Importance of DOC in sediments for contaminant transport modelling

Contaminants in the interstitial waters are not only dissolved but also associated with a filterable colloidal phase such as DOC. The DOC plays an important role regulating the distribution of chemicals between particulate and dissolved phases since it binds chemicals and makes them unavailable for vertical diffusive exchange. A three-phase partitioning model that consists of free-dissolved, DOC-bound, particulate-bound components of the chemicals involved is used for the contaminant transport model in order to include the effect of DOC on the partition coefficient. The contaminant model is linked to WASP modeling framework to predict remobilization of PCBs in sediments and the fate and transport of the contaminant in overlying waters of the New Bedford Harbor where the harbor has been contaminated with PCBs and heavy metals released from electronic capacitor manufacturers. Simulation of remedial controls indicates that if no action is taken, PCB concentrations will continue to be at elevated levels. Several scenarios for the removal of contaminated sediments have been performed to reduce the elevated PCB concentrations to background levels.

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Generalizing Source Geometry of Site Contamination by Simulating and Analyzing Analytical Solution of Three-Dimensional Solute Transport Model

Mathematical Problems in Engineering ◽

10.1155/2014/646495 ◽

2014 ◽

Vol 2014 ◽

pp. 1-8

Author(s):

Xingwei Wang ◽

Jiajun Chen ◽

Hao Wang ◽

Jianfei Liu

Keyword(s):

Solute Transport ◽

Contaminant Transport ◽

Transport Model ◽

Three Dimensional ◽

Fate And Transport ◽

Source Area ◽

Equation Model ◽

Plume Migration ◽

Advective Diffusion ◽

Source Geometry

Due to the uneven distribution of pollutions and blur edge of pollutant area, there will exist uncertainty of source term shape in advective-diffusion equation model of contaminant transport. How to generalize those irregular source terms and deal with those uncertainties is very critical but rarely studied in previous research. In this study, the fate and transport of contaminant from rectangular and elliptic source geometry were simulated based on a three-dimensional analytical solute transport model, and the source geometry generalization guideline was developed by comparing the migration of contaminant. The result indicated that the variation of source area size had no effect on pollution plume migration when the plume migrated as far as five times of source side length. The migration of pollution plume became slower with the increase of aquifer thickness. The contaminant concentration was decreasing with scale factor rising, and the differences among various scale factors became smaller with the distance to field increasing.

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Effect of interface transmissivity and hydraulic conductivity on contaminant migration through composite liners with wrinkles or failed seams

Canadian Geotechnical Journal ◽

10.1139/cgj-2018-0660 ◽

2019 ◽

Vol 56 (11) ◽

pp. 1650-1667 ◽

Cited By ~ 4

Author(s):

R. Kerry Rowe ◽

A.Y. AbdelRazek

Keyword(s):

Hydraulic Conductivity ◽

Contaminant Transport ◽

Finite Element Modelling ◽

Transport Model ◽

Closed Form Solution ◽

Chloride Concentration ◽

Form Solution ◽

Contaminant Migration ◽

Transport Modelling ◽

Composite Liners

The leakage and the peak chloride concentration in an aquifer for a single composite liner facility is modelled for (i) a hole in a geomembrane wrinkle and (ii) a failed seam. A method using a closed-form solution to calculate leakage together with a l½-dimensional (l½D) semi-analytic contaminant transport model is proposed, and the results compared with those obtained from two-dimensional (2D) finite element modelling (FEM). Leakage is shown to be highly dependent on the interaction between the interface transmissivity (θ) and hydraulic conductivity beneath the wrinkle (kb). Similar leakages arising from different combinations of transmissivity and hydraulic conductivity are shown to have significantly different impacts on an underlying aquifer. Contaminant transport modelling is needed to assess this effect for the likely range of uncertainty regarding interface transmissivity (θ) and hydraulic conductivity. The 2D FEM is conceptually more comprehensive; however, using conventional software only a very limited size of problem could be accurately modeled given the greatly different scales that must be modelled. In contrast, the semi-analytic 1½D approach readily allowed consideration of the highly variable scales, and gave results at the down-gradient edge sufficiently similar to the 2D approach.

