Simple Linear Model for Calibration of Time Domain Reflectometry Measurements on Solute Concentration

Kim, D.J.; Vanclooster, Marnik; Feyen, Jan; Vereecken, Harry

doi:10.2136/sssaj1998.03615995006200010011x

Cited by 16 publications

(8 citation statements)

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“…A perforated disk and a nylon mesh, similar to that used by Kim et al (1998), were placed at the bottom of each cylinder in order to allow free drainage and prevent the loss of sandy or PAC materials. Plexiglass has previously been used for studies of organic compounds.…”

Section: Column Testmentioning

confidence: 99%

Irreversible sorption of benzene in sandy aquifer materials

Baek¹,

Kim²,

Kim³

2002

Hydrological Processes

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Abstract:Hydrocarbon compounds in aquifers are generally known to show a retardation effect due to sorption onto the surfaces of solid particles. In this study, we investigated the effect of sorption on the transport of benzene in sandy aquifer materials by conducting batch and column tests for both sandy aquifer materials and sandy materials to which had been added 0Ð5% powdered activated carbon. The batch test was conducted by equilibrating dry materials with benzene solutions of various initial concentrations, and by analysing the concentrations of benzene in the initial and equilibrated solutions using high-performance liquid chromatography (HPLC). The column test was performed to monitor the concentrations of effluent versus time, known as a breakthrough curve (BTC). We injected KCl and benzene solutions as tracers into the inlet boundary as two different types of square pulse and step, and monitored the effluent concentrations at the exit boundary under a steady-state condition using an electrical conductivity meter and HPLC. Simulation of benzene transport was performed using the convective-dispersive equation model with the distribution coefficients obtained from the batch test and the transport parameters of the conservative solute KCl from the column test. The observed BTCs of KCl and benzene for pulse injection showed that the arrival times of the peaks of both tracers coincided well, but the relative peak concentration of benzene was much lower than that of KCl. Comparison of the simulated and observed BTCs showed a great discrepancy for all cases of injection mode and material texture, indicating the absence of retardation effect. These results reveal that the predominant process affecting the benzene transport in the sandy aquifer materials is an irreversible sorption rather than retardation. This tentative conclusion was verified by simulation of benzene transport using an irreversible sorption parameter that led to a good agreement between the simulated and observed BTCs.

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Section: Column Testmentioning

confidence: 99%

Irreversible sorption of benzene in sandy aquifer materials

Baek¹,

Kim²,

Kim³

2002

Hydrological Processes

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“…Several studies (Rhoads et al, 1989;Kachanoski et al, 1992;Ward et al, 1994;Ward et al, 1995;Kim et al, 1998) were performed to establish the linear relationship between inverse of resistance or medium conductance and bulk electrical conductivity, which enables one to measure inorganic solute concentrations in a soil system. Based on the relationship, measurements of solutes such as KCl or CaCl 2 either in a laboratory column or field scale were performed under a steady-state and saturated condition to obtain breakthrough curves and subsequently solute transport parameters (Vanclooster et al, 1995;Kim et al, 1998;Jacques et al, 1998;Kim and Feyen, 2000).…”

Section: Introductionmentioning

confidence: 99%

“…Based on the relationship, measurements of solutes such as KCl or CaCl 2 either in a laboratory column or field scale were performed under a steady-state and saturated condition to obtain breakthrough curves and subsequently solute transport parameters (Vanclooster et al, 1995;Kim et al, 1998;Jacques et al, 1998;Kim and Feyen, 2000). Contrary to the column condition, most of contaminants in field sites can exist as unsaturated condition where various water contents are present.…”

Section: Introductionmentioning

confidence: 99%

Detection of inorganic chemicals in a sandy soil using TDR: Effect of probe geometry and water content

Kim

Choi

et al. 2010

Geosci J

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Monitoring of soil contamination becomes an important issue for effective remediation of soil and groundwater.Recently time domain reflectometry (TDR) has emerged as a promising tool for monitoring soils contaminated with inorganic chemicals since concentration of these chemicals can significantly contribute to the electrical property of a porous medium such as conductance or inverse of resistance (1/R) which can be measured by TDR. In this study, we investigated a possibility of detecting two inorganic chemicals (zinc and nitrate) in a sandy soil using TDR by conducting a number of batch experiments on TDR-measured resistance for various probe geometries (length (L) = 10, 15, 25 cm; ratio of rod spacing to diameter (s/d) = 5, 6) and saturation degrees (Se = 0.1-1.0). Column experiment was also performed to investigate the extent of input concentration which allows the detection of nitrate by TDR for various travel distances under saturated flow condition. The results of batch experiments showed that the inverse of TDRmeasured resistance was sensitive to both probe geometry and saturation degree. The short probe (L = 10 cm) could not detect properly the electrical property in the low concentration range (0~0.5 g/L) due to the higher s/d ratio and short length. This phenomenon was more pronounced for zinc than nitrate. Saturation degree also affected significantly the measurement of resistance especially for the short probe when low saturation degree (Se < 0.5) was imposed, showing incapability of detection due to the resistance higher than the upper limit (1 kΩ) of TDR measurement. Column experiment revealed that the short probe could not detect nitrate at a travel distance of 5 cm when input concentration of nitrate lower than 500 mg/L was imposed. This indicates that the long probe (L = 25 cm) is mostly recommended to use for detection of zinc and nitrate contamination whereas use of short probe is strictly limited to the condition of high water content (Se > 0.5) and input concentration higher than 2000 mg/L in the sandy soil.

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“…Many researchers proposed different forms of empirical equations to enhance the accuracy of water content measurement [6,14,16].…”

Section: Introductionmentioning

confidence: 99%

Measurement of glucose and sucrose concentrations by time-domain reflectometry

Lin

Chen

2008

Sens. & Instrumen. Food Qual.

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The time-domain reflectometry (TDR) technology was applied in this study to measure sugar concentrations below 10%. The influences of temperature and species of sugars were evaluated. The results indicated that the TDR methods could be used for measuring sugar concentrations. The slope of TDR waveforms at a specific range was found to be a function of sugar concentrations and temperature. The differences in TDR waves derived from various sugar species and TDR probes were insignificant. The effects of the concentration and temperature on the slope of the TDR waveforms were established by regression analysis. The accuracy of the TDR method to measure sugar concentrations in new independent samples was within 0.365%. This technique is inexpensive, rapid, in-situ and suitable for online applications.

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Simple Linear Model for Calibration of Time Domain Reflectometry Measurements on Solute Concentration

Cited by 16 publications

References 0 publications

Irreversible sorption of benzene in sandy aquifer materials

Irreversible sorption of benzene in sandy aquifer materials

Detection of inorganic chemicals in a sandy soil using TDR: Effect of probe geometry and water content

Measurement of glucose and sucrose concentrations by time-domain reflectometry

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