Insights into size-segregated particulate chemistry and sources in urban environment over central Indo-Gangetic Plain

Document Type

Article

Publication Date

2-1-2021

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 (+/- 1 sigma) concentration of PM2.1 was 98 (+/- 76) mgm(-3) with a seasonal high during winter (DJF, 162 +/- 71 mu gm(-3)) compared to pre-monsoon specific high in PM>2.1 (MAMJ, 177 +/- 84 mgm(-3)) with an annual mean of 170 (+/- 69) mgm(-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 H2SO4 neutralization in bisulfate form compared to Ca2+ and Mg2+-based neutralization in PM>2.1. Molecular distribution of n-alkanes homologues (C-17-C-35) showed C-max at C-23 (PM2.1) and C-18 (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 (C-16:0). 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. (C) 2020 Elsevier Ltd. All rights reserved.

Keywords

Aerosols, Levoglucosan, Organics, Receptor model, Secondary aerosols

Publication Title

Chemosphere

Divisions

Science

Funders

Science and Engineering Research Board, Department of Science and Technology, New Delhi[SR/FTP/ES-52/2014],ASEAN- India S&T Development Fund, Govt. of India under ASEAN- India Collaborative Research and Development Scheme[CRD/2018/000011],Department of Science & Technology (India)[SR/WOS-A/EA-1012/2015],VSSC, Indian Space Research Organization[R&D/SA/ISRO/ChE/19/2006]

Volume

263

Publisher

Elsevier

Publisher Location

THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND

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