Search

The measurement of soil water content is a very important factor in plant cultivation, both from an economic and ecological point of view. Proper estimation of moisture content not only allows for proper yields but can also contribute to ecologically appropriate use of fresh water, of which the world's resources are limited. It is important, for example, that the moisture content in the root area of plants is optimal for their growth, while over-watering can result in losses in the form of water, which seeps below the root layer and is lost. The novel, inexpensive electronic meter for measuring soil moisture is presented in the article. The meter, based on a capacitive method, uses an optimization algorithm to calculate soil electrical permeability and a simplified new formula between soil electrical permeability and volumetric moisture content. Moreover, by using two high-frequency signals for measurements, it is possible not only to estimate moisture content but also soil conductivity. Both readings obtained from the meter not only allow for rational management of crop optimization for economic reasons but are also important for environmental protection. In addition, the inexpensive meter, based on the principle of operation presented, can be made as an IoT module, which allows for its wide application. [ABSTRACT FROM AUTHOR]

Rare earth elements (REEs) are essential raw materials for modern industries but mining them has caused severe environmental issues, particularly the recovery of heavy REEs (HREEs) from ion-adsorption deposits (IADs). Very recently, an emerging technology, electrokinetic mining (EKM), has been proposed for the green and efficient recovery of REEs from IADs. However, the conduction mechanism of the weathering crust soil, which is also a prerequisite for EKM, remains unclear, making the EKM process unpredictable. Here, we systematically investigated the conductivity of weathering crust soil in the presence of light REEs (LREEs, i.e., La3+ and Sm3+) and HREEs (Er3+ and Y3+), respectively. Results suggested that the voltage was dynamically and spatially redistributed by the movement of REEs and water during EKM, and the conventional assumption of the linear distribution of voltage leads to an inaccurate description of soil voltage. We proposed an improved Archie's equation by coupling the mechanisms of liquid phase and solid-liquid interface conduction, which can predict soil conductivity more precisely. Moreover, the extended Archie's equation is able to recalculate the voltage distribution at distinct times and spaces well during EKM. More importantly, the water content in field-scale weathered-crust soils can be retrieved by the newly proposed Archie's equation, which helps optimize the leaching wells and improve the recovery rate of REE. This study focuses on the conduction mechanism of weathering crust soil, which provides a theoretical basis for better use of the EKM technology and promotes mining efficiency fundamentally. [ABSTRACT FROM AUTHOR]

Copyright of Acta Prataculturae Sinica is the property of Acta Prataculturae Sinica Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

【Objective】 Soil salinization due to shallow groundwater table is a main abiotic stress facing agricultural production in eastern Henan province. In this paper we analyze the migration of salt in the plough layer and its relationship with geochemistry of both surface water and groundwater at different seasons. 【Method】 The experiment was conducted in areas adjacent to the National Agro-ecological System Observation and Research Station of Shangqiu. We measured salt content, depth of groundwater table, as well as surface water runoff from 2010 to 2020. The relationship between salt content and these environmental factors was calculated using the descriptive statistics and Piper figure analysis method. 【Result】 The increased salt content in the top 0~20 cm soil layer was mainly induced by the increased precipitation. The maximum electric conductivity of the topsoil layer occurred between October and November, but it is linearly correlated to precipitation in August (y=0.794 3x+126.65, R2=0.631 3, P

[Objective] Soil salinization due to shallow groundwater table is a main abiotic stress facing agricultural production in eastern Henan province. In this paper we analyze the migration of salt in the plough layer and its relationship with geochemistry of both surface water and groundwater at different seasons. [Method]The experiment was conducted in areas adjacent to the National Agro-ecological System Observation and Research Station of Shangqiu. We measured salt content, depth of groundwater table, as well as surface water runoff from 2010 to 2020. The relationship between salt content and these environmental factors was calculated using the descriptive statistics and Piper figure analysis method.[Result]The increased salt content in the top 0~20 cm soil layer was mainly induced by the increased precipitation. The maximum electric conductivity of the topsoil layer occurred between October and November, but it is linearly correlated to precipitation in August (y=0.794 3x+126.65, R2=0.631 3, P<0.05). The content of Ca2+, Mg2+, Na+, HCO3 -, SO4 2-, Cl- and electric conductivity of water in the topsoil layer and the 0~100 cm soil layer, as well as depth of the shallow groundwater table in 2020 was significantly higher than those in 2015 (P<0.05). We also found that the leachate from the topsoil was geochemically similar to that of the shallow groundwater and the surface runoff in 2020, indicating that the soluble salt in the topsoil was related to both surface water and subsurface water.[Conclusion]The electric conductivity of water in the topsoil layer and the 0~100 cm-depth soil layer in October was both positively correlated to precipitation and the depth of the groundwater table, suggesting that salt in the topsoil was hydraulically connected to soluble salt in the surface water and the subsurface water. [ABSTRACT FROM AUTHOR]

