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Title: Applied gas tracing or permeable reactive barriers (PRBs)
Author: Newton, B. T.
Awarding Body: Queen's University Belfast
Current Institution: Queen's University Belfast
Date of Award: 2013
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The aim of my thesis is to evaluate the use of applied dissolved noble gas tracers for the estimation of flow and transport parameters in permeable reactive barriers (PRBs) and for the assessment of changes in those parameters over time. PRBs consist of reactive materials that are p l aced in the subsurface to intercept a contaminant plume. PRBs have been proven to effectively remediate a variety of groundwater contaminants. The main limitation to the use PRBs as a remediation tool is the build up of mineral precipitates and gases that may inhibit water flow through the barrier, decrease the reactivity of the PRB medium, and reduce the residence time of contaminated water. Applied chemical tracers provide the most direct measurement of how water moves through PRBs to assess the effects of mineral precipitation and gas evolution on flow and transport parameters in PRBs. Tracer experiments in laboratory columns and full scale permeable reactive barriers are described in detail , highlighting advantages and disadvantages of using noble gases as applied tracers. The volatility of noble gases presents advantages and disadvantages. The retardation of dissolved gas tracers, as a result of interactions with gas bubbles trapped in pore spaces, provides information about the volume of a gas phase that is present in the system. However, the degassing of dissolved gas tracers during tracer injection, sampling , and sample preparation can result in many uncertainties with respect initial tracer concentrations. These uncertainties are best dealt with by using multiple noble gas tracers along with a "conservative" tracer such as Bromide or Chloride. This thesis demonstrates that noble gases can be used effectively as applied tracers to assess the long - term effectiveness of PRBs.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available