REMEDIATION OF CONTAMINATED SOIL USING COMPOST: CHARACTERIZATION OF THE ORGANIC MATTER

The humic substances (HS) are macromolecules involved in many chemical and biochemical processes of great importance for soil fertility and environmental equilibrium. The HS ensure a slow release of nutrients, a high soil quality and a less extent of green house gas emissions. The addition of organic matter to contaminated soils, especially those with organic pollutants (PAH, PCBs, LAS) has been recently employed successfully. For these reasons, the addition of biomasses more or less rich in humic-like compounds had become important to improve the quality of organic matter in exploited or contaminated soils. The aim of this study' was to characterize the organic matter of three contaminated soils located in North Italy, before and after the remediation with two different kind of compost. The soils analyzed came from a stone quarry, a landfill and from an industrial area in disuse. The samples extracted and separated in the two classical conventional fractions (humic and fulvic acids) have been investigated using some humification parameters and different analytical techniques: potentiometric titrations, spectroscopic (FT-IR) and thermal analysis (TG and DTA) were applied to obtain structural information. The results have shown a general increase in the organic matter in the soil samples amended with biomasses respect to untreated soils. In particular, thermal analysis reveals an increase of the second exotermic peak after the soil treatment due to the presence of organic matter more resistant to the degradation. DRIFT spectra confirm a structural change of the soil organic matter well correlated with the amendment type. Note: 'Research supported with funds provided by PRIN-Cofin 2002 (National Coord. P. Genevini).