Abstract
In this study, we have coupled measurements, modeling, and remote sensing techniques to better delineate the source characteristics and variability of air pollutants in Delhi primarily during the post-monsoon season in 2019. We show a comparison of ambient PM2.5 (particulate matter having aerodynamic diameter ≤2.5 μm) levels and associated elements during the post-monsoon with those during a relatively clean season of monsoon (experiencing frequent wet precipitation). Air-mass back trajectories from Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model have been used to infer the possible source pathways of PM2.5 impacting at the receptor site in Delhi. The average concentrations of PM2.5 during monsoon (June–July) and post-monsoon (October–November) were 42.2 ± 15.5 μg m−3 (range: 22–73 μg m−3) and 121.4 ± 53.6 μg m−3 (range: 46–298 μg m−3), respectively. The PM2.5 samples were analyzed for heavy and trace elements (Si, S, Na, Mg, Al, Cl, Ca, K, Ti, V, Cr, Mn, Fe, Ni, Cu, Br, Rb, Zr, and Pb) using an Energy Dispersive X-ray Fluorescence (ED-XRF) technique and their concentrations have been used to carry out the source-apportionment utilizing principal component analysis (PCA) tool. The PCA analysis has identified three major sources of fine aerosols including contributions from the sources viz. vehicular emission, biomass burning, coal combustion, secondary aerosols formation, soil dust, solid-waste burning and industrial emission. The source involving biomass burning contributed largely to the PM2.5 in post-monsoon season through long-range transport of large-scale agriculture-residue burning emissions (occurring in the states of Punjab, Haryana, and western part of Uttar Pradesh). The industrial emissions include primarily, medium- and small-scale metal processing industries (e.g. steel sheet rolling) in Delhi-National Capital Region. Traces of emission from coal based thermal power plants and waste incineration have also been observed in this study.
Highlights
Clean and healthy air is essential to all life on earth and is crucial for the well-being of human beings and the optimum performance of its supporting ecosystems
The PM2.5 data monitored by the Central Pollution Control Board (CPCB) at four nearby sites (Aya Nagar, IGI Airport, PUSA and Sri Aurobindo Marg) was taken into account to assess the spatial heterogeneity in PM2.5 mass concentrations
The average PM2.5 concentration at the sampling site i.e., Jawaharlal Nehru University (JNU) is lower than the other adjoining areas in the post-monsoon season
Summary
Clean and healthy air is essential to all life on earth and is crucial for the well-being of human beings and the optimum performance of its supporting ecosystems. The atrocious levels of particulate matter (PM) pollution in the atmosphere has created a disconcerting situation across the world’s scientific and political communities, especially in developing countries due to their climatic and human health impacts (Khodeir et al, 2012; World Health Organization, 2016). Numerous harmful impacts of PM exposure such as pulmonary and cardiovascular diseases, allergies and premature deaths have been evinced in several epidemiological studies (Badyda et al, 2016; Ghude et al, 2016). The study has mentioned that exposure to ambient PM2.5 resulted in ∼9.8 lakhs premature deaths in a year and is of the major concern to human health point of view. Another research has estimated that PM2.5 exposures could lead to average loss of life expectancy (LLE) of 3.4 years for the country with the highest value of LLE of 6.3 years for Delhi (Ghude et al, 2016)
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