Friday, June 1, 2012
Monday, March 19, 2012
ELECTRICAL POTENTIAL (Self-Potential) MEASUREMENTS with LandMapper ERM-02
The self-potential (SP) method was used by Fox as early as 1830 on sulphide veins in a Cornish mine, but the systematic use of the SP and electrical resistivity methods in conventional geophysics dates from about 1920 (Parasnis, 1997). The SP method is based on measuring the natural potential differences, which generally exist between any two points on the ground. These potentials are associated with electrical currents in the soil. Large potentials are generally observed over sulphide and graphite ore bodies, graphitic shale, magnetite, galena, and other electronically highly conducting minerals (usually negative). However, SP anomalies are greatly affected by local geological and topographical conditions. These effects are considered in exploration geophysics as “noise”. The electrical potential anomalies over the highly conducting rock are usually overcome these environmental “noise”, thus, the natural electrical potentials existing in soils are usually not considered in conventional geophysics.
LandMapper ERM-02, equipped with proper non-polarizing electrodes, can be used to measure such “noise” electrical potentials created in soils due to soil-forming process and water/ion movements. The electrical potentials in soils, clays, marls, and other water-saturated and unsaturated sediments can be explained by such phenomena as ionic layers, electro-filtration, pH differences, and electro-osmosis.
Another possible environmental and engineering application of self-potential method is to study subsurface water movement. Measurements of electro-filtration potentials or streaming potentials have been used in USSR to detect water leakage spots on the submerged slopes of earth dams (Semenov, 1980). The application of self-potential method to outline water fluxes in shallow subsurface of urban soils is described in (Pozdnyakova et al., 2001). The detail description of self-potential method procedure is provided in this manual.
Another important application of LandMapper ERM-02 is measuring electrical potentials between soils and plants. Electrical balance between soil and plants is important for plant health and electrical potential gradient governs water and nutrient uptake by plants. Monitoring of electrical potentials in plants and soils is a cutting-edge research topic in the leading scientific centers around the world.
2. Choose the reference electrode and put in the presumable area of low electrical potential, usually wettest and clay-rich areas. For example, for measuring electrical potential difference in soil pits, put reference electrode in the lowest layer of subsoil. When measuring potential difference between soils and plants, it is advised to put reference electrode on soil surface and the measuring electrodes on the leaves or trunk of growing plants.
3. Holding down the FUNCTION key (►) press the DOWN (▼) key to enter the potential mode. The display should read:
Umn = - -.— mV
where –.—is value of potential in mV
4. Slightly press flat measuring surface of the electrodes to the selected locations and observe the display.
5. The actual value of electrical potential between the electrodes is shown in mV. The device automatically takes a reading every second, takes 10 readings and outputs average value every 10 sec (natural potentials will fluctuate). This data cannot be saved in the RAM of LandMapper during field measurements if device is used as stand-alone (without PC). However, if LandMapper is connected to PC during measurements, the values of potentials are displayed on the PC screen and can be saved on PC directly (Note: software to automatically direct measurements from computer is under development). You can manually
record as many readings at the same location as you like.
with electrical fields of a various nature, arising directly in soil profiles (Semenov, 1980). The potentials originated in soil profiles are divided into diffusion-adsorption potentials, electrode potentials, and potentials of “varying in time fields" (Semenov, 1980). The “geological” potentials are limited to certain natural conditions, such as sharp change of oxidation-reduction conditions above an ore deposit or perched mineralized groundwater. The natural “soil” electrical potentials, on the contrary, can form under any soil condition.
All the natural electrical fields can be classified by mechanisms and nature of their occurrence in two large groups: electrical fields of stationary processes, existing on the contacts of various media and electrical fields, arising in saturated and unsaturated soils due to movement of soil solutions. The most widespread electrical fields in soils are attributable to diffusion-adsorption potentials, in which sorption accounts for more essential contribution than diffusion. The natural electrical fields are measured together with electrode potentials, which can be considered as artificially created potentials on the contacts of electrodes with soil.
Natural electrical fields and their potentials were studied in some soils in Russia (Borovinskaya, 1970; Vadunina, 1979; Pozdnyakov et al., 1996a). Vadunina (1979) pointed out that potentials measured on the soil surface could be used to estimate different soil properties in the whole soil profile. The measurements of natural potentials on the surface of some Aridisols (including Natrargids) and Alfisols (Pozdnyakov et al., 1996a) show that such estimation is possible only when the surface soil horizons are genetically related to the other horizons in the soil profile.
We consider soil electrical potentials as diffusion-adsorption potentials on the contacts of different soil structures, such as soil aggregates, horizons, and pedons in topographic sequences. This concept, based on Poisson’s and Maxwell’s laws of electromagnetism and Boltzmann’s distribution law of statistical thermodynamics, was used to explain relationships among various soil properties, mobile electrical charges, and electrical parameters. The theory considers soil cover as a huge "source" generating natural electrical fields and allows constructing models of electrical profiles in various soils.
