Complex permittivity measurement system for detecting soil contamination

The design, calibration, and operation of a laboratory-scale system to assess the viability of detecting contaminants in soil based on changes in its electromagnetic response are described. The complex permittivity measurement device, permeation apparatus, and dielectric responses of soil specimens measured before and after permeation with different CaCl2 solutions are discussed. It is shown that the change in the complex permittivity of the soil is best characterized in terms of the permittivity and loss factor at the frequency of 250 MHz, since they exhibit a significant response to changes in the pore-fluid chemistry. The laboratory system can be used routinely to create soil samples permeated with a known contaminant at known concentrations and then measure the complex permittivity of the contaminated soil samples directly after permeation. The system is such that other factors (e.g., density and water content) which could influence the complex permittivity can be carefully controlled, allowing the relationship between the type and level of contamination and dielectric behaviour of soils to be established.