Integrated biomonitoring of airborne pollutants over space and time using tree rings, bark, leaves and epiphytic lichens

The integrated use of tree rings and outer tissues, and lichens, was tested for monitoring how pollutantconcentrations vary in space and over time nearby an incinerator in industrial area in Central Italy. Traceelements in thalli of lichen Xanthoria parietina and in leaves, bark, wood of Quercus pubescens, as well ascarbon, oxygen and nitrogen isotope ratios in tree rings were analyzed. Some trace elements in the leavesdiffered significantly between the plots, though this was not the case in lichens and bark. The values of13C and 18O showed the same trend in all plots, while the values of 15N were higher in the distal plot.The results indicated that trace elements were intercepted and collected by tree bark and leaves, as wellas lichens, at low concentrations, and that they hardly entered into tree xylem tissues during the growingseason to be stored into the woody tissues. Indeed, the study did not highlight marked changes over timeand space, in accumulation of airborne pollutants in the selected biomonitors, most probably due to thelow levels of industrial development. Nevertheless, the analysis of tree ring cores in combination withbark and leaves, and lichens might potentially contribute to depict historic impacts of airborne pollutantsat pronounced concentrations.