Assessment of plant species suitability in green walls based on API, heavy metal accumulation, and particulate matter capture capacity

Abstract

Today, one of the most pressing issues confronting the civilized and modern world is air pollution.Particulate matter (PM) is a well-known pollutant that contributes signi cantly to urban air pollution and has numerous short-and long-term adverse effects on human health. One method of reducing air pollution is to create green spaces, mainly green walls, as a short-term solution. The current study investigated the ability of nine plant species to reduce tra c-related PM using a green wall system installed along a busy road in Mashhad, Iran. The main aims were (1) estimate the tolerance level of plant species on green walls to air pollution using the Air pollution tolerance index (APTI); (2) assess the PM capture on the leaves of green wall species using Scanning Electron Microscopy (SEM), Energy Dispersive X-ray (EDX) analysis and accumulation of heavy metals using Inductively Coupled Plasma (ICP); (3) select the most tolerance species for reducing air pollution using Anticipated Performance Index (API). The plants' APTI values ranged from 5 to 12. The highest APTI value was found in Carpobrotus edulis and Rosmarinus o cinalis, while Kochia Prostrata had the lowest. Among the APTI constituents, leaf water content (R 2 = 0.29) and ascorbic acid (R 2 = 0.33) had a positive effect on APTI. According to SEM analysis, many PM were adsorbed on the adaxial and abaxial leaf surfaces, as well as near the stomata of Lavandula angustifolia, C. edulis, Vinca minor, and Hylotelephium sp. Based on EDX analysis, carbon and oxygen formed the highest amount (more than 60%) of metals detected in the elemental composition of PM deposited on the leaves of all species. The Sedum re exum had the highest Cr, Fe, Pb, and As accumulation. The concentrations of all heavy metals studied in green wall plants were higher than in the control sample. Furthermore, the C. edulis is the best plant for planting in industrial, urban areas of the city based on APTI, biological, economic, and social characteristics. It concludes that the use of green walls composed primarily of plants with small leaves can signi cantly adsorb PM and accumulation of heavy metal.

A biochemical and morphological study with multiple linear regression modeling–based impact prediction of ambient air pollutants on some native tree species of Haldwani City of Kumaun Himalaya, Uttarakhand, India

“…Wax-like foliar accumulation in P. guajava and C. citrinus (Fig. 3 n and p) act as a transpiration inhibitor, which justifies the increase in water content at the polluted site (Banerjee et al 2022 ; Hozhabralsadat et al 2022 ). At the control site, the clear and open stomata along with guard cells and linear striations can be seen at the epidermis of P. guajava and C. citrinus .…”

“…In this investigation, relatively fewer stomata were observed for A. indica and T. ciliate in comparison to C. citrinus and P. guajava . A study by Hozhabralsadat et al ( 2022 ) found that the plants with low stomatal density have high potential retention of fine particles. In the present study, the stomatal density and trichomes were more in the polluted site as compared to the control site.…”

“…In the present study, the stomatal density and trichomes were more in the polluted site as compared to the control site. So, it can be concluded that the presence of more stomata on the surface is an adaptation to the leaf to survive under stressed and polluted conditions (Hozhabralsadat et al 2022 ). Similarly, the trichomes provide biochemical and physical resistance by secreting secondary metabolites (Banerjee et al 2022 ).…”

“…Surface deposition of atmospheric particulates on tree foliage is assessed by the size, kind, and characteristics of the particles and surface to which they adhere. Plant hairs, trichomes, and non-smooth surfaces have been assisted in the deposition and storage of suspended particles (Adhikari et al 2022 ; Banerjee et al 2022 ; Hozhabralsadat et al 2022 ). Various processes in vegetation such as photosynthesis, biochemical, morphological (Banerjee et al 2022 ; Enitan et al 2022 ), and physiological processes vary under susceptibility toward varying levels of air pollution (Thawale et al 2011 ; Zhao et al 2021 ).…”

A Nature-Inspired Green–Blue Solution: Incorporating a Fog Harvesting Technique into Urban Green Wall Design

“…Water's ability to capture pollutants in the air [5] and the air-purifying attributes of green vegetation constitute additional advantages conferred by the implementation of systems aimed at advancing the United Nations Sustainable Development Goals (SDGs) [6][7][8][9][10][11][12][13][14][15][16]. By integrating fog harvesting technology into green wall systems, the overall sustainability of these structures is enhanced.…”