A dendrochronological evaluation of the effects of air pollution on radial growth of Pine trees

Tehran is one of the most polluted cities in the world and is a good candidate for the evaluation of the effects of pollution caused by vehicles on the radial growth of Pine (Pinus eldarica) trees.Trees have been cored at three sites: Azadi Square, the most polluted site, and two others spots: Chitgar Park and Sorkhehesar Park, our control sites. The concentrations of the heavy metals (Pb, Mn, Ba, Cu, Zn) in the tree rings determined by ICP showed no significant difference between the rings when grouped in 5-yr intervals, but their concentrations at the Azadi site were significantly higher than those at the control sites. The comparison of the pine trees of the same age at the three sites indicates that radial growth of pines at Azadi Square has been reduced over the past 10 years.A comparison between this research and similar studies indicates that tree rings in dry regions such as Tehran with calcareous soil are not as good bio-monitors as the trees in wet regions with acidic soil.