Method of self-potential (SP) measures the naturally existed stationary electrical potentials in the soil. The SP method was used by Fox as early as 1830 on sulphide veins in a Cornish mine, but the systematic use of the SP and electrical resistivity methods in conventional geophysics dates from about 1920 (Parasnis, 1997). The SP method is based on measuring the natural potential differences, which generally exist between any two points on the ground. These potentials are associated with electrical currents in the soil. Large potentials are generally observed over sulphide and graphite ore bodies, graphitic shale, magnetite, galena, and other electronically highly conducting minerals (usually negative). However, SP anomalies are greatly affected by local geological and topographical conditions. These effects are considered in exploration geophysics as “noise”. The electrical potential anomalies over the highly conducting rock are usually overcome these environmental “noise”, thus, the natural electrical potentials existing in soils are usually not considered in conventional geophysics.
In soil studies researchers are especially interested in the measurement of such “noise” electrical potentials created in soils due to soil-forming process and water/ion movements. The electrical potentials in soils, clays, marls, and other water-saturated and unsaturated sediments can be explained by such phenomena as ionic layers, electro-filtration, pH differences, and electro-osmosis. Soil-forming processes can create electrically variable horizons in soil profiles.
Another possible environmental and engineering application of self-potential method is to study subsurface water movement. Measurements of electro-filtration potentials or streaming potentials have been used in USSR to detect water leakage spots on the submerged slopes of earth dams (Semenov, 1980). The application of self-potential method to outline water fluxes in shallow subsurface of urban soils is described in (Pozdnyakova et al., 2001).
Potentials generated by subsurface environmental sources are lower than those induced by mineral and geothermal anomalies and often associated with high noise polarization level (Corwin, 1990). Therefore, the usage of non-polarizing electrodes is mandatory when the SP method is applied in soil and environmental studies. The non-polarizing electrode consists of a metal element immersed in a solution of salt of the same metal with a porous membrane between the solution and the soil (Corwin and Butler, 1989). Because of easy breakage of the membrane and leakage of the electrode solution we adopted firm non-polarizing electrodes (carbon cores from the exhausted electrical cells) and also developed and patented non-polarizing electrodes for soil studies (Pozdnyakov, 2001).
The SP method utilizes two electrodes (trailing and leading), a potentiometer, and connecting wire. Two measuring techniques, fixed-base (or total field) and gradient (or leapfrog), are suggested in conventional geophysics (Fig. 1).
Fig. 1. Scheme of self-potential method with (a) fixed-base, (b) gradient, and (c) combined techniques. Crosses indicate leading (measuring) electrode locations and circles show trailing (base) electrode locations.
We used the fixed-base technique to obtain distributions of electrical potentials in soil profiles. Measurements were conducted on the walls of open soil pits. The base or trailing electrode was permanently installed in the place of high potential, usually in illuvial, wet, fine-textured, or salty soil horizon. The difference of electrical potential between the base and leading (measuring) electrodes was measured by the consequent movement of the leading electrode along the soil profile (Fig. 1a).
The gradient technique is applied in conventional geophysics when information about the electrical potential distribution within a large area is required. In such case extensive amount of wires is needed if the fixed-base method is used. The gradient technique allows reducing the amount of wires necessary for the mapping of electrical potentials on soil surface (Corwin, 1990). The technique is based on the consequent movement of the base electrode; thus, for every measurement it takes the previous location of the trailing electrode as shown in Fig. 1b. Despite the advantage in reduction of required wires, the gradient technique introduces large errors related to different polarization of the base electrode at different ground locations. For soil investigations with small natural electrical potentials and high potential variation such errors can be critical. Therefore, for mapping of natural electrical potentials on the soil surface we propose a combination of the fixed-base (or total field) and gradient (or leapfrog) measurement procedures. The combined procedure reduces errors associated with varied electrode polarization at different locations in the gradient method and minimizes length of wires necessary for the fixed-base method. The procedure is described as follows (Fig. 1c). The trailing electrode is first installed in a place with the relatively high potential, for example, in a wet clay layer on the soil surface or in an illuvial horizon of a soil profile. The leading electrode is placed on the soil surface at any desired location. The potential differences between the leading and trailing electrodes are measured in nearby locations by moving the leading electrode. Then the trailing electrode is moved to one of the previous locations of the leading electrode and the potential differences are measured around the new location of the trailing electrode. The procedure is repeated until the electrical potential is measured in all desirable locations with a sufficient replication. All the potential differences are recalculated as if they were measured with the only moving leading electrode and the trailing electrode fixed the first location, i.e. standardized by potential at the first location of the trailing electrode. The data obtained with the SP method are incorporated to develop iso-potential maps of the measured areas.
References
Borovinskaya, L.B. 1970. Application of self-potential method to study filtration in soils and grounds. (In Russian.) Rus. Soil Sci. 11:113-121.
