Abstract
According to the United Nations, 55% of the world’s population currently lives in urban areas and which is projected to increase to 67% by 2050. Trees and green spaces are effective strategies for mitigating urban pollution. This study develops a framework to investigate the impact of trichome morphology and wind speed on the deposition of 0.3 μm and 1.0 μm particles at the micro-scale. Representative trichome diameters, D = 5 and 20 μm are investigated by varying their height, H, between 100 to 600 μm with packing density of 5 and 15 mm−2. The results show that trichome diameter, density, and wind speed have a favorable impact on deposition velocity. Compared to a smooth leaf, the presence of the thicker 20 μm hairs increases the deposition velocity by 1.5–4 times, whereas, the presence of short 5 μm trichomes reduces the deposition by 15–45%. Increasing trichome height to diameter ratio from H/D = 20 to 30 shows benefits for the thinner trichomes but lowers the deposition for the densely packed thicker trichomes. Less aerosol deposition is also observed when the particle diameter increases from 0.3 μm to 1.0 μm. Within the scope of this study, the complex interplay between these various traits, is captured via a non-dimensional ratio Rhp to model the aerosol deposition on the leaf surface. The results offer valuable insight into the effects of trichome morphology on pollutant deposition in isolation from other environmental and macro-factors.
