High Levels Of Electrical Conductivity Research Articles

Suitability assessment of natural water in relation to irrigation and soil properties

An investigation was carried out using 25 natural water samples from N arayanganj district, Bangladesh to examine the quality of both groundwater and surface water in relation to pollution and the suitability of these waters for irrigation. High concentrations of Na, Ca, Mg, HCO3, and CI ions were recorded in all the tested samples. Significant variations in the values of electrical conductivity (EC), total dissolved solids (TDS), and major ions were observed. Some samples contained high levels of EC (0.184 to 1.624 dS m−1 at 25°C) that revealed the presence of soluble salts which could cause crust formation and seal development of the soil profile due to the chemical and mechanical action of test water, and reduce infiltration rate. The average concentrations of Ca and Mg were 78.15 and 16.55 mg L−1. Higher amounts of Ca and Mg ions contributed to the water hardness in some samples. Sodium adsorption ratio (SAR) and the amount of residual sodium carbonate (RSC) ranged from 0.14 to 4.09 and −7.62 to 0.11 meq L−1, respectively, values within the safety limit. Soluble sodium percentage (SSP) ranging from 6.31 to 64.46, graded as excellent to doubtful. The latter category might be unsuitable for crop production and irrigation. The most serious hazard was represented by the contamination with highly soluble Na that could cause a salinity problem in the soil environment and decrease crop yields.

Potassium Affects Sodium Content in Tomato Plants Grown in Hydroponic Cultivation under Saline-sodic Stress

The tomato cultivars Edkawi and UC 82B (Lycopersicon esculentum Mill.) were grown hydroponically in a solution [electrical conductivity (EC) 2.4 dS·m-1] containing 150 mm Na (EC 11.4 dS·m-1), 37 mm of K (EC 14.1 dS·m-1), or 75 mm of K (EC 19.7 dS·m-1). The leaf Na content of `Edkawi' and `UC 82B' reached values of 1717 and 2022 mmol·kg-1 dry weight at EC 19.7 dS·m-1, respectively. The high levels of K in the hydroponic solution reduced the Na concentration in the roots, petioles, and stems, but not in the leaves. Potassium concentrations in the petioles of `Edkawi' and `UC 82 B' reached values of 2655 and 2966 mmol·kg-1 dry weight, respectively. At these elevated ECs, the Ca concentrations in the leaves of `Edkawi' and `UC 82B' were 30% and 40% lower than in the control, respectively. The elevated rates of K improved the fruit: flower ratio of `UC 82B', but the high salinity of the solution reduced yields significantly. Plant fresh weight and root dry weight of `UC 82B' were most affected by high EC levels. The elevated levels of K used in this study did not increase yield, but K ions can adjust to Na uptake.

Assessing Temporal Variations in Soil Water Composition with Time Domain Reflectometry

AbstractTime domain reflectometry (TDR) can be used to study temporal variations in volumetric soil water content (θ) and bulk soil electrical conductivity (σa). The variations in σa are associated with changes in θ and the soil water composition. Laboratory and field experiments were conducted to verify if TDR can be used to monitor the temporal variation in the soil water composition between solution sampling occasions. Effects of cable length and temperature on the σa measurement were evaluated. Including the series resistance of the cable and connectors in the analysis improves measurements at high electrical conductivity levels. The temperature factor of the bulk soil appears to be similar to the temperature factor of soil extracts. Laboratory experiments showed that the theoretical model giving σa as function of θ and the electrical conductivity of the soil solution (σw) combined with the water retention function was capable of describing σw measured on soil solution extracted with ceramic cup solution samplers under static water flow conditions. After optimization of a single parameter, the model was able to describe σw values of the soil solution obtained in the laboratory, whereas literature values were sufficient for field data. Concentrations of a number of solutes in a field data set spanning 3 yr were positively correlated with σw. Site‐specific regressions between solute concentration and σw combined with automated TDR measurements of σa and θ enable a more meaningful interpretation of the temporal variation of the concentration of major solutes present in the soil solution between sampling occasions.

Influence of Cattle‐Manure Slurry Application on the Solubility of Cadmium, Copper, and Zinc in a Manured Acidic, Loamy‐Sand Soil

