shown that a theoretical slope value of -1 for a pure ion-exchange mechanism of strontium adsorption onto Ca-saturated clay is predicted. Experimentally determined slopes represent an average of adsorption on several different mineral surfaces having different relative affinities for strontium, calcium and magnesium. Strontium was found to be adsorbed to ion-exchange sites and calcium and magnesium cations were observed to be effective competitors for these sites. Pure clay minerals yielded adsorption coefficients from equations with slopes of -10. (author)

  8. Influence of crop residues on trifluralin mineralization in a silty clay loam soil.

    Science.gov (United States)

    Farenhorst, Annemieke

    2007-01-01

    Trifluralin is typically applied onto crop residues (trash, stubble) at the soil surface, or onto the bare soil surface after the incorporation of crop residues into the soil. The objective of this study was to quantify the effect of the type and amount of crop residues in soil on trifluralin mineralization in a Wellwood silty clay loam soil. Leaves and stubble of Potato (Solanum tuberosum) (P); Canola (Brassica napus) (C), Wheat (Triticum aestivum) (W), Oats (Avena sativa), (O), and Alfalfa (Medicago sativa) (A) were added to soil microcosms at rates of 2%, 4%, 8% and 16% of the total soil weight (25 g). The type and amount of crop residues in soil had little influence on the trifluralin first-order mineralization rate constant, which ranged from 3.57E-03 day(-1) in soil with 16% A to 2.89E-02 day(-1) in soil with 8% W. The cumulative trifluralin mineralization at 113 days ranged from 1.15% in soil with 16% P to 3.21% in soil with 4% C, again demonstrating that the observed differences across the treatments are not of agronomic or environmental importance. PMID:17454379

  9. Time and frequency GPR waveforms analysis for clay content evaluation in soils

    Science.gov (United States)

    Tosti, F.; Patriarca, C.

    2012-04-01

    The mechanical behaviour of soils is partly affected by their clay content, which exerts some considerable effects in many applications in the fields of civil engineering, geology and environmental engineering. This study focuses on pavement engineering, but the approach can be extended to other purposes. The presence of clay in the bearing structural layers of pavements frequently causes damages and defects, such as transversal and longitudinal cracks, deformations and rutting. Consequently, the road safety and operability decrease, while the expected number of accidents increases. In this work Ground Penetrating Radar (GPR) laboratory inspections are carried out in order to predict the presence of clay in pavement structural layers. Data are post-processed in the frequency domain, according to the Rayleigh scattering method based on the Fresnel theory. This new technique can be supported by other survey methods, improving the quality of the results. Analysis are carried out using two different GPR systems. A Radar is used with ground-coupled antennae in a bistatic configuration and common offset; the transmitter and receiver are linked by optic fiber electronic modules and operate at 500 MHz central frequency. The received signal is sampled in the time domain at time steps of 7.8125 x 10-2 ns. A Vector Network Analyzer (VNA) acquires ultra-wide band data in a bandwidth from 500 MHz to 3000 MHz. The signal is sampled in the frequency domain with approximately 1.56 MHz frequency steps. A double-ridged broadband horn antenna is connected via a high-quality coaxial cable to the VNA pulse generator and illuminates the analyzed target in a monostatic off-ground configuration. The experimental setting required the use of road material, typically employed for sub-grade and sub-base layers. Three kind of soils, classified as A1, A2, A3 by AASHTO are used and adequately compacted in electrically and hydraulically isolated boxes. Bentonite clay is gradually added from 2% to

  10. Sorption of radioiodine on organic rich soil, clay minerals and alumina

    International Nuclear Information System (INIS)

    Batch method was used to investigate the sorption behavior of radioiodine on organic rich soil, alumina, chlorite-illite clay mixture and bentonite. 131 I was used as tracer. The grain sizes of the samples used were all below 38μm. A rather slow kinetics was observed for the adsorption of radioiodine on organic rich soil. The distribution ratio increased with increasing solution/solid (V/m) ratio, and the contact time. The pH of the synthetic groundwater did not change the distribution ratio appreciably. The soil biomass however, showed a striking effect on the adsorption of radioiodine. Among the clay minerals, the highest distribution ratio value was found for chlorite-illite clay mixture. All the values were however well below those of the organic rich soil. The sorption data were fitted to Freundlich and Dubinin-Radushkevich type isotherms. Mean energies of adsorption, as well as the affinity ratios of the sorption sites to iodine and chlorine were calculated. (author) 13 refs.; 6 figs.; 6 tabs

  11. Comparative adsorption of sup 90 Sr on soil sediments, pure clay phases and feldspar minerals

    International Nuclear Information System (INIS)

    Laboratory batch experiments were conducted to determine the adsorption of 90 Sr by a soil sediment, mineralogically pure clay phases (vermiculites, smectites and illites) and feldspar minerals (adesine, albite, microcline and oligoclase) as a function of ionic composition. The clay minerals were present at different proportion in the soil sediment. The important adsorbing phases and the adsorption mechanism(s) can be determined from the studies. Twenty two stock solutions were prepared with concentrations of the major cations Ca, Mg and Na and were varied from 0.0 to 0.00312 M, 0.0 to 0.00165 M, and 0.0 to 0.00312 M, respectively. The experiments yielded adsorption coefficient values K sub d that could be described by equations. Theoretical slope value -1 for pure ion-exchange mechanism of strontium adsorption onto Ca-saturated clay was described. The slopes obtained in the experiments represented an average of adsorption on several different mineral surfaces having different relative affinities for strontium, calcium and magnesium. Experiment results showed that strontium was adsorbed to ion-exchange sites and that calcium and magnesium cations were effective competitors for these sites. Pure clay minerals yielded adsorption coefficients that could be described by equations slopes -1.0 similar to the theoretical value. The feldspar minerals yielded slope ranges from -072 to -1.13, and the sediments slope value of -0.81. These suggest that ion-exchange was the dominant adsorption mechanism for strontium

  12. Influence of Amang (Tin Tailing) on Geotechnical Properties of Clay Soil

    International Nuclear Information System (INIS)

    Amang or tin tailing is commonly found in the vicinity of disused mining area and responsible in downgrading the water quality, landscape and mechanical behaviour of soils. It was generated from extraction process of separating valuable metal from particular ore. This paper presents the geotechnical characteristics of amang-contaminated clay soil. The geotechnical properties of uncontaminated soils were studied in order to compare to that of amang contaminated soils. The base soil used in this study represents completely weathered horizon of meta sedimentary rock. Meanwhile, tin tailing sample was taken from the disused mine at Sungai Lembing, Pahang. The geotechnical characterisations of base soil and contaminated soils were determined based on consistency index, compaction behaviour, hydraulic conductivity and undrained shear strength (UU tests). Contaminated soil samples were prepared by adding 5, 10 and 20 % of tailing, based on dry weigh of the studied base soil. The results from the particle size distribution analysis showed that residual soil from meta sedimentary rock comprised 42.6 % clay, 32.2 % silt and 25.2 % sand whilst tailing was dominated by 98 % of sand fraction. XRD analysis indicated the presence of quartz, kaolinite and muscovite minerals in the studied soil. The specific gravity of soil used is 2.67 and the pH is 3.88. Tailing found to have higher specific gravity of 3.37. The consistency index of contaminated soils showed that liquid limit, wL and plastic limit, wP decreased with the increase in the percentage of tailing added to the soil samples. The value of maximum dry density, ρ dry max increased while optimum moisture content decreased due to the increase in tailing content in soil sample. The permeability of contaminated soil also increased with the increase in tailing contents ranged from 19.8 cm/ hr to 23.8 cm/ hr. The undrained shear strength, Cu, of contaminated soil decreased from 646 kPa (5 % of tailing) to 312 kPa (20 % of

  13. Nonlinear soil parameter effects on dynamic embedment of offshore pipeline on soft clay

    Directory of Open Access Journals (Sweden)

    Yu Su Young

    2015-06-01

    Full Text Available In this paper, the effects of nonlinear soft clay on dynamic embedment of offshore pipeline were investigated. Seabed embedment by pipe-soil interactions has impacts on the structural boundary conditions for various subsea structures such as pipeline, riser, pile, and many other systems. A number of studies have been performed to estimate real soil behavior, but their estimation of seabed embedment has not been fully identified and there are still many uncertainties. In this regards, comparison of embedment between field survey and existing empirical models has been performed to identify uncertainties and investigate the effect of nonlinear soil parameter on dynamic embedment. From the comparison, it is found that the dynamic embedment with installation effects based on nonlinear soil model have an influence on seabed embedment. Therefore, the pipe embedment under dynamic condition by nonlinear parameters of soil models was investigated by Dynamic Embedment Factor (DEF concept, which is defined as the ratio of the dynamic and static embedment of pipeline, in order to overcome the gap between field embedment and currently used empirical and numerical formula. Although DEF through various researches is suggested, its range is too wide and it does not consider dynamic laying effect. It is difficult to find critical parameters that are affecting to the embedment result. Therefore, the study on dynamic embedment factor by soft clay parameters of nonlinear soil model was conducted and the sensitivity analyses about parameters of nonlinear soil model were performed as well. The tendency on dynamic embedment factor was found by conducting numerical analyses using OrcaFlex software. It is found that DEF was influenced by shear strength gradient than other factors. The obtained results will be useful to understand the pipe embedment on soft clay seabed for applying offshore pipeline designs such as on-bottom stability and free span analyses.

  14. Nonlinear soil parameter effects on dynamic embedment of offshore pipeline on soft clay

    Science.gov (United States)

    Yu, Su Young; Choi, Han Suk; Lee, Seung Keon; Park, Kyu-Sik; Kim, Do Kyun

    2015-06-01

    In this paper, the effects of nonlinear soft clay on dynamic embedment of offshore pipeline were investigated. Seabed embedment by pipe-soil interactions has impacts on the structural boundary conditions for various subsea structures such as pipeline, riser, pile, and many other systems. A number of studies have been performed to estimate real soil behavior, but their estimation of seabed embedment has not been fully identified and there are still many uncertainties. In this regards, comparison of embedment between field survey and existing empirical models has been performed to identify uncertainties and investigate the effect of nonlinear soil parameter on dynamic embedment. From the comparison, it is found that the dynamic embedment with installation effects based on nonlinear soil model have an influence on seabed embedment. Therefore, the pipe embedment under dynamic condition by nonlinear parameters of soil models was investigated by Dynamic Embedment Factor (DEF) concept, which is defined as the ratio of the dynamic and static embedment of pipeline, in order to overcome the gap between field embedment and currently used empirical and numerical formula. Although DEF through various researches is suggested, its range is too wide and it does not consider dynamic laying effect. It is difficult to find critical parameters that are affecting to the embedment result. Therefore, the study on dynamic embedment factor by soft clay parameters of nonlinear soil model was conducted and the sensitivity analyses about parameters of nonlinear soil model were performed as well. The tendency on dynamic embedment factor was found by conducting numerical analyses using OrcaFlex software. It is found that DEF was influenced by shear strength gradient than other factors. The obtained results will be useful to understand the pipe embedment on soft clay seabed for applying offshore pipeline designs such as on-bottom stability and free span analyses.

  15. Soil moisture distribution over time in a clay loam soil in Kosovo

    OpenAIRE

    Abdullah Nishori; Besnik Gjongecaj; Deme Abazi

    2013-01-01

    Studying the soil moisture distribution over time in a given soil profile is the object of the present study. The way the soil moisture gets distributed over soil profile depends particularly on the soil texture and on the soil suction gradients developed. However, it changes continuously over time for a given soil depth. The method of determining the soil moisture distribution over time is based on the measuring of soil moisture suctions developed and the soil moisture contents in various ti...

  16. Traditional Underground Grain Storage in Clay Soils in Sudan Improved by Recent Innovations

    Directory of Open Access Journals (Sweden)

    Abdalla, AT.

    2002-01-01

    Full Text Available In the central clay plain of the Sudan, traditional subsistence farmers and small farmers that also produce for local markets want to keep the region near food self-sufficiency. They combine annual production of sorghum with underground pit storage of part of the harvest. With increasing climate variability this food security is coming more and more under pressure. Farmers recently experimented with pit innovations that would allow storage for more than one season. These innovations were quantified and further improvements were suggested. It was found that in the most abundantly occurring cracking clay soils, wide shallow pits, using thick chaff linings, with wider above ground soil caps, are most suitable for longer term storage.

  17. Enrichment of trace elements in the clay size fraction of mining soils.

    Science.gov (United States)

    Gomes, Patrícia; Valente, Teresa; Braga, M Amália Sequeira; Grande, J A; de la Torre, M L

    2016-04-01

    Reactive waste dumps with sulfide minerals promote acid mine drainage (AMD), which results in water and soil contamination by metals and metalloids. In these systems, contamination is regulated by many factors, such as mineralogical composition of soil and the presence of sorption sites on specific mineral phases. So, the present study dedicates itself to understanding the distribution of trace elements in different size fractions (clay size fraction. Hence, the higher degree of contamination by toxic elements, especially arsenic in Penedono as well as the role of clay minerals, jarosite, and goethite in retaining trace elements has management implications. Such information must be carefully thought in the rehabilitation projects to be planned for both waste dumps. PMID:25712883

  18. Bulk and clay mineral composition indicate origin of terra rossa soils in Western Herzegovina

    OpenAIRE

    Durn, Goran; Ćorić, Radica; Tadej, Neven; Barudžija, Uroš; Rubinić, Vedran; Husnjak, Stjepan

    2014-01-01

    The B horizons of terra rossa soils developed on three different carbonate lithologies having variable insoluble residue contents were studied in Western Herzegovina. Comparison of  their composition and properties illustrates to what extent mineral (especially clay mineral assemblage) and particle size composition of those horizons and the insoluble residue of the underlying carbonate rocks can be used as indicators of the polygenetic nature of terra rossa in this region. Terra rossa B horiz...

  19. The role of clay minerals on the hardsetting properties of soils in the Carnarvon horticultural district of Western Australia

    International Nuclear Information System (INIS)

    Full text: We investigated the role of clay minerals on the hardsetting properties of soils used for intensive irrigated horticulture in the Carnarvon horticultural district of Western Australia. Hardsetting soils break down when wetted due to a combination of slaking and dispersion processes, resulting in a structureless mass of soil when dry. Soil samples were studied from several horizons from six profiles with hardsetting problems. On bulk samples, we measured the cation exchange capacity (CEC) and following treatment with sodium (Na), measured the tensile strength of (Na saturated) remoulded cores. On clay separates we measured the clay mineralogy using X-ray . diffraction (XRD) analysis and CEC by X-ray fluorescence (XRF) analysis after barium (Ba) saturation. Samples were also investigated using transmission electron microscopy (TEM). The tensile strength of the Na saturated remoulded cores was highly correlated (p ≤ 0.001) to both clay % and CEC of the soil. Lugo (1975) working with dried briquettes of soil materials produced similar results, and demonstrated that the increase in tensile strength adversely affected the stand of plants. When the tensile strength of the remoulded cores was compared to the CEC of the clay fractions, the soil clays with higher CEC had greater tensile strength than soils lower in CEC (p=0.09). Initial qualitative XRD results using the SIROQUANT method indicated that the soil clays mainly consisted of kaolinite with some illite, but very little smectite content. However the measured CEC's (by Ba saturation) were higher than expected and could not be explained on the basis of the illite and kaolinite contents. It was therefore inferred that interstratified smectite was also present. Using the proprietary software 'Traces', and a Pseudo-Voigt peak-shape algorithm, each XRD pattern was fitted with calculated peaks for the clay minerals present. Comparison with calculated patterns for interstratified illite/smectite (I/S) using

  20. Short-term effects of land leveling on irrigation-related some soil properties in a clay loam soil.

    Science.gov (United States)

    Öztekin, Tekin

    2013-01-01

    There are few studies conducted on the short-term effects of land leveling on soil water holding capacity. The objectives of this study were to analyze the short-term effects of land leveling on the magnitudes, variances, spatial variability, and distributions of surface (0-20 cm) and subsurface (20-40 cm) soil properties of bulk density, field capacity, permanent wilting point, water holding capacity and particle size fractions. The study was conducted in a 1.2 ha field with clay loam soil located on the low terraces of Yesilirmak River, Tokat, Turkey. According to the paired t-test results, water holding capacity, and bulk density significantly increased, while permanent wilting point (P ≤ 0.001) and field capacity (P ≤ 0.05) significantly decreased for surface soil due to land leveling. The reasons for the increases in WHC values in both cut and fill areas (29%, and 12%, resp.) of surface soil are look like the much more decreases in PWP values than those of FC values and the increases in BD values. The moderate positive linear relationship between the surface soil clay contents and cut depths through cut areas (r = 0.64) was also determined in this study. PMID:23843730

  1. Evaluation of clay content in soils for pavement engineering applications using GPR

    Science.gov (United States)

    Tosti, Fabio; Patriarca, Claudio; Benedetto, Andrea; Slob, Evert C.; Lambot, Sébastien

    2013-04-01

    Clay content significantly influences the mechanical behavior of soils, thereby playing an important role in many fields of applications such as civil engineering, geology and agriculture. In the area of pavement engineering, clay content in structural bearing courses of pavement frequently causes damages and defects, such as transversal and longitudinal cracks, or other faults. The main consequence is a lowering of both the road safety and operability, with the number of expected accidents increasing. In this study, ground-penetrating radar (GPR) laboratory tests were carried out to predict the clay amount in pavement structural layers under different clay and moisture conditions. GPR data processing is performed using two different methods. The first method is based on the Fresnel theory and focuses on the Rayleigh scattering of the radar waves. The approach is based on a different scattering of the various components of the frequency spectrum, mostly depending on both the soil texture and variation in soil moisture content. For the application of this method, we used a pulse radar with ground-coupled, 500 MHz centre-frequency antennas in a common offset, bistatic configuration. The transmitter and receiver were linked by optic fiber electronic modules. The second method is based on full-waveform inversion of the ultra wideband radar data. In particular, a specific radar-antenna electromagnetic model is used to filter out antenna effects and antenna-medium interactions from the raw radar data and retrieve the response of the soil only, expressed in terms of a layered medium Green's function. To estimate the medium geometrical and electrical values, an optimization inverse problem is formulated. For the application of that second method, we used a vector network analyzer (VNA) as continuous-wave stepped-frequency radar system to acquire data in the 500-3000 MHz frequency range. A doubled-ridged broadband horn antenna operating in far-field conditions was used as

  2. IMPACT OF POLLUTION ON THE CLAY MINERALOGICAL COMPOSITION OF SOME SOILS FROM ZLATNA AREA (ROMANIA

    Directory of Open Access Journals (Sweden)

    C. Craciun

    2008-10-01

    Full Text Available Zlatna area is a high polluted zone with heavy metals due to industrial activity (extraction and processing of non-ferrous area. In spite of the fact that industrial activity was stoped for 2-3 years, the effect of pollution are still obvious. The aim of this paper is to make evident some aspects concerning the impact of pollution on the mineralogical composition of the clay fraction (below 2μ from some soils belonging to dystric cambisol and luvisol type. From the chemical point of view, the effect of pollution is the acidifiation and depletion of bases, reflected by the decrease of values of indices which express soil reaction (pH and soil exchange properties, especially in the surface horizon. From mineralogical point of view, the acidifiation determines a strong alteration of primary minerals (micas and feldspars and just of secondary minerals (illite, evolution beeing towards hydroxy interlayered minerals (intergrade and kaolinite. As result of this alteration the content of kaolinite increases, achiving a double content in the surface horizon of some polluted soils. Sometimes kaolinite becomes the dominant mineral in the clay fraction of some strong polluted soil.

  3. The origin and early genesis of clay bands in youthful sandy soils along lake Michigan, U.S.A.

    Science.gov (United States)

    Berg, R.C.

    1984-01-01

    A beach ridge and dune complex with good radiocarbon control sampling the last 3500 radiocarbon years B.P. provides new insights on the early genesis of clay bands in sandy soils. Soil profiles were sampled by age groups, described in the field, and then subjected to laboratory analyses for particle-size distribution, pH, organic carbon, carbonate minerals, and extractable iron and manganese. This study suggests that small increases in pH, brought about by small increases in carbonate content within the soil profile, are responsible for flocculating small amounts of illuviated clay. This process, along with a transition to a greater hydraulic conductivity with soil depth due to coarser textures in any given profile, partly explains the existence and possible reason for the initiation of illuvial zones and eventually for clay-band horizons. A pronounced increase in the thickness of incipient clay-band horizons in soils older than 2300 years appears due to finer textures in the parent materials than are present in younger soils. Because of slightly reduced porosity and lower permeability, carbonates and a high pH are retained in both illuvial and eluvial horizons of some of these older soils. In addition, only in those profiles older than 2300 years do clay and iron oxide concentrations coincide and is there some suggestion of greater amounts of extractable manganese in horizons of minimum iron and clay. A pronounced segregation of clay-iron bands is not apparent at the study area but should occur in future years as additional amounts of iron and clay are deposited. ?? 1984.

  4. Effect of Polypropylene Fibers, Lime and Ceramic Additives on the Compressibility of Silty-Clay Soil

    Directory of Open Access Journals (Sweden)

    Hiba D. Saleem

    2016-07-01

    Full Text Available Soil stabilization is widely used by geotechnical engineers in the world to increase soil strength, soil compressibility and reduce the permeability. The main aim of this paper is to investigate the effect of adding different materials to the silty clayey soil (i.e. polypropylene fibers, lime and ceramic and to figure out how the compressibility behave under mixture soil and these stabilized material at different percent (investigation their effect on the value of settlement. Silty clay soil it is used in this research in the geotechnical laboratories of the University of Wasit and the samples of soil are subjected to two main stress level using one-dimensional compression apparatus (i.e. 40KP and 80 KPa for both untreated and treated (stabilized soil with additives. A total of 48 hours of loading time is used and conventional reading rate for one-dimensional compression test is followed. Two main percentages (i.e. 1.5% and 3.5% from the total weight of soil specimens and they had been mixed with soil for 30 min using electrical mixer to attain a uniform soil-material mixture prior to consolidation cell preparation and loading procedure. The results of the experimental tests show that the compressibility of the treated soil specimens were decrease when the soil stabilized with these material and minimum compressibility was obtained when the polypropylene fibers at 1.5 % percentages is used at the higher stress level and 3.5% of lime-stabilized at low stress level.

  5. THE EFFECT OF MIXING WITH ORGANIC SOIL ON CHANGES IN SOME PHYSICAL PROPERTIES OF A COMPACTED CLAY LOAM SOIL

    Directory of Open Access Journals (Sweden)

    Abdullah BARAN

    1996-01-01

    Full Text Available In this research, the effect of organic soil on changes in total pore space, aeration porosity, available water content and hydraulic conductivity of a compacted clay loam were investigated. By adding organic soil at rates of 0 %, 1 %, 2 % and 4 % to soil, mixtures were compacted at compaction levels of 0 kg/cm2, 0.21 kg/cm2, 1.98 kg/cm2 and 3.95 kg/cm2 Some physical properties of compacted soil were determined. Compaction decreased total pore space, areation porosity, available water content and hydraulic conductivity, but in samples with the mixing rate of 4 %, all properties inspected were affected positively in all compaction levels, except available water content

  6. 222Rn and CO2 soil-gas geochemical characterization of thermally altered clays at Orciatico (Tuscany, Central Italy)

    International Nuclear Information System (INIS)

    Research highlights: → Soil-gas technique is applied to study gas permeability of Orciatico clay units. → Clay permeability depends on thermal and mechanical alteration degree. → Soil-gas distributions are due to shallow fracturing of clays. → Rn and CO2 soil-gas anomalies highlight secondary permeability in clay sequence. → Soil-gas results are supported by detailed geoelectrical surveys. - Abstract: The physical properties of clay allow argillaceous formations to be considered geological barriers to radionuclide migration in high-level radioactive-waste isolation systems. As laboratory simulations are short term and numerical models always involve assumptions and simplifications of the natural system, natural analogues are extremely attractive surrogates for the study of long-term isolation. The clays of the Orciatico area (Tuscany, Central Italy), which were thermally altered via the intrusion of an alkali-trachyte laccolith, represent an interesting natural model of a heat source which acted on argillaceous materials. The study of this natural analogue was performed through detailed geoelectrical and soil-gas surveys to define both the geometry of the intrusive body and the gas permeability of a clay unit characterized by different degrees of thermal alteration. The results of this study show that gas permeability is increased in the clay sequences subjected to greater heat input from the emplacement of the Orciatico intrusion, despite the lack of apparent mineral and geotechnical variations. These results, which take into consideration long time periods in a natural, large-scale geological system, may have important implications for the long-term safety of underground storage of nuclear waste in clay formations.

  7. Availability and bio-accessibility of metals in the clay fraction of urban soils of Sevilla

    International Nuclear Information System (INIS)

    The availability of Cd, Cr, Cu, Ni, Mn, Pb and Zn present in the finest size particles of urban soils is studied by comparing the concentrations in the clay fraction with those extracted from the whole soil by either single-extraction or sequential extraction method. Many metals are preferentially present in the finest particles as compared to coarser fractions. This is true for most metals studied, except Mn and, perhaps, Cd. Those metals present in the clay fraction are often in easily bio-accessible forms, especially Cu, Pb and Zn. The results suggest that bio-accessible forms of these three metals are distributed among the three sequential fractions, and even the fraction considered as 'residual' is also bio-accessible to a significant extent. The statistical analysis shows some distinctions among metals that are compared to the 'urban', 'natural', or intermediate behaviour of the various metals as proposed earlier in the literature. - The recreational use of most urban soils causes that the availability of metals in the finest soil particles must be studied and eventually controlled

  8. Determination of essential and toxic elements in clay soil commonly consumed by pregnant women in Tanzania

    International Nuclear Information System (INIS)

    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. - Highlights: • We assessed exposure of heavy metals to pregnant mothers who consume geophagic soil. • We analyzed 100 samples of soil originated in Tanzania. • The technique used was energy dispersive X-ray fluorescent. • Essential and toxic elements were detected in concentrations above WHO limits. • Hence, geophagy is exposing pregnant mothers and their children to metal toxicity

  9. Dissolution kinetics of soil clays in sulfuric acid solutions: Ionic strength and temperature effects

    International Nuclear Information System (INIS)

    Highlights: • Acid sulfate dissolution of clay-rich sediments from inland acid sulfate site in flow-through reactor experiments at pH 1–4. • Enhanced Al and K release at the higher ionic strength of solutions compared to the lower ionic strength. • Acid neutralization capacity (ANC) of 1.11 kg H2SO4/tonne clay-rich sediment/day was provided at pH 1, 25 °C. • ANC provided at 45 °C by the same amount of clay-rich sediment was more than three times higher than the ANC at 25 °C. - Abstract: Significant amounts of sulfuric acid (H2SO4) rich saline water can be produced by the oxidation of sulfide minerals contained in inland acid sulfate soils (IASS). In the absence of carbonate minerals, the dissolution of phyllosilicate minerals is one of very few processes that can provide long-term acid neutralisation. It is therefore important to understand the acid dissolution behavior of naturally occurring clay minerals from IASS under saline–acidic solutions. The objective of this study was to investigate the dissolution of a natural clay-rich sample under saline–acidic conditions (pH 1–4; ionic strengths = 0.01 and 0.25 M; 25 °C) and over a range of temperatures (25–45 °C; pH 1 and pH 4). The clay-rich sample referred to as Bottle Bend clay (BB clay) used was from an IASS (Bottle Bend lagoon) in south-western New South Wales (Australia) and contained smectite (40%), illite (27%), kaolinite (26%) and quartz (6%). Acid dissolution of the BB clay was initially rapid, as indicated by the fast release of cations (Si, Al, K, Fe, Mg). Relatively higher Al (pH 4) and K (pH 2–4) release was obtained from BB clay dissolution in higher ionic strength solutions compared to the lower ionic strength solutions. The steady state dissolution rate (as determined from Si, Al and Fe release rates; RSi, RAl, RFe) increased with decreasing solution pH and increasing temperature. For example, the highest log RSi value was obtained at pH 1 and 45 °C (−9.07 mol g−1 s−1

  10. Soil-Structural Stability as Affected by Clay Mineralogy, Soil Texture and Polyacrylamide Application

    Science.gov (United States)

    Soil-structural stability (expressed in terms of aggregate stability and pore size distribution) depends on (i) soil inherent properties, (ii) extrinsic condition prevailing in the soil that may vary temporally and spatially, and (iii) addition of soil amendments. Different soil management practices...

  11. Changes in the sorption-desorption of fungicides over time in an amended sandy clay loam soil under laboratory conditions

    OpenAIRE

    Marín Benito, Jesús María; Andrades, M. S.; Rodríguez-Cruz, M. S.; Sánchez Martín, M. J.

    2012-01-01

    Purpose The aim of this work was to study the temporal changes in the sorption–desorption of fungicides in a sandy clay loam soil amended with spent mushroom substrate (SMS) under controlled laboratory conditions and the influence that fungicides properties and soil characteristics have on these processes. Soil amendment with SMS is becoming a widespread management practice since it can effectively solve the problems of uncontrolled SMS accumulation and disposal and improve soil quality...

  12. Effects of Humic Acid and Solution pH on Dispersion of Na—and Ca—Soil Clays

    Institute of Scientific and Technical Information of China (English)

    LANYEQING; HUQIONGYING; 等

    1996-01-01

    Dispersed soil clays have a negative impact on soil structure and contribute to soil erosion and contaminant movement.In this study,two typical soils from the south of China were chosen for investigating roles of pH and humic acid(HA) on dispersion of soil clays.Critical flocculation concentration (CFC) of the soil clay suspension was determined by using light transmission at a wavelength of 600 nm.The results indicated that effects of pH and HA on dispersion of the soil clays were closely related to the type of the major minerals makin up the soil and to the valence of the exchangeable cations as well.At four rates of pH(4,6,8and 10),the CFC for the Na-yellow-brown soil treated with H2O2 was increased from 0.32 to 0.56,6.0 to 14.0,10.0 to 24.6 and 26.0 to 52.0mmol L-1 NaCl,respectively when Na-HA was added at the rate of from 0 to 40mgL-1,With the same Na-HA addition and three pH(6,8and 10)treatments,the CFC for the Na-red soil was incresed from 0.5 to 20.0,1.0 to 40.0 and 6.0 to 141.0mmol L-1 NaCl,respectively.Obviously,pH and HA has greater effects on clay dispersion of the red soil(dominated by 1:1 minerals and oxides) than on that of the yellow-brown soil(dominated by 2:1minerals).However,at three rates of pH(6,8and 10) and with the addition of Ca-HA from 0 to 40mg L-1,the CFC of the Ca-yellow-brown soil and Ca-red soil treated with H2O2 was increased from 0.55 to 0.81,0.75 to 1.28,0.55 to 1.45and 0.038 to 0.266.0.25 to 0.62,0.7to 1.6mmol CaCl2 L-1,respectively.So,Na-soil claye are more sensitive to pH and HA than Ca-soil clays.

  13. Study of Various Techniques for Improving Weak and Compressible Clay Soil under a High Earth Embankment

    Directory of Open Access Journals (Sweden)

    Zein A.K. M.

    2014-04-01

    Full Text Available This paper investigates the suitability of three soil improvement techniques for the construction of a high earth embankment on thick weak and highly compressible clay soil. The eastern approach embankment of Alhalfaya Bridge on the River Nile linking Khartoum North and Omdurman cities was chosen as a case study and a comprehensive site investigation program was carried out to determine the properties the subsurface soils. The study results showed that unless the subsurface soils have been improved they may fail or undergo excessively large settlements due to the embankment construction. Three ground improvement techniques based on the principles of the “staged construction method, SCM”, “vertical sand drain, VSD” and “sand compaction piles, SCP” of embankment foundation soil treatment are discussed and evaluated. Embankment design options based on applications of the above methods have been proposed for foundation treatment to adequately support embankment loads. A method performance evaluation based on the improvement of soil properties achieved; the time required for construction and compared estimated costs criteria was made to assess the effectiveness and expected overall performance. Adoption of any of the soil improvement techniques considered depends mainly on the most critical and decisive factor governing the embankment design. Based on the overall performance for the embankment case studied, the sand drains is considered as the most appropriate improvement method followed by the sand compaction piles technique whereas the staged construction method showed the poorest overall performance.

  14. Studies of fertilizer nitrogen transformation in soil with special regard to ammonium fixation in clay minerals

    International Nuclear Information System (INIS)

    Transformation of 15N is investigated by means of nitrogen analyses of the soil and analyses for nitrogen uptake by plants after 15(NH4)2SO4 or K15NO3 fertilization. Under conditions of nitrogen deficiency, winter wheat utilizes 50-60% of the fertilizer nitrogen. Nitrogen uptake is higher with K15NO3 fertilization. This is due to higher immobilization and additional fixation after fertilization with ammonium. Nitrogen fixation under plant cover amounts to 12 kg N·ha-1 in loess soil and 4.5 kg N·ha-1 in heavily loamed clay soil. Remobilization and plant availability of these reserves cannot be discerned within one growing season. (author)

  15. Soil moisture distribution over time in a clay loam soil in Kosovo

    Directory of Open Access Journals (Sweden)

    Abdullah Nishori

    2013-02-01

    Full Text Available Studying the soil moisture distribution over time in a given soil profile is the object of the present study. The way the soil moisture gets distributed over soil profile depends particularly on the soil texture and on the soil suction gradients developed. However, it changes continuously over time for a given soil depth. The method of determining the soil moisture distribution over time is based on the measuring of soil moisture suctions developed and the soil moisture contents in various times, but in a given soil depth (internal drainage method [7]. The soil depths under investigation are four, starting from 0cm to 60cm, which means that the most important depth of soil profile is considered. Such measurements are supposed to be done over soil profile when the soil water flow is already ceased, in the conditions of preventing the evaporation [1, 7, and 9]. Therefore, to determine the soil moisture distribution over time, a plot of 8m x 6m or 48 m2 with no plants was set. The tensiometers and the electronic devices for soil moisture content measurements were installed in four soil depths. The plot was previously wetted and covered by a plastic to prevent the evaporation. In this way, it was made sure that the only possibility for water is to move internally, which gave us the opportunity to measure the changes in soil water content and in soil water suction over time. The final result showed that the dependency of soil water suction and soil moisture content over time is a power function (expressed as a semi logarithmic function, basically.

  16. Effect of Kiwi Shell and Incubation Time on Mobility of Lead and Cadmium in Contaminated Clay Soil

    OpenAIRE

    Bahareh Lorestani; Chia Arjangi; Hajar Merrikhpour

    2014-01-01

    In this study, the effectiveness of kiwi shell was investigated to reduce the mobility of Lead and Cadmium in clay soil in different intervals. For this purpose a clay soil sample was contaminated with Lead and Cadmium in distinct dishes with 10 and 600 ppm concentrations respectively and mixed with 5% kiwi shell. Samples were placed in incubator, and then sampling of soil in incubator was performed in intervals 3 hours, 1, 3, 7, 14, 21 and 28 days. Heavy metals concentrations were determined...

  17. Simulation of water movement and isoproturon behaviour in a heavy clay soil using the MACRO model

    Directory of Open Access Journals (Sweden)

    T. J. Besien

    1997-01-01

    Full Text Available In this paper, the dual-porosity MACRO model has been used to investigate methods of reducing leaching of isoproturon from a structured heavy clay soil. The MACRO model was applied to a pesticide leaching data-set generated from a plot scale experiment on a heavy clay soil at the Oxford University Farm, Wytham, England. The field drain was found to be the most important outflow from the plot in terms of pesticide removal. Therefore, this modelling exercise concentrated on simulating field drain flow. With calibration of field-saturated and micropore saturated hydraulic conductivity, the drain flow hydrographs were simulated during extended periods of above average rainfall, with both the hydrograph shape and peak flows agreeing well. Over the whole field season, the observed drain flow water budget was well simulated. However, the first and second drain flow events after pesticide application were not simulated satisfactorily. This is believed to be due to a poor simulation of evapotranspiration during a period of low rainfall around the pesticide application day. Apart from an initial rapid drop in the observed isoproturon soil residue, the model simulated isoproturon residues during the 100 days after pesticide application reasonably well. Finally, the calibrated model was used to show that changes in agricultural practice (deep ploughing, creating fine consolidated seed beds and organic matter applications could potentially reduce pesticide leaching to surface waters by up to 60%.

  18. Water and solute transport in agricultural soils predicted by volumetric clay and silt contents

    Science.gov (United States)

    Karup, Dan; Moldrup, Per; Paradelo, Marcos; Katuwal, Sheela; Norgaard, Trine; Greve, Mogens H.; de Jonge, Lis W.

    2016-09-01

    Solute transport through the soil matrix is non-uniform and greatly affected by soil texture, soil structure, and macropore networks. Attempts have been made in previous studies to use infiltration experiments to identify the degree of preferential flow, but these attempts have often been based on small datasets or data collected from literature with differing initial and boundary conditions. This study examined the relationship between tracer breakthrough characteristics, soil hydraulic properties, and basic soil properties. From six agricultural fields in Denmark, 193 intact surface soil columns 20 cm in height and 20 cm in diameter were collected. The soils exhibited a wide range in texture, with clay and organic carbon (OC) contents ranging from 0.03 to 0.41 and 0.01 to 0.08 kg kg- 1, respectively. All experiments were carried out under the same initial and boundary conditions using tritium as a conservative tracer. The breakthrough characteristics ranged from being near normally distributed to gradually skewed to the right along with an increase in the content of the mineral fines (particles ≤ 50 μm). The results showed that the mineral fines content was strongly correlated to functional soil structure and the derived tracer breakthrough curves (BTCs), whereas the OC content appeared less important for the shape of the BTC. Organic carbon was believed to support the stability of the soil structure rather than the actual formation of macropores causing preferential flow. The arrival times of 5% and up to 50% of the tracer mass were found to be strongly correlated with volumetric fines content. Predicted tracer concentration breakthrough points as a function of time up to 50% of applied tracer mass could be well fitted to an analytical solution to the classical advection-dispersion equation. Both cumulative tracer mass and concentration as a function of time were well predicted from the simple inputs of bulk density, clay and silt contents, and applied tracer

  19. IMPACT OF POLLUTION ON THE CLAY MINERALOGICAL COMPOSITION OF SOME SOILS FROM ZLATNA AREA (ROMANIA)

    OpenAIRE

    C.Craciun; Alexandrina Manea; Laura Paulette; Marius Eftene; Victoria Mocanu

    2008-01-01

    Zlatna area is a high polluted zone with heavy metals due to industrial activity (extraction and processing of non-ferrous area). In spite of the fact that industrial activity was stoped for 2-3 years, the effect of pollution are still obvious. The aim of this paper is to make evident some aspects concerning the impact of pollution on the mineralogical composition of the clay fraction (below 2μ) from some soils belonging to dystric cambisol and luvisol type. From the chemical point of view, ...

  20. Irrigation with saline-sodic water: effects on two clay soils

    Directory of Open Access Journals (Sweden)

    Giovanna Cucci

    2013-05-01

    Full Text Available The results of a 4-year experiment aimed at evaluating the effect of irrigation with saline-sodic water on the soil are reported. The research was carried out at the Campus of the Agricultural Faculty of Bari University (Italy on 2 clay soils (Bologna – T1 and Locorotondo – T2. The soils were cropped to borlotto bean (Phaseolus vulgaris L., capsicum (Capsicum annuum L., sunflower (Helianthus annuus L., wheat (Triticum durum Desf grown in succession; the crops were irrigated with 9 saline-sodic types of water and subjected to two different leaching fractions (10% and 20% of the watering volume. The 9 solutions were obtained dissolving in de-ionised water weighted amounts of sodium chloride (NaCl and calcium chloride (CaCl2, deriving from the combination of 3 saline concentrations and 3 sodicity levels. The crops were irrigated whenever the water lost by evapotranspiration from the soil contained in the pots was equal to 30% of the soil maximum available water. The results showed that, though the soils were leached during the watering period, they showed a high salt accumulation. Consequently, the saturated soil extract electrical conductivity increased from initial values of 0.65 and 0.68 dS m-1 to 11.24 and 13.61 dS m-1 at the end of the experiment, for the soils T1 and T2, respectively. The saline concentration increase in irrigation water caused in both soils a progressive increase in exchangeable sodium, and a decrease in exchangeable calcium and non-significant variations in exchangeable potassium (K and magnesium (Mg.

  1. Risk assessment of gas oil and kerosene contamination on some properties of silty clay soil.

    Science.gov (United States)

    Fallah, M; Shabanpor, M; Zakerinia, M; Ebrahimi, S

    2015-07-01

    Soil and ground water resource pollution by petroleum compounds and chemical solvents has multiple negative environmental impacts. The aim of this research was to investigate the impacts of kerosene and gas oil pollutants on some physical and chemical properties, breakthrough curve (BTC), and water retention curve (SWRC) of silty clay soil during a 3-month period. Therefore, some water-saturated soils were artificially contaminated in the pulse condition inside some glassy cylinders by applying half and one pore volume of these pollutants, and then parametric investigations of the SWRC were performed using RETC software for Van Genukhten and Brooks-Corey equations in the various suctions and the soil properties were determined before and after pollution during 3 months. The results showed that gas oil and kerosene had a slight effect on soil pH and caused the cumulative enhancement in the soil respiration, increase in the bulk density and organic matter, and reduction in the soil porosity and electrical and saturated hydraulic conductivity. Furthermore, gas oil retention was significantly more than kerosene (almost 40%) in the soil. The survey of SWRC indicated that the contaminated soil samples had a little higher amount of moisture retention (just under 15% in most cases) compared to the unpolluted ones during this 3-month period. The parametric analysis of SWRC demonstrated an increase in the saturated water content, Θ s, from nearly 49% in the control sample to just under 53% in the polluted ones. Contaminants not only decreased the residual water content, Θ r, but also reduced the SWRC gradient, n, and amount of α parameter. The evaluation of both equations revealed more accurate prediction of SWRC's parameters by Van Genukhten compared to those of Brooks and Corey. PMID:26085279

  2. Water Retention and Structure Stability in Smectitic or Kaolinitic Loam and Clay Soils Affected by Polyacrylamide Addition

    Science.gov (United States)

    Mamedov, Amirakh; Levy, Guy

    2015-04-01

    Studying the effects of polyacrylamide (PAM) on soil aggregate and structure stability is important in developing effective soil and water conservation practices and in sustaining soil and water quality. Five concentrations of an anionic PAM (0, 25, 50, 100 and 200 mg L-1) with a high molecular weight were tested on loam and clay soils having either a predominant smectitic or kaolinitic clay mineralogy. The effects of the PAM and of soil texture on soil water retention at near saturation and on aggregate and structure stability were investigated using the high energy moisture characteristic (HEMC) method. The S-shaped water retention curves obtained by the HEMC method were characterized by the modified van Genuchten (1980) model that provided: (i) the model parameters α and n, which represent the location of the inflection point and the steepness of the water retention curve, respectively; and (ii) the soil structure index, SI =VDP/MS, where VDP is the volume of drainable pores, an indicator of the quantity of water released by a soil over the range of applied suctions (0-5 J kg-1), and MS is the modal suction representing the most frequent pore sizes (> 60 μm). In general, the treatments tested (clay mineralogy, soil type and PAM concentration) resulted in: (i) a considerable modification of the shape of the water retention curves as indicated by the changes in the α and n values; and; (ii) substantial effects on the stability indices and other model parameters. The contribution of PAM concentration to soil structure stability depended on the clay mineralogy, being more effective in the smectitic soils than in the kaolinitic ones. Although kaolinitic soils are usually more stable than smectitic soils, when the latter were treated with PAM (25-200 mg L-1) the opposite trend was observed. In the loam soils, increasing the PAM concentration notably decreased the differences between values of the stability indices of the smectitic and kaolinitic samples. The

  3. Interactions of Cations with Electrodialyzed Clay Fraction of Soils as Inferred from Wien Effect in Soil Suspensions

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The electrical conductivities (ECs) of suspensions containing 25 and 30 g kg-1 solids prepared from theelectrodialyzed clay fraction (< 2 μm in diameter) of latosol, yellow-brown soil, and black soil, dispersed invarious nitrate solutions having concentrations of 1 × 10-4/z mol L-1, where z is the valence, and in distilledwater, were measured at field strengths ranging from 14 kV cm-1 to 210 kV cm-1. On the basis of analysesof the charge density and exchangeable ion composition on the surfaces of soil particles in the suspensions,and of the characters of the EC-field strength curves of the various suspensions, it was inferred that theincrement of EC (△EC) and/or relative electrical conductivity (REC) can indicate the bonding strengthbetween cations and soil particles. The bonding strengths of various cations with the soils diminished in theorder: K+ > Zn2+ > Mg2+ = Ca2+ > Na+ for latosol, Ca2+ > Zn2+ > Mg2+ = K+ > Na+ for yellow-brownsoil, and Zn2+ >Ca2+ > Mg2+ > K+ > Na+ for black soil.

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

    Science.gov (United States)

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

    2016-07-01

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

  5. Clay and Soil Photolysis of the Pesticides Mesotrione and Metsulfuron Methyl

    Directory of Open Access Journals (Sweden)

    Marie Siampiringue

    2014-01-01

    Full Text Available Photolysis may represent an important degradation process of pollutants at the surface of soil. In the present work, we report a detailed study on the degradation of two pesticides: mesotrione and metsulfuron methyl using a sunlight simulator. In a first step, we studied the photochemical behaviour at the surface of clays from the kinetic as well as from the analytical point of view. In both cases, the quantum yields were found to be higher when compared to those obtained in aqueous solutions. The effect of iron(III, water, and humic substances contents was studied. In the former cases, an increase of the degradation rate was observed while an inhibition was observed with the latter owing to a filter effect phenomenon. In a second step, we studied the photodegradation at the surface of natural soil and identified the generated byproducts. They appear to mainly arise from photohydrolysis process.

  6. The influence of clay mineralogy on the mobility of radiocaesium in upland soils of NW Italy

    International Nuclear Information System (INIS)

    137Cs extraction experiments were performed on 14 contaminated soils from NW Italy with different characteristics and mineralogical composition. Solutions of HCl (pH=0.5) and buffered EDTA/ammonium acetate (Lakanen solution) were used to assess bioavailability. The results show that less than 2% of 137Cs is available for leaching and/or root uptake. Even within a complex natural system it was possible to identify the amount of swelling clays (vermiculite+smectite) as the main control on Cs mobility under acidic conditions. The ammonium ion appears to be effective in desorbing Cs and its role is briefly discussed in terms of crystal chemistry. The relevance of mineralogy in assessing soil vulnerability is underlined

  7. Water storage change estimation from in situ shrinkage measurements of clay soils

    Directory of Open Access Journals (Sweden)

    B. te Brake

    2013-05-01

    Full Text Available The objective of this study is to assess the applicability of clay soil elevation change measurements to estimate soil water storage changes, using a simplified approach. We measured moisture contents in aggregates by EC-5 sensors, and in multiple aggregate and inter-aggregate spaces (bulk soil by CS616 sensors. In a long dry period, the assumption of constant isotropic shrinkage proved invalid and a soil moisture dependant geometry factor was applied. The relative overestimation made by assuming constant isotropic shrinkage in the linear (basic shrinkage phase was 26.4% (17.5 mm for the actively shrinking layer between 0 and 60 cm. Aggregate-scale water storage and volume change revealed a linear relation for layers ≥ 30 cm depth. The range of basic shrinkage in the bulk soil was limited by delayed drying of deep soil layers, and maximum water loss in the structural shrinkage phase was 40% of total water loss in the 0–60 cm layer, and over 60% in deeper layers. In the dry period, fitted slopes of the ΔV–ΔW relationship ranged from 0.41 to 0.56 (EC-5 and 0.42 to 0.55 (CS616. Under a dynamic drying and wetting regime, slopes ranged from 0.21 to 0.38 (EC-5 and 0.22 to 0.36 (CS616. Alternating shrinkage and incomplete swelling resulted in limited volume change relative to water storage change. The slope of the ΔV–ΔW relationship depended on the drying regime, measurement scale and combined effect of different soil layers. Therefore, solely relying on surface level elevation changes to infer soil water storage changes will lead to large underestimations. Recent and future developments might provide a basis for application of shrinkage relations to field situations, but in situ observations will be required to do so.

  8. Carbon-Nitrogen Relationships during the Humification of Cellulose in Soils Containing Different Amounts of Clay

    DEFF Research Database (Denmark)

    Sørensen, Lasse Holst

    1981-01-01

    amount of labeled N incorporated into organic forms increased in the clay-rich soils with increasing size of amendments. Of the total labeled C remaining in the soils after the 1st mo. of incubation 50-70% was acid hydrolyzable, compared to 80-100% of the total remaining labeled organic N. This...... immobilization reactions. Some of the labeled organic N when mineralized was re-incorporated into organic compounds containing increasing proportions of native soil-C, whereas labeled C when mineralized as CO2 disappeared from the soils. The amount of labeled amino acid-C, formed during decomposition of the...... 1st mo. of incubation at temperatures of 10, 20 and 30.degree. C, respectively, 38-65% of the labeled C added in cellulose had disappeared from the soils as CO2, and 60-nearly 100% of the labeled N added as NH4+ were incorporated into organic forms. The retention of total labeled C was largest in...

  9. Performance Evaluation of Different Tillage Systems in a Clay Loam Soil

    International Nuclear Information System (INIS)

    Field experiments were conducted to assess the performance of different tillage systems in a clay loam soil. A completely randomized block design with four treatments i.e., conventional tillage (CT), minimum tillage (MT), zero tillage (ZT) and controlled traffic farming (CTF) was carried out to evaluate the performance of tillage systems. Results indicated that the soil pulverization was higher (P<0.05) under MT and lower under CT treatments while, it was non-significant between MT and CTF treatments. Similarly, soil volume disturbed and effective ploughing depth was maximum (P<0.05) under CT followed by MT, CTF and minimum under ZT. Similarly the operating speed was significantly higher (P<0.05) under CTF and lower under CT whereas, wheel slippage/travel reduction was significantly minimum (P<0.05) under CTF and maximum under CT. Significantly, higher field capacity was recorded under CTF and lower (P<0.05) under CT. The maximum fuel consumption (P<0.05) was recorded under CT while it was minimum under ZT. Almost similar trends were observed for all parameters in 2012 and 2013. The results suggested that the control traffic system was more efficient tillage system in terms of soil pulverization, operating speed, travel reduction and over all field capacity. While, zero tillage had minimum fuel consumption and conventional tillage had higher working depth hence, more soil volume was disturbed under this treatment. (author)

  10. Comparing predictive abilities of three visible-near infrared spectrophotometers for soil organic carbon and clay determination

    DEFF Research Database (Denmark)

    Knadel, Maria; Stenberg, Bo; Deng, Fan;

    2013-01-01

    -NIRS sensors for soil characterization. There is a need for more work on the effects of scanning strategies, and use of different soil instrumentation. We compared three vis-NIR sensors with varying resolution, signal-to-noise ratios and spectral range. Their performance was evaluated based on soil organic...... carbon (SOC) and clay calibrations for 194 Danish top soils. Scanning procedures for the three spectrophotometers where done according to uniform laboratory protocols. SOC and clay calibrations were performed using PLS regression. One third of the data was used as an independent test set. A range of......Due to advances in optical technology a wide range of spectrometers is available. Recent interests in soil global libraries and sensor fusion presents a challenge with respect to combining data from different instrumentation. Only little research, however, has been done on the comparison of vis...

