Impacts of unsaturated zone reaeration on the bioattenuation of organic contaminants in groundwater systems

Simple item page
dc.contributor.advisorHughes, Joseph B.
dc.contributor.advisorWard, C. H.
dc.creatorNeale, Charles Nelson
dc.date.accessioned2009-06-04T08:24:46Z
dc.date.available2009-06-04T08:24:46Z
dc.date.issued2000
dc.description.abstractReaeration, or the diffusion of O2 through the unsaturated zone and into an aquifer system, is a mechanism that influences the extent of hydrocarbon contaminant bioattenuation in ground water. A series of laboratory and numerical modeling experiments were completed to determine the amount of O2 supplied to an anaerobic aquifer by reaeration under various unsaturated zone conditions and to quantify the impacts of reaeration on the migration of hydrocarbon plumes in ground water. Results from laboratory experiments indicated that reaeration flux rates exhibited a bimodal distribution and either approached 12,000 Mg/M2-day or were less than 2,000 Mg/M2-day. Soil water content significantly affected the reaeration flux rate while soil type, soil O2 utilization rate, and unsaturated zone thickness did not influence the reaeration rate. In some cases, the capillary rise impeded O2 transport into the bulk ground water due to high water content near the base of the capillary region. An unsaturated zone transport model was developed to predict reaeration flux based on the effective diffusion coefficient of soil (Ds), liquid-side mass transfer coefficient (KL), Soil O2 utilization rate (Rsoil), and unsaturated zone thickness (z). Good agreement was generally found between the predicted and experimental flux results. Results from numerical modeling experiments indicated that reaeration reduced the steady-state length of hydrocarbon plumes in ground water for aquifer hydraulic conductivities of K = 10--2 cm/s and K = 10--4cm/s. Important groundwater reaeration parameters having an influence on the steady-state hydrocarbon plume length included the concentration of O2 in the overlying soil gas (C O2(g)), the ground water mass transfer coefficient (KL,GW), the vertical dispersivity in the saturated zone (alphav), and the zone of reaeration or the thickness of the top model layer (ZR). The relative importance of each of these parameters was on the order of alphav > > KL,GW > CO2(g) > ZR.
dc.format.extent307 p.en_US
dc.format.mimetypeapplication/pdf
dc.identifier.callnoTHESIS ENV.SCI. 2000 NEALE
dc.identifier.citationNeale, Charles Nelson. "Impacts of unsaturated zone reaeration on the bioattenuation of organic contaminants in groundwater systems." (2000) Diss., Rice University. <a href="https://hdl.handle.net/1911/19538">https://hdl.handle.net/1911/19538</a>.
dc.identifier.urihttps://hdl.handle.net/1911/19538
dc.language.isoeng
dc.rightsCopyright is held by the author, unless otherwise indicated. Permission to reuse, publish, or reproduce the work beyond the bounds of fair use or other exemptions to copyright law must be obtained from the copyright holder.
dc.subjectEnvironmental science
dc.subjectEnvironmental engineering
dc.titleImpacts of unsaturated zone reaeration on the bioattenuation of organic contaminants in groundwater systems
dc.typeThesis
dc.type.materialText
thesis.degree.departmentEnvironmental Science
thesis.degree.disciplineEngineering
thesis.degree.grantorRice University
thesis.degree.levelDoctoral
thesis.degree.nameDoctor of Philosophy
Files
Original bundle
Now showing 1 - 1 of 1
Thumbnail Image
Name:
9969298.PDF
Size:
10.06 MB
Format:
Adobe Portable Document Format
Download
Collections
Rice University Electronic Theses and Dissertations