The Assessment of Atmospheric Pollution of Heavy Metals with the Help of Ornamental Plants in Isfahan Landscape

Plants are the most common bioindicatorsused in air quality biomonitoring studies because they are immobile and they have more sensitive to the most prevalent air pollutants than humans and animals. To identify the concentrations and sources of heavy metals in ornamental plants of Isfahan landscape, samples of leaves and soil around Pinuseldarica and Nerium oleander were collected at different distances (1, 4 and 10 km) from the most populated and dense vehicle traffic area of Isfahan and control site with and opposite wind directions (SW and NE).For determination of heavy metal contamination source, plant leaves were washed with distilled water. Finally, concentrations of zinc, lead and cadmium in soil and plant samples were determined by atomic absorption. Heavy metals were found at higher concentrations in the all studied sites in comparison with control. Heavy metal concentrations were increased with reducing distance from contamination center with wind direction. Negligiblecorrelation between plant available Zn and Pb concentrations in soil and metal contents in plant leaves and reduction of these metals by water washing treatment indicated that soil cannot be the source of metal contamination in plants. Both ornamental plants were found to be appropriate indicators for airborne Zn and Pb contamination, especially Nerium oleander.