Soil Spatial Variability in contaminated sites: field sampling procedure in Italy

Assessment of soil spatial variability is a debated crucial matter in the context of agriculture and environmental management, such as precision agriculture, land erosion and contaminated sites. In rural and industrial areas, the natural complex spatial variability of soil properties (mainly due to changing pedogenetic factors) is further complicated by anthropogenic activities related to soil management (such as deep plowing, sloping vineyards, etc.) or land contamination. Above all, natural and anthropogenic processes considerably overlap in industrial sites or areas affected by illegal waste dumping, where several times type/quantity and especially localization of contaminants are unknown. Proper investigation tools, as much as possible providing rapid, unexpensive and reliable data on soil properties and characteristics, are increasingly requested to scientific community for both the assessment of contamination geography and the soil sampling strategies. Then, focusing on soil sampling of contaminated sites in Europe, the procedure is currently performed according to national regulations, in terms of number, location, type and depth of sampling points.  The Italian regulation (Decree 471/99 - Annex 2) provides a sampling scheme in which the number of observations is commensurated to the geographical extent of the contaminated site. However, data obtained by some Italian surveyed sites, in which a denser sampling scheme was applied, evidenced that observations planned by the regulation were too low and unexpected “hot spots” were not adequately identified. For sure, contamination can frequently follow a very complex site-specific geospatial distribution. Hence, since number, location, type and depth of sampling points has very strong consequences in terms of public safety and costs of characterisation and remediation of contaminated sites, it is a key issue to set up the best strategies for ameliorating field sampling to achieve a proper understanding of the geospatial distribution of soil contamination.