Analysis of tree bark and lichens for detecting contamination and physiological effects in the urban environment of Kaunas (Lithuania)

Abstract

Biomonitoring of air pollution in urban area was studied analyzing samples of Tilia sp. tree bark and lichens. The samples of bark and naturally growing Xanthoria parietina were collected removing a surface layer of the bark and lichen thallus. Samples of the lichen Evernia prunastri were transplanted for 5 weeks at the study sites and changes in ecophysiological parameters (photosynthetic pigments, membrane lipid peroxidation, cell membrane damage) were assessed. The concentration of heavy metals (Pb, Cd, Cu) in the samples were used as an indicator of the level of air pollution in the three sites of different activities. The bark tissue analysis revealed that the highest metal concentrations were obtained in intense traffic zone. The conductivity of the bark samples was found to be a sensitive indicator of pollution. Lichen revealed the increased amount of heavy metals and changes in some physiological parameters in urban sites. Although the tree bark was not as sensitive to pollution as lichens, but it can be used as an indicator for various pollutants in areas, where other bioindicators are unavailable.