  11. Measuring the specific caesium sorption capacity of soils, sediments and clay minerals

    Energy Technology Data Exchange (ETDEWEB)

    De Koning, A. [aEnergy Research Centre of the Netherlands (ECN), Westerduinweg 3, P.O. Box 1, 1755 ZG, Petten (Netherlands); Konoplev, A.V. [Institute of Experimental Meteorology, 82 Lenin Avenue, Obninsk, Kaluga Region, 249020 (Russian Federation); Comans, R.N.J. [Wageningen University, Department of Soil Quality, P.O. Box 8005, 6700 EC Wageningen (Netherlands)

    2007-01-15

    Two methods to quantify the specific Cs sorption capacity of soils and sediments, which is generally believed to be associated with the Frayed Edge Sites (FES) of illitic clay minerals, are described in detail and are critically reviewed. The first method is a direct measurement of the FES capacity, while the second quantifies the combined parameter K{sub D}{sup C}s x [K{sup +}] (=K{sub C}(K-->Cs) x [FES]) i.e. the product of the FES capacity and the affinity of these sites for Cs. Both methods use the bulky AgTU-complex to mask non-specific sorption sites for Cs and are applied to a number of different soils and pure minerals. Measurement of the FES capacity of pure illite is straightforward. It is shown that the measured capacity is independent of the saturating ion, but does depend on particle size. This method could not be successfully applied to a peat bog soil with 90% organic matter, because the necessary correction for non-specific Cs sorption by the large pool of organic exchange sites overpasses the capacity of the small FES fraction. Measurement of the combined parameter K{sub D}{sup C}s x [K{sup +}] is shown to be more appropriate in such cases. Application of the FES capacity method to the hydrous aluminosilicate mineral allophane, an important soil constituent of Andisols, shows that the AgTU-complex is unable to block all non-specific sorption sites for Cs on this mineral. The K{sub D}{sup C}s x [K{sup +}] measurements show evidence of a very small number of specific Cs sorption sites on allophane, much smaller than inferred from the FES capacity measurement. The FES capacity of the clay mineral vermiculite is difficult to quantify because the high Cs concentrations that are needed to measure the FES capacity probably cause a collapse of the vermiculite interlayers, thereby creating more high-affinity sites for Cs. The K{sub D}{sup C}s x [K{sup +}] method, in which only trace concentrations of Cs are used, is shown to be more appropriate for soils

  12. Clay mineralogical evidence of a bioclimatically-affected soil, Rouge River basin, South-Central Ontario, Canada

    Science.gov (United States)

    Mahaney, W. C.

    2015-01-01

    Holocene soils in drainage basins of South-Central Ontario, Canada, are generally Fluvisols (Entisols) in floodplains transitioning to Brunisols (Inceptisols), Luvisols (Alfisols) and Podzols (Spodosols) in older terraces and in the glaciated tableland. A single landslide sourced from the highest fluvial terrace in the Rouge basin, with a rubble drop of ~ 12 m emplaced a lobe-shaped mass of reworked stream gravel, glaciolacustrine sediment and till, emplaced approximately 6 m above mean water level at a height roughly equivalent to previously dated mid-Holocene terraces and soils. Clay mineralogy of the soil formed in this transported regolith produced the usual semi-detrital/pedogenic distribution of 1:1 (Si:Al = 1:1), 2:1 and 2:1:1 clay minerals as well as primary minerals consisting of plagioclase feldspar, quartz, mica and calcite. Unexpectedly, the presence of moderate amounts of Ca-smectite in the Bk and Ck horizons, relative to a clay-mineral depleted parent material (Cuk), argues for a soil hydrological change affecting the wetting depth in the deposit. The presence of the uncommon 'maidenhair fern' (Adiantum pedantum) in the mass wasted deposit, a plant capable of high evapotranspiration, is interpreted as producing a bioclimatic disruption limiting soil water penetration to near root depth (wetting depth), thus producing a clay mineral anomaly.

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

    Science.gov (United States)

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

    2012-05-01

    Interactions between organic and mineral constituents prolong the residence time of organic matter in soils. However, the structural organization and mechanisms of organic coverage on mineral surfaces as well as their development with time are still unclear. We used clay fractions from a soil chronosequence (15, 75 and 120 years) in the foreland of the retreating Damma glacier (Switzerland) and from mature soils outside the proglacial area (>700 and mature soils. These findings from solid-state 13C NMR spectroscopy are in line with the increasing amounts of microbial-derived carbohydrates with soil age. The large accumulation of proteins, which was comparable to those of carbohydrates, and the very low C/N ratios of H2O2-resistant OM indicated strong and preferential associations between proteinaceous compounds and mineral surfaces. In the acid soils, poorly crystalline Fe oxides were the main providers of mineral surface area and important for the stabilization of OM during aging of the clay fractions. This was indicated by (I) the strong correlations between oxalate soluble Fe and both, SSA of H2O2-treated clay fractions and OC content, and (II) the low formation of expandable clays due to small extents of mineral weathering. Our chronosequence approach provided new insights into the evolution of organo-mineral interactions in acid soils. The formation of organo-mineral associations started with the sorption of proteinaceous compounds and microbial-derived carbohydrates on mineral surfaces which were mainly provided by ferrihydrite. The sequential accumulation of different organic compounds and the large OC loadings point to multiple accretion of OM in distinct zones or layers during the initial evolution of clay fractions.

  14. Source Zone Remediation by ZVI-Clay Soil-Mixing: Reduction of Tetrachloroethene Mass and Mass Discharge at a Danish DNAPL Site

    DEFF Research Database (Denmark)

    Fjordbøge, Annika Sidelmann; Lange, Ida Vedel; Binning, Philip John; Bjerg, Poul Løgstrup; Riis, Charlotte; Christensen, Anders G.; Terkelsen, Mads; Kjeldsen, Peter

    ZVI-Clay soil-mixing is a relatively new in situ remediation technology for remediation of chlorinated dense non-aqueous phase liquids (DNAPLs). The technology combines abiotic degradation (via zero-valent iron, ZVI, addition) and immobilization (via soil mixing and clay addition), whereby both c...

  15. Reducing the Influence of Soil Moisture on the Estimation of Clay from Hyperspectral Data: A Case Study Using Simulated PRISMA Data

    OpenAIRE

    Fabio Castaldi; Angelo Palombo; Simone Pascucci; Stefano Pignatti; Federico Santini; Raffaele Casa

    2015-01-01

    Soil moisture hampers the estimation of soil variables such as clay content from remote and proximal sensing data, reducing the strength of the relevant spectral absorption features. In the present study, two different strategies have been evaluated for their ability to minimize the influence of soil moisture on clay estimation by using soil spectra acquired in a laboratory and by simulating satellite hyperspectral data. Simulated satellite data were obtained according to the spectral charact...

  16. Influence of Compost and Compost Leachate on Growth and Chemical Composition of Barley and Bioavailability of Some Nutrients in Calcareous Clay Loam Soil and Sandy Soil

    OpenAIRE

    Z. Hatam; A. Ronaghi

    2012-01-01

    Application of compost and compost leachate as organic fertilizers can improve plant growth, nutrients uptake and increase phytoavailability of nutrients in soil. A factorial experiment (4×4×2) was conducted in a completely randomized design to evaluate the effect of compost and compost leachate on growth and chemical composition of barley and bioavailability of some nutrients in calcareous clay loam soil and sandy soil under greenhouse conditions. Treatments consisted of four levels of compo...

  17. Oxygen Isotope Fractionation Effects in Soil Water via Cations Adsorbed to High-CEC Clays

    Science.gov (United States)

    Oerter, E.; Finstad, K.; Schaefer, J.; Goldsmith, G. R.; Dawson, T. E.; Amundson, R.

    2012-12-01

    In isotope-based approaches to hydrology, soil and sediment are implicitly considered to be an inert matrix in which water resides or moves. Yet, this assumption is inconsistent with the fact that soils contain a wide range of solutes, and highly variable concentrations of chemically reactive clay particles, all of which may react with bulk water and create pools of energetically differing water with varying isotope compositions. The empirical basis of this hypothesis is the work of Sofer and Gat (1972, EPSL, 15(3)), who showed that the formation of hydration spheres around cations in aqueous solutions fractionate oxygen isotopes of water in ways that appear to be dependent on the cation's ionic potential and concentration. Because soil solutions commonly have high solid to fluid ratios, the potential for solids to create substantial pools of low free energy water, with corresponding isotope fractionation of the free and low energy waters, may be a common process. The potential for this to create measurable isotopic effects would be most evident in soils with high Cation Exchange Capacity (CEC). In order to test this hypothesis, montmorillonite (CEC ≈ 100 meq/100g), kaolinite (CEC≈10) and quartz (CEC≈0) mineral powders were saturated with 3M MgCl2 and KCl solutions (separately), rinsed with methanol and dried to saturate all available CEC sites with either Mg or K cations. Triplicate sets of monominerallic-deionized water mixtures were created at 5, 25, 50, 75 and 95% gravimetric water content. Each set of samples was then subjected to one of three water extraction techniques designed to access specific "pools" of soil water: (1) direct equilibration with CO2 to sample the soil's "free water", i.e. water not adsorbed to cations via hydration spheres; (2) centrifugation to simulate permanent wilting point conditions, thereby yielding most micro-pore, macro-pore, and free water; and (3) cryogenic vacuum distillation to recover all the soil water (free, pore and

  18. Determination of dependence between physical clay content in sod-podzolic soils and specific activity of 40K natural isotope

    International Nuclear Information System (INIS)

    In the conditions of the Republic of Belarus there was analyzed the dependence between physical clay content in sod-podzolic soil and specific activity of 40K natural isotope. There was described a new method of determination of soil belonging to a particular soil type in the conditions of identification of the natural isotope K40. Experiments were realized on sod-podzolic automorphous and half-hydromorphic soils of natural and cultural agrocoenosis polluted with 137Cs and 90Sr after the Chernobyl disaster. The pollution density of 137Cs was from 313 to 2480 kBq/m2 and 90Sr – from 2 to 63 kBq/m2. Research results showed that soil texture content influenced on radionuclide fixation. Radionuclide entering into plants from sod-podzolic loamy soils was in 1,5-2,0 times and more lower in comparison with radionuclide entering from sod-podzolic sandy soils. The highest base exchange capacity of 137Cs, 90Sr and 40K was typical for the fraction of physical clay with the minimal particle size of 0,01mm. There was marked a close correlation connection between natural isotope 40K and a content of physical clay

  19. Impact of Long-Term Alfalfa Cropping on Soil Potassium Content and Clay Minerals in a Semi-Arid Loess Soil in China

    Institute of Scientific and Technical Information of China (English)

    LI De-Cheng; B. VELDE; LI Feng-Min; ZHANG Gan-Lin; ZHAO Ming-Song; HUANG Lai-Ming

    2011-01-01

    Alfalfa cropping has been considered an efficient method of increasing soil fertility.Usually nitrogen increase in root nodules is considered to be the major beneficial effect.A 21-year time series (five sampling periods) of alfalfa cultivation plots on a loess soil,initially containing illite and chlorite,in Lanzhou of northwestern China was selected to investigate the relationships among alfalfa cropping,soil potassium (K) content and soil clay minerals.The results indicated that soil K significantly accumulated after cropping,with a peak value at about 15 years,and decreased afterwards.The accumulated K was associated with the K increase in the well-crystallized illite,which was not extracted by the traditional laboratory K extraction methods in assessing bioavailability.The steep decline in soil K content after 15-year cropping was in accord with the observed fertility loss in the alfalfa soil.Plant biomass productivity peaked at near 9 years of culture,whereas soil K and clay minerals continued to increase until cropping for 15 years.This suggested that K increased in the topsoil came from the deep root zone.Thus alfalfa continued to store K in clays even after peak production occurred.Nitrogen did not follow these trends,showing a general decline compared with the native prairie soils that had not been cropped.Therefore,the traditional alfalfa cropping can increase K content in the topsoil.

  20. INFLUENCE OF THE SATURATION PERCENTAGE OF THE CLAY-BEARING SOIL ON ITS STRESS-STRAIN STATE

    OpenAIRE

    Ter-Martirosyan Zaven Grigorevich; Nguyen Huy Hiep Huy Hiep

    2012-01-01

    The authors propose new analytical and numerical solutions to develop an advanced method of assessment of the stress-strain state of unsaturated clay soils exposed to external loading. The research findings demonstrate that the stress-strain state of the soil exposed to distributed loading in the half-space b = 2a is complex and homogeneous. It depends on the percentage of saturation and on the excessive pore pressure based on the saturation percentage. At the interim stage, when ...

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

    Science.gov (United States)

    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

  2. Effect of Alumina Colloid on the Sorption of Cs+ onto Sand and Clay Soils under Different Conditions

    International Nuclear Information System (INIS)

    Distribution coefficient of cesium on soil (yellow sand and clay) with and without alumina as a colloidal material was measured by batch technique. The adsorption of Cs+ ions from aqueous sodium chloride solution onto yellow sand and clay in absences and presence of Al2O3, was investigated under different physicochemical conditions including contact time between liquid and solid phases, ph, ionic strength, initial metal ion concentration and temperature. Pseudo first order and pseudo second-order kinetic models were used to analyze the sorption rate data and the results showed that the pseudo second-order model is best correlation the kinetics data in all studied sorption processes. Both Freundlich and Langmuir isotherm models were applicable to describe the adsorption of Cs+ ions by yellow sand with and without alumina but in case of clay with and without alumina Langmuir model not applicable. The maximum sorption capacities of clay in absences and presence of Al2O3 were found to be greater than that of yellow sand with and without Al2O3. The maximum sorption capacities for two sorbents were increased in presence of colloid alumina thane in absences. The sorption capacity is reduced at high temperature was related to the partial enhancement of desorption from yellow sand and clay surfaces. The adsorption of Cs+ ions by yellow sand and clay with and without alumina was exothermic reaction.

  3. Estimating hydraulic conductivities of the soil aggregates and their clay-organic coatings using numerical inversion of capillary rise data

    Science.gov (United States)

    Fér, Miroslav; Kodešová, Radka

    2012-10-01

    SummarySoil aggregates are in some soils and their horizons covered by organomineral coatings, which may significantly influence water and solute transfer into the aggregates. Knowledge of a coating occurrence, their structure and hydraulic properties is required for a more precise description of water flow and contaminant transport in soils. The aim of this study was to describe hydraulic properties of clay and organic matter coatings in the iluvial (Bt2) horizon of Haplic Luvisol. Sets of 30 unsorted aggregates, 24 aggregates with mostly clay coatings and 24 aggregates with clay-organic coatings, respectively, were studied to evaluate an impact of various coating composition. The coatings were removed from a half of the aggregates of each set. First, the wetting soil-water retention curve was measured on all soil aggregates. Then the capillary rise from the saturation pan into the multiple aggregates (set of 14 or 15 aggregates) without and with coatings was measured. Numerical inversion of the measured cumulative capillary rise data using the HYDRUS-1D program were applied to estimate the saturated hydraulic conductivities of the aggregates, Ks,aggr, and their coatings, Ks,coat. Results were compared with saturated hydraulic conductivities evaluated analytically using the sorptivity method, which was proposed previously. Data of the soil-water retention curves, measured on aggregates with and without coatings, did not allow distinguishing between retention curve parameters of the soil aggregates and their coatings. Therefore the same parameters were evaluated for both. Capillary rise into the soil aggregates without coatings was always faster than into the aggregates with coatings. As result the optimized saturated hydraulic conductivities, Ks,coat, of the clay and the organic matter coatings (the average values for unsorted, mostly clay and clay-organic coatings were 3.69 × 10-7, 2.76 × 10-7 and 1.81 × 10-7 cm min-1, respectively) were one to two order of

  4. Swelling clays and salt-affected soils : demixing of Na / Ca clays as the rationale for discouraging the use of sodium adsorption ratio (SAR

    Directory of Open Access Journals (Sweden)

    Guilhem Bourrie

    2014-12-01

    Full Text Available Sodium adsorption ratio SAR defined as SAR = (Na / V w(Ca+Mg/2 here concentrations of cations in solution are expressed in meq/L has long been considered as correlated to exchangeable sodium percentage (ESP on clay minerals or soil exchange complex, and as the key concept to explain swelling of clay minerals and the difficulties of reclaiming salt-affected soils. Though its basis is empirical, it was alleged to be theoretically justified on the basis of ion exchange, derived from the Gapon convention. However, it has long been challenged on the basis of both field observations and experimental evidence : it fails to account for the fact that calcium and magnesium do not play the same role, while potassium is absent from the formula ; calcium concentration must be “corrected “when calcite is present etc. There exist specific ion effects. Experimental measurements of the decrease of permeability when solutions are diluted led Quirk and Schofield (1955 to define the concept of critical threshold, and to show that potassium and magnesium play an intermediate role between sodium and calcium. This threshold is simply determined by the concentration of calcium, irrespective of the value of SAR or ESP. Indeed, demixing of Ca-Na clay minerals during ion exchange, a phenomenon well known since Glaeser and Mering (1954, implies that there exists an interaction between adjacent sites. This undermines the theoretical basis of SAR : the derivation of SAR from ion exchange equilibria implies to use an equilibrium constant. This parameter is no more constant if demixing occurs. The results obtained are positive : demixing leads to expulsion of sodium from inner exchange surfaces and its replacement by calcium, according to the “three crystals pore”proposed by Quirk (2003b. Sodium can then be more easily leached, as permeability is maintained by clusters of Ca-sites. Calcium concentration in solution appears thus as the simpler parameter to guide

  5. An Improved Description of the Seismic Response of Sites with High Plasticity Soils, Organic Clays, and Deep Soft Soil Deposits

    Science.gov (United States)

    Carlton, Brian

    Near surface soils can greatly influence the amplitude, duration, and frequency content of ground motions. The amount of their influence depends on many factors, such as the geometry and engineering properties of the soils and underlying bedrock, as well as the earthquake source mechanism and travel path. Building codes such as the 2012 International Building Code (IBC) define six site categories for seismic design of structures, which are based on the sites defined by the National Earthquake Hazards Reduction Program (NEHRP). Site categories A, B, C, D, and E are defined by the time averaged shear wave velocity over the top 30 meters of the soil deposit. Site category F is defined as sites that include liquefiable or sensitive soils, as well as sites with more than 3 meters (10 ft) of peat or highly organic clays, more than 7.5 meters (25 ft) of soil with PI > 75, and more than 37 meters (120 ft) of soft to medium stiff clays. The IBC specifies simplified procedures to calculate design spectra for NEHRP sites A through E, and requires a site specific investigation for NEHRP F sites. However, established procedures for performing the required site specific investigations for NEHRP F sites are limited. The objective of this research is to develop a simplified procedure to estimate design spectra for non-liquefiable NEHRP F sites, specifically sites with organic soils, highly plastic soils, and deep soft soil deposits. The results from this research will directly affect US practice by developing much needed guidelines in this area. There is little empirical data on the seismic response of non-liquefiable NEHRP F sites. As a result, this study focused on generating data from site response analyses. To capture the variability of ground motions, this study selected five base case scenarios according to tectonic environments and representative cases encountered in common US practice. Suites of ground motions for each scenario were created by collecting ground motions

  6. Clay content drives carbon stocks in soils under a plantation of Eucalyptus saligna Labill. in southern Brazil

    Directory of Open Access Journals (Sweden)

    Tanise Luisa Sausen

    2014-06-01

    Full Text Available Soil carbon accumulation is largely dependent on net primary productivity. To our knowledge, there have been no studies investigating the dynamics of carbon accumulation in weathered subtropical soils, especially in managed eucalyptus plantations. We quantified the seasonal input of leaf litter, the leaf decomposition rate and soil carbon stocks in an commercial plantation of Eucalyptus saligna Labill. in southern Brazil. Our goal was to evaluate, through multiple linear regression, the influence that certain chemical characteristics of litter, as well as chemical and physical characteristics of soil, have on carbon accumulation in soil organic matter fractions. Variables related to the chemical composition of litter were not associated with the soil carbon stock in the particulate and mineral fractions. However, certain soil characteristics were significantly associated with the carbon stock in both fractions. The concentrations of nutrients associated with plant growth and productivity, such as phosphorus, sulfur, copper and zinc, were associated with variations in the labile carbon pool (particulate fraction. Clay content was strongly associated with the carbon stock in the mineral fraction. The carbon accumulation and stabilization in weathered subtropical Ultisol seems to be mainly associated with the intrinsic characteristics of the soil, particularly clay content, rather than with the quantity, chemical composition or decomposition rate of the litter.

  7. Carbon sequestration in clay and silt fractions of Brazilian soils under conventional and no-tillage systems

    Directory of Open Access Journals (Sweden)

    Cecília Estima Sacramento dos Reis

    2014-08-01

    Full Text Available The capacity of soils to sequestrate carbon (C is mainly related to the formation of organo-mineral complexes. In this study, we investigated the influence of soil management systems on the C retention capacity of soil with an emphasis on the silt and clay fractions of two subtropical soils with different mineralogy and climate. Samples from a Humic Hapludox and a Rhodic Hapludox, clayey soils cultivated for approximately 30 years under no-tillage (NT and conventional tillage (CT were collected from six layers distributed within 100-cm soil depth from each site and from an adjacent native forest. After the removal of particulate organic matter (POM, the suspension (<53 µm was sonicated, the silt and clay fractions were separated in accordance with Stokes' law and the carbon content of whole soil and physical fractions was determined. In the Humic Hapludox, the clay and silt fractions under NT showed a higher maximum C retention (72 and 52 g kg-1, respectively in comparison to those under CT (54 and 38 g kg-1, respectively. Moreover, the C concentration increase in both fractions under NT occurred mainly in the topsoil (up to 5 cm. The C retention in physical fractions of Rhodic Hapludox varied from 25 to 32 g kg-1, and no difference was observed whether under an NT or a CT management system. The predominance of goethite and gibbsite in the Humic Hapludox, as well as its exposure to a colder climate, may have contributed to its greater C retention capacity. In addition to the organo-mineral interaction, a mechanism of organic matter self-assemblage, enhanced by longer periods of soil non-disturbance, seems to have contributed to the carbon stabilization in both soils.

  8. Enhanced degradation of 14C-HCB in two tropical clay soils using multiple anaerobic–aerobic cycles

    International Nuclear Information System (INIS)

    The aim of the study was to induce and enhance the degradation of hexachlorobenzene (HCB), a highly-chlorinated persistent organic pollutant, in two ecologically different tropical soils: a paddy soil (PS) and a non-paddy soil (FS). The degradation of HCB was enhanced using two anaerobic–aerobic cycles in model laboratory experiments. There was greater degradation of HCB in the PS (half-life of 224 days) relative to the FS (half-life of 286 days). It was further shown that soils amended with compost had higher metabolite concentrations relative to the non-amended soils. In the first cycle, there was little degradation of HCB in both soils. However, in the second cycle, there was enhanced mineralization in the PS under aerobic conditions, with the compost-treated samples showing higher mineralization. There was also extensive volatilization in both soils. The metabolite pattern revealed that the increased mineralization and volatilization was due to the formation of lower chlorinated benzenes. - Highlights: ► Two anaerobic–aerobic cycles enhanced the dissipation of HCB in two tropical soils – a paddy and non-paddy soil. ► The paddy soil was more effective in degrading HCB. ► The non-paddy soil adapted and degraded HCB in the second anaerobic–aerobic cycle. ► An additional carbon source enhanced degradation and mineralisation of HCB in both soils. - Two anaerobic–aerobic cycles enhance the degradation of HCB in two ecologically different tropical clay soils.

  9. Production of CO2 in crude oil bioremediation in clay soil

    Directory of Open Access Journals (Sweden)

    Sandro José Baptista

    2005-06-01

    Full Text Available The aim of the present work was to evaluate the biodegradation of petroleum hydrocarbons in clay soil a 45-days experiment. The experiment was conducted using an aerobic fixed bed reactor, containing 300g of contaminated soil at room temperature with an air rate of 6 L/h. The growth medium was supplemented with 2.5% (w/w (NH42SO4 and 0.035% (w/w KH2PO4. Biodegradation of the crude oil in the contaminated clay soil was monitored by measuring CO2 production and removal of organic matter (OM, oil and grease (OandG, and total petroleum hydrocarbons (TPH, measured before and after the 45-days experiment, together with total heterotrophic and hydrocarbon-degrading bacterial count. The best removals of OM (50%, OandG (37% and TPH (45% were obtained in the bioreactors in which the highest CO2 production was achieved.O objetivo do trabalho foi avaliar a biodegradação de petróleo em solo argiloso durante 45 dias de ensaios. Os ensaios de biodegradação foram conduzidos em biorreatores aeróbios de leito fixo, com 300 g de solo contaminado, à temperatura ambiente e com uma vazão de ar de 6 L/h. As deficiências nutricionais foram corrigidas com 2,5% (p/p (NH42SO4 e com 0,035% (p/p KH2PO4. O monitoramento foi realizado em função da produção de CO2, da remoção de matéria orgânica (OM, de óleos e graxas (OandG e de hidrocarbonetos totais de petróleo (TPH, além bactérias heterotróficas totais (BHT e hidrocarbonoclásticas (BHc, no início e após 45 dias. Nos biorreatores onde houve maior crescimento de bactérias hidrocarbonoclásticas e maior produção de CO2, obteve-se os melhores percentuais de remoções de MO (50%, OandG (37% e TPH (45%.

  10. Estimation model of Cs-137 activity in soil samples derives from percentage of organic carbon and silt-clay

    International Nuclear Information System (INIS)

    Estimation of Cs-137 activity in soil samples was conducted at Nganjuk area through its soil organic carbon and silt-clay percentage. Twenty-six soil samples taken from Nganjuk area have been used to establish the relationship of Cs-137 activity and its soil samples quality parameters by using SPSS (Statistical Product and Service Solutions) software. Chemical parameters of samples have higher variation compared to the physical. Estimated of Cs-137 activity in soil samples can be established by two parameters, those are percent of total organic carbon and percent of silt-clay contents. However, these two parameters could only explained 69.3 % of Cs-137 activity, the remaining 30.7 % potentially could be due to 10 % of error measurement, run-on redistribution of soil, farming as well as tillage system. By using the soil quality parameters, the Cs-137 activity under the limit detection could be estimated, hence, its usefulness to estimate the erosion rate through applying the Cs-model. (author)

  11. The ratio of clay content to total organic carbon content is a useful parameter to predict adsorption of the herbicide butachlor in soils

    International Nuclear Information System (INIS)

    Thirteen soils collected from 11 provinces in eastern China were used to investigate the butachlor adsorption. The results indicated that the total organic carbon (TOC) content, clay content, amorphous Fe2O3 content, silt content, CEC, and pH had a combined effect on the butachlor sorption on soil. Combination of the data obtained from the 13 soils in the present study with other 23 soil samples reported by other researchers in the literature showed that Koc would be a poor predictive parameter for butachlor adsorption on soils with TOC content higher than 4.0% and lower than 0.2%. The soils with the ratio of clay content to TOC content (RCO) values less than 60 adsorbed butachlor mainly by the partition into soil organic matter matrix. The soils with RCO values higher than 60 apparently adsorbed butachlor by the combination of the partition into soil organic matter matrix and adsorption on clay surface. - The relative importance of organic matter and clay in butachlor adsorption in soil will depend on the ratio of clay content to total organic carbon content

  12. Modeling Air Permeability in Variably Saturated Soil from Two Natural Clay Gradients

    DEFF Research Database (Denmark)

    Chamindu, Deepagoda T K K; Arthur, Emmanuel; Møldrup, Per;

    2013-01-01

    ka measurements from two Danish arable fields, each located on natural clay gradients, this study presents a pore tortuosity–disconnectivity analysis to characterize the soil–gas phase. The main objective of this study is to investigate the effect of soil–moisture condition, clay content, and other...... moisture conditions showed a strong linear relation (R2 = 0.74) to clay content. The Xa, further showed promising relations to specific surface area, Rosin–Rammler particle size distribution indices, α and β (representing characteristic particle size and degree of sorting, respectively), and the Campbell...... water retention parameter, b. Considering clay as a main driver of soil–gas phase characteristics, we developed expressions linking clay content and ka,1000 at ɛ1000 and discussed the effect of clay content on general ka–ɛ behavior....

  13. Influence of foliar application of algae extract and amino acids mixture on fenugreek plants in sandy and clay soils

    OpenAIRE

    SHAHIRA A. TARRAF; Talaat, Iman M.; ABO EL-KHAIR B. EL-SAYED; LAILA K. BALBAA

    2015-01-01

    Abstract. Tarraf SA, Talaat IM, El-Sayed AEB, Balbaa LK. 2015. Influence of foliar application of algae extract and amino acids mixture on fenugreek plants in sandy and clay soils. Nusantara Bioscience 7: 33-37. Two pot experiments were conducted to study the effect of foliar application of algae extract and amino acids mixture on the growth and chemical constituents of fenugreek plants (Trigonella foenum-graecum L.). Plants were sprayed with different concentrations of algae extract (0.0, 2....

  14. Tropical dryland agroforestry on clay soils: : Analysis of systems based on Acacia senegal in the Blue Nile region, Sudan

    OpenAIRE

    Raddad, Elamin Yousif Abdalla

    2006-01-01

    Acacia senegal, the gum arabic producing tree, is the most important component in traditional dryland agroforestry systems in the Blue Nile region, Sudan. The aim of the present study was to provide new knowledge on the potential use of A. senegal in dryland agroforestry systems on clay soils, as well as information on tree/crop interaction, and on silvicultural and management tools, with consideration on system productivity, nutrient cycling and sustainability. Moreover, the aim was also to ...

  15. THE EFFECT OF REINFORCEMENT ON THE GBFS AND LIME TREATED MARINE CLAY FOR FOUNDATION SOIL BEDS

    OpenAIRE

    D. Koteswara Rao,; G.V.R. Prasada Raju,; N. L. Manikanta Kumar

    2011-01-01

    India being peninsular country has large area coming under coastal region and also it has been the habitat for considerable percentage of population. The marine clays are generally found in the coastal region of West Bengal, Orissa, Andhra Pradesh, Tamilnadu, Kerala, Karnataka, Maharashtra and some parts of Gujarat. Marine or soft clays exists in these region are weak and deformative in nature. The present study deals with the strength characteristics of the marine clay collected from Kakinad...

  16. The Effect of Chloride and Sulfate Ions on the Adsorption of Cd2+ on Clay and Sandy Loam Egyptian Soils

    OpenAIRE

    EL-Hefnawy, Mohamed E.; Selim, Elmetwaly M.; Assaad, Faiz F.; Ismail, Ali I.

    2014-01-01

    Adsorption of Cd2+ on two types of Egyptian soils: clay (alluvial) and sandy loam (calcareous), was studied. Effect of changing the matrix electrolyte type and concentration was used to mimic the natural soil salts. Kinetics and thermodynamic parameters of the adsorption were calculated at two different electrolyte concentrations: 0.05 N and 0.15 N. The adsorption was described by Langmuir and Freundlich isotherms. Results showed that lower concentration of the NaCl or Na2SO4 electrolytes (0....

  17. Influence of Cracking on the distribution of Suction profile of a clay soil:comparative Approach by modeling of thermo-fluid coupling

    International Nuclear Information System (INIS)

    Soil shrinks as it desiccates, and the magnitude of shrinkage can be large for clay soils, rich in fine particles. Soil drying leads to cracks formation, causing a phenomenon of high significance in environmental geotechnics. To illustrate the effect of cracking, a numerical model of soil atmosphere interaction has been developed taking into account the thermo fluid coupling of an unsaturated clay soil. The model is used to simulate the evolution if suction during the drying process. The study simulates firstly the model of an intact soil. Then, the study is extended to investigate the case of a cracked soil. The main results showed a significant influence of the presence of crack on the suction profile.In cracked soil, further loss of moisture occurs as direct evaporation from crack followed by an increase of the suction in the soil. High suction is initially concentrated on the head of the crack then extended to both vertical and horizontal sideway directions. (author)

  18. Clay composition and swelling potential estimation of soils using depth of absorption bands in the SWIR (1100-2500 nm) spectral domain

    Science.gov (United States)

    Dufréchou, Grégory; Granjean, Gilles; Bourguignon, Anne

    2014-05-01

    Swelling soils contain clay minerals that change volume with water content and cause extensive and expensive damage on infrastructures. Presence of clay minerals is traditionally a good estimator of soils swelling and shrinking behavior. Montmorillonite (i.e. smectite group), illite, kaolinite are the most common minerals in soils and are usually associated to high, moderate, and low swelling potential when they are present in significant amount. Characterization of swelling potential and identification of clay minerals of soils using conventional analysis are slow, expensive, and does not permit integrated measurements. SWIR (1100-2500 nm) spectral domain are characterized by significant spectral absorption bands related to clay content that can be used to recognize main clay minerals. Hyperspectral laboratory using an ASD Fieldspec Pro spectrometer provides thus a rapid and less expensive field surface sensing that permits to measure soil spectral properties. This study presents a new laboratory reflectance spectroscopy method that used depth of clay diagnostic absorption bands (1400 nm, 1900 nm, and 2200 nm) to compare natural soils to synthetic montmorillonite-illite-kaolinite mixtures. We observe in mixtures that illite, montmorillonite, and kaolinite content respectively strongly influence the depth of absorption bands at 1400 nm (D1400), 1900 nm (D1900), and 2200 nm (D2200). To attenuate or removed effects of abundance and grain size, depth of absorption bands ratios were thus used to performed (i) 3D (using D1900/D2200, D1400/D1900, and D2200/D1400 as axis), and (ii) 2D (using D1400/D1900 and D1900/D2200 as axis) diagrams of synthetic mixtures. In this case we supposed that the overall reduction or growth of depth absorption bands should be similarly affected by the abundance and grain size of materials in soil. In 3D and 2D diagrams, the mixtures define a triangular shape formed by two clay minerals as external envelop and the three clay minerals mixtures

  19. Colloid and Phosphorus Leaching From Undisturbed Soil Cores Sampled Along a Natural Clay Gradient

    DEFF Research Database (Denmark)

    Vendelboe, Anders Lindblad; Møldrup, Per; Heckrath, Goswin Johann;

    2011-01-01

    followed by lower and stable colloid and phosphorus concentrations. The mass of particles leached at first flush was independent of clay content and was attributed to the instant release of particles associated with the macropore walls and released upon contact with flowing water. Below a clay content of È......0.15 kg kgj1, the later leaching (after the first flush) of particles was independent of the clay content. Above this threshold, there was a positive relationship between the mass of leached particles after the first flush and the clay content. Particle release after the first flush was linearly...... correlated to the accumulated outflow and was described as a diffusion controlled process, using ¾(accumulated outflow). The mass of leached particles was positively correlated to the clay content as well as to water-dispersible colloids. Particulate phosphorus (P) was linearly correlated to concentration of...

  20. Investigating the Effect of Three Nitrate Fertilizers on Nitrate Leaching under the Root Zone in Clay Loam Soil

    Directory of Open Access Journals (Sweden)

    Thamer A. Mohammed

    2009-01-01

    Full Text Available Problem statement: Nitrogen fertilizer is recognized as an important factor in crop’s yield level, however more application of N fertilizers in the soil have some adverse effects on environment and especially on ground water contamination. Perception and recognition the factors influencing nitrate transport through soil profile is helpful for fertilizer management to minimize adverse impacts on environment and nitrate leaching below the root zone. Approach: In this study, 9 large cylindrical lysimeters with 1 m height and 0.5 m diameter were filled with clay loam soil and planted with maize to investigate nitrate leaching under different types of N-fertilizer, chemical fertilizer, activated sludge and organic manure. Nitrate concentration in the soil and drainage water samples were analyzed by spectrophotometer method and the mass of nitrate was calculated in soil and drainage water. Crop productions for different treatments were compared too. Results: Results showed that cumulative mass of nitrate leaching from organic fertilizer was greater than the other treatments (229 kg ha-1. Organic manure had the greatest nitrate accumulation in soil (15.17 mg kg-1, which was significantly greater than chemical fertilizer. Conclusions/Recommendations: experimental results showed that manure application could result in NO3--N accumulation increase in the deeper soil profiles compared with activated sludge. Results showed that maize production was significantly higher under activated sludge fertilizer. Observations made in the current study suggested activated sludge fertilizer due to a higher crop production with same level of ground water contamination, especially in clay loam soils.

  1. The development of a multi-surface soil speciation model for Cd (II) and Pb (II): Comparison of two approaches for metal adsorption to clay fractions

    International Nuclear Information System (INIS)

    Highlights: • A two-site surface complexation model was used to predict metal binding onto clays. • Five different surfaces are included in the multi-surface speciation model. • The improved model well predicted metal adsorption under various I and pH. • Adsorption on clays should be considered especially at low I and high pH condition. - Abstract: The mobility of toxic metals in soils or sediments is of great concern to scientists and environmentalists since it directly affects the bioavailability of metals and their movement to surface and ground waters. In this study, a multi-surface soil speciation model for Cd (II) and Pb (II) was developed to predict the partition of metals on various soil solid components (e.g. soil organic matter (SOM), oxide mineral, and clay mineral). In previous study, the sorption of metal cations on SOM and oxide minerals has been evaluated by thermodynamically based surface complexation model. However, metal binding to soil clay fractions was normally treated in a simplistic manner: only cation exchange reactions were considered and exchange coefficient was assumed unity. In this study, the binding of metals onto clays was described by a two-site surface sorption model (a basal surface site and an edge site). The model was checked by predicting the adsorption behavior of Cd (II) and Pb (II) onto three selected Chinese soils as a function of pH and ionic strengths. Results showed that the proposed model more accurately predicted the metal adsorption on soils under studied condition, especially in low ionic strength condition, suggesting that adsorption of metals to soil clay fractions need to be considered more carefully when modeling the partition of trace elements in soils. The developed soil speciation model will be useful when evaluating the movement and bioavailability of toxic metals in soil environment

  2. Can mud (silt and clay) concentration be used to predict soil organic carbon content within seagrass ecosystems?

    KAUST Repository

    Serrano, O.

    2016-01-18

    The emerging field of blue carbon science is seeking cost-effective ways to estimate the organic carbon content of soils that are bound by coastal vegetated ecosystems. Organic carbon (Corg) content in terrestrial soils and marine sediments has been correlated with mud content (i.e. silt and clay), however, empirical tests of this theory are lacking for coastal vegetated ecosystems. Here, we compiled data (n = 1345) on the relationship between Corg and mud (i.e. silt and clay, particle sizes <63 μm) contents in seagrass ecosystems (79 cores) and adjacent bare sediments (21 cores) to address whether mud can be used to predict soil Corg content. We also combined these data with the δ13C signatures of the soil Corg to understand the sources of Corg stores. The results showed that mud is positively correlated with soil Corg content only when the contribution of seagrass-derived Corg to the sedimentary Corg pool is relatively low, such as in small and fast growing meadows of the genera Zostera, Halodule and Halophila, and in bare sediments adjacent to seagrass ecosystems. In large and long-living seagrass meadows of the genera Posidonia and Amphibolis there was a lack of, or poor relationship between mud and soil Corg content, related to a higher contribution of seagrass-derived Corg to the sedimentary Corg pool in these meadows. The relative high soil Corg contents with relatively low mud contents (i.e. mud-Corg saturation) together with significant allochthonous inputs of terrestrial organic matter could overall disrupt the correlation expected between soil Corg and mud contents. This study shows that mud (i.e. silt and clay content) is not a universal proxy for blue carbon content in seagrass ecosystems, and therefore should not be applied generally across all seagrass

  3. Contamination Time Effect on Plant Available Fractions of Cadmium and Zinc in a Mexican Clay Loam Soil

    Science.gov (United States)

    Ehsan, Muhammad; Augustine Molumeli, Polile; Espinosa Hernandez, Vicente; Baeza Reyes, Alejandro; Perez Moreno, Jesus; Hernandez, Marcos Soto; Ojeda Trejo, Enrique; Jaen Contreras, David; Ruiz Bello, Alejandrina; Robledo Santoyo, Edmundo

    Knowledge of plant available fractions of heavy metals in soil can assist directing phytoremediation efforts for contaminated soils. For this reason different doses of ZnCl2 (0, 200, 400 and 600 mg kg-1) and CdCl2, 2½ H2O (0, 9, 18 and 27 mg kg-1) were applied to an uncontaminated slightly acidic clay loam soil from Sate of Mexico, Mexico incubated under ambient temperature and humidity for 90 days. Both the metals were extracted with a DTPA-TEA-CaCl2 mixture after 1, 5, 15, 25, 60 and 90 days and analyzed using atomic absorption spectroscopy. The results showed that DTPA extractable contents of Zn and Cd followed a decreasing trend with increase in incubation time. Maximum contents were found at day 01 in all the treatments. After 15 days of incubation, the variation in extractable contents was non-significant. The rapid adsorption of the metals might be due to elevated clay content (34%) of the incubated soil.

  4. Clay mineralogy and geochemistry of the soils derived from metamorphic and mafic igneous parent rocks in Lahijan area

    International Nuclear Information System (INIS)

    The mineralogical and geochemical composition of the soils of three representative pedons formed on basaltic andesite, andesitic basalt and phyllite were investigated. Results by x-ray diffraction showed that progressive weathering of rocks have been marked by gradual accumulation of Al, Fe, Ti, Mg, H3O+ and depletion of Na, K, Ca and Si in the soil; although, predominant clay, loss and gain trend of elements was different on the various rocks. Based on x-ray diffraction analysis, minerals in basaltic andesite and andesitic basalt were similar but, the intensity of mica to smectite or vermiculite transformation for latter was relatively higher than the former. This process revealed the degradation mineral because of two reasons: (i) - smectite and vermiculite increased whereas mica decreased in surface horizons. (i i)-Irregular mixed layer of mica-smectite or vermiculite was present in deeper part (170 cm) of the soils from andesitic basalt but shallower depth (75 em) of the soils from basaltic andesite. Clay minerals in phyllite were mica and chlorite that stratified with vermiculite. However, the absence of smectite in phyllite might be attributed to more acidic condition or position of the Fe ion in the mineral lattice of chlorite (higher Fe in the interlayer hydroxide sheet)

  5. Some Fertility Characteristics and Fertilizer Requirements of a Newly Reclaimed Upland Red Soil Derived from Quaternary Red Clay

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    A series of field experiments from 1990 to 1994 in Yingtan, Jiangxi Province, were conducted on an upland red soil derived from Quaternary red clay which had been reclaimed three years before the experiments, in order to study the fertility characteristics and fertilizer requirements of the newly reclaimed soil. The field experiments included that on nutrient characteristics and fertilizer effect, that on K-supplying potential and K-Mg relationship, that on fertilization rates of K and N, etc. The newly reclaimed upland soil was low in both N and P, and its responses to nitrogen and phosphate application were very significant. The K-supplying potential was also low, so the soil was highly responsive to K fertilizer. The effect of Ca and Mg fertilizers was not so great for the reason that certain amounts of Ca and Mg were incorporated into the soil through application of calcium magnesium phosphate during land leveling before the experiments. Among the four micronutrients, B, Mo, Zn and Cu, B had the greatest effect on the soil. The fertilizer requirements of the soil were in an order of P and N > K > lime and B > Mg > Mo, Zn and Cu. Eight crops tested had different fertilizer-requiring characteristics. Rapeseed was very sensitive to P and B fertilizers. Barely was especially sensitive to P and lime and it also responded to B, Mo, Zn and Cu. And sweet potato was especially sensitive to K.

  6. Short-term Effects of Tillage Practices on Organic Carbon in Clay Loam Soil of Northeast China

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A tillage experiment, consisting of moldboard plow (MP), ridge tillage (RT), and no-tillage (NT), was performed in a randomized complete block design with four replicates to study the effect of 3-year tillage management on SOC content and its distribution in surface layer (30 cm) of a clay loam soil in northeast China. NT did not lead to significant increase of SOC in topsoil (0-5 cm) compared with MP and RT; however, the SOC content in NT soil was remarkably reduced at a depth of 5-20 cm. Accordingly, short-term (3-year) NT management tended to stratify SOC concentration, but not necessarily increase its storage in the plow layer for the soil.

  7. Survival of Escherichia coli and Salmonella Typhimurium in slurry applied to clay soil on a Danish swine farm

    DEFF Research Database (Denmark)

    Boes, J.; Alban, L.; Bagger, J.;

    2005-01-01

    A pilot study was carried out on a Danish swine farm infected with multi-resistant Salmonella Typhimurium DT104 (MRDT104). We aimed to (1) investigate to which degree the decline of Escherichia coli and Salmonella in swine slurry applied to farmland depended on the application method; (2) estimate...... the survival times of E. coli and Salmonella in the soil surface following deposition of naturally contaminated pig slurry; and (3) simulate survival of Salmonella in different infection levels using E. coli data as input estimates. Slurry was deposited by four different methods: (1) hose applicator...... soil amended with contaminated pig slurry was an effective means to reduce environmental exposure to E. coli and Salmonella on this clay-soil farm....

  8. Methodical comparison of neutron depth probes and long-term soil moisture measurements on loess, sandy loess, and boulder clay

    International Nuclear Information System (INIS)

    Three measuring instruments were tested: 0.05 mCi Cf-252, 100 mCi Am-241/Be, 500 mCi Am-241/Be. The advantages - measurement in undisturbed soil profiles, large depths of measurement, reproducibility of measurements in the same place over several years - and the disadvantages - radiation protection, resolution, variations of measured volume in dependence of moisture, background influences etc. - have been critically checked by experiment. In addition, annual soil moisture curves have been measured over two years by parallel use of the free probes on a loess, sandy loess, and boulder clay site. The results were compared and discussed with a view to the soil water dynamics of these sites. (orig./HP)

  9. Effects of different fertilizers on the abundance and community structure of ammonia oxidizers in a yellow clay soil.

    Science.gov (United States)

    Yao, Huaiying; Huang, Sha; Qiu, Qiongfen; Li, Yaying; Wu, Lianghuan; Mi, Wenhai; Dai, Feng

    2016-08-01

    Yellow clay paddy soil (Oxisols) is a typical soil with low productivity in southern China. Nitrification inhibitors and slow release fertilizers have been used to improve nitrogen fertilizer utilization and reduce environmental impaction of the paddy soil. However, their effects on ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) in paddy soil have rarely been investigated. In the present work, we compared the influences of several slow release fertilizers and nitrification inhibitors on the community structure and activities of the ammonia oxidizers in yellow clay soil. The abundances and community compositions of AOA and AOB were determined with qPCR, terminal restriction fragment length polymorphism (T-RFLP), and clone library approaches. Our results indicated that the potential nitrification rate (PNR) of the soil was significantly related to the abundances of both AOA and AOB. Nitrogen fertilizer application stimulated the growth of AOA and AOB, and the combinations of nitrapyrin with urea (NPU) and urea-formaldehyde (UF) inhibited the growth of AOA and AOB, respectively. Compared with other treatments, the applications of NPU and UF also led to significant shifts in the community compositions of AOA and AOB, respectively. NPU showed an inhibitory effect on AOA T-RF 166 bp that belonged to Nitrosotalea. UF had a negative effect on AOB T-RF 62 bp that was assigned to Nitrosospira. These results suggested that NPU inhibited PNR and increased nitrogen use efficiency (NUE) by inhibiting the growth of AOA and altering AOA community. UF showed no effect on NUE but decreased AOB abundance and shifted AOB community. PMID:27063014

  10. Properties of a clay soil from 1.5 to 3.5 years after biochar application and the impact on rice yield

    NARCIS (Netherlands)

    Carvalho, M.T.M.; Madari, B.E.; Bastiaans, L.; Oort, van P.A.J.; Leal, W.G.O.; Heinemann, A.B.; Silva, da M.A.S.; Maia, A.H.N.; Parsons, D.; Meinke, H.

    2016-01-01

    We assessed the impact of a single application of wood biochar on soil chemical and physical properties and aerobic rice grain yield on an irrigated kaolinitic clay Ferralsol in a tropical Savannah. We used linear mixed models to analyse the response of soil and plant variables to application rat

  11. Mapping of Total Carbon and Clay Contents in Glacial Till Soil Using On-the-Go Near-Infrared Reflectance Spectroscopy and Partial Least Squares Regression

    Institute of Scientific and Technical Information of China (English)

    SHEN Zhang-Quan; SHAN Ying-Jie; PENG Li; JIANG Yu-Gen

    2013-01-01

    Characterizing spatial variability of soil attributes,using traditional soil sampling and laboratory analysis,is cost prohibitive.The potential benefit of managing soils on a site-specific basis is well established.High variations in glacial till soil render detailed soil mapping difficult with limited number of soil samples.To overcome this problem,this paper demonstrates the feasibility of soil carbon and clay mapping using the newly developed on-the-go near-infrared reflectance spectroscopy (NIRS).Compared with the geostatistics method,the partial least squares regression (PLSR),with NIRS measurements,could yield a more detailed map for both soil carbon and clay.Further,by using independent validation dataset,the accuracy of predicting could be improved significantly for soil clay content and only slightly for soil carbon content.Owing to the complexity of field conditions,more work on data processing and calibration modeling might be necessary for using on-the-go NIRS measurements.

  12. Innovative Uses of Organo-philic Clays for Remediation of Soils, Sediments and Groundwater

    International Nuclear Information System (INIS)

    PCBs and similar low-solubility organic compounds continue to offer significant challenges in terrestrial and sediment remediation applications. While selective media such as granular activated carbon (GAC) have proven to be successful at absorbing soluble organics, these media may have reduced performance due to blinding in the presence of high molecular weight organic matter. An alternative technology addresses this problem with a clay-based adsorption media, which effectively and efficiently stabilizes low-solubility organic matter. OrganoclayTM reactive media utilizes granular sodium bentonite, which has been chemically modified to attract organic matter without absorbing water. The unique platelet structure of bentonite clays provides tremendous surface area and the capacity of the media to absorb over 60 percent of its own weight in organic matter. Because of these properties, organo-clays allow for several cost-effective in-situ remediation techniques, such as: - Flow-through filtration for removal of organic matter from aqueous solutions. Organo-clay can be utilized as a fixed-bed media in a column operation. This specialty media offers a high efficient alternative to Granular Activated Carbon (GAC) when applied as a flow through media to remove oil, PCB and other low soluble organic contaminates from water. - Placement in a Reactive Core MatTM. Organo-clay may be encapsulated into carrier textiles which are adhered together to create a thin reactive layer with high strength and even distribution of the reactive media. This type of delivery mechanism can be successfully applied in a sub aqueous or terrestrial environment for sediment capping applications - Permeable reactive barriers. Organo-clay can deliver high sorption capacity, high efficiency, and excellent hydraulic conductivity as a passive reactive media in these applications. (authors)

  13. Size and Persistence of the Microbial Biomass Formed during the Humification of Glucose Hemicellulose Cellulose, and Straw in Soils Containing Different Amounts of Clay

    DEFF Research Database (Denmark)

    Sørensen, Lasse Holst

    1983-01-01

    straw. The half-life of labelled C in biomass during the second year of incubation ranged from 2 to 3 years.Native C in biomass ranged from 0.5 to 1.4% of the total C in native soil organic matter, the highest values occurring in the clay-rich soils. The half-life of native soil C, estimated from CO2...

  14. [Effects of Different Residue Part Inputs of Corn Straws on CO2 Efflux and Microbial Biomass in Clay Loam and Sandy Loam Black Soils].

