| Particulate matter (PM) pollution causes serious problems on human health and environmental crisis, which has been widely concerned. Numerous studies have demonstrated that plants can purify air by absorbing atmospheric pollutants, and may significantly affect air quality. This study evaluated deposits of PM on the leaves and in the wax layer of common plant species in Beijing, China in 2014. This study measured night typical kinds of PM water inorganic ions. To test the relationships between leaf traits and PM accumulation, leaf samples of selected species were observed using a scanning electron microscope (SEM). The results of this study may inform the selection of species for urban green areas where the goal is to capture air pollutants and mitigate the adverse effects of air pollution on human health.The major conclusions are as follows:There are some water inorganic ions in the presence of PM which are accumulated on plant leaf surface. There are linear positive correlation between the amount of water inorganic ions and total surface particles (TSP). The main ions are NO3-, SO42-, Ca2+ and Mg+. The components of water inorganic ions are mainly decided by the source of particulate matter in the atmosphere.Differences in the accumulation of PM were observed between species and in different seasons. Plants could absorb more TSP in spring and winter than in summer and autumn. The PM2.5 accumulation on leaf surface has little difference between seasons. Aiphyllium trees could accumulate a lot of particles in spring, while aiphyllium trees accumulate similar amounts of particles in other seasons. It is a gradual process for plants to accumulate particulate matters in wax layer.There is significant correlation between TSP and PM2.5, PM10 accumulations on deciduous trees’ leaf surfaces and in their wax layers. The adsorption abilities of different plants will change with seasons. The microstructures of leaf surface and leaf aera index (LAI) influence the adsorption abilities of plant species. The herbs in this study could accumulate little PM. Shrubs could accumulate more PM than herbs and trees could accumulated the most PM.The plants exhibiting high amounts of total PM accumulation (on leaf surfaces and/or in the wax layer), also showed comparatively high levels of PM accumulation across all particle sizes. Growth forms with greater amounts of pubescence and increased roughness supported PM accumulation; the adaxial leaf surfaces collected more particles than the abaxial surfaces. The particles are mainly accumulated in the grooves of the leaf surfaces. There are a lot of particles accumulated near the leaf veins.Total leaf area of individual plant has a decisive role on the adsorption ability of plant. The larger the total leaf area is, the more PM accumulated on the whole plant. There are quiet differences of PM accumulation among different species. Pinus tabulaeformis, Pinus armandii and Salix matsudana could absorb more PM than the other species. In the six main districts, plants could accumulate 1211.16kg/km2 TSP,242.41kg/km2PM10 and 90.11kg/km2PM2.5.A comparison of shrubs and trees did not reveal obvious differences in their ability to accumulate particles based on growth form; a combination of plantings with different growth forms can efficiently reduce airborne PM concentrations near the ground. |
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