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Fate and Transport Modelling of Perchloroethylene in the St. Clair River

Water Quality Research Journal ◽

10.2166/wqrj.1986.035 ◽

1986 ◽

Vol 21 (3) ◽

pp. 398-410 ◽

Cited By ~ 4

Author(s):

John A. McCorquodale ◽

Kamal Ibrahim ◽

Yousry Hamdy

Keyword(s):

Water Column ◽

Environmental Protection Agency ◽

Transport Model ◽

Fate And Transport ◽

River System ◽

Protection Agency ◽

Transport Modelling ◽

River Bed ◽

System Water ◽

The U.S

Abstract The response of the St. Clair River system (water column and bed sediments) to a spill of perchloroethylene (PERC) is predicted by application of the U.S. Environmental Protection Agency (EPA) TOXIWASP fate transport model. The spill occurred from August 13 to 16, 1986 at the Dow Chemical of Canada Inc. site. The estimated quantity of the spill was 18000 kg of which approximately 10,000 kg initially settled out In the vicinity of the Dow Chemical outfalls. At the end of 30 days the model indicated that about 12600 kg had been discharged to Lake St. Clair while 4500 kg and 90 kg remained on the river bed and in temporary storage in the water column respectively. Approximately 5% of the original spill was volatilized in the river during the 30 days after the spill.

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A detailed contaminant transport model for facility hazard assessment in urban areas

10.2514/6.1999-3441 ◽

1999 ◽

Cited By ~ 10

Author(s):

Bohdan Cybyk ◽

Jay Boris ◽

Theodore Young, Jr. ◽

Charles Lind ◽

Alexandra Landsberg

Keyword(s):

Contaminant Transport ◽

Hazard Assessment ◽

Urban Areas ◽

Transport Model

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Transport of organochlorine pesticides in soil columns enhanced by dissolved organic carbon

Water Science & Technology ◽

10.2166/wst.1997.0270 ◽

1997 ◽

Vol 35 (7) ◽

pp. 139-145 ◽

Cited By ~ 10

Author(s):

Jiann-Yuan Ding ◽

Shian-Chee Wu

Keyword(s):

Organic Carbon ◽

Dissolved Organic Carbon ◽

Organochlorine Pesticides ◽

Transport Model ◽

Phase Model ◽

Soil Columns ◽

Two Phase ◽

Three Phase ◽

Phase Transport ◽

Remediation Of Soil

The objective of this study is to quantify the effects of humic acid solution infiltration on the transport of organochlorine pesticides (OCPs) in soil columns using a three-phase transport model. From experimental results, it is found that the dissolved organic carbon enhances the transport of OCPs in the soil columns. In the OCPs-only column, the concentration profiles of OCPs can be simulated well using a two-phase transport model with numerical method or analytical solution. In the OCPs-DOC column, the migrations of aldrin, DDT and its daughter compounds are faster than those in the OCPs-only column. The simulation with the three-phase model is more accurate than that with the two-phase model. In addition, significant decrease of the fluid pore velocities of the OCPs-DOC column was found. When DOC leachate is applied for remediation of soil or groundwater pollution, the decrease of mean pore velocities will be a crucial affecting factor.

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Quality Analysis of Fresh Cheese Prepared Using Wrightia tinctoria Proteases

Current Nutrition & Food Science ◽

10.2174/1573401316666200214102828 ◽

2020 ◽

Vol 16 (9) ◽

pp. 1309-1317

Author(s):

Anusha Rajagopalan ◽

Bindhu O. Sukumaran

Keyword(s):

Textural Properties ◽

Artemia Salina ◽

Quality Analysis ◽

Human Consumption ◽

Cheese Making ◽

Phase Partitioning ◽

Milk Clotting ◽

Three Phase ◽

Fresh Cheese ◽

Wrightia Tinctoria

Background: Aqueous leaf extract of Wrightia tinctoria has been in use for artisanal cheese preparation in diverse parts of India. Scientific validation behind the milk clotting potential of W. tinctoria stem proteases purified through three-phase partitioning (TPP) has been attempted. However, its contribution to cheese quality standards has not been tried yet. Objective: To evaluate the suitability of three-phase partitioned W. tinctoria (WT) stem proteases in fresh cheese making. Methods: Fresh cheese was prepared using W. tinctoria TPP proteases and its characteristics were compared with that of commercial plant milk coagulant, Enzeco® (CEz) and rennin (CRn). Yield, organoleptic and textural properties, total fat, protein and moisture content of all cheese were determined according to FSSAI standards. Toxicity of the TPP proteases was assessed on the shrimp model (Artemia salina egg and Litopenaeus vannamei post-larval shrimps). Results: TPP proteases were found to be non-toxic and safe for human consumption with no change in egg hatchability and survival of the shrimps in comparison to that of control. Cheese analysis results indicated perceptible resemblance in nutritional characteristics of WT cheese with control cheese. Yield, textural properties and organoleptic acceptance of WT cheese resembled more closely with that of CEz cheese. Conclusion: Observation from the study paves the way for the acceptance of W. tinctoria proteases as a suitable vegetable rennet for fresh cheese making.

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