Corwin, R.F. 1990. The self-potential method for environmental and engineering applications. In: S.H. Ward (ed). Geotechnical and environmental geophysics. Vol. I: Review and tutorial. Soc. of Exploration Geophysics. P.O. Box 702740/Tulsa, OH 74170-2740.
Corwin, R.F., and D.K. Butler. 1989. Geotechnical applications of the self-potential method; Rept 3: Development of self-potential interpretation techniques for seepage detection: Tech. Rep. REMR-GT-6, U.S. Army Corps of Engineers, Washington DC.
Parasnis, D.S. 1997. Principles of applied geophysics. Chapman & Hall, 2-6 Boundary Row, London SE1 8HN, UK.
Pozdnyakov, A.I. 2001. Polevaya electrofizika pochv (Field Soil Electrophysics). MAIK "Nauka-Interpereodika", Moscow. 1-278 (in Russian).
Pozdnyakov, A.I, L.A. Pozdnyakova, and A.D. Pozdnyakova. 1996a. Stationary electrical fields in soils (in Russian with English summary). KMK Scientific Press, Moscow, Russia. 1-358.
Pozdnyakova, L., A. Pozdnyakov, and R. Zhang. 2001. Application of geophysical methods to evaluate hydrology and soil properties in urban areas. London, UK, Urban Water 3:205-216 – included on enclosed CD
Semenov, A.S. 1980. Electroexploration with method of natural electrical field (self-potential). (In Russian.). Nedra. Leningrad. Russia.
Vadunina, A.F. 1979. Electroreclamation of saline soils. (In Russian.). Moscow Univ. Press. Moscow.
LandMapper ERM-02, equipped with proper non-polarizing electrodes, can be used to measure such “noise” electrical potentials created in soils due to soil-forming process and water/ion movements. The electrical potentials in soils, clays, marls, and other water-saturated and unsaturated sediments can be explained by such phenomena as ionic layers, electro-filtration, pH differences, and electro-osmosis.
Another possible environmental and engineering application of self-potential method is to study subsurface water movement. Measurements of electro-filtration potentials or streaming potentials have been used in USSR to detect water leakage spots on the submerged slopes of earth dams (Semenov, 1980). The application of self-potential method to outline water fluxes in shallow subsurface of urban soils is described in (Pozdnyakova et al., 2001). The detail description of self-potential method procedure is provided in this manual.
Another important application of LandMapper ERM-02 is measuring electrical potentials between soils and plants. Electrical balance between soil and plants is important for plant health and electrical potential gradient governs water and nutrient uptake by plants. Monitoring of electrical potentials in plants and soils is a cutting-edge research topic in the leading scientific centers around the world.
Measuring potential
1. Connect non-polarizing electrodes to MN socket on the front panel of the device.
2. Choose the reference electrode and put in the presumable area of low electrical potential, usually wettest and clay-rich areas. For example, for measuring electrical potential difference in soil pits, put reference electrode in the lowest layer of subsoil. When measuring potential difference between soils and plants, it is advised to put reference electrode on soil surface and the measuring electrodes on the leaves or trunk of growing plants.
3. Holding down the FUNCTION key (►) press the DOWN (▼) key to enter the potential mode. The display should read:
Umn = - -.— mV
where –.—is value of potential in mV
4. Slightly press flat measuring surface of the electrodes to the selected locations and observe the display.5. The actual value of electrical potential between the electrodes is shown in mV. The device automatically takes a reading every second, takes 10 readings and outputs average value every 10 sec (natural potentials will fluctuate). This data cannot be saved in the RAM of LandMapper during field measurements if device is used as stand-alone (without PC). However, if LandMapper is connected to PC during measurements, the values of potentials are displayed on the PC screen and can be saved on PC directly (Note: software to automatically direct measurements from computer is under development). You can manually
record as many readings at the same location as you like.
Method of Self-Potential
Many kinds of electrical fields and potentials are often simultaneously observed in natural soil; thus, it is difficult to know what mechanism is responsible for their formation. Stationary electrical fields originated in deep geological formations can be observed in soils togetherwith electrical fields of a various nature, arising directly in soil profiles (Semenov, 1980). The potentials originated in soil profiles are divided into diffusion-adsorption potentials, electrode potentials, and potentials of “varying in time fields" (Semenov, 1980). The “geological” potentials are limited to certain natural conditions, such as sharp change of oxidation-reduction conditions above an ore deposit or perched mineralized groundwater. The natural “soil” electrical potentials, on the contrary, can form under any soil condition.
All the natural electrical fields can be classified by mechanisms and nature of their occurrence in two large groups: electrical fields of stationary processes, existing on the contacts of various media and electrical fields, arising in saturated and unsaturated soils due to movement of soil solutions. The most widespread electrical fields in soils are attributable to diffusion-adsorption potentials, in which sorption accounts for more essential contribution than diffusion. The natural electrical fields are measured together with electrode potentials, which can be considered as artificially created potentials on the contacts of electrodes with soil.
