IN SITU MEASUREMENT OF GAS DIFFUSION CHARACTERISTICS IN UNSATURATED POROUS MEDIA BY MEANS OF TRACER EXPERIMENTS.

Persistent Link:
http://hdl.handle.net/10150/185115
Title:
IN SITU MEASUREMENT OF GAS DIFFUSION CHARACTERISTICS IN UNSATURATED POROUS MEDIA BY MEANS OF TRACER EXPERIMENTS.
Author:
KREAMER, DAVID KENNETH.
Issue Date:
1982
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract:
A gas-diffusion tracer experiment was conducted at the ChemNuclear, Inc., nuclear waste burial site near Barnwell, South Carolina, on June 1-10; 1981, testing a new methodology to measure the in situ gaseous diffusion characteristics of unsaturated porous media for the purpose of estimating the diffusive flux of volatile contaminants from the burial ground. The tracers used were CClBrF₂ and SF₆. They were released in the subsurface from permeation devices that closely approximate an ideal point-diffusion source. The permeation devices contain the tracer in liquid form and allow the tracer to escape at a constant rate by diffusion through a Teflon membrane. The release rates for CClBrF₂ and SF6 during the test were 105 and 3.3 nanograms/second, respectively. These compounds were selected on the basis of their compatabi1ity with the permeation-release device, their absence in the subsurface, and detectability in the part-per-tri11ion range in soil gas. Analyses were made in the field on a Varian 3700 series gas chromatograph equipped with an electron-capture detector. The instrument was modified to introduce soil gas through sampling valves and a Nafion tube desiccant. The diffusion sources were placed in the unsaturated soil at depths of 2 meters and 13 meters below land surface. Diffusive movements of tracer were monitored for a period of 7 days and tracer breakthrough was observed at points up to 3.5 meters away. Diffusion was modeled using a three-dimensional, continuous point source, transient-state, analytical model which allowed estimation of the effective diffusion coefficient of the porous media, and an independent assessment of the media's sorptive effects on the tracer gas. The model was calibrated using least squares and curve matching techniques, the latter of which enables a field technician to quickly interpret observed field data. Field values obtained for effective diffusion coefficient ranged from 0.026 to 0.037 cm²/sec. The average tortuosity factor observed for test site was 0.705.
Type:
text; Dissertation-Reproduction (electronic)
Keywords:
Tracers (Chemistry); Diffusion -- Mathematical models.; Radioactive pollution of the atmosphere.; Hazardous wastes -- Mathematical models.; Gas flow -- Mathematical models.
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Hydrology and Water Resources; Graduate College
Degree Grantor:
University of Arizona

Full metadata record

DC FieldValue Language
dc.language.isoenen_US
dc.titleIN SITU MEASUREMENT OF GAS DIFFUSION CHARACTERISTICS IN UNSATURATED POROUS MEDIA BY MEANS OF TRACER EXPERIMENTS.en_US
dc.creatorKREAMER, DAVID KENNETH.en_US
dc.contributor.authorKREAMER, DAVID KENNETH.en_US
dc.date.issued1982en_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.description.abstractA gas-diffusion tracer experiment was conducted at the ChemNuclear, Inc., nuclear waste burial site near Barnwell, South Carolina, on June 1-10; 1981, testing a new methodology to measure the in situ gaseous diffusion characteristics of unsaturated porous media for the purpose of estimating the diffusive flux of volatile contaminants from the burial ground. The tracers used were CClBrF₂ and SF₆. They were released in the subsurface from permeation devices that closely approximate an ideal point-diffusion source. The permeation devices contain the tracer in liquid form and allow the tracer to escape at a constant rate by diffusion through a Teflon membrane. The release rates for CClBrF₂ and SF6 during the test were 105 and 3.3 nanograms/second, respectively. These compounds were selected on the basis of their compatabi1ity with the permeation-release device, their absence in the subsurface, and detectability in the part-per-tri11ion range in soil gas. Analyses were made in the field on a Varian 3700 series gas chromatograph equipped with an electron-capture detector. The instrument was modified to introduce soil gas through sampling valves and a Nafion tube desiccant. The diffusion sources were placed in the unsaturated soil at depths of 2 meters and 13 meters below land surface. Diffusive movements of tracer were monitored for a period of 7 days and tracer breakthrough was observed at points up to 3.5 meters away. Diffusion was modeled using a three-dimensional, continuous point source, transient-state, analytical model which allowed estimation of the effective diffusion coefficient of the porous media, and an independent assessment of the media's sorptive effects on the tracer gas. The model was calibrated using least squares and curve matching techniques, the latter of which enables a field technician to quickly interpret observed field data. Field values obtained for effective diffusion coefficient ranged from 0.026 to 0.037 cm²/sec. The average tortuosity factor observed for test site was 0.705.en_US
dc.typetexten_US
dc.typeDissertation-Reproduction (electronic)en_US
dc.subjectTracers (Chemistry)en_US
dc.subjectDiffusion -- Mathematical models.en_US
dc.subjectRadioactive pollution of the atmosphere.en_US
dc.subjectHazardous wastes -- Mathematical models.en_US
dc.subjectGas flow -- Mathematical models.en_US
thesis.degree.namePh.D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplineHydrology and Water Resourcesen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.committeememberThompson, Glennen_US
dc.contributor.committeememberSimpson, Geneen_US
dc.contributor.committeememberInce, Simonen_US
dc.contributor.committeememberEvans, Danen_US
dc.identifier.proquest8305986en_US
dc.identifier.oclc686765559en_US
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