Solution Electrical Conductivity Research Articles

Study on the Morphology and Fiber Properties of Nanoclay Added Polyvinyl Alcohol (PVA) Nanofibrous Mats: Effect of Mechanical Dispersion

In this study, polyvinyl alcohol (PVA) polymer and Cloisite 15A, a modified form of organo Montmorillonite nanoclay, are used to produce nanofibrous mats via electrospinning technique. Pure PVA nanofibrous mats from mechanically stirred polymeric solutions at 8, 10 and 12 wt % PVA percents; and nanoclay added PVA nanofibrous mat samples are produced at increased nanoclay weight/ polymer weight ratios (1/13, 1/11, 1/9 and 1/6) using several mechanically stirred nanoclay-PVA solutions at various proportions of nanoclay and PVA polymer wt % in solutions. The viscosities, surface tensions and electrical conductivities of solutions were measured. FESEM (Field Emission Scanning Electron Microscopy) analysis, fiber diameter distribution with Image J software analysis and tensile testing was applied to nanofibrous samples. Increased polymer concentration led to bead-free nanofibrous PVA mats. EDX analysis approved nanoclay is present in samples produced from nanoclay added PVA solutions. Mechanical stirring for nanoclay dispersion enabled smooth nanofibrous structures only in low (1/13) nanoclay weight/ polymer weight ratios and showed very little tensile increase from 1 wt % clay loading to 2 wt % addition. A direct increase in tensile strength wasn’t achieved with nanoclay content increase in PVA nanofibrous mats; this might be due to the effect of poor nanoclay distribution adversely affecting tensile results. Morphological analysis proved that nanofibrous structures were far away from smooth fiber structures as they transformed from smooth nanofibers into non-uniform fibrous structures at increased nanoclay weight/ polymer weight ratios in nanoclay added PVA samples. Keywords: nanofibrous mat, electrospinning, polyvinyl alcohol (PVA), nanoclay, mechanical dispersion DOI : 10.7176/CPER/62-08 Publication date: May 30 th 2020

Experimental and mathematical analysis of electroformed rotating cone electrode

In this study, we present results of a mathematical model in which the governing equations of electroforming process were solved using a robust finite element solver (COMSOL Multiphysics). The effects of different parameters including applied current density, solution electrical conductivity, electrode spacing, and anode height on the copper electroforming process have been investigated. An electroforming experiment using copper electroforming cell was conducted to verify the developed model. The obtained results show that by increasing the applied current density, the electroforming process takes place faster, thereby resulting in a higher thickness of the electroformed layer. In addition, higher applied current density led to non-uniformity of the coated layer. It was revealed that by increasing electrolytic conductivity from 5 to 20 S/m, the electroformed layer became thicker. By considering three different anode heights, it was found that if the cathode and anode are the same height, the process will be more effective. Finally, it was concluded that there is an optimum value of anode-cathode spacing: above it, energy consumption and plating time are high; while below it, the resultant layer is non-uniform. The present study demonstrates that the developed model can accurately capture the physics of electroforming with a reasonable computational time.

Hydrogen production by photovoltaic-electrolysis using aqueous waste from ornamental stones industries

Researchers are currently focused on cost reduction (economic and environmental) in the production of hydrogen by coupling the electrochemical system to photovoltaic (PV) panels and using alternative electrolytes, mainly pollutants. The present work aims to use an electrochemical system coupled to PV panels to convert the energy coming from the sun into hydrogen gas, by residual water electrolysis from ornamental stones industries. This study designed a cylindrical electrolytic cell made of acrylic and 304 stainless steel electrodes to hydrogen production. Of tested residues, conventional loom granite electrolyte presented better accumulated hydrogen production, reaching 329 mL after 2 h of experiment, with an average irradiance of 1332 W m2. Cut diamond multiwire granite residue generated 54% less than conventional loom granite electrolyte, due to lower solution electrical conductivity. During experiments, iron ions precipitation in hydroxide form was observed. Overall efficiency for conventional loom granite electrolyte was approximately half the NaOH 2 mol L−1 however; it was 2.7 times larger than diamond multiwire granite electrolyte. It is noteworthy that use of NaOH, for electrolysis is a problem, given high corrosivity and cost of operation.