Copyright of Acta Scientiarum Naturalium Universitatis Sunyatseni / Zhongshan Daxue Xuebao is the property of Sun-Yat-Sen University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The measurement of soil water content is a very important factor in plant cultivation, both from an economic and ecological point of view. Proper estimation of moisture content not only allows for proper yields but can also contribute to ecologically appropriate use of fresh water, of which the world’s resources are limited. It is important, for example, that the moisture content in the root area of plants is optimal for their growth, while over-watering can result in losses in the form of water, which seeps below the root layer and is lost. The novel, inexpensive electronic meter for measuring soil moisture is presented in the article. The meter, based on a capacitive method, uses an optimization algorithm to calculate soil electrical permeability and a simplified new formula between soil electrical permeability and volumetric moisture content. Moreover, by using two high-frequency signals for measurements, it is possible not only to estimate moisture content but also soil conductivity. Both readings obtained from the meter not only allow for rational management of crop optimization for economic reasons but are also important for environmental protection. In addition, the inexpensive meter, based on the principle of operation presented, can be made as an IoT module, which allows for its wide application.

Abstract Background For better understanding the mechanism of Reaumuria soongarica community formation in a salt stressed grassland ecosystem, we designed a field experiment to test how leaves salt secretion changes the competitive relationship between species in this plant communities. Results Among the three species (R. soongarica, Stipa glareosa and Allium polyrhizum) of the salt stressed grassland ecosystem, the conductivity of R. soongarica rhizosphere soil was the highest in five soil layers (0–55 cm depth). The high soil conductivity can increase the daily salt secretion rate of plant leaves of R. soongarica. In addition, we found the canopy size of R. soongarica was positively related to the distance from S. glareosa or A. polyrhizum. The salt-tolerance of R. soongarica was significantly higher than the other two herbs (S. glareosa and A. polyrhizum). Moreover, there was a threshold (600 µS/cm) for interspecific competition of plants mediated by soil conductivity. When the soil conductivity was lower than 600 µS/cm, the relative biomass of R. soongarica increased with the soil conductivity increase. Conclusions The efficient salt secretion ability of leaves increases soil conductivity under the canopy. This leads the formation of a “saline island” of R. soongarica. Meanwhile R. soongarica have stronger salt tolerance than S. glareosa and A. polyrhizum. These promote the competitiveness of R. soongarica and inhibit interspecies competition advantage of the other two herbs (S. glareosa and A. polyrhizum) in the plant community. It is beneficial for R. soongarica to establish dominant communities in saline regions of desert grassland.

Abstract Background Soil-Transmitted Helminths are a group of parasites that cause gastrointestinal infections in humans and require the soil to develop into their infective forms. Ecological factors such as soil temperature, soil pH and rainfall patterns are, however, important determinants for the successful transmission of soil helminths as they play a major role in their abundance and survival in the soil. The study investigated the ecological factors influencing the transmission of soil-transmitted helminths in Ifedore district, Southwest Nigeria. Results Out of the one hundred and ninety-two (192) soil samples from the study area, one hundred and fifty-two 152 (79.2%) were positive for the presence of soil helminths’ larvae and ova. Higher occurrence of soil helminths was recorded during the rainy months (n = 416) than during the months with no records of rainfall (n = 290). Sandy soil had the highest number of soil helminths 285 (40.4%), while clay soil recorded the least 88 (12.5%). Soil temperature showed negative correlations with the occurrence of Ancylostoma duodenale (r = − 0.53) and Strongyloides stercoralis larvae (r = − 0.36), while soil conductivity showed positive correlations with the occurrence of Ascaris lumbricoides (r = 0.28) and A. duodenale (r = 0.34). Conclusion It is evident from the study that ecological factors played a significant role in the occurrence and abundance of soil-transmitted helminths. This research is important for predicting and monitoring soil-transmitted helminthiasis in endemic countries, and to devise effective control measures.

