Characterization of atmospheric trace gases and water soluble inorganic chemical ions of PM1 and PM2.5 at Indira Gandhi International Airport, New Delhi during 2017-18 winter

Prodip Acharja; Kaushar Ali; Dinesh Kumar Trivedi; P D Safai; Sachin Ghude; Thara Prabhakaran; M Rajeevan

doi:10.1016/j.scitotenv.2020.138800

Characterization of atmospheric trace gases and water soluble inorganic chemical ions of PM₁ and PM_2.5 at Indira Gandhi International Airport, New Delhi during 2017-18 winter

Sci Total Environ. 2020 Aug 10:729:138800. doi: 10.1016/j.scitotenv.2020.138800. Epub 2020 Apr 22.

Authors

Prodip Acharja¹, Kaushar Ali², Dinesh Kumar Trivedi³, P D Safai³, Sachin Ghude³, Thara Prabhakaran³, M Rajeevan⁴

Affiliations

¹ Indian Institute of Tropical Meteorology, Dr. Homi Bhabha Road, Pashan, Pune 411008, India; Savitribai Phule Pune University, Ganeshkhind Road, Pune 411007, India.
² Indian Institute of Tropical Meteorology, Dr. Homi Bhabha Road, Pashan, Pune 411008, India. Electronic address: kaushar@tropmet.res.in.
³ Indian Institute of Tropical Meteorology, Dr. Homi Bhabha Road, Pashan, Pune 411008, India.
⁴ Ministry of Earth Sciences, Prithvi Bhavan, Lodhi Road, New Delhi 110003, India.

PMID: 32361437
DOI: 10.1016/j.scitotenv.2020.138800

Abstract

Water soluble inorganic chemical ions of PM₁ and PM_2.5 and atmospheric trace gases were monitored simultaneously on hourly resolution at Indira Gandhi International Airport (IGIA), Delhi during 8 December 2017-10 February 2018. Monitoring was made by MARGA (Monitoring AeRosol and Gases in ambient Air) under winter fog experiment (WIFEX) program of the Ministry of Earth Sciences (MoES), Government of India. The result based on the analysis of the data so generated reveals that Cl^-, NH₄⁺, NO₃^- and SO₄^2- were dominant ions in order which collectively constituted 96.8 and 97.3% of the of the total measured ionic mass in PM₁ and PM_2.5 respectively. Their overall average concentrations in PM₁ were 19.5 ± 19.7, 18.4 ± 10.5, 16.6 ± 8.7 and 10.3 ± 5.7 μg/m³ and in PM_2.5 were 36.0 ± 33.9, 32.7 ± 17.2, 28.5 ± 13.6 and 19.9 ± 13.9 μg/m³. Average concentrations of HCl, HNO₃, HNO₂, SO₂ and NH₃ trace gases were 0.7 ± 0.3, 2.7 ± 1.1, 6.6 ± 4.7, 22.0 ± 12.3 and 25.7 ± 9.1 μg/m³ respectively. Weather parameters along with low mixing height played significant role in the occurrence of high concentration of these chemical species. NH₄⁺ was the prime neutralizer of the acidic components and mostly occurred in (NH₄)₂SO₄/NH₄HSO₄, NH₄NO₃ and NH₄Cl molecular forms. Major sources of these chemical species were fossil fuel combustion in aviation activity and transportation, coal burning in thermal power plants, industrial processes and emissions from biomass burning and agro-based activity. The quality of air with respect to PM_2.5 always remained deteriorated. It became alarming during low visibility period mainly due to high concentration of Cl^-, NO₃^-, SO₄^2- and NH₄⁺. Both meteorological and chemical processes interactively fed each other which occasionally resulted in fog development and visibility degradation. The knowledge gained by this study will help in simulation of atmospheric processes which lead to fog development and dispersal in the Delhi region.

Keywords: Chemical ions; Fine particulate; IGIA; MARGA; Meteorology; Trace gases.