Physico-chemical and mineralogical characterization of clay materials suitable for production of stabilized compressed earth blocks

The main objective of this study is to characterize the physico-chemical and mineral properties of clay materials from Burkina Faso to produce stabilized compressed earth blocks (CEBs). The reactivity of the clay materials was tested based on the electrical conductivity of solutions and the compressive strength of CEBs stabilized with 0–20 wt% CCR (calcium carbide residue) and cured for 45 days at 40 ± 2 °C. Pabre and Kossodo respectively contain the highest fractions of clay (20–30%) and gravel (40%). Saaba and Pabre contain the highest content of kaolinite (60–70%) and quartz (45–60%) and recorded the highest and lowest reactivity, respectively. The compressive strength of CEBs stabilized with 20% CCR improved tenfold (0.8–8.3 MPa) for Saaba and only 2.6 (2–7.1 MPa) for Pabre. The clay materials in the present study are suitable to produce CCR-stabilized CEBs for load-bearing construction.

Influence of exchangeable sodium and clay mineralogy on soil water retention and hydraulic conductivity

Soil hydraulic properties are important for water management in salt and sodium (Na) affected soils. The soil saturated hydraulic conductivity (K_sat) has been found to decrease when high soil solution Na adsorption ratio (SAR) is coupled with low solution electrical conductivity (EC). Soil clay type plays an important role in changes to soil K_sat when the soil solution composition has a high SAR and low EC. Little is known about how soil water retention changes from solution EC and SAR. The objective of this study was to determine the impact of a range of solution EC and SAR values on soil K_sat, and water retention for soils containing swelling and nonswelling clay minerals. The soil K_sat and water retention were measured on four smectitic soils, a kaolinitic soil, and an illitic soil. Smectite swelling caused large changes in soil hydraulic properties in smectitic soils at high exchangeable Na percentage (ESP) and low EC levels, whereas there was a reduced effect on soils with little smectite clay. Increasing soil solution ESP and decreasing EC level caused the K_sat to decrease and the water content at a given pressure head to increase on soils that contained smectite. A narrower range of EC and SAR of waters suitable for use on smectitic soils are required to prevent changes in soil water flow rates and soil water retention.

Influence of heavy rainfall in 2018-2019 and submerging on some soil properties greenhouse’s in Bazian plain, Sulaymaniyah Governorate

In rain season 2018-2019 Sulaymaniyah governorate has been precluded to rainfall precipitation with very high quantities that never has been recorded since 1985 that impact on some soil properties taking samples from 80 greenhouses in (Tainal watershed, Bazian plain, Sulaymaniyah Governorate). Since in some of these greenhouse waters flood get 1.5m high and others distorted and kinds of residues has been collected in others greenhouses as well as effects of water submerging on these greenhouses soils. Taking soil samples from greenhouses from all locations that effected hardly and making analysis for some properties’ as a parameters and the results showed that the soil solution electrical conductivity (EC) decreased significantly (P<0.05) in ( Location1, Location2, Location6) (1.65dsm-1,0.35dsm-1, 0.25dsm-1 ) respectively. the pH of soils decreased as the results showed (Location1, Location2, Location3) (8.06, 8.31, 7.8) respectively but not significantly, soil aggregate differences had effected significantly and changed in different locations because of removal of the sand part, silt decreased from (% 17.25) in control Location to (5.6 in Location2, 4.1in Location7) but didn’t get to the limit that could change the soil texture. Submergence soils caused decreasing significantly (P<0.05) in phosphorus concentration in (Location1, Location7) (17ppm, 12ppm) respectively. The Concentration of nitrate in soil solution decreased significantly (P<0.05) (Location1, Location7) (2.5mg kg-1, 14mg kg-1) respectively under the submerged condition at field capacity causing an increase in the concentration of potassium (0.743 in Location3 and 4.358 in Location4) in some locations. Sodium increased in most of the locations significantly (P<0.05) (L1, L3, L5, L7) (0.378m mol-1, 0.434m.mol-1, 0.443m.mol-1, 0.643 m.mol-1) respectively otherwise, magnesium and calcium decreased in the soil solution. From the investigation some farmer record that in the study area vegetables grew better after the submerging soils.

