Influence of sodium adsorption ratio on sodium and calcium breakthrough curves and hydraulic conductivity in soil columns

Soil Research ◽  
2007 ◽  
Vol 45 (8) ◽  
pp. 586 ◽  
Author(s):  
Oagile Dikinya ◽  
Christoph Hinz ◽  
Graham Aylmore
Keyword(s):  
Hydraulic Conductivity ◽  
Electrolyte Concentration ◽  
Soil Aggregates ◽  
Breakthrough Curves ◽  
Sodium Adsorption Ratio ◽  
Threshold Concentration ◽  
Critical Threshold ◽  
Soil Columns ◽  
Clay Particles ◽  
The Matrix

The paper examines the effects of electrolyte concentration and sodium adsorption ratio (SAR) on the relative saturated hydraulic conductivity (RHC) and the ionic behaviour of calcium (Ca) and sodium (Na) ions in the Na–Ca exchange complex. Batch binary exchange and saturated column transport experiments were carried out to quantify these effects using an agricultural Balkuling soil and a mining residue. Generally, RHC has been found to decrease with time, with increasing SAR, and with decreasing electrolyte concentration. The more rapid decrease in RHC in the mining residue, particularly at the lowest concentration (1 mmol/L), was consistent at all SAR values. The decreases in RHC were likely to be caused by partial blocking of pores by dispersed clay particles, as evidenced by the appearance of suspended clay particles in the effluent during leaching. Significant differences in RHC were observed in the passage of fronts of decreasing electrolyte concentrations for CaCl2 and SAR 15 solutions through the soil columns. These differences were attributable to structural alterations (slaking) of the media and the nature of the particles released and mobilised within the porous structure at any given point in the column. Measurements at the critical threshold concentration and turbidity concentration at SAR 15 revealed structural breakdown of the pore matrix system as evidenced by decreased RHC. The increase in SAR to 15 is initially accompanied by erratic RHC, presumably due to the break up of soil aggregates under the increased swelling forces. The less coherent mining residue soil was substantially more vulnerable to blockage of pores than the Balkuling soil in which clay particles are likely to be more readily mobilised, and hence available to re-deposit and occlude the matrix pores.

CALCULATION OF HYDRAULIC CONDUCTIVITY DECREASES IN THE PRESENCE OF MIXED NaCl-CaCl2 SOLUTIONS

1978 ◽  
Vol 58 (2) ◽  
pp. 145-152 ◽  
Author(s):  
J. H. DANE
Keyword(s):  
Hydraulic Conductivity ◽  
Electrolyte Concentration ◽  
Solid Phase ◽  
Particle Density ◽  
Sodium Adsorption Ratio ◽  
Soil Porosity ◽  
Swelling Soils ◽  
Swelling Model ◽  
Good Agreement ◽  
Swelling Factor

A model was developed to calculate hydraulic conductivity decreases in swelling soils in the presence of mixed NaCl-CaCl2 solutions. A calculated swelling factor, based on a demixed-ion clay swelling model, was used to compute an effective soil porosity corresponding to each electrolyte solution. The procedure required knowledge of the total electrolyte concentration (C) and sodium adsorption ratio (SAR) of the solution phase, and of the fraction of expansible minerals, the bulk density, and the particle density of the solid phase. The calculated effective soil porosities were used to predict hydraulic conductivity values corresponding to solutions of decreasing C or increasing SAR values. A hydraulic conductivity value, corresponding to a solution which suppressed all swelling, had to be experimentally determined in order to make the prediction. Good agreement was found between predicted and experimental hydraulic conductivity values for two soils containing different amounts of expansible minerals and subjected to salt solutions of varying compositions.

