scholarly journals Solute Transport through a Pine Bark-based Substrate under Saturated and Unsaturated Conditions

2014 ◽  
Vol 139 (6) ◽  
pp. 634-641 ◽  
Author(s):  
Tyler C. Hoskins ◽  
James S. Owen ◽  
Jeb S. Fields ◽  
James E. Altland ◽  
Zachary M. Easton ◽  
...  
Keyword(s):  
Solute Transport ◽  
Relative Concentration ◽  
Breakthrough Curves ◽  
Transport Processes ◽  
Pine Bark ◽  
Mineral Nutrient ◽  
Use Efficiency ◽  
Container Nurseries ◽  
Mineral Soils ◽  
Horticultural Research

An understanding of how dissolved mineral nutrient ions (solutes) move through pine bark substrates during the application of irrigation water is vital to better understand nutrient transport and leaching from containerized crops during an irrigation event. However, current theories on solute transport processes in soilless systems are largely based on research in mineral soils and thus do not necessarily explain solute transport in soilless substrates. A study was conducted to characterize solute transport through a 9 pine bark:1 sand (by volume) substrate by developing and analyzing breakthrough curves (BTCs). Columns filled with pine bark substrate were subjected to the application of a nutrient solution (tracer) and deionized water under saturated and unsaturated conditions. Effluent drained from the columns during these applications was collected and analyzed to determine the effluent concentration (C) of the bulk ions in solution through electrical conductivity (EC) and nitrate (NO3–), phosphate, and potassium (K+) concentrations. The BTCs were developed by plotting C relative to the concentration of the input solution (Co) (i.e., relative concentration = C/Co) as a function of the cumulative effluent volume. Solutes broke through the column earlier (i.e., with less cumulative effluent) and the transition from C/Co = 0 to 1 occurred more abruptly under unsaturated than saturated conditions. Movement of the anion, NO3–, through the substrate was observed to occur more quickly than the cation K+. Throughout the experiment, 37% of the applied K+ was retained by the pine bark. The adsorption of K+ to pine bark cation exchange sites displaced calcium (Ca2+) and magnesium (Mg2+), of which the combined equivalent charge accounted for 43.1% of the retained K+. These results demonstrate the relative ease that negatively charged fertilizer ions could move through a pine bark substrate while solution is actively flowing through substrate pores such as during irrigation events. This approach to evaluating solute transport may be used in horticultural research to better understand how mineral nutrients move through and subsequently leach from soilless substrates during irrigation. Expanding this knowledge base may lead to the refinement of production practices that improve nutrient and water use efficiency in container nurseries.

scholarly journals SOLUTE TRANSPORT MODELLING IN LOW-PERMEABILITY HOMOGENEOUS AND SATURATED SOIL MEDIA

2021 ◽  
Vol 36 (2) ◽  
pp. 25-32
Author(s):  
Muhammad Zaheer ◽  
Hadayat Ullah ◽  
Saad Ahmed Mashwani ◽  
Ehsan ul Haq ◽  
Syed Husnain Ali Shah ◽  
...  
Keyword(s):  
Solute Transport ◽  
Preferential Flow ◽  
Relative Concentration ◽  
Breakthrough Curves ◽  
Saturated Soil ◽  
Low Permeability ◽  
Transport Modelling ◽  
Variation Of Parameters ◽  
Solute Transport Modeling ◽  
Soil Media

Fickian and non-Fickian behaviors were often detected for contaminant transport activity owed to the preferential flow and heterogeneity of soil media. Therefore, using diverse methods to measure such composite solute transport in soil media has become an important research topic for solute transport modeling in soil media. In this article, the continuous-time random walk (CTRW) model was applied to illustrate the relative concentration of transport in low-permeability homogeneous and saturated soil media. The solute transport development was also demonstrated with the convection-dispersion equation (CDE) and Two Region Model (TRM) for comparison. CXTFIT 2.1 software was used for CDE and TRM, and CTRW Matlab Toolbox v.3.1 for the CTRW simulation of the breakthrough curve. It was found that higher values of determination coefficient (R2) and lower values of root mean square error (RMSE) concerning the best fits of CDE, TRM, and CTRW. It was found that in the comparison of CDE, TRM, and CTRW, we tend to use CTRW to describe the transport behavior well because there are prevailing Fickian and non-Fickian transport. The CTRW gives better fitting results to the breakthrough curves (BTCs) when β has an increasing pattern towards 2.00. In this study, the variation of parameters in three methods was investigated and results showed that the CTRW modeling approach is more effective to determine non-reactive contaminants concentration in low-permeability soil media at small depths.

