Spatial interpolation of soil salinity and sodicity for a saline soil in Southern Alberta

1992 ◽  
Vol 72 (4) ◽  
pp. 503-516 ◽  
Author(s):  
Jacques Gallichand ◽  
Gary D. Buckland ◽  
Denis Marcotte ◽  
M. J. Hendry
Keyword(s):  
Soil Salinity ◽  
Spatial Interpolation ◽  
Moving Average ◽  
Three Dimensional ◽  
Data Representation ◽  
Absolute Difference ◽  
Sodium Absorption ◽  
Contour Maps ◽  
Sodium Absorption Ratio ◽  
Southern Alberta

Soil salinity and sodicity data are usually represented as contour maps based on spatially interpolated data. This study was conducted to assess two commonly used spatial interpolation methods (moving average and weighted moving average) and three forms of two-dimensional (2D) and three-dimensional (3D) kriging. Soil was sampled from two depths on a 25-m grid at 40 sites in a saline and sodic soil of Southern Alberta. Samples were analyzed for electrical conductivity (ECe) and sodium absorption ratio (SARe) of saturation paste extracts. Methods were compared by cross-validation using the mean absolute difference (MAD) between estimated and observed values. Values of MAD resulting from 3D kriging were inferior to those obtained from moving averages. Moving average methods were very sensitive to the number of neighbors used in the estimation. For kriging methods, however, precision remained stable for more than about 10–12 neighbors. Three-dimensional ordinary kriging was the most precise and robust interpolator with a MAD value of 9.74 dS m−1 for ECe. For SARe the lowest MAD value of 10.55 was obtained with 3D ordinary co-kriging. Data representation produced by 3D kriging allowed easy identification of ECe spatial structure. Key words: Spatial interpolation, kriging, moving average, soil, salinity, sodicity

scholarly journals Geophysical and physicochemical characterization of organic waste contamination of hydrolithofacies in the coastal dumpsite of Akwa Ibom State, southern Nigeria

2017 ◽  
Vol 17 (6) ◽  
pp. 1626-1637 ◽  
Author(s):  
Johnson C. Ibuot ◽  
Francisca N. Okeke ◽  
Nyakno J. George ◽  
Daniel N. Obiora
Keyword(s):  
Water Samples ◽  
Physicochemical Characterization ◽  
Sodium Absorption ◽  
Organic Contamination ◽  
Contour Map ◽  
Contour Maps ◽  
Sodium Absorption Ratio ◽  
Negative Effect ◽  
Physicochemical Methods

Abstract Geophysical and physicochemical methods were carried out to examine the effect of leachate on groundwater in a dumpsite location in Akwa Ibom State, Nigeria. This was done to ascertain the level of organic contamination in the wells located in the study area. The analysis of water samples from boreholes close to the dumpsite was done to constrain the interpretation of electrical resistivity data on the reality of the effect imposed by dumpsite leachate on the hydrolithofacies. The resistivity values of the underlying layers were observed to be lower than the overlying layer, an effect which may be associated with the infiltration of leachate into the underlying layers. The geohydrolayer resistivities range from 78.4 to 1,669.8 Ωm. The contour maps generated display the variations of the parameters. The elevation contour map indicates the flow of groundwater in a southwest–northeast direction which also depicts the direction of leachate flow. The physicochemical water samples show differences in concentrations of the physicochemical parameters. The concentrations of the ions in the water samples measured are compared with the WHO standard for drinking water. The sodium absorption ratio and sodium percentage show that the groundwater within the dumpsite has no negative effect on the subsurface.

scholarly journals Effects of treated wastewater irrigation on soil salinity and sodicity in Sfax (Tunisia): A case study

2010 ◽  
Vol 23 (2) ◽  
pp. 133-146 ◽  
Author(s):  
Nebil Belaid ◽  
Catherine Neel ◽  
Monem Kallel ◽  
Tarek Ayoub ◽  
Abdel Ayadi, ◽  
...  
Keyword(s):  
Soil Salinity ◽  
Exchange Capacity ◽  
Control Area ◽  
Treated Wastewater ◽  
Sodium Absorption ◽  
Treatment Area ◽  
Sodium Absorption Ratio ◽  
A Value ◽  
Different Depths ◽  
The Impact

