Showing papers on "Vermiculite published in 1981"

Dissipation of Chlorpyrifos from Dry Soil Surfaces

Abstract: Hydrolysis and volatility contributed to loss of 14C-ring-labeled chlorpyrifos on air-dried surfaces of SOils and soil clays in the laboratory. Dissipation rates were influenced by temperature, composition of the substrate, and level of hydration. Chlorpyrifos degraded rapidly via a temperature-dependent catalytic hydrolysis process on Sultan silt loam. Times for 50% degradation at 5, 15, 25, 35, and 45°C were >20, >20, 8, 3, and 1 day, respetively, when ambient RH levels were 93, 67, 38, 30, and 10%, respectively. The insecticide degraded even more rapidly on air-dried surfaces of calcium homoionic clays (illite, vermiculite, adkaolinite) and clay separates isolated from Sultan silt loam and Chehalis clay loam. Degradation was slower on a sandy loam, on montmorillinite, and on an organic soil and negligible on pulverized peat moss and quartz sand. An increae in the sorbed water content of air-dried substrates decreased the rate of the clay-catlyzed hydrolysis reaction and increased the volatilization rate of 14C from mineral substrate surfaces. 3,5,6-trichloro-2-pyridinol was the only 14C-breakdown product found in acetone extracts of aged, chlorpyrifos-treated soils and homoionic clays.

Interaction of chlordimeform with clay minerals

Abstract: The adsorption-desorption of the cationic pesticide chlordimeform from aqueous solutions on montmorillonite, kaolinite, illite, and vermiculite appears to be a cation-exchange process coupled with the coadsorption of neutral molecules and the extraction of AI from the structure of the mineral. Chlordimeform adsorption on montmorillonite, illite, and vermiculite by cation exchange is an irreversible process, where- as chlordimeform adsorbed on kaolinite is weakly bonded to the clay and easily removed by washing with water. X-ray powder diffraction and infrared spectroscopic data show that chlordimeform cations are ad- sorbed in the interlamellar spaces of montmorillonite at charge sites, lying in a fiat position in contrast to kaolinite, illite, and vermiculite, where they adsorb on external surfaces or charge sites close to the crystal edges.

Weathering of Micaceous Minerals in Some Salt-Affected Soils

Abstract: Mineralogy of some sodic soil profiles developed on alluvium was investigated both by X-ray and optical methods. The sand fractions showed a dominance of quartz and feldspars in association with white mica, biotite and other accessory minerals. Semiquantitative estimates of minerals in the silt fractions indicated illite as the dominant mineral followed by mixed layers, chlorite and vermiculite. Subsequent weathering produced vermiculite, smectite and two-component (10–14 A) as well as three-component (10.14–14 A) interstratified minerals in the clay fractions. A plausible mechanism involving K depletion together with Fe2+ oxidation and subsequent movement of Fe3+ from the octahedral positions under the seasonally arid environment appeared to be responsible for the transformation of biotite to smectite through the intermediate stages of (10–14) A interstratification. The principle of ‘nucleation and silication’ has been invoked to explain the three-component interstratification.

Mineralogy, O18/O16, and D/H Ratios of Clay-Rich Sediments from Deep Sea Drilling Project Site 180, Aleutian Trench1

Abstract: Mineralogy, O18/O16, and D/H ratios have been determined in five size fractions ( 2.0µm) of seven samples taken from 500 m of Pleistocene deep-sea sediments cored at Deep Sea Drilling Project Site 180 in the Aleutian Trench. The depositional age of the samples spans the last 300,000 years; the samples have been interpreted by others to be continental detritus weathered from a mixed igneous, metamorphic, and sedimentary source area and then deposited by ice-rafting and turbidity currents. The minerals present are quartz, feldspar, illite, chlorite and/or non-expandable vermiculite, and expandable vermiculite and/or mixed-layer illite/expandable vermiculite. The relative amounts of quartz, feldspar, and total clay vary with particle size, but are nearly constant from sample to sample for a given particle size. δO18 is values of the four coarser size fractions range from +9.7 to +12.0‰ with variations attributable to changes in quartz/feldspar and clay/(quartz + feldspar) abundances. Values of δO18 for the expandable vermiculite-rich <0.1-µm size fraction range from +12.1 to +16.3‰ which indicates some oxygen isotope exchange at surface temperatures between meteoric waters and the parent rock during vermiculite formation. Values of δD range from −46 to −74‰ with variations attributable to changes in amounts of different clay minerals present. There is no mineralogic or isotopic evidence of post-depositional reactions in the coarser size fractions, but a general change in δD of the vermiculite-rich, <0.1-µm size fraction from about −50‰ to about −70‰ with increasing depth may be due either to post-depositional isotopic exchange or to climatic changes in the terrestrial weathering environment.