Forecasting potato tuber yield using a soil electromagnetic induction method

AbstractTimely forecasting of crop yield is vital for precision agriculture management practices. This study used on‐the‐go proximal soil sensing using electromagnetic induction (EMI) readings of apparent ground electrical conductivity (ECa) to map ECa and forecast potato tuber yield in four fields across Atlantic Canada. The ECa data, measured in the horizontal co‐planar (HCP) configuration mode of the DualEM‐2 instrument, were segmented to the top 0.30‐m thickness of the soil layer using a standard method to compare mapping/prediction accuracy. Results showed that ECa correlated well (R2 = 0.81–0.90) with a 1:5 soil‐to‐water ratio solution's electrical conductivity (EC1:5). The actual tuber yield, which moderately varied (CV = 18.9–27.5%) across the fields and significantly correlated with ECa, explained more than 55% of the yield variability (R2 = 0.57–0.66). The forecasted tuber yield calculated from cubic regression models of the actual tuber yield versus ECa was non‐significantly different from the actual tuber yield (RMSE = 12.2–18.3%; R2 = 0.57–0.66). Interpolated maps of the predicted and the actual yields, and their correlation analyses, showed similar trends of variations within the study fields (r = 0.69–0.80). The higher values of cation exchange capacity, calcium, phosphate, potash, organic matter and soil moisture content in the New Brunswick soils compared to the Prince Edward Island soils resulted in an overestimation of the predicted tuber yield than the actual yield at the lower ECa values, and an underestimation of the predicted tuber yield at higher ECa values for New Brunswick. The results revealed that the province‐based calibrations produced more accurate predictions when compared with the single calibration by combining all of the data from New Brunswick and Prince Edward Island. The non‐destructive prediction of potato tuber yield can enable the development of precision agricultural techniques and management practices for yield forecasting, in addition to making informed decisions for enhanced potato productivity.Highlights Potato cropping is highly important to the economy of Atlantic Canada. The DualEM‐2 sensor was used to forecast and map tuber yield to advance crop management. The tuber yields significantly correlated with ground conductivity that explained >55% of variability in yield. The DualEM‐2 sensor can accurately predict potato yield under agricultural conditions similar to Atlantic Canada.

Increased Drought and Salinity Tolerance in Citrus aurantifolia (Mexican Lemon) Plants Overexpressing Arabidopsis CBF3 Gene

Citrus are a globally important fruit crop. Abiotic stressors such as drought and salinity adversely affect physiological citrus performance and survival. With the aim of improving drought tolerance in citrus plants, we constructed transgenic lines of Citrus lemon overexpressing the Arabidopsis transcription factor CBF3. Molecular, physiological, and quantitative real-time analyses showed high expression of AtCBF3 in three selected transgenic lines. During a 15-day treatment of water deficit by cessation of irrigation, the transgenic lines LM2 and LM14 showed lower stomatal conductance and transpiration paired with lower photosynthesis, whereas transgenic line LM7 maintained its photosynthesis, declining stomatal conductance, and transpiration compared to WT plants, which is manifested into more efficient water use. The genes CsRafS1 and CsGolS1 showed similar or greater expression in one of the transgenic lines with respect to control plants. Moreover, transgenic lines were more tolerant to saline stress and presented a greener phenotype with increased chlorophyll content in leaf discs compared to WT plants. In addition, a lower electrical conductivity in solution was observed in transgenic lines. Furthermore, all transgenic lines exhibited significantly less accumulation of reactive oxygen species than WT plants. Together, these results suggest the potential for heterologous expression of the AtCBF3 gene to mediate tolerance to hydric and saline stress in citrus plants.

