Leaves of Pittosporum tobira as indicators of airborne trace element and PM10 distribution in central Italy

Leaves of the evergreen ornamental shrub species Pittosporum tobira were used as a passive monitor to describe the distribution of selected elements in three coastal cities of central Italy (namely Livorno, Rosignano Marittimo and Piombino) differing for number of inhabitants and economical activities. Unwashed healthy mature leaves collected in June 2004 from 88 sampling sites covering the whole municipalities according to a systematic stratified unallineated sampling design were analysed by ICP-MS for Al, Ba, Be, Bi, Br, Ca, Cd, Cl, Co, Cr, Cs, Cu, Fe, K, Li, Mg, Mn, Mo, Na, Ni, Pb, Si, Ti, V and Zn. Values were normalised by subtracting baseline concentrations of biologically essential elements. Enrichment factors were calculated taking Al as crustal reference element. Factor analysis allowed to identify three main source groups of elements, namely crustal components, sea-salt spray and anthropogenic sources (vehicular traffic, industrial activities). SEM–EDX analyses were performed on 556 PM10 samples collected from the 88 sampling sites. High contributions of geological elements and marine aerosols were detected. Pb is no longer of environmental concern in the area. Results are discussed with emphasis on the potential role of vegetation for the removal of particulate pollution.