Definition of a site as contaminated: Problems related to agricultural soils

For defining a soil as contaminated and to be remediated, it is necessary to make a risk analysis for assessing the risks for human health and environment and the exposure pathways to contaminants. The tools currently available, consider only the direct risks for people who frequent a residential or commercial/industrial site, but the risks related to agricultural soils are not laid down in Italian legislation. In this last case, the risks for human health can be defined as indirect since they are due to the uptake of contaminants by the food crops and to the consequent dietary exposure of population. Therefore, the risks of contamination of food chain are represented only by the bioavailable fraction of potentially toxic elements (PTEs) that can be absorbed by crops, rather than by the total content of PTEs into the soil that often is not mobile. Once environmental characterization and risk analysis allow classification of an agricultural site as contaminated, then its remediation must be undertaken, but it must aim to progressively reduce the bioavailable portion of PTEs. In this regard, the use of environmentally friendly techniques based on the use of natural resources (e.g. vegetation and soil microflora) resulted the most suitable both for the reduced costs and for the positive environmental impact. Indeed bio and phytoremediation allow protecting soil and its ecosystem services. The main steps of ecocompatible remediation of contaminated soils carried out in the Ecoremed projects are reported in this volume from the detailed geophysical and geochemical characterization, and the assessment of ecological and dietary risks, to the agriculture-based techniques for remediation and to the evaluation of the impact on ecosystem services of such soils.