    Science.gov (United States)

    Liu, Si-yi; Liang, Ai-zhen; Yang, Xue-ming; Zhang, Xiao-ping; Jia, Shu-xia; Chen, Xue-wen; Zhang, Shi-xiu; Sun, Bing-jie; Chen, Sheng-long

    2015-07-01

    The decomposed rate of crop residues is a major determinant for carbon balance and nutrient cycling in agroecosystem. In this study, a constant temperature incubation study was conducted to evaluate CO2 emission and microbial biomass based on four different parts of corn straw (roots, lower stem, upper stem and leaves) and two soils with different textures (sandy loam and clay loam) from the black soil region. The relationships between soil CO2 emission, microbial biomass and the ratio of carbon (C) to nitrogen (N) and lignin of corn residues were analyzed by the linear regression. Results showed that the production of CO2 was increased with the addition of different parts of corn straw to soil, with the value of priming effect (PE) ranged from 215. 53 µmol . g-1 to 335. 17 µmol . g -1. Except for corn leaves, the cumulative CO2 production and PE of clay loam soil were significantly higher than those in sandy loam soil. The correlation of PE with lignin/N was obviously more significant than that with lignin concentration, nitrogen concentration and C/N of corn residue. The addition of corn straw to soil increased the contents of MBC and MBN and decreased MBC/MBN, which suggested that more nitrogen rather than carbon was conserved in microbial community. The augmenter of microbial biomass in sandy loam soil was greater than that in clay loam soil, but the total dissolved nitrogen was lower. Our results indicated that the differences in CO2 emission with the addition of residues to soils were primarily ascribe to the different lignin/N ratio in different corn parts; and the corn residues added into the sandy loam soil could enhance carbon sequestration, microbial biomass and nitrogen holding ability relative to clay loam soil. PMID:26489342

  15. CONSTRUCTION OF A NEW HIGHWAY EMBANKMENT ON THE SOFT CLAY SOIL TREATMENT BY STONE COLUMNS IN MALAYSIA

    Directory of Open Access Journals (Sweden)

    QASIM A. ALJANABI

    2013-08-01

    Full Text Available To continue of the second phase of the East Coast Expressway between Kuantan and Kula Terengganu in Malaysia system innovative solution are required. In this new phase there are embankment region has been subjected to extensive soft clay soil. These comprise typically of clayey silts of very high water content and undrained shear strengths in the range of 8 to 11 kPa to depths of up to 8m. To support an embankment height of up to 12 m, were filled and thereafter Vibro Replacement treatment was carried out to treat the very soft soil. Extensive instrumentation using rod settlement gauges, inclinometers and piezometers were installed to monitor the performance of the Vibro Replacement treatment. This paper reports on aspects of design, installation and the measured results from the instrumentation scheme.

  16. Use of Clay Deposits in Water Management of Calcareous Sandy Soils Under-surface and Sub-surface Drip Irrigation

    International Nuclear Information System (INIS)

    The objective of this study was to investigate the effect of irrigation (levels and methods) and type of clay deposits on lettuce yield, water use efficiency WUE and the distributions of soil moisture and salts in the root zone of sandy calcareous soils. A field experiment was conducted at the college experimental station in 2002-2003. It consists of three clay deposits, three rates (0, 1.0 and 2.0%), and four total irrigation applied water levels, 360 mm (T1), 520 mm (T2), 635 mm (T3) and 822 mm (T4), using surface and subsurface drip irrigation. Results indicated that yield was significantly increased with the increase of irrigation level, whereas WUE significantly decreased with increase of irrigation level. The average yield increased by 9.30% in a high irrigation level compared to a moderate irrigation level, and decreased by 14.2% at the more stressed irrigation level. WUE decreased by 49.0% at a moderate irrigation level and yield was significantly affected by amendment rates. The difference between surface and subsurface drip on yields and WUE were also significant. Results indicated that the moisture content of the subsurface treated layer increased dramatically, while salts were accumulated at the surface and away from the emitters in subsurface drip irrigation. The advantages of surface drip irrigation were related to the relative decrease in salt accumulation in the root zone area where the plant roots were active and the water content was relatively high. (author)

  17. Liquefaction Susceptibility of Soils With Clay Particles from Earthquake-induced Landslides

    Institute of Scientific and Technical Information of China (English)

    CHEN Chuan-sheng; JIANG Xin; ZHANG Xu

    2007-01-01

    The main reason for earthquake-induced landslides is liquefaction of soil, a process considered to occur mostly in sandy soils. Liquefaction can occur in clayey soils has also been reported and proven in the recent literature, but liquefaction in clayey soils still remains unclear and there are many questions that need to be addressed. In order to address these questions, an depth study on the liquefaction potential of clayey soils was conducted on the basis of field investigation and a series of laboratory tests on the samples collected from the sliding surface of the landslides. The liquefaction potential of the soils was studied by means of undrained cyclic ring-shear tests. Research results show that the liquefaction potential of sandy soils is higher than that of clayey soils given the same void ratio;the soil resistance to liquefaction rises with an increase in plasticity for clayey soils; relation between plasticity index and the liquefaction potential of soil can be used in practical application to estimate the liquefaction potential of soil.

  18. Evaluation of biostimulation in clay soil contaminated by petroleum; Avaliacao da bioestimulacao em solos argilosos contaminados com petroleo

    Energy Technology Data Exchange (ETDEWEB)

    Baptista, Sandro J.; Cammarota, Magali C.; Freire, Denize D.C. [Universidade Federal do Rio de Janeiro, RJ (Brazil). Dept. de Engenharia Bioquimica. Lab. de Tecnologia Ambiental]. E-mail: baptista@eq.ufrj.br; denize@eq.ufrj.br

    2003-07-01

    Biostimulation has been used as a technic in order to increase the microbial activity adding inorganic nutrients and/or terminal electron acceptor in the contaminated place. The main goal of this work was evaluate how each inorganic nutrient could help the biodegradation at a given petroleum contaminated clay soil. At first, the work was designed to investigate the optimal relation between C:N:P that could influence the best organic matter removal (OMR) in aerobic bioreactors with 50 ml during 30 days. It was noticed that when one worked with 35 mg KH{sub 2}PO{sub 4}/100 g soil, without adding nitrogen source, the OMR was 35%. Furthermore, it was noticed that the highest concentration of nitrogen and phosphorus was a limiting factor for microbial degradation and this resulted in the lowest OMR. At second, it was designed in aerobic bioreactor with 500 ml for 45 days and worked with the optimal concentrations of added phosphorus from the last stage. Although the assays have focused that nitrogen was not necessary to add to the soil, it was worked with 2,5 g (NH{sub 4}){sub 2}SO{sub 4}/100 g soil. The OMR was 46%, Oil and Grease removal was around 38% and TPH removal was around 45%. (author)

  19. Effects of subsoil compaction on hydraulic properties and preferential flow in a Swedish clay soil

    DEFF Research Database (Denmark)

    Mossadeghi-Björklund, M; Arvidsson, J.; Keller, Thomas;

    2016-01-01

    preferential transport derived from non-reactive tracer breakthrough curves and measurements of saturated hydraulic conductivity (Ks) and air permeability at the field moisture content (Ka). Although the traffic treatment did not cause any compaction effects at one of the two sites, it did result in significant......Soil compaction by vehicular traffic modifies the pore structure and soil hydraulic properties. These changes potentially influence the occurrence of preferential flow, which so far has been little studied. Our aim was to study the effect of compaction on soil hydraulic and transport properties in...... subsoil. A randomized block design trial at two sites on a well-structured clay soil in central Sweden was established. Plots with two levels of compaction were created at both sites, in the following referred to as trafficked and control. The trafficked treatment was created by 4 passes track-by-track with...

  20. Crop uptake and leaching losses of 15N labelled fertilizer nitrogen in relation to waterlogging of clay and sandy loam soils

    International Nuclear Information System (INIS)

    Ammonium nitrate fertilizer, labelled with 15N, was applied in spring to winter wheat growing in undisturbed monoliths of clay and sandy loam soil in lysimeters; the rates of application were respectively 95 and 102 kg N ha-1 in the spring of 1976 and 1975. Crops of winter wheat, oilseed rape, peas and barley grown in the following 5 or 6 years were treated with unlabelled nitrogen fertilizer at rates recommended for maximum yields. During each year of the experiments the lysimeters were divided into treatments which were either freely drained or subjected to periods of waterlogging. Another labelled nitrogen application was made in 1980 to a separate group of lysimeters with a clay soil and a winter wheat crop to study further the uptake of nitrogen fertilizer in relation to waterlogging. In the first growing season, shoots of the winter wheater at harvest contained 46 and 58% of the fertilizer nitrogen applied to the clay and sandy loam soils respectively. In the following year the crops contained a further 1-2% of the labelled fertilizer, and after 5 and 6 years the total recoveries of labelled fertilizer in the crops were 49 and 62% on the clay and sandy loam soils respectively. In the first winter after the labelled fertilizer was applied, less than 1% of the fertilizer was lost in the drainage water, and only about 2% of the total nitrogen (mainly nitrate) in the drainage water from both soils was derived from the fertilizer

  1. THE SIDE-EFFECT OF ORGANIC INSECTICIDE SPINOSAD ON BIOCHEMICAL AND MICROBIOLOGICAL PROPERTIES OF CLAY SOIL

    Directory of Open Access Journals (Sweden)

    Arkadiusz Telesiński

    2015-09-01

    Full Text Available The aim of the study was to determine the effect of spinosad on soil biochemical and microbiological properties. The experiment was carried out on sandy loam with Corg content 10.91 g·kg-l. Spinosad, as Spintor 240 SC was added into soil in dosages: a recommended field dosage, and fivefold, tenfold, and twenty-fivefold higher dosages. The amount of spinosad introduced into soil was between 12.55 and 313.75 g·kg-l. Moreover, soil samples without spinosad supplement were prepared as a reference. Respective Spintor 240 SC doses were converted into 1 kg soil, taking into account 10 cm depth. After application of insecticide water emulsions, soil moisture was brought to 60% maximum holding water capacity. The soil was thoroughly mixed and stored in tightly-closed polyethylene bags at 20 °C for a period 4 weeks. During the experiment dissipation of spinosad, soil enzymes (dehydrogenase, alkaline phosphatase, acid phosphatase, urease and number of bacteria, fungi, actinomycetes were assayed. Obtained results showed, that dissipation of spinosad in soil was relatively fast – the DT50 of this insecticide was ranged between 1.11 and 2.21 days. Spinosad residues had different effects on soil microbiological and biochemical properties. However, over time the impact of this insecticide definitely decreased. This indicated that the use of spinosad in organic farming, particularly in the field dosage, does not pose a long-term threat to the soil environment.

  2. Synthesis and Characterization of the Hybrid Clay- Based Material Montmorillonite-Melanoidin: A Potential Soil Model

    Energy Technology Data Exchange (ETDEWEB)

    V Vilas; B Matthiasch; J Huth; J Kratz; S Rubert de la Rosa; P Michel; T Schäfer

    2011-12-31

    The study of the interactions among metals, minerals, and humic substances is essential in understanding the migration of inorganic pollutants in the geosphere. A considerable amount of organic matter in the environment is associated with clay minerals. To understand the role of organic matter in the environment and its association with clay minerals, a hybrid clay-based material (HCM), montmorillonite (STx-1)-melanoidin, was prepared from L-tyrosine and L-glutamic acid by the Maillard reaction. The HCM was characterized by elemental analysis, nuclear magnetic resonance, x-ray photoelectron spectroscopy (XPS), scanning transmission x-ray microscopy (STXM), and thermal analysis. The presence of organic materials on the surface was confirmed by XPS and STXM. The STXM results showed the presence of organic spots on the surface of the STx-1 and the characterization of the functional groups present in those spots. Thermal analysis confirmed the existence of organic materials in the montmorillonite interlayer, indicating the formation of a composite of melanoidin and montmorillonite. The melanoidin appeared to be located partially between the layers of montmorillonite and partially at the surface, forming a structure that resembles the way a cork sits on the top of a champagne bottle.

  3. Sorption of water vapour by the Na+-exchanged clay-sized fractions of some tropical soil samples

    International Nuclear Information System (INIS)

    Water vapour sorption isotherms at 299K for the Na+-exchanged clay-sized (≤ 2μm e.s.d.) fraction of two sets of samples taken at three different depths from a tropical soil profile have been studied. One set of samples was treated (with H2O2) for the removal of much of the organic matter (OM); the other set (of the same samples) was not so treated. The isotherms obtained were all of type II and analyses by the BET method yielded values for the Specific Surface Areas (SSA) and for the average energy of adsorption of the first layer of adsorbate (Ea). OM content and SSA for the untreated samples were found to decrease with depth. Whereas removal of organic matter made negligible difference to the SSA of the top/surface soil, the same treatment produced a significant increase in the SSA of the samples taken from the middle and from the lower depths in the profile; the resulting increase was more pronounced for the subsoil. It has been deduced from these results that OM in the surface soil was less involved with the inorganic soil colloids than that in the subsoil. The increase in surface area which resulted from the removal of OM from the subsoil was most probably due to disaggregation. Values of Ea obtained show that for all the samples the adsorption of water vapour became more energetic after the oxidative removal of organic matter; the resulting ΔEa also increased with depth. This suggests that in the dry state, the ''cleaned'' surface of the inorganic soil colloids was more energetic than the ''organic-matter-coater surface''. These data provide strong support for the deduction that OM in the subsoil was in a more ''combined'' state than that in the surface soil. (author). 21 refs, 4 figs, 2 tabs

  4. Tensile behaviour of unsaturated compacted clay soils — A direct assessment method.

    OpenAIRE

    Stirling, R.A.; Hughes, P N; Davie, C. T.; Glendinning, S.

    2015-01-01

    This paper presents a new method for testing the behaviour of soils placed under tensile load and demonstrates its suitability for testing a number of soil types under various conditions including saturation, compaction and stabilisation. Validation of the results obtained for the soils at relatively low saturation has been conducted using the established Brazilian (indirect) test for measuring the tensile strength of brittle materials. A fair comparison has been found and the results highlig...

  5. Nutrient leaching potential following application of papermill lime-sludge to an acidic clay soil

    OpenAIRE

    S. C. Vettorazzo; F. C. S. Amaral; J. C. Chitolina

    2001-01-01

    This experiment was carried out under greenhouse conditions with soil pots during 210 days, to evaluate the effect of calcitic papermill lime-sludge application (at the rates 0, 773, 1.547, and 2.320 mg kg-1 or respective equivalents to control, 2, 4, and 6 t ha-1), on chemical composition of soil leachate and its effects on eucalypt growth and yield. Highest soil leachate pH, SO4, and Na concentrations occurred in the 4 and 6 t ha-1 treatments. Soil leachate nitrate concentrations decreased ...

  6. Movement of 14C-carbofuran in a silt clay soil. A laboratory study

    International Nuclear Information System (INIS)

    Carbofuran is used in the Syrian Arab Republic to control the sitona weevil, Sitona crinitus Herbst (S. macularius Marsch), on legume crops. It is sprayed on soil to kill the immature stages, which attack the leaves close to the soil surface and the nitrogen fixing nodes on the roots in the soil. A laboratory study was conducted to examine the movement of this pesticide into the soil. A known amount of 14C-carbofuran (specific activity of 2 μCi/mg) was applied to the top of the soil columns inside hard polyvinyl chloride (PVC) cylinders inserted into PVC tanks filled with soil of the same origin. The columns were sampled at varying intervals for up to 120 days. Each column was divided vertically from top to bottom into five zones. Each zone was 5 cm high. The radioactive residues were Soxhlet extracted for 6 hours. Extracts were concentrated and the aliquots counted for radioactivity using a liquid scintillation counter (LSC). In addition, samples of Soxhlet extracted soil were combusted in a biological oxidizer and the radioactivity was counted using LSC. The results show that recovery was good. Twenty-four hours after treatment the total radioactivity recovered was 71% of the total amount of insecticide applied. The major radioactive residues were confined to the top 5 cm of the soil column 24 hours after application. The amount of radioactive residues present in the lower layers increased gradually with time. However, this was accompanied by a relatively rapid and gradual loss in the total radioactivity recovered from the whole soil column. At the end of the experiment, most of the recovered radioactive residues (29%) were bound to the soil surface, whereas only 2% of the applied dose was extractable from the whole soil column. (author). 11 refs, 1 fig., 1 tab

  7. Innovative uses of organo-philic clays for remediation of soils, sediments and groundwater

    International Nuclear Information System (INIS)

    PCBs and similar low-solubility organic compounds continue to offer significant challenges in terrestrial and sediment remediation applications. While selective media such as granular activated carbon (GAC) have proven to be successful at absorbing soluble organics, these media may have reduced performance due to blinding in the presence of high molecular weight organic matter. An alternative technology addresses this problem with a clay-based adsorption media, which effectively and efficiently stabilizes low-solubility organic matter. OrganoclayTM reactive media utilizes granular sodium bentonite, which has been chemically modified to attract organic matter without absorbing water. The unique platelet structure of bentonite clays provides tremendous surface area and the capacity of the media to absorb over 60 percent of its own weight in organic matter. Because of these properties, organo-clays allow for several cost-effective in-situ remediation techniques, such as: - Flow-through filtration for removal of organic matter from aqueous solutions: Organoclay can be utilized as a fixed-bed media in a column operation. This specialty media offers a high efficient alternative to Granular Activated Carbon (GAC) when applied as a flow through media to remove oil, PCB and other low soluble organic contaminates from water. - Placement in a Reactive Core MatTM: Organoclay may be encapsulated into carrier textiles which are adhered together to create a thin reactive layer with high strength and even distribution of the reactive media. This type of delivery mechanism can be successfully applied in a sub aqueous or terrestrial environment for sediment capping applications - Permeable reactive barriers: Organoclay can deliver high sorption capacity, high efficiency, and excellent hydraulic conductivity as a passive reactive media in these applications. (authors)

  8. The Influence of Stress Treatments on the Microbial Biomass and the Rate of Decomposition of Humified Matter in Soils Containing Different Amounts of Clay

    DEFF Research Database (Denmark)

    Sørensen, Lasse Holst

    1983-01-01

    content of clay. The effect of the other treatments was largely the same in all 4 soils. The effect of the treatments towards the native biomass and humic matter was largely parallel to that on the labeled biomass. The observations are consistent with the view that the biomass as determined by fumigation...

  9. The effect of kauri (Agathis australis) on grain size distribution and clay mineralogy of andesitic soils in the Waitakere Ranges, New Zealand

    NARCIS (Netherlands)

    Jongkind, A.G.; Buurman, P.

    2006-01-01

    Kauri (Agathis australis) is generally associated with intense podzolisation, but little research has been carried out to substantiate this. We studied soil profiles, grain size distribution patterns and clay mineralogy under kauri and broadleaf/tree fern vegetation in the Waitakere Ranges, North Is

  10. Source zone remediation by ZVI-clay soil-mixing: Reduction of tetrachloroethene mass and mass discharge at a Danish DNAPL site

    DEFF Research Database (Denmark)

    Fjordbøge, Annika Sidelmann; Lange, Ida Vedel; Binning, Philip John;

    2012-01-01

    test was to document in situ destruction of the contaminant mass and the down-gradient response in contaminant mass discharge. The field sampling consisted of baseline measurements and a 19-month monitoring program (7 sampling campaigns) subsequent to the implementation of ZVI-Clay soil mixing. The...

  11. Evolution of the soil humus status on the calcareous Neogene clay dumps of the Sokolov quarry complex in the Czech Republic

    Czech Academy of Sciences Publication Activity Database

    Abakumov, E.V.; Frouz, Jan

    2009-01-01

    Roč. 42, č. 7 (2009), s. 718-724. ISSN 1064-2293 Grant ostatní: Russian Foundation for Basic Research(XE) 08-04-01128 Institutional research plan: CEZ:AV0Z60660521 Keywords : soil humus status * calcareous Neogene clay dumps * Sokolov quarry complex Subject RIV: EH - Ecology, Behaviour Impact factor: 0.222, year: 2009

  12. CLAY MINERALS AND THE ACCUMULATION OF SOIL ORGANIC MATTER IN NORTHWESTERN U.S. FORESTS

    Science.gov (United States)

    Globally soils are an important terrestrial reservoir of carbon, storing approximately 3 times the carbon held in vegetation and 2 times the amount contained in the atmosphere. With the potential for global climate change it is imperative that world soils continue to be a sink f...

  13. Removal of Pah from clay soil contaminated with diesel oil by bioremediation treatments

    International Nuclear Information System (INIS)

    Diesel oil is one of the most common soil organic pollutants, as a consequence of spilling of storage tank spills and accidental leaks. In Pernambuco State, Northeast part of Brazil, there are several evidences of soil contamination by petroleum derivates due to gas station leaking. (Author)

  14. Removal of Pah from clay soil contaminated with diesel oil by bioremediation treatments

    Energy Technology Data Exchange (ETDEWEB)

    Changas-spinelli, A. C. O.; Kato, M. T.; Lima, E. S.; Gavazza, S.

    2009-07-01

    Diesel oil is one of the most common soil organic pollutants, as a consequence of spilling of storage tank spills and accidental leaks. In Pernambuco State, Northeast part of Brazil, there are several evidences of soil contamination by petroleum derivates due to gas station leaking. (Author)

  15. Settling Velocity, Aggregate Stability, and Interrill Erodibility of Soils Varying in Clay Mineralogy

    Science.gov (United States)

    The relation of soil structural stability with soil erodibility depends on the mechanisms of aggregate disruption of different aggregate sizes and the measurement technique. In this study, we evaluated the relationship between settling velocity and stability of aggregates of different sizes, and int...

  16. Nematodes in clay colliery spoil dumps and experimentally introduced strips of meadow soil

    Czech Academy of Sciences Publication Activity Database

    Háněl, Ladislav

    České Budějovice : Institute of Soil Biology ASCR, 2005, s. 19-23. ISBN 80-86525-04-X. [Contributions to soil Zoology in Central Europe I. Central European Workshop on Soil Zoology /7./. České Budějovice (CZ), 14.04.2003-16.04.2003] R&D Projects: GA ČR(CZ) GA526/01/1055 Institutional research plan: CEZ:AV0Z6066911 Keywords : nematoda * trophic groups * landscape reclamation Subject RIV: EH - Ecology, Behaviour

  17. New Technique Assessment of Plastic Limit of Soft Clay Particularly Peat Soils

    OpenAIRE

    Adon, Rashidah; Yasufuku, Noriyuki; Ishikura, Ryohei; Wijeyesekera, Devapriya

    2013-01-01

    Plastic Limit (PL) is considered as the moisture content at which soil becomes too dry to remain plastic. Both the British Standards Institute (BS 1377 (1990)) and American Society for Testing and Materials (ASTM D4318 (2001)) are consistent with their proposition of determining PL as the moisture content when the soil crumbles upon rolling it to thread of 3 mm diameter. However for challenging soils such as peat which is naturally organic substance derived from the remains of plants, the “ro...

  18. Root-Zone Redox Dynamics - In Search for the Cause of Damage to Treated-Wastewater Irrigated Orchards in Clay Soils

    Science.gov (United States)

    Yalin, David; Shenker, Moshe; Schwartz, Amnon; Assouline, Shmuel; Tarchitzky, Jorge

    2016-04-01

    Treated wastewater (TW) has become a common source of water for agriculture. However recent findings raise concern regarding its use: a marked decrease (up to 40%) in yield appeared in orchards irrigated with TW compared with fresh water (FW) irrigated orchards. These detrimental effects appeared predominantly in orchards cultivated in clay soils. The association of the damage with clay soils rather than sandy soils led us to hypothesize that the damage is linked to soil aeration problems. We suspected that in clay soils, high sodium adsorption ratio (SAR) and high levels of organic material, both typical of TW, may jointly lead to an extreme decrease in soil oxygen levels, so as to shift soil reduction-oxidation (redox) state down to levels that are known to damage plants. Two-year continuous measurement of redox potential, pH, water tension, and oxygen were conducted in the root-zone (20-35 cm depth) of avocado trees planted in clay soil and irrigated with either TW or FW. Soil solution composition was sampled periodically in-situ and mineral composition was sampled in tree leaves and woody organs biannually. In dry periods the pe+pH values indicated oxic conditions (pe+pH>14), and the fluctuations in redox values were small in both TW and FW plots. Decreases in soil water tension following irrigation or rain were followed by drops in soil oxygen and pe+pH values. TW irrigated plots had significantly lower minimum pe+pH values compared with FW-irrigated plots, the most significant differences occurred during the irrigation season rather than the rain season. A linear correlation appeared between irrigation volume and reduction severity in TW-irrigated plots, but not in the FW plots, indicating a direct link to the irrigation regime in TW-irrigated plots. The minimum pe+pH values measured in the TW plots are indicative of suboxic conditions (9soil solution and in

  19. Clay:organic-carbon and organic carbon as determinants of the soil physical properties: reassessment of the Complexed Organic Carbon concept

    Science.gov (United States)

    Matter, Adrien; Johannes, Alice; Boivin, Pascal

    2016-04-01

    Soil Organic Carbon (SOC) is well known to largely determine the soil physical properties and fertility. Total porosity, structural porosity, aeration, structural stability among others are reported to increase linearly with increasing SOC in most studies. Is there an optimal SOC content as target in soil management, or is there no limit in physical fertility improvement with SOC? Dexter et al. (2008) investigated the relation between clay:SOC ratio and the physical properties of soils from different databases. They observed that the R2 of the relation between SOC and the physical properties were maximized when considering the SOC fraction limited to a clay:SOC ratio of 10. They concluded that this fraction of the SOC was complexed, and that the additional SOC was not influencing the physical properties as strongly as the complexed one. In this study, we reassessed this approach, on a database of 180 undisturbed soil samples collected from cambiluvisols of the Swiss Plateau, on an area of 2400 km2, and from different soil uses. The physical properties were obtained with Shrinkage Analysis, which involved the parameters used in Dexter et al., 2008. We used the same method, but detected biases in the statistical approach, which was, therefore, adapted. We showed that the relation between the bulk density and SOC was changing with the score of visual evaluation of the structure (VESS) (Ball et al., 2007). Therefore, we also worked only on the "good" structures according to VESS. All shrinkage parameters were linearly correlated to SOC regardless of the clay:SOC ratio, with R2 ranging from 0.45 to 0.8. Contrarily to Dexter et al. (2008), we did not observed an optimum in the R2 of the relation when considering a SOC fraction based on the clay:SOC ratio. R2 was increasing until a Clay:SOC of about 7, where it reached, and kept, its maximum value. The land use factor was not significant. The major difference with the former study is that we worked on the same soil group

  20. Nutrient leaching potential following application of papermill lime-sludge to an acidic clay soil

    Directory of Open Access Journals (Sweden)

    S. C. Vettorazzo

    2001-09-01

    Full Text Available This experiment was carried out under greenhouse conditions with soil pots during 210 days, to evaluate the effect of calcitic papermill lime-sludge application (at the rates 0, 773, 1.547, and 2.320 mg kg-1 or respective equivalents to control, 2, 4, and 6 t ha-1, on chemical composition of soil leachate and its effects on eucalypt growth and yield. Highest soil leachate pH, SO4, and Na concentrations occurred in the 4 and 6 t ha-1 treatments. Soil leachate nitrate concentrations decreased with increasing lime-sludge rate. Soil leachate phosphate remained low (below the detection limit in all treatments until 120 days, while the concentration increased in the lime-sludge treatments at 210 days (last sampling in about 600 mg L-1. Lime-sludge decreased leachate Mg concentration, but had no significant effect among rates. Soil leachate Ca, K, B, Cu, Fe, and Zn did not change significantly for any lime-sludge application rates. The maximum NO3, Ca, Mg, K, and Na concentrations in the soil leachate occurred at 60 days after lime-sludge application (leaching equivalent to 1 pore volume, but for pH and SO4, the maximum occurred at 210 days (leaching equivalent to 4 pore volumes. Lime-sludge application decreased the concentration of exchangeable Al in the soil. Plant diameter growth and dry matter yield were increased with increasing lime-sludge rate. Beneficial effects on mineral nutrition (P, K, Ca, B, and Zn of eucalypts were also obtained by the application of 4 and 6 t ha-1 of lime-sludge.

  1. A mechanistic study of arsenate removal from artificially contaminated clay soils by electrokinetic remediation.

    Science.gov (United States)

    Suzuki, Tasuma; Moribe, Mai; Okabe, Yohhei; Niinae, Masakazu

    2013-06-15

    Batch desorption experiments and bench-scale electrokinetic experiments were performed to elucidate the electrokinetic remediation mechanisms of arsenate from artificially contaminated kaolinite. The electrokinetic experiments in which a constant voltage was applied demonstrated that high soil pH favored arsenate remediation with respect to both the remediation time and electricity consumption. It was also demonstrated that applying a pulse voltage (1 h ON, 1 h OFF) significantly improved the electricity consumption efficiency when the soil pH was maintained at the initial value during the experiments; this trend was not observed when the soil pH was gradually increased from the cathode side. These electrokinetic experimental results, with the support of arsenate desorption data obtained from batch experiments, indicate that the remediation rate-limiting step varied with soil pH. When the soil pH was maintained at the initial value of 7.2 during the experiments, arsenate desorption was the remediation rate-limiting step rather than the migration of dissolved arsenate toward the anode. Conversely, when the cathode pH was not controlled and the soil pH was correspondingly increased gradually from the cathode side, the migration of hydroxyl and desorbed arsenate ions toward the anode played a more important role in the control of the overall remediation efficiency. PMID:23643955

  2. An Improved Description of the Seismic Response of Sites with High Plasticity Soils, Organic Clays, and Deep Soft Soil Deposits

    OpenAIRE

    Carlton, Brian

    2014-01-01

    Near surface soils can greatly influence the amplitude, duration, and frequency content of ground motions. The amount of their influence depends on many factors, such as the geometry and engineering properties of the soils and underlying bedrock, as well as the earthquake source mechanism and travel path. Building codes such as the 2012 International Building Code (IBC) define six site categories for seismic design of structures, which are based on the sites defined by the National Earthqua...

  3. Primary succession of soil rotifers in clays of brown coal post-mining dumps

    Czech Academy of Sciences Publication Activity Database

    Devetter, Miloslav; Frouz, J.

    2011-01-01

    Roč. 96, č. 2 (2011), s. 164-174. ISSN 1434-2944 R&D Projects: GA MŠk 2B08023 Institutional research plan: CEZ:AV0Z60660521 Keywords : soil rotifers * post mining dumps * primary succession Subject RIV: EH - Ecology, Behaviour Impact factor: 1.190, year: 2011

  4. Improvement of Soil Moisture Retrieval from Hyperspectral VNIR-SWIR Data Using Clay Content Information: From Laboratory to Field Experiments

    Directory of Open Access Journals (Sweden)

    Rosa Oltra-Carrió

    2015-03-01

    Full Text Available The aim of this work is to study the constraints and performance of SMC retrieval methodologies in the VNIR (Visible-Near InfraRed and SWIR (ShortWave InfraRed regions (from 0.4 to 2.5 µm when passing from controlled laboratory conditions to field conditions. Five different approaches of signal processing found in literature were considered. Four local criteria are spectral indices (WISOIL, NSMI, NINSOL and NINSON. These indices are the ratios between the spectral reflectances acquired at two specific wavelengths to characterize moisture content in soil. The last criterion is based in the convex hull concept and it is a global method, which is based on the analysis of the full spectral signature of the soil. The database was composed of 464 and 9 spectra, respectively, measured over bare soils in laboratory and in-situ. For each measurement, SMC and texture were well-known and the database was divided in two parts dedicated to calibration and validation steps. The calibration part was used to define the empirical relation between SMC and SMC retrieval approaches, with coefficients of determination (R2 between 0.72 and 0.92. A clay content (CC dependence was detected for the NINSOL and NINSON indices. Consequently, two new criteria were proposed taking into account the CC contribution (NINSOLCC and NINSONCC. The well-marked regression between SMC and global/local indices, and the interest of using the CC, were confirmed during the validation step using laboratory data (R² superior to 0.76 and Root mean square errors inferior to 8.3% m3∙m−3 in all cases and using in-situ data, where WISOIL, NINSOLCC and NINSONCC criteria stand out among the NSMI and CH.

  5. Carbon storage in a heavy clay soil landfill site after biosolid application

    International Nuclear Information System (INIS)

    Applying organic amendments including biosolids and composts to agricultural land could increase carbon (C) storage in soils and contribute significantly to the reduction of greenhouse gas emissions. Although a number of studies have examined the potential value of biosolids as a soil conditioner and nutrient source, there has been only limited work on the impact of biosolid application on C sequestration in soils. The objective of this study was to examine the potential value of biosolids in C sequestration in soils. Two types of experiments were conducted to examine the effect of biosolid application on C sequestration. In the first laboratory incubation experiment, the rate of decomposition of a range of biosolid samples was compared with other organic amendments including composts and biochars. In the second field experiment, the effect of biosolids on the growth of two bioenergy crops, Brassica juncea (Indian mustard) and Helianthus annuus (sunflower) on a landfill site was examined in relation to biomass production and C sequestration. The rate of decomposition varied amongst the organic amendments, and followed: composts > biosolids > biochar. There was a hundred fold difference in the rate of decomposition between biochar and other organic amendments. The rate of decomposition of biosolids decreased with increasing iron (Fe) and aluminum (Al) contents of biosolids. Biosolid application increased the dry matter yield of both plant species (by 2–2.5 fold), thereby increasing the biomass C input to soils. The rate of net C sequestration resulting from biosolid application (Mg C ha−1 yr−1 Mg−1 biosolids) was higher for mustard (0.103) than sunflower (0.087). Biosolid application is likely to result in a higher level of C sequestration when compared to other management strategies including fertilizer application and conservation tillage, which is attributed to increased microbial biomass, and Fe and Al oxide-induced immobilization of C. - Graphical

  6. Carbon storage in a heavy clay soil landfill site after biosolid application

    Energy Technology Data Exchange (ETDEWEB)

    Bolan, N.S., E-mail: Nanthi.Bolan@unisa.edu.au [Centre for Environmental Risk Assessment and Remediation (CERAR), University of South Australia, SA 5095 (Australia); Cooperative Research Centre for Contaminants Assessment and Remediation of the Environment (CRC CARE), University of South Australia, SA 5095 (Australia); Kunhikrishnan, A. [Chemical Safety Division, Department of Agro-Food Safety, National Academy of Agricultural Science, Suwon-si, Gyeonggi-do 441-707 (Korea, Republic of); Naidu, R. [Centre for Environmental Risk Assessment and Remediation (CERAR), University of South Australia, SA 5095 (Australia); Cooperative Research Centre for Contaminants Assessment and Remediation of the Environment (CRC CARE), University of South Australia, SA 5095 (Australia)

    2013-11-01

    Applying organic amendments including biosolids and composts to agricultural land could increase carbon (C) storage in soils and contribute significantly to the reduction of greenhouse gas emissions. Although a number of studies have examined the potential value of biosolids as a soil conditioner and nutrient source, there has been only limited work on the impact of biosolid application on C sequestration in soils. The objective of this study was to examine the potential value of biosolids in C sequestration in soils. Two types of experiments were conducted to examine the effect of biosolid application on C sequestration. In the first laboratory incubation experiment, the rate of decomposition of a range of biosolid samples was compared with other organic amendments including composts and biochars. In the second field experiment, the effect of biosolids on the growth of two bioenergy crops, Brassica juncea (Indian mustard) and Helianthus annuus (sunflower) on a landfill site was examined in relation to biomass production and C sequestration. The rate of decomposition varied amongst the organic amendments, and followed: composts > biosolids > biochar. There was a hundred fold difference in the rate of decomposition between biochar and other organic amendments. The rate of decomposition of biosolids decreased with increasing iron (Fe) and aluminum (Al) contents of biosolids. Biosolid application increased the dry matter yield of both plant species (by 2–2.5 fold), thereby increasing the biomass C input to soils. The rate of net C sequestration resulting from biosolid application (Mg C ha{sup −1} yr{sup −1} Mg{sup −1} biosolids) was higher for mustard (0.103) than sunflower (0.087). Biosolid application is likely to result in a higher level of C sequestration when compared to other management strategies including fertilizer application and conservation tillage, which is attributed to increased microbial biomass, and Fe and Al oxide-induced immobilization of C

  7. Influence of climate and eolian dust on the major-element chemistry and clay mineralogy of soils in the northern Bighorn basin, U.S.A.

    Science.gov (United States)

    Reheis, M.C.

    1990-01-01

    Soil chronosequences in the northern Bighorn basin permit the study of chronologic changes in the major-element chemistry and clay mineralogy of soils formed in different climates. Two chronosequences along Rock Creek in south-central Montana formed on granitic alluvium in humid and semiarid climates over the past two million years. A chronosequence at the Kane fans in north-central Wyoming formed on calcareous alluvium in an arid climate over the past 600,000 years. Detailed analyses of elemental chemistry indicate that the soils in all three areas gradually incorporated eolian dust that contained less zirconium, considered to be chemically immobile during weathering, than did the alluvium. B and C horizons of soils in the wettest of the chronosequences developed mainly at logarithmic rates, suggesting that leaching, initially rapid but decelerating, dominated the dust additions. In contrast, soils in the most arid of the chronosequences developed at linear rates that reflect progressive dust additions that were little affected by leaching. Both weathering and erosion may cause changes with time to appear logarithmic in A horizons of soils under the moist and semiarid climatic regimes. Clay minerals form with time in the basal B and C horizons and reflect climatic differences in the three areas. Vermiculite, mixed-layer illite-smectite, and smectite form in the soils of the moist-climate chronosequence; smectite forms in the semiarid-climate chronosequence; and smectite and palygorskite form in the arid-climate chronosequence. ?? 1990.

  8. Aspects of the X-ray identification of swelling clay minerals in soils and sediments

    International Nuclear Information System (INIS)

    Despite the interest in and necessity for identifying swelling clay minerals of the smectite group because of their economic importance, routine investigation by conventional X-ray diffraction methods seldom includes any attempt to identify the sub-group or species of smectite. The more important techniques for achieving such identification are examined with special reference to the Greene-Kelly test and intercalation with alkylammonium chlorides. The Greene-Kelly test can only be used for dioctahedral species and stevensite and fails to distinguish between montmorillonite and beidellite in a manner consistent with the internationally recognised definitions for these species based on layer charge. A better differentiation of species is achieved by the alkylammonium chloride method, but the effort involved makes routine application unattractive unless an abbreviated version is applied, in which case, however, the presence of chlorite may produce an ambiguos result. There are, nevertheless, distinct advantages to the use of this method, both in obtaining an identification of smectite species which is most consistent with definition, and in being able to predict the usefulness of a particular smectite for certain types of industrial application

  9. Effect of blade vibration on mulch tillage performance under silt clay loam soil

    Directory of Open Access Journals (Sweden)

    B Goudarzi

    2015-09-01

    Full Text Available Introduction: Mulch tillage system is an intermediate system which covers some of disadvantages of no tillage and conventional tillage systems. In farms in which tillage is done with a chisel plow, runoff and soil erosion have a less important relation to moldboard and disk plow and naturally absorption of rainfall will be developed. Thus, the mulch tillage system is an appropriate alternative to conventional tillage and no tillage (Backingham and Pauli, 1993. The unwanted vibration in machinery and industry mainly processes most harmful factors, for example: bearing wear, cracking and loosening joints. And noise is produced in electrical systems by creating a short circuit (Wok, 2011. Self-induced and induced vibration are used in tillage systems. Induced vibration is created by energy consumption and self-induced vibration is created by collision among the blades and soil at the shank (Soeharsono and Setiawan, 2010. A study by Mohammadi-gol et al. (2005 was conducted. It was found that on the disk plow, plant residues maintained on the soil are more than that of moldboard plow. 99% frequency and amplitude, speed and rack angle of blade directly affect soil inversion and indirectly affect preservation of crop residue on the soil. The effect of vibration frequency and rack angle of blade to reduce the tensile strength is also clear. Moreover, in contrast to previous studies when speed progressing is less than (λ, not only the relative speed (λ, but also frequency can reduce the tensile strength (Beiranvand and Shahgoli, 2010; Awad-Allah et al., 2009. Therefore, aim of this study was to determine the effect of vibration and the speed of tillage on soil parameters and drawbar power in using electric power. Materials and Methods: To perform this test, three different modes of vibration (fixed, variable and induced vibration and two levels of speed in real terms at a depth of 20 cm were used for farming. The test was performed with a split plot

  10. Transport, sorption and degradation of atrazine in two clay soils from Mexico : Andosol and Vertisol

    OpenAIRE

    Prado, B.; Duwig, Céline; Hidalgo, C; Muller, K.; de Mora, L.; Raymundo, E.; Etchevers, J.D.

    2014-01-01

    Although atrazine has been banned in the European Union, it is still one of the most widely used herbicides in the world. It is has been detected in surface and groundwater and has been shown to be associated with major human health problems. Atrazine fate in the environment, e.g. sorption, leaching and degradation depends, inter alia, on soil characteristics. Independent static and dynamic experiments were conducted to identify and uncouple the processes governing the fate of atrazine. Two a...

  11. Performance of a Bentleg Subsoiler with Shallow Tines in a Clay Soil

    OpenAIRE

    M. H. Raoufat; M. Kazemi Najaf Abadi

    2007-01-01

    The present research was intended to alleviate the problems and costs of deep tilling in sugarcane production in Mian-Ab sugarcane farms located in Khuzestan province, Iran. The main objective was to investigate the feasibility of subsoiling operations with bentleg subsoiler (BLS) equipped with shallow tines, a combination expected to increase the critical depth resulting in less power consumption and improved soil physical conditions. Six treatments arranged in a completely randomized block ...

  12. Natural clay based soil as an effective barrier against radionuclide migration in a uranium tailings structure

    International Nuclear Information System (INIS)

    Olympic Dam Operations mines and processes copper, uranium, silver and gold from a vast underground ore body located in the far north of South Australia. The tailings from the milling operation are pumped at the current rate of 2.3 million tonnes annually into an above ground Tailings Retention System (TRS) covering an area of 180 hectares. Initial studies conducted at a small scale pilot plant TRS in 1985 indicated that contaminants in the acid based tailings were reduced to background levels within a short distance after the tailings/soil interface. This study was commenced to confirm the effectiveness of the natural soils at the base of the current TRS in preventing downward migration of radionuclides. Core samples have been taken at a number of locations, and radionuclide concentrations plotted against depth. Results from the core samples taken to date have confirmed that downward radionuclide movement is effectively stopped within the first 40 centimeters after the tailings/soil interface. 5 refs., 1 tab., 7 figs

  13. Use of a flashiness index to predict phosphorus losses from subsurface drains on a Swedish farm with clay soils

    Science.gov (United States)

    Ulén, Barbro; Stenberg, Maria; Wesström, Ingrid

    2016-02-01

    Risk assessment for elevated leaching losses of phosphorus (P) from agricultural land is commonly based on indices, since such losses are highly episodic and difficult to predict. Here a flashiness index (FI) representing changes in daily water flow from drainage systems was estimated from measured discharge (agrohydrological years 2004-2013) after reconstruction of subsurface drainage systems in 16 fields on a former swine farm. The fields were analysed for ammonium lactate-extractable soil P (P-AL), clay, carbon and other soil parameters in 2004. Transport of total P (TP), dissolved reactive P (DRP) and unreactive P (UP) was estimated from concentrations in composite water samples taken flow-proportionally up to 20 times per year. On average, 2.20 kg TP ha-1 yr-1 was leached, with 27% in DRP form, from the entire farm. FI was significantly negatively correlated (Pearson correlation coefficient p < 0.05) to mean yearly discharge from each field. Stepwise regression demonstrated that FI index was the most important single explanatory parameter for flow-proportional yearly mean concentration of unreactive P losses (UP) from each field, with a coefficient of determination (r2) of 0.67. The corresponding concentration of dissolved reactive P (DRP) was significantly positively correlated (p = 0.015) to soil P-AL and FI. A regression model for TP leaching losses based on FI, P-AL and yearly discharge (Q) from 11 of the fields over nine years (r2 = 0.67, p = 0.002) was validated against TP leaching from the remaining five fields (32% of farm area). Root mean square error (RMSE) was 0.43, which represented 20% of measured leaching (mean 2.14 kg TP ha-1 yr-1). For individual years, RMSE for different fields was 37-80% of measured TP leaching (0.8-3.7 kg TP ha-1 yr-1). The FI index could be used together with soil P test to predict P leaching from individual fields of a drained farm.

  14. The influence of clay-to-carbon ratio on soil physical properties in a humid sandy loam soil with contrasting tillage and residue management

    DEFF Research Database (Denmark)

    Getahun, Gizachew Tarekegn; Munkholm, Lars Juhl; Schjønning, Per

    2016-01-01

    × SOC according to Dexter et al. (2008). NCC was a better predictor of dispersible clay than total clay and SOC at all depths in natural aggregates, while tensile strength and derived parameters were generally better explained by the total amount of clay in remoulded aggregates. Remoulded aggregates had...

  15. In-situ studies on the performance of landfill caps (compacted soil liners, geomembranes, geosynthetic clay liners, capillary barriers)

    Energy Technology Data Exchange (ETDEWEB)

    Melchior, S. [IGB - Ingenieurbuero fuer Grundbau, Hamburg (Germany)

    1997-12-31

    Since 1986 different types of landfill covers have been studied in-situ on the Georgswerder landfill in Hamburg, Germany. Water balance data are available for eight years. The performance of different carriers has been measured by collecting the leakage on areas ranging from 100 m{sup 2} to 500 m{sup 2}. Composite liners with geomembranes performed best, showing no leakage. An extended capillary barrier also performed well. The performance of compacted soil liners, however, decreased severely within five years due to desiccation, shrinkage and plant root penetration (liner leakage now ranging from 150 mm/a to 200 mm/a). About 50 % of the water that reaches the surface of the liner is leaking through it. The maximum leakage rates have increased from 2 x 10{sup -10} m{sup 3} m{sup -2} s{sup -1} to 4 x 10{sup -8} m{sup 3} m{sup -2} s{sup -1}. Two types of geosynthetic clay liners (GCL) have been tested for two years now with disappointing results. The GCL desiccated during the first dry summer of the study. High percolation rates through the GCL were measured during the following winter (45 mm resp. 63 mm in four months). Wetting of the GCL did not significantly reduce the percolation rates.

  16. In-situ studies on the performance of landfill caps (compacted soil liners, geomembranes, geosynthetic clay liners, capillary barriers)

    International Nuclear Information System (INIS)

    Since 1986 different types of landfill covers have been studied in-situ on the Georgswerder landfill in Hamburg, Germany. Water balance data are available for eight years. The performance of different carriers has been measured by collecting the leakage on areas ranging from 100 m2 to 500 m2. Composite liners with geomembranes performed best, showing no leakage. An extended capillary barrier also performed well. The performance of compacted soil liners, however, decreased severely within five years due to desiccation, shrinkage and plant root penetration (liner leakage now ranging from 150 mm/a to 200 mm/a). About 50 % of the water that reaches the surface of the liner is leaking through it. The maximum leakage rates have increased from 2 x 10-10 m3 m-2 s-1 to 4 x 10-8 m3 m-2 s-1. Two types of geosynthetic clay liners (GCL) have been tested for two years now with disappointing results. The GCL desiccated during the first dry summer of the study. High percolation rates through the GCL were measured during the following winter (45 mm resp. 63 mm in four months). Wetting of the GCL did not significantly reduce the percolation rates

  17. Sedimentos arcillosos en un suelo del valle inferior del río Colorado (Argentina Clay sediments in a soil of the lower Colorado river valley (Argentina

    Directory of Open Access Journals (Sweden)

    Norman Peinemann

    2008-12-01

    Full Text Available Se describe la presencia de capas sedimentarias ricas en minerales de arcilla en un subsuelo del valle inferior del río Colorado por su importancia para el régimen hídrico de suelos bajo riego. Difractogramas de rayos X efectuados sobre la fracción arcilla fina de estos sedimentos revelaron que está compuesta por smectitas con muy buena cristalización. La caracterización fisicoquímica del perfil de suelo mostró que el fuerte incremento de minerales de arcilla en el subsuelo estuvo vinculado con un aumento de pH y PSI y en consecuencia una marcada disminución en la conductividad hidráulica, motivo por el cual la eventual presencia de estas capas sedimentarias debe ser muy tenida en cuenta en la programación de las prácticas de riego para evitar el posible deterioro de los suelos.The presence of sedimentary clay layers in subsoils of the lower Colorado river valley are described due to their impact on the water balance of soils under irrigation. X-ray difractograms of the fine clay fraction of these sediments show that they are composed of smectites with a very good crystallization. The physicochemical characterization of the soil profile indicates that the abrupt increase of clay minerals was associated with high pH and ESP values as well as a sharp decrease in hydraulic conductivity. Therefore, the presence of sedimentary clay layers in soils has to be considered when planning irrigation practices to avoid soil degradation.

  18. Selenium bioavailability and uptake as affected by four different plants in a loamy clay soil with particular attention to mycorrhizae inoculated ryegrass

    International Nuclear Information System (INIS)

    The aim of this study was to investigate the influence of plant species, especially of their rhizosphere soil, and of inoculation with an arbuscular mycorrhizal (AM) fungus on the bioavailability of selenium and its transfer in soil-plant systems. A pot experiment was performed with a loamy clay soil and four plant species: maize, lettuce, radish and ryegrass, the last one being inoculated or not with an arbuscular mycorrhizal fungus (Glomus mosseae). Plant biomass and Se concentration in shoots and roots were estimated at harvest. Se bioavailability in rhizosphere and unplanted soil was evaluated using sequential extractions. Plant biomass and selenium uptake varied with plant species. The quantity of rhizosphere soil also differed between plants and was not proportional to plant biomass. The highest plant biomass, Se concentration in plants, and soil to plant transfer factor were obtained with radish. The lowest Se transfer factors were obtained with ryegrass. For the latter, mycorrhizal inoculation did not significantly affect plant growth, but reduced selenium transfer from soil to plant by 30%. In unplanted soil after 65 days aging, more than 90% of added Se was water-extractable. On the contrary, Se concentration in water extracts of rhizosphere soil represented less than 1% and 20% of added Se for ryegrass and maize, respectively. No correlation was found between the water-extractable fraction and Se concentration in plants. The speciation of selenium in the water extracts indicated that selenate was reduced, may be under organic forms, in the rhizosphere soil

  19. Selenium bioavailability and uptake as affected by four different plants in a loamy clay soil with particular attention to mycorrhizae inoculated ryegrass

    Energy Technology Data Exchange (ETDEWEB)

    Munier-Lamy, C. [LIMOS, UMR 7137 CNRS-Nancy University, Faculty of Sciences, P.O. Box 239, F-54506 Vandoeuvre-les-Nancy Cedex (France)], E-mail: colette.munier@limos.uhp-nancy.fr; Deneux-Mustin, S. [LIMOS, UMR 7137 CNRS-Nancy University, Faculty of Sciences, P.O. Box 239, F-54506 Vandoeuvre-les-Nancy Cedex (France); Mustin, C. [LIMOS, UMR 7137 CNRS-Nancy University, Faculty of Sciences, P.O. Box 239, F-54506 Vandoeuvre-les-Nancy Cedex (France)], E-mail: christian.mustin@limos.uhp-nancy.fr; Merlet, D. [LIMOS, UMR 7137 CNRS-Nancy University, Faculty of Sciences, P.O. Box 239, F-54506 Vandoeuvre-les-Nancy Cedex (France)], E-mail: denis.merlet@limos.uhp-nancy.fr; Berthelin, J. [LIMOS, UMR 7137 CNRS-Nancy University, Faculty of Sciences, P.O. Box 239, F-54506 Vandoeuvre-les-Nancy Cedex (France)], E-mail: jacques.berthelin@limos.uhp-nancy.fr; Leyval, C. [LIMOS, UMR 7137 CNRS-Nancy University, Faculty of Sciences, P.O. Box 239, F-54506 Vandoeuvre-les-Nancy Cedex (France)], E-mail: corinne.leyval@limos.uhp-nancy.fr

    2007-10-15

    The aim of this study was to investigate the influence of plant species, especially of their rhizosphere soil, and of inoculation with an arbuscular mycorrhizal (AM) fungus on the bioavailability of selenium and its transfer in soil-plant systems. A pot experiment was performed with a loamy clay soil and four plant species: maize, lettuce, radish and ryegrass, the last one being inoculated or not with an arbuscular mycorrhizal fungus (Glomus mosseae). Plant biomass and Se concentration in shoots and roots were estimated at harvest. Se bioavailability in rhizosphere and unplanted soil was evaluated using sequential extractions. Plant biomass and selenium uptake varied with plant species. The quantity of rhizosphere soil also differed between plants and was not proportional to plant biomass. The highest plant biomass, Se concentration in plants, and soil to plant transfer factor were obtained with radish. The lowest Se transfer factors were obtained with ryegrass. For the latter, mycorrhizal inoculation did not significantly affect plant growth, but reduced selenium transfer from soil to plant by 30%. In unplanted soil after 65 days aging, more than 90% of added Se was water-extractable. On the contrary, Se concentration in water extracts of rhizosphere soil represented less than 1% and 20% of added Se for ryegrass and maize, respectively. No correlation was found between the water-extractable fraction and Se concentration in plants. The speciation of selenium in the water extracts indicated that selenate was reduced, may be under organic forms, in the rhizosphere soil.

