scholarly journals Modeling of NO3 transport in gypsiferous soil under unsaturated flow

2021 ◽  
Vol 8 (3) ◽  
Author(s):  
Ramzi M. Shihab ◽  
Ahmed A. Fattah ◽  
Noor Aldeen M. Muhawish
Keyword(s):  
Unsaturated Flow ◽  
Nitrate Concentration ◽  
Dispersion Model ◽  
Soil Column ◽  
Potassium Nitrate ◽  
Breakthrough Curves ◽  
Retardation Factor ◽  
Soil Columns ◽  
Water Head ◽  
Gypsum Content

"This study was conducted to determine the effect of gypsum content and depth of water head on displacement and transport of nitrate in gypsiferous soil under unsaturated flow conditions. Also, to predict the concentration of nitrate using convection dispersion model (CDE). Soil columns with 63, 97, 142, 180, and 236 g kg-1 of gypsum were prepared. 200 mg L-1 of potassium nitrate were added to the surface of each soil column. The soil columns were leached by intermittent ponding in 2 pore volumes of water. A constant head depth of 0.005, 0.01, and 0.015 m of water was kept on the top of soil column. Samples of effluent were collected for measuring nitrate concentration. The CDE model was analyzed to estimate the best fitting between measured and predicted nitrate concentration, and to calculate dispersion coefficient (D), the retardation factor (R), and Peclet number (P). Results showed that CDE can be used to predict nitrate concentration in soil. Good fit was observed to describe breakthrough curves (BTC's), and predict the transport of nitrates in the leachate of gypsum soil columns. D values increased with the increase in the content of soil gypsum and decrease with increase the water head. Its values ranged between 6.59-9.87 m 2h-1. P and pore water velocity (v) decreased with the increase in soil gypsum content. The R values were less than 1 for all treatments"

Parameter Determination for Chloride and Tritium Transport in Undisturbed Lysimeters during Steady Flow

1992 ◽  
Vol 23 (2) ◽  
pp. 89-104 ◽  
Author(s):  
Ole H. Jacobsen ◽  
Feike J. Leij ◽  
Martinus Th. van Genuchten
Keyword(s):  
Experimental Data ◽  
Unsaturated Flow ◽  
Transport Model ◽  
Time Moment ◽  
Breakthrough Curves ◽  
Coarse Sand ◽  
Retardation Factor ◽  
Parameter Determination ◽  
Model Parameters ◽  
Water Fraction

Breakthrough curves of Cl and 3H2O were obtained during steady unsaturated flow in five lysimeters containing an undisturbed coarse sand (Orthic Haplohumod). The experimental data were analyzed in terms of the classical two-parameter convection-dispersion equation and a four-parameter two-region type physical nonequilibrium solute transport model. Model parameters were obtained by both curve fitting and time moment analysis. The four-parameter model provided a much better fit to the data for three soil columns, but performed only slightly better for the two remaining columns. The retardation factor for Cl was about 10 % less than for 3H2O, indicating some anion exclusion. For the four-parameter model the average immobile water fraction was 0.14 and the Peclet numbers of the mobile region varied between 50 and 200. Time moments analysis proved to be a useful tool for quantifying the break through curve (BTC) although the moments were found to be sensitive to experimental scattering in the measured data at larger times. Also, fitted parameters described the experimental data better than moment generated parameter values.

Determination of Technetium and Selenium Transport Properties in Laboratory Soil Columns

1988 ◽  
Vol 127 ◽  
Author(s):  
J. A. Del Debbio ◽  
T. R. Thomas
Keyword(s):  
Transport Properties ◽  
Soil Column ◽  
Retardation Factor ◽  
Soil Columns ◽  
Water Contact ◽  
Near Surface ◽  
One Dimensional ◽  
High Level ◽  
Water Saturated

