Manisha Mishra, U.C. Kulshrestha This email address is being protected from spambots. You need JavaScript enabled to view it.

School of Environmental Sciences, Jawaharlal Nehru University, New Delhi 110067, India


 

Received: January 19, 2020
Revised: April 8, 2020
Accepted: April 25, 2020

 Copyright The Author(s). This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are cited.


Download Citation: ||https://doi.org/10.4209/aaqr.2019.12.0622 


Cite this article:

Mishra, M. and Kulshrestha, U. (2020). Extreme Air Pollution Events Spiking Ionic Levels at Urban and Rural Sites of Indo-Gangetic Plain. Aerosol Air Qual. Res. 20: 1266–1281. https://doi.org/10.4209/aaqr.2019.12.0622


HIGHLIGHTS

  • NH4+, Ca2+, NO3 and SO42– were found as major WSIIs during winters at both the sites.
  • Spiking levels of ∑WSII in November month were linked to crop residue burning and Diwali.
  • Significant scavenging of crustal dust associated species were observed on foggy days.
  • Fossil fuel and solid waste burning were the major contributors at the urban site.
  • Biomass burning and agricultural activities were dominant sources at the rural site.
 

ABSTRACT


The present study is a modest attempt to quantify the water-soluble inorganic ions (WSIIs) in the early morning (fog-forming) ambient air on the central Indo-Gangetic Plain (IGP) during winter via dissolution using a low-cost refluxing mist chamber. The chemical composition of the bulk samples showed significant differences in the WSIIs between the two monitored sites, one urban and the other rural, with NH4+ (47% and 37%, respectively) and Ca2+ (18% and 8%, respectively) being the major cations and NO3 (10% and 16%, respectively) and SO42– (9% and 14%, respectively) being the major anions. The WSII concentration spiked during November at both locations (∑WSII = 159.6 and 141.9 µg m–3) due to two extreme air pollution events, viz., i) the burning of crop residue and ii) the Diwali festival. These changes, which were corroborated by observations of the meteorological conditions, played an essential role in the wintertime atmospheric chemistry. On foggy days, significant scavenging of ions associated with crustal dust (Ca2+, Na+, Mg2+ and Cl) occurred, although the ambient concentrations of other species (K+, NH4+, NO2, NO3 and SO42–) remained relatively unaffected. Furthermore, the relationship between the cations and anions demonstrated that NH3 and HONO, as the primary gaseous species, were involved in heterogeneous aqueous-phase reactions and the formation of secondary aerosols. Source apportionment based on principal component analysis and the mass ratios also indicated that local anthropogenic sources, in addition to natural ones such as soil/road dust and biogenic emissions, influenced the WSII composition. Vehicular exhaust, solid waste and biofuel burning were identified as the major contributors of WSIIs at the urban site, whereas biomass burning, agricultural activity and coal combustion in brick kilns were the predominant sources at the rural site.


Keywords: Atmospheric chemistry, Mist Chamber, Ionic Interactions, Fog scavenging, Source Apportionment.



Aerosol Air Qual. Res. 20:1266-1281. https://doi.org/10.4209/aaqr.2019.12.0622 


Impact Factor: 2.735

5-Year Impact Factor: 2.827


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