The Removal Efficiencies of Several Temperate Tree Species at Adsorbing Airborne Particulate Matter in Urban Forests and Roadsides

Myeong Ja Kwak,Sanghee Park,Ji Eun Kim,Handong Kim,Su Young Woo,Yeaji Lim,Saeng Geul Baek,Jongkyu Lee,Kyeong Nam Kim,Se Myeong Seo

doi:10.3390/f10110960

Myeong Ja Kwak, Sanghee Park + Show 8 more

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https://doi.org/10.3390/f10110960

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Abstract

Although urban trees are proposed as comparatively economical and eco-efficient biofilters for treating atmospheric particulate matter (PM) by the temporary capture and retention of PM particles, the PM removal effect and its main mechanism still remain largely uncertain. Thus, an understanding of the removal efficiencies of individual leaves that adsorb and retain airborne PM, particularly in the sustainable planning of multifunctional green infrastructure, should be preceded by an assessment of the leaf microstructures of widespread species in urban forests. We determined the differences between trees in regard to their ability to adsorb PM based on the unique leaf microstructures and leaf area index (LAI) reflecting their overall ability by upscaling from leaf scale to canopy scale. The micro-morphological characteristics of adaxial and abaxial leaf surfaces directly affected the PM trapping efficiency. Specifically, leaf surfaces with grooves and trichomes showed a higher ability to retain PM as compared to leaves without epidermal hairs or with dynamic water repellency. Zelkova serrata (Thunb.) Makino was found to have significantly higher benefits with regard to adsorbing and retaining PM compared to other species. Evergreen needle-leaved species could be a more sustainable manner to retain PM in winter and spring. The interspecies variability of the PM adsorption efficiency was upscaled from leaf scale to canopy scale based on the LAI, showing that tree species with higher canopy density were more effective in removing PM. In conclusion, if urban trees are used as a means to improve air quality in limited open spaces for urban greening programs, it is important to predominantly select a tree species that can maximize the ability to capture PM by having higher canopy density and leaf grooves or trichomes.

Highlights

Urban forests have a wide range of benefits, the purification of air and water quality, mitigation of urban heat islands [1,2], space services for recreational activities [3], and enhancement of the physical and mental health of urban dwellers [4,5]
The primary aim of this study was to demonstrate the amount of particulate matter (PM) adsorbed by major tree species, especially species that are commonly planted in both urban forests and roadsides, and to evaluate tree species that are highly effective at capturing PM particles from the atmosphere in temperate zone trees
The Seoul Forest Park (SFP) and Yangjae Citizen's Forest (YCF),3 which are surrounded by roadsides, are 480,994 m2 (32◦ 32.60 N, 127◦ 2.40 E) and 258,991 m2

Summary

Introduction

Urban forests have a wide range of benefits, the purification of air and water quality, mitigation of urban heat islands [1,2], space services for recreational activities [3], and enhancement of the physical and mental health of urban dwellers [4,5]. Air pollution, including airborne particulate pollutants in urban areas, has become a serious problem in developed and developing countries. It has a detrimental effect on humans, as well as on living organisms, plants, and environments [6]. Forests 2019, 10, 960 service of urban trees has become increasingly important, as they adsorb atmospheric particulate matter (PM), linking adaptation, mitigation, and sustainable management to air pollutants.

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