Response of Calceolaria ×herbeohybrida Cultivars to Substrate pH and Corresponding Leaf Tissue Nutrient Concentration Effects

Calceolaria (Calceolaria ×herbeohybrida) is a flowering potted greenhouse crop that often develops upper-leaf chlorosis, interveinal chlorosis, and marginal and leaf-tip necrosis (death) caused by cultural practices. The objectives of this research were to 1) determine the optimal incorporation rate of dolomitic and/or hydrated lime to increase substrate pH; 2) determine the influence of the liming material on substrate pH, plant growth, and leaf tissue nutrient concentrations; and 3) determine the optimal substrate pH to grow and maintain during calceolaria production. Sphagnum peatmoss was amended with 20% (by volume) perlite and incorporated with pulverized dolomitic carbonate limestone (DL) and/or hydrated limestone (HL) at the following concentrations: 48.1 kg·m−3 or 144.2 kg·m−3 DL, 17.6 kg·m−3 DL + 5.3 kg·m−3 HL, or 17.6 kg·m−3 DL + 10.6 kg·m−3 HL to achieve a target substrate pH of 4.5, 5.5, 6.5, and 7.5, respectively. Calceolaria ‘Orange’, ‘Orange Red Eye’, ‘Yellow’, and ‘Yellow Red Eye’ were grown in each of the prepared substrates. For all cultivars, substrate solution pH increased as limestone incorporation concentration and weeks after transplant (WAT) increased, although to different magnitudes. For example, as limestone incorporation increased from 48.1 kg·m−3 DL to 17.6 kg·m−3 DL + 10.6 kg·m−3 HL, substrate solution pH for ‘Orange’ calceolaria increased from 4.1 to 6.9 to 4.8 to 7.2 at 2 and 6 WAT, respectively. Substrate solution electrical conductivity (EC) and growth indices were not influenced by limestone incorporation, but total plant dry mass increased. Few macronutrients and most micronutrients were influenced by limestone incorporation. Leaf tissue iron concentrations for ‘Orange’, ‘Orange Red Eye’, ‘Yellow’, and ‘Yellow Red Eye’ calceolaria decreased by 146%, 91%, 71%, and 84%, respectively, when plants were grown in substrates incorporated with increasing limestone concentrations from 144.2 kg·m−3 DL to 17.6 kg·m−3 DL + 10.6 kg·m−3 HL (pH 6.5–6.9). Therefore, incorporating 144.2 kg·m−3 DL into peat-based substrates and maintaining a pH <6.5 will avoid high pH–induced Fe deficiency and prevent upper-leaf and interveinal chlorosis.

Relationship between Electrical Conductivity and Chemical Content of Rat Skeletal Muscle Impregnating Solution and Postmortem Interval.

Objective To study the mechanism of change of the electrical conductivity （EC） of rat skeletal muscle impregnating solution that occurs with the change of postmortem interval （PMI）. Methods Healthy Sprague-Dawley rats were killed and kept at about 25 ℃. Skeletal muscles were extracted at different PMI--immediate （0 d）, 1 d, 2 d, 3 d, 4 d, 5 d, 6 d, and 7 d, then mixed with deionized water to make impregnating solution with a mass concentration of 0.1 g/mL. The solution's EC and nine common chemicals in it, such as potassium ion, calcium ion, and chloride ion, were determined. Results EC increased gradually with the extending of PMI （P=0.024） during the 7 days after the rats' death. The content of uric acid （P=0.032）, urea nitrogen （P=0.013） and phosphorus （P=0.022） also increased during the extension. However, the content of magnesium ions decreased with extending of PMI （P=0.047）. The correlation between potassium ion, sodium ion, chlorine ion, calcium ion, creatinine and PMI were weak （P>0.05）. Conclusion The molecular basis of skeletal muscle EC change in rats after their death is the changes of uric acid, urea nitrogen, inorganic phosphorus and other chemical components. Furthermore, combine use of various indicators can improve the accuracy of the EC method to infer PMI.

