Screening of heavy metal pollution in Bulgaria using Populus nigra 'Italica'

The pollution with As, Cd, Co, Cr, Cu, Fe, Mn, Pb, Sb and Zn on the territory of Bulgaria has been evaluated using standardized samples of leaves of Populus nigra 'Italica' collected during the last 10 years. Background values for the respective elements are established in the leaves of the plant. The comparisons of urban and industrial pollution to some other European countries indicates similar or lower concentrations. Using cluster analysis of the analytical data the territory of Bulgaria is divided into six regions with different pollution levels.