Urban vegetation has the potential to improve air quality as it promotes pollutant deposition and retention.Urban air quality models often include the effect vegetation have on pollution dispersion, however, processesinvolved in pollution removal by vegetation are often excluded or simplified and does not consider differentvegetation characteristics. In this systematic review, we analyze the influence of the large interspecies variationin vegetation characteristics to identify the key factors affecting the removal of the major urban pollutants,particulate matter (PM) and nitrogen dioxide (NO2) from the air through vegetation deposition.
The aim is toidentify key processes needed to represent vegetation characteristics in urban air quality modelling assessments.We show that PM is mainly deposited to the leaf surface, and thus representation of characteristics affectingthe aerodynamics from canopy down to leaf surface are important, such as branch/shoot complexity and leafsize, leaf surface roughness and hairiness. In addition, characteristics affecting PM retention capacity, resuspensionand wash-off, include leaf surface roughness, hairiness and wax content. NO2 is mainly depositedthrough stomatal uptake, and thus stomatal conductance and its responses to environmental conditions are keyfactors. These include response to solar radiation, vapour pressure deficit and soil moisture.Representation of these vegetation characteristics in urban air quality models could greatly improve ourability to optimize the type and species of urban vegetation from an air quality perspective.
A-rapport,A2674.