ABSTRACTLaboratory studies are being conducted to measure the transport properties of various radionuclide species through soil columns. The studies are being conducted to support evaluations for potential near-surface disposal of high-level radioactive waste (HLW) calcine stored at the Idaho National Engineering Laboratory. The data will be used to model radionuclide transport through the vadose (unsaturated) zone of the site under various water-contact scenarios. Retardation factors and dispersion coefficients for technetium and selenium species have been measured in water-saturated soil columns made up of sediments taken from 12 and 35 meters below the surface. A one-dimensional, convective-dispersive, solute-transport equation was fitted to column effluent data by optimizing three parameters (retardation factor, dispersion coefficient and pulse time) using a non-linear, least-squares fitting routine. The data indicated no retardation of the pertechnetate ion (TcO4-)and selenate ion (SeO4-) and a large retardation of the selenite ion (SeO3-) relative to water transport through the soil column.

scholarly journals Applied tracers for the observation of subsurface stormflow at the hillslope scale

2009 ◽  
Vol 6 (2) ◽  
pp. 2961-3006 ◽  
Author(s):  
J. Wienhöfer ◽  
K. Germer ◽  
F. Lindenmaier ◽  
A. Färber ◽  
E. Zehe
Keyword(s):  
Large Scale ◽  
Preferential Flow ◽  
Unsaturated Flow ◽  
Dispersion Model ◽  
Breakthrough Curves ◽  
Flow Paths ◽  
Transient Flows ◽  
Natural Rainfall ◽  
Flow Features ◽  
Hillslope Scale

Abstract. Rainfall-runoff response in temperate humid headwater catchments is mainly controlled by hydrological processes at the hillslope scale. Applied tracer experiments with fluorescent dye and salt tracers are well known tools in groundwater studies at the large scale and vadose zone studies at the plot scale, where they provide a means to characterise subsurface flow. We extend this approach to the hillslope scale to investigate saturated and unsaturated flow paths concertedly at a forested hillslope in the Austrian Alps. Dye staining experiments at the plot scale revealed that cracks and soil pipes function as preferential flow paths in the fine-textured soils of the study area, and these preferential flow structures were active in fast subsurface transport of tracers at the hillslope scale. Breakthrough curves obtained under steady flow conditions could be fitted well to a one-dimensional convection-dispersion model. Under natural rainfall a positive correlation of tracer concentrations to the transient flows was observed. The results of this study demonstrate qualitative and quantitative effects of preferential flow features on subsurface stormflow in a temperate humid headwater catchment. It turns out that, at the hillslope scale, the interactions of structures and processes are intrinsically complex, which implies that attempts to model such a hillslope satisfactorily require detailed investigations of effective structures and parameters at the scale of interest.

scholarly journals Applied tracers for the observation of subsurface stormflow at the hillslope scale

2009 ◽  
Vol 13 (7) ◽  
pp. 1145-1161 ◽  
Author(s):  
J. Wienhöfer ◽  
K. Germer ◽  
F. Lindenmaier ◽  
A. Färber ◽  
E. Zehe
Keyword(s):  
Large Scale ◽  
Preferential Flow ◽  
Unsaturated Flow ◽  
Dispersion Model ◽  
Breakthrough Curves ◽  
Flow Paths ◽  
Transient Flows ◽  
Natural Rainfall ◽  
Flow Features ◽  
Hillslope Scale

Abstract. Rainfall-runoff response in temperate humid headwater catchments is mainly controlled by hydrological processes at the hillslope scale. Applied tracer experiments with fluorescent dye and salt tracers are well known tools in groundwater studies at the large scale and vadose zone studies at the plot scale, where they provide a means to characterise subsurface flow. We extend this approach to the hillslope scale to investigate saturated and unsaturated flow paths concertedly at a forested hillslope in the Austrian Alps. Dye staining experiments at the plot scale revealed that cracks and soil pipes function as preferential flow paths in the fine-textured soils of the study area, and these preferential flow structures were active in fast subsurface transport of tracers at the hillslope scale. Breakthrough curves obtained under steady flow conditions could be fitted well to a one-dimensional convection-dispersion model. Under natural rainfall a positive correlation of tracer concentrations to the transient flows was observed. The results of this study demonstrate qualitative and quantitative effects of preferential flow features on subsurface stormflow in a temperate humid headwater catchment. It turns out that, at the hillslope scale, the interactions of structures and processes are intrinsically complex, which implies that attempts to model such a hillslope satisfactorily require detailed investigations of effective structures and parameters at the scale of interest.