Copyright of Agrochemistry & Soil Science / Agrokémia és Talajtan is the property of Akademiai Kiado and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The direct estimation of soil hydraulic conductivity (Ks) requires expensive laboratory measurement to present adequately soil properties in an area of interest. Moreover, the estimation process is labor and time-intensive due to the difficulties of collecting the soil samples from the field. Hence, innovative methods, such as machine learning techniques, can be an alternative to estimate Ks. This might facilitate agricultural water and nutrient management which has an impact on food and water security. In this spirit, the study presents neural-network-based models (artificial neural network (ANN), deep learning (DL)), tree-based (decision tree (DT), and random forest (RF)) to estimate Ks using eight combinations of soil data under calcareous alluvial soils in a semi-arid region. The combinations consisted of soil data such as clay, silt, sand, porosity, effective porosity, field capacity, permanent wilting point, bulk density, and organic carbon contents. The results compared with the well-established model showed that all the models had satisfactory results for the estimation of Ks, where ANN7 with soil inputs of sand, silt, clay, permanent wilting point, field capacity, and bulk density values showed the best performance with mean absolute error (MAE) of 2.401 mm h−1, root means square error (RMSE) of 3.096 mm h−1, coefficient of determination (R2) of 0.940, and correlation coefficient (CC) of 0.970. Therefore, the ANN could be suggested among the neural-network-based models. Otherwise, RF could also be used for the estimation of Ks among the tree-based models. [ABSTRACT FROM AUTHOR]

The temperature, moisture, and salt content of soil in alpine regions are sensitive to changes in climatic factors and are important indicators of ecosystem functions. In this study, we collected soil moisture, temperature and electrical conductivity data at different depths at a sampling site on Bird Island in Qinghai Lake during winter using a continuous soil temperature, moisture and salt content monitoring system and analyzed their variations and influential factors. The variation in soil moisture showed an obvious 'V-shaped' pattern from 00:00 to 23:00 and an upward trend with soil layer depth. From 00:00 to 23:00, the overall soil temperature data fitted a 'unimodal' curve and showed a clear and continuous upward trend with soil layer depth at a rate of 0.684 (p < 0.001). Soil electrical conductivity data also exhibited a distinct 'V-shaped' pattern from 00:00 to 23:00 and a continuous increase with increasing soil depth. The correlation between soil temperature, moisture, and conductivity and the spatial distribution of five climate factors indicated that climate factors accounted for 53.6% of the changes in soil temperature, moisture, and salinity. Climate factors showed a significant positive correlation with soil temperature, moisture, and conductivity (p < 0.001), and air temperature was the most important factor influencing soil temperature and soil moisture changes, whereas wind direction was the most important factor influencing soil conductivity. (Wind direction and wind speed affect soil evapotranspiration, and then affect soil moisture and solute transport process). The results of this preliminary study reveal the characteristics associated with soil temperature, moisture, and salinity changes in winter within the wetlands of Bird Island on Qinghai Lake in the context of climate change, and they can be used as valuable reference data in further studies investigating associated changes in ecosystem functions. [ABSTRACT FROM AUTHOR]

Background: For better understanding the mechanism of Reaumuria soongarica community formation in a salt stressed grassland ecosystem, we designed a field experiment to test how leaves salt secretion changes the competitive relationship between species in this plant communities. Results: Among the three species (R. soongarica, Stipa glareosa and Allium polyrhizum) of the salt stressed grassland ecosystem, the conductivity of R. soongarica rhizosphere soil was the highest in five soil layers (0–55 cm depth). The high soil conductivity can increase the daily salt secretion rate of plant leaves of R. soongarica. In addition, we found the canopy size of R. soongarica was positively related to the distance from S. glareosa or A. polyrhizum. The salt-tolerance of R. soongarica was significantly higher than the other two herbs (S. glareosa and A. polyrhizum). Moreover, there was a threshold (600 µS/cm) for interspecific competition of plants mediated by soil conductivity. When the soil conductivity was lower than 600 µS/cm, the relative biomass of R. soongarica increased with the soil conductivity increase. Conclusions: The efficient salt secretion ability of leaves increases soil conductivity under the canopy. This leads the formation of a "saline island" of R. soongarica. Meanwhile R. soongarica have stronger salt tolerance than S. glareosa and A. polyrhizum. These promote the competitiveness of R. soongarica and inhibit interspecies competition advantage of the other two herbs (S. glareosa and A. polyrhizum) in the plant community. It is beneficial for R. soongarica to establish dominant communities in saline regions of desert grassland. [ABSTRACT FROM AUTHOR]

