SOIL CONTAMINATION AT THE DUMP-FIELD OF ABANDONED Cu-DEPOSIT LIBIOLA, ITALY

In the past centuries significant and now closed Libiola copper deposit in Liguria (Northern Italy) can be considered one of the most important mining areas of the Apennine Peninsula. The environmental risk is caused by the character of the dump matter, whose average pH is 4.03 and whose shows a high proportion of sulphidic sulphur (in average 0.30 %) in comparison with sulphate sulphur (in average of 0.10 %), so it has still great potential to create acidity and release potentially to the country components (soil, water, atmosphere, and biota) potentially toxic elements. The average concentrations of these elements are: Fe 16.37 %, Cu 3.753, Ni 771, Pb 35, As 12, and Cd 1.5 mg•kg-1. To characterize the mineralogical composition of the dump matter was used X-ray diffraction analyses. The risk is increased by the absence of carbonates, which could neutralize the acidity. On the other hand, the soil colloids have negative surface charge which facilitates the sorption of metals released into the solution and thus cause their partial immobilization. This article also presents the potential distribution of main potentially toxic elements, processed as an interpolation model in GIS.