Use of gamma emission computed tomography to study the effect of electrolyte concentration on regions of preferred flow and hydraulic conductivity in deep regolith materials

Soil Research ◽  
2008 ◽  
Vol 46 (2) ◽  
pp. 101 ◽  
Author(s):  
M. L. Turner ◽  
R. S. B. Greene ◽  
M. Knackstedt ◽  
T. J. Senden ◽  
A. Sakellariou ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Fluid Flow ◽  
Hydraulic Conductivity ◽  
Pore Structure ◽  
Electrolyte Concentration ◽  
Sodium Adsorption Ratio ◽  
Emission Computed Tomography ◽  
Saline Aquifer ◽  
Gamma Emission ◽  
Emission Computed

Understanding fluid flow, displacement, and mixing processes in natural porous media is fundamentally dependent upon the accurate characterisation of complex 3-dimensional structures. This current study delineated the distribution of conducting regions within a suite of regolith materials as they interacted with electrolyte solutions of different concentrations. Previous studies on the effects of electrolyte concentration on clay swelling and dispersion and the concomitant changes in pore structure, and hence soil permeability, have mainly been carried out on repacked samples of disturbed surface soils. This study used unconsolidated materials recovered as undisturbed cores from a saline aquifer from the deeper regolith (8.0–55.8 m). Progressive dilution of the electrolyte concentration of the percolating fluid (while maintaining a constant sodium adsorption ratio) was used to alter the pore structure of these saturated regolith materials. The electrolyte concentration was reduced from an initial value of 383 m.e./L (the original electrolyte concentration of the saline aquifer) to below the threshold concentration, and finally the cores were rinsed with deionised water. The corresponding changes to the regions conducting fluid and therefore pore structure, and the major fluid pathways followed during the percolation process, were imaged using gamma emission computed tomography. Five experimental core samples from depths of 8, 28, 30 (×2), and 55 m were used in the experiments. The average hydraulic conductivity was measured and found to decrease as a function of electrolyte concentration. The regions containing the major fluid pathways were found to decrease in volume as a function of electrolyte concentration. Clay mineralogy, sodium adsorption ratio, and grain size characteristics were found to be positively correlated with reductions in the average hydraulic conductivity. This method has the potential to aid in our understanding of the fundamental processes that govern the dynamics of pore structure changes and hence fluid flow in porous regolith materials, particularly in relation to changes in the electrolyte concentration and sodium adsorption ratio of the pore fluid. Such data will add significantly to our understanding of factors that affect the hydraulic properties of regolith materials under saline/sodic conditions.

scholarly journals Imazapic interaction and mobility in soil cultivated with sugarcane in northeast Brazil

RBRH ◽  
2021 ◽  
Vol 26 ◽  
Author(s):  
Fernando Xavier de Assis ◽  
André Maciel Netto ◽  
Bruno Toríbio de Lima Xavier ◽  
Valmir Felix de Lima ◽  
João Paulo Siqueira da Silva
Keyword(s):  
Partition Coefficients ◽  
Biological Effects ◽  
Clay Content ◽  
Breakthrough Curves ◽  
Northeastern Brazil ◽  
Adsorption Potential ◽  
Soil Columns ◽  
Leaching Potential ◽  
Physical Chemical ◽  
Sorption Leaching

ABSTRACT In the plantation of sugarcane, Imazapic has used pre- or post-emergence, alone or in combination with other herbicides. When applied to the soil in pre-emergence, Imazapic can undergo the sorption, leaching and/or degradation processes due to physical, chemical and biological effects, besides being absorbed by weeds. The objective of this work was to evaluate the interaction and mobility of the Imazapic herbicide in the soil where the soil columns with a dystrophic Yellow Ultisol (YUd) and a dystrophic Red-Yellow Oxisol (RYOd) from northeastern Brazil were used. The higher adsorption potential of the RYOd is associated with higher clay content, higher Fed and Feo concentrations, and soil acidic pH. The CDE – 2 sorption sites model adequately represented the experimental data from the Imazapic breakthrough curves to the RYOd and YUd soils. From the Kd partition coefficients for RYOd and YUd, high values of the GUS index (5.94 and 7.04, respectively) were calculated, confirming the high leaching potential of the Imazapic molecule in these soils.

scholarly journals Limits of seed germination of phytomeliorants under conditions of heavy metals toxic concentrations

2019 ◽  
Vol 8 (1) ◽  
pp. 82-86
Author(s):  
Anastasia Olegovna Oznobihina
Keyword(s):  
Heavy Metal ◽  
Contaminated Soils ◽  
Experimental Studies ◽  
Threshold Concentration ◽  
Leguminous Plant ◽  
Critical Threshold ◽  
Toxic Agent ◽  
Germination Energy ◽  
Lead Zinc ◽  
The Impact

