Determination of soil water content by X-ray computed tomography and magnetic resonance imaging

Anderson, Stephen H.; Gantzer, Clark J.

doi:10.1007/bf00266158

Cited by 15 publications

(6 citation statements)

References 19 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…nondestructive, 3-D morphological characterization of parts of the soil in its 3-phase composition (Hainsworth and soil structure at the microscale level. X-ray CT measure- Aylmore, 1983 and; Phogat ments have previously been used to obtain nondestruc- et al, 1991): tive measurements of water content and dry bulk density (Petrovic et al, 1982;Crestana et al, 1985;Brown et soil (x,y,z) ϭ SV(x,y,z) matrix ϩ WV(x,y,z) water [1] al., 1987;Anderson et al, 1988;Jenssen and Heyerdahl, where soil (x,y,z ) is the linear x-ray attenuation coefficient 1988; Tollner and Ramseur, 1988;Tollner and Verma, (cm Ϫ1 ) of a particular soil volume element as a function of its Hopmans et al, 1992Hopmans et al, , 1994, as well as macropospatial coordinates x, y, and z; SV(x,y,z ) is the relative solid rosity and pore continuity ; Warner volume (cm 3 cm Ϫ3 ); WV(x,y,z ) is the volumetric water content Anderson et al, 1990;Peyton et al, 1992; (cm 3 cm Ϫ3 ); matrix is the linear x-ray attenuation coefficient of soil matrix (cm Ϫ1 ); and water is the linear x-ray attenuation Grevers and de Jong, 1994). In addition, CT has been coefficient of water (cm Ϫ1 ).…”

mentioning

confidence: 99%

Discrimination of Soil Phases by Dual Energy X‐ray Tomography

Rogasik

Crawford

Wendroth

et al. 1999

Soil Science Soc of Amer J

View full text Add to dashboard Cite

ergy-level scanning, which is characterized by scanning with two different energy levels simultaneously. Impor-Numerous soil ecological functions are influenced by soil structure tant results from dual energy-level scanning with x-rays through its impact on spatial and temporal distributions of soil particles, water, and air within the soil profile. The nondestructive tech-and ␥-rays were presented by Phogat et al. (1991) and nique of x-ray computed tomography (CT) was used for studying soil DiCarlo et al. (1997). We apply dual energy x-ray CT structure. X-ray attenuation determined for two energy levels (80 kV using a commercial scanner (i) to determine the variaand 120 kV) was used to calculate distributions of water, air, and tions of water content, dry bulk density, and phase comsolids, as well as the voxel dry bulk density for two silt loam subsoils. position at the microscale and (ii) to measure their spa-The spatial resolution during scanning was 0.25 mm in the horizontal tial distribution in naturally structured soils. These and 1 mm in the vertical direction. For different voxel sizes, the measurements for the characterization of soil structure weighted mean of the derived volumetric water, air, and solid contents, should enhance our knowledge regarding the impact of and the dry bulk densities agreed with the sample's phase composition soil structure on water and gas transport processes. and dry bulk density obtained by weighing. The use of dual energy scanning to study the heterogeneity of soil structure and the spatial distribution of water, air, and solids is discussed. THEORY Soil Phases, the Linear Attenuation Coefficient, and Hounsfield Unit A n important limitation in soil science is the lack The three phases of soil (solid, water, and air) contribute of knowledge concerning the effect of soil structure specifically to the attenuation of x-rays depending on their on functional processes. The application of x-ray comvolumetric fractions. A linear relationship exists between the puted tomography (CT) provides the possibility for a linear attenuation coefficient, soil , as measured for defined

