Accumulation of metals in the leaves of different urban forest tree species and its relation to the proximity to the airport.

Metal pollution in urban areas has become a serious problem during the last two decades because of vehicular emission, industrial activity, fossil fuel use, and their accumulation constitutes a serious environmental hazard. The aviation sector puts additional impact on the environment further impacting human health. Urban trees can uptake and accumulate pollutants in their tissues, through their roots and leaves. This study aimed to determine whether airport traffic has toxic effects on airport's vegetation, to compare five urban trees with different morphological and silvicultural characteristics (Pinus brutia, Tamarix sp., Populus alba, Olea europaea, Nerium oleander) regarding their foliar metals (Cu, Ni, Pb, Mn, Fe, Co, Cr, Cd, Zn) accumulation, and to find out how proximity to the airport affects above accumulation. Airport of Thessaloniki, northern Greece (SKG) was the case study where data were collected. Results showed that forest tree species presented different heavy metal accumulation patterns. The metals concentration in leaf samples was low and did not exceed toxicity threshold, both inside and outside the airport area. The taller trees with extensive crown surface area i.e., the deciduous and fast-growing tree species P. alba and the evergreen conifer tree species P. brutia, were the most affected. The proximity to the airport area had strong influence on the metal's concentrations in the foliage of P. brutia, while in the other tree species it significantly affected only one or two metals.