Extreme Air Pollution Events Spiking Ionic Levels at Urban and Rural Sites of Indo-Gangetic Plain

Abstract

The present study is a modest attempt to quantify the water-soluble inorganic ions (WSIIs) in the early morning (fogforming) 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 NH 4 + (47% and 37%, respectively) and Ca 2+ (18% and 8%, respectively) being the major cations and NO 3-(10% and 16%, respectively) and SO 4 2-(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 (Ca 2+ , Na + , Mg 2+ and Cl-) occurred, although the ambient concentrations of other species (K + , NH 4 + , NO 2-, NO 3and SO 4 2-) remained relatively unaffected. Furthermore, the relationship between the cations and anions demonstrated that NH 3 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.

A Brief Review on Changes in Air Pollution Scenario over South Asia during COVID-19 Lockdown

“…2) (Metya et al, 2020). Cities located in Indo Gangetic plain region (northern India) which also suffers severe pollution all through the year have showed a significant improvement in AQI values due to reduction in local contributions (Jain and Sharma, 2020;Mishra and Kulshrestha, 2020). The major contributors of air pollution in India are transport sector, biomass burning, industries, construction activities, power plants and road dust resuspension (Guttikunda et al, 2014;Singh et al, 2016).…”

Spatio-Temporal Variation of Atmospheric Gaseous and Particulate Reactive Nitrogen over Northern India

“…35,40 Exceptionally, higher values in post-monsoon season at Delhi can also be attributed to the crop residue burning incidents in the northwestern region of IGP and its transportation to the downwind regions, since none of the other local activity changes wereobserved. 41 Seasonal contribution at Madhupur village was totally different from the urban locations. The pattern was in the order of Summer (41%) > monsoon (24%) > postmonsoon (23%) > winter (12%), suggesting the local factors which might be impacting the distribution pattern.…”

Source Impact Analysis Using Char-EC/Soot-EC Ratios in the Central Indo-Gangetic Plain (IGP) of India

“…A small amount of the extracted sample was also used to analyze K + ions using ion chromatography (IC). The detailed principle and working of IC have been already discussed in previous studies (Mishra and Kulshrestha, 2020;Tiwari and Kulshrestha, 2019). Several field blanks (10% of collected samples of each season) and lab blanks were also analyzed along with the batch of samples for quality control and assurance (QA & QC).…”