show abstract

mentioning

confidence: 99%

Discrimination of Soil Phases by Dual Energy X‐ray Tomography

Rogasik

Crawford

Wendroth

et al. 1999

Soil Science Soc of Amer J

View full text Add to dashboard Cite

show abstract

“…Omasa et al (1985), employing a saturation-recovery MRI pulse sequence, reported successful MR images of plant roots growing in pots filled with a 1 : 1 (v/v) mixture of perlite and peat moss. However, when Anderson and Gantzer (1989) compared CAT and MRI methods for determining soil-water contents in two types of silt-loam soil in crumbs packed into soil columns and saturated either with distilled water or solutions of 20% CuSO 4 or of 0.01% Cu(NO 3 ) 2 , their attempts to obtain MR images for these soil columns all failed. They realized that, even though the magnetic field strength used was relatively low (0.6 T), failure to observe an adequate MR signal intensity was due to the loss of magnetization during the long echo time (90 ms) used in this spin±echo imaging pulse sequence.…”

Section: The Application Of Mri To Studies Of Static and Dynamic Amentioning

confidence: 94%

Infiltration into soils, with particular reference to its visualization and measurement by magnetic resonance imaging (MRI)

Amin

Hall

Chorley

et al. 1998

Progress in Physical Geography: Earth and Environment

View full text Add to dashboard Cite

This article draws attention to the potential of magnetic resonance imaging (MRI) for studies of patterns and mechanisms of water infiltration into soils, and stresses the vitally important need for collaboration between hydrologists, soil physicists and MRI experts. A brief introduction of the principles of MRI is given. This is followed by a review of the literature relating to nonpreferential infiltration, preferential infiltration exhibiting fingering and preferential infiltration involving a wide range of macropore flow. These differing degrees of complexity of infiltration dynamics require the employment of noninvasive and nondestructive techniques for their detailed investigation. Finally, an overview of applications of MRI to the detection of the spatial and temporal distribution of soil moisture and its changes is given. General conclusions are drawn from previous and current research, and the potential of the application of MRI to infiltration studies is summarized.

show abstract

“…Simple systems, such as sand/ water/air mixtures, are readily imaged by the pulse sequence we will analyze. More complex systems, such as soils, are imaged with difficulty [Anderson and Gantzer, 1989] due to the presence of magnetic and paramagnetic materials which can drastically alter the relaxation time characteristics of a sample. This type of problem can be circumvented by creative pulse sequence design, and indeed, much of current NMR imaging research is aimed at solving such problems.…”

Section: •=--+• (17) R(r) T2 T2 I(r)mentioning

confidence: 99%

Use of Nuclear Magnetic Resonance as an Experimental Probe in Multiphase Systems: Determination of the Instrument Weight Function for Measurements of Liquid‐Phase Volume Fractions

Maneval¹,

McCarthy²,

Whitaker³

1990

Water Resources Research

View full text Add to dashboard Cite

The relativist approach (Baveye and Sposito (1984)) to the interpretation of measurements in multiphase systems was proposed in order to incorporate the details of measurements into theoretical analyses of multiphase transport processes. To help establish the utility of this approach, the weight functions for actual experimental probes must be determined. In this paper we analyze the measurement of liquid-phase porosity in a model system by nuclear magnetic resonance imaging. We show how both nuclear magnetic resonance (NMR) physics and experimental technique combine to determine the weight function for the spin-warp spin-echo sequence. The analysis shows clearly what aspects of the weight function are determined by the experimental method and what aspects are determined by the system being studied. The results will help establish the utility of the relativist approach as well as improve understanding NMR measurements in multiphase systems.

show abstract

Determination of soil water content by X-ray computed tomography and magnetic resonance imaging

Cited by 15 publications

References 19 publications

Discrimination of Soil Phases by Dual Energy X‐ray Tomography

Discrimination of Soil Phases by Dual Energy X‐ray Tomography

Infiltration into soils, with particular reference to its visualization and measurement by magnetic resonance imaging (MRI)

Use of Nuclear Magnetic Resonance as an Experimental Probe in Multiphase Systems: Determination of the Instrument Weight Function for Measurements of Liquid‐Phase Volume Fractions

Contact Info

Product

Resources

About