Natural electrical fields and their potentials were studied in some soils in Russia (Borovinskaya, 1970; Vadunina, 1979; Pozdnyakov et al., 1996a). Vadunina (1979) pointed out that potentials measured on the soil surface could be used to estimate different soil properties in the whole soil profile. The measurements of natural potentials on the surface of some Aridisols (including Natrargids) and Alfisols (Pozdnyakov et al., 1996a) show that such estimation is possible only when the surface soil horizons are genetically related to the other horizons in the soil profile.
We consider soil electrical potentials as diffusion-adsorption potentials on the contacts of different soil structures, such as soil aggregates, horizons, and pedons in topographic sequences. This concept, based on Poisson’s and Maxwell’s laws of electromagnetism and Boltzmann’s distribution law of statistical thermodynamics, was used to explain relationships among various soil properties, mobile electrical charges, and electrical parameters. The theory considers soil cover as a huge "source" generating natural electrical fields and allows constructing models of electrical profiles in various soils.
Method of self-potential (SP) measures the naturally existed stationary electrical potentials in the soil. The SP method was used by Fox as early as 1830 on sulphide veins in a Cornish mine, but the systematic use of the SP and electrical resistivity methods in conventional geophysics dates from about 1920 (Parasnis, 1997). The SP method is based on measuring the natural potential differences, which generally exist between any two points on the ground. These potentials are associated with electrical currents in the soil. Large potentials are generally observed over sulphide and graphite ore bodies, graphitic shale, magnetite, galena, and other electronically highly conducting minerals (usually negative). However, SP anomalies are greatly affected by local geological and topographical conditions. These effects are considered in exploration geophysics as “noise”. The electrical potential anomalies over the highly conducting rock are usually overcome these environmental “noise”, thus, the natural electrical potentials existing in soils are usually not considered in conventional geophysics.
In soil studies researchers are especially interested in the measurement of such “noise” electrical potentials created in soils due to soil-forming process and water/ion movements. The electrical potentials in soils, clays, marls, and other water-saturated and unsaturated sediments can be explained by such phenomena as ionic layers, electro-filtration, pH differences, and electro-osmosis. Soil-forming processes can create electrically variable horizons in soil profiles.
Another possible environmental and engineering application of self-potential method is to study subsurface water movement. Measurements of electro-filtration potentials or streaming potentials have been used in USSR to detect water leakage spots on the submerged slopes of earth dams (Semenov, 1980). The application of self-potential method to outline water fluxes in shallow subsurface of urban soils is described in (Pozdnyakova et al., 2001).
Potentials generated by subsurface environmental sources are lower than those induced by mineral and geothermal anomalies and often associated with high noise polarization level (Corwin, 1990). Therefore, the usage of non-polarizing electrodes is mandatory when the SP method is applied in soil and environmental studies. The non-polarizing electrode consists of a metal element immersed in a solution of salt of the same metal with a porous membrane between the solution and the soil (Corwin and Butler, 1989). Because of easy breakage of the membrane and leakage of the electrode solution we adopted firm non-polarizing electrodes (carbon cores from the exhausted electrical cells) and also developed and patented non-polarizing electrodes for soil studies (Pozdnyakov, 2001).
The SP method utilizes two electrodes (trailing and leading), a potentiometer, and connecting wire. Two measuring techniques, fixed-base (or total field) and gradient (or leapfrog), are suggested in conventional geophysics (Fig. 1).
Fig. 1. Scheme of self-potential method with (a) fixed-base, (b) gradient, and (c) combined techniques. Crosses indicate leading (measuring) electrode locations and circles show trailing (base) electrode locations.
We used the fixed-base technique to obtain distributions of electrical potentials in soil profiles. Measurements were conducted on the walls of open soil pits. The base or trailing electrode was permanently installed in the place of high potential, usually in illuvial, wet, fine-textured, or salty soil horizon. The difference of electrical potential between the base and leading (measuring) electrodes was measured by the consequent movement of the leading electrode along the soil profile (Fig. 1a).
The gradient technique is applied in conventional geophysics when information about the electrical potential distribution within a large area is required. In such case extensive amount of wires is needed if the fixed-base method is used. The gradient technique allows reducing the amount of wires necessary for the mapping of electrical potentials on soil surface (Corwin, 1990). The technique is based on the consequent movement of the base electrode; thus, for every measurement it takes the previous location of the trailing electrode as shown in Fig. 1b. Despite the advantage in reduction of required wires, the gradient technique introduces large errors related to different polarization of the base electrode at different ground locations. For soil investigations with small natural electrical potentials and high potential variation such errors can be critical. Therefore, for mapping of natural electrical potentials on the soil surface we propose a combination of the fixed-base (or total field) and gradient (or leapfrog) measurement procedures. The combined procedure reduces errors associated with varied electrode polarization at different locations in the gradient method and minimizes length of wires necessary for the fixed-base method. The procedure is described as follows (Fig. 1c). The trailing electrode is first installed in a place with the relatively high potential, for example, in a wet clay layer on the soil surface or in an illuvial horizon of a soil profile. The leading electrode is placed on the soil surface at any desired location. The potential differences between the leading and trailing electrodes are measured in nearby locations by moving the leading electrode. Then the trailing electrode is moved to one of the previous locations of the leading electrode and the potential differences are measured around the new location of the trailing electrode. The procedure is repeated until the electrical potential is measured in all desirable locations with a sufficient replication. All the potential differences are recalculated as if they were measured with the only moving leading electrode and the trailing electrode fixed the first location, i.e. standardized by potential at the first location of the trailing electrode. The data obtained with the SP method are incorporated to develop iso-potential maps of the measured areas.
