EVALUATION OF GEOCHEMICAL BACKGROUND AT REGIONAL AND LOCAL SCALES BY FRACTAL FILTERING TECHNIQUE: CASE STUDIES IN SELECTED ITALIAN AREAS

Backgrounds represent, in the environmental field, the borderline between concentrations of a chemical element that naturally occurs in a media as compared with the concentrations of the same analytes present as a result of anthropogenic activities. To evaluate background values, there are two basic approaches: statistical frequency analysis and spatial analysis. Statistical frequency analysis uses techniques for characterizing the frequency distribution based on the assumption that point data from different locations may originate from different sources and represent different populations. Spatial analysis refers to methods dealing with spatial distribution of values on a 2-D map where geochemical point data are generally interpolated. In this paper, the application of GeoDAS software to perform multifractal inverse distance weighted interpolation and a fractal filtering technique, named spatial and spectral analysis (or simply the S-A method), will be illustrated, to evaluate geochemical background at regional and local scale.