Investigation of dryland salinity using the electrical image method

Soil Research ◽  
1999 ◽  
Vol 37 (4) ◽  
pp. 623 ◽  
Author(s):  
R. I. Acworth
Keyword(s):  
Electrical Conductivity ◽  
Salt Content ◽  
Image Method ◽  
Dryland Salinity ◽  
Conductivity Variation ◽  
South Wales ◽  
Electrical Imaging ◽  
Profile Line ◽  
Conductivity Anomalies ◽  
A Site

Electrical imaging is a 2-dimensional investigation method that can be used to rapidly determine subsurface conductivity variation. In dryland salinity studies, electrical imaging is used to define the vertical extent of high electrical conductivity zones first identified using electromagnetic (EM) profiling equipment. Field techniques are described using 25 or 50 electrodes, connected to a resistance meter by a multi-core cable, to obtain images at a variety of electrode separations. The model of electrical conductivity variation obtained by an inversion of the field data is shown to agree very well with the results of detailed field investigations, including data from soil sampling, 1 : 5 extract analysis, and borehole electrical conductivity logging. Results are described from the Liverpool Plains at Yarramanbah Creek and Round Island, where a thick sequence of smectite clay overlies sands and gravels. The image clearly identifies zones of high salt content in the clay which have been sampled and logged using borehole measurements of electrical conductivity. Results are also described from a dryland salinity area in the upper part of Dicks Creek catchment on the Southern Tablelands of New South Wales. These data show the extent of clay overlying bedrock and correlate very well with the results of 1 : 5 extract analysis from shallow piezometers along the profile line. Electrical imaging is an appropriate follow-up method for the investigation of electrical conductivity anomalies first identified by EM profiling and is advisable before drilling at a site to optimise the location of piezometers.

scholarly journals A 2D Magneto-Acousto-Electrical Tomography Method to Detect Conductivity Variation Using Multifocus Image Method

Sensors ◽  
2018 ◽  
Vol 18 (7) ◽  
pp. 2373 ◽  
Author(s):  
Ming Dai ◽  
Xin Chen ◽  
Tong Sun ◽  
Lingyao Yu ◽  
Mian Chen ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Chirp Pulse ◽  
Image Method ◽  
Electrical Tomography ◽  
Conductivity Distribution ◽  
Conductivity Variation ◽  
Shaped Hole ◽  
Imaging Resolution ◽  
Single Focus ◽  
Pulse Stimulation

As magneto-acoustic-electrical tomography (MAET) combines the merits of high contrast and high imaging resolution, and is extremely useful for electrical conductivity measurement, so it is expected to be a promising medical imaging modalities for diagnosis of early-stage cancer. Based on the Verasonics system and the MC600 displacement platform, we designed and implemented a MAET system with a chirp pulse stimulation (MAET-CPS) method and a focal probe was utilized for stepscan focus excitation to enhance the imaging resolution. The relevant experiments were conducted to explore the influence of excitation positions of the single-focus point, and the effect of the excitation position on the amplitudes of the conductivity variation was clearly demonstrated. In order to take advantage of the merits of multifocus imaging, we firstly proposed a single focus MAET system with a chirp pulse stimulation (sfMAET-CPS) method and a multifocus MAET system with a chirp pulse stimulation (mfMAET-CPS) method for high-resolution conductivity imaging, and a homogenous gelatin phantom with a cuboid-shaped hole was used to investigate the accuracy of mfMAET-CPS. Comparative experiments were carried out on the same uniform phantom by the sfMAET-CPS and the mfMAET-CPS, respectively. The results showed that: (1) the electrical conductivity distributions of the homogenous phantom with a cuboid-shaped hole were detected by the sfMAET-CPS but were easily affected by the focal point, which demonstrated that the sfMAET-CPS had a low imaging resolution. (2) Compared with the sfMAET-CPS, the imaging effect of the mfMAET-CPS was much better than that of the sfMAET-CPS. (3) A linear interpolation algorithm was used to process the 2D conductivity distribution; it increased the smoothness of the conductivity distribution and improved the imaging effect. The stepscan focus excitation and the linearly frequency-modulated theory provide an alternative scheme for the clinical application of MAET.

Apparent electrical conductivity (ECa) as a surrogate for neutron probe counts to measure soil moisture content in heavy clay soils (Vertosols)

Soil Research ◽  
2014 ◽  
Vol 52 (4) ◽  
pp. 373 ◽  
Author(s):  
John N. Stanley ◽  
David W. Lamb ◽  
Gregory Falzon ◽  
Derek A. Schneider
Keyword(s):  
Electrical Conductivity ◽  
Soil Surface ◽  
Field Capacity ◽  
Wetting Front ◽  
Site Specific ◽  
Neutron Probe ◽  
South Wales ◽  
Moisture Extraction ◽  
Apparent Electrical Conductivity ◽  
A Site