Carboxylate Bridge Controlled Formation of Tetra‐ and Pentanuclear Nickel(II) Complexes: Synthesis, Crystal Structure, Spectroscopy and Magnetic Properties

AbstractA carboxyamine functionalized tridentate ligand in combination with three different carboxylate bridging groups (RCO2−; R=CH3, C2H5 and CF3) has been utilized to prepare tetra‐ and pentanuclear nickel(II) complexes, [Ni4(L)2(μ3‐OCH3)2(μ1,1‐O2CCH3)2(μ1,3‐O2CCH3)2(CH3OH)2] (1), [Ni4(L)2(μ3‐OCH3)2(μ1,1‐O2CC2H5)2(μ1,3‐O2CC2H5)2(CH3OH)2] (2) and [Ni5(L)4(μ3‐OH)2(μ1,3‐O2CCF3)2]Br2⋅3H2O (3) (HL=3‐[(2‐pyridylmethyl)‐amino]‐propionic acid). The complexes have been characterized using several techniques such as elemental analysis, solution electrical conductivity, FTIR and UV‐Vis spectroscopy, and low temperature magnetic measurements. While complex 1 and 3 were further characterized using single crystal X‐ray diffraction, molecular structure of complex 2 has been optimized using DFT calculation. Whereas the acetate/propionate groups deliver Ni4 cluster, the trifluoroacetate group provides Ni5 assembly. Molecular structures of complexes 1 and 2 comprise a central [Ni4O6] core that could be described as a distorted face‐shared dicubane with two missing vertices. On the other hand, the [Ni5(μ3‐OH)2(μ1,3‐O2CCF3)2]6+ structural core of complex 3 contains five coplanar nickel(II) ions in a rectangular organization. Variable‐temperature magnetic susceptibility studies reveal the interesting magnetic properties of complexes 1 and 3. While complex 1 shows both ferro‐ and antiferromagnetic interactions with J1=−1.10 cm−1, J2=+2.40 cm−1 and J3=−0.65 cm−1, complex 3 exhibits only ferromagnetic interactions with J1=+2.0 cm−1 and J2=+1.0 cm−1.

Rapid Removal of Poly- and Perfluorinated Compounds from Investigation-Derived Waste (IDW) in a Pilot-Scale Plasma Reactor.

A pilot-scale plasma reactor installed into an 8 × 20 ft2 mobile trailer was used to rapidly and effectively degrade poly- and perfluoroalkyl substances (PFAS) from liquid investigation-derived waste (IDW; development and purge water from monitoring wells) obtained from 13 different site investigations at Air Force installations. In the raw water, numerous PFAS were detected in a wide concentration range (∼10-105 ng/L; total oxidizable precursors (TOP) ∼102-105 ng/L, total fluorine by combustion ion chromatography ∼102 to 5 × 106 ng F/L). The concentration of total PFAS (12 perfluorocarboxylic acids (PFCAs) and perfluoroalkyl sulfonates (PFSAs)) in the 13 samples ranged between 2.7 and 1440 μg/L and the concentration of perfluorooctane sulfonate (PFOS) plus perfluorooctanoic acid (PFOA) ranged between 365 and 73700 ng/L. Plasma-based water treatment resulted in rapid perfluoroalkyl acids (PFAAs) removal from 4 L individual IDW samples with faster rates for longer-chain PFCAs (C ≥ 8) and PFSAs (C ≥ 6) than for PFCAs and PFSAs of shorter chain length. In 9 of the 13 IDW samples, both PFOS and PFOA were removed to below United States Environmental Protection Agency's (USEPA's)health advisory concentration level (HAL)concentrations in <1 min, whereas longer treatment times (up to 50 min) were required for the remaining four IDW samples due to either extremely high solution electrical conductivity, which decreased the plasma-liquid contact area (one IDW sample) or high concentrations of PFAAs and their precursors; the latter was found to be converted to PFAAs during the treatment. Overall, 36-99% of the TOP concentration present in the IDWs was removed during the treatment. There was no effect of non-PFAS co-contaminants on the degradation efficiency. Overall, the results indicate that plasma-based water treatment is a viable technology for the treatment of PFAS-contaminated IDW.