  20. Molecular modelling studies of clay-exopolysaccharide complexes: Soil aggregation and water retention phenomena

    International Nuclear Information System (INIS)

    In soils, the bacterial exopolysaccharides (EPS) aggregate mineral particles, enhancing their cohesion and their ability to retain water. These phenomena have been studied at the atomic scale by molecular modelling; we have considered seven rhizospheric polysaccharides interacting with the basal surfaces of montmorillonite. Models accounted for the aggregation phenomena induced by EPS: some segments of the polysaccharide were adsorbed on the mineral surfaces while others formed loops and bridges linking two surfaces. Adsorption energies were favourable and depended mostly on the interacting area. Cohesion of aggregates was estimated by the adhesion work, predicted values differed from one EPS to the other, suggesting that the chemical structure influences interaction strength with the mineral surface. Mechanisms of water uptake and release have also been investigated: hydration energies revealed that EPS strongly retain water at low water concentrations.

  1. Potential for Recycling Nutrients from Biosolids Amended with Clay and Lime in Coarse-Textured Water Repellence, Acidic Soils of Western Australia

    Directory of Open Access Journals (Sweden)

    Sanjutha Shanmugam

    2015-01-01

    Full Text Available Application of biosolids in soils is an efficient method of recycling nutrients from biosolids and it is considered even safer when it is modified after mixing and diluting with other suitable soil organic amendments. A variety of soil organic amendments, such as green manures and composts, are used for modifying and co-composting with biosolids. However, these may not be considered as appropriate biosolids disposal and remedial measures for soils with unique problems such as low soil pH, water repellence nature, and poor water and nutrient retention capacities due to soil textural issues. Historically, soil amendments such as lime, clay, and recently biochar are being applied for such problematic soils at Western Australia and these researches focused mostly on improvement in soil physical and chemical properties. However, studies with potential for applying modified biosolids with these amendments are not complete yet. This review focused on identifying such gaps in these studies from over 170 peer-reviewed key research and review articles published over decades to latest in these areas.

  2. Microbial assimilation of 14C of ground and unground plant materials decomposing in a loamy sand and a clay soil

    DEFF Research Database (Denmark)

    Sørensen, P.; Ladd, J.N.; Amato, M.

    1996-01-01

    The influence of grinding plant materials on the microbial decomposition and the distribution of plant-derived carbon in soil was measured. Ground and unground, C-14-labelled subclover leaves (Trifolium subterraneum) were added to a loamy sand and clay soil and incubated for 42 d at 25 degrees C....... More C-14 and N were mineralized and less microbial biomass C-14 accumulated in soils amended with unground than with ground subclover leaves. Differences in the amounts of (CO2)-C-14 and biomass C-14 were established during the initial 7 days of decomposition. At this time, biomass C-14 in the two...... rate of evolution of (CO2)-C-14 was least from glucose. Thus, the glucose-derived residual C-14, which was mainly present in microbial biomass, was to a higher degree retained in soil than residual C-14 from the decomposing plant materials. It is suggested that grinding of plant materials favours, on...

  3. Clay minerals and sedimentary basin history

    OpenAIRE

    Merriman, Richard J.

    2005-01-01

    Clay minerals in the mud and soil that coat the Earth's surface are part of a clay cycle that breaks down and creates rock in the crust. Clays generated by surface weathering and shallow diagenetic processes are transformed into mature clay mineral assemblages in the mudrocks found in sedimentary basins. During metamorphism, the release of alkali elements and boron from clay minerals generates magmas that are subsequently weathered and recycled, representing the magma-to-mud pathway of the cl...

  4. Clay Houses

    Science.gov (United States)

    Pedro, Cathy

    2011-01-01

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

  5. Radionuclides in milk of dairy heifers raised on forages harvested from phosphatic clay soils on reclaimed mined land

    International Nuclear Information System (INIS)

    Alfalfa (AR; Medicago sativa L.) and corn (CSR; Zea mays L.) were grown in phosphatic clay soils on phosphate-mined reclaimed land in central Florida. Corn (CSC) also was grown on unmined land and served as a control forage. Upon harvesting, plants were chopped and ensiled. Concentrations of 226Ra averaged 2.44, 0.26 and 0.15; 210Pb averaged 1.04, 0.63, and 0.52; and 210Po averaged 1.59, 0.59, and 1.26 Bq kg-1 DM for AR, CSR, and CSC, respectively. These forages were fed separately to Holstein dairy replacement heifers (Bos taurus) (n=15 per forage) from approximately 9 to 25 mo of age. Heifers gave birth to calves at approximately 24 mo of age. Samples of milk were collected on d 1, 15, and 30 of lactation and analyzed for radionuclides. Averaged across sampling days, heifers fed AR had greater milk concentrations of 226Ra compared with those fed CSR (0.27 vs. 0.22 Bq kg-1 DM; P -1 DM; P 210Po compared with heifers fed CSR (0.58 vs. 0.30 Bq kg-1 DM; P -1 DM). Lead-210 was greater in milk from heifers fed CSR compared with those fed AR or CSC (1.38 vs. 0.94 and 0.92 Bq kg-1 DM; P < 0.13), respectively. Plasma S and Cu concentrations suggested subclinical molybdenosis in heifers fed AR. However, all heifers grew at an acceptable rate, conceived normally, had normal gestation periods, gave high quality colostrum at calving, and produced similar amounts of milk. 17 refs., 9 tabs

  6. Field experiments of Controlled Drainage of agricultural clay soils show positive effects on water quantity (retention, runoff) and water quality (nitrate leaching).

    Science.gov (United States)

    schipper, peter; stuyt, lodewijk; straat, van der, andre; schans, van der, martin

    2014-05-01

    Despite best management practices, agriculture is still facing major challenges to reduce nutrients leaching to the aquatic environment. In deltas, most of total nutrient losses from artificially drained agricultural soils are discharged via drains. Controlled drainage is a promising measure to prevent drainage of valuable nutrients, improve water quality and agricultural yield and adapt to climate change (reduce peak runoff, manage water scarcity and drought). In The Netherlands, this technique has attracted much attention by water managers and farmers alike, yet field studies to determine the expected (positive) effects for Dutch conditions were scarce. Recently, a field experiment was set up on clay soils. Research questions were: how does controlled, subsurface drainage perform on clay soils? Will deeper tile drains function just as well? What are the effects on drain water quality (especially with respect to nitrogen and salt) and crop yield? An agricultural field on clay soils was used to test different tile drainage configurations. Four types of tile drainage systems were installed, all in duplicate: eight plots in total. Each plot has its own outlet to a control box, where equipment was installed to control drain discharge and to measure the flow, concentrations of macro-ions, pH, nitrogen, N-isotopes and heavy metals. In each plot, groundwater observation wells and suction cups are installed in the saturated and vadose zones, at different depths, and crop yield is determined. Four plots discharge into a hydrologic isolated ditch, enabling the determination of water- and nutrient balances. Automatic drain water samplers and innovative nitrate sensors were installed in four plots. These enable identification and unravelling so-called first flush effects (changes in concentrations after a storm event). Water-, chloride- and nitrogen balances have been set up, and the interaction between groundwater and surface water has been quantified. The hydrological

  7. Hydraulic Anisotropy Characterization Using Azimuthal Self Potential Gradient [ASPG]: Results from Pneumatic Fracturing of Tight Clay Soils

    Science.gov (United States)

    Slater, L.; Wishart, D.; Schnell, D.; Hermann, G.

    2008-12-01

    Recent studies have shown that bulk hydraulic anisotropy associated with fractures in fractured rock aquifers can be inferred from Azimuthal Self Potential Gradient (ASPG) measurements. This extremely simple technique involves measuring the self potential gradient as a function of azimuth with a pair of non polarizing electrodes connected to a voltmeter. The electrokinetic effect associated with the flow of fluids within fractures is the source of the ASPG signal. Fracture strike mapping at multiple sites has repeatedly demonstrated the effectiveness of the method at the field scale and indicated that the direction of flow can be determined from the polarity of relatively large ASPG signals. A laboratory study was conducted to determine whether ASPG could also be used to characterize the hydraulic anisotropy associated with the enhancement of permeability and porosity of tight unconsolidated soils (e.g. clays) as a result of pneumatic fracturing, a technique to improve the effectiveness of remediation efforts. Compressed kaolinite sediments were pneumatically fractured following industry procedures. The resulting fracture geometry was quantified from strike analysis of visible fractures combined with strike data from optical borehole televiewer (BHTV) imaging. ASPG measurements were then made during injection of a simulated remedial treatment (electrolyte/dye) under an applied gas pressure. Consistent with previous findings in fractured rock aquifers, ASPG lobes are well correlated with azimuths of high fracture strike density suggesting that the ASPG anisotropy is a proxy measure of hydraulic anisotropy created by the pneumatic fracturing. The magnitude of the ASPG signal scales linearly (linear correlation coefficients > 0.74) with the applied gas pressure gradient for any particular hydraulically-active fracture set and the positive lobe of the ASP anomaly denotes the flow direction within that fracture set. These findings demonstrate that applications of the

  8. Mineralogical analysis of clays in hardsetting soil horizons, by X-ray fluorescence and X-ray diffraction using Rietveld method

    International Nuclear Information System (INIS)

    Diffraction and spectroscopic techniques have been shown to be suitable for obtaining physical and mineralogical properties in polycrystalline soil samples, and also in their precursor compounds. For instance, the X-ray fluorescence (XRF) spectroscopy allows obtaining the elemental composition of an investigated sample, while the X-ray diffraction (XRD) technique permits obtaining qualitative and quantitative composition of the soil minerals through the Rietveld method (RM). In this study Yellow Latosol (Oxisol), Yellow Argisol (Ultisol) and Gray Argisol (Ultisol) soil samples, classified as “hardsetting soils”, extracted from areas located at Northeast and Southeast of Brazilian coast were investigated. The soils and their fractions were analyzed in an EDX-700 and an XRD-6000 (Cu Kα radiation). XRF results indicate high percentages of Si and Al, and small percentage of Fe and Ti in the investigated samples. The DRX data and RM indicate that there was a predominance of kaolinite and halloysite minerals (kaolin group minerals) in the clay fractions, which are presumably responsible for the formation of kaolinitic plasma in these soils. Also, the obtained results showed that the XRF, XRD techniques and RM were very helpful for investigating the mineralogical composition of a hardsetting soil. - Highlights: ► Elemental composition of soil samples through X-Ray fluorescence. ► Mineralogical quantification through X-ray diffraction and Rietveld method. ► Oxisol and Ultisol, Brazil ‘Barreiras’ formation. ► High amounts of Si and Al oxides and low amounts of Fe and Ti oxides. ► Predominance of kaolinite in the clay fraction

  9. Evaluation of Turf-Grass and Prairie-Vegetated Rain Gardens in a Clay and Sand Soil, Madison, Wisconsin, Water Years 2004-08

    Science.gov (United States)

    Selbig, William R.; Balster, Nicholas

    2010-01-01

    The U.S. Geological Survey, in cooperation with a consortium of 19 cities, towns, and villages in Dane County, Wis., undertook a study to compare the capability of rain gardens with different vegetative species and soil types to infiltrate stormwater runoff from the roof of an adjacent structure. Two rain gardens, one planted with turf grass and the other with native prairie species, were constructed side-by-side in 2003 at two locations with different dominant soil types, either sand or clay. Each rain garden was sized to a ratio of approximately 5:1 contributing area to receiving area and to a depth of 0.5 foot. Each rain garden, regardless of vegetation or soil type, was capable of storing and infiltrating most of the runoff over the 5-year study period. Both rain gardens in sand, as well as the prairie rain garden in clay, retained and infiltrated 100 percent of all precipitation and snowmelt events during water years 2004-07. The turf rain garden in clay occasionally had runoff exceed its confining boundaries, but was still able to retain 96 percent of all precipitation and snowmelt events during the same time period. Precipitation intensity and number of antecedent dry days were important variables that influenced when the storage capacity of underlying soils would become saturated, which resulted in pooled water in the rain gardens. Because the rooftop area that drained runoff to each rain garden was approximately five times larger than the area of the rain garden itself, evapotranspiration was a small percentage of the annual water budget. For example, during water year 2005, the maximum evapotranspiration of total influent volume ranged from 21 percent for the turf rain garden in clay to 25 percent for the turf rain garden in sand, and the minimum ranged from 12 percent for the prairie rain garden in clay to 19 percent for the prairie rain garden in sand. Little to no runoff left each rain garden as effluent and a small percentage of runoff returned to the

  10. The key role of micromorphology in studies of the genesis of clay minerals and their associations in soils and its relevance to advances in the philosophy of soil science

    OpenAIRE

    CHURCHMAN, Gordon Jock

    2013-01-01

    Micromorphological observations from 3 different published works have been studied to aid understanding of aggregation and of colloids, both unique to soils. Saprolites in Hong Kong included ‘veins’ of different thicknesses and colours. Optical mineralogy identified them as infill from the neogenesis of clays in rock fractures. The common thicker infills resulted from weathering. Dark infill contained comminuted primary minerals whereas thin pale infill originated hydrothe...

  11. Field investigation with regard to the impermeability of clay formations. Helium-4 soil gas surveys in sedimentary basins as a tentative study of secondary permeability in clayey sequences

    International Nuclear Information System (INIS)

    This report deals with a tentative study for the detection of the secondary permeability in clayey formations conducted in several sedimentary basins in Central Italy, by means of geochemical methods. The main purposes are: to try a geochemical method, based on the distribution of deep origin gases in soil gas (4He and 222Rn), to detect buried fault systems and to study the permeability of clay as a potential migration pathway for nuclides of radioactive waste deposits; to verify the effectiveness of this method for the selection of suitable sites for radwaste disposal. This research programme consists in a collaboration between ENEA and the University of Rome within the communitarian programme for the disposal of high level and long-live radwaste. Investigations concerned sedimentary basins filled by sand-clay formations 1000-2000 meters thick and characterized by different tectonic: Era and Chiani-Paglia Valleys (Tuscany and North Latium), structural trenches due to extensive tectonics along the tyrrhenian edge, and Vasto region, a basin in the 'Adriatic foretrench', characterized by compressive tectonics. The investigated areas are near or directly correspond to geothermal fields or to hydrocarbon reservoirs supplying gases which may migrate upward along fractures. Almost 4000 soil gas samples were collected in the three surveyed areas; the sampling density was of about 1.5 points / km2, normally used in the regional scale surveys. The obtained results show that the observed helium anomalies are distributed or elongated according to the main tectonic features of the substratum (fault systems, fractures, deep structures); the magnitude of anomalies seems to correlate with the nature of the deep gas reservoir (i.e. oil in Vasto), geothermal reservoir in the Paglia valley. These observations seem to confirm that the presence of deep origin gases in soils is controlled by tectonics. Clay thickness does not significantly control the uprising of deep gases: in fact a

  12. Salinity control in a clay soil beneath an orchard irrigated with treated waste water in the presence of a high water table: A numerical study

    Science.gov (United States)

    Russo, David; Laufer, Asher; Bardhan, Gopali; Levy, Guy J.

    2015-12-01

    A citrus orchard planted on a structured, clay soil associated with a high water table, irrigated by drip irrigation system using treated waste water (TWW) and local well water (LWW) was considered here. The scope of the present study was to analyze transport of mixed-ion, interacting salts in a combined vadose zone-groundwater flow system focusing on the following issues: (i) long-term effects of irrigation with TWW on the response of the flow system, identifying the main factors (e.g., soil salinity, soil sodicity) that control these effects, and (ii) salinity control aiming at improving both crop productivity and groundwater quality. To pursue this two-fold goal, 3-D numerical simulations of field-scale flow and transport were performed for an extended period of time, considering realistic features of the soil, water table, crop, weather and irrigation, and the coupling between the flow and the transport through the dependence of the soil hydraulic functions, K(ψ) and θ(ψ), on soil solution concentration C, and sodium adsorption ratio, SAR. Results of the analyses suggest that in the case studied, the long-term effect of irrigation with TWW on the response of the flow system is attributed to the enhanced salinity of the TWW, and not to the increase in soil sodicity. The latter findings are attributed to: (i) the negative effect of soil salinity on water uptake, and the tradeoff between water uptake and drainage flux, and, concurrently, solute discharge below the root zone; and, (ii) the tradeoff between the effects of C and SAR on K(ψ) and θ(ψ). Furthermore, it was demonstrated that a data-driven protocol for soil salinity control, based on alternating irrigation water quality between TWW and desalinized water, guided by the soil solution salinity at the centroid of the soil volume active in water uptake, may lead to a substantial increase in crop yield, and to a substantial decrease in the salinity load in the groundwater.

  13. Dispersão de argila em microagregados de solo incubado com calcário Clay dispersion in microaggregates of soil incubated with limestone

    Directory of Open Access Journals (Sweden)

    Silvio Tulio Spera

    2008-12-01

    incubated with 0, 1.9, 3.8, 5.7, 7.6 and 15.2 Mg ha-1. After the incubation period, the micro and macro porosity, soil density, clay dispersion, hydraulic conductivity and concentration of exchangeable Al, Ca and Mg and soil organic matter were evaluated. Soil density, clay dispersion, pH and Ca and Mg concentration increased with lime application, while macro porosity, hydraulic conductivity, soil organic matter, and Al decreased. The increase of pH and hydraulic conductivity were higher in the sterilized soil. Liming effects were more evident at a rate of 3.8 Mg ha-1. Soil sterilization increased the pH value and decreased the organic matter content and Ca, besides the hydraulic conductivity. Micro- aggregate dispersion in limed soils can, at least partially, contribute to soil compaction.

  14. Clay matrix voltammetry

    International Nuclear Information System (INIS)

    Document available in extended abstract form only. In many countries, it is planned that the long life highly radioactive nuclear spent fuel will be stored in deep argillaceous rocks. The sites selected for this purpose are anoxic and satisfy several recommendations as mechanical stability, low permeability and low redox potential. Pyrite (FeS2), iron(II) carbonate, iron(II) bearing clays and organic matter that are present in very small amounts (about 1% w:w) in soils play a major role in their reactivity and are considered today as responsible for the low redox potential values of these sites. In this communication, we describe an electrochemical technique derived from 'Salt matrix voltammetry' and allowing the almost in-situ voltammetric characterization of air-sensitive samples of soils after the only addition of the minimum humidity required for electrolytic conduction. Figure 1 shows the principle of the developed technique. It consists in the entrapment of the clay sample between a graphite working electrode and a silver counter/quasi-reference electrode. The sample was previously humidified by passing a water saturated inert gas through the electrochemical cell. The technique leads to well-defined voltammetric responses of the electro-active components of the clays. Figure 2 shows a typical voltammogram relative to a Callovo-Oxfordian argillite sample from Bure, the French place planned for the underground nuclear waste disposal. During the direct scan, one can clearly distinguish the anodic voltammetric signals for the oxidation of the iron (II) species associated with the clay and the oxidation of pyrite. The reverse scan displays a small cathodic signal for the reduction of iron (III) associated with the clay that demonstrates that the majority of the previously oxidized iron (II) species were transformed into iron (III) oxides reducible at lower potentials. When a second voltammetric cycle is performed, one can notice that the signal for iron (II

  15. Change effects in the land use about the mineral clay

    International Nuclear Information System (INIS)

    The Pampas land changes during the Quaternary, left their mark on the mineralogy of soil clays. This work is oriented to compare the mineralogical composition of the clays and the value of potassium in an eucalyptus forestation. These results show that the mineralogical illite alteration is the cause of its destruction. This clay is the main reservoir of potassium for the agricultural soils

  16. Fracture mapping in clays: the design and application of a mobile gas geochemistry laboratory for the analysis of soil gases

    International Nuclear Information System (INIS)

    Integrated soil gas analyses for helium, radon, carbon dioxide, oxygen and organic gases allow the accurate interpretation of soil gas signatures as indicators of underlying structure. The most important features observed in the patterns of soil gas behaviour are large variations over faults and fractures. Structures such as these provide channelways for fluid movement in the upper crust. The construction of a mobile gas geochemistry laboratory for the analysis of soil gases at field investigation sites, and the subsequent trials carried out to evaluate the laboratory, clearly show that the soil gas investigation technique is accurate and viable as an independent site investigation method for the study of fracturing and groundwater movement around potential waste repository sites. (author)

  17. Amplification of plasmid DNA bound on soil colloidal particles and clay minerals by the polymerase chain reaction

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Polymerase chain reaction (PCR) was used to amplify a 600-base pair (bp) sequence of plasmid pGEX-2T DNA bound on soil colloidal particles from Brown soil (Alfisol) and Red soil (Ultisol), and three different minerals (goethite, kaolinite, montmorillonite). DNA bound on soil colloids, kaolinite, and montmorillonite was not amplified when the complexes were used directly but amplification occurred when the soil colloid or kaolinite-DNA complex was diluted, 10- and 20-fold. The montmorillonite-DNA complex required at least 100-fold dilution before amplification could be detected. DNA bound on goethite was amplified irrespective of whether the complex was used directly, or diluted 10- and 20-fold. The amplification of mineral-bound plasmid DNA by PCR is, therefore, markedly influenced by the type and concentration of minerals used. This information is of fundamental importance to soil molecular microbial ecology with particular reference to monitoring the fate of genetically engineered microorganisms and their recombinant DNA in soil environments.

  18. Tile drain losses of nitrogen and phosphorus from fields under integrated and organic crop rotations. A four-year study on a clay soil in southwest Sweden.

    Science.gov (United States)

    Stenberg, Maria; Ulén, Barbro; Söderström, Mats; Roland, Björn; Delin, Karl; Helander, Carl-Anders

    2012-09-15

    In order to explore the influence of site-specific soil properties on nitrogen (N) and phosphorus (P) losses between individual fields and crop sequences, 16 drained fields with clay soils were investigated in a four-year study. Mean total N (TN) loss was 6.6-11.1 from a conventional, 14.3-21.5 from an organic and 13.1-23.9 kg ha(-1) year(-1) from an integrated cropping system across a 4 year period, with 75% in nitrate form (NO(3)-N). Mean total P (TP) loss was 0.96-3.03, 0.99-4.63 and 0.76-2.67 kg ha(-1) year(-1), from the three systems respectively during the same period, with 25% in dissolved reactive form (DRP). Median N efficiency was calculated to be 70% including gains from estimated N fixation. According to principal component factor (PCA) analysis, field characteristics and cropping system were generally more important for losses of N and P than year. Accumulation of soil mineral N in the autumn and (estimated) N fixation was important for N leaching. No P fertilisers were used at the site in either cropping system. Total P concentration in drainage water from each of the fields was marginally significantly (pcrop with efficient nutrient uptake and good soil structure was general preconditions for low nutrient leaching. Incorporation of ley by tillage operations in the summer before autumn crop establishment and repeated operations in autumn as well, increased N leaching. Crop management in sequences with leguminous crops needs to be considered carefully when designing cropping systems high efficiency in N utilisation and low environmental impact. PMID:22264921

  19. Evaluation of Drainage from Passive Suction and Nonsuction Flux Meters in a Volcanic Clay Soil under Tropical Conditions

    Energy Technology Data Exchange (ETDEWEB)

    van der Velde, M; Green, S R.; Gee, Glendon W.; Vanclooster, M; Clothier, B E.

    2005-11-30

    Root zone drainage measurements are needed to improve fertilizer management in areas where agriculture may be impacting groundwater supplies. We present results of field tests where drainage was measured with two types of suction (resolution of 0.16 and 1.6 mm -1) and a nonsuction (resolution of 0.22 mm tip-1) water flux meter (WFM). The soil was a microstructured weathered volcanic ash located on a coral atoll subject to intense rainfall and located in the Kingdom of Tonga. Our objectives were to evaluate water flux measurements by comparing them with (i) simple water balance estimates of cumulative fluxes deduced from soil moisture content changes, and (iii) simulated fluxes using HYDRUS-1D. Soil hydraulic properties were obtained at five soil depths. During the 60-d evaluation period rainfall totaled 340 mm. The WFMs were installed in duplicate using disturbed soil. The consistency of the shape of the drainage curves measured with the WFMs, those derived from soil moisture changes, and those obtained with modeling led us to conclude that soil disturbance during WFM installation did not severely influence measurements. This was attributed to the strong microaggregation and disturbance introduced by plowing. Water balance and HYDRUS model estimates of drainage corresponded well with the measurement by nonsuction WFMs. Suction WFMs overestimated drainage, possibly due to flow convergence created by wick and divergence barrier lengths being not properly sized for the observed flow conditions. After the evaluation period some of the WFMs failed to respond. Nevertheless, flux meters are seen as promising tools to provide remote and continuous measurement of root zone drainage.

  20. Soil Water Repellency of Sands and Clay as Affected by Particle Size%砂土和黏土的颗粒差异对土壤斥水性的影响

    Institute of Scientific and Technical Information of China (English)

    杨松; 吴珺华; 董红艳; 张燕明

    2016-01-01

    斥水性土壤广泛存在于自然界中,并且对土壤环境和作物生长等有重要影响。建立理想化的土壤颗粒模型对砂土和黏土的斥水特性进行计算分析。结果表明:当接触角很小时,砂土中不存在斥水现象。随着接触角的增大,砂土斥水性与含水率密切相关,砂土的密实度对其斥水性也有重要影响,当砂土比较密实时,土壤的“亲水”与“斥水”特性对含水率特别敏感,随着含水率的变化,砂土可能由亲水性较好的土壤转变为斥水性土壤;当砂土比较松散时,土壤颗粒的斥水性对含水率并不敏感。当黏土接触角略小于90°且湿润半径b也较小时,黏土也存在斥水现象。如果黏土颗粒的接触角较小或接触角小于90°且湿润半径b较大,黏土总是亲水的。黏土含水率较大时,斥水特性由土壤颗粒的接触角决定。%Water-repellent soils,existing widely in nature,have some important effects on soil environment and crop growth. In order to analyze water repellency of sand and clay,models of sand and clay different in particle size were built. Results showed that no phenomenon of water repellency was found in sand soil when the contact angle of water with sand was small. Water repellency of sand soil was closely related to soil water content when the sand-water contact angle was big. Compactness of the soil was another important factor affecting soil water repellency. When the sand soil was highly compacted,whether the soil was hydrophilic or hydrophobic was very sensitive to water content,and it might switch from one state to another with changing soil water content. When the sand soil was quite loose,it was no longer sensitive to soil water content. In clay soil with soil-water contact angle being slightly less than 90°and wetting radius b being small,the phenomenon of water repellency was observed. But when the clay soil was much smaller than 90°in soil-water and

  1. Interaction Effects of Insecticides on Enzyme Activities in Black Clay Soil from Groundnut (Arachis hypogaea L. Fields

    Directory of Open Access Journals (Sweden)

    C. Nasreen

    2012-06-01

    Full Text Available In practice pesticides are extensively used in agriculture as a part of pest control strategies. Two insecticides, endosulfan (organochlorine and profenophos (organophosphate, were assessed for their effects on the activities of protease (in terms of tyrosine formed from casein and urease (as ammonia released from urea in soil, collected from a fallow groundnut field by applications of insecticides at normal field rates and at higher concentrations (1.0, 2.5, 5.0, 7.5, 10.0 kg ha-1, in a laboratory study. The results showed a strong positive influence on protease and urease enzyme activities in soil treated with 2.5 and 5.0 kg ha-1 dry soil and they were significantly (P ≤ 0.05 higher than the control over the course of incubation. In soil treatment, there was a significant increase in protease and decrease in urease activities after 24h of incubation which continued up to 20 days. However, a significant decrease in both protease and urease enzyme activities was observed in 30 and 40 days of incubation.DOI: http://dx.doi.org/10.5755/j01.erem.60.2.671

  2. Satellite based radar interferometry to estimate large-scale soil water depletion from clay shrinkage: possibilities and limitations

    NARCIS (Netherlands)

    Brake, te B.; Hanssen, R.F.; Ploeg, van der M.J.; Rooij, de G.H.

    2013-01-01

    Satellite-based radar interferometry is a technique capable of measuring small surface elevation changes at large scales and with a high resolution. In vadose zone hydrology, it has been recognized for a long time that surface elevation changes due to swell and shrinkage of clayey soils can serve as

  3. Biochar improves fertility of a clay soil in the Brazilian Savannah: short term effects and impact on rice yield

    Directory of Open Access Journals (Sweden)

    Marcia Thais de Melo Carvalho

    2013-12-01

    Full Text Available The objective of this study was to report single season effects of wood biochar (char application coupled with N fertilization on soil chemical properties, aerobic rice growth and grain yield in a clayey Rhodic Ferralsol in the Brazilian Savannah. Char application effected an increase in soil pH, K, Ca, Mg, CEC, Mn and nitrate while decreasing Al content and potential acidity of soils. No distinct effect of char application on grain yield of aerobic rice was observed. We believe that soil properties impacted by char application were inconsequential for rice yields because neither water, low pH, nor the availability of K or P were limiting factors for rice production. Rate of char above 16 Mg ha^(−1 reduced leaf area index and total shoot dry matter by 72 days after sowing. The number of panicles infected by rice blast decreased with increasing char rate. Increased dry matter beyond the remobilization capacity of the crop, and high number of panicles infected by rice blast were the likely cause of the lower grain yield observed when more than 60 kg N ha^(−1 was applied. The optimal rate of N was 46 kg ha^(−1 and resulted in a rice grain yield above 3 Mg ha^(−1.

  4. Assessment of degradation potential of aliphatic hydrocarbons by autochthonous filamentous fungi from a historically polluted clay soil

    Czech Academy of Sciences Publication Activity Database

    Covino, Stefano; D´Annibale, A.; Stazi, S. R.; Cajthaml, Tomáš; Čvančarová, Monika; Stella, Tatiana; Petruccioli, M.

    2015-01-01

    Roč. 505, FEB 2015 (2015), s. 545-554. ISSN 0048-9697 R&D Projects: GA MŠk(CZ) EE2.3.30.0003; GA ČR GA13-28283S Institutional support: RVO:61388971 Keywords : Mycoaugmentation * Pseudoallescheria sp * Oil -contaminated soil Subject RIV: EE - Microbiology, Virology Impact factor: 4.099, year: 2014

  5. Effects of Different Factors on Water Flow and Solute Transport Investigated by Time Domain Reflectometry in Sandy Clay Loam Field Soil.

    Science.gov (United States)

    Merdun, Hasan

    2012-09-01

    Factors affecting preferential flow and transport in the vadose zone need to be investigated by experiments and simulations to protect groundwater against surface applied chemicals. The objectives of this study were to investigate the effects of several factors (soil structure, initial soil water content (SWC), and application rate) and their interactions on the extent of preferential flow and transport in a sandy clay loam field soil using the time domain reflectometry (TDR) for measuring SWC and electrical conductivity (EC) in 12 treatments, modeling (by HYDRUS-1D and VS2DTI) the measured SWC and EC, and conducting statistical tests for comparing the means of the measured and modeled SWC and EC and solute transport parameters (pore water velocity and dispersion coefficient) obtained by inversely fitting in the CXTFIT program. The study results showed that the applied solution moved faster in the undisturbed, wet initial SWC, and higher application rate experimental conditions than in the disturbed, dry initial SWC, and lower application rate, respectively, based on the analysis of the changes in TDR measured SWC and EC with depth at 1, 2, 5, and 15 h of the experiments. However, the effects of interactive factors or treatments on water flow and solute transport were not clear enough. The modeling results showed that HYDRUS-1D was better than VS2DTI in the estimation of EC and especially SWC, but overall the models had relatively low performances in the simulations. Statistical test results also showed that the treatments had different flow and transport characteristics because they were divided into different groups in terms of the means of SWC and EC and solute transport parameters. These results suggest that similar experiments with more distinct interactions and modeling studies with different approaches need to be considered for better understanding the complex flow and transport processes in the vadose zone. PMID:23002311

  6. Adsorção de fósforo em solos de argila de atividade baixa Phosphate sorption in low activity clay soils

    Directory of Open Access Journals (Sweden)

    Gustavo Souza Valladares

    2003-01-01

    Full Text Available Neste estudo foram avaliadas possíveis correlações entre atributos físicos e químicos do solo e a capacidade máxima de adsorção de fósforo (CMAP em solos com argila de atividade baixa de diferentes regiões do Brasil, sendo utilizadas amostras de horizontes superficiais (A e subsuperficiais (B de 16 perfis de solos. As doses para a determinação da CMAP foram calculadas com base no teor de fósforo remanescente e variaram de 0 a 135 mg.L-1. A partir dos dados obtidos foram então construídas isotermas de adsorção de Langmuir. Foram feitas correlações entre CMAP e os teores de argila, de carbono orgânico, ki, kr, superfície específica, teor de alumínio determinado por ataque sulfúrico e teores das diferentes formas de ferro extraível. Foi observada grande variação nos valores de CMAP para o horizonte superficial (48 a 1429 mg.kg-1 e para o horizonte subsuperficial (455 e 1.667 mg.kg-1. Os coeficientes de correlação demonstraram haver uma associação significativa entre a CMAP e o teor de argila dos solos, ferro e alumínio, determinados pelo ataque sulfúrico e ferro extraído com ditionito-citrato-bicarbonato (DCB. A análise de regressão múltipla mostrou bom ajuste aos valores da CMAP com base em atributos dos solos estudados.In this study possible correlations between physical and chemical properties and the maximum phosphorus adsorption capacity (MAPC were evaluated in soils with low activity clay from different regions of Brazil, using samples from the surface (A and subsurface (B horizons of 16 soil profiles. The dosages for the determination of MAPC were calculated from the level of remaining phosphorus and they ranged from 0 to 135 mg L-1. From this data isotherms of P adsorption were built. Correlations were tested between MAPC and the clay content, organic carbon, ki, kr, specific surface, Al content determined by sulfuric acid attack, and content of different forms of extracted iron. A high variation in the

  7. Constitutive model for overconsolidated clays

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Based on the relationships between the Hvorslev envelope,the current yield sur-face and the reference yield surface,a new constitutive model for overconsolidated clays is proposed. It adopts the unified hardening parameter,to which the potential failure stress ratio and the characteristic state stress ratio are introduced. The model can describe many characteristics of overconsolidated clays,including stress-strain relationships,strain hardening and softening,stress dilatancy,and stress path dependency. Compared with the Cam-clay model,the model only re-quires one additional soil parameter which is the slope of the Hvorslev envelope. Comparisons with data from triaxial drained compression tests for Fujinomori clay show that the proposed model can rationally describe overconsolidated properties. In addition,the model is also used to predict the stress-strain relationship in the isotropic consolidation condition and the stress paths in the undrained triaxial compression tests.

  8. Contact micromechanics in granular media with clay

    Energy Technology Data Exchange (ETDEWEB)

    Ita, S.L.

    1994-08-01

    Many granular materials, including sedimentary rocks and soils, contain clay particles in the pores, grain contacts, or matrix. The amount and location of the clays and fluids can influence the mechanical and hydraulic properties of the granular material. This research investigated the mechanical effects of clay at grain-to-grain contacts in the presence of different fluids. Laboratory seismic wave propagation tests were conducted at ultrasonic frequencies using spherical glass beads coated with Montmorillonite clay (SWy-1) onto which different fluids were adsorbed. For all bead samples, seismic velocity increased and attenuation decreased as the contact stiffnesses increased with increasing stress demonstrating that grain contacts control seismic transmission in poorly consolidated and unconsolidated granular material. Coating the beads with clay added stiffness and introduced viscosity to the mechanical contact properties that increased the velocity and attenuation of the propagating seismic wave. Clay-fluid interactions were studied by allowing the clay coating to absorb water, ethyl alcohol, and hexadecane. Increasing water amounts initially increased seismic attenuation due to clay swelling at the contacts. Attenuation decreased for higher water amounts where the clay exceeded the plastic limit and was forced from the contact areas into the surrounding open pore space during sample consolidation. This work investigates how clay located at grain contacts affects the micromechanical, particularly seismic, behavior of granular materials. The need for this work is shown by a review of the effects of clays on seismic wave propagation, laboratory measurements of attenuation in granular media, and proposed mechanisms for attenuation in granular media.

  9. Long term corrosion of iron and non alloy or low alloy steels in clay soils. Physico-chemical characterisation and electrochemical study of archaeological analogues

    International Nuclear Information System (INIS)

    Archaeological objects of Gallo-Roman and Merovingian time, and from a battlefield of World War 1, were studied to better understand long term corrosion phenomena of iron in clay soils. This study is part of the French national program about nuclear waste deep repository, conducted by the ANDRA (French national Agency for Radioactive Waste Management). Iron archaeological analogues make a valuable contribution to the specifying of containers for long lived and high level wastes (HLWs), because they provide access to the considered time scale. The experimental issue is divided into two major parts: - a physico-chemical characterisation of corrosion products, by Raman spectroscopy; - an electrochemical study of the behaviour of the different corrosion layers. Although the metallic material is different between ancient artefacts (ferrite) and 1914-1918 remains (hypo-eutectoid steels), the same stable phases are identified in their corrosion products: mainly iron oxides and oxi-hydroxides. From a macroscopic point of view, these products are staggered into two layers: an internal one, and an external one, which contains soil markers. Under the microscope, a complex composite structure appears. Goethite a-FeOOH, which was identified on each object, is frequently in contact with the metal core. The average corrosion rate in the burial environment, deduced from the layers thickness, highlights a significant slowdown of corrosion after the first burial time, about one century. The electrochemical study showed the predominant role of transport phenomena in the pores of corrosion layers. The behaviour of the metal - internal layer system is well explained by a model of porous electrode (De Levie theory). Despite its porosity, the internal layer is protective, as it leads to a significant decrease of the corrosion rate (about ten time). (author)

  10. Evaluation of Long-Term Application of Organic Residues on Accumulation of Organic Matter and Improvement of Soil Chemical Properties in a Clay Terrace Soil of Bangladesh

    OpenAIRE

    Egashira, Kazuhiko; Han, Jing-Long; Karim, A.J.M. Sirajul; Abu Zofar Md. Moslehuddin; Yamada, Yoshio

    2003-01-01

    The field experiment on the long-term application of organic residues was started in 1988 at the farm of Bangabandhu Shekh Mujibur Rahamn Agricultural University (BSMRAU; named as Institute of Postgraduate Studies in Agriculture (ISPA)until 1998) and is continued until now. Five kinds of organic residues (no-application, rice straw green manure, compost and cowdung) were applied every June to cover soil surface uniformly as a thin layer and incorporated into soil to the depth of 10cm. Rice(Ju...

  11. Organic waste treatment with organically modified clays

    International Nuclear Information System (INIS)

    The use of organically modified clays in hazardous waste management applications offers a significant new and untapped potential. These clays may be used in the stabilization of organic wastes and organically contaminated soils, for waste water treatment, for oil spill control, for liner systems beneath fuel oil storage tanks, and as a component within liner systems of hazardous waste storage treatment and disposal facilities. Organically modified clays (organophilic clays) may be employed in each of these systems to adsorb organic waste constituents, enhancing the performance of the applications

  12. Study on Engineering Geological Property of Q2 Overlapping Clay Soil in Ningxiang along Changsha- Yiyang Railway%长益城际宁乡Q2网纹黏土工程地质特性研究

    Institute of Scientific and Technical Information of China (English)

    汪莹鹤; 郭建湖; 赵新益; 高威

    2011-01-01

    研究目的:长沙至益阳城际铁路宁乡境内广泛分布Q2网纹状红黏土,这种土体性质有很强的区域性,城际铁路对路基的沉降变形控制十分严格,所以针对此类路基如何采用合理的处理方法是一个关键问题.为了全面了解宁乡Q2网纹状红黏土的工程性质,结合现场地质调绘、钻探、原位测试及室内试验,对土体的形态成因、物理性质、强度特性、变形固结特性以及膨胀特性进行系统的探讨,为路基设计提供可靠的依据.研究结论:网纹状土是在湿热的气候条件及多水的环境下,红黏土经多次淋溶沉淀作用而形成;网纹土的孔隙比比一般黏土要大,饱和度一般低于90%,为非饱和土;液限及液性指数较高,为高液限土;天然状态下网纹土的强度较高,一般处于硬塑~坚硬状态,承载力可达200 kPa;网纹土属于中压缩性土,下层网纹土压缩性比上层土要高;网纹土是典型的超固结土,表层的超固结比达到15.4;网纹土一般为弱膨胀土.%Research purposes; The Q2 overlapping clay soil is widely distributed in Ningxiang along the ChangshaYiyang Railway and it is hardly found in other regions. To choose the proper method to treat this type of soil is the key problem because the subgrade settlement of intercity railway must be controlled strictly. Through the in - situ investigation, drilling exploration, in -situ test and indoor experiment, etc, the study is done on the soils morphology and genesis, physical property, strength characteristics, deformation consolidation and expansive property to know the engineering characteristics of the overlapping clay soil for providing the reliable basis for the subgrade design. Research conclusions;The overlapping soil is formed from the red clay caused by the effect of leaching and depositing under the warm and wet environment, and it is a typical unsaturated soil with void ratio being bigger than red clay and saturation degree

  13. Nanomechanical characterization of clay micro flocs

    OpenAIRE

    Zhang, Guoping; Yin, Hang; Reed, Allen

    2014-01-01

    Clay flocs are abundant in natural soils (a particulate material) and water-borne sediments. As the basic microscale, loading-bearing fundamental units, their mechanical properties control the macroscopic response of bulk soils and sediment transport. Owing to their tiny size and extremely soft consistency (especially for suspended water-borne flocs), significant difficulties and challenges exist for mechanical characterization of clay micro flocs. A novel nanomechanical characterization tech...

  14. Adjustment of the expedite method for clay content determination in Rondônia soils Ajuste de método expedito para determinação de teor de argila em solos de Rondônia

    Directory of Open Access Journals (Sweden)

    Jairo André Schlindwein

    2011-12-01

    Full Text Available Soil clay content is an important soil attribute and has been used to classification of phosphorus status in the soil in order to determinate the needing of phosphorus amounts to be applied to crops production. The aim of this research was to adjust the method for soil clay content determination, adopted by the laboratories of Southern Brazil (ROLAS-RS/SC, for soil clay content evaluation in Rondônia soils. The study was conducted using 50 soil samples from Rondônia State with wide range clay content. It was tested shaking periods (1.5, 2.0 and 2.5h associated with periods for soil particles decantation (1.5 and 2.0h to correlate with the standard method for soil texture testing, known as the pipette method. Clay content determined through this method was significantly correlated with pipette method. The better treatment was the combination of 2.0h of shaking and 1.5h of decantation, resulted in total period of 3.5h, which reduced the period to determine the soil clay content without loss of accuracy.O teor de argila é um importante atributo de solo e é utilizado na determinação de faixas de teores de fósforo para fins de recomendação de adubação. O objetivo deste trabalho foi ajustar o método de determinação de argila utilizado pelos laboratórios da ROLAS-RS/SC para avaliar os teores de argila dos solos de Rondônia. O estudo foi conduzido com 50 amostras de solos do Estado de Rondônia, com diferentes teores de argila. O teor de argila foi determinado utilizando-se o método da ROLAS-RS/SC, com diferentes períodos de agitação (1,5; 2,0 e 2,5h e de decantação das partículas do solo (1,5 e 2,0h e o método da pipeta, considerado padrão para essa determinação. Os teores de argila determinados nas combinações de períodos de agitação e de decantação se correlacionaram significativamente com os teores determinados pelo método da pipeta. O melhor tratamento foi a combinação de 2,0h de agitação e 1,5h de decanta

  15. A fast and efficient algorithm to map prerequisites of landslides in sensitive clays based on detailed soil and topographical information

    Science.gov (United States)

    Tryggvason, Ari; Melchiorre, Caterina; Johansson, Kerstin

    2015-02-01

    We present an algorithm developed for GIS-applications in order to produce maps of landside susceptibility in postglacial and glacial sediments in Sweden. The algorithm operates on detailed topographic and Quaternary deposit data. We compare our algorithm to two similar computational schemes based on a global visibility operator and a shadow-casting algorithm. We find that our algorithm produces more reliable results in the vicinity of stable material than the global visibility algorithm. We also conclude that our algorithm is more computationally efficient than the other two methods, which is important when we may want to assess the effects of uncertainty in the data by evaluating many different models. Our method also provides the possibility to take other data into account. We show how different soil types with different geotechnical properties may be modelled. Our algorithm may also take depth information, i.e. the thicknesses of the deposits into account. We thus propose that our method may be used to provide more refined maps than the overview maps in areas where more detailed geotechnical/geological data have been acquired. The efficiency of our algorithm suggests that it may replace any global visibility operators used in other applications or processing schemes of gridded map data.

  16. Comparative short-term effects of sewage sludge and its biochar on soil properties, maize growth and uptake of nutrients on a tropical clay soil in Zimbabwe

    Institute of Scientific and Technical Information of China (English)

    Willis Gwenzi; Moreblessing Muzava; Farai Mapanda; Tonny P Tauro

    2016-01-01

    Soil application of biochar from sewage could potentialy enhance carbon sequestration and close urban nutrient balances. In sub-Saharan Africa, comparative studies investigating plant growth effect and nutrients uptake on tropical soils amended with sewage sludge and its biochar are very limited. A pot experiment was conducted to investigate the effects of sewage sludge and its biochar on soil chemical properties, maize nutrient and heavy metal uptake, growth and biomass partitioning on a tropical clayey soil. The study compared three organic amendments; sewage sludge (SS), sludge biochar (SB) and their combination (SS+SB) to the unamended control and inorganic fertilizers. Organic amendments were applied at a rate of 15 t ha–1 for SS and SB, and 7.5 t ha–1 each for SS and SB. Maize growth, biomass production and nutrient uptake were signiifcantly improved in biochar and sewage sludge amendments compared to the unamended control. Comparable results were observed with F, SS and SS+SB on maize growth at 49 d of sowing. Maize growth for SB, SS, SS+SB and F increased by 42, 53, 47, and 49%, respectively compared to the unamended control. Total biomass for SB, SS, SS+SB, and F increased by 270, 428, 329, and 429%, respectively compared with the unamended control. Biochar amendments reduced Pb, Cu and Zn uptakes by about 22% compared with sludge alone treatment in maize plants. However, there is need for future research based on the current pot experiment to determine whether the same results can be produced under ifeld conditions.

  17. Swelling transition of a clay induced by heating.

    Science.gov (United States)

    Hansen, E L; Hemmen, H; Fonseca, D M; Coutant, C; Knudsen, K D; Plivelic, T S; Bonn, D; Fossum, J O

    2012-01-01

    Clays are of paramount importance for soil stability, but also in applications ranging from oil recovery to composites and hydrogels. Generically, clays are divided into two subclasses: macroscopically swelling, 'active' clays that have the capacity for taking up large amounts of water to form stable gels, and 'passive' or non-swelling clays; the former stabilize soils whereas the latter are known to lead to landslides. However, it has been unclear so far what mechanisms underlie clay swelling. Here, we report the first observation of a temperature-induced transition from a passive to an active, swelling clay. We propose a simple description of the swelling transition; while net attractive interactions are dominant at low temperatures so that the clay particles remain attached to each other in stacks, at higher temperatures it is energetically favourable for the clay to swell due to the entropy that is gained by counterions which are liberated during swelling. PMID:22943004

  18. Mineralogy of the clay fraction of soils from the moray cusco archaeological site: a study by energy dispersive X-ray fluorescence, X-ray diffractometry and Moessbauer spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Ceron Loayza, Maria L., E-mail: malucelo@hotmail.com; Bravo Cabrejos, Jorge A.; Mejia Santillan, Mirian E. [Universidad Nacional Mayor de San Marcos, Laboratorio de Analisis de Suelos, Laboratorio de Espectroscopia Moessbauer, Facultad de Ciencias Fisicas (Peru)

    2011-11-15

    The purpose of this work is to report the advances in the elemental and structural characterization of the clay fraction of soils from the terraces of the Moray Archaeological site, located 38 km north of the city of Cusco, Cusco Region. One sample was collected from each of the twelve terraces of this site and its clay fraction was separated by sedimentation. Previously the pH of the raw samples was measured resulting that all of the samples were from alkaline to strongly alkaline. Energy dispersive X-ray fluorescence (EDXRF) was used for the elemental characterization, and X-ray diffractometry (XRD) and transmission Moessbauer spectroscopy (TMS), using the {gamma} 14.4 keV nuclear resonance transition in {sup 57}Fe, were used for the structural characterization of the clays and clay minerals present in each sample. The EDXRF analyses of all the samples show the presence of relatively high concentrations of sulfur in some of the samples and relatively high concentrations of calcium in all of the samples, which may be related to the high alkalinity of the samples. By XRD it is observed the presence of quartz, calcite, gypsum, cronstedtite, 2:1 phyllosilicates, and iron oxides. The mineralogical analysis of Fe by TMS shows that it is present in the form of hematite and occupying Fe{sup 2 + } and Fe{sup 3 + } sites in phyllosilicates, cronstedtite, and other minerals not yet identified.