References
Borovinskaya, L.B. 1970. Application of self-potential method to study filtration in soils and grounds. (In Russian.) Rus. Soil Sci. 11:113-121.
Corwin, R.F. 1990. The self-potential method for environmental and engineering applications. In: S.H. Ward (ed). Geotechnical and environmental geophysics. Vol. I: Review and tutorial. Soc. of Exploration Geophysics. P.O. Box 702740/Tulsa, OH 74170-2740.
Corwin, R.F., and D.K. Butler. 1989. Geotechnical applications of the self-potential method; Rept 3: Development of self-potential interpretation techniques for seepage detection: Tech. Rep. REMR-GT-6, U.S. Army Corps of Engineers, Washington DC.
Parasnis, D.S. 1997. Principles of applied geophysics. Chapman & Hall, 2-6 Boundary Row, London SE1 8HN, UK.
Pozdnyakov, A.I. 2001. Polevaya electrofizika pochv (Field Soil Electrophysics). MAIK "Nauka-Interpereodika", Moscow. 1-278 (in Russian).
Pozdnyakov, A.I, L.A. Pozdnyakova, and A.D. Pozdnyakova. 1996a. Stationary electrical fields in soils (in Russian with English summary). KMK Scientific Press, Moscow, Russia. 1-358.
Pozdnyakova, L., A. Pozdnyakov, and R. Zhang. 2001. Application of geophysical methods to evaluate hydrology and soil properties in urban areas. London, UK, Urban Water 3:205-216 – included on enclosed CD
Semenov, A.S. 1980. Electroexploration with method of natural electrical field (self-potential). (In Russian.). Nedra. Leningrad. Russia.
Vadunina, A.F. 1979. Electroreclamation of saline soils. (In Russian.). Moscow Univ. Press. Moscow.
Thursday, January 12, 2012
Internet Explorer - Cleaning Cache
Sometimes web applications cannot reach underlying database and report errors or just freeze browser permanently. 
Re-starting browser sometimes solve this problem, but not always. Problem can be solved by clearing browser cache. This article explain how to do so in Internet Explorer.
Go to “Tools” / “Internet Options”.
In “Internet Options” on “General” Tab, make sure that “Delete browsing history on exit” is Checked, to prevent future problems.
Hit “Delete” button.
On the next screen: check “Temporary Internet files”. Click “Delete”.
Then in previous screen hit "Apply" and "OK".
![clip_image002[1]](http://lh3.ggpht.com/-X059zQDs8lQ/Tw9GaPfn89I/AAAAAAAAAg8/RTvbgt8y_D8/s1600-h/clip_image002%25255B1%25255D%25255B3%25255D.png "clip_image002[1]")
Re-start your browser and navigate back to the page that was causing problems. If you still having problems, post a comment below.
Friday, November 18, 2011
Landviser’s on-line store is being re-created
Our on-line store is being re-created. Meanwhile, you can still place orders for LandMappers ERM-01/ ERM-02 and accessories, GIS consulting, or geophysical software RES2DINV / RES3DINV. Download our Catalog or contact us for personal quote. We ship worldwide and accept PayPal, VISA/MC and wire-transfers to our US bank account.
| More information about our products and services: Main web: www.landviser.com Store: www.landviser.biz Toll-free (USA/Canada): 888-306-LAND (5263) Phone (International): +1-609-412-0555 Blog: http://landviser.blogspot.com LinkedIn: http://www.linkedin.com/in/larisagolovko Fax: +1-815-301-8955 | Landviser develops innovative non-invasive technologies (hand-held equipment and software) for mapping and monitoring core biosphere components: soils, plants and groundwater. We provide custom research system integration and consulting on electrical geophysics applications in agricultural and environmental sciences; GIS; geostatistics; and remote sensing. Depending on your project we can assist with equipment/software procurement and develop training courses in geophysical equipment (ERM-02 and ABEM) and software (GIS, seismic and resistivity imaging). We are an international consulting company with headquarters in Texas, USA and business contacts in Canada, Russia, Malaysia, Philippines, Middle East, China and South America. Please, do not hesitate to contact me, Larisa Golovko (Pozdnyakova) - info@landviser.com |
LandMapper ERM-01 is a hand-held resistivity meter which accepts Wenner (as well as any other four-electrode arrays, dipole-dipole or square ones f.e.). It can sense down to 15 meters in most soils. You can use hyperlinks to download our publications about LandMapper and popular geophysical freeware/shareware. LandMapper ERM-02 measures electrical resistivity (ER), electrical conductivity (EC) and natural electrical potential (EP) from soil surface down to 25 m depth as well as in soil pits, pots, samples, pastes and water solutions. Don't let the small size fool you - LandMapper ERM-02 measures electrical parameters in a widest range possible (from ultra-pure water and rocks to ocean waters) with the accuracy comparable to the standard devices used in electrical geophysical prospecting, like ABEM, Syscal, etc, but weights and costs TEN times less!
