Urban environments are increasingly impacted by heavy metals pollution originating from traffic emissions, solid waste burning, and other anthropogenic sources (i.e., foundries, smelters, oil refineries, petrochemical plants, pesticide production, and chemical industries). Suspended particulate matter (SPM) serves as a carrier for heavy metals, posing a potential risk to vegetation and human health. This study aimed to investigate the levels and distribution of heavy metals, including Ag, Cd, Co, Mo, V, As, Cr, Ni, Pb, Cu, Mn, Zn, and Fe, accumulated on the surface and inside the leaves of six plant species (Ficus benghalensis, Ficus religiosa, Polyalthia longifolia, Azadirachta indica, Ficus benjamina, and Bougainvillea glabra) during the pre-and post-monsoon at Okhla Phase-2 and Siri Fort in the Delhi, India. Leaves samples were collected from both sites during the pre- and post- monsoon and analyzed for heavy metals content using Inductively Coupled Plasma Optical Emission spectroscopy (ICP-OES). Results revealed that the pre-monsoon exhibited about 9 % higher levels of heavy metals concentration than post-monsoon, possibly because of washout effects due to rainfall during the monsoon and seasonal variations in atmospheric deposition. Moreover, among all plant species the average of accumulated heavy metals in the both seasons inside the leaves has been observed in the following pattern: F. benjamina (55.51 mg/kg) > B. glabra (43.77 mg/kg) > F.benghalensis (40.55 mg/kg) > A. indica (34.23 mg/kg) > P. longifolia (34.00 mg/kg) > F. religiosa (31.51 mg/kg). The study highlighted F. benjamina and B. glabra as potential bioindicators of heavy metal pollution due to their higher metal’s uptake.

The findings of this research contribute to understanding heavy metals pollution in urban areas, emphasizing the importance of monitoring, and mitigating the impact of atmospheric deposition on vegetation. Furthermore, identifying plants with varying metals accumulation capabilities can aid in developing phytoremediation strategies to combat metallic pollutants.

Keywords: Heavy metals, Bougainvillea glabra, Atmospheric deposition