Assessing the Capacity of Plant Species to Accumulate Particulate Matter in Beijing, China

Abstract

Air pollution causes serious problems in spring in northern China; therefore, studying the ability of different plants to accumulate particulate matter (PM) at the beginning of the growing season may benefit urban planners in their attempts to control air pollution. This study evaluated deposits of PM on the leaves and in the wax layer of 35 species (11 shrubs, 24 trees) in Beijing, China. Differences in the accumulation of PM were observed between species. Cephalotaxus sinensis, Euonymus japonicus, Broussonetia papyriferar, Koelreuteria paniculata and Quercus variabilis were all efficient in capturing small particles. 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. 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. To test the relationships between leaf traits and PM accumulation, leaf samples of selected species were observed using a scanning electron microscope. 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 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.

Plants and Atmospheric Aerosols

“…The loading of aerosols on leaf surfaces is generally between 20 and 100 μg cm À2 , although lower and higher values have been observed (Burkhardt 2010;Mo et al 2015;Popek et al 2013;Przybysz et al 2014;Sgrigna et al 2015). This is similar to the range of epicuticular waxes (35-100 μg cm…”

“…Studies with two-stage extraction of leaf surfaces with water followed by chloroform (Mo et al 2015;Popek et al 2013;Saebo et al 2012;Sgrigna et al 2015), and analysis of magnetic properties of leaves in high-aerosol urban environments (Hofman et al 2014), have shown that fine aerosols, including those with magnetic properties, become embedded in the surface waxes. This confirms earlier results with other techniques (Kozlov et al 2000;Lin and Schuepp 1996;Oliva and Raitio 2003;Oliva and Valdes 2004;Simmleit et al 1989).…”

“…Leaves may be washed with water and/or organic solvents such as chloroform, followed by filtration and weighing or chemical analysis of the fractions (FreerSmith et al 2005;Mo et al 2015;Oliva and Raitio 2003;Saebo et al 2012;Wyttenbach and Tobler 1998). The advantage of this approach is that it includes the actual microroughness and other local parameters.…”

“…Phytoremediation through planting of urban forests, roadside shrubs, and green walls to reduce urban aerosol concentrations is under active investigation (Beckett et al 1998;Escobedo and Nowak 2009;Freer-Smith et al 1997;Manso and Castro-Gomes 2015;Pugh et al 2012). Urban forests were found to remove 770 Mg of PM 10 year À1 in central Beijing (Mo et al 2015) and 64 Mg year À1 in Atlanta (Nowak et al 2013). Although impressive, these adsorption levels represent <10 % of the ambient atmospheric aerosol burden in polluted environments (McDonald et al 2007;Pugh et al 2012).…”

Multi-scale comparison of the fine particle removal capacity of urban forests and wetlands

“…In recent years, particles have led to hazy weather in many cities in China567. Thus, determining an effective way to reduce particle concentrations in urban areas has become a crucial endeavor.…”