Polycyclic aromatic hydrocarbons (PAHs) accumulation in urban plants.

Recent research demonstrated the role of urban vegetation in the interception and degradation of air pollutants in cities. Trees, shrubs and plants can improve the quality of the air we breathe by filtering out certain air pollutants. Dense screens of trees and shrubs can be used efficiently to provide quieter areas in city parks where people can relax away from the constant background noise of city life. In addition, the foliage of vegetation can trap certain air pollutants, especially air-borne particulates, removing them from the urban atmosphere. Leaf samples of the evergreen shrubs Elaeagnus x ebbingei; Ilex aquifolium; Laurus nobilis; Ligustrum spp.; Photinia x fraserii and Viburnum lucidum were collected at two sites of the urban area of Udine (NE-Italy) and at a control site in the Agriculture Experimental Farm of University of Udine. Ultrastructural aspects of leaf morphology were investigated by means of Transmission electron microscopy (TEM). Polyciclic Aromatic Hydrocarbons (PAHs) extraction was conducted on dried leaves by sonication in dichloromethane; extracts were analyzed by HR-GC–MS, after clean up on Florisil columns. The target PAHs were those addressed by EU air quality directive 2008/50/EC, i.e. benzo(a)pyrene, benz(a)antracene, benzo(b)fluoranthene, benzo(j)fluoranthene, benzo(k)fluoranthene, indeno(1,2,3-cd)pyrene and dibenzo(a,h)anthracene. Since plants exposed to air pollutants experience physiological changes before exhibiting visible damage to leaves, the Air Pollution Tolerance Index (APTI) was calculated considering the ascorbic acid, total chlorophyll, pH, and relative water contents for leaves collected in control and experimental sites. The project started in October 2010 and it is currently running. The expected results will provide valuable information for greenbelt designers and urban landscapers to select tolerant plant species for the urban green.