Transport of Microorganisms in the Underground – Processes, Experiments and Simulation Models

1991 ◽  
Vol 24 (2) ◽  
pp. 309-314 ◽  
Author(s):  
G. Teutsch ◽  
K. Herbold-Paschke ◽  
D. Tougianidou ◽  
T. Hahn ◽  
K. Botzenhart
Keyword(s):  
Simulation Models ◽  
Mass Conservation ◽  
Breakthrough Curves ◽  
Conservation Equation ◽  
Retardation Factor ◽  
Natural Systems ◽  
Laboratory Setup ◽  
Preliminary Model ◽  
Sand And Gravel ◽  
Mass Conservation Equation

In this paper the major processes governing the persistence and underground transport of viruses and bacteria are reviewed in respect to their importance under naturally occurring conditions. In general, the simulation of the governing processes is based on the macroscopic mass-conservation equation with the addition of some filter and/or retardation factor and a decay coefficient, representing the natural “die-off” of the microorganisms. More advanced concepts try to incorporate growth and decay coefficients together with deposition and declogging factors. At present, none of the reported concepts has been seriously validated. Due to the complexity of natural systems and the pathogenic properties of some of the microorganisms, experiments under controlled laboratory conditions are required. A laboratory setup is presented in which a great variety of natural conditions can be simulated. This comprises a set of 1 metre columns and an 8 metre stainless-steel flume with 24 sampling ports. The columns are easily filled and conditioned and therefore used to study the effects of different soil-microorganism combinations under various environmental conditions. In the artificial flume natural underground conditions are simulated using sand and gravel aquifer material from the river Neckar alluvium. A first set of results from the laboratory experiments is presented together with preliminary model simulations. The large variety of observed breakthrough curves and recovery for the bacteria and viruses under investigation demonstrates the great uncertainty encountered in microbiological risk assessment.

Thermoelectric Studies of Silver Nitrate in Sodium Nitrate – Potassium Nitrate Eutectic Melt

1971 ◽  
Vol 49 (12) ◽  
pp. 2044-2047
Author(s):  
L. G. Boxall ◽  
K. E. Johnson
Keyword(s):  
Seebeck Coefficient ◽  
Silver Nitrate ◽  
Mole Fraction ◽  
Sodium Nitrate ◽  
Nitrate Concentration ◽  
Potassium Nitrate ◽  
Silver Nitrate Concentration ◽  
Eutectic Melt

The Seebeck coefficient, εT, of the thermocell Ag(T)/AgNO3 in NaNO3 − KNO3/Ag (T + ΔT) was measured as a function of silver nitrate concentration and temperature. Extrapolation of the results to unit mole fraction, N, of AgNO3 gave the value εT0 = − 277.5 − 0.136T °C (µV deg−1).For several mixed melts of AgNO3 and an alkali nitrate the function [Formula: see text] was calculated and shown to be linear in N. P was extrapolated to finite values for the pure alkali nitrates.

scholarly journals Temperature effect in potassium and nitrate ions in soil transport

2008 ◽  
Vol 28 (3) ◽  
pp. 438-447 ◽  
Author(s):  
Adriano D. M. A. Gonçalves ◽  
Jarbas H. Miranda ◽  
Paulo Rossi ◽  
José F. G. Sabadin ◽  
Marcos Y. Kamogawa
Keyword(s):  
Porous Medium ◽  
Dispersion Coefficient ◽  
Potassium Nitrate ◽  
Positive Influence ◽  
Retardation Factor ◽  
Nitrate Transport ◽  
Transport Parameters ◽  
Medium Temperature ◽  
Soil Transport ◽  
Solute Dynamics