  19. 粘土矿物固定化微生物对土壤中阿特拉津的降解研究%Biodegradation of Atrazine in Soils by Clay Minerals Immobilized a Degradation Bacterium

    Institute of Scientific and Technical Information of China (English)

    汪玉; 王磊; 司友斌; 孟雪梅

    2009-01-01

    Biodegradation of atrazine in soils by clay minerals immobilized a degradation bacterium were studied. The bacterium which was isolated from activated sludge by enrichment using atrazine as sole source of carbon and nitrogen was preliminarily identified as Ochrobac-trum sp., according to its physiological-biochemical characteristics, photos of ESEM and the similarity analysis of its 16S rDNA gene sequence. The strains growed well on clay minerals, and reached logarithmic phase at 48 h. The degradation rate of atrazine was larger signifi-cally when adding degradation bacteria into soils. The biodegradation capacity by immobilized microorganism on clay minerals was improved compared with free microorganism. The smaller the particle size of clay minerals, the more the biodegradation of atrazine. The effect of immobilized nano-clay minerals was better than corresponding clays. The degradation of atrazine were 42.47%, 46.19%, 56.31 % respectively, after adding free microorganism into vertisol, alfisol and red soil on 28 d. When adding immobilized microorganism by montmorillonite, nano-mont-morillonite, the degradation of atrazine were 52.16%, 63.97% in vertisol, 59.28%, 63.91% in alfisol, and 68.03%, 76.59% in red soil. The degradation of atrazine in the soil without microorganism was 29.16% in vertisol, 30.63% in alfisol, 41.47% in red soil. Atrazine degradation in soils could be described by first-order kinetic equation. The effect of degradation varied from different soils. The(t_(1/2) of atrazine was 36.9 d in red soil, 49.1 d in vertisol, and 55.0 d in alfisol without microorganism. When adding immobilized microorganism by nano-montmorillonite, half-life was 16.3 d, 25.3 d, 21.7 d respectively.%以粘土矿物为载体,采用吸附挂膜法对已筛选的阿特拉津降解菌株进行固定化,并应用固定化微生物降解土壤中的阿特拉津.结果表明,该菌株在粘土矿物上生长良好,根据菌种生理生化特性、

  20. The plastic limit of clays

    OpenAIRE

    Haigh, Stuart K.; Vardanega, Paul J.; Bolton, Malcolm D.

    2013-01-01

    The plastic limit of soils was first described by Atterberg in 1911. The thread-rolling test was standardised at the US Public Roads Bureau in the 1920s and 1930s, and has subsequently become one of the standard tests of soil mechanics. This paper reviews the original definitions of plastic limit as proposed by Atterberg, and proposes that the brittle failure observed in the plastic limit test is caused by either air entry or cavitation in the clay. Critical state soil mechanics is used to sh...

  1. Response of Soybean [Glycine Max (L. Merrill] to Lime Based Integrated Nutrient Management and Mulching on Nodulation, Nutrient Contents and Yield in Clay Loam Soil.

    Directory of Open Access Journals (Sweden)

    R.C. Jain

    2015-08-01

    Full Text Available The present experiment was laid out in a randomized block design consisted of 6 treatments viz. (T1-Absolute control,(T2 -Farmer practice (50kg DAP/ha,(T3 RDF+ ZnSO4@25 kg/ha+ Ammonium Molybdate 1.0g/kg seed+ slacked lime@25Kg Ca(OH 2 /ha,(T4-RDF+ ZnSO4@25 kg/ha+ slacked lime@25Kg Ca(OH 2 /ha +Rhizobium+PSB (@Each 5g/kg seed +Ammonium Molybdate 1.0g/kg seed,(T5-50%RDF+ ZnSO4@25 kg/ha +FYM 2.5 t/ha+ slacked lime@25Kg Ca(OH 2 /ha + Rhizobium+PSB (@Each 5g/kg seed + Ammonium Molybdate 1.0g/kg seed + Mulching and(T6-50% RDF + ZnSO4@25 kg/ha+ slacked lime@25 Kg Ca(OH 2 + Vermicompost 1.5t/ha + Rhizobium + *PSB (@Each 5g/kg seed + Ammonium Molybdate1.0g/kg seed + Mulching. Variety JS 95-60 was used under experimentation which was conducted in clay loam soil during kharif seasons of 2010, 2011 and 2012 at ZARS Khargone (M.P The effect of lime based integrated nutrient management and mulching on nodulation, its dry weight, nutrient contents in straw & seed at maturity and grain yield(kg/ha were found to increase significantly and beneficial due to the application of 50% RDF + ZnSO4@25 kg/ha+ slacked lime@25Kg Ca(OH 2 /ha + V.C. 1.5t/ha + B.F.+ A.M. + Mulching(T6 followed by treatment T4 and T5 ( Table 1 over other treatments.

  2. Dredging Processes I: The Cutting of Sand, Clay & Rock - Theory

    NARCIS (Netherlands)

    Miedema, S.A.

    2013-01-01

    This book gives an overview of cutting theories. It starts with a generic model, which is valid for all types of soil (sand, clay and rock) after which the specifics of dry sand, water saturated sand, clay, rock and hyperbaric rock are covered. For each soil type small blade angles and large blade a

  3. 膨胀土与红黏土石灰改性对比试验研究%Comparative laboratory study of lime-treated expansive soil and red clay

    Institute of Scientific and Technical Information of China (English)

    孙志亮; 郭爱国; 太俊

    2013-01-01

    为探讨石灰改性膨胀土与红黏土的强度发展规律,以生石灰与消石灰改性的南阳膨胀土与郴州红黏土为研究对象,进行了无侧限抗压、固结快速直剪和固结压缩试验的对比研究。研究发现:在1a养生龄期内,石灰改性的南阳膨胀土与郴州红黏土无侧限抗压强度与养生龄期的对数基本呈线性关系;按大于最佳含水率3%制样的强度在养生28 d以后高于按最佳含水率制样;生石灰改性效果比消石灰改性效果好,由于矿物成分不同,石灰改性南阳膨胀土的效果比石灰改性郴州红黏土好。%To explore the development law of the strength of lime-treated expansive soil and red clay, the unconfined compression, consolidated quick direct shear tests and consolidation test are carried out to compare the Nanyang expansive soil and Chenzhou red clay modified by quicklime and hydrated lime respectively. The study found that during the one-year curing period of lime-treated Nanyang expansive soil and Chenzhou red clay, the unconfined compression strength is linear with the logarithm of curing age. The strength of the samples with moisture content larger than optimum moisture content for 3%after 28 days curing is higher than that of the optimum moisture content samples. In addition, the modification effect of quicklime is better than the effect of hydrated lime. Due to the different mineral composition, the modification effect of lime-treated Nanyang expansive soil is better than that of Chenzhou red clay.

  4. Discrete analysis of clay layer tensile strength

    International Nuclear Information System (INIS)

    The Discrete Element Method is used to investigate the tensile behaviour and cracks mechanisms of a clay material submitted to bending loading. It is the case of compacted clay liners in landfill cap cover application. Such as the soil tested in this study is plastic clay, the distinct elements model was calibrated with previous data results by taking into account cohesive properties. Various contact and cohesion laws are tested to show that the numerical model is able to reproduce the failure mechanism. Numerical results are extending to simulate a landfill cap cover and comparing to experimental large scale field bending tests achieved in a real site of storage. (authors)

  5. Soil-water characteristics and pore-size distribution of lateritic clay%红黏土的土水特性及其孔隙分布

    Institute of Scientific and Technical Information of China (English)

    孙德安; 高游; 刘文捷; 韦昌富; 张升

    2015-01-01

    The pressure plate method, filter paper method and vapor equilibrium technique with saturated salt solution and mercury intrusion porosimetry tests on Guilin lateritic clay are used to investigate the soil-water characteristics and pore-size distribution of undisturbed and compacted specimens in full suction range. The test results show that the undisturbed specimen has lower water content and saturation degree than the compacted one in the suction ranging from 0 kPa to 10 MPa because of the development of internal crack of undisturbed specimen with the increasing suction. When the suction is higher than 10 MPa, the soil-water characteristic curves (SWCC) coincide with each other. In the transition zone, the SWCCs of the undisturbed and compacted specimens are different from the typical ones. The undisturbed natural specimens exhibit a unimodal pore-size distribution, and the compacted ones usually have a double-porosity microstructure. The stability of shrinkage of the undisturbed natural specimen is larger than that of the compacted one. The compacted specimens with different dry densities also have the same pore-size distribution between particles, while the inter-aggregate pore distribution differ between the compacted specimens with different dry densities. It explains that when it is expressed by the relation between suction and water content, the SWCC is independent of dry density in the high suction range. When it is expressed by the relation between suction and saturation degree, the SWCC with high dry density is higher than that with the small one.%以桂林红黏土为研究对象,采用压力板法、滤纸法和饱和盐溶液蒸气平衡法3种方法研究在全吸力范围内原状样和压实样的土水特性,并结合压汞试验研究其孔隙分布。试验结果表明:当吸力约小于10 MPa时原状样的土水特征曲线略低于压实样,主要原因是原状样内部裂隙随吸力的增加而不断发展;当吸力约大于10

  6. Comparison of soil nematode communities in three forest types on sand and clay coal-mining dumps in Germany and Czech Republic

    Energy Technology Data Exchange (ETDEWEB)

    Hanel, L. [Academy of Science Czech Republic, Ceske Budejovice (Czech Republic). Inst. Soil Biology

    2003-12-01

    Nematode communities were studied in alder, oak and pine plantations, about 30-year-old, on sand coal-mining spoils at Cottbus in Germany and on clay coal-mining spoils at Sokolov, Czech Republic. Mean abundance of nematodes varied from 326 to 772 x 10{sup 3} ind.m{sup -2} and biomass from 286 to 795 mg.m{sup -2}. The genera Plectus, Acrobeloides, Filenchus and Aphelenchoides were common in all localities. The genera Rhabditis, Wilsonema, Tylencholaimus, Cephalenchus, Coslenchus, Rotylenchus, Aporcelaimellus, Eudorylaimus. and Prionchulus showed particular preferences for individual sites. Nematode faunas in alder and oak plantations were more affected by region than nematode faunas in pine plantations. Maturity Index and trophic diversity of nematode communities were greater in tree plantations on clay spoils than on sand spoils. Taxonomic diversity of nematode communities was greater in deciduous forest plantations on sand spoils than on clay spoils.

  7. EFFECT OF AQUEOUS PHASE PROPERTIES ON CLAY PARTICLE ZETA POTENTIAL AND ELECTRO-OSMOTIC PERMEABILITY: IMPLICATIONS FOR ELECTRO-KINETIC SOIL REMEDIATION PROCESSES

    Science.gov (United States)

    The influence of aqueous phase properties (pH, ionic strength and divalent metal ion concentration) on clay particle zeta potential and packed-bed electro-osmotic permeability was quantified. Although pH strongly altered the zeta potential of a Georgia kaolinite, it did not signi...

  8. Clay Minerals and Health

    OpenAIRE

    Abdurrahman Dalgıç; Orhan Kavak

    2004-01-01

    The aim of this study is to examine clay minerals, which take very importantplace in relationships of minerals and human health. They have high areadensity, adsorption capacity, rheological properties, chemical inertia and verylow or nontoxic effects to human health. So, they are widely used in medicaltreatments. Commercially used clay minerals are; smectit, polygrstite, caoliniteand talc. The other clay minerals are under investigations for medicaltreatments.

  9. Feasibility of classification of clay minerals by using PAS

    Science.gov (United States)

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

    2015-06-01

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

  10. On The Thermal Consolidation Of Boom Clay

    CERN Document Server

    Delage, Pierre; Cui, Yu-Jun

    2012-01-01

    When a mass of saturated clay is heated, as in the case of host soils surrounding nuclear waste disposals at great depth, the thermal expansion of the constituents generates excess pore pressures. The mass of clay is submitted to gradients of pore pressure and temperature, to hydraulic and thermal flows, and to changes in its mechanical properties. In this work, some of these aspects were experimentally studied in the case of Boom clay, so as to help predicting the response of the soil, in relation with investigations made in the Belgian underground laboratory at Mol. Results of slow heating tests with careful volume change measurements showed that a reasonable prediction of the thermal expansion of the clay-water system was obtained by using the thermal properties of free water. In spite of the density of Boom clay, no significant effect of water adsorption was observed. The thermal consolidation of Boom clay was studied through fast heating tests. A simple analysis shows that the hydraulic and thermal trans...

  11. Clays in prebiological chemistry

    Science.gov (United States)

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

    1980-01-01

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

  12. LABORATORY TESTING OF BENTONITE CLAYS FOR LANDFILL DESIGN AND CONSTRUCTION

    OpenAIRE

    Biljana Kovačević Zelić; Dubravko Domitrović; Želimir Veinović

    2007-01-01

    Top and bottom liners are one of the key construction elements in every landfill. They are usually made as compacted clay liners (CCLs) composed of several layers of compacted clay with strictly defined properties or by the use of alternative materials such as: GCL – geosynthetic clay liner, BES – bentonite enhanced soils or bentonite/polymer mixtures. Following the state of the art experiences in the world, GCLs are used in Croatian landfills for several years, as well. Depending upon the lo...

  13. Clay-Bacteria Systems and Biofilm Production

    Science.gov (United States)

    Steiner, J.; Alimova, A.; Katz, A.; Steiner, N.; Rudolph, E.; Gottlieb, P.

    2007-12-01

    Soil clots and the aerosol transport of bacteria and spores are promoted by the formation of biofilms (bacteria cells in an extracellular polymeric matrix). Biofilms protect microorganisms by promoting adhesion to both organic and inorganic surfaces. Time series experiments on bacteria-clay suspensions demonstrate that biofilm growth is catalyzed by the presence of hectorite in minimal growth media for the studied species: Gram negatives (Pseudomonas syringae and Escherichia coli,) and Gram positives (Staphylococcus aureus and Bacillus subtilis). Soil organisms (P. syringae, B. subtilis) and organisms found in the human population (E. coli, S. aureus) are both used to demonstrate the general applicability of clay involvement. Fluorescent images of the biofilms are acquired by staining with propidium iodide, a component of the BacLightTM Live/Dead bacterial viability staining kit (Molecular Probes, Eugene, OR). The evolving polysaccharide-rich biofilm reacts with the clay interlayer site causing a complex substitution of the two-water hectorite interlayer with polysaccharide. The result is often a three-peak composite of the (001) x-ray diffraction maxima resulting from polysaccharide-expanded clays and an organic-driven contraction of a subset of the clays in the reaction medium. X-ray diffractograms reveal that the expanded set creates a broad maximum with clay subsets at 1.84 nm and 1.41 nm interlayer spacings as approximated by a least squares double Lorentzian fit, and a smaller shoulder at larger 2q, deriving from a contraction of the interlayer spacing. Washing with chlorox removes organic material from the contracted clay and creates a 1-water hectorite single peak in place of the double peak. The clay response can be used as an indirect indicator of biofilm in an environmental system.

  14. Centrifuge modelling of rigid piles in soft clay

    DEFF Research Database (Denmark)

    Klinkvort, R.T.; Poder, M.; Truong, P.;

    2016-01-01

    this study is to employ centrifuge modelling in order to derive experimental p-y curves for rigid piles embedded in over-consolidated soft clay. A kaolin clay sample was prepared and pre-consolidated by applying a constant pressure at the soil surface, while different over-consolidation ratios were...

  15. Calculation of the debris flow concentration based on clay content

    Institute of Scientific and Technical Information of China (English)

    CHEN; Ningsheng; CUI; Peng; LIU; Zhonggang; WEI; Fangqiang

    2003-01-01

    The debris flow clay content has very tremendous influence on its concentration (γC). It is reported that the concentration can be calculated by applying the relative polynomial based on the clay content. Here one polynomial model and one logarithm model to calculate the concentration based on the clay content for both the ordinary debris flow and viscous debris flow are obtained. The result derives from the statistics and analysis of the relationship between the debris flow concentrations and clay content in 45 debris flow sites located in the southwest of China. The models can be applied for the concentration calculation to those debris flows that are impossible to observe. The models are available to calculate the debris flow concentration, the principles of which are in the clay content affecting on the debris flow formation, movement and suspending particle diameter. The mechanism of the relationship of the clay content and concentration is clear and reliable. The debris flow is usually of micro-viscous when the clay content is low (<3%), by analyzing the developing tendency on the basics of the relationship between the clay content and debris flow concentration. Indeed, the less the clay content, the less the concentration for most debris flows. The debris flow tends to become the water rock flow or the hyperconcentrated flow with the clay content decrease. Through statistics it is apt to transform the soil into the viscous debris flow when the clay content of ranges is in 3%-18%. Its concentration increases with the increasing of the clay content when the clay content is between 5% and 10%. But the value decreases with the increasing of the clay content when the clay content is between 10% and 18%. It is apt to transform the soil into the mudflow, when the clay content exceeds 18%. The concentration of the mudflow usually decreases with the increase of the clay content, and this developing tendency reverses to that of the micro-viscous debris flow. There is

  16. Black Carbon, The Pyrogenic Clay Mineral?

    Science.gov (United States)

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

  17. Geotechnical studies of Jaitapur marine clay

    Digital Repository Service at National Institute of Oceanography (India)

    Bhat, S.T.; Nayak, B.U.

    characterisEd. by high water content and high Atterberg limits. Undrained shear strength varied from 1.8 to 6 KPa. These were moderately sensitive clays. Carbonate content which varied from 3 to 27%, was found to influence engineering properties of the soil...

  18. Nanoporous clay with carbon sink and pesticide trapping properties

    OpenAIRE

    Woignier, Thierry; Duffours, L.; Colombel, P.; Dieudonné, P.

    2015-01-01

    A thorough understanding of the mechanisms and factors involved in the dynamics of organic carbon in soils is required to identify and enhance natural sinks for greenhouse gases. Some tropical soils, such as Andosols, have 3-6 fold higher concentrations of organic carbon than other kinds of soils containing classical clays. In the tropics, toxic pesticides permanently pollute soils and contaminate crops, water resources, and ecosystems. However, not all soils are equal in terms of pesticide c...

  19. Actual cation exchange capacity of agricultural soils and its relationship with pH and content of organic carbon and clay

    NARCIS (Netherlands)

    Erp, van P.J.; Houba, V.J.G.; Beusichem, van M.L.

    2001-01-01

    For the set up of a multinutrient 0.01 M calcium chloride (CaCl2) soil testing program a conversion from conventional soil testing programs to a CaCl2 program has been proposed in literature. Such conversion should be based on the relationship between test values of the conventional method and the C

  20. The use of clays as sorbents and catalysts

    International Nuclear Information System (INIS)

    The paper attempts to show the structural, physical and chemical properties of clay minerals relate to their laboratory, industrial and environmental uses as sorbents and catalysts. A brief review of the formulae and structures of clays and their relationship to their chemical and physical properties follows. Clay minerals are also useful in environmental protection as they can adsorb crude oils from spills and they are used, sometimes mixed into concrete, as containment barriers for radionuclides caesium 137 and strontium 90. Clay soils can also act as natural barriers to the migration of radionuclides in the environment

  1. Engineering property test of kaolin clay contaminated by diesel oil

    Institute of Scientific and Technical Information of China (English)

    刘志彬; 刘松玉; 蔡奕

    2015-01-01

    Engineering property of kaolin clay contaminated by diesel oil was studied through a series of laboratory experiments. Oil contents (mass fraction) of 4%, 8%, 12%, 16% and 20% were selected to represent different contamination degrees, and the soil specimens were manually prepared through mixing and static compaction method. Initial water content and dry density of the test kaolin clay were controlled at 10% and 1.58 g/cm3, respectively. Test results indicate that since part of the diesel oil will be released from soil by evaporation, the real water content should be derived through calibration of the quasi water content obtained by traditional test method. As contamination degree of the kaolin clay increases, both liquid limit and plastic limit decrease, but there’s only a slight increase for plasticity index. Swelling pressure of contaminated kaolin clay under confined condition will be lowered when oil-content gets higher. Unconfined compressive strength (UCS) of the oil-contaminated kaolin clay is influenced by not only oil content but also curing period. Increase of contamination degree will continually lower UCS of the kaolin clay specimen. In addition, electrical resistivity of the contaminated kaolin clay with given water content decreases with the increase of oil content. However, soil resistivity is in good relationship with oil content and UCS. Finally, oil content of 8% is found to be a critical value for engineering property of kaolin clay to transit from water-dominated towards oil-dominated characteristics.

  2. Transport of dodecane in sand and clay columns

    International Nuclear Information System (INIS)

    Contamination of soil by petroleum hydrocarbons is a significant problem in the United States. Release of nonaqueous phase liquids (NAPLs) petroleum contaminants at or near the ground surface can migrate through the vadose zone to the groundwater. In contaminated coarse-textured soils containing abrupt interfaces with clay layers, petroleum hydrocarbons can accumulate at the clay interface due to restricted water flow through the clay layer. In addition, the soil matrix can act as a sink to which the petroleum contaminant becomes adsorbed, resulting in a difficult remediation scenario. Soil columns were erected using six inch PVC pipe. Three types of columns were constructed: one comprised only of sand, one of only clay, and one with both clay and sand layers. Each column was 24 inches long and duplicate columns were prepared, as well. Dodecane was introduced into the columns at a single mid-point at the top of each column as a one-time event. Four sets of each type of column were constructed to permit sampling of the column soil at four subsequent time intervals. Each column was disassembled at specified times and the contaminant concentration levels were quantified as a function of distance into the column. Results of this study contribute to a more comprehensive understanding of the behavior of NAPLs in contaminated heterogeneous soils with high clay content

  3. Studies on Tagged Clay Migration Due to Water Movement

    International Nuclear Information System (INIS)

    55Fe-tagged clay minerals, produced by hydrothermal synthesis, serve to clarify the question whether clay migration or clay formation in situ is the predominating mechanism in the Bt-development of Parabraunerde (sol brun lessive, grey brown podsolic, hapludalf, dernopodsol). They further indicate the possibilities of clay transportation caused by water percolation. Suitable experimental approaches, such as thin-layer chromatography and autoradiography, translocation tests in columns filled with monotypical textural fractions or with undisturbed soil profiles, and synchronous hydrothermal treatment of 55Fe-con raining material from different horizons of Parabraunerde, to reveal the specific readiness of the different profile zones for 55Fe-clay production, are described. The possibilities of clay percolation are discussed. (author)

  4. Clay Mineral: Radiological Characterization

    Science.gov (United States)

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

    2008-08-01

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

  5. Clay Mineral: Radiological Characterization

    International Nuclear Information System (INIS)

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

  6. Probabilistic Description of a Clay Site using CPTU tests

    DEFF Research Database (Denmark)

    Andersen, Sarah; Lauridsen, Kristoffer; Nielsen, Benjaminn Nordahl; Ibsen, Lars Bo

    A clay site at the harbour of Aarhus, where numerous cone penetration tests have been conducted, is assessed. The upper part of the soil deposit is disregarded, and only the clay sections are investigated. The thickness of the clay deposit varies from 5 to 6 meters, and is sliced into sections of...... geotechnical assessment of a site, using both the method for classifying soil behaviour types and applying statistics, yield a new level of information, and certainty about the estimates of the strength parameters which are the important outcome of such a site description....

  7. Strength and Deformation Properties of Tertiary Clay at Moesgaard Museum

    DEFF Research Database (Denmark)

    Kaufmann, Kristine Lee; Nielsen, Benjaminn Nordahl; Augustesen, Anders Hust

    The tertiary clay at Moesgaard Museum near Aarhus in the eastern part of Jutland in Denmark is a highly plastic, glacially disturbed nappe of Viborg Clay. The clay is characterised as a swelling soil, which could lead to damaging of the building due to additional heave of the soil. To take...... this characteristic, as well as the strength and deformation properties, into account during the design phase, two consolidation tests and one triaxial test have been conducted. This paper evaluates the results of the laboratory tests leading to the preconsolidation stress, the deformation parameters consisting...

  8. Contracción de agregados de Argiudoles de la Pampa Ondulada diferenciados en su mineralogía de arcillas Shrinkage of soil aggregates from rolling Pampa Argiudolls differentiated by their clay mineralogy

    Directory of Open Access Journals (Sweden)

    Mario Guillermo Castiglioni

    2005-07-01

    propiedades que mejor se relacionaron con la tasa de contracción residual, mientras que la presencia de carbono orgánico disminuyó sensiblemente su valor.Swelling and shrinking affect soil physical and chemical behavior. Mc Garry & Malafant improved a model with three shrinkage areas, through which it is possible to estimate parameters with physical significance to compare different soils. The objective of the present work was to determine which soil properties and characteristics of Rolling Pampa Argiudolls with different clay mineralogy, affect the model parameters of Mc Garry & Malafant. Clods of distinct horizons of three non-disturbed soils were used to set the specific volume change / gravimetric water content relationship. Estimated parameters of the three straight lines model, were correlated with soils properties and characteristics. Whereas the distinct behavior in the volume change of argilic horizons with contrasting mineralogy was mainly at low soil water contents, the influence of clay percentage was best appreciated with normal shrinkage slope and at high soil water contents. Independently of clay mineralogy, the air entry point in the argilic horizons was registered at soil moisture seldom registered in the field. In the BC and C horizons, the joined consideration of clay and CEC gave a better correlation with the residual shrinkage slope, than the values obtained pondering those parameters individually. In the A and BA horizons the CEC was the better predictive parameter of the residual shrinkage slope. Analyzing the A, BA, BC and C horizons together, equivalent moisture and particle density were the best soil properties for predicting the residual contraction rate, whereas organic carbon decreased this value significantly.

  9. The effect of freeze-thaw cycles on the hydraulic conductivity of compacted clay

    International Nuclear Information System (INIS)

    A study was conducted to investigate the detrimental effects of freeze-thaw on the hydraulic conductivity of compacted clay. The purpose of this study was to determine the effect that molding water content has on the hydraulic conductivity of a compacted clay soil that is subjected to freeze-thaw cycles, and to determine the relationship between the number of freeze-thaw cycles and the hydraulic conductivity of the compacted clay soil. Clay soils compacted and frozen wet of optimum experienced an increase in hydraulic conductivity of approximately 140 fold. The hydraulic conductivity of clay compacted dry of optimum increased ten fold. These results are consistent with recent research which suggests that clay compacted wet of optimum experiences large increases in hydraulic conductivity while the hydraulic conductivity of clay compacted dry of optimum increases to a lesser extent. 12 refs., 9 figs

  10. Relationship between specific surface area and the dry end of the water retention curve for soils with varying clay and organic carbon contents

    DEFF Research Database (Denmark)

    Resurreccion, Augustus C.; Møldrup, Per; Tuller, Markus;

    2011-01-01

    contents. However, the TO model still overestimated water film thickness at potentials approaching ovendry condition (about −800 MPa). The semi–log linear Campbell-Shiozawa-Rossi-Nimmo (CSRN) model showed better fits for all investigated soils from −10 to −800 MPa and yielded high correlations with CL and......Accurate description of the soil water retention curve (SWRC) at low water contents is important for simulating water dynamics and biochemical vadose zone processes in arid environments. Soil water retention data corresponding to matric potentials of less than −10 MPa, where adsorptive forces...... classified into four groups on the basis of the Dexter number (n = CL/OC), and the Tuller-Or (TO) general scaling model describing water film thickness at a given matric potential (<−10 MPa) was evaluated. The SA estimated from the dry end of the SWRC (SA_SWRC) was in good agreement with the SA measured with...

  11. Clays as prebiotic photocatalysts

    Science.gov (United States)

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

    1981-01-01

    Clay minerals catalyze peptide bond formation in fluctuating environments. A number of plausible mechanisms have been proposed and tested. The possibility that clays may actually be energizing the reaction by means of electronic excitation, creating mobile or trapped holes and electrons in the lattice, is explored. It has been discovered that clays emit light upon dehydration. The correlation between dehydration-induced, or thermoluminescent, processes and the yield of glycine oligomers after treatments known to affect the luminescent yields is being tested, in an effort to understand the catalytic mechanism

  12. Characterization of clay minerals

    International Nuclear Information System (INIS)

    The natural clays are the more abundant minerals on the crust. They are used for making diverse industrial products. Due to the adsorption and ion exchange properties of these, a great interest for developing research directed toward the use of natural clays for the waste water treatment has been aroused. As part of such researches it is very important to carry out previously the characterization of the interest materials. In this work the results of the mineral and elemental chemical composition are presented as well as the morphological characteristics of clay minerals from different regions of the Mexican Republic. (Author)

  13. Clay content mapping through integration of geophysical proximal and remote sensing data

    Science.gov (United States)

    Garfagnoli, Francesca; André, Frédéric; Grandjean, Gilles; Lambot, Sébastien; Ciampalini, Andrea; Moretti, Sandro

    2013-04-01

    Soil sustainable exploitation planning and land resource evaluation require up-to-date and accurate maps of soil properties. In that respect, geophysical techniques present particular interests given their non-invasiveness and their fast data acquisition capacity, which permit to characterize large areas with fine spatial and/or temporal resolutions. We investigated the relevancy of combining data from airborne hyperspectral (Hs), electromagnetic induction (EMI) and far-field ground-penetrating radar (GPR) for mapping soil properties, in particular soil clay content, at the field scale. Data from the three techniques were acquired at a test site in Mugello (Italy) characterized by relatively strong spatial variations of soil texture. Soil samples were collected for determining actual clay contents. For the frequencies used in this study (200-2000 MHz), the GPR surface reflection is mainly determined by soil dielectric permittivity, itself primarily influenced by soil moisture. In contrast, EMI is mostly sensitive to soil electrical conductivity, which integrates several soil properties including in particular soil moisture and clay content. Taking advantage of the complementary information provided by the two instruments, the GPR and EMI data were combined and correlated to local ground-truth measurements of clay content to provide high-resolution clay content maps over the entire field area. Besides, a relationship was also observed between Hs data and clay content measurements, which permitted to produce a Hs-derived clay content map. EMI-GPR and Hs maps showed close spatial patterns and a relatively high correlation was observed between both clay content estimates, as well as between clay content estimates and ground-truth clay content measurements. Future analyses will entail more advanced Bayesian data fusion techniques for combining EMI-GPR and Hs information. These results demonstrated great promise for integrated, digital soil mapping applications.

  14. Gardening in Sandy Soils

    OpenAIRE

    Wagner, Katie; Kuhns, Michael; Cardon, Grant

    2015-01-01

    This fact sheet covers the basics of clay, silt and sand soils with an emphasis on gardening in soils with a high sand content. It includes information on the composition of sandy soils, gardening tips for managing sandy soils, and the types of plants that grow best in sandy soils.

  15. Germination of nine species of a pioneer plant community of pliocene clay soils of central western italy under different photo- and thermo-periods

    Directory of Open Access Journals (Sweden)

    Aldemaro Boscagli

    2014-02-01

    Full Text Available Germination response under different photo- and thermo-periods was investigated in nine species of the association Parapholido-Artemisietum cretaceae, a typical plant community of clay badland vegetation in central western Italy. The species showed: (i more rapid germination under the photo- and thermo-period emulating autumn conditions than under the one emulating early spring conditions; (ii different germination rates under condition emulating periods with high diurnal insolation followed by high or low nocturnal heat dispersion: Aegilops geniculata, Parapholis strigosa and Artemisia cretacea were indifferent, Hordeum maritimum, Trifolium scabrum, Brachypodium distachyum and Parapholis incurva responded positively to higher thermal dispersion, whereas Medicago minima and Scorpiurus muricatus responded negatively; (iii different responses to a constant low temperature of 2oC: Artemisia cretacea, Parapholis incurva, Parapholis strigosa and Scorpiurus muricatus showed complete or very high dormancy; the other species showed a germination capacity between 55 and 87% in the following decreasing order: Medicago minima > Hordeum maritimum > Trifolium scabrum > Aegilops geniculata > Brachypodium distachyum. All species had delayed and reduced germination responses at 2oC. Grasses showed prompt, quick and high germination as environmental conditions became more favourable; legumes showed a similar response when their coat-imposed dormancy was removed, while the asteracea A. cretacea showed only a moderate germination capacity and one of the lowest germination rates. Nomenclaure: Pignatti (1982.

  16. Organophilic clay suspension medium

    Energy Technology Data Exchange (ETDEWEB)

    Dixon, G.G.; Parlman, R.M.; Stewart, W.

    1989-10-24

    This patent describes an improved liquid suspension medium for particulate solids. The suspension medium having been formed by admixing an organophilic clay wherein the clay is selected from the group consisting of bentonite, attapulgite, sepiolite and hectorite and admixtures thereof present in the quantity of about 0.5-8 weight percent with a liquid hydrocarbon present in the quantity of about 99-70 weight percent and at least one activator selected from the group consisting of phenyl hydroxyalkyl ethers.

  17. Clay Minerals: Adsorbophysical Properties

    International Nuclear Information System (INIS)

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

  18. Organic-geochemical investigations on the mode of incorporation of a defined nonylphenol isomer and the herbicide MCPA in soil derived organo-clay complexes

    OpenAIRE

    Riefer, Patrick

    2011-01-01

    During the last decades the scientific interest to understand the interactions of organic contaminates with naturally occurring organic material increased. Emphasis was laid on the toxicity, bioavailability and transport of xenobiotics within the environment. Numerous publications have shown that high portions of anthropogenic substances could not be released by conventional extraction procedures from soils. It was assumed, that these non-extractable residues are incorporated in the organic m...

  19. On the thermal behaviour of Boom clay

    Energy Technology Data Exchange (ETDEWEB)

    Delage, P.; Cui Yu Jun [Ecole Nationale des Ponts et Chaussees, Paris (France); Sultan, N. [IFREMER, Brest (France)

    2004-07-01

    When temperature is increased, the various phenomena that occur in a saturated natural potential host clay for nuclear waste disposal (Boom clay from SCK-CEN in Mol, Belgium) were experimentally investigated in a temperature controlled high stress triaxial cell. Firstly, the pore pressure build-up due to the difference in thermal dilation of both water and minerals was investigated through thermal consolidation tests. Interesting information was obtained about the dissipation of thermally induced pore pressure in Boom clay, based on the standard Terzaghi consolidation theory. Secondly, the volume change behaviour in drained conditions (i.e. under a very slow temperature increase) confirmed that the clay overconsolidation ratio (OCR) controlled the nature of the volume changes. Whereas overconsolidated soils use to dilate as any material when temperature is elevated, normally consolidated soils present a decrease in volume, which is less common. The principles of a coupled thermo-elasto-plastic model that was specifically developed to model this particular behaviour are finally presented. Obviously, it appears necessary to account in detail for these thermal phenomena in order to properly understand the response of the geological barrier in the near field once nuclear waste has been stored. (orig.)

  20. On the thermal behaviour of Boom clay

    International Nuclear Information System (INIS)

    When temperature is increased, the various phenomena that occur in a saturated natural potential host clay for nuclear waste disposal (Boom clay from SCK-CEN in Mol, Belgium) were experimentally investigated in a temperature controlled high stress triaxial cell. Firstly, the pore pressure build-up due to the difference in thermal dilation of both water and minerals was investigated through thermal consolidation tests. Interesting information was obtained about the dissipation of thermally induced pore pressure in Boom clay, based on the standard Terzaghi consolidation theory. Secondly, the volume change behaviour in drained conditions (i.e. under a very slow temperature increase) confirmed that the clay overconsolidation ratio (OCR) controlled the nature of the volume changes. Whereas overconsolidated soils use to dilate as any material when temperature is elevated, normally consolidated soils present a decrease in volume, which is less common. The principles of a coupled thermo-elasto-plastic model that was specifically developed to model this particular behaviour are finally presented. Obviously, it appears necessary to account in detail for these thermal phenomena in order to properly understand the response of the geological barrier in the near field once nuclear waste has been stored. (orig.)

  1. Fixation of Selenium by Clay Minerals and Iron Oxides

    DEFF Research Database (Denmark)

    Hamdy, A. A.; Nielsen, Gunnar Gissel

    1977-01-01

    In studying Se fixation, soil components capable of retaining Se were investigated. The importance of Fe hydrous oxides in the fixation of Se was established. The clay minerals common to soils, such as kaolinite, montmorillonite and vermiculite, all exhibited Se fixation, but greater fixation...

  2. The infiltration process of clay soil under different initial soil water contents%不同初始含水率下粘质土壤的入渗过程

    Institute of Scientific and Technical Information of China (English)

    刘目兴; 聂艳; 于婧

    2012-01-01

    Soil infiltration is the basic hydrologicsl process for water penetrating into the soil, and the amount of water infiltrating the soil surface directly affects the quantity of surface runoff and soil erosion, even the recharge of both soil and underground water. The initial soil water content is an important factor to soil infiltration, and its role in runoff controlling and soil erosion prevention has been taken into account by many researches. In this study, the double-ring infiltration method was used to quantitatively measure the infiltrability of surface soil (0-5 cm depth) covered with forestland and grassland, which were under two antecedent soil water contents of 12% and 40% , respectively. In addition, the changes of soil infiltration process over time were estimated with different infiltration models.The results indicated that the initial soil infiltration rate of forestland and grassland tended to decrease with increasing initial soil water content. And an increase in initial soil water content results in an increase in steady infiltration rate and cumulative infiltration rate. Whether forestland or grassland, soil infiltration process with higher initial soil water content reaches the steady infiltration stage earlier than that with lower initial soil water content. For forestland with initial soil gravimetric water content rate of 12% , the initial soil infiltration rate was 8.95 mm/min, which was four times to the initial infiltration rate for forestland soil with gravimetric water content rate of 40%. However, its steady infiltration rate 0. 24 mm/min was only one eighth of the forestland with initial soil gravimetric water content rate of 40% , and the cumulative infiltration in an hour was only two thirds of that. This phenomena may attribute to the faster wetting rate of drier soil in infiltration process, which cause stronger slaking forces of the soil and severe aggregates breakdown, enhance surface sealing or promote the destruction of soil

  3. Monitoring of radioactive nuclides in incinerator fly ash and adsorption of Cs in simulated and actual eluate of the fly ash onto clay and soil

    International Nuclear Information System (INIS)

    Radioactive nuclides in the incinerator fly ash of municipal solid waste was determined and monitored. For leaching radioactive Cs from incinerating fly ash in reclaimed land, a modified No. 13 elution test and adsorption with stable Cs onto andosol were performed. The activity concentration of radioactive nuclides in incinerator fly ash was constant within the range of the activity concentration before the accident at Fukushima Daiichi Nuclear Power Station. The 134Cs/137Cs activity concentration ratio was almost equal to 1, corresponding to 137Cs existing in environment before the accident. 40% of 137Cs in incinerator fly ash eluted with the modified No. 13 elution test, and adsorption ratio of Cs+ onto the andosol showed 90% as being the primary concentration was equal to or more than 5000 μg L−1. In addition, the desorption results used for 5 types of solvent showed that desorption ratio of adsorbed Cs+ from the soil was 3.6% at the maximum. Hence, it is anticipated that using a soil that is similar in composition to the andosol suppresses the leaching out of radioactive Cs from reclaimed land. (author)

  4. Mineral Composition of Clay Fraction of the Chernozems Spread out in Ovče Pole in Republic of Macedonia

    OpenAIRE

    Mile Markoski; Tatjana Mitkova; Vedran Rubinić

    2011-01-01

    The results of mineral composition of the clay fraction of the chernozems spread out in Ovče Pole are presented. The mechanical composition of the soil samples show high domination of the physical clay and clay fractions in the soil separates, what is one of the reasons for strong influence on the physical and physical-mechanical properties of the soil. The clay content is dominant in the soil separates fraction and varies from 23.60% to 56.90%, or 36.23% average. The average content of physi...

  5. Macro-and Micro- Properties of Two Natural Marine Clays in China

    Institute of Scientific and Technical Information of China (English)

    JIANG Ming-jing; PENG Li-cai; ZHU He-hua; LIN Yi-xi; HUANG Liang-ji

    2009-01-01

    In this paper,macro- and micro- properties of natural marine clay in two different and representative regions of China are investigated in detail.In addition to in-situ tests,soil samples are collected by use of Shelby tubes for laboratory examination in Shanghai and Zhuhai respectively,two coastal cities in China.In the laboratory tests,macro-properties such as consolidation characteristics and undrained shear strength are measured.Moreover,X-ray diffraction test,scanning electron microscope test,and mercury intrusion test are carried out for the investigation of their micro-properties including clay minerals and microstructure.The study shows that:(1) both clays are Holocene series formations,classified as either normal or underconsolidated soils.The initial gradient of the stress-strain curves shows their increase with increasing consolidation pressure;however,the Shanghai and the Zhuhai clays are both structural soils with the latter shown to be more structured than the former.As a result,the Zhuhai clay shows strain softening behavior at low confining pressures,but strain hardening at high pressures.In contrast,the Shanghai clay mainly manifests strain-hardening.(2) An activity ranges from 0.75 to 1.30 for the Shanghai marine clay and from 0.5 to 0.85 for the Zhuhai marine clay.The main clay mineral is illite in the Shanghai clay and kaolinite in the Zhuhai clay.The Zhuhai clay is mainly characterized by a flocculated structure,while the typical Shanghai clay shows a dispersed structure.The porous structure of the Shanghai clay is characterized mainly by large and medium-sized pores,while the Zhuhai clay porous structure is mainly featreed by small and medium-sized pores.The differences in their macro- and micro- properties can he attributed to different sedimentation environments.

  6. Matéria orgânica e aumento da capacidade de troca de cátions em solo com argila de atividade baixa sob plantio direto Soil organic matter and cation exchange capacity increase in a low activity clay soil under no-tillage system

    Directory of Open Access Journals (Sweden)

    Marlise Nara Ciotta

    2003-12-01

    Full Text Available O sistema de manejo afeta a matéria orgânica do solo, o que pode ter expressivo efeito na CTC de solos com argila de atividade baixa. Neste estudo, avaliou-se o efeito da utilização durante 21 anos do sistema plantio direto (SPD sobre os estoques de carbono orgânico (CO, bem como a sua relação com o aumento da CTC de um Latossolo bruno (629 g kg-1 de argila, em Guarapuava, PR. O SPD promoveu acúmulo de CO na camada superficial do solo (0-6cm, o que refletiu-se num aumento de 2,63t ha-1 no estoque de CO, na camada de 0-20cm, em comparação ao preparo convencional. A baixa taxa de acúmulo de CO (0,12t ha-1 ano-1 foi relacionada à alta estabilidade física da matéria orgânica neste solo argiloso e oxídico. Apesar do pequeno acúmulo de CO no solo sob SPD, este teve reflexo positivo na CTC do solo, com um aumento médio, na camada de 0-8cm, de 15,2mmol c kg-1 na CTC efetiva, e de 20,7mmol c kg-1 na CTC a pH 7,0, em comparação ao solo em preparo convencional. Os resultados obtidos reforçam a importância do SPD quanto ao seu efeito nos estoques de matéria orgânica e, em consequência, na CTC de solos tropicais e subtropicais com predominância de argila de atividade baixa.Soil management affects the organic matter stocks, and thus the CEC especially in low activity clay soils. The main goal of this study was to evaluate the long-term (21 years effect of the no-tillage on soil organic carbon (SOC stocks and its relationship with CEC increase in a clayey Oxisol (Hapludox, in Guarapuava (PR, Southern Brazil. No-tillage soil had only 2.63t ha-1 more SOC than conventionally tilled soil at 0-20cm, and the highest net accumulation occurred in soil surface layers (0-6cm. The low accumulation rate of SOC in the no-tilled soil (0,12t ha-1 yr-1 was related to the high physical stability of soil organic matter in this clayey Oxisol. Despite the small effect on SOC contents, the no-tilllage had an expressive influence on the CEC of 0-8cm soil

  7. Sustainable agriculture and nitrogen reduction: an open field experiment using natural zeolitites in silty-clay reclaimed soil at Codigoro (Po River Delta, Ferrara, Italy)

    Science.gov (United States)

    Faccini, Barbara; Di Giuseppe, Dario; Mastrocicco, Micòl; Coltorti, Massimo; Colombani, Nicolò; Ferretti, Giacomo

    2014-05-01

    Following the guidelines of Nitrate and Water Framework Directives (91/676/CEE, 200/60/CE) an innovative integrated zeolitite cycle is being tested on a reclaimed clayey-silt soil in the Po Delta area (Ferrara Province, Italy), in the framework of the EU-funded ZeoLIFE project (LIFE+10 ENV/IT/000321). Natural zeolitites are pyroclastic rocks containing more than 50% of zeolites, a kind of hydrous minerals with peculiar physical and chemical properties, like high and selective cation exchange capacity (CEC), molecular adsorption and reversible dehydration. Zeolitites can trap NH4+ from solutions and release it gradually to the plant roots once they have been mixed in agricultural soils, allowing both fertilization and irrigation reduction and improvement of the yield. The fertilization reduction can result in a decrease of the nitrate content in groundwater and surface waters, ultimately leading to a mitigation of nutrient excess in the environment. Similarly, reduction of irrigation water means a minor exploitation of the water resource. The selected material used in the project is a chabazite zeolitite coming from a quarry near Sorano in Central Italy (Bolsena volcanic district). The open-field experimentation foresees two year of cultivation. A surface of about 6 ha has been divided into six parcels: three control parcels are cultivated and irrigated in traditional way; two parcels have been added with coarse-grained (ø = 3- 6 mm) natural zeolitite at different zeolitite/soil ratios (5 kg/m2 and 15 kg/m2) and one has been mixed with fine-grained (ø natural zeolitite and in that bearing NH4+-charged zeolitite, the fertilization has been reduced by 30% and 50% with respect to the controls. Notwithstanding these reductions, the yield increased by 5% and 15% in the parcel added with natural zeolitite and in that treated with NH4+-charged zeolitite, respectively. As confirmed by previously performed laboratory leaching tests, NH4+ in porewater and surface water was

  8. Determining the clay/organic carbon ratio by visible near infrared spectroscopy

    DEFF Research Database (Denmark)

    Knadel, Maria; Peng, Yi; Hermansen, Cecilie;

    The recently presented Dexter et al. (2008) threshold (ratio of clay to organic carbon (OC) of 10 kg/kg-1) is a good indicator for soil functional properties. However, the conventional analysis of OC and clay are costly and time consuming, thus an alternative method to quantify OC, clay or clay...... most important absorption bands related to both clay minerals (1421, 1910 and 2206 nm – OH bonds and 429, 720 nm – Fe oxides) and organic carbon (1730, 2160 nm and 2310 nm). The results of this study show that vis-NIRS can provide very successful and direct determination of Dexter index on a field...

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

    Science.gov (United States)

    Kohut, Connie K.; And Others

    1993-01-01

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

  10. Depth distribution of 137Cs adsorption property of clay minerals influenced by mineral weathering

    International Nuclear Information System (INIS)

    Radiocesium adsorption potential of mica clay mineral can increase as it is weathered, because K depletion in mica interlayer sites generates new Cs selective sites. However, in soils weathered under field conditions, the increase in 137Cs adsorption potential associated with mineral weathering has not been observed extensively. We investigated four soil profiles from Japan and Thailand with different soil pH ranges (3.3-4.0, 4.2-4.3, 5.0-5.7, and 5.5-7.3). The solid/liquid distribution coefficients of Cs (CsKd) in clay (137Cs adsorption potential of mica clay minerals. In three soil profiles, CsKd value in clay was the largest at a surface horizon and was decreased with depth, whereas in the most acidic of Podzolic soil profile, it was the largest at B horizon. The large CsKd value in surface clays relative to deeper horizons were well associated with that of 2.0-1.0 μm clay fraction. We assumed that the 137Cs adsorption potential increased at surface horizons mainly because coarser clay micas were weathered and generated Cs selective sites. The exceptional result obtained in Podzolic soil profile suggests that too intensive weathering destruct mica structure and may decrease in Cs adsorption potential of mica clay minerals. (author)

  11. Clay membrane made of natural high plasticity clay:

    DEFF Research Database (Denmark)

    Foged, Niels; Baumann, Jens

    1999-01-01

    into account advective ion transport as well as diffusion. Clay prospecting for clays rich in smectite has revealed large deposits of Tertiary clay of very high plasticity in the area around Rødbyhavn on the Danish island of Lolland. The natural clay contains 60-75% smectite, dominantly as a sodium...... have been tested successfully. At a natural water content of w=40-45% it is possible to establish a homogeneous membrane with hydraulic conductivity k...

  12. Long-term behaviour of iron in clay soils: a study of world war 1 remains by physico-chemical and electrochemical characterization

    International Nuclear Information System (INIS)

    Iron archaeological analogues constitute a good way to contribute to the definition of the containers for high-level radioactive wastes. In the present study we considered objects from a battle field of world war 1. Visual and microscopic observations revealed 2 corrosion layers of similar thickness: an external layer that appeared orange-brown, about 200 μm to 1 mm thick and in contact with the metallic cores an internal layer which was dark-grey. The Raman spectroscopy testing showed that the external layer was made out of oxy-hydroxides, mixed with crystals from the soil, while the presence of oxides was always associated with the internal corrosion layer. Electrochemical measurements clearly illustrated a different behaviour between the 2 corrosion layers. Impedance spectroscopy measuring confirmed the porosity of the external layer. Polarization tests were performed in Evian water to better understand the behaviour of the internal corrosion layer, an indicative corrosion current was defined and its measurement confirmed the protective role of the internal layer against corrosion. Nevertheless the burial environment seems to play also a significant role in the slowdown of the corrosion. (A.C.)

  13. Controlling cyanobacterial blooms through effective flocculation and sedimentation with combined use of flocculants and phosphorus adsorbing natural soil and modified clay.

    Science.gov (United States)

    Noyma, Natalia Pessoa; de Magalhães, Leonardo; Furtado, Luciana Lima; Mucci, Maíra; van Oosterhout, Frank; Huszar, Vera L M; Marinho, Marcelo Manzi; Lürling, Miquel

    2016-06-15

    Eutrophication often results in blooms of toxic cyanobacteria that hamper the use of lakes and reservoirs. In this paper, we experimentally evaluated the efficacy of a metal salt (poly-aluminium chloride, PAC) and chitosan, alone and combined with different doses of the lanthanum modified bentonite Phoslock(®) (LMB) or local red soil (LRS) to sediment positively buoyant cyanobacteria from Funil Reservoir, Brazil, (22°30'S, 44°45'W). We also tested the effect of calcium peroxide (CaO2) on suspended and settled cyanobacterial photosystem efficiency, and evaluated the soluble reactive P (SRP) adsorbing capacity of both LMB and LRS under oxic and anoxic conditions. Our data showed that buoyant cyanobacteria could be flocked and effectively precipitated using a combination of PAC or chitosan with LMB or LRS. The SRP sorption capacity of LMB was higher than that of LRS. The maximum P adsorption was lowered under anoxic conditions especially for LRS ballast. CaO2 addition impaired photosystem efficiency at 1 mg L(-1) or higher and killed precipitated cyanobacteria at 4 mg L(-1) or higher. A drawback was that oxygen production from the peroxide gave positive buoyancy again to the settled flocs. Therefore, further experimentations with slow release pellets are recommended. PMID:26706124

  14. Nanoporous clay with carbon sink and pesticide trapping properties

    Science.gov (United States)

    Woignier, T.; Duffours, L.; Colombel, P.; Dieudonné, P.

    2015-07-01

    A thorough understanding of the mechanisms and factors involved in the dynamics of organic carbon in soils is required to identify and enhance natural sinks for greenhouse gases. Some tropical soils, such as Andosols, have 3-6 fold higher concentrations of organic carbon than other kinds of soils containing classical clays. In the tropics, toxic pesticides permanently pollute soils and contaminate crops, water resources, and ecosystems. However, not all soils are equal in terms of pesticide contamination or in their ability to transfer pollution to the ecosystem. Andosols are generally more polluted than the other kinds of soils but, surprisingly, they retain and trap more pesticides, thereby reducing the transfer of pesticides to ecosystems, water resources, and crops. Andosols thus have interesting environmental properties in terms of soil carbon sequestration and pesticide retention. Andosols contain a nano porous clay (allophane) with unique structures and physical properties compared to more common clays; these are large pore volume, specific surface area, and a tortuous and fractal porous arrangement. The purpose of this mini review is to discuss the importance of the allophane fractal microstructure for carbon sequestration and pesticide trapping in the soil. We suggest that the tortuous microstructure (which resembles a labyrinths) of allophane aggregates and the associated low accessibility partly explain the poor availability of soil organic matter and of any pesticides trapped in andosols.