In arid regions such as near Sfax (Tunisia), treated wastewater effluents (TWE) are often applied as agricultural irrigation. Irrigation TWE usually contain large amounts of carbon, nitrogen and sodium. The objective of this study was to evaluate the impact of TWE irrigation on soil salinity and sodicity. In the city of Sfax, two sites were selected with two soil types (fluvisol and calcisol) having been irrigated for 4 and 15 years respectively. Soils were sampled at three different depths (0-30, 30-60 and 60-90 cm) in the TWE irrigated area and in a non-irrigated control area. Irrigated and non-irrigated study soils were analyzed for pH, nitrate and ammonia, electrical conductivity (ECs), exchangeable sodium percentage (ESP), sodium absorption ratio (SAR) and soil organic matter. The fluvisol, irrigated for only four years, is more affected by salinity than the calcisol irrigated for 15 years. In the upper fluvisol layer irrigated by the treated wastewater, ECs reach 8 mS•cm-1 and ESP a value of 15% while in all layers of the calcisol, ECs and ESP are lower and rarely exceed 4 mS•cm-1 and 6% respectively. This result is due to a combination of factors in the fluvisol treatment area including texture, cation exchange capacity, irrigation procedure and crop management.

scholarly journals Validation of Scolioscan Air-Portable Radiation-Free Three-Dimensional Ultrasound Imaging Assessment System for Scoliosis

Sensors ◽  
2021 ◽  
Vol 21 (8) ◽  
pp. 2858
Author(s):  
Kelly Ka-Lee Lai ◽  
Timothy Tin-Yan Lee ◽  
Michael Ka-Shing Lee ◽  
Joseph Chi-Ho Hui ◽  
Yong-Ping Zheng
Keyword(s):  
Ultrasound Imaging ◽  
Imaging System ◽  
Outcome Measurement ◽  
Three Dimensional ◽  
3D Ultrasound ◽  
Mean Difference ◽  
Assessment System ◽  
Absolute Difference ◽  
Data Sets ◽  
Low Profile

To diagnose scoliosis, the standing radiograph with Cobb’s method is the gold standard for clinical practice. Recently, three-dimensional (3D) ultrasound imaging, which is radiation-free and inexpensive, has been demonstrated to be reliable for the assessment of scoliosis and validated by several groups. A portable 3D ultrasound system for scoliosis assessment is very much demanded, as it can further extend its potential applications for scoliosis screening, diagnosis, monitoring, treatment outcome measurement, and progress prediction. The aim of this study was to investigate the reliability of a newly developed portable 3D ultrasound imaging system, Scolioscan Air, for scoliosis assessment using coronal images it generated. The system was comprised of a handheld probe and tablet PC linking with a USB cable, and the probe further included a palm-sized ultrasound module together with a low-profile optical spatial sensor. A plastic phantom with three different angle structures built-in was used to evaluate the accuracy of measurement by positioning in 10 different orientations. Then, 19 volunteers with scoliosis (13F and 6M; Age: 13.6 ± 3.2 years) with different severity of scoliosis were assessed. Each subject underwent scanning by a commercially available 3D ultrasound imaging system, Scolioscan, and the portable 3D ultrasound imaging system, with the same posture on the same date. The spinal process angles (SPA) were measured in the coronal images formed by both systems and compared with each other. The angle phantom measurement showed the measured angles well agreed with the designed values, 59.7 ± 2.9 vs. 60 degrees, 40.8 ± 1.9 vs. 40 degrees, and 20.9 ± 2.1 vs. 20 degrees. For the subject tests, results demonstrated that there was a very good agreement between the angles obtained by the two systems, with a strong correlation (R2 = 0.78) for the 29 curves measured. The absolute difference between the two data sets was 2.9 ± 1.8 degrees. In addition, there was a small mean difference of 1.2 degrees, and the differences were symmetrically distributed around the mean difference according to the Bland–Altman test. Scolioscan Air was sufficiently comparable to Scolioscan in scoliosis assessment, overcoming the space limitation of Scolioscan and thus providing wider applications. Further studies involving a larger number of subjects are worthwhile to demonstrate its potential clinical values for the management of scoliosis.

scholarly journals Classification of groundwater suitability for irrigation purposes using a comprehensive approach based on the AHP and GIS techniques in North Kurdufan Province, Sudan

