The Characteristic Of Foliar Dust Of Main Afforestation Tree Species In Nanjing And Association With Leaf's Surface Micro-Structure

Atmospheric particulate is the main contaminant in the urban area. It has great influence on the environmental quality. Because of the relatively good purification effect, forest plant is prevailingly used to urban ecological environmental protection. In the present work, dust retention for 27 species of plants, Characteristics of size distributions of foliar dust for 29 species of plants, and the micro-structures of leaf were studied to determine the main factors of influencing the dust retention. The main conclusion is as following:(1) The dust retention for different species and type of plants has great discrepancy. The dust retention followed the descending order: shrubs > deciduous arbors > evergreen arbors and decreased with the increase of height and distance of the pollution source. The leaf angle also has significant influence on the dust retention. The results of the Viburnum Awabuki indicated that most of dust was retained when the leaf angle was between 60o～90o and least when 30o～60o.(2) The distributions of foliar dust show bi-peak distributing curve. The main peak for broadleaved species is 10～100μm and that for conifer species is 0～10μm. The dust retention for Cedrus Deodara, Sabina Chinensis(L.)Ant Oine, Juniperus Chinensis Cv.Kaizuka and Taxodium Distichum was least in the selected conifer species and the average specific surface area was 0.82 m2/cm3. As for broadleaved species, the dust retention for Ligustrum Lucidum was the most (0.987 m2/cm3) and that for Pterocarya Stenoptera was the least. The retention for particulate below the size of 2.5μm for conifer species followed the the descending order: Cedrus Deodara > Sabina Chinensis > Dagon Juniper > Osmanthus Fragrans > Taxodium Mucronatum. The size of dust for Amygdalus Persica, Broussonetia Papyrifera and Viburnum Awabuki decreased with the increase of distance and specific surface area for them increased with the increase of distance.(3) The dust retention increased with the increase of the amount of stomata and hair and decreased with the increase of the length of hair.