Potential of Particle Matter Dry Deposition on Green Roofs and Living Walls Vegetation for Mitigating Urban Atmospheric Pollution in Semiarid Climates

Abstract

Abstract:In the last two decades, the incorporation of green roofs and living walls in buildings has increased significantly worldwide because of their benefits such as building energy savings, promoting biodiversity, controlling water run-off, mitigating urban heat island effect, improving indoor and urban air quality, and connecting people with nature. However, few studies have quantified the impact of green roofs (GRs) and living walls (LWs) on mitigating air pollution, especially in semiarid climates where airborne particle matter (PM) levels are high. Therefore, the aim of this paper is quantifying the dry deposition of PM 10 and PM 2.5 by several vegetation species commonly used in GRs and LWs in semiarid climates. Five species (Pitosporum tobira, Lavandula angustifolia, Lampranthus spectabillis, Sedum album, and Sedum reflexum) for GRs and four species (Aptenia cordiflora, Erigeron karvinskianus, Sedum palmeri, and Sedum spurium p.) for LWs were tested in an experimental facility-through washing, filtering, and weighing-to quantify the dry deposition of PM 2.5 and PM 10 on vegetation leaves as well as PM captured by the leaf wax. The main result is that a significant amount of PM is deposited on the typical vegetation used in GRs and LWs in semiarid climates. However, large differences in PM dry deposition were found among species, ranging from 0.09 µg/cm 2 ·h −1 to 1.32 µg/cm 2 ·h −1 for PM 2.5 , 0.48 µg/cm 2 ·h −1 to 4.7 µg/cm 2 ·h −1 for PM 10 and 0.41 µg/cm 2 ·h −1 to 25.6 µg/cm 2 ·h −1 for leaf wax. The species that showed the highest potential to capture PM were S. album, S. reflexum, S. palmeri, and L. spectabillis. This study shows this green infrastructures can contribute to mitigate air pollution, thus GRs and LWs have the potential for being included in decontamination plans.

Designing vegetation barriers for urban air pollution abatement: a practical review for appropriate plant species selection

“…Epicuticular wax ultrastructures were also found to be significant in PM deposition to both conifers and broadleaves by a number of other studies 36,90,103,113 . Grote et al 77 suggest that this may be partly due to leaf wettability, with particle concentrations significantly reduced through reactions with wet surfaces, and water-soluble pollutants such as NO 2 and SO 2 subject to dissolution in a water film at the leaf surface.…”

“…Leaf size and shape or complexity Differences in leaf size and complexity are significant predictors of deposition, particularly for PM 91 . Numerous field experiments have found that species with smaller leaves tend to be more effective than species with larger leaves, which may be partly attributed to the higher perimeter/surface area ratio of smaller leaves 103 . For example, a recent study into leaf characteristics for traffic-related PM (PM 1 , PM 2.5 and PM 10 ) capture found that leaf size inversely correlated with PM accumulation, whereas there were no leaf surface characteristics that showed a clear correlation with PM accumulation across species 104 .…”

“…Generally, rough leaf surfaces are more effective for deposition than smooth surfaces 36,88,91,103,107,110,111 . For example, Weerakkody et al 91 reported a number of beneficial traits for PM capture, including, most significantly, small leaf size and complex leaf shape (macromorphological features, discussed above), as well as trichomes, epicuticular wax and surface ridges (micromorphological features).…”

Green Facades and Living Walls—A Review Establishing the Classification of Construction Types and Mapping the Benefits

“…Empirical data from a survey on the perception of local people and employees of the VGS installed on one office building in Genoa, Italy revealed that people see VGS as effective tools to improve air quality and the urban environment [68]. Another empirical study by Viecco et al [69] aimed to quantify the dry deposition of particle matters by vegetation species (Pitosporumtobira, Lavandulaangustifolia, Lampranthusspectabillis, Sedumalbum, and Sedumreflexum) in semiarid climates. The species with the highest potential to capture particle matter were S. album, S. reflexum, S. palmeri, and L. spectabillis.…”

The impact of forest fire on air-quality and visibility in Palangka Raya

“…Particulate removes of the atmosphere through washing by rainwater and deposites due to gravity settling or an object such as a plant. Some plant specieses have a good ability to deposite particulate for reducing particulate in urban ambient air (Viecco et al, 2018). The smaller the particle size the greater the viscosity force so that it becomes more difficult to settle in the ground.…”