The focus of the research reported in this thesis is the quantification of colloid transport through porous media, which is implicated in the contamination of soil and shallow groundwater. The limited spatio-temporal resolution of existing experimental techniques prevents the formulation of testable hypotheses for colloid transport within· complex (environmentally-relevant) porous media and therefore restricts further progress in the understanding of colloid movement in the environment. The research presented here responds to this premise by developing, testing and applying a high spatial and temporal resolution, meso-scale (millimetre to decimetre) fluorescence imaging system for measurement ofcolloids transport in porous media. A review of existing literature highlights the restrictions placed on the parameterisation of theoretical models by the low resolution of experimental datasets such as breakthrough curves and retained mass profiles. Previous applications of meso-scale imaging techniques do not extend to quantitative measurement of colloids in unsaturated or transient flow through porous media. In Chapter 2 an existing UVfluorescence imaging system is modified and calibrated to enable quantification of changing colloid mass distributions over time in saturated pore conditions. In Chapter 3 the technique, Time Lapse Fluorescence Imaging, is further extended to enable quantification oftwo-dimensional spatial variations in pore saturation, simultaneously with measurement of colloid mass. A data analysis method is developed to enable quantification of the colloid removal efficiency (ratio of deposition rate to colloid flux) at any point in a variably saturated flow field. In Chapter 4, the methods developed in previous chapters are applied to the problem of colloid mobilisation during drainage ofa previously-saturated quartz sand. The descriptive power of the novel meso-scale fluorescence imaging techniques. presented provides important objective data that will help to extend the theoretical framework for colloid deposition to non-uniform, unsaturated flow and to constrain transport models for colloids in the vadose zone.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:486545 |
| Date | January 2007 |
| Creators | Bridge, Jonathan |
| Publisher | University of Sheffield |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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