scholarly journals Water Content of a Pine-bark Growing Substrate in a Drying Mineral Soil

HortScience ◽  
2004 ◽  
Vol 39 (3) ◽  
pp. 591-594 ◽  
Author(s):  
Anne-Marie Hanson ◽  
J. Roger Harris ◽  
Robert Wright ◽  
Alex Niemiera ◽  
Naraine Persaud
Keyword(s):  
Water Relations ◽  
Mineral Soil ◽  
Pine Bark ◽  
Landscape Plants ◽  
Water Plant ◽  
Adjacent Soil ◽  
Plant Available Water ◽  
Soil Volume ◽  
Container Nurseries ◽  
Mineral Soils

Newly transplanted container-grown landscape plants are reported to require very frequent irrigation. However, container nurseries in the U.S. commonly use growing substrates that are mostly bark, even though the contribution of bark-based growing substrates to water relations of transplanted root balls is unknown. Therefore, a field experiment was undertaken to determine water relations of a pine-bark substrate (container removed) within a drying mineral soil over a three week period. A range of common production container sizes—3.7 L (#1), 7.5 L (#2), 21.9 L (#7), 50.6 L (#15), and 104.5 L (#25)—was used. The fraction of substrate volume that is water [total volumetric water (TVW)] within the top and middle zones of substrate was compared to TVW at corresponding depths of adjacent mineral soil. The fraction of substrate and soil volume that is plant-available water [plant-available volumetric water (PAVW)] was calculated by subtracting the fraction of substrate or soil volume below where water is unavailable to most plants (measured with pressure plates) [plant-unavailable volumetric water (PUVW)] from each TVW measurement. The pine-bark substrate had a PUVW of 0.32 compared to a PUVW of 0.06 for soil. Top sections of substrate dried to near zero PAVW 6 days after irrigation for all containers. Larger container sizes maintained higher PAVW in middle sections than smaller container sizes, and PAVW was always higher in the adjacent soil than in the embedded substrate. Overall, very little PAVW is held by the embedded pine-bark growing substrate, suggesting the need for container substrates with greater water retention once transplanted to mineral soils.

scholarly journals Non-Fickian Solute Transport in a Single Fracture of Marble Parallel Plate

Geofluids ◽  
2018 ◽  
Vol 2018 ◽  
pp. 1-9 ◽  
Author(s):  
Xiaosan Yan ◽  
Jiazhong Qian ◽  
Lei Ma ◽  
Mu Wang ◽  
Aofeng Hu
Keyword(s):  
Electrical Conductivity ◽  
Solute Transport ◽  
Breakthrough Curves ◽  
Transport Processes ◽  
Single Fracture ◽  
Experimental Conditions ◽  
Monitoring Method ◽  
Subsurface Hydrology ◽  
Advection Dispersion ◽  
The Right

Accurate prediction of solute transport processes in a fracture aquifer is an important task not only for proper management of the groundwater but also for pollution control. A key issue of this task is how to accurately obtain the experimental data and to analyze the solute transport in fracture in subsurface hydrology, which would greatly help us to understand the releasing mechanism and transport of the solute in a fracture. In this study, a fracture experiment is conducted in a laboratory based on previous studies. The fracture used with a length of 60 cm and a width of 10 cm is sealed with glass glue to avoid leakage of tracer due to uneven fracture walls. The sodium chloride (NaCl) solute is injected from the left of the fracture. And an electrical conductivity monitoring system is installed on the right of the fracture. Then breakthrough curves (BTCs) of solute transport are fitted using the classical advection-dispersion equation (ADE) and the truncation power-law function (TPL) model in the package of the continuous time random walk (CTRW). The results show that the flow satisfies non-Darcian law in the experimental conditions, which can be better fitted using the Forchheimer equation and Izbash equation. The solute transport presents non-Fickian phenomena and shows a long tailing. The fitting results of the TPL model are far better than ADE in fitting the long tailing at three different flow velocities. Furthermore, electrical conductivity monitoring method not only is effective but also has an advantage of no disturbance to water and concentration fields in a fracture.