Background: Soil-Transmitted Helminths are a group of parasites that cause gastrointestinal infections in humans and require the soil to develop into their infective forms. Ecological factors such as soil temperature, soil pH and rainfall patterns are, however, important determinants for the successful transmission of soil helminths as they play a major role in their abundance and survival in the soil. The study investigated the ecological factors influencing the transmission of soil-transmitted helminths in Ifedore district, Southwest Nigeria. Results: Out of the one hundred and ninety-two (192) soil samples from the study area, one hundred and fifty-two 152 (79.2%) were positive for the presence of soil helminths' larvae and ova. Higher occurrence of soil helminths was recorded during the rainy months (n = 416) than during the months with no records of rainfall (n = 290). Sandy soil had the highest number of soil helminths 285 (40.4%), while clay soil recorded the least 88 (12.5%). Soil temperature showed negative correlations with the occurrence of Ancylostoma duodenale (r = − 0.53) and Strongyloides stercoralis larvae (r = − 0.36), while soil conductivity showed positive correlations with the occurrence of Ascaris lumbricoides (r = 0.28) and A. duodenale (r = 0.34). Conclusion: It is evident from the study that ecological factors played a significant role in the occurrence and abundance of soil-transmitted helminths. This research is important for predicting and monitoring soil-transmitted helminthiasis in endemic countries, and to devise effective control measures. [ABSTRACT FROM AUTHOR]

In the coastal saline soils, moisture and salinity are the functions of groundwater depth affecting crop growth and yield. Accordingly, the objectives of this study were to: 1) investigate the combined effects of moisture and salinity stresses on wheat growth as affected by groundwater depth, and 2) find the optimal groundwater depth for wheat growth in coastal saline soils. The groundwater depths (0.7, 1.1, 1.5, 1.9, 2.3, and 2.7 m during 2013–2014 (Y1) and 0.6, 1.0, 1.4, 1.8, 2.2, and 2.6 m during 2014–2015 (Y2)) of the field experiment were maintained by soil columns. There was a positive correlation between soil moisture and salinity. Water logging with high salinity (groundwater depth at 0.7 m in Y1 and 0.6 m in Y2) showed a greater decline towards wheat growth than that of slight drought with medium (2.3 m in Y1) or low salinity (2.7 m in Y1, 2.2 and 2.6 m in Y2). The booting stage was the most sensitive stage of wheat crop under moisture and salinity stresses. Data showed the most optimal rate of photosynthesis, grain yield, and flour quality were obtained under the groundwater depth (ditch depth) of 1.9 m (standard soil moisture with medium salinity) and 2.3 m (slight drought with medium salinity) in Y1 and 1.8 m (standard soil moisture with medium salinity) and 2.2 m (slight drought with low salinity) in Y2. The corresponding optimal soil relative moisture content and conductivity with the 1:5 distilled water/soil dilution, in the depth of 0–20 cm and 20–40 cm in coastal saline soils, were equal to 58.67–63.07% and 65.51–72.66% in Y1, 63.09–66.70% and 69.75–74.72% in Y2; 0.86–1.01 dS m–1 and 0.63–0.77 dS m–1 in Y1, 0.57–0.93 dS m–1 and 0.40–0.63 dS m–1 in Y2, respectively.

