Holm Oak (Quercus ilex L.) canopy as interceptor of airborne trace elements and their accumulation in the litter and topsoil

► Of the main metal contaminants only leaf Pb concentrations decreased in the period 1994-2011. ► Leaf Cd, Cr, Cu, Pb and Zn concentrations were higher in urban than in extra urban park. ► In urban park litter, Cu, Cd, Pb and Zn concentrations were higher outside than underneath the tree crown. ► Conversely, in urban park soil, Cu, Cd, Pb and Zn concentrations were lower outside the crown. ► Soil therefore behaves as a sink for metal contaminants such as Cu, Pb and Cd.