  15. Molecular Mechanisms of Enhanced Bacterial Growth on Hexadecane with Red Clay.

    Science.gov (United States)

    Jung, Jaejoon; Jang, In-Ae; Ahn, Sungeun; Shin, Bora; Kim, Jisun; Park, Chulwoo; Jee, Seung Cheol; Sung, Jung-Suk; Park, Woojun

    2015-11-01

    Red clay was previously used to enhance bioremediation of diesel-contaminated soil. It was speculated that the enhanced degradation of diesel was due to increased bacterial growth. In this study, we selected Acinetobacter oleivorans DR1, a soil-borne degrader of diesel and alkanes, as a model bacterium and performed transcriptional analysis using RNA sequencing to investigate the cellular response during hexadecane utilization and the mechanism by which red clay promotes hexadecane degradation. We confirmed that red clay promotes the growth of A. oleivorans DR1 on hexadecane, a major component of diesel, as a sole carbon source. Addition of red clay to hexadecane-utilizing DR1 cells highly upregulated β-oxidation, while genes related to alkane oxidation were highly expressed with and without red clay. Red clay also upregulated genes related to oxidative stress defense, such as superoxide dismutase, catalase, and glutaredoxin genes, suggesting that red clay supports the response of DR1 cells to oxidative stress generated during hexadecane utilization. Increased membrane fluidity in the presence of red clay was confirmed by fatty acid methyl ester analysis at different growth phases, suggesting that enhanced growth on hexadecane could be due to increased uptake of hexadecane coupled with upregulation of downstream metabolism and oxidative stress defense. The monitoring of the bacterial community in soil with red clay for a year revealed that red clay stabilized the community structure. PMID:25956940

  16. Rattles of Clay.

    Science.gov (United States)

    Banning, Donna

    1983-01-01

    Using the rattles of Native American cultures as inspiration, students used pinching, coiling, and slab and molding techniques to form the bodies of rattles and clay pellets for sound. Surface decoration included glazed and unglazed areas as well as added handles, feathers, and leather. (IS)

  17. Polyethylene/clay nanocomposites

    Czech Academy of Sciences Publication Activity Database

    Měřínská, D.; Kovářová, L.; Kalendová, A.; Chmielová, M.; Weiss, Z.; Hromádková, Jiřina; Šimoník, J.

    Akron: Polymer Processing Society, 2004. s. 245. [Polymer Processing Society Annual Meeting. 20.06.2004-24.06.2004, Akron] R&D Projects: GA AV ČR KSK4050111 Keywords : polyethylene * clay * polymer nanotechnology Subject RIV: CD - Macromolecular Chemistry

  18. Forage Legume Species for Cutting on Heavy Clay Soils with Bad Drainage Especies Leguminosas Forrajeras para Cortes en Suelos Arcillosos de Mal Drenaje

    Directory of Open Access Journals (Sweden)

    Patricio Soto O.

    2005-06-01

    Full Text Available Forage yield of three species of leguminous forrages: alfalfa, Medicago sativa L.; red clover, Trifolium pratense L.; and birdsfoot trefoil Lotus corniculatus L. was evaluated in waterlogged soils in the VIIth Region, Chile, during four seasons with three fertilization rates: 2 t lime ha-1 + 150 kg P2O5 ha-1; no lime application + 150 kg P2O5 ha-1; and no lime + 70 kg of P2O5 ha-1, applying half of the fertilizer dose during the seasons following establishment. The experimental design was randomized complete blocks with four repetitions. An analysis of variance was carried out and means were compared using the Duncan test (P ≤ 0.05. Alfalfa needed high fertilization to achieve production comparable to birdsfoot trefoil and red clover, reaching its best production with complete fertilization in the first season (4.6 t DM ha-1. The red clover maintained high production until the second season independent of the fertilizer dose (11.8 t DM ha-1, but began to decline in the third season. The birdsfoot trefoil was the species best adapted to these soil conditions, DM yield was not affected by the dose of phosphorus in the four years, reaching production levels of 7.1 t DM ha-1 during the fourth season.Se evaluó el rendimiento de forraje en tres especies de leguminosas forrajeras: alfalfa, Medicago sativa L.; trébol rosado, Trifolium pratense L.; y lotera, Lotus corniculatus L. en suelos arcillosos de mal drenaje de la VII Región, Chile, durante cuatro temporadas, con tres niveles de fertlización: 2 t de cal ha-1 + 150 kg de P2O5 ha-1; sin aplicación de cal + 150 kg de P2O5 ha-1; y sin cal + 70 kg de P2O5 ha-1, aplicando durante las siguientes temporadas la mitad de la dosis de fertilizante aplicado al establecimiento. El diseño experimental utilizado fue de bloques completos al azar con cuatro repeticiones. Se realizó análisis de varianza y en la comparación de medias se usó la prueba de Duncan (P ≤ 0,05. La alfalfa necesitó una alta

  19. Clay fraction mineralogy of a Cambisol in Brazil

    International Nuclear Information System (INIS)

    Clay minerals having a 2:1 (tetrahedral:octahedral sheet) structure may be found in strongly weathering soils only if the local pedo-climatic environment prevents them from further weathering to other minerals such as iron oxides. The clay minerals impart important chemical properties to soils, in part by virtue of changes in the redox state of iron in their crystal structures. Knowing the chemical nature of soil clays is a first step in evaluating their potential reactivity with other soil constituents and processes, such as the chemical decomposition of organic substrates to be potentially used in environmental remediation. The purpose of this work was to characterize the iron oxides and iron-bearing clay minerals from a B horizon of a Cambisol developed on tuffite in the State of Minas Gerais, Brazil, using chemical analysis, powder X-ray diffraction, Moessbauer spectroscopy, and thermal analysis. The iron oxides of this NaOH-treated clay-fraction were found to contain mainly maghemite (γFe2O3) and superparamagnetic goethite (αFeOOH). Kaolinite (Al2Si2O5(OH)4), smectite, and minor portions of anatase (TiO2) were identified in the CBD-treated sample.

  20. Clay fraction mineralogy of a Cambisol in Brazil

    Energy Technology Data Exchange (ETDEWEB)

    Anastacio, A. S.; Fabris, J. D., E-mail: jdfabris@ufmg.br [Federal University of Minas Gerais, Campus - Pampulha, Department of Chemistry (Brazil); Stucki, J. W. [Department of Natural Resources and Environmental Sciences (United States); Coelho, F. S.; Pinto, I. V. [Federal University of Minas Gerais, Campus - Pampulha, Department of Chemistry (Brazil); Viana, J. H. M. [Embrapa Milho e Sorgo (Brazil)

    2005-11-15

    Clay minerals having a 2:1 (tetrahedral:octahedral sheet) structure may be found in strongly weathering soils only if the local pedo-climatic environment prevents them from further weathering to other minerals such as iron oxides. The clay minerals impart important chemical properties to soils, in part by virtue of changes in the redox state of iron in their crystal structures. Knowing the chemical nature of soil clays is a first step in evaluating their potential reactivity with other soil constituents and processes, such as the chemical decomposition of organic substrates to be potentially used in environmental remediation. The purpose of this work was to characterize the iron oxides and iron-bearing clay minerals from a B horizon of a Cambisol developed on tuffite in the State of Minas Gerais, Brazil, using chemical analysis, powder X-ray diffraction, Moessbauer spectroscopy, and thermal analysis. The iron oxides of this NaOH-treated clay-fraction were found to contain mainly maghemite ({gamma}Fe{sub 2}O{sub 3}) and superparamagnetic goethite ({alpha}FeOOH). Kaolinite (Al{sub 2}Si{sub 2}O{sub 5}(OH){sub 4}), smectite, and minor portions of anatase (TiO{sub 2}) were identified in the CBD-treated sample.

  1. Clay Animals and Their Habitats

    Science.gov (United States)

    Adamson, Kay

    2010-01-01

    Creating clay animals and their habitats with second-grade students has long been one of the author's favorite classroom activities. Students love working with clay and they also enjoy drawing animal homes. In this article, the author describes how the students created a diorama instead of drawing their clay animal's habitat. This gave students…

  2. Clay membrane made of natural high plasticity clay

    DEFF Research Database (Denmark)

    Foged, Niels; Baumann, Jens

    1998-01-01

    ion transport as well as diffusion.Clay prospection for clays rich in smectite has revealed large deposits of Tertiary clay of very high plasticity in the area around Rødbyhavn on the Danish island Lolland. The natural clay contains 60 to 75% smectite, dominantly as a sodium-type. The clay material...... successfully. At natural watercontent w = 40 to 45% it is possible to establish a homogeneous membrane with hydraulic conductivity k conductivity measured in oedometer tests used for establishing swell and deformation properties showed...

  3. Atrazine biodegradation modulated by clays and clay/humic acid complexes

    International Nuclear Information System (INIS)

    The fate of pesticides in the environment is strongly related to the soil sorption processes that control not only their transfer but also their bioavailability. Cationic (Ca-bentonite) and anionic (Layered Double Hydroxide) clays behave towards the ionisable pesticide atrazine (AT) sorption with opposite tendencies: a noticeable sorption capacity for the first whereas the highly hydrophilic LDH showed no interactions with AT. These clays were modified with different humic acid (HA) contents. HA sorbed on the clay surface and increased AT interactions. The sorption effect on AT biodegradation and on its metabolite formation was studied with Pseudomonas sp. ADP. The biodegradation rate was greatly modulated by the material's sorption capacity and was clearly limited by the desorption rate. More surprisingly, it increased dramatically with LDH. Adsorption of bacterial cells on clay particles facilitates the degradation of non-sorbed chemical, and should be considered for predicting pesticide fate in the environment. - The biodegradation rate of atrazine was greatly modulated by adsorption of the pesticide and also bacterial cells on clay particles.

  4. 饱和软黏土中足尺静压桩挤土效应试验研究%Test research on soil compacting effect of full scale jacked-in pile in saturated soft clay

    Institute of Scientific and Technical Information of China (English)

    周火垚; 施建勇

    2009-01-01

    Soil compacting effect of jacked-in pile in the saturated soft clay is a topic of concern in the geotechnical engineering. Monitoring laws of lateral displacement of soil, pore pressure and land upheaval during pile-sinking is a project that a lot of researchers hope to implement. In this research, three full scale jacked-in piles are penetrated into the saturated soft clay and mostly studied by monitoring the law of lateral displacement with depth and radial distance to pile-sinking, the law of land upheaval with depth of penetration and radial distance to pile-sinking, and the law of pore pressure with penetration depth and time. Characteristics of maximum excess pore water pressure with radial distance and depth are also analyzed. From this test results, it is obtained that the maximum lateral displacement occurs at a depth of about 0.75L; land upheaval build up rapidly and reach the maximum when the pile tip arrive at depth of about 6 m; and the increment of excess pore water pressure reaches the maximum when the pile tip arrive at the piezometer level; while the maximum excess pore pressure presents a hysteresis quality with radial distance.%饱和软黏土地基中静压桩挤土效应是岩土工程中常见的问题.监测土体侧向位移、孔隙压力、地面隆起随压桩过程变化的规律是很多研究者希望实施的计划.在饱和软黏土地基中进行了3根足尺静压桩的压入试验,重点监测了沉桩时的侧向位移随深度和距桩轴不同距离、地面隆起量随桩的贯入深度和距桩轴不同距离、孔隙压力随桩的贯入深度和时间的变化规律,并分析了超静孔隙水压力最大值沿径向和深度的变化特性.由测试结果可知,最大的侧向位移发生在距地表0.75L附近,地面隆起从桩贯入开始迅速发展,并在桩压入到6 m左右时达到最大值,测点处超静孔压增量的最大值发生在桩端到达该点所在水平面时,而超孔压的最大值沿径向有滞后性.

  5. The effects of treading by two breeds of dairy cow with different live weights on soil physical properties, poaching damage and herbage production on a poorly drained clay-loam soil

    OpenAIRE

    Tuohy, P.; Fenton, O; Holden, N. M.; Humphreys, J.

    2014-01-01

    SUMMARY There is little empirical evidence to indicate that dairy cow live weight affects the extent of soil damage at the hoof-soil interface during grazing on poorly drained permanent grassland. In the present study the impact of Holstein-Friesian (HF) dairy cows with a mean (±standard deviation) live weight of 570 (±61) kg were compared with Jersey × Holstein-Friesian (JX) with a mean live weight of 499 (±52) kg each at two stocking densities: mean 2·42 ± (0·062) and 2·66 (±0·079) cows/ha....

  6. Effect of Salinity, Sodicity and Soil Texture on Aggregate Stability of Semi-arid Soils

    Science.gov (United States)

    Soil texture, sodicity and salinity or water quality play a significant role in determining soil aggregate stability, hydraulic properties and the response of soil clays to dispersion and swelling. We studied aggregate stability from 60 samples of Israeli top soils, widely varying in clay content an...

  7. 29 CFR Appendix A to Subpart P of... - Soil Classification

    Science.gov (United States)

    2010-07-01

    ... exhibit visible signs of moisture content. Fissured means a soil material that has a tendency to break... penetration tests, and other methods. Wet soil means soil that contains significantly more moisture than moist... clay (fine grained soil), or soil with a high clay content, which has cohesive strength. Cohesive...

  8. Clay membrane made of natural high plasticity clay

    DEFF Research Database (Denmark)

    Foged, Niels; Baumann, Jens

    1998-01-01

    Leachate containment in Denmark has through years been regulated by the DIF Recommendation for Sanitary Landfill Liners (DS/R 466). It states natural clay deposits may be used for membrane material provided the membrane and drainage system may contain at least 95% of all leachate created throughout...... advective ion transport as well as diffusion.Clay prospection for clays rich in smectite has revealed large deposits of Tertiary clay of very high plasticity in the area around Rødbyhavn on the Danish island Lolland. The natural clay contains 60 to 75% smectite, dominantly as a sodium-type. The clay...... coefficient being much lower than anticipated using the total porosity. These properties are of major importance to the future use of clay membranes for containment of hazardous waste. In order to explain these properties microstrutural investigations were initiated to establish boundary conditions for...

  9. Study of Adsorption of Phenanthrene on Different Types of Clay Minerals

    International Nuclear Information System (INIS)

    The fate and behaviour of non-ionic hydrophobic organic compounds in deep soil is mainly controlled by the mineral fraction present in the soil due to the very low organic carbon content of the deep soil. The mineral fraction that may greatly influence the fate and transport of these compounds due to its presence and properties are the clay minerals. Clay minerals also become increasingly important in low organic matter content soils. There tree, studies of non-ionic hydrophobic organic compounds adsorption on clay minerals without organic matter are necessary lo better understand the fate and transport of these compounds. In this work we used phenanthrene as model compound of non-ionic hydrophobic organic compound and four pure clay minerals: kaolinite, illite, montmorillonite, and vermiculite including muscovite mica. These clays minerals are selected due to its abundance in represents ve Spanish soils and different properties as its structural layers and expanding capacity. Batch experiments were performed using phenanthrene aqueous solutions and the clays selected. Phenanthrene sorption isotherms for all clays, except muscovite mica, were best described by the Freundlich model. Physical sorption on the external surfaces is the most probable adsorption mechanisms. In this sense, the presence of non-polar nano-sites on clay surfaces could determine the adsorption of phenanthrene by hydrophobic interaction on these sites. (Author) 22 refs

  10. Geotechnical and mineralological Konyaalti (Antalya, Turkey) clays

    International Nuclear Information System (INIS)

    Geotechnical and mineralogical characteristics of blue-green clays of the Harbour District existing inside the boundaries of Antalya Konyaalti Municipality were investigated with comprehensive field and laboratory tests. Today, building construction in this district is carried out without any prior qualified geotechnical investigations taking place. Undisturbed and disturbed soil specimens were taken from 12 drilled boreholes at 1.5 m intervals and down 30 m deep. Shelby tubes samples were retrieved and SPT were carried out in order to determine soil profile and geotechnical properties. After comparing the laboratory and field test results, it was observed that they were in agreement. Strength and compressibility characteristics of the soil were defined with the correlations using laboratory and field test results. Since the region has been formed of lagoon-sedimented clays, rock analysis was done on two specimens achieved from various depths along the soil profile. XRD analyses on eleven specimens were also conducted. Unconfined compressive strength (qu), undrained cohesion (Cu) and compression index (Cc) varies between 40 kN/m2, 7.0 kN/m2 and 90 kN/m2, 0.095 and 0.38, respectively. (author)

  11. A structural analysis model for clay caps

    International Nuclear Information System (INIS)

    This paper presents a structural analysis model for clay caps used in the landfill of low-level nuclear waste to minimize the migration of fluid through the soil. The clay cap resting on the soil foundation is treated as an axially symmetric elastic plate supported by an elastic foundation. A circular hole (concentric with the plate) in the elastic foundation represents an underlying cavity formed in the landfill due to waste decomposition and volume reduction. Unlike the models that commonly represent the soil foundation with equivalent springs, this model treats the foundation as a semi-infinite space and accounts for the work done by both compression and shear stresses in the foundation. The governing equation of the plate is based upon the classical theory of plate bending, whereas the governing equation derived by using Vlasov's general variational method describes the soil foundation. The solutions are expressed in terms of Basset functions. A FORTRAN program was written to carry out the numerical calculations

  12. Fixation of Selenium by Clay Minerals and Iron Oxides

    DEFF Research Database (Denmark)

    Hamdy, A. A.; Nielsen, Gunnar Gissel

    1977-01-01

    In studying Se fixation, soil components capable of retaining Se were investigated. The importance of Fe hydrous oxides in the fixation of Se was established. The clay minerals common to soils, such as kaolinite, montmorillonite and vermiculite, all exhibited Se fixation, but greater fixation...... occurred with the 1:1 than the 2:1 clay type. Experiments with finely ground minerals showed that the pH of the systems greatly influenced the rate of fixation, reaching a maximum between pH 3 and 5 and decreasing rapidly as the pH increased. With the Fe2O3 system fixed Se was slightly reduced as the p......H was increased to over 8. The extractability of Se from the clay minerals indicated that 1:1 clay type minerals fix selenite more indissolubly than 2:1 clays and that selenite was adsorbed on the clays mainly by a surface exchange reaction. The major part of the selenite added to the Fe2O3 system was...

  13. Water-clay interactions. Experimental study

    International Nuclear Information System (INIS)

    Clay minerals contribute to the chemical composition of soil and sediment groundwaters via surface and dissolution/precipitation reactions. The understanding of those processes is still today fragmentary. In this context, our experimental purpose is to identify the contribution of each reaction in the chemical composition of water in a water/clay System. Kaolinite, illite, montmorillonite are the reference clays. After a fine mineralogical study, the exchange equilibria between K+ and H+ are characterised. Different exchange sites are identified and the exchange capacities and selectivity coefficients are quantified. Then, mixtures of the three clays are equilibrated with acidic and basic (I≤10-2 M) solutions at 25 deg. C, 60 deg. C, 80 deg. C, during 320 days. The System evolution is observed by chemical analysis of the solutions and mineralogical analysis by TEM. We show that montmorillonite is unstable compared to the kaolinite/amorphous silica assemblage for solutions of pH<7. Aqueous silica is probably controlled by the kinetics of dissolution of the montmorillonite in moderate pH media. In more acidic solutions, amorphous silica precipitates. Al is under control of 'kaolinite' neo-formations. The use of the selectivity coefficients in a numerical simulation shows that K+ concentration depends on exchange reactions. The pH has a more complicated evolution, which is not completely understood. This evolution depends on both exchange equilibria and organic acid occurrence. In this type of experiments, we have demonstrated that the equilibrium equations between smectite and kaolinite are inexact. The problem of the thermodynamic nature of clays remains and is not resolved by these solubility experiments. (author)

  14. Faults in clays their detection and properties

    Energy Technology Data Exchange (ETDEWEB)

    Baldi, G.; Carabelli, E.; Chiantore, V.; Colombo, P.F.; Gruszka, A.; Pensieri, R.; Superbo, S.; Gera, F.

    1991-12-31

    The `Faults in clays project`, a cooperative research effort between Ismes and Enea of Italy and BGS and Exeter University of the UK, has been aimed at assessing and improving the resolution capability of some high resolution geophysical techniques for the detection of discontinuities in clay formations. All Ismes activities have been carried out in Italy: they consisted in the search of one or more sites - faulted clay formations - suitable for the execution of geophysical and geotechnical investigations, in the execution of such tests and in additional geological surveys and laboratory (geotechnical and geochemical) testing. The selected sites were two quarries in plio-pleistocenic clay formations in central Italy where faults had been observed. The greatest part of the research work has been carried out in the Orte site where also two 90 m boreholes have been drilled and cored. Geophysical work at Orte consisted of vertical electrical soundings (VESs) and horizontal electrical lines (HELs), four high resolution seismic reflection lines, and in-hole and cross-hole logs. Laboratory activities were geotechnical characterization and permeability tests, and measurements of disequilibrium in the uranium decay series. At Narni, where Exeter University sampled soil gases for geochemical analyses, the geophysical work consisted in a geo-electrical survey (five VESs and two HELs), and in two high resolution reflection seismic lines. Additional investigations included a structural geology survey. The main conclusion of the research is that current geophysical techniques do not have a resolution capacity sufficient to detect the existence and determine the characteristics of faults in deep homogeneous clay formations.

  15. Faults in clays their detection and properties

    International Nuclear Information System (INIS)

    The 'Faults in clays project', a cooperative research effort between Ismes and Enea of Italy and BGS and Exeter University of the UK, has been aimed at assessing and improving the resolution capability of some high resolution geophysical techniques for the detection of discontinuities in clay formations. All Ismes activities have been carried out in Italy: they consisted in the search of one or more sites - faulted clay formations - suitable for the execution of geophysical and geotechnical investigations, in the execution of such tests and in additional geological surveys and laboratory (geotechnical and geochemical) testing. The selected sites were two quarries in plio-pleistocenic clay formations in central Italy where faults had been observed. The greatest part of the research work has been carried out in the Orte site where also two 90 m boreholes have been drilled and cored. Geophysical work at Orte consisted of vertical electrical soundings (VESs) and horizontal electrical lines (HELs), four high resolution seismic reflection lines, and in-hole and cross-hole logs. Laboratory activities were geotechnical characterization and permeability tests, and measurements of disequilibrium in the uranium decay series. At Narni, where Exeter University sampled soil gases for geochemical analyses, the geophysical work consisted in a geo-electrical survey (five VESs and two HELs), and in two high resolution reflection seismic lines. Additional investigations included a structural geology survey. The main conclusion of the research is that current geophysical techniques do not have a resolution capacity sufficient to detect the existence and determine the characteristics of faults in deep homogeneous clay formations

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

    Science.gov (United States)

    1991-01-01

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

  17. Effect of heavy metal cations on the fate of extracellular DNA adsorbed and bound on clay minerals.

    OpenAIRE

    Ascher J.; Ceccherini M.T.; Arfaioli P.; Borgogni F.; Pietramellara G.

    2011-01-01

    The presence of high-valent metal cations on clay mineral surfaces is hypothesised to induce conformational changes in the secondary and tertiary structure of the DNA molecule adsorbed and bound onto clays, defined as M-conformation, and its condensation. The hypothesis that these reversible phenomena could enhance the resistance of DNA to enzymatic degradation strongly encourages the studies on the effects of heavy metal contamination in clay rich soils on the fate of extracellular soil DNA ...

  18. Thermostability of montmorillonitic clays

    Directory of Open Access Journals (Sweden)

    Petr Jelínek

    2014-05-01

    Full Text Available Bentonite is one of the most widespread used clays connected with various applications. In the case of foundry technology, bentonite is primarily used as a binder for mold manufacture. Thermal stability of bentonites is a natural property of clay minerals and it depends on the genesis, source and chemical composition of the clay. This property is also closely connected to bentonite structure. According to DTA analysis if only one peak of dehydroxylation is observed (about 600 ºC, the cis- isomerism of bentonite is expected, while two peaks of de-hydroxylation (about 550 and 850 ºC are expected in the trans- one. In this overview, the bentonite structure, the water – bentonite interaction and the swelling behavior of bentonite in connection with the general technological properties of bentonite molding mixture are summarized. Further, various types of methods for determination of bentonite thermostability are discussed, including instrumental analytical methods as well as methods that employ evaluation of various technological properties of bentonite binders and/or bentonite molding mixtures.

  19. LABORATORY TESTING OF BENTONITE CLAYS FOR LANDFILL DESIGN AND CONSTRUCTION

    Directory of Open Access Journals (Sweden)

    Biljana Kovačević Zelić

    2007-12-01

    Full Text Available Top and bottom liners are one of the key construction elements in every landfill. They are usually made as compacted clay liners (CCLs composed of several layers of compacted clay with strictly defined properties or by the use of alternative materials such as: GCL – geosynthetic clay liner, BES – bentonite enhanced soils or bentonite/polymer mixtures. Following the state of the art experiences in the world, GCLs are used in Croatian landfills for several years, as well. Depending upon the location and the obeying function, GCLs have to fulfill certain conditions. A legislated compatibility criterion has to be proven by various laboratory tests. In the paper are presented the results of direct shear and chemical compatibility tests of GCLs as well as the results of permeability measurement of kaolin clay (the paper is published in Croatian .

  20. Developments in modelling of thermohydro-geomechanical behaviour of Boom clay and clay-based buffer materials (Volume 1)

    International Nuclear Information System (INIS)

    The results of two years of research on thermomechanics of clays performed within CEC contract Fl1W/0150 are described herein. Previous studies (research contracts with CEC/WAS/380.83.7 l) performed by ISMES have evidenced the need for an improved modelling of the volumetric response of natural clays. In a coupled approach, this leads to an improved prediction of pore-pressure development and dissipation. This is crucial for assessing conditions of a possible local thermal failure as verified in laboratory tests done at ISMES. The first part of the study lays the foundations of a comprehensive theoretical treatment of the interaction between water and soil skeleton. It consists in: (a) developing a framework for inclusion of water/soil particle thermally induced interaction into a thermodynamically consistent mixture theory approach (Section 2); (b) studying possible modelling approaches of considering the effective thermal expansion coefficient of pore water dependency on pore water status (Section 2); (c) testing artificial clays to assess pore water thermal expansion dependence on temperature in the presence of different amounts of active clay minerals and also Boom clay (Section 3); (d) performing a laboratory test campaign on Boom clay with special attention to the response in the overconsolidated domain (Section 4). 89 figs., 18 tabs., 102 refs

  1. Contribuição dos constituintes da fração argila de solos subtropicais à área superficial específica e à capacidade de troca catiônica Contribution of clay fraction minerals of subtropical soils to the specific surface area and cation exchange capacity

    Directory of Open Access Journals (Sweden)

    Ivan Granemann de Souza Junior

    2007-12-01

    area (SSA is related to several properties that define the soil physico-chemical behavior. In this research, 23 soil samples developed from different parent materials found in the southern Brazil were used. They were evaluated for the contribution of the main soil constituents to the effective cation exchange capacity (CECe and SSA. The clay fraction minerals were identified by X ray diffraction (XRD and quantified by thermal analysis; the CECe, the SSAt (total by the ethylene glycol monoethyl ether method (EGME, the SSAe (external by the BET-N2 method, and the ASEi (internal by the difference of the values obtained with the two methods. The clay fraction samples were determined before and after the following sequential selective dissolution procedures: removal of organic matter (clay-NaOCl; removal of organic matter and free iron oxides (clay-NaOCl + DCB; removal of kaolinite, gibbsite and low cristalinity aluminosilicate minerals (clay-NaOCl+DCB + NaOH 5 mol L-1. The mineralogy of the clay fraction of the soils varied considerably, as verified by X ray diffraction, thermogravimetric analysis, and SSA and CECe values. For most soils kaolinite is the predominant mineral in the clay fraction, followed by expandable 2:1 clay mineral or iron and aluminum oxihydroxides. SSA and CECe of the natural clay fraction were not correlated due to the occlusion of the clay surface by organic matter. Iron oxide aggregate effects reduced SSAe by 21 %. For the studied samples, the 2:1 clay minerals were present in concentrations varying from 3 to 65 % of the silicate fraction and presented average values of 1.054 mmol c kg-1 and 202 m² g-1 for CECe and SSEt, respectively. SSAi contributed with 58 % of SSAt of the clay fraction, mostly due to 2:1 clay type minerals.

  2. Deformation mechanisms in experimentally deformed Boom Clay

    Science.gov (United States)

    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

  3. Chlordecone retention in the fractal structure of volcanic clay

    International Nuclear Information System (INIS)

    Highlights: ► Allophanic soils are highly polluted but less contaminant for cultivated vegetables. ► SAXS and TEM show the fractal structure of allophane aggregates at the nanoscale. ► Allophane aggregates play the role of a labyrinth which fixes and traps chlordecone. ► Allophane physical properties contribute to chlordecone retention in andosols. - Abstract: Chlordecone (CHLD), a soil and foodstuff pollutant, as well as an environmentally persistent organochlorine insecticide, was used intensively in banana fields. The chlordecone uptake of three crops was measured for two types of polluted soils: allophanic and non-allophanic. The uptake is lower for allophanic soils even if their chlordecone content is higher than with non-allophanic soils. The fractal structure of the allophane aggregates was characterized at the nanoscale by small angle X-rays scattering, pore size distribution and transmission electron microscopy. We showed that clay microstructures should be an important physico-chemical factor governing the fate of chlordecone in the environment. Allophanic clays result in two counterintuitive findings: higher contaminant trappings yet lower contaminant availability. We propose that this specific, tortuous structure, along with its associated low accessibility, partly explains the low availability of chlordecone confined in allophanic soils. Capsule The fractal and tortuous microstructure of allophane clay favours the chlordecone retention in soils and disfavours the crop uptake.

  4. Chlordecone retention in the fractal structure of volcanic clay

    Energy Technology Data Exchange (ETDEWEB)

    Woignier, Thierry, E-mail: thierry.woignier@imbe.fr [IRD, UMR 237, IMBE, PRAM B.P. 214 Petit Morne, 97232, Le Lamentin, Martinique (France); CNRS, UMR 7263, IMBE, PRAM B.P. 214 Petit Morne, 97232, Le Lamentin, Martinique (France); Aix Marseille Universite, IMBE, Faculte des Sciences et Techniques de Saint Jerome, avenue Escadrille Normandie Niemen, F-13397 Marseille Cedex 20 (France); Clostre, Florence [Cirad/PRAM, UPR fonctionnement agroecologique et performances des systemes de culture horticoles, B.P. 214 Petit Morne, 97232, Le Lamentin, Martinique (France); Macarie, Herve [IRD, UMR 237, IMBE, PRAM B.P. 214 Petit Morne, 97232, Le Lamentin, Martinique (France); Cirad UR HortSys, TA B-103/PS4, Boulevard de la Lironde, 34398, Montpellier Cedex 5 (France); Jannoyer, Magalie [Cirad/PRAM, UPR fonctionnement agroecologique et performances des systemes de culture horticoles, B.P. 214 Petit Morne, 97232, Le Lamentin, Martinique (France); Cirad UR HortSys, TA B-103/PS4, Boulevard de la Lironde, 34398, Montpellier Cedex 5 (France)

    2012-11-30

    Highlights: Black-Right-Pointing-Pointer Allophanic soils are highly polluted but less contaminant for cultivated vegetables. Black-Right-Pointing-Pointer SAXS and TEM show the fractal structure of allophane aggregates at the nanoscale. Black-Right-Pointing-Pointer Allophane aggregates play the role of a labyrinth which fixes and traps chlordecone. Black-Right-Pointing-Pointer Allophane physical properties contribute to chlordecone retention in andosols. - Abstract: Chlordecone (CHLD), a soil and foodstuff pollutant, as well as an environmentally persistent organochlorine insecticide, was used intensively in banana fields. The chlordecone uptake of three crops was measured for two types of polluted soils: allophanic and non-allophanic. The uptake is lower for allophanic soils even if their chlordecone content is higher than with non-allophanic soils. The fractal structure of the allophane aggregates was characterized at the nanoscale by small angle X-rays scattering, pore size distribution and transmission electron microscopy. We showed that clay microstructures should be an important physico-chemical factor governing the fate of chlordecone in the environment. Allophanic clays result in two counterintuitive findings: higher contaminant trappings yet lower contaminant availability. We propose that this specific, tortuous structure, along with its associated low accessibility, partly explains the low availability of chlordecone confined in allophanic soils. Capsule The fractal and tortuous microstructure of allophane clay favours the chlordecone retention in soils and disfavours the crop uptake.

  5. Clays, clay minerals and cordierite ceramics - a review

    OpenAIRE

    Marta Valaskova

    2015-01-01

    The conventional methods for the synthesis of cordierite ceramics include the solid-state sintering of individual oxides of magnesium, aluminium and silicon of the corresponding chemical composition of cordierite, or sintering of the natural raw materials. Clays are used in the ceramics industries largely because of their contribution to the molding and drying properties. The most effective use of clays meets with the problems of the improvement of the working properties of clays and...

  6. Novel clay carriers for the controlled release of organic agrochemicals

    International Nuclear Information System (INIS)

    Controlled-release (CR) formulations of alachlor and atrazine herbicides were prepared using sodium alginate and pectine as natural, biodegradable matrices and clay minerals as inert fillers. The release of the two herbicides from different type of CR formulations was studied in static water. The release of alachlor from alginate based formulations and a commercial formulation in sandy loam soil and its movement in a soil column was also studied. The rate of release was affected by the type of clay and the size of the formulation beads. The addition of Fisher bentonite to the alginate reduced the rate of release of herbicides. The release was slower from the larger beads and from those prepared using high viscosity alginate. The release of alachlor in the soil and its movement through the soil column was faster from the commercial formulation than the CR formulation. (author). 6 refs, 10 figs, 2 tabs

  7. Submicron structures provide preferential spots for carbon and nitrogen sequestration in soils

    OpenAIRE

    Vogel, Cordula; Mueller, Carsten W.; Höschen, Carmen; Buegger, Franz; Heister, Katja; Schulz, Stefanie; Schloter, Michael; Kögel-Knabner, Ingrid

    2014-01-01

    The sequestration of carbon and nitrogen by clay-sized particles in soils is well established, and clay content or mineral surface area has been used to estimate the sequestration potential of soils. Here, via incubation of a sieved (

  8. Selected Properties and Systematic Position of Soils Developed from Red Sandstones and Clays of the Lower Triassic Buntsandstein in the Nw Part of the Holy Cross Mountains (Poland / Niektóre właściwości i pozycja systematyczna gleb wytworzonych z czerwonych piaskowców i iłów dolnego triasu w NW obrzeżeniu Gór Świętokrzyskich

    Directory of Open Access Journals (Sweden)

    Zagórski Zbigniew

    2015-09-01

    Full Text Available The aim of the study was to compare the properties of soils developed from the Lower Triassic Buntsandstein sediments in the north-western part of the Holy Cross Mountains (Poland. These are deposits of continental genesis and unique features such as red beds. Two representative soil pedons - the Bartków profile (pBK developed from clay and the Góra Czerwona profile (pGC developed from sandstone were selected for detailed analyzes. The morphology of profiles, their micromorphological features, mineralogical composition, and physico-chemical properties were examined. Most of the properties of the soils are a consequence of the original parent rock lithology. A specific feature of the morphology of the soils are the presence of red color (about 10R by the Munsell color scale related to the presence of hematite. As shown by the XRD data, hematite is not the product of the current soil-forming processes, but it is a lithogenic component, which was inherited from the parent rock. Under the influence of climatic factors primary rock structure has been transformed into a new pedogenic one. Soils developed from clays have a characteristic angular blocky structure. Micromorphological analysis showed that an important role in the formation of soil structure involves geogenic susceptibility of Triassic clays to specific cuboid disintegration. This is indicated by the pore system of planes as an orthogonal nets visible in thin section. The soils developed from sandstone have a weak (unstable subangular blocky structure. The main reason is the insufficient dispersion of the clay-ferruginous fraction from the sandstone matrix. Microscopic observations indicate that fine factions occurs as loose microaggregates, which results in a feature that smaller rock fragments and individual quartz grains are not bonded into soil aggregates. The studied soils are characterized by specific physical-chemical properties. Some of them strongly depend on the mineralogical

  9. Soils

    International Nuclear Information System (INIS)

    For Austria there exists a comprehensive soil data collection, integrated in a GIS (geographical information system). The content values of pollutants (cadmium, mercury, lead, copper, mercury, radio-cesium) are given in geographical charts and in tables by regions and by type of soil (forests, agriculture, greenland, others) for the whole area of Austria. Erosion effects are studied for the Austrian region. Legal regulations and measures for an effective soil protection, reduction of soil degradation and sustainable development in Austria and the European Union are discussed. (a.n.)

  10. Potentials for the Modified Cam-Clay model

    OpenAIRE

    Zouain, Nestor; Pontes, Ivaldo; Vaunat, Jean

    2009-01-01

    Abstract Energy and dissipation pseudo-potentials are employed to derive constitutive relationships, in the context of thermodynamic concepts, for the widely used Modified Cam-Clay (MCC) model for soil mechanics. A variational formulation of the MCC evolution equations is proposed in this paper. Since plastic collapse of MCC soils cannot be embedded in the classical limit analysis theory, finding the critical amplification of the load that produces plastic collapse is formulated in...

  11. Clay Mineral Image Collection for Education in Geotechnical Engineering and the Earth Sciences

    OpenAIRE

    Stone, Gordon; Dove, Joseph E.; Han, Nizhou; Dove, Patricia

    2015-01-01

    This file contains a collection of scanning electron microscope images of Kaolinite and Bentonite pure clay minerals, and the fine portion of a natural soil. National Science Foundation Grant No. 1301124

  12. Spectromicroscopy of Fe distributions in clay microcrystals

    Energy Technology Data Exchange (ETDEWEB)

    Grundl, T. [Univ. of Wisconsin, Milwaukee, WI (United States); Cerasari, S.; Garcia, A. [Lawrence Berkeley National Lab., CA (United States)] [and others

    1997-04-01

    Clays are ubiquitous crystalline particles found in nature that are responsible for contributing to a wide range of chemical reactions in soils. The structure of these mineral particles changes when the particle is hydrated ({open_quotes}wet{close_quotes}), from that when it is dry. This makes a study of the microscopic distribution of chemical content of these nanocrystals difficult using standard techniques that require vacuum. In addition to large structural changes, it is likely that chemical changes accompany the drying process. As a result, spectroscopic measurements on dried clay particles may not accurately reflect the actual composition of the material as found in the environment. In this work, the authors extend the use of the ALS Spectromicroscopy Facility STXM to high spectral and spatial resolution studies of transition metal L-edges in environmental materials. The authors are studying mineral particles of montmorillonite, which is an Fe bearing clay which can be prepared with a wide distribution of Fe concentrations, and with Fe occupying different substitutional sites.

  13. Cyclic Shearing Deformation Behavior of Saturated Clays

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The apparatus for static and dynamic universal triaxial and torsional shear soil testing is employed to perform stress-controlled cyclic single-direction torsional shear tests and two-direction coupled shear tests under unconsolidated-undrained conditions. Through a series of tests on saturated clay, the effects of initial shear stress and stress reversal on the clay's strain-stress behavior are examined, and the behavior of pore water pressure is studied. The experimental results indicate that the patterns of stress-strain relations are distinctly influenced by the initial shear stress in the cyclic single-direction shear tests. When the initial shear stress is large and no stress reversal occurs, the predominant deformation behavior is characterized by an accumulative effect. When the initial shear stress is zero and symmetrical cyclic stress occurs, the predominant deformation behavior is characterized by a cyclic effect. The pore water pressure fluctuates around the confining pressure with the increase of cycle number. It seems that the fluctuating amplitude increases with the increase of the cyclic stress. But a buildup of pore water pressure does not occur. The deformations of clay samples under the complex initial and the cyclic coupled stress conditions include the normal deviatoric deformation and horizontal shear deformation, the average deformation and cyclic deformation. A general strain failure criterion taking into account these deformations is recommended and is proved more stable and suitable compared to the strain failure criteria currently used.

  14. Distribución de la porosidad de un suelo franco arcilloso (alfisol en condiciones semiáridas después de 15 años bajo siembra directa Soil porosity distribution of a clay loam soil (alfisol in semi-arid conditions after 15 years under direct drilling

    Directory of Open Access Journals (Sweden)

    Cecilia Isabel Cerisola

    2005-12-01

    Full Text Available A partir de un estudio más amplio sobre evolución de las propiedades físicas de un suelo sometido a tres sistemas de labranza, se realizó, en dos campañas consecutivas, un seguimiento de la distribución de la porosidad del suelo según su origen, en parcelas cultivadas bajo siembra directa continua durante 15 años. En el ensayo se consideró un trayecto de 2 metros de longitud, perpendicular a la dirección de las labores, donde se realizaron mediciones de densidad aparente seca y contenido de humedad. El cultivo extensivo de secano (cereal, en cada una de las dos campañas, fue cebada de ciclo corto y de ciclo largo. El calendario de la toma de datos de las variables medidas se fijó en 5 fechas por campaña. La porosidad estructural del suelo, debida principalmente a la alternancia de ciclos de humectación - desecación, fue calculada cada 5 cm y hasta 35 cm de profundidad. Este proceso de fisuración natural resulta suficiente para asegurar un buen drenaje y facilitar el desarrollo radicular de las plantas, siempre y cuando el contenido de humedad se mantenga dentro de la capacidad de retención de agua.On a long-term essay under direct drilling, the evolution of the physical properties of a clay loam soil, such as distribution by origin of soil porosity, has been assessed during two growing seasons. The cereal crops in each growing seasons were spring barley and winter barley, respectively. Soil physical properties were measured on a 2 m length transect located in a perpendicular line to the direction of vehicular traffic for field operations. Five sampling opportunities, within crop cycle, were used to measure the variables. Structural soil porosity, due principally to shrinkage and swelling cycles, was assessed in the 0 to 35 cm depth soil profile. This natural process seemed to be sufficient to guarantee good drainage and normal crop development, unless in the moisture content range included in field capacity.

  15. Electrokinetic-enhanced bioaugmentation for remediation of chlorinated solvents contaminated clay

    OpenAIRE

    Mao, Xuhui; Wang, James; Ciblak, Ali; Cox, Evan E.; Riis, Charlotte; Terkelsen, Mads; Gent, David B.; Alshawabkeh, Akram N

    2012-01-01

    Successful bioremediation of contaminated soils is controlled by the ability to deliver bioremediation additives, such as bacteria and/or nutrients, to the contaminated zone. Because hydraulic advection is not practical for delivery in clays, electrokinetic (EK) injection is an alternative for efficient and uniform delivery of bioremediation additive into low-permeability soil and heterogeneous deposits. EK–enhanced bioaugmentation for remediation of clays contaminated with chlorinated solven...

  16. Cation exchange and adsorption on clays and clay minerals

    OpenAIRE

    Ammann, Lars

    2003-01-01

    The specific surface area of a clay mineral comprises the external and internal surface area and, finally, the surface area which is exposed to the solution (Chap. 6.1). The aim of this study was to correlate adsorption data of common clays with these specific surface areas.

  17. Euroclay 95. Clays and clay materials sciences. Book of abstracts

    International Nuclear Information System (INIS)

    The document contains the abstracts of the invited lecturers (18) and posters (247) presented at EUROCLAY '95. Clays and clay materials sciences. 13 items (4 from the invited lecturers and 12 from posters) have been considered within the INIS Subject Scope and indexed separately

  18. Impact of Oriented Clay Particles on X-Ray Spectroscopy Analysis

    Science.gov (United States)

    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.

  19. Clay resources in the Netherlands

    NARCIS (Netherlands)

    Meulen, M.J. van der; Maljers, D.; Gessel, S.F. van; Gruijters, S.H.L.L.

    2007-01-01

    Clay is a common lithology in the Dutch shallow subsurface. It is used in earth constructions such as dikes, and as raw material for the fabrication of bricks, roof tiles etc. We present a new national assessment of Dutch clay resources, as part of a project that provides mineral-occurrence informat

  20. Clay resources in the Netherlands

    NARCIS (Netherlands)

    Meulen, M.J. van der; Maljers, D.; Gessel, S.F. van; Gruijters, S.H.L.L.

    2007-01-01

    Clay is a common lithology in the Dutch shallow subsurface. It is used in earth constructions such as dikes, and as raw material for the fabricationof bricks, roof tiles etc. We present a new national assessment of Dutch clay resources, as part of a project that provides mineral-occurrenceinformatio

  1. Fluoride retention by kaolin clay

    DEFF Research Database (Denmark)

    Kau, P. M. H.; Smith, D. W.; Binning, Philip John

    1997-01-01

    To evaluate the potential effectiveness of kaolin clay liners in storage of fluoride contaminated waste, an experimental study of the sorption and desorption behaviour of fluoride in kaolin clay was conducted. The degree of fluoride sorption by kaolin was found to depend on solution pH and...

  2. Strength Properties of Aalborg Clay

    DEFF Research Database (Denmark)

    Iversen, Kirsten Malte; Nielsen, Benjaminn Nordahl; Augustesen, Anders Hust

    In the northern part of Vendsyssel, Denmark, the deposits made in the late glacial time are formed by the sea. The deposits are named after two mussels: Yoldia clay and Saxicava sand. However, in the southern part of Vendsyssel and in the area of Aalborg the clay and sand deposits from the late g...

  3. Influence of clay mineralogy on clay based ceramic products

    International Nuclear Information System (INIS)

    Clay-based ceramic products can either be produced directly from a suitable clay source without the need further addition or such products can be produced from a ceramic body formulated by additions of other raw materials such as feldspar and silica sand. In either case, the mineralogical make-up of the clay component plays a dominating role in the fabrication and properties of the ceramic product. This study was sparked off by a peculiar result observed in one of five local ball clay samples that were used to reformulate a ceramic body. Initial characterisation tests conducted on the clays indicated that these clays can be classified as kaolinitic. However, one of these clays produced a ceramic body that is distinctively different in terms of whiteness, smoothness and density as compared to the other four clays. Careful re-examination of other characterisation data, such as particle size distribution and chemical analysis, failed to offer any plausible explanation. Consequently, the mineralogical analysis by x-ray diffraction was repeated by paying meticulous attention to specimen preparation. Diffraction data for the clay with anomalous behaviour indicated the presence of a ∼ 10A peak that diminished when the same specimen was re-tested after heating in an oven at 12O degree C whilst the other four clays only exhibit the characteristic kaolinite (Al sub 2 O sub 3. 2SiO sub 2. 2H sub 2 0) and muscovite peaks at ∼ 7A and ∼ 10A before and after heat treatment. This suggests the presence of the mineral halloysite (A1 sub 2 0 sub 3. 2SiO sub 2.4H sub 2 0) in that particular clay. This difference in mineralogy can be attributed to account for the variations in physical properties of the final product. Consequently, this paper reviews in general the precautionary measures that must be adhered to during any mineralogical investigation of clay minerals or clay-based materials. The common pitfalls during specimen preparation, machine settings and interpretation of

  4. Developments in modelling of thermohydro-geomechanical behaviour of Boom clay and clay-based buffer materials (volume 2)

    International Nuclear Information System (INIS)

    This study is composed of two parts: The first part (Volume 1) lays the foundations of a comprehensive theoretical treatment of the interaction between water and soil skeleton during thermal dilatation. The second part (volume 2) is devoted to the development and the application of advance constitutive modelling of mechanical behaviour of clays taking into account the extensive tests of Boom clay reported in the first volume. The development concentrated on the improvement of prediction of the volumetric response of clay skeleton: (a) improving the dilatancy prediction at low to high overconsolidation ratios (Section 2). An elasto-plastic constitutive model has been developed to account for this effect (Section 3.2.); (b) modelling of swelling effects (Section 2.5). A preliminary interpretative model for swelling prediction has been developed (Section 2.5). The application part consisted in interpreting the experimental results obtained for Boom clay to calibrate a set of constants (Section 3) for performing numerical analyses (Section 4) for the thermomechanical model already calibrated for Boom clay (Appendix). Interpretation of the tests required an assessment of influence of the strong anisotropy effects revealed by Boom clay on the basis of an interpretative model characterized by a kinematic hardening plasticity and coupled elasticity (section 3)

  5. Evaluation of some ceramic clays from Zambia

    OpenAIRE

    Mitchell, C J

    1993-01-01

    This reports details the technical evaluation of ceramic clays collected during visits to Zambia in 1990 and 1991 by the author (Clive Mitchell). The clay samples included: Choma kaolin (Southern Province), Twapia kaolin (Copperbelt Province), Kapiri Mposhi kaolin (Central Province), Masenche clay (Northern Province), Leula clay, Misenga clay and Chikankata clay (Southern Province). The Choma kaolin was asessed to be an excellent source of ceramic-grade kaolin. The Twapia and Kapiri Mposhi ka...

  6. Influence of soil texture on carbon dynamics and storage potential in tropical forest soils of Amazonia

    OpenAIRE

    Telles, Everaldo de Carvalho Conceicao; Camargo, Plinio Barbosa; Luiz A Martinelli; Trumbore, Susan E.; da Costa, Enir Salazar; Santos, Joaquim; Higuchi, Niro; de Oliveira, Raimundo Cosme

    2003-01-01

    Stable and radiocarbon isotopes were used to investigate the role of soil clay content in the storage and dynamics of soil carbon in tropical forest soils. Organic matter in clay-rich Oxisols and Ultisols contains at least two distinct components: (1) material with light δ13C signatures and turnover times of decades or less; and (2) clay-associated, 13C-enriched, carbon with turnover times of decades at the surface to millennia at depths >20 cm. Soil texture, in this case clay content, exerts...

  7. Influence of soil texture on carbon dynamics and storage potential in tropical forest soils of Amazonia

    OpenAIRE

    Telles, E.; de Camargo, P.; Martinelli, L.; Trumbore, S.; Da Costa, E; Santos, J.; N. Higuchi; de Oliveira, R.

    2003-01-01

    [1] Stable and radiocarbon isotopes were used to investigate the role of soil clay content in the storage and dynamics of soil carbon in tropical forest soils. Organic matter in clay-rich Oxisols and Ultisols contains at least two distinct components: ( 1) material with light delta(13)C signatures and turnover times of decades or less; and ( 2) clay-associated, C-13-enriched, carbon with turnover times of decades at the surface to millennia at depths > 20 cm. Soil texture, in this case clay c...

  8. Reduction of soil tare by improved uprooting of sugar beet : a soil dynamic approach

    NARCIS (Netherlands)

    Vermeulen, G.D.

    2001-01-01

    The relative amount of soil in sugar beet lots, called soil tare, should be reduced to curtail the cost and negative aspects of soil tare. Highest soil tare occurs in beet lots harvested out of wet clay soil. The main problem is that commonly-used share lifters press the soil against the beet. There

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

    Science.gov (United States)

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

    2013-04-01

    -del Hoyo, C. (2007). Applied Clay Science. 36, 103-121.Layered Double Hydroxides and human health: An overview. -Valderrábano, M., Rodríguez-Cruz, S., del Hoyo, C., Sánchez-Martín, M.J. (2006). 4th International Workshop "Bioavalailability of pollutants and soil remediation". 1, 5-6. Physicochemical study of the adsorption of pesticides by lignins. -Volzone, C. (2007). Applied Clay Science. 36, 191-196. Retention of pollutant gases: Comparison between clay minerals and their modified products.

