Capacity of Landscaping Plants to Accumulate Airborne Particulate Matter in Hangzhou, China

Plants have a great capacity to absorb airborne particulate matter (PM), which can be used to improve air quality in severely polluted regions. We selected eight common landscaping plants in Hangzhou, China, and determined the different-sized PM adsorption capacities of their leaf surfaces and wax layers using gravimetric analysis. In addition, we used scanning electron microscopy to observe surface microstructures of the leaves to determine relationships between their microstructural characteristics and adsorption capacities. Results showed that the capacity of these eight species to accumulate PM varied markedly, showing obvious differences in particle retention between trees and shrubs. The densities of PM per unit leaf area of the various plants ranged from 12.4 mu g/cm(2) to 151.8 mu g/cm(2), with Fatsia japonica > Ilex latifolia > Eriobotrya japonica > Magnolia grandiflora > Rhododendron pulchrum > Cinnamomum camphora > Trifolium repens > Albizia julibrissin. There was a close relationship between surface microstructures of the leaves and their PM adsorption capacities: the rougher the leaf surface and the greater the furrow depth, the better their capacity for PM adsorption, resulting in a greater dust-retention capacity. Clearly, understanding retention of PM on different plants can aid in the selection of landscaping plants to reduce urban air pollution.