Copyright of Agrochemistry & Soil Science / Agrokémia és Talajtan is the property of Akademiai Kiado and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper proposes a technique to approximate a multi-layer earth structure by a homogeneous conductivity soil in ground return impedance calculations. An equivalent real-valued conductivity parameter is obtained, which can be used with reasonable accuracy in a simpler expression or in commonly available EMTP software, such as the Line Constants routine of the Alternative Transients Program (ATP). Several actual soil models are evaluated at frequencies ranging from 1 Hz to 2 MHz. Results show that the proposed method is accurate for modeling most power system problems, from steady-state conditions to transients commonly verified in electrical systems. The proposed expression is easy to use and introduces a considerable performance gain in terms of floating-point operations, compared to the analytical formulation of the general multi-layer soil structure. [ABSTRACT FROM AUTHOR]

In order to improve the level of management and utilization of the coastal salinization land, its variation character of temporal and spatial should be grasped. Kenli County of the Yellow River delta was chose, the temporal and spatial variation were studied during recent 10 years from 2007 to 2016 by GIS technology. The results show that study area has strong soil salinization variation characteristics both of the two periods in the study area and different levels of salinization land area have been changed a lot in the past 10 years. The non-salinization land area is changed slightly, moderate salinization and severe salinization land area are reduced by 39.28%, mild salinization land area is increased by 10.03% and the data also shows that the area of the salt land has been increased. The area of soil salinity degree is significantly decreased mainly distributed in the central and southeast of Kenli County, which it has a great relationship with the straw utilization and rice farming. The area of soil salinity degree is significantly increased mainly distributed in the southwest, south-central and east of Kenli County, which it has a great relationship with sea water infiltration and land use pattern changes. Thus it can be adjusted in the way of land use according to the condition of soil water and salt, for effectively and reasonablely utilizing salinization land. [ABSTRACT FROM AUTHOR]

This paper presents mathematical modeling of the relation between basic chemical elements and soil properties. An overview of the basic chemical elements and properties of the soil is presented. An approach is proposed to conduct an experimental study of the impact of basic chemical elements and soil properties. Statistical methods are used for data processing. Mathematical models for relation between basic chemical elements and soil quality indicators are developed. Mathematical models for indirect determining the content of basic chemical elements by measuring the main soil indicators are analyzed. [ABSTRACT FROM AUTHOR]

Soil moisture is an important type of data in many fields; ranging from agriculture to environmental monitoring. Three soil samples were collected at definite proportions to represent the three basic soil types (sandy, loamy and clay soils). The moisture contents of these soil samples were analyzed using the thermogravimetric method. This paper employed the use of PC-based soil moisture content measuring system in order to obtain accurate results. It works with the principle that there is an increase or decrease in soil conductivity as soil moisture increases or decreases respectively. The constructed prototype was used to test the three soil samples as well and the results were compared with that of the thermogravimetric method. The results gotten from this prototype shows the relationship between conductivity and moisture content of the soil. The system was well calibrated in order to get standard readings and conquer the problem of transistor amplification at the signal pick up stage. This therefore makes it possible to get fast an accurate results without wasting much time and energy.

Soil moisture is an important type of data in many fields; ranging from agriculture to environmental monitoring. Three soil samples were collected at definite proportions to represent the three basic soil types (sandy, loamy and clay soils). The moisture contents of these soil samples were analyzed using the thermogravimetric method. This paper employed the use of PC-based soil moisture content measuring system in order to obtain accurate results. It works with the principle that there is an increase or decrease in soil conductivity as soil moisture increases or decreases respectively. The constructed prototype was used to test the three soil samples as well and the results were compared with that of the thermogravimetric method. The results gotten from this prototype shows the relationship between conductivity and moisture content of the soil. The system was well calibrated in order to get standard readings and conquer the problem of transistor amplification at the signal pick up stage. This therefore makes it possible to get fast an accurate results without wasting much time and energy. [ABSTRACT FROM AUTHOR]

