Boadu This research explores the possibility of assessing non-invasively, the evolution of the structural changes in contaminated soils of different composition. The hypothesis is that structural changes result from changes in the size of inter-particle spacing, and compositional changes result from ionic or solution replacement in the spacing. These changes result in modification of hydraulic conductivity and porosity. Knowledge about such changes in contaminated soils is important and needs to be assessed non-invasively if proper measures are to be taken to implement storage or remediation of contaminants.
The investigation will involve laboratory measurements of the spectral electrical response of contaminated soils integrated with theoretical and equivalent circuit models of the soil-contaminant system. Studies of the electrical properties will provide information on the pore geometry and pore surface area as both transport of free charge carriers in the pore space and polarization at the pore-grain interfaces contribute to the total conductivity. The experimental study involves soil-contaminant mixtures of varying ratios of clay, silt and sand, mixed with pore fluids that will include organic and inorganic chemicals (acids and bases) and petroleum products (e.g., kerosene). Soil mixtures will be allowed to interact over time and the frequency-dependent electrical response will be measured. An inversion method using a nonlinear optimization scheme, simulated annealing, will be employed to retrieve the electrical and physico-chemical parameters of the soil system over time. ***