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

    Energy Technology Data Exchange (ETDEWEB)

    Ng, C.W.W.; Chen, Z.K.; Coo, J.L. [Department of Civil and Environmental Engineering, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon (Hong Kong); Chen, R., E-mail: chenrui1005@hotmail.com [Shenzhen Key Laboratory of Urban and Civil Engineering for Disaster Prevention and Mitigation, Harbin Institute of Technology Shenzhen Graduate School, Shenzhen 518055 (China); Zhou, C. [Department of Civil and Environmental Engineering, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon (Hong Kong)

    2015-10-15

    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 pressure 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

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

    International Nuclear Information System (INIS)

    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 pressure 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

  12. Predicting radiocaesium sorption characteristics with soil chemical properties for Japanese soils.

    Science.gov (United States)

    Uematsu, Shinichiro; Smolders, Erik; Sweeck, Lieve; Wannijn, Jean; Van Hees, May; Vandenhove, Hildegarde

    2015-08-15

    The high variability of the soil-to-plant transfer factor of radiocaesium (RCs) compels a detailed analysis of the radiocaesium interception potential (RIP) of soil, which is one of the specific factors ruling the RCs transfer. The range of the RIP values for agricultural soils in the Fukushima accident affected area has not yet been fully surveyed. Here, the RIP and other major soil chemical properties were characterised for 51 representative topsoils collected in the vicinity of the Fukushima contaminated area. The RIP ranged a factor of 50 among the soils and RIP values were lower for Andosols compared to other soils, suggesting a role of soil mineralogy. Correlation analysis revealed that the RIP was most strongly and negatively correlated to soil organic matter content and oxalate extractable aluminium. The RIP correlated weakly but positively to soil clay content. The slope of the correlation between RIP and clay content showed that the RIP per unit clay was only 4.8 mmol g(-1) clay, about threefold lower than that for clays of European soils, suggesting more amorphous minerals and less micaceous minerals in the clay fraction of Japanese soils. The negative correlation between RIP and soil organic matter may indicate that organic matter can mask highly selective sorption sites to RCs. Multiple regression analysis with soil organic matter and cation exchange capacity explained the soil RIP (R(2)=0.64), allowing us to map soil RIP based on existing soil map information. PMID:25897723

  13. Collective Structural Changes in Vermiculite Clay Suspensions Induced by Cesium Ions

    Science.gov (United States)

    Motokawa, Ryuhei; Endo, Hitoshi; Yokoyama, Shingo; Nishitsuji, Shotaro; Kobayashi, Tohru; Suzuki, Shinichi; Yaita, Tsuyoshi

    2014-10-01

    Following the Fukushima Daiichi nuclear disaster in 2011, Cs radioisotopes have been dispersed over a wide area. Most of the Cs has remained on the surface of the soil because Cs+ is strongly adsorbed in the interlayer spaces of soil clays, particularly vermiculite. We have investigated the microscopic structure of an aqueous suspension of vermiculite clay over a wide length scale (1-1000 Å) by small-angle X-ray scattering. We determined the effect of the adsorption behavior of Cs+ on the structural changes in the clay. It was found that the abruption of the clay sheets was induced by the localization of Cs+ at the interlayer. This work provides important information for predicting the environmental fate of radioactive Cs in polluted areas, and for developing methods to extract Cs from the soil and reduce radioactivity.

  14. Importância das espécies minerais no potássio total da fração argila de solos do Triângulo Mineiro Importance of mineral species in total potassium content of clay fraction in soils of the Triângulo Mineiro, Minas Gerais State, Brazil

    Directory of Open Access Journals (Sweden)

    V. F. Melo

    2003-10-01

    arenito da Formação Uberaba, migmatito/micaxisto do Grupo Araxá e basalto da Formação Serra Geral.Few studies relate the K reserve in soils developed in a humid tropic climate with the minerals found in the clay fraction. Nineteen soils were collected for this purpose in the Triângulo Mineiro region, Minas Gerais State, Brazil, developed from different parent materials and different weathering degrees. Due to the greater occurrence, a larger number of samples of the Bauru Group was collected, comprising all the geological formations found in the region. The total K content in soil and the sand, silt, and clay fractions were determined after the digestion of the soil samples by HF, HNO3 and H2SO4. To quantify the contribution of each mineral species to the total K content, Na-saturated clay samples were submitted by a sequential and selective mineral extraction procedure, following the order: amorphous Al and Fe oxides; crystalline Fe oxides; kaolinite and gibbsite; mica and other 2:1 minerals and; feldspar and resistant minerals. The clay mineralogy composition reflects the high weathering and leaching degree in soils of the Triângulo Mineiro, with low contents of amorphous minerals, a predominant proportion of kaolinite and the presence of other secondary resistant minerals. In spite of this mineral composition, the clay fraction presented the highest total K content, mainly in the most weathered soils. Due to the high proportion of kaolinite in the clay fraction, this mineral was an important source of non-exchangeable K forms. On the other hand, the contribution of amorphous Fe and Al oxides and crystalline Fe oxides to the total K content of the clay fraction was negligible. In general, easily weathered primary minerals (mica and feldspar contributed largely to the total K of the clay fraction, principally to the youngest soils developed from the Uberaba (sandstone and Serra Geral (basalt Formations, and the Araxá Group (migmatite/micaschist.

  15. Assessment of Time Functions for Piles Driven in Clay

    DEFF Research Database (Denmark)

    Augustesen, Anders; Andersen, Lars; Sørensen, Carsten Steen

    The vertical bearing capacity of piles situated in clay is studied with regard to the long-term set-up. A statistical analysis is carried out on the basis of data from numerous static loading tests. The database covers a wide range of both soil and pile properties, which ensures a general...... alternative models. In the first of these models, the rate of set-up is independent of the soil properties, whereas the second function depends on the undrained shear strength. Based on the available data, there is no statistical evidence that the magnitude of set-up depends on the properties of the soil...

  16. The effect of intrinsic soil properties on soil quality assessments

    OpenAIRE

    2013-01-01

    The assessment of soil quality is based on indicators and indices derived from soil properties. However, intrinsic soil properties may interfere with other soil properties that vary under different land uses and are used to calculate the indices. The aim of this study was to assess the extent to which intrinsic soil properties (clay and iron oxide contents) explain variable soil properties (sum of bases, potential acidity, organic carbon, total porosity, and bulk density) under different land...

  17. Clay energetics in chemical evolution

    Science.gov (United States)

    Coyne, L. M.

    1986-01-01

    Clays have been implicated in the origin of terrestrial life since the 1950's. Originally they were considered agents which aid in selecting, concentrating and promoting oligomerization of the organic monomeric substituents of cellular life forms. However, more recently, it has been suggested that minerals, with particular emphasis on clays, may have played a yet more fundamental role. It has been suggested that clays are prototypic life forms in themselves and that they served as a template which directed the self-assembly of cellular life. If the clay-life theory is to have other than conceptual credibility, clays must be shown by experiment to execute the operations of cellular life, not only individually, but also in a sufficiently concerted manner as to produce some semblance of the functional attributes of living cells. Current studies are focussed on the ability of clays to absorb, store and transfer energy under plausible prebiotic conditions and to use this energy to drive chemistry of prebiotic relevance. Conclusions of the work are applicable to the role of clays either as substrates for organic chemistry, or in fueling their own life-mimetic processes.

  18. Boom clay pore water chemistry

    International Nuclear Information System (INIS)

    In Belgium, geological disposal in clay is the primary option for the isolation of high-level radioactive waste and spent fuel from the biosphere. The Boom Clay is studied as the potential host rock for methodological studies on the geological disposal of radioactive waste. It is present under the facilities of the SCK-CEN at Mol, at a depth of 190 to 293 m. The current R and D programme focuses on the feasibility and safety of radioactive waste disposal in the Boom Clay. In this framework, a detailed characterisation of the clay is performed (mechanical, physico-chemical and hydrogeological properties, variability, role of organic matter,...). In addition, high priority is given to the understanding of the basic phenomena which control the retention o f radionuclides in the clay. Therefore, it is very important to characterise and understand the pore water composition in the host rock. All the available information from previous studies on the Boom Clay pore water chemistry was synthesise d in a 'state of the art' report, status 2004. This report describes the pore water sampling and analytical techniques, the results, and interpretation of a series of studies carried out in-situ in the HADES URF and in the laboratories. The objective of this study was to evaluate the most reliable technique(s) to obtain representative pore water samples, to determine the variation of the pore water composition in the Boom Clay, to present a coherent geochemical model for explaining the mechanisms controlling the Boom Clay pore water composition, and to propose a reference pore water composition to be used in the laboratory experiments, for speciation calculations, and for assessments of perturbation that might influence the Boom Clay pore water. The main conclusions will be presented here. (authors)

  19. Shear Strength of Remoulding Clay Samples Using Different Methods of Moulding

    Science.gov (United States)

    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.

  20. Spatial and temporal variability of soil electrical conductivity related to soil moisture

    OpenAIRE

    José Paulo Molin; Gustavo Di Chiacchio Faulin

    2013-01-01

    Soil electrical conductivity (ECa) is a soil quality indicator associated to attributes interesting to site-specific soil management such as soil moisture and texture. Soil ECa provides information that helps guide soil management decisions, so we performed spatial evaluation of soil moisture in two experimental fields in two consecutive years and modeled its influence on soil ECa. Soil ECa, moisture and clay content were evaluated by statistical, geostatistical and regression analyses. Semiv...

  1. Development of a Large Scale Infiltration Tank for Determination of the Hydraulic Properties of Expansive Clays

    OpenAIRE

    TANG, Anh Minh; Ta, An-Ninh; Cui, Yu-Jun; THIRIAT, Jérémy

    2009-01-01

    International audience A large-scale infiltration tank was developed to study the water transfer in compacted expansive clay. Volumetric water content sensors were buried in a soil column for water content monitoring during infiltration. In addition to water content, soil suction and temperature at various locations and the heave at the soil surface were also monitored. Emphasis was put in minimizing the effect of sensors installation on water transfer and soil deformation. The results obt...

  2. Phosphorus speciation of clay fractions from long-term fertility experiments in Sweden

    OpenAIRE

    Eriksson, Ann Kristin; Gustafsson, Jon Petter; Hesterberg, Dean

    2015-01-01

    Phosphorus (P) losses from agricultural soils constitute a main driver for eutrophication of the Baltic Sea. There is limited knowledge about sorption and release processes of P in these soils, especially concerning the effects of fertilization. In this study, P speciation of the clay fractions from six different soils in long-term fertility experiments in Sweden was investigated by P K-edge XANES spectroscopy. As expected, unfertilized soils had lower concentrations of acid-digestible P comp...

  3. Prions, Radionuclides and Clays: Impact of clay interlayer "acidity" on toxic compound speciation

    Science.gov (United States)

    Charlet, L.; Hureau, C.; Sobolev, O.; Cuello, G.; Chapron, Y.

    2007-05-01

    The physical and chemical processes that are the basis of contaminant retardation in clay rich medium, such as soil or nuclear waste repository, have been studied at the molecular level by a combination of molecular dynamics (MD), electron paramagnetic spectroscopy (EPR) and neutron diffraction with isotopic substitution (NDIS). The speciation of contaminants such as Sm, a radionuclide analogue, and Cu, bound to Prion protein (PrP), has been studied upon adsorption in clay interlayers. We used as molecular probe the P5-Cu(II) complex, where the P5 pentapeptide(92-96 PrP residues) represents one of the five Cu(II) binding site present in PrP, the key protein involved in diseases known as transmissible spongiform encephalopathies. In both cases, the pH of the interlayer has been inferred from the metal ion coordination, here used as a molecular reporter. In circum neutral pH waters, samarium is present as Sm(OH)3° species and should not be adsorbed in clay interlayer by "cation exchange" unless its hydrolysis is altered. Samarium NDIS results indicate that whether the number of oxygen nearest neighbours varies only from 8.5 to 7, as Sm penetrates the interlayer, the number of hydrogen nearest neighbours drops from 12 to 6. The high affinity of clay for Sm shows that a change in Sm hydrolysis occurs in the clay interlayer, but is directly followed by the formation of a surface complex with montmorillonite siloxane plane functional groups which prevents the determination of a "local pH". Conversely, has been found to be a much more sensitive interlayer water pH probe. and this peptide domain is involved in the misfolding of the protein,a transconformation which may lead to the pathogenic PrPSc form. We have therefore studied by EPR spectroscopy the adsorption of Cu(II)-P5 complexes on montmorillonite, and found the clay to have a large and selective adsorption capacity for the various [Cu(P5)H-n](2-n)+ complexes where n is the number of deprotonated amido function

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

    OpenAIRE

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

    2002-01-01

    Smectite clay minerals are abundant in soils and sediments worldwide and are typically rich in Fe. While recent investigations have shown that the structural Fe(III) bound in clay minerals is reduced by microorganisms, previous studies have not tested growth with clay minerals as the sole electron acceptor. Here we have demonstrated that a pure culture of Shewanella oneidensis strain MR-1 as well as enrichment cultures of Fe(III)-reducing bacteria from rice paddy soil and subsurface sediments...

  5. Productivity of clay tailings from phosphate mining: I. Biomass crops

    International Nuclear Information System (INIS)

    Phosphate mining in Florida has waste products of phosphatic clay and quartz sand tailings, each making up about one-third of the original matrix (PO4 ore, sand, and clay). Phosphatic clay ponds typically occupy about 50% of the mined sites and normally require 10 to 15 yr before 40 to 50% solids are obtained. These clays contain no phytotoxic materials and are high in most plant nutrients. When surface water has disappeared, these clays are classified as clayey Haplaquents. A split-plot field experiment was conducted to study biomass yield, quality, plant nutrient concentrations, changes in soil nutrients, and 226Ra. Seven biomass crops -(i) elephantgrass (Pennisetum purpureum L. PI 300086), (ii) leucaena [Leucaena leucocephala (Lam.) De Wet], (iii) alemangrass [Echinochloa polystachya (H.B.K) Hitch], (iv) erianthus [Erianthus arundinaceum (Retz) Jews IK 76-63'], (v) desmodium (Desmodium cinerascens A. Gray), (vi) sweet sorghum [Sorghum bicolor (L.) Moench USDA M 81E], and (vii) forage sorghum [Sorghum bicolor (L.) Moench Pioneer 931] - were grown on the phosphatic clay with and without a 5-cm surface layer of quartz sand tailings. Nitrogen was the only fertilizer element applied for grass species and no fertilizer was applied for legumes during the 4-yr period. Dry biomass yield averaged over 4 yr for erianthus, leucaena, and elephantgrass averaged 139.6, 58.5, and 56.5 Mg ha-1 yr-1, respectively. Crude protein and digestibility were low in mature, whole-plant samples except for leucaena (122.0 g kg-1). Generally, all whole plants contained adequate concentrations of nutrients. Mehlich-I-extractable soil nutrient concentrations changed little over the 4-yr period. Radium-226 concentration in plant tissue (0.23 pCi g-1) was nearly six times higher than the concentration measured in plants from an unmined surface Spodosol (0.04 pCi g-1)

  6. Influence of salinity on bioremediation of oil in soil

    International Nuclear Information System (INIS)

    Spills from oil production and processing result in soils being contaminated with oil and salt. The effect of NaCl on degradation of oil in a sandy-clay loam and a clay loam soil was determined. Soils were treated with 50 g kg-1 non-detergent motor oil (30 SAE). Salt treatments included NaCl amendments to adjust the soil solution electrical conductivities to 40, 120, and 200 dS m-1. Soils were amended with nutrients and incubated at 25oC. Oil degradation was estimated from the quantities of CO2 evolved and from gravimetric determinations of remaining oil. Salt concentrations of 200 dS m-1 in oil amended soils resulted in a decrease in oil mineralized by 44% for a clay loam and 20% for a sandy-clay loam soil. A salt concentration of 40 dS m-1 reduced oil mineralization by about 10% in both soils. Oil mineralized in the oil amended clay-loam soil was 2-3 times greater than for comparable treatments of the sandy-clay loam soil. Amending the sandy-clay loam soil with 5% by weight of the clay-loam soil enhanced oil mineralization by 40%. Removal of salts from oil and salt contaminated soils before undertaking bioremediation may reduce the time required for bioremediation. (author)

  7. Predicted performance of clay-barrier landfill covers in arid and semi-arid environments.

    Science.gov (United States)

    Sadek, S; Ghanimeh, S; El-Fadel, M

    2007-01-01

    Conventional landfill cover systems for municipal solid waste include low-permeability compacted clay barriers to minimize infiltration into the landfilled waste. Such layers are vulnerable in climates where arid to semi-arid conditions prevail, whereby the clay cover tends to desiccate and crack, resulting in drastically higher infiltration, i.e., lower cover efficiency. To date, this phenomenon, which has been reported in field observations, has not been adequately assessed. In this paper, the performance of a cover system solely relying on a clay barrier was simulated using a numerical finite element formulation to capture changes in the clay layer and the corresponding modified hydraulic characteristics. The cover system was guided by USEPA Subtitle-D minimum requirements and consisted of a clay layer underlying a protective vegetated soil. The intrinsic characteristics of the clay barrier and vegetative soil cover, including their saturated hydraulic conductivities and their soil-water characteristic curves, were varied as warranted to simulate intact or "cracked" conditions as determined through the numerical analyses within the proposed methodology. The results indicate that the levels of percolation through the compromised or cracked cover were up to two times greater than those obtained for intact covers, starting with an intact clay hydraulic conductivity of 10(-5)cm/s. PMID:16987648

  8. Emprego de calcário e de superfosfato simples na cultura do algodoeiro em solo argiloso ácido Use of lime and of ordinary superphosphate for cotton cultivated on acid clay soil

    Directory of Open Access Journals (Sweden)

    Nelson M. da Silva

    1980-01-01

    liming experiment with cotton are discussed. This experiment was conducted on Latosolic B Terra Roxa soil, acid, with a pH index of 5.0, originally under "cerradão" vegetation, with 66% of clay, 4.3% of organic mater, 0.9, 0.8 and 0.5 (meq/100 ml of Al3+, Ca2+and Mg2+, respectively. The experimental design was a split-plot, with four replications. Dolomitic limestone was applied in the first year, on main plots at the levels of 0, 1.5, 3.0 and 6.0 t/ha. P and K were annually applied on split-plots, as a factorial 3 x 2, at the levels of 0, 60 and 120 kg/ha of P2O5, and 40 and 80 kg/ha of K2O, respectively, with ordinary superphosphate and potassium chloride. Four months after lime application, the neutralization of the exchangeable aluminum found by soil analysis was observed, at the highest level, the pH value increased up to 5.5 and values of calcium plus magnesium reached 3.0 meq. The linear effect upon cotton yield, due to liming, was significant during all the period of this study, increasing from the first to the third year. The effect of phosphorus was smaller, but positive and significant. Cotton plants did not react to potassium fertilization and interactions were not observed. Lime increased the concentrations of P, Ca and Mg in leaf blades, and decreased those of K, Fe, Mn and Al in the year when it was applied. There were no symptoms of K or micronutrient deficiencies due to the use of lime at high level.

  9. Activity of Cellulolytic Enzymes Immobilized on Some Organic and Inorganic Matter of Soil

    OpenAIRE

    H. Shariatmadari; G. Emtiazi; A. A. Safari Sinejani

    2002-01-01

    Soil organic matter and clay minerals adsorb and immobilize extracellular enzymes of microorganisms and increase soil enzymes stability. This study aims to clarify the relative importance of soil organic matter and clay minerals on the cellulolytic activities of soils. Fluca prepared cellulase was immobilized on some agricultural residues and clay minerals, avicel and a sample of soil. Immobilized exoglucanase and endoglucanase were assayed at different times. Activities of the immobilized en...

  10. Clays in radioactive waste disposal

    OpenAIRE

    Delage, Pierre; CUI, Yu-Jun; Tang, Anh-Minh

    2010-01-01

    Clays and argillites are considered in some countries as possible host rocks for nuclear waste disposal at great depth. The use of compacted swelling clays as engineered barriers is also considered within the framework of the multi-barrier concept. In relation to these concepts, various research programs have been conducted to assess the thermo-hydro-mechanical properties of radioactive waste disposal at great depth. After introducing the concepts of waste isolation developed in Belgium, Fran...

  11. Boron Enrichment in Martian Clay

    OpenAIRE

    James D Stephenson; Lydia J Hallis; Kazuhide Nagashima; Freeland, Stephen J.

    2013-01-01

    We have detected a concentration of boron in martian clay far in excess of that in any previously reported extra-terrestrial object. This enrichment indicates that the chemistry necessary for the formation of ribose, a key component of RNA, could have existed on Mars since the formation of early clay deposits, contemporary to the emergence of life on Earth. Given the greater similarity of Earth and Mars early in their geological history, and the extensive disruption of Earth's earliest minera...

  12. Barrier properties of natural clay minerals

    OpenAIRE

    Дудар, Т.В.; С.П. Бугера; В.М. Кадошніков; Б.П. Злобенко

    2009-01-01

     Clay minerals is a perfect material for geochemical barrier due to their high water resistivity, plasticity, high sorbing capacity, well developed surface and cheapness in extraction and processing. This work studies the peculiarities of uranium sorbtion on clay minerals on the example of bentonite and palygorskite clay from Cherkassy deposit, and clay usage as a barrier material.

  13. Barrier properties of natural clay minerals

    Directory of Open Access Journals (Sweden)

    Т.В. Дудар

    2009-01-01

    Full Text Available  Clay minerals is a perfect material for geochemical barrier due to their high water resistivity, plasticity, high sorbing capacity, well developed surface and cheapness in extraction and processing. This work studies the peculiarities of uranium sorbtion on clay minerals on the example of bentonite and palygorskite clay from Cherkassy deposit, and clay usage as a barrier material.

  14. Characterization of edible clay (multani mitti) using INAA (abstract)

    International Nuclear Information System (INIS)

    Multani Mitti is basically clay commonly used in cosmetics, medicines. It is also used for cleansing of body and hair and eating specially women (pregnant and lactating) and children. 16 Essential major, minor and trace elements (Ba, Co, Cr, Cs, Fe, K, Mg, Mn, Mo, Na, Rb, Se Sr, Ti, V and Zn) have been determined in Multani Mitti (MM) clay using instrumental neutron activation analysis (INAA) technique were studied in collected clay samples from Rakhi Gaj located 40 Km from D. G. Khan, Pakistan. These samples were analyzed by Instrumental Neutron Activation Analysis (INAA) to detect the elemental hazard assessment. Radioassay schemes for three sets of elements after neutron irradiation and cooling were evolved to avoid matrix effects. The composition of MM clay shows major elements in descending order as Fe > K > Mg > Na > Mn > Zn > V > Rb > Cr >Ba followed by minor elements as Sr >Co > Cs with trace levels of Se. Data have been compared with clays available in literature globally. Intakes of essential elements were calculated for pregnant, lactating women and children. Intakes were found comparable to WHO levels except Fe and Cr. Risk assessment was measured using mathematical model. The quality assurance of data was performed using Standard Reference Materials (SRMs) of a similar matrix (IAEA Lake sediment SL-1 and IAEA Soil S-7). (author)

  15. Permeability response of oil-contaminated compacted clays

    International Nuclear Information System (INIS)

    This paper presents the results of a laboratory investigation on the behavior of motor oil-contaminated, partially saturated compacted clays. For the study, both a natural clay and an artificially purified kaolinite, contaminated with 0 to 8% of motor oil, were firstly compacted following the ASTM standard procedure. Secondly, permeability tests were carried out in a triaxial cell on 10 cm-diameter compacted clay specimens. The results of the investigation indicate that increasing percentages of motor oil decrease both the optimum water content and the optimum dry density of the two clays. However, whereas the optimum water content on the average decreases by about 6% when the percentage contamination increases from 0 to 8%, the corresponding decrease in the optimum dry density is less than 3%. Even though the optimum dry density decreases as the percentage of oil increases from 0 to 8%, there is, however, a range in oil content varying between 2 and 4% for which the optimum dry density is slightly greater than that of the untreated soils. As far as the permeability tests are concerned, the results indicate that as the percentage of oil increases, the coefficient of permeability decreases substantially, especially for clay specimens which were initially compacted on the dry side of optimum

  16. Clay Minerals Deposit of Halakabad (Sabzevar- Iran)

    OpenAIRE

    Seyed Mohammad Hashemi

    2012-01-01

    Clay minerals are expanded in south of Sabzevar. They are identified with light color in the filed. The XRD and XRF chemical and mineralogical studies on the Clay minerals indicated that their main clay minerals are Kaolinite, Illite and Dickite. Pyrophyllite is minor clay mineral. Quartz and Sanidine non clay minerals are present with clay minerals .Ratio of Al2O3 is about 40 per cent, it is very good for industrial minerals .Volcanic rocks are origin clay minerals .Their composition are bas...

  17. SBR Brazilian organophilic/clay nanocomposites

    International Nuclear Information System (INIS)

    The aim of this work is the obtaining of SBR composites using a Brazilian raw bentonite and the same bentonite treated with an organic salt. The clays were characterized by XRD. The clay addition in the composites was 10 pcr. The composites were characterized by XRD and had measured theirs tension strength (TS). The composite with Brazilian treated clay showed TS 233% higher than a composite with no clay, 133% higher than a composite with Cloisite 30B organophilic clay and 17% lower than a composite with Cloisite 20 A organophilic clay. XRD and TS data evidence that the composite with Brazilian treated clay is an intercalated nanocomposite. (author)

  18. First Direct Detection of Clay Minerals on Mars

    Science.gov (United States)

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

    1985-01-01

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

  19. Characterisation and engineering properties of Tiller clay

    OpenAIRE

    Gylland, A.; Long, Michael; Emdal, A.; et al.

    2013-01-01

    A detailed characterisation of the quick clay underlying the NTNU research site at Tiller, Trondheim is presented. The objective of the work is to provide guidance on quick clay parameters to engineers and researchers working with similar clays in Scandinavia and North America especially on landslide hazard assessment. The material is lightly overconsolidated and is characterised by its high degree of structure and very high sensitivity (quick clay). Clay and water contents are both about 40%...

  20. Finite Element Investigations on the Interaction between a Pile and Swelling Clay

    OpenAIRE

    Kaufmann, Kristine Lee; Nielsen, Benjaminn Nordahl; Augustesen, Anders Hust

    2010-01-01

    This paper aims to investigate the interaction between a pile and a swelling soil modelled as a cohesive soil subjected to unloading. The investigations include analyses of the heave of the excavation level, shear stresses at the soil–pile interface and internal pile forces based on a case study of Little Belt Clay. The case study involves a circular concrete pile installed in clay immediately after an excavation. The influence of the swelling soil on the soil–pile interaction and the interna...

  1. Geosynthetic clay liners - slope stability field study

    International Nuclear Information System (INIS)

    A field research project was developed to examine the internal shear performance of geosynthetic clay liners (GCLs). Several combinations of cross sections were assembled using GCL materials that were available at the time of project initiation. The cross sections utilized were intended to simulate landfill cover applications. Thirteen (13) resulting test plots were constructed on two different slope angles, and each plot is instrumented for physical displacement and soil moisture characteristics. Test plots were constructed in a manner that dictated the shear plane in the clay portion of the GCL product. The project purpose is to assess field performance and to verify design parameters associated with the application of GCLs in waste containment applications. Interim research data shows that test slopes on 2H:1V show global deformation, but little internal shear evidence, and the 3H:1V slopes show little deformation at approximately 650 days. The research is ongoing, and this paper presents the most recent information available from the project

  2. Geosynthetic clay liners - slope stability field study

    Energy Technology Data Exchange (ETDEWEB)

    Carson, D.A. [Environmental Protection Agency, Cincinnati, OH (United States); Daniel, D.E. [Univ. of Illinois, Urbana, IL (United States); Koerner, R.M. [Geosynthetic Research Institute, Philadelphia, PA (United States); Bonaparte, R. [GeoSyntec Consultants, Atlanta, GA (United States)

    1997-12-31

    A field research project was developed to examine the internal shear performance of geosynthetic clay liners (GCLs). Several combinations of cross sections were assembled using GCL materials that were available at the time of project initiation. The cross sections utilized were intended to simulate landfill cover applications. Thirteen (13) resulting test plots were constructed on two different slope angles, and each plot is instrumented for physical displacement and soil moisture characteristics. Test plots were constructed in a manner that dictated the shear plane in the clay portion of the GCL product. The project purpose is to assess field performance and to verify design parameters associated with the application of GCLs in waste containment applications. Interim research data shows that test slopes on 2H:1V show global deformation, but little internal shear evidence, and the 3H:1V slopes show little deformation at approximately 650 days. The research is ongoing, and this paper presents the most recent information available from the project.

  3. Determination of spatial variability of aluminum according to the clay distribution in soils of Querência do Norte/Paraná State, BrazilDeterminação da variabilidade espacial de alumínio em função da distribuição de argila em solos de Querência do Norte/Paraná, Brasil

    Directory of Open Access Journals (Sweden)

    Marcelo Luiz Chicati

    2011-10-01

    Full Text Available The major part of Brazilian soils shows elevated aluminum contents and in several cases this element occurs in phytotoxic levels. Aluminum is a constituent of the soil´s clay minerals. Its release can occur to the exchangeable fraction or to the soil solution. The objective of this work was to demonstrate the relationship between the spatial variability of aluminum and the distribution of soil clay. In order to achieve that, a grid of soil samples was collected in field, defined by means of photointerpretation and observation of images. The results obtained in laboratory were submitted to statistical analyses to verify spatial dependence, which was proven later. The space continuity was studied by means of the semivariogram’s elaboration using different models. The best semivariograms were chosen by cross validation performed through "ordinary kriging". Thus, it could be observed that these variables showed structure of spatial dependence, with a positive correlation between them, besides it was possible to make maps in order to allow a better agricultural exploitation.A maior parte dos solos brasileiros possui altos teores de alumínio e, em muitos casos, este elemento ocorre em níveis fitotóxicos. Constituinte dos minerais de argila, pode ter sua liberação diretamente na forma trocável ou para a solução do solo. O objetivo deste trabalho foi demonstrar a relação entre a variabilidade espacial do alumínio e a distribuição de argila do solo. Para isto, foi coletada uma malha de amostras de solo em campo, definida por meio de fotointerpretação e observação de imagens. Os resultados obtidos em laboratório foram submetidos a análises estatísticas visando a verificação da dependência espacial, que foi comprovada posteriormente. A continuidade espacial foi estudada mediante a elaboração de semivariogramas utilizando-se diferentes modelos. Os melhores semivariogramas foram escolhidos mediante a validação cruzada executada

  4. Hydrogeology in Clay Tills

    DEFF Research Database (Denmark)

    Kessler, Timo Christian; Klint, Knud Erik; Nilsson, Bertel;

    2012-01-01

    Low-permeability soils such as clayey tills constitute geological boundaries to underlying chalk aquifers that are commonly used as a drinking water resource. Fractures and sand lenses within till sequences represent hydraulic avenues with high hydraulic conductivites limiting the protective...... have on the hydraulic regime within a clayey till aquitard. De fleste steder i Danmark danner moræneler en geologisk grænse til underliggende grundvandsmagasiner, der udgør vigtige drikkevandskilder i den danske vandforsyning. Sprækker og sandlinser i moræneleret resulterer i en øget strømning gennem...

  5. Thermal Behaviour of clay formations

    International Nuclear Information System (INIS)

    The programme carried out by ENEA to model the thermal-hydraulic-mechanical behaviour of the clay formations and to measure, in situ and in laboratory, the thermal properties of these rocks, is presented. An in situ heating experiment has been carried out in an open clay quarry in the area of Monterotondo, near Rome. The main goal of the experiment was to know the temperature field and the thermal effects caused by the high level radioactive waste disposed of in a clayey geological formation. The conclusions are as follows: - the thermal conduction codes are sufficiently accurate to forecast the temperature increases caused in the clay by the dissipation of the heat generated by high level radioactive waste; - the thermal conductivity deduced by means of the ''curve fitting'' method ranges from 0.015 to 0.017 W.cm-1.0C-1 - the temperature variation associated with the transport of clay interstitial water caused by temperature gradient is negligible. A laboratory automated method has been designed to measure the thermal conductivity and diffusivity in clay samples. A review of experimental data concerning thermomechanical effects in rocks as well as results of thermal experiments performed at ISMES on clays are presented. Negative thermal dilation has been found both in the elastic and plastic range under constant stress. Thermoplastic deformation appears ten times greater than the thermoelastic one. A mathematical model is proposed in order to simulate the above and other effects that encompass thermal-elastic-plastic-pore water pressure response of clays at high temperature and effective pressure with undrained and transient drainage conditions. Implementation of the two versions into a finite element computer code is described

  6. Vulnerability of shallow ground water and drinking-water wells to nitrate in the United States: Model of predicted nitrate concentration in shallow, recently recharged ground water -- Input data set for clay sediment (gwava-s_clay)

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This data set represents the amount of clay sediment in the soil, in percent times 1000, in the conterminous United States. The data set was used as an input data...

  7. On the decay of strength in Guilin red clay with cracks

    Directory of Open Access Journals (Sweden)

    Yi Li

    2015-10-01

    Full Text Available In order to research the effect of cracks in red clay on shear strength through dry-wet cycle test, the experimenters used imaging software and a mathematical model to determine fractal dimension and crack ratio of surface cracks in red clay in Guilin, China. After each dry-wet cycle, direct shear tests were carried out on the sample, and such variables as matrix suction on the crack propagation process of red clay were analyzed. The mechanics model was established and obtained the critical condition of soil cracks. The results show that with the increase in the number of dry-wet cycles the shear strength of the samples would decrease. But the rule of shear strength of sample 3 is slightly different from samples 1 and 2. The shear strength of red clay has a good correlation with fractal dimension and crack ratio, which could be an identification index of the strength of red clay

  8. Evaluation of the Efficiency of Clay Pots in Removal of Water Impurities

    Directory of Open Access Journals (Sweden)

    K Naddafi , AH Mahvi, S Nasseri, M Mokhtari, H Zeraati

    2005-04-01

    Full Text Available Recently, inexpensive technologies for drinking water supply in small communities are highly considered in developing countries. One of these technologies is the application of ceramic filters that are usually made of diatomaceous earth or clay soil. This research was carried out to determine the efficiency of clay pots (as a filter in removing water impurities. Pilot and the related clay parts were manufactured and its efficiency in removing TDS, hardness, NO3-, color and turbidity was measured by passing water through the clay pipes. The results showed that the clay filters had not the potential to remove hardness, EC, TDS and nitrate of water. However, they showed excellent efficiency in turbidity removal (≥ 90% and could significantly decrease the color of the water (≥ 60%.

  9. Performance of asphalt and clay liners as a uranium mill tailings leachate barrier

    International Nuclear Information System (INIS)

    Pacific Northwest Laboratory is evaluating the long-term effectiveness of various asphalt and clay liner materials as a radionuclide and process chemical barrier from uranium mill tailings. A field test is being conducted by monitoring asphalt and clay liners installed at the Grand Junction, Colorado tailings site. In addition eight prospective liners have undergone three months exposure to accelerated conditions to predict their behavior over a 1000 year period. High calcium leachates have been forced through thin layers of clay to determine the ability of the clay to resist ion exchange, which reduces its swelling capabilities. Asphalt liners have been exposed to elevated temperatures and increased strengths of oxidizing agents to accelerate their aging process. The permeability coefficients measured during this exposure were then used to predict each liners stability with time. The analyses thus far show that clay soils with bentonite amendments and most asphalt compositions have good long-term performance characteristics. 3 figures, 1 table

  10. Performance of asphalt and clay liners as a uranium mill tailings leachate barrier

    International Nuclear Information System (INIS)

    Pacific Northwest Laboratory is evaluating the long-term effectiveness of various asphalt clay liner materials as a radionuclide and process chemical barrier from uranium mill tailings. A field test is being conducted by monitoring asphalt and clay liners installed at the Grand Junction, Colorado tailings site. In addition, eight prospective liners have undergone three months exposure to accelerated conditions to predict their behavior over a 1000-year period. High-calcium leachates have been forced through thin layers of clay to determine the ability of the clay to resist ion exchange, which reduces its swelling capabilities. Asphalt liners have been exposed to elevated temperatures and increased strengths of oxidizing agents to accelerate their aging process. The permeability coefficients measured during this exposure were then used to predict each liners stability with time. The analyses thus far show that clay soils with bentonite amendments and most asphalt compositions have good long-term performance characteristics

  11. The soil reference shrinkage curve

    CERN Document Server

    Chertkov, V Y

    2014-01-01

    A recently proposed model showed how a clay shrinkage curve is transformed to the soil shrinkage curve at the soil clay content higher than a critical one. The objective of the present work was to generalize this model to the soil clay content lower a critical one. I investigated (i) the reference shrinkage curve, that is, one without cracks; (ii) the superficial layer of aggregates, with changed pore structure compared with the intraaggregate matrix; and (iii) soils with sufficiently low clay content where there are large pores inside the intraaggregate clay (so-called lacunar pores). The methodology is based on detail accounting for different contributions to the soil volume and water content during shrinkage. The key point is the calculation of the lacunar pore volume variance at shrinkage. The reference shrinkage curve is determined by eight physical soil parameters: (1) oven-dried specific volume; (2) maximum swelling water content; (3) mean solid density; (4) soil clay content; (5) oven-dried structural...

  12. The Determination Of Scaling Factor of Clay Properties

    Directory of Open Access Journals (Sweden)

    Agus Sulaeman

    2015-05-01

    Full Text Available The observations and tests under small scale in 1-gravity condition is intended to obtain a comparative behavior of model and prototype of geotechnical case by imposing the scaling relations. Simulation to represent related structure, sub-soil and failure mechanism need to be prepared prior to do observations in this modelling. To obtain the new parameter for sub-soil simulation and inter-dependency with scaling relationship, the  ten samples with different water content of prototype clay soil were consolidated in the triaxial CU test.  After consolidation, each sample were given the arbitrarily initial mean stress po =1/3 (σ1+σ2+σ3 at the same time each corresponding void ratio were recorded. The data was plotted and numbered in the e Ln p’ axises to adopt critical state line concept. Further shear stage in triaxial CU test were done to record the stress and strain of each ten samples. Among those of ten stress strain curves there were 3 similar curves (1, 6 and 8 observed when the deviatoric stress was normalized with its po, this showed similar behavior among them. The further observation revealed that void ratio in the clay soil no. 8 (ep corresponded with void ratio of the sample no. 1 (em, stress ratio N and critical state line parameter l in the form of  em= ep+ l Ln N. To support the expression of  em= ep+ l Ln N,  The “pile loading test” case was prepared in small scale and full scale modeling, em   represented void ratio of clay in small scale and ep represented void ratio of clay at original project location. Load settlement curves were obtained from both “pile loading test” in small and full scale simulation and the result showed closely good agreement.

  13. Clay with Desiccation Cracks is an Advection Dominated Environment

    Science.gov (United States)

    Baram, S.; Kurtzman, D.; Sher, Y.; Ronen, Z.; Dahan, O.

    2012-04-01

    Heavy clay sediments are regarded "safe" from the hydrological point of view due to their low hydraulic conductivities. However, the formation of desiccation cracks in dispersive clays may dramatically change their bulk hydraulic properties. The impact of desiccation cracks on water percolation, dissolved salts and contaminants transport and redox related reactions (microbial ammonium oxidation and denitrification) were investigated in 6 -12 m clay layer near a diary farm waste lagoon. The study implemented unique vadose-zone monitoring systems that enable in-situ measurements of the temporal variation of the sediment's water content along with frequent sampling of the sediment's pore water along the entire vadose zone (> 30 m). Results from four years of continuous measurements showed quick rises in sediment water content following rain events and temporal wastewater overflows. The percolation pattern indicated dominance of preferential flow through a desiccation-cracks network crossing the entire clay sediment layer. High water-propagation velocities (0.4 - 23.6 m h-1) were observed, indicating that the desiccation-crack network remains open and serves as a preferential flow pathway year-round, even at high sediment water content (~0.50 m3 m-3). The rapid percolation bypassed the most bio-geo-active parts of the soil, transporting even highly sorptive contaminants (testosterone and estrogen) in to the deep sections of the vadose zone, accelerating the underlying groundwater contamination. The ammonium and nitrate concentrations in the vadose zone and the high number of nitrifying and denitrifying bacteria (~108 gene copies gdry-sediemt-1, each) found in the sediment indicated that the entire vadose zone is aerated even at high water content conditions (~0.55 m3 m-3). The dissolved salts concentration in the pore-water and the δ2H-H2O and δ18O-H2O values of the pore-water substantially increased with depth (becoming less depleted) in the clay sediment

  14. Three Soil Quality Demonstrations for Educating Extension Clientele

    Science.gov (United States)

    Hoorman, James J.

    2014-01-01

    There is a renewed interest in educating youth, Master Gardeners, and agricultural producers about soil quality. Three soil demonstrations show how soil organic matter increases water holding capacity, improves soil structure, and increases nutrient retention. Exercise one uses clay bricks and sponges to represent mineral soils and soil organic…

  15. Dynamics of clay mineralogy with profile depth in relation to long term potassium fertilizer application to sugar cane crop

    International Nuclear Information System (INIS)

    The experiment consisted of treatment of sugar cane crop with N, NP, NPK and farmyard manure and determination of its effect on soil mica, vermiculite and montmorillonite over a period of 18 years. The NPK treatment had greater mica in coarse clay, but less in fine clay than NP and control treatments. Vermiculite in coarse clay fraction, in NPK treatment, increased with the depth as compared to other treatments. The fertilizer treatment effect on smectite content was obvious only in AP horizon in fine clay fraction. (author)

  16. Prediction of Soil Moisture Content and Soil Salt Concentration from Hyperspectral Laboratory and Field Data

    OpenAIRE

    Chi Xu; Wenzhi Zeng; Jiesheng Huang; Jingwei Wu; Willem J. D. van Leeuwen

    2016-01-01

    This research examines the simultaneous retrieval of surface soil moisture and salt concentrations using hyperspectral reflectance data in an arid environment. We conducted laboratory and outdoor field experiments in which we examined three key soil variables: soil moisture, salt and texture (silty loam, clay and silty clay). The soil moisture content models for multiple textures (M_SMC models) were based on selected hyperspectral reflectance data located around 1460, 1900 and 2010 nm and res...

  17. Retention of radiocaesium traces in clay: a dynamic semi-empirical modelling

    International Nuclear Information System (INIS)

    The contribution consists of an abstract of a PhD thesis. After deposition, Cs+bioavailability in soil is a key parameter with regard to public exposure after a severe nuclear accident.The objective of the PhD thesis was to understand and model the interaction of Cs+ and 2:1 clay minerals. This interaction was characterised through Cs+ sorption-desorption experiments carried out on seven 2:1 clay minerals (four smectite types, illite, biotite and vermiculite)

  18. Electrokinetic-enhanced bioaugmentation for remediation of chlorinated solvents contaminated clay

    Energy Technology Data Exchange (ETDEWEB)

    Mao, Xuhui, E-mail: x.mao@neu.edu [Civil and Environmental Engineering Department, Northeastern University, Boston, MA 02115 (United States); School of Resources and Environmental Science, Wuhan University, Wuhan 430079 (China); Wang, James [Geosyntec Consultants, Columbia, MA (United States); Ciblak, Ali [Civil and Environmental Engineering Department, Northeastern University, Boston, MA 02115 (United States); Cox, Evan E. [Geosyntec Consultants, Columbia, MA (United States); Riis, Charlotte [NIRAS A/S, Alleroed (Denmark); Terkelsen, Mads [Capital Region of Denmark, Hilleroed (Denmark); Gent, David B. [Environmental Laboratory, Engineer Research and Development Center (ERDC), US Army Corps of Engineers, Vicksburg, MS (United States); Alshawabkeh, Akram N., E-mail: aalsha@neu.edu [Civil and Environmental Engineering Department, Northeastern University, Boston, MA 02115 (United States)

    2012-04-30

    Highlights: Black-Right-Pointing-Pointer Simultaneous delivery of electron donors and bacteria into low permeability clays. Black-Right-Pointing-Pointer Bacteria injection, growth and consequent transformation of contaminants are viable. Black-Right-Pointing-Pointer EK injection is more effective than advection-based injection for clay soil. Black-Right-Pointing-Pointer Electroosmosis appears to be the driving mechanism for bacteria injection. Black-Right-Pointing-Pointer Both EK transport and biodegradation contribute the removal of VOCs in clay. - Abstract: Successful bioremediation of contaminated soils is controlled by the ability to deliver bioremediation additives, such as bacteria and/or nutrients, to the contaminated zone. Because hydraulic advection is not practical for delivery in clays, electrokinetic (EK) injection is an alternative for efficient and uniform delivery of bioremediation additive into low-permeability soil and heterogeneous deposits. EK-enhanced bioaugmentation for remediation of clays contaminated with chlorinated solvents is evaluated. Dehalococcoides (Dhc) bacterial strain and lactate ions are uniformly injected in contaminated clay and complete dechlorination of chlorinated ethene is observed in laboratory experiments. The injected bacteria can survive, grow, and promote effective dechlorination under EK conditions and after EK application. The distribution of Dhc within the clay suggests that electrokinetic transport of Dhc is primarily driven by electroosmosis. In addition to biodegradation due to bioaugmentation of Dhc, an EK-driven transport of chlorinated ethenes is observed in the clay, which accelerates cleanup of chlorinated ethenes from the anode side. Compared with conventional advection-based delivery, EK injection is significantly more effective for establishing microbial reductive dechlorination capacity in low-permeability soils.

  19. Gas migration through bentonite clay

    International Nuclear Information System (INIS)

    Hydrogen gas produced by irradiation of pore water in the highly compacted bentonite that surrounds the copper canisters according to the KBS 2 and 3 concepts, may escape from the clay/copper interface if the gas pressure is higher than the groundwater pressure. A reasonable physical model predicts that gas may penetrate wider capillary passages that actually exist in the very dense clay, although these passages are still of microscopic size. In the large majority of the clay voids, the capillary action is sufficient, however, to resist gas penetration, and this suggests that a possible mechanism of gas migration is that of a finger-like pattern of tortuous gas passages extending from the canisters if radiolysis takes place at all. Two series of experiments have been run at gas pressures up to about 10 MPa. Nitrogen as well as hydrogen were used in these tests which seem to confirm, in principle, the validity of the physical model. (authors)

  20. Survival of microorganisms in smectite clays - Implications for Martian exobiology

    Science.gov (United States)

    Moll, Deborah M.; Vestal, J. R.

    1992-01-01

    The survival of Baccillus subtilis, Azotobacter chroococcum, and the enteric bacteriophage MS2 has been examined in clays representing terrestrial (Wyoming type montmorillonite) and Martian (Fe3+ montmorillonite) soils exposed to terrestrial and Martian environmental conditions of temperature and atmospheric composition and pressure. An important finding is that MS2 survived simulated Mars conditions better than the terrestrial environment, probably owing to stabilization of the virus caused by the cold and dry conditions of the simulated Mars environment. This finding, the first published indication that viruses may be able to survive in Mars-type soils, may have important implications for future missions to Mars.

  1. Boron enrichment in martian clay.

    Directory of Open Access Journals (Sweden)

    James D Stephenson

    Full Text Available We have detected a concentration of boron in martian clay far in excess of that in any previously reported extra-terrestrial object. This enrichment indicates that the chemistry necessary for the formation of ribose, a key component of RNA, could have existed on Mars since the formation of early clay deposits, contemporary to the emergence of life on Earth. Given the greater similarity of Earth and Mars early in their geological history, and the extensive disruption of Earth's earliest mineralogy by plate tectonics, we suggest that the conditions for prebiotic ribose synthesis may be better understood by further Mars exploration.

  2. Boron enrichment in martian clay.

    Science.gov (United States)

    Stephenson, James D; Hallis, Lydia J; Nagashima, Kazuhide; Freeland, Stephen J

    2013-01-01

    We have detected a concentration of boron in martian clay far in excess of that in any previously reported extra-terrestrial object. This enrichment indicates that the chemistry necessary for the formation of ribose, a key component of RNA, could have existed on Mars since the formation of early clay deposits, contemporary to the emergence of life on Earth. Given the greater similarity of Earth and Mars early in their geological history, and the extensive disruption of Earth's earliest mineralogy by plate tectonics, we suggest that the conditions for prebiotic ribose synthesis may be better understood by further Mars exploration. PMID:23762242

  3. Thermo-mechanical constitutive modeling of unsaturated clays based on the critical state concepts

    Institute of Scientific and Technical Information of China (English)

    Saeed Tourchi; Amir Hamidi

    2015-01-01

    A thermo-mechanical constitutive model for unsaturated clays is constructed based on the existing model for saturated clays originally proposed by the authors. The saturated clays model was formulated in the framework of critical state soil mechanics and modified Cam-clay model. The existing model has been generalized to simulate the experimentally observed behavior of unsaturated clays by introducing Bishop’s stress and suction as independent stress parameters and modifying the hardening rule and yield criterion to take into account the role of suction. Also, according to previous studies, an increase in temperature causes a reduction in specific volume. A reduction in suction (wetting) for a given confining stress may induce an irreversible volumetric compression (collapse). Thus an increase in suction (drying) raises a specific volume i.e. the movement of normal consolidation line (NCL) to higher values of void ratio. However, some experimental data confirm the assumption that this reduction is dependent on the stress level of soil element. A generalized approach considering the effect of stress level on the magnitude of clays thermal dependency in compression plane is proposed in this study. The number of modeling parameters is kept to a minimum, and they all have clear physical interpretations, to facilitate the usefulness of model for practical applications. A step-by-step procedure used for parameter cali-bration is also described. The model is finally evaluated using a comprehensive set of experimental data for the thermo-mechanical behavior of unsaturated soils.

  4. Thermo-mechanical constitutive modeling of unsaturated clays based on the critical state concepts

    Directory of Open Access Journals (Sweden)

    Saeed Tourchi

    2015-04-01

    Full Text Available A thermo-mechanical constitutive model for unsaturated clays is constructed based on the existing model for saturated clays originally proposed by the authors. The saturated clays model was formulated in the framework of critical state soil mechanics and modified Cam-clay model. The existing model has been generalized to simulate the experimentally observed behavior of unsaturated clays by introducing Bishop's stress and suction as independent stress parameters and modifying the hardening rule and yield criterion to take into account the role of suction. Also, according to previous studies, an increase in temperature causes a reduction in specific volume. A reduction in suction (wetting for a given confining stress may induce an irreversible volumetric compression (collapse. Thus an increase in suction (drying raises a specific volume i.e. the movement of normal consolidation line (NCL to higher values of void ratio. However, some experimental data confirm the assumption that this reduction is dependent on the stress level of soil element. A generalized approach considering the effect of stress level on the magnitude of clays thermal dependency in compression plane is proposed in this study. The number of modeling parameters is kept to a minimum, and they all have clear physical interpretations, to facilitate the usefulness of model for practical applications. A step-by-step procedure used for parameter calibration is also described. The model is finally evaluated using a comprehensive set of experimental data for the thermo-mechanical behavior of unsaturated soils.

  5. Role of clay microstructure in expandable buffer clay

    Czech Academy of Sciences Publication Activity Database

    Pusch, R.; Přikryl, R.; Weishauptová, Zuzana; Xiaodong, L.; Knutsson, S.

    2012-01-01

    Roč. 1, č. 6 (2012), s. 267-292. ISSN 2232-1179 R&D Projects: GA ČR GA205/08/0676 Institutional research plan: CEZ:AV0Z30460519 Keywords : cementation * expandable clay * hydraulic conductivity Subject RIV: DL - Nuclear Waste, Radioactive Pollution ; Quality http://pure.ltu.se/portal/files/39920921/332.pdf

  6. Correlation Between Soil Water Retention Capability and Soil Salt Content

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The soil moisture retention capability of Chao soil and coastal saline Chao soil in Shandong and Zhejiang provinces were measured by pressure membrane method. The main factors influencing soil moisture retention capability were studied by the methods of correlation and path analyses. The results indicated that < 0.02mm physical clay and soil salt content were the main factors influencing soil moisture retention capability. At soil suction of 30~50 kPa, the soil salt content would be the dominant factor.