To design holographic and impulse ground penetrating radar (GPR) sensors suitable for humanitarian de-mining in the Donbass (Ukraine) conflict zone, we measured critical electromagnetic parameters of typical local soils using simple methods that could be adapted to any geologic setting. Measurements were recorded along six profiles, each crossing at least two mapped soil types. The parameters selected to evaluate GPR and metal detector sensor performance were magnetic permeability, electrical conductivity, and dielectric permittivity. Magnetic permeability measurements indicated that local soils would be conducive to metal detector performance. Electrical conductivity measurements indicated that local soils would be medium to high loss materials for GPR. Calculation of the expected attenuation as a function of signal frequency suggested that 1 GHz may have optimized the trade-off between resolution and penetration and matched the impulse GPR system power budget. Dielectric permittivity was measured using both time domain reflectometry and impulse GPR. For the latter, a calibration procedure based on an in-situ measurement of reflection coefficient was proposed and the data were analyzed to show that soil conditions were suitable for the reliable use of impulse GPR. A distinct difference between the results of these two suggested a dry (low dielectric) soil surface, grading downward into more moist (higher dielectric) soils. This gradation may provide a matching layer to reduce ground surface reflections that often obscure shallow subsurface targets. In addition, the relatively high dielectric deeper (10 cm–20 cm) subsurface soils should provide a strong contrast with plastic-cased mines.

A modified field‐to‐line coupling model for simulating the corona effect on the lightning induced voltages of the overhead multi‐conductor transmission lines is proposed in this study. Since the model is non‐linear, it is solved in an iterative way combining with the time‐domain finite‐element method and is validated by the measurements of Inoue's experiments. Furthermore, the unconditional stability of the numerical method is theoretically proved. The proposed model is a simplified method according to the method recently proposed by Thang et al., in which finite difference time domain (FDTD) is used to calculate the induced voltages. Compared with FDTD, the proposed model can achieve good efficiency because the transmission line theory is adopted instead of the electromagnetic solution. Both the effects of the corona and the lossy ground on the induced voltage are studied, furthermore, the relationship between the corona effect and the soil conductivity is discussed. The simulation results demonstrate that the corona effect will cause a rise time increase and waveform distortion of the induced voltage, and the magnitudes of induced voltages in the presence of corona discharge are larger than those computed without considering corona. [ABSTRACT FROM AUTHOR]

Hydrogeophysics is a rapidly evolving discipline emerging from geophysical methods. Geophysical methods are nowadays able to illustrate not only the fabric and the structure of the underground, but also the subsurface processes that occur within it, as fluids dynamic and biogeochemical reactions. This is a growing wide inter-disciplinary field, specifically dedicated to revealing soil properties and monitoring processes of change due to soil/bio/atmosphere interactions. The discipline involves environmental, hydrological, agricultural research and counts application for several engineering purposes. The most frequently used techniques in the hydrogeophysical framework are the electric and electromagnetic methods because they are highly sensitive to soil physical properties such as texture, salinity, mineralogy, porosity and water content. Non-invasive techniques are applied in a number of problems related to characterization of subsurface hydrology and groundwater dynamic processes. Ground based methods, as electrical tomography, proved to obtain considerable resolution but they are difficult to extend to wider exploration purposes due to their logistical limitation. Methods that don't need electrical contact with soil can be, on the contrary, easily applied to broad areas. Among these methods, a rapidly growing role is played by frequency domain electro-magnetic (FDEM) survey. This is due thanks to the improvement of multi-frequency and multi-coils instrumentation, simple time-lapse repeatability, cheap and accurate topographical referencing, and the emerging development of inversion codes. From raw terrain apparent conductivity meter, FDEM survey is becoming a key tool for 3D soil characterization and dynamics observation in near surface hydrological studies. Dozens of papers are here summarized and presented, in order to describe the promising potential of the technique. [ABSTRACT FROM AUTHOR]

Electrokinetic (EK) remediation is one of the most useful approaches for de-contamination of soils. However, it is unclear that how and when the electrokinetic remediation gives advantages over other remediation techniques in soil. This study was designed to find the influence of Fe 2+ particles on the mobility of Pb 2+ ions, during electrokinetic remediation, in soil contaminated purposely by lead nitrate Pb(NO 3 ) 2 . Two types of electrokinetic experiments were performed, by using iron and graphite electrodes. The Fe 2+ ions from the iron electrodes, produced due to acidic environment in anode compartment, affected the mobility of lead particles by precipitating as Fe(OH) 2 . Fe 2+ ions enhance the adsorption of lead ions in soil. The results show Fe 2+ ions of lower ionic conductivity decreased mobility of other particles in soil. Electrokinetic remediation for up to 120 h with iron electrodes is shown to be less effective for removal of lead. In contrast, graphite electrodes were 15 times more effective in lead removal from soil. [ABSTRACT FROM AUTHOR]