When doing researches on solute dynamics in porous medium, the knowledge of medium characteristics and percolating liquids, as well as of external factors is very important. An important external factor is temperature and, in this sense, our purpose was determining potassium and nitrate transport parameters for different values of temperature, in miscible displacement experiments. Evaluated parameters were retardation factor (R), diffusion/dispersion coefficient (D) and dispersivity, at ambient temperature (25 up to 28 ºC), 40 ºC and 50 ºC. Salts used were potassium nitrate and potassium chlorate, prepared in a solution made up of 5 ppm nitrate and 2.000 ppm potassium, with Red-Yellow Latosol porous medium. Temperature exhibited a positive influence upon porous medium solution and upon dispersion coefficient.

Development of a soil water dispersion index (SOWADIN) for testing the effectiveness of soil-wetting agents

Soil Research ◽  
1989 ◽  
Vol 27 (1) ◽  
pp. 17 ◽  
Author(s):  
Y Sawada ◽  
LAG Aylmore ◽  
JM Hainsworth
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Water Distribution ◽  
Soil Column ◽  
Water Repellent ◽  
Computer Assisted ◽  
Dispersion Index ◽  
Soil Columns ◽  
Water Dispersion ◽  
Soil Wetting

Computer-assisted tomography (CAT) applied to gamma-ray attenuation measurements has been used to develop an index termed the soil water dispersion index (SOWADIN), which describes quantitatively the amount and distribution of water in soil columns. The index, which is determined by classifying pixels in a scanned slice into three categories according to their attenuation coefficients, contains two numerical values. The first value corresponds to the water content of the scanned slice and the second value is a measure of the dispersion of the water throughout the slice. Artificially wetted zones were created in soil columns to give one-third of the scanned layer wetted with various patterns of wetted-area distribution. The SOWADIN values obtained accurately reflected the differences in water distribution associated with the different patterns. Application of SOWADIN to columns of a water-repellent sand before and after treatment with a soil-wetting agent clearly illustrates both the increase in water content and improvement in water distribution in the soil column following treatment.

scholarly journals Managed aquifer recharge: study of undisturbed soil column tests on the infiltration and treatment capacity using effluent of wastewater stabilization pond

RBRH ◽  
2018 ◽  
Vol 23 (0) ◽  
Author(s):  
Jaqueline Vígolo Coutinho ◽  
Cristiano das Neves Almeida ◽  
Eduardo Bernardo da Silva ◽  
Catalin Stefan ◽  
Gilson Barbosa Athayde Júnior ◽  
...  
Keyword(s):  
Soil Column ◽  
Managed Aquifer Recharge ◽  
Future Research ◽  
Sewage Effluent ◽  
Ammoniacal Nitrogen ◽  
Aquifer Recharge ◽  
Soil Columns ◽  
Undisturbed Soil ◽  
Coastal Watershed ◽  
Stabilization Pond

ABSTRACT Managed Aquifer Recharge (MAR) is a useful tool for the treatment and use of sewage effluent because it complements conventional treatment, recovers the aquifer and minimizes risk of saltwater intrusion. This study aims to investigate technical data to determine the treatment of wastewater stabilization pond effluent using undisturbed soil columns collected from a coastal watershed study area within the BRAMAR (BRAzil Managed Aquifer Recharge) project. The treatment efficiency was monitored by measuring physico-chemical parameters (BOD 5, COD, DOC, TSS, NH3 and NO3) in two columns filled with undisturbed sandy soil in which sewage effluent was infiltrated under unsaturated condition for 72 days with an average input flow of 10 mm h-1. Results indicated reduction greater than 60% of organic matter, suspended solids and ammoniacal nitrogen. However, high concentrations of nitrate in the outflow were detected originating from nitrification of ammoniacal nitrogen. Moreover, difficulties in relation to soil clogging were observed. Furthermore, this study brought relevant contributions to understanding the influence of the infiltration rate and ability to treat effluent from wastewater stabilization ponds using undisturbed soil columns. Future research should be undertaken to improve the pretreatment methods and the operation of a MAR system in the study area.

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.

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