Distribution of Heavy Metals in Leaf and Bark of Trees Used in Urban Forestry of Hamadan

The role of trees in reducing the amount of heavy metals in the air and thus reducing the environmental risks cannot be denied. In the present study, distribution of cadmium, nickel, lead and zinc metals was investigated in leaf and skin of Plane tree, Ash and Eldarica pine in urban parks of Hamadan. For this purpose, in the different parks of Hamadan, samples were taken from the skin and leaves of the trees. After transferring the samples to the laboratory and digesting them, the concentration of metals was measured by atomic absorption. Comparison of the concentration of heavy metals in the leaves and the skin of the tree species showed that the Plane trees have a higher ability to absorb of heavy metals than the Ash and Eldarica pine trees. The zinc concentration in the skin and the leaves of the trees was higher than the concentrations of other elements. Comparison of the concentrations of the elements in the skin and the leaves of the trees with global standards showed that the concentration of cadmium in the skin and leaves of trees was higher than the standard limit and the concentration of nickel in the skin of the two Plane tree and Ash species was higher than the standard limit Which indicates the pollution of the urban environment. Correlation between the concentration of heavy elements in the skin and the leaves of the trees showed that there was a significant positive correlation between cadmium concentrations in leaves and skin of Plane tree and Eldarica pine trees (P <0.05). In general, the comparison of heavy metal concentrations in the leaf and skin of the tree species showed that Plant tree and Ash were very effective in absorbing heavy metals from their surroundings than Eldarica pine.