SUMMARY This paper presents an efficient method for the calculation of the induced voltage in a finite-length horizontal overhead conductor over a finitely conducting earth. The method uses the classical Rusck's analytical expression for perfect conducting earth added to a second component that considers the influence of the horizontal electric field developed at the surface of a finitely conducting earth. The results obtained with the proposed formulation are compared with a computer code based on the Finite-Difference Time-Domain (FDTD) Method earlier presented by the authors as well as with different formulations proposed by Paolone et al., He-Ming et al. and Andreotti et al. In all cases, a very good agreement is verified. The presented formulation is very efficient in saving computer time and may be a powerful tool for lightning performance analysis of overhead distribution lines. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

We present a review and comparison of different models representing the frequency dependence of the soil electrical parameters (conductivity and permittivity). These models are expressed in terms of curve-fit expressions for the soil conductivity and relative permittivity, which are based on experimental data. Six available models/expressions are discussed and compared making reference to two sets of experimental data. It is shown that the soil models by Scott, Smith–Longmire, Messier, and Visacro–Alipio predict overall similar results, which are in reasonable agreement with both sets of experimental data. Differences between the soil models are found to be more significant at high frequencies and for low-resistivity soils. The causality of the considered models is tested using the Kramers–Kronig relationships. It is shown that the models/expressions of Smith–Longmire, Messier, and Portela satisfy the Kramers–Kronig relationships and thus provide causal results. The soil models are applied to the analysis of grounding systems subject to a lightning current. A full-wave computational model is adopted for the analysis. The analysis is performed considering two cases: 1) a simple horizontal grounding electrode, and 2) a realistic grounding system of a wind turbine. Two current waveforms associated with typical first and subsequent return strokes are adopted for the representation of the incident lightning current. In agreement with recent studies, simulations show that the frequency dependence of the soil parameters results in a decrease of the potential of the grounding electrode, with respect to the case where the parameters are assumed to be constant. It is found that the models/expressions by Scott, Smith–Longmire, Messier, and Visacro–Alipio predict similar levels of decrease, which vary from about 2% (\rhoLF = 20 Ω·m and first stroke) up to 45% (\rhoLF = 10 000 Ω·m and subsequent stroke). On the other hand, the models of Portela and Visacro–Portela predict significantly larger levels of the decrease, especially for very high resistivity soils. Furthermore, in the case of a high resistivity soil (10 000 Ω·m), the Visacro–Alipio expression predicts a longer risetime for the grounding potential rise, compared to the predictions of Scott, Smith–Longmire, and Messier models. [ABSTRACT FROM PUBLISHER]

Abstract: We use the Bayesian method to invert a simple two-layer pedological horizon (1-D with a topsoil and a subsoil) of a surveyed site to be assessed. We show how the Bayesian method is well suited to the determination of topsoil/subsoil features, and can be used in particular as a tool for the analysis of parameters to be retrieved in terms of information content. Our approach is devoted mainly to the assessment of topsoil thickness, and of topsoil and subsoil conductivities, which are provided in terms of probability density functions. We first summarize the methodology implemented with the Geonics EM38-MK2 conductivity meter, and discuss the adaptation of field procedures and post-processing methods to mitigate the effects of drift and bias. We briefly review some non-Bayesian approaches, and then develop the Bayesian approach for the context of our geophysical survey, highlighting its merits. Positivity constraints (on thickness and conductivity) are included in the form of log parameters. A priori knowledge, based on an objective choice made by the geophysicist, is naturally included in the Bayesian scheme. We discuss the equivalence problem associated with the application of the Slingram method to soil structure analysis. The survey of a luvisol at the Kwazulu-Natal (South Africa) site of Potshini is used to illustrate an ecological application of the Slingram and Bayesian methods, used to define the geo-electrical structure of the near-surface soil. These algorithms have demonstrated their usefulness in mapping the clay content of the Bt horizon associated with the control of encroaching trees. [Copyright &y& Elsevier]

