Trees can deposit the air-borne dust on their leaves thus they can improve air quality in urban condition. The degree of deposition is also affected by the species, the shape and surface of leaves. In addition to the trees, we also find herbaceous plants, perennials, annual and shrubs in public place to imitate the forest ecosystems, and on their leaves the air-borne dust can also deposit.
Next to a busy road (Astoria, VII. district, Budapest), there is a flower bed where we collected leaf-samples of some species to determine the amount of dust on their leaves. We chose the following species from the flowerbed: Coreopsis grandiflora, Gaillardia aristata, Tradescantia × andersoniana, Rosa sp. and Verbena bonariensis.
The samples were prepared according to Margitai and Braun (2005). Beakers were weighed beforehand and the leaf samples were washed into the beakers with 80 ml of distilled water and shaken on a shaker for 2 hours. The leaves were then removed and the distilled water from the suspension containing the powder was evaporated in a drying oven at 115 Celsius-degrees. After that, beakers were weighed again and the amount of dust deposited by the leaves was calculated by subtracting the starting weight. Individual leaf area was determined by leaf scanner to count the total leaf area of species.
The leaf surface of each species differs significantly, however, their ability to deposit dust depends on the surface of the leaves (hairiness, roughness, etc.). As in forest ecosystems, it is important for green surface in cities to have three levels (such as perennials, shrubs and trees). These levels can filter more effectively the dust from urban air. If we developed three-level plantings between roads and pathway, the filtering effect can also be increased. This solution not only satisfies our aesthetic needs but is also useful. Further studies are needed to prove this.
Szabo, Veronika and Kohut, Ildiko
"Foliar dust on leaves of some perennials,"
Proceedings of the Fábos Conference on Landscape and Greenway Planning: Vol. 7:
1, Article 8.
Available at: https://scholarworks.umass.edu/fabos/vol7/iss1/8