UTILIZZO DI MUSCHI E LICHENI TRAPIANTATI IN BAGS NEL MONITORAGGIO DELLA QUALITÀ DELLARIA IN AMBIENTE URBANO

Monitoring of pollutants consists in the quali-quantitative determination of the presence and distribution of each pollutant and of its space- temporal deposition. Mosses and lichens are widely used as indicators and/or monitors of air contamination due to their remarkable accumulative capacity for pollutants. In the present study moss and lichen bags were exposed along Naples city streets characterised by high vehicular traffic over a period of 10-17 weeks to evaluate the space-temporal air born deposition of trace elements. The species employed were the lichen Pseudevernia furfuracea (L.) Zopf and the moss Sphagnum capillifolium (Ehrh.) Hedw., both collected in the Alpi Carniche (Northern Italy), a natural, relatively unpolluted habitat. After collection moss and lichen were extensively washed with distilled water, air dried and gently mixed to make homogeneous specimens. Aliquots of 400 mg were employed to prepare nylon bags (1 mm2 meshes). At the beginning of July 1999 the moss bags were exposed to atmospheric wet and dry depositions, at 3 to 10 meters height from soil, in 24 sites of the urban area of Naples. The study area measures 15 km2 about and is situated in the town of Naples on the west coast of southern Italy. The concentration of the elements Pb, Zn, Ni, Cu, Cr (III and VI), Sn, Co, Cd, As, V, Ti, Fe, Al, Mn, Ba, Ca, Na, K and Mg in the moss and lichen material prior and after to exposure was determined by Atomic Absorption Spectrophotometry (AAS). For most of the analysed elements the levels in the original moss and lichen material did not differ appreciably. Al, Fe, K, Mg, Mn and Ti values were found significantly higher in the moss than in the lichen. Opposite behaviour was shown by Ca and Pb. Data obtained will be used to produce deposition maps for each element and correlated to bioindication studies to provide a possible interpretation of contamination sources and trends.