Heavy metals in the soil-plant system: monitoring urban and extra-urban parks in the Emilia Romagna Region (Italy)

SUMMARY. - For each of three Emilia Romagna Region (Italy) cities (Bologna, Ferrara and Cesena) an urban park situated in the historical heart of the city and an extra-urban park were selected. The aim of the study was to assess the concentration of heavy metals and microelements in different environmental matrixes, namely: soil, leaf tissues of coniferous and deciduous trees, mosses (spp. Hypnum cupressiforme) and grass, and washed-leaves water. The concentration of heavy metals (Cd, Co, Cu. Cr, Ni, Pb, Zn) was detected using an ICP-OE Spectrometer. For sampling point of Massari park in Ferrara city (FE-M1) and of Giardini Margherita park in Bologna city (BO-M3) heavy metals concentrations exceeded the threshold values established by the current Italian laws for soils of "public, residential and private areas" (D.Lgs 152/2006). The correlation between the concentration values of top- and subsoil highlights that some elements, such as Cd, Cu, Pb and Zn, have an anthropic origin and are mainly linked to the deposition of airborne pollutants, while other elements (Co, Cr and Ni) have a lithologic origin. The study of mosses, grass and the washed-leaves water made it possible to identify seasonal variations of pollutants deposition and, furthermore, to calculate the enrichment coefficient and the accumulation of heavy metals over time.