The applications of LandMapper are not limited to soils but can be extended to any semisolid media and even live plants! Download new LandMapper ERM-02 brochure or complete manual.
We now have limited quantities of both models in stock - basic ERM-01 with resistivity mode only for $1,579 (sug. retail) and ERM-02 (resistivity, conductivity, and self-potential) for $2,437 (sug. retail). Probes and arrays can be easily constructed from common hardware, but we can build probes to your specs for very reasonable price and can provide other accessories.
Note, that we also offer dealers' and academia discounts on equipment and software!
Thursday, November 10, 2011
Our popular LandMapper devices are back in stock!
LandMapper ERM-01 is a hand-held resistivity meter that can accept Wenner (as well as any other four-electrode
configuration, dipole-dipole or square ones f.e.). It can sense down to 15 meters in most soils. You can use hyperlinks to download our publications about LandMapper and popular geophysical freeware/shareware.
LandMapper ERM-02 measures electrical resistivity (ER), electrical conductivity (EC) and natural electrical potential (EP) from soil surface down to 25 m depth as well as in soil pits, pots, samples, pastes and water solutions. Don't let the small size fool you - LandMapper ERM-02 measures electrical parameters in a widest range possible (from ultra-pure water and rocks to ocean waters) with the accuracy comparable to the standard devices used in electrical geophysical prospecting, like ABEM, Syscal, etc, but weights and costs TEN times less!
The applications of LandMapper are not limited to soils but can be extended to any semisolid media and even live plants! Download new LandMapper ERM-02 brochure or complete manual.
We now have limited quantities of both models in stock - basic ERM-01 with resistivity mode only for $1,579 (sug. retail) and ERM-02 (resistivity, conductivity, and self-potential) for $2,437 (sug. retail). Probes and arrays can be easily constructed from common hardware, but we can build probes to your specs for very reasonable price and can provide other accessories. 
Note, that we also offer dealers' and academia discounts!
We ship worldwide and accept PayPal, VISA/MC and wire-transfers to our US bank account. Customers from USA may also pay with Purchase Order. Landviser, LLC is US government vendor and service provider and is registered in CCR.
Please, inquire early to insure device availability for your intended research project! Do not hesitate to contact me to discuss suitability of our equipment for YOUR applications. We at Landviser, LLC are always "enlightening research" for you!
Best,
Larisa Golovko (Pozdnyakova), Ph.D. (thesis "Electrical properties of soils")
Thursday, February 10, 2011
LandMapper ERM-02: Handheld Meter for Near-Surface Electrical Geophysical Surveys
was just published in
Golovko L, Pozdnyakov A, Pozdnyakova A (2010) LandMapper ERM-02: Handheld Meter for Near-Surface Electrical Geophysical Surveys. FastTIMES (EEGS) 15: 85-93. http://www.eegs.org/Publications/FASTTIMES.aspx Accessed 6 June 2011
Abstract On-the-go sensors, designed to measure soil electrical resistivity (ER) or electrical conductivity (EC) are vital for faster non-destructive soil mapping in precision agriculture, civi
l and environmental engineering, archaeology and other near-surface applications. Compared with electromagnetic methods and ground penetrating radar, methods of EC/ER measured with direct current and a four-electrode probe have fewer limitations and were successfully applied on clayish and saline soils as well as on highly resistive sandy soils, such as Alfisols and Spodosols. However, commercially available contact devices, which utilize a four-electrode principle, are bulky, very expensive, and can be used only on fallow fields. Multi-electrode ER-imaging systems applied in deep geophysical explorations are heavy, cumbersome and their use is usually cost-prohibited in many near-surface applications, such as forestry, archaeology, environmental site assessment and cleanup, and in agricultural surveys on farms growing perennial horticultural crops, vegetables, or turf-grass. In such applications there is a need for an accurate, portable, low-cost device to quickly check resistivity of the ground on-a-spot, especially on the sites non-accessible to heavy machinery.
