Comparing the compositions and influence of aerosol particles retained on trees, shrubs, and herbs

Abstract

Aerosol particle pollution has become an increasing serious environmental problem, and urban vegetation plays a long-lasting and positive role in mitigating it. This study compared the particle capture abilities of trees, shrubs, and herbs, and examined the compositions and influence of aerosol particles accumulated on leaf functional traits. Retained particles primarily contained Ca²⁺, K⁺, SO₄²⁻, NO₃⁻ and NH₄⁺, indicating their anthropogenic origins. The leathery-leaved tree Osmanthus fragrans and the papery-leaved herb Alternanthera sessilis demonstrated the higher competence in particle accumulation than other plants, and leaf morphologic structures (e.g., leaf grooves, trichomes, waxy layers, and stomata characteristics) were closely associated with particle capture by plant species. Particle retention negatively impacted stomata, impeding photosynthesis, and reducing transpiration. In response to particle accumulation, plants tended to decrease specific leaf area and adjust stomatal conductance. Both growth form and leaf texture significantly influenced the particle capture abilities of different plant species. The substantial contribution of plants, particularly herbs in the lower vegetation strata, to particle removal should not be overlooked. Vegetation with a tree-shrub-herb configuration excels at particle capture, offering potential advantages in mitigating particle pollution and enhancing ecological benefits.