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

Plants play a crucial role in mitigating air pollution, which can be evaluated by examining their biochemical characteristics, including ascorbic acid, total chlorophyll content, pH, and relative water content. These traits provide valuable insights into plants' capacity to counteract atmospheric pollutants. Moreover, combining air pollution tolerance and Suspended Particulate Matter (SPM) retention potentials could lead to an adequate assessment of plant species for greenbelt development. This study assessed biochemical characteristics and SPM retention potential of six selected plant species (Ficus benghalensis L, Ficus religiosa L, Polyalthia longifolia (Sonn.) Thwaites, Azadirachta indica A.Juss, Ficus benjamina L, and Bougainvillea glabra) at polluted (Okhla Phase-2) and non-polluted (Siri Fort) sites in Delhi, India, during pre- and post-monsoon. In addition, based on biochemical characteristics, the Air Pollution Tolerance Index (APTI) of selected plant species has been calculated. Also, the impact of changes in independent variables such as the relative water content, ascorbic acid, pH, and total chlorophyll content on the APTI of different plant species was assessed using linear regression. The study found that A.indica exhibited the highest APTI of 9.43 and F.benghalensis the lowest APTI of 8.3 during pre- and post-monsoon. Also, the maximum and minimum recorded values of the total SPM adhesion on the leaves of F. benghalensis and F. religiosa during pre- and post-monsoon were 1305.46 g/cm2 and 185.51 g/cm2, respectively. Additionally, in the statistical analysis, the highest linear regression coefficient (R2 = 0.93) was observed between ascorbic & total chlorophyll content with APTI, indicating a substantial impact on the APTI calculation of these biochemical parameters. This study demonstrated that plants with elevated biochemical parameters, APTI, and SPM retention potential can effectively reduce air pollutants from the atmosphere. These findings highlight the importance of considering specific biochemical characteristics and SPM retention potential when selecting plant species for greenbelt development.

Bio-methanation offers a safe, effective, and efficient avenue for the environmentally sound disposal of urban organic waste, while concurrently facilitating the recuperation of valuable by-products. A well-maintained Bio-methanation facility with organic waste as input feed can not only help decrease the waste disposal costs, reduce the volume (and mass) of waste that needs to be processed, and create multilateral employment opportunities but also fosters the production of clean electricity and Compressed Biogas (CBG). Various programs and schemes initiated by different governments in India aim to address the imperatives of waste management and escalating energy demands. These strategic initiatives actively encourage the establishment of Bio-methanation plants (BMPs) by local communities, regional authorities, and private enterprises. Despite the recognition of its potential, the actual number of successfully operational BMPs across India remains relatively low. This dearth of success in operating and managing existing Bio-methanation facilities may emerge as a critical restraint for prospective stakeholders (owners, builders, and operators) when contemplating new plant installations. Consequently, comprehensive research is indispensable to advance energy recovery from waste and to establish standardized design parameters for BMPs. The present investigation intends to appraise the current status of select BMPs in India, conscientiously collating and presenting information pertaining to critical parameters such as size/design capacity, type of reactor, no. of stages employed, etc. Additionally, the study identifies the challenges encountered by plant operators and technology providers in their pursuit of effective plant operation, thus, presenting valuable insights for further development and optimization of the existing technologies. B02-07, Article available at AGU23 Website