Here are direct links to full issue of FastTIMES on EEGS website
low resolution http://www.eegs.org/Portals/2/FastTimeFiles/ft1504_Dec2010_low_r02.pdf
high resolution http://www.eegs.org/Portals/2/FastTimeFiles/ft1504_Dec2010_high_r02.pdf
Permanent link to just LandMapper article on Landviser's website http://landviser.net/webfm_send/69
Also look for this and other relevant references in our free-access public library “Soil Electrical Geophysics” http://www.landviser.net/content/soil-electrical-geophysics-public-library-zotero
Golovko L, Pozdnyakov A, Pozdnyakova A (2010) LandMapper ERM-02: Handheld Meter for Near-Surface Electrical Geophysical Surveys. FastTIMES (EEGS) 15: 85-93. http://www.eegs.org/Publications/FASTTIMES.aspx Accessed 6 June 2011
Abstract On-the-go sensors, designed to measure soil electrical resistivity (ER) or electrical conductivity (EC) are vital for faster non-destructive soil mapping in precision agriculture, civi
l and environmental engineering, archaeology and other near-surface applications. Compared with electromagnetic methods and ground penetrating radar, methods of EC/ER measured with direct current and a four-electrode probe have fewer limitations and were successfully applied on clayish and saline soils as well as on highly resistive sandy soils, such as Alfisols and Spodosols. However, commercially available contact devices, which utilize a four-electrode principle, are bulky, very expensive, and can be used only on fallow fields. Multi-electrode ER-imaging systems applied in deep geophysical explorations are heavy, cumbersome and their use is usually cost-prohibited in many near-surface applications, such as forestry, archaeology, environmental site assessment and cleanup, and in agricultural surveys on farms growing perennial horticultural crops, vegetables, or turf-grass. In such applications there is a need for an accurate, portable, low-cost device to quickly check resistivity of the ground on-a-spot, especially on the sites non-accessible to heavy machinery. Here are direct links to full issue of FastTIMES on EEGS website
low resolution http://www.eegs.org/Portals/2/FastTimeFiles/ft1504_Dec2010_low_r02.pdf
high resolution http://www.eegs.org/Portals/2/FastTimeFiles/ft1504_Dec2010_high_r02.pdf
Permanent link to just LandMapper article on Landviser's website http://landviser.net/webfm_send/69
Also look for this and other relevant references in our free-access public library “Soil Electrical Geophysics” http://www.landviser.net/content/soil-electrical-geophysics-public-library-zotero
Wednesday, February 2, 2011
Applications of LandMapper handheld for near-surface soil surveys and beyond
On-the-go sensors, designed to measure soil electrical resistivity (ER) or electrical conductivity (EC) are vital for faster non-destructive soil mapping in precision agriculture, civil and environmental engineering, archaeology and other near-surface applications. Compared with electromagnetic methods and ground penetrating radar, methods of EC/ER measured with direct current and four-electrode probe have fewer limitations and were successfully applied on clayish and saline soils as well as on highly resistive stony and sandy soils. However, commercially available contact devices, which utilize a four-electrode principle, are bulky, very expensive, and can be used only on fallow fields. Multi-electrode ER-imaging systems applied in deep geophysical explorations are heavy, cumbersome and their use is usually cost-prohibited in many near-surface applications, such as forestry, archaeology, environmental site assessment and cleanup, and in agricultural surveys on farms growing perennial horticultural crops, vegetables, or turf-grass. In such applications there is a need for accurate, portable, low-cost device to quickly check resistivity of the ground on-a-spot, especially on the sites non-accessible with heavy machinery.
The increase of the distance among four electrodes in a set allows measuring resistivity of deeper layers, f.e. probe of A2M2N2B2 reaches deeper than A1M1N1B1. In theory, electrical resistivity (ER) of a material is defined as follows: 
where L is the length of a uniform conductor with a cross-sectional area A. A/L is a geometrical coefficient (K), which is easily calculated for different in-situ electrode arrangements and laboratory conductivity cells. LandMapper® calculates electrical resistivity using formula:
. The direct digital output of the device is electrical resistivity in Ohm m. Those can be converted automatically in electrical conductivity (S/m) inside LandMapper® ERM-02 by using reciprocal of the measured resistivity: 
. Thus, the measured results may as well be presented in convenient for soil scientists form of soil electrical conductivity (EC), which is routinely used to evaluate salinity of soils and irrigation water. However, EC can be used in many more applications than just soil salinity! Also ERM-02 can output natural electrical potential (EP) of soil and plants, which has some specific applications .
1. Soil salinity
2. Soil texture (i.e. silt, sand and clay contents, working formula needs to be developed)
3. Coarse fragment content and depth to bedrock
4. Depth to limiting layers like clay and plow pan (wastewater - leaching fields)
5. Groundwater depth - capillary rise extent in profile
6. Correlations between soil EC maps and yield maps for many crops were established
7. Depth and extent of permafrost.
8. Pollution detection - depth and limits (pollution during oil and gas mining, for example)
9. Location and stability of karsts and carbonate sink holes.
10. Mapping of soil disturbance and search for hidden objects (drainage pipes, urban underground communications, forensic and archaeological applications).
11. Estimating depth of peat deposits during prospecting and locating methane accumulations in natural bogs and swamps.
13. Monitoring fertilizer uptake and other solute transport in soils (f.e. during phytoremediation)
14. Monitoring of freezing-melting processes in soil
15. Mapping and monitoring leakage from the retention ponds and sewage ponds, and underground oil storage tanks.
16. The thickness of horizons, the degree of eluviations and soil profile organization can be evaluated either without digging soil pits or by quick checking EC on the walls of soil pits.