Effects of electric conductivity and plant density on lettuce baby leaf production in NFT hydroponic system

The baby leaf market is at its beginning in Brazil, but in some European countries and in the United States the market is already established. Similar to the market, production systems are starting to be established in Brazil. Thus, they need to be studied in order to gain knowledge of how to produce baby leaf in each production system. Some farmers who grow leafy vegetables in nutrient film technique (NFT) hydroponic system are adapting their systems to grow baby leaf, but without the technical support provided by research. Therefore, to find answers on how to produce baby leaf in NFT hydroponic systems, the intention of the present study was to verify the effect of nutrient solution electrical conductivity (0.4, 0.8, 1.2 and 1.6 mS cm(‑1) and the distance between plants (2.5, 5.0 and 10.0 cm) on development and yield of lettuce cultivar 'Vera'. The experiments were carried out in a nutrient film hydroponic system inside a greenhouse in the period of February to March 2012. The experimental design used was a split plot with randomized blocks replicated four times. There was no significant interaction among treatments, however, there were statistical effects for the treatments separately. The higher yield of 3.1 kg m(‑2) were obtained at 1.4 mS cm(‑1). The distance between plants of 2.5 cm promoted higher yield of 4.9 kg m(‑2).

Relationship between Electrical Conductivity and Related Biochemical Indicators of Rat Cerebrum Tissues and Postmortem Interval.

Objective To explore the relationship between the electrical conductivity （EC） and biochemical indicators of rat cerebrum tissues and postmortem intervals （PMIs） and discuss the mechanism of applying EC to infer PMI. Methods Forty healthy Sprague-Dawley rats were sacrificed and stored in an environment of about 25 ℃. The whole cerebrum tissues of rats were removed respectively at different PMIs of 0, 1, 2, 3, 4, 5, 6, and 7 d, and then made into homogenized impregnation solution. The EC and related biochemical indicators （potassium, sodium, chloride, calcium, inorganic phosphorus, magnesium, uric acid, urea nitrogen and creatinine） in cerebrum tissue impregnation solution were determined, and the relationships among EC in impregnation solution, related biochemical indicators and PMI were analyzed. Results The EC in cerebrum tissues increased gradually with the extension of PMI, and the content of uric acid, urea nitrogen and inorganic phosphorus in its impregnation solution also increased gradually with the extension of PMI. The correlation of EC, uric acid, urea nitrogen, and inorganic phosphorus with PMI was relatively good （R2 was 0.95-0.99）, and there was a linear correlation between the content change of uric acid, urea nitrogen, inorganic phosphorus and EC （R2 was 0.97-0.99）. The changes of the other 6 kinds of biochemical indicators with the extension of PMI within 7 d after the rats' death were non-significant （P>0.05）. Conclusion The correlation between EC in cerebrum tissues, uric acid, urea nitrogen, inorganic phosphorus and PMI were relatively good, and combining various indicators can also improve the accuracy of PMI estimation.

Nutrient Solution Strength Does Not Interact with the Daily Light Integral to Affect Hydroponic Cilantro, Dill, and Parsley Growth and Tissue Mineral Nutrient Concentrations

