09 - Studia Geobotanica. An international journal - Vol. 9 (1989)

LICHENS AS BIOMONITORS OF AIR POILUTION. A CASE STUDY AT MACERATA (ITALY). This study presents the results of a research carried out around an incinerator at Macerata (Central Italy), aiming at monitoring air pollution with the use of epiphytic lichens as bioindicators and bioaccumulators. Two main approaches have been adopted: 1) lndirect approach, based on the relative frequencies of epiphytic species; 2) Direct approach, based on measurements of metal concentrations in the lichen thalli. The two approaches are complementary: the former mainly gives information on pollutants with a long-range deposition, such as S02 and NOx, the latter indicates the pollution by metals. The frequency of species within a 10-mesh grid of 30 x 50 cm has been recorded in 34 sampling stations (average 3 trees per station). The metal concentrations in the thalli of Xanthoria parietina have been recorded in 19 stations. Pollution maps have been constructed by programs of authomatic mapping. Tue results indicate that the incinerator should be considered as the main emitting source for the following metals: Cr, Cu, Fe, Hg, Mn, Ni. The main source for Pb is the vehicular traffic. Al is mostly of terrigenous origin. Most of the gaseous pollutants are probably produced by domestic heating.