17. Measuring of soil vertical and horizontal anisotropy non-destructively.
18. Forestry – in addition to evaluating all important soil properties of forest soils, monitoring ER of a growing tree can indicate wood quality and if plant is stressed (also electrical potential is especially useful in plant health studies as non-penetrating electrodes can be mounted on surface of herbaceous plants).
19. Evaluating and monitoring stability of the roads (seasonal, gr avel, asphalt, on permafrost or landslides, etc.).
20. Measuring integrity of underground electrical cables and pipes (and soil corrosive properties).
21. Monitoring charge-recharge processes in membrane resins in water purification plants or consumer distillers.
22. ….? Can you think of any other possible applications that can benefit if electrical conductivity/potential of a natural system could be measured quickly and non-destructively?
We at Landviser, LLC would like to hear from you! Post a comment, or email us at info@landviser.com.
Four-electrode principle of EC/ER measurements
Our equipment utilizes well-known four-electrode principle to measure electrical resistivity or conductivity, as shown in the figure. LandMapper® measures potential difference ( Dj) which arises between two electrodes (M and N), when electrical current (I) is applied to other two electrodes (A and B).
The increase of the distance among four electrodes in a set allows measuring resistivity of deeper layers, f.e. probe of A2M2N2B2 reaches deeper than A1M1N1B1. In theory, electrical resistivity (ER) of a material is defined as follows: 
where L is the length of a uniform conductor with a cross-sectional area A. A/L is a geometrical coefficient (K), which is easily calculated for different in-situ electrode arrangements and laboratory conductivity cells. LandMapper® calculates electrical resistivity using formula:
. The direct digital output of the device is electrical resistivity in Ohm m. Those can be converted automatically in electrical conductivity (S/m) inside LandMapper® ERM-02 by using reciprocal of the measured resistivity: 
. Thus, the measured results may as well be presented in convenient for soil scientists form of soil electrical conductivity (EC), which is routinely used to evaluate salinity of soils and irrigation water. However, EC can be used in many more applications than just soil salinity! Also ERM-02 can output natural electrical potential (EP) of soil and plants, which has some specific applications .Applications of EC/ER technology in soil studies
Mapping of soil properties highly influencing density of mobile electrical charges (measured EC/ER strongly correlates with those properties in-situ):1. Soil salinity
2. Soil texture (i.e. silt, sand and clay contents, working formula needs to be developed)
3. Coarse fragment content and depth to bedrock
4. Depth to limiting layers like clay and plow pan (wastewater - leaching fields)
5. Groundwater depth - capillary rise extent in profile
6. Correlations between soil EC maps and yield maps for many crops were established
7. Depth and extent of permafrost.
8. Pollution detection - depth and limits (pollution during oil and gas mining, for example)
9. Location and stability of karsts and carbonate sink holes.
10. Mapping of soil disturbance and search for hidden objects (drainage pipes, urban underground communications, forensic and archaeological applications).
11. Estimating depth of peat deposits during prospecting and locating methane accumulations in natural bogs and swamps.
Monitoring processes where only one soil properties changes:
12. Soil water content changes13. Monitoring fertilizer uptake and other solute transport in soils (f.e. during phytoremediation)
14. Monitoring of freezing-melting processes in soil
15. Mapping and monitoring leakage from the retention ponds and sewage ponds, and underground oil storage tanks.
Applications in soil genesis studies.
Many soils of humid areas developed under downward leaching and typically feature the elluvial horizon with very high resistivity.16. The thickness of horizons, the degree of eluviations and soil profile organization can be evaluated either without digging soil pits or by quick checking EC on the walls of soil pits.
17. Measuring of soil vertical and horizontal anisotropy non-destructively.
Special applications beyond soil studies:
18. Forestry – in addition to evaluating all important soil properties of forest soils, monitoring ER of a growing tree can indicate wood quality and if plant is stressed (also electrical potential is especially useful in plant health studies as non-penetrating electrodes can be mounted on surface of herbaceous plants).19. Evaluating and monitoring stability of the roads (seasonal, gr avel, asphalt, on permafrost or landslides, etc.).
20. Measuring integrity of underground electrical cables and pipes (and soil corrosive properties).
21. Monitoring charge-recharge processes in membrane resins in water purification plants or consumer distillers.
22. ….? Can you think of any other possible applications that can benefit if electrical conductivity/potential of a natural system could be measured quickly and non-destructively?
We at Landviser, LLC would like to hear from you! Post a comment, or email us at info@landviser.com.
Richard Feynman once said: “There is not a single phenomenon in Nature which is not driven by electricity to some extent. ” (quote paraphrased)
Richard Feynman (1918-88) had an enormous talent of explaining complicated scientific matters to non-scientists. Watch this short video where he admires wonders of electricity in the dentist’s waiting room – “Electricity is bigger than gravity!”
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