Air pollution monitoring by lichens in a small medieval town of central Italy

Air quality and the deposition pattern of trace elements were assessed in Siena (Central Italy) using epiphytic lichens. Air quality was assessed in terms of the Index of Atmospheric Purity (IAP) based on frequency counts of lichen species in 25 stations in the urban area. Forty-six species of epiphytic lichens were found. There were no lichen desert areas and some widespread species of lichens which could facilitate future surveillance monitoring programmes were identified. Trace element deposition was estimated by analysing the thalli of Parmelia caperata, collected in 28 urban sites, Among the elements considered (Al, B, Ba, Ca, Cd, Cr, Cu, Fe, K, Mg, Mn, Na, P, Pb, S, Zn) Pb was the most widespread, indicating that despite the progressive introduction of unleaded fuel this metal is still emitted copiously (and/or resuspended) by traffic. The results of the two biomonitoring approaches used in the study area were compared.