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Characteristics and Sources of Trace Elements in Fine Mode Aerosols at Delhi: A Long-Term Trends Analysis (2013-2021)
* , , , ,
1  CSIR-National Physical Laboratory, Dr. K S Krishnan Road, New Delhi-110 012, India
2  Academy of Scientific and Innovative Research (AcSIR), Ghaziabad-201 002, India
Academic Editor: Patricia Quinn

Published: 14 November 2023 by MDPI in The 6th International Electronic Conference on Atmospheric Sciences session Aerosols

Trace elements contribute a small fraction to fine-mode aerosols as compared to the other chemical species (organic & inorganic) and affect the ambient air quality and human health. In this paper, we report the inter-annual and seasonal concentrations, and sources of trace elements in PM2.5 over Delhi, India based on long-term analysis (2013–2021). In all the PM2.5 samples 19 trace elements were extracted: Na, Mg, Ca, Mn, Al, Fe, Ti, Cu, Zn, Cr, Ni, As, Mo, Cl, P, S, K, Pb, and Br. The total annual mean concentration (∑El in PM2.5) of trace elements was 17.49±3.13 µg m-3 which is accounted for 13.9% of PM2.5 mass concentration. Enrichment factor (EF) and IMPROVE model analysis indicate the seasonal abundance of mineral/soil dust (Fe, Al, Ti, Na, Ca, and Mg) at the sampling site of Delhi, India. During the sampling period, the highest loading of trace elements was recorded in 2015 (19% of PM2.5) and the lowest in 2020 (9% of PM2.5) due to restricted activities during covid-19 lockdown/unlock periods. Four major sources of trace elements (in PM2.5) were extracted by principal component analysis as crustal/soil dust, vehicular traffic/industrial emissions, combustion (solid+fossil fuels), and sodium magnesium salts in Delhi. This long-term study on the elemental composition of PM2.5 will be useful for policymakers in mitigating ambient air quality and improving human health.

Keywords: PM2.5, Trace elements, Enrichment factor, Source of elements