Application of scanning electron microscopy in the analysis of the 2:1 group of clay minerals: Vermiculite

Abstract: Various pretreatments required for analysis of vermiculite minerals by scanning electron miscroscopy are described. It is shown that lyophilized samples exhibit more characteristic and reproducible micrographs than when simply dried in air. The mineral should e preheated in vacuum at 150°C to aviod the risk of exfoliation. In view of the fragile structure of clay minerals, polishing of the solid is to be avioded.

Potting Media Affect Growth and Disease Development of Container-Grown Southern Pines

Abstract: Longleaf pine (Pinus palustris Mill.) and shortleaf pine (F! echinata Mill.) seedlings grew best in equal parts of peat and vermiculite with a low pH. Seedlings grew better in shredded pine cone media than pine bark media. Growth increased when soil or vermiculite was added to cone or bark chips. Commercial bark-vermiculite media with high pHs produced the smallest seedlings: Disease loss was related to drainage and pH. Seedling mortal i ty was greatest in commercial media with pHs above 6.0. Losses, lowest in bark media, increased as the proportion of vermiculite increased. Addltional keywords: Pinus, Pythium, Fusarium, damping-off, seedlings, tubelings.

Soil clay mineralogy in relation to fertility management: Effect of soil clay mineral composition on potassium fixation under conditions of upland rice soils

Abstract: Since K fixation in soils is largely a function of clay mineralogy, an effort was made to elucidate the influence of mineralogical variations in soil clays on K fixation, under the moisture-temperature regimes usually prevalent in tropical upland rice soils. Beidellitic clay turned out to be the most severe fixer of addedK (80%), followed by vermiculitic (69%) clays. Fixation is not appreciable (< 15%) in clays consisting of montmorillonite, x-ray amorphous material, chlorite, hydrous mica, kaolinite and halloysite. Fixation by beidellite and vermiculite clays is reduced by the simultaneous occurrence of other mineral species.

Desiccating agent for high humidity

Abstract: PURPOSE: To obtain a desiccating agent of high economy and effect by impregnating open-cellular porous mineral carriers consistig of particles of expanded vermiculite or pearlite with inorg. salts, such as calcium chloride and others, which cause deliquescence by absorbing moisture. CONSTITUTION: The under-mentioned carrier is jimpregnated with inorg. salts, such as calcium chloride, magnesium chloride and others, which have a high capaicyt of moisture absorption and deliquescence: The mixed carriers of 1 or 2 kinds of open-cellular porous mineral carriers consisting of vermiculite with 0.5W3mm grain sizes or pearlite with 0.5W3mm grain sizes obtd. by expansion are impregnation is, for example, 40W60% (as dihydrate salt) in case of calcium chloride. COPYRIGHT: (C)1982,JPO&Japio

Caracteristiques mineralogiques et chimiques de quelques sols sableux du quebec en regard de leur evolution pedologique

Abstract: A, B and C horizons of 13 sandy soil series were sampled in the lowlands of southern Quebec. From the amounts of pyrophosphate-extractable Fe and Al and clay contents, nine of these profiles were classified as Podzolic soils while the others were Brunisols. Formation of montmorillonite and dissolution of chlorite in Ae horizons indicate intense weathering of the minerals at this level. In the B horizons, vermiculite that was present in the parent material or resulted from the alteration of illite was often chloritized. Values of pH measured in 1 M NaF were generally higher than 10.2 for the B horizons. The amounts of phosphorus retained by the samples varied in the following ranges: 23–397 μg P/g of soil for A horizons, 301–1578 μg P/g of soil for B horizons and 71–296 μg P/g of soil for C horizons. Cation exchange capacity of the soils was lower than 10 meq/100 g of soil, except in those horizons that contained high amounts of organic matter and where values up to 27.6 meq/100 g were measured. Using regr...

Evaluation of the axial ratio of soil clays from gray lowland soils based on viscosity measurements

Abstract: The axial ratio of soil clays differing in their major mineral species was evaluated. The axial ratio for clays containing smectite as the predominant mineral was 18–24. Based on this axial ratio and the smectite content, the axial ratio for soil smectite was calculated to be 36–51. This value was lower than the axial ratio (90–97) for mineral montmorillonite. Clays containing kaolinite, mica, vermiculite, and vermiculite(or smectite)-chlorite intergrade as dominant minerals had axial ratios ranging from 9 to 16, depending on the specific surface area. For all the clays, the axial ratio increased linearly with increasing specific surface area. Also, in the region of a surface area of 200–400 m2/g, the increase in surface area was due mainly to splitting of the particles in a direction parallel to the ab-plane.

