f Wavelet technique applied to localisation and interpretation of electrical signal distortions produced by pollutants in soils

On the bases of previous laboratory results, we performed and tested a Geoelectrical Integrated Method (GIM) to investigate and monitor the presence of chemical and organic pollutants near riverbed, water tables, and urban waste deposits. The GIM is based on the electrical parameters obtained both at frequency and DC conditions in laboratory and in `in situ'. So doing no destructive and low cost investigations allow find the presence of pollutants and evaluate the volume of polluted terrain. In particular it will be possible discriminate macromolecules of organic pollutants from metallic ions. To find the class and the quantity of pollutants in soils and rocks we can use the different electrical behaviour of organic compounds and metallic ions at the solid-liquid interface as function of electrical frequency in the DC÷200kHz range. In particular the electrical behaviour of polluted soil samples resulted strongly no-linear and consequently the output waveform are distorted. We used the classical THD% (% Total Harmonic Distortion) and the HD%(ω) parameters to quantify the deformation level. This method allows to identify the frequency interval of nonlinear electrical behaviour, that is strictly dependent of the pollutant molecular size and give an "electrical signature" of the pollutant-mineral interaction.