Site-specific measurements of the apparent electrical conductivity (ECa) of soil using the EM38 were correlated with near-simultaneous neutron probe readings over periods of moisture extraction by an irrigated cotton crop. Thirty sites were monitored from three ECa zones within a 96-ha field of grey Vertosol soil 30 km west of Moree, New South Wales, Australia. This study differs from previous approaches by reporting the effect on ECa of a wetting front (irrigation) reaching a single ECa measurement point in a field and by using polyethylene neutron probe access tubes so that the EM38 could be operated directly over the same site measured by a neutron probe. We report strong correlations (r = 0.94) between neutron probe counts (CRR) averaged to a depth of 40 or 60 cm and ECa from an EM38 held in the vertical mode 20 cm above the soil surface. All combinations of EM sensor height (0–1.2 m) to neutron probe measurement depth (0.2–1.4 m) returned correlations >0.85. The relationship between CCR and ECa was linear for the purposes of estimating water content over a range of background ECa levels. More critical modelling suggested a slight curve (logarithmic model) fitted best. The range of surface-surveyed ECa from the start of irrigation (refill point) to fully irrigated (full point) was ~27 mS m–1 for this Vertosol, where surface ECa readings typically ranged from 50 to 200 mS m–1. We suggest that the calibration of ECa to CRR might be effected by a two-point measurement of the soil, namely at both upper (field capacity) and lower (wilting point) ECa values, and a site-specific calibration template generated by extending these point measures to whole-field surveys.

scholarly journals Bioremediation of polluted soil due to tsunami by using recycled waste glass

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
M. Azizul Moqsud
Keyword(s):  
Heavy Metals ◽  
Electrical Conductivity ◽  
Laboratory Experiments ◽  
Saline Soil ◽  
Salt Content ◽  
Tohoku Earthquake ◽  
Polluted Soil ◽  
Waste Glass ◽  
Excess Cost ◽  
Recycled Waste

AbstractIn this research, bioremediation of tsunami-affected polluted soil has been conducted by using collective microorganisms and recycled waste glass. The Tohoku earthquake, which was a mega earthquake in Japan triggered a huge tsunami on March 11th, 2011 that caused immeasurable damage to the geo-environmental conditions by polluting the soil with heavy metals and excessive salt content. Traditional methods to clean this polluted soil was not possible due to the excess cost and efforts. Laboratory experiments were conducted to examine the capability of bioremediation of saline soil by using recycled waste glass. Different collective microorganisms which were incubated inside the laboratory were used. The electrical conductivity (EC) was measured at different specified depths. It was noticed that the electrical conductivity decreased with the assist of the microbial metabolisms significantly. Collective microorganisms (CM2) were the highly capable to reduce salinity (up to 75%) while using recycled waste glass as their habitat.

Shallow Magnetic Induction Measurements for Delineating Near-Surface Hot Groundwater Sources in Alaskan Geothermal Areas

1983 ◽  
Vol 105 (2) ◽  
pp. 156-161 ◽  
Author(s):  
T. E. Osterkamp ◽  
K. Kawasaki ◽  
J. P. Gosink
Keyword(s):  
Electrical Conductivity ◽  
Magnetic Induction ◽  
Hot Springs ◽  
Measured Temperature ◽  
Conductivity Data ◽  
Induction Method ◽  
Near Surface ◽  
Saline Groundwater ◽  
Geophysical Surveys ◽  
Conductivity Anomalies

Variations in the electrical conductivity of a soil and water system with temperature and salt concentration suggest that a soil containing hot and/or saline groundwater may be expected to have a higher conductivity compared to a cooler and/or less saline system. Temperature and conductivity surveys were carried out at Pilgrim Springs, on the Seward Peninsula, and at Chena Hot Springs, near Fairbanks, to test the use of a magnetic induction method (which measures electrical conductivity) for delineating near-surface hot groundwater sources in geothermal areas surrounded by permafrost. Comparison of the temperature data and conductivity data from these surveys demonstrates that the conductivity anomalies, as measured by the magnetic induction method, can be used to define the precise location of hot groundwater sources in these geothermal areas with the higher temperatures correlating with higher values of conductivity. Magnetic induction measurements of conductivity can also be used to define the lateral extent of the thawed geothermal areas (used for calculating the stored energy) in permafrost terrain. The utility of these magnetic induction measurements of conductivity for reconnaissance geophysical surveys of geothermal areas is that a much greater density of data can be obtained in a shorter time in comparison with shallow temperature measurements. In addition, it is simpler, cheaper and easier (physically) to obtain the data. While conductivity anomalies can result from other than hot and/or saline groundwater, these conductivity data, when coupled with a few measured temperature profiles and groundwater samples, should result in reliable reconnaissance level geophysical surveys in Alaskan geothermal areas.

Electrical conductivity anomalies in the earth

1978 ◽  
Vol 3 (3) ◽  
pp. 225-253 ◽  
Author(s):  
Yoshimori Honkura
Keyword(s):  
Electrical Conductivity ◽  
The Earth ◽  
Conductivity Anomalies
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