Capacity of six shrub species to retain atmospheric particulates with different diameters

Garden plants can absorb and retain atmospheric particles and are important for remediating environmental pollution. In this study, the dust retention characteristics of six typical shrub species were measured in the greenbelt of a road in the Chengyang District of Qingdao, China, and the maximum capacity for dust retention of each species was determined. The different diameters and areas occupied by particulate matter (PM) were analyzed on the leaf surfaces of the plants. Based on the results for the six shrub species, the rank order of average content of dust retention per unit leaf area was Euonymus japonicus > Pyracantha fortuneana > Ligustrum vicaryi > Amygdalus triloba > Ligustrum sinense > Forsythia suspensa, whereas the rank order of average content per unit volume was E. japonicus > A. triloba > P. fortuneana > L. vicaryi > L. sinense > F. suspensa. The maximum content of dust retention per unit leaf area was reached in approximately 24 days. Plants retained atmospheric PM primarily on the upper leaf surfaces. The primary portion of particles on the leaves was PM₁₀ (over 80%), and PM_2.5 was the principal component of PM₁₀. Leaf surface structure significantly affected the abilities of plants to retain PM, and the plants with a thick wax layer or large and dense stomata adsorbed more PM, such as E. japonicus. This study provides a scientific basis for the capacity of landscape plants to retain different diameter particulates.