The distance from road effects on heavy metals accumulation in soil and leaves of Persian oak trees (Quercus brantii) in Aleshtar- Khorramabad highway

Heavy metals are important environmental pollutants which cause risks for humans, plants and microorganisms by entering to the food chains. This study was done to determine the adsorption of heavy metals in soil and leaves of Persian oak trees in Aleshtar - Khorramabad highway. For this purpose, on the five transects at intervals of 0, 500 and 1000 meters on each side of the road, plots whith 10 × 10 meters were selected. In each plot, 30 soil samples and 30 leaf samples from all directions of crown were collected. After preparation of samples, concentration of heavy metals of lead, copper and zinc on soil and leaves were measured using atomic absorption device. The results showed that the concentration of soil heavy metals decreased with increasing distance from the road. The amount of heavy metal concentration in soil was obtauid respectively in distances 0, 500 and 1000 meters 4.6, 2.65 and 3 for lead, 56.13, 55.38 and 55.32 for zinc and 44.81, 45.34 and 38.00 mg/kg for copper. Also the amount of heavy metal concentration in leaves was obtauid respectively in distances 0, 500 and 1000 meters 0.5, 0.4 and 0.2 for lead, 34.6, 57.3 and 38.00 for zinc and 8.5, 7.3 and 8.6 mg/kg for copper. The results also showed that there is a significant negative correlation between organic matter and soil copper at the 5% level. The concentrations of heavy metals in Persian Oak leaves are lower than the standard values of the world and so this tree species can accumulate heavy metals.