Heat insulating material for refining or casting of metal

Abstract: PURPOSE:To improve the performance in high-temp. use by using diatomaceous earth or pulp sludge as a main raw material, compounding vermiculite with this and granulating these by using a specific binder, followed by drying. CONSTITUTION:Diatomaceous earth or plup sludge is used as a main raw material, and bentonite or the like is suitably compounded with these and these are mixed. A suitable amount of vermiculite is compounded with this mixture and the mixture is granulated by using an aqueous carboxymethylcellulose soln. or aqueous sodium silicate soln. as the binder, followed by drying. The materail compounded with vermiculite in this way is collapsed by the expansion of vermiculite at the instant when it is charged into a high-temp. atmosphere, whereby it is diffused to a uniform layer, and this achieves the decreased heat conductivity and bulk density and the expanded heat insulation layer.

X-ray absorption study of vermiculite mica

Abstract: The K-absorption spectrum has been studied in vermiculite mica with a view to studying its Fe2+/Fe3+ ratio and Fe-O bond length before and after subjecting it to heat treatment at 800 degrees C. The heat treatment is found to lead to near total conversion of Fe2+ to Fe3+, but the value of the bond length does not seem to change significantly. The 'white line' observed in its spectrum, ascribed to exciton levels, is found to broaden on heat treatment. The results are compared with those obtained on other trioctahedral micas in an earlier study.

Animal, e.g. cat, excrement absorbent - contg. ground vermiculite, gypsum and/or ground clay

Abstract: Parent patent described an absorbent, (A), for animal excrement consisting of vermiculite having bulk wt. less than 200 (100) g/l and grain-size no more than 15 (3-6)mm. In this Addn., the absorbent, (B), consists of granular vermiculite, gypsum and/or ground clay and pref. has bulk wt. 0.3-0.8 (0.3-0.5) g/ml. Granular absorbent (B) does not adhere to long fur, and is partic. suitable for indoor toilet use by cats, e.g. in flats.

Soil improving method used in the green house

Abstract: A soil improving method in the green house was described Thus, plant fiber of rice-bran, saw-dust or buckwheat-bran was carbonized by 35-95 % and grinded vermiculite, peat, zeolite or bentonite with 3-150 mesh were prepd. separately. Another humus or plant fiber was added with some enzymes, urea or ammonia to be performed fermn. procedure at 20-80≰C by the moisture content of 60-80 %. These three substances were mixed together with the weight ratio of 2-8%; 77-95 %; 3-15%. Disinfection treatment was followed at 50-90≰C and PH 3.5-8.0.

Mechanism and reaction course in the process of alteration of phlogopite

Abstract: Alteration mechanism of phlogopite was studied with Ca-bearing aqueous solution in laboratory. The experiment was undertaken in two systems ; one is batch system regarded as a closed one and the other is batch-flow system corresponding to a quasi-open one. Both vermiculite (14.9 A) and regularly interstratified phlogopite/vermiculite (25.7 A) were formed in the process of the alteration of phlogopite. Of them, there were two types of interstratified mineral from the viewpoint of its genesis. One is the interstratified mineral which is formed directly from phlogopite accompanied with gradual leaching of K ion (type I) and the other is formed from vermiculite that regains K ion from ambient solution after an initial loss (type II). Formation mechanism of alteration mineral and reaction course in the process of the alteration of phlogopite are greatly controlled by concentration of K ion in the reaction solution and its flow rate.

Micromorphologie de sols bruns acides sur materiaux granitiques

Abstract: The authors have studied brown acid soils on granites in Morvan (northeastern Massif Central). On granites, the fine material of A and B horizons results from: (1) the collapse of deeply weathered plagioclases altered in small secondary micas and in kaolinite; (2) the clay and silt clay coatings present in the B horizon and in the saprolith, (3) an intense comminution of micas, orthoclases and even quartz, and also plant remnants. On granites, vermiculite and hydroxy aluminous vermiculite increase considerably in the A and B horizons due to a rapid weathering of fine-textured micas, mostly biotites. Fine and silty material (mineral and organic) is randomly aggregated into small peds, 70–100 μm in size. These are called ocric aggregates. Often they are packed into secondary, blocky peds. The cement of ocric aggregates was assumed to be amorphous organic matter. All A and B horizons of brown acid soils have eluvial properties. On granites, such properties are weakly expressed, being limited to the edges of ...