  7. Testosterone sorption and desorption: Effects of soil particle size

    Energy Technology Data Exchange (ETDEWEB)

    Qi, Yong, E-mail: yqi01@unomaha.edu [Civil Engineering Dept., University of Nebraska-Lincoln at Omaha Campus, Omaha, NE 68182 (United States); Zhang, Tian C. [Civil Engineering Dept., University of Nebraska-Lincoln at Omaha Campus, Omaha, NE 68182 (United States); Ren, Yongzheng [School of Environmental Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074 (China)

    2014-08-30

    Graphical abstract: - Highlights: • Smaller soil particles have higher sorption and lower desorption rates. • The sorption capacity ranks as clay > silt > sand. • Small particles like clays have less potential for desorption. • Colloids (clays) have high potential to facilitate the transport of hormones in soil–water environments. - Abstract: Soils contain a wide range of particles of different diameters with different mobility during rainfall events. Effects of soil particles on sorption and desorption behaviors of steroid hormones have not been investigated. In this study, wet sieve washing and repeated sedimentation methods were used to fractionate the soils into five ranges. The sorption and desorption properties and related mechanisms of testosterone in batch reactors filled with fractionated soil particles were evaluated. Results of sorption and desorption kinetics indicate that small soil particles have higher sorption and lower desorption rates than that of big ones. Thermodynamic results show the sorption processes are spontaneous and exothermal. The sorption capacity ranks as clay > silt > sand, depending mainly on specific surface area and surface functional groups. The urea control test shows that hydrogen bonding contributes to testosterone sorption onto clay and silt but not on sand. Desorption tests indicate sorption is 36–65% irreversible from clay to sand. Clays have highest desorption hysteresis among these five soil fractions, indicating small particles like clays have less potential for desorption. The results provide indirect evidence on the colloid (clay)-facilitated transport of hormones (micro-pollutants) in soil environments.

  8. Spatial and temporal variability of soil electrical conductivity related to soil moisture

    Directory of Open Access Journals (Sweden)

    José Paulo Molin

    2013-02-01

    Full Text Available Soil electrical conductivity (ECa is a soil quality indicator associated to attributes interesting to site-specific soil management such as soil moisture and texture. Soil ECa provides information that helps guide soil management decisions, so we performed spatial evaluation of soil moisture in two experimental fields in two consecutive years and modeled its influence on soil ECa. Soil ECa, moisture and clay content were evaluated by statistical, geostatistical and regression analyses. Semivariogram models, adjusted for soil moisture, had strong spatial dependence, but the relationship between soil moisture and soil ECa was obtained only in one of the experimental fields, where soil moisture and clay content range was higher. In this same field, coefficients of determinations between soil moisture and clay content were above 0.70. In the second field, the low soil moisture and clay content range explain the absence of a relationship between soil ECa and soil moisture. Data repetition over the years, suggested that ECa is a qualitative indicator in areas with high spatial variability in soil texture.

  9. Magnetic resonance imaging of clays: swelling, sedimentation, dissolution

    Science.gov (United States)

    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

  10. Mineral Composition of Clay Fraction of the Chernozems Spread out in Ovče Pole in Republic of Macedonia

    Directory of Open Access Journals (Sweden)

    Mile Markoski

    2011-03-01

    Full Text Available The results of mineral composition of the clay fraction of the chernozems spread out in Ovče Pole are presented. The mechanical composition of the soil samples show high domination of the physical clay and clay fractions in the soil separates, what is one of the reasons for strong influence on the physical and physical-mechanical properties of the soil. The clay content is dominant in the soil separates fraction and varies from 23.60% to 56.90%, or 36.23% average. The average content of physical sand and physical clay fractions is 42.20% and 57.80% respectively. Analysis of the mineral composition of clay in its entirety showed that no one of the minerals in the analyzed chernozem samples is not in absolute domination, but there is evident higher presence of clay minerals with 2:1 lattice type (vermiculite, illite and smectites in comparison with 1:1 lattice type (kaolinite. This shows that our variety of vertical chernozems has little deteriorated physical and physical-mechanical properties compared with typical chernozems.

  11. Transport and biodegradation of NAPLs at subsurface sand/clay interfaces

    International Nuclear Information System (INIS)

    Throughout the United States, petroleum hydrocarbon contamination of soil is a severe problem. Storage tanks are quite often the source, whereby hydrocarbons are released on or near the ground surface and are free to migrate through the soil to the groundwater. Sometimes, such chemicals accumulate at interface of different soil types. Hexadecane transport and degradation in soil reactors were studied in a series of experiments. Three reactors, consisting of soil in sand-clay-sand layers, were contaminated at single points in the center of the top sand layer just below the surface. One reactor was used as a control while the other two were equipped with influent and effluent water ports located above the sand/clay interface. The ports were utilized to add water to the soil. One reactor was supplied with water only and the other was injected with a phosphorus/nitrogen solution to enhance degradation. The project focused on two aspects: (1) the transport of the NAPLs at an abrupt sand/clay interface and (2) the ability of the soil microbes to degrade the hexadecane under aerobic conditions. Gas chromatography analysis of the effluent water samples indicate no significant removal of the NAPL from the soil by pumping, while mass balances indicate NAPL degradation due to microbial action. In addition, gas chromatography data of soil samples trace the movement of the chemical throughout the three reactors

  12. Biodegradable Pectin/clay Aerogels

    Science.gov (United States)

    Biodegradable, foamlike materials based on renewable pectin and sodium montmorillonite clay were fabricated through a simple, environmentally friendly freeze-drying process. Addition of multivalent cations (Ca2+ and Al3+) resulted in apparent crosslinking of the polymer, and enhancement of aerogel p...

  13. Geotechnical properties of Karwar marine clay

    Digital Repository Service at National Institute of Oceanography (India)

    Bhat, S.T.; Nayak, B.U.; Naik, R.L.

    Karwar marine clay possesses high plasticity characteristics with natural water content higher than the liquid limit. Liquidity index was as high as 1.7. Predominant clay mineral was kaolinite. Undrained shear strength showed an increasing trend...

  14. 21 CFR 186.1256 - Clay (kaolin).

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Clay (kaolin). 186.1256 Section 186.1256 Food and... Substances Affirmed as GRAS § 186.1256 Clay (kaolin). (a) Clay (kaolin) Al2O3.2SiO2.nH2O, Cas Reg. No. 1332-58-7) consists of hydrated aluminum silicate. The commercial products of clay (kaolin)...

  15. Sorption of Cesium on Latvia clays

    International Nuclear Information System (INIS)

    Cesium is like potassium - good solubility and mobile in a ground, easy assimilates in organism expressly brawn woof. It is a problem if pollutant is radioactive 137Cs. We made experiments to sorption a 2M CsF solution on some Latvian clays which mainly contain hydro micas. We establish that clay treated with 25% sulfuric acid absorb cesium two times more that waste clay. Hereto unstuck elute Cs from clays

  16. Resposta à aplicação e recuperação de enxofre em cultivos de casa de vegetação em solos com diferentes teores de argila e matéria orgânica Responses to sulfur application and recuperation in greenhouse crops in soils with different clay and organic matter content

    Directory of Open Access Journals (Sweden)

    Danilo dos Santos Rheinheimer

    2007-04-01

    after each crop and analyzed for S-SO4-2. It was evaluate the dry matter production and S-SO4-2 absorbed by plants. Only canola responded to sulphur application. Soybean, black bean, sesame, clover and wheat did not response to sulfur application. There was not observed correlation between soil S-SO4-2 available in 10cm topsoil and crop yields. Soils with different clay and organic matter content showed similar behavior of crop response to sulfur application. The increase of S-SO4-2 availability with fertilization was greater in soils with more clay content.

  17. Nitrate Adsorption on Clay Kaolin: Batch Tests

    Directory of Open Access Journals (Sweden)

    Morteza Mohsenipour

    2015-01-01

    Full Text Available Soils possessing kaolin, gibbsite, goethite, and hematite particles have been found to have a natural capacity to attenuate pollution in aqueous phase. On the other hand, the hydroxyl group in soil increases anion exchange capacity under a low pH condition. The main objective of this paper was to evaluate effects of kaolin on nitrate reduction under acidic condition. In order to analyze the kaolin adsorption behaviour under various conditions, four different concentrations of nitrate, 45, 112.5, 225, and 450 mgNO3-/L, with a constant pH equal to 2, constant temperature equal to 25°C, and exposure period varying from 0 to 150 minutes were considered. The capacity of nitrate adsorption on kaolin has also been studied involving two well-known adsorption isotherm models, namely, Freundlich and Longmuir. The results revealed that approximately 25% of the nitrate present in the solution was adsorbed on clay kaolin. The laboratory experimental data revealed that Freundlich adsorption isotherm model was more accurate than Longmuir adsorption model in predicting of nitrate adsorption. Furthermore, the retardation factor of nitrate pollution in saturated zone has been found to be approximately 4 in presence of kaolin, which indicated that kaolin can be used for natural scavenger of pollution in the environment.

  18. Application of short-wave infrared (SWIR) spectroscopy in quantitative estimation of clay mineral contents

    International Nuclear Information System (INIS)

    Clay minerals are significant constituents of soil which are necessary for life. This paper studied three types of clay minerals, kaolinite, illite, and montmorillonite, for they are not only the most common soil forming materials, but also important indicators of soil expansion and shrinkage potential. These clay minerals showed diagnostic absorption bands resulting from vibrations of hydroxyl groups and structural water molecules in the SWIR wavelength region. The short-wave infrared reflectance spectra of the soil was obtained from a Portable Near Infrared Spectrometer (PNIS, spectrum range: 1300∼2500 nm, interval: 2 nm). Due to the simplicity, quickness, and the non-destructiveness analysis, SWIR spectroscopy has been widely used in geological prospecting, chemical engineering and many other fields. The aim of this study was to use multiple linear regression (MLR) and partial least squares (PLS) regression to establish the optimizing quantitative estimation models of the kaolinite, illite and montmorillonite contents from soil reflectance spectra. Here, the soil reflectance spectra mainly refers to the spectral reflectivity of soil (SRS) corresponding to the absorption-band position (AP) of kaolinite, illite, and montmorillonite representative spectra from USGS spectral library, the SRS corresponding to the AP of soil spectral and soil overall spectrum reflectance values. The optimal estimation models of three kinds of clay mineral contents showed that the retrieval accuracy was satisfactory (Kaolinite content: a Root Mean Square Error of Calibration (RMSEC) of 1.671 with a coefficient of determination (R2) of 0.791; Illite content: a RMSEC of 1.126 with a R2 of 0.616; Montmorillonite content: a RMSEC of 1.814 with a R2 of 0.707). Thus, the reflectance spectra of soil obtained form PNIS could be used for quantitative estimation of kaolinite, illite and montmorillonite contents in soil

  19. GEOSYNTHETIC CLAY LINERS (GCLS) IN LANDFILL COVERS

    Science.gov (United States)

    Low permeability, compacted clay linters are commonly required as a barrier to water infiltration in landfill covers. elatively new material, known as geosynthetic clay liner (GCL), has been proposed as an alternative to a compacted clay liner. CL has the practical advantages of ...

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

    Science.gov (United States)

    Ng, C W W; Chen, Z K; Coo, J L; Chen, R; Zhou, C

    2015-10-01

    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 pressure 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 0.6m or thicker

  1. Engineered clay-shredded tyre mixtures as barrier materials

    Energy Technology Data Exchange (ETDEWEB)

    Al-Tabbaa, A.; Aravinthan, T. [Univ. of Birmingham (United Kingdom)

    1997-12-31

    An engineered clay consisting of kaolin and bentonite was mixed with shredded tyre in various weight percentages and examined for use as a constituent in a landfill liner. The clay-tyre mixtures properties in terms of compaction, unconfined compressive strength, permeability to water and paraffin, leachability, stress-strain behaviour, free swell behaviour and swelling pressure were investigated. The results show that the dry density and strength reduced with the addition of tyre and also with increased tyre content but that good interaction was developed between the clay and tyre. The strain at failure increased showing reinforcing effect of the tyre. The permeability to paraffin was considerably reduced compared to that to water due to the presence of the tyre which caused high swelling pressures to develop. The leachability results indicate initial high concentrations leaching out of the soil-tyre mixtures which will be subjected to dilution in the environment. This work adds evidence to the potential advantages of using soil-tyre mixtures as a landfill liner material.

  2. Diffusion and adsorption of benzene in Regina clay

    International Nuclear Information System (INIS)

    Surface or near-surface spills of hydrocarbons such as gasoline and diesel often occur in clay soils which are fractured and unsaturated. For cost-effective remediation, the extent of contamination and the distribution of the various phases should be determined before the development of remediation methods. The four volatile compounds that are commonly associated with gasoline leaking from underground fuel storage tanks are benzene, toluene, ethlybenzene and xylene. Existing diffusion test methods have been used successfully for inorganic species, but the successful application of these methods to volatile organic compounds is limited. The main difficulty with experiments using volatile organics is that there is a need for careful sample handling and sensitive analytical methods to accurately measure the aqueous concentration. Work was carried out to develop an apparatus that could be used to measure the diffusion and adsorption of volatile organics in clay. The best visual fit to the experimental data for the single reservoir test was an effective diffusion coefficient of 0.01 mL/g, and an adsorption coefficient of 0.1 mL/g. Based on diffusion cell tests, there are relatively low levels of retardation for benzene as it moves in clay soils with low organic carbon content. The implications for remediation are summarized. 28 refs., 16 figs., 5 tabs

  3. Engineered clay-shredded tyre mixtures as barrier materials

    International Nuclear Information System (INIS)

    An engineered clay consisting of kaolin and bentonite was mixed with shredded tyre in various weight percentages and examined for use as a constituent in a landfill liner. The clay-tyre mixtures properties in terms of compaction, unconfined compressive strength, permeability to water and paraffin, leachability, stress-strain behaviour, free swell behaviour and swelling pressure were investigated. The results show that the dry density and strength reduced with the addition of tyre and also with increased tyre content but that good interaction was developed between the clay and tyre. The strain at failure increased showing reinforcing effect of the tyre. The permeability to paraffin was considerably reduced compared to that to water due to the presence of the tyre which caused high swelling pressures to develop. The leachability results indicate initial high concentrations leaching out of the soil-tyre mixtures which will be subjected to dilution in the environment. This work adds evidence to the potential advantages of using soil-tyre mixtures as a landfill liner material

  4. The effect of soil type on the bioremediation of petroleum contaminated soils.

    Science.gov (United States)

    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. PMID:27233045

  5. Finite Element Investigations on the Interaction between a Pile and Swelling Clay

    DEFF Research Database (Denmark)

    Kaufmann, Kristine Lee; Nielsen, Benjaminn Nordahl; Augustesen, Anders Hust

    This paper aims to investigate the interaction between a pile and a swelling soil modelled as a cohesive soil subjected to unloading. The investigations include analyses of the heave of the excavation level, shear stresses at the soil–pile interface and internal pile forces based on a case study of...... Little Belt Clay. The case study involves a circular concrete pile installed in clay immediately after an excavation. The influence of the swelling soil on the soil–pile interaction and the internal pile forces are analysed by solely observing the upper pile part positioned in the swelling zone. For the...... surrounding soil implies upward shear stresses at the soil–pile interface leading to tensile vertical stresses in the pile. In the current case, they exceed the tensile strength of concrete. The tensile vertical stresses peak after 35-50 years. However, the heave of the soil continues for additional 300 years...

  6. Study of adsorption of Phenanthrene on Different Types of Clay Minerals; Estudio de Adsorcion de Fenentreno en Diferentes Tipos de Arcillas

    Energy Technology Data Exchange (ETDEWEB)

    Contreras, M. L.; Escolano, O.; Rodriguez, V.; Diaz, F. J.; Perez, R.; Garcia, S.; Garcia Frutos, F. J.

    2003-07-01

    The fate and behaviour of non-ionic hydrophobic organic compounds in deep soil is mainly controlled by the mineral fraction present in the soil due to the very low organic carbon content of the deep soil. The mineral fraction that may greatly influence the fate and transport of these compounds due to its presence and properties are the clay minerals. Clay mineral also become increasingly important in low organic matter content soils. There tree, studies of non-ionic hydrophobic organic compounds adsorption on clay minerals without organic matter are necessary lo better understand the fate and transport of these compounds. In this work we used phenanthrene as model compound of non-ionic hydrophobic organic compound and four pure clay minerals: kaolinite, illite, montmorillonite, and vermiculite including muscovite mica. These clays minerals are selected due to its abundance in represent ve Spanish soils and different properties as its structural layers and expanding capacity. Batch experiments were performed using phenanthrene aqueous solutions and the clays selected. Phenanthrene sorption isotherms for all clays, except muscovite mica, were best described by the Freundlich model. Physical sorption on the external surfaces is the most probable adsorption mechanisms. In this sense, the presence of non-polar nano-sites on clay surfaces could determine the adsorption of phenanthrene by hydrophobic interaction on these sites. (Author) 22 refs.

  7. Effects of Paper-Mill Sludge as a Mulch versus Topsoil Incorporation on Potassium Uptake and the Grain Yield of Rain-Fed Wheat in a High Specific Surface Loess Soil with Illite Dominance in Clay Fraction

    OpenAIRE

    S Amini; Movahedi Naeini, S. A. R.; Mashayekhi, K.

    2012-01-01

    A field experiment with rain-fed winter wheat investigated the nutritional aspects of paper-mill sludge as a mulch and incorporated into the topsoil. Treatments with chemical fertilizers were also used as controls. Paper-mill sludge used as mulch with high rate (100 MG ha−1) and also the combined N and K mineral fertilizer treatments increased yield when a low potassium otherwise caused potassium deficiency in wheat with high specific surface soil. High soil Ca : K molar ratio by incorporatio...

  8. Shrinkage limit of soil mixtures

    International Nuclear Information System (INIS)

    Shrinkage limit, one of the Atterberg limits, is widely linked with many plasticity-based soil behaviors. However, in a great majority of these cases, such correlations have been found to exhibit poor performance. Recently, it has been brought out that the shrinkage limit of a natural soil does not depend upon plasticity characteristics, and it is primarily governed by the relative grain size distribution of the soil. The present study confirms this mechanism with the results obtained using clay-clay, clay-non-cohesive soil, and non-cohesive soil mix systems. The present study gains importance from the point of view of criteria with respect to the design of back fill materials to be used in various applications, such as nuclear waste disposal projects

  9. Organophilic clays as a tracer to determine Erosion processes

    Science.gov (United States)

    Mentler, A.; Strauss, P.; Schomakers, J.; Hann, S.; Köllensberger, G.; Ottner, F.

    2009-04-01

    In recent years the use of new tracing techniques to measure soil erosion has gained attention. Beside long time existing isotopic methods the use of rare earth elements has been reported. We wanted to contribute to the efforts of obtaining better methods for determination surface soil movement and tested a novel method using organophilic clays as a tracer for erosion related studies. At present tests to extract organophilic clays from soil have been performed successfully using an Industrial produced organophilic bentonite (Tixogel TVZ, Süd-Chemie) treated with quaternary ammonium surfactants. A liquid extraction method with barium ions (Ba2+) and methanol was used to extract the n-alkyl ammonium compounds from the inter crystal layers of the modified Bentonite. To increase extraction efficiency, an ultrasound device was used (UW 2200 Bandelin, 10.000 cycles per second, vibration amplitude 54 µm, sonification time of one minute). This procedure lead to a recovery rate of about 85% for the organophilic bentonite. This was clearly superior to alternative extraction methods such as acetonitrile in different mixing ratios. Quantification of the extracted surfactants was performed via high performance liquid chromatography - mass spectrometry (HPLC-MS, Agilent 1200 SL HPLC and 6220 time-of-flight MS). The mass spectra of this industrial produced organophilic clay mineral showed four different molecular masses (M+H+ of 304.30, 332.33, 360.36 and 388.39. The four substances could be separated by HPLC (20 x 2 mm Zorbax C18 reversed phase column, 0.5 mL/min isocratic flow with 90% acetonitrile and 0.1% formic acid in water, run time of 7 minutes). The linear working range of the method was 5 to 1000 µg/L, with a limit of quantification of 1 µg/L n-alkyl ammonium compound. All four compounds of the Tixogel were extracted with identical extraction efficiencies and are hence suitable for accurate quantification procedures. Next steps of the methodology to develop are the

  10. Water Retention Curves of Opalinus Clay

    International Nuclear Information System (INIS)

    The water retention curve of Opalinus clay samples was determined under different conditions: total and matric suction, stress or no-stress conditions, wetting and drying paths. Through the fitting of these results to the van Genuchten expression the P parameter, related to the air entry value (AEV), was obtained. The AEV is the suction value above which air is able to enter the pores of the sample, and consequently, above which 2-phase flow can take place in the soil pore structure. The samples used in this research came from two different boreholes, BHT-1 and BHG-D1, but the behaviour of them did not depend on their location, what was probably due to the fact that both were drilled in the shay facies of the Opalinus clay. There was not a distinct difference between the results obtained under total or matric suctions. In the drying paths, both the water contents and the degrees of saturation tended to be higher when total suction was applied, however the reverse trend was observed for the water contents reached in wetting paths. As well, no clear difference was observed in the water retention curves obtained in odometers under matric and total suctions, what points to the osmotic component of suction in Opalinus clay not being significant. Overall, the water contents were lower and the degrees of saturation higher when suction was applied under vertical stress, what would indicate that the water retention capacity was lower under 8 MPa vertical stress than under free volume conditions. This vertical stress value is slightly higher than the maximum in situ stress. Also, the samples showed hysteresis according to the expected behaviour, i.e. the water contents for a given suction were higher during a drying path than during a wetting path. The P values obtained were between 6 and 34 MPa, and tended to be higher for the samples tested under stress, in drying paths and when total suction was used. The air entry value calculated from the mercury intrusion porosimetry

  11. Water Retention Curves of Opalinus Clay

    Energy Technology Data Exchange (ETDEWEB)

    Villar, M. V.; Romero, F. J.

    2012-11-01

    The water retention curve of Opalinus clay samples was determined under different conditions: total and matric suction, stress or no-stress conditions, wetting and drying paths. Through the fitting of these results to the van Genuchten expression the P parameter, related to the air entry value (AEV), was obtained. The AEV is the suction value above which air is able to enter the pores of the sample, and consequently, above which 2-phase flow can take place in the soil pore structure. The samples used in this research came from two different boreholes, BHT-1 and BHG-D1, but the behaviour of them did not depend on their location, what was probably due to the fact that both were drilled in the shay facies of the Opalinus clay. There was not a distinct difference between the results obtained under total or matric suctions. In the drying paths, both the water contents and the degrees of saturation tended to be higher when total suction was applied, however the reverse trend was observed for the water contents reached in wetting paths. As well, no clear difference was observed in the water retention curves obtained in odometers under matric and total suctions, what points to the osmotic component of suction in Opalinus clay not being significant. Overall, the water contents were lower and the degrees of saturation higher when suction was applied under vertical stress, what would indicate that the water retention capacity was lower under 8 MPa vertical stress than under free volume conditions. This vertical stress value is slightly higher than the maximum in situ stress. Also, the samples showed hysteresis according to the expected behaviour, i.e. the water contents for a given suction were higher during a drying path than during a wetting path. The P values obtained were between 6 and 34 MPa, and tended to be higher for the samples tested under stress, in drying paths and when total suction was used. The air entry value calculated from the mercury intrusion porosimetry

  12. Effect of clay organic modifier on the final performance of PCL/clay nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Luduena, L.N., E-mail: luduena@fi.mdp.edu.ar [Research Institute of Material Science and Technology (INTEMA), Engineering Faculty, National University of Mar del Plata, Juan B. Justo 4302 B7608FDQ, Mar del Plata (Argentina); Kenny, J.M. [Institute of Polymers Science and Technology, ICTP, Juan de la Cierva 3, 28006 Madrid (Spain); Vazquez, A., E-mail: avazquez@fi.uba.ar [INTECIN (UBA-CONICET), Polymer and Composite Group, Engineering Faculty, University of Buenos Aires, Las Heras 2214 C1063ACV, Buenos Aires (Argentina); Alvarez, V.A., E-mail: alvarezvera@fi.mdp.edu.ar [Research Institute of Material Science and Technology (INTEMA), Engineering Faculty, National University of Mar del Plata, Juan B. Justo 4302 B7608FDQ, Mar del Plata (Argentina)

    2011-11-25

    Highlights: {yields} The degradation of clay organo-modifiers during processing affect clay dispersion degree and clay content inside the matrix. {yields} Isothermal thermogravimetrical analysis was used to simulate the thermal degradation of clay organo-modifiers in extrusion. {yields} Improving polymer-clay compatibility may not be the main factor to achieve the best mechanical performance. {yields} The best combination between PCL/clay compatibility and thermal resistance of the clay, was obtained for C20A. - Abstract: The effect of un-modified and several organo-modified montmorillonites on the morphology, mechanical properties and thermal behavior of polycaprolactone (PCL) based nanocomposites prepared by melt intercalation was studied. The study was centered on the analysis of the clay characteristics that have influence on the final properties of PCL/clay nanocomposites. Polymer/clay compatibility was analyzed studying both bulk and surface polarity degree of the clays by means of water absorption tests (bulk) and contact angle measurements (surface). The thermal stability of the clays was analyzed by dynamic thermogravimetrical tests (TGA). The degradation of the clay organo-modifiers during processing was simulated by isothermal TGA. The clay dispersion degree inside the nanocomposites was analyzed by X-ray diffractometry (XRD). The melt rheology was used as a method to compare the dispersion degree of the clay by means of the shear thinning exponent, n{sub Rh}. The tensile mechanical properties were measured and theoretically analyzed by means of several micro-mechanical models. It was found that the thermal stability of the clay organo-modifiers is a critical factor that can modify the final clay content and the clay dispersion degree inside the nanocomposite, demonstrating that the enhancement of the polymer-clay compatibility may not be the main factor to achieve the best mechanical performance when shear forces during processing, i.e. extrusion

  13. Effect of Grain Size on Selected Physico-Chemical Properties of Clay

    Directory of Open Access Journals (Sweden)

    Osumanu H. Ahmed

    2009-01-01

    Full Text Available Problem statement: Mixture of the right proportion of expanding and non-expanding clays to improve plasticity (moldability of clays used in the pot industry of Malaysia is yet to be well investigated. In addition, little is known about the choice of the right clay size to eliminate or reduce the content of undesirable compounds such as Fe2O3, Al2O3 to improve the strength of pots and roofing tiles in the country. The objective of this study was to investigate how selected physico-chemical properties of pottery clay relate to grain size of Nyalau series ((Typic Paleudults. Approach: Soil samples were refined into 25, 20 and 63 µm using size grading method. The mineralogical composition of the samples was determined using X-Ray Diffraction (XRD. The chemical composition of the samples was also determined using standard procedures. Firing was done at 800°C in a muffle furnace and the cracks of the samples recorded. Results: The clay particles with sizes 20 and 25 µm were higher in LOI and total C than that those of 63 µm regardless of grain size, the clay investigated had quartz (SiO2, illite-montmorillonite, Anatase ((TiO2 and kaolinite. Grading affected the concentrations of Fe, Al and Si as clays with particle sizes 20 and 25 µm had higher contents of the aforementioned elements compared with those of 63 µm. The clay with particles 63 µm had the best strength and this was so because the clay particles had the lowest amount of Fe, Al and Si. Conclusion: The strength of Malaysian pots could be improved upon proper grading of the clay particles.

  14. Technetium migration in natural clays

    International Nuclear Information System (INIS)

    The present work was performed within the joint research project ''Retention of repository relevant radionuclides in argillaceous rocks and saline systems'' (contract no.: 02E10981), funded by the Federal Ministry for Economic Affairs and Energy (BMWi). The aim was to obtain first insights into the interaction of the long-lived fission product technetium and natural clay with regard to a repository for high-level nuclear waste. For this purpose Opalinus Clay from Mont Terri (northern Switzerland) was used as a reference material. The nuclide technetium-99 will contribute to the radiotoxicity of spent nuclear fuel for more than thousand years due to its long half-live. In case of a leakage of the storage vessels, the geochemistry of technetium is determined by its oxidation state, at which only the oxidation states +IV and +VII are relevant. Because of the high solubility and low affinity to sorption on surfaces of minerals, Tc(VII) is considered to be very mobile and thus the most hazardous species. The focuses of this study therefore are diffusion experiments with this mobile species and investigations of the effect of ferrous iron on the mobility and speciation of technetium.rnThe interaction of technetium and Opalinus Clay was studied in sorption and diffusion experiments varying several parameters (pH value, addition of reducing agents, effect of oxygen, diffusion pathways). In the course of this study spatially resolved investigations of the speciation have been performed on Opalinus Clay thin sections and bore cores for the first time. In addition to the speciation, further information regarding elemental distributions and crystalline phases near technetium enrichments were obtained. Supplementary investigations of powder samples allowed determining the molecular structure of technetium on the clay surface.rnBoth the combination of sorption experiments with spectroscopic investigations and the diffusion experiment exhibit a reduction of Tc

  15. Mineral acquisition from clay by budongo forest chimpanzees

    NARCIS (Netherlands)

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

    2015-01-01

    Chimpanzees of the Sonso community, Budongo Forest, Uganda were observed eating clay and drinking clay-water from waterholes. We show that clay, clay-rich water, and clay obtained with leaf sponges, provide a range of minerals in different concentrations. The presence of aluminium in the clay consum

  16. Clay-based Nanocomposites Possibilities and Limitations

    Science.gov (United States)

    Papoulis, Dimitris

    2011-09-01

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

  17. Preparation and characterization of bentonite organo clay

    International Nuclear Information System (INIS)

    Bentonite clays organically modified have great potential use for environmental remediation, especially in the separation of organic compounds from the water. The aim of this work was the preparation of organophilic clays from 'Verde-Lodo' bentonite clay with the quaternary ammonium salts cetyl-pyridinium chloride and benzalkonium chloride. The materials obtained were characterized by XRD, thermogravimetric analyses, Helium picnometry, SEM and energy dispersive X-ray techniques. The results show consistently successful synthesis of the organoclay through the increase in the basal spacing, as well as salt elimination picks and presence of carbon and chlorine in the modified clays; they are inexistent elements in the natural clay. (author)

  18. Sorption of cesium on Latvian clays

    International Nuclear Information System (INIS)

    Cesium is like potassium - good solubility and mobile in a ground, easily assimilate in organism expressly brawn woof. It is a problem if pollutant is a radioactive 137Cs. We made experiments to sorption a 2M CsF solution on some Latvian clays which mainly contain hydro micas (cesium content after good elute of clays are in table). We establish, that clay treated with 25 % sulfuric acid adsorb cesium two times more that waste clay. Hereto unstuck elute Cs from clays. (author)

  19. Optimal Design of Sheet Pile Wall Embedded in Clay

    Science.gov (United States)

    Das, Manas Ranjan; Das, Sarat Kumar

    2015-09-01

    Sheet pile wall is a type of flexible earth retaining structure used in waterfront offshore structures, river protection work and temporary supports in foundations and excavations. Economy is an essential part of a good engineering design and needs to be considered explicitly in obtaining an optimum section. By considering appropriate embedment depth and sheet pile section it may be possible to achieve better economy. This paper describes optimum design of both cantilever and anchored sheet pile wall penetrating clay using a simple optimization tool Microsoft Excel ® Solver. The detail methodology and its application with examples are presented for cantilever and anchored sheet piles. The effects of soil properties, depth of penetration and variation of ground water table on the optimum design are also discussed. Such a study will help professional while designing the sheet pile wall penetrating clay.

  20. Nonlinear elastic model for compacted clay concrete interface

    Institute of Scientific and Technical Information of China (English)

    R. R. SHAKIR; Jungao ZHU

    2009-01-01

    In this paper, a nonlinear elastic model was developed to simulate the behavior of compacted clay concrete interface (CCCI) based on the principle of transition mechanism failure (TMF). A number of simple shear tests were conducted on CCCI to demonstrate different failure mechanisms; i.e., sliding failure and deformation failure. The clay soil used in the test was collected from the "Shuang Jang Kou" earth rockfill dam project. It was found that the behavior of the interface depends on the critical water contents by which two failure mechanisms can be recognized. Mathematical relations were proposed between the shear at failure and water content in addition to the transition mechanism indicator.The mathematical relations were then incorporated into the interface model. The performance of the model is verified with the experimental results. The verification shows that the proposed model is capable of predicting the interface shear stress versus the total shear displacement very well.

  1. The Adsorption Capacity, Pore Structure, and Thermal Behavior of the Modified Clay Containing SSA

    Directory of Open Access Journals (Sweden)

    Haijun Lu

    2016-01-01

    Full Text Available Sewage sludge ash (SSA was created by burning municipal sludge. The potential of clay containing 1 or 3 or 5% SSA was assessed for use as a landfill liner-soil material. Batch adsorption, low temperature N2 adsorption, and TG-DTA tests were performed to evaluate the adsorption capacity, micropore structure, thermostability, and components of soils under Cr(VI and Pb(II chemical solutions. With the increasing amount of SSA in modified clay, the adsorption capacity of Cr(VI and Pb(II to the modified clay increases gradually. After absorption, the pore size of modified clay ranges from 2 nm to 8 nm. With the increasing amount of absorption, the pore volume decreases and the specific surface area increases. With the increasing of adsorption concentration of Cr(VI and Pb(II, the mass loss percentage of modified clay increases to 23.4% and 12.6%, respectively. The modified clay containing SSA may be used as a good barrier material to attenuate contamination of Cr(VI and Pb(II in landfills.

  2. Correlation between index properties and electrical resistivity of hydrocarbon contaminated periodic marine clays

    Science.gov (United States)

    Tiwari, P.; Shah, M. V.

    2015-09-01

    Hydrocarbon contamination is a measure issue of concern as it adversely affects the soil inherent properties viz. index properties and strength properties.The main objective of this research work is to determine Electrical resistivity to study and correlate with soil index properties and engineering propertiescontaminated with hydrocarbon at the rate of 3%, 6% and 9% for the period of 15, 30 45 and 60 days and compare it with the results obtained for non-contaminated marine clay. Electrical resistivity of virgin marine clay (bentonite which is expansive in nature) and hydrocarbon contaminated clay for each percent of contamination is obtained in the laboratory for each period and its co-relation with index properties and engineering properties is proposed. CEC, EDAX tests were performed to evaluate the effect of ions of montmorillonite clays and their penetrability into hydrocarbon- clay matrix. The correlations at the end of each period for each percentage of contamination thus enabled to integrate index properties of non-contaminated and hydrocarbon contaminated marine clays with Electrical resistivity.

  3. Technetium diffusion in clay-based materials under oxic and anoxic conditions

    International Nuclear Information System (INIS)

    Diffusion coefficients were determined for Tc in compacted clay-based materials in both anoxic and oxic environments. The soils were saturated with a synthetic groundwater solution; the principle ions in solution were CA2+, Na+ and Cl-. Anoxic conditions were established by conducting the experiments in low-O2 glove box and by mixing 0.5 wt% powdered Fe with the soils. Under anoxic conditions, apparent diffusion coefficients, Da, were 2/s for Tc in compacted backfill material (a 1:3 mix by dry mass of Lake Agassiz clay and crushed granite aggregate). Distribution coefficients, Kd, for Tc on Lake Agassiz clay and backfill material in anoxic environments were back-calculated from Da values. Based on the Kd values, Tc strongly sorbs on Lake Agassiz clay and backfill under anoxic conditions. Effective diffusion coefficients De, for Tc of 10, 16 and 110 μm2/s were measured in oxic Avonlea bentonite, Lake Agassiz clay and illite-smectite, respectively, at a clay dry bulk density of ∼ 1.2 Mg/m3; the corresponding Da values were 55, 48 and 75 μm2/s. Since anoxic conditions are expected in a disposal vault excavated deep in granitic rock in the Canadian Shield, the results suggest the migration of Tc through the backfill will be relatively slow. (author) 23 refs., 9 tabs., 4 figs

  4. Characteristics of deformation of saturated soft clay under the load of Shanghai subway line No. 2

    Science.gov (United States)

    Tang, Yi-Qun; Yang, Ping; Zhao, Shu-Kai; Zhang, Xi; Wang, Jian-Xiu

    2008-05-01

    Shanghai subway Line No. 2 passes through the center of Shanghai from Songhong Road station in the west to Zhangjianggaoke station in the east. The total length of Shanghai subway Line No. 2 is 25 km. The tunnel mostly lies in the saturated soft clay and the environment issue can not be ignored. The response frequency and response stress of soil around the tunnel are monitored when the subway train passes through. The cyclic triaxial test of the saturated soft clay around the subway tunnel is conducted using the data monitored. The characteristics of deformation of the saturated soft clay of Shanghai under the subway load are analyzed. The results show that when the subway train Line No. 2 begins to run, a small and vertical rebound first occurs in the saturated soft clay at the side wall of the tunnel. Although a large deformation does not occur in the saturated soft clay at the side wall of the tunnel when the subway train has run for a period of time, yet with the lapse of time, a perceptive and non-uniform deformation will still occur. The vertical rebound is transitory and a plastic deformation occurs immediately in the saturated soft clay at the bottom of the tunnel, the large deformation at the bottom of the tunnel is 30 times that of the saturated soft clay at the side wall of the tunnel.

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

    Science.gov (United States)

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

    2015-12-01

    Bioremediation is an effective strategy for cleaning up organic contaminants, such as polycyclic aromatic hydrocarbons (PAHs) and volatile organic compounds (VOCs). Advanced bioremediation implies that biotic agents are more efficient in degrading the contaminants completely. Bioremediation by microbial degradation is often employed and to make this process efficient, natural and cost-effective materials can serve as supportive matrices. Clay/modified clay minerals are effective adsorbents of PAHs/VOCs, and readily available substrate and habitat for microorganisms in the natural soil and sediment. However, the mechanism underpinning clay-mediated biodegradation of organic compounds is often unclear, and this requires critical investigation. This review describes the role of clay/modified clay minerals in hydrocarbon bioremediation through interaction with microbial agents in specific scenarios. The vision is on a faster, more efficient and cost-effective bioremediation technique using clay-based products. This review also proposes future research directions in the field of clay modulated microbial degradation of hydrocarbons. PMID:26408945

  6. Immobilization of fungal laccase onto a nonionic surfactant-modified clay material: application to PAH degradation.

    Science.gov (United States)

    Chang, Yi-Tang; Lee, Jiunn-Fwu; Liu, Keng-Hua; Liao, Yi-Fen; Yang, Vivian

    2016-03-01

    Nonionic surfactant-modified clay is a useful absorbent material that effectively removes hydrophobic organic compounds from soil/groundwater. We developed a novel material by applying an immobilized fungal laccase onto nonionic surfactant-modified clay. Low-water-solubility polycyclic aromatic hydrocarbons (PAHs) (naphthalene/phenanthrene) were degraded in the presence of this bioactive material. PAH degradation by free laccase was higher than degradation by immobilized laccase when the surfactant concentration was allowed to form micelles. PAH degradation by immobilized laccase on TX-100-modified clay was higher than on Brij35-modified clay. Strong laccase degradation of PAH can be maintained by adding surfactant monomers or micelles. The physical adsorption of nonionic surfactants onto clay plays an important role in PAH degradation by laccase, which can be explained by the structure and molecular interactions of the surfactant with the clay and enzyme. A system where laccase is immobilized onto TX-100-monomer-modified clay is a good candidate bioactive material for in situ PAHs bioremediation. PMID:25739840

  7. Organo-clay formulations of the hydrophobic herbicide norflurazon yield reduced leaching.

    Science.gov (United States)

    Undabeytia, T; Nir, S; Rubin, B

    2000-10-01

    The study aimed to reduce leaching of the hydrophobic herbicide norflurazon (4-chloro-5-methylamino-2-(alpha,alpha, alpha)-trifluoro-m-tolylpyridazin-3-(2H)-one) by adsorbing it on clays or organo-clays. The surface of the clay mineral montmorillonite was modified from hydrophilic to hydrophobic by preadsorbing it with organic cations, of which thioflavin-T (TFT) at a loading corresponding to (5)/(8) of the cation-exchange capacity of the clay mineral yielded the highest affinity of adsorption of norflurazon. Pillared clay (PC) used without organic cations exhibited enhanced affinity for norflurazon adsorption, much higher than that of montmorillonite or sepiolite. Fourier transform infrared (FTIR) results showed interactions between aromatic moieties of preadsorbed TFT and the herbicide. Stronger interaction of the herbicide with a clay mineral or organo-clay corresponded to its slower release. Formulations prepared on the basis of montmorillonite-TFT and PC were more effective in reducing herbicide leaching in soil columns in comparison to the commercial formulation, whereas the herbicidal efficiencies were comparable. PMID:11052732

  8. MRI profiles over very wide concentration ranges: Application to swelling of a bentonite clay

    Science.gov (United States)

    Dvinskikh, S. V.; Szutkowski, K.; Furó, I.

    2009-06-01

    In MRI investigation of soils, clays, and rocks, mainly mobile water is detected, similarly to that in biological and medical samples. However, the spin relaxation properties of water in these materials and/or low water concentration may make it difficult to use standard MRI approaches. Despite these limitations, one can combine MRI techniques developed for solid and liquid states and use independent information on relaxation properties of water, interacting with the material of interest, to obtain true images of both water and material content. We present procedures for obtaining such true density maps and demonstrate their use for studying the swelling of bentonite clay by water. A constant time imaging protocol provides 1D mapping of the clay distribution in regions with clay concentration above 10 vol%. T1 relaxation time imaging is employed to monitor the clay content down to 10 -3 vol%. Data provided by those two approaches are in good agreement in the overlapping range of concentrations. Covering five orders of magnitude of clay concentration, swelling of sodium-exchanged bentonite clays from pre-compacted pellets into a gel phase is followed in detail.

  9. A Study on Sorption of (226)Ra on Different Clay Matrices.

    Science.gov (United States)

    Alhajji, E; Al-Masri, M S; Khalily, H; Naoum, B E; Khalil, H S; Nashawati, A

    2016-08-01

    The sorption of radium 226 ((226)Ra) on different clay materials (bentonite, illite and a mixture of bentonite-illite) was studied. Clay materials are used in the construction of disposal pits for technically enhanced naturally occurring radioactive materials (TENORM) wastes (i.e., contaminated soil and sludge) generated by the oil and gas industry operations. Experimental conditions (pH, clay materials quantity, and activity concentrations of (226)Ra) were changed in order to determine the optimal state for adsorption of (226)Ra. The results showed that the concentration of adsorbed (226)Ra on clay materials increased with time to reach an equilibrium state after approximately 5 h. More than 95 % of the radium was adsorbed. The mixture of bentonite-illite (1/9) exhibited the greatest adsorption of radium under all experimental conditions. PMID:27329110

  10. CLAY MINERAL ASSEMBLAGES AND THEIR IMPLICATIONS IN SHIHEZI FORMATION FROM THE HUAIBEI COAL-BEARING STRATA

    Institute of Scientific and Technical Information of China (English)

    黄文辉; 许光泉; 刑军

    1998-01-01

    Clay mineral assemblages in Shihezi Formation of Huaibei coal-bearing strata are determined by X-ray diffraction and Differential Thermal Analyzer, that is restated to the sedimentfaces and climatic changes in the source area, and to a lesser extent, alterations during burial diagenesis. In the Upper Shihezi Formation, the clay fraction is dominated by kaolinite in norther npart of the coal field, which was formed in alluvial sediment environment. But in the South ofHuaibei coal field, the clay mineral assemblage consists of mainly illite that reflects the influenceof sea water. The predominately kaolinite and sederite composition of the clay fraction in the lower Shihezi Formation sediments documents less relief and gentle erosion of kaolinite rich soils developing under warm source area. In the lower part of Shihezi Formation, some chlorite is detected, which suggests transformation of illite or kaolinite to chlorite under conditions of burial diagenesis.

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

    Energy Technology Data Exchange (ETDEWEB)

    Smith, David E.

    2000-09-14

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

  12. Modelling unfrozen water content in a silty clay permafrost deposit

    DEFF Research Database (Denmark)

    Agergaard, Frederik Ancker; Ingeman-Nielsen, Thomas

    2011-01-01

    permafrost core of material properties similar to the test soil. The calibration for 5°C is seen to make a good fit to the permafrost core data. Further experiments should be performed in order to extend the range of water contents tested and hence the range of validity of the calibration equation.......The mechanical properties of both unfrozen soils and permafrost soils are influenced by the amount of unfrozen water in the pore space. When dealing with foundation engineering in permafrost areas it is essential to estimate the unfrozen water content (wu). This paper deals with the establishing of...... a calibration equation for determining the unfrozen water content of a Greenlandic silty clay permafrost deposit. Calibration experiments have been conducted for water contents in the interval 0 – 10 % at both 5 °C and 22 °C. Calibration equations are verified against permittivity data from a...

  13. Searching for reciclability of modified clays for an environmental application

    Science.gov (United States)

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

    2014-05-01

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

  14. Electrokinetic-enhanced bioaugmentation for remediation of chlorinated solvents contaminated clay.

    Science.gov (United States)

    Mao, Xuhui; Wang, James; Ciblak, Ali; Cox, Evan E; Riis, Charlotte; Terkelsen, Mads; Gent, David B; Alshawabkeh, Akram N

    2012-04-30

    Successful bioremediation of contaminated soils is controlled by the ability to deliver bioremediation additives, such as bacteria and/or nutrients, to the contaminated zone. Because hydraulic advection is not practical for delivery in clays, electrokinetic (EK) injection is an alternative for efficient and uniform delivery of bioremediation additive into low-permeability soil and heterogeneous deposits. EK-enhanced bioaugmentation for remediation of clays contaminated with chlorinated solvents is evaluated. Dehalococcoides (Dhc) bacterial strain and lactate ions are uniformly injected in contaminated clay and complete dechlorination of chlorinated ethene is observed in laboratory experiments. The injected bacteria can survive, grow, and promote effective dechlorination under EK conditions and after EK application. The distribution of Dhc within the clay suggests that electrokinetic transport of Dhc is primarily driven by electroosmosis. In addition to biodegradation due to bioaugmentation of Dhc, an EK-driven transport of chlorinated ethenes is observed in the clay, which accelerates cleanup of chlorinated ethenes from the anode side. Compared with conventional advection-based delivery, EK injection is significantly more effective for establishing microbial reductive dechlorination capacity in low-permeability soils. PMID:22365139

  15. Modernity and putty-clay

    Science.gov (United States)

    Ganesh, Trichur Kailas

    This dissertation addresses issues arising out of the problems of capital accumulation, productivity growth and 'putty-clay' technology. The concept of economic modernity occupies a central place in the subject-matter studied here in that it expresses both the incessant drive for newness that characterizes economic reality and the persistence of dated techniques that successfully resist replacement. This study examines the way in which an expansive development-theoretic 'putty-clay' framework may be employed to explain the historical processes behind both the avalanche of newness (innovations) and the conservatism of technology in the U.S. economy. The guiding link is the fixity of investments in physical capital equipment over time and space. The dilemma of fixed capital is studied in the context of the constant entrepreneurial search for flexibility and liquidity. The thesis advanced is that a development (Entwicklung)-theoretic 'putty-clay' conceptualization of the economic system adequately addresses the recurring problems of fixity, flexibility, and liquidity, and thereby permits important insights into the enigma surrounding the persistent productivity growth slowdown and 'stagflation' of the late sixties and seventies and the related phenomena of physical 'capital obsolescence' and the financial or 'speculative explosions' of our times. The notion of 'putty-clay' used here is an innovative one in that it departs from the growth-theoretic literature to re-appear as a Schumpeterian theory of modernity modified by a Veblenite view of an economic system directed by the exigencies of the 'machine-process'. The empirical aptitude of a macroeconomic 'putty-clay' model to explain capital obsolescence mediated by the energy 'crises' (supply shocks) of the seventies and eighties is examined in a separate chapter with results that differ markedly from the standard (Berndt and Wood) conclusions for the U.S. economy. The final chapter in the dissertation reverts to the

  16. Hydraulic conductivity in sugar cane cultivated in soils previous vin aza application

    International Nuclear Information System (INIS)

    This work analyzes the hydraulic conductivity in soil clay loams developed in Libertad formation in Bella Union where grows sugar cane with vinaza. In the agricultural activities are used different chemical additives such as organic and inorganic fertilizers, herbicides and pesticides, which interact with the biotic (roots, soil microbiology) and abiotic (clay, soil solution, etc.) elements

  17. Effects of Soil and Rock Mineralogy on Soil Erosion Features in the Merek Watershed, Iran

    OpenAIRE

    Mosayeb Heshmati; Nik M. Majid; Shamshuddin Jusop; Mohamad Gheitury; Arifin Abdu

    2013-01-01

    Accelerated soil erosion is anthropogenic phenomenon and a major worldwide environmental problem. It mainly leads to removal of the clay minerals and soil nutrients and thereby reduces soil fertility because of mineralogical influence on the soil. The objectives of this study were to identify the dominant soil and rock minerals and the influences of mineralogical properties on soil erosion features. This study was conducted at the Merek watershed, located in Kermanshah, Iran. There are diff...

  18. Effects of soil moisture content and tractor wheeling intensity on traffic-induced soil compaction

    OpenAIRE

    AHMADI, Iman; GHAUR, Hossein

    2015-01-01

    Soil compaction causes deleterious effects on physical and mechanical proprieties of agricultural soils. In order to investigate the effect of soil moisture content and tractor wheeling intensity on traffic-induced soil compaction, this study was carried out on a field with clay loam soil. Soil dry bulk density and hydraulic conductivity as well as emergence percentage of corn seedlings and dry mass of the sampled mature plants were considered the dependent variables of the experiment. Ind...

  19. Considering Organic Carbon for Improved Predictions of Clay Content from Water Vapor Sorption

    DEFF Research Database (Denmark)

    Arthur, Emmanuel; Tuller, Markus; Moldrup, Per; Karup Jensen, Dan; de Jonge, Lis Wollesen

    2014-01-01

    Accurate determination of the soil clay fraction (CF) is of crucial importance for characterization of numerous environmental, agricultural, and engineering processes. Because traditional methods for measurement of the CF are laborious and susceptible to errors, regression models relating the CF to...... carbon (OC) content and propose a modification to improve prediction accuracy. Evaluation of the CF prediction accuracy for 29 soils with clay contents ranging from 6 to 25% and with OC contents from 2.0 to 8.4% showed that the models worked reasonably well for all soils when the OC content was below 2...... water vapor sorption isotherms that can be rapidly measured with a fully automated vapor sorption analyzer are a viable alternative. In this presentation we evaluate the performance of recently developed regression models based on comparison with standard CF measurements for soils with high organic...

  20. Factors affecting the hydraulic performance of infiltration based SUDS in clay

    DEFF Research Database (Denmark)

    Bockhorn, B.; Klint, K.E.S.; Locatelli, Luca;

    2015-01-01

    The influence of small scale soil heterogeneity on the hydraulic performance of infiltration based SUDS was studied using field data from a clayey glacial till and groundwater simulations with the integrated surface water and groundwater model HydroGeoSphere. Simulations of homogeneous soil blocks...... with hydraulic properties ranging from sand to clay showed that infiltration capacities vary greatly for the different soil types observed in glacial till. The inclusion of heterogeneities dramatically increased infiltration volume by a factor of 22 for a soil with structural changes above and below...