Insights into size-segregated particulate chemistry and sources in urban environment over central Indo-Gangetic Plain. (January 2021)

• Record Type: Journal Article
• Authors: Singh, Nandita; Banerjee, Tirthankar; Murari, Vishnu; Deboudt, Karine; Khan, Md Firoz; Singh, R.S.; Latif, Mohd Talib
• Is Part Of: Chemosphere. Volume 263(2021)
• Publication Date: 2021-01
• Subjects: Aerosols -- Levoglucosan -- Organics -- Receptor model -- Secondary aerosols; Pollution -- Periodicals; Pollution -- Physiological effect -- Periodicals; Environmental sciences -- Periodicals; Atmospheric chemistry -- Periodicals; 551.511
• DOI: 10.1016/j.chemosphere.2020.128030
• Languages: English
• ISSNs: 0045-6535

Abstract

Abstract: Size-segregated airborne fine (PM2.1 ) and coarse (PM>2.1 ) particulates were measured in an urban environment over central Indo-Gangetic plain in between 2015 and 2018 to get insights into its nature, chemistry and sources. Mean (±1σ) concentration of PM2.1 was 98 (±76) μgm − 3 with a seasonal high during winter (DJF, 162 ± 71 μgm -3 ) compared to pre-monsoon specific high in PM> 2.1 (MAMJ, 177 ± 84 μgm − 3 ) with an annual mean of 170 (±69) μgm − 3 . PM2.1 was secondary in nature with abundant secondary inorganic aerosols (20% of particulate mass) and water-soluble organic carbon (19%) against metal enriched (25%) PM> 2.1, having robust signature of resuspensions from Earth's crust and road dust. Ammonium-based neutralization of particulate acidity was essentially in PM2.1 with an indication of predominant H2 SO4 neutralization in bisulfate form compared to Ca 2+ and Mg 2+ -based neutralization in PM>2.1 . Molecular distribution of n -alkanes homologues (C17 –C35 ) showed Cmax at C23 (PM2.1 ) and C18 (PM>2.1 ) with weak dominance of odd-numbered n -alkanes. Carbon preference index of n -alkanes was close to unity (PM2.1 : 1.4 ± 0.3; PM>2.1 : 1.3 ± 0.4). Fatty acids (C12 –C26 ) were characterized with predominance of even carbon with Cmax at n-hexadecanoic acid (C16:0 ). Low to high molecular weight fatty acid ratio ranged from 2.0 (PM>2.1 ) to 5.6 (PM2.1 ) with vital signature of anthropogenic emissions. Levoglucosan was abundant in PM2.1 (758 ± 481 ngm −3 ) with a high ratio (11.6) against galactosan, emphasizing robust contribution from burning of hardwood and agricultural residues. Receptor model resolves secondary aerosols and biomass burning emissions (45%) as the most influential sources of PM2.1 whereas, crustal (29%) and secondary aerosols (29%) were found responsible for PM>2.1 ; with significant variations among the seasons. Graphical abstract: Image 1 Highlights: Fine particulates were secondary in nature against metal enriched coarse particulates. Neutralization of particulate acidity varies in size-segregated particulates. Molecular distributions of organics indicate both biogenic & anthropogenic emissions. Secondary aerosols and biomass burning emissions are the dominant sources of PM2.1 . Both crustal resuspensions and secondary aerosols were responsible emitters of PM>2.1 .