Claudin Tight Junction Proteins: Novel Aspects in Paracellular Transport

2008 ◽  
Vol 28 (6) ◽  
pp. 577-584 ◽  
Author(s):  
Constanze Will ◽  
Michael Fromm ◽  
Dominik Müller
Keyword(s):  
Tight Junction ◽  
Solute Transport ◽  
Molecular Mechanisms ◽  
Family Members ◽  
Transport Processes ◽  
Paracellular Transport ◽  
Solute Flux ◽  
Solute Fluxes ◽  
Essential Components ◽  
Renal Tubular

Claudins are essential components of the intercellular tight junction and major determinants of paracellular solute fluxes across epithelia and endothelia. Many members of this family display a distinct charge or size specificity, whereas others render the epithelium impermeable to transport. Due to intercellular localization, claudin-mediated transport processes are passive and driven by an electrochemical gradient. In epithelial tissues, claudins exhibit a temporal–spatial expression pattern corresponding with regional and local solute transport profiles. Whereas paracellular transport mechanisms in organs such as intestine and kidney have been extensively investigated, little is known about the molecular mechanisms determining solute transport in the peritoneum, and thus the determinants of peritoneal dialysis. Given the ubiquitous expression of claudins in endothelia and epithelia, it is predictable that claudins also contribute to pore formation and determination in the peritoneum, and that they are involved in solute flux. Therefore, we review the basic characteristics of claudin family members and their function as exemplified in renal tubular transport and give an outlook to what extent claudin family members might be of importance for solute reabsorption across the peritoneal membrane.

scholarly journals Review on the Macro-Transport Processes Theory for Irregular Pores able to Perform Catalytic Reactions

Catalysts ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 281 ◽  
Author(s):  
Iván Santamaría-Holek ◽  
Saúl Hernández ◽  
Consuelo García-Alcántara ◽  
Aldo Ledesma-Durán
Keyword(s):  
Porous Media ◽  
Diffusion Coefficients ◽  
Mass Conservation ◽  
Breakthrough Curves ◽  
Transport Processes ◽  
Catalytic Reactions ◽  
Irregular Domains ◽  
Surface Mass ◽  
Physicochemical Basis ◽  
Mass Uptake

We review and generalize a recent theoretical framework that provides a sound physicochemical basis to describe how volume and surface diffusion are affected by adsorption and desorption processes, as well as by catalytic conversion within the space defined by the irregular geometry of the pores in a material. The theory is based on two single-dimensional mass conservation equations for irregular domains deduced for the volumetric (bulk) and surface mass concentrations. It offers a powerful tool for analyzing and modeling mass transport across porous media like zeolites or artificially build materials, since it establishes how the microscopic quantities that refer to the internal details of the geometry, the flow and the interactions within the irregular pore can be translated into macroscopic variables that are currently measured in experiments. The use of the theory in mass uptake experiments is explained in terms of breakthrough curves and effective mass diffusion coefficients which are explicitly related to the internal geometry of the pores.

scholarly journals Micronutrient Availability from Steel Slag Amendment in Pine Bark Substrates

2016 ◽  
Vol 34 (3) ◽  
pp. 67-74
Author(s):  
James E. Altland ◽  
James C. Locke ◽  
Wendy L. Zellner
Keyword(s):  
Plant Uptake ◽  
Steel Slag ◽  
Nutrient Deficiency ◽  
Dry Weight ◽  
Nutrient Content ◽  
Sole Source ◽  
Pine Bark ◽  
Mineral Nutrient ◽  
Micronutrient Availability ◽  
Base Substrate

Steel slag is a byproduct of the steel industry that can be used as a liming agent, but also has a high mineral nutrient content. While micronutrients are present in steel slag, it is not known if the mineral form of the micronutrients would render them available for plant uptake. The objective of this research was to determine if steel slag could be used as the sole micronutrient source for container-grown nursery crops. Butterfly bush (Buddleja davidii ‘Pink Delight’) and rose (Rosa ‘Radrazz’) were grown in #3 (3 gal) containers in a base substrate composed of pine bark and peatmoss (80:20, by vol). The base substrate was amended with the following treatments: with a complete controlled release fertilizer (CRF) including micronutrients (C-control), a substrate amended with a different CRF containing only N, P, and K along with a granular micronutrient package (M-control), and three additional treatments amended with the CRF (N, P, and K only) and either 1.2, 2.4, or 4.8 kg·m−3 (2, 4, and 8 lb·yd−3) of steel slag. Plants were harvested at 2 and 4 months after potting (MAP). None of the plants displayed any sign of nutrient deficiency or toxicity throughout the experiment. However, plants grown in the substrate amended with the highest slag rate [4.8 kg·m−3 (8 lb·yd−3)] had lower shoot dry weight (SDW) than both control groups. Substrate pH increased with increasing slag rate, which may have affected micronutrient availability in those substrates. Among the micronutrients analyzed, only Copper (Cu) was consistently deficient in both the substrate and foliar tissue of slag-amended treatments. Steel slag either does not provide a sufficient quantity of Cu or the concomitant increase in pH with increasing rates of steel slag renders Cu unavailable for plant uptake. Steel slag should not be used as the sole source of micronutrients for shrubs grown in pine bark-based substrates.