Our objectives were to quantify the growth and tissue mineral nutrient concentrations of cilantro (Coriandrum sativum ‘Santo’), dill (Anethum graveolens ‘Fernleaf’), and parsley (Petroselinum crispum ‘Giant of Italy’) in response to nutrient solution electrical conductivity (EC) under low and high photosynthetic daily light integrals (DLI). Three-week old seedlings of cilantro, dill, and parsley were transplanted into nutrient-film technique hydroponic systems with one of five nutrient solution EC treatments (0.5, 1.0, 2.0, 3.0, or 4.0 dS·m−1) in greenhouses under a low (~7.0 mol·m−2·d−1) or high (~18.0 mol·m−2·d−1) DLI. The DLI, but not nutrient solution EC, affected culinary herb growth. For example, fresh mass increased by 21.0 (154%), 17.1 (241%), or 13.3 g (120%) for cilantro, dill, and parsley, respectively, for plants grown under high DLI compared to those grown under a low DLI; dry mass followed a similar trend. Tissue nutrient concentrations were generally affected by either DLI or EC. For those nutrients affected by DLI, concentrations increased with increasing DLI, except for potassium (K; all species) and manganese (Mn; dill). For those nutrients affected by EC, Ca and Mg decreased with increasing EC, while the remaining increased with increasing EC. When our tissue nutrient data are compared to recommended tissue concentrations, the vast majority of elements were either within or above recommended tissue ranges for cilantro, dill, and parsley. Our results demonstrate cilantro, dill, and parsley can be successfully grown across a range of EC, regardless of the light intensity of the growing environment.

Laboratory Calibration of TDR Probes for Simultaneous of Measurements Soil Water Content and Electrical Conductivity

ABSTRACTAccurate measurement of water content (θ), apparent electrical conductivity (ECa) of soils, and soil solution electrical conductivity (ECw) is critical for a better management of irrigation water and the effective monitoring and control of soil salinity. In this paper, we demonstrate the design and validation of an identical time domain reflectometry (TDRWO) probe for accurate and non-destructive measurements of ECw. Two calibration functions were used to determine the soil-water content by TDR. Theses relations were verified by laboratory experiment over a wide range of θ and bulk density (BD) for dune sand. The exact length and the impedance of all TDR-probes were calibrated using the WinTDR procedure. Estimates of ECw were based on θ and the bulk ECa using a special modeling approach which applies long-time TDR waveform analysis. The geometrical disposition of the matrix phase factors (τ and β) was calculated by immersing the TDR probe in sodium chloride (NaCl) solutions of different electrical conductivities in pressure cells wetted and drained with each of these NaCl solutions. The reliability of the TDRWO was validated/proven under laboratory conditions. The laboratory experiment consisted in inserting the TDR probe into a pressure cell packed with mixed sand and 2-mm sieved loam soil that was subsequently wetted and drained with different NaCl solutions at various pressure heads. The ECw estimated by TDRWO was compared to the ECw measured in the draining solutions after they stabilized in the soil porous system. The τ and β factors calculated for the ceramic disks sets were 1.991 and 4.312, respectively. In the laboratory experiments, high and therefore significant correlations (R2 = 0.986; P < .001) were found between the ECw estimated by the TDRWO and the corresponding ECw values measured in the column-drainage. These results demonstrate that the TDRWO is an instrument which allows researchers to accurately estimate soil solution salinity independently of the soil water content and the porous medium in which the TDR probe is installed. Test results showed that the TDR method has high accuracy for monitoring soil water content but is less accurate in monitoring soil electrical conductivity across a water content range of about ≤0.03cm3/cm3. Regression analysis between TDR-Volumetric water content (ϴv) and weighing method – ϴv showed good correlation with an R2 of 0.97 and 0.98 during two laboratory experiments.

Quantitative evaluation of soil ion content using an imaginary part model of soil dielectric constant

An imaginary part model of soil dielectric constant for predicting the soil salinity status was developed based on a series of relations between dielectric imaginary part and soil bulk conductivity, soil bulk conductivity and soil solution electrical conductivity, and soil solution electrical conductivity and ion contents in soil using pot trials with different soil salinity levels in the 2008 growing season. This model was calibrated and tested with data from the 2009 growing season. The results showed that the inverted values of the total concentration of salt (Sc), Cl−, and Ca2+ at low frequencies (P-band of microwave observations) from the imaginary part model fitted well with the observed values, since root mean square errors (RMSEs) were 0.34 g kg−1, 0.09 g kg−1 and 0.13 g kg−1, respectively, but the inversion effect of Na+ was relatively poor. Moreover, the Sc, Cl−, and Na+ could be well inverted at high frequencies (C-band of microwave observations), since RMSEs were minor, with values of 0.25 g kg−1, 0.02 g kg−1, and 0.15 g kg−1, respectively. The close fit between the observed and inverted values indicated that the present models could be used to estimate soil ion content quickly and reliably under different saline conditions, which, when suitable measures are taken, can be used to reduce the effects of soil salinity on crop growth.

