Origin of the high sensitivity of Chinese red clay soils to drought: Significance of the clay characteristics

AbstractThe tropical red clay soils, formed by the Quaternary weathering of volcanic deposits (and other rock types) in tropical and subtropical environments, have a very open structure and consequent high voids ratio. These soils are particularly sensitive to disturbance during sampling and subsequent transportation and extrusion of the samples. This technical note describes a simple method for obtaining high quality, undisturbed samples from pits in a way that does not require extrusion or trimming of the sample in the laboratory prior to triaxial testing, and only minimal preparation prior to oedometer testing.

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Erosion control at construction sites on red clay soils

Environmental Management ◽

10.1007/bf01875066 ◽

1982 ◽

Vol 6 (4) ◽

pp. 343-352 ◽

Cited By ~ 4

Author(s):

A. Dennis Lemly

Keyword(s):

Erosion Control ◽

Clay Soils ◽

Construction Sites ◽

Red Clay

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A soil catena on weathered basalt in Queensland

Soil Research ◽

10.1071/sr9740001 ◽

1974 ◽

Vol 12 (1) ◽

pp. 1 ◽

Cited By ~ 7

Author(s):

RH Gunn

Keyword(s):

Soil Properties ◽

Clay Minerals ◽

Plant Communities ◽

Parent Rock ◽

Clay Soils ◽

Red Clay ◽

Parent Materials ◽

Surface Cover ◽

Soil Catena ◽

Fresh Rock

Deep weathering in the upper layers of basalt flows in central Queensland led to the deveIopment of lateritic profiles with a surface cover of leached red clay soils overlying ferruginous and mottled zones. Subsequent erosion and bevelling of the weathered mantle left small residuals of the old surface and exposed the underlying weathered zones. In places the mantle was completely removed to uncover fresh rock. A soil catena comprising six zones with associated discrete plant communities developed in these landscapes. Soil differences are related to variations in the intensity of weathering of parent materials and the leaching, translocation, and precipitation of differentially soluble and mobile constituents of the parent rock. The sequence of clay minerals is kaolinite -->kaolinite + randomly interstratified material + montmorillonite --> montmorillonite. The distribution of the plant communities is closeIy associated with variations in soil properties, particularly those which affect water relationships.

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Vegetation analysis for the rehabilitation of red clay soils at Panchkhal, Kabhrepalanchok District

Banko Janakari ◽

10.3126/banko.v10i1.17649 ◽

2017 ◽

Vol 10 (1) ◽

pp. 20-27

Author(s):

Sushim R. Baral ◽

Mrigendra B. Malla ◽

John Howell

Keyword(s):

Clay Soils ◽

Vegetation Analysis ◽

Red Clay

Abstract on PDF

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Influence of the insecticides acetamiprid and carbofuran on arylamidase and myrosinase activities in the tropical black and red clay soils

Environmental Monitoring and Assessment ◽

10.1007/s10661-015-4631-2 ◽

2015 ◽

Vol 187 (6) ◽

Cited By ~ 5

Author(s):

G. Jaffer Mohiddin ◽

M. Srinivasulu ◽

N. R. Maddela ◽

B. Manjunatha ◽

V. Rangaswamy ◽

...

Keyword(s):

Clay Soils ◽

Red Clay

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Radio Measurements of Coronal Magnetic Fields

International Astronomical Union Colloquium ◽

10.1017/s0252921100024933 ◽

1994 ◽

Vol 144 ◽

pp. 21-28 ◽

Cited By ~ 4

Author(s):

G. B. Gelfreikh

Keyword(s):

