Heavy metal accumulation and anatomical responses of plane plant to urban pollutions in two areas of Tehran

Urban pollutions have adverse effects on plants, which results in changing the anatomical properties of leaves. The present study aimed at studying the cadmium (Cd), lead (Pb), zinc (Zn), copper (Cu), nickel (Ni) and chromium (Cr) accumulation in plane (Platanus orientalis) leaves and its anatomical response to urban pollutions in the center of Tehran (most polluted area) as compare to Chitgar Forest Park (CFP) (lowest polluted area). For this purpose, 20 healthy trees, each location 10, were selected to investigate the stomatal density, width and length of stomata, mesophyll parenchyma as well as epidermis and cuticle thickness in summer of 2014. The results showed that the concentration of Cd, Pb, Ni, Cr, and Cu in Tehran was more than those in CFP. Stomatal density in the urban area and CFP were measured 211.9 and 224.7 per mm2, respectively, and the length and width of stomata in urban area was significantly less than those in CFP. The thickness of upper and lower epidermis in urban area was less than that in CFP. The changes observed in anatomical properties are the strategies to resist the stress induced by urban pollution. Plane trees are an appropriate sink for heavy metals, but they rapidly respond to the commutation of heavy metals by changing their anatomical properties. Hence plane trees are sensitive to such value of pollution.