Chemical Composition of PM2.5 in Metropolitan Cities of India: Results from an Extensive Winter Campaign
PRINCE VIJAY, Shreya Dubey, Nidhi Singh, Tamara Schikowski, Harish C Phuleria,
Indian Institute of Technology Bombay Abstract Number: 203
Working Group: Urban Aerosols
AbstractAmbient particulate matter concentrations in metropolitan cities in India and its peripheral towns has been a matter of serious concern for several decades. Understanding that the nature of the chemical composition of particulates changes, the spatial variability can be utilized for identifying probable sources. The study presents a dataset of the chemical composition of PM2.5 collected using MiniVol samplers, from 9 residential locations representing traffic-influenced, industrial-influence and residential zones during winter seasons in the year 2019–20. Identification of contributing sources using chemical ratios as source indicators was attempted. Daily PM2.5 concentrations were 131.3±71.8 for Mumbai, 75.2±33.4 for Bangalore and 192.2±75.5 μgm-3 for Delhi. The fine fraction was dominated by organic matter (OM) with mean concentrations of 45.9±33.6, 24.8±21.4, 60.8±25.8 for three cities respectively; followed by Elemental Carbon (EC) (11.2±3.3) for Mumbai, Sea Salt (SS) fraction (10.1±7.3) for Bangalore and Secondary Ions (SI) 18.56±4.05 μgm-3 for Delhi. Sulfate is the most abundant species among inorganic ions contributing ~40% in PM2.5 fraction. The average concentration of major and trace elements accounted for ~1.5% of PM2.5 mass. The air mass trajectories calculated by HYSPLIT model indicated that the air mass approaches to the observational site mainly from the neighbouring cities and even countries as in case of Delhi. The chemical ratios suggested mixed sources for fine fraction with major contributions from vehicular emissions, re-suspended and/or construction dust, and fossil fuel combustion along with intermittent contributions from biomass and open waste burning. The further analysis to quantitatively estimate source contributions to PM2.5 in urban environments provides useful insights to establish strategies to control anthropogenic air pollution. Further analysis is underway.
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