2021 ◽  
Vol 11 (7) ◽  
Author(s):  
Elsiddig Eldaw ◽  
Tao Huang ◽  
Adam Khalifa Mohamed ◽  
Yahaya Mahama
Keyword(s):  
Water Quality ◽  
Spatial Distribution ◽  
Groundwater Quality ◽  
Irrigation Water ◽  
Research Effort ◽  
Sodium Absorption ◽  
Irrigation Water Quality ◽  
Middle Income ◽  
Sodium Absorption Ratio ◽  
Deep Aquifers

AbstractDeterioration of groundwater quality due to drastic human interventions is rising at an alarming rate particularly in lower- and middle-income countries. Yet, limited research effort has been devoted to monitoring and ascertaining groundwater quality. The present study develops a comprehensive irrigation water quality index (IWQI) for rating water quality of shallow and deep aquifers in North Kurdufan province, Sudan. The new approach is developed to overcome the deficiencies of the existing irrigation indices and coming up with a unified decision for classifying water quality for irrigation purposes. Because of these indices like permeability index (PI), sodium absorption ratio (SAR), etc., depending on specific elements, entirely subjective, as well as the great variations in their results, particularly when classifying water quality. Thus, IWQI is created based on eight indices that are generally used to evaluate irrigation water quality, plus three physicochemical parameters have been proven an impact on water quality. The analytic hierarchy process (AHP) is applied to minimize the subjectivity at assign parameter weights under multiple criteria decision analysis tools (MCDA). The spatial distribution of IWQI agrees with the spatial distribution of the most parameters. The results of our approach reveal that the majority of samples are suitable for irrigation uses for both aquifers except few wells in the confined aquifer. Also, noted that there are very variations in the irrigation indices results for classifying water quality. The comparison result showed that the new index robust, fair calculations and has best classifying of water quality.

Computational Atom-based Three-Dimensional Quantitative Structure-Activity Relationship (3D QSAR) Model for Predicting Anti-Dengue Agents

2021 ◽  
Vol 16 (10) ◽  
pp. 50-58
Author(s):  
Ali Qusay Khalid ◽  
Vasudeva Rao Avupati ◽  
Husniza Hussain ◽  
Tabarek Najeeb Zaidan
Keyword(s):  
Dengue Fever ◽  
Three Dimensional ◽  
3D Qsar ◽  
Qsar Model ◽  
Quantitative Structure Activity Relationship ◽  
Activity Relationship ◽  
Quantitative Structure ◽  
Contour Maps ◽  
Structure Activity ◽  
Bioactive Ligands

Dengue fever is a viral infection spread by the female mosquito Aedes aegypti. It is a virus spread by mosquitoes found all over the tropics with risk levels varying depending on rainfall, relative humidity, temperature and urbanization. There are no specific medications that can be used to treat the condition. The development of possible bioactive ligands to combat Dengue fever before it becomes a pandemic is a global priority. Few studies on building three-dimensional quantitative structure-activity relationship (3D QSAR) models for anti-dengue agents have been reported. Thus, we aimed at building a statistically validated atom-based 3D-QSAR model using bioactive ligands reported to possess significant anti-dengue properties. In this study, the Schrodinger PhaseTM atom-based 3D QSAR model was developed and was validated using known anti-dengue properties as ligand data. This model was also tested to see if there was a link between structural characteristics and anti-dengue activity of a series of 3-acyl-indole derivatives. The established 3D QSAR model has strong predictive capacity and is statistically significant [Model: R2 Training Set = 0.93, Q2 (R2 Test Set) = 0.72]. In addition, the pharmacophore characteristics essential for the reported anti-dengue properties were explored using combined effects contour maps (coloured contour maps: blue: positive potential and red: negative potential) of the model. In the pathway of anti-dengue drug development, the model could be included as a virtual screening method to predict novel hits.

The structure of haemoglobin. IX. A three-dimensional Fourier synthesis at 5.5 Å resolution: description of the structure

1962 ◽  
Vol 265 (1321) ◽  
pp. 161-187 ◽  
Keyword(s):  
Tertiary Structure ◽  
Three Dimensional ◽  
Sperm Whale ◽  
Anomalous Scattering ◽  
Fourier Synthesis ◽  
Human Haemoglobin ◽  
Contour Maps ◽  
To Come ◽  
Polypeptide Chains ◽  
Sperm Whale Myoglobin