AbstractThe concentrations of Cd, Cu, and Zn were evaluated bimonthly in the soil solution of five acidic loamy‐sand soil plots during an 18‐mo period, before and after application of 25 Mg ha−1 cattle‐manure slurry on top of the plots. pH, Cd, Zn, Cu, and Fe concentrations, electrical conductivity (EC), and dissolved organic carbon (DOC) were monitored in the soil‐solution samples extracted from soil down to 80‐cm depth. Dissolved metal concentrations ranged from 9 × 10−7 to 9 × 10−5 mmol m−3 for Cd, from 0.14 to 33 mmol m−3 for Zn, from 0.005 to 5 mmol m−3 for Cu, and from 0.54 to 4.6 × 10−3 mmol m−3 for Fe. Maximum soil solution concentrations of Cd (9 × 10−5 mmol m−3) and Zn (33 mmol m−3) were found between 0‐ and 40‐cm depth 6 wk after cattle‐manure slurry application; Cu and Fe concentrations were not elevated. Except for the peak concentrations of Cd and Zn following the cattle‐manure slurry application, no statistically significant temporal trends in heavy metal concentrations were observed. Multiple linear regression analysis showed a positive correlation between the metal concentrations with DOC and a negative correlation with pH. High EC levels in topsoil layers, resulting from manuring were also found to increase metal concentrations. In the topsoil the Cd and Zn concentrations were affected by soil solution pH, and in the subsoil by DOC variations. The Cu concentration was affected by DOC variations in all soil layers. Supercentrifugation of selected subsoil samples from one sampling date removed 80% of the Cd, Zn, and Cu from the solution along with DOC and Fe. Cation‐exchange column experiments as well as anodic stripping voltammetry measurements (speciation) of selected soil solution samples, showed that 30 to 70% of the dissolved Cu and all Cd was bound in relatively fast dissociating metal complexes. The observed variations in soil solution heavy metal concentration and speciation show that a distribution coefficient that describes the partition of metals over soil solution and solid phase is not a constant but depends on the physicochemical situation.

Counter-ion induced processibility of conducting polyaniline

By using a suitably functionalized acid to protonate the base form of polyaniline, the counter ion can induce processibility of the resulting PANI complex. Thus, polyaniline can be processed in its conducting form from the melt and/or from a wide variety of common organic solvents, such as decalin, xylene, chloroform and m-cresol, etc. The resulting conducting polyaniline can be processed neat or in blends with common, insulating bulk polymers to enable the fabrication of thin films, sheets, fibers, transparent conductive films, bulk parts, etc. These materials exhibit relatively high levels of electrical conductivity at low volume fractions of the polyaniline complex, while maintaining excellent mechanical properties, essentially equivalent to those of the host bulk polymer.

Counter-ion induced processibility of conducting polyaniline and of conducting polyblends of polyaniline in bulk polymers

By using a suitably functionalized protonic acid to protonate polyaniline, the counter ion can induce processibility of the resulting PANI complex. Our results demonstrate the feasibility of processing, in the conducting form, polyaniline and a variety of polyblends made from polyaniline. The resulting conducting polymer materials can be melt-processed or processed from solution to enable the fabrication of thin films, sheets, fibers, transparent conductive films, bulk parts, etc. These materials exhibit relatively high levels of electrical conductivity at low volume fractions of the polyaniline complex, while maintaining excellent mechanical properties, essentially equivalent to those of the host bulk polymer.

Effect of root-zone and air temperature on growth, ornamental value and keepability of Ficus benjamina and Schefflera arboricola ‘Compacta’

Two species of foliage plants were subjected to different root-zone temperatures up to 30°C on heated aluminium benches with a usual greenhouse temperature of 20°C or lower. Elevated root-zone and air temperatures had a promoting effect on growth rates in the beginning of the cultivation period. In the later stages of growth, no effect of the root-zone temperature on growth could be detected. Bench heating with a root-zone temperature of 30°C and an air temperature among the plants of 23–24°C reduced the cultivation time for Schefflera arboricola ‘Compacta’ and Ficus benjamina by 2.5 weeks compared with the lowest temperature of 19°C, while the ornamental value was not unfavourably affected. A large part of the total heating demand can be supplied by bench heating systems as relatively high root-zone temperatures up to 30°C can be used during the whole cultivation period. Bench heating increased the accumulation of salts in the 4-cm top layer of the potting soil. Both crops tolerated high electrical conductivity levels in the top layer, even if salts were rinsed back to the roots by watering on top of the potting soil during post-harvest life.

Radiochemical analysis of ions in hydrocarbons

This study is concerned with hydrocarbons in which by chemical means a high level of electrical conductivity has been obtained. By means of chemisorption of radioactively labeled organic components and metal atoms present it may be established whether these components form part of the cation or the anion. Thus by suitably selecting the components, the composition of the ions may be obtained. In the present study ion-exchange resins and certain metals such as copper and magnesium were used as ionic adsorbers. Carbon 14 labeled benzoic acid and cobalt 60 labeled cobalt chloride were used as components. In the particular system under study, the cation is formed essentially of the organic compound containing a carbonyl; in the absence of dissolved metal this is probably an oxonium ion, in the presence of dissolved metal a metal-complex cation. The anion in that system also contains the organic compound, possibly as an enolate ion.