The aim of the study is to conduct biological testing at the initial stages of plant objects viability in the model conditions of heavy metal pollution. The paper presents the results of laboratory experiments to assess the impact of different concentrations of heavy metal salts on the viability of yellow melilot and great trefoil seeds. In the course of the conducted experimental studies the author has been established a direct dependence of the decrease in the indices of germination energy and laboratory germination of seeds with an increase in the concentration of phytotoxicant salts, determined the critical (threshold) concentration of the studied elements and the metal content, in which the processes of growth and development of seeds remain. The concentration of 0,01% cadmium, zinc, lead and copper was optimal for germination of melilot seeds, where germination was equal to 80%, 74%, 69% and 64%, respectively. For great trefoil seeds, high germination rates were noted in case of 0,01% contamination with lead, zinc, cadmium and copper - 82%, 80%, 77% and 76%, respectively, and in 0,1% salt solution of lead, copper and zinc there were recorded 75%, 74% and 72% of seedlings. Zinc in the concentration of 0,01% at the initial stages of germination of phytomeliorant seeds stimulated germination energy. The tendency of resistance to pollution by lead, zinc and copper was observed at sprouts of a great trefoil, and to pollution by cadmium the greatest resistance was shown by a melilot yellow. Defining the limits of the leguminous plant seeds germination in the presence of a toxic agent will allow research and development in respect of biological restoration of contaminated soils and can be used in technologically disturbed lands.

scholarly journals INFLUENC OF IRRIGATION PERIODS AND ORGANIC FERTILIZER ON SOIL PHYSICAL CHARACTERIZATION UNDER THE SYSTEM OF RICE INTENSIFICATION (SRI)

2017 ◽  
Vol 48 (3) ◽  
Author(s):  
Al-Hasanie & Al-Maadhedi
Keyword(s):  
Hydraulic Conductivity ◽  
Average Rate ◽  
Day Treatment ◽  
Soil Aggregates ◽  
Organic Fertilizer ◽  
Irrigation Schedule ◽  
System Of Rice Intensification ◽  
Research Station ◽  
Irrigation Interval ◽  
Rice Intensification

A field trial was conducted at Al-Mishkhab Rice Research Station at Najaf province during 2015 rice season to assess the effects of irrigation periods and organic manure on soil physical properties under System of Rice Intensification The experiment was conducted using split   split plot arrangement with RCBD design with three replicates. The main plots were irrigation schedule where practiced: daily and intermittent water application where irrigation water was at two different intervals 3, 5 day. The sub plots were varieties (anber33,jasmin) and three amount of organic manures 0, 5, 10 ton.haˉ¹, planted under System of Rice Intensification (SRI) compared with conventional method. The results indicated that superiority of irrigation interval 3 day treatment with 10 ton.haˉ¹ In the attribute of soil density and total soil porosity, as this treatment gave the  average in the bulk density 1.24 Mg m-3  compare with fertilization treatment with irrigation 3 days intervals, which gave an average of less than 1.39 Mg m-3, as well as the treatment excelled in the  total porosity of the soil as it gave the highest average 50.18 %, while the comparison gave the lowest percentage of soil aggregate reached 13.00 %. In irrigation 3 days interval and 10 ton.haˉ¹ of organic matter led to increased values of available water to 0.331 cm3.cm -3 compared with a sample before planting, which gave an average of less than 0.193 cm3.cm-3. Given the treatment of interaction between the irrigation 3 days intervals and fertilization treatment recorded the lowest average porosity 48.13 %. The high percentage of soil aggregates, was with the treatment irrigation 3 days interval on the highest average rate of 57.00 % compared with the comparison treatment fertilization and daily irrigation, which 10 ton.haˉ¹ quantities highest average for the hydraulic conductivity reached 0.1320 cm . min-1 compared with the treatment of fertilizing comparison and irrigation daily which gave the lowest average saturated hydraulic conductivity reached 0.0577 cm . min-1.