Direct mapping of variability in soils can be a complex, time-consuming and costly process. Consequently, maps of geophysical data such as ground penetrating radar (GPR) and electromagnetic induction (EMI) are commonly used as proxies for soil maps, and these geophysical maps are most useful if they relate to variations in plant attributes such as grapevine trunk circumference. This article demonstrates that vine trunk circumference in five pinot noir vineyards is primarily influenced by changes in slope, elevation and aspect. Variability in GPR maps shows mixed correlations with vine trunk circumference data. In contrast, multi-frequency EMI surveys yield soil apparent electrical conductivity data that commonly show significant correlations with variations in vine trunk circumference data, especially when coupled with global positioning system surveys, suggesting that this is the preferred geophysical tool for mapping variability in soils. [ABSTRACT FROM AUTHOR]

This paper presents the calculation results of lightning-induced voltages on overhead lines using two different formulations for the horizontal electric field at the earth surface. The first one is a time-domain equation equivalent to the surface impedance contained in the Cooray–Rubinstein formula, while the second one is an improved equation that provides more accurate results in the vicinity of lightning. The induced voltages are calculated for a strike in the vicinity of the line (50 m) and the results show that, for good-conducting earth, the two formulations are equivalent. However, for poor-conducting earth, the second expression provides a higher and longer induced voltage. Based on the calculation results, a limiting condition for the use of these equations is proposed. [ABSTRACT FROM PUBLISHER]

This paper presents an approximate formula for the peak value of lightning-induced voltages in an overhead line, considering the ground resistivity and a trapezoidal lightning return stroke current waveform with typical parameters 3.8-\mus front time and 120-m/\mus velocity. It presents an improvement in a formula previously proposed by the authors. The formula is used with a probabilistic approach, and the results are compared with theoretical and experimental results available in the literature. The results show that the proposed formula, although very simple, is in good agreement with results obtained using complete formulations and experimental data. [ABSTRACT FROM AUTHOR]

Abstract: The land surface parameters are simulated with a Noah-LSM (NCEP, OSU, Air Force and Office of Hydrology Land Surface Model) version 2.7.1 for the tropical conditions using the surface and subsurface observations over a semi-arid region of Gujarat, India from the Land Surface Processes Experiment (LASPEX) data sets. The surface forcings are air temperature, air humidity, surface pressure, wind speed, and surface downward short wave and long wave radiations. The model simulations were carried out for two cases viz one in using soil moisture dependent soil thermal conductivity and the other by using a fixed site specific soil thermal conductivity. Simulated surface parameters are compared with observations obtained in the LASPEX to validate the Noah-LSM performance. Simulated skin temperature and net radiation are in agreement with observed results for dry surface conditions. However, simulated soil temperatures at different depths are deviating from observations particularly for wet period. Simulation of soil hydrology related parameters is very sensitive to the use of soil thermal conductivity. Based on the evaluations of model and observed results, we propose the improvement of Noah-LSM taking into consideration the site specific soil thermal conductivities and surface parameters for tropical conditions. [ABSTRACT FROM AUTHOR]

Favorable effects of organic wastes on soil characteristics are capable of permitting a sustainable agriculture. This experiment was conducted to evaluate the effects of organic compost from two agri-industrial wastes on soil fertility and productivity of corn and wheat in Astorga County, northwestern Parana, Brazil. The organic compost had components from the gelatin industry, which uses bovine chips and shavings by-products from the tannery industry and by-products (filter cake and plant straws) from the sugarcane industry. The experimental design was randomized complete block with eight treatments and four replications. Only the wheat had increased productivity, and there was no response to doses above 25 t ha-1. Not all levels of organic compost affected the soil electrical conductivity. [ABSTRACT FROM AUTHOR]

An approximate formula is proposed to estimate the peak value of lightning induced voltages in an infinite line, considering the soil resistivity. The formula is derived from results of a computer code for lightning induced voltage calculation. The code is based on Rusck's formulation for the vertical electric field, for a perfect conducting earth, and the formulation for the horizontal electric field for finitely conducting earth proposed by Barbosa and Paulino. The electromagnetic field coupling with the line is carried out using the model proposed by Agrawal. The results are compared with experimental data from Barker et al. for validation purposes. The paper also presents an extension of the methodology proposed in IEEE Std.1410 Guide to include the effect of the soil finite conductivity in the assessment of the lightning performance of distribution lines due to nearby strikes. The annual indirect lightning induced voltage flashover rates obtained with IEEE Std. 1410 method are compared with the approximate formula results. [ABSTRACT FROM AUTHOR]