Magnetic Field ◽

Magnetic Fields ◽

Solar Corona ◽

Active Regions ◽

High Sensitivity ◽

Coronal Magnetic Field ◽

Transverse Magnetic ◽

Radio Sources ◽

Radio Waves ◽

Solar Active Regions

AbstractA review of methods of measuring magnetic fields in the solar corona using spectral-polarization observations at microwaves with high spatial resolution is presented. The methods are based on the theory of thermal bremsstrahlung, thermal cyclotron emission, propagation of radio waves in quasi-transverse magnetic field and Faraday rotation of the plane of polarization. The most explicit program of measurements of magnetic fields in the atmosphere of solar active regions has been carried out using radio observations performed on the large reflector radio telescope of the Russian Academy of Sciences — RATAN-600. This proved possible due to good wavelength coverage, multichannel spectrographs observations and high sensitivity to polarization of the instrument. Besides direct measurements of the strength of the magnetic fields in some cases the peculiar parameters of radio sources, such as very steep spectra and high brightness temperatures provide some information on a very complicated local structure of the coronal magnetic field. Of special interest are the results found from combined RATAN-600 and large antennas of aperture synthesis (VLA and WSRT), the latter giving more detailed information on twodimensional structure of radio sources. The bulk of the data obtained allows us to investigate themagnetospheresof the solar active regions as the space in the solar corona where the structures and physical processes are controlled both by the photospheric/underphotospheric currents and surrounding “quiet” corona.

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Backscattered Electron Imaging of GaAs/AlGaAs Super Lattice Structures with an Ultra-High- Resolution SEM

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100103103 ◽

1988 ◽

Vol 46 ◽

pp. 204-205

Author(s):

Kazumichi Ogura ◽

Michael M. Kersker

Keyword(s):

High Resolution ◽

Layer Structure ◽

High Sensitivity ◽

Beam Current ◽

Electron Beam Current ◽

Lattice Structures ◽

Super Lattice ◽

Different Types ◽

Backscattered Electron ◽

Electron Imaging

Backscattered electron (BE) images of GaAs/AlGaAs super lattice structures were observed with an ultra high resolution (UHR) SEM JSM-890 with an ultra high sensitivity BE detector. Three different types of super lattice structures of GaAs/AlGaAs were examined. Each GaAs/AlGaAs wafer was cleaved by a razor after it was heated for approximately 1 minute and its crosssectional plane was observed.First, a multi-layer structure of GaAs (100nm)/AlGaAs (lOOnm) where A1 content was successively changed from 0.4 to 0.03 was observed. Figures 1 (a) and (b) are BE images taken at an accelerating voltage of 15kV with an electron beam current of 20pA. Figure 1 (c) is a sketch of this multi-layer structure corresponding to the BE images. The various layers are clearly observed. The differences in A1 content between A1 0.35 Ga 0.65 As, A1 0.4 Ga 0.6 As, and A1 0.31 Ga 0.69 As were clearly observed in the contrast of the BE image.

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An x-ray microprobe based upon a close-coupled focal-spot / glass capillary arrangement

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100133424 ◽

1992 ◽

Vol 50 (2) ◽

pp. 1758-1759

Author(s):

D. A. Carpenter ◽

M. A. Taylor

Keyword(s):

Imaging Techniques ◽

Fluorescence Analysis ◽

High Sensitivity ◽

Specimen Preparation ◽

X Rays ◽

Glass Capillary ◽

Close Coupling ◽

X Ray ◽

Point To Point ◽

Beam Damage

The development of intense sources of x rays has led to renewed interest in the use of microbeams of x rays in x-ray fluorescence analysis. Sparks pointed out that the use of x rays as a probe offered the advantages of high sensitivity, low detection limits, low beam damage, and large penetration depths with minimal specimen preparation or perturbation. In addition, the option of air operation provided special advantages for examination of hydrated systems or for nondestructive microanalysis of large specimens.The disadvantages of synchrotron sources prompted the development of laboratory-based instrumentation with various schemes to maximize the beam flux while maintaining small point-to-point resolution. Nichols and Ryon developed a microprobe using a rotating anode source and a modified microdiffractometer. Cross and Wherry showed that by close-coupling the x-ray source, specimen, and detector, good intensities could be obtained for beam sizes between 30 and 100μm. More importantly, both groups combined specimen scanning with modern imaging techniques for rapid element mapping.

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