Resource-Saving Technology of Wastewater Treatment of Factories of Reinforced Concrete

A low-waste resource-saving technology for wastewater treatment from emulsified contaminants at the construction industry enterprises was developed. The technology allows reusing purified water, processing organic pollutants into secondary raw materials.Laboratory and industrial tests were carried out. The experimental data were obtained with the use of instruments, equipment, providing the required accuracy, reliability of the measurement results, processed using the mathematical statistics of experiment planning, confirmed by implementation in production.The conditions for the destruction of water-organic emulsions by a constant electric current in a device with insoluble anodes have been studied. The main factors were identified and analyzed: electrode material, solution electrical conductivity, current density, electrolyte composition, hydrogen value, temperature and processing time. The optimal parameters of the purification process are established. The kinetics of the process has been studied. A probabilistic mechanism for the destruction of emulsified organic substances in the investigated medium is presented.On the experimental unit, the operations of averaging, sedimentation, electrochemical treatment, secondary sedimentation and the return of purified water to the technological cycle were worked out and introduced into production. The technological regulations were developed.

Water relations of chives in function of salinity and circulation frequency of nutrient solutions

ABSTRACT Hydroponic cultivation using saline waters is an alternative for agricultural production, especially in the cultivation of vegetables. Therefore, the present work was conducted with the objective of evaluating the water consumption, water use efficiency and water content, as well as dry matter partitioning of chives (Allium schoenoprasum), cv. Todo Ano Evergreen – Nebuka exposed to six levels of nutrient solution salinity (1.5, 3.0, 4.5, 6.0, 7.5 and 9.0 dS m-1), applied at two circulation frequencies (twice a day at 8 and 16 h; and three times a day - at 8, 12 and 16 h). The level in the nutrient solution reservoir, which decreased according to the water consumption by plants, was replaced with the respective saline water (Experiment I) and supply water (Experiment II). Both experiments used a completely randomized design, in a 6 x 2 factorial scheme, with five replicates. It was observed that increased circulation frequency and the use of supply water in the replacement mitigated the effects of salinity on water consumption, water use efficiency and water content in the plant. However, with the increase in nutrient solution electrical conductivity, dry matter allocation in the roots increased, to the detriment of the shoots.

Phosphorus availability and soybean growth in contrasting Oxisols in response to humic acid concentrations combined with phosphate sources

ABSTRACTHumic acid (HA) use can improve phosphorus (P) availability in soils with high P fixation capacity. The aim of this study was to evaluate soil P availability and soybean growth in both medium-texture (MT) and clayey (CL) Oxisols under humic acid carbon (C-HA) concentrations: 0, 5, 10, 50 and 100 mg kg−1, combined with Araxá phosphate rock (APR) and single superphosphate (SS). Mixtures of C-HA with P sources were incubated for 15 d. In sequence, the soil solution was extracted and analyzed for soil solution C (SSC), soil solution P (SSP) and soil solution electrical conductivity (EC). Soil initial resin-P and pH were determined before soybean sowing and, after harvest, shoot (SDM), root (RDM), total dry matter (TDM), soil residual resin-P and soil pH were determined. In CL fertilized with SS, the addition of C-HA increased SSP by 17%, residual resin-P by 42%, SDM, P and N accumulated in the shoot. Addition of C-HA reduced SSP and initial resin-P in MT treated with SS and increased in 18% residual resin-P in MT fertilized with APR. Effects of HA on soil attributes, soybean growth and nutritional status rely on HA concentration, soil texture and P source used.