SOIL POLLUTION BY HEAVY METAL AND MICROELEMENT MONITORING IN URBAN AREA.

Soil contamination by heavy metals, such as cadmium, lead, chromium, copper, zinc, mercury and arsenic, is a matter of great concern. Heavy metals are present naturally in the soil, but their levels are increased by industry (non-ferrous industries, power plants, iron, steel and chemical industries), agriculture (irrigation with polluted water, use of mineral fertilisers), waste incineration, combustion of fossil fuels and road traffic. Reduction of heavy metal emissions is the most direct way to decrease the atmospheric deposition of these elements and their build-up in the soil. In order to evaluate soil pollution in urban areas a monitoring activities focused on the soil-plant system were led in the last 2 years by our study group. Urban parks were investigated and used as indicator of soil contamination by heavy metal due to wet and dry atmospheric deposition. Heavy metal deposits on soils remain predominantly in the top few centimetres and can cause health risks for children and old people that usually frequent this green areas. The same approach was used to monitoring the land surrounding an incineration in the municipality of Granarolo dell'Emilia (Bologna province). The monitoring activities, focused on the soil-plant system, included seasonal sampling of topsoil, leaves, turfs and musks, at 12 sites located within a 3 km range from the incinerator and 6 urban parks in 3 different city of Emilia Romagna Region ( Bologna, Ferrara, Cesena). Each monitoring program lasted one year, during which four sampling campaigns were conducted in correspondence of seasonal changes. The samples collected were suitably treated and analysed by means of optical emission spectrometry using a CCD detector (ICP-OES, Spectro CIR.O.S.CCD). Integrated analysis of the different environmental matrixes permitted identification of the most critical sites, from an environmental standpoint, with respect to the content of heavy metals and microelements and the data repeatability. In addition a correlation between soil pollution and atmospheric deposition on leaves (broadleaf and conifer) and musks (Hypnum cupressiforme) were found. In particular the zones of the urban parks, directly connected with the main street, show critical concentrations of some elements (Zn and Pb) exceeding the limits established by current laws and directly connected with vehicular emissions.