INFLUENCE OF AMMONIUM ON THE BEHAVIOR OF CLAY PARTICLES IN A SODIC SOIL AND BENTONITE

1974 ◽  
Vol 54 (1) ◽  
pp. 39-44 ◽  
Author(s):  
J. C. VAN SCHAIK ◽  
R. R. CAIRNS
Keyword(s):  
Hydraulic Conductivity ◽  
Beneficial Effect ◽  
Salt Concentration ◽  
Soil Type ◽  
Water Movement ◽  
Ammonium Salts ◽  
Sodic Soil ◽  
Clay Particles ◽  
Mobility Studies ◽  
Solonetz Soil

The addition of ammonium salts increased the hydraulic conductivity of samples taken from the Bnt horizon of a Solonetz soil. The improved conductivity was caused by an increase in the salt concentration in the soil solution and by the ammonium adsorbed on the clay particles. Since the dominant clay mineral in this soil type is montmorillonite, purified bentonite was used for comparative studies. Mobility studies of montmorillonite systems indicated that the adsorbed NH4 ions are tightly bound to the clay particles. The size of the NH4-tactoids was found to be larger than that of the Na-tactoids but less than half that of the Ca-tactoids. It was concluded that the beneficial effect of ammonium on water movement in Solonetz soils will be less than that of calcium, but the transformation of the adsorbed ammonium in the field, followed by replacement of sodium by hydrogen, may result in further improvement of these soils.

scholarly journals Travel-time-based thermal tracer tomography

2016 ◽  
Vol 20 (5) ◽  
pp. 1885-1901 ◽  
Author(s):  
Márk Somogyvári ◽  
Peter Bayer ◽  
Ralf Brauchler
Keyword(s):  
Hydraulic Conductivity ◽  
Grid Method ◽  
Early Time ◽  
Thermal Conditions ◽  
Breakthrough Curves ◽  
Injection Rate ◽  
Staggered Grid ◽  
Travel Times ◽  
Data Set ◽  
Technical Parameters

Abstract. Active thermal tracer testing is a technique to get information about the flow and transport properties of an aquifer. In this paper we propose an innovative methodology using active thermal tracers in a tomographic setup to reconstruct cross-well hydraulic conductivity profiles. This is facilitated by assuming that the propagation of the injected thermal tracer is mainly controlled by advection. To reduce the effects of density and viscosity changes and thermal diffusion, early-time diagnostics are used and specific travel times of the tracer breakthrough curves are extracted. These travel times are inverted with an eikonal solver using the staggered grid method to reduce constraints from the pre-defined grid geometry and to improve the resolution. Finally, non-reliable pixels are removed from the derived hydraulic conductivity tomograms. The method is applied to successfully reconstruct cross-well profiles as well as a 3-D block of a high-resolution fluvio-aeolian aquifer analog data set. Sensitivity analysis reveals a negligible role of the injection temperature, but more attention has to be drawn to other technical parameters such as the injection rate. This is investigated in more detail through model-based testing using diverse hydraulic and thermal conditions in order to delineate the feasible range of applications for the new tomographic approach.

Correction of zinc and boron deficiencies and control of phytophthora root rot of avocardo by trunk injection

1991 ◽  
Vol 31 (4) ◽  
pp. 575 ◽  
Author(s):  
AW Whiley ◽  
KG Pegg ◽  
JB Saranah ◽  
PW Langdon
Keyword(s):  
Root Rot ◽  
Growing Season ◽  
Zinc Nitrate ◽  
Threshold Concentration ◽  
Persea Americana ◽  
Critical Threshold ◽  
Phytophthora Root Rot ◽  
Zinc Concentrations ◽  
Trunk Injection ◽  
And Control

Phosphonate at 3 concentrations (7.5, 10 and 20%) was injected into the trunks of avocado (Persea americana Mill.) trees showing advanced symptoms of canopy decline caused by phytophthora root rot. All formulations of phosphonate and potassium phosphonate, including the lower rates of 7.5 and 10%, successfully controlled root rot and resulted in improved tree health. The 7.5% phosphonate treatment permitted the formulation of chemically compatible mixtures containing zinc and boron which, when trunk-injected, increased the concentrations of these nutrients in mature summer-grown leaves. Phosphonate formulations containing 17% zinc chelate or 10% zinc nitrate and injected twice during a growing season, at 15 mL/m canopy diameter, increased leaf zinc concentrations above the critical level of 30 mg/kg DM. However, the inclusion of zinc chelate in formulations substantially increased the time of uptake of the injection compared with the formulation containing zinc nitrate. Phosphonate formulations with 0.9% boron, injected twice during a growing season at 15 mL/m canopy diameter, improved leaf boron concentrations, but they failed to reach the critical threshold concentration of 50 mg/kg DM.

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