The electron density distribution in the unit cell is calculated at intervals of approximately 2Å and plotted in a series of sections parallel to (010). The contour maps show that haemoglobin consists of four subunits in a tetrahedral array. The subunits are identical in pairs in accordance with the twofold symmetry of the molecule. The two pairs are very similar in structure, and the members of each pair closely resemble the molecule of sperm-whale myoglobin. The four haem groups lie in separate pockets at the surface of the molecule. The positions of the iron atoms are confirmed by comparison of observed and calculated anomalous scattering effects, which also serve to determine the absolute configuration of the molecule. The four subunits found by X-ray analysis correspond to the four polypeptide chains into which haemoglobin can be divided by chemical methods. In horse haemoglobin the amino acid sequence within these chains is still partly unknown, but in human haemoglobin it has already been determined. Comparison of this sequence with the tertiary structure of the chains as now revealed in horse haemoglobin and with the atomic model of sperm-whale myoglobin recently obtained by Kendrew and his collaborators shows many interesting relations. Prolines appear to come where the chains turn corners or where their configuration is known to be non-helical. On the other hand, the chains also have corners which contain no proline. Certain residues appear to be structurally vital, because they appear in identical positions in myoglobin and in the two chains of haemoglobin, while in other parts of the molecule a wide variety of different side-chains appears to be allowed.

scholarly journals Summary on Several Key Techniques in 3D Geological Modeling

2014 ◽  
Vol 2014 ◽  
pp. 1-11 ◽  
Author(s):  
Gang Mei
Keyword(s):  
Mesh Generation ◽  
Spatial Interpolation ◽  
Three Dimensional ◽  
Geological Modeling ◽  
3D Geological Modeling ◽  
Surface Intersection ◽  
Key Techniques

Several key techniques in 3D geological modeling including planar mesh generation, spatial interpolation, and surface intersection are summarized in this paper. Note that these techniques are generic and widely used in various applications but play a key role in 3D geological modeling. There are two essential procedures in 3D geological modeling: the first is the simulation of geological interfaces using geometric surfaces and the second is the building of geological objects by means of various geometric computations such as the intersection of surfaces. Discrete geometric surfaces that represent geological interfaces can be generated by creating planar meshes first and then spatially interpolating; those surfaces intersect and then form volumes that represent three-dimensional geological objects such as rock bodies. In this paper, the most commonly used algorithms of the key techniques in 3D geological modeling are summarized.

scholarly journals Hydrochemical assessment of water quality for irrigation: A case study of the wetland complex of Guerbes-Sanhadja, North-East of Algeria

2018 ◽  
Vol 38 (1) ◽  
pp. 43-52 ◽  
Author(s):  
Sihem Hedjal ◽  
Derradji Zouini ◽  
Abdelwaheb Benamara
Keyword(s):  
Water Quality ◽  
Quality Parameters ◽  
Irrigated Agriculture ◽  
Sodium Absorption ◽  
Sodium Absorption Ratio ◽  
North East ◽  
The Status ◽  
Wetland Complex ◽  
Eastern Algeria ◽  
Irrigation Quality

AbstractThe wetland complex of Guerbes-Sanhadja (north-eastern Algeria), has experienced in recent years a certain economic expansion, particularly agricultural, about 47% of the useful agricultural area marked by several varieties of crops ranging from market gardening to speculative crops, requiring large quantities of water for irrigation purposes, however the swampy areas are the main sources used for irrigation purposes in this practice. It is therefore necessary for this water to have physicochemical properties adapted to plants, in particular the absence of salinity. This study was done to evaluate the status of the swamps areas quality and its suitability for irrigated agriculture. To achieve this objective, water samples from ten swamps areas water were collected from Guerbes-Sanhadja in February and June of 2016. The water quality of these swamps was estimated from different water quality parameters such as pH and electrical conductivity (EC), the chemical parameters like Na+, K+, Ca2+, HCO3−, SO42−, Cl−, BOD5, NO3−, NO2−, NH4+ and PO43−. Based on the physico-chemical analyses, irrigation quality parameters like sodium absorption ratio (SAR), percent sodium (% Na), residual sodium carbonate (RSC), permeability index (PI), magnesium hazard (MH) were calculated. The results showed that the overall concentration of nitrate was very high. About 60 percent of the swampy areas had suitable water quality for chloride, and they had a concentration below the permissible limit for crop irrigation. From the Richards diagram, it is observed that most of the samples from the study area fall in the good to permissible classes for irrigation purpose.

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