Award Date


Degree Type


Degree Name

Master of Science (MS)



Number of Pages



Experiments were conducted to assess and model the effects of unsaturated zone soil moisture content on vapor-phase pollutant propagation in a controlled setting. A two-dimensional sandtank was utilized for controlled vapor-phase experiments, with pollutant vapors of octane and diesel fuel introduced through a finely slotted source tube. Soil moisture content was varied from 0% to 10% by weight for octane experiments, and from 0% to 5% by weight for diesel fuel. The effects of introduced soil moisture on the transport of each pollutant vapor were observed via soil-gas sampling from access ports. Soil-gas samples were analyzed with FID gas chromatography to determine a gross hydrocarbon concentration for discrete time intervals and distances from the vapor source; Analytical modeling methods based on Fickian diffusion, developed by Kreamer (1982), were used to estimate two primary diffusion parameters D{dollar}\sb{\rm e}{dollar}, the effective diffusion coefficient, and A*, the sorption corrected porosity. Estimations were carried out using a FORTRAN program with a non-linear subroutine. The estimated parameters were used to model concentration curves for each moisture content. The modeling indicated adverse effects on vapor propagation near 2% moisture content for octane and 2% moisture content for diesel fuel; A trend observed for the octane vapor modeling illustrates the relationship of D{dollar}\rm\sb{e},\ D\sb{k},{dollar} and A* to the tortuosity factor. Tortuosity was observed to decrease as moisture content increased up to 5% by mass. As moisture content increase beyond 5% gravimetrically, tortuosity began to increase as the porosity became occluded by water molecules.


Content; Controlled; Effects; Experiments; Laboratory; Moisture; Phase; Pollutant; Propagation; Soil; Unsaturated; Vapor; Zone

Controlled Subject

Hydrology; Environmental sciences

File Format


File Size

2816 KB

Degree Grantor

University of Nevada, Las Vegas




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