Geochemical background and baseline values of toxic elements in stream sediments of Campania region (Italy)

In this paper are discussed the baseline geochemical maps of elements harmful to human health, using concentration values of 2389 stream sediment samples collected over the Campania region (Southern Italy). Each sample was digested in aqua regia and analysed by ICP-MS. For compilation of baseline geochemical maps, a recently developed multifractal inverse distance weighted (lDW) interpolation method and spectral analysis (S-A) was applied, using a new geochemistry dedicated GIS software (GeoDAS). The aim of this study is to discriminate between the geogenic natural content (background) and the anthropogenic contribution in the collected sediments. The definition of background values, in contrast to baseline values, is very important in determining the extent of polluted areas in countries like Italy, where environmental legislation has not yet established intervention limits for stream sediments.In the Campania region, baseline and background values are often coincident, where the samples represent catchment basins away from urban or industrial areas. Potential polluted areas are often very small in size, except for some sites where the anthropogenic influence on sediments is clearly evident, due to the wide extent of local industrial and agricultural activities (e.g., the Sarno River catchment basin).R-mode factor analysis has proved very useful in distinguishing geochemical data, clearly dominated by anthropogenic in comparison to geogenic sources.