Black poplar-tree ( Populus nigra L.) bark as an alternative indicator of urban air pollution by chemical elements

Capabilities of black poplar-tree (Populus nigra L.) bark as a biomonitor of atmospheric air pollution by chemical elements were tested against epiphytic lichens Xanthoria parietina (L.) and Physcia adscendens (Fr.). Concentrations of 40 macro and trace elements were determined using epicadmium and instrumental NAA. The data obtained were processed using non-parametric tests. A good correlation was found between concentrations of majority of elements in bark and lichens. On the accumulation capability bark turned out to be competitive with both lichens examined. The main inorganic components of black poplar-tree bark were revealed. A substrate influence on the concentrations of some elements in epiphytic lichens was established. An optimized procedure of bark pre-irradiation treatment was suggested.