Surface-Based Analysis of Leaf Microstructures for Adsorbing and Retaining Capability of Airborne Particulate Matter in Ten Woody Species

Abstract

We evaluated surface-based analysis for assessing the possible relationship between the microstructural properties and particulate matter (i.e., two size fractions of PM2.5 and PM10) adsorption efficiencies on their leaf surfaces of Aesculus turbinata, Chionanthus retusus, Ginkgo biloba, Liriodendron tulipifera, Magnolia denudata, Styphnolobium japonicum, Taxus cuspidata, Buxus koreana, Euonymus japonicus, and Rhododendron schlippenbachii. We focused on the effect of PM adsorption capacity between micro-morphological features on leaf surfaces using a scanning electron microscope and a non-contact surface profiler as an example. The species with higher adsorption of PM10 on leaf surfaces were B. koreana and E. japonicus, followed by M. denudata, T. cuspidata, A. turbinata, C. retusus, G. biloba, and R. schlippenbachii. There was a higher capacity for the adsorption of PM2.5 on the leaf surfaces of B. koreana and T. cuspidata, followed by A. turbinata, C. retusus, E. japonicus, G. biloba, and M. denudata. In wax layer tests, T. cuspidata, A. turbinata, R. schlippenbachii, and C. retusus showed a statistically higher PM2.5 capturing capacity than the other species. Different types of trichomes were distributed on the adaxial and abaxial leaves of A. turbinata, C. retusus, M. denudata, S. japonicum, B. koreana, and R. schlippenbachii; however, these trichomes were absent on both sides of the leaves of G. biloba, L. tulipifera, E. japonicus, and T. cuspidata. Importantly, leaf surfaces of G. biloba and S. japonicum with dense or thick epicuticular leaf waxes and deeper roughness revealed lower PM adsorption. Based on the overall performance of airborne PM capture efficiency, evergreen species such as B. koreana, T. cuspidata, and E. japonicus showed the best results, whereas S. japonicum and L. tulipifera had the lowest capture. In particular, evergreen shrub species showed higher PM2.5 depositions inside the inner wall of stomata or the periphery of guard cells. Therefore, in leaf microstructural factors, stomatal size may be related to notably high PM2.5 holding capacities on leaf surfaces, but stomatal density, trichome density, and roughness had a limited effect on PM adsorption. Finally, our findings indicate that surface-based microstructures are necessarily not a correlation for corresponding estimates with leaf PM adsorption.

Characterizing leaf-deposited particles: Single-particle mass spectral analysis and comparison with naturally fallen particles

“…These findings imply that different plant species influence the chemical makeup of deposited particles differently. This could be due to the unique surface properties of the leaves of each species, affecting how particles adhere and react upon deposition [ 45 ].…”

Particulate Matter (PM) Adsorption and Leaf Characteristics of Ornamental Sweet Potato (Ipomoea batatas L.) Cultivars and Two Common Indoor Plants (Hedera helix L. and Epipremnum aureum Lindl. & Andre)

“…However, it is well known that the microstructure of the leaf surface has a strong influence on its ability to retain PM. On the surface, there are dense, narrow, and deep grooves that provide enough space for the particles to be retained [19]. According to several studies, the presence of stomata helps retain PM [68,69].…”

“…Furthermore, different types of plant leaves have various physiochemical traits, which means that their capacity to absorb PM particles significantly varies. Therefore, several studies have been conducted on the effects of physiological characteristics and leaf morphology on PM removal efficiency [16][17][18][19]. At the leaf scale, the accumulation ability is highly correlated to leaf morphology and microstructure, such as leaf and waxy cuticle shape, leaf roughness, leaf pubescence, and leaf surface wettability [20][21][22].…”

Comparative analysis of the dust retention capacity and leaf microstructure of 11 Sophora japonica clones

“…The reason might be that leaf furrows increased leaf surface roughness, and stomata and fur increased the contact area between leaf surface and air. The enhanced dust-catching ability of leaf surface [ 35 – 37 ] may also be due to the fact that atmospheric particles contact with the surface fur and enter through the cracks in the leaf’s cuticle, thus increasing the dust-catching ability of leaf surface as a whole [ 38 , 39 ]. The SEM & AFM index, and the dust retention index revealed a significant positive correlation between the leaflet area and total dust retention per unit leaf area under natural and artificial conditions.…”