Historical development of soil-water physics and solute transport in porous media

2007 ◽  
Vol 7 (1) ◽  
pp. 59-66 ◽  
Author(s):  
D.E. Rolston
Keyword(s):  
Porous Media ◽  
Hydraulic Conductivity ◽  
Solute Transport ◽  
Soil Water ◽  
20Th Century ◽  
Water Flow ◽  
Unsaturated Soils ◽  
Transport Processes ◽  
Transport In Porous Media ◽  
Unsaturated Hydraulic Conductivity

The science of soil-water physics and contaminant transport in porous media began a little more than a century ago. The first equation to quantify the flow of water is attributed to Darcy. The next major development for unsaturated media was made by Buckingham in 1907. Buckingham quantified the energy state of soil water based on the thermodynamic potential energy. Buckingham then introduced the concept of unsaturated hydraulic conductivity, a function of water content. The water flux as the product of the unsaturated hydraulic conductivity and the total potential gradient has become the accepted Buckingham-Darcy law. Two decades later, Richards applied the continuity equation to Buckingham's equation and obtained a general partial differential equation describing water flow in unsaturated soils. For combined water and solute transport, it had been recognized since the latter half of the 19th century that salts and water do not move uniformly. It wasn't until the middle of the 20th century that scientists began to understand the complex processes of diffusion, dispersion, and convection and to develop mathematical formulations for solute transport. Knowledge on water flow and solute transport processes has expanded greatly since the early part of the 20th century to the present.

scholarly journals Effect of Flow Rate and Particle Concentration on the Transport and Deposition of Bare and Stabilized Zero-Valent Iron Nanoparticles in Sandy Soil

2019 ◽  
Vol 11 (23) ◽  
pp. 6608
Author(s):  
Ibrahim ◽  
Awad ◽  
Al-Farraj ◽  
Al-Turki
Keyword(s):  
Flow Rate ◽  
Sandy Soil ◽  
Particle Deposition ◽  
Particle Concentration ◽  
Soil Column ◽  
Relative Concentration ◽  
Methyl Cellulose ◽  
Maximum Flow ◽  
Breakthrough Curves ◽  
Zero Valent Iron

Efficient application of nanoscale zero-valent iron (nZVI) particles in remediation processes relies heavily on the ability to modify the surfaces of nZVI particles to enhance their stability and mobility in subsurface layers. We investigated the effect of sodium carboxy-methyl-cellulose (CMC) polymer stabilizer, pH, particle concentration, and flow rate on the transport of nZVI particles in sand columns. Breakthrough curves (BTCs) of nZVI particles indicated that the transport of nZVI particles was increased by the presence of CMC and by increasing the flow rate. The relative concentration (RC) of the eluted CMC–nZVI nanoparticles was larger at pH 9 as compared to RC at pH 7. This is mainly attributed to the increased nZVI particle stability at higher pH due to the increase in the electrostatic repulsion forces and the formation of larger energy barriers. nZVI particle deposition was larger at 0.1 cm min-1 flow due to the increased residence time, which increases the aggregation and settlement of particles. The amount of CMC–nZVI particles eluted from the sand columns was increased by 52% at the maximum flow rate of 1.0 cm min-1. Bare nZVI were mostly retained in the first millimeters of the soil column, and the amount eluted did not exceed 1.2% of the total amount added. Our results suggest that surface modification of nZVI particles was necessary to increase stability and enhance transport in sandy soil. Nevertheless, a proper flow rate, suitable for the intended remediation efforts, must be considered to minimize nZVI particle deposition and increase remediation efficiency.

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