Continuous time random walk model better describes the tailing of atrazine transport in soil

J. C. Deng, X. Jiang, Xiaoxian Zhang, W. Hu, John W. Crawford

Research output: Contribution to journalArticle

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Abstract

Contaminant transport in soils is complicated and involves some physical and chemical nonequilibrium processes. In this research, the soil column displacement experiments of Cl‾ and atrazine under different flow velocities were carried out. The data sets of Cl‾ transport in sandy loam fitted to the convection dispersion equation (CDE) and the two-region model (TRM) indicated that the effects of physical nonequilibrium process produced by immobile water on the breakthrough curves (BTCs) of Cl‾ and atrazine transport through the repacking soil columns were negligible. The two-site model (TSM) and the continuous time random walk (CTRW) were also used to fit atrazine transport behavior at the flow rate of 19.86 cm hˉ¹. The CTRW convincingly captured the full evolution of atrazine BTC in the soil column, especially for the part of long tailing. However, the TSM failed to characterize the tailing of atrazine BTC in the soil column. The calculated fraction of equilibrium sorption sites, F, ranging from 0.78 to 0.80 for all flow rates suggested the contribution of nonequilibrium sorption sites to the asymmetry of atrazine BTCs. Furthermore, the data sets for the flow rates of 6.68 cm hˉ¹ and 32.81 cm hˉ¹ were predicted by the TSM and the CTRW. As to the flow rate of 6.68 cm hˉ¹, the CTRW predicted the entire BTC of atrazine transport better than the TSM did. For the flow rate of 32.81 cm hˉ¹, the CTRW characterized the late part of the tail better, while the TSM failed to predict the tailings of atrazine BTC.
Original languageEnglish
Pages (from-to)2150-2157
Number of pages8
JournalChemosphere
Volume71
Issue number11
DOIs
StatePublished - May 2008

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atrazine
Atrazine
Soil
Anthralin
breakthrough curve
Soils
5-Hydroxytryptophan
soil column
tailings
Tailings
Datasets
sorption
soil
Acetates
Physical Processes
Chemical Processes
Convection
Water
pollutant transport
sandy loam

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Deng, J. C., Jiang, X., Zhang, X., Hu, W., & Crawford, J. W. (2008). Continuous time random walk model better describes the tailing of atrazine transport in soil. Chemosphere, 71(11), 2150-2157. DOI: 10.1016/j.chemosphere.2008.01.001

Deng, J. C.; Jiang, X.; Zhang, Xiaoxian; Hu, W.; Crawford, John W. / Continuous time random walk model better describes the tailing of atrazine transport in soil.

In: Chemosphere, Vol. 71, No. 11, 05.2008, p. 2150-2157.

Research output: Contribution to journalArticle

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abstract = "Contaminant transport in soils is complicated and involves some physical and chemical nonequilibrium processes. In this research, the soil column displacement experiments of Cl‾ and atrazine under different flow velocities were carried out. The data sets of Cl‾ transport in sandy loam fitted to the convection dispersion equation (CDE) and the two-region model (TRM) indicated that the effects of physical nonequilibrium process produced by immobile water on the breakthrough curves (BTCs) of Cl‾ and atrazine transport through the repacking soil columns were negligible. The two-site model (TSM) and the continuous time random walk (CTRW) were also used to fit atrazine transport behavior at the flow rate of 19.86 cm hˉ¹. The CTRW convincingly captured the full evolution of atrazine BTC in the soil column, especially for the part of long tailing. However, the TSM failed to characterize the tailing of atrazine BTC in the soil column. The calculated fraction of equilibrium sorption sites, F, ranging from 0.78 to 0.80 for all flow rates suggested the contribution of nonequilibrium sorption sites to the asymmetry of atrazine BTCs. Furthermore, the data sets for the flow rates of 6.68 cm hˉ¹ and 32.81 cm hˉ¹ were predicted by the TSM and the CTRW. As to the flow rate of 6.68 cm hˉ¹, the CTRW predicted the entire BTC of atrazine transport better than the TSM did. For the flow rate of 32.81 cm hˉ¹, the CTRW characterized the late part of the tail better, while the TSM failed to predict the tailings of atrazine BTC.",
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Deng, JC, Jiang, X, Zhang, X, Hu, W & Crawford, JW 2008, 'Continuous time random walk model better describes the tailing of atrazine transport in soil' Chemosphere, vol 71, no. 11, pp. 2150-2157. DOI: 10.1016/j.chemosphere.2008.01.001

Continuous time random walk model better describes the tailing of atrazine transport in soil. / Deng, J. C.; Jiang, X.; Zhang, Xiaoxian; Hu, W.; Crawford, John W.

In: Chemosphere, Vol. 71, No. 11, 05.2008, p. 2150-2157.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Continuous time random walk model better describes the tailing of atrazine transport in soil

AU - Deng,J. C.

AU - Jiang,X.

AU - Zhang,Xiaoxian

AU - Hu,W.

AU - Crawford,John W.

PY - 2008/5

Y1 - 2008/5

N2 - Contaminant transport in soils is complicated and involves some physical and chemical nonequilibrium processes. In this research, the soil column displacement experiments of Cl‾ and atrazine under different flow velocities were carried out. The data sets of Cl‾ transport in sandy loam fitted to the convection dispersion equation (CDE) and the two-region model (TRM) indicated that the effects of physical nonequilibrium process produced by immobile water on the breakthrough curves (BTCs) of Cl‾ and atrazine transport through the repacking soil columns were negligible. The two-site model (TSM) and the continuous time random walk (CTRW) were also used to fit atrazine transport behavior at the flow rate of 19.86 cm hˉ¹. The CTRW convincingly captured the full evolution of atrazine BTC in the soil column, especially for the part of long tailing. However, the TSM failed to characterize the tailing of atrazine BTC in the soil column. The calculated fraction of equilibrium sorption sites, F, ranging from 0.78 to 0.80 for all flow rates suggested the contribution of nonequilibrium sorption sites to the asymmetry of atrazine BTCs. Furthermore, the data sets for the flow rates of 6.68 cm hˉ¹ and 32.81 cm hˉ¹ were predicted by the TSM and the CTRW. As to the flow rate of 6.68 cm hˉ¹, the CTRW predicted the entire BTC of atrazine transport better than the TSM did. For the flow rate of 32.81 cm hˉ¹, the CTRW characterized the late part of the tail better, while the TSM failed to predict the tailings of atrazine BTC.

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DO - 10.1016/j.chemosphere.2008.01.001

M3 - Article

VL - 71

SP - 2150

EP - 2157

JO - Chemosphere

T2 - Chemosphere

JF - Chemosphere

SN - 0045-6535

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Deng JC, Jiang X, Zhang X, Hu W, Crawford JW. Continuous time random walk model better describes the tailing of atrazine transport in soil. Chemosphere. 2008 May;71(11):2150-